Analysis of the Effects of Streamwise Lift Distribution on Sonic Boom Signature
Yoo, Paul
2013-01-01
Investigation of sonic boom has been one of the major areas of study in aeronautics due to the benefits a low-boom aircraft has in both civilian and military applications. This work conducts a numerical analysis of the effects of streamwise lift distribution on the shock coalescence characteristics. A simple wing-canard-stabilator body model is used in the numerical simulation. The streamwise lift distribution is varied by fixing the canard at a deflection angle while trimming the aircraft with the wing and the stabilator at the desired lift coefficient. The lift and the pitching moment coefficients are computed using the Missile DATCOM v. 707. The flow field around the wing-canard- stabilator body model is resolved using the OVERFLOW-2 flow solver. Overset/ chimera grid topology is used to simplify the grid generation of various configurations representing different streamwise lift distributions. The numerical simulations are performed without viscosity unless it is required for numerical stability. All configurations are simulated at Mach 1.4, angle-of-attack of 1.50, lift coefficient of 0.05, and pitching moment coefficient of approximately 0. Four streamwise lift distribution configurations were tested.
Stream-wise distribution of skin-friction drag reduction on a flat plate with bubble injection
Qin, Shijie; Chu, Ning; Yao, Yan; Liu, Jingting; Huang, Bin; Wu, Dazhuan
2017-03-01
To investigate the stream-wise distribution of skin-friction drag reduction on a flat plate with bubble injection, both experiments and simulations of bubble drag reduction (BDR) have been conducted in this paper. Drag reductions at various flow speeds and air injection rates have been tested in cavitation tunnel experiments. Visualization of bubble flow pattern is implemented synchronously. The computational fluid dynamics (CFD) method, in the framework of Eulerian-Eulerian two fluid modeling, coupled with population balance model (PBM) is used to simulate the bubbly flow along the flat plate. A wide range of bubble sizes considering bubble breakup and coalescence is modeled based on experimental bubble distribution images. Drag and lift forces are fully modeled based on applicable closure models. Both predicted drag reductions and bubble distributions are in reasonable concordance with experimental results. Stream-wise distribution of BDR is revealed based on CFD-PBM numerical results. In particular, four distinct regions with different BDR characteristics are first identified and discussed in this study. Thresholds between regions are extracted and discussed. And it is highly necessary to fully understand the stream-wise distribution of BDR in order to establish a universal scaling law. Moreover, mechanism of stream-wise distribution of BDR is analysed based on the near-wall flow parameters. The local drag reduction is a direct result of near-wall max void fraction. And the near-wall velocity gradient modified by the presence of bubbles is considered as another important factor for bubble drag reduction.
Jing Fan; Chong Xie; Jianzheng Jiang
2007-01-01
Measured mass flow rates and streamwise pressure distributions of gas flowing through microchannels were reported by many researchers. Assessment of these data is crucial before they are used in the examination of slip models and numerical schemes, and in the design of microchannel elements in various MEMS devices. On the basis of kinetic solutions of the mass flow rates and pressure distributions in microchannel gas flows, the measured data available are properly normalized and then are compared with each other. The 69 normalized data of measured pressure distributions are in excellent agreement, and 67 of them are within 1 ± 0.05. The normalized data of mass flow-rates ranging between 0.95 and 1 agree well with each other as the inlet Knudsen number Kni ＞ 0.02, but they scat ter between 0.85 and 1.15 as Kni ＜ 0.02 with, to some extent, a very interesting bifurcation trend.
KNIGHT; Donald; W
2009-01-01
Natural rivers are commonly characterized by a main channel for primary flow conveyance and a floodplain, often partially covered with vegetation such as shrubs or trees, to carry extra flow during floods. The hydraulic resistance due to vegetation on the floodplain typically causes a further reduction of flow velocity and increases the velocity difference between the main channel and the floodplain. As a consequence a strong lateral shear layer leads to the exchange of mass and momentum between the main channel and floodplain, which in turn affects the overall channel conveyance and certain fluvial processes. The prediction of the lateral velocity distribution is important for many flood alleviation schemes, as well as for studies on sediment transport and dispersion in such channels. The present paper proposes a method for predicting the depth-averaged velocity in compound channels with partially vegetated floodplains, based on an analytical solution to the depth-integrated Reynolds-Averaged Navier-Stokes equation with a term included to account for the effects of vegetation. The vegetation is modelled via an additional term in the momentum equation to account for the additional drag force. The method includes the effects of bed friction, drag force, lateral turbulence and secondary flows, via four coefficients f, CD, λ & Γ respectively. The predicted lateral distributions of depth-averaged velocity agree well with the experimental data. The analytical solutions can also be used to predict the distribution of boundary shear stresses, which adds additional weight to the method proposed.
TANG XiaoNan; KNIGHT Donald W
2009-01-01
Natural rivers are commonly characterized by a main channel for primary flow conveyance and a floodplain, often partially covered with vegetation such as shrubs or trees, to carry extra flow during floods.The hydraulic resistance due to vegetation on the floodplain typically causes a further reduction of flow velocity and increases the velocity difference between the main channel and the floodplain.As a consequence a strong lateral shear layer leads to the exchange of mass and momentum between the main channel and floodplain, which in turn affects the overall channel conveyance and certain fluvial processes.The prediction of the lateral velocity distribution is important for many flood alleviation schemes, as well as for studies on sediment transport and dispersion in such channels.The present paper proposes a method for predicting the depth-averaged velocity in compound channels with par-tially vegetated floodplains, based on an analytical solution to the depth-integrated Reynolds-Averaged Navier-Stokes equation with a term included to account for the effects of vegetation.The vegetation is modelled via an additional term in the momentum equation to account for the additional drag force.The method includes the effects of bed friction, drag force, lateral turbulence and secondary flows, via four coefficients f, C_D,λ & Г respectively.The predicted lateral distributions of depth-averaged velocity agree well with the experimental data.The analytical solutions can also be used to predict the distribu-tion of boundary shear stresses, which adds additional weight to the method proposed.
Analysis of a distributed system for lifting trucks
Groote, J.F.; Pang, J.; Wouters, A.G.
2001-01-01
The process-algebraic language muCRL is used to analyse an existing distributed system for lifting trucks. Four errors are found in the original design. We propose solutions for these problems and show by means of model-checking that the modified system meets the requirements.
COMPRESSIBILITY EFFECTS ON DISTRIBUTIONS OF PRESSURE AND LIFT COEFFICIENTS
AZZEDINE NAHOUI
2015-06-01
Full Text Available Reduce energy consumption of airplanes, or enhance the aerodynamic performance of compressors and turbines by reducing drag, or increasing lift is a major challenge for many institutions specializing in aerodynamics [1, 2]. One way to achievethis, isconsidered the study of compressible potential flow compared to incompressible potential flow [3], Outside the boundary layer, to study the effects of compressibility and the control parameters. And the pressure coefficient and lift distributions around the NACA 0012 profile, NACA 0015 and NACA 0018 were studied and presented in terms of the Mach number, angle of attack and the relative thickness of the profiles.
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.
Patterson, Michael D.; Derlaga, Joseph M.; Borer, Nicholas K.
2016-01-01
Although the primary function of propellers is typically to produce thrust, aircraft equipped with distributed electric propulsion (DEP) may utilize propellers whose main purpose is to act as a form of high-lift device. These \\high-lift propellers" can be placed upstream of wing such that, when the higher-velocity ow in the propellers' slipstreams interacts with the wing, the lift is increased. This technique is a main design feature of a new NASA advanced design project called Scalable Convergent Electric Propulsion Technology Operations Research (SCEPTOR). The goal of the SCEPTOR project is design, build, and y a DEP aircraft to demonstrate that such an aircraft can be much more ecient than conventional designs. This paper provides details into the high-lift propeller system con guration selection for the SCEPTOR ight demonstrator. The methods used in the high-lift propeller system conceptual design and the tradeo s considered in selecting the number of propellers are discussed.
Flow pattern and lift evolution of hydrofoil with control of electro-magnetic forces
无
2009-01-01
The initial responses and evolutions of the flow pattern and lift coefficient of a hydrofoil under the action of electro-magnetic (Lorentz) force have been studied experimentally and numerically, and trace particle methods are employed for them. With the introduction of BVF (boundary vortex flux), the quantitative relation among Lorentz forces, BVF and lifts is deduced. The influences of flow patterns on the hydrofoil lift coefficient have been discussed based on the BVF distribution, and the flow control mechanism of Lorentz force for a hydrofoil has been elucidated. Our results show that the flow pattern and lift of the hydrofoil vary periodically without any force. However, with the action of streamwise Lorentz forces, the separation point on the hydrofoil surface moves backward with a certain velocity, which makes the flow field steady finally. The streamwise Lorentz force raises the foil lift due to the increase of BVF intensity. On the other hand, Lorentz force also increases the hydrofoil surface pressure, which makes the lift decrease. However, the factor leading to the lift enhancement is determinant, therefore, the Lorentz force on the suction side can increase the lift, and the stronger the Lorentz force, the larger the lift enhancement. Our results also show that the localized Lorentz force can also both suppress the flow separation and increase the hydrofoil lift coefficient, furthermore, the Lorentz force located on the tail acts better than that located on the front.
Medan, R. T.; Ray, K. S.
1974-01-01
A description of and users manual are presented for a U.S.A. FORTRAN 4 computer program which evaluates spanwise and chordwise loading distributions, lift coefficient, pitching moment coefficient, and other stability derivatives for thin wings in linearized, steady, subsonic flow. The program is based on a kernel function method lifting surface theory and is applicable to a large class of planforms including asymmetrical ones and ones with mixed straight and curved edges.
Streamwise Vortex Interaction with a Horseshoe Vortex
Piotr Doerffer; Pawel Flaszynski; Franco Magagnato
2003-01-01
Flow control in turbomachinery is very difficult because of the complexity of its fully 3-D flow structure. The authors propose to introduce streamwise vortices into the control of internal flows. A simple configuration of vortices was investigated in order to better understand the flow control methods by means of streamwise vortices.The research presented here concerns streamwise vortex interaction with a horseshoe vortex. The effects of such an interaction are significantly dependent on the relative location of the streamwise vortex in respect to the leading edge of the profile. The streamwise vortex is induced by an air jet. The horseshoe vortex is generated by the leading edge of a symmetric profile. Such a configuration gives possibility to investigate the interaction of these two vortices alone. The presented analysis is based on numerical simulations by means of N-S compressible solver with a two-equation turbulence model.
High-Lift Propeller Noise Prediction for a Distributed Electric Propulsion Flight Demonstrator
Nark, Douglas M.; Buning, Pieter G.; Jones, William T.; Derlaga, Joseph M.
2017-01-01
Over the past several years, the use of electric propulsion technologies within aircraft design has received increased attention. The characteristics of electric propulsion systems open up new areas of the aircraft design space, such as the use of distributed electric propulsion (DEP). In this approach, electric motors are placed in many different locations to achieve increased efficiency through integration of the propulsion system with the airframe. Under a project called Scalable Convergent Electric Propulsion Technology Operations Research (SCEPTOR), NASA is designing a flight demonstrator aircraft that employs many "high-lift propellers" distributed upstream of the wing leading edge and two cruise propellers (one at each wingtip). As the high-lift propellers are operational at low flight speeds (take-off/approach flight conditions), the impact of the DEP configuration on the aircraft noise signature is also an important design consideration. This paper describes efforts toward the development of a mulit-fidelity aerodynamic and acoustic methodology for DEP high-lift propeller aeroacoustic modeling. Specifically, the PAS, OVERFLOW 2, and FUN3D codes are used to predict the aerodynamic performance of a baseline high-lift propeller blade set. Blade surface pressure results from the aerodynamic predictions are then used with PSU-WOPWOP and the F1A module of the NASA second generation Aircraft NOise Prediction Program to predict the isolated high-lift propeller noise source. Comparisons of predictions indicate that general trends related to angle of attack effects at the blade passage frequency are captured well with the various codes. Results for higher harmonics of the blade passage frequency appear consistent for the CFD based methods. Conversely, evidence of the need for a study of the effects of increased azimuthal grid resolution on the PAS based results is indicated and will be pursued in future work. Overall, the results indicate that the computational
The Circulation Distribution on the Lifting Line for a Given Extracted Power
Ali Helali
2012-01-01
Full Text Available Presently, there exist few numerical methods which treat the inverse problem for the determination of the geometry of wind turbine blades. In this work, authors intend to solve the inverse optimum project for horizontal axis wind turbine in which the selection of the circulation distribution is obtained by resolving two variational problems: the first consists in sorting the circulation distribution on the lifting line, which, for a given power extracted by the wind turbine, minimizes the loses due to the induced velocity. In the second, the optimal circulation distribution is selected such that the kinetic energy of the wind downstream of the rotor disc is minimum, when the energy extracted by the wind turbine for one rotating period is imposed. A code has been developed which incorporates the real pitch of the helicoidal vortex wake. Very promising results have been obtained: the circulation distribution for a given extracted power and the chord lengths distribution law along the blade span.
Flow pattern and lift evolution of hydrofoil with control of electro-magnetic forces
CHEN YaoHui; FAN BaoChun; CHEN ZhiHua; LI HongZhi
2009-01-01
The Initial responses and evolutions of the flow pattern and lift coefficient of a hydrofoil under the ac-tion of electro-magnetic (Lorentz) force have been studied experimentally and numerically,and trace particle methods are employed for them.With the introduction of BVF (boundary vortex flux),the quantitative relation among Lorentz forces,BVF and lifts is deduced.The influences of flow patterns on the hydrofoil lift coefficient have been discussed based on the BVF distribution,and the flow control mechanism of Lorentz force for a hydrofoil has been elucidated.Our results show that the flow pattern and lift of the hydrofoil vary periodically without any force.However,with the action of streamwise Lorentz forces,the separation point on the hydrofoil surface moves backward with a certain velocity,which makes the flow field steady finally.The streamwise Lorentz force raises the foil lift due to the Increase of BVF intensity.On the other hand,Lorentz force also increases the hydrofoil surface pres-sure,which makes the lift decrease.However,the factor leading to the lift enhancement is determinant,therefore,the Lorentz force on the suction side can increase the lift,and the stronger the Lorentz force,the larger the lift enhancement.Our results also show that the localized Lorentz force can also both suppress the flow separation and increase the hydrofoil lift coefficient,furthermore,the Lorentz force located on the tail acts better than that located on the front.
Streamwise-body-force-model for rapid simulation combining internal and external flow fields
Cui Rong
2016-10-01
Full Text Available A streamwise-body-force-model (SBFM is developed and applied in the overall flow simulation for the distributed propulsion system, combining internal and external flow fields. In view of axial stage effects, fan or compressor effects could be simplified as body forces along the streamline. These body forces which are functions of local parameters could be added as source terms in Navier-Stokes equations to replace solid boundary conditions of blades and hubs. The validation of SBFM with uniform inlet and distortion inlet of compressors shows that pressure performance characteristics agree well with experimental data. A three-dimensional simulation of the integration configuration, via a blended wing body aircraft with a distributed propulsion system using the SBFM, has been completed. Lift coefficient and drag coefficient agree well with wind tunnel test results. Results show that to reach the goal of rapid integrated simulation combining internal and external flow fields, the computational fluid dynamics method based on SBFM is reasonable.
Heat transfer with very high free-stream turbulence and streamwise vortices
Moffat, Robert J.; Maciejewski, Paul; Eaton, John K.; Pauley, Wayne
1986-01-01
Results are presented for two experimental programs related to augmentation of heat transfer by complex flow characteristics. In one program, high free stream turbulence (up to 63 percent) was shown to increase the Stanton number by more than a factor of 5, compared with the normally expected value based on x-Reynolds number. These experiments are being conducted in a free-jet facility, near the margins of the jet. To a limited extent, the mean velocity, turbulence intensity, and integral length scale can be separately varied. The results show that scale is a very important factor in determining the augmentation. Detailed studies of the turbulence structure are being carried out using an orthogonal triple hot-wire anemometer equipped with a fourth wire for measuring temperature. The v' component of turbulence appears to be distributed differently from u' or w'. In the second program, the velocity distributions and boundary layer thicknesses associated with a pair of counter-rotating, streamwise vortices were measured. There is a region of considerably thinned boundary layer between the two vortices when they are of approximately the same strength. If one vortex is much stronger than the other, the weaker vortex may be lifted off the surface and absorbed into the stronger.
Peak-Seeking Optimization of Spanwise Lift Distribution for Wings in Formation Flight
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.
On generating counter-rotating streamwise vortices
Winoto, S H
2015-09-23
Counter-rotating streamwise vortices are known to enhance the heat transfer rate from a surface and also to improve the aerodynamic performance of an aerofoil. In this paper, some methods to generate such counter-rotating vortices using different methods or physical conditions will be briefly considered and discussed.
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Annoyance to Noise Produced by a Distributed Electric Propulsion High-Lift System
Rizzi, Stephen A.; Palumbo, Daniel L.; Rathsam, Jonathan; Christian, Andrew; Rafaelof, Menachem
2017-01-01
A psychoacoustic test was performed using simulated sounds from a distributed electric propulsion aircraft concept to help understand factors associated with human annoyance. A design space spanning the number of high-lift leading edge propellers and their relative operating speeds, inclusive of time varying effects associated with motor controller error and atmospheric turbulence, was considered. It was found that the mean annoyance response varies in a statistically significant manner with the number of propellers and with the inclusion of time varying effects, but does not differ significantly with the relative RPM between propellers. An annoyance model was developed, inclusive of confidence intervals, using the noise metrics of loudness, roughness, and tonality as predictors.
Analysis of streamwise-oriented vortex interactions for two wings in close proximity
Barnes, Caleb J.; Visbal, Miguel R.; Gordnier, Raymond E.
2015-01-01
This investigation addresses the impingement of the trailing vortex provided by a leader-wing upon a follower-wing operating in close proximity. Exploration of the relative spacing between the two wings reveals several distinct flow regimes occur within a small range of lateral positions of the incident vortex. These changes effectively alter the evolution of the follower-wing wake via mutual induction between the incident and trailing vortices. Several unsteady mechanisms impact the general flow field in each regime. The incident vortex for an inboard impingement rapidly decays over the wing due to transition to turbulence. A tip-aligned vortex results in a highly unsteady interaction and generates enhanced surface pressure fluctuations beneath the tip vortex. Placing the incident vortex outboard elicits mutual instability between the leader and follower-wing trailing vortices. While lift-enhancement was found to be dominated by an inviscid increase in effective angle of attack, viscous effects in the near-tip region alter the local surface force distribution and influence the rolling moment coefficient. These flow variations which occur over a small range of lateral positions could generate buffeting loads in the presence of a wandering streamwise vortex.
Formation Flight: Upstream Influence of a Wing on a Streamwise Vortex
McKenna, Chris; Rockwell, Donald; Lehigh University Fluids Lab Team
2015-11-01
Aircraft flying together in formation can experience aerodynamic advantages. Impingement of the tip vortex of the leader wing on the trailer wing can increase the lift to drag ratio L/D and the unsteady loading on the trailer wing. These increases are sensitive to the impingement location of the vortex on the wing. Particle image velocimetry is employed to determine patterns of velocity and vorticity on successive crossflow planes along the vortex, which lead to volume representations and thereby characterization of the streamwise evolution of the vortex structure as it approaches the trailer wing. This evolution of the incident vortex is affected by the upstream influence of the trailer wing, and is highly dependent on the location of vortex impingement. As the spanwise impingement location of the vortex moves from outboard of the wing tip to inboard, the upstream influence on the development of the vortex increases. For spanwise locations close to or intersecting the vortex core, the effects of upstream influence of the wing on the vortex are to: increase the streamwise velocity deficit; decrease the streamwise vorticity; increase the in-plane vorticity; decrease the downwash; and increase the root-mean-square of both streamwise velocity and vorticity.
Spanwise lift distributions and wake velocity surveys of a semi-span wing with a discontinuous twist
Kumagai, Hiroyuki
1989-01-01
A wind tunnel test was conducted in the NASA-Ames 7 x 10 ft wind tunnel to investigate the lift distribution on a semispan wing with a discontinuous change in spanwise twist. The semispan wing had a tip with an adjustable pitch angle independent on the inboard section pitch angle simulating the free tip rotor blade when its free tip is at a deflected position. The spanwise lift distribution over the wing and the tip were measured and three component velocity surveys behind the wing were obtained with a 3-D laser Doppler velocimeter (LV) with the wing at one angle of attack and the tip deflected at different pitch angles. A six-component internal strain gage balance was also used to measure total forces and moments on the tip. The 3-D lift was computed from the 2-D lift distributions obtained from the LV and from the strain gage balance. The results from both experimental methods are shown to be in agreement with predictions made by a steady, 3-D panel code, VSAERO.
Berrino, M.; Satta, F.; Simoni, D.; Ubaldi, M.; Zunino, P.; Bertini, F.
2014-02-01
The present paper reports the results of an experimental investigation aimed at comparing aerodynamic performance of three low-pressure turbine cascades for several Reynolds numbers under steady and unsteady inflows. This study is focused on finding design criteria useful to reduce both profile and secondary losses in the aero-engine LP turbine for the different flight conditions. The baseline blade cascade, characterized by a standard aerodynamic loading (Zw=1.03), has been compared with two Ultra-High-Lift profiles with the same Zweifel number (Zw=1.3 for both cascades), but different velocity peak positions, leading to front and mid-loaded blade cascade configurations. The aerodynamic flow fields downstream of the cascades have been experimentally investigated for Reynolds numbers in the range 70000plane downstream of the cascade for both inflow conditions. The analysis of the results allows the evaluation of the aerodynamic performance of the blade cascades in terms of profile and secondary losses and the understanding of the effects of loading distribution and Zweifel number on secondary flows. When operating under unsteady inflow, contrarily to the steady case, the mid-loaded cascade has been found to be characterized by the lowest profile and secondary losses, making it the most attractive solution for the design of blades working in real conditions where unsteady inflow effects are present.
Analysis of streamwise conduction in forced convection of microchannels using fin approach
Suhandran MUNIANDY; Yew Mun HUNG
2011-01-01
The effects induced by streamwise conduction on the thermal characteristics of forced convection for single-phase liquid flow in rectangular microchannel heat sinks under imposed constant wall temperature have been studied.By employing the fin approach in the first law of analysis,models with and without streamwise conduction term in the energy equation were developed for hydrodynamically and thermally fully-developed flow under local thermal non-equilibrium for the solid and fluid phases.These two models were solved to obtain closed form analytical solutions for the fluid and solid temperature distributions and the analysis emphasized details of the variations induced by the streamwise conduction on the fluid temperature distributions.The effects of the Peclet number,aspect ratio,and thermal conductivity ratio on the thermal characteristics of forced convection in microchannel heat sinks were analyzed and discussed.This study reveals the conditions under which the effect of streamwise conduction is significant and should not be neglected in the forced convective heat transfer analysis ofmicrochannel heat sinks.
Laminar streak enhancement using streamwise grooves
Martel, Carlos; Martín, Juan Ángel
2011-11-01
Laminar streak promotion in a flat plate boundary layer results in an increase of the stability of the Tollmien-Schlichting waves with respect to that of the 2D Blasius profile. This stabilization delays the laminar-turbulent transition, increasing the laminar phase of the flow. The stabilization effect is stronger for higher streak amplitudes, and therefore simple ways of generating high amplitude stable streaks are sought to be used as boundary layer flow control methods. In a recent experiment [Tallamelli & Franson,AIAA 2010-4291] high amplitude stable steady streaks have been produced using Miniature Vortex Generators (MGVs), where one array of MGVs is used to excite the streak and a second array is used downstream to enhance their amplitude. In this presentation we numerically explore the possibility of enhancing the streaks using a different passive mechanism: streamwise grooves carved in the plate. We will present some numerical simulations for different values of the spanwise period of the streaks and of the grooves, and we will show the combinations that provide maximum streak amplitude.
Ivanchin, Alexander
2010-01-01
It is shown that one of the causes for tornado is Tornado Lift. At increasing vortex diameter its kinetic energy decreases to keep the moment of momentum constant. A kinetic energy gradient of such vortex is Tornado Lift. Evaluation shows that contribution of Tornado Lift in air lifting in a tornado is comparable to buoyancy according to the order of magnitude.
Lifting operations and lifting equipment
Douwes, M.
2013-01-01
Lifting operations are inherent to many occupations in the construction industry. They can be performed manually or using lifting equipment. Both manual lifting and mechanical lifting operations can put construction workers at great risk of injury or health symptoms causing sick leave or disability.
A streamwise constant model of turbulence in plane Couette flow
Gayme, D. F.; McKeon, B. J.; Papachristodoulou, A.; Bamieh, B; Doyle, J. C.
2010-01-01
Streamwise and quasi-streamwise elongated structures have been shown to play a significant role in turbulent shear flows. We model the mean behaviour of fully turbulent plane Couette flow using a streamwise constant projection of the Navier–Stokes equations. This results in a two-dimensional three-velocity-component (2D/3C) model. We first use a steady-state version of the model to demonstrate that its nonlinear coupling provides the mathematical mechanism that shapes the turbulent velocity p...
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A Streamwise Constant Model of Turbulence in Plane Couette Flow
Gayme, D F; Papachristodoulou, A; Bamieh, B; Doyle, J C
2010-01-01
There is a consensus that turbulent flow is characterized by coherent structures. In particular, streamwise and quasi-streamwise elongated structures have been observed in both numerical simulations and experiments. Using this idea the mean behavior of fully turbulent plane Couette flow is modeled using a streamwise constant projection of the Navier Stokes equations. This assumption results in a two dimensional, three velocity component (2D/3C) model. We first use a steady state version of this 2D/3C model to demonstrate that the nonlinear coupling in the equations provides the mathematical mechanisms associated with the shape of the turbulent velocity profile. In simulating the full model we borrow some ideas from robust control and represent uncertainty as well as modeling errors using small amplitude noise forcing. Simulations of the 2D/3C model under small amplitude Gaussian forcing of the cross stream components is compared to DNS data. The results indicate that a streamwise constant projection of the Na...
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Steady streamwise transpiration control in turbulent pipe flow
Gómez, F; Rudman, M; Sharma, AS; McKeon, BJ
2016-01-01
A study of the the main features of low- and high amplitude steady streamwise wall transpiration applied to pipe flow is presented. The effect of the two transpiration parameters, amplitude and wavenumber, on the flow have been investigated by means of direct numerical simulation at a moderate turbulent Reynolds number. The behaviour of the three identified mechanisms that act in the flow: modification of Reynolds shear stress, steady streaming and generation of non-zero mean streamwise gradients, have been linked to the transpiration parameters. The observed trends have permitted the identification of wall transpiration configurations able to reduce or increase the overall flow rate in -36.1% and 19.3% respectively. A resolvent analysis has been carried out to obtain a description of the reorganization of the flow structures induced by the transpiration.
Effects of streamwise vortex breakdown on supersonic combustion.
Hiejima, Toshihiko
2016-04-01
This paper presents a numerical simulation study of the combustion structure of streamwise vortex breakdown at Mach number 2.48. Hydrogen fuel is injected into a combustor at sonic speed from the rear of a hypermixer strut that can generate streamwise vortices. The results show that the burning behavior is enhanced at the points of the shock waves that are incident on the vortex and therefore the vortex breakdown in the subsonic region occurs due to combustion. The breakdown domain in the mainstream is found to form a flame-holding region suited to combustion and to lead to a stable combustion field with detached flames. In this way, streamwise vortex breakdown has an essential role in combustion enhancement and the formation of flames that hold under supersonic inflow conditions. Finally, the combustion property defined here is shown to coincide with the produced-water mass flow. This property shows that the amount of combustion is saturated at equivalence ratios over 0.4, although there is a slight increase beyond 1.
Blade Sections in Streamwise Oscillations into Reverse Flow
2015-05-07
blade surges into the freestream and dropping to near zero as the blade retreats. At this high angle of attack, however, maxi - mum lift no longer lags...progresses, stronger viscous effects might cause precipitation of deep stall, a weak - ening of bound circulation, and a drop in lift ahead of the drop
Effect of streamwise vortices on Tollmien-Schlichting waves
Nayfeh, A. H.
1981-01-01
The method of multiple scales is used to determine a first-order uniform expansion for the effect of counter-rotating steady streamwise vortices in growing boundary layers on oblique Tollmien-Schlichting waves. The results show that such vortices have a strong tendency to amplify oblique Tollmien-Schlichting waves having a spanwise wavelength that is twice the wavelength of the vortices. An analytical expression is derived for the growth rates of these waves. These exponential growth rates increase linearly with increasing amplitudes of the vortices. Numerical results are presented. They suggest that this mechanism may dominate the instability.
Shock Wave Induced Separation Control by Streamwise Vortices
Ryszard SZWABA
2005-01-01
Control of shock wave and boundary layer interaction finds still a lot of attention. Methods of this interaction control have been especially investigated in recent decade. This research was mostly concerned with flows without separation. However, in many applications shock waves induce separation often leads to strong unsteady effects. In this context it is proposed to use streamwise vortices for the interaction control. The results of experimental investigations are presented here. The very promising results were obtained, meaning that the incipient separation was postponed and the separation size was reduced for the higher Mach numbers. The decrease of the RMS of average shock wave oscillation was also achieved.
Interaction of Streamwise and Wall-Normal Velocities in Combined Wave-Current Motion
Shu-Qing YANG; In-Soo KIM; Daniel S. KOH; Young-Chae SONG
2005-01-01
The aim of this paper is to present an analytical expression for the streamwise velocity distribution in a non-uniform flow in the presence of waves; the correlation between the horizontal and vertical velocity components has been comprehensively examined. Different from previous researches which attributed the deviation of velocity from the classical log-law to the wave Reynolds stress, i.e. -ρ(uv)only, this study demonstrates that the momentum flux caused by mean velocities, i.e.,(u)and(v) , is also responsible for the velocity deviation, and it is found that the streamwise velocity for a flow in the presence of non-zero wall-normal velocity does not follow the classical log-law, but the modified log-law proposed in this study based on simplified mixing-length theorem. The validity of the modified log-law has been verified by use of available experimental data from published sources for combined wave-current flows, and good agreement between the predicted and observed velocity profiles has been achieved.
Schobeiri, M. T.; John, J.
1996-01-01
The turbomachinery wake flow development is largely influenced by streamline curvature and streamwise pressure gradient. The objective of this investigation is to study the development of the wake under the influence of streamline curvature and streamwise pressure gradient. The experimental investigation is carried out in two phases. The first phase involves the study of the wake behind a stationary circular cylinder (steady wake) in curved channels at positive, zero, and negative streamwise pressure gradients. The mean velocity and Reynolds stress components are measured using a X-hot-film probe. The measured quantities obtained in probe coordinates are transformed to a curvilinear coordinate system along the wake centerline and are presented in similarity coordinates. The results of the steady wakes suggest strong asymmetry in velocity and Reynolds stress components. However, the velocity defect profiles in similarity coordinates are almost symmetrical and follow the same distribution as the zero pressure gradient straight wake. The results of Reynolds stress distributions show higher values on the inner side of the wake than the outer side. Other quantities, including the decay of maximum velocity defect, growth of wake width, and wake integral parameters, are also presented for the three different pressure gradient cases of steady wake. The decay rate of velocity defect is fastest for the negative streamwise pressure gradient case and slowest for the positive pressure gradient case. Conversely, the growth of the wake width is fastest for the positive streamwise pressure gradient case and slowest for the negative streamwise pressure gradient. The second phase studies the development of periodic unsteady wakes generated by the circular cylinders of the rotating wake generator in a curved channel at zero streamwise pressure gradient. Instantaneous velocity components of the periodic unsteady wakes, measured with a stationary X-hot-film probe, are analyzed by the
Formation Flight: Modes of Interaction of a Streamwise Vortex with a Wing
McKenna, Chris; Bross, Matthew; Rockwell, Donald
2014-11-01
Aircraft flying together in an echelon or V formation experience aerodynamic advantages. Impingement of the tip vortex of the leader (upstream) wing on the follower wing can yield an increase of lift to drag ratio. This enhancement is known to be sensitive to the location of vortex impingement on the follower wing. Particle image velocimetry is employed to determine patterns of velocity and vorticity in successive crossflow planes, which characterize the streamwise evolution of the vortex structure along the chord of the follower wing and into its wake. Different modes of vortex-follower wing interaction are created by varying the spanwise location of the leader wing. These modes are defined by differences in the development of, and interaction between, the incident tip vortex from the leader wing and the tip vortex along the follower wing. Modes of development/interaction of the tip vortices include bifurcation, attenuation, and mutual induction. The bifurcation and attenuation modes decrease the strength of the follower tip vortex. In contrast, the mutual induction mode increases the strength of the follower tip vortex.
Linear and Nonlinear Evolution of Disturbances in Supersonic Streamwise Vortices
Khorrami, Mehdi R.; Chang, Chau-Lyan; Wie, Yong-Sun
1997-11-01
Effective control of compressible streamwise vortices play a significant role in both external and internal aerodynamics. In this study, evolution of disturbances in a supersonic vortex is studied by using quasi-cylindrical linear stability analysis and parabolized stability equations (PSE)footnote M. R. Malik and C.-L. Chang, AIAA Paper 97-0758. formulation. Appropriate mean-flow profilesfootnote M. K. Smart, I. M. Kalkhoran, and J. Bentson, AIAA Paper 94-2576. suitable for stability analysis were identified and modeled successfully. Using linear stability analysis, the stability characteristics of axisymmetric vortices were mapped thoroughly. The results indicate that viscosity has very little effect while increasing Mach number significantly stabilizes the disturbance. Linear PSE analysis shows that the effect of streamwise mean flow variation is small for the case considered here. Nonlinear evolution of helical modes is also studied by using PSE. The growth of the disturbances results in the appearance of coherent large scale motion and significant mean flow distortion in the axial velocity and temperature fields. In the end, nonlinear effects tend to stabilize the vortex.
Rostamzadeh, N.; Hansen, K. L.; Kelso, R. M.; Dally, B. B.
2014-10-01
Wings with tubercles have been shown to display advantageous loading behavior at high attack angles compared to their unmodified counterparts. In an earlier study by the authors, it was shown that an undulating leading-edge configuration, including but not limited to a tubercled model, induces a cyclic variation in circulation along the span that gives rise to the formation of counter-rotating streamwise vortices. While the aerodynamic benefits of full-span tubercled wings have been associated with the presence of such vortices, their formation mechanism and influence on wing performance are still in question. In the present work, experimental and numerical tests were conducted to further investigate the effect of tubercles on the flow structure over full-span modified wings based on the NACA 0021 profile, in the transitional flow regime. It is found that a skew-induced mechanism accounts for the formation of streamwise vortices whose development is accompanied by flow separation in delta-shaped regions near the trailing edge. The presence of vortices is detrimental to the performance of full-span wings pre-stall, however renders benefits post-stall as demonstrated by wind tunnel pressure measurement tests. Finally, primary and secondary vortices are identified post-stall that produce an enhanced momentum transfer effect that reduces flow separation, thus increasing the generated amount of lift.
EXPERIMENTAL STUDY ON TURBULENT BOUNDARY LAYER CHARACTERISTICS OVER STREAMWISE RIBLETS
ZHAO Zhi-yong; DONG Shou-ping; DU Ya-nan
2004-01-01
Measurements of characteristics by means of a two-component Laser Doppler Velocimeter (LDV) were carried out in turbulent boundary layers over both a symmetric V-shaped ribbed plate and a smooth one in a low speed wind tunnel. The present results clearly indicate that the logarithmic velocity profile over the riblets surface is shifted upward with a 30.9% increase in the thickness of the viscous sublayer. Also a change in the log-law region is found. And the maximum value of streamwise velocity fluctuations is reduced by approximately 17%. The skewness and flatness factors do not show any change besides those in the region of y+＜0.6. It is evident that the Reynolds shear stress over the riblets is reduced. Further more, in log-law region, the Reynolds shear stress has a larger reduction of up to 18%.
Streamwise decay of localized states in channel flow
Zammert, Stefan
2016-01-01
Channel flow, the pressure driven flow between parallel plates, has exact coherent structures that show various degrees of localization. For states which are localized in streamwise direction but extended in spanwise direction, we show that they are exponentially localized, with decay constants that are different on the upstream and downstream side. We extend the analysis of Brand and Gibson, J. Fluid Mech. 750, R1 (2014), for stationary states to the case of advected structures that is needed here, and derive expressions for the decay in terms of eigenvalues and eigenfunctions of certain second order differential equations. The results are in very good agreement with observations on exact coherent structures of different transversal wave length.
Lift enhancement by trapped vortex
Rossow, Vernon J.
1992-01-01
The viewgraphs and discussion of lift enhancement by trapped vortex are provided. Efforts are continuously being made to find simple ways to convert wings of aircraft from an efficient cruise configuration to one that develops the high lift needed during landing and takeoff. The high-lift configurations studied here consist of conventional airfoils with a trapped vortex over the upper surface. The vortex is trapped by one or two vertical fences that serve as barriers to the oncoming stream and as reflection planes for the vortex and the sink that form a separation bubble on top of the airfoil. Since the full three-dimensional unsteady flow problem over the wing of an aircraft is so complicated that it is hard to get an understanding of the principles that govern the vortex trapping process, the analysis is restricted here to the flow field illustrated in the first slide. It is assumed that the flow field between the two end plates approximates a streamwise strip of the flow over a wing. The flow between the endplates and about the airfoil consists of a spanwise vortex located between the suction orifices in the endplates. The spanwise fence or spoiler located near the nose of the airfoil serves to form a separated flow region and a shear layer. The vorticity in the shear layer is concentrated into the vortex by withdrawal of fluid at the suction orifices. As the strength of the vortex increases with time, it eventually dominates the flow in the separated region so that a shear or vertical layer is no longer shed from the tip of the fence. At that point, the vortex strength is fixed and its location is such that all of the velocity contributions at its center sum to zero thereby making it an equilibrium point for the vortex. The results of a theoretical analysis of such an idealized flow field are described.
Pesetskaya, N. N.; Timofeev, I. YA.; Shipilov, S. D.
1988-01-01
In recent years much attention has been given to the development of methods and programs for the calculation of the aerodynamic characteristics of multiblade, saber-shaped air propellers. Most existing methods are based on the theory of lifting lines. Elsewhere, the theory of a lifting surface is used to calculate screw and lifting propellers. In this work, methods of discrete eddies are described for the calculation of the aerodynamic characteristics of propellers using the linear and nonlinear theories of lifting surfaces.
Pesetskaya, N. N.; Timofeev, I. YA.; Shipilov, S. D.
1988-01-01
In recent years much attention has been given to the development of methods and programs for the calculation of the aerodynamic characteristics of multiblade, saber-shaped air propellers. Most existing methods are based on the theory of lifting lines. Elsewhere, the theory of a lifting surface is used to calculate screw and lifting propellers. In this work, methods of discrete eddies are described for the calculation of the aerodynamic characteristics of propellers using the linear and nonlinear theories of lifting surfaces.
Lichtenstein, J. H.
1978-01-01
An analytical method of computing the averaging effect of wing-span size on the loading of a wing induced by random turbulence was adapted for use on a digital electronic computer. The turbulence input was assumed to have a Dryden power spectral density. The computations were made for lift, rolling moment, and bending moment for two span load distributions, rectangular and elliptic. Data are presented to show the wing-span averaging effect for wing-span ratios encompassing current airplane sizes. The rectangular wing-span loading showed a slightly greater averaging effect than did the elliptic loading. In the frequency range most bothersome to airplane passengers, the wing-span averaging effect can reduce the normal lift load, and thus the acceleration, by about 7 percent for a typical medium-sized transport. Some calculations were made to evaluate the effect of using a Von Karman turbulence representation. These results showed that using the Von Karman representation generally resulted in a span averaging effect about 3 percent larger.
Tests and Procedures Face-lift By Mayo Clinic Staff A face-lift (rhytidectomy) is a cosmetic surgical procedure to improve the look of your face and neck. During a face-lift, facial soft tissues are lifted, excess skin is ...
A statistical model to predict streamwise turbulent dispersion from the wall at small times
Nguyen, Quoc; Papavassiliou, Dimitrios V.
2016-12-01
Data from simulations are used to develop a statistical model that can provide the streamwise dispersion distribution of passive particles released from the wall of a turbulent flow channel. It is found that a three-point gamma probability density function is the statistical distribution that can describe the dispersion of particles with Schmidt numbers ranging from 6 to 2400 at relatively short times after the release of the particles. Scaling arguments are used to physically justify and predict the parameters of the gamma three-point distribution. The model is used to predict particle separation that can occur in turbulent flow under special conditions. Close to the channel wall, turbulent convection is not the dominant transport mechanism, but molecular diffusion can dominate transport depending on the Schmidt number of the particles. This leads to turbulence-induced separation rather than mixing, and the currently proposed model can be used to predict the level of separation. Practically, these results can be applied for separating very small particles or even macromolecules in dilute suspensions.
Unseren, M.A.
1994-04-01
A general framework for solving the dynamic load distribution when two manipulators hold a rigid object is proposed. The underspecified problem of solving for the contact forces and torques based on the object`s equations of motion is transformed into a well specified problem. This is accomplished by augmenting the object`s equations of motion with additional equations which relate a new vector variable quantifying the internal contact force and torque degrees of freedom (DOF) as a linear function of the contact forces and torques. The resulting augmented system yields a well specified solution for the contact forces and torques in which they are separated into their motion inducing and internal components. A particular solution is suggested which enables the designer to conveniently specify what portion of the payload`s mass each manipulator is to bear. It is also shown that the results of the previous work are just a special case of the general load distribution framework described here.
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.
... 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 ...
Breast lift (mastopexy) - slideshow
... 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 ...
Inexpensive Dramatic Pneumatic Lift
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.
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.
Inexpensive Dramatic Pneumatic Lift
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…
Tests and Procedures Breast lift By Mayo Clinic Staff A breast lift — also known as mastopexy — is a surgical procedure to change the shape of your breasts. During a breast lift, excess skin is removed and breast tissue is ...
Accurate measurement of streamwise vortices in low speed aerodynamic flows
Waldman, Rye M.; Kudo, Jun; Breuer, Kenneth S.
2010-11-01
Low Reynolds number experiments with flapping animals (such as bats and small birds) are of current interest in understanding biological flight mechanics, and due to their application to Micro Air Vehicles (MAVs) which operate in a similar parameter space. Previous PIV wake measurements have described the structures left by bats and birds, and provided insight to the time history of their aerodynamic force generation; however, these studies have faced difficulty drawing quantitative conclusions due to significant experimental challenges associated with the highly three-dimensional and unsteady nature of the flows, and the low wake velocities associated with lifting bodies that only weigh a few grams. This requires the high-speed resolution of small flow features in a large field of view using limited laser energy and finite camera resolution. Cross-stream measurements are further complicated by the high out-of-plane flow which requires thick laser sheets and short interframe times. To quantify and address these challenges we present data from a model study on the wake behind a fixed wing at conditions comparable to those found in biological flight. We present a detailed analysis of the PIV wake measurements, discuss the criteria necessary for accurate measurements, and present a new dual-plane PIV configuration to resolve these issues.
Horia Dumitrescu
1998-01-01
Full Text Available The vortex model of propellers is modified and applied to the high-speed horizontal axis turbines. The turbine blades are replaced by lifting lines and trailing vortices which shed along the blade span. The model is not a free wake model, but it is still a nonlinear one which should be solved iteratively. In addition to the regular case where the trailing vortices are constrained to distribute along a helical surface, another version, where each trailing vortex sheding from the blade grows as a free helical vortex line, is also included. Performance parameters are calculated by application of the Biot-Savart law along with the Kutta-Joukowski theorem. Predictions are, shown to compare favorably with existing numerical data from more involved free wake methods, but require less computational effort. Thereby, the present method may be a very useful tool for calculating the aerodynamic loads on horizontal-axis wind turbine blades.
Development of plasma streamwise vortex generators for increased boundary layer control authority
Bowles, Patrick; Schatzman, David; Corke, Thomas; Thomas, Flint
2009-11-01
This experimental study focuses on active boundary layer flow control utilizing streamwise vorticity produced by a single dielectric barrier discharge plasma actuator. A novel plasma streamwise vortex generator (PSVG) layout is presented that mimics the passive flow control characteristics of the trapezoidal vane vortex generator. The PSVG consists of a common insulated electrode and multiple, exposed streamwise oriented electrodes used to produce counter-rotating vortical structures. Smoke and oil surface visualization of boundary layer flow over a flat plate compare the characteristics of passive control techniques and different PSVG designs. Passive and active control over a generic wall-mounted hump model, Rec = 288,000-575,000, are compared through static wall pressure measurements along the model's centerline. Different geometric effects of the PSVG electrode configuration were investigated. PSVG's with triangular exposed electrodes outperformed ordinary PSVG's under certain circumstances. The electrode arrangement produced flow control mechanisms and effectiveness similar to the passive trapezoidal vane vortex generators.
Numerical simulation of quasi-streamwise hairpin-like vortex generation in turbulent boundary layer
ZHANG Nan; LU Li-peng; DUAN Zhen-zhen; YUAN Xiang-jiang
2008-01-01
A mechanism for generation of near wall quasi-streamwise hairpin-like vortex (QHV) and secondary quasi-streamwise vortices (SQV) is presented. The conceptual model of resonant triad in the theory of hydrodynamic instability and direct numerical simulation of a turbulent boundary layer were applied to reveal the formation of QHV and SQV. The generation procedures and the characteristics of the vortex structures are obtained, which share some similarities with previous numerical simulations. The research using resonant triad conceptual model and numerical simulation provides a possibility for investigating and controling the vortex structures, which play a dominant role in the evolution of coherent structures in the near-wall region.
Lifting endomorphisms to automorphisms
Arveson, William; Courtney, Dennis
2007-01-01
Normal endomorphisms of von Neumann algebras need not be extendable to automorphisms of a larger von Neumann algebra, but they always have asymptotic lifts. We describe the structure of endomorphisms and their asymptotic lifts in some detail, and apply those results to complete the identification of asymptotic lifts of unital completely positive linear maps on von Neumann algebras in terms of their minimal dilations to endomorphisms.
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…
Streamwise transport in multi-component granular flows
Johnson, Chris; Hogg, Andrew; Phillips, Jeremy
2016-11-01
Thin free-surface avalanches of granular material occur widely in nature and industry. In these contexts the flows often contain particles of a wide range of sizes, which separate from one another due to particle size segregation. This segregation is troublesome in industry (where a well-mixed state is usually desired) and is an important mechanism for determining the runout and morphology of natural avalanches and debris flows. In this talk we develop a model for the spatial and temporal evolution of the particle size distribution in a granular flow, due to particle segregation, diffusion and advection processes. We use asymptotic solutions of this model to formulate equations governing the depth-integrated particle size distribution. These equations naturally extend the shallow-water models often used to predict the dynamics of monodisperse avalanches. Our modelling shows that particles in granular avalanches may strongly segregate in the direction of flow, even when the segregation is relatively weak compared to diffusive mixing and the avalanche is nearly homogeneous throughout its depth. We demonstrate this surprising phenomenon through comparison with discrete particle simulations.
Coltharp, E.D.; Khokhar, M.
1984-09-01
Dubai Petroleum Company has recently installed a computer gas lift surveillance and gas lift gas injection control system in the Fateh and S.W. Fateh Fields located in the southern part of the Arabian Gulf. This system is the fourth generation of the computer control system installed in California in 1971 by Conoco, Inc. This paper describes the advantages and problems in this system to monitor and control the gas lift operation of 116 wells through 30 intelligent remote terminal units (RTU). In addition, this system monitors the condition of critical operational
FREIGHT CONTAINER LIFTING STANDARD
POWERS DJ; SCOTT MA; MACKEY TC
2010-01-13
This standard details the correct methods of lifting and handling Series 1 freight containers following ISO-3874 and ISO-1496. The changes within RPP-40736 will allow better reading comprehension, as well as correcting editorial errors.
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.
Xu Wan-hai; Yu Jian-xing; Du Jie; CHENG An-kang; KANG Hao
2012-01-01
The streamwise flow-induced vibration of a circular cylinder with symmetric vortex shedding in the first instability range is investigated,and a wake oscillator model for the dynamic response prediction is proposed.An approach is applied to calibrate the empirical parameters in the present model; the numerical and experimental results are compared to validate the proposed model.It can be found that the present prediction model is accurate and sufficiently simple to be easily applied in practice.
Development of Pre-set Counter-rotating Streamwise Vortices in Wavy Channel
Budiman, A.C.
2015-10-23
Development of counter-rotating streamwise vortices in a rectangular channel with one-sided wavy surface has been experimentally quantified using hot-wire anemometry. The wavy surface has fixed amplitude of 3.75 mm. The counter-rotating vortices are pre-set by means of a sawtooth pattern cut at the leading edge of the wavy surface. Variations of the central streamwise velocity Uc with a channel gap H = 35 mm and 50 mm (corresponding to a Reynolds number from 1600 to 4400) change the instability of the flow which can be distinguished from the velocity contours at a certain spanwise plane. The streamwise velocity contours and turbulence intensity for Reynolds number Re = 3100 and H = 35 mm show the disappearance of the mushroom-like vortices prior to turbulence near the second peak of the wavy surface, while for higher Re, this phenomenon occurs earlier. Under certain conditions, for example, for Re = 4400 and H = 50 mm, the splitting of the vortices can also be observed.
The lift-up effect: the linear mechanism behind transition and turbulence in shear flows
Brandt, Luca
2014-01-01
The formation and amplification of streamwise velocity perturbations induced by cross-stream disturbances is ubiquitous in shear flows. This disturbance growth mechanism, so neatly identified by Ellingsen and Palm in 1975, is a key process in transition to turbulence and self-sustained turbulence. In this review, we first present the original derivation and early studies and then discuss the non-modal growth of streaks, the result of the lift-up process, in transitional and turbulent shear flows. In the second part, the effects on the lift-up process of additives in the fluid and of a second phase are discussed and new results presented with emphasis on particle-laden shear flows. For all cases considered, we see the lift-up process to be a very robust process, always present as a first step in subcritical transition.
Approach Considerations in Aircraft with High-Lift Propeller Systems
Patterson, Michael D.; Borer, Nicholas K.
2017-01-01
NASA's research into distributed electric propulsion (DEP) includes the design and development of the X-57 Maxwell aircraft. This aircraft has two distinct types of DEP: wingtip propellers and high-lift propellers. This paper focuses on the unique opportunities and challenges that the high-lift propellers--i.e., the small diameter propellers distributed upstream of the wing leading edge to augment lift at low speeds--bring to the aircraft performance in approach conditions. Recent changes to the regulations related to certifying small aircraft (14 CFR x23) and these new regulations' implications on the certification of aircraft with high-lift propellers are discussed. Recommendations about control systems for high-lift propeller systems are made, and performance estimates for the X-57 aircraft with high-lift propellers operating are presented.
Regional changes in spine posture at lift onset with changes in lift distance and lift style.
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.
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.
Lagrangian structures and mixing in the wake of a streamwise oscillating cylinder
Cagney, N.; Balabani, S.
2016-04-01
Lagrangian analysis is capable of revealing the underlying structure and complex phenomena in unsteady flows. We present particle-image velocimetry measurements of the wake of a cylinder undergoing streamwise vortex-induced vibrations and calculate the Finite-Time Lyapunov Exponents (FTLE) in backward- and forward-time. The FTLE fields are compared to the phase-averaged vorticity fields for the four different wake modes observed while the cylinder experiences streamwise vortex-induced vibrations. The backward-time FTLE fields characterise the formation of vortices, with the roll up of spiral-shaped ridges coinciding with the roll up of the shear layers to form the vortices. Ridges in the forward-time fields tend to lie perpendicular to the flow direction and separate nearby vortices. The shedding of vortices coincides with a "peel off" process in the forward-time FTLE fields, in which a ridge connected to the cylinder splits into two strips, one of which moves downstream. Particular attention is given to the "wake breathing" process, in which the streamwise motion of the cylinder causes both shear layers to roll up simultaneously and two vortices of opposite sign to be shed into the wake. In this case, the ridges in forward-time FTLE fields are shown to define "vortex cells," in which the new vortices form, and the FTLE fields allow the wake to be decomposed into three distinct regions. Finally, the mixing associated with each wake mode is examined, and it is shown that cross-wake mixing is significantly enhanced when the vibration amplitude is large and the vortices are shed alternately. However, while the symmetric shedding induces large amplitude vibrations, no increase in mixing is observed relative to the von Kármán vortex street observed behind near-stationary bodies.
Probe shapes that measure time-averaged streamwise momentum and cross-stream turbulence intensity
Rossow, Vernon J. (Inventor)
1993-01-01
A method and apparatus for directly measuring the time-averaged streamwise momentum in a turbulent stream use a probe which has total head response which varies as the cosine-squared of the angle of incidence. The probe has a nose with a slight indentation on its front face for providing the desired response. The method of making the probe incorporates unique design features. Another probe may be positioned in a side-by-side relationship to the first probe to provide a direct measurement of the total pressure. The difference between the two pressures yields the sum of the squares of the cross-stream components of the turbulence level.
... sagging. An arm lift might also boost your body image. As you get older, the skin on your upper arms changes — sagging and becoming loose. Significant weight loss also can cause the undersides of your upper arms to droop. While exercise can strengthen and improve muscle tone in the ...
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…
Gato-Rivera, B. [NIKHEF Theory Group, Kruislaan 409, 1098 SJ Amsterdam (Netherlands); Instituto de Fisica Fundamental, CSIC, Serrano 123, Madrid 28006 (Spain); Schellekens, A.N., E-mail: t58@nikhef.n [NIKHEF Theory Group, Kruislaan 409, 1098 SJ Amsterdam (Netherlands); Instituto de Fisica Fundamental, CSIC, Serrano 123, Madrid 28006 (Spain); IMAPP, Radboud Universiteit, Nijmegen (Netherlands)
2010-03-21
We describe a method for constructing genuinely asymmetric (2,0) heterotic strings out of N=2 minimal models in the fermionic sector, whereas the bosonic sector is only partly build out of N=2 minimal models. This is achieved by replacing one minimal model plus the superfluous E{sub 8} factor by a non-supersymmetric CFT with identical modular properties. This CFT generically lifts the weights in the bosonic sector, giving rise to a spectrum with fewer massless states. We identify more than 30 such lifts, and we expect many more to exist. This yields more than 450 different combinations. Remarkably, despite the lifting of all Ramond states, it is still possible to get chiral spectra. Even more surprisingly, these chiral spectra include examples with a certain number of chiral families of SO(10), SU(5) or other subgroups, including just SU(3)xSU(2)xU(1). The number of families and mirror families is typically smaller than in standard Gepner models. Furthermore, in a large number of different cases, spectra with three chiral families can be obtained. Based on a first scan of about 10% of the lifted Gepner models we can construct, we have collected more than 10,000 distinct spectra with three families, including examples without mirror fermions. We present an example where the GUT group is completely broken to the standard model, but the resulting and inevitable fractionally charged particles are confined by an additional gauge group factor.
Lifted Inference for Relational Continuous Models
Choi, Jaesik; Hill, David J
2012-01-01
Relational Continuous Models (RCMs) represent joint probability densities over attributes of objects, when the attributes have continuous domains. With relational representations, they can model joint probability distributions over large numbers of variables compactly in a natural way. This paper presents a new exact lifted inference algorithm for RCMs, thus it scales up to large models of real world applications. The algorithm applies to Relational Pairwise Models which are (relational) products of potentials of arity 2. Our algorithm is unique in two ways. First, it substantially improves the efficiency of lifted inference with variables of continuous domains. When a relational model has Gaussian potentials, it takes only linear-time compared to cubic time of previous methods. Second, it is the first exact inference algorithm which handles RCMs in a lifted way. The algorithm is illustrated over an example from econometrics. Experimental results show that our algorithm outperforms both a groundlevel inferenc...
Alexander Christantho Budiman
2016-01-01
Full Text Available Two different channel entrance designs, code named Valley First (VF and Peak First (PF, were experimentally visualized by means of smoke-wire visualization technique to observe their effects towards the streamwise counter-rotating vortices generated. The spanwise wavelength of the vortices was pre-set by modifying the leading edge. The investigation was carried out on the laminar boundary-layer flow in a rectangular channel with one-sided wavy surface that has amplitude a and wavelength λ of 7.5 mm and 76 mm, respectively. The vortices in the channel with VF design preserve farther downstream than those on the PF design, which might be caused by the large favorable pressure gradient between the entrance flat plate and the first peak location. The counter-rotating vortices could still be observed at non-dimensionalized streamwise distance χ (= x/λ = 2.47 for Reynolds number Re (= UH/ν = 9900 in channel with VF design. For lower Re, the vortices could preserve further downstream. In contrast, in channel with PF design, the structures were only visible clearly up to approximately χ = 1.32 for Re = 4700 and χ = 0.39 for Re = 5200.
Negative streamwise velocities and other rare events near the wall in turbulent flows
Lenaers, Peter; Li Qiang; Brethouwer, Geert; Schlatter, Philipp; Oerlue, Ramis, E-mail: Lenaers@mech.kth.se [Linne FLOW Centre, KTH Mechanics, SE-100 44 Stockholm (Sweden)
2011-12-22
Negative streamwise velocities, extreme wall-normal velocites and high flatness values for the wall-normal fluctuations near the wall are investigated for turbulent channel flow simulations at a series of Reynolds numbers up to Re{sub {tau}} = 1000 in this paper. Probability density functions of the wall-shear stress and velocity components are presented, as well as joint probability density functions of the velocity components and the pressure. Backflow occurs more often (0.06% at Re{sub {tau}} = 1000) and further away from the wall into the buffer layer for rising Reynolds number. An oblique vortex outside the viscous sublayer is found to cause this backflow. Extreme v events occur also more often for rising Reynolds number. Positive and negative velocity spikes appear in pairs, located on the two edges of a strong streamwise vortex: the negative spike occurring in a high speed streak indicating a sweeping motion, while the positive spike is located between a high and low speed streak. These extreme v events cause high flatness values near the wall (F(v) = 43 at Re{sub {tau}} = 1000).
On classical and quantum liftings
Accardi, L; Kossakowski, A; Matsuoka, T; Ohya, M
2011-01-01
We analyze the procedure of lifting in classical stochastic and quantum systems. It enables one to `lift' a state of a system into a state of `system+reservoir'. This procedure is important both in quantum information theory and the theory of open systems. We illustrate the general theory of liftings by a particular class related to so called circulant states.
Helicopter Toy and Lift Estimation
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.)
Helicopter Toy and Lift Estimation
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.)
Moulden, Steve [Sysco Food Service, Houston, TX (United States)
2015-08-20
This project, entitled “Recovery Act: Fuel Cell-Powered Lift Truck Sysco (Houston) Fleet Deployment”, was in response to DOE funding opportunity announcement DE-PS36-08GO98009, Topic 7B, which promotes the deployment of fuel cell powered material handling equipment in large, multi-shift distribution centers. This project promoted large-volume commercialdeployments and helped to create a market pull for material handling equipment (MHE) powered fuel cell systems. Specific outcomes and benefits involved the proliferation of fuel cell systems in 5-to 20-kW lift trucks at a high-profile, real-world site that demonstrated the benefits of fuel cell technology and served as a focal point for other nascent customers. The project allowed for the creation of expertise in providing service and support for MHE fuel cell powered systems, growth of existing product manufacturing expertise, and promoted existing fuel cell system and component companies. The project also stimulated other MHE fleet conversions helping to speed the adoption of fuel cell systems and hydrogen fueling technology. This document also contains the lessons learned during the project in order to communicate the successes and difficulties experienced, which could potentially assist others planning similar projects.
Bouremel, Yann
2016-11-01
Particle Image Velocimetry (PIV) has been used to characterize the evolution of counter-rotating streamwise vortices in a rectangular channel with one sided wavy surface. The vortices were created by a uniform set of saw-tooth carved over the leading edge of a flat plate at the entrance of a flat rectangular channel with one-sided wavy wall. PIV measurements were taken over the spanwise and streamwise planes at different locations and at Reynolds number of 2500. Two other Reynolds numbers of 2885 and 3333 have also been considered for quantification purpose. Pairs of counter-rotating streamwise vortices have been shown experimentally to be centred along the spanwise direction at the saw-tooth valley where the vorticity ωz=0ωz=0. It has also been found that the vorticity ωzωz of the pairs of counter-rotating vortices decreases along the streamwise direction, and increases with the Reynolds number. Moreover, different quantifications of such counter-rotating vortices have been discussed such as their size, boundary layer, velocity profile and vorticity. The current study shows that the mixing due to the wall shear stress of counter-rotating streamwise vortices as well as their averaged viscous dissipation rate of kinetic energy decrease over flat and adverse pressure gradient surfaces while increasing over favourable pressure gradient surfaces. Finally, it was also demonstrated that the main direction of stretching is orientated at around 45° with the main flow direction.
Lift performance and lumbar loading in standing and seated lifts.
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.
2007-08-01
the 500 group include climate control, freshwater/seawater systems, mechanical handling, and special purpose systems. Due to the large troop...compliment carried on the JHSS, large amounts of climate control and ventilation were required. The transformable heavy lift ship has only a single... Treeline Connector Innovation Cell Naval Research Enterprise Intern Program Final Report, NSWCCD-20-TR-2005/05 August 2005 "Saturn." Nijhuis
Gato-Rivera, B
2009-01-01
We describe a method for constructing genuinely asymmetric (2,0) heterotic strings out of N=2 minimal models in the fermionic sector, whereas the bosonic sector is only partly build out of N=2 minimal models. This is achieved by replacing one minimal model plus the superfluous E_8 factor by a non-supersymmetric CFT with identical modular properties. This CFT generically lifts the weights in the bosonic sector, giving rise to a spectrum with fewer massless states. We identify more than 30 such lifts, and we expect many more to exist. This yields more than 450 different combinations. Remarkably, despite the lifting of all Ramond states, it is still possible to get chiral spectra. Even more surprisingly, these chiral spectra include examples with a certain number of chiral families of SO(10), SU(5) or other subgroups, including just SU(3) x SU(2) x U(1). The number of families and mirror families is typically smaller than in standard Gepner models. Furthermore, in a large number of different cases, spectra with ...
Moarref, Rashad; Tropp, Joel A; McKeon, Beverley J
2013-01-01
We study the Reynolds number scaling of a gain-based, low-rank approximation to turbulent channel flows, determined by the resolvent formulation of McKeon & Sharma (2010), in order to obtain a description of the streamwise turbulence intensity from direct consideration of the Navier-Stokes equations. Under this formulation, the velocity field is decomposed into propagating waves (with single streamwise and spanwise wavelengths and wave speed) whose wall-normal shapes are determined from the principal singular function of the corresponding resolvent operator. We establish that the resolvent formulation admits three classes of wave parameters that induce universal behavior with Reynolds number on the low-rank model, and which are consistent with scalings proposed throughout the wall turbulence literature. For the rank-1 model subject to broadband forcing, the integrated streamwise energy density takes a universal form which is consistent with the dominant near-wall turbulent motions. When the shape of the f...
Lifting speed preferences and their effects on the maximal lifting capacity.
Lin, Chiuhsiang Joe; Cheng, Chih-Feng
2017-02-07
The objectives of this study were to evaluate how lifting capacity and subjective preferences are affected by different lifting speeds. The maximum lifting capacity of lift was determined with three independent variables, lifting speed, lifting technique, and lifting height. Questionnaires were evaluated after the experiment by the participants for the lifting speed preferences. This study found that the lifting speed was a significant factor in the lifting capacity (plifting height (plifting 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.
Numerical study of streamwise and cross flow in the presence of heat and mass transfer
Rizwan-ul-Haq; Soomro, Feroz Ahmed; Khan, Z. H.; Al-Mdallal, Qasem M.
2017-05-01
The present model is devoted to investigate the streamwise and cross flow of a viscous fluid over a heated moving surface. Viscous dissipation effects are also considered with heat and mass transfer effects and these effects with cross flow have not been explored yet in the literature. Governing boundary layer equations consist in the form of nonlinear partial differential equations (PDEs). Compatible transformations are applied to change such equations into ordinary differential equations which are further solved using the Runge-Kutta technique and shooting method. Linear stability analysis is also performed over the obtained solutions to validate the results and to determine the smallest eigenvalues. Three different kinds of fluids namely: acetone, water and ethaline glycol are investigated to analyse the heat transfer rate. The problem contains important physical parameters namely: Prandtl number, Eckert numbers and Lewis number. The obtained solutions are discussed in detail against each physical parameter using graphs and tables.
Joint Stream-Wise THP Transceiver Design for the Multiuser MIMO Downlink
Miao, Wei; Chen, Xiang; Zhao, Ming; Zhou, Shidong; Wang, Jing
This paper addresses the problem of joint transceiver design for Tomlinson-Harashima Precoding (THP) in the multiuser multiple-input-multiple-output (MIMO) downlink under both perfect and imperfect channel state information at the transmitter (CSIT). For the case of perfect CSIT, we differ from the previous work by performing stream-wise (both inter-user and intra-user) interference pre-cancelation at the transmitter. A minimum total mean square error (MT-MSE) criterion is used to formulate our optimization problem. By some convex analysis of the problem, we obtain the necessary conditions for the optimal solution. An iterative algorithm is proposed to handle this problem and its convergence is proved. Then we extend our designed algorithm to the robust version by minimizing the conditional expectation of the T-MSE under imperfect CSIT. Simulation results are given to verify the efficacy of our proposed schemes and to show their superiorities over existing MMSE-based THP schemes.
Controlling the onset of turbulence by streamwise traveling waves. Part 1: Receptivity analysis
Moarref, Rashad
2010-01-01
We examine the efficacy of streamwise traveling waves generated by a zero-net-mass-flux surface blowing and suction for controlling the onset of turbulence in a channel flow. For small amplitude actuation, we utilize weakly nonlinear analysis to determine base flow modifications and to assess the resulting net power balance. Receptivity analysis of the velocity fluctuations around this base flow is then employed to design the traveling waves. Our simulation-free approach reveals that, relative to the flow with no control, the downstream traveling waves with properly designed speed and frequency can significantly reduce receptivity which makes them well-suited for controlling the onset of turbulence. In contrast, the velocity fluctuations around the upstream traveling waves exhibit larger receptivity to disturbances. Our theoretical predictions, obtained by perturbation analysis (in the wave amplitude) of the linearized Navier-Stokes equations with spatially periodic coefficients, are verified using full-scale...
Lieu, Binh K; Jovanović, Mihailo R
2010-01-01
This work builds on and confirms the theoretical findings of Part 1 of this paper, Moarref & Jovanovi\\'c (2010). We use direct numerical simulations of the Navier-Stokes equations to assess the efficacy of blowing and suction in the form of streamwise traveling waves for controlling the onset of turbulence in a channel flow. We highlight the effects of the modified base flow on the dynamics of velocity fluctuations and net power balance. Our simulations verify the theoretical predictions of Part 1 that the upstream traveling waves promote turbulence even when the uncontrolled flow stays laminar. On the other hand, the downstream traveling waves with parameters selected in Part 1 are capable of reducing the fluctuations' kinetic energy, thereby maintaining the laminar flow. In flows driven by a fixed pressure gradient, a positive net efficiency as large as 25 % relative to the uncontrolled turbulent flow can be achieved with downstream waves. Furthermore, we show that these waves can also relaminarize full...
An experimental study of spanwise flow effects on lift generation in flapping wings
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
2008-08-04
The Eagle Books are a series of four books that are brought to life by wise animal characters - Mr. Eagle, Miss Rabbit, and Coyote - who engage Rain That Dances and his young friends in the joy of physical activity, eating healthy foods, and learning from their elders about health and diabetes prevention. Knees Lifted High gives children fun ideas for active outdoor play. Created: 8/4/2008 by National Center for Chronic Disease Prevention and Health Promotion (NCCDPHP). Date Released: 8/5/2008.
Lift application development cookbook
Garcia, Gilberto T
2013-01-01
Lift Application Development Cookbook contains practical recipes on everything you will need to create secure web applications using this amazing framework.The book first teaches you basic topics such as starting a new application and gradually moves on to teach you advanced topics to achieve a certain task. Then, it explains every step in detail so that you can build your knowledge about how things work.This book is for developers who have at least some basic knowledge about Scala and who are looking for a functional, secure, and modern web framework. Prior experience with HTML and JavaScript
AbstractWhile microbial growth is well-understood in pure culture systems, less is known about growth in intact soil systems. The objective of this work was to develop a technique to allow visualization of the two-dimensional spatial distribution of bacterial growth o...
Velte, Clara Marika; Okulov, Valery; Hansen, Martin Otto Laver
2013-01-01
The current work describes the experimental parametric study of streamwise vortices generated in a boundary layer by a rectangular vane (commonly named vortex generator) mounted perpendicularly to the wall and at an angle to the oncoming flow. Stereoscopic Particle Image Velocimetry measurements...
Ostanek, Jason K.; Thole, Karen A.
2012-12-01
While flow across long tube bundles is considered classical data, pin-fin arrays made up of short tubes have become a growing topic of interest for use in cooling gas turbine airfoils. Data from the literature indicate that decreasing streamwise spacing increases heat transfer in pin-fin arrays; however, the specific mechanism that causes increased heat transfer coefficients remains unknown. The present work makes use of time-resolved PIV to quantify the effects of streamwise spacing on the turbulent near wake throughout various pin-fin array spacings. Specifically, proper orthogonal decomposition was used to separate the (quasi-) periodic motion from vortex shedding and the random motion from turbulent eddies. Reynolds number flow conditions of 3.0 × 103 and 2.0 × 104, based on pin-fin diameter and velocity at the minimum flow area, were considered. Streamwise spacing was varied from 3.46 pin diameters to 1.73 pin diameters while the pin-fin height-to-diameter ratio was unity and the spanwise spacing was held constant at two diameters. Results indicated that (quasi-) periodic motions were attenuated at closer streamwise spacings while the level of random motions was not strongly dependent on pin-fin spacing. This trend was observed at both Reynolds number conditions considered. Because closer spacings exhibit higher heat transfer levels, the present results imply that periodic motions may not contribute to heat transfer, although further experimentation is required.
Unseren, M.A.
1994-04-01
A rigid body model for the entire system which accounts for the load distribution scheme proposed in Part 1 as well as for the dynamics of the manipulators and the kinematic constraints is derived in the joint space. A technique is presented for expressing the object dynamics in terms of the joint variables of both manipulators which leads to a positive definite and symmetric inertia matrix. The model is then transformed to obtain reduced order equations of motion and a separate set of equations which govern the behavior of the internal contact forces. The control architecture is applied to the model which results in the explicit decoupling of the position and internal contact force-controlled degrees of freedom (DOF).
Flow interaction between a streamwise oscillating cylinder and a downstream stationary cylinder
Xu, S. J.; Gan, L.; Zhou, Y.
2016-11-01
In this paper, we present some experimental results about the physical effects of a cylinder's streamwise oscillation motion on a downstream one in a tandem arrangement. The upstream cylinder undergoes a controlled simple harmonic oscillation at amplitudes A/ d = 0.2-0.8, where d is the cylinder diameter, and the frequency ratio of f_e/f_s = 0-3.0, where f_e is the cylinder oscillation frequency and f_s is the natural frequency of vortex shedding from a single stationary cylinder. Under these conditions, the vortex shedding is locked to the controlled oscillation motion. Flow visualisation using the planar laser-induced fluorescence and qualitative measurements using hot-wire anemometry reveal three distinct flow regimes behind the downstream cylinder. For f_e/f_s > (f_e/f_s)_c, where (f_e/f_s)_c is a critical frequency ratio which depends on A/ d and Reynolds number Re, a so-called SA-mode occurs. The upstream oscillating cylinder generates binary vortices symmetrically arranged about the centreline, each containing a pair of counter-rotating vortices, and the downstream cylinder sheds vortices alternately at 0.5f_e. For 0.7-1.0 < f_e/f_s < (f_e/f_s)_c a complex vortex street that consists of two outer rows of vortices generated by the oscillating cylinder and two inner rows of vortices shed from the downstream stationary cylinder, which is referred to as AA-mode. For 0.3-0.6 < f_e/f_s< 0.8-1.0, one single staggered vortex street (A-mode) is observed. It is also found that, when f_e/f_s is near unity, the streamwise interaction of the two cylinders gives rise to the most energetic wake in the cross-stream direction, in terms of its maximum width, and the wake is AA-mode-like. The effects of other parameters such as the spacing between the two cylinders, Re and A/ d on the flow pattern are also discussed in details. The observations are further compared to the stationary tandem cylinder cases.
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.
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,…
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,…
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.
Wavelets and the lifting scheme
la Cour-Harbo, Anders; Jensen, Arne
2012-01-01
The objective of this article is to give a concise introduction to the discrete wavelet transform (DWT) based on a technique called lifting. The lifting technique allows one to give an elementary, but rigorous, definition of the DWT, with modest requirements on the reader. A basic knowledge of li...... of linear algebra and signal processing will suffice. The lifting based definition is equivalent to the usual filer bank based definition of the DWT. The article does not discuss applications in any detail. The reader is referred to other articles in this collection.......The objective of this article is to give a concise introduction to the discrete wavelet transform (DWT) based on a technique called lifting. The lifting technique allows one to give an elementary, but rigorous, definition of the DWT, with modest requirements on the reader. A basic knowledge...
Wavelets and the lifting scheme
la Cour-Harbo, Anders; Jensen, Arne
2009-01-01
The objective of this article is to give a concise introduction to the discrete wavelet transform (DWT) based on a technique called lifting. The lifting technique allows one to give an elementary, but rigorous, definition of the DWT, with modest requirements on the reader. A basic knowledge of li...... of linear algebra and signal processing will suffice. The lifting based definition is equivalent to the usual filer bank based definition of the DWT. The article does not discuss applications in any detail. The reader is referred to other articles in this collection.......The objective of this article is to give a concise introduction to the discrete wavelet transform (DWT) based on a technique called lifting. The lifting technique allows one to give an elementary, but rigorous, definition of the DWT, with modest requirements on the reader. A basic knowledge...
Wavelets and the Lifting Scheme
la Cour-Harbo, Anders; Jensen, Arne
The objective of this article is to give a concise introduction to the discrete wavelet transform (DWT) based on a technique called lifting. The lifting technique allows one to give an elementary, but rigorous, definition of the DWT, with modest requirements on the reader. A basic knowledge of li...... of linear algebra and signal processing will suffice. The lifting based definition is equivalent to the usual filer bank based definition of the DWT. The article does not discuss applications in any detail. The reader is referred to other articles in this collection.......The objective of this article is to give a concise introduction to the discrete wavelet transform (DWT) based on a technique called lifting. The lifting technique allows one to give an elementary, but rigorous, definition of the DWT, with modest requirements on the reader. A basic knowledge...
Krishna Nandan Kumar
2011-01-01
Full Text Available The present study attempts to reduce secondary flow losses by application of streamwise endwall fence. After comprehensive analysis on selection of objective function for secondary flow loss reduction, coefficient of secondary kinetic energy (CSKE is selected as the objective function in this study. A fence whose height varies linearly from the leading edge to the trailing edge and located in the middle of the flow passage produces least CSKE and is the optimum fence. The reduction in CSKE by the optimum fence is 27% compared to the baseline case. The geometry of the fence is new and is reported for the first time. Idea of this fence comes from the fact that the size of the passage vortex (which is the prime component of secondary flow increases as it travels downstream, hence the height of fence should vary as the objective of fence is to block the passage vortex from crossing the passage and impinging on suction surface of the blade. Optimum fence reduced overturning and underturning of flow by more than 50% compared to the baseline case. Magnitude and spanwise penetration of the passage vortex were reduced considerably compared to the baseline case.
Hasheminejad, S. M.
2016-01-05
A series of flow visualizations were conducted to qualitatively study the development of streamwise counter-rotating vortices over a flat plate induced by triangular patterns at the leading edge of a flat plate. The experiments were carried out for a Reynolds number based on the pattern wavelength (λ) of 3080. The results depict the onset, development and breakdown of the vortical structures within the flat plate boundary layer. Moreover, the effect of one spanwise array of holes with diameter of 0.2λ (=3 mm) was examined. This investigation was done on two different flat plates with holes placed at the location x/λ = 2 downstream of the troughs and peaks. The presence of holes after troughs does not show any significant effect on the vortical structures. However, the plate with holes after peaks noticeably delays the vortex breakdown. In this case, the “mushroom-like” vortices move away from the wall and propagate downstream with stable vortical structures. The vortex growth is halted further downstream but start to tilt aside.
Influence of pressure gradient on streamwise skewness factor in turbulent boundary layer
Dróżdż, Artur
2014-08-01
The paper shows an effect of favourable and adverse pressure gradients on turbulent boundary layer. The skewness factor of streamwise velocity component was chosen as a measure of the pressure gradient impact. It appears that skewness factor is an indicator of convection velocity of coherent structures, which is not always equal to the average flow velocity. The analysis has been performed based upon velocity profiles measured with hot-wire technique in turbulent boundary layer with pressure gradient corresponding to turbomachinery conditions. The results show that the skewness factor decreases in the flow region subjected to FPG and increases in the APG conditions. The changes of convection velocity and skewness factor are caused by influence of large-scale motion through the mechanism called amplitude modulation. The large-scale motion is less active in FPG and more active in APG, therefore in FPG the production of vortices is random (there are no high and low speed regions), while in the APG the large-scale motion drives the production of vortices. Namely, the vortices appear only in the high-speed regions, therefore have convection velocity higher than local mean velocity. The convection velocity affects directly the turbulent sweep and ejection events. The more flow is dominated by large-scale motion the higher values takes both the convection velocity of small-scale structures and sweep events induced by them.
Lift Recovery for AFC-Enabled High Lift System
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.
Wavelets and the lifting scheme
la Cour-Harbo, Anders; Jensen, Arne
2009-01-01
The objective of this article is to give a concise introduction to the discrete wavelet transform (DWT) based on a technique called lifting. The lifting technique allows one to give an elementary, but rigorous, definition of the DWT, with modest requirements on the reader. A basic knowledge...... of linear algebra and signal processing will suffice. The lifting based definition is equivalent to the usual filer bank based definition of the DWT. The article does not discuss applications in any detail. The reader is referred to other articles in this collection....
Lifting strength in two-person teamwork.
Lee, Tzu-Hsien
2016-01-01
This study examined the effects of lifting range, hand-to-toe distance, and lifting direction on single-person lifting strengths and two-person teamwork lifting strengths. Six healthy males and seven healthy females participated in this study. Two-person teamwork lifting strengths were examined in both strength-matched and strength-unmatched groups. Our results showed that lifting strength significantly decreased with increasing lifting range or hand-to-toe distance. However, lifting strengths were not affected by lifting direction. Teamwork lifting strength did not conform to the law of additivity for both strength-matched and strength-unmatched groups. In general, teamwork lifting strength was dictated by the weaker of the two members, implying that weaker members might be exposed to a higher potential danger in teamwork exertions. To avoid such overexertion in teamwork, members with significantly different strength ability should not be assigned to the same team.
Optimizing Spanwise & Streamwise Spacings of MHK Devices in a Trapezoidal River Channel
Roberts, J. D.; Barco, J.; Johnson, E.; James, S. C.; Jones, C. A.; Jepsen, R. A.
2011-12-01
The world is facing significant challenges meeting the energy demands for the future. Growing populations and developing economies as well as increasing energy expenditures highlight the need for a spectrum of energy sources. One promising renewable is marine and hydrokinetic (MHK) energy, which has the potential to make important contributions to future energy portfolios. Increasing interest in MHK energy has spurred to significant research on optimal placement of emerging technologies to maximize energy capture and minimize potential negative effects on the environment. Understanding changes to near- and far-field hydrodynamics is necessary to assess optimal placement. This work demonstrates a newly developed modeling tool that can be used to optimize MHK array layouts to maximize energy capture while minimizing potentially harmful environmental effects. SNL has developed and implemented modifications to an existing flow, sediment-dynamics, and water-quality code (SNL-EFDC) to qualify, quantify, and visualize the interaction and influence of MHK-device operation at a representative site using an appropriate and verified representation of momentum/energy extraction and turbulent wake generation. Various hypothetical MHK array configurations are simulated within a straight rectangular unidirectional flow conditions channel at several water column depths. Results show that the turbine-array power efficiency increased, nonlinearly, as turbine spacing was increased in both the spanwise and streamwise directions as well as when turbines were placed higher in the water column. Contour plots facilitate evaluation of tradeoffs between efficiency and spacing. In addition, results show that flow increases around and over/under the array leading to elevated velocities in the main channel, near the bank, and near the sediment bed, which may have potential implications for bank and bottom erosion, and navigation. SNL-EFDC's "MHK friendly" array-optimization tool is and will
Three-dimensional instability analysis of boundary layers perturbed by streamwise vortices
Martín, Juan A.; Paredes, Pedro
2016-08-01
A parametric study is presented for the incompressible, zero-pressure-gradient flat-plate boundary layer perturbed by streamwise vortices. The vortices are placed near the leading edge and model the vortices induced by miniature vortex generators (MVGs), which consist in a spanwise-periodic array of small winglet pairs. The introduction of MVGs has been experimentally proved to be a successful passive flow control strategy for delaying laminar-turbulent transition caused by Tollmien-Schlichting (TS) waves. The counter-rotating vortex pairs induce non-modal, transient growth that leads to a streaky boundary layer flow. The initial intensity of the vortices and their wall-normal distances to the plate wall are varied with the aim of finding the most effective location for streak generation and the effect on the instability characteristics of the perturbed flow. The study includes the solution of the three-dimensional, stationary, streaky boundary layer flows by using the boundary region equations, and the three-dimensional instability analysis of the resulting basic flows by using the plane-marching parabolized stability equations. Depending on the initial circulation and positioning of the vortices, planar TS waves are stabilized by the presence of the streaks, resulting in a reduction in the region of instability and shrink of the neutral stability curve. For a fixed maximum streak amplitude below the threshold for secondary instability (SI), the most effective wall-normal distance for the formation of the streaks is found to also offer the most stabilization of TS waves. By setting a maximum streak amplitude above the threshold for SI, sinuous shear layer modes become unstable, as well as another instability mode that is amplified in a narrow region near the vortex inlet position.
On the generalized lifting problem
Giorgio Bolondi
1993-05-01
Full Text Available We construct curves for which the generalized lifting property does not hold, with high degree. We discuss the behaviour of the Hilbert function of the general plane section of these curves.
Nordic noir and lifted localities
Hansen, Kim Toft
What I do here is to draw attention to a particular visual quality of recent Nordic noir and to relate the visuality of TV-drama to what I – with a term borrowed from Roland Robertson – dub lifted localites.......What I do here is to draw attention to a particular visual quality of recent Nordic noir and to relate the visuality of TV-drama to what I – with a term borrowed from Roland Robertson – dub lifted localites....
Zhong, Qiang; Chen, Qigang; Wang, Hao; Li, Danxun; Wang, Xingkui
2016-05-01
Long streamwise-elongated high- and low-speed streaks are repeatedly observed near the free surface in open channel flows in natural rivers and lab experiments. Super-streamwise vortex model has been proposed to explain this widespread phenomenon for quite some time. However, statistical evidence of the existence of the super-streamwise vortices as one type of coherent structures is still insufficient. Correlation and proper orthogonal decomposition (POD) analysis based on PIV experimental data in the streamwise-spanwise plane near the free surface in a smooth open channel flow are employed to investigate this topic. Correlation analysis revealed that the streaky structures appear frequently near the free surface and their occurrence probability at any spanwise position is equal. The spanwise velocity fluctuation usually flows from low-speed streaks toward high-speed streaks. The average spanwise width and spacing between neighboring low (or high) speed streaks are approximately h and 2h respectively. POD analysis reveals that there are streaks with different spanwise width in the instantaneous flow fields. Typical streamwise rotational movement can be sketched out directly based on the results from statistical analyses. Point-by-point analysis indicates that this pattern is consistent everywhere in the measurement window and is without any inhomogeneity in the spanwise direction, which reveals the essential difference between coherent structures and secondary flow cells. The pattern found by statistical analysis is consistent with the notion that the super-streamwise vortices exist universally as one type of coherent structure in open channel flows.
Mist lift analysis summary report
Davenport, R.L.
1980-09-01
The mist flow open-cycle OTEC concept proposed by S.L. Ridgway has much promise, but the fluid mechanics of the mist flow are not well understood. The creation of the mist and the possibility of droplet growth leading to rainout (when the vapor can no longer support the mist) are particularly troublesome. This report summarizes preliminary results of a numerical analysis initiated at SERI in FY79 to study the mist-lift process. The analysis emphasizes the mass transfer and fluid mechanics of the steady-state mist flow and is based on one-dimensional models of the mist flow developed for SERI by Graham Wallis. One of Wallis's models describes a mist composed of a single size of drops and another considers several drop sizes. The latter model, further developed at SERI, considers a changing spectrum of discrete drop sizes and incorporates the mathematics describing collisions and growth of the droplets by coalescence. The analysis results show that under conditions leading to maximum lift in the single-drop-size model, the multigroup model predicts significantly reduced lift because of the growth of droplets by coalescence. The predicted lift height is sensitive to variations in the mass flow rate and inlet pressure. Inclusion of a coasting section, in which the drops would rise ballistically without change in temperature, may lead to increased lift within the existing range of operation.
CERN lifting equipment use authorisation
2004-01-01
Updated procedures to obtain authorisation to use lifting equipment at CERN have been put in place. As a general rule, lifting equipment at CERN may be operated only by qualified staff, i.e. those who have had intensive training in and adequate experience of using such equipment. However, for straightforward recurrent lifting operations, the Organization issues authorisations to operate lifting equipment at CERN to people who have followed a suitable course of training. The authorisation to use lifting equipment is valid for five years. More information about the procedures will be found at the following addresses: CERN Staff: http://sc-gs.web.cern.ch/sc-gs/gs_ms/ms/freq%20topics/te_mc_FT_staff.htm Associated members of the personnel (users, ...) : http://sc-gs.web.cern.ch/sc-gs/gs_ms/ms/freq%20topics/te_mc_FT_users.htm Contractors personnel : http://sc-gs.web.cern.ch/sc-gs/gs_ms/ms/freq%20topics/te_mc_FT_peoplefromext.htm In case of questions, please send a message to: securite...
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.
Phillip Burgers
Full Text Available 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.
Endoscopic brow lifts uber alles.
Patel, Bhupendra C K
2006-12-01
Innumerable approaches to the ptotic brow and forehead have been described in the past. Over the last twenty-five years, we have used all these techniques in cosmetic and reconstructive patients. We have used the endoscopic brow lift technique since 1995. While no one technique is applicable to all patients, the endoscopic brow lift, with appropriate modifications for individual patients, can be used effectively for most patients with brow ptosis. We present the nuances of this technique and show several different fixation methods we have found useful.
Fuel Cell-Powered Lift Truck Fleet Deployment Projects Final Technical Report May 2014
Klingler, James J [GENCO Infrastructure Solutions, Inc.
2014-05-06
The overall objectives of this project were to evaluate the performance, operability and safety of fork lift trucks powered by fuel cells in large distribution centers. This was accomplished by replacing the batteries in over 350 lift trucks with fuel cells at five distribution centers operated by GENCO. The annual cost savings of lift trucks powered by fuel cell power units was between $2,400 and $5,300 per truck compared to battery powered lift trucks, excluding DOE contributions. The greatest savings were in fueling labor costs where a fuel cell powered lift truck could be fueled in a few minutes per day compared to over an hour for battery powered lift trucks which required removal and replacement of batteries. Lift truck operators where generally very satisfied with the performance of the fuel cell power units, primarily because there was no reduction in power over the duration of a shift as experienced with battery powered lift trucks. The operators also appreciated the fast and easy fueling compared to the effort and potential risk of injury associated with switching heavy batteries in and out of lift trucks. There were no safety issues with the fueling or operation of the fuel cells. Although maintenance costs for the fuel cells were higher than for batteries, these costs are expected to decrease significantly in the next generation of fuel cells, making them even more cost effective.
49 CFR 178.970 - Bottom lift test.
2010-10-01
... permissible gross mass, the load being evenly distributed. (c) Test method. All Large Packaging design types must be raised and lowered twice by a lift truck with the forks centrally positioned and spaced at three quarters of the dimension of the side of entry (unless the points of entry are fixed). The...
Prosthetic Hand Lifts Heavy Loads
Carden, James R.; Norton, William; Belcher, Jewell G.; Vest, Thomas W.
1991-01-01
Prosthetic hand designed to enable amputee to lift diverse heavy objects like rocks and logs. Has simple serrated end effector with no moving parts. Prosthesis held on forearm by system of flexible straps. Features include ruggedness, simplicity, and relatively low cost.
Influences of Lorentz force on the hydrofoil lift
Yaohui Chen; Baochun Fan; Zhihua Chen; Hongzhi Li
2009-01-01
In this paper, Lorentz forces are proved to be able to suppress separation in flows over hydrofoils. Further-more, a differential equation of pressure distributions on the hydrofoil surface is derived, from which it is found that BVF (boundary vortex flux) cr is a suitable criterion for describing the lift coefficient variations during the electromagnetic control process. According to our numerical results, the peri-odic variations of lift for a hydrofoil at an attack angle of 17 o are analyzed and its inherent mechanism is discussed in detail with the concept of BVE On the other hand, the effects of Lorentz force on the hydrofoil's lift are investigated both experimentally and numerically for different magnitudes and locations.
Laser-induced forward transfer (LIFT) of congruent voxels
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.
49 CFR 37.203 - Lift maintenance.
2010-10-01
... 49 Transportation 1 2010-10-01 2010-10-01 false Lift maintenance. 37.203 Section 37.203... DISABILITIES (ADA) Over-the-Road Buses (OTRBs) § 37.203 Lift maintenance. (a) The entity shall establish a system of regular and frequent maintenance checks of lifts sufficient to determine if they are...
30 CFR 57.16016 - Lift trucks.
2010-07-01
... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Lift trucks. 57.16016 Section 57.16016 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND... § 57.16016 Lift trucks. Fork and other similar types of lift trucks shall be operated with the: (a...
30 CFR 56.16016 - Lift trucks.
2010-07-01
... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Lift trucks. 56.16016 Section 56.16016 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND....16016 Lift trucks. Fork and other similar types of lift trucks shall be operated with the— (a) Upright...
Protect Your Back: Guidelines for Safer Lifting.
Cantu, Carolyn O.
2002-01-01
Examines back injury in teachers and child care providers; includes statistics, common causes of back pain (improper alignment, improper posture, improper lifting, and carrying), and types of back pain (acute and chronic). Focuses on preventing back injury, body mechanics for lifting and carrying, and proper lifting and carrying of children. (SD)
The Effect of Lifting Speed on Cumulative and Peak Biomechanical Loading for Symmetric Lifting Tasks
Kasey O. Greenland
2013-06-01
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.
Simões BrunoAscenso
2010-01-01
Full Text Available The use of twistor methods in the study of Jacobi fields has proved quite fruitful, leading to a series of results. L. Lemaire and J. C. Wood proved several properties of Jacobi fields along harmonic maps from the two-sphere to the complex projective plane and to the three- and four-dimensional spheres, by carefully relating the infinitesimal deformations of the harmonic maps to those of the holomorphic data describing them. In order to advance this programme, we prove a series of relations between infinitesimal properties of the map and those of its twistor lift. Namely, we prove that isotropy and harmonicity to first order of the map correspond to holomorphicity to first order of its lift into the twistor space, relatively to the standard almost complex structures and . This is done by obtaining first-order analogues of classical twistorial constructions.
Lifting quasianalytic mappings over invariants
Rainer, Armin
2010-01-01
Let $\\rho : G \\to \\operatorname{GL}(V)$ be a rational finite dimensional complex representation of a reductive linear algebraic group $G$, and let $\\sigma_1,\\ldots,\\sigma_n$ be a system of generators of the algebra of invariant polynomials $\\mathbb{C}[V]^G$. We study the problem of lifting mappings $f : \\mathbb{R}^q \\supseteq U \\to \\sigma(V) \\subseteq \\mathbb{C}^n$ over the mapping of invariants $\\sigma=(\\sigma_1,\\ldots,\\sigma_n) : V \\to \\sigma(V)$. Note that $\\sigma(V)$ can be identified with the categorical quotient $V /\\!\\!/ G$ and its points correspond bijectively to the closed orbits in $V$. We prove that, if $f$ belongs to a quasianalytic subclass $\\mathcal{C} \\subseteq C^\\infty$ satisfying some mild closedness properties which guarantee resolution of singularities in $\\mathcal{C}$ (e.g.\\ the real analytic class), then $f$ admits a lift of the same class $\\mathcal{C}$ after desingularization by local blow-ups and local power substitutions. As a consequence we show that $f$ itself allows for a lift which...
Generalised Eisenhart lift of the Toda chain
Cariglia, Marco, E-mail: marco@iceb.ufop.br [DEFIS, Universidade Federal de Ouro Preto, Campus Morro do Cruzeiro, 35400-000 Ouro Preto, MG (Brazil); Gibbons, Gary, E-mail: g.w.gibbons@damtp.cam.ac.uk [DAMTP, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA (United Kingdom)
2014-02-15
The Toda chain of nearest neighbour interacting particles on a line can be described both in terms of geodesic motion on a manifold with one extra dimension, the Eisenhart lift, or in terms of geodesic motion in a symmetric space with several extra dimensions. We examine the relationship between these two realisations and discover that the symmetric space is a generalised, multi-particle Eisenhart lift of the original problem that reduces to the standard Eisenhart lift. Such generalised Eisenhart lift acts as an inverse Kaluza-Klein reduction, promoting coupling constants to momenta in higher dimension. In particular, isometries of the generalised lift metric correspond to energy preserving transformations that mix coordinates and coupling constants. A by-product of the analysis is that the lift of the Toda Lax pair can be used to construct higher rank Killing tensors for both the standard and generalised lift metrics.
Generalised Eisenhart lift of the Toda chain
Cariglia, Marco
2013-01-01
The Toda chain of nearest neighbour interacting particles on a line can be described both in terms of geodesic motion on a manifold with one extra dimension, the Eisenhart lift, or in terms of geodesic motion in a symmetric space with several extra dimensions. We examine the relationship between these two realisations and discover that the symmetric space is a generalised, multi-particle Eisenhart lift of the original problem, that reduces to the standard Eisenhart lift. Such generalised Eisenhart lift acts as an inverse Kaluza-Klein reduction, promoting coupling constants to momenta in higher dimension. In particular, isometries of the generalised lift metric correspond to energy preserving transformations that mix coordinates and coupling constants. A by-product of the analysis is that the lift of the Toda Lax pair can be used to construct higher rank Killing tensors for both the standard and generalised lift metrics.
Lift enhancement by bats' dynamically changing wingspan
Wang, Shizhao; Zhang, Xing; He, Guowei; Liu, Tianshu
2015-01-01
This paper elucidates the aerodynamic role of the dynamically changing wingspan in bat flight. Based on direct numerical simulations of the flow over a slow-flying bat, it is found that the dynamically changing wingspan can significantly enhance the lift. Further, an analysis of flow structures and lift decomposition reveal that the elevated vortex lift associated with the leading-edge vortices intensified by the dynamically changing wingspan considerably contributed to enhancement of the time-averaged lift. The nonlinear interaction between the dynamically changing wing and the vortical structures plays an important role in the lift enhancement of a flying bat in addition to the geometrical effect of changing the lifting-surface area in a flapping cycle. In addition, the dynamically changing wingspan leads to the higher efficiency in terms of generating lift for a given amount of the mechanical energy consumed in flight. PMID:26701882
Hasheminejad, S.M.
2017-04-03
Development of streamwise counter-rotating vortices induced by leading edge patterns with different pattern shape is investigated using hot-wire anemometry in the boundary layer of a flat plate. A triangular, sinusoidal and notched patterns with the same pattern wavelength λ of 15mm and the same pattern amplitude A of 7.5mm were examined for free-stream velocity of 3m/s. The results show a good agreement with earlier studies. The inflection point on the velocity profile downstream of the trough of the patterns at the beginning of the vortex formation indicates that the vortices non-linearly propagate downstream. An additional vortex structure was also observed between the troughs of the notched pattern.
Frewer, Michael
2016-01-01
The study by Oberlack et al. (2006) consists of two main parts: a direct numerical simulation (DNS) of a turbulent plane channel flow with streamwise rotation and a preceding Lie-group symmetry analysis on the two-point correlation equation (TPC) to analytically predict the scaling of the mean velocity profiles for different rotation rates. We will only comment on the latter part, since the DNS result obtained in the former part has already been commented on by Recktenwald et al. (2009), stating that the observed mismatch between DNS and their performed experiment is possibly due to the prescription of periodic boundary conditions on a too small computational domain in the spanwise direction. By revisiting the group analysis part in Oberlack et al. (2006), we will generate more natural scaling laws describing better the mean velocity profiles than the ones proposed. However, due to the statistical closure problem of turbulence, this improvement is illusive. As we will demonstrate, any arbitrary invariant scal...
WECS incompressible Lifting Surface Aerodynamics (WILSA)
Suciu, E.; Morino, L.
1976-05-01
A method is described for computing the distribution for a zero-thickness horizontal axis windmill, as well as for obtaining the power coefficient. The problem is formulated in terms of velocity potential, and the study deals with a nonlinear finite-element lifting-surface analysis of horizontal-axis windmills in a steady incompressible, inviscid, irrotational flow, with a prescribed helicoidal wake. A zero-order-finite-element analysis is used with a straight-vortex line wake. The correct wake geometry is obtained and the pressure coefficient calculated using both linearized and nonlinear forms of the Bernoulli Theorem. The numerical results compare well with those obtained with Windmill Incompressible Complex Configuration Aerodynamics (WICCA), a computer program for solving the same problem which uses a completely different integral equation. A number of suggestions are offered to improve the model presented.
Abdominal lift for laparoscopic cholecystectomy.
Gurusamy, Kurinchi Selvan; Koti, Rahul; Davidson, Brian R
2013-08-31
Laparoscopic cholecystectomy (key-hole removal of the gallbladder) is now the most often used method for treatment of symptomatic gallstones. Several cardiopulmonary changes (decreased cardiac output, pulmonary compliance, and increased peak airway pressure) occur during pneumoperitoneum, which is now introduced to allow laparoscopic cholecystectomy. These cardiopulmonary changes may not be tolerated in individuals with poor cardiopulmonary reserve. To assess the benefits and harms of abdominal wall lift compared to pneumoperitoneum in patients undergoing laparoscopic cholecystectomy. We searched the Cochrane Hepato-Biliary Group Controlled Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library, MEDLINE, EMBASE, and Science Citation Index Expanded until February 2013. We included all randomised clinical trials comparing abdominal wall lift (with or without pneumoperitoneum) versus pneumoperitoneum. We calculated the risk ratio (RR), rate ratio (RaR), or mean difference (MD) with 95% confidence intervals (CI) based on intention-to-treat analysis with both the fixed-effect and the random-effects models using the Review Manager (RevMan) software. For abdominal wall lift with pneumoperitoneum versus pneumoperitoneum, a total of 130 participants (all with low anaesthetic risk) scheduled for elective laparoscopic cholecystectomy were randomised in five trials to abdominal wall lift with pneumoperitoneum (n = 53) versus pneumoperitoneum only (n = 52). One trial which included 25 people did not state the number of participants in each group. All five trials had a high risk of bias. There was no mortality or conversion to open cholecystectomy in any of the participants in the trials that reported these outcomes. There was no significant difference in the rate of serious adverse events between the two groups (two trials; 2/29 events (0.069 events per person) versus 2/29 events (0.069 events per person); rate ratio 1.00; 95% CI 0
Krajewski diagrams and spin lifts
Schücker, T
2005-01-01
A classification of irreducible, dynamically non-degenerate, almost commutative spectral triples is refined. It is extended to include centrally extended spin lifts. Simultaneously it is reduced by imposing three constraints: (i) the condition of vanishing Yang-Mills and mixed gravitational anomalies, (ii) the condition that the fermion representation be complex under the little group, while (iii) massless fermions are to remain neutral under the little group. These constraints single out the standard model with one generation of leptons and quarks and with an arbitrary number of colours.
Training for lifting; an unresolved ergonomic issue?
Sedgwick, A W; Gormley, J T
1998-10-01
The paper describes a nine year project on lifting training which included nine trans-Australia consensus conferences attended by more than 900 health professionals. Major outcomes were: (1) The essence of lifting work is the need for the performer to cope with variability in task, environment, and self, and the essence of lifting skill is therefore adaptability; (2) the semi-squat approach provides the safest and most effective basis for lifting training; (3) for lifting training to be effective, the basic principles of skill learning must be systematically applied, with adaptability as a specific goal; (4) physical work capacity (aerobic power, strength, endurance, joint mobility) is a decisive ingredient of safe and effective lifting and, in addition to skill learning, should be incorporated in the training of people engaging regularly in heavy manual work; (5) if effective compliance with recommended skilled behaviour is to be achieved, then training must apply the principles and methods appropriate to adult learning and behaviour modification.
Lowering the Error Floor of LDPC Codes Using Cyclic Liftings
Asvadi, Reza; Ahmadian-Attari, Mahmoud
2010-01-01
Cyclic liftings are proposed to lower the error floor of low-density parity-check (LDPC) codes. The liftings are designed to eliminate dominant trapping sets of the base code by removing the short cycles which form the trapping sets. We derive a necessary and sufficient condition for the cyclic permutations assigned to the edges of a cycle $c$ of length $\\ell(c)$ in the base graph such that the inverse image of $c$ in the lifted graph consists of only cycles of length strictly larger than $\\ell(c)$. The proposed method is universal in the sense that it can be applied to any LDPC code over any channel and for any iterative decoding algorithm. It also preserves important properties of the base code such as degree distributions, encoder and decoder structure, and in some cases, the code rate. The proposed method is applied to both structured and random codes over the binary symmetric channel (BSC). The error floor improves consistently by increasing the lifting degree, and the results show significant improvemen...
Constraint Processing in Lifted Probabilistic Inference
Kisynski, Jacek
2012-01-01
First-order probabilistic models combine representational power of first-order logic with graphical models. There is an ongoing effort to design lifted inference algorithms for first-order probabilistic models. We analyze lifted inference from the perspective of constraint processing and, through this viewpoint, we analyze and compare existing approaches and expose their advantages and limitations. Our theoretical results show that the wrong choice of constraint processing method can lead to exponential increase in computational complexity. Our empirical tests confirm the importance of constraint processing in lifted inference. This is the first theoretical and empirical study of constraint processing in lifted inference.
Yoshida lifts and Selmer groups
Böcherer, Siegfried; Schulze-Pillot, Rainer
2010-01-01
Let $f$ and $g$, of weights $k'>k\\geq 2$, be normalised newforms for $\\Gamma_0(N)$, for square-free $N>1$, such that, for each Atkin-Lehner involution, the eigenvalues of $f$ and $g$ are equal. Let $\\lambda\\mid\\ell$ be a large prime divisor of the algebraic part of the near-central critical value $L(f\\otimes g,\\frac{k+k'-2}{2})$. Under certain hypotheses, we prove that $\\lambda$ is the modulus of a congruence between the Hecke eigenvalues of a genus-two Yoshida lift of (Jacquet-Langlands correspondents of) $f$ and $g$ (vector-valued in general), and a non-endoscopic genus-two cusp form. In pursuit of this we also give a precise pullback formula for a genus-four Eisenstein series, and a general formula for the Petersson norm of a Yoshida lift. Given such a congruence, using the $4$-dimensional $\\lambda$-adic Galois representation attached to a genus-two cusp form, we produce, in an appropriate Selmer group, an element of order $\\lambda$, as required by the Bloch-Kato conjecture on values of $L$-functions. (Her...
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
Isolated neck-lifting procedure: isolated stork lift.
Barbarino, Sheila C; Wu, Allan Y; Morrow, David M
2013-04-01
Many patients desire cosmetic improvement of neck laxity when consulting with a plastic surgeon about their face. Neck laxity and loss of the cervicomental angle can be due to multiple components of aging such as skin quality/elasticity, loss of platysma muscle tone, and submental fat accumulation. Traditionally, the procedure of choice for patients with an aging lower face and neck is a cervicofacial rhytidectomy. However, occasionally, a patient wishes to have no other facial surgery than an improvement of their excessive skin of the anterior, lateral, and/or posterior neck. In other instances, a patient may present with having had a face/neck-lifting procedure that left objectionable vertical/diagonal lines at the lateral neck. In both these instances, a surgeon should consider an isolated stork lift (ISL) procedure. An ISL procedure avoids and/or corrects problematic vertical/diagonal lateral neck folds by "walking" the excess skin flaps around the posterior inferior occipital hairline bilaterally, bringing the flaps together at the lateral and posterior neck, which sometimes involves a midline posterior dart excision of the dog ear. A patient presenting with excessive skin of the neck (anterior, lateral, and/or posterior) and/or residual vertical/diagonal skin folds is an excellent candidate for the ISL. The ISL procedure was performed on 273 patients over a 2-year period at The Morrow Institute. Patients were included if they had excessive skin of the anterior, lateral, and/or posterior neck and/or diagonal/vertical lateral bands and did not desire a full face-lifting procedure. Patients were excluded from this study if they would not accept having longer hair in order to cover the scar along the posterior inferior occipital hairline or a midline T-flap skin closure scar at the base of the posterior midline neck. Under a combination of local anesthesia and IV sedation, a postauricular face-lift incision was made that was extended in a circumoccipital fashion
33 CFR 118.85 - Lights on vertical lift bridges.
2010-07-01
... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Lights on vertical lift bridges... BRIDGES BRIDGE LIGHTING AND OTHER SIGNALS § 118.85 Lights on vertical lift bridges. (a) Lift span lights. The vertical lift span of every vertical lift bridge shall be lighted so that the center of the...
Energy Dissipation Distribution in a Draft Tube-lifted Gas-Solid Air Loop Reactor%中心气升式气固环流反应器中的能耗分布
沈志远; 杨利军; 刘梦溪; 卢春喜
2012-01-01
Based on the energy balance, an energy dissipation rate model of different regions of a draft tube-lifted gas-solid air loop reactor (GSALR) was established. The local particle velocity, bed density and pressure drop were measured in a cold model GSALR and the model parameters were obtained based on the experimental data. The predictions agree with experimental data. The predicted results show that nearly 40% and 30% of the energy dissipation rate occur in the annulus and gas-solid separation regions, while that in the draft tube and gas distributors region is relatively small, reaching a sum of nearly 30%. With increasing of the draft tube gas velocity, the ratio of individual region to global reactor energy dissipation rate decreases for the annulus region, increases for the gas-solid separation region, and basically remains constant for the draft tube and gas distributor affecting regions. Compared with that obtained in an annulus-lifted GSALR, the location of gas distributor has a significant influence on energy dissipation, the flow resistance is smaller in the draft tube-lifted GSALR.%基于能量平衡,推导出计算中心气升式气固环流反应器中不同区域内气固混合物流动能耗的理论模型,测量了不同区域内固相颗粒速度、气固混合物密度及床层压降,并根据实验数据确定出相应的模型参数,模型计算与实验结果吻合较好.模型计算表明,中心气升式气固环流反应器内环隙区和气固分离区的能耗分别占反应器总能耗的近40％和30％,颗粒环流受到的阻力主要集中在这2个区域;而导流筒区及分布器影响区能耗较小,共占总能耗的近30％.随导流筒区表观气速增加,环隙区能耗占总能耗的比重减小,气固分离区能耗所占比重增大,导流筒区和分布器影响区能耗基本保持不变.气体分布器的安装位置对反应器内能量消耗的分布影响较大,中心气升式气固环流反应器内流动阻力更小.
CNOOC Lifts 2011 Production Target
2011-01-01
@@ China National Offshore Oil Corporation (CNOOC), China's top offshore oil and gas producer, has lifted its 2011 production target by up to 11 percent as new projects at home and overseas come on stream.The offshore oil giant, with a market capitalization of about US$105 billion, said in a statement released in late January 2011 that it aimed to produce between 355 and 365 million barrels of oil equivalent (BOE).Oil prices climbed 15 percent in 2010 on the back of expectations that a global economic recovery will drive the demand.Analysts are similarly bullish for 2011, predicting crude prices to trade at around US$100 for the year.CNOOC, the smallest of China's triumvirate of energy companies that also includes CNPC and Sinopee, said it targeted US$8.8 billion in capital expenditure for 2011.
Tischler, M. B.; Ringland, R. F.; Jex, H. R.
1983-01-01
The basic aerodynamic and dynamic properties of an example heavy-lift airship (HLA) configuration are analyzed using a nonlinear, multibody, 6-degrees-of-freedom digital simulation. The slung-payload model is described, and a preliminary analysis of the coupled vehicle-payload dynamics is presented. Trim calculations show the importance of control mixing selection and suggest performance deficiencies in crosswind stationkeeping for the unloaded example HLA. Numerically linearized dynamics of the unloaded vehicle exhibit a divergent yaw mode and an oscillatory pitch mode whose stability characteristic is sensitive to flight speed. An analysis of the vehicle-payload dynamics shows significant coupling of the payload dynamics with those of the basic HLA. It is shown that significant improvement in the vehicle's dynamic behavior can be achieved with the incorporation of a simple flight controller having proportional, rate, and integral-error feedbacks.
Lip Lifting: Unveiling Dental Beauty.
Stanley, Kyle; Caligiuri, Matthew; Schlichting, Luís Henrique; Bazos, Panaghiotis K; Magne, Michel
2017-01-01
The focus for the achievement of complete success in the esthetic zone has traditionally been on addressing deficiencies of intraoral hard and soft tissue. Often, these deficiencies are accompanied by esthetic concerns regarding the lips that are routinely neglected by the dental team. A predictable plastic surgery technique - the lip lift - has been used for decades to enhance lip esthetics by shortening the senile upper lip to achieve a more youthful appearance. Over the years, this technique has been refined and used in many different ways, allowing its routine incorporation into full facial esthetic planning. Through restoration of the upper lip to its optimal position, the artistry of the dentist and dental technician can truly be appreciated in the rejuvenated smile. By the introduction of this minimally invasive surgical technique to the dental community, patients stand to benefit from a comprehensive orofacial approach to anterior dental esthetic planning.
丁凤丽
2007-01-01
<正>Many people hurt their backs when they try to lift heavy things from the floor. It is easy to hurt your back muscles when you pick up a heavy object. However, there is a correct way to lift things from the floor. If you pick up big or heavy objects correctly, you probably will not hurt your back.
Improving Grading Consistency through Grade Lift Reporting
Millet, Ido
2010-01-01
We define Grade Lift as the difference between average class grade and average cumulative class GPA. This metric provides an assessment of how lenient the grading was for a given course. In 2006, we started providing faculty members individualized Grade Lift reports reflecting their position relative to an anonymously plotted school-wide…
Soccer Ball Lift Coefficients via Trajectory Analysis
Goff, John Eric; Carre, Matt J.
2010-01-01
We performed experiments in which a soccer ball was launched from a machine while two high-speed cameras recorded portions of the trajectory. Using the trajectory data and published drag coefficients, we extracted lift coefficients for a soccer ball. We determined lift coefficients for a wide range of spin parameters, including several spin…
Soccer Ball Lift Coefficients via Trajectory Analysis
Goff, John Eric; Carre, Matt J.
2010-01-01
We performed experiments in which a soccer ball was launched from a machine while two high-speed cameras recorded portions of the trajectory. Using the trajectory data and published drag coefficients, we extracted lift coefficients for a soccer ball. We determined lift coefficients for a wide range of spin parameters, including several spin…
Effect of Streamwise Fences on Secondary Flows and Losses in a Twod-imensional Turbine Rotor Cascade
M. Govardhan; A. Rajender; J.P. Umang
2006-01-01
To control secondary flows,streamwise fences were attached to end wall of a linear turbine rotor cascade.The cascade had 8 blades of 400 mm long and 175 mm chord.The blades deflected the flow by 120°.The fences were madeout of 0.7 mm thick brass sheet and the heights of the fences were 14 mm,18 mm respectively.The curvature of the fences was the same as that of the blade camber line.The fences were fixed normal to the end wall and at half pitch away from the blades.The experimental program consists of total pressure,static pressure measurements at the inlet and outlet of the cascade,by using five-hole probe.In addition,static pressure on the blade suction surface and pressure surface was also obtained.Fences are effective in preventing the movement of the pressure side leg of the horseshoe vortex.Consequently the accumulation of low energy fluid on the suction surface is minimised.End wall losses are reduced by the fences due to weakening of the end wall cross flow.
Occupational lifting and pelvic pain during pregnancy:
Larsen, Pernille Stemann; Strandberg-Larsen, Katrine; Juhl, Mette;
2013-01-01
OBJECTIVES: Pelvic pain during pregnancy is a common ailment, and the disease is a major cause of sickness absence during pregnancy. It is plausible that occupational lifting may be a risk factor of pelvic pain during pregnancy, but no previous studies have examined this specific exposure. The aim...... of this study was to examine the association between occupational lifting and pelvic pain during pregnancy. METHODS: The study comprised 50 143 pregnant women, enrolled in the Danish National Birth Cohort in the period from 1996-2002. During pregnancy, the women provided information on occupational lifting...... (weight load and daily frequency), and six months post partum on pelvic pain. Adjusted odds ratios for pelvic pain during pregnancy according to occupational lifting were calculated by logistic regression. RESULTS: Any self-reported occupational lifting (>1 time/day and loads weighing >10 kg...
Lift conference | 5-7 February
2014-01-01
Since 2006, Lift Events explore the business and social implications of new technologies through the organisation of international event series and open innovation programs in Europe, Asia and America. The next conference will be held on 5-7 February in Geneva. (Image: © Lift Conference) The Lift Conference is one of the leading conferences on innovation in Europe and a key annual meeting for individuals and organizations wishing to understand and anticipate trends and innovation. Held every year in February in Geneva (5-7 February 2014), the Lift Conference is a three-day event consisting of talks, interactive workshops, exhibitions, and discussions bringing together over 1’000 participants from all society’s sectors and industries in a dynamic and informal environment with the aim to learn, connect, share and leverage innovation opportunities. Extraordinary speakers will take to the stage at Lift14: Porter Erisman, former VP of Alibaba.com turned...
Lambda-Lifting in Quadratic Time
Danvy, Olivier; Schultz, Ulrik Pagh
2002-01-01
Lambda-lifting is a program transformation that is used in compilers, partial evaluators, and program transformers. In this article, we show how to reduce its complexity from cubic time to quadratic time, and we present a flow-sensitive lambda-lifter that also works in quadratic time. Lambda-lifting...... that yields the cubic factor in the traditional formulation of lambda-lifting, which is due to Johnsson. This search is carried out by computing a transitive closure. To reduce the complexity of lambda-lifting, we partition the call graph of the source program into strongly connected components, based...... of lambda-lifting from O(n^3) to O(n^2) . where n is the size of the program. Since a lambda-lifter can output programs of size O(n^2), our algorithm is asympotically optimal....
Lambda-Lifting in Quadratic Time
Danvy, Olivier; Schultz, Ulrik Pagh
2004-01-01
Lambda-lifting is a program transformation that is used in compilers, partial evaluators, and program transformers. In this article, we show how to reduce its complexity from cubic time to quadratic time, and we present a flow-sensitive lambda-lifter that also works in quadratic time. Lambda-lifting...... that yields the cubic factor in the traditional formulation of lambda-lifting, which is due to Johnsson. This search is carried out by computing a transitive closure. To reduce the complexity of lambda-lifting, we partition the call graph of the source program into strongly connected components, based...... of lambda-lifting from O(n^3) to O(n^2) . where n is the size of the program. Since a lambda-lifter can output programs of size O(n^2), our algorithm is asympotically optimal....
Lambda-Lifting in Quadratic Time
Danvy, Olivier; Schultz, Ulrik Pagh
2003-01-01
Lambda-lifting is a program transformation that is used in compilers, partial evaluators, and program transformers. In this article, we show how to reduce its complexity from cubic time to quadratic time, and we present a flow-sensitive lambda-lifter that also works in quadratic time. Lambda-lifting...... that yields the cubic factor in the traditional formulation of lambda-lifting, which is due to Johnsson. This search is carried out by computing a transitive closure. To reduce the complexity of lambda-lifting, we partition the call graph of the source program into strongly connected components, based...... of lambda-lifting from O(n^3) to O(n^2) . where n is the size of the program. Since a lambda-lifter can output programs of size O(n^2), our algorithm is asympotically optimal....
Lambda-lifting in Quadratic Time
Danvy, O.; Schultz, U.P.
2004-01-01
Lambda-lifting is a program transformation that is used in compilers, partial evaluators, and program transformers. In this article, we show how to reduce its complexity from cubic time to quadratic time, and we present a flow-sensitive lambda-lifter that also works in quadratic time. Lambda-lifting...... that yields the cubic factor in the traditional formulation of lambda-lifting, which is due to Johnsson. This search is carried out by computing a transitive closure. To reduce the complexity of lambda-lifting, we partition the call graph of the source program into strongly connected components, based...... of lambda-lifting from O(n^3) to O(n^2) . where n is the size of the program. Since a lambda-lifter can output programs of size O(n^2), our algorithm is asympotically optimal....
Lifting index of the niosh lifting equation and low back pain
Eliana Remor Teixeira
2011-09-01
Full Text Available The purpose of this study is to assess the relationship of the Lifting Index obtained through the application of the NIOSH Lifting Equation and the incidence of low back pain among forty-eight workers involved in manual lifting tasks. It was applied the equation in eleven tasks and the workers were interviewed. The most unfavorable conditions presented themselves in the lifting destination. The variables that most contributed to the inadequate values of the Lifting Index were: the horizontal location, the lifting frequency and the vertical distance, beyond the high weight of the load. The incidence of low back pain in the last twelve months was 19%, whereas the incidence of work-related low back pain in the same period was 10%. In 72.7% of the tasks evaluated the Composite Lifting Index was more than three, which are considered as high ergonomic risk.
Occupational lifting of heavy loads and preterm birth:
Runge, Stine Bjerrum; Pedersen, Jacob Krabbe; Svendsen, Susanne Wulff
2013-01-01
To examine the association between occupational lifting during pregnancy and preterm birth. The risk of preterm birth was estimated for total burden lifted per day and number of medium and heavy loads lifted per day.......To examine the association between occupational lifting during pregnancy and preterm birth. The risk of preterm birth was estimated for total burden lifted per day and number of medium and heavy loads lifted per day....
Development of predictive equations for lifting strengths.
Kumar, S
1995-10-01
The purpose of the study was to determine relationship between lifting strengths of male and female subjects and body posture, type of lift (stoop or squat) and velocity of lift. Thirty normal young adults (18 males and 12 females) volunteered for the study. All subjects were required to perform a total of 56 tasks. Of these, 28 were stoop lifts and 28 were squat lifts. In each of the categories of stoop and squat lifts, the strengths were tested in standard posture, isokinetic (linear velocity of 500 mm/s), and isometric modes at half, three-quarters and full horizontal individual reach distances in sagittal, 30 degrees lateral and 60 degrees lateral planes. The strengths were measured using a static dynamic strength tester with a load cell and an IBM microcomputer with an A/D card. The peak and average strength values were extracted and statistically compared across conditions and gender (ANOVA). Finally a multiple regression analysis was carried out to predict strength as a function of reach, posture and velocity of lift. The ANOVA revealed a highly significant effect of gender, reach, plane and velocity (p capabilities for industrial application based on simple anthropometric and strength characteristics.
Cost Benefit Analysis of Boat Lifts
2014-09-01
to avoid the potential of mishaps due to jumping across open water to reach both sides of the lift. With the life expectancy of a boat ramp...to jumping across open water to reach both sides of the lift. Cost Benefit Analysis of Boat Lifts 11 UNCLAS//Public | CG-926 R&DC | B. Fike...equipment from boats and craft that have been corrosion problems in the past. such as wire rope and non-stainless steel hardware. Corrosion is a function
Database queries and constraints via lifting problems
Spivak, David I
2012-01-01
Previous work has shown a tight relationship between databases and categories. In the present paper we extend that connection to show that certain queries and constraints correspond to the algebro-topological notion of lifting problems. In our formulation, each so-called SPARQL graph pattern query corresponds to a lifting problem, and each solution to the query corresponds to a lift. We interpret constraints within the same formalism and then investigate some formal properties of queries and constraints, e.g. their behavior under data migration functors.
Laser-induced forward transfer (LIFT) of congruent voxels
Piqué, Alberto, E-mail: pique@nrl.navy.mil [Materials Science and Technology Division, Code 6364, Naval Research Laboratory, Washington, DC 20375 (United States); Kim, Heungsoo; Auyeung, Raymond C.Y.; Beniam, Iyoel [Materials Science and Technology Division, Code 6364, Naval Research Laboratory, Washington, DC 20375 (United States); Breckenfeld, Eric [National Research Council Fellow at the Naval Research Laboratory, Washington, DC 20375 (United States)
2016-06-30
Highlights: • Laser-induced forward transfer (LIFT) is demonstrated with high viscosity Ag nanopaste. • Under the right conditions (viscosity and fluence) the transfer of congruent voxels was achieved. • For viscosities under 100 Pa s, congruent voxel transfer of silver nano-suspensions is only possible under a very narrow range of conditions. • For viscosities over 100 Pa s, congruent voxel transfer of silver nano-pastes works over a wider range of fluences, donor substrate thickness, gap distances and voxel areas. • The laser transfer of congruent voxels can be used for printing electronic patterns in particular interconnects. - Abstract: 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
Lambda-Lifting in Quadratic Time
Danvy, Olivier; Schultz, Ulrik Pagh
2002-01-01
Lambda-lifting is a program transformation used in compilers and in partial evaluators and that operates in cubic time. In this article, we show how to reduce this complexity to quadratic time. Lambda-lifting transforms a block-structured program into a set of recursive equations, one for each...... local function in the source program. Each equation carries extra parameters to account for the free variables of the corresponding local function and of all its callees. It is the search for these extra parameters that yields the cubic factor in the traditional formulation of lambda-lifting, which...... is not needed. We therefore simplify the search for extra parameters by treating each strongly connected component instead of each function as a unit, thereby reducing the time complexity of lambda-lifting from O(n 3 log n)toO(n2 log n), where n is the size of the program. Since a lambda-lifter can output...
Lower complexity bounds for lifted inference
Jaeger, Manfred
2015-01-01
instances of the model. Numerous approaches for such “lifted inference” techniques have been proposed. While it has been demonstrated that these techniques will lead to significantly more efficient inference on some specific models, there are only very recent and still quite restricted results that show...... the feasibility of lifted inference on certain syntactically defined classes of models. Lower complexity bounds that imply some limitations for the feasibility of lifted inference on more expressive model classes were established earlier in Jaeger (2000; Jaeger, M. 2000. On the complexity of inference about...... that under the assumption that NETIME≠ETIME, there is no polynomial lifted inference algorithm for knowledge bases of weighted, quantifier-, and function-free formulas. Further strengthening earlier results, this is also shown to hold for approximate inference and for knowledge bases not containing...
Spherical projections and liftings in geometric tomography
Goodey, Paul; Kiderlen, Markus; Weil, Wolfgang
2011-01-01
We consider a variety of integral transforms arising in Geometric Tomography. It will be shown that these can be put into a common framework using spherical projection and lifting operators. These operators will be applied to support functions and surface area measures of convex bodies and to rad......We consider a variety of integral transforms arising in Geometric Tomography. It will be shown that these can be put into a common framework using spherical projection and lifting operators. These operators will be applied to support functions and surface area measures of convex bodies...... and to radial functions of star bodies. We then investigate averages of lifted projections and show that they correspond to self-adjoint intertwining operators. We obtain formulas for the eigenvalues of these operators and use them to ascertain circumstances under which tomographic measurements determine...... the original bodies. This approach via mean lifted projections leads us to some unexpected relationships between seemingly disparate geometric constructions....
Lifting scheme of symmetric tight wavelets frames
ZHUANG BoJin; YUAN WeiTao; PENG LiZhong
2008-01-01
This paper proposes a method to realize the lifting scheme of tight frame wavelet filters. As for 4-channel tight frame wavelet filter, the tight frame transforms' ma-trix is 2×4, but the lifting scheme transforms' matrix must be 4×4. And in the case of 3-channel tight frame wavelet filter, the transforms' matrix is 2×3, but the lifting scheme transforms' matrix must be 3×3. In order to solve this problem, we intro-duce two concepts: transferred polyphase matrix for 4-channel filters and trans-ferred unitary matrix for 3-channel filters. The transferred polyphase matrix is sym-metric/antisymmetric. Thus, we use this advantage to realize the lifting scheme.
Experimental determination of baseball spin and lift.
Alaways, L W; Hubbard, M
2001-05-01
The aim of this study was to develop a new method for the determination of lift on spinning baseballs. Inertial trajectories of (a) ball surface markers during the first metre of flight and (b) the centre of mass trajectory near home-plate were measured in a pitch using high-speed video. A theoretical model was developed, incorporating aerodynamic Magnus-Robins lift, drag and cross forces, which predicts the centre of mass and marker trajectories. Parameters including initial conditions and aerodynamic coefficients were estimated iteratively by minimizing the error between predicted and measured trajectories. We compare the resulting lift coefficients and spin parameter values with those of previous studies. Lift on four-seam pitches can be as much as three times that of two-seam pitches, although this disparity is reduced for spin parameters greater than 0.4.
Design of heavy lift cargo aircraft
National Aeronautics and Space Administration — This is the bird of the skies of the future. The heavy lift cargo aircraft which is currently being developed by me has twice the payload capacity of an Antonov...
Integrated lift/drag controller for aircraft
Olcott, J. W.; Seckel, E.; Ellis, D. R. (Inventor)
1974-01-01
A system for altering the lift/drag characteristics of powered aircraft to provide a safe means of glide path control includes a control device integrated for coordination action with the aircraft throttle. Such lift/drag alteration devices as spoilers, dive brakes, and the like are actuated by manual operation of a single lever coupled with the throttle for integrating, blending or coordinating power control. Improper operation of the controller is inhibited by safety mechanisms.
Effect of 3D stall-cells on the pressure distribution of a laminar NACA64-418 wing
Ragni, Daniele; Ferreira, Carlos
2016-08-01
A 3D stall-cell flow-field has been studied in a 4.8 aspect-ratio wing obtained by linear extrusion of a laminar NACA64-418 airfoil profile. The span-wise change in the velocity and pressure distribution along the wing has been quantified with respect to the development of cellular structures from 8° to 20° angle of attack. Oil-flow visualizations help localizing the regular cellular pattern in function of the angle of attack. Multi-plane stereoscopic PIV measurements obtained by traversing the entire setup along the wing span show that the flow separation is not span-wise uniform. The combination of different stereoscopic fields into a 3D volume of velocity data allows studying the global effect of the stall-cell pattern on the wing flow. Integration of the experimentally computed pressure gradient from the Navier-Stokes equation is employed to compute the span-wise distribution of the mean surface pressure. Comparison of the results with the ones obtained from pressure taps installed in the wing evidences a span-wise periodic loading on the wing. The periodic loading has maxima confined in the stream-wise direction between the location of the highest airfoil curvature and the one of the airfoil flow separation. Estimation of the periodic loading is found within 2-6 % of the sectional wing lift.
Plunger lift analysis, troubleshooting and optimization
Rowlan, O.L.; McCoy, J.N. [Echometer Co., Wichita Falls, TX (United States); Podio, A.L. [Texas Univ. at Austin, Austin, TX (United States)
2007-07-01
Plunger lifting is used to lift liquids such as condensates, water and oil from liquid loaded gas wells. This paper described a portable system designed to monitor gas plunger lift. The system digitized, stored and processed acoustic pulse signals generated by the plunger as it fell through each tubing collar recess when the well was shut in. Data were used to determine depth; fall velocity; the amount of appropriate cycle times for optimum operation; and the volume and rate of gas flowing into the well. The stored signals were then used to determine plunger position, plunger fall velocity, and plunger arrival at the liquid level in the tubing. Analysis of the data were used to optimize and troubleshoot the operation of plunger lifted wells. Examples of various operational problems encountered during the operation of the plunger lift system were also provided. It was concluded that the monitoring system increases the safety of plunger lift operations by allowing operators to know the exact placement of the plunger. 5 refs., 1 tab., 17 figs.
刘璐璐; 张军; 翟树成; 张国平
2015-01-01
The analysis of detailed flow structure of a turbulent boundary layer is of great significance for establishing the link among the detailed flow structure characteristics, flow noise and wall friction, which can help lay the foundation for deeper research of the drag and noise reduction mechanism. PIV (particle image velocimetry) technique is applied in this paper to study the hairpin vortex signatures in the streamwise-spanwise plane in turbulent boundary layer flow on a flat plate. The experiment successfully identifies low-speed streaks from PIV instantaneous velocity field and the distributions of spanwise spacing of low-speed streaks along with wall-normal distance and Reynolds number are obtained through statistical analysis in the logarithmic layer. Meanwhile, the counter-rotating vortices surrounding the long low-speed streaks in the streamwise-spanwise plane are extracted through vortex identification criterion, which reveals the relationship between hairpin packets and long low-speed streaks. Besides, this paper performs a research about the distribution of spanwise spacing of hairpin vortex legs, considering various wall-normal distances and the effect of Reynolds numbers.%研究湍流边界层精细流动结构特征，有助于建立流动结构特征与壁面摩阻、流噪声之间的关联，从而为湍流边界层减阻降噪机理的深层次研究奠定基础。该文应用PIV（粒子图像测速）技术，对平板湍流边界层中发卡涡在流向-展向平面的涡迹特征进行研究。利用PIV瞬时速度场，捕捉到明显的低速条带，通过统计分析获得对数层范围低速条带间距随壁面法向距离的变化以及雷诺数的影响规律。同时，通过涡识别准则，提取在流向-展向平面内长低速条带两侧的反向漩涡带，揭示了发卡涡包与长低速条带的内在关系。此外，还研究了流向-展向平面发卡涡涡腿间距随壁面法向距离的变化规律以及雷诺数的影响。
14 CFR 25.697 - Lift and drag devices, controls.
2010-01-01
... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Lift and drag devices, controls. 25.697....697 Lift and drag devices, controls. (a) Each lift device control must be designed so that the pilots....101(d). Lift and drag devices must maintain the selected positions, except for movement produced by an...
Analysis of sand particles' lift-off and incident velocities in wind-blown sand flux
Tian-Li Bo; Xiao-Jing Zheng; Shao-Zhen Duan; Yi-Rui Liang
2013-01-01
In the research of windblown sand movement,the lift-off and incident velocities of saltating sand particles play a significant role in bridging the spatial and temporal scales from single sand particle's motion to windblown sand flux.In this paper,we achieved wind tunnel measurements of the movement of sand particles near sand bed through improving the wind tunnel experimental scheme of paticle image velocimetry (PIV) and data processing method.And then the influence of observation height on the probability distributions of lift-off and incident velocities of sand particles was analyzed.The results demonstrate that the observation height has no obvious influence on the distribution pattern of the lift-off and incident velocities of sand particles,i.e.,the probability distribution of horizontal and vertical velocities of lift-off and incident sand particles follow a Gaussian distribution and a negative exponential distribution,respectively.However,it influences the center of the Gaussian distribution,the decay constant and the amplitude of the negative exponential distribution.
Research on the aerodynamic characteristics of a lift drag hybrid vertical axis wind turbine
Xiaojing Sun
2016-01-01
Full Text Available Compared with a drag-type vertical axis wind turbines, one of the greatest advantages for a lift-type vertical axis wind turbines is its higher power coefficient (Cp. However, the lift-type vertical axis wind turbines is not a self-starting turbine as its starting torque is very low. In order to combine the advantage of both the drag-type and the lift-type vertical axis wind turbines, a lift drag hybrid vertical axis wind turbines was designed in this article and its aerodynamics and starting performance was studied in detail with the aid of computational fluid dynamics simulations. Numerical results indicate that the power coefficient of this lift drag hybrid vertical axis wind turbines declines when the distance between its drag-type blades and the center of rotation of the turbine rotor increases, whereas its starting torque can be significantly improved. Studies also show that unlike the lift-type vertical axis wind turbines, this lift drag hybrid-type vertical axis wind turbines could be able to solve the problem of low start-up torque. However, the installation position of the drag blade is very important. If the drag blade is mounted very close to the spindle, the starting torque of the lift drag hybrid-type vertical axis wind turbines may not be improved at all. In addition, it has been found that the power coefficient of the studied vertical axis wind turbines is not as good as expected and possible reasons have been provided in this article after the pressure distribution along the surfaces of the airfoil-shaped blades of the hybrid turbine was analyzed.
2012-04-05
... National Highway Traffic Safety Administration 49 CFR Part 571 RIN 2127-AJ93 Federal Motor Vehicle Safety Standards; Platform Lifts for Motor Vehicles; Platform Lift Installations in Motor Vehicles AGENCY: National.... SUMMARY: This document adopts amendments to the Federal motor vehicle safety standards on platform...
CERN Bulletin
2010-01-01
The Communication Group is organising a competition offering people at CERN the chance to submit their ideas and win a ticket to the Lift10 Conference, which will be held in Geneva from 5 to7 May. Lift is a community of technology "pioneers", created in 2006. It now involves more than 4,000 people from over 60 countries, who meet regularly in Europe and in Asia to explore the social implications of new technologies and the major shifts ahead. CERN is one of the academic partners of the next Lift conference, whose theme is "Connected people”. For this occasion, 10 free tickets to the conference will be awarded to the "CERNois" who come up with the best answers to the question: “How would you contribute to Lift10?” Those taking part in the competition can choose from among the following categories: - run workshop(s); - cover the conference on a blog; - coordinate a discussion during the breaks; - organize a lift@home ...
Lift and wakes of flying snakes
Krishnan, Anush; Vlachos, Pavlos P; Barba, L A
2013-01-01
Flying snakes use a unique method of aerial locomotion: they jump from tree branches, flatten their bodies and undulate through the air to produce a glide. The shape of their body cross-section during the glide plays an important role in generating lift. This paper presents a computational investigation of the aerodynamics of the cross-sectional shape. We performed two-dimensional simulations of incompressible flow past the anatomically correct cross-section of the species Chrysopelea paradisi, showing that a significant enhancement in lift appears at an angle of attack of 35 degrees, above Reynolds numbers 2000. Previous experiments on physical models also obtained an increased lift, at the same angle of attack. The flow is inherently three-dimensional in physical experiments, due to fluid instabilities, and it is thus intriguing that the enhanced lift appears also in the two-dimensional simulations. The simulations point to the lift enhancement arising from the early separation of the boundary layer on the ...
Precision markedly attenuates repetitive lift capacity.
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.
Facial thread lifting with suture suspension.
Tavares, Joana de Pinho; Oliveira, Carlos Augusto Costa Pires; Torres, Rodolfo Prado; Bahmad, Fayez
2017-05-09
The increased interest in minimally-invasive treatments, such as the thread lifting, with lower risk of complications, minimum length of time away from work and effectiveness in correcting ptosis and aging characteristics has led many specialists to adopt this technique, but many doubts about its safety and effectiveness still limit its overall use. To analyze data published in the literature on the durability of results, their effectiveness, safety, and risk of serious adverse events associated with procedures using several types of threading sutures. Literature review using the key words "thread lift", "barbed suture", "suture suspension" and "APTOS". Due to the scarcity of literature, recent reports of facial lifting using threads were also selected, complemented with bibliographical references. The first outcomes of facial lifting with barbed sutures remain inconclusive. Adverse events may occur, although they are mostly minor, self-limiting, and short-lived. The data on the maximum effect of the correction, the durability of results, and the consequences of the long-term suture stay are yet to be clarified. Interest in thread lifting is currently high, but this review suggests that it should not yet be adopted as an alternative to rhytidectomy. Copyright © 2017 Associação Brasileira de Otorrinolaringologia e Cirurgia Cérvico-Facial. Published by Elsevier Editora Ltda. All rights reserved.
Lift mechanics of downhill skiing and snowboarding
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.
Katarina Anthony
2011-01-01
CERN was especially featured at the Lift11 conference, held in Geneva early this month. Tara Shears delivered a keynote speech at the event, while Paul Oortman Gerlings (DGS-SEE) and Erik van der Bij (BE-CO) – winners of the Bulletin’s Lift11 competition – organised the CERN workshop. Paul Oortman Gerlings takes questions at CERN's Lift11 workshop. Lift11 was an opportunity for CERN to reach today’s innovators and developers. “The event was filled with people eager to learn new ideas, who were not afraid to ask questions,” says Tara Shears, physicist from the LHCb Collaboration who presented an update on the status of the LHC. “People were amazed by what goes on inside CERN, by our science, our facilities – even by the way we carry out our day-to-day work. It is a branch of fundamental research that really seems to inspire everyone.” A small Lift11 group had the chance to take a tour of CERN, ...
Carlson, H. W.; Walkley, K. B.
1982-01-01
Numerical methods incorporated into a computer program to provide estimates of the subsonic aerodynamic performance of twisted and cambered wings of arbitrary planform with attainable thrust and vortex lift considerations are described. The computational system is based on a linearized theory lifting surface solution which provides a spanwise distribution of theoretical leading edge thrust in addition to the surface distribution of perturbation velocities. The approach used relies on a solution by iteration. The method also features a superposition of independent solutions for a cambered and twisted wing and a flat wing of the same planform to provide, at little additional expense, results for a large number of angles of attack or lift coefficients. A previously developed method is employed to assess the portion of the theoretical thrust actually attainable and the portion that is felt as a vortex normal force.
Dritselis, Chris D, E-mail: dritseli@mie.uth.gr [Mechanical Engineering Department, University of Thessaly, Pedion Areos, 38334 Volos (Greece)
2016-02-15
The budgets of the Reynolds stress and streamwise enstrophy are evaluated through direct numerical simulations for the turbulent particle-laden flow in a vertical channel with momentum exchange between the two phases. The influence of the dispersed particles on the budgets is examined through a comparison of the particle-free and the particle-laden cases at the same Reynolds number of Re{sub b} = 5600 based on the bulk fluid velocity and the distance between the channel walls. Results are obtained for particle ensembles with four response times in simulations with and without streamwise gravity and inter-particle collisions at average mass (volume) fractions of 0.2 (2.7 × 10{sup −5}) and 0.5 (6.8 × 10{sup −5}). The particle feedback force on the flow of the carrier phase is modeled by a point-force approximation (PSIC-method). It is shown that all the terms in the budgets of the Reynolds stress components are decreased in the presence of particles. The level of reduction depends on the particle response time and it is higher under the effects of gravity and inter-particle collisions. A considerable reduction in all the terms of the streamwise enstrophy budget is also observed. In particular, all production mechanisms, and mainly vortex stretching, are inhibited in the particulate flows and thus the production of streamwise vorticity is significantly damped. A further insight into the direct particle effects on the fluid turbulence is provided by analyzing in detail the fluid–fluid, fluid–particle and particle–particle correlations, and the spectra of the fluid–particle energy exchange rate. The present results indicate that the turbulence production, dissipation and pressure–strain term are generally large quantities, but their summation is relatively small and comparable to the fluid–particle direct energy exchange rate. Consequently, the particle contribution can potentially increase or decrease the fluctuating fluid velocities and eventually
Characterization of graphite dust produced by pneumatic lift
Shen, Ke [Guangdong Provincial Key Laboratory of Thermal Management Engineering and Materials, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, Guangdong (China); Peng, Wei; Liu, Bing [Institute of Nuclear and New Energy Technology of Tsinghua University, Advanced Nuclear Energy Technology Cooperation Innovation Center, The Key Laboratory of Advanced Nuclear Engineering and Safety, Ministry of Education, Beijing 100084 (China); Kang, Feiyu [Guangdong Provincial Key Laboratory of Thermal Management Engineering and Materials, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, Guangdong (China); Yang, Xiaoyong; Li, Weihua [Institute of Nuclear and New Energy Technology of Tsinghua University, Advanced Nuclear Energy Technology Cooperation Innovation Center, The Key Laboratory of Advanced Nuclear Engineering and Safety, Ministry of Education, Beijing 100084 (China); Yu, Suyuan, E-mail: suyuan@tsinghua.edu.cn [Center for Combustion Energy, The Key Laboratory for Thermal Science and Power Engineering, Ministry of Educations, Tsinghua University, Beijing 100084 (China)
2016-08-15
Highlights: • Generation of graphite dust by pneumatic lift. • Determination of morphology and particle size distribution of graphite dust. • The size of graphite dust in this study is compared to AVR and THTR-300 results. • Graphite dust originates from both filler and binder of the matrix graphite. - Abstract: Graphite dust is an important safety concern of high-temperature gas-cooled reactor (HTR). The graphite dust could adsorb fission products, and the radioactive dust is transported by the coolant gas and deposited on the surface of the primary loop. The simulation of coagulation, aggregation, deposition, and resuspension behavior of graphite dust requires parameters such as particle size distribution and particle shape, but currently very limited data on graphite dust is available. The only data we have are from AVR and THTR-300, however, the AVR result is likely to be prejudiced by the oil ingress. In pebble-bed HTR, graphite dust is generally produced by mechanical abrasion, in particular, by the abrasion of graphite pebbles in the lifting pipe of the fuel handling system. Here we demonstrate the generation and characterization of graphite dust that were produced by pneumatic lift. This graphite dust could substitute the real dust in HTR for characterization. The dust, exhibiting a lamellar morphology, showed a number-weighted average particle size of 2.38 μm and a volume-weighted average size of 14.62 μm. These two sizes were larger than the AVR and THTR results. The discrepancy is possibly due to the irradiation effect and prejudice caused by the oil ingress accident. It is also confirmed by the Raman spectrum that both the filler particle and binder contribute to the dust generation.
Coriolis effects enhance lift on revolving wings.
Jardin, T; David, L
2015-03-01
At high angles of attack, an aircraft wing stalls. This dreaded event is characterized by the development of a leading edge vortex on the upper surface of the wing, followed by its shedding which causes a drastic drop in the aerodynamic lift. At similar angles of attack, the leading edge vortex on an insect wing or an autorotating seed membrane remains robustly attached, ensuring high sustained lift. What are the mechanisms responsible for both leading edge vortex attachment and high lift generation on revolving wings? We review the three main hypotheses that attempt to explain this specificity and, using direct numerical simulations of the Navier-Stokes equations, we show that the latter originates in Coriolis effects.
Fuel Cell Hydroge Manifold for Lift Trucks
Hosseinzadeh, Elham
Reducing CO2 emissions are getting more attention because of global warming. The transport sector which is responsible for a significant amount of emissions is going to reduce them due to new and upcoming regulations. Using fuel cells may be one way to help to reduce the emissions from this sector....... Battery driven lift trucks are being used more and more in different companies to reduce their emissions. However, battery driven lift trucks need long time to recharge and may be out of work for a long time. Fuel cell driven lift trucks diminish this problem and are therefore getting more attention....... The most common type of fuel cell used for automotive applications is PEM fuel cell. They are known for their high efficiency, low emissions and high reliability. However, lack of a hydrogen infrastructure, cost and durability of the stack is considered the biggest obstacles to the introduction of fuel...
Hydraulic Lifting Mechanisms for the Erection Equipment
B. M. Novozhilov
2016-01-01
Full Text Available In erection equipment of space launch complexes the hydraulic lifting mechanisms (HLM are solely and exclusively used to accomplish changing the space-mission vehicle (SMV position from horizontal to the vertical one. Existing designs of lifting mechanisms are diverse, but all of them basically contain a basic mechanism comprising one hydro-cylinder. With increasing SMV size and weight a task to design the more complicated lifting mechanisms, comprising more kinematic links and using several hydro-cylinders becomes urgent.The article conducts a detailed analysis of the basic HLM schemes and defines the features of their arrangement in erection equipment. Gives basic calculation relationships, allowing us to determine design parameters of mechanisms for stationary and transport units. Via examples of available erection equipment shows the embodiment of lifting mechanisms using basic schemes.The ways for development of HLM schemes to erect a SMV of the large size and weight are shown. Two options of the double-cylinder HLM are described. Both schemes are based on dividing a lift cycle into two parts, in each of which only one of the cylinders is in operation. The first option contains an additional, intermediate boom, with respect to which the main boom is erected. In such a mechanism the cylinders start running sequentially: at first, one of the cylinders erects the intermediate boom, then the other cylinder does the main one. The second HLM embodiment comprises a single carrier boom with the swing arm, which allows to swing the boom at a certain angle of less than 90 ° using one of the cylinders, also sequentially operating. The second cylinder allows the boom to fall into vertical position. Such schemes can reduce a stroke length of used hydraulic cylinders, which are the most expensive devices of the lifting mechanism.The analysis results are of interest to designers of erection equipment for the space launch complexes.
Active Control of Flow Separation on a High-Lift System with Slotted Flap at High Reynolds Number
Khodadoust, Abdollah; Washburn, Anthony
2007-01-01
The NASA Energy Efficient Transport (EET) airfoil was tested at NASA Langley's Low- Turbulence Pressure Tunnel (LTPT) to assess the effectiveness of distributed Active Flow Control (AFC) concepts on a high-lift system at flight scale Reynolds numbers for a medium-sized transport. The test results indicate presence of strong Reynolds number effects on the high-lift system with the AFC operational, implying the importance of flight-scale testing for implementation of such systems during design of future flight vehicles with AFC. This paper describes the wind tunnel test results obtained at the LTPT for the EET high-lift system for various AFC concepts examined on this airfoil.
Asymmetric Gepner Models II. Heterotic Weight Lifting
Gato-Rivera, B
2010-01-01
A systematic study of "lifted" Gepner models is presented. Lifted Gepner models are obtained from standard Gepner models by replacing one of the N=2 building blocks and the $E_8$ factor by a modular isomorphic $N=0$ model on the bosonic side of the heterotic string. The main result is that after this change three family models occur abundantly, in sharp contrast to ordinary Gepner models. In particular, more than 250 new and unrelated moduli spaces of three family models are identified. We discuss the occurrence of fractionally charged particles in these spectra.
Fuel Cell Hydroge Manifold for Lift Trucks
Hosseinzadeh, Elham; Rokni, Masoud; Elmegaard, Brian
2012-01-01
Reducing CO2 emissions are getting more attention because of global warming. The transport sector which is responsible for a significant amount of emissions is going to reduce them due to new and upcoming regulations. Using fuel cells may be one way to help to reduce the emissions from this sector. Battery driven lift trucks are being used more and more in different companies to reduce their emissions. However, battery driven lift trucks need long time to recharge and may be out of work for a...
Soccer ball lift coefficients via trajectory analysis
Goff, John Eric [Department of Physics, Lynchburg College, Lynchburg, VA 24501 (United States); Carre, Matt J, E-mail: goff@lynchburg.ed [Department of Mechanical Engineering, University of Sheffield, Sheffield S1 3JD (United Kingdom)
2010-07-15
We performed experiments in which a soccer ball was launched from a machine while two high-speed cameras recorded portions of the trajectory. Using the trajectory data and published drag coefficients, we extracted lift coefficients for a soccer ball. We determined lift coefficients for a wide range of spin parameters, including several spin parameters that have not been obtained by today's wind tunnels. Our trajectory analysis technique is not only a valuable tool for professional sports scientists, it is also accessible to students with a background in undergraduate-level classical mechanics.
Asymmetric Gepner models II. Heterotic weight lifting
Gato-Rivera, B. [NIKHEF Theory Group, Kruislaan 409, 1098 SJ Amsterdam (Netherlands); Instituto de Fisica Fundamental, CSIC, Serrano 123, Madrid 28006 (Spain); Schellekens, A.N., E-mail: t58@nikhef.n [NIKHEF Theory Group, Kruislaan 409, 1098 SJ Amsterdam (Netherlands); Instituto de Fisica Fundamental, CSIC, Serrano 123, Madrid 28006 (Spain); IMAPP, Radboud Universiteit, Nijmegen (Netherlands)
2011-05-21
A systematic study of 'lifted' Gepner models is presented. Lifted Gepner models are obtained from standard Gepner models by replacing one of the N=2 building blocks and the E{sub 8} factor by a modular isomorphic N=0 model on the bosonic side of the heterotic string. The main result is that after this change three family models occur abundantly, in sharp contrast to ordinary Gepner models. In particular, more than 250 new and unrelated moduli spaces of three family models are identified. We discuss the occurrence of fractionally charged particles in these spectra.
Belan, Marco
2013-01-01
The background of this work is the problem of reducing the aerodynamic turbulent friction drag, which is an important source of energy waste in innumerable technological fields. We develop a theoretical framework aimed at predicting the behaviour of existing drag reduction techniques when used at the large values of Re which are typical of applications. We focus on one recently proposed and very promising technique, which consists in creating at the wall streamwise-travelling waves of spanwise velocity. A perturbation analysis of the Navier-Stokes equations that govern the fluid motion is carried out, for the simplest wall-bounded flow geometry, i.e. the plane channel flow. The streamwise base flow is perturbed by the spanwise time-varying base flow induced by the travelling waves. An asymptotic expansion is then carried out with respect to the velocity amplitude of the travelling wave. The analysis, although based on several assumptions, leads to predictions of drag reduction that agree well with the measure...
徐万海; 杜杰; 余建星; 李敬成
2011-01-01
A wake oscillator model is presented for the stream-wise vortex-induced vibration of a circular cylinder in the second excitation region. The near wake dynamics related to the fluctuating nature of alternate vortex shedding is modeled based on the classical van der Pol equation. An appropriate approach used in cross-Sow VIV is developed to estimate the model empirical parameters. The comparison between our calculations and experiments is carried out to validate the proposed model. It is found that the present model results agree fairly well with the experimental data.%A wake oscillator model is presented for the stream-wise vortex-induced vibration of a circular cylinder in the second excitation region.The near wake dynamics related to the fluctuating nature of alternate vortex shedding is modeled based on the classical van der Pol equation.An appropriate approach used in cross-flow VIV is developed to estimate the nodel empirical parameters.The comparison between our calculations and experiments is carried out to validate the proposed model.It is found that the present model results agree fairly well with the experimental data.
Complications of lower blepharoplasty and midface lifting.
Schwarcz, Robert M; Kotlus, Brett
2015-01-01
Lower eyelid blepharoplasty and midface lifting share a complex anatomy, which should be mastered before attempting these types of surgeries. In recent years, there have been significant contributions to rejuvenating this area. A thorough understanding of the rejuvenative approaches and their outcomes is imperative. Thus, the problem must be preoperatively evaluated to offer the appropriate technique and minimize complications.
Leading-Edge Vortex lifts swifts
Videler, JJ; Stamhuis, EJ; Povel, GDE
2004-01-01
The current understanding of how birds fly must be revised, because birds use their hand-wings in an unconventional way to generate lift and drag. Physical models of a common swift wing in gliding posture with a 60degrees sweep of the sharp hand-wing leading edge were tested in a water tunnel. Inter
Lifts of projective congruence groups, II
Kiming, Ian
2014-01-01
We continue and complete our previous paper ``Lifts of projective congruence groups'' concerning the question of whether there exist noncongruence subgroups of that are projectively equivalent to one of the groups or . A complete answer to this question is obtained: In case of such noncongruence...
Measuring Lift with the Wright Airfoils
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…
Redheffer representations and relaxed commutant lifting
ter Horst, S.
2011-01-01
It is well known that the solutions of a (relaxed) commutant lifting problem can be described via a linear fractional representation of the Redheffer type. The coefficients of such Redheffer representations are analytic operator-valued functions defined on the unit disc D of the complex plane. In th
Image Compression using Space Adaptive Lifting Scheme
Ramu Satyabama
2011-01-01
Full Text Available Problem statement: Digital images play an important role both in daily life applications as well as in areas of research and technology. Due to the increasing traffic caused by multimedia information and digitized form of representation of images; image compression has become a necessity. Approach: Wavelet transform has demonstrated excellent image compression performance. New algorithms based on Lifting style implementation of wavelet transforms have been presented in this study. Adaptively is introduced in lifting by choosing the prediction operator based on the local properties of the image. The prediction filters are chosen based on the edge detection and the relative local variance. In regions where the image is locally smooth, we use higher order predictors and near edges we reduce the order and thus the length of the predictor. Results: We have applied the adaptive prediction algorithms to test images. The original image is transformed using adaptive lifting based wavelet transform and it is compressed using Set Partitioning In Hierarchical Tree algorithm (SPIHT and the performance is compared with the popular 9/7 wavelet transform. The performance metric Peak Signal to Noise Ratio (PSNR for the reconstructed image is computed. Conclusion: The proposed adaptive algorithms give better performance than 9/7 wavelet, the most popular wavelet transforms. Lifting allows us to incorporate adaptivity and nonlinear operators into the transform. The proposed methods efficiently represent the edges and appear promising for image compression. The proposed adaptive methods reduce edge artifacts and ringing and give improved PSNR for edge dominated images.
NASA HL-20 PLS Lifting Body (Mockup)
1991-01-01
NASA HL-20 PLS Lifting Body (Mockup): The HL-20 came into use at Langley in October 1990 and is a full-scale non-flying mockup. This mockup was used for engineering studies of maintainability of the vehicle, as testing crew positions, pilot visibility and other human factors considerations.
Soft sensing for gas-lift wells
Bloemen, H.H.J.; Belfroid, S.P.C.; Sturm, W.L.; Verhelst, F.J.P.C.M.G.
2006-01-01
This paper considers the use of extended Kalman filtering as a soft-sensing technique for gas lift wells. This technique is deployed for the estimation of dynamic variables that are not directly measured. Possible applications are the estimation of flow rates from surface and downhole pressure measu
Innovative Alternatives to Lifting Overturned Military Vehicles
2014-04-25
objects. For instance, Mine -Resistant Ambush Protected (MRAP) vehicles, which can weigh up to 55,000 lbs, have in the past overturned, trapping people...through long, small wires, and gives the user great control over the lift. The motors are powered by high performance 6.0 amp-hour lithium
Lift and down-gradient shear-induced diffusion in Red Blood Cell suspensions
Grandchamp, Xavier; Srivastav, Aparna; Minetti, Christophe; Podgorski, Thomas
2013-01-01
The distribution of Red Blood Cells in a confined channel flow is inhomogeneous and shows a marked depletion near the walls due to a competition between migration away from the walls and shear-induced diffusion resulting from interactions between particles. We investigated the lift of RBCs in a shear flow near a wall and measured a significant lift velocity despite the tumbling motion of cells. We also provide values for the collective and anisotropic shear-induced diffusion of a cloud of RBCs, both in the direction of shear and in the direction of vorticity. A generic down-gradient subdiffusion characterized by an exponent 1/3 is highlighted.
Lift estimation of Half-Rotating Wing in hovering flight
Wang, X. Y.; Dong, Y. P.; Qiu, Z. Z.; Zhang, Y. Q.; Shan, J. H.
2016-11-01
Half-Rotating Wing (HRW) is a new kind of flapping wing system with rotating flapping instead of oscillating flapping. Estimating approach of hovering lift which generated in hovering flight was important theoretical foundation to design aircraft using HRW. The working principle of HRW based on Half-Rotating Mechanism (HRM) was firstly introduced in this paper. Generating process of lift by HRW was also given. The calculating models of two lift mechanisms for HRW, including Lift of Flow Around Wing (LFAW) and Lift of Flow Dragging Wing (LFDW), were respectively established. The lift estimating model of HRW was further deduced, by which hovering lift for HRW with different angular velocity could be calculated. Case study using XFLOW software simulation indicates that the above estimating method was effective and feasible to predict roughly the hovering lift for a new HRW system.
Hybrid Aircraft for Heavy Lift / High Speed Strategic Mobility
2011-04-01
engines only need to move the airship , not lift it. AU/ACSC/KRISTOF/AY11 12 Figure 6: Aerodynamic Lift (Source: Wikipedia.org at http...4 Early Modern Military Airship Operations ................................................................................. 4 A...10 II: Airship Basics
The Design of Wheelchair Lifting Mechanism and Control System
ZHAO Cong; WANG Zheng-xing; JIANG Shi-hong; ZHANG Li; LIU Zheng-yu
2014-01-01
In order to achieve a wheelchair lift function, this paper designs a tri-scissors mechanism. Through the so-called H-type transmission and L-type swing rod, the three scissors mechanisms lift in the same rate with only one liner motor while ensuring the stability of the lift. Finite element analysis in ANSYS is performed to verify the material strength. The control system with Sunplus SCM achieves the voice control of wheelchair walking and lifting.
Clinical application of palatal lift appliance in velopharyngeal incompetence
S Premkumar
2011-01-01
Full Text Available The presence of nasal air leak in cleft palate patients with velopharyngeal incompetence leads to characteristic nasal snort. The efficacy of the palatal lift appliance in patients with adequate velopharyngeal tissue with incompetence was tested. Speech quality improved after the wearing of palatal lift appliance. Palatal lift appliances are simple and efficient in reducing the nasal air leak. Ongoing speech therapy is necessary and advised for patients receiving palatal lift.
Medan, R. T.
1973-01-01
A method for computing the lifting pressure distribution on a wing with partial span, swept control surfaces is presented. This method is valid within the framework of linearized, steady, potential flow theory and consists of using conventional lifting surface theory in conjuction with a flap pressure mode. The cause of a numerical instability that can occur during the quadrature of the flap pressure mode is discussed, and an efficient technique to eliminate the instability is derived. This technique is valid for both the flap pressure mode and regular pressure modes and could be used to improve existing lifting surface methods. Examples of the use of the flap pressure mode and comparisons among this method, other theoretical methods, and experiments are given. Discrepancies with experiment are indicated and candidate causes are presented. It is concluded that the method can lead to an efficient and accurate solution of the mathematical problem when a partial span, trailing edge flap is involved.
Abadi, Ali Salehi Sahl; Mazlomi, Adel; Saraji, Gebraeil Nasl; Zeraati, Hojjat; Hadian, Mohammad Reza; Jafari, Amir Homayoun
2015-10-01
In spite of the widespread use of automation in industry, manual material handling (MMH) is still performed in many occupational settings. The emphasis on ergonomics in MMH tasks is due to the potential risks of workplace accidents and injuries. This study aimed to assess the effect of box size, frequency of lift, and height of lift on maximum acceptable weight of lift (MAWL) on the heart rates of male university students in Iran. This experimental study was conducted in 2015 with 15 male students recruited from Tehran University of Medical Sciences. Each participant performed 18 different lifting tasks that involved three lifting frequencies (1lift/min, 4.3 lifts/min and 6.67 lifts/min), three lifting heights (floor to knuckle, knuckle to shoulder, and shoulder to arm reach), and two box sizes. Each set of experiments was conducted during the 20 min work period using the free-style lifting technique. The working heart rates (WHR) were recorded for the entire duration. In this study, we used SPSS version 18 software and descriptive statistical methods, analysis of variance (ANOVA), and the t-test for data analysis. The results of the ANOVA showed that there was a significant difference between the mean of MAWL in terms of frequencies of lifts (p = 0.02). Tukey's post hoc test indicated that there was a significant difference between the frequencies of 1 lift/minute and 6.67 lifts/minute (p = 0. 01). There was a significant difference between the mean heart rates in terms of frequencies of lifts (p = 0.006), and Tukey's post hoc test indicated a significant difference between the frequencies of 1 lift/minute and 6.67 lifts/minute (p = 0.004). But, there was no significant difference between the mean of MAWL and the mean heart rate in terms of lifting heights (p > 0.05). The results of the t-test showed that there was a significant difference between the mean of MAWL and the mean heart rate in terms of the sizes of the two boxes (p = 0.000). Based on the results of
The personal lift-assist device and lifting technique: a principal component analysis.
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.
49 CFR 178.975 - Top lift test.
2010-10-01
... opposite lifting devices, so that the hoisting forces are applied vertically for a period of five minutes; and (ii) Lifted by each pair of diagonally opposite lifting devices so that the hoisting forces are... which it is designed until clear of the floor and maintained in that position for a period of...
On lifting line analysis of horizontal axis windturbines
Politis, G. K.; Loukakis, T. A.
A convergent iteration scheme for lifting line performance analysis of horizontal axis windturbines is presented. Lifting line correction factors are introduced and compared with those of Prandtl and Goldstein. Lifting line and strip theory formulations are applied for the calculation of performance for two windturbines. Differences of engineering importance are shown to exist in the prediction of the Power coefficient.
14 CFR 23.345 - High lift devices.
2010-01-01
... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false High lift devices. 23.345 Section 23.345 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... lift devices. (a) If flaps or similar high lift devices are to be used for takeoff, approach or landing...
49 CFR 37.165 - Lift and securement use.
2010-10-01
... 49 Transportation 1 2010-10-01 2010-10-01 false Lift and securement use. 37.165 Section 37.165... DISABILITIES (ADA) Provision of Service § 37.165 Lift and securement use. (a) This section applies to public... with disabilities with the use of securement systems, ramps and lifts. If it is necessary for the...
14 CFR 25.699 - Lift and drag device indicator.
2010-01-01
... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Lift and drag device indicator. 25.699....699 Lift and drag device indicator. (a) There must be means to indicate to the pilots the position of each lift or drag device having a separate control in the cockpit to adjust its position. In addition...
14 CFR 25.345 - High lift devices.
2010-01-01
... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false High lift devices. 25.345 Section 25.345... STANDARDS: TRANSPORT CATEGORY AIRPLANES Structure Flight Maneuver and Gust Conditions § 25.345 High lift...) A head-on gust of 25 feet per second velocity (EAS). (c) If flaps or other high lift devices are to...
14 CFR 23.369 - Rear lift truss.
2010-01-01
... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Rear lift truss. 23.369 Section 23.369 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... lift truss. (a) If a rear lift truss is used, it must be designed to withstand conditions of reversed...
δ-Lifting and δ-Supplemented Modules
Muhammet Tamer Kosan
2007-01-01
In this paper, δ-lifting and δ-supplemented modules are defined as generalizations of lifting and supplemented modules. Several properties of these modules are proved.New characterizations of δ-semiperect and b-perfect rings studied in [9] are obtained using δ-lifting and δ-supplemented modules.
Lifting a familiar object: visual size analysis, not memory for object weight, scales lift force.
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
2010-06-11
... SECURITY U.S. Customs and Border Protection Notice of Issuance of Final Determination Concerning a Lift Unit for an Overhead Patient Lift System; Correction AGENCY: U.S. Customs and Border Protection... notice that it had issued a final determination concerning the country of origin of a lift unit for an...
An assessment of the impact of local processes on dust lifting in martian climate models
Mulholland, David P.; Spiga, Aymeric; Listowski, Constantino; Read, Peter L.
2015-05-01
observed, including the flushing storm sources of Chryse and Utopia, and southern midlatitude areas from which larger storms tend to initiate, such as Hellas and Solis Planum. The seasonal cycle of emission, which includes a double-peaked structure in northern autumn and winter, also appears realistic. Significant increases to lifting rates are produced for any sensible choices of parameters controlling the sub-grid distributions used, but results are sensitive to the smallest scale of variability considered, which high-resolution modelling suggests should be O(1 km) or less. Use of such models in future will permit the use of a diagnosed (rather than prescribed) variable gustiness intensity, which should further enhance dust lifting in the southern hemisphere in particular.
Lift and Drag Measurements of Superhydrophobic Hydrofoils
Sur, Samrat; Kim, Jeong-Hyun; Rothstein, Jonathan
2015-11-01
For several years, superhydrophobic surfaces which are chemically hydrophobic with micron or nanometer scale surface features have been considered for their ability to reduce drag and produce slip in microfluidic devices. More recently it has been demonstrated that superhydrophobic surfaces reduce friction coefficient in turbulent flows as well. In this talk, we will consider that modifying a hydrofoil's surface to make it superhydrophobic has on the resulting lift and drag measurements over a wide range of angles of attack. Experiments are conducted over the range of Reynolds numbers between 10,000hydrofoil is made superhydrophobic. The hydrofoils are coated Teflon that has been hot embossed with a 325grit stainless steel woven mesh to produce a regular pattern of microposts. In addition to fully superhydrophobic hydrofoils, selectively coated symmetrical hydrofoils will also be examined to study the effect that asymmetries in the surface properties can have on lift and drag. Partially funded by NSF CBET-1334962.
Lifting CERN entrepreneurs to new heights
William Rode
2014-01-01
How can an international research institution help employees who wish to leave their comfort zone for the risky endeavour of starting a company? CERN encourages the creation of companies as a way of disseminating technology developed here. But what else can be done to foster these initiatives? William Rode, a technical student in CERN’s Knowledge Transfer Group, studied spin-off creations in some leading research institutions as part of his Master's thesis in entrepreneurship at the Norwegian University of Science and Technology. William, who was offered a ticket to attend the Lift14 conference in Geneva, shares some insight into how we can support entrepreneurship at CERN: "A while ago I attended the Lift conference in Geneva. The conference explores the business and social implications of technology innovation through talks and workshops, as well as through art and discussion. Innovation is at the core of the conference and is reflected in the open-mindedness of th...
Approximately isometric lifting in quasidiagonal extensions
FANG XiaoChun; ZHAO YiLe
2009-01-01
Let O→I→A→A/I→O be a short exact sequence of C*-algebras with A unital.Suppose that the extension O→I→A→A/I→O is quasidiagonal,then it is shown that any positive element (projection,partial isometry,unitary element,respectively) in A/I has a lifting with the same form which commutes with some quasicentral approximate unit of I consisting of projections.Furthermore,it is shown that for any given positive number e,two positive elements (projections,As an application,it is shown that for any positive numbers e and (u) in U(A/I)0,there exists u in U(A)0which is a lifting of (u) such that cel(u) ＜ cel(u) +e.
Lift and drag of cetacean flippers
Murray, Mark; Weber, Paul; Howle, Laurens; Fish, Frank
2008-11-01
Field observation and collection of biological samples has resulted in cetacean (whales, dolphins and porpoises) flipper geometry being known for most species. However, the hydrodynamic properties of cetacean flippers have not been rigorously tested and thus their performance characteristics are unknown. Here, conducting water tunnel testing using scale models of cetacean flippers derived via computed tomography (CT) scans, as well as computational fluid dynamic (CFD) simulations, we present a baseline work to determine the hydrodynamic characteristics of cetacean flippers. We found that flippers of similar planform shape had similar hydrodynamic performance characteristics. Furthermore, one group of flippers of planform shape similar to a modern swept wing was found to have lift coefficient versus angle of attack curves that were biphasic rather than linear in nature, which was caused by the onset of vortex-dominated lift. Drag coefficient versus angle of attack curves were found to be less dependant on planform shape.
Particle Lifting Processes in Dust Devils
Neakrase, L. D. V.; Balme, M. R.; Esposito, F.; Kelling, T.; Klose, M.; Kok, J. F.; Marticorena, B.; Merrison, J.; Patel, M.; Wurm, G.
2016-10-01
Particle lifting in dust devils on both Earth and Mars has been studied from many different perspectives, including how dust devils could influence the dust cycles of both planets. Here we review our current understanding of particle entrainment by dust devils by examining results from field observations on Earth and Mars, laboratory experiments (at terrestrial ambient and Mars-analog conditions), and analytical modeling. By combining insights obtained from these three methodologies, we provide a detailed overview on interactions between particle lifting processes due to mechanical, thermal, electrodynamical and pressure effects, and how these processes apply to dust devils on Earth and Mars. Experiments and observations have shown dust devils to be effective lifters of dust given the proper conditions on Earth and Mars. However, dust devil studies have yet to determine the individual roles of each of the component processes acting at any given time in dust devils.
Eisenhart lift for higher derivative systems
Galajinsky, Anton; Masterov, Ivan
2017-02-01
The Eisenhart lift provides an elegant geometric description of a dynamical system of second order in terms of null geodesics of the Brinkmann-type metric. In this work, we attempt to generalize the Eisenhart method so as to encompass higher derivative models. The analysis relies upon Ostrogradsky's Hamiltonian. A consistent geometric description seems feasible only for a particular class of potentials. The scheme is exemplified by the Pais-Uhlenbeck oscillator.
Eisenhart lift for higher derivative systems
Anton Galajinsky
2017-02-01
Full Text Available The Eisenhart lift provides an elegant geometric description of a dynamical system of second order in terms of null geodesics of the Brinkmann-type metric. In this work, we attempt to generalize the Eisenhart method so as to encompass higher derivative models. The analysis relies upon Ostrogradsky's Hamiltonian. A consistent geometric description seems feasible only for a particular class of potentials. The scheme is exemplified by the Pais–Uhlenbeck oscillator.
Eisenhart lift for higher derivative systems
Galajinsky, Anton
2016-01-01
The Eisenhart lift provides an elegant geometric description of a dynamical system of second order in terms of null geodesics of the Brinkmann-type metric. In this work, we attempt to generalize the Eisenhart method so as to encompass higher derivative models. The analysis relies upon Ostrogradsky's Hamiltonian. A consistent geometric description seems feasible only for a particular class of potentials. The scheme is exemplified by the Pais-Uhlenbeck oscillator.
Efficacy of LIFT for recurrent anal fistula.
Lehmann, J-P; Graf, W
2013-05-01
Ligation of the intersphincteric fistula tract (LIFT) is a novel sphincter-preserving technique for anal fistula. This pilot study was designed to evaluate the results in patients with a recurrent fistula. Seventeen patients [nine men; median age 49 (range, 30-76) years] with a recurrent trans-sphincteric fistula were treated with a LIFT procedure between June 2008 and February 2011. All were followed prospectively for a median of 16 (range, 5-27) weeks with clinical examination. Fifteen followed for 13.5 (range, 8-26) months by clinical examination also had three-dimensional (3D) anal ultrasound. The duration of the procedure was 35 (range, 18-70) min. One patient developed a small local haematoma and one had a subcutaneous infection, but otherwise there was no morbidity. At follow up, 11 (65%) patients had a successful closure, two (12%) had a remaining sinus and four (23%) had a persistent fistula. The incidence of persistent or recurrent fistulae at 13.5 months was six (40%) of 15 patients. No de novo faecal incontinence was reported. LIFT is a safe procedure for patients with recurrent anal fistula, with healing at short-term and medium-term follow-up comparable with or superior to that of other sphincter-preserving techniques. Larger studies with a longer follow up are needed to define the ultimate role of LIFT in patients with recurrence. © 2013 The Authors. Colorectal Disease © 2013 The Association of Coloproctology of Great Britain and Ireland.
Unified treatment of lifting atmospheric entry
Nachtsheim, P. R.; Lehman, L. L.
1980-01-01
This paper presents a unified treatment of the effect of lift on peak acceleration during atmospheric entry. Earlier studies were restricted to different regimes because of approximations invoked to solve the same transcendental equation. This paper shows the connection between the earlier studies by employing a general expression for the peak acceleration and obtains solutions to the transcendental equation without invoking the earlier approximations. Results are presented and compared with earlier studies where appropriate.
Dragonfly flight. III. Lift and power requirements.
Wakeling, JM; Ellington, CP
1997-02-01
A mean lift coefficient quasi-steady analysis has been applied to the free flight of the dragonfly Sympetrum sanguineum and the damselfly Calopteryx splendens. The analysis accommodated the yaw and accelerations involved in free flight. For any given velocity or resultant aerodynamic force (thrust), the damselfly mean lift coefficient was higher than that for the dragonfly because of its clap and fling. For both species, the maximum mean lift coefficient L was higher than the steady CL,max. Both species aligned their strokes planes to be nearly normal to the thrust, a strategy that reduces the L required for flight and which is different from the previously published hovering and slow dragonfly flights with stroke planes steeply inclined to the horizontal. Owing to the relatively low costs of accelerating the wing, the aerodynamic power required for flight represents the mechanical power output from the muscles. The maximum muscle mass-specific power was estimated at 156 and 166 W kg-1 for S. sanguineum and C. splendens, respectively. Measurements of heat production immediately after flight resulted in mechanical efficiency estimates of 13 % and 9 % for S. sanguineum and C. splendens muscles, respectively.
Occupational lifting, fetal death and preterm birth
Mocevic, Emina; Svendsen, Susanne Wulff; Jørgensen, Kristian Tore
2014-01-01
OBJECTIVE: We examined the association between occupational lifting during pregnancy and risk of fetal death and preterm birth using a job exposure matrix (JEM). METHODS: For 68,086 occupationally active women in the Danish National Birth Cohort, interview information on occupational lifting...... the JEM. We used Cox regression models with gestational age as underlying time variable and adjustment for covariates. RESULTS: We observed 2,717 fetal deaths and 3,128 preterm births within the study cohort. No exposure-response relation was observed for fetal death, but for women with a prior fetal...... death, we found a hazard ratio (HR) of 2.87 (95% CI 1.37, 6.01) for stillbirth (fetal death ≥22 completed gestational weeks) among those who lifted >200 kg/day. For preterm birth, we found an exposure-response relation for primigravid women, reaching a HR of 1.43 (95% CI 1.13, 1.80) for total loads >200...
Dynamic response of Hovercraft lift fans
Moran, D. D.
1981-08-01
Hovercraft lift fans are subjected to varying back pressure due to wave action and craft motions when these vehicles are operating in a seaway. The oscillatory back pressure causes the fans to perform dynamically, exhibiting a hysteresis type of response and a corresponding degradation in mean performance. Since Hovercraft motions are influenced by variations in lift fan pressure and discharge, it is important to understand completely the nature of the dynamic performance of lift fans in order to completely solve the Hovercraft seakeeping problem. The present study was performed to determine and classify the instabilities encountered in a centrifugal fan operating against time-varying back pressure. A model-scale experiment was developed in which the fan discharge was directed into a flow-measuring device, terminating in a rotating valve which produced an oscillatory back pressure superimposed upon a mean aerodynamic resistance. Pressure and local velocity were measured as functions of time at several locations in the fan volute. The measurements permitted the identification of rotating (or propagating) stall in the impeller. One cell and two cell configurations were classified and the transient condition connecting these two configurations was observed. The mechanisms which lead to rotating stall in a centrifugal compressor are presented and discussed with specific reference to Hovercraft applications.
Blache, Y; Dal Maso, F; Desmoulins, L; Plamondon, A; Begon, M
2015-04-01
This study aimed to assess the level of co-activation of the superficial shoulder muscles during lifting movement. Boxes containing three different loads (6, 12, and 18 kg) were lifted by fourteen subjects from the waist to shoulder or eye level. The 3D kinematics and electromyograms of the three deltoids, latissimus dorsi and pectoralis major were recorded. A musculoskeletal model was used to determine direction of the moment arm of these muscles. Finally an index of muscle co-activation named the muscle focus was used to evaluate the effects of lifting height, weight lifted and phase (pulling, lifting and dropping phases) on superficial shoulder muscle coactivation. The muscle focus was lower (more co-contraction) during the dropping phase compared to the two other phases (-13%, pmuscle activations and by a change in the direction of the muscle moment arm as a function of glenohumeral joint position. Consequently, the function of the shoulder superficial muscles varied with respect to the glenohumeral joint position. To increase the superficial muscle coactivation during the dropping phase may be a solution to increase glenohumeral joint stiffness. Copyright © 2014 Elsevier Ltd. All rights reserved.
Leading-Edge Velocities and Lifted Methane Jet Flame Stability
W. Wang
2010-01-01
Full Text Available Current interest exists in understanding reaction-zone dynamics and mechanisms with respect to how they counterpropagate against incoming reactants. Images of flame position and flow-field morphology are presented from flame chemiluminescence and particle image velocimetry (PIV measurements. In the present study, PIV experiments were carried out to measure the methane jet lifted-flame flow-field velocities in the vicinity of the flame leading edge. Specifically, velocity fields within the high-temperature zone were examined in detail, which complements previous studies, whose prime focus is the flow-field upstream of the high-temperature boundary. PIV data is used not only to determine the velocities, but, along with chemiluminescence images, to also indicate the approximate location of the reaction zone (further supported by/through the leading-edge flame velocity distributions. The velocity results indirectly support the concept that the flame is anchored primarily through the mechanism of partially premixed flame propagation.
1981-06-01
26 We turn our attention now to the width of distribution characterized by the parameter a and its relation to the amalgama - tion...the equation (1.3.17) was solved for K - 0 and the above three forms of amalgama - tion, tearing, pairing, and tripling. These results are given in Table
Group Lifting Structures For Multirate Filter Banks, I: Uniqueness Of Lifting Factorizations
Brislawn, Christopher M [Los Alamos National Laboratory
2008-01-01
This paper studies two-channel finite impulse response (FIR) perfect reconstruction filter banks. The connection between filter banks and wavelet transforms is well-known and will not be treated here. Figure 1 depicts the polyphase-with-advance representation of a filter bank [6]. A lifting factorization, is a factorization of polyphase matrices into upper and lower triangular lifting matrices. The existence of such decompositions via the Euclidean algorithm was shown for general FIR perfect reconstruction filter banks in [9] and was subsequently refined for linear phase filter banks in [10], [6]. These latter works were motivated by the ISO JPEG 2000 image coding standard [11], [12], [10], which specifies whole-sample symmetric (WS, or FIR type 1 linear phase) filter banks, as in Figure 2(a), in terms of half-sample symmetric (RS, or FIR type 2) lifting filters.
Advanced Model for Extreme Lift and Improved Aeroacoustics (AMELIA)
Lichtwardt, Jonathan; Paciano, Eric; Jameson, Tina; Fong, Robert; Marshall, David
2012-01-01
tunnel model design would be completed, manufactured, and calibrated. During the fifth year the large scale wind tunnel test was conducted. This technical memo will describe all phases of the Advanced Model for Extreme Lift and Improved Aeroacoustics (AMELIA) project and provide a brief summary of the background and modeling efforts involved in the NRA. The conceptual designs considered for this project and the decision process for the selected configuration adapted for a wind tunnel model will be briefly discussed. The internal configuration of AMELIA, and the internal measurements chosen in order to satisfy the requirements of obtaining a database of experimental data to be used for future computational model validations. The external experimental techniques that were employed during the test, along with the large-scale wind tunnel test facility are covered in great detail. Experimental measurements in the database include forces and moments, and surface pressure distributions, local skin friction measurements, boundary and shear layer velocity profiles, far-field acoustic data and noise signatures from turbofan propulsion simulators. Results and discussion of the circulation control performance, over-the-wing mounted engines, and the combined performance are also discussed in great detail.
Experimental analysis of sand particles' lift-off and incident velocities in wind-blown sand flux
Li Xie; Zhibao Dong; Xiaojing Zheng
2005-01-01
The probability distributions of sand particles' lift-off and incident velocities in a wind-blown sand flux play very important roles in the simulation of the wind-blown sand movement. In this paper, the vertical and the horizontal speeds of sand particles located at 1.0 mm above a sand-bed in a wind-blown sand flux are observed with the aid of Phase Doppler Anemometry (PDA) in a wind tunnel. Based on the experimental data, the probability distributions of not only the vertical lift-off speed but also the lift-off velocity as well as its horizontal component and the incident velocity as well as its vertical and horizontal components can be obtained by the equal distance histogram method. It is found, according to the results of the χ2-test for these probability distributions, that the probability density functions (pdf's) of the sand particles' lift-off and incident velocities as well as their vertical components are described by the Gamma density function with different peak values and shapes and the downwind incident and lift-off horizontal speeds, respectively, can be described by the lognormal and the Gamma density functions. These pdf's depend on not only the sand particle diameter but also the wind speed.
AN EFFECTIVE SCHEDULING SCHEME FOR LIFT CLUBS
W. Van Wijck
2012-01-01
Full Text Available
ENGLISH ABSTRACT: This paper describes a formula for scheduling the day-to-day operation of a lift club. The formula is remarkably simple, and can easily be implemented on a spreadsheet. It is also extremely flexible and can cater for almost any peculiarity that may arise. Much like a business, the lift club is viewed as an entity in its own right, rather than as a collection of individuals. The scheme can be used to generate interesting statistics such as percentage utilization of each member, average percentage utilization of all members, effective size of the lift club, etc. In addition, a graph, depicting each member's liability towards the club against time, can be generated. Finally, every member can obtain a record of his/her trip data over any specific period, which may be handy for income tax purposes.
AFRIKAANSE OPSOMMING: Hierdie artikel beskryf 'n fonnule vir die dag-tot-dag skedulering van 'n saamryklub. Die fonnule is merkwaardig eenvoudig en kan maklik op 'n sigblad geimplementeer word. Dit is ook besonder buigsaam deurdat dit vir bykans enige gebeurlikheid voorsienning maak. Die voorgestelde skeduleringsmetode beskou die saamryklub as 'n entiteit in eie reg, en skeduleing word vanuit die saamryklub se oogpunt gedoen. Die skema kan gebruik word om interesante statistieke soos byvoorbeeld die persentasie benutting deur enige lid, die gemiddelde persentasie benutting deur aIle lede, die effektiewe grootte van die klub, ens., te genereer. Voorts kan 'n grafiek gegenereer word wat elke lid se aanspreeklikheid teenoor die klub as 'n funksie van tyd grafies vertoon. Laastens kan enige lid op enige stadium 'n rekord trek van die aantal saamrygeleenthede wat hy oor 'n bepaalde periode voorsien en ontvang het. Dit mag handig wees vir belasting doeleindes.
Pure spinor equations to lift gauged supergravity
Rosa, Dario; Tomasiello, Alessandro [Dipartimento di Fisica, Università di Milano-Bicocca, and INFN, sezione di Milano-Bicocca,I-20126 Milano (Italy)
2014-01-31
We rewrite the equations for ten-dimensional supersymmetry in a way formally identical to a necessary and sufficient G-structure system in N=2 gauged supergravity, where all four-dimensional quantities are replaced by combinations of pure spinors and fluxes in the internal space. This provides a way to look for lifts of BPS solutions without having to reduce or even rewrite the ten-dimensional action. In particular this avoids the problem of consistent truncation, and the introduction of unphysical gravitino multiplets.
Variable-Compliance Couplings For Heavy Lifting
Kerley, James; Eklund, Wayne; Burkhardt, Raymond; Richardson, George W.
1992-01-01
New coupling devices contain manual or electronically controlled, motorized drives that vary stiffnesses. Short, clamped lengths of cable provide compliance. Using threaded rods, cables stretched, relaxed, or folded to make coupling more or less stiff. In more-advanced device, brackets holding cables moved by stepping motor via gearbox and ball screw. Motor operates under computer control with position feedback. Control computer commands greater stiffness during operations requiring precise positioning, and greater compliance to accommodate manufacturing tolerances. Intended for use in wrist joints of robotic manipulators and other industrial equipment that must lift heavy objects.
Lambda-Lifting in Quadratic Time
Danvy, Olivier; Schultz, Ulrik Pagh
2004-01-01
Lambda-lifting is a program transformation that is used in compilers, partial evaluators, and program transformers. In this article, we show how to reduce its complexity from cubic time to quadratic time, and we present a flow-sensitive lambda-lifter that also works in quadratic time. Lambda...... on the simple observation that all functions in each component need the same extra parameters and thus a transitive closure is not needed. We therefore simplify the search for extra parameters by treating each strongly connected component instead of each function as a unit, thereby reducing the time complexity...
Lambda-lifting in Quadratic Time
Danvy, O.; Schultz, U.P.
2004-01-01
Lambda-lifting is a program transformation that is used in compilers, partial evaluators, and program transformers. In this article, we show how to reduce its complexity from cubic time to quadratic time, and we present a flow-sensitive lambda-lifter that also works in quadratic time. Lambda...... on the simple observation that all functions in each component need the same extra parameters and thus a transitive closure is not needed. We therefore simplify the search for extra parameters by treating each strongly connected component instead of each function as a unit, thereby reducing the time complexity...
Bone suture and lateral sinus lift surgery
Amin Rahpeyma
2015-01-01
Full Text Available Bone suture in lateral sinus lift has four indications. Three of them depend on creating a hole in the lateral maxillary sinus wall above the antrostomy window for securing the elevated medial maxillary sinus membrane to manage perforated Schneiderian membrane. Covering the buccal antrostomy window with the buccal fat pad (BFP for better nourishment of the inserted graft and as an alternative for bone tags in fixation of collagen membrane has been reported previously. A new indication for firmly anchoring the BFP to the medial maxillary sinus wall as the last resort for the management of perforated Schneiderian membrane is explained in this article.
Fixed Wordsize Implementation of Lifting Schemes
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.
APOLLO 14: Lift off from lunar surface
1974-01-01
APOLLO 14: The lunar module 'Falcon' lifts off from the lunar surface From the film documentary 'APOLLO 14: 'Mission to Fra Mauro'', part of a documentary series on the APOLLO missions made in the early '70's and narrated by Burgess Meredith. APOLO 14: Third manned lunar landing with Alan B. Shepard, Jr.,Stuart A. Roosa, and Edgar D. Mitchell. Landed in the Fra Mauro area on Ferurary 5, 1971; performed EVA, deployed lunar experiments, returned lunar samples. Mission Duration 216 hrs 1 min 58 sec
Interjoint coordination and the personal lift-assist device.
Graham, Ryan B; Smallman, Catherine L W; Sadler, Erin M; Stevenson, Joan M
2013-04-01
It has been suggested that interjoint coordination may serve to reduce joint stress and muscular demand and to maintain balance during dynamic lifting tasks, thus having implications for safe lifting practices. Before recommending the use of an on-body ergonomic aid, the Personal Lift-Assist Device (PLAD), it is important to determine any effects this device may have on interjoint coordination. Principal component analyses were applied to relative phase angle waveforms, defining the hip-knee and lumbar spine-hip coordination of 15 males and 15 females during a repetitive lifting task. When wearing the PLAD, users lifted with more synchronous hip-knee and lumbar spine-hip coordination patterns (P lift (P < .01) for all conditions. No significant main effects of sex or significant interactions were observed on any of the outcome variables.
Back injury prevention: a lift team success story.
Hefti, Kelly S; Farnham, Richard J; Docken, Lisa; Bentaas, Ruth; Bossman, Sharon; Schaefer, Jill
2003-06-01
Work related back injuries among hospital personnel account for high volume, high cost workers' compensation claims. These injuries can be life altering experiences, affecting both the personal and professional lives of injured workers. Lifting must be viewed as a skill involving specialized training and mandated use of mechanical equipment, rather than as a random task performed by numerous health care providers. The use of a lift team specially trained in body mechanics, lifting techniques, and the use of mandated mechanical equipment can significantly affect injury data, financial outcomes, and employee satisfaction. The benefits of a lift team extend beyond the effect on injury and financial outcomes--they can be used for recruitment and retention strategies, and team members serve as mentors to others by demonstrating safe lifting techniques. Ultimately, a lift team helps protect a valuable resource--the health care worker.
Lift enhancement by dynamically changing wingspan in forward flapping flight
Wang, Shizhao; Zhang, Xing; He, Guowei; Liu, Tianshu
2014-06-01
Dynamically stretching and retracting wingspan has been widely observed in the flight of birds and bats, and its effects on the aerodynamic performance particularly lift generation are intriguing. The rectangular flat-plate flapping wing with a sinusoidally stretching and retracting wingspan is proposed as a simple model for biologically inspired dynamic morphing wings. Numerical simulations of the low-Reynolds-number flows around the flapping morphing wing are conducted in a parametric space by using the immersed boundary method. It is found that the instantaneous and time-averaged lift coefficients of the wing can be significantly enhanced by dynamically changing wingspan in a flapping cycle. The lift enhancement is caused by both changing the lifting surface area and manipulating the flow structures responsible to the vortex lift generation. The physical mechanisms behind the lift enhancement are explored by examining the three-dimensional flow structures around the flapping wing.
Lift Enhancement by Dynamically Changing Wingspan in Forward Flapping Flight
Wang, Shizhao; He, Guowei; Liu, Tianshu
2013-01-01
Stretching and retracting wingspan has been widely observed in the flight of birds and bats, and its effects on the aerodynamic performance particularly lift generation are intriguing. The rectangular flat-plate flapping wing with a sinusoidally stretching and retracting wingspan is proposed as a simple model of biologically-inspired dynamic morphing wings. Direct numerical simulations of the low-Reynolds-number flows around the flapping morphing wing in a parametric space are conducted by using immersed boundary method. It is found that the instantaneous and time-averaged lift coefficients of the wing can be significantly enhanced by dynamically changing wingspan in a flapping cycle. The lift enhancement is caused not only by changing the lifting surface area, but also manipulating the flow structures that are responsible to the generation of the vortex lift. The physical mechanisms behind the lift enhancement are explored by examining the three-dimensional flow structures around the flapping wing.
Aule, Margit, 1981-
2012-01-01
Linnainstallatsioonide festivalist "Lift 11", installatsioonidest. Festivali kuraatorid Margit Argus ja Margit Aule ning kaaskuraatorid Maarin Ektermann ja Ingrid Ruudi pälvisid EK arhitektuuri sihtkapitali 2011. a. arhitektuurialase tegevuse preemia avaliku linnaruumi mitmekesisust märkama, kasutama ning mõtestama ärgitanud ürituse korraldamise eest
Aule, Margit, 1981-
2012-01-01
Linnainstallatsioonide festivalist "Lift 11", installatsioonidest. Festivali kuraatorid Margit Argus ja Margit Aule ning kaaskuraatorid Maarin Ektermann ja Ingrid Ruudi pälvisid EK arhitektuuri sihtkapitali 2011. a. arhitektuurialase tegevuse preemia avaliku linnaruumi mitmekesisust märkama, kasutama ning mõtestama ärgitanud ürituse korraldamise eest
HSR High Lift Program and PCD2 Update
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).
Sectional lift coefficient of a rotating wing at low Reynolds numbers
Kim, Ji Eun [Hyundai Motor Company, Hwaseong (Korea, Republic of); Kweon, Ji Hoon [Asan Medical Center, Seoul (Korea, Republic of); Choi, Hae Cheon [Seoul National University, Seoul (Korea, Republic of)
2015-11-15
We study the characteristics of the sectional lift coefficient (C{sub L,S}) of low-aspect-ratio wings in rotating motion at low Reynolds number (Re = 136), by conducting three-dimensional numerical simulations. Three different shapes of thin-plate wings (fruit-fly, rectangular, and triangular wings) are considered but keeping their aspect ratio (wing span/wing chord) the same at 3.74. Each wing rotates at a constant angular velocity and the angle of attack (α) is fixed during rotation. During rotation, the wing is exposed to the downward flows generated from the previous rotation, and thus C{sub L,S} is overall reduced due to the decrease in the effective angle of attack. At low α's, C{sub L,S} becomes almost constant on the whole span. At high α's, C{sub L,S} on the wing mid-section is inversely proportional to the radial position. The radial distribution of the sectional lift coefficient is less affected by the wing planform, while the lift coefficient significantly depends on the wing planforms. Finally, we show that the effect of the Reynolds number on the sectional lift coefficient is insignificant at low angle of attack but becomes important at high angle of attack.
Kamat, S. R.; Zula, N. E. N. Md; Rayme, N. S.; Shamsuddin, S.; Husain, K.
2017-06-01
Warehouse is an important entity in manufacturing organizations. It usually involves working activities that relate ergonomics risk factors including repetitive and heavy lifting activities. Aerospace manufacturing workers are prone of having musculoskeletal disorder (MSD) problems because of the manual handling activities. From the questionnaires is states that the workers may have experience discomforts experience during manual handling work. Thus, the objectives of this study are; to investigate the body posture and analyze the level of discomfort for body posture of the workers while performing the repetitive and heavy lifting activities that cause MSD problems and to suggest proper body posture and alternatives to reduce the MSD related problems. Methodology of this study involves interviews, questionnaires distribution, anthropometry measurements, RULA (Right Upper Limb Assessment) assessment sheet and CATIA V5 RULA analysis, NIOSH lifting index (LI) and recommended weight limit (RWL). Ten workers are selected for pilot study and as for anthropometry measurement all workers in the warehouse department were involved. From the first pilot study, the RULA assessment score in CATIA V5 shows the highest score which is 7 for all postures and results after improvement of working posture is very low hence, detecting weight of the material handling is not in recommendation. To reduce the risk of MSD through the improvisation of working posture, the weight limit is also calculated in order to have a RWL for each worker. Therefore, proposing a guideline for the aerospace workers involved with repetitive movement and excessive lifting will help in reducing the risk of getting MSD.
Validation of Vortex-Lattice Method for Loads on Wings in Lift-Generated Wakes
Rossow, Vernon J.
1995-01-01
A study is described that evaluates the accuracy of vortex-lattice methods when they are used to compute the loads induced on aircraft as they encounter lift-generated wakes. The evaluation is accomplished by the use of measurements made in the 80 by 120 ft Wind Tunnel of the lift, rolling moment, and downwash in the wake of three configurations of a model of a subsonic transport aircraft. The downwash measurements are used as input for a vortex-lattice code in order to compute the lift and rolling moment induced on wings that have a span of 0.186, 0.510, or 1.022 times the span of the wake-generating model. Comparison of the computed results with the measured lift and rolling-moment distributions the vortex-lattice method is very reliable as long as the span of the encountering or following wing is less than about 0.2 of the generator span. As the span of the following wing increases above 0.2, the vortex-lattice method continues to correctly predict the trends and nature of the induced loads, but it overpredicts the magnitude of the loads by increasing amounts.
Sikkerhedsbestemmelser for beskæringsarbejde fra lift
Jakobsen, Ole Sejr; Theilby, Frans
2010-01-01
Brug af lift til beskæring og fældning af træer er blevet udbredt i den grønne sektor. Som bruger er det vigtigt at kende den lift, man har valgt, og at arbejdet med motorsav foregår efter Arbejdstilsynets regler og anbefalinger.......Brug af lift til beskæring og fældning af træer er blevet udbredt i den grønne sektor. Som bruger er det vigtigt at kende den lift, man har valgt, og at arbejdet med motorsav foregår efter Arbejdstilsynets regler og anbefalinger....
Adaptation of lift forces in object manipulation through action observation.
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.
Masculinity and Lifting Accidents among Danish Ambulance Personnel
Hansen, Claus D.; Nielsen, Kent J
Background Work injuries related to lifting are the most prevalent among ambulance personnel (AP) despite the introduction of ‘assistive technologies’ (AT) that help reduce situations of manual lifting. One third of the AP report using AT only ‘sometimes’ and 10% report having lifted a patient...... alone. For those 5% scoring lowest on MRNI the probability of reporting lifting alone was 6% while this figure was 17% for those scoring above the 95th percentile. Conclusion This study suggests that male ambulance workers performance of masculinity might pose a threat to their safety. AP...
Lift augmentation for highly swept wing aircraft
Rao, Dhanvada M. (Inventor)
1993-01-01
A pair of spaced slots, disposed on each side of an aircraft centerline and spaced well inboard of the wing leading edges, are provided in the wing upper surfaces and directed tangentially spanwise toward thin sharp leading wing edges of a highly swept, delta wing aircraft. The slots are individually connected through separate plenum chambers to separate compressed air tanks and serve, collectively, as a system for providing aircraft lift augmentation. A compressed air supply is tapped from the aircraft turbojet power plant. Suitable valves, under the control of the aircraft pilot, serve to selective provide jet blowing from the individual slots to provide spanwise sheets of jet air closely adjacent to the upper surfaces and across the aircraft wing span to thereby create artificial vortices whose suction generate additional lift on the aircraft. When desired, or found necessary, unequal or one-side wing blowing is employed to generate rolling moments for augmented lateral control. Trailing flaps are provided that may be deflected differentially, individually, or in unison, as needed for assistance in take-off or landing of the aircraft.
AMS gets lift on space shuttle Discovery
2009-01-01
AMS-02, the CERN-recognized experiment that will seek dark matter, missing matter and antimatter in Space aboard the International Space Station (ISS), has recently got the green light to be part of the STS-134 NASA mission in 2010. Installation of AMS detectors in the Prévessin experiment hall.In a recent press release, NASA announced that the last or last-but-one mission of the Space Shuttle programme would be the one that will deliver AMS, the Alpha Magnetic Spectrometer, to the International Space Station. The Space Shuttle Discovery is due to lift off in July 2010 from Kennedy Space Center and its mission will include the installation of AMS to the exterior of the space station, using both the shuttle and station arms. "It wasn’t easy to get a lift on the Space Shuttle from the Bush administration," says professor Samuel Ting, spokesperson of the experiment, "since during his administration all the funds for space research w...
Does Malleolus non-Lifting Tympanoplasty have any Advantage Over Malleus Lifting Technique?
Mohammad Reza Vahidi
2016-01-01
Full Text Available Introduction: In order to achieve a higher success rate for tympanoplasty, different techniques have been developed, and a wide variety of grafting materials have been developed. One of the techniques currently receiving considerable attention involves not lifting the remaining of eardrum from the malleus and embedding the graft underneath in order to repair the eardrum correctly in its original position, as well as minimizing graft lateralization leading to progression of hearing rehabilitation. We compared the effects of tympanoplasty with and without malleus lifting on hearing loss in patients with chronic otitis media. Materials and Methods: In this study, 30 consecutive patients diagnosed as having chronic otitis media without cholesteatoma were randomly assigned to two tympanoplasty groups; with or without malleus lifting. Air and bone conduction thresholds were recorded before and 45 days after the intervention. Results: In groups, except for 8000 Hz, the air conduction was significantly improved following surgery. According to air conduction there was no difference between the groups before surgery at different frequencies, although it was improved to a greater degree in the group without lifting at 250 Hz postoperatively. The average post-operative air-bone gap (ABG gain was significantly higher in all study frequencies in the target group. One of the effects of this technique is inner-ear protection from physical trauma to the ossicular chain, and prevention of damage to bone conduction. Conclusion: A higher hearing threshold and also higher ABG gain can be achieved by not lifting the remaining eardrum from the malleus and embedding the graft undereath it, especially at lower frequencies.
Zehnder, Michele; Favrat, Daniel
2005-01-01
This thesis presents a system approach with the aim to develop improved concepts for small capacity, high temperature lift air-water heat pumps. These are intended to replace fuel fired heating systems in the residential sector, which leads to a major reduction of the local greenhouse gas emissions. Unfavorable temperature conditions set by the existing heat distribution systems and by the use of atmospheric air, as the only accessible heat source, have to be overcome. The proposed concepts a...
Sensorimotor memory biases weight perception during object lifting
Vonne evan Polanen
2015-12-01
Full Text Available 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, the 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
Levator plate upward lift and levator muscle strength
Rostaminia, Ghazaleh; Peck, Jennifer; Quiroz, Lieschen; Shobeiri, S. Abbas
2016-01-01
Objective The aim of study was to compare digital palpation with the levator plate lift measured by endovaginal and transperineal dynamic ultrasound. Methods Dynamic transperineal and endovaginal ultrasound were performed as part of multicompartmental pelvic floor functional assessment. Patients were instructed to perform Kegels while a probe captured the video clip of the levator plate movement at rest and during contraction in 2D mid-sagittal posterior view. We measured the distance between the levator plate and the probe on endovaginal ultrasound as well as the distance between the levator plate and the gothic arch of the pubis in transperineal ultrasound. The change in diameter (lift) and a levator plate lift ratio (lift / rest) x 100) were calculated. Pelvic floor muscle strength was assessed by digital palpation and divided into functional and non-functional groups using the Modified Oxford Scale (MOS). Mean differences in levator plate upward lifts were compared by MOS score using student t-tests and analysis of variance (ANOVA). Results 74 women were available for analysis. The mean age was 55 (SD±11.9). When measured by vaginal dynamic ultrasound, mean values of the lift and lift/rest ratio increased with increasing MOS score (ANOVA p=0.09 and p=0.04, respectively). When MOS scores were categorized to represent non-functional (MOS 0-1) and functional (MOS 2-5) muscle strength groups, the mean values of the lift (3.2 mm vs. 4.6 mm, p=0.03) and lift/rest ratio (13% vs 20%, p=0.01) were significantly higher in women with functional muscle strength. All patients with ≥ 30% lift detected by vaginal ultrasound had functional muscle strength. Conclusions Greater levator plate lift ratio detected by dynamic endovaginal ultrasound was associated with higher muscle strength as determined by MOS. This novel measurement can be incorporated into ultrasound evaluation of the levator ani function. PMID:26333568
Separation of blood cells using hydrodynamic lift
Geislinger, T. M.; Eggart, B.; Braunmüller, S.; Schmid, L.; Franke, T.
2012-04-01
Using size and deformability as intrinsic biomarkers, we separate red blood cells (RBCs) from other blood components based on a repulsive hydrodynamic cell-wall-interaction. We exploit this purely viscous lift effect at low Reynolds numbers to induce a lateral migration of soft objects perpendicular to the streamlines of the fluid, which closely follows theoretical prediction by Olla [J. Phys. II 7, 1533, (1997)]. We study the effects of flow rate and fluid viscosity on the separation efficiency and demonstrate the separation of RBCs, blood platelets, and solid microspheres from each other. The method can be used for continuous and label-free cell classification and sorting in on-chip blood analysis.
Fixed Wordsize Implementation of Lifting Schemes
Tanja Karp
2007-01-01
Full Text Available 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.
Fitness Tracker for Weight Lifting Style Workouts
Wihl, B. M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
2017-02-01
This document proposes an early, high level design for a fitness tracking system which can automatically log weight lifting style workouts. The system will provide an easy to use interface both physically through the use of several wireless wristband style motion trackers worn on the limbs, and graphically through a smartphone application. Exercise classification will be accomplished by calibration of the user’s specific motions. The system will accurately track a user’s workout, miscounting no more than one repetition in every 20, have sufficient battery life to last several hours, work with existing smartphones and have a cost similar to those of current fitness tracking devices. This document presents the mission background, current state-of-theart, stakeholders and their expectations, the proposed system’s context and concepts, implementation concepts, system requirements, first sublevel function decomposition, possible risks for the system, and a reflection on the design process.
Insulation Test Cryostat with Lift Mechanism
Fesmire, James E. (Inventor); Dokos, Adam G. (Inventor)
2016-01-01
A multi-purpose, cylindrical thermal insulation test apparatus is used for testing insulation materials and systems of materials using a liquid boil-off calorimeter system for absolute measurement of the effective thermal conductivity (k-value) and heat flux of a specimen material at a fixed environmental condition (cold-side temperature, warm-side temperature, vacuum pressure level, and residual gas composition). An inner vessel receives liquid with a normal boiling point below ambient temperature, such as liquid nitrogen, enclosed within a vacuum chamber. A cold mass assembly, including upper and lower guard chambers and middle test vessel, is suspended from a lid of the vacuum canister. Each of the three chambers is filled and vented through a single feedthrough. All fluid and instrumentation feedthroughs are mounted and suspended from a top domed lid allowing easy removal of the cold mass. A lift mechanism allows manipulation of the cold mass assembly and insulation test article.
Vector lifting schemes for stereo image coding.
Kaaniche, Mounir; Benazza-Benyahia, Amel; Pesquet-Popescu, Béatrice; Pesquet, Jean-Christophe
2009-11-01
Many research efforts have been devoted to the improvement of stereo image coding techniques for storage or transmission. In this paper, we are mainly interested in lossy-to-lossless coding schemes for stereo images allowing progressive reconstruction. The most commonly used approaches for stereo compression are based on disparity compensation techniques. The basic principle involved in this technique first consists of estimating the disparity map. Then, one image is considered as a reference and the other is predicted in order to generate a residual image. In this paper, we propose a novel approach, based on vector lifting schemes (VLS), which offers the advantage of generating two compact multiresolution representations of the left and the right views. We present two versions of this new scheme. A theoretical analysis of the performance of the considered VLS is also conducted. Experimental results indicate a significant improvement using the proposed structures compared with conventional methods.
Development of a Marine Propeller With Nonplanar Lifting Surfaces
Andersen, Poul; Friesch, Jürgen; Kappel, Jens J.
2005-01-01
The principle of non-planar lifting surfaces is applied to the design of modern aircraft wings to obtain better lift to drag ratios. Whereas a pronounced fin or winglet at the wingtip has been developed for aircraft, the application of the nonplanar principle to marine propellers, dealt...
49 CFR 178.812 - Top lift test.
2010-10-01
... devices, so that the hoisting forces are applied vertically, for a period of five minutes; and (ii) Lifted by each pair of diagonally opposite lifting devices, so that the hoisting forces are applied towards... designed until clear of the floor and maintained in that position for a period of five minutes. (2)...
Effect of ship motion on spinal loading during manual lifting
Faber, G.S.; Kingma, I.; Delleman, N.; Dieën, J. van
2008-01-01
This study investigated the effects of ship motion on peak spinal loading during lifting. All measurements were done on a ship at sea. In 1-min trials, which were repeated over a wide range of sailing conditions, subjects lifted an 18 kg box five times. Ship motion, whole body kinematics, ground rea
UF{sub 6} cylinder lifting equipment enhancements
Hortel, J.M. [Martin Marietta Energy Systems, Inc., Piketon, OH (United States)
1991-12-31
This paper presents numerous enhancements that have been made to the Portsmouth lifting equipment to ensure the safe handling of cylinders containing liquid uranium hexafluoride (UF{sub 6}). The basic approach has been to provide redundancy to all components of the lift path so that any one component failure would not cause the load to drop or cause any undesirable movement.
On the Relationship between Integer Lifting and Rounding Transform
R. Vargic
2007-12-01
Full Text Available In this paper we analyze the relationship between integer Lifting scheme and Rounding transform as means to compute the wavelet transform in signal processing area. We bring some new results which better describe relationship, reversibility and equivalence of integer lifting scheme and rounding transform concept.
Efficient assessment of exposure to manual lifting using company data
van der Beek, Allard J.; Mathiassen, Svend Erik; Burdorf, Alex
2013-01-01
The objective of this study, based on an extensive dataset on manual materials handling during scaffolding, was to explore whether routinely collected company data can be used to estimate exposure to manual lifting. The number of manual lifts of scaffold parts while constructing/dismantling scaffold
Efficient assessment of exposure to manual lifting using company data
Beek, A.J. van der; Mathiassen, S.E.; Burdorf, A.
2013-01-01
The objective of this study, based on an extensive dataset on manual materials handling during scaffolding, was to explore whether routinely collected company data can be used to estimate exposure to manual lifting.The number of manual lifts of scaffold parts while constructing/dismantling scaffolds
Effect of ship motion on spinal loading during manual lifting
Faber, G.S.; Kingma, I.; Delleman, N.; Dieën, J. van
2008-01-01
This study investigated the effects of ship motion on peak spinal loading during lifting. All measurements were done on a ship at sea. In 1-min trials, which were repeated over a wide range of sailing conditions, subjects lifted an 18 kg box five times. Ship motion, whole body kinematics, ground
A design and analysis approach for drag reduction on aircraft with adaptive lifting surfaces
Cusher, Aaron Anthony
Adaptive lifting surfaces, which can be tailored for different flight conditions, have been shown to be beneficial for drag reduction when compared with conventional non-adaptive surfaces. Applying multiple trailing-edge flaps along the wing span allows for the redistribution of lift to suit different flight conditions. The current approach uses the trailing-edge flap distribution to reduce both induced- and profile- components of drag with a trim constraint. Induced drag is reduced by optimally redistributing the lift between the lifting surfaces and along the span of each surface. Profile drag is reduced through the use of natural laminar flow airfoils, which maintain distinct low-drag-ranges (drag buckets) surrounding design lift values. The low-drag-ranges can be extended to include off-design values through small flap deflections, similar to cruise flaps. Trim is constrained for a given static margin by considering longitudinal pitching moment contributions from changes in airfoil section due to individual flap deflections, and from the redistribution of fore-and-aft lift due to combination of flap deflections. The approach uses the concept of basic and additional lift to linearlize the problem, which allows for standard constrained-minimization theory to be employed for determining optimal flap-angle solutions. The resulting expressions for optimal flap-angle solutions are presented as simple matrix equations. This work presents a design and analysis approach which is used to produce flap-angle solutions that independently reduce induced, profile, and total drag. Total drag is defined to be the sum of the induced- and profile-components of drag. The general drag reduction approach is adapted for each specific situation to develop specific drag reduction schemes that are applied to single- and multiple-surface configurations. Successful results show that, for the application of the induced drag reduction schemes on a tailless aircraft, near-elliptical lift
Shape Design of Lifting body Based on Genetic Algorithm
Yongyuan Li
2010-11-01
Full Text Available This paper briefly introduces the concept and history of lifting body, and puts forward a new method for the optimization of lifting body. This method has drawn lessons from the die line design of airplane is used to parametric numerical modeling for the lifting body, and extract the characterization of shape parameters as design variables, a combination of lifting body reentry vehicle aerodynamic conditions, aerodynamic heating, volumetric Rate and the stability of performance. Multi-objective hybrid genetic algorithm is adopted to complete the aerodynamic shape optimization and design of hypersonic lifting body vehicle when under more variable and constrained condition in order to obtain the Pareto optimal solution of Common Aero Vehicle shape.
Refined AFC-Enabled High-Lift System Integration Study
Hartwich, Peter M.; Shmilovich, Arvin; Lacy, Douglas S.; Dickey, Eric D.; Scalafani, Anthony J.; Sundaram, P.; Yadlin, Yoram
2016-01-01
A prior trade study established the effectiveness of using Active Flow Control (AFC) for reducing the mechanical complexities associated with a modern high-lift system without sacrificing aerodynamic performance at low-speed flight conditions representative of takeoff and landing. The current technical report expands on this prior work in two ways: (1) a refined conventional high-lift system based on the NASA Common Research Model (CRM) is presented that is more representative of modern commercial transport aircraft in terms of stall characteristics and maximum Lift/Drag (L/D) ratios at takeoff and landing-approach flight conditions; and (2) the design trade space for AFC-enabled high-lift systems is expanded to explore a wider range of options for improving their efficiency. The refined conventional high-lift CRM (HL-CRM) concept features leading edge slats and slotted trailing edge flaps with Fowler motion. For the current AFC-enhanced high lift system trade study, the refined conventional high-lift system is simplified by substituting simply-hinged trailing edge flaps for the slotted single-element flaps with Fowler motion. The high-lift performance of these two high-lift CRM variants is established using Computational Fluid Dynamics (CFD) solutions to the Reynolds-Averaged Navier-Stokes (RANS) equations. These CFD assessments identify the high-lift performance that needs to be recovered through AFC to have the CRM variant with the lighter and mechanically simpler high-lift system match the performance of the conventional high-lift system. In parallel to the conventional high-lift concept development, parametric studies using CFD guided the development of an effective and efficient AFC-enabled simplified high-lift system. This included parametric trailing edge flap geometry studies addressing the effects of flap chord length and flap deflection. As for the AFC implementation, scaling effects (i.e., wind-tunnel versus full-scale flight conditions) are addressed
[Lifting-thrusting and rotating manipulations: a comparison on energy input].
Wang, Xi-ming
2011-01-01
Through the energy input model of lifting-thrusting and rotating manipulations, using the theory of energy density, energy flux density and sound intensity level in physics, the average energy flux intensity and frequency distributions of average poynting's vector were calculated respectively within the range of infrasound. According to the distribution table, it was discovered that both of the energy flux density and sound intensity level during the process of acupuncture were high. And it was concluded that the essence of meridians was probably fascial tissues which were rich in elastic fibers and collagenous fibers. The heat-producing needling with reinforcing effect (setting the moutain on fire) which focused on forceful thrusting was held to be the result of the action of same position solitary wave. And the coolness-producing needling with reducing effect (thorough heavenly cool) emphasized on the manipulation of forceful lifting was considered as the action of opposite position solitary wave. The energy input of lifting-thrusting manipulation is comparatively larger than the rotating method, however without significant difference. The speed of manipulations applied is regarded to have greater impact on energy transmission. And the energy produced by rotating manipulation can be better transmitted through meridians.
Carbon Nanotube Arrays with Strong Shear Binding-On and Easy Normal Lifting-Off
Qu, Liangti; Dai, Liming; Stone, Morley; Xia, Zhenhai; Wang, Zhong Lin
2008-10-01
The ability of gecko lizards to adhere to a vertical solid surface comes from their remarkable feet with aligned microscopic elastic hairs. By using carbon nanotube arrays that are dominated by a straight body segment but with curly entangled top, we have created gecko-foot mimetic dry adhesives that show macroscopic adhesive forces of ~100 newtons per square centimeter, almost 10 times that of a gecko foot, and a much stronger shear adhesion force than the normal adhesion force, to ensure strong binding along the shear direction and easy lifting in the normal direction. This anisotropic force distribution is due to the shear-induced alignments of the curly segments of the nanotubes. The mimetic adhesives can be alternatively binding-on and lifting-off over various substrates for simulating the walking of a living gecko.
FENG Ya-li; ZHANG Wen-ming; FENG Fu-zhang
2006-01-01
A flexible connector of lifting pipes in a deep sea mining system is designed. The buttress thread (based on API standard) is used and foreign experience in connector design is referred to. With this kind of connector, the lifting pipe will only bear the axial force, free of moment. The strength of the connector is analyzed in detail, including the connecting strength of the buttress thread, the dynamic load of the pipe system, pressures inside and outside of the pipe, the lateral stress of the pipe wall and so on. Especially, a geometric model is built for 3-D contact stress analysis. The distribution graph of contact stress is presented. It is indicated that the strength of the spherical connector meets the demand.
GENETIC ALGORITHMS AND GAME THEORY FOR HIGH LIFT DESIGN PROBLEMS IN AERODYNAMICS
PériauxJacques; WangJiangfeng; WuYizhao
2002-01-01
A multi-objective evolutionary optimization method (combining genetic algorithms(GAs)and game theory(GT))is presented for high lift multi-airfoil systems in aerospace engineering.Due to large dimension global op-timization problems and the increasing importance of low cost distributed parallel environments,it is a natural idea to replace a globar optimization by decentralized local sub-optimizations using GT which introduces the notion of games associated to an optimization problem.The GT/GAs combined optimization method is used for recon-struction and optimization problems by high lift multi-air-foil desing.Numerical results are favorably compared with single global GAs.The method shows teh promising robustness and efficient parallel properties of coupled GAs with different game scenarios for future advanced multi-disciplinary aerospace techmologies.
EMG Processing Based Measures of Fatigue Assessment during Manual Lifting
E. F. Shair
2017-01-01
Full Text Available Manual lifting is one of the common practices used in the industries to transport or move objects to a desired place. Nowadays, even though mechanized equipment is widely available, manual lifting is still considered as an essential way to perform material handling task. Improper lifting strategies may contribute to musculoskeletal disorders (MSDs, where overexertion contributes as the highest factor. To overcome this problem, electromyography (EMG signal is used to monitor the workers’ muscle condition and to find maximum lifting load, lifting height and number of repetitions that the workers are able to handle before experiencing fatigue to avoid overexertion. Past researchers have introduced several EMG processing techniques and different EMG features that represent fatigue indices in time, frequency, and time-frequency domain. The impact of EMG processing based measures in fatigue assessment during manual lifting are reviewed in this paper. It is believed that this paper will greatly benefit researchers who need a bird’s eye view of the biosignal processing which are currently available, thus determining the best possible techniques for lifting applications.
EMG Processing Based Measures of Fatigue Assessment during Manual Lifting
Marhaban, M. H.; Abdullah, A. R.
2017-01-01
Manual lifting is one of the common practices used in the industries to transport or move objects to a desired place. Nowadays, even though mechanized equipment is widely available, manual lifting is still considered as an essential way to perform material handling task. Improper lifting strategies may contribute to musculoskeletal disorders (MSDs), where overexertion contributes as the highest factor. To overcome this problem, electromyography (EMG) signal is used to monitor the workers' muscle condition and to find maximum lifting load, lifting height and number of repetitions that the workers are able to handle before experiencing fatigue to avoid overexertion. Past researchers have introduced several EMG processing techniques and different EMG features that represent fatigue indices in time, frequency, and time-frequency domain. The impact of EMG processing based measures in fatigue assessment during manual lifting are reviewed in this paper. It is believed that this paper will greatly benefit researchers who need a bird's eye view of the biosignal processing which are currently available, thus determining the best possible techniques for lifting applications. PMID:28303251
Lifting kernel-based sprite codec
Dasu, Aravind R.; Panchanathan, Sethuraman
2000-12-01
The International Standards Organization (ISO) has proposed a family of standards for compression of image and video sequences, including the JPEG, MPEG-1 and MPEG-2. The latest MPEG-4 standard has many new dimensions to coding and manipulation of visual content. A video sequence usually contains a background object and many foreground objects. Portions of this background may not be visible in certain frames due to the occlusion of the foreground objects or camera motion. MPEG-4 introduces the novel concepts of Video Object Planes (VOPs) and Sprites. A VOP is a visual representation of real world objects with shapes that need not be rectangular. Sprite is a large image composed of pixels belonging to a video object visible throughout a video segment. Since a sprite contains all parts of the background that were at least visible once, it can be used for direct reconstruction of the background Video Object Plane (VOP). Sprite reconstruction is dependent on the mode in which it is transmitted. In the Static sprite mode, the entire sprite is decoded as an Intra VOP before decoding the individual VOPs. Since sprites consist of the information needed to display multiple frames of a video sequence, they are typically much larger than a single frame of video. Therefore a static sprite can be considered as a large static image. In this paper, a novel solution to address the problem of spatial scalability has been proposed, where the sprite is encoded in Discrete Wavelet Transform (DWT). A lifting kernel method of DWT implementation has been used for encoding and decoding sprites. Modifying the existing lifting scheme while maintaining it to be shape adaptive results in a reduced complexity. The proposed scheme has the advantages of (1) avoiding the need for any extensions to image or tile border pixels and is hence superior to the DCT based low latency scheme (used in the current MPEG-4 verification model), (2) mapping the in place computed wavelet coefficients into a zero
The Lifting Scheme Based on the Second Generation Wavelets
FENG Hui; GUO Lanying; XIAO Jinsheng
2006-01-01
The lifting scheme is a custom-design construction of Biorthogonal wavelets, a fast and efficient method to realize wavelet transform, which provides a wider range of application and efficiently reduces the computing time with its particular frame. This paper aims at introducing the second generation wavelets, begins with traditional Mallat algorithms, illustrates the lifting scheme and brings out the detail steps in the construction of Biorthogonal wavelets. Because of isolating the degrees of freedom remaining the biorthogonality relations, we can fully control over the lifting operators to design the wavelet for a particular application, such as increasing the number of the vanishing moments.
Hydrofoils: optimum lift-off speed for sailboats.
Baker, R M
1968-12-13
For a hydrofoil sailboat there is a unique optimum lift-off speed. Before this speed is reached, if there are no parasitic vertical hydrofoil appendages, the submerged or partially submerged hydrofoils increase drag and degrade performance. As soon as this speed is reached and the hydrofoils are fully and promptly deployed, the performance of a hydrofoil-borne craft is significantly improved. At speeds exceeding optimum lift-off speed, partially submerged hydrofoils impair performance if there is no significant effect of loading on the hydrofoil lift-to-drag ratio.
Neurologic disorders associated with weight lifting and bodybuilding.
Busche, Kevin
2009-02-01
Weight lifting and other forms of strength training are becoming more common because of an increased awareness of the need to maintain individual physical fitness. Emergency room data indicate that injuries caused by weight training have become more universal over time, likely because of increased participation rates. Neurologic injuries can result from weight lifting and related practices. Although predominantly peripheral nervous system injuries have been described, central nervous system disease may also occur. This article illustrates the types of neurologic disorders associated with weight lifting.
Heavy Lift Launch Capability with a New Hydrocarbon Engine
Threet, Grady E., Jr.; Holt, James B.; Philips, Alan D.; Garcia, Jessica A.
2011-01-01
The Advanced Concepts Office at NASA's George C. Marshall Space Flight Center was tasked to define the thrust requirement of a new liquid oxygen rich staged combustion cycle hydrocarbon engine that could be utilized in a launch vehicle to meet NASA s future heavy lift needs. Launch vehicle concepts were sized using this engine for different heavy lift payload classes. Engine out capabilities for one of the heavy lift configurations were also analyzed for increased reliability that may be desired for high value payloads or crewed missions. The applicability for this engine in vehicle concepts to meet military and commercial class payloads comparable to current ELV capability was also evaluated.
Drag and lift coefficients evolution of a Savonius rotor
Chauvin, A.; Benghrib, D.
1989-10-01
The lift and drag coefficients of the rotating Savonius wind machine are determined from the pressure difference measured between the upper plane and the lower plane of a blade. Pressure measurements have been performed for two sets of experiments; the first one for U ∞ = 10 m/s and the second one for U ∞ = 12.5 m/s. In each case it is to be noted that a negative lift effect is present for low values of the tip speed ratio λ. The lift coefficient becomes positive when λ increases. The drag coefficient is of course always negative.
General equilibrium characteristics of a dual-lift helicopter system
Cicolani, L. S.; Kanning, G.
1986-01-01
The equilibrium characteristics of a dual-lift helicopter system are examined. The system consists of the cargo attached by cables to the endpoints of a spreader bar which is suspended by cables below two helicopters. Results are given for the orientation angles of the suspension system and its internal forces, and for the helicopter thrust vector requirements under general circumstances, including nonidentical helicopters, any accelerating or static equilibrium reference flight condition, any system heading relative to the flight direction, and any distribution of the load to the two helicopters. Optimum tether angles which minimize the sum of the required thrust magnitudes are also determined. The analysis does not consider the attitude degrees of freedom of the load and helicopters in detail, but assumes that these bodies are stable, and that their aerodynamic forces in equilibrium flight can be determined independently as functions of the reference trajectory. The ranges of these forces for sample helicopters and loads are examined and their effects on the equilibrium characteristics are given parametrically in the results.
KOr.U Face Lift: Personal Technique.
Colombo, Giuseppe; Ruvolo, Vittorio; Pagliarulo, Valentina
2015-03-01
Facial aging is the union of multiple effects such as exposure to the sun, ambiental stress, smog, tobacco. It reflects the dynamic, cumulative effects of time on the skin, soft tissues, and deep structural components of the face showing skin textural changes and loss of facial volume. There are a multitude of techniques currently used to perform face lifts, but the unique objective is to achieve a good and safe result. This paper describes a new safe approach to midfacial rejuvenation that combines the elements of superficial musculoaponeurotic system (SMAS) plication, about four vectors, with a blepharoplasty to achieve long-lasting improvement of the aging midface and a more natural effect. Plication of the SMAS over the suture, provides three vectors of elevation beneath the skin in midface rhytidectomy linked to the Lorè's fascia and the third vector of elevation of platysma behind the ear. This new technique, called KOr.U technique, was used in 31 patients between October 2010 and October 2012, producing effective long-lasting results, returning a volume of midface with no injury. This simplified approach is safe and can be easily performed under local anesthesia as an isolated midface procedure, avoiding the facial nerve.
Lotz, Christy A; Agnew, Michael J; Godwin, Alison A; Stevenson, Joan M
2009-04-01
Occupations demanding frequent and heavy lifting are associated with an increased risk of injury. A personal lift assist device (PLAD) was designed to assist human muscles through the use of elastic elements. This study was designed to determine if the PLAD could reduce the level of general and local back muscle fatigue during a cyclical lifting task. Electromyography of two erector spinae sites (T9 and L3) was recorded during a 45-min lifting session at six lifts/lowers per minute in which male participants (n=10) lifted a box scaled to represent 20% of their maximum back extensor strength. The PLAD device reduced the severity of muscular fatigue at both muscle sites. RMS amplitude increased minimally (22% and 26%) compared to the no-PLAD condition (104% and 88%). Minimal median frequency decreases (0.33% and 0.41%) were observed in the PLAD condition compared to drops of 12% and 20% in the no-PLAD condition. The PLAD had an additional benefit of minimizing pre-post changes in muscular strength and endurance. The PLAD also resulted in a significantly lower rate of perceived exertion across the lifting session. It was concluded that the PLAD was effective at decreasing the level of back muscular fatigue.
49 CFR 178.811 - Bottom lift test.
2010-10-01
... truck with the forks centrally positioned and spaced at three quarters of the dimension of the side of... bottom lift test. The IBC must be loaded to 1.25 times its maximum permissible gross mass, the load...
Simultaneous oroantral communication closure, sinus‑lifting, and ...
2015-10-10
Oct 10, 2015 ... revealed healthy and functional implants in the teeth area. Key words: .... the development of several alternative treatment modalities by some ... 1. Lee BK. One‑stage operation of large oroantral fistula closure, sinus lifting,.
Lift-Off Processing and Superconducting Circuit Coherence
Quintana, C. M.; Megrant, A.; Dunsworth, A.; Chen, Zijun; Chiaro, B.; Barends, R.; Campbell, B.; Chen, Yu; Jeffrey, E.; Kelly, J.; Mutus, J. Y.; Neill, C.; O'Malley, P. J. J.; Roushan, P.; Sank, D.; Wenner, J.; White, T. C.; Cleland, A. N.; Martinis, John M.
2014-03-01
As superconducting circuit coherence continues to increase, careful attention must be paid to device fabrication techniques. Substantial evidence points to dielectric loss from two-level state defects in thin amorphous interfacial regions as a limiting relaxation mechanism for superconducting qubits. Transmon qubits have traditionally been fabricated using lift-off aluminum deposited together with their Josephson junctions; however, improved coherence times have recently been found in transmons which use lift-off metal for only a small fraction of the qubit. To better understand this improvement and predict any remaining limits imposed by the incorporation of lift-off, we characterize the increased loss found in coplanar waveguide resonators formed with lift-off metal. We vary surface treatment such as oxygen ashing and ion milling, and study the effects of double-angle evaporation, e-beam resist residue, and surface roughness on resonator quality factors.
Lifting of a sector block for YE-2 at Kawasaki.
R. Loveless/U. of Wisconsin
2000-01-01
YE-2 is build from machined sector blocks. Trial assembly is carried out horizontally. This picture represents the lifting of a machined sector block destined to the trial assembly of a half disk YE-2 at Kawasaki (KHI) Kobe, Japan.
Linnainstallatsioonide festival Tallinnas 2011 ehk "Lift11" / Margit Aule
Aule, Margit
2011-01-01
Tallinna linnainstallatsioonide festivalist "LIFT11", konkursist. 10 installatsioonist (nimetatud autorid), millest avlikku ruumi on jõudnud 8 installatsiooni. Intervjuu installatsiooni "Face it", mille sünd on veel kahtluse all, autorite Argo Peeveri ja Margus Tammega
Advanced Epitaxial Lift-Off Quantum Dot Photovoltaic Devices Project
National Aeronautics and Space Administration — We propose to develop a high-efficiency, triple-junction, epitaxial lift-off (ELO) solar cell by incorporating quantum dots (QDs) within the current-limiting...
"LIFT11" lõpetab installatsioon "Rada metsas" / Margit Aule
Aule, Margit
2011-01-01
Kadrioru pargis 24.09.-22.10.2011 avatud jaapani arhitekti Tetsuo Kondo installatsioonist "Rada metsas", linnainstallatsioonide festivali LIFT11 viimasest ja suurimast teosest. Installatsiooni on rahastanud Jaapani Fond. Arhitektist
Large-Eddy Simulations of Flapping-Induced Lift Enhancement
Franck, Jennifer; Swartz, Sharon; Breuer, Kenneth
2011-11-01
This work isolates the heaving motion of flapping flight in order to numerically investigate the fluid-structure interaction at Reynolds numbers relevant to birds and bats. Although there has been much focus on insect flight, larger vertebrates fly at a higher Reynolds number, which leads to different dynamics in terms of flow separation, reattachment, and high-lift mechanisms. In this work, an incompressible large-eddy simulation is used to simulate the periodic heaving of a flat plate at various angles of attack. It is found that the heaving motion can increase the average lift when compared with the steady flow, more so than is expected from the relative angle of attack. The additional lift is attributed to the vortex dynamics at the leading edge. The lift enhancement and flow features are compared with experimental results.
Lift and Drag Performance of Odontocete Cetacean Flippers
2009-01-01
Cooper et al., 2008). The cross-section of a typical flipper is similar to that of a modern engineered air/ hydrofoil (Fish, 2004; Miklosovic et al., 2004...to modern engineered hydrofoils , which have hydrodynamic properties such as lift coefficient, drag coefficient and associated efficiency. Field...study are differentiated by whether or not their lift curves are linear. An engineered hydrofoil with linear behavior in the non-stall region was also
Fuzzy-PID controlled lift feedback fin stabilizer
LIANG Yan-hua; JIN Hong-zhang; LIANG Li-hua
2008-01-01
Conventional PID controllers are widely used in fin stabilizer control systems,but they have time-variations,nonlinearity,and uncertainty influencing their control effects.A lift feedback fuzzy-PID control method was developed to better deal with these problems,and this lift feedback fin stabilizer system was simulated under different sea condition.Test results showed the system has better anti-rolling performance than traditional fin-angle PID control systems.
Generalizing Lifted Tensor-Product Wavelets to Irregular Polygonal Domains
Bertram, M.; Duchaineau, M.A.; Hamann, B.; Joy, K.I.
2002-04-11
We present a new construction approach for symmetric lifted B-spline wavelets on irregular polygonal control meshes defining two-manifold topologies. Polygonal control meshes are recursively refined by stationary subdivision rules and converge to piecewise polynomial limit surfaces. At every subdivision level, our wavelet transforms provide an efficient way to add geometric details that are expanded from wavelet coefficients. Both wavelet decomposition and reconstruction operations are based on local lifting steps and have linear-time complexity.
Downhole emulsion breaker injection into the lift gas stream
Lagerlef, D.L.; Sindelar, S.T.; McLelland, W.G.; Blumer, D.J.
1995-12-31
A program is in operation at Prudhoe Bay, Alaska which injects emulsion breaker downhole with lift gas to enhance production. This paper addresses the reasons emulsions can limit production in a gas lifted well and the benefits that can be realized by breaking the emulsion downhole. A discussion of the simple but effective produced fluids emulsion screening test and the field implementation of downhole emulsion breaker in wells at Prudhoe Bay are included in this paper.
Managing cultural diversity in healthcare partnerships: the case of LIFT.
Mannion, Russell; Brown, Sally; Beck, Matthias; Lunt, Neil
2011-01-01
The National Health Service (NHS) Local Improvement Finance Trust (LIFT) programme was launched in 2001 as an innovative public-private partnership to address the historical under-investment in local primary care facilities in England. The organisations from the public and private sector that comprise a local LIFT partnership each have their own distinctive norms of behaviour and acceptable working practices - ultimately different organisational cultures. The purpose of this article is to assess the role of organisational culture in facilitating (or impeding) LIFT partnerships and to contribute to an understanding of how cultural diversity in public-private partnerships is managed at the local level. The approach taken was qualitative case studies, with data gathering comprising interviews and a review of background documentation in three LIFT companies purposefully sampled to represent a range of background factors. Elite interviews were also conducted with senior policy makers responsible for implementing LIFT policy at the national level. Interpreting the data against a conceptual framework designed to assess approaches to managing strategic alliances, the authors identified a number of key differences in the values, working practices and cultures in public and private organisations that influenced the quality of joint working. On the whole, however, partners in the three LIFT companies appeared to be working well together, with neither side dominating the development of strategy. Differences in culture were being managed and accommodated as partnerships matured. As LIFT develops and becomes the primary source of investment for managing, developing and channelling funding into regenerating the primary care infrastructure, further longitudinal work might examine how ongoing partnerships are working, and how changes in the cultures of public and private partners impact upon wider relationships within local health economies and shape the delivery of patient care
Lift augmentation via spanwise tip blowing - A numerical study
Childs, R. E.
1986-01-01
Numerical simulations of a low aspect ratio wing with and without a spanwise directed jet issuing from the wing tip have been performed. The results show that the tip vortex is displaced outward and upward by the blowing. This gives rise to a local lift augmentation mechanism, vortex lift caused by the vortex core being above the wing, and a global mechanism, the reduction of induced velocities due to greater apparent spin.
CT gas lift captures last of field reserves
Tran, T.B.; Miller, J.; Woodell, M.E.; Johnson, H.
1996-06-01
Texaco Exploration and Production Inc.`s (TEPI) Brookeland Field in Newton County, Texas, produces from 30, mostly dual-horizontal, wells in the Austin Chalk reservoir. The wells are typically drilled vertically and casing is set to the top of the Austin Chalk at about 10,000 ft. Building at 15{degree}/100 ft, 4,000-ft laterals are drilled to the northwest and southeast to intersect the natural fractures of the Austin Chalk. The horizontal sections of the wellbore are openhole completions that average 700 b/d of oil and 5 MMcfd of gas. Within 1 year of initial production, the wells require compression to sustain flow and conventional gas lift is used when the wells load up with fluid. Typically, when production declines to 200 Mcfd and 100 b/d of fluid, the gas lift injection point is at 8,000 ft and average gas lift usage is 500 Mcfd. Coiled tubing-conveyed artificial lift was suggested, but first other concerns had to be addressed. The long, horizontal lateral sections functioned as a natural gas and fluid separator, resulting in a distinct slug flow pattern. During a 24-hour period, slug flow caused the wells to produce 100% gas or 100% fluid. For cost reasons TEPI chose conventional, field-installed coiled tubing (CT) gas lift equipment over spoolable equipment. Texaco then formed a team alliance with McMurry-Macco Lift Systems and Dowell to evaluate and complete trial wells with coiled tubing gas lift equipment. This paper reviews the case history of the field, the design considerations of the coiled tubing gas lift, and the surface support equipment used.
Searching for ski-lift injury: an uphill struggle?
Smartt, Pam; Chalmers, David
2010-03-01
Injuries arising from ski-lift malfunction are rare. Most arise from skier error when embarking or disembarking, or from improper lift operation. A search of the literature failed to uncover any studies focusing specifically on ski-lift injuries. The purpose of this study was to identify and characterise ski-lift injury resulting in hospitalisation and comment on barriers to reporting and reporting omissions. New Zealand hospitalised injury discharges 2000-2005 formed the primary dataset. To aid case identification these data were linked to ACC compensated claims for the same period and the data searched for all hospitalised cases of injury arising from ski-lifts. 44 cases were identified representing 2% of snow-skiing/snowboarding cases. 28 cases (64%) were male and 16 (36%) female, the average age was 32 yrs (range 5-73 yrs). The majority of cases were snow-skiers (35 cases, 80%). Most of the injuries were serious, or potentially so, with 1 case of traumatic pneumothorax, one of pulmonary embolism (after jumping from a ski-lift) and 28 cases sustaining fractures (six to the neck-of-femur, one to the lumbar spine and one to the pubis). ICISS scores for all cases ranged from 1.00 to 0.8182 (probability of dying in hospital 0-18.18%). Only 14 (32%) cases could be easily identified from ICD-10-AM e-codes and activity codes in the discharge summary. The ICD-10-AM external cause code for ski-lift injury V98 ("other specified transport accidents") was only assigned to 39% of cases. The type of ski-lift could only be determined in 24 cases (55%).
ANALYSIS OF VIBROACOUSTIC SIGNALS RECORDED IN THE PASSENGER LIFT CABIN
Kamil Szydło
2016-06-01
Full Text Available The analysis of private tests is presented in the article. The applicable tests refer to accelerations, the level of the sound pressure as well as to the sound power emitted by the passenger lift cabin at different technical conditions of the lift. For a group of lifting devices the accelerations were tested at three axes with the use of an accelerometer. The accelerometer was placed in the central part of the cabin with simultaneous measurement of the acoustic parameters with the sound analyzer equipped with the sound volume double microphone probe. The attempt was made to determine the impact of the frame - cabin system construction as well as the lift technical condition on the recorded parameters. It can allow to establish the limit values of the lift structure parameters under which a rapid drop of comfort takes place while travelling in the lift as well as to indicate those construction elements the modification of which would affect the improvement of the operation noiselessness.
Classification of similar medical images in the lifting domain
Sallee, Chad W.; Tashakkori, Rahman
2002-03-01
In this paper lifting is used for similarity analysis and classification of sets of similar medical images. The lifting scheme is an invertible wavelet transform that maps integers to integers. Lifting provides efficient in-place calculation of transfer coefficients and is widely used for analysis of similar image sets. Images of a similar set show high degrees of correlation with one another. The inter-set redundancy can be exploited for the purposes of prediction, compression, feature extraction, and classification. This research intends to show that there is a higher degree of correlation between images of a similar set in the lifting domain than in the pixel domain. Such a high correlation will result in more accurate classification and prediction of images in a similar set. Several lifting schemes from Calderbank-Daubechies-Fauveue's family were used in this research. The research shows that some of these lifting schemes decorrelates the images of similar sets more effectively than others. The research presents the statistical analysis of the data in scatter plots and regression models.
Research on the Aerodynamic Lift of Vehicle Windshield Wiper
Gu Zhengqi
2016-01-01
Full Text Available Currently, research on the aerodynamic lift of vehicle windshield wipers is confined to the steady results, and there are very few test results. In the face of this truth, a wind tunnel test is conducted by using the Multipoint Film Force Test System (MFF. In this test, the aerodynamic lift of four kinds of wiper is measured at different wind speeds and different rotation angles. And then, relevant steady-state numerical simulations are accomplished and the mechanism of the aerodynamic lift is analyzed. Furthermore, combined with dynamic meshing and user-defined functions (UDF, transient aerodynamic characteristics of wipers are obtained through numerical simulations. It is found that the aerodynamic lift takes great effect on the stability of wipers, and there is maximum value of the lift near a certain wind speed and rotation angle. The lift force when wipers are rotating with the free stream is less than steady, and the force when rotating against the free stream is greater than steady.
Lifting particles in martian dust devils by pressure excursions
Koester, Marc; Wurm, Gerhard
2017-10-01
The passage of a dust devil vortex goes along with a pressure reduction above ground. This leads to a sub-soil overpressure. It has been suggested that this enhances the lift on particles and facilitates dust entrainment by dust devils. We quantify the necessary pressure difference to lift fine sand from sand beds with thickness of 50, 150, and 250 mm in laboratory experiments with basalt samples consisting of 63-125 μm grains. The absolute pressure was varied between 1,300 and 3,600 Pa. In general, a pressure differences of about 30 Pa per mm depth is needed to lift sand grains. With slight systematic variations this is in agreement to simply accounting for the weight of a lifted particle layer. On Mars observed absolute pressure difference are several Pa. This limits particle lift to a layer smaller than 100 μm . However, it clearly allows Δp lifting if the top layer has a decreased permeability. This might be the case for dust layers sitting on top of a coarse grained sand bed. These measurements support the idea of enhanced dust entrainment due to the Δp -effect in Martian dust devils under certain conditions.
75 FR 27662 - Special Conditions: Boeing 747-468, Installation of a Medical Lift
2010-05-18
... Medical Lift AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of proposed special... installation of a medical lift. The applicable airworthiness regulations do not contain adequate or appropriate... modification includes the installation of a medical lift between the main deck and upper deck. The lift allows...
49 CFR 571.404 - Standard No. 404; Platform lift installations in motor vehicles.
2010-10-01
... Systems for Motor Vehicles (49 CFR 571.403). S4.1.5Platform lighting on public use lifts. Public use lifts... be equipped with a public use lift certified as meeting Federal Motor Vehicle Safety Standard No. 403... subject to paragraph S4.1.1, must be equipped with a platform lift certified as meeting either the public...
2014-09-18
tech- nical information and knowledge focused specifically on the mechanical lift systems used for raising the structures to elevate and maintain them...international history and the state-of-the-art of building on permanent snowfields, focusing on elevated buildings that are periodi- cally lifted to...systems would have been tanks within ele- ERDC/CRREL SR-14-2 16 vated buildings moved every few years to higher ground by using crawler
Neuromuscular trunk activation patterns in back pain patients during one-handed lifting
Mueller, Juliane; Engel, Tilman; Kopinski, Stephan; Mayer, Frank; Mueller, Steffen
2017-01-01
AIM To analyze neuromuscular activity patterns of the trunk in healthy controls (H) and back pain patients (BPP) during one-handed lifting of light to heavy loads. METHODS After assessment of back pain (graded chronic pain scale according to von Korff) all subjects (n = 43) performed a warm-up (treadmill walking). Next, subjects were instructed to lift 3 × a 20 kg weight placed in front of them (with both hand) onto a table (height: 0.75 m). Subsequently, all subjects lifted with one hand (left-side, 3 repetitions) a weight of 1 kg (light), 10 kg (middle) and 20 kg (heavy) in random order from the ground up onto the table left of them. Trunk muscle activity was assessed with a 12-lead EMG (6 ventral/6 dorsal muscles; 4000 Hz). EMG-RMS (%) was averaged over the 3 repetitions and analyzed for the whole one-handed lifting cycle, then normalized to RMS of the two-handed lifting. Additionally, the mean (normalized) EMG-RMS of four trunk areas [right/left ventral area (VR/VL); right/left dorsal area (DR/DL)] was calculated. Data were analyzed descriptively (mean ± SD) followed by student’s t-test comparing H and BPP (α = 0.05). With respect to the unequal distribution of subjects in H and BPP, a matched-group analysis was conducted. Seven healthy controls were gender- and age-matched (group Hmatched) to the 7 BPP. In addition, task failure was calculated and compared between H/Hmatched vs BPP using χ2. RESULTS Seven subjects (3m/4f; 32 ± 7 years; 171 ± 7 cm; 65 ± 11 kg) were assigned to BPP (pain grade ≥ 2) and 36 (13m/23f; 28 ± 8 years; 174 ± 10 cm; 71 ± 12 kg) to H (pain grade ≤ 1). H and BPP did not differ significantly in anthropometrics (P > 0.05). All subjects were able to lift the light and middle loads, but 57% of BPP and 22% of H were not able to lift the heavy load (all women). χ2 analysis revealed statistically significant differences in task failure between H vs BPP (P = 0.03). EMG-RMS ranged from 33% ± 10%/30% ± 9% (DL, 1 kg) to 356%
Heavy Lift Launch Capability with a New Hydrocarbon Engine (NHE)
Threet, Grady E., Jr.; Holt, James B.; Philips, Alan D.; Garcia, Jessica A.
2011-01-01
The Advanced Concepts Office (ACO) at NASA Marshall Space Flight Center has analyzed over 2000 Ares V and other heavy lift concepts in the last 3 years. These concepts were analyzed for Lunar Exploration Missions, heavy lift capability to Low Earth Orbit (LEO) as well as exploratory missions to other near earth objects in our solar system. With the pending retirement of the Shuttle fleet, our nation will be without a civil heavy lift launch capability, so the future development of a new heavy lift capability is imperative for the exploration and large science missions our Agency has been tasked to deliver. The majority of the heavy lift concepts analyzed by ACO during the last 3 years have been based on liquid oxygen / liquid hydrogen (LOX/LH2) core stage and solids booster stage propulsion technologies (Ares V / Shuttle Derived and their variants). These concepts were driven by the decisions made from the results of the Exploration Systems Architecture Study (ESAS), which in turn, led to the Ares V launch vehicle that has been baselined in the Constellation Program. Now that the decision has been made at the Agency level to cancel Constellation, other propulsion options such as liquid hydrocarbon fuels are back in the exploration trade space. NASA is still planning exploration missions with the eventual destination of Mars and a new heavy lift launch vehicle is still required and will serve as the centerpiece of our nation s next exploration architecture s infrastructure. With an extensive launch vehicle database already developed on LOX/LH2 based heavy lift launch vehicles, ACO initiated a study to look at using a new high thrust (> 1.0 Mlb vacuum thrust) hydrocarbon engine as the primary main stage propulsion in such a launch vehicle.
Shape memory alloy resetable spring lift for pedestrian protection
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.
A second-order shock-expansion method applicable to bodies of revolution near zero lift
1957-01-01
A second-order shock-expansion method applicable to bodies of revolution is developed by the use of the predictions of the generalized shock-expansion method in combination with characteristics theory. Equations defining the zero-lift pressure distributions and the normal-force and pitching-moment derivatives are derived. Comparisons with experimental results show that the method is applicable at values of the similarity parameter, the ratio of free-stream Mach number to nose fineness ratio, from about 0.4 to 2.
Automated gas-lift satellites; Satelites de gas-lift automatizados
Branco, Carlos Eduardo M. [PETROBRAS, Salvador, BA (Brazil). Exploracao e Producao; Lira, Franklin S. [PETROBRAS, Rio de Janeiro, RJ (Brazil). SERINF
1998-12-31
A gas-lift satellite automation system was developed by E and P-BA, exploration and production PETROBRAS unit in Bahia State. In the past, individual digital controllers were installed in each production well. As they were manufactured specifically for the oil industry their prices were high what resulted in high costs to completely install a satellite besides not permitting to synchronize the injection times of the various wells. PC (programmable controllers) were used what enable that one equipment control various wells simultaneously. That enable additional developments in the technology as using operational research to optimize the injection and inactive times so that the number of simultaneous injections were reduced. After the need to go the satellite in order to alter the times was on obstacle. Further development were done to enable the times to be changed remotely using ratio links through a supervisory system running in a microcomputer in an Operation Central. (author) 3 refs., 2 figs.
A comparative study of DRL-lift and lift on integrated polyisobutylene polymer matrices
Dinca, V.; Palla Papavlu, A.; Matei, A.; Luculescu, C.; Dinescu, M.; Lippert, T.; di Pietrantonio, F.; Cannata, D.; Benetti, M.; Verona, E.
2010-11-01
This paper presents a comparative study of polymer pixel on sensors obtained by Laser Induced Forward Transfer (LIFT) assisted by a triazene polymer as Dynamic Release Layer (DRL). Polyisobutylene (PIB) was selected as model for chemoselective polymers which could be used as hydrogen-bond acidic polymer for vapor sensors. PIB films deposited on fused silica, respectively, on triazene polymer coated fused silica substrates were used as targets. Both targets were prepared by Matrix Assisted Pulsed Laser Evaporation (MAPLE). The parameters related to a regular, well-defined transfer were analyzed and compared for the substrates with and without the DRL. The morphological characterization of the transferred PIB was performed by Atomic Force Microscopy (AFM), Optical Microscopy, and Scanning Electron Microscopy (SEM). It was found that a minimal thickness of the dynamic release layer, i.e. 100 nm is required to protect the sensitive PIB polymer in a clean laser transfer process.
Lower body lift with superficial fascial system suspension.
Lockwood, T
1993-11-01
Multiple body contour deformities of the trunk and thighs are commonly treated in separate stages to limit postoperative complications and disability. Recent advances in the surgical design of the medial thigh lift and the lateral thigh/buttock lift along with an understanding of the functional anatomy of the superficial fascial system have significantly improved results and decreased complications of trunk/thigh lifts. The enhanced safety of current trunk/thigh lifts has allowed new combinations to treat multiple body contour deformities in a single stage. Laxity of the entire lower trunk and thigh regions can be treated in one stage in selected patients. The lower body lift combines the transverse flank/thigh/buttock lift and the fascial anchoring medial thigh lift in one operation. In addition to the expected tightening of the flank, buttocks, and total thighs, this procedure results in a surprising degree of epigastric and hypogastric tightening of mild to moderate abdominal laxity without direct surgical undermining or umbilical transposition. Ten patients having the lower body lift alone or in combination with liposuction and other body contouring procedures were followed for 6 to 24 months. The primary indication for surgery is moderate to severe soft-tissue laxity of the lower trunk and thighs with minimal or mild residual fat deposits. Skin contour irregularities due to skin laxity (cellulite of laxity) or to postliposuction adhesions are frequently present and may be severe. Patients with significant fat deposits may be treated initially with liposuction 3 to 4 months earlier to become candidates for this procedure. Key technical elements of this procedure include (1) both supine and lateral decubitus positioning with the hip flexed and abducted to allow overcorrection, (2) appropriate direct surgical undermining through superficial fascial system zones of adherence in the superior thigh while avoiding the lymphatics of the femoral triangle, (3) more
Numerical Study of Transition of an Annular Lift Fan Aircraft
Yun Jiang
2016-09-01
Full Text Available The present study aimed at studying the transition of annular lift fan aircraft through computational fluid dynamics (CFD simulations. The oscillations of lift and drag, the optimization for the figure of merit, and the characteristics of drag, yawing, rolling and pitching moments in transition are studied. The results show that a two-stage upper and lower fan lift system can generate oscillations of lift and drag in transition, while a single-stage inner and outer fan lift system can eliminate the oscillations. The characteristics of momentum drag of the single-stage fans in transition are similar to that of the two-stage fans, but with the peak of drag lowered from 0.63 to 0.4 of the aircraft weight. The strategy to start transition from a negative angle of attack −21° further reduces the peak of drag to 0.29 of the weight. The strategy also reduces the peak of pitching torque, which needs upward extra thrusts of 0.39 of the weight to eliminate. The peak of rolling moment in transition needs differential upward thrusts of 0.04 of the weight to eliminate. The requirements for extra thrusts in transition lead to a total thrust–weight ratio of 0.7, which makes the aircraft more efficient for high speed cruise flight (higher than 0.7 Ma.
Conditional moment closure modeling of a lifted turbulent flame
JIANG Yong; QIU Rong; ZHOU Wei; FAN Weicheng
2005-01-01
Results obtained using conditional moment closure (CMC) approach to modeling a lifted turbulent hydrogen flame are presented. Predictions are based on k-ε-g turbulent closure, a 23-step chemical mechanism and a radially averaged CMC model. The objectives are to find out how radially averaged CMC can represent a lifted flame and which mechanism of flame stabilization can be described by this modeling method. As a first stage of the study of multi-dimensional CMC for large eddy simulation (LES) of the lifted turbulent flames, the effect of turbulence upon combustion is included, the high-order compact finite- difference scheme (Padé) is used and previously developed characteristic-wave-based boundary conditions for multi- component perfect gas mixtures are here extended to their conditional forms but the heat release due to combustion is not part of the turbulent calculations. Attention is focused to the lift-off region of the flame which is commonly considered as a cold flow. Comparison with published experimental data and the computational results shows that the lift-off height can be accurately determined, and Favre averaged radial profiles of temperature and species mole fractions are also reasonably well predicted. Some of the current flame stabilization mechanisms are discussed.
Advances in Engineering Software for Lift Transportation Systems
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.
Experimental research on dust lifting by propagating shock wave
Żydak, P.; Oleszczak, P.; Klemens, R.
2017-03-01
The aim of the presented work was to study the dust lifting process from a layer of dust behind a propagating shock wave. The experiments were conducted with the use of a shock tube and a specially constructed, five-channel laser optical device enabling measurements at five positions located in one vertical plane along the height of the tube. The system enabled measurements of the delay in lifting up of the dust from the layer, and the vertical velocity of the dust cloud was calculated from the dust concentration measurements. The research was carried out for various initial conditions and for three fractions of black coal dust. In the presented tests, three shock wave velocities: 450, 490 and 518 m/s and three dust layer thicknesses, equal to 1.0, 1.5 and 2.0 mm, were taken into consideration. On the grounds of the obtained experimental results, it was assumed that the vertical component of the lifted dust velocity is a function of the dust particle diameter, the velocity of the air flow in the channel, the layer thickness and the dust bulk density. It appeared, however, that lifting up of the dust from the thick layers, thicker than 1 mm, is a more complex process than that from thin layers and still requires further research. A possible explanation is that the shock wave action upon the thick layer results in its aggregation in the first stage of the dispersing process, which suppresses the dust lifting process.
Performance and Vibration Analyses of Lift-Offset Helicopters
Jeong-In Go
2017-01-01
Full Text Available A validation study on the performance and vibration analyses of the XH-59A compound helicopter is conducted to establish techniques for the comprehensive analysis of lift-offset compound helicopters. This study considers the XH-59A lift-offset compound helicopter using a rigid coaxial rotor system as a verification model. CAMRAD II (Comprehensive Analytical Method of Rotorcraft Aerodynamics and Dynamics II, a comprehensive analysis code, is used as a tool for the performance, vibration, and loads analyses. A general free wake model, which is a more sophisticated wake model than other wake models, is used to obtain good results for the comprehensive analysis. Performance analyses of the XH-59A helicopter with and without auxiliary propulsion are conducted in various flight conditions. In addition, vibration analyses of the XH-59A compound helicopter configuration are conducted in the forward flight condition. The present comprehensive analysis results are in good agreement with the flight test and previous analyses. Therefore, techniques for the comprehensive analysis of lift-offset compound helicopters are appropriately established. Furthermore, the rotor lifts are calculated for the XH-59A lift-offset compound helicopter in the forward flight condition to investigate the airloads characteristics of the ABC™ (Advancing Blade Concept rotor.
Unsuccessful vs. successful performance in snatch lifts: a kinematic approach.
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 snatch lifts. Thus, coaches should pay particular attention to the applied force onto the barbell from the first pull.
Lifting Wing in Constructing Tall Buildings —Aerodynamic Testing
Ian Skelton
2014-05-01
Full Text Available This paper builds on previous research by the authors which determined the global state-of-the-art of constructing tall buildings by surveying the most active specialist tall building professionals around the globe. That research identified the effect of wind on tower cranes as a highly ranked, common critical issue in tall building construction. The research reported here presents a design for a “Lifting Wing,” a uniquely designed shroud which potentially allows the lifting of building materials by a tower crane in higher and more unstable wind conditions, thereby reducing delay on the programmed critical path of a tall building. Wind tunnel tests were undertaken to compare the aerodynamic performance of a scale model of a typical “brick-shaped” construction load (replicating a load profile most commonly lifted via a tower crane against the aerodynamic performance of the scale model of the Lifting Wing in a range of wind conditions. The data indicate that the Lifting Wing improves the aerodynamic performance by a factor of up to 50%.
Kuijer, P P F M; van Oostrom, S H; Duijzer, K; van Dieën, J H
2012-01-01
It is unclear whether the maximum acceptable weight of lift (MAWL), a common psychophysical method, reflects joint kinetics when different lifting techniques are employed. In a within-participants study (n = 12), participants performed three lifting techniques--free style, stoop and squat lifting from knee to waist level--using the same dynamic functional capacity evaluation lifting test to assess MAWL and to calculate low back and knee kinetics. We assessed which knee and back kinetic parameters increased with the load mass lifted, and whether the magnitudes of the kinetic parameters were consistent across techniques when lifting MAWL. MAWL was significantly different between techniques (p = 0.03). The peak lumbosacral extension moment met both criteria: it had the highest association with the load masses lifted (r > 0.9) and was most consistent between the three techniques when lifting MAWL (ICC = 0.87). In conclusion, MAWL reflects the lumbosacral extension moment across free style, stoop and squat lifting in healthy young males, but the relation between the load mass lifted and lumbosacral extension moment is different between techniques. Tests of maximum acceptable weight of lift (MAWL) from knee to waist height are used to assess work capacity of individuals with low-back disorders. This article shows that the MAWL reflects the lumbosacral extension moment across free style, stoop and squat lifting in healthy young males, but the relation between the load mass lifted and lumbosacral extension moment is different between techniques. This suggests that standardisation of lifting technique used in tests of the MAWL would be indicated if the aim is to assess the capacity of the low back.
2013-04-01
concrete materials together. The maximum capacity of a single batch in this mixer is approximately 27 ft3. The aggregates are dumped from hydraulically...distributed into the mixer . Following the concrete sand, the ASTM #57 crushed limestone was weighed and added to the mixer . The two aggregates were...ER D C/ G SL T R -1 3 -7 Investigation of Lift Bonding for Roller- Compacted Concrete with Low Normal Loads at Variable Placement Times
To design a belt drive scissor lifting table
Corrado Andrea
2016-02-01
Full Text Available The present work deals with the design of a belt drive scissor lifting table to be install on platforms, called skillet, that constitute a typical line of handling on which the operator can stay and proceed to assembly, with times established by the product manufacturing. The aim of this work is to design a new lifting table with the cheapest actuation commercially available, simple and able to respond to the functional requirements, in order to replace two commercial lifting tables actually in use on the skillets along the handling line. In order to satisfy these requirements, the design has involved two different analysis: a dynamic motion analysis and a structural analysis.
Designs and Technology Requirements for Civil Heavy Lift Rotorcraft
Johnson, Wayne; Yamauchi, Gloria K.; Watts, Michael E.
2006-01-01
The NASA Heavy Lift Rotorcraft Systems Investigation examined in depth several rotorcraft configurations for large civil transport, designed to meet the technology goals of the NASA Vehicle Systems Program. The investigation identified the Large Civil Tiltrotor as the configuration with the best potential to meet the technology goals. The design presented was economically competitive, with the potential for substantial impact on the air transportation system. The keys to achieving a competitive aircraft were low drag airframe and low disk loading rotors; structural weight reduction, for both airframe and rotors; drive system weight reduction; improved engine efficiency; low maintenance design; and manufacturing cost comparable to fixed-wing aircraft. Risk reduction plans were developed to provide the strategic direction to support a heavy-lift rotorcraft development. The following high risk areas were identified for heavy lift rotorcraft: high torque, light weight drive system; high performance, structurally efficient rotor/wing system; low noise aircraft; and super-integrated vehicle management system.
Lifting a large object from an anisotropic porous bed
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.
Mid-L/D Lifting Body Entry Demise Analysis
Ling, Lisa
2017-01-01
The mid-lift-to-drag ratio (mid-L/D) lifting body is a fully autonomous spacecraft under design at NASA for enabling a rapid return of scientific payloads from the International Space Station (ISS). For contingency planning and risk assessment for the Earth-return trajectory, an entry demise analysis was performed to examine three potential failure scenarios: (1) nominal entry interface conditions with loss of control, (2) controlled entry at maximum flight path angle, and (3) controlled entry at minimum flight path angle. The objectives of the analysis were to predict the spacecraft breakup sequence and timeline, determine debris survival, and calculate the debris dispersion footprint. Sensitivity analysis was also performed to determine the effect of the initial pitch rate on the spacecraft stability and breakup during the entry. This report describes the mid-L/D lifting body and presents the results of the entry demise and sensitivity analyses.
The cycloconverter based on fuzzy controller for lift
WANG Gen-ping; YI Ling-zhi
2005-01-01
In order to ensure the lift can go up and down steadily and safely, a cycloconverter based on fuzzy control algorithm for lift was introduced, which can keep the output voltage to be symmetric sine wave. In this cycloconverter system,the main circuit structure was designed as circumfluence mode, with the strong DSP as the control unit, the fuzzy control policy of average weight accumulation decision was used to control the tuning of the triggering angle for thyristor in the main circuit, and then,the output voltage of the cycloconverter can be controlled. The experiment and simulation prove that the performance of the fuzzy cycloconverter is improved a lot and the output voltage is very similar to symmetric sine wave. This kind of cycloconverter can help the lift stop accurately, and the shock can be decreased.
High lift generation of low-aspect-ratio wings
Devoria, Adam; Mohseni, Kamran
2016-11-01
The time-averaged flow field in the center-span of low-aspect-ratio rectangular wings is experimentally measured. It is shown that lift stall is preceded by shedding of strong trailing-edge vorticity. The induced downwash of the tip vortices delays the growth of the attached boundary layer as well as leading-edge separation. Reattached flow occurs for sufficiently low aspect ratios and results in a smooth merging of the flow at the trailing edge thus assisting in satisfying a Kutta condition there. As a consequence, the strength of vorticity shed from the trailing edge is decreased and allows for continued lift generation at high angles of attack. When the reattachment point passes beyond the trailing edge, a strong shear layer is generated there and represents negative lift, leading to stall with a slight increase in angle of attack or aspect ratio.
2013-01-01
The Lift Conference returns to the Centre International de Conférence de Genève, with speakers ranging from a science fiction author to a cognitive neuroscience researcher. As one of the foremost talk events of Europe, Lift 2013 seeks to discover new trends and turn them into opportunities. The three-day conference is designed to engage and arouse intellectual curiosity by exploring the business and social implications of technological innovation. This year’s schedule also includes discussion of the political implications of technology and the impact of the online market on the future of economy. Alongside talks, workshops will be held on a wide range of topics, including the relationship between entrepreneur and investor, designs that influence social behaviour, and how ordinary people are changing the urban space. Lift 2013 also seeks to promote new business ventures and will award prizes to the start-up company that succeeds in convincing the audience an...
LeHew, J.; McKeon, B.J. [California Institute of Technology, Graduate Aerospace Laboratories, Pasadena, CA (United States); Guala, M. [California Institute of Technology, Graduate Aerospace Laboratories, Pasadena, CA (United States); University of Minnesota, Department of Civil Engineering, Minneapolis, MN (United States)
2011-10-15
Time-resolved particle image velocimetry (PIV) measurements performed in wall parallel planes at three wall normal locations, y{sup +} = 34, 108, and 278, in a zero pressure gradient turbulent boundary layer at Re{sub {tau}}=470 are used to illuminate the distribution of streamwise velocity fluctuations in a three-dimensional energy spectrum (2D in space and 1D in time) over streamwise, spanwise, and temporal wavelengths. Two high-speed cameras placed side by side in the streamwise direction give a 10{delta}x 5{delta} streamwise by spanwise field of view with a vector spacing of {delta}x{sup +}={delta}z{sup +}{approx} 37 and a time step of {delta}t{sup +}=0.5. Although 3D wavenumber-frequency spectra have been calculated in acoustics studies, to the authors' knowledge this is the first time they has been calculated and presented for a turbulent boundary layer. The calculation and normalization of this spectrum, its relation to 2D and 1D spectra, and the effects of the PIV algorithm on its shape are carefully analyzed and outlined. (orig.)
Lift outs: how to acquire a high-functioning team.
Groysberg, Boris; Abrahams, Robin
2006-12-01
More and more, expanding companies are hiring high-functioning groups of people who have been working together effectively within one company and can rapidly come up to speed in a new environment. These lifted-out teams don't need to get acquainted with one another or to establish shared values, mutual accountability, or group norms; their long-standing relationships and trust help them make an impact very quickly. Of course, the process is not without risks: A failed lift out can lead to loss of money, opportunity, credibility, and even native talent. Boris Groysberg and Robin Abrahams studied more than 40 high-profile moves and interviewed team leaders in multiple industries and countries to examine the risks and opportunities that lift outs present. They concluded that, regardless of industry, nationality, or size of the team, a successful lift out unfolds over four consecutive, interdependent stages that must be meticulously managed. In the courtship stage, the hiring company and the leader of the targeted team determine whether the proposed move is, in fact, a good idea, and then define their business goals and discuss strategies. At the same time, the team leader discusses the potential move with the other members of his or her group to assess their level of interest and prepare them for the change. The second stage involves the integration of the team leader with the new company's top leadership. This part of the process ensures the team's access to senior executives-the most important factor in a lift out's success. Operational integration is the focus of the third stage. Ideally, teams will start out working with the same or similar clients, vendors, and industry standards. The fourth stage entails full cultural integration. To succeed, the lifted-out team members must be willing to re-earn credibility by proving their value and winning their new colleagues' trust.
Comparison of Infant Car Seat grip orientations and lift strategies.
Clamann, Michael; Zhu, Biwen; Beaver, Leah; Taylor, Kinley; Kaber, David
2012-07-01
The rear-facing Infant Car Seat (ICS) is designed to meet federal requirements for transporting children less than 1 year old. Typical use includes transfer in and out of a vehicle, which is shown to be a difficult lift. Despite the frequency of this lift, manufacturers provide little guidance for users. Review of relevant literature suggested an ICS featuring an angled handle, promoting a neutral wrist posture, would increase grip stability and decrease lifting effort. Popular press suggested a foot-in-car stance for the ICS lift would do the same. An experiment was conducted in which wrist deviations from neutral posture were recorded along with lifting muscle activation levels (multiple flexor muscles and biceps brachii) and overall perceived exertion for straight versus a new bent handle design and conventional stance versus foot-in-car. Foot position was examined to test the recommendations in the popular press. Surprisingly, wrist deviation was not significantly affected by the new bent handle design (due to compensatory behavior with the straight handle) but was related to foot placement (p=0.04). Results revealed the bent handle to significantly reduce flexor activation compared with the straight handle (p=0.0003); however, the level of biceps activation increased. Biceps activation also significantly increased for foot-in-car stance (p=0.035) but not flexor activation. In general, the bent handle enabled the user to lift the ICS with a steadier grip and less effort. Copyright © 2011 Elsevier Ltd and The Ergonomics Society. All rights reserved.
Complications of Lower Body Lift Surgery in Postbariatric Patients
van Dijk, Martine M.; Klein, Steven; Hoogbergen, Maarten M.
2016-01-01
Background: There is an exponential rise of patients with massive weight loss because of bariatric surgery or lifestyle changes. The result is an increase of patients with folds of redundant skin that may cause physical and psychological problems. The lower body lift is a procedure to correct deformities in the abdomen, mons, flanks, lateral thighs, and buttocks. Complication rates are quite high and could negatively affect the positive outcomes. The purpose of this study is to assess complication rates and to identify predictors of complications to optimize outcomes for patients after lower body lift surgery. Methods: A retrospective analysis of 100 patients who underwent a lower body lift procedure was performed. The patients were reviewed for complications, demographic data, comorbidities, smoking, highest lifetime body mass index, body mass index before lower body lift surgery, percentage of excess weight loss, and amount of tissue excised. Results: The overall complication rate was 78%. Twenty-two percent of the patients had major complications and 56% had minor complications. There is a linear relationship between body mass index before lower body lift surgery and complications (P = 0.03). The percentage of excess weight loss (odds ratio [OR] 0.97; 95% confidence interval [CI] 0.92–1.00), highest lifetime body mass index (OR 1.08; 95% CI 1.01–1.15), body mass index before lower body lift surgery (OR 1.17; 95% CI 1.02–1.33), and smoking (OR 7.74; CI 0.98–61.16) are significantly associated with the development of complications. Conclusions: This study emphasizes the importance of a good weight status before surgery and cessation of smoking to minimize the risk of complications.
Lifting solutions to perturbing problems in C*-algebras
Loring, Terry A
1996-01-01
The nature of C^*-algebras is such that one cannot study perturbation without also studying the theory of lifting and the theory of extensions. Approximation questions involving representations of relations in matrices and C^*-algebras are the central focus of this volume. A variety of approximation techniques are unified by translating them into lifting problems: from classical questions about transitivity of algebras of operators on Hilbert spaces to recent results in linear algebra. One chapter is devoted to Lin's theorem on approximating almost normal matrices by normal matrices. The techn
Control of manual lifting hazards: II. Job redesign.
Ayoub, M A
1982-09-01
Job content and workplace components can be altered to assure that lifting stresses remain within the acceptable limits defined for the industrial population-at-large. The plan for redesign advocates (1) maintaining the weight handled within the recommended limits; (2) modifying the workplace to enhance postural stability and to avoid handling weights and excessive physical loading; and (3) increasing available job time by reducing frequency of lifts and/or introducing appropriate rest periods. Limits recommended by the National Institute for Occupational Safety and Health on acceptable loads are reviewed.
The lifting scheme of 4-channel orthogonal wavelet transforms
PENG Lizhong; CHU Xiaoyong
2006-01-01
The 4-channel smooth wavelets with linear phase and orthogonality are designed from the 2-channel orthogonal wavelets with high transfer vanishing moments. Reversely, for simple lifting scheme of such 4-channel orthogonal wavelet transforms, a new 2-channel orthogonal wavelet associated with this 4-channel wavelet is constructed. The new 2-channel wavelet has at least the same number of vanishing moments as the associated 4-channel one. Finally, by combining the two such 2-channel wavelet systems, the lifting scheme of 4-channel orthogonal wavelet transform, which has simple structure and is easy to apply, is presented.
Lifted Java: A Minimal Calculus for Translation Polymorphism
Ingesman, Matthias Diehn; Ernst, Erik
2011-01-01
To support roles and similar notions involving multiple views on an object, languages like Object Teams and CaesarJ include mechanisms known as lifting and lowering. These mechanisms connect pairs of objects of otherwise unrelated types, and enables programmers to consider such a pair almost...... of translation polymorphism has not been proved. This paper presents a simple model that extends Featherweight Java with the core operations of translation polymorphism, provides a Coq proof that its type system is sound, and shows that the ambiguity problem associated with the so-called smart lifting mechanism...
Lift of a rotating circular cylinder in unsteady flows
Carstensen, Stefan; Mandviwalla, Xerxes; Vita, Luca
2012-01-01
A cylinder rotating in steady current experiences a lift known as the Magnus effect. In the present study the effect of waves on the Magnus effect has been investigated. This situation is experienced with the novel floating offshore vertical axis wind turbine (VAWT) concept called the DEEPWIND...... concept, which incorporates a rotating spar buoy and thereby utilizes seawater as a roller-bearing. The a priori assumption and the results suggest that the lift in waves, to a first approximation, may be represented by a formulation similar to the well-known Morison formulation. The force coefficients...
New constructions of twistor lifts for harmonic maps
Svensson, Martin; C. Wood, John
2014-01-01
We show that given a harmonic map \\varphi from a Riemann surface into a classical simply connected compact inner symmetric space, there is a J_2-holomorphic twistor lift of \\varphi (or its negative) if and only if it is nilconformal. In the case of harmonic maps of finite uniton number, we give...... algebraic formulae in terms of holomorphic data which describes their extended solutions. In particular, this gives explicit formulae for the twistor lifts of all harmonic maps of finite uniton number from a surface to the above symmetric spaces....
Large Scale Composite Manufacturing for Heavy Lift Launch Vehicles
Stavana, Jacob; Cohen, Leslie J.; Houseal, Keth; Pelham, Larry; Lort, Richard; Zimmerman, Thomas; Sutter, James; Western, Mike; Harper, Robert; Stuart, Michael
2012-01-01
Risk reduction for the large scale composite manufacturing is an important goal to produce light weight components for heavy lift launch vehicles. NASA and an industry team successfully employed a building block approach using low-cost Automated Tape Layup (ATL) of autoclave and Out-of-Autoclave (OoA) prepregs. Several large, curved sandwich panels were fabricated at HITCO Carbon Composites. The aluminum honeycomb core sandwich panels are segments of a 1/16th arc from a 10 meter cylindrical barrel. Lessons learned highlight the manufacturing challenges required to produce light weight composite structures such as fairings for heavy lift launch vehicles.
Unitary cycles on Shimura curves and the Shimura lift II
Sankaran, Siddarth
2013-01-01
We consider two families of arithmetic divisors defined on integral models of Shimura curves. The first was studied by Kudla, Rapoport and Yang, who proved that if one assembles these divisors in a formal generating series, one obtains the q-expansion of a modular form of weight 3/2. The present work concerns the Shimura lift of this modular form: we identify the Shimura lift with a generating series comprised of unitary divisors, which arose in recent work of Kudla and Rapoport regarding cyc...
Block-based adaptive lifting schemes for multiband image compression
Masmoudi, Hela; Benazza-Benyahia, Amel; Pesquet, Jean-Christophe
2004-02-01
In this paper, we are interested in designing lifting schemes adapted to the statistics of the wavelet coefficients of multiband images for compression applications. More precisely, nonseparable vector lifting schemes are used in order to capture simultaneously the spatial and the spectral redundancies. The underlying operators are then computed in order to minimize the entropy of the resulting multiresolution representation. To this respect, we have developed a new iterative block-based classification algorithm. Simulation tests carried out on remotely sensed multispectral images indicate that a substantial gain in terms of bit-rate is achieved by the proposed adaptive coding method w.r.t the non-adaptive one.
Lift and Drag on Cylinder of Octagonal Cross-Section in a Turbulent Stream
Md. Jomir Hossain
2013-12-01
Full Text Available An experimental investigation of surface static pressure distributions on octagonal cylinder in uniform and turbulent flows was carried out. The study was performed on both the single cylinder and the group of two cylinders, two cylinders were used, one was at the upstream side, and the other was at the downstream side of the flow. They were placed centrally along the flow direction. The inter-spacing space between the two cylinders was varied at 1D, 2D, 3D, 4D, 5D, 6D, 7D and 8D, where D is the width of the cylinder across the flow direction. The pressure coefficients were calculated from the measured values of the surface static pressure distribution on the cylinder. Then the drag and lift coefficients were obtained from the pressure coefficients by the numerical integration method. It was observed that at various angles of attack, the values of the lift coefficients and drag coefficients were insignificant compared to those for a sharp-edged square cylinder. The strength of the vortex shedding was shown to be reduced as the intensity of the incident turbulence was increased. Measurements of drag at various angles of attack (0° to 40° showed that with increase in turbulence level the minimum drag occurred at smaller values of angle of attack.
Personnel launch system (PLS) lifting body and low lift-to-drag (L/D)
Erwin, Harry O.
1990-09-01
The Personnel Launch System (PLS) is a small transportation system designed to transport people, but no cargo, to and from low-earth orbit. The PLS is being considered as an addition to the manned launch capability of the United States for three main reasons: (1) to assure manned access to space, (2) to achieve a first-stage abort ability, and (3) to reduce operations costs. To those ends, two designs are being considered for the PLS that differ in their lift-to-drag (L/D) ratio. The Lyndon B. Johnson Space Center was assigned the task of examining low L/D capsules with no wings and a parachute landing capability. The Langley Research Center is studying a higher L/D PLS with wings and runway landings. Whichever design is selected, the PLS will act as a complement to the Space Shuttle fleet and will enhance the ability of our Nation to achieve reliable, safe, and cost-effective access to space flight, thus furthering the goals of the U.S. space program and increasing the safety of the human crews manning a future space station.
SAGD gas lift completions and optimization : a field case study at Surmont
Handfield, T.C.; Nations, T.; Noonan, S.G. [ConocoPhillips Co., Houston, TX (United States)
2008-10-15
Gas lift completions for steam assisted gravity drainage (SAGD) producers are unique. Because of the extreme temperatures of the downhole environment, conventional gas lift valves and mandrels with a packer completion cannot be used. Most gas lifts enter the production stream downhole through open-ended tubing or nozzles, which if not properly sized could result in operational issues, such as fluid/gas slugging and pressure instabilities which negatively effect the overall lift efficiency. ConocoPhillips performed a study in 2006 to design a gas lift system for the Surmont SAGD development that would allow better control of lift gas into the production string. The wells completed with gas lift were placed on production in 2007. This paper discussed the data collection effort and analysis completed to determine the efficiency of the two types of gas lift nozzles used in the completions. It also presented the methodology for optimization of SAGD gas lift systems and recommendations for future improvement. Background information on the Surmont oil sands project, located southeast of Fort McMurray in the Athabasca oil sands was included along with a historical perspective of the SAGD Surmont gas lift experience followed by a discussion of the Surmont initial gas lift design. Last, the paper discussed the Surmont gas lift start-up and optimization. It was concluded that installation of backcheck valves in coil tubing used for gas lift may mitigate plugging issues on initial start-up and following periods of shut-down. 5 refs., 10 figs.
Leading edge embedded fan airfoil concept -- A new powered high lift technology
Phan, Nhan Huu
A new powered-lift airfoil concept called Leading Edge Embedded Fan (LEEF) is proposed for Extremely Short Take-Off and Landing (ESTOL) and Vertical Take-Off and Landing (VTOL) applications. The LEEF airfoil concept is a powered-lift airfoil concept capable of generating thrust and very high lift-coefficient at extreme angles-of attack (AoA). It is designed to activate only at the take-off and landing phases, similar to conventional flaps or slats, allowing the aircraft to operate efficiently at cruise in its conventional configuration. The LEEF concept consists of placing a crossflow fan (CFF) along the leading-edge (LE) of the wing, and the housing is designed to alter the airfoil shape between take-off/landing and cruise configurations with ease. The unique rectangular cross section of the crossflow fan allows for its ease of integration into a conventional subsonic wing. This technology is developed for ESTOL aircraft applications and is most effectively applied to General Aviation (GA) aircraft. Another potential area of application for LEEF is tiltrotor aircraft. Unlike existing powered high-lift systems, the LEEF airfoil uses a local high-pressure air source from cross-flow fans, does not require ducting, and is able to be deployed using distributed electric power systems throughout the wing. In addition to distributed lift augmentation, the LEEF system can provide additional thrust during takeoff and landing operation to supplement the primary cruise propulsion system. Two-dimensional (2D) and three-dimensional (3D) Computational Fluid Dynamics (CFD) simulations of a conventional airfoil/wing using the NACA 63-3-418 section, commonly used in GA, and a LEEF airfoil/wing embedded into the same airfoil section were carried out to evaluate the advantages of and the costs associated with implementing the LEEF concept. Computational results show that significant lift and augmented thrust are available during LEEF operation while requiring only moderate fan power
The temporal endoscopic midface lift -centrofacial rejuvenation without facial scars
Thomas Haffner
2016-01-01
Aim: The author describes a new endoscopic midface lifting technique using solely temporal access and evaluates its advantages and perspectives.Methods: This is a single-surgeon case study. Through a short temporal incision, dissection is performed along a single plane connecting the superifcial surfaces of both the facial and temporal superifcial musculoaponeurotic system (SMAS) layers. Subsequent midface dissection divides the malar fat pad into the deeper and superifcial parts. A new concept of a combination high malar SMAS lift and internal skin lfap anchorage that provides long-term stability is described.Results: The temporal endoscopic midface (TEM) lift technique resulted in good objective results with high patient satisfaction. The temporal access allowed proper vertical vector correction of the sagging centro-facial structures. The resulting scar was inconspicuous and hidden in the hair bearing skin, and its length was measured between 5-6 cm. A conversion to the conventional long facial scar approach was completely avoided.Conclusion:The TEM lift is a new and effective procedure for facial rejuvenation, especially the midface and cheek. The results illustrate the importance of internal anchorage of both the midface SMAS and skin lfap. These are the keys to long-lasting and pleasing results. The procedure is best suited for younger men and women with little or no neck skin laxity.
Lambda-lifting and CPS conversion in an imperative language
Kerneis, Gabriel
2012-01-01
This paper is a companion technical report to the article "Continuation-Passing C: from threads to events through continuations". It contains the complete version of the proofs of correctness of lambda-lifting and CPS-conversion presented in the article.
Lifting the ban on brothels : Prostitution in 2000-2001
Daalder, A.L.
2004-01-01
On October 1, 2000 the general ban on brothels in the Netherlands was lifted. The core of the legislation is that those forms of prostitution in which adult prostitutes are voluntarily engaged are no longer illegal. This report is the English translation of the first comprehensive, evaluative report
Leading-Edge Vortices Elevate Lift of Autorotating Plant Seeds
Lentink, D.; Dickson, W.B.; Leeuwen, van J.L.; Dickinson, M.H.
2009-01-01
As they descend, the autorotating seeds of maples and some other trees generate unexpectedly high lift, but how they attain this elevated performance is unknown. To elucidate the mechanisms responsible, we measured the three-dimensional flow around dynamically scaled models of maple and hornbeam see
Lifted Java: A Minimal Calculus for Translation Polymorphism
Ingesman, Matthias Diehn; Ernst, Erik
2012-01-01
To support roles and similar notions involving multiple views on an object, languages like Object Teams and CaesarJ include mechanisms known as lifting and lowering. These mechanisms connect pairs of objects of otherwise unrelated types, and enable programmers to consider such a pair almost as a ...
Auxiliary lift propulsion system with oversized front fan
Castells, O.T.; Johnson, J.E.; Rundell, D.J.
1980-09-16
A propulsion system for use primarily in V/STOL aircraft is provided with a variable cycle, double bypass gas turbofan engine and a remote augmenter to produce auxiliary lift. The fan is oversized in air-pumping capability with respect to the cruise flight requirements of the remainder of the engine and a variable area, low pressure turbine is capable of supplying varying amounts of rotational energy to the oversized fan, thereby modulating its speed and pumping capability. During powered lift flight, the variable cycle engine is operated in the single bypass mode with the oversized fan at its maximum pumping capability. In this mode, substantially all of the bypass flow is routed as an auxiliary airstream to the remote augmenter where it is mixed with fuel, burned and exhausted through a vectorable nozzle to produce thrust for lifting. Additional lift is generated by the high energy products of combustion of the variable cycle engine which are further energized in an afterburner and exhausted through a thrust vectorable nozzle at the rear of the engine.
Prostatic urethral lift vs transurethral resection of the prostate
Gratzke, Christian; Barber, Neil; Speakman, Mark J
2017-01-01
OBJECTIVES: To compare prostatic urethral lift (PUL) with transurethral resection of the prostate (TURP) with regard to symptoms, recovery experience, sexual function, continence, safety, quality of life, sleep and overall patient perception. PATIENTS AND METHODS: A total of 80 patients with lower...
Bubble Size Effect on the Gas-lift Technique
Guet, S.C.L.
2004-01-01
The gas-lift technique uses gas injection in vertical oil wells to decrease the gravitational pressure drop. The decreased pressure in the production pipe results in an increase of the pressure drop from the reservoir to the oil well and enhances the oil production. In this thesis we investigated th
Control of a Buoyancy-Based Pilot Underwater Lifting Body
Finn Haugen
2010-04-01
Full Text Available This paper is about position control of a specific small-scale pilot underwater lifting body where the lifting force stems from buoyancy adjusted with an air pocket in the lifting body. A mathematical model is developed to get a basis for a simulator which is used for testing and for designing the control system, including tuning controller parameters. A number of different position controller solutions were tried both on a simulator and on the physical system. Successful control on both the simulator and the physical system was obtained with cascade control based on feedback from measured position and height of the air pocket in the lifting body. The primary and the secondary controllers of the cascade control system were tuned using Skogestad's model-based PID tuning rules. Feedforward from estimated load force was implemented in combination with the cascade control system, giving a substantial improvement of the position control system, both with varying position reference and varying disturbance (load mass.
Bubble Size Effect on the Gas-lift Technique
Guet, S.C.L.
2004-01-01
The gas-lift technique uses gas injection in vertical oil wells to decrease the gravitational pressure drop. The decreased pressure in the production pipe results in an increase of the pressure drop from the reservoir to the oil well and enhances the oil production. In this thesis we investigated th
Accelerating Wavelet Lifting on Graphics Hardware Using CUDA
Laan, Wladimir J. van der; Jalba, Andrei C.; Roerdink, Jos B.T.M.
The Discrete Wavelet Transform (DWT) has a wide range of applications from signal processing to video and image compression. We show that this transform, by means of the lifting scheme, can be performed in a memory and computation-efficient way on modern, programmable GPUs, which can be regarded as
On the lifting and approximation theorem for nonsmooth vector fields
Bramanti, Marco; Pedroni, Marco
2010-01-01
We prove a version of Rothschild-Stein's theorem of lifting and approximation and some related results in the context of nonsmooth Hormander's vector fields for which the highest order commutators are only Holder continuous. The theory explicitly covers the case of one vector field having weight two while the others have weight one.
Accelerating Wavelet Lifting on Graphics Hardware Using CUDA
Laan, Wladimir J. van der; Jalba, Andrei C.; Roerdink, Jos B.T.M.
2011-01-01
The Discrete Wavelet Transform (DWT) has a wide range of applications from signal processing to video and image compression. We show that this transform, by means of the lifting scheme, can be performed in a memory and computation-efficient way on modern, programmable GPUs, which can be regarded as
Usefulness of Kent retractor and lifting hook for Nuss procedure.
Takahashi, Tsubasa; Okazaki, Tadaharu; Yamataka, Atsuyuki; Uchida, Eiji
2015-11-01
Although the Nuss procedure for pectus excavatum has been widely employed, a variety of complications have been reported. The most dangerous complication is cardiac injury from the insertion of the introducer. To eliminate these complications, we present a sternum elevating technique using a Kent retractor and a lifting hook.
Tip vorticity reduction and optimization of lifting surfaces
Sparenberg, JA
2001-01-01
In linearized optimization theory, lifting surfaces, moving in an inviscid and incompressible fluid, shed tip vorticity of which the strength has infinite square-root singularities. Here we discuss that an optimization procedure can be coupled to constraints so that the strength of the shed vorticit
Assembly and lifting of Pearl-Chain arches
Halding, Philip Skov; Hertz, Kristian Dahl; Viebæk, N.E.
2015-01-01
Pearl-Chain arches were invented at the Technical University of Denmark in cooporation with the company Abeo A/S. The system uses specially designed, pre-fabricated concrete elements that are post-tensioned together into an arch shape, which is then lifted into place. The arches can be used both...
Aerodynamic Optimization for Distributed Electro Mechanical Actuators Project
National Aeronautics and Space Administration — Traditional hydraulic actuation and control surface layout both limit span wise control of lift distribution, and require large volume within wing cross-section,...
Thermal lift generation and drag reduction in rarefied aerodynamics
Pekardan, Cem; Alexeenko, Alina
2016-11-01
With the advent of the new technologies in low pressure environments such as Hyperloop and helicopters designed for Martian applications, understanding the aerodynamic behavior of airfoils in rarefied environments are becoming more crucial. In this paper, verification of rarefied ES-BGK solver and ideas such as prediction of the thermally induced lift and drag reduction in rarefied aerodynamics are investigated. Validation of the rarefied ES-BGK solver with Runge-Kutta discontinous Galerkin method with experiments in transonic regime with a Reynolds number of 73 showed that ES-BGK solver is the most suitable solver in near slip transonic regime. For the quantification of lift generation, A NACA 0012 airfoil is studied with a high temperature surface on the bottom for the lift creation for different Knudsen numbers. It was seen that for lower velocities, continuum solver under predicts the lift generation when the Knudsen number is 0.00129 due to local velocity gradients reaching slip regime although lift coefficient is higher with the Boltzmann ES-BGK solutions. In the second part, the feasibility of using thermal transpiration for drag reduction is studied. Initial study in drag reduction includes an application of a thermal gradient at the upper surface of a NACA 0012 airfoil near trailing edge at a 12-degree angle of attack and 5 Pa pressure. It was seen that drag is reduced by 4 percent and vortex shedding frequency is reduced due to asymmetry introduced in the flow due to temperature gradient causing reverse flow due to thermal transpiration phenomena.
Cleft-lift operation for pilonidal sinuses under tumescent local anesthesia
Bertelsen, Claus Anders
2011-01-01
The use of tumescent local anesthesia in the Bascom cleft-lift procedure has not been described before.......The use of tumescent local anesthesia in the Bascom cleft-lift procedure has not been described before....
Huijing, Marijn A.; van der Lei, Berend
In case of both medial and lateral brow ptosis in a balding candidate with a furrowed forehead, one may consider a midforehead lift, a technique that has not gained much popularity because of concerns regarding clearly visible scarring. We have applied this technique in a selected group of patients
Design, characterization and application of the Multiple Air-lift Loop bioreactor.
Bakker, W.A.M.
1995-01-01
A new bioreactor is introduced: the Multiple Air-lift Loop reactor (MAL). The MAL consists of a series of air-lift loop reactors within one vessel. With the MAL, a new type of geometry for air-lift reactors with an internal loop is introduced. This new geometry was characterized with respect to hydr
THE SHAPING OF SOME LIFTING AND TRANSPORTATION SYSTEMS, USING AUTODESK INVENTOR
URSE Cătălin
2011-11-01
Full Text Available The paper presents, through the use of Autodesk Inventor software package, several mechanisms from the structure of lifting and transportation machines, in this case lifting system with winch operated by screw,lifting system type with muffle with hook, respectively bridge crane type.
Design, characterization and application of the multiple air-lift loop bioreactor
Bakker, W.A.M.
1995-01-01
A new bioreactor is introduced: the Multiple Air-lift Loop reactor (MAL). The MAL consists of a series of air-lift loop reactors within one vessel. With the MAL, a new type of geometry for air-lift reactors with an internal loop is introduced. This new geometry was characterized with
Effect of lifting height and load mass on low back loading.
Hoozemans, Marco J M; Kingma, Idsart; de Vries, Wiebe H K; van Dieën, Jaap H
2008-07-01
The objective of this study was to quantify the effect of lifting height and mass lifted on the peak low back load in terms of net moments, compression forces and anterior-posterior shear forces. Ten participants had to lift a box using four handle heights. Low back loading was quantified using a dynamic 3-D linked segment model and a detailed electromyographic driven model of the trunk musculature. The effects of lifting height and lifting mass were quantified using a regression technique (GEE) for correlated data. Results indicate that an increase in lifting height and a decrease in lifting mass were related to a decrease in low back load. It is argued that trunk flexion is a major contributor to low back load. For ergonomic interventions it can be advised to prioritise optimisation of the vertical location of the load to be lifted rather than decreasing the mass of the load for handle heights between 32 cm and 155 cm, and for load masses between 7.5 and 15 kg. Lifting height and load mass are important determinants of low back load during manual materials handling. This paper provides the quantitative effect of lifting height and mass lifted, the results of which can be used by ergonomists at the workplace to evaluate interventions regarding lifting height and load mass.
Investigation of Maximum Blade Loading Capability of Lift-Offset Rotors
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.
17 CFR 3.64 - Procedure to lift or modify conditions or restrictions.
2010-04-01
... 17 Commodity and Securities Exchanges 1 2010-04-01 2010-04-01 false Procedure to lift or modify... COMMISSION REGISTRATION Denial, Suspension or Revocation of Registration § 3.64 Procedure to lift or modify... Enforcement to lift or modify conditions or restrictions on the registrant's registration. (1) The petition...
How to lift a box that is too large to fit between the knees.
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 CFR 61.163 - Aeronautical experience: Powered-lift category rating.
2010-01-01
... 14 Aeronautics and Space 2 2010-01-01 2010-01-01 false Aeronautical experience: Powered-lift... Transport Pilots § 61.163 Aeronautical experience: Powered-lift category rating. (a) A person who is applying for an airline transport pilot certificate with a powered-lift category rating must have at least...
76 FR 15798 - Special Conditions: Boeing 747-468, Installation of a Medical Lift
2011-03-22
... Medical Lift AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Final special conditions. SUMMARY... Aviation, will have a novel or unusual design feature associated with the installation of a medical lift... configuration. This modification includes the installation of a medical lift between the main deck and upper...
75 FR 17754 - Certificate of Alternative Compliance for the Lift Boat GARY CHIASSON ELEVATOR
2010-04-07
... SECURITY Coast Guard Certificate of Alternative Compliance for the Lift Boat GARY CHIASSON ELEVATOR AGENCY... Compliance was issued for the lift boat GARY CHIASSON ELEVATOR as required by 33 U.S.C. 1605(c) and 33 CFR 81... Regulations, Parts 81 and 89, has been issued for the lift boat GARY CHIASSON ELEVATOR. The Certificate...
Double-Sided Opportunities Using Chemical Lift-Off Lithography.
Andrews, Anne M; Liao, Wei-Ssu; Weiss, Paul S
2016-08-16
We discuss the origins, motivation, invention, development, applications, and future of chemical lift-off lithography, in which a specified pattern of a self-assembled monolayer is removed, i.e., lifted off, using a reactive, patterned stamp that is brought into contact with the monolayer. For Au substrates, this process produces a supported, patterned monolayer of Au on the stamp in addition to the negative pattern in the original molecular monolayer. Both the patterned molecular monolayer on the original substrate and the patterned supported metal monolayer on the stamp are useful as materials and for further applications in sensing and other areas. Chemical lift-off lithography effectively lowers the barriers to and costs of high-resolution, large-area nanopatterning. On the patterned monolayer side, features in the single-nanometer range can be produced across large (square millimeter or larger) areas. Patterns smaller than the original stamp feature sizes can be produced by controlling the degree of contact between the stamp and the lifted-off monolayer. We note that this process is different than conventional lift-off processes in lithography in that chemical lift-off lithography removes material, whereas conventional lift-off is a positive-tone patterning method. Chemical lift-off lithography is in some ways similar to microtransfer printing. Chemical lift-off lithography has critical advantages in the preparation of biocapture surfaces because the molecules left behind are exploited to space and to orient functional(ized) molecules. On the supported metal monolayer side, a new two-dimensional material has been produced. The useful important chemical properties of Au (vis-à-vis functionalization with thiols) are retained, but the electronic and optical properties of bulk Au or even Au nanoparticles are not. These metal monolayers do not quench excitation and may be useful in optical measurements, particularly in combination with selective binding due to
Design, Construction and Validation of Internally-Lit Air Lift Photobioreactor for Growing Algae
Ben J Stuart
2015-01-01
Full Text Available A novel 28 L photobioreactor for growing algae was developed from a previous bubble column system. The proposed design uses the air lift principle to enhance the culture circulation and induce light/dark cycles to the microorganisms. Optical fibers were used to distribute photons inside the culture media providing an opportunity to control both light cycle and intensity. The fibers were coupled to an artificial light source, however the development of this approach aims for the future use of natural light collected through parabolic solar collectors. This idea could also allow the use of non-clear materials for photobioreactor construction significantly reducing costs and increasing durability.Internal light levels were determined in dry conditions and were maintained above 80 µmol/(s•m2. The hydrodynamic equations of the air lift phenomena were explored and used to define the geometric characteristics of the unit. The reactor was inoculated with the algae strain Chlorella sp. and sparged with air. The reactor was operated under batch mode and daily monitored for biomass concentration. The specific growth rate constant of the novel device was determined to be 0.011 h-1, similar to other reactor designs reported in the literature, suggesting the proposed design can be effectively and economically used in carbon dioxide mitigation technologies and in the production of algal biomass for biofuel and other bioproducts.
Carbon nanotube assisted Lift off of GaN layers on sapphire
Long, Hao; Feng, Xiaohui; Wei, Yang; Yu, Tongjun; Fan, Shoushan; Ying, Leiying; Zhang, Baoping
2017-02-01
Laser lift off (LLO) was one of the most essential processes in fabrication of vertical GaN-based LEDs. However, traditional laser lift off of GaN on sapphire substrates needed high laser energy threshold, which deteriorated the GaN crystal. In this paper, it was found that inserting carbon nanotube between GaN and sapphire could effectively reduce the laser energy threshold in GaN LLO, from 1.5 J /cm2 of conventional GaN/sapphire to 1.3 J /cm2 of CNT inserted GaN/sapphire. The temperature distributions at the GaN/sapphire interfaces with and without CNTs were simulated by the finite elements calculation under laser irradiation. It was found that, due to the higher laser absorption coefficient of CNT, the CNT played as a powerful heating wire, sending out the thermal outside to elevate the GaN's temperature, and thus reduce the laser threshold for LLO. Raman and photoluminescence measurements indicated that residual stress of GaN membranes was as small as 0.3 GPa by the carbon nanotube assisted LLO. This work not only opens new application of CNTs, but also demonstrates the potential of high performance blue and green LEDs.
Automation of Workplace Lifting Hazard Assessment for Musculoskeletal Injury Prevention
2014-01-01
Objectives Existing methods for practically evaluating musculoskeletal exposures such as posture and repetition in workplace settings have limitations. We aimed to automate the estimation of parameters in the revised United States National Institute for Occupational Safety and Health (NIOSH) lifting equation, a standard manual observational tool used to evaluate back injury risk related to lifting in workplace settings, using depth camera (Microsoft Kinect) and skeleton algorithm technology. Methods A large dataset (approximately 22,000 frames, derived from six subjects) of simultaneous lifting and other motions recorded in a laboratory setting using the Kinect (Microsoft Corporation, Redmond, Washington, United States) and a standard optical motion capture system (Qualysis, Qualysis Motion Capture Systems, Qualysis AB, Sweden) was assembled. Error-correction regression models were developed to improve the accuracy of NIOSH lifting equation parameters estimated from the Kinect skeleton. Kinect-Qualysis errors were modelled using gradient boosted regression trees with a Huber loss function. Models were trained on data from all but one subject and tested on the excluded subject. Finally, models were tested on three lifting trials performed by subjects not involved in the generation of the model-building dataset. Results Error-correction appears to produce estimates for NIOSH lifting equation parameters that are more accurate than those derived from the Microsoft Kinect algorithm alone. Our error-correction models substantially decreased the variance of parameter errors. In general, the Kinect underestimated parameters, and modelling reduced this bias, particularly for more biased estimates. Use of the raw Kinect skeleton model tended to result in falsely high safe recommended weight limits of loads, whereas error-corrected models gave more conservative, protective estimates. Conclusions Our results suggest that it may be possible to produce reasonable estimates of
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.
Design and implementation of an expert system for remote fault diagnosis in ship lift
无
2007-01-01
In this paper an expert system for remote fault diagnosis in the ship lift was developed by analysis of the fault tree and combination with VPN. The fault tree was constructed based on the operation condition of the ship lift. The diagnosis model was constructed by hierarchical classification of the fault tree structure, and the inference mechanism was given. Logical structure of the fault diagnosis in the ship lift was proposed. The implementation of the expert system for remote fault diagnosis in the ship lift was discussed, and the expert system developed was realized on the VPN virtual network. The system was applied to the Gaobaozhou ship lift project, and it ran successfully.
Incremental wind tunnel testing of high lift systems
Victor, Pricop Mihai; Mircea, Boscoianu; Daniel-Eugeniu, Crunteanu
2016-06-01
Efficiency of trailing edge high lift systems is essential for long range future transport aircrafts evolving in the direction of laminar wings, because they have to compensate for the low performance of the leading edge devices. Modern high lift systems are subject of high performance requirements and constrained to simple actuation, combined with a reduced number of aerodynamic elements. Passive or active flow control is thus required for the performance enhancement. An experimental investigation of reduced kinematics flap combined with passive flow control took place in a low speed wind tunnel. The most important features of the experimental setup are the relatively large size, corresponding to a Reynolds number of about 2 Million, the sweep angle of 30 degrees corresponding to long range airliners with high sweep angle wings and the large number of flap settings and mechanical vortex generators. The model description, flap settings, methodology and results are presented.
Maximizing aesthetics in lateral-tension abdominoplasty and body lifts.
Lockwood, Ted E
2004-10-01
The high-lateral-tension abdominoplasty addresses the practical and theoretic faults of standard abdominoplasty design. Key features include limited direct undermining, increased lateral skin resection with highest-tension wound closure along lateral limbs, two-layer superficial fascial system repair, and significant truncal liposuction when needed. The high-lateral-tension design limits the unfavorable features of standard abdominoplasty and produces balanced natural aesthetic contours. The high-lateral-tension abdominoplasty is the foundation for treatment of more generalized relaxation problems in the circumferential trunk and thighs. For more significant thigh laxity and buttock ptosis, the lateral-tension abdominoplasty is combined with the transverse thigh/buttock lift to produce the lower body lift #2.
Eisenhart lifts and symmetries of time-dependent systems
Cariglia, M; Gibbons, G W; Horvathy, P A
2016-01-01
Certain dissipative systems, such as Caldirola and Kannai's damped simple harmonic oscillator, may be modelled by time-dependent Lagrangian and hence time dependent Hamiltonian systems with $n$ degrees of freedom. In this paper we treat these systems, their projective and conformal symmetries as well as their quantisation from the point of view of the Eisenhart lift to a Bargmann spacetime in $n+2$ dimensions, equipped with its covariantly constant null Killing vector field. Reparametrization of the time variable corresponds to conformal rescalings of the Bargmann metric. We show how the Arnold map lifts to Bargmann spacetime. We contrast the greater generality of the Caldirola-Kannai approach with that of Arnold and Bateman. At the level of quantum mechanics, we are able to show how the relevant Schr\\"odinger equation emerges naturally using the techniques of quantum field theory in curved spacetimes, since a covariantly constant null Killing vector field gives rise to well defined one particle Hilbert space...
A New Lift for Those Who Need It
2000-01-01
The eZ-uP device was designed by NASA engineer, Paul Neal, who worked with Kennedy Space Center. He took his idea to RJDesigns & Associates. With refinements, they developed a lightweight aluminium structure to assist the elderly in lifting themselves from seated positions. It can support people in excess of 500 pounds and is quickly assembled without tools. It is completely adjustable to fit under most sofas, chairs, and beds and will not slip on wood or tile floors. Also, it is relatively inexpensive compared to other products on the market. The apparatus is placed under the seat and adjusted so that the hand supports are in front of the person just under shoulder level. The seated person then takes hold and easily lifts himself from the seat. Product still commercially available as of March 2002.
Lifting Term Rewriting Derivations in Constructor Systems by Using Generators
Adrián Riesco
2015-01-01
Full Text Available Narrowing is a procedure that was first studied in the context of equational E-unification and that has been used in a wide range of applications. The classic completeness result due to Hullot states that any term rewriting derivation starting from an instance of an expression can be "lifted" to a narrowing derivation, whenever the substitution employed is normalized. In this paper we adapt the generator- based extra-variables-elimination transformation used in functional-logic programming to overcome that limitation, so we are able to lift term rewriting derivations starting from arbitrary instances of expressions. The proposed technique is limited to left-linear constructor systems and to derivations reaching a ground expression. We also present a Maude-based implementation of the technique, using natural rewriting for the on-demand evaluation strategy.
Sinus Lift and Transantral Approach to Root Fragment Removal
Andrea Enrico Borgonovo
2013-01-01
Full Text Available The aim of this case report is to present a case of root fragment removal during planned sinus lift procedure. After failed molar tooth extraction, we chose to retrieve the residual root apex with transantral approach not to damage excessively bone volume. Without changing primary implant rehabilitation purpose, the fragment removal procedure was performed prior to implant placement during necessary sinus lift surgery. Higher visibility of surgical field was achieved. The root fragment residual was removed without an additional surgery appointment avoiding postoperative discomfort. The goal is to underline the importance of being able to change planning during intrasurgical complications. It is most appropriate to operate with safe and simple procedures to reduce surgical discomfort for the patient.
Procedure for utilizing the lift and thrust forces of ornithopters
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.
THE CLINICAL APPLICATION OF ENDOSCOPE IN FRONTO-TEMPORAL LIFTING
无
2001-01-01
Objective To introduce and discuss the usage and effects of endoscopic technique in the frontal-temporal lifting. Methods 15 endoscopic forehead-lift cases were treated from 1996 to 1999. The frontal and deep temporal fascia dissection were performed to produce a visualization pocket. The resection of the procerus and corrugator muscles were performed under direct vision to correct the imbalance of the muscles. The periosteum was also released along the supraobital rim. Results The results were satisfactory. The pro- cedure was usually performed to rejuvenate the ptosis of the eyebrow, to eliminate the temporal and glabellar wrinkles as well. Conclusion Small incision, less bleeding, mild numbness and less alopecia are the advan- tages of endoscopic operation.
Asymmetric Gepner Models III. B-L Lifting
Gato-Rivera, B
2010-01-01
In the same spirit as heterotic weight lifting, B-L lifting is a way of replacing the superfluous and ubiquitous U(1)_{B-L} with something else with the same modular properties, but different conformal weights and ground state dimensions. This method works in principle for all variants of (2,2) constructions, such as orbifolds, Calabi-Yau manifolds, free bosons and fermions and Gepner models, since it only modifies the universal SO(10) x E_8 part of the CFT. However, it can only yield chiral spectra if the ``internal" sector of the theory provides a simple current of order 5. Here we apply this new method to Gepner models. Including exceptional invariants, 86 of them have the required order 5 simple current, and 69 of these yield chiral spectra. Three family spectra occur abundantly.
On the Use of Surface Porosity to Reduce Unsteady Lift
Tinetti, Ana F.; Kelly, Jeffrey J.; Bauer, Steven X. S.; Thomas, Russell H.
2001-01-01
An innovative application of existing technology is proposed for attenuating the effects of transient phenomena, such as rotor-stator and rotor-strut interactions, linked to noise and fatigue failure in turbomachinery environments. A computational study was designed to assess the potential of passive porosity technology as a mechanism for alleviating interaction effects by reducing the unsteady lift developed on a stator airfoil subject to wake impingement. The study involved a typical high bypass fan Stator airfoil (solid baseline and several porous configurations), immersed in a free field and exposed to the effects of a transversely moving wake. It was found that, for the airfoil under consideration, the magnitude of the unsteady lift could be reduced more than 18% without incurring significant performance losses.
Asymmetric Gepner models III. B-L lifting
Gato-Rivera, B. [NIKHEF Theory Group, Kruislaan 409, 1098 SJ Amsterdam (Netherlands); Instituto de Fisica Fundamental, CSIC, Serrano 123, Madrid 28006 (Spain); Schellekens, A.N., E-mail: t58@nikhef.n [NIKHEF Theory Group, Kruislaan 409, 1098 SJ Amsterdam (Netherlands); Instituto de Fisica Fundamental, CSIC, Serrano 123, Madrid 28006 (Spain); IMAPP, Radboud Universiteit, Nijmegen (Netherlands)
2011-06-21
In the same spirit as heterotic weight lifting, B-L lifting is a way of replacing the superfluous and ubiquitous U(1){sub B-L} with something else with the same modular properties, but different conformal weights and ground state dimensions. This method works in principle for all variants of (2,2) constructions, such as orbifolds, Calabi-Yau manifolds, free bosons and fermions and Gepner models, since it only modifies the universal SO(10)xE{sub 8} part of the CFT. However, it can only yield chiral spectra if the 'internal' sector of the theory provides a simple current of order 5. Here we apply this new method to Gepner models. Including exceptional invariants, 86 of them have the required order 5 simple current, and 69 of these yield chiral spectra. Three family spectra occur abundantly.
Current developments lighter than air systems. [heavy lift airships
Mayer, N. J.
1981-01-01
Lighter than air aircraft (LTA) developments and research in the United States and other countries are reviewed. The emphasis in the U.S. is on VTOL airships capable of heavy lift, and on long endurance types for coastal maritime patrol. Design concepts include hybrids which combine heavier than air and LTA components and characteristics. Research programs are concentrated on aerodynamics, flight dynamics, and control of hybrid types.
Predictive Maintenance of Hydraulic Lifts through Lubricating Oil Analysis
Stamatios S. Kalligeros
2013-01-01
This article examines the possibility of measuring lift maintenance through analysis of used hydraulic oil. Hydraulic oils have proved to be a reliable indicator for the maintenance performed on elevators. It has also been proved that the end users or the maintenance personnel do not always conform to the instructions of the elevators’ hydraulic machine manufacturer. Furthermore, by examining the proportion of the metals, an estimation of the corrosion and the wear resistance of the joined mo...
Transcutaneous Serdev Suture For Buttock’s Lift
Nikolay Serdev
2012-01-01
This article presents the author's technique and experience in the treatment of the flaccid "unhappy buttock" form with his surgical procedure of buttock lift by suture, without incision scars. The author first presented this new operation technique on a national level at the 2nd Annual Meeting of the National Bulgarian Society for Aesthetic Surgery and Aesthetic Medicine in Sofia on March 18, 1994 [1] and internationally at many scientific meetings over the world [2, 3, 4…]. The result is a ...
Experimental Study of Air-Lift Pumps Characteristics
Naji F. Al-Saqer
2014-03-01
Full Text Available The mean aim of this work is to study the Air-lift pumps characteristics according to design parameters such as the percentage of the distance between throat section and nozzle and the driving air pressure, suction head and also study the effect of each parameter on the air lift pump characteristics in order to have a better performance of such pump under various conditions. A certain geometry for air-lift pump designed and manufactured. The experiments show that there must be careful in increasing the suction head, and a balance must be considered between the suction head and the driving air volumetric flow rate. While the effect of increasing air pressure will stop at certain maximum of the ratio of the volumetric flow rate of water and air that is any increase in air pressure will meet no change ratio of the volumetric flow rate of water and air, While Increasing S/Dth will leads to decrease in the percentage of ratio of the volumetric flow rate of water and air because the optimum S/Dth so that at this value we will have the best performance and any other values for S/Dth the percentage of ratio of the volumetric flow rate of water and air will decreases , but this effect is not so clear and it could be neglected. The pump performance is not so sensitive with the change of S/Dth after a certain value, this information will help in the use of the air-lift pump in several applications using the predetermined operating conditions.
Video Coding with Motion-Compensated Lifted Wavelet Transforms
Flierl, M.; Girod, B.
2004-01-01
This article explores the efficiency of motion-compensated three-dimensional transform coding, a compression scheme that employs a motion-compensated transform for a group of pictures. We investigate this coding scheme experimentally and theoretically. The practical coding scheme employs in temporal direction a wavelet decomposition with motion-compensated lifting steps. Further, we compare the experimental results to that of a predictive video codec with single-hypothesis motion compensation...
Spatial model of lifting scheme in wavelet transforms and image compression
Wu, Yu; Li, Gang; Wang, Guoyin
2002-03-01
Wavelet transforms via lifting scheme are called the second-generation wavelet transforms. However, in some lifting schemes the coefficients are transformed using mathematical method from the first-generation wavelets, so the filters with better performance using in lifting are limited. The spatial structures of lifting scheme are also simple. For example, the classical lifting scheme, predicting-updating, is two-stage, and most researchers simply adopt this structure. In addition, in most design results the lifting filters are not only hard to get and also fixed. In our former work, we had presented a new three-stage lifting scheme, predicting-updating-adapting, and the results of filter design are no more fixed. In this paper, we continue to research the spatial model of lifting scheme. A group of general multi-stage lifting schemes are achieved and designed. All lifting filters are designed in spatial domain and proper mathematical methods are selected. Our designed coefficients are flexible and can be adjusted according to different data. We give the mathematical design details in this paper. Finally, all designed model of lifting are used in image compression and satisfactory results are achieved.
Assessing manual lifting tasks based on segment angle interpolations.
Chang, Chien-Chi; Xu, Xu; Faber, Gert S; Kingma, Idsart; Dennerlein, Jack
2012-01-01
This study investigates the effects of the number of interpolation points on the prediction accuracy of segment angle trajectory during lifting. Ten participants performed various lifting tasks while a motion tracking system recorded their movements. Two-point through ten-point equal time-spaced segment angles extracted from major segment trajectory data captured by the motion tracking system were used to re-generate the whole body lifting motion by using polynomial and cubic spline interpolation methods. The root mean square error (RMSE) between the reference (motion tracking system) and the estimated (interpolation method) segment angle trajectories were calculated to quantify the prediction accuracy. The results showed that the cubic spline interpolation will yield a smaller RMSE value than one based on the polynomial interpolation. While increasing the number of interpolation points can reduce the RMSE of the estimated segment angle trajectories, there was a diminishing advantage in continuing to add interpolation points. A sensitivity analysis suggests that if the estimation of the segment angles at each interpolation point deviates considerably from the real value, and cannot be controlled at a low level (interpolation points will not improve the estimation accuracy.
Separation efficiency of a vacuum gas lift for microalgae harvesting.
Barrut, Bertrand; Blancheton, Jean-Paul; Muller-Feuga, Arnaud; René, François; Narváez, César; Champagne, Jean-Yves; Grasmick, Alain
2013-01-01
Low-energy and low-cost separation of microalgae from water is important to the economics of microalgae harvesting and processing. Flotation under vacuum using a vacuum gas lift for microalgae harvesting was investigated for different airflow rates, bubble sizes, salinities and harvest volumes. Harvesting efficiency (HE) and concentration factor (CF) of the vacuum gas lift increased by around 50% when the airflow rate was reduced from 20 to 10 L min(-1). Reduced bubble size multiplied HE and CF 10 times when specific microbubble diffusers were used or when the salinity of the water was increased from 0‰ to 40‰. The reduction in harvest volume from 100 to 1L increased the CF from 10 to 130. An optimized vacuum gas lift could allow partial microalgae harvesting using less than 0.2 kWh kg(-1) DW, thus reducing energy costs 10-100 times compared to complete harvesting processes, albeit at the expense of a less concentrated biomass harvest.
Lichen planopilaris following hair transplantation and face-lift surgery.
Chiang, Y Z; Tosti, A; Chaudhry, I H; Lyne, L; Farjo, B; Farjo, N; Cadore de Farias, D; Griffiths, C E M; Paus, R; Harries, M J
2012-03-01
Cosmetic surgical procedures, including hair transplantation and face-lift surgery, are becoming increasingly popular. However, there is very little information regarding the associated development of dermatological conditions following these procedures. Lichen planopilaris (LPP) is an uncommon inflammatory hair disorder of unknown aetiology that results in permanent alopecia and replacement of hair follicles with scar-like fibrous tissue. Frontal fibrosing alopecia (FFA), a variant of LPP, involves the frontal hairline and shares similar histological findings with those of LPP. We report 10 patients who developed LPP/FFA following cosmetic scalp surgery. Seven patients developed LPP following hair transplantation, and three patients developed FFA following face-lift surgery. In all cases there was no previous history of LPP or FFA. There is currently a lack of evidence to link the procedures of hair transplantation and cosmetic face-lift surgery to LPP and FFA, respectively. This is the first case series to describe this connection and to postulate the possible pathological processes underlying the clinical observation. Explanations include Koebner phenomenon induced by surgical trauma, an autoimmune process targeting an (as yet, unknown) hair follicle antigen liberated during surgery or perhaps a postsurgery proinflammatory milieu inducing hair follicle immune privilege collapse and follicular damage in susceptible individuals.
Laser polymerization-based novel lift-off technique
Bhuian, B. [Tyndall National Institute, Lee Maltings, Prospect Row, Cork (Ireland); Department of Microelectronic Engineering, University College Cork, Cork (Ireland); Winfield, R.J. [Tyndall National Institute, Lee Maltings, Prospect Row, Cork (Ireland)], E-mail: richard.winfield@tyndall.ie; Crean, G.M. [Tyndall National Institute, Lee Maltings, Prospect Row, Cork (Ireland); Department of Microelectronic Engineering, University College Cork, Cork (Ireland)
2009-03-01
The fabrication of microstructures by two-photon polymerization has been widely reported as a means of directly writing three-dimensional nanoscale structures. In the majority of cases a single point serial writing technique is used to form a polymer model. Single layer writing can also be used to fabricate two-dimensional patterns and we report an extension of this capability by using two-photon polymerization to form a template that can be used as a sacrificial layer for a novel lift-off process. A Ti:sapphire laser, with wavelength 795 nm, 80 MHz repetition rate, 100 fs pulse duration and an average power of 700 mW, was used to write 2D grid patterns with pitches of 0.8 and 1.0 {mu}m in a urethane acrylate resin that was spun on to a lift-off base layer. This was overcoated with gold and the grid lifted away to leave an array of gold islands. The optical transmission properties of the gold arrays were measured and found to be in agreement with a rigorous coupled-wave analysis simulation.
Biomechanical comparison of unilateral and bilateral power snatch lifts.
Lauder, Mike A; Lake, Jason P
2008-05-01
Biomechanical characteristics of the one-handed dumbbell power snatch (DBPS) were examined to determine whether significant differences existed between unilateral and bilateral weightlifting movements. Kinetic and kinematic movement data were recorded from 10 male weightlifters (mean +/- SD: age: 30.2 +/- 10.2 years; height: 174.2 +/- 4.4 cm; body mass: 81.5 +/- 14.6 kg) during one-handed dumbbell (DB) and traditional barbell (BBPS) power snatch performance with loads of approximately 80% of respective lift one repetition maximums (1RM) with the use of 2 synchronized Kistler force plates and high-speed 3-dimensional video. Results highlighted asymmetry in the ground reaction force and kinematic profile of the DBPS, which deviated from the observed patterns of the bilateral movement. This study found that the nonlifting side (the side corresponding with the hand that did not hold the DB) tended to generate a greater pull phase peak vertical ground reaction forces significantly faster (p = 0.001) than the lifting side (the side corresponding with the hand that held the DB) during the DBPS. In addition, the DBPS nonlifting side catch phase loading rate was approximately double that of the lifting side loading rate (p snatch movement both during the concentric muscular contraction of load vertical displacement, and the loading implications of unilateral landing. This asymmetry supports the contention that unilateral variations of weightlifting movements may provide a different training stimulus to athletes.
Adaptive lifting scheme of wavelet transforms for image compression
Wu, Yu; Wang, Guoyin; Nie, Neng
2001-03-01
Aiming at the demand of adaptive wavelet transforms via lifting, a three-stage lifting scheme (predict-update-adapt) is proposed according to common two-stage lifting scheme (predict-update) in this paper. The second stage is updating stage. The third is adaptive predicting stage. Our scheme is an update-then-predict scheme that can detect jumps in image from the updated data and it needs not any more additional information. The first stage is the key in our scheme. It is the interim of updating. Its coefficient can be adjusted to adapt to data to achieve a better result. In the adaptive predicting stage, we use symmetric prediction filters in the smooth area of image, while asymmetric prediction filters at the edge of jumps to reduce predicting errors. We design these filters using spatial method directly. The inherent relationships between the coefficients of the first stage and the other stages are found and presented by equations. Thus, the design result is a class of filters with coefficient that are no longer invariant. Simulation result of image coding with our scheme is good.
Lift and drag performance of odontocete cetacean flippers.
Weber, Paul W; Howle, Laurens E; Murray, Mark M; Fish, Frank E
2009-07-01
Cetaceans (whales, dolphins and porpoises) have evolved flippers that aid in effective locomotion through their aquatic environments. Differing evolutionary pressures upon cetaceans, including hunting and feeding requirements, and other factors such as animal mass and size have resulted in flippers that are unique among each species. Cetacean flippers may be viewed as being analogous to modern engineered hydrofoils, which have hydrodynamic properties such as lift coefficient, drag coefficient and associated efficiency. Field observations and the collection of biological samples have resulted in flipper geometry being known for most cetacean species. However, the hydrodynamic properties of cetacean flippers have not been rigorously examined and thus their performance properties are unknown. By conducting water tunnel testing using scale models of cetacean flippers derived via computed tomography (CT) scans, as well as computational fluid dynamic (CFD) simulations, we present a baseline work to describe the hydrodynamic properties of several cetacean flippers. We found that flippers of similar planform shape had similar hydrodynamic performance properties. Furthermore, one group of flippers of planform shape similar to modern swept wings was found to have lift coefficients that increased with angle of attack nonlinearly, which was caused by the onset of vortex-dominated lift. Drag coefficient versus angle of attack curves were found to be less dependent on planform shape. Our work represents a step towards the understanding of the association between performance, ecology, morphology and fluid mechanics based on the three-dimensional geometry of cetacean flippers.
Robust GPS Satellite Signal Acquisition Using Lifting Wavelet Transform
M. Djebbouri
2006-04-01
Full Text Available A novel GPS satellite signal acquisition scheme that utilizes lifting wavelet to improve acquisition performance is proposed. Acquisition in GPS system is used to calculate the code phase (or shift and find the pseudo-range, which is used to calculate the position. The performance of a GPS receiver is assessed by its ability to precisely measure the pseudo-range, which depends on noise linked to the signals in the receiverÃ¢Â€Â™s tracking loops. The level of GPS receiving equipment system noise determines in part how precisely pseudo-range can be measured. Our objective, in this paper, is to achieve robust real-time positioning with maximum of accuracy in the presence of noise. Robust positioning describes a positioning system's ability to maintain position data continuity and accuracy through most or all anticipated operational conditions. In order to carry out a robust less complex GPS signals acquisition system and to facilitate its implementation, a substitute algorithm for calculating the convolution by using lifting wavelet decomposition is proposed. Simulation is used for verifying the performance which shows that the proposed scheme based lifting wavelet transform outperforms both FFT search and signal decimation schemes in the presence of a hostile environment.
Investigation into Interface Lifting Within FSW Lap Welds
K. S. Miller; C. R. Tolle; D. E. Clark; C. I. Nichol; T. R. McJunkin; H. B. Smartt
2008-06-01
Friction stir welding (FSW) is rapidly penetrating the welding market in many materials and applications, particularly in aluminum alloys for transportation applications. As this expansion outside the research laboratory continues, fitness for service issues will arise, and process control and NDE methods will become important determinants of continued growth. The present paper describes research into FSW weld nugget flaw detection within aluminum alloy lap welds. We present results for two types of FSW tool designs: a smooth pin tool and a threaded pin tool. We show that under certain process parameters (as monitored during welding with a rotating dynamometer that measures x, y, z, and torque forces) and tooling designs, FSW lap welds allow significant nonbonded interface lifting of the lap joint, while forming a metallurgical bond only within the pin region of the weld nugget. These lifted joints are often held very tightly together even though unbonded, and might be expected to pass cursory NDE while representing a substantial compromise in joint mechanical properties. The phenomenon is investigated here via radiographic and ultrasonic NDE techniques, with a copper foil marking insert (as described elsewhere) and by the tensile testing of joints. As one would expect, these results show that tool design and process parameters significantly affect plactic flow and this lifted interface. NDE and mechanical strength ramifications of this defect are discussed.
Palatal lifting prosthesis and velopharyngeal insufficiency: Preliminary report
Ali Ibrahim Aboloyoun
2013-05-01
Full Text Available Objectives. Our study aimed to highlight the effectiveness of palatal lift prosthesis in patients with velopharyngeal insufficiency with previous operated cleft palate. Methods. This study was done undertaken January 2008 to December of 2009 in the Phoniatic unit of Alnoor Specialist Hospital, Makkah, Saudi Arabia. Ten patients of ≥ 8 years to ≤ 10 years of age, who had previously undergone surgery for cleft palate, with or without cleft lip, with no other systemic illness and normal intelligent quotient level, were selected and managed by palatal lift prosthesis. All the study subjects were subjected to auditory perceptual speech evaluation for assessment of the degree of hypernasality, compensatory articulator mechanisms, glottal and pharyngeal articulation, audible nasal emission, facial grimace and overall intelligibility of speech. Data were analyzed using SPSS version 16. Results. The study included 10 subjects whose mean ± standard deviation of age was (8.9±0.9. On auditory speech perceptual evaluation after prosthesis application, significant improvement was found in glottal articulation 6 (85.7%, p=0.04, facial grimace 6 (85.7% p=0.04, hyper nasality 10 (10% p=0.008, and speech intelligibility 9 (90% p=0.008. Conclusion. Young patients with repaired palatal cleft have significant improvement after application of palatal lift prosthesis.
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.
Airfoil design: Finding the balance between design lift and structural stiffness
Bak, Christian; Gaudern, Nicholas; Zahle, Frederik
2014-01-01
When upscaling wind turbine blades there is an increasing need for high levels of structural efficiency. In this paper the relationships between the aerodynamic characteristics; design lift and lift-drag ratio; and the structural characteristics were investigated. Using a unified optimization setup......, the design lift coefficient increases if the box length reduces and at the same time the relative thickness increases. Even though the conclusions are specific to the airfoil design approach used, the study indicated that an increased design lift required slightly higher relative thickness compared...... to airfoils with lower design lift to maintain the flapwise stiffness. Also, the study indicated that the lift-drag ratio as a function of flapwise stiffness was relatively independent of the airfoil design with a tendency that the lift-drag ratio decreased for large box lengths. The above conclusions were...
Effects of height and load weight on shoulder muscle work during overhead lifting task.
Blache, Y; Desmoulins, L; Allard, P; Plamondon, A; Begon, M
2015-01-01
Few musculoskeletal models are available to assess shoulder deeper muscle demand during overhead lifting tasks. Our objective was to implement a musculoskeletal model to assess the effect of lifting height and load on shoulder muscle work. A musculoskeletal model scaled from 15 male subjects was used to calculate shoulder muscle work during six lifting tasks. Boxes containing three different loads (6, 12 and 18 kg) were lifted by the subjects from the waist to shoulder or eye level. After optimisation of the maximal isometric force of the model's muscles, the bio-fidelity of the model was improved by 19%. The latter was able to reproduce the subjects' lifting movements. Mechanical work of the rotator cuff muscles, upper trapezius and anterior deltoid was increased with lifting load and height augmentation. In conclusion, the use of a musculoskeletal model validated by electromyography enabled to evaluate the muscle demand of deep muscles during lifting tasks.
Dittmar, J. H.
1984-01-01
Previous comparisons between calculated and measured supersonic helical tip speed propeller noise show them to have different trends of peak blade passing tone versus helical tip Mach number. It was postulated that improvements in this comparison could be made first by including the drag force terms in the prediction and then by reducing the blade lift terms at the tip to allow the drag forces to dominate the noise prediction. Propeller hub to tip lift distributions were varied, but they did not yield sufficient change in the predicted lift noise to improve the comparison. This result indicates that some basic changes in the theory may be needed. In addition, the noise predicted by the drag forces did not exhibit the same curve shape as the measured data. So even if the drag force terms were to dominate, the trends with helical tip Mach number for theory and experiment would still not be the same. The effect of the blade shock wave pressure rise was approxmated by increasing the drag coefficient at the blade tip. Predictions using this shock wdave approximation did have a curve shape similar to the measured data. This result indicates that the shock pressure rise probably controls the noise at supersonic tip speed and that the linear prediction method can give the proper noise trend with Mach number.
High-Temperature-High-Volume Lifting for Enhanced Geothermal Systems
Turnquist, Norman [GE Global Research, Munchen (Germany); Qi, Xuele [GE Global Research, Munchen (Germany); Raminosoa, Tsarafidy [GE Global Research, Munchen (Germany); Salas, Ken [GE Global Research, Munchen (Germany); Samudrala, Omprakash [GE Global Research, Munchen (Germany); Shah, Manoj [GE Global Research, Munchen (Germany); Van Dam, Jeremy [GE Global Research, Munchen (Germany); Yin, Weijun [GE Global Research, Munchen (Germany); Zia, Jalal [GE Global Research, Munchen (Germany)
2013-12-20
This report summarizes the progress made during the April 01, 2010 – December 30, 2013 period under Cooperative Agreement DE-EE0002752 for the U.S. Department of Energy entitled “High-Temperature-High-Volume Lifting for Enhanced Geothermal Systems.” The overall objective of this program is to advance the technology for well fluids lifting systems to meet the foreseeable pressure, temperature, and longevity needs of the Enhanced Geothermal Systems (EGS) industry for the coming ten years. In this program, lifting system requirements for EGS wells were established via consultation with industry experts and site visits. A number of artificial lift technologies were evaluated with regard to their applicability to EGS applications; it was determined that a system based on electric submersible pump (ESP) technology was best suited to EGS. Technical barriers were identified and a component-level technology development program was undertaken to address each barrier, with the most challenging being the development of a power-dense, small diameter motor that can operate reliably in a 300°C environment for up to three years. Some of the targeted individual component technologies include permanent magnet motor construction, high-temperature insulation, dielectrics, bearings, seals, thrust washers, and pump impellers/diffusers. Advances were also made in thermal management of electric motors. In addition to the overall system design for a full-scale EGS application, a subscale prototype was designed and fabricated. Like the full-scale design, the subscale prototype features a novel “flow-through-the-bore” permanent magnet electric motor that combines the use of high temperature materials with an internal cooling scheme that limits peak internal temperatures to <330°C. While the full-scale high-volume multi-stage pump is designed to lift up to 80 kg/s of process water, the subscale prototype is based on a production design that can pump 20 kg/s and has been modified
LIFT AND POWER REQUIREMENTS OF HOVERING INSECT FLIGHT
孙茂; 杜刚
2003-01-01
Lift and power requirements for hovering flight of eight species of insects are studied by solving the Navier-Stokes equation numerically. The solution provides velocity and pressure fields,from which unsteady aerodynamic forces and moments are obtained. The inertial torque of wing mass are computed analytically. The wing length of the insects ranges from 2 mm (fruit fly) to 52 mm (hawkmoth); Reynolds numbers Re (based on mean flapping speed and mean chord length) ranges from 75 to 3 850. The primary findings are shown in the following: (1) Either small (R = 2 mm, Re = 75),medium (R ≈ 10 mm, Re ≈ 500) or large (R ≈ 50 mm, Re ≈ 4 000) insects mainly employ the same high-lift mechanism, delayed stall, to produce lift in hovering flight. The midstroke angle of attack needed to produce a mean lift equal to the insect weight is approximately in the range of 25° to 45°,which is approximately in agreement with observation. (2) For the small insect (fruit fly) and for the medium and large insects with relatively small wingbeat frequency (cranefly, ladybird and hawkmoth),the specific power ranges from 18 to 39W.kg-1 , the major part of the power is due to aerodynamic force, and the elastic storage of negative work does not change the specific power greatly. However for medium and large insects with relatively large wingbeat frequency (hoverfly, dronefly, honey bee and bumble bee), the specific power ranges from 39 to 61W.kg-1 , the major part of the power is due to wing inertia, and the elastic storage of negative work can decrease the specific power by approximately 33%. (3) For the case of power being mainly contributed by aerodynamic force (fruit fly, cranefly,ladybird and hawkmoth), the specific power is proportional to the product of the wingbeat frequency,the stroke amplitude, the wing length and the drag-to-lift ratio. For the case of power being mainly contributed by wing inertia (hoverfly, dronefly, honey bee and bumble bee), the specific power (without
Does the personal lift-assist device affect the local dynamic stability of the spine during lifting?
Graham, Ryan B; Sadler, Erin M; Stevenson, Joan M
2011-02-03
The personal lift-assist device (PLAD) is an on-body ergonomic aid that reduces low back physical demands through the restorative moment of an external spring element, which possesses a mechanical advantage over the erector spinae. Although the PLAD has proven effective at reducing low back muscular demand, spinal moments, and localized muscular fatigue during laboratory and industrial tasks, the effects of the device on the neuromuscular control of spinal stability during lifting have yet to be assessed. Thirty healthy subjects (15M, 15F) performed repetitive lifting for three minutes, at a rate of 10 lifts per minute, with and without the PLAD. Maximum finite-time Lyapunov exponents, representing short-term (λ(max-s)) and long-term (λ(max-l)) divergence were calculated from the measured trunk kinematics to estimate the local dynamic stability of the lumbar spine. Using a mixed-design repeated-measures ANOVA, it was determined that wearing the PLAD did not significantly change λ(max-s) (μ(NP)=0.335, μ(P)=0.321, p=0.225), but did significantly reduce λ(max-l) (μ(NP)=0.0024, μ(P)=-0.0011, p=0.014, η(2)=0.197). There were no between-subject effects of sex, or significant interactions (p>0.720). The present results indicated that λ(max-s) was not statistically different between the device conditions, but that the PLAD significantly reduced λ(max-l) to a negative (stable) value. This shows that subjects' neuromuscular systems were able to respond to local perturbations more effectively when wearing the device, reflecting a more stable control of spinal movements. These findings are important when recommending the PLAD for long-term industrial or clinical use. Copyright © 2010 Elsevier Ltd. All rights reserved.
Hydraulic model of a gas-lift bioreactor with flocculating yeast
Roca, E. [Chemical Engineering Dept., Univ. of Santiago de Compostela (Spain); Ghommidh, C. [G.B.S.A. Microbiologie et Biochimie Industrielle. Univ. Montpellier 2, 34 Montpellier (France); Navarro, J.M. [G.B.S.A. Microbiologie et Biochimie Industrielle. Univ. Montpellier 2, 34 Montpellier (France); Lema, J.M. [Chemical Engineering Dept., Univ. of Santiago de Compostela (Spain)
1995-04-01
The hydraulic model of a gas lift bioreactor, during a continuous alcoholic fermentation by using a strongly flocculating yeast, is analysed. Sucrose at two different concentrations (50 and 100 g/l) was used as substrate and the dilution rate for all the experiments was 1 h{sup -1}. The biomass concentrations were between 85 and 110 g dry weight/l. A stimulus response technique was used to obtain the Residence Time Distribution curves, a pulse of a lactose solution being used as the tracer. Mixing time was determined by means of the response to a pulse of an acid tracer. These experiments were carried out by using an on-line data-acquisition system. The bioreactor behaviour is completely homogeneous, except for high substrate and biomass concentrations. A two parameters combined model is necessary, in this case, to fit the experimental data. Mixing times are very low, in the order of 10 seconds. (orig.)
A COMPRESSION ALGORITHM FOR ECG BASED ON INTEGER LIFTING SCHEME WAVELET TRANSFORM
无
2007-01-01
In view of the shortcomes of conventional ElectroCardioGram (ECG) compression algorithms, such as high complexity of operation and distortion of reconstructed signal, a new ECG compression encoding algorithm based on Set Partitioning In Hierarchical Trees (SPIHT) is brought out after studying the integer lifting scheme wavelet transform in detail. The proposed algorithm modifies zero-tree structure of SPIHT, establishes single dimensional wavelet coefficient tree of ECG signals and enhances the efficiency of SPIHT-encoding by distributing bits rationally, improving zero-tree set and ameliorating classifying method. For this improved algorithm, floating-point computation and storage are left out of consideration and it is easy to be implemented by hardware and software. Experimental results prove that the new algorithm has admirable features of low complexity,high speed and good performance in signal reconstruction. High compression ratio is obtained with high signal fidelity as well.
SPL^{LIFT}: Statically Analyzing Software Product Lines in Minutes instead of Years
Bodden, Eric; Tolêdo, Társis; Ribeiro, Márcio
2013-01-01
IFDS framework for inter-procedural, ﬁnite, distributive, subset problems to an SPL-aware analysis formulated in the IDE framework, a well-known extension to IFDS. Using a full implementation based on Heros, Soot, CIDE and JavaBDD, we show that with SPLLIFT one can reuse IFDS-based analyses without....... In this work, however, we show how an important class of existing inter-procedural static analyses can be transparently lifted to SPLs. Without requiring programmers to change a single line of code, our approach SPLLIFT automatically converts any analysis formulated for traditional programs within the popular...... changing a single line of code. Through experiments using three static analyses applied to four Java-based product lines, we were able to show that our approach produces correct results and outperforms the traditional approach by several orders of magnitude....
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.
Sapountzis, Stamatis; Kim, Ji Hoon; Li, Tzong-Shiun; Rashid, Abid; Cruz, Pedro Ciudad; Hwang, Yoong Soo
2012-12-01
Facial soft tissue lifting with subdermal sutures has a significant attraction for physician and patient alike. The case report describes a 48 year old woman who presented with pain and discomfort over the left cheek after a thread-lift procedure with anti-ptosis (APTOS) sutures performed 13 months previously. The clinical examination showed extrusion of the APTOS thread (Aptos, Moscow, Russia) accompanied by slight soft tissue tightness and tenderness along its course to the temporal area, indicating complete removal of the thread. A simple minimal access cranial suspension lift was performed with the patient under local anesthesia to remove the subdermal sutures together with autologous fat grafting to enhance the aesthetic result. At the 1 year follow-up visit, no complications were reported, and the patient was entirely satisfied with the final result. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .
Tolerability to prolonged lifting tasks. A validation of the recommended limits.
Capodaglio, P; Bazzini, G
1997-01-01
Prolonged physical exertion is subjectively regulated by the perception of effort. This preliminary study was conducted to validate the use of subjective perceptions of effort in assessing objectively tolerable workloads for prolonged lifting tasks. Ten healthy male subjects tested their maximal lifting capacity (MLC) on a lift dynamometer (LidoLift, Loredan Biomed., West Sacramento, CA) and underwent incremental and 30-minute endurance lifting tests. Cardiorespiratory parameters were monitored with an oxygen uptake analyzer, mechanical parameters were calculated using a computerized dynamometer. Ratings of perceived exertion were given on Borg's 10-point scale. Physiological responses to repetitive lifting were matched with subjective perceptions. A single-variable statistical regression for power functions was performed to obtain the individual "iso-perception" curves as functions of the mechanical work exerted. We found that the "iso-perception" curve corresponding to a "moderate" perception of effort may represent the individual "tolerance threshold" for prolonged lifting tasks, since physiological responses at this level of intensity did not change significantly and the respiratory exchange ratio was less than one. The individually tolerable weight for lifting tasks lasting 30 min has been expressed as a percentage of the isoinertial MLC value and compared with the currently recommended limits for prolonged lifting tasks (Italian legislation D.L. 626/94). On the basis of our preliminary results a "tolerance threshold" of 20% MLC has been proposed for prolonged lifting tasks.
PROBABILITY DISTRIBUTION FUNCTION OF NEAR-WALL TURBULENT VELOCITY FLUCTUATIONS
无
2005-01-01
By large eddy simulation (LES), turbulent databases of channel flows at different Reynolds numbers were established. Then, the probability distribution functions of the streamwise and wall-normal velocity fluctuations were obtained and compared with the corresponding normal distributions. By hypothesis test, the deviation from the normal distribution was analyzed quantitatively. The skewness and flatness factors were also calculated. And the variations of these two factors in the viscous sublayer, buffer layer and log-law layer were discussed. Still illustrated were the relations between the probability distribution functions and the burst events-sweep of high-speed fluids and ejection of low-speed fluids-in the viscous sub-layer, buffer layer and loglaw layer. Finally the variations of the probability distribution functions with Reynolds number were examined.
Impact of chevron spacing and asymmetric distribution on supersonic jet acoustics and flow
Heeb, N.; Gutmark, E.; Kailasanath, K.
2016-05-01
An experimental investigation into the effect of chevron spacing and distribution on supersonic jets was performed. Cross-stream and streamwise particle imaging velocimetry measurements were used to relate flow field modification to sound field changes measured by far-field microphones in the overexpanded, ideally expanded, and underexpanded regimes. Drastic modification of the jet cross-section was achieved by the investigated configurations, with both elliptic and triangular shapes attained downstream. Consequently, screech was nearly eliminated with reductions in the range of 10-25 dB depending on the operating condition. Analysis of the streamwise velocity indicated that both the mean shock spacing and strength were reduced resulting in an increase in the broadband shock associated noise spectral peak frequency and a reduction in the amplitude, respectively. Maximum broadband shock associated noise amplitude reductions were in the 5-7 dB range. Chevron proximity was found to be the primary driver of peak vorticity production, though persistence followed the opposite trend. The integrated streamwise vorticity modulus was found to be correlated with peak large scale turbulent mixing noise reduction, though optimal overall sound pressure level reductions did not necessarily follow due to the shock/fine scale mixing noise sources. Optimal large scale mixing noise reductions were in the 5-6 dB range.
Nonlinear prediction of the aerodynamic loads on lifting surfaces
Kandil, O. A.; Mook, D. T.; Nayfeh, A. H.
1974-01-01
A numerical procedure is used to predict the nonlinear aerodynamic characteristics of lifting surfaces of low aspect ratio at high angles of attack for low subsonic Mach numbers. The procedure utilizes a vortex-lattice method and accounts for separation at sharp tips and leading edges. The shapes of the wakes emanating from the edges are predicted, and hence the nonlinear characteristics are calculated. Parallelogram and delta wings are presented as numerical examples. The numerical results are in good agreement with the experimental data.
A continuous-vorticity panel method for lifting surfaces
Yen, A.; Mook, D. T.; Nayfeh, A. H.
1981-01-01
A continuous-vorticity panel method is developed and utilized to predict the steady aerodynamic loads on lifting surfaces having sharp-edge separation. Triangular panels with linearly varying vorticity are used. The velocity field generated by an individual element is obtained in closed form. An optimization scheme is constructed for finding the vorticity at the nodes of the elements. The method is not restricted by aspect ratios, angles of attack, planforms, or camber. Rectangular and delta wings are presented as numerical examples. The numerical results are in good agreement with the experimental data for incompressible flows.
Lift-off dynamics in a simple jumping robot
Aguilar, Jeffrey; Wiesenfeld, Kurt; Goldman, Daniel I
2012-01-01
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 $f_0$. Two distinct jumping modes emerge: a simple jump which is optimal above $f_0$ is achievable with a squat maneuver, and a peculiar stutter jump which is optimal below $f_0$ is generated with a counter-movement. A simple dynamical model reveals how optimal lift-off results from non-resonant transient dynamics.
Large-Area Laser-Lift-Off Processing in Microelectronics
Delmdahl, R.; Pätzel, R.; Brune, J.
Laser lift-off is an enabling technology for microelectronics growth markets such as light emitting diodes, densely packaged semiconductor devices, and flexible displays. For example, thin film transistor structures fabricated on top of polymer layers spun on glass carriers must be delaminated from rigid substrates to create lightweight and rugged flexible displays on polymers. Low-thermal-budget processes are generically required to protect adjacent functional films. Excimer lasers provide short UV wavelength and short pulse duration required for highly-localized energy coupling. The high output power of excimer lasers enables a large processing footprint and the high-throughput rates needed in mass manufacturing.
[Rhabdomyolysis after lifting IKEA bags in a man using sertraline].
Kummen, Ingvild; Jensen, Thomas Giver
2016-12-12
We present a case of a 28-year-old male, using sertraline, who experienced progressive oedema in both upper extremities after having lifted two IKEA bags weighing 20 kg each from his car up to the third floor. Blood creatine kinase (CK) level was measured 5,260 U/l, and the patient was admitted for oral rehydration with the diagnosis rhabdomyolysis. The MRI showed swelling in the triceps muscles and latissimus dorsi muscles resulting in compression of the brachial vein. We discuss the pathomechanism behind the increased CK level and the swelling, and the possible effect sertraline may have had on the development of rhabdomyolysis.
Heavy Lift Vehicle (HLV) Avionics Flight Computing Architecture Study
Hodson, Robert F.; Chen, Yuan; Morgan, Dwayne R.; Butler, A. Marc; Sdhuh, Joseph M.; Petelle, Jennifer K.; Gwaltney, David A.; Coe, Lisa D.; Koelbl, Terry G.; Nguyen, Hai D.
2011-01-01
A NASA multi-Center study team was assembled from LaRC, MSFC, KSC, JSC and WFF to examine potential flight computing architectures for a Heavy Lift Vehicle (HLV) to better understand avionics drivers. The study examined Design Reference Missions (DRMs) and vehicle requirements that could impact the vehicles avionics. The study considered multiple self-checking and voting architectural variants and examined reliability, fault-tolerance, mass, power, and redundancy management impacts. Furthermore, a goal of the study was to develop the skills and tools needed to rapidly assess additional architectures should requirements or assumptions change.
Predictive Maintenance of Hydraulic Lifts through Lubricating Oil Analysis
Stamatios S. Kalligeros
2013-12-01
Full Text Available This article examines the possibility of measuring lift maintenance through analysis of used hydraulic oil. Hydraulic oils have proved to be a reliable indicator for the maintenance performed on elevators. It has also been proved that the end users or the maintenance personnel do not always conform to the instructions of the elevators’ hydraulic machine manufacturer. Furthermore, by examining the proportion of the metals, an estimation of the corrosion and the wear resistance of the joined moving parts can be observed. Additionally, the presence of chlorine and calcium in hydraulic oils demonstrates their function in a highly corrosive environment.
On the estimation of time dependent lift of a European Starling during flapping
Stalnov, Oksana; Kirchhefer, Adam J; Guglielmo, Christoper G; Kopp, Gregory A; Liberzon, Alex; Gurka, Roi
2015-01-01
We study the role of unsteady lift in the context of flapping wings in birds' flight. Both aerodynamicists and biologists attempt to address this subject, yet it seems that the contribution of the unsteady lift still holds many open questions. The current study deals with the estimation of unsteady aerodynamic forces on a freely flying bird through analysis of wingbeat kinematics and near wake flow measurements using time resolved particle image velocimetry. The aerodynamic forces are obtained through unsteady thin airfoil theory and lift calculation using the momentum equation for viscous flows. The unsteady lift is comprised of circulatory and non-circulatory components. Both are presented over wingbeat cycles. Using long sampling data, several wingbeat cycles have been analyzed in order to cover the downstroke and upstroke phases. It appears that the lift varies over the wingbeat cycle emphasizing its contribution to the total lift and its role in power estimations. It is suggested that the circulatory lif...
Articulated Lifting System Modeling Based on Dynamics of Flexible Multi-Body Systems
无
2007-01-01
In lifting sub-system of deep-sea mining system, spherical joint is used to connect lifting pipes to replace fixed joint. Based on Dynamics of Flexible Multi-body systems, the mechanics model of articulated lifting system is established. Under the four-grade and six-grade oceanic condition, dynamic responses of lifting system are simulated and experiment verified. The simulation results are consistent with experimental ones. The maximum moment of flexion is 322 kN-m on the first pipe under six-grade sea condition. It is seen that the articulated connection can reduce the moment of flexion. The bending deformation of pipe center is researched, and the maximum is 0.000479 m on the first pipe. Deformation has a little effect on the motion of system. It is feasible to analyze articulated lifting system by applying the theory of flexible multi-body dynamics. The articulated lifting system is obviously better than the fixed one.
Study on lift-up speed of aerodynamic compliant foil thrust bearings
Yang Lihua; Shi Jianhua; Liu Heng; Yu Lie
2007-01-01
Objective The experimental study on the lift-up speed of a new kind of compliant aerodynamic foil thrust bearings was performed on the multifunctional test rig established for testing the performances of foil gas bearings. Methods The lift-up speed of foil gas thrust bearing under given axial load was analyzed through the spectrum of axial displacement response in frequency domain. Results The test results indicated that the difference in the spectrum of axial displacement responses before and after lifting up of the rotor was obvious. After lifting up of the rotor, there were only larger components of rotation frequency and lower harmanic frequencies. If the rotor wasn't lift-up, there were also larger components of other frequencies in the spectrum. Conclusion So by analyzing the spectrum of axial displacement response, the results showed that the lift-up speed was about 1 860 rpm when the axial load was 31N.
Occupational heavy lifting and risk of ischemic heart disease and all-cause mortality
Petersen, Christina Bjørk; Eriksen, Louise; Tolstrup, Janne S
2012-01-01
ABSTRACT: BACKGROUND: Occupational heavy lifting is known to impose a high cardiovascular strain, but the risk of ischemic heart disease (IHD) from occupational heavy lifting is unknown. The objective was to investigate the association between occupational heavy lifting and risk of IHD and all...... cardiovascular disease at baseline. Conventional risk factors for the outcomes IHD and all-cause mortality were controlled for in Cox analyses. RESULTS: Among men, heavy lifting was associated with increased risk for IHD (hazard ratio (HR): 1.52, 95 % Confidence interval (95 % CI): 1.15, 2.02), while a decreased...... risk was associated with occupational (HR: 0.50, 95 % CI: 0.37, 0.68) and leisure time (HR: 0.73, 95 % CI: 0.56, 0.95) physical activity. Referencing men with high occupational physical activity and no heavy lifting, men with high occupational physical activity and heavy lifting did not have...
Measuring the needle lift and return timing of a CRDI injector using an accelerometer
Choong Hoon Lee
2014-10-01
Full Text Available The needle lift and return timing of a CRDI (common rail direct injection injector were investigated using an accelerometer and the Bosch injection rate measurement method. The Bosch method was used to measure the fuel injection rate shape when fuel was injected with several patterns. An accelerometer was mounted on the outside of the injector to catch the needle lift and return timing of the injector according to the switching signal of the injector driving voltage. The accelerometer accurately caught the timing of the injector needle lift and return for a single-injection pattern, but it could not for the second or third injection when multiple injections occurred. Only the first needle lift timing of the injector was caught with the injection rate shape obtained from the Bosch method, however, this method cannot identify any other lift or return timing values after the first lift timing.
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.
21 CFR 880.5510 - Non-AC-powered patient lift.
2010-04-01
... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Non-AC-powered patient lift. 880.5510 Section 880... Devices § 880.5510 Non-AC-powered patient lift. (a) Identification. A non-AC-powered patient lift is a... patient in the horizontal or other required position from one place to another, as from a bed to a...
Lift Production on Flapping and Rotary Wings at Low Reynolds Numbers
2016-02-26
AFRL-AFOSR-VA-TR-2016-0098 Flapping and Rotary Wing Lift at Low Reynolds Number Anya Jones MARYLAND UNIV COLLEGE PARK Final Report 02/26/2016... Lift Production on Flapping and Rotary Wings at Low Reynolds Numbers (YIP) 5a. CONTRACT NUMBER 5b. GRANT NUMBER FA9550-12-1-0251 5c. PROGRAM...The objective of this research was to identify the mechanisms of lift production on models of an entomological flapping wing stroke by evaluating
Remote sensing image compression method based on lift scheme wavelet transform
Tao, Hongjiu; Tang, Xinjian; Liu, Jian; Tian, Jinwen
2003-06-01
Based on lifting scheme and the construction theorem of the integer Haar wavelet and biorthogonal wavelet, we propose a new integer wavelet transform construct method on the basis of lift scheme after introduciton of constructing specific-demand biorthogonal wavelet transform using Harr wavelet and Lazy wavelet. In this paper, we represent the method and algorithm of the lifting scheme, and we also give mathematical formulation on this method and experimental results as well.
The Use of a Stylet to Aid the Lifting of the Epiglottis With a Video Laryngoscope
2016-01-01
This study involved 154 anesthetized patients requiring endotracheal intubation, in whom the epiglottis was visible but not lifted, which restricted the view of the glottis. A simple stylet was used to lift the epiglottis, thus improving the view of the glottis with the Glide Scope®, allowing tracheal tubes to be inserted into the patients. The stylet easily resolved the difficulty of lifting the epiglottis when using a video laryngoscope, thus facilitating endotracheal intubation in patients...
LiFTinG: Lightweight Freerider-Tracking Protocol in Gossip
Guerraoui, Rachid; Huguenin, Kévin; Kermarrec, Anne-Marie; Monod, Maxime; Prusty, Swagatika
2010-01-01
International audience; This paper presents LiFTinG, the first protocol to detect freeriders, including colluding ones, in gossip-based content dissemination systems with asymmetric data exchanges. LiFTinG relies on nodes tracking abnormal behaviors by cross-checking the history of their previous interactions, and exploits the fact that nodes pick neighbors at random to prevent colluding nodes from covering up each others' bad actions. We present a methodology to set the parameters of LiFTinG...
Comparison of two stump-lifting heads in final felling Norway spruce stand
Karha, K.
2012-07-01
The use of stump and root wood chips has increased very rapidly in the 21st century in Finland: in the year 2000, the total consumption of stump wood chips for energy generation was 10 GWh, while in 2010 it was approximately 2 TWh. Metsaeteho Oy and TTS Research evaluated two stump-lifting devices for the lifting of Norway spruce (Picea abies) stumps. The productivity and costs of stump lifting were determined. There was one base machine with one operator in the time study. When lifting stumps with a diameter of 30 cm, the effective hour productivity of stump lifting was 11.2 m{sup 3} solid over bark (sob)/E0 (4.8 ton{sub D}/E{sub 0}) without site preparation using a Vaekevae Stump Processor, and when lifting spruce stumps with a diameter of 40 cm, the productivity was 14.9 m{sup 3} sob/E{sub 0} (6.5 tonD/E0). When the site preparation (mounding) was integrated into lifting work, the stump-lifting productivity decreased 21-27%. The stump-lifting productivity of the other lifting head (Jarvinen) was lower than that of the Vaekevae Stump Processor. Some development suggestions for the Jarvinen lifting head were presented and discussed. The cost calculations showed that stump-lifting costs are extremely high when stump diameter is less than 20 cm. Therefore, the study recommended a change in the current stump-harvesting guidelines of Finland: The study suggested that all the stumps with a diameter less than 20 cm should be left on the harvesting site. (orig.)
Frost, David M; Abdoli-E, Mohammad; Stevenson, Joan M
2009-12-01
The PLAD (personal lift assistive device) was designed to reduce the lumbar moment during lifting and bending tasks via elastic elements. This investigation examined the effects of modulating the elastic stiffness. Thirteen men completed 90 lifts (15 kg) using 6 different PLAD stiffnesses in stoop, squat and freestyle lifting postures. The activity of 8 muscles were recorded (latissimus dorsi, thoracic and lumbar erector spinae, rectus abdominis, external oblique, gluteus maximus, biceps femoris and rectus femoris), 3D electromagnetic sensors tracked the motion of each segment and strain gauges measured the elastic tension. EMG data were rectified, filtered, normalized and integrated as a percentage of the lifting task. The highest PLAD tension elicited the greatest reduction in erector spinae activity (mean of thoracic and lumbar) in comparison to the no-PLAD condition for the stoop (37%), squat (38%), and freestyle (37%) lifts, while prompting comparable reductions in gluteus maximums and biceps femoris activity. The highest PLAD stiffness also elicited the greatest reduction in the integrated L4/L5 flexion moment for the stoop (19.0%), squat (18.4%) and freestyle (17.4%) lifts without changing peak lumbar flexion. Each increase in PLAD stiffness further reduced the muscle activity of the posterior chain and the dynamic lumbar moment.
High-Lift Optimization Design Using Neural Networks on a Multi-Element Airfoil
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.
An improved method for lifting and transporting anesthetized pigs within an animal facility
Schumacher-Petersen, Camilla; Hammelev, Karsten Pharao; Flescher, Jens Erik
2014-01-01
Transporting anesthetized pigs in a laboratory setting often requires strenuous manual lifting, posing a hazard to the safety of animal care personnel and to the welfare of the pigs. The authors developed an improved approach to lifting and transporting anesthetized pigs weighing up to 350 kg using...... mechanical lifts. Different equipment was used to accommodate pigs of different sizes as well as the building designs of three animal facilities. Using the lifts, anesthetized pigs are carried on sheets to maintain their comfort while being transported. The approach refines previous methods for handling...
CFD Study of an Annular-Ducted Fan Lift System for VTOL Aircraft
Yun Jiang
2015-09-01
Full Text Available The present study aimed at assessing a novel annular-ducted fan lift system for VTOL aircraft through computational fluid dynamics (CFD simulations. The power and lift efficiency of the lift fan system in hover mode, the lift and drag in transition mode, the drag and flight speed of the aircraft in cruise mode and the pneumatic coupling of the tip turbine and jet exhaust were studied. The results show that the annular-ducted fan lift system can have higher lift efficiency compared to the rotor of the Apache helicopter; the smooth transition from vertical takeoff to cruise flight needs some extra forward thrust to overcome a low peak of drag; the aircraft with the lift fan system enclosed during cruise flight theoretically may fly faster than helicopters and tiltrotors based on aerodynamic drag prediction, due to the elimination of rotor drag and compressibility effects on the rotor blade tips; and pneumatic coupling of the tip turbine and jet exhaust of a 300 m/s velocity can provide enough moment to spin the lift fan. The CFD results provide insight for future experimental study of the annular-ducted lift fan VTOL aircraft.
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.
Osteotomy in direct sinus lift. A comparative study of the rotary technique and ultrasound
Peñarrocha-Diago, María; Peñarrocha-Diago, Miguel; Sanchez-Recio, Cristina; Peñarrocha-Oltra, David; Romero-Millán, Javier
2012-01-01
The present study investigates sinus membrane rupture in direct maxillary sinus lift with the rotary technique and with ultrasound, examining the survival of implants placed after sinus augmentation...
Application of adaptive wavelet transforms via lifting in image data compression
Ye, Shujiang; Zhang, Ye; Liu, Baisen
2008-10-01
The adaptive wavelet transforms via lifting is proposed. In the transform, update filter is selected by the signal's character. Perfect reconstruction is possible without any overhead cost. To make sure the system's stability, in the lifting scheme of adaptive wavelet, update step is placed before prediction step. The Adaptive wavelet transforms via lifting is benefit for the image compression, because of the high stability, the small coefficients of high frequency parts, and the perfect reconstruction. With the adaptive wavelet transforms via lifting and the SPIHT, the image compression is realized in this paper, and the result is pleasant.
Visser, Steven; van der Molen, Henk F; Kuijer, P Paul F M; Hoozemans, Marco J M; Frings-Dresen, Monique H W
2014-11-01
The objective of this study was to assess differences in work demands, energetic workload and workers' discomfort and physical effort in two regularly observable workdays in ironwork; one where loads up to 50kg were handled with two persons manually (T50) and one where loads up to 100kg were handled manually with four persons (T100). Differences between these typical workdays were assessed with an observational within-subject field study of 10 ironworkers. No significant differences were found for work demands, energetic workload or discomfort between T50 and T100 workdays. During team lifts, load mass exceeded 25kg per person in 57% (T50 workday) and 68% (T100 workday) of the lifts. Seven ironworkers rated team lifting with two persons as less physically demanding compared with lifting with four persons. When loads heavier than 25kg are lifted manually with a team, regulations of the maximum mass weight are frequently violated. Loads heavier than 25kg are frequently lifted during concrete reinforcement work and should be lifted by a team of persons. However, the field study showed that loads above 25kg are most of the time not lifted with the appropriate number of workers. Therefore, loads heavier than 25kg should be lifted mechanically. Copyright © 2014 Elsevier Ltd and The Ergonomics Society. All rights reserved.
Study on dynamic characteristics of coupled model for deep-water lifting system
Wu, Yunxia; Lu, Jianhui; Zhang, Chunlei
2016-10-01
The underwater installation of marine equipment in deep-water development requires safe lifting and accurate positioning. The heave compensation system is an important technology to ensure normal operation and improve work accuracy. To provide a theoretical basis for the heave compensation system, in this paper, the continuous modeling method is employed to build up a coupled model of deep-water lifting systems in vertical direction. The response characteristics of dynamic movement are investigated. The simulation results show that the resonance problem appears in the process of the whole releasing load, the lifting system generates resonance and the displacement response of the lifting load is maximal when the sinking depth is about 2000 m. This paper also analyzes the main influencing factors on the dynamic response of load including cable stiffness, damping coefficient of the lifting system, mass and added mass of lifting load, among which cable stiffness and damping coefficient of the lifting system have the greatest influence on dynamic response of lifting load when installation load is determined. So the vertical dynamic movement response of the load is reduced by installing a damper on the lifting cable and selecting the appropriate cable stiffness.
Functional dorsoventral symmetry in relation to lift-based swimming in the ocean sunfish Mola mola.
Watanabe, Yuuki; Sato, Katsufumi
2008-01-01
The largest (up to 2 tons) and a globally distributed teleost--the ocean sunfish Mola mola--is commonly regarded as a planktonic fish because of its unusual shape including absence of caudal fin. This common view was recently questioned because the horizontal movements of the ocean sunfish tracked by acoustic telemetry were independent of ocean currents. However, direct information regarding their locomotor performance under natural conditions is still lacking. By using multi-sensor tags, we show that sunfish indeed swam continuously with frequent vertical movements at speeds of 0.4-0.7 m s(-1), which is similar to the records of other large fishes such as salmons, marlins, and pelagic sharks. The acceleration data revealed that they stroked their dorsal and anal fins synchronously (dominant frequency, 0.3-0.6 Hz) to generate a lift-based thrust, as penguins do using two symmetrical flippers. Morphological studies of sunfish (mass, 2-959 kg) showed that the dorsal and anal fins had similar external (symmetrical shape and identical area) and internal (identical locomotory muscle mass) features; however, the muscle shape differed markedly. We conclude that ocean sunfish have functional dorsoventral symmetry with regards to the non-homologous dorsal and anal fins that act as a pair of vertical hydrofoils. Although sunfish lack a swimbladder, we found that they are neutrally buoyant independent of depth because of their subcutaneous gelatinous tissue that has low density and is incompressible. Efficient lift-based swimming in conjunction with neutral buoyancy enables sunfish to travel long distances both horizontally and vertically.
Failure Modes and Causes for Swing and Lift Type Check Valves.
McElhaney, K.L.
1997-12-31
Prior to the recent work performed by Oak Ridge National Laboratory (ORNL)relative to nuclear industry check valve performance, no information was readily available regarding the failure characteristics of check valves based on valve type (e.g., swing check, lift check). Although it had been recognized by component experts that the two most significant factors in determining check valve performance were valve design (i.e., type) and operating conditions, no industry data was available relative to the former. In cooperation with the Nuclear Industry Check Valve Group (NIC), ORNL has reviewed and analyzed check valve failures from the Institute of Nuclear Power Operations` (INPOs`) Nuclear Plant Reliability Database System (NPRDS) according to several parameters,including valve type. Since the valve type identification is not inherently included within the NPRDS engineering record for each component, ORNL had to rely upon input from NIC, valve manufacturers, and catalogs to supply the missing information. As a result of this effort, approximately 77% of the check valve failures occurring during the 1991-1996 study period and nearly 62% of the overall installed population were identified according to type. This data provided the basis to perform previously unavailable cross-correlations between parameters such as valve type versus failure mode and failure cause. Design characteristics and service applications differ markedly among check valve types, resulting in discernible differences in performance. This paper focuses on the performance characteristics of swing and lift type check valves since failure and population distributions have shown these to be the two most common types employed in a wide range of nuclear plant applications.
Functional dorsoventral symmetry in relation to lift-based swimming in the ocean sunfish Mola mola.
Yuuki Watanabe
Full Text Available The largest (up to 2 tons and a globally distributed teleost--the ocean sunfish Mola mola--is commonly regarded as a planktonic fish because of its unusual shape including absence of caudal fin. This common view was recently questioned because the horizontal movements of the ocean sunfish tracked by acoustic telemetry were independent of ocean currents. However, direct information regarding their locomotor performance under natural conditions is still lacking. By using multi-sensor tags, we show that sunfish indeed swam continuously with frequent vertical movements at speeds of 0.4-0.7 m s(-1, which is similar to the records of other large fishes such as salmons, marlins, and pelagic sharks. The acceleration data revealed that they stroked their dorsal and anal fins synchronously (dominant frequency, 0.3-0.6 Hz to generate a lift-based thrust, as penguins do using two symmetrical flippers. Morphological studies of sunfish (mass, 2-959 kg showed that the dorsal and anal fins had similar external (symmetrical shape and identical area and internal (identical locomotory muscle mass features; however, the muscle shape differed markedly. We conclude that ocean sunfish have functional dorsoventral symmetry with regards to the non-homologous dorsal and anal fins that act as a pair of vertical hydrofoils. Although sunfish lack a swimbladder, we found that they are neutrally buoyant independent of depth because of their subcutaneous gelatinous tissue that has low density and is incompressible. Efficient lift-based swimming in conjunction with neutral buoyancy enables sunfish to travel long distances both horizontally and vertically.
Lifting Entry & Atmospheric Flight (LEAF) Applications at Solar System Bodies.
Lee, G.; Sen, B.; Polidan, R. S.
2015-12-01
Introduction: Northrop Grumman and L'Garde have continued the development of a hypersonic entry, maneuverable platform capable of performing long-duration (months to a year) in situ and remote measurements at any solar system body that possesses an atmosphere. The Lifting Entry & Atmospheric Flight (LEAF) family of vehicles achieve this capability by using a semi-buoyant, ultra-low ballistic coefficient vehicle whose lifting entry allows it to enter the atmosphere without an aeroshell. In this presentation, we discuss the application of the LEAF system at various solar system bodies: Venus, Titan, Mars, and Earth. We present the key differences in platform design as well as operational differences required by the various target environments. The Venus implementation includes propulsive capability to reach higher altitudes during the day and achieves full buoyancy in the "habitable layers" of Venus' atmosphere at night. Titan also offers an attractive operating environment, allowing LEAF designs that can target low, medium, or high altitude operations, also with propulsive capabilities to roam within each altitude regime. The Mars version is a glider that descends gradually, allowing targeted delivery of payloads to the surface. Finally, an Earth version could remain in orbit in a stowed state until activated, allowing rapid response type deployments to any region of the globe.
Experiments to investigate lift production mechanisms on pitching flat plates
Stevens, P. R. R. J.; Babinsky, H.
2017-01-01
Pitching flat plates are a useful simplification of flapping wings, and their study can provide useful insights into unsteady force generation. Non-circulatory and circulatory lift producing mechanisms for low Reynolds number pitching flat plates are investigated. A series of experiments are designed to measure forces and study the unsteady flowfield development. Two pitch axis positions are investigated, namely a leading edge and a mid-chord pitch axis. A novel PIV approach using twin laser lightsheets is shown to be effective at acquiring full field of view velocity data when an opaque wing model is used. Leading-edge vortex (LEV) circulations are extracted from velocity field data, using a Lamb-Oseen vortex fitting algorithm. LEV and trailing-edge vortex positions are also extracted. It is shown that the circulation of the LEV, as determined from PIV data, approximately matches the general trend of an unmodified Wagner function for a leading edge pitch axis and a modified Wagner function for a mid-chord pitch axis. Comparison of experimentally measured lift correlates well with the prediction of a reduced-order model for a LE pitch axis.
Jet flow control at the blade scale to manipulate lift
Braud, Caroline; Guilmineau, Emmanuel
2016-09-01
The turbulent atmospheric boundary layer in which wind turbines are implemented is strongly inhomogeneous and unsteady. This induces unsteady mechanical loads at different characteristic time scales from seconds to minutes which limits significantly their life time. Different control strategies have been proposed in the framework of the French ANR SmartEole project to alleviate the impact of these upstream fluctuations at the farm, wind turbine and blade scales (i.e. characteristic time scales from seconds to minutes). The present work, which is part of this ANR project, focuses on the flow control strategies at the blade scale, to manipulate lift and thus alleviate fatigue loads. The design of a NACA654-421 airfoil profile has been modified to be able to implement jet control. Slotted jet and discrete jet configurations were implemented numerically and experimentally respectively. Results show the ability of both configurations to increase the lift by up to 30% using a significant redistribution of the mean shear. Efficiency seems to be more important using slotted jets, which however needs to be confirmed from 3D simulations.
Eisenhart lifts and symmetries of time-dependent systems
Cariglia, M.; Duval, C.; Gibbons, G. W.; Horváthy, P. A.
2016-10-01
Certain dissipative systems, such as Caldirola and Kannai's damped simple harmonic oscillator, may be modelled by time-dependent Lagrangian and hence time dependent Hamiltonian systems with n degrees of freedom. In this paper we treat these systems, their projective and conformal symmetries as well as their quantisation from the point of view of the Eisenhart lift to a Bargmann spacetime in n + 2 dimensions, equipped with its covariantly constant null Killing vector field. Reparametrisation of the time variable corresponds to conformal rescalings of the Bargmann metric. We show how the Arnold map lifts to Bargmann spacetime. We contrast the greater generality of the Caldirola-Kannai approach with that of Arnold and Bateman. At the level of quantum mechanics, we are able to show how the relevant Schrödinger equation emerges naturally using the techniques of quantum field theory in curved spacetimes, since a covariantly constant null Killing vector field gives rise to well defined one particle Hilbert space. Time-dependent Lagrangians arise naturally also in cosmology and give rise to the phenomenon of Hubble friction. We provide an account of this for Friedmann-Lemaître and Bianchi cosmologies and how it fits in with our previous discussion in the non-relativistic limit.
Lifting a Butterfly – A Component-Based FFT
Sibylle Schupp
2003-01-01
Full Text Available While modern software engineering, with good reason, tries to establish the idea of reusability and the principles of parameterization and loosely coupled components even for the design of performance-critical software, Fast Fourier Transforms (FFTs tend to be monolithic and of a very low degree of parameterization. The data structures to hold the input and output data, the element type of these data, the algorithm for computing the so-called twiddle factors, the storage model for a given set of twiddle factors, all are unchangeably defined in the so-called butterfly, restricting its reuse almost entirely. This paper shows a way to a component-based FFT by designing a parameterized butterfly. Based on the technique of lifting, this parameterization includes algorithmic and implementation issues without violating the complexity guarantees of an FFT. The paper demonstrates the lifting process for the Gentleman-Sande butterfly, i.e., the butterfly that underlies the large class of decimation-in-frequency (DIF FFTs, shows the resulting components and summarizes the implementation of a component-based, generic DIF library in C++.
Lifting gate polydimethylsiloxane microvalves and pumps for microfluidic control.
Kim, Jungkyu; Kang, Minjee; Jensen, Erik C; Mathies, Richard A
2012-02-21
We describe the development and characterization of pneumatically actuated "lifting gate" microvalves and pumps. A fluidic layer containing the gate structure and a pneumatic layer are fabricated by soft-lithography in PDMS and bonded permanently with an oxygen plasma treatment. The microvalve structures are then reversibly bonded to a featureless glass or plastic substrate to form hybrid glass-PDMS and plastic-PDMS microchannel structures. The break-through pressures of the microvalve increase linearly up to 65 kPa as the closing pressure increases. The pumping capability of these structures ranges from the nanoliter to microliter scale depending on the number of cycles and closing pressure employed. The micropump structures exhibit up to 86.2% pumping efficiency from flow rate measurements. The utility of these structures for integrated sample processing is demonstrated by performing an automated immunoassay. These lifting gate valve and pump structures enable facile integration of complex microfluidic control systems with a wide range of lab-on-a-chip substrates.
Effect of hydrogen addition on autoignited methane lifted flames
Choin, Byung Chul
2012-01-01
Autoignited lifted flames in laminar jets with hydrogen-enriched methane fuels have been investigated experimentally in heated coflow air. The results showed that the autoignited lifted flame of the methane/hydrogen mixture, which had an initial temperature over 920 K, the threshold temperature for autoignition in methane jets, exhibited features typical of either a tribrachial edge or mild combustion depending on fuel mole fraction and the liftoff height increased with jet velocity. The liftoff height in the hydrogen-assisted autoignition regime was dependent on the square of the adiabatic ignition delay time for the addition of small amounts of hydrogen, as was the case for pure methane jets. When the initial temperature was below 920 K, where the methane fuel did not show autoignition behavior, the flame was autoignited by the addition of hydrogen, which is an ignition improver. The liftoff height demonstrated a unique feature in that it decreased nonlinearly as the jet velocity increased. The differential diffusion of hydrogen is expected to play a crucial role in the decrease in the liftoff height with increasing jet velocity.
Image compression with directional lifting on separated sections
Zhu, Jieying; Wang, Nengchao
2007-11-01
A novel image compression scheme is presented that the directional sections are separated and transformed differently from the rest of image. The discrete directions of anisotropic pixels are calculated and then grouped to compact directional sections. One dimensional (1-D) adaptive directional lifting is continuously applied along orientations of direction sections other than applying 1-D wavelet transform alternately in two dimensions for the whole image. For the rest sections, 2-D adaptive lifting filters are applied according to pixels' positions. Our single embedded coding stream can be truncated exactly for any bit rate. Experiments have showed that large coefficients can be significantly reduced along directional sections by our transform which makes energy more compact than traditional wavelet transform. Though rate-distortion (R-D) optimization isn't exploited, the PSNR is still comparable to that of JPEG-2000 with 9/7 filters at high bit rates. And at low bit rates, the visual quality is better than that of JPEG-2000 for along directional sections both blurring and ringing artifacts can be avoided and edge preservation is good.
Building the Composite Face Lift: A Personal Odyssey.
Hamra, Sam T
2016-07-01
This article is a 42-year history of the development of a comprehensive face-lift technique by the author. It describes how the composite rhytidectomy has been constructed, anatomical area by anatomical area, over the author's lifetime career as a plastic surgeon. Over the course of these years, beginning with Skoog's 1973 description of using the platysma muscle of the lower face, it describes how progressively the other significant structures of anatomy necessary to be used in achieving significant rejuvenation have been analyzed by the author and in turn surgically repositioned. The theory was based on creating a composite flap of the face, keeping the orbicularis oculi muscle, facial platysma muscle, and cheek fat in their normal anatomical and intimate relationship with each other by using the skin as the carriage. In addition, differences of vectors between the composite rhytidectomy and traditional techniques are demonstrated. The gradual and persistent pursuit of periorbital rejuvenation using the lower eyelid fat and the septal orbitale is described. Each of the anatomical structures involved and the description of their importance and surgical execution have been published over the surgical career of the author, including use of the same principles for reversing suboptimal face-lift results.
Weight lifting training and left ventricular function in adolescent subjects.
Sagiv, M; Sagiv, M; Ben-Sira, D
2007-09-01
Training during adolescence may influence the myocardium's adaptation. Effects of exercise training on left ventricular function differ depending whether they result from pressure or volume overload. Accordingly, the present study was designed to examine, by echocardiography studies, the effects of endurance versus weight lifting training modes on left ventricular contractility in healthy adolescent boys. Sixty healthy adolescent boys were randomly and evenly divided into 3 groups: weightlifting training, run-training, and control. Exercising groups underwent 28-week training programs, 3-4 times a week, 35 min each session. The weight lifting program for consisted of training on 6 dynamic resistive machines at resistance corresponding to 6-repetition maximum. The running program was composed of aerobic exercise training at 65% of their VO(2max). At rest, only in the runners end diastolic volume and end systolic pressure-volume ratio differed significantly (Pweightlifters demonstrated improvement respectively in: wall stress (245+/-42 and 290+/-35 103 dyn.cm(2)), end systolic pressure-volume ratio (7.2+/-.7 and 6.4+/-.5 ratio) and ejection fraction (82+/-5% and 76+/-5%). Maximal oxygen uptake (48.2+/-3.2 and 43.8+/-3.5 mL.kg(-1).min(-1)), also improved significantly (Padolescent boys the mode of exercise training leads to significant differences in left ventricular function and contractility, related to differences in volume-after-load relationship and not to fundamental differences in the properties of the myocardium.
Weight lifting can facilitate appreciative comprehension for museum exhibits
Yuki eYamada
2014-04-01
Full Text Available Appreciation of exhibits in a museum can be equated to a virtual experience of lives in the contexts originally surrounding the exhibits. Here we focus on the importance of weight information, and hence tested whether experiencing a weight during museum exhibit appreciation affects the beholders’ satisfaction and recognition memory for the exhibits. An experiment was performed at a museum exhibiting skeletal preparations of animals. We used nine preparations and prepared four weight stimuli as weight cues in accordance with the actual weight of four of the preparations: Remaining five preparations was displayed without weight stimuli. In the cued condition, participants were asked to lift up the weight stimuli during their observation of the four exhibits. In the uncued condition, participants observed the exhibits without touching the weight stimuli. After observation of the exhibits, the participants responded to a questionnaire that measured their impressions of the exhibits and the museum, and performed a recognition test on the exhibits. Results showed that memory performance was better and viewing duration was longer with weight lifting instruction than without instruction. A factor analysis on the questionnaires revealed four factors (likeability, contentment, value, and quality. A path analysis showed indirect effects of viewing duration on memory performance and willingness-to-pay for the museum appreciation through the impression factors. Our findings provide insight into a new interactive exhibition that enables long appreciation producing positive effects on visitors’ impression, memory, and value estimation for exhibits.
Jensen, L K
2008-01-01
The aim of the study was to evaluate the evidence for an association between hip osteoarthritis (OA) and physical work demands. Systematic searches were made and epidemiological studies on hip OA and heavy lifting, including farming and construction work and climbing stairs, were reviewed for the period 1966-2007 inclusive. The quality of the studies was assessed and best-evidence syntheses of a causal relation between hip OA and physical demanding work have been made using specific criteria of the different degrees of evidence of causality. Limitations of the studies include few participants, use of different diagnostic criteria, and a poor description of the exposure. It is concluded that moderate to strong evidence was found for a relation between heavy lifting and hip OA. The burdens have to be at least 10-20 kg and the duration at least 10-20 years to give a clearly increased risk of hip OA. For farmers the risk of hip OA seems doubled after approximately 10 years of farming and the evidence is considered as moderate to strong. The evidence for a relation between hip OA for construction workers is limited and there is insufficient or no evidence that climbing stairs or ladders causes hip OA.
Abrasion behavior of graphite pebble in lifting pipe of pebble-bed HTR
Shen, Ke; Su, Jiageng [Institute of Nuclear and New Energy Technology, Advanced Nuclear Energy Technology Cooperation Innovation Center, The Key Laboratory of Advanced Nuclear Engineering and Safety, Ministry of Education, Beijing 10084 (China); Zhou, Hongbo [Institute of Nuclear and New Energy Technology, Advanced Nuclear Energy Technology Cooperation Innovation Center, The Key Laboratory of Advanced Nuclear Engineering and Safety, Ministry of Education, Beijing 10084 (China); Chinergy Co., LTD., Beijing 100193 (China); Peng, Wei; Liu, Bing [Institute of Nuclear and New Energy Technology, Advanced Nuclear Energy Technology Cooperation Innovation Center, The Key Laboratory of Advanced Nuclear Engineering and Safety, Ministry of Education, Beijing 10084 (China); Yu, Suyun, E-mail: suyuan@tsinghua.edu.cn [Center for Combustion Energy, The Key Laboratory for Thermal Science and Power Engineering, Ministry of Educations, Tsinghua University, Beijing 10084 (China)
2015-11-15
Highlights: • Quantitative determination of abrasion rate of graphite pebbles in different lifting velocities. • Abrasion behavior of graphite pebble in helium, air and nitrogen. • In helium, intensive collisions caused by oscillatory motion result in more graphite dust production. - Abstract: A pebble-bed high-temperature gas-cooled reactor (pebble-bed HTR) uses a helium coolant, graphite core structure, and spherical fuel elements. The pebble-bed design enables on-line refueling, avoiding refueling shutdowns. During circulation process, the pebbles are lifted pneumatically via a stainless steel lifting pipe and reinserted into the reactor. Inevitably, the movement of the fuel elements as they recirculate in the reactor produces graphite dust. Mechanical wear is the primary source of graphite dust production. Specifically, the sources are mechanisms of pebble–pebble contact, pebble–wall (structural graphite) contact, and fuel handling (pebble–metal abrasion). The key contribution to graphite dust production is from the fuel handling system, particularly from the lifting pipe. During pneumatic lift, graphite pebbles undergo multiple collisions with the stainless steel lifting pipe, thereby causing abrasion of the graphite pebbles and producing graphite dust. The present work explored the abrasion behavior of graphite pebble in the lifting pipe by measuring the abrasion rate at different lifting velocities. The abrasion rate of the graphite pebble in helium was found much higher than those in air and nitrogen. This gas environment effect could be explained by either tribology behavior or dynamic behavior. Friction testing excluded the possibility of tribology reason. The dynamic behavior of the graphite pebble was captured by analysis of the audio waveforms during pneumatic lift. The analysis results revealed unique dynamic behavior of the graphite pebble in helium. Oscillation and consequently intensive collisions occur during pneumatic lift, causing
Fuel properties to enable lifted-flame combustion
Kurtz, Eric [Ford Motor Company, Dearborn, MI (United States)
2015-03-15
The Fuel Properties to Enable Lifted-Flame Combustion project responded directly to solicitation DE-FOA-0000239 AOI 1A, Fuels and Lubricants for Advanced Combustion Regimes. This subtopic was intended to encompass clean and highly-efficient, liquid-fueled combustion engines to achieve extremely low engine-out nitrogen oxides (NOx) and particulate matter (PM) as a target and similar efficiency as state-of-the-art direct injection diesel engines. The intent of this project was to identify how fuel properties can be used to achieve controllable Leaner Lifted Flame Combustion (LLFC) with low NOx and PM emissions. Specifically, this project was expected to identify and test key fuel properties to enable LLFC and their compatibility with current fuel systems and to enhance combustion models to capture the effect of fuel properties on advanced combustion. Successful demonstration of LLFC may reduce the need for after treatment devices, thereby reducing costs and improving thermal efficiency. The project team consisted of key technical personnel from Ford Motor Company (FMC), the University of Wisconsin-Madison (UW), Sandia National Laboratories (SNL) and Lawrence Livermore National Laboratories (LLNL). Each partner had key roles in achieving project objectives. FMC investigated fuel properties relating to LLFC and sooting tendency. Together, FMC and UW developed and integrated 3D combustion models to capture fuel property combustion effects. FMC used these modeling results to develop a combustion system and define fuel properties to support a single-cylinder demonstration of fuel-enabled LLFC. UW investigated modeling the flame characteristics and emissions behavior of different fuels, including those with different cetane number and oxygen content. SNL led spray combustion experiments to quantify the effect of key fuel properties on combustion characteristics critical for LLFC, as well as single cylinder optical engine experiments to improve fundamental