WorldWideScience

Sample records for active flap rotor

  1. Active Flap Control of the SMART Rotor for Vibration Reduction

    Science.gov (United States)

    Hall, Steven R.; Anand, R. Vaidyanathan; Straub, Friedrich K.; Lau, Benton H.

    2009-01-01

    Active control methodologies were applied to a full-scale active flap rotor obtained during a joint Boeing/ DARPA/NASA/Army test in the Air Force National Full-Scale Aerodynamic Complex 40- by 80-foot anechoic wind tunnel. The active flap rotor is a full-scale MD 900 helicopter main rotor with each of its five blades modified to include an on-blade piezoelectric actuator-driven flap with a span of 18% of radius, 25% of chord, and located at 83% radius. Vibration control demonstrated the potential of active flaps for effective control of vibratory loads, especially normal force loads. Active control of normal force vibratory loads using active flaps and a continuous-time higher harmonic control algorithm was very effective, reducing harmonic (1-5P) normal force vibratory loads by 95% in both cruise and approach conditions. Control of vibratory roll and pitch moments was also demonstrated, although moment control was less effective than normal force control. Finally, active control was used to precisely control blade flap position for correlation with pretest predictions of rotor aeroacoustics. Flap displacements were commanded to follow specific harmonic profiles of 2 deg or more in amplitude, and the flap deflection errors obtained were less than 0.2 deg r.m.s.

  2. Identification of Flap Motion Parameters for Vibration Reduction in Helicopter Rotors with Multiple Active Trailing Edge Flaps

    Directory of Open Access Journals (Sweden)

    Uğbreve;ur Dalli

    2011-01-01

    Full Text Available An active control method utilizing the multiple trailing edge flap configuration for rotorcraft vibration suppression and blade loads control is presented. A comprehensive model for rotor blade with active trailing edge flaps is used to calculate the vibration characteristics, natural frequencies and mode shapes of any complex composite helicopter rotor blade. A computer program is developed to calculate the system response, rotor blade root forces and moments under aerodynamic forcing conditions. Rotor blade system response is calculated using the proposed solution method and the developed program depending on any structural and aerodynamic properties of rotor blades, structural properties of trailing edge flaps and properties of trailing edge flap actuator inputs. Rotor blade loads are determined first on a nominal rotor blade without multiple active trailing edge flaps and then the effects of the active flap motions on the existing rotor blade loads are investigated. Multiple active trailing edge flaps are controlled by using open loop controllers to identify the effects of the actuator signal output properties such as frequency, amplitude and phase on the system response. Effects of using multiple trailing edge flaps on controlling rotor blade vibrations are investigated and some design criteria are determined for the design of trailing edge flap controller that will provide actuator signal outputs to minimize the rotor blade root loads. It is calculated that using the developed active trailing edge rotor blade model, helicopter rotor blade vibrations can be reduced up to 36% of the nominal rotor blade vibrations.

  3. Enhanced Correlation of SMART Active Flap Rotor Loads

    Science.gov (United States)

    Kottapalli, Sesi

    2011-01-01

    This is a follow-on study to a 2010 correlation effort. Measured data from the SMART rotor test in the NASA Ames 40- by 80- Foot Wind Tunnel are compared with CAMRAD II calculations. As background, during the wind tunnel test, unexpectedly high inboard loads were encountered, and it was hypothesized at that time that due to changes in the flexbeams over the years, the flexbeam properties used in the analysis needed updating. Boeing Mesa, recently updated these properties. This correlation study uses the updated flexbeam properties. Compared to earlier studies, the following two enhancements are implemented: i) the inboard loads (pitchcase and flexbeam loads) correlation is included for the first time (reliable prediction of the inboard loads is a prerequisite for any future anticipated flight-testing); ii) the number of blade modes is increased to better capture the flap dynamics and the pitchcase-flexbeam dynamics. Also, aerodynamically, both the rolled-up wake model and the more complex, multiple trailer wake model are used, with the latter slightly improving the blade chordwise moment correlation. This sensitivity to the wake model indicates that CFD is needed. Three high-speed experimental cases, one uncontrolled free flap case and two commanded flap cases, are considered. The two commanded flap cases include a 2o flap deflection at 5P case and a 0o flap deflection case. For the free flap case, selected modifications to the HH-06 section flap airfoil pitching moment table are implemented. For the commanded 2o flap case, the experimental flap variation is approximately matched by increasing the analytical flap hinge stiffness. This increased flap hinge stiffness is retained for the commanded 0o flap case also, which is treated as a free flap case, but with larger flap hinge stiffness. The change in the mid-span and outboard loads correlation due to the updating of the flexbeam properties is not significant. Increasing the number of blade modes results in an

  4. Adaptive Trailing Edge Flaps for Active Load Alleviation in a Smart Rotor Configuration

    DEFF Research Database (Denmark)

    Bergami, Leonardo

    with flaps laid out on the outer 20 % of the blade span, from 77 % to 97% of the blade length. The configuration is first tested with a simplified cyclic control approach, which gives a preliminary indication of the load alleviation potential, and also reveals the possibility to enhance the rotor energy......-MPC requires lower flap activity, and also achieves higher reductions of the tower fatigue loads, thus indicating that a combined control approach that coordinates and integrates all available sensors and actuators has the potential for overall better results than achieved by a series of independent control...

  5. Adaptive trailing edge flaps for active load alleviation in a smart rotor configuration

    Energy Technology Data Exchange (ETDEWEB)

    Bergami, L.

    2013-08-15

    The work investigates the development of an active smart rotor concept from an aero-servo-elastic perspective. An active smart rotor is a wind turbine rotor that, through a combination of sensors, control units and actuators, is able to alleviate the fluctuating part of the aerodynamic loads it has to withstand. The investigation focuses on a specific actuator type: the Adaptive Trailing Edge Flap (ATEF), which introduces a continuous deformation of the aft part of the airfoil camber-line. An aerodynamic model that accounts for the steady and unsteady effects of the flap deflection on a 2D airfoil section is developed, and, considering both attached and separated flow conditions, is validated by comparison against Computational Fluid Dynamic solutions and a panel code method. The aerodynamic model is integrated in the BEM-based aeroelastic simulation code HAWC2, thus providing a tool able to simulate the response of a wind turbine equipped with ATEF. A load analysis of the NREL 5 MW reference turbine in its baseline configuration reveals that the highest contribution to the blade flapwise fatigue damage originates from normal operation above rated wind speed, and from loads characterized by frequencies below 1 Hz. The analysis also reports that periodic load variations on the turbine blade account for nearly 11 % of the blade flapwise lifetime fatigue damage, while the rest is ascribed to load variations from disturbances of stochastic nature. The study proposes a smart rotor configuration with flaps laid out on the outer 20 % of the blade span, from 77 % to 97% of the blade length. The configuration is first tested with a simplified cyclic control approach, which gives a preliminary indication of the load alleviation potential, and also reveals the possibility to enhance the rotor energy capture below rated conditions by using the flaps. Two model based control algorithms are developed to actively alleviate the fatigue loads on the smart rotor with ATEF. The first

  6. HIGH EFFICIENCY STRUCTURAL FLOWTHROUGH ROTOR WITH ACTIVE FLAP CONTROL: VOLUME ONE: PRELIMINARY DESIGN REPORT

    Energy Technology Data Exchange (ETDEWEB)

    Zuteck, Michael D. [Zimitar, Inc.; Jackson, Kevin L. [Zimitar, Inc.; Santos, Richard A. [Zimitar, Inc.; Chow, Ray [Zimitar, Inc.; Nordenholz, Thomas R. [The California Maritime Academy; Wamble, John Lee [Zimitar, Inc.

    2015-05-16

    The Zimitar one-piece rotor primary structure is integrated, so balanced thrust and gravity loads flow through the hub region without transferring out of its composite material. Large inner rotor geometry is used since there is no need to neck down to a blade root region and pitch bearing. Rotor control is provided by a highly redundant, five flap system on each blade, sized so that easily handled standard electric linear actuators are sufficient.

  7. HIGH EFFICIENCY STRUCTURAL FLOWTHROUGH ROTOR WITH ACTIVE FLAP CONTROL: VOLUME TWO: INNOVATION & COST OF ENERGY

    Energy Technology Data Exchange (ETDEWEB)

    Zuteck, Michael D. [Zimitar, Inc.; Jackson, Kevin L. [Zimitar, Inc.; Santos, Richard A. [Zimitar, Inc.

    2015-05-16

    The Zimitar one-piece rotor primary structure is integrated, so balanced thrust and gravity loads flow through the hub region without transferring out of its composite material. Large inner rotor geometry is used since there is no need to neck down to a blade root region and pitch bearing. Rotor control is provided by a highly redundant, five flap system on each blade, sized so that easily handled standard electric linear actuators are sufficient.

  8. HIGH EFFICIENCY STRUCTURAL FLOWTHROUGH ROTOR WITH ACTIVE FLAP CONTROL: VOLUME ZERO: OVERVIEW AND COMMERCIAL PATH

    Energy Technology Data Exchange (ETDEWEB)

    Zuteck, Michael D. [Zimitar, Inc.; Jackson, Kevin L. [Zimitar, Inc.; Santos, Richard A. [Zimitar, Inc.

    2015-05-16

    The Zimitar one-piece rotor primary structure is integrated, so balanced thrust and gravity loads flow through the hub region without transferring out of its composite material. Large inner rotor geometry is used since there is no need to neck down to a blade root region and pitch bearing. Rotor control is provided by a highly redundant, five flap system on each blade, sized so that easily handled standard electric linear actuators are sufficient.

  9. HIGH EFFICIENCY STRUCTURAL FLOWTHROUGH ROTOR WITH ACTIVE FLAP CONTROL: VOLUME THREE: MARKET & TEAM

    Energy Technology Data Exchange (ETDEWEB)

    Zuteck, Michael D. [Zimitar, Inc.; Jackson, Kevin L. [Zimitar, Inc.; Santos, Richard A. [Zimitar, Inc.

    2015-05-16

    The Zimitar one-piece rotor primary structure is integrated, so balanced thrust and gravity loads flow through the hub region without transferring out of its composite material. Large inner rotor geometry is used since there is no need to neck down to a blade root region and pitch bearing. Rotor control is provided by a highly redundant, five flap system on each blade, sized so that easily handled standard electric linear actuators are sufficient.

  10. A smart rotor configuration with linear quadratic control of adaptive trailing edge flaps for active load alleviation

    DEFF Research Database (Denmark)

    Bergami, Leonardo; Poulsen, Niels Kjølstad

    2015-01-01

    The paper proposes a smart rotor configuration where adaptive trailing edge flaps (ATEFs) are employed for active alleviation of the aerodynamic loads on the blades of the NREL 5 MW reference turbine. The flaps extend for 20% of the blade length and are controlled by a linear quadratic (LQ....... The effects of active flap control are assessed with aeroelastic simulations of the turbine in normal operation conditions, as prescribed by the International Electrotechnical Commission standard. The turbine lifetime fatigue damage equivalent loads provide a convenient summary of the results achieved...

  11. Low Speed and High Speed Correlation of SMART Active Flap Rotor Loads

    Science.gov (United States)

    Kottapalli, Sesi B. R.

    2010-01-01

    Measured, open loop and closed loop data from the SMART rotor test in the NASA Ames 40- by 80- Foot Wind Tunnel are compared with CAMRAD II calculations. One open loop high-speed case and four closed loop cases are considered. The closed loop cases include three high-speed cases and one low-speed case. Two of these high-speed cases include a 2 deg flap deflection at 5P case and a test maximum-airspeed case. This study follows a recent, open loop correlation effort that used a simple correction factor for the airfoil pitching moment Mach number. Compared to the earlier effort, the current open loop study considers more fundamental corrections based on advancing blade aerodynamic conditions. The airfoil tables themselves have been studied. Selected modifications to the HH-06 section flap airfoil pitching moment table are implemented. For the closed loop condition, the effect of the flap actuator is modeled by increased flap hinge stiffness. Overall, the open loop correlation is reasonable, thus confirming the basic correctness of the current semi-empirical modifications; the closed loop correlation is also reasonable considering that the current flap model is a first generation model. Detailed correlation results are given in the paper.

  12. Vibration reduction in helicopter rotors using an actively controlled partial span trailing edge flap located on the blade

    Science.gov (United States)

    Millott, T. A.; Friedmann, P. P.

    1994-01-01

    This report describes an analytical study of vibration reduction in a four-bladed helicopter rotor using an actively controlled, partial span, trailing edge flap located on the blade. The vibration reduction produced by the actively controlled flap (ACF) is compared with that obtained using individual blade control (IBC), in which the entire blade is oscillated in pitch. For both cases a deterministic feedback controller is implemented to reduce the 4/rev hub loads. For all cases considered, the ACF produced vibration reduction comparable with that obtained using IBC, but consumed only 10-30% of the power required to implement IBC. A careful parametric study is conducted to determine the influence of blade torsional stiffness, spanwise location of the control flap, and hinge moment correction on the vibration reduction characteristics of the ACF. The results clearly demonstrate the feasibility of this new approach to vibration reduction. It should be emphasized than the ACF, used together with a conventional swashplate, is completely decoupled from the primary flight control system and thus it has no influence on the airworthiness of the helicopter. This attribute is potentially a significant advantage when compared to IBC.

  13. Smart rotor modeling aero-servo-elastic modeling of a smart rotor with adaptive trailing edge flaps

    CERN Document Server

    Bergami, Leonardo

    2014-01-01

    A smart rotor is a wind turbine rotor that, through a combination of sensors, control units and actuators actively reduces the variation of the aerodynamic loads it has to withstand. Smart rotors feature?promising load alleviation potential and might provide the technological breakthrough required by the next generation of large wind turbine rotors.The book presents the aero-servo-elastic model of a smart rotor with Adaptive Trailing Edge Flaps for active load alleviation and provides an insight on the rotor aerodynamic, structural and control modeling. A novel model for the unsteady aerodynam

  14. Benchmarking aerodynamic prediction of unsteady rotor aerodynamics of active flaps on wind turbine blades using ranging fidelity tools

    Science.gov (United States)

    Barlas, Thanasis; Jost, Eva; Pirrung, Georg; Tsiantas, Theofanis; Riziotis, Vasilis; Navalkar, Sachin T.; Lutz, Thorsten; van Wingerden, Jan-Willem

    2016-09-01

    Simulations of a stiff rotor configuration of the DTU 10MW Reference Wind Turbine are performed in order to assess the impact of prescribed flap motion on the aerodynamic loads on a blade sectional and rotor integral level. Results of the engineering models used by DTU (HAWC2), TUDelft (Bladed) and NTUA (hGAST) are compared to the CFD predictions of USTUTT-IAG (FLOWer). Results show fairly good comparison in terms of axial loading, while alignment of tangential and drag-related forces across the numerical codes needs to be improved, together with unsteady corrections associated with rotor wake dynamics. The use of a new wake model in HAWC2 shows considerable accuracy improvements.

  15. Smart Rotor Modeling: Aero-Servo-Elastic Modeling of a Smart Rotor with Adaptive Trailing Edge Flaps

    DEFF Research Database (Denmark)

    Bergami, Leonardo

    This book presents the formulation of an aero-servo-elastic model for a wind turbine rotor equipped with Adaptive Trailing Edge Flaps (ATEF), a smart rotor configuration. As the name suggests, an aero-servo-elastic model consists of three main components: an aerodynamic model, a structural model......, and a control model. The book first presents an engineering type of aerodynamic model that accounts for the dynamic effects of flap deflection. The aerodynamic model is implemented in a Blade Element Momentum framework, and coupled with a multi-body structural model in the aero-servoelastic simulation code HAWC...... the trailing edge flap deflection to actively reduce the fatigue loads on the structure. The performance of the smart rotor configuration and its control algorithms are finally quantified by aero-servo-elastic simulations of the smart rotor turbine operating in a standard turbulent wind field....

  16. Simulations of a rotor with active deformable trailing edge flaps in half-wake inflow: Comparison of EllipSys 3D with HAWC2

    DEFF Research Database (Denmark)

    Barlas, Thanasis K.; Zahle, Frederik; Sørensen, Niels N.;

    2012-01-01

    . In this study, a comparison between aerodynamic predictions of the aeroelastic code HAWC2 and the Navier-Stokes code EllipSys3D for the NREL 5MW reference wind turbine rotor in a stiff configuration equipped with a deformable trailing edge flap is performed. A case where the half rotor plane experiences...... an inflow resembling the wake from an upstream wind turbine is investigated, which is appropriate for comparing the predictions of the two codes related to the abrupt aerodynamic response and the influence of the controllable flap. The trailing edge flap is actuated to alleviate the added loads from a non...

  17. Flap motion of helicopter rotors with novel, dynamic stall model

    Directory of Open Access Journals (Sweden)

    Han Wei

    2016-01-01

    Full Text Available In this paper, a nonlinear flapping equation for large inflow angles and flap angles is established by analyzing the aerodynamics of helicopter blade elements. In order to obtain a generalized flap equation, the Snel stall model was first applied to determine the lift coefficient of the helicopter rotor. A simulation experiment for specific airfoils was then conducted to verify the effectiveness of the Snel stall model as it applies to helicopters. Results show that the model requires no extraneous parameters compared to the traditional stall model and is highly accurate and practically applicable. Based on the model, the relationship between the flapping angle and the angle of attack was analyzed, as well as the advance ratio under the dynamic stall state.

  18. Development of a Wind Turbine Test Rig and Rotor for Trailing Edge Flap Investigation: Static Flap Angles Case

    Science.gov (United States)

    Abdelrahman, Ahmed; Johnson, David A.

    2014-06-01

    One of the strategies used to improve performance and increase the life-span of wind turbines is active flow control. It involves the modification of the aerodynamic characteristics of a wind turbine blade by means of moveable aerodynamic control surfaces. Trailing edge flaps are relatively small moveable control surfaces placed at the trailing edge of a blade's airfoil that modify the lift of a blade or airfoil section. An instrumented wind turbine test rig and rotor were specifically developed to enable a wide-range of experiments to investigate the potential of trailing edge flaps as an active control technique. A modular blade based on the S833 airfoil was designed to allow accurate instrumentation and customizable settings. The blade is 1.7 meters long, had a constant 178mm chord and a 6° pitch. The modular aerodynamic parts were 3D printed using plastic PC-ABS material. The blade design point was within the range of wind velocities in the available large test facility. The wind facility is a large open jet wind tunnel with a maximum velocity of 11m/s in the test area. The capability of the developed system was demonstrated through an initial study of the effect of stationary trailing edge flaps on blade load and performance. The investigation focused on measuring the changes in flapwise bending moment and power production for different trailing edge flap spanwise locations and deflection angles. The relationship between the load reduction and deflection angle was linear as expected from theory and the highest reduction was caused by the flap furthest from the rotor center. Overall, the experimental setup proved to be effective in measuring small changes in flapwise bending moment within the wind turbine blade and will provide insight when (active) flap control is targeted.

  19. High-fidelity linear time-invariant model of a smart rotor with adaptive trailing edge flaps

    DEFF Research Database (Denmark)

    Bergami, Leonardo; Hansen, Morten Hartvig

    2017-01-01

    aero-servo-elastic model support the design, systematic tuning and model synthesis of smart rotor control systems. As an example application, the gains of an individual flap controller are tuned using the Ziegler-Nichols method for the full-order poles. The flap controller is based on feedback...... of inverse Coleman transformed and low-pass filtered flapwise blade root moments to the cyclic flap angles through two proportional-integral controllers. The load alleviation potential of the active flap control, anticipated by the frequency response of the linear closed-loop model, is also confirmed by non...

  20. Random gust response statistics for coupled torsion-flapping rotor blade vibrations.

    Science.gov (United States)

    Gaonkar, G. H.; Hohenemser, K. H.; Yin, S. K.

    1972-01-01

    An analysis of coupled torsion-flapping rotor blade vibrations in response to atmospheric turbulence revealed that at high rotor advance ratios anticipated for future high speed pure or convertible rotorcraft both flapping and torsional vibrations can be severe. While appropriate feedback systems can alleviate flapping, they have little effect on torsion. Dynamic stability margins have also no substantial influence on dynamic torsion loads. The only effective means found to alleviate turbulence caused torsional vibrations and loads at high advance ratio was a substantial torsional stiffness margin with respect to local static torsional divergence of the retreating blade.

  1. CALCULATION OF HELICOPTER ROTOR FLAPPING ANGLES AND COMPARISON WITH MEASURED DATA

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Helicopter rotor flapping angles from hover to low-speed forward flight are calculated and compared with the measured data in this paper. The analytical method is based on a second order lifting-line/full-span free wake model as well as a fully coupled rotor trim model. It is shown that, in order to accurately predict the lateral flapping angle at low advance ratio, it is necessary to use free wake analysis to account for the highly non-uniform inflow induced by the distorted wake geometry at rotor disc plane.

  2. Design and performance prediction of swashplateless helicopter rotors with trailing edge flaps and tabs

    Science.gov (United States)

    Falls, Jaye

    This work studies the design of trailing edge controls for swashplateless helicopter primary control, and examines the impact of those controls on the performance of the rotor. The objective is to develop a comprehensive aeroelastic analysis for swashplateless rotors in steady level flight. The two key issues to be solved for this swashplateless control concept are actuation of the trailing edge controls and evaluating the performance of the swashplateless rotor compared to conventionally controlled helicopters. Solving the first requires simultaneous minimization of trailing flap control angles and hinge moments to reduce actuation power. The second issue requires not only the accurate assessment of swashplateless rotor power, but also similar or improved performance compared to conventional rotors. The analysis consists of two major parts, the structural model and the aerodynamic model. The inertial contributions of the trailing edge flap and tab are derived and added to the system equations in the structural model. Two different aerodynamic models are used in the analysis, a quasi-steady thin airfoil theory that includes arbitrary hinge positions for the flap and the tab, and an unsteady lifting line model with airfoil table lookup based on wind tunnel test data and computational fluid dynamics simulation. The design aspect of the problem is investigated through parametric studies of the trailing edge flap and tab for a Kaman-type conceptual rotor and a UH-60A swashplateless variant. The UH-60A model is not changed except for the addition of a trailing edge flap to the rotor blade, and the reduction of pitch link stiffness to imitate a soft root spring. Study of the uncoupled blade response identifies torsional stiffness and flap hinge stiffness as important design features of the swashplateless rotor. Important trailing edge flap and tab design features including index angle, aerodynamic overhang, chord and length are identified through examination of coupled

  3. Primary control of a Mach scale swashplateless rotor using brushless DC motor actuated trailing edge flaps

    Science.gov (United States)

    Saxena, Anand

    The focus of this research was to demonstrate a four blade rotor trim in forward flight using integrated trailing edge flaps instead of using a swashplate controls. A compact brushless DC motor was evaluated as an on-blade actuator, with the possibility of achieving large trailing edge flap amplitudes. A control strategy to actuate the trailing edge flap at desired frequency and amplitude was developed and large trailing edge flap amplitudes from the motor (instead of rotational motion) were obtained. Once the actuator was tested on the bench-top, a lightweight mechanism was designed to incorporate the motor in the blade and actuate the trailing edge flaps. A six feet diameter, four bladed composite rotor with motor-flap system integrated into the NACA 0012 airfoil section was fabricated. Systematic testing was carried out for a range of load conditions, first in the vacuum chamber followed by hover tests. Large trailing edge flap deflections were observed during the hover testing, and a peak to peak trailing edge flap amplitude of 18 degree was achieved at 2000 rotor RPM with hover tip Mach number of 0.628. A closed loop controller was designed to demonstrate trailing edge flap mean position and the peak to peak amplitude control. Further, a soft pitch link was designed and fabricated, to replace the stiff pitch link and thereby reduce the torsional stiffness of the blade to 2/rev. This soft pitch link allowed for blade root pitch motion in response to the trailing edge flap inputs. Blade pitch response due to both steady as well as sinusoidal flap deflections were demonstrated. Finally, tests were performed in Glenn L. Martin wind tunnel using a model rotor rig to assess the performance of motor-flap system in forward flight. A swashplateless trim using brushless DC motor actuated trailing edge flaps was achieved for a rotor operating at 1200 RPM and an advance ratio of 0.28. Also, preliminary exploration was carried out to test the scalability of the motor

  4. Power performance optimization and loads alleviation with active flaps using individual flap control

    Science.gov (United States)

    Pettas, Vasilis; Barlas, Thanasis; Gertz, Drew; Madsen, Helge A.

    2016-09-01

    The present article investigates the potential of Active Trailing Edge Flaps (ATEF) in terms of increase in annual energy production (AEP) as well as reduction of fatigue loads. The basis for this study is the DTU 10 MW Reference Wind Turbine (RWT) simulated using the aeroelastic code HAWC2. In an industrial-oriented manner the baseline rotor is upscaled by 5% and the ATEFs are implemented in the outer 30% of the blades. The flap system is kept simple and robust with a single flap section and control with wind speed, rotor azimuth, root bending moments and angle of attack in flap's mid-section being the sensor inputs. The AEP is increased due to the upscaling but also further due to the flap system while the fatigue loads in components of interest (blade, tower, nacelle and main bearing) are reduced close to the level of the original turbine. The aim of this study is to demonstrate a simple and applicable method that can be a technology enabler for rotor upscaling and lowering cost of energy.

  5. Active control for performance enhancement of electrically controlled rotor

    Institute of Scientific and Technical Information of China (English)

    Lu Yang; Wang Chao

    2015-01-01

    Electrically controlled rotor (ECR) system has the potential to enhance the rotor perfor-mance by applying higher harmonic flap inputs. In order to explore the feasibility and effectiveness for ECR performance enhancement using closed-loop control method, firstly, an ECR rotor perfor-mance analysis model based on helicopter flight dynamic model is established, which can reflect the performance characteristics of ECR helicopter at high advance ratio. Based on the simulation platform, an active control method named adaptive T-matrix algorithm is adopted to explore the feasibility and effectiveness for ECR performance enhancement. The simulation results verify the effectiveness of this closed-loop control method. For the sample ECR helicopter, about 3%rotor power reduction is obtained with the optimum 2/rev flap inputs at the advance ratio of 0.34. And through analyzing the distributions of attack of angle and drag in rotor disk, the underlying physical essence of ECR power reduction is cleared. Furthermore, the influence of the key control parameters, including convergence factor and weighting matrix, on the effectiveness of closed-loop control for ECR performance enhancement is explored. Some useful results are summarized, which can be used to direct the future active control law design of ECR performance enhancement.

  6. Active Control of Long Bridges Using Flaps

    DEFF Research Database (Denmark)

    Hansen, H. I.; Thoft-Christensen, Palle

    The main problem in designing ultra-long span suspension bridges is flutter. A solution to this problem might be to introduce an active flap control system to increase the flutter wind velocity. The investigated flap control system consists of flaps integrated in the bridge girder so each flap...... is the streamlined part of the edge of the girder. Additional aerodynamic derivatives are shown for the flaps and it is shown how methods already developed can be used to estimate the flutter wind velocity for a bridge section with flaps. As an example, the flutter wind velocity is calculated for different flap...... configurations for a bridge section model by using aerodynamic derivatives for a flat plate. The example shows that different flap configurations can either increase or decrease the flutter wind velocity. for optimal flap configurations flutter will not occur....

  7. An experimental and analytical investigation of isolated rotor flap-lag stability in forward flight

    Science.gov (United States)

    Gaonkar, Gopal H.; Mcnulty, Michael J.; Nagabhushanam, J.

    1990-01-01

    The flap-lag stability of an isolated hingeless rotor is investigated, both experimentally and analytically, in hover and in forward flight. The effects of forward flight aerodynamics on regressing lead-lag mode stability are the focus of the investigation. The soft-inplane, three-bladed, isolated model rotor was operated untrimmed at advance ratios from hover to 0.55 and at shaft angles as high as 20 deg. The experimental data base includes forward flight damping data for two lead-lag natural frequencies, for three values of collective pitch, and for both zero and full-lag structural coupling. With the aid of computerized symbolic manipulation, a rigid-blade lag-flap model analysis was developed to calculate the Floquent eigenvalues and to identify the modes. Good correlation is shown for some cases, but other cases show large discrepancies between the theory and experiment.

  8. Aeromechanical Evaluation of Smart-Twisting Active Rotor

    Science.gov (United States)

    Lim, Joon W.; Boyd, D. Douglas, Jr.; Hoffman, Frauke; van der Wall, Berend G.; Kim, Do-Hyung; Jung, Sung N.; You, Young H.; Tanabe, Yasutada; Bailly, Joelle; Lienard, Caroline; Delrieux, Yves

    2014-01-01

    An investigation of Smart-Twisting Active Rotor (STAR) was made to assess potential benefits of the current active twist rotor concept for performance improvement, vibration reduction, and noise alleviation. The STAR rotor is a 40% Mach-scaled, Bo105 rotor with an articulated flap-lag hinge at 3.5%R and no pre-cone. The 0-5 per rev active twist harmonic inputs were applied for various flight conditions including hover, descent, moderate to high speed level flights, and slowed rotor high advance ratio. For the analysis, the STAR partners used multiple codes including CAMRAD II, S4, HOST, rFlow3D, elsA, and their associated software. At the high thrust level in hover, the 0 per rev active twist with 80% amplitude increased figure of merit (FM) by 0.01-0.02 relative to the baseline. In descent, the largest BVI noise reduction was on the order of 2 to 5 dB at the 3 per rev active twist. In the high speed case (mu = 0.35), the 2 per rev actuation was found to be the most effective in achieving a power reduction as well as a vibration reduction. At the 2 per rev active twist, total power was reduced by 0.65% at the 60 deg active twist phase, and vibration was reduced by 47.6% at the 45 deg active twist phase. The use of the 2 per rev active twist appears effective for vibration reduction. In the high advance ratio case (mu = 0.70), the 0 per rev actuation appeared to have negligible impact on performance improvement. In summary, computational simulations successfully demonstrated that the current active twist concept provided a significant reduction of the maximum BVI noise in descent, a significant reduction of the vibration in the high speed case, a small improvement on rotor performance in hover, and a negligible impact on rotor performance in forward flight.

  9. Effects of a trailing edge flap on the aerodynamics and acoustics of rotor blade-vortex interactions

    Science.gov (United States)

    Charles, B. D.; Tadghighi, H.; Hassan, A. A.

    1992-01-01

    The use of a trailing edge flap on a helicopter rotor has been numerically simulated to determine if such a device can mitigate the acoustics of blade vortex interactions (BVI). The numerical procedure employs CAMRAD/JA, a lifting-line helicopter rotor trim code, in conjunction with RFS2, an unsteady transonic full-potential flow solver, and WOPWOP, an acoustic model based on Farassat's formulation 1A. The codes were modified to simulate trailing edge flap effects. The CAMRAD/JA code was used to compute the far wake inflow effects and the vortex wake trajectories and strengths which are utilized by RFS2 to predict the blade surface pressure variations. These pressures were then analyzed using WOPWOP to determine the high frequency acoustic response at several fixed observer locations below the rotor disk. Comparisons were made with different flap deflection amplitudes and rates to assess flap effects on BVI. Numerical experiments were carried out using a one-seventh scale AH-1G rotor system for flight conditions simulating BVI encountered during low speed descending flight with and without flaps. Predicted blade surface pressures and acoustic sound pressure levels obtained have shown good agreement with the baseline no-flap test data obtained in the DNW wind tunnel. Numerical results indicate that the use of flaps is beneficial in reducing BVI noise.

  10. Design study of a feedback control system for the Multicyclic Flap System rotor (MFS)

    Science.gov (United States)

    Weisbrich, R.; Perley, R.; Howes, H.

    1977-01-01

    The feasibility of automatically providing higher harmonic control to a deflectable control flap at the tip of a helicopter rotor blade through feedback of selected independent parameter was investigated. Control parameters were selected for input to the feedback system. A preliminary circuit was designed to condition the selected parameters, weigh limiting factors, and provide a proper output signal to the multi-cyclic control actuators. Results indicate that feedback control for the higher harmonic is feasible; however, design for a flight system requires an extension of the present analysis which was done for one flight condition - 120 kts, 11,500 lbs gross weight and level flight.

  11. Development of a resonant trailing-edge flap actuation system for helicopter rotor vibration control

    Science.gov (United States)

    Kim, J.-S.; Wang, K. W.; Smith, E. C.

    2007-12-01

    A resonant trailing-edge flap actuation system for helicopter rotors is developed and evaluated experimentally. The concept involves deflecting each individual trailing-edge flap using a compact resonant piezoelectric actuation system. Each resonant actuation system yields high authority, while operating at a single frequency. By tailoring the natural frequencies of the actuation system (including the piezoelectric actuator and the related mechanical and electrical elements) to the required operating frequencies, one can increase the output authority. The robustness of the device can be enhanced by increasing the high authority bandwidth through electric circuitry design. Such a resonant actuation system (RAS) is analyzed for a full-scale piezoelectric induced-shear tube actuator, and bench-top testing is conducted to validate the concept. An adaptive feed-forward controller is developed to realize the electric network dynamics and adapt to phase variation. The control strategy is then implemented via a digital signal processor (DSP) system. Analysis is also performed to examine the rotor system dynamics in forward flight with piezoelectric resonant actuators, using a perturbation method to evaluate the system's time-varying characteristics. Numerical simulations reveal that the resonant actuator concept can be applied to forward flights as well as to hover conditions.

  12. Wind tunnel testing of a full scale helicopter blade section with an upstream active Gurney flap

    NARCIS (Netherlands)

    Loendersloot, R.; Freire Gomez, J.; Booker, J.D.

    2014-01-01

    Wind tunnel tests were performed on an aerofoil section comparable to that of a full scale helicopter blade section with an upstream active Gurney flap in the framework of the European project CleanSky ITD Green RotorCraft. A modified NACA0012 profile was used, with 23 Kulite pressure transducers em

  13. Design and development of an active Gurney flap for rotorcraft

    Science.gov (United States)

    Freire Gómez, Jon; Booker, Julian D.; Mellor, Phil H.

    2013-03-01

    The EU's Green Rotorcraft programme will develop an Active Gurney Flap (AGF) for a full-scale helicopter main rotor blade as part of its `smart adaptive rotor blade' technology demonstrators. AGFs can be utilized to provide a localized and variable lift enhancement on the rotor, enabling a redistribution of loading on the rotor blade around the rotor azimuth. Further advantages include the possibility of using AGFs to allow a rotor speed reduction, which subsequently provides acoustic benefits. Designed to be integrable into a commercial helicopter blade, and thereby capable of withstanding real in-flight centrifugal loading, blade vibrations and aerodynamic loads, the demonstrator is expected to achieve a high technology readiness level (TRL). The AGF will be validated initially by a constant blade section 2D wind tunnel test and latterly by full blade 3D whirl tower testing. This paper presents the methodology adopted for the AGF concept topology selection, based on a series of both qualitative and quantitative performance criteria. Two different AGF candidate mechanisms are compared, both powered by a small commercial electromagnetic actuator. In both topologies, the link between the actuator and the control surface consists of two rotating torque bars, pivoting on flexure bearings. This provides the required reliability and precision, while making the design virtually frictionless. The engineering analysis presented suggests that both candidates would perform satisfactorily in a 2D wind tunnel test, but that equally, both have design constraints which limit their potential to be further taken into a whirl tower test under full scale centrifugal and inertial loads.

  14. Active Flow Control on Bidirectional Rotors for Tidal MHK Applications

    Energy Technology Data Exchange (ETDEWEB)

    Shiu, Henry [Research Engineer; van Dam, Cornelis P. [Professor

    2013-08-22

    A marine and hydrokinetic (MHK) tidal turbine extracts energy from tidal currents, providing clean, sustainable electricity generation. In general, all MHK conversion technologies are confronted with significant operational hurdles, resulting in both increased capital and operations and maintenance (O&M) costs. To counter these high costs while maintaining reliability, MHK turbine designs can be simplified. Prior study found that a tidal turbine could be cost-effectively simplified by removing blade pitch and rotor/nacelle yaw. Its rotor would run in one direction during ebb and then reverse direction when the current switched to flood. We dubbed such a turbine a bidirectional rotor tidal turbine (BRTT). The bidirectional hydrofoils of a BRTT are less efficient than conventional hydrofoils and capture less energy, but the elimination of the pitch and yaw systems were estimated to reduce levelized cost of energy by 7.8%-9.6%. In this study, we investigated two mechanisms for recapturing some of the performance shortfall of the BRTT. First, we developed a novel set of hydrofoils, designated the yy series, for BRTT application. Second, we investigated the use of active flow control via microtabs. Microtabs are small deployable/retractable tabs, typically located near the leading or trailing edge of an air/hydrofoil with height on the order of the boundary layer thickness (1% - 2% of chord). They deploy approximately perpendicularly to the foil surface and, like gurney flaps and plain flaps, globally affect the aerodynamics of the airfoil. By strategically placing microtabs and selectively deploying them based on the direction of the inflow, performance of a BRTT rotor can be improved while retaining bidirectional operation. The yy foils were computationally designed and analyzed. They exhibited better performance than the baseline bidirectional foil, the ellipse. For example, the yyb07cn-180 had 14.7% higher (l/d)max than an ellipse of equal thickness. The yyb07cn

  15. Aeroelastic Optimization of a 10 MW Wind Turbine Blade with Active Trailing Edge Flaps

    DEFF Research Database (Denmark)

    Barlas, Athanasios; Tibaldi, Carlo; Zahle, Frederik;

    2016-01-01

    This article presents the aeroelastic optimization of a 10MW wind turbine ‘smart blade’ equipped with active trailing edge flaps. The multi-disciplinary wind turbine analysis and optimization tool HawtOpt2 is utilized, which is based on the open-source framework Open-MDAO. The tool interfaces...... to several state-of-the art simulation codes, allowing for a wide variety of problem formulations and combinations of models. A simultaneous aerodynamic and structural optimization of a 10 MW wind turbine rotor is carried out with respect to material layups and outer shape. Active trailing edge flaps...

  16. ANALYSIS OF AN ELECTROSTRICTIVE STACK ACTUATORFOR ACTIVE TRAILING EDGE FLAPS

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Helicopter is a complex dynamic system with many rotating components. The rotor blades operate in a highly complex aerodynamic environment. The vibratory hub load, which is caused by cyclic variation of centrifugal and aerodynamic load of the rotating blades in flight, is transmitted to the fuselage, resulting in serious vibration and noise of the structure. It is one of the most important exciting sources in helicopters.  There has long been a desire to reduce helicopter vibration and to improve its performance. Control schemes adopted so far can be classified as either passive or active control technologies. The passive technologies include optimization of rotor hub, blade and the fuselage, hub or blade mounted passive vibration absorbers and anti-resonant vibration isolators. One of the major disadvantages with passive technologies is that they are designed to provide maximum vibration reduction at a specific frequency; therefore, their performance is degraded significantly with changes in the operating conditions of the rotor system.  With the development of computer science and active control technology, increasing efforts have been devoted to active control technologies to benefit helicopter vibration suppression in recent years. Earlier studies include Higher Harmonic Control (HHC)[1] and Individual Blade Control (IBC)[2], which is aimed to reduce the vibratory blade load by oscillating the blade in pitch motion using hydraulic actuators. It is successful in suppressing the vibration of the fuselage; however, its application is limited by serious energy consumption.  To overcome these difficulties, a new concept in helicopter vibration control is the smart rotor system. In this scheme, actuators are embedded in composite blades. They are used to activate the trailing edge flaps in higher harmonic pitch motion to adjust the lift force actively. Under the regulation of a control system, the vibratory hub load can be counteracted actively at

  17. Extreme load alleviation using industrial implementation of active trailing edge flaps in a full design load basis

    Science.gov (United States)

    Barlas, Thanasis; Pettas, Vasilis; Gertz, Drew; Madsen, Helge A.

    2016-09-01

    The application of active trailing edge flaps in an industrial oriented implementation is evaluated in terms of capability of alleviating design extreme loads. A flap system with basic control functionality is implemented and tested in a realistic full Design Load Basis (DLB) for the DTU 10MW Reference Wind Turbine (RWT) model and for an upscaled rotor version in DTU's aeroelastic code HAWC2. The flap system implementation shows considerable potential in reducing extreme loads in components of interest including the blades, main bearing and tower top, with no influence on fatigue loads and power performance. In addition, an individual flap controller for fatigue load reduction in above rated power conditions is also implemented and integrated in the general controller architecture. The system is shown to be a technology enabler for rotor upscaling, by combining extreme and fatigue load reduction.

  18. Rotor Vibration Reduction via Active Hybrid Bearings

    DEFF Research Database (Denmark)

    Nicoletti, Rodrigo; Santos, Ilmar

    2002-01-01

    The use of fluid power to reduce and control rotor vibration in rotating machines is investigated. An active hybrid bearing is studied, whose main objective is to reduce wear and vibration between rotating and stationary machinery parts. By injecting pressurised oil into the oil film, through...... orifices machined in the bearing pads, one can alter the machine dynamic characteristics, thus enhancing its operational range. A mathematical model of the rotor-bearing system, as well as of the hydraulic system, is presented. Numerical results of the system frequency response show good agreement...

  19. Structural and mechanism design of an active trailing-edge flap blade

    DEFF Research Database (Denmark)

    Lee, Jae Hwan; Natarajan, Balakumaran; Eun, Won Jong

    2013-01-01

    of excessive hub vibratory loads and noise. The active control device manipulates the blade pitch angle with arbitrary higher harmonic frequencies individually. In this paper, an active trailing-edge flap blade, which is one of the active control methods, is developed to reduce vibratory loads and noise...... of the rotor through modification of unsteady aerodynamic loads. Piezoelectric actuators installed inside the blade manipulate the motion of the trailing edge flap. The proposed blade rotates at higher speed and additional structures are included to support the actuators and the flap. This improves the design......, as the blade is able to withstand increased centrifugal force. The cross-section of the active blade is designed first. A stress/strain recovery analysis is then conducted to verify its structural integrity. A one-dimensional beam analysis is also carried out to assist with the construction of the fan diagram...

  20. Extreme load alleviation using industrial implementation of active trailing edge flaps in a full design load basis

    DEFF Research Database (Denmark)

    Barlas, Athanasios; Pettas, Vasilis; Gertz, Drew Patrick

    2016-01-01

    The application of active trailing edge flaps in an industrial oriented implementation is evaluated in terms of capability of alleviating design extreme loads. A flap system with basic control functionality is implemented and tested in a realistic full Design Load Basis (DLB) for the DTU 10MW...... Reference Wind Turbine (RWT) model and for an upscaled rotor version in DTU's aeroelastic code HAWC2. The flap system implementation shows considerable potential in reducing extreme loads in components of interest including the blades, main bearing and tower top, with no influence on fatigue loads and power...

  1. Wind Turbine Rotors with Active Vibration Control

    DEFF Research Database (Denmark)

    Svendsen, Martin Nymann

    are assumed to be proportional to the relative inflow angle, which also gives a linear form with equivalent stiffness and damping terms. Geometric stiffness effects including the important stiffening from tensile axial stresses in equilibrium with centrifugal forces are included via an initial stress......This thesis presents a framework for structural modeling, analysis and active vibration damping of rotating wind turbine blades and rotors. A structural rotor model is developed in terms of finite beam elements in a rotating frame of reference. The element comprises a representation of general...... formulation. The element provides an accurate representation of the eigenfrequencies and whirling modes of the gyroscopic system, and identifies lightly damped edge-wise modes. By adoption of a method for active, collocated resonant vibration of multi-degree-of-freedom systems it is demonstrated...

  2. Effect of Smart Rotor Control Using a Deformable Trailing Edge Flap on Load Reduction under Normal and Extreme Turbulence

    Directory of Open Access Journals (Sweden)

    Jian Zhong Xu

    2012-09-01

    Full Text Available This paper presents a newly developed aero-servo-elastic platform for implementing smart rotor control and shows its effectiveness with aerodynamic loads on large-scale offshore wind turbines. The platform was built by improving the FAST/Aerodyn codes with the integration of an external deformable trailing edge flap controller in the Matlab/Simulink software. Smart rotor control was applied to an Upwind/NREL 5 MW reference wind turbine under various operating wind conditions in accordance with the IEC Normal Turbulence Model (NTM and Extreme Turbulence Model (ETM. Results showed that, irrespective of whether the NTM or ETM case was considered, aerodynamic load in terms of blade flapwise root moment and tip deflection were effectively reduced. Furthermore, the smart rotor control also positively affected generator power, pitch system and tower load. These results laying a foundation for a future migration of the “smart rotor control” concept into the design of large-scale offshore wind turbines.

  3. Design optimization for active twist rotor blades

    Science.gov (United States)

    Mok, Ji Won

    This dissertation introduces the process of optimizing active twist rotor blades in the presence of embedded anisotropic piezo-composite actuators. Optimum design of active twist blades is a complex task, since it involves a rich design space with tightly coupled design variables. The study presents the development of an optimization framework for active helicopter rotor blade cross-sectional design. This optimization framework allows for exploring a rich and highly nonlinear design space in order to optimize the active twist rotor blades. Different analytical components are combined in the framework: cross-sectional analysis (UM/VABS), an automated mesh generator, a beam solver (DYMORE), a three-dimensional local strain recovery module, and a gradient based optimizer within MATLAB. Through the mathematical optimization problem, the static twist actuation performance of a blade is maximized while satisfying a series of blade constraints. These constraints are associated with locations of the center of gravity and elastic axis, blade mass per unit span, fundamental rotating blade frequencies, and the blade strength based on local three-dimensional strain fields under worst loading conditions. Through pre-processing, limitations of the proposed process have been studied. When limitations were detected, resolution strategies were proposed. These include mesh overlapping, element distortion, trailing edge tab modeling, electrode modeling and foam implementation of the mesh generator, and the initial point sensibility of the current optimization scheme. Examples demonstrate the effectiveness of this process. Optimization studies were performed on the NASA/Army/MIT ATR blade case. Even though that design was built and shown significant impact in vibration reduction, the proposed optimization process showed that the design could be improved significantly. The second example, based on a model scale of the AH-64D Apache blade, emphasized the capability of this framework to

  4. A comparison of smart rotor control approaches using trailing edge flaps and individual pitch control

    NARCIS (Netherlands)

    Lackner, M.A.; van Kuik, G.A.M.

    2009-01-01

    Modern wind turbines have been steadily increasing in size, and have now become very large, with recent models boasting rotor diameters greater than 120 m. Reducing the loads experienced by the wind turbine rotor blades is one means of lowering the cost of energy of wind turbines. Wind turbines are

  5. Stall Inception Process and Prospects for Active Hub-Flap Control in Three-Stage Axial Flow Compressor

    Institute of Scientific and Technical Information of China (English)

    Tomoya OKADA; Atsushi KAWAJIRI; Yutaka OHTA; Eisuke OUTA

    2008-01-01

    The possibility to apply the active hub-flap control method, which is a proven rotating stall control method for a single-stage compressor, to a 3-stage axial compressor is experimentally discussed, where complex rotating stall inception processes ate observed. The research compressor is a 3-stage one and could change the stagger angle settings for rotor blades and stator vanes. Sixteen rotor blade/stator vane configuration patterns were tested by changing stagger angle for the stator vanes. By measurement of surface-pressure fluctuation, stall inception proc-esses are investigated and the measured pressure fluctuation data is used as a predictive signal for rotating stall. The experimental results show that the stall detection system applied to active hub-flap control in a single-stage compressor could be usefully applied to that in a 3-stage compressor with a more complex stall inception process.

  6. Sizing and Control of Trailing Edge Flaps on a Smart Rotor for Maximum Power Generation in Low Fatigue Wind Regimes

    DEFF Research Database (Denmark)

    Smit, Jeroen; Berghammer, Lars O.; Navalkar, Sachin;

    2014-01-01

    In this paper an extension of the spectrum of applicability of rotors with active aerody-namic devices is presented. Besides the classical purpose of load alleviation, a secondary objective is established: power capture optimization. As a _rst step, wind speed regions that contribute little...

  7. Sizing and control of trailing edge flaps on a smart rotor for maximum power generation in low fatigue wind regimes

    DEFF Research Database (Denmark)

    Smit, Jeroen; Bernhammer, Lars O.; Navalkar, Sachin T.;

    2016-01-01

    An extension of the spectrum of applicability of rotors with active aerodynamic devices is presented in this paper. Besides the classical purpose of load alleviation, a secondary objective is established: optimization of power capture. As a first step, wind speed regions that contribute little...

  8. Toward comparing experiment and theory for corroborative research on hingeless rotor stability in forward flight (an experimental and analytical investigation of isolated rotor-flap-lag stability in forward flight)

    Science.gov (United States)

    Gaonkar, G.

    1986-01-01

    For flap-lag stability of isolated rotors, experimental and analytical investigations are conducted in hover and forward flight on the adequacy of a linear quasisteady aerodynamics theory with dynamic inflow. Forward flight effects on lag regressing mode are emphasized. Accordingly, a soft inplane hingeless rotor with three blades is tested at advance ratios as high as 0.55 and at shaft angles as high as 20 degrees. The 1.62 m model rotor is untrimmed with an essentially unrestricted tilt of the tip path plane. In combination with lag natural frequencies, collective pitch settings and flap-lag coupling parameters, the data base comprises nearly 1200 test points (damping and frequency) in forward flight and 200 test points in hover. By computerized symbolic manipulation, a linear analytical model is developed in substall to predict stability margins with mode identificaton. To help explain the correlation between theory and data it also predicts substall and stall regions of the rotor disk from equilibrium values. The correlation shows both the strengthts and weaknesses of the theory in substall.

  9. Active damping of flexible rotor blade dynamics using electrorheological-fluid-based actuators

    Science.gov (United States)

    Wereley, Norman M.

    1994-05-01

    Advanced rotor systems including hingeless and bearingless rotors have air and ground resonance instabilities due to coalescence of low-frequency rotor modes with landing gear and fuselage modes, respectively. This coalescence is of difficulty due to the direct connection of the rotor blade in these advanced rotor systems to the rotor hub using a flexure or flexbeam. We are currently exploring the mitigation of this modal coalescence through the use of active damping techniques and electro-rheological fluid technology.

  10. Power performance optimization and loads alleviation with active flaps using individual flap control

    DEFF Research Database (Denmark)

    Pettas, Vasilis; Barlas, Athanasios; Gertz, Drew Patrick;

    2016-01-01

    The present article investigates the potential of Active Trailing Edge Flaps (ATEF) in terms of increase in annual energy production (AEP) as well as reduction of fatigue loads. The basis for this study is the DTU 10 MW Reference Wind Turbine (RWT) simulated using the aeroelastic code HAWC2...... the sensor inputs. The AEP is increased due to the upscaling but also further due to the flap system while the fatigue loads in components of interest (blade, tower, nacelle and main bearing) are reduced close to the level of the original turbine. The aim of this study is to demonstrate a simple...

  11. Robust stabilization of rotor-active magnetic bearing systems

    Science.gov (United States)

    Li, Guoxin

    Active magnetic bearings (AMBs) are emerging as a beneficial technology for high-speed and high-performance suspensions in rotating machinery applications. A fundamental feedback control problem is robust stabilization in the presence of uncertain destabilizing mechanisms in aeroelastic, hydroelastic dynamics, and AMB feedback. As rotating machines are evolving in achieving high speed, high energy density, and high performance, the rotor and the support structure become increasingly flexible, and highly coupled. This makes rotor-AMB system more challenging to stabilize. The primary objective of this research is to develop a systematic control synthesis procedure for achieving highly robust stabilization of rotor-AMB systems. Of special interest is the stabilization of multivariable systems such as the AMB supported flexible rotors and gyroscopic rotors, where the classical control design may encounter difficulties. To this end, we first developed a systematic modeling procedure. This modeling procedure exploited the best advantages of technology developed in rotordynamics and the unique system identification tool provided by the AMBs. A systematic uncertainty model for rotor-AMB systems was developed, eliminating the iterative process of selecting uncertainty structures. The consequences of overestimation or underestimation of uncertainties were made transparent to control engineers. To achieve high robustness, we explored the fundamental performance/robustness limitations due to rotor-AMB system unstable poles. We examined the mixed sensitivity performance that is closely related to the unstructured uncertainty. To enhance transparency of the synthesis, we analyzed multivariable controllers from classical control perspectives. Based on these results, a systematic robust control synthesis procedure was established. For a strong gyroscopic rotor over a wide speed range, we applied the advanced gain-scheduled synthesis, and compared two synthesis frameworks in

  12. Blade tip vortex measurements on actively twisted rotor blades

    Science.gov (United States)

    Bauknecht, André; Ewers, Benjamin; Schneider, Oliver; Raffel, Markus

    2017-05-01

    Active rotor control concepts, such as active twist actuation, have the potential to effectively reduce the noise and vibrations of helicopter rotors. The present study focuses on the experimental investigation of active twist for the reduction of blade-vortex interaction (BVI) effects on a model rotor. Results of a large-scale smart-twisting active rotor test under hover conditions are described. This test investigated the effects of individual blade twist control on the blade tip vortices. The rotor blades were actuated with peak torsion amplitudes of up to 2° and harmonic frequencies of 1-5/rev with different phase angles. Time-resolved stereoscopic particle image velocimetry was carried out to study the effects of active twist on the strength and trajectories of the tip vortices between ψ _ {v}= 3.6° and 45.7° of vortex age. The analysis of the vortex trajectories revealed that the 1/rev active twist actuation mainly caused a vertical deflection of the blade tip and the corresponding vortex trajectories of up to 1.3% of the rotor radius R above and -1%R below the unactuated condition. An actuation with frequencies of 2 and 3/rev significantly affected the shapes of the vortex trajectories and caused negative vertical displacements of the vortices relative to the unactuated case of up to 2%R within the first 35° of wake age. The 2 and 3/rev actuation also had the most significant effects on the vortex strength and altered the initial peak swirl velocity by up to -34 and +31% relative to the unactuated value. The present aerodynamic investigation reveals a high control authority of the active twist actuation on the strength and trajectories of the trailing blade tip vortices. The magnitude of the evoked changes indicates that the active twist actuation constitutes an effective measure for the mitigation of BVI-induced noise on helicopters.

  13. Design of the Active Elevon Rotor for Low Vibration

    Science.gov (United States)

    Fulton, Mark V.; Rutkowski, Michael (Technical Monitor)

    2000-01-01

    Helicopter fuselages vibrate more than desired, and traditional solutions have limited effectiveness and can impose an appreciable weight penalty. Alternative methods of combating high vibration, including Higher Harmonic Control (HHC) via harmonic swashplate motion and Individual Blade Control (IBC) via active pitch links, have been studied for several decades. HHC via an on-blade control surface was tested in 1977 on a full scale rotor using a secondary active swashplate and a mechanical control system. Recent smart material advances have prompted new research into the use of on-blade control concepts. Recent analytical studies have indicated that the use of on-blade control surfaces produces vibration reduction comparable to swashplate-based HHC but for less power. Furthermore, smart materials (such as piezoceramics) have been shown to provide sufficient control authority for preliminary rotor experiments. These experiments were initially performed at small scale for reduced tip speeds. More recent experiments have been conducted at or near full tip speeds, and a full-scale active rotor is under development by Boeing with Eurocopter et al. pursuing a similarly advanced full-scale implementation. The US Army Aeroflightdynamics Directorate has undertaken a new research program called the Active Elevon Rotor (AER) Focus Demo. This program includes the design, fabrication, and wind. tunnel testing of a four-bladed, 12.96 ft diameter rotor with one or two on-blade elevons per blade. The rotor, which will be Mach scaled, will use 2-5/rev elevon motion for closed-loop control and :will be tested in late 2001. The primary goal of the AER Focus Demo is the reduction of vibratory hub loads by 80% and the reduction of vibratory blade structural loads. A secondary goal is the reduction of rotor power. The third priority is the measurement and possible reduction of Blade Vortex Interaction (BVI) noise. The present study is focused on elevon effectiveness, that is, the elevon

  14. Smart helicopter rotors optimization and piezoelectric vibration control

    CERN Document Server

    Ganguli, Ranjan; Viswamurthy, Sathyamangalam Ramanarayanan

    2016-01-01

    Exploiting the properties of piezoelectric materials to minimize vibration in rotor-blade actuators, this book demonstrates the potential of smart helicopter rotors to achieve the smoothness of ride associated with jet-engined, fixed-wing aircraft. Vibration control is effected using the concepts of trailing-edge flaps and active-twist. The authors’ optimization-based approach shows the advantage of multiple trailing-edge flaps and algorithms for full-authority control of dual trailing-edge-flap actuators are presented. Hysteresis nonlinearity in piezoelectric stack actuators is highlighted and compensated by use of another algorithm. The idea of response surfaces provides for optimal placement of trailing-edge flaps. The concept of active twist involves the employment of piezoelectrically induced shear actuation in rotating beams. Shear is then demonstrated for a thin-walled aerofoil-section rotor blade under feedback-control vibration minimization. Active twist is shown to be significant in reducing vibra...

  15. Boeing Smart Rotor Full-scale Wind Tunnel Test Data Report

    Science.gov (United States)

    Kottapalli, Sesi; Hagerty, Brandon; Salazar, Denise

    2016-01-01

    A full-scale helicopter smart material actuated rotor technology (SMART) rotor test was conducted in the USAF National Full-Scale Aerodynamics Complex 40- by 80-Foot Wind Tunnel at NASA Ames. The SMART rotor system is a five-bladed MD 902 bearingless rotor with active trailing-edge flaps. The flaps are actuated using piezoelectric actuators. Rotor performance, structural loads, and acoustic data were obtained over a wide range of rotor shaft angles of attack, thrust, and airspeeds. The primary test objective was to acquire unique validation data for the high-performance computing analyses developed under the Defense Advanced Research Project Agency (DARPA) Helicopter Quieting Program (HQP). Other research objectives included quantifying the ability of the on-blade flaps to achieve vibration reduction, rotor smoothing, and performance improvements. This data set of rotor performance and structural loads can be used for analytical and experimental comparison studies with other full-scale rotor systems and for analytical validation of computer simulation models. The purpose of this final data report is to document a comprehensive, highquality data set that includes only data points where the flap was actively controlled and each of the five flaps behaved in a similar manner.

  16. SMART wind turbine rotor. Data analysis and conclusions

    Energy Technology Data Exchange (ETDEWEB)

    Berg, Jonathan Charles; Barone, Matthew Franklin; Yoder, Nathanael C.

    2014-01-01

    The Wind Energy Technologies department at Sandia National Laboratories has developed and field tested a wind turbine rotor with integrated trailing-edge flaps designed for active control of the rotor aerodynamics. The SMART Rotor project was funded by the Wind and Water Power Technologies Office of the U.S. Department of Energy (DOE) and was conducted to demonstrate active rotor control and evaluate simulation tools available for active control research. This report documents the data post-processing and analysis performed to date on the field test data. Results include the control capability of the trailing edge flaps, the combined structural and aerodynamic damping observed through application of step actuation with ensemble averaging, direct observation of time delays associated with aerodynamic response, and techniques for characterizing an operating turbine with active rotor control.

  17. SMART wind turbine rotor. Design and field test

    Energy Technology Data Exchange (ETDEWEB)

    Berg, Jonathan Charles; Resor, Brian Ray; Paquette, Joshua A.; White, Jonathan Randall

    2014-01-01

    The Wind Energy Technologies department at Sandia National Laboratories has developed and field tested a wind turbine rotor with integrated trailing-edge flaps designed for active control of rotor aerodynamics. The SMART Rotor project was funded by the Wind and Water Power Technologies Office of the U.S. Department of Energy (DOE) and was conducted to demonstrate active rotor control and evaluate simulation tools available for active control research. This report documents the design, fabrication, and testing of the SMART Rotor. This report begins with an overview of active control research at Sandia and the objectives of this project. The SMART blade, based on the DOE / SNL 9-meter CX-100 blade design, is then documented including all modifications necessary to integrate the trailing edge flaps, sensors incorporated into the system, and the fabrication processes that were utilized. Finally the test site and test campaign are described.

  18. Stability investigation of an airfoil section with active flap control

    DEFF Research Database (Denmark)

    Bergami, Leonardo; Gaunaa, Mac

    2010-01-01

    This work presents a method to determine flutter and divergence instability limits for a two-dimensional (2-D) airfoil section fitted with an actively controlled trailing edge flap. This flap consists of a deformable trailing edge, which deformation is governed by control algorithms based...... for fatigue load alleviation. The structural model of the 2-D airfoil section contains three degrees of freedom: heave translation, pitch rotation and flap deflection. A potential flow model provides the aerodynamic forces and their distribution. The unsteady aerodynamics are described using an indicial...... function approximation. Stability of the full aeroservoelastic system is determined through eigenvalue analysis by state-space formulation of the indicial approximation. Validation is carried out against an implementation of the recursive method by Theodorsen and Garrick for flexure-torsion-aileron flutter...

  19. ANALYSIS OF AN ELECTROSTRICTIVE STACK ACTUATOR FOR ACTIVE TRAILING EDGE FLAPS

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Stack actuator is a solid-state driving component of Active Tailing Edge Flap in smart rotor systems. It is a multi-layer serial structure of basic units composed of electrostrictive and adhesive layers. In this paper, a dynamic model of the actuator is derived based on the constitutive equation of electrostrictive material and the equation of motion. Theoretical analysis is made on the factors involved in the design of the actuator, which reveals that the electrostrictive layer and the adhesive layer should be optimized to compromise between displacement and frequency requirements. In the final part of the paper, the experiment of an ATEF system is introduced. The results show that the model is reasonable. It also suggests that the bending stiffness of elastic mechanism is an important factor in design, which should be carefully studied to provide satisfactory dynamic response of the ATEF system.

  20. Active Flow Control of Lifting Surface With Flap-Current Activities and Future Directions

    Science.gov (United States)

    Ahmadi, G.; Marzocca, P.; Jha, R.; Alstorm, B.; Obied, S.; Kabir, P.; Shahrabi, A.

    2010-01-01

    The main objective is to develop effective control strategies for separation control of an airfoil with a single hinge flap. The specific objectives are: Develop an active control architecture for flow control around an airfoil with flap. Design, fabricate, a wind tunnel test of a high lift wing (with flap) with integrated actuators and sensors. Design, development and fabrication of synthetic jet actuators. Develop appropriate control strategy for application to the airfoil. Wind tunnel testing of the high lift wing at various angles of attack and flap positions with closed loop control.

  1. Vibration reduction in helicopter rotors using an active control surface located on the blade

    Science.gov (United States)

    Millott, T. A.; Friedmann, P. P.

    1992-01-01

    A feasibility study of vibration reduction in a four-bladed helicopter rotor using individual blade control (IBC), which is implemented by an individually controlled aerodynamic surface located on each blade, is presented. For this exploratory study, a simple offset-hinged spring restrained model of the blade is used with fully coupled flap-lag-torsional dynamics for each blade. Deterministic controllers based on local and global system models are implemented to reduce 4/rev hub loads using both an actively controlled aerodynamic surface on each blade as well as conventional IBC, where the complete blade undergoes cyclic pitch change. The effectiveness of the two approaches for simultaneous reduction of the 4/rev hub shears and hub moments is compared. Conventional IBC requires considerably more power to achieve approximately the same level of vibration reduction as that obtained by implementing IBC using an active control surface located on the outboard segment of the blade. The effect of blade torsional flexibility on the vibration reduction effectiveness of the actively controlled surface was also considered and it was found that this parameter has a very substantial influence.

  2. Vibration reduction in helicopter rotors using an active control surface located on the blade

    Science.gov (United States)

    Millott, T. A.; Friedmann, P. P.

    1992-01-01

    A feasibility study of vibration reduction in a four-bladed helicopter rotor using individual blade control (IBC), which is implemented by an individually controlled aerodynamic surface located on each blade, is presented. For this exploratory study, a simple offset-hinged spring restrained model of the blade is used with fully coupled flap-lag-torsional dynamics for each blade. Deterministic controllers based on local and global system models are implemented to reduce 4/rev hub loads using both an actively controlled aerodynamic surface on each blade as well as conventional IBC, where the complete blade undergoes cyclic pitch change. The effectiveness of the two approaches for simultaneous reduction of the 4/rev hub shears and hub moments is compared. Conventional IBC requires considerably more power to achieve approximately the same level of vibration reduction as that obtained by implementing IBC using an active control surface located on the outboard segment of the blade. The effect of blade torsional flexibility on the vibration reduction effectiveness of the actively controlled surface was also considered and it was found that this parameter has a very substantial influence.

  3. Human exonuclease 1 (EXO1) activity characterization and its function on FLAP structures

    DEFF Research Database (Denmark)

    Keijzers, Guido; Bohr, Vilhelm A; Juel Rasmussen, Lene

    2015-01-01

    Human exonuclease 1 (EXO1) is involved in multiple DNA metabolism processes, including DNA repair and replication. Most of the fundamental roles of EXO1 have been described in yeast. Here, we report a biochemical characterization of human full-length EXO1. Prior to assay EXO1 on different DNA flap...... structures, we determined factors essential for the thermodynamic stability of EXO1. We show that enzymatic activity and stability of EXO1 on DNA is modulated by temperature. By characterization of EXO1 flap activity using various DNA flap substrates, we show that EXO1 has a strong capacity for degrading...... double stranded DNA and has a modest endonuclease or 5' flap activity. Furthermore, we report novel mechanistic insights into the processing of flap structures, showing that EXO1 preferentially cleaves one nucleotide inwards in a double stranded region of a forked and nicked DNA flap substrates...

  4. Stress optimization of leaf-spring crossed flexure pivots for an active Gurney flap mechanism

    Science.gov (United States)

    Freire Gómez, Jon; Booker, Julian D.; Mellor, Phil H.

    2015-04-01

    The EU's Green Rotorcraft programme is pursuing the development of a functional and airworthy Active Gurney Flap (AGF) for a full-scale helicopter rotor blade. Interest in the development of this `smart adaptive rotor blade' technology lies in its potential to provide a number of aerodynamic benefits, which would in turn translate into a reduction in fuel consumption and noise levels. The AGF mechanism selected employs leaf-spring crossed flexure pivots. These provide important advantages over bearings as they are not susceptible to seizing and do not require maintenance (i.e. lubrication or cleaning). A baseline design of this mechanism was successfully tested both in a fatigue rig and in a 2D wind tunnel environment at flight-representative deployment schedules. For full validation, a flight test would also be required. However, the severity of the in-flight loading conditions would likely compromise the mechanical integrity of the pivots' leaf-springs in their current form. This paper investigates the scope for stress reduction through three-dimensional shape optimization of the leaf-springs of a generic crossed flexure pivot. To this end, a procedure combining a linear strain energy formulation, a parametric leaf-spring profile definition and a series of optimization algorithms is employed. The resulting optimized leaf-springs are proven to be not only independent of the angular rotation at which the pivot operates, but also linearly scalable to leaf-springs of any length, minimum thickness and width. Validated using non-linear finite element analysis, the results show very significant stress reductions relative to pivots with constant cross section leaf-springs, of up to as much as 30% for the specific pivot configuration employed in the AGF mechanism. It is concluded that shape optimization offers great potential for reducing stress in crossed flexure pivots and, consequently, for extending their fatigue life and/or rotational range.

  5. Active Magnetic Bearing Rotor Model Updating Using Resonance and MAC Error

    Directory of Open Access Journals (Sweden)

    Yuanping Xu

    2015-01-01

    Full Text Available Modern control techniques can improve the performance and robustness of a rotor active magnetic bearing (AMB system. Since those control methods usually rely on system models, it is important to obtain a precise rotor AMB analytical model. However, the interference fits and shrink effects of rotor AMB cause inaccuracy to the final system model. In this paper, an experiment based model updating method is proposed to improve the accuracy of the finite element (FE model used in a rotor AMB system. Modelling error is minimized by applying a numerical optimization Nelder-Mead simplex algorithm to properly adjust FE model parameters. Both the error resonance frequencies and modal assurance criterion (MAC values are minimized simultaneously to account for the rotor natural frequencies as well as for the mode shapes. Verification of the updated rotor model is performed by comparing the experimental and analytical frequency response. The close agreements demonstrate the effectiveness of the proposed model updating methodology.

  6. Influence of backup bearings and support structure dynamics on the behavior of rotors with active supports

    Science.gov (United States)

    Flowers, George T.

    1995-02-01

    This semiannual status report lists specific accomplishments made on the research of the influence of backup bearings and support structure dynamics on the behavior of rotors with active supports. Papers have been presented representing work done on the T-501 engine model; an experimental/simulation study of auxiliary bearing rotordynamics; and a description of a rotordynamical model for a magnetic bearing supported rotor system, including auxiliary bearing effects. A finite element model for a foil bearing has been developed. Additional studies of rotor/bearing/housing dynamics are currently being performed as are studies of the effects of sideloading on auxiliary bearing rotordynamics using the magnetic bearing supported rotor model.

  7. Analysis on Dynamic Performance for Active Magnetic Bearing—Rotor System

    Institute of Scientific and Technical Information of China (English)

    YANHui-yan; WANGXi-ping; 等

    2001-01-01

    In the application of active magnetic bearings(AMB),one of the key problems to be solved is the safety and stabiltiy in the sense of rotor dynamics,The project related to the present paper deals with the method for analyzing bearing rotor systems with high rotation speed and specially supported by active magnetic bearings,and studies its rotor dynamics performance,including calculation of the natural frequencies with their distribution characteristics,and the critical speeds of the system.one of the targets of this project is to formulate a theory and method valid for the analysis of the dynamic performance of the active magntic bearing-rotor systemby combining the traditional theory and method of rotor dynamics with the analytical theory and design method based on modern control theory of the AMB system.

  8. 2D CFD Analysis of an Airfoil with Active Continuous Trailing Edge Flap

    Science.gov (United States)

    Jaksich, Dylan; Shen, Jinwei

    2014-11-01

    Efficient and quieter helicopter rotors can be achieved through on-blade control devices, such as active Continuous Trailing-Edge Flaps driven by embedded piezoelectric material. This project aims to develop a CFD simulation tool to predict the aerodynamic characteristics of an airfoil with CTEF using open source code: OpenFOAM. Airfoil meshes used by OpenFOAM are obtained with MATLAB scripts. Once created it is possible to rotate the airfoil to various angles of attack. When the airfoil is properly set up various OpenFOAM properties, such as kinematic viscosity and flow velocity, are altered to achieve the desired testing conditions. Upon completion of a simulation, the program gives the lift, drag, and moment coefficients as well as the pressure and velocity around the airfoil. The simulation is then repeated across multiple angles of attack to give full lift and drag curves. The results are then compared to previous test data and other CFD predictions. This research will lead to further work involving quasi-steady 2D simulations incorporating NASTRAN to model aeroelastic deformation and eventually to 3D aeroelastic simulations. NSF ECE Grant #1358991 supported the first author as an REU student.

  9. Influence of time domain unsteady aerodynamics on coupled flap-lag-torsional aeroelastic stability and response of rotor blades

    Science.gov (United States)

    Friedmann, P. P.; Robinson, L. H.

    1988-01-01

    This paper describes the incorporation of finite-state, time-domain aerodynamics in a flag-lag-torsional aeroelastic stability and response analysis in forward flight. Improvements to a previous formulation are introduced which eliminate spurious singularities. The methodology for solving the aeroelastic stability and response problems with augmented states, in the time domain, is presented using an implicit formulation. Results describing the aeroelastic behavior of soft and stiff in-plane hingeless rotor blades, in forward flight, are presented to illustrate the sensitivity of both the stability and response problems to time domain unsteady aerodynamics.

  10. Influence of time domain unsteady aerodynamics on coupled flap-lag-torsional aeroelastic stability and response of rotor blades

    Science.gov (United States)

    Friedmann, P. P.; Robinson, L. H.

    1988-01-01

    This paper describes the incorporation of finite-state, time-domain aerodynamics in a flag-lag-torsional aeroelastic stability and response analysis in forward flight. Improvements to a previous formulation are introduced which eliminate spurious singularities. The methodology for solving the aeroelastic stability and response problems with augmented states, in the time domain, is presented using an implicit formulation. Results describing the aeroelastic behavior of soft and stiff in-plane hingeless rotor blades, in forward flight, are presented to illustrate the sensitivity of both the stability and response problems to time domain unsteady aerodynamics.

  11. Multiple attractors in the response of a flexible rotor in active magnetic bearings with geometric coupling

    Energy Technology Data Exchange (ETDEWEB)

    Inayat-Hussain, J I [School of Engineering, Monash University, Jalan Lagoon Selatan, 46150 Bandar Sunway, Selangor Darul Ehsan (Malaysia)], E-mail: jawaid.inayat-hussain@eng.monash.edu.my

    2008-02-15

    Numerical results on the response of a flexible rotor supported by nonlinear active magnetic bearings are presented. Nonlinearity arising from the magnetic actuator forces that are nonlinear functions of the coil current and the air gap between the rotor and the stator, and from the geometric coupling of the magnetic actuators is incorporated into the mathematical model of the flexible rotor - active magnetic bearing system. For relatively large values of the geometric coupling parameter, the response of the rotor with the variation of the speed parameter within the range 0.05 {<=}{omega} {<=} 5.0 displayed a rich variety of nonlinear dynamical phenomena including sub-synchronous vibrations of periods -2, -3, -6, -9, and -17, quasi-periodicity and chaos. Numerical results also reveal the occurrence of bi-stable operation within certain ranges of the speed parameter where multiple attractors may co-exist at the same speed parameter value depending on the operating speed of the rotor.

  12. SMART Wind Turbine Rotor: Data Analysis and Conclusions

    Energy Technology Data Exchange (ETDEWEB)

    Berg, Jonathan C. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Barone, Matthew F. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Yoder, Nathanael C. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2014-01-29

    This report documents the data post-processing and analysis performed to date on the field test data. Results include the control capability of the trailing edge flaps, the combined structural and aerodynamic damping observed through application of step actuation with ensemble averaging, direct observation of time delays associated with aerodynamic response, and techniques for characterizing an operating turbine with active rotor control.

  13. Active magnetic bearings dynamic parameters identification from experimental rotor unbalance response

    Science.gov (United States)

    Xu, Yuanping; Zhou, Jin; Di, Long; Zhao, Chen

    2017-01-01

    Active magnetic bearings (AMBs) support rotors using electromagnetic force rather than mechanical forces. It is necessary to accurately identify the AMBs force coefficients since they play a critical role in the rotordynamic analysis including system stability, bending critical speeds and modes of vibrations. This paper proposes a rotor unbalance response based approach to identifying the AMBs stiffness and damping coefficients during rotation. First, a Timoshenko beam finite element (FE) rotor model is created. Second, an identification procedure based on the FE model is proposed. Then based on the experimental rotor unbalance response data from 1200 rpm to 30,000 rpm, the AMBs dynamic force parameters (stiffness and damping) are obtained. Finally, the identified results are verified by comparing the estimated and experimental rotor unbalance responses, which shows high accuracy.

  14. Active vibration control for flexible rotor by optimal direct-output feedback control

    Science.gov (United States)

    Nonami, Kenzou; Dirusso, Eliseo; Fleming, David P.

    1989-01-01

    Experimental research tests were performed to actively control the rotor vibrations of a flexible rotor mounted on flexible bearing supports. The active control method used in the tests is called optimal direct-output feedback control. This method uses four electrodynamic actuators to apply control forces directly to the bearing housings in order to achieve effective vibration control of the rotor. The force actuators are controlled by an analog controller that accepts rotor displacement as input. The controller is programmed with experimentally determined feedback coefficients; the output is a control signal to the force actuators. The tests showed that this active control method reduced the rotor resonance peaks due to unbalance from approximately 250 micrometers down to approximately 25 micrometers (essentially runout level). The tests were conducted over a speed range from 0 to 10,000 rpm; the rotor system had nine critical speeds within this speed range. The method was effective in significantly reducing the rotor vibration for all of the vibration modes and critical speeds.

  15. Unbalance and resonance elimination with active bearings on a Jeffcott Rotor

    Science.gov (United States)

    Heindel, Stefan; Becker, Fabian; Rinderknecht, Stephan

    2017-02-01

    In this contribution we have proven theoretically and practically that active bearings are able to eliminate both bearing forces and the resonance of a Jeffcott Rotor system. Active bearings can displace a rotor such that its center of mass always stays in the rotational center. The proposed collocated controller is able to keep this state at any rotational speed, leading to an elimination of bearing forces and resonances. We analytically demonstrated that the closed-loop system is always stable, even without knowledge of the rotor's properties. The generalization of the proposed control approach for force-free operation either using displacement or force actuators enables its use for all kinds of active bearings. Moreover, the control approach allows a real time estimation of the rotor's eccentricity. The low parameter count and the unproblematic stability behavior qualify the controller for many applications.

  16. Control of flexible rotor systems with active magnetic bearings

    Science.gov (United States)

    Lei, Shuliang; Palazzolo, Alan

    2008-07-01

    An approach is presented for the analysis and design of magnetic suspension systems with large flexible rotordynamics models including dynamics, control, and simulation. The objective is to formulate and synthesize a large-order, flexible shaft rotordynamics model for a flywheel supported with magnetic bearings. A finite element model of the rotor system is assembled and then employed to develop a magnetic suspension compensator to provide good reliability and disturbance rejection. Stable operation over the complete speed range and optimization of the closed-loop rotordynamic properties are obtained via synthesis of eigenvalue analysis, Campbell plots, waterfall plots, and mode shapes. The large order of the rotor model and high spin speed of the rotor present a challenge for magnetic suspension control. A flywheel system is studied as an example for realizing a physical controller that provides stable rotor suspension and good disturbance rejection in all operating states. The baseline flywheel system control is determined from extensive rotordynamics synthesis and analysis for rotor critical speeds, mode shapes, frequency responses, and time responses.

  17. Active control of gust- and interference-induced vibration of tilt-rotor aircraft

    Science.gov (United States)

    Ham, Norman D.; Wereley, Norman M.; Von Ellenrieder, Karl D.

    1989-01-01

    An active control system to suppress the response of the blade bending modes of a tilt-rotor aircraft to axial gusts and wing/rotor interference is described. The use of blade-mounted accelerometers as sensors is shown to permit the measurement and control of tilt-rotor blade modal responses and their associated vibratory loads directly. The feedback of modal acceleration, in addition to modal rate and displacement, is demonstrated to provide a control phase lead, in comparison with feedback of modal rate and displacement only, which makes higher system gains achievable.

  18. Concepts for a theoretical and experimental study of lifting rotor random loads and vibrations, Phase 1

    Science.gov (United States)

    Hohenemser, K. H.; Gaonkar, G. H.

    1967-01-01

    A number of lifting rotor conditions with random inputs are discussed. The present state of random process theory, applicable to lifting rotor problems is sketched. Possible theories of random blade flapping and random blade flap-bending are outlined and their limitations discussed. A plan for preliminary experiments to study random flapping motions of a see-saw rotor is developed.

  19. A New Sensorless MRAS Based on Active Power Calculations for Rotor Position Estimation of a DFIG

    Directory of Open Access Journals (Sweden)

    Gil Domingos Marques

    2011-01-01

    Full Text Available A sensorless method for the estimation of the rotor position of the wound-rotor induction machine is described in this paper. The method is based on the MRAS methodology and consists in the comparison of two models for the evaluation of the active power transferred across the air gap: the reference model and the adaptive model. The reference model obtains the power transferred across the air gap using directly available and measured stator variables. The adaptive model obtains the same quantity in function of electromotive forces and rotor currents that are measurable on the rotor position, which is under estimation. The method does not need any information about the stator or rotor flux and can be implemented in the rotor or in the stator reference frames with a hysteresis or with a PI controller. The stability analysis gives an unstable region on the rotor current dq plane. Simulation and experimental results show that the method is appropriate for the vector control of the doubly fed induction machine under the stability region.

  20. A New Sensorless MRAS Based on Active Power Calculations for Rotor Position Estimation of a DFIG

    OpenAIRE

    Gil Domingos Marques; Duarte Mesquita e Sousa

    2011-01-01

    A sensorless method for the estimation of the rotor position of the wound-rotor induction machine is described in this paper. The method is based on the MRAS methodology and consists in the comparison of two models for the evaluation of the active power transferred across the air gap: the reference model and the adaptive model. The reference model obtains the power transferred across the air gap using directly available and measured stator variables. The adaptive model obtains the same quanti...

  1. Active Vibration Control in a Rotor System by an Active Suspension with Linear Actuators

    Directory of Open Access Journals (Sweden)

    M. Arias-Montiel

    2014-10-01

    Full Text Available In this paper the problem of modeling, analysis and unbalance response control of a rotor system with two disks in an asymmetrical configuration is treated. The Finite Element Method (FEM is used to get the system model including the gyroscopic effects and then, the obtained model is experimentally validated. Rotordynamic analysis is carried out using the finite element model obtaining the Campbell diagram, the natural frequencies and the critical speeds of the rotor system. An asymptotic observer is designed to estimate the full state vector which is used to synthesize a Linear Quadratic Regulator (LQR to reduce the vibration amplitudes when the system passes through the first critical speed. Some numerical simulations are carried out to verify the closed-loop system behavior. The active vibration control scheme is experimentally validated using an active suspension with electromechanical linear actuators, obtaining significant reductions in the resonant peak.

  2. Active Control of Flapping Wings Using Wing Deformation

    Science.gov (United States)

    Tokutake, Hiroshi; Sunada, Shigeru; Ohtsuka, Yukio

    A new method for the attitude control of a flapping-wing aircraft is proposed. In this method, the variations in wing deformation, that is, the feathering angle and the camber, are controlled by pulling the wing at a certain point with a thread connected to a servomotor. The experimental setup for verifying the practicability of this method was developed, and aerodynamic forces and wing deformation were measured. It was concluded that thread control caused effective wing deformation, and the variation in the deformation generated the pitching moment that controls the attitude of a flapping-wing aircraft.

  3. Chaos via torus breakdown in the vibration response of a rigid rotor supported by active magnetic bearings

    Energy Technology Data Exchange (ETDEWEB)

    Inayat-Hussain, Jawaid I. [School of Engineering, Monash University Malaysia, No. 2, Jalan Kolej, Bandar Sunway, 46150 Petaling Jaya, Selangor Darul Ehsan (Malaysia)]. E-mail: jawaid.inayat-hussain@eng.monash.edu.my

    2007-02-15

    This work reports on a numerical study undertaken to investigate the response of an imbalanced rigid rotor supported by active magnetic bearings. The mathematical model of the rotor-bearing system used in this study incorporates nonlinearity arising from the electromagnetic force-coil current-air gap relationship, and the effects of geometrical cross-coupling. The response of the rotor is observed to exhibit a rich variety of dynamical behavior including synchronous, sub-synchronous, quasi-periodic and chaotic vibrations. The transition from synchronous rotor response to chaos is via the torus breakdown route. As the rotor imbalance magnitude is increased, the synchronous rotor response undergoes a secondary Hopf bifurcation resulting in quasi-periodic vibration, which is characterized by a torus attractor. With further increase in the rotor imbalance magnitude, this attractor is seen to develop wrinkles and becomes unstable resulting in a fractal torus attractor. The fractal torus is eventually destroyed as the rotor imbalance magnitude is further increased. Quasi-periodic and frequency-locked sub-synchronous vibrations are seen to appear and disappear alternately before the emergence of chaos in the response of the rotor. The magnitude of rotor imbalance where sub-synchronous, quasi-periodic and chaotic vibrations are observed in this study, albeit being higher than the specified imbalance level for rotating machinery, may possibly occur due to a gradual degradation of the rotor balance quality during operation.

  4. Magnetostatic analysis of a rotor system supported by radial active magnetic bearings

    Directory of Open Access Journals (Sweden)

    Ferfecki P.

    2009-06-01

    Full Text Available The development and the design of a radial active magnetic bearing (AMB reflects a complex process of the multidisciplinary rotor dynamics, electromagnetism and automatic control analysis. Modelling is performed by application of the physical laws from different areas, e.g. Newton's laws of motion and Maxwell's equations. The new approach in the numerical modelling of radial AMB and design methodology allowing automatic generation of primary dimensions of the radial AMB is proposed. Instead of the common way of computation of electromagnetic forces by linearizing at the centre position of the rotor with respect to rotor displacement and coil current, the finite element computation of electromagnetic forces is used. The heteropolar radial AMB consisting of eight pole shoes was designed by means of the built up algorithms for rotor system with two discs fixed on the cantilever shaft. A study of the influence of the nonlinear magnetization characteristics of a rotor and stator material on the equilibrium position of a rotor system is carried out. The performed numerical study shows that results obtained from the analytical nonlinear relation for electromagnetic forces can be considerably different from forces computed with magnetostatic finite element analysis.

  5. Control system design for flexible rotors supported by actively lubricated bearings

    DEFF Research Database (Denmark)

    Nicoletti, Rodrigo; Santos, Ilmar

    2008-01-01

    This article presents a methodology for calculating the gains of an output feedback controller for active vibration control of flexible rotors. The methodology is based on modal reduction. The proportional and derivative gains are obtained by adjusting the first two damping factors of the system...... and keeping the lengths of the two eigenvalues constant in the real-imaginary plane. The methodology is applied to an industrial gas compressor supported by active tilting-pad journal bearings. The unbalance response functions and mode shapes of the flexible rotor with and without active control are presented...

  6. Actuators of active tribotechnical systems of the rotor-bearing type

    Science.gov (United States)

    Savin, L.; Shutin, D.; Kuzavka, A.

    2017-08-01

    The article describes the perspectives of using active bearings in rotor-bearing systems. The principal scheme of a mechatronic tribotechnical system anв classification of actuators used in such system are shown. Piezo actuators are considered from the point of view of use as actuators in active bearings. The comparative characteristics of different types of actuators

  7. An active optimal control strategy of rotor vibrations using external forces

    Science.gov (United States)

    Zhu, W.; Castelazo, I.; Nelson, H. D.

    1989-01-01

    An active control strategy for lateral rotor vibrations using external forces is proposed. An extended state observer is used to reconstruct the full states and the unbalance distribution. An optimal controller which accommodates persistent unbalance excitation is derived with feedback of estimated states and unbalances. Numerical simulations were conducted for two separate four degree of freedom rotor systems. These simulations indicated that the proposed strategy can achieve almost complete vibration cancellation. This was shown to be true even when the number of external control forces was less than the system order so long as coordinate coupling was present. Both steady state and transient response at a constant speed are presented.

  8. Active control of counter-rotating open rotor interior noise in a Dornier 728 experimental aircraft

    Science.gov (United States)

    Haase, Thomas; Unruh, Oliver; Algermissen, Stephan; Pohl, Martin

    2016-08-01

    The fuel consumption of future civil aircraft needs to be reduced because of the CO2 restrictions declared by the European Union. A consequent lightweight design and a new engine concept called counter-rotating open rotor are seen as key technologies in the attempt to reach this ambitious goals. Bearing in mind that counter-rotating open rotor engines emit very high sound pressures at low frequencies and that lightweight structures have a poor transmission loss in the lower frequency range, these key technologies raise new questions in regard to acoustic passenger comfort. One of the promising solutions for the reduction of sound pressure levels inside the aircraft cabin are active sound and vibration systems. So far, active concepts have rarely been investigated for a counter-rotating open rotor pressure excitation on complex airframe structures. Hence, the state of the art is augmented by the preliminary study presented in this paper. The study shows how an active vibration control system can influence the sound transmission of counter-rotating open rotor noise through a complex airframe structure into the cabin. Furthermore, open questions on the way towards the realisation of an active control system are addressed. In this phase, an active feedforward control system is investigated in a fully equipped Dornier 728 experimental prototype aircraft. In particular, the sound transmission through the airframe, the coupling of classical actuators (inertial and piezoelectric patch actuators) into the structure and the performance of the active vibration control system with different error sensors are investigated. It can be shown that the active control system achieves a reduction up to 5 dB at several counter-rotating open rotor frequencies but also that a better performance could be achieved through further optimisations.

  9. Frequency Response Analysis of an Actively Lubricated Rotor/Tilting-Pad Bearing System

    DEFF Research Database (Denmark)

    Nicoletti, Rodrigo; Santos, Ilmar

    2004-01-01

    In the present paper, the dynamic response of a rotor supported by an active lubricated tilting-pad bearing is investigated in the frequency domain. The theoretical part of the investigation is based on a mathematical model obtained by means of rigid body dynamics. The oil film forces are inserte...

  10. Adjustable ETHD lubrication applied to the improvement of dynamic performance of flexible rotors supported by active TPJB

    DEFF Research Database (Denmark)

    Salazar, Jorge Andrés González; Cerda Varela, Alejandro Javier; Santos, Ilmar

    2013-01-01

    This paper reports the dynamic study of a flexible rotor-bearing test rig which resembles a large overhung centrifugal compressor. The rotor is supported by an active tilting pad journal bearing (TPJB) able to perform the adjustable lubrication regime. Such a regime is obtained by injecting press...

  11. Adjustable ETHD lubrication applied to the improvement of dynamic performance of flexible rotors supported by active TPJB

    DEFF Research Database (Denmark)

    Salazar, Jorge Andrés González; Cerda Varela, Alejandro Javier; Santos, Ilmar

    2013-01-01

    This paper reports the dynamic study of a flexible rotor-bearing test rig which resembles a large overhung centrifugal compressor. The rotor is supported by an active tilting pad journal bearing (TPJB) able to perform the adjustable lubrication regime. Such a regime is obtained by injecting...

  12. Lateral vibration control of a flexible overcritical rotor via an active gas bearing – Theoretical and experimental comparisons

    DEFF Research Database (Denmark)

    Pierart Vásquez, Fabián Gonzalo; Santos, Ilmar

    2016-01-01

    The lack of damping of radial gas bearings leads to high vibration levels of a rotor supported by this type of bearing when crossing resonant areas. This is even more relevant for flexible rotors, as studied in this work. In order to reduce these high vibration levels, an active gas bearing is pr...

  13. A Study of Active Rotor-Blade Vibration Control using Electro-Magnetic Actuation - Part II: Experiment

    DEFF Research Database (Denmark)

    Christensen, Rene Hardam; Santos, Ilmar

    2004-01-01

    . The remaining two sets of actuators are applied to act directly onto the hub, working as an active radial bearing controlling the rotor lateral movement. The rig is equipped with sensors measuring blade and rotor vibrations. Actuators and sensors are connected to a digital signal processor running the control......This is the second paper in a two-part study on active rotor-blade vibration control. This part presents an experimental contribution into the work of active controller design for rotor-blade systems. The primary aim is to give an experimental validation and show the applicability...... shaft is mounted in a flexible hub, which can perform lateral movement. The blades are designed as simple Euler-Bernoulli beams with tip masses in order to increase the vibration coupling among the rigid rotors and the flexible blades motion. Different schemes of blade configurations, with and without...

  14. Contributions to the dynamics of helicopters with active rotor controls

    Science.gov (United States)

    Malpica, Carlos A.

    This dissertation presents an aeromechanical closed loop stability and response analysis of a hingeless rotor helicopter with a Higher Harmonic Control (HHC) system for vibration reduction. The analysis includes the rigid body dynamics of the helicopter and blade flexibility. The gain matrix is assumed to be fixed and computed off-line. The discrete elements of the HHC control loop are rigorously modeled, including the presence of two different time scales in the loop. By also formulating the coupled rotor-fuselage dynamics in discrete form, the entire coupled helicopter-HHC system could be rigorously modeled as a discrete system. The effect of the periodicity of the equations of motion is rigorously taken into account by converting the system into an equivalent system with constant coefficients and identical stability properties using a time lifting technique. The most important conclusion of the present study is that the discrete elements in the HHC loop must be modeled in any HHC analysis. Not doing so is unconservative. For the helicopter configuration and HHC structure used in this study, an approximate continuous modeling of the HHC system indicates that the closed loop, coupled helicopter-HHC system remains stable for optimal feedback control configurations which the more rigorous discrete analysis shows can result in closed loop instabilities. The HHC gains must be reduced to account for the loss of gain margin brought about by the discrete elements. Other conclusions of the study are: (i) the HHC is effective in quickly reducing vibrations, at least at its design condition, although the time constants associated with the closed loop transient response indicate closed loop bandwidth to be 1 rad/sec on average, thus overlapping with FCS or pilot bandwidths, and raising the issue of potential interactions; (ii) a linearized model of helicopter dynamics is adequate for HHC design, as long as the periodicity of the system is correctly taken into account, i

  15. Modal Tilt/Translate Control and Stability of a Rigid Rotor with Gyroscopics on Active Magnetic Bearings

    Directory of Open Access Journals (Sweden)

    Timothy Dimond

    2012-01-01

    Full Text Available Most industrial rotors supported in active magnetic bearings (AMBs are operated well below the first bending critical speed. Also, they are usually controlled using proportional, integral and derivative controllers, which are set up as modally uncoupled parallel and tilt rotor axes. Gyroscopic effects create mode splitting and a speed-dependent plant. Two AMBs with four axes of control must simultaneously control and stabilize the rotor/AMB system. Various analyses have been published considering this problem for different rotor/AMB configurations. There has not been a fully dimensionless analysis of these rigid rotor AMB systems. This paper will perform this analysis with a modal PD controller in terms of translation mode and tilt mode dimensionless eigenvalues and eigenvectors. The number of independent system parameters is significantly reduced. Dimensionless PD controller gains, the ratio of rotor polar to transverse moments of inertia and a dimensionless speed ratio are used to evaluate a fully general system stability rigid rotor analysis. An objective of this work is to quantify the effects of gyroscopics on rigid rotor AMB systems. These gyroscopic forces reduce the system stability margin. The paper is also intended to help provide a common framework for communication between rotating machinery designers and controls engineers

  16. Model-Based Control Design for Flexible Rotors Supported by Active Gas Bearings - Theory & Experiment

    DEFF Research Database (Denmark)

    Pierart Vásquez, Fabián Gonzalo

    Gas journal bearings have been increasingly adopted in modern turbo-machinery due to their numerous indisputable advantages. They can operate at higher speed than most bearing designs, almost without noise or heat generation and in most cases, as in this work, the gas used is air which is cheap...... work, the control signal design is based on a theoretical model. This approach enables easy modifications of any of the numerous physical parameters in the system if needed. The theoretical model used is based on a modifed version of Reynolds equation where an extra term is added in order to include...... frequencies and damping ratios of the rotor-bearing system) is performed and finally to design controllers that allows improvement of the dynamic properties of the rotor-active gas bearings system and lets the systemto safely cross the critical speeds, using the theoretical model as a design tool. The results...

  17. Dynamics of an Active-Site Flap Contributes to Catalysis in a JAMM Family Metallo Deubiquitinase.

    Science.gov (United States)

    Bueno, Amy N; Shrestha, Rashmi K; Ronau, Judith A; Babar, Aditya; Sheedlo, Michael J; Fuchs, Julian E; Paul, Lake N; Das, Chittaranjan

    2015-10-06

    The endosome-associated deubiquitinase (DUB) AMSH is a member of the JAMM family of zinc-dependent metallo isopeptidases with high selectivity for Lys63-linked polyubiquitin chains, which play a key role in endosomal-lysosomal sorting of activated cell surface receptors. The catalytic domain of the enzyme features a flexible flap near the active site that opens and closes during its catalytic cycle. Structural analysis of its homologues, AMSH-LP (AMSH-like protein) and the fission yeast counterpart, Sst2, suggests that a conserved Phe residue in the flap may be critical for substrate binding and/or catalysis. To gain insight into the contribution of this flap in substrate recognition and catalysis, we generated mutants of Sst2 and characterized them using a combination of enzyme kinetics, X-ray crystallography, molecular dynamics simulations, and isothermal titration calorimetry (ITC). Our analysis shows that the Phe residue in the flap contributes key interactions during the rate-limiting step but not to substrate binding, since mutants of Phe403 exhibit a defect only in kcat but not in KM. Moreover, ITC studies show Phe403 mutants have similar KD for ubiquitin compared to the wild-type enzyme. The X-ray structures of both Phe403Ala and the Phe403Trp, in both the free and ubiquitin bound form, reveal no appreciable structural change that might impair substrate or alter product binding. We observed that the side chain of the Trp residue is oriented identically with respect to the isopeptide moiety of the substrate as the Phe residue in the wild-type enzyme, so the loss of activity seen in this mutant cannot be explained by the absence of a group with the ability to provide van der Waals interactions that facilitate the hyrdolysis of the Lys63-linked diubiquitin. Molecular dynamics simulations indicate that the flap in the Trp mutant is quite flexible, allowing almost free rotation of the indole side chain. Therefore, it is possible that these different dynamic

  18. Alleviation of whirl-flutter on a joined-wing tilt-rotor aircraft configuration using active controls

    Science.gov (United States)

    Vanaken, Johannes M.

    1991-01-01

    The feasibility of using active controls to delay the onset of whirl-flutter on a joined-wing tilt rotor aircraft was investigated. The CAMRAD/JA code was used to obtain a set of linear differential equations which describe the motion of the joined-wing tilt-rotor aircraft. The hub motions due to wing/body motion is a standard input to CAMRAD/JA and were obtained from a structural dynamics model of a representative joined-wing tilt-rotor aircraft. The CAMRAD/JA output, consisting of the open-loop system matrices, and the airframe free vibration motion were input to a separate program which performed the closed-loop, active control calculations. An eigenvalue analysis was performed to determine the flutter stability of both open- and closed-loop systems. Sensor models, based upon the feedback of pure state variables and based upon hub-mounted sensors, providing physically measurable accelerations, were evaluated. It was shown that the onset of tilt-rotor whirl-flutter could be delayed from 240 to above 270 knots by feeding back vertical and span-wise accelerations, measured at the rotor hub, to the longitudinal cyclic pitch. Time response calculations at a 270-knot cruise condition showed an active cyclic pitch control level of 0.009 deg, which equates to a very acceptable 9 pound active-control force applied at the rotor hub.

  19. Rotors on Active Magnetic Bearings: Modeling and Control Techniques

    OpenAIRE

    Tonoli, Andrea; Bonfitto, Angelo; Silvagni, Mario; Suarez, Lester D.

    2012-01-01

    In the last decades the deeper and more detailed understanding of rotating machinery dynamic behavior facilitated the study and the design of several devices aiming at friction reduction, vibration damping and control, rotational speed increase and mechanical design optimization. Among these devices a promising technology is represented by active magnetic actuators which found a great spread in rotordynamics and in high precision applications due to (a) the absence of all fatigue and tribolog...

  20. Active Pedicle Epithelial Flap Transposition Combined with Amniotic Membrane Transplantation for Treatment of Nonhealing Corneal Ulcers

    Directory of Open Access Journals (Sweden)

    Ting Zhang

    2016-01-01

    Full Text Available Introduction. The objective was to evaluate the efficacy of active pedicle epithelial flap transposition combined with amniotic membrane transplantation (AMT in treating nonhealing corneal ulcers. Material and Methods. Eleven patients (11 eyes with nonhealing corneal ulcer who underwent the combined surgery were included. Postoperatively, ulcer healing time was detected by corneal fluorescein staining. Visual acuity, intraocular pressure, surgical complications, and recurrence were recorded. Corneal status was inspected by the laser scanning confocal microscopy and anterior segment optical coherence tomography (AS-OCT. Results. The primary diseases were herpes simplex keratitis (8 eyes, corneal graft ulcer (2 eyes, and Stevens-Johnson syndrome (1 eye. All epithelial flaps were intact following surgery, without shedding or displacement. Mean ulcer healing time was 10.8±3.1 days, with a healing rate of 91%. Vision significantly improved from 1.70 to 0.82 log MAR (P=0.001. A significant decrease in inflammatory cell infiltration and corneal stromal edema was revealed 2 months postoperatively by confocal microscopy and AS-OCT. Corneal ulcer recurred in 1 eye. None of the patients developed major complications. Conclusion. Active pedicle epithelial flap transposition combined with AMT is a simple and effective treatment for nonhealing corneal ulcers.

  1. The Research of Influence of Blood upon the Dynamics of Artificial Ventricle Rotor on Active Magnetic Bearings

    Directory of Open Access Journals (Sweden)

    E. E. Ovsiannikova

    2015-01-01

    Full Text Available The article studies dynamics of rotor on active magnetic bearings within the mathematical model development of rotor in artificial ventricle. The problem of stabilization of rigid titanium rotor with magnetic inserts on active magnetic bearings is analyzed.The relevance of the research field is caused by high percent of people who are suffering from heart disease. The purposes of work are to create a mathematical model of the rigid rotor and position its center to meet specified requirements for displacement of no more than 0.2 millimeter while rotating with the speed from 5 000 rpm to 10 000 rpm in constant blood flow. The work of AMBs is based on the principle of active magnetic pendant of ferromagnetic solid. The stabilization in adjusted position is accomplished by magnetic forces, which affect the solid from the control electromagnets.The article presents initial data, design scheme, assumptions accepted to solve the problem and derivation of dynamic equation of rotating rigid rotor on AMBs. The decentralized control of magnetic pendant was implemented. The PD control – proportional differential control - was chosen as the base of control system. Its application is widespread due to the simplicity, industrial use and operation stability. The use of decentralized control in dynamics modeling of a rigid rotor in AMBs is physically occurred and has some advantages. One of the most important advantages is the calculation of control parameters by selection of appropriate values of rigidity and damping parameters.The analysis of rotor dynamics was conducted in MATLAB© software package.The modeling was performed to allow observing the system action while the parameters were varied.The conducted research showed that to meet the specified requirements of maximal rotor displacement no more than 0.2 mm the following values of coefficients were required:                                       and The stabilization of the rotor

  2. Study on the application of active balancing device to solve the vibration problem for the rotor with bending fault

    Institute of Scientific and Technical Information of China (English)

    He Lidong; Shen Wei; Gao Jinji; Zhou Weihua

    2006-01-01

    The rotor with bending faults that occurrs on the rotating machinery usually vibrates seriously. This paper investigates to apply the active balancing device on a flexible rotor with bending faults to solve the vibration problem. Two problems are studied by finite element method firstly: Where the balance actuator is fixed on the shaft and how much the balancing capacity of the active balancing device is needed. The experiment is then carried out on the test rig, which consists of a flexible rotor with bending faults. The test results indicate that the bending rotor peak vibration response can be decreased from 550μm to 40μm below by using the active balancing device. The peak vibration response decreases approximately by 93%. The synchronous vibration due to the rotor bending faults can be controlled effectively by using active balancing device. The active balancing device is especially adapted to solve the problem caused by thermal distortion with time-variation and randomness, which is varied with working conditions, thus it has good practical value in practice.

  3. Frequency Response Analysis of an Actively Lubricated Rotor/Tilting-Pad Bearing System

    DEFF Research Database (Denmark)

    Nicoletti, Rodrigo; Santos, Ilmar

    2005-01-01

    In the present paper the dynamic response of a rotor supported by an active lubricated tilting-pad bearing is investigated in the frequency domain. The theoretical part of the investigation is based on a mathematical model obtained by means of rigid body dynamics. The oil film forces are inserted...... into the model by using two different approaches: (a) linearized active oil film forces and the assumption that the hydrodynamic forces and the active hydraulic forces can be decoupled, and (b) equivalent dynamic coefficients of the active oil film and the solution of the modified Reynolds equation...... lubricated tilting-pad bearing. By applying a simple proportional controller it is possible to reach 30% reduction of the resonance peak associated with the first rigid body mode shape of the system. One of the most important consequences of such a vibration reduction in rotating machines is the feasibility...

  4. Active tilting-pad journal bearings supporting flexible rotors: Part I – The hybrid lubrication

    DEFF Research Database (Denmark)

    Salazar, Jorge Andrés González; Santos, Ilmar

    2017-01-01

    This is part I of a twofold paper series, of theoretical and experimental nature, presenting the design and implementation of model-based controllers meant for assisting the hybrid and developing the feedback-controlled lubrication regimes in active tilting-pad journal bearings (active TPJBs......). In part I, the flexible rotor-active TPJB modelling is thoroughly covered by establishing the link between the mechanical and hydraulic systems for all regimes. The hybrid lubrication is herein covered in depth; from a control viewpoint, an integral controller to aid such a regime is designed using model......-based standard tools. Results show slight improvement on the system dynamic performance by using the hybrid lubrication instead of the passive one. Further improvements are pursued with the active lubrication in part II....

  5. Initial Aerodynamic and Acoustic Study of an Active Twist Rotor Using a Loosely Coupled CFD/CSD Method

    Science.gov (United States)

    Boyd, David D. Jr.

    2009-01-01

    Preliminary aerodynamic and performance predictions for an active twist rotor for a HART-II type of configuration are performed using a computational fluid dynamics (CFD) code, OVERFLOW2, and a computational structural dynamics (CSD) code, CAMRAD -II. These codes are loosely coupled to compute a consistent set of aerodynamics and elastic blade motions. Resultant aerodynamic and blade motion data are then used in the Ffowcs-Williams Hawkins solver, PSU-WOPWOP, to compute noise on an observer plane under the rotor. Active twist of the rotor blade is achieved in CAMRAD-II by application of a periodic torsional moment couple (of equal and opposite sign) at the blade root and tip at a specified frequency and amplitude. To provide confidence in these particular active twist predictions for which no measured data is available, the rotor system geometry and computational set up examined here are identical to that used in a previous successful Higher Harmonic Control (HHC) computational study. For a single frequency equal to three times the blade passage frequency (3P), active twist is applied across a range of control phase angles at two different amplitudes. Predicted results indicate that there are control phase angles where the maximum mid-frequency noise level and the 4P non -rotating hub vibrations can be reduced, potentially, both at the same time. However, these calculated reductions are predicted to come with a performance penalty in the form of a reduction in rotor lift-to-drag ratio due to an increase in rotor profile power.

  6. Active Control for Multinode Unbalanced Vibration of Flexible Spindle Rotor System with Active Magnetic Bearing

    OpenAIRE

    Xiaoli Qiao; Guojun Hu

    2017-01-01

    The unbalanced vibration of the spindle rotor system in high-speed cutting processes not only seriously affects the surface quality of the machined products, but also greatly reduces the service life of the electric spindle. However, since the unbalanced vibration is often distributed on different node positions, the multinode unbalanced vibration greatly exacerbates the difficulty of vibration control. Based on the traditional influence coefficient method for controlling the vibration of a f...

  7. Numerical analysis of active chordwise flexibility on the performance of non-symmetrical flapping airfoils

    Science.gov (United States)

    Tay, W. B.; Lim, K. B.

    2010-01-01

    This paper investigates the effect of active chordwise flexing on the lift, thrust and propulsive efficiency of three types of airfoils. The factors studied are the flexing center location, standard two-sided flexing as well as a type of single-sided flexing. The airfoils are simulated to flap with four configurations, and the effects of flexing under these configurations are investigated. Results show that flexing is not necessarily beneficial for the performance of the airfoils. However, with the correct parameters, efficiency is as high as 0.76 by placing the flexing centre at the trailing edge. The average thrust coefficient is more than twice as high, from 1.63 to 3.57 with flapping and flexing under the right conditions. Moreover, the single-sided flexing also gives an average lift coefficient as high as 4.61 for the S1020 airfoil. The shape of the airfoil does alter the effect of flexing too. Deviating the flexing phase angle away from 90° does not give a significant improvement to the airfoil’s performance. These results greatly enhance the design of a better performing ornithopter wing.

  8. A Study of Active Rotor-Blade Vibration Control using Electro-Magnetic Actuation - Part I: Theory

    DEFF Research Database (Denmark)

    Christensen, Rene Hardam; Santos, Ilmar

    2004-01-01

    This is the first paper in a two-part study on active rotor-blade vibration control. Blade faults are a major problem in bladed machines, such as turbines and compressors. Moreover, increasing demands for higher efficiency, lower weight and higher speed imply that blades become even more suscepti...

  9. 主动电磁轴承系统的动力学性能分析%Analysis on Dynamic Performance for Active Magnetic Bearing-Rotor System

    Institute of Scientific and Technical Information of China (English)

    严慧燕; 汪希平; 朱礼进; 张直明; 万金贵

    2001-01-01

    In the application of active magnetic bearings (AMB), one of the key problems to be solved is the safety and stability in the sense of rotor dynamics. The project related to the present paper deals with the method for analyzing bearing rotor systems with high rotation speed and specially supported by active magnetic bearings, and studies its rotor dynamics performance, including calculation of the natural frequencies with their distribution characteristics, and the critical speeds of the system. One of the targets of this project is to formulate a theory and method valid for the analysis of the dynamic performance of the active magnetic bearing-rotor system by combining the traditional theory and method of rotor dynamics with the analytical theory and design method based on modern control theory of the AMB system.

  10. Aeroelastic Modelling and Comparison of Advanced Active Flap Control Concepts for Load Reduction on the Upwind 5MW Wind Turbine

    NARCIS (Netherlands)

    Barlas, A.; Van Kuik, G.A.M.

    2009-01-01

    A newly developed comprehensive aeroelastic model is used to investigate active flap concepts on the Upwind 5MW reference wind turbine. The model is specially designed to facilitate distributed control concepts and advanced controller design. Different concepts of centralized and distributed control

  11. Aeroelastic modelling and comparison of advanced active flap control concepts for load reduction on the Upwind 5MW wind turbine

    NARCIS (Netherlands)

    Barlas, A.; van Kuik, G.A.M.

    2009-01-01

    A newly developed comprehensive aeroelastic model is used to investigate active flap concepts on the Upwind 5MW reference wind turbine. The model is specially designed to facilitate distributed control concepts and advanced controller design. Different concepts of centralized and distributed control

  12. Wind tunnel test on airfoil Riso-B1-18 with an Active Trailing Edge Flap

    DEFF Research Database (Denmark)

    Bak, Christian; Gaunaa, Mac; Andersen, Peter Bjørn;

    2010-01-01

    A wind tunnel test of the wind turbine airfoil Risø-B1-18 equipped with an Active Trailing Edge Flap (ATEF) was carried out. The ATEF was 9% of the total chord, made of piezo electric actuators attached to the trailing edge of a non-deformable airfoil and actuated using an (electric) amplifier...

  13. Load alleviation potential of active flaps and individual pitch control in a full design load basis

    DEFF Research Database (Denmark)

    Barlas, Athanasios; Bergami, Leonardo; Hansen, Morten Hartvig;

    2015-01-01

    The load alleviation potential of the Controllable Rubber Trailing Edge Flap (CRTEF) is verified on a full Design Load Basis (DLB) setup using the aeroelastic code HAWC2, and by investigating a flap configuration for the NREL 5MW Reference Wind Turbine (RWT) model. The performance of the CRTEF co...

  14. A Model Based Control methodology combining Blade Pitch and Adaptive Trailing Edge Flaps in a common framework

    DEFF Research Database (Denmark)

    Henriksen, Lars Christian; Bergami, Leonardo; Andersen, Peter Bjørn

    2013-01-01

    This work investigates how adaptive trailing edge flaps and classical blade pitch can work in concert using a model-based state space control formulation. The trade-off between load reduction and actuator activity is decided by setting different weights in the objective function used by the model......-based controller. The combined control approach allow to achieve higher load alleviations, furthermore, in the presence of e.g. deterioration of an actuator, it enables an online re-tuning of the workload distribution of blade pitch and trailing edge flaps, thus potentially increasing the smart rotor reliability....

  15. A Model Based Control methodology combining Blade Pitch and Adaptive Trailing Edge Flaps in a common framework

    DEFF Research Database (Denmark)

    This work investigates how adaptive trailing edge flaps and classical blade pitch can work in concert using a model-based state space control formulation. The trade-off between load reduction and actuator activity is decided by setting different weights in the objective function used by the model......-based controller. The combined control approach allow to achieve higher load alleviations, furthermore, in the presence of e.g. deterioration of an actuator, it enables an online re-tuning of the workload distribution of blade pitch and trailing edge flaps, thus potentially increasing the smart rotor reliability....

  16. Singular value decomposition of optically-mapped cardiac rotors and fibrillatory activity

    Science.gov (United States)

    Rabinovitch, A.; Biton, Y.; Braunstein, D.; Friedman, M.; Aviram, I.; Yandrapalli, S.; Pandit, S. V.; Berenfeld, O.

    2015-03-01

    Our progress of understanding how cellular and structural factors contribute to arrhythmia is hampered in part because of controversies as to whether a fibrillating heart is driven by a single, several, or multiple number of sources, whether they are focal or reentrant and how to localize them. Here we demonstrate how a novel usage of the neutral singular value decomposition (SVD) method enables the extraction of the governing spatial and temporal modes of excitation from a rotor and fibrillatory waves. Those modes highlight patterns and regions of organization in the midst of the otherwise seemingly random propagating excitation waves. We apply the method to experimental models of cardiac fibrillation in rabbit hearts. We show that SVD analysis is able to enhance the classification of the heart electrical patterns into regions harboring drivers in the form of fast reentrant activity and other regions of by-standing activity. This enhancement is accomplished without any prior assumptions regarding the spatial, temporal or spectral properties of those drivers. The analysis corroborates that the dominant mode has the highest activation rate and further reveals a new feature: a transfer of modes from the driving to passive regions resulting in a partial reaction of the passive region to the driving region.

  17. Cyclic Control Optimization for a Smart Rotor

    DEFF Research Database (Denmark)

    Bergami, Leonardo; Henriksen, Lars Christian

    2012-01-01

    The paper presents a method to determine cyclic control trajectories for a smart rotor undergoing periodic-deterministic load variations. The control trajectories result from a constrained optimization problem, where the cost function to minimize is given by the variation of the blade root flapwise...... bending moment within a rotor revolution. The method is applied to a rotor equipped with trailing edge flaps, and capable of individual blade pitching. Results show that the optimized cyclic control significantly alleviates the load variations from periodic disturbances; the combination of both cyclic...

  18. Fractional Order PID Control of Rotor Suspension by Active Magnetic Bearings

    Directory of Open Access Journals (Sweden)

    Parinya Anantachaisilp

    2017-01-01

    Full Text Available One of the key issues in control design for Active Magnetic Bearing (AMB systems is the tradeoff between the simplicity of the controller structure and the performance of the closed-loop system. To achieve this tradeoff, this paper proposes the design of a fractional order Proportional-Integral-Derivative (FOPID controller. The FOPID controller consists of only two additional parameters in comparison with a conventional PID controller. The feasibility of FOPID for AMB systems is investigated for rotor suspension in both the radial and axial directions. Tuning methods are developed based on the evolutionary algorithms for searching the optimal values of the controller parameters. The resulting FOPID controllers are then tested and compared with a conventional PID controller, as well as with some advanced controllers such as Linear Quadratic Gausian (LQG and H ∞ controllers. The comparison is made in terms of various stability and robustness specifications, as well as the dimensions of the controllers as implemented. Lastly, to validate the proposed method, experimental testing is carried out on a single-stage centrifugal compressor test rig equipped with magnetic bearings. The results show that, with a proper selection of gains and fractional orders, the performance of the resulting FOPID is similar to those of the advanced controllers.

  19. Local correlations for flap gap oscillatory blowing active flow control technology

    Directory of Open Access Journals (Sweden)

    Cătălin NAE

    2010-09-01

    Full Text Available Active technology for oscillatory blowing in the flap gap has been tested at INCAS subsonic wind tunnel in order to evaluate this technology for usage in high lift systems with active flow control. The main goal for this investigation was to validate TRL level 4 for this technology and to extend towards flight testing. CFD analysis was performed in order to identify local correlations with experimental data and to better formulate a design criteria so that a maximum increase in lift is possible under given geometrical constraints. Reference to a proposed metric for noise evaluation is also given. This includes basic 2D flow cases and also 2.5D configurations. In 2.5D test cases this work has been extended so that the proposed system may be selected as a mature technology in the JTI Clean Sky, Smart Fixed Wing Aircraft ITD. Complex post-processing of the experimental and CFD data was mainly oriented towards system efficiency and TRL evaluation for this active technology.

  20. Foot and ankle reconstruction: an experience on the use of 14 different flaps in 226 cases.

    Science.gov (United States)

    Zhu, Yue-Liang; Wang, Yi; He, Xiao-Qing; Zhu, Min; Li, Fu-Bin; Xu, Yong-Qing

    2013-11-01

    The aim of this report was to present our experience on the use of different flaps for soft tissue reconstruction of the foot and ankle. From 2007 to 2012, the soft tissue defects of traumatic injuries of the foot and ankle were reconstructed using 14 different flaps in 226 cases (162 male and 64 female). There were 62 pedicled flaps and 164 free flaps used in reconstruction. The pedicled flaps included sural flap, saphenous flap, dorsal pedal neurocutaneous flap, pedicled peroneal artery perforator flap, pedicled tibial artery perforator flap, and medial plantar flap. The free flaps were latissimus musculocutaneous flap, anterolateral thigh musculocutaneous flap, groin flap, lateral arm flap, anterolateral thigh perforator flap, peroneal artery perforator flap, thoracdorsal artery perforator flap, medial arm perforator flap. The sensory nerve coaptation was not performed for all of flaps. One hundred and ninety-four cases were combined with open fractures. One hundred and sixty-two cases had tendon. Among 164 free flaps, 8 flaps were completely lost, in which the defects were managed by the secondary procedures. Among the 57 flaps for plantar foot coverage (25 pedicled flaps and 32 free flaps), ulcers were developed in 5 pedicled flaps and 6 free flaps after weight bearing, and infection was found in 14 flaps. The donor site complications were seen in 3 cases with the free anterolateral thigh perforator flap transfer. All of limbs were preserved and the patients regained walking and daily activities. All of patients except for one regained protective sensation from 3 to 12 months postoperatively. Our experience showed that the sural flap and saphenous flap could be good options for the coverage of the defects at malleolus, dorsal hindfoot and midfoot. Plantar foot, forefoot and large size defects could be reconstructed with free anterolateral thigh perforator flap. For the infected wounds with dead spce, the free latissimus dorsi musculocutaneous flap remained to

  1. Variable Parameters PD Control and Stability of a High Rate Rigid Rotor-Journal Active Magnetic Bearing System

    Institute of Scientific and Technical Information of China (English)

    LUO Kai

    2005-01-01

    Stability is a key problem that means whether a high rate rotor-active magnetic bearings system works reliably or not. Aiming at a bearings system described with nonlinear equations, this paper built a linear model according to the system behavior. Considering realization of the control system and behavior of a high rate rotor system (magnetic force is far smaller than input force produced by mass eccentricity) this paper proposes a design method of variable parameters PD control algorithm that can be used universally. The control system was simplified and a mass of adjusting work of control parameters was reduced. Analysis and simulation indicated that the bearings system could get a wider stable region of harmonic motion, and proved that the algorithm is robust and advanced. The control system can be realized because the winding electric currents are positive. The method is convenient for operation and can easily be used for engineering practice.

  2. Molecular Rotors

    Science.gov (United States)

    2006-10-31

    Molecular Dipolar Rotors on Insulating Surfaces," Salamanca , Spain. Trends in Nanotechnology Conference. September 5-9, 2003 [86] Laura I. Clarke, Mary Beth...Horansky at the Trends in Nanotechnology Conference, Salamanca , Spain (September 5-9, 2003). [145] Michl, J. “Unusual Molecules: Artificial Surface...temperature and frequency for difluorophenylene rotor crystal. Figure JP6. Monte Carlo results for the local potential asymmetry at

  3. Geometrical optimization of a hingeless deployment system for an active rotor blade

    NARCIS (Netherlands)

    Paternoster, Alexandre; Loendersloot, Richard; de Boer, Andries; Akkerman, Remko

    2013-01-01

    Deployment systems for the Gurney flap need to sustain large centrifugal loads and vibrations while maintaining precisely the displacement under aerodynamic loading. Designing such a mechanism relies on both the actuation technology and the link that transmits motion to the control surface. Flexible

  4. Active Control of Parametric Vibrations in Coupled Rotor-Blade Systems

    DEFF Research Database (Denmark)

    Christensen, Rene Hardam; Santos, Ilmar

    2003-01-01

    In rotor-blade systems basis as well as parametric vibration modes will appear due to the vibration coupling among flexible rotating blades and hub rigid body motion. Parametric vibration will typically occur when the hub operates at a constant angular velocity. Operating at constant velocity...

  5. Active vibration control of a rotor-bearing system based on dynamic stiffness

    Directory of Open Access Journals (Sweden)

    Andrés Blanco Ortega

    2010-01-01

    Full Text Available En este artículo se presenta un esquema de control activo de vibraciones para atenuar las amplitudes de vibración síncrona inducidas por el desbalance en un sistema rotorchumaceras; donde una de las chumaceras puede ser desplazada automáticamente para modificar la longitud efectiva del rotor, y como consecuencia, la rigidez del rotor. El control de la rigidez dinámica se basa en un análisis de la respuesta en frecuencia, control de velocidad y en el uso de esquemas de aceleración, para evadir las amplitudes de la vibración en la resonancia mientras el sistema rotatorio pasa (acelerado o desacelerado a través de una velocidad crítica. Se utiliza identificación algebraica para estimar el desbalance en línea, mientras el rotor es llevado a la velocidad de operación deseada. Algunas simulaciones numéricas y resultados experimentales son incluidos para mostrar las propiedades de la compensación del desbalance y la robustez del esquema de control activo de vibraciones propuesto, cuando el rotor se opera a una velocidad por encima de la primera velocidad crítica.

  6. Active tilting-pad journal bearings supporting flexible rotors: Part II–The model-based feedback-controlled lubrication

    DEFF Research Database (Denmark)

    Salazar, Jorge Andrés González; Santos, Ilmar

    2017-01-01

    This is part II of a twofold paper series dealing with the design and implementation of model-based controllers meant for assisting the hybrid and developing the feedback-controlled lubrication regimes in active tilting pad journal bearings (active TPJBs). In both papers theoretical and experimen......This is part II of a twofold paper series dealing with the design and implementation of model-based controllers meant for assisting the hybrid and developing the feedback-controlled lubrication regimes in active tilting pad journal bearings (active TPJBs). In both papers theoretical...... and experimental analyses are presented with focus on the reduction of rotor lateral vibration. This part is devoted to synthesising model-based LQG optimal controllers (LQR regulator + Kalman Filter) for the feedback-controlled lubrication and is based upon the mathematical model of the rotor-bearing system...... derived in part I. Results show further suppression of resonant vibrations when using the feedback-controlled or active lubrication, overweighting the reduction already achieved with hybrid lubrication, thus improving the whole machine dynamic performance....

  7. Rotordynamic Modelling and Response Characteristics of an Active Magnetic Bearing Rotor System

    Science.gov (United States)

    Free, April M.; Flowers, George T.; Trent, Victor S.

    1996-01-01

    Auxiliary bearings are a critical feature of any magnetic bearing system. They protect the soft iron core of the magnetic bearing during an overload or failure. An auxiliary bearing typically consists of a rolling element bearing or bushing with a clearance gap between the rotor and the inner race of the support. The dynamics of such systems can be quite complex. It is desired to develop a rotordynamic model which describes the dynamic behavior of a flexible rotor system with magnetic bearings including auxiliary bearings. The model is based upon an experimental test facility. Some simulation studies are presented to illustrate the behavior of the model. In particular, the effects of introducing sideloading from the magnetic bearing when one coil fails is studied. These results are presented and discussed.

  8. Optimal deployment schedule of an active twist rotor for performance enhancement and vibration reduction in high-speed flights

    Directory of Open Access Journals (Sweden)

    Young H. YOU

    2017-08-01

    Full Text Available The best active twist schedules exploiting various waveform types are sought taking advantage of the global search algorithm for the reduction of hub vibration and/or power required of a rotor in high-speed conditions. The active twist schedules include two non-harmonic inputs formed based on segmented step functions as well as the simple harmonic waveform input. An advanced Particle Swarm assisted Genetic Algorithm (PSGA is employed for the optimizer. A rotorcraft Computational Structural Dynamics (CSD code CAMRAD II is used to perform the rotor aeromechanics analysis. A Computation Fluid Dynamics (CFD code is coupled with CSD for verification and some physical insights. The PSGA optimization results are verified against the parameter sweep study performed using the harmonic actuation. The optimum twist schedules according to the performance and/or vibration reduction strategy are obtained and their optimization gains are compared between the actuation cases. A two-phase non-harmonic actuation schedule demonstrates the best outcome in decreasing the power required while a four-phase non-harmonic schedule results in the best vibration reduction as well as the simultaneous reductions in the power required and vibration. The mechanism of reduction to the performance gains is identified illustrating the section airloads, angle-of-attack distribution, and elastic twist deformation predicted by the present approaches.

  9. Retrospective study of reverse dorsal metacarpal flap and compound flap: a review of 122 cases

    Institute of Scientific and Technical Information of China (English)

    LU Lai-jin; GONG Xu; LIU Zhi-gang; ZHANG Zhi-xin

    2006-01-01

    Objective:To evaluate the clinical application and discuss the operative indication of the reverse dorsal metacarpal flap and its compound flap on the skin defects of hand.Methods: From 1990 to 2003, we applied the reverse dorsal metacarpal flap and its compound flap to repair soft tissue defects of fingers in 122 cases, which included 90cases of the reverse metacarpal flap and 32 cases of its compound flaps with tendon grafts, nerve grafts or bone grafts. Based on the follow-up observations, we analyzed the indications of the reverse metacarpal flap and its compound flaps, the postoperative contours, flap colors and textures in comparison to contralateral fingers retrospectively.Results: In the series of 122 cases, flaps survived and the donor site defects were closed directly. The follow-up period ranged from 1-12 years. The postoperative contours,colors and textures of the flaps and its compound flaps were similar to those of normal fingers, although linear scar remained. According to standards of sense recovery(British Medical Research Council, BMRC ), the sense function of the flaps resumed S3 after operation for 1 year.In 10 cases with the tendon defects treated by the flap with tendon grafts, function of flexion-extension of fingers resumed 50%-75% in comparison to the contralateral fingers using the method of measurement of total active motion. In 7 cases with the phalangeal nonunion or bone defects treated by the flap with bone grafts, union occurred after operation for 3 months.Conclusions: To soft tissue defects on fingers with bone or tendon exposure, the reverse metacarpal flap and its compound flap are a better choice for repairing. The range of repairing is up to the distal interphalangeal joint of fingers. The second dorsal metacarpal artery is more consistent and larger as the choice of vascular pedicle, in comparison with other dorsal metacarpal arteries.Postoperative flap color and texture are similar to normal fingers.

  10. An experimental and analytical investigation of stall effects on flap-lag stability in forward flight

    Science.gov (United States)

    Nagabhushanam, J.; Gaonkar, Gopal H.; Mcnulty, Michael J.

    1987-01-01

    Experiments have been performed with a 1.62 m diameter hingeless rotor in a wind tunnel to investigate flap-lag stability of isolated rotors in forward flight. The three-bladed rotor model closely approaches the simple theoretical concept of a hingeless rotor as a set of rigid, articulated flap-lag blades with offset and spring restrained flap and lag hinges. Lag regressing mode stability data was obtained for advance ratios as high as 0.55 for various combinations of collective pitch and shaft angle. The prediction includes quasi-steady stall effects on rotor trim and Floquet stability analyses. Correlation between data and prediction is presented and is compared with that of an earlier study based on a linear theory without stall effects. While the results with stall effects show marked differences from the linear theory results, the stall theory still falls short of adequate agreement with the experimental data.

  11. Dynamic characteristics of the rotor in a magnetically suspended control moment gyroscope with active magnetic bearing and passive magnetic bearing.

    Science.gov (United States)

    Tang, Jiqiang; Xiang, Biao; Zhang, Yongbin

    2014-07-01

    For a magnetically suspended control moment gyroscope, stiffness and damping of magnetic bearing will influence modal frequency of a rotor. In this paper the relationship between modal frequency and stiffness and damping has been investigated. The mathematic calculation model of axial passive magnetic bearing (PMB) stiffness is developed. And PID control based on internal model control is introduced into control of radial active magnetic bearing (AMB), considering the radial coupling of axial PMB, a mathematic calculation model of stiffness and damping of radial AMB is established. According to modal analysis, the relationship between modal frequency and modal shapes is achieved. Radial vibration frequency is mainly influenced by stiffness of radial AMB; however, when stiffness increases, radial vibration will disappear and a high frequency bending modal will appear. Stiffness of axial PMB mainly affects the axial vibration mode, which will turn into high-order bending modal. Axial PMB causes bigger influence on torsion modal of the rotor. Copyright © 2014 ISA. Published by Elsevier Ltd. All rights reserved.

  12. Fasciocutaneous flaps

    NARCIS (Netherlands)

    D.E. Tolhurst (David)

    1988-01-01

    textabstractAbout that time the concept of independent myocutaneous vascular territories (Me Craw and Dibbell, 1977) was beginning to take hold but the deep fascia, sandwiched between muscles and the skin, was largely regarded as an isolating layer of dense, avascular fibrous tissue from which flaps

  13. Unbalanced Magnetic Pull Effect on Stiffness Models of Active Magnetic Bearing due to Rotor Eccentricity in Brushless DC Motor Using Finite Element Method

    Directory of Open Access Journals (Sweden)

    Bangcheng Han

    2013-01-01

    Full Text Available We firstly report on an investigation into the unbalanced magnetic pull (UMP effect on the static stiffness models of radial active magnetic bearing (RAMB in brushless DC motor (BDCM in no-loaded and loaded conditions using the finite element method (FEM. The influences of the UMP on the force-control current, force-position, current stiffness, and position stiffness of RAMB are clarified in BDCM with 100 kW rated power. We found the position stiffness to be more susceptible to UMP. The primary source of UMP is the permanent magnets of BDCM. In addition, the performance of RAMB is affected by the UMP ripples during motor commutation and also periodically affected by the angular position of rotor. The characteristic curves of RAMB force versus control current (or rotor position and angular position of rotor affected by the UMP are given. The method is useful in design and optimization of RAMB in magnetically suspended BDCMs.

  14. An advanced stochastic model for threshold crossing studies of rotor blade vibrations.

    Science.gov (United States)

    Gaonkar, G. H.; Hohenemser, K. H.

    1972-01-01

    A stochastic model to analyze turbulence-excited rotor blade vibrations, previously described by Gaonkar et al. (1971), is generalized to include nonuniformity of the atmospheric turbulence velocity across the rotor disk in the longitudinal direction. The results of the presented analysis suggest that the nonuniformity of the vertical turbulence over the rotor disk is of little influence on the random blade flapping response, at least as far as longitudinal nonuniformity is concerned.

  15. Active load reduction by means of trailing edge flaps on a wind turbine blade

    DEFF Research Database (Denmark)

    Couchman, Ian; Castaignet, Damien; Poulsen, Niels Kjølstad

    2014-01-01

    This paper presents the blade fatigue load reduction achieved with a trailing edge flap during a full scale test on a Vestas V27 wind turbine. A frequency-weighted linear model predictive control (MPC) is tuned to decrease flapwise blade root fatigue loads at the frequencies where most of the bla...... was first tested in aero-servo-elastic simulations, before being implemented on a Vestas V27 wind turbine. Consistent load reduction is achieved during the full-scale test. An average of 14% flapwise blade root fatigue load reduction is measured....

  16. Dynamic Gust Load Analysis for Rotors

    Directory of Open Access Journals (Sweden)

    Yuting Dai

    2016-01-01

    Full Text Available Dynamic load of helicopter rotors due to gust directly affects the structural stress and flight performance for helicopters. Based on a large deflection beam theory, an aeroelastic model for isolated helicopter rotors in the time domain is constructed. The dynamic response and structural load for a rotor under the impulse gust and slope-shape gust are calculated, respectively. First, a nonlinear Euler beam model with 36 degrees-of-freedoms per element is applied to depict the structural dynamics for an isolated rotor. The generalized dynamic wake model and Leishman-Beddoes dynamic stall model are applied to calculate the nonlinear unsteady aerodynamic forces on rotors. Then, we transformed the differential aeroelastic governing equation to an algebraic one. Hence, the widely used Newton-Raphson iteration algorithm is employed to simulate the dynamic gust load. An isolated helicopter rotor with four blades is studied to validate the structural model and the aeroelastic model. The modal frequencies based on the Euler beam model agree well with published ones by CAMRAD. The flap deflection due to impulse gust with the speed of 2m/s increases twice to the one without gust. In this numerical example, results indicate that the bending moment at the blade root is alleviated due to elastic effect.

  17. Identification of helicopter rotor dynamic models

    Science.gov (United States)

    Molusis, J. A.; Bar-Shalom, Y.; Warmbrodt, W.

    1983-01-01

    A recursive, extended Kalman-filter approach is applied to the identifiction of rotor damping levels of representative helicopter dynamic systems. The general formulation of the approach is presented in the context of a typically posed stochastic estimation problem, and the method is analytically applied to determining the damping levels of a coupled rotor-body system. The identified damping covergence characteristics are studied for sensitivity to both constant-coefficient and periodic-coefficient measurement models, process-noise covariance levels, and specified initial estimates of the rotor-system damping. A second application of the method to identifying the plant model for a highly damped, isolated flapping blade with a constant-coefficient state model (hover) and a periodic-coefficient state model (forward flight) is also investigated. The parameter-identification capability is evaluated for the effect of periodicity on the plant model coefficients and the influence of different measurement noise levels.

  18. Solid State Adaptive Rotor Using Postbuckled Precompressed, Bending-Twist Coupled Piezoelectric Actuator Elements

    Directory of Open Access Journals (Sweden)

    Ronald M. Barrett

    2012-01-01

    Full Text Available This paper is centered on a new actuation mechanism which is integrated on a solid state rotor. This paper outlines the application of such a system via a Post-Buckled Precompression (PBP technique at the end of a twist-active piezoelectric rotor blade actuator. The basic performance of the system is handily modeled by using laminated plate theory techniques. A dual cantilevered spring system was used to increasingly null the passive stiffness of the root actuator along the feathering axis of the rotor blade. As the precompression levels were increased, it was shown that corresponding blade pitch levels also increased. The PBP cantilever spring system was designed so as to provide a high level of stabilizing pitch-flap coupling and inherent resistance to rotor propeller moments. Experimental testing showed pitch deflections increasing from just 8° peak-to-peak deflections at 650 V/mm field strength to more than 26° at the same field strength with design precompression levels. Dynamic testing showed the corner frequency of the linear system coming down from 63 Hz (3.8/rev to 53 Hz (3.2/rev. Thrust coefficients manipulation levels were shown to increase from 0.01 to 0.028 with increasing precompression levels. The paper concludes with an overall assessment of the actuator design.

  19. Prediction of BVI Noise for an Active Twist Rotor Using a Loosely Coupled CFD/CSD Method and Comparison to Experimental Data

    Science.gov (United States)

    Fogarty, David E.; Wilbur, Matthew L.; Sekula, Martin K.; Boyd, David Douglas, Jr.

    2012-01-01

    Numerical predictions of the acoustic characteristics of an Active Twist Rotor (ATR), using two methods to compute the rotor blade aerodynamics and elastic blade motion are compared to experimental data from a wind tunnel test in the NASA Langley Transonic Dynamics Tunnel (TDT) in 2000. The first method, a loosely coupled iterative method, utilizes the Computational Fluid Dynamics (CFD) code OVERFLOW 2 and the Computational Structural Dynamics (CSD) code CAMRAD II. The second method utilizes the CAMRAD II free-wake model only. The harmonic active-twist control to the main rotor blade system is identified with three parameters - harmonic actuation frequency, actuation amplitude, and control phase angle. The resulting aerodynamics and blade motion data from the two methods are then used in the acoustics code PSU-WOPWOP to predict acoustic pressure on a spherical array of equally spaced observers surrounding the rotor. This spherical distribution of pressure is used to compute the sound power level representing baseline and actuated conditions. Sound power levels for three categories of noise are defined as - blade-vortex interaction sound power level (BVIPWL), low frequency sound power level (LFPWL), and overall sound power level, OAPWL. Comparisons with measured data indicate the CFD/CSD analysis successfully captures the trends in sound power levels and the effects of active-twist control at advance ratios of 0.14 and 0.17. The free-wake model predictions show inconsistent sound power levels relative to the trends in the experimental and CFD data. This paper presents the first ever comparison between CFD/CSD acoustic predictions for an active-twist rotor and experimental measurements.

  20. Rotor Embedded with Shape Memory Alloy Wires

    Directory of Open Access Journals (Sweden)

    K. Gupta

    2000-01-01

    Full Text Available In the present analysis, the fundamental natural frequency of a Jeffcott and a two-mass rotor with fibre reinforced composite shaft embedded with shape memory alloy (SMA wires is evaluated by Rayleigh's procedure. The flexibility of rotor supports is taken into account. The effect of three factors, either singly or in combination with each other, on rotor critical speed is studied. The three factors are: (i increase in Young's modulus of SMA (NITINOL wires when activated, (ii tension in wires because of phase recovery stresses, and (iii variation of support stiffness by three times because of activation of SMA in rotor supports. It is shown by numerical examples that substantial variation in rotor critical speeds can be achieved by a combination of these factors which can be effectively used to avoid resonance during rotor coast up/down.

  1. Selected topics on the active control of helicopter aeromechanical and vibration problems

    Science.gov (United States)

    Friedmann, Peretz P.

    1994-01-01

    This paper describes in a concise manner three selected topics on the active control of helicopter aeromechanical and vibration problems. The three topics are as follows: (1) the active control of helicopter air-resonance using an LQG/LTR approach; (2) simulation of higher harmonic control (HHC) applied to a four bladed hingeless helicopter rotor in forward flight; and (3) vibration suppression in forward flight on a hingeless helicopter rotor using an actively controlled, partial span, trailing edge flap, which is mounted on the blade. Only a few selected illustrative results are presented. The results obtained clearly indicate that the partial span, actively controlled flap has considerable potential for vibration reduction in helicopter rotors.

  2. The interpectoral fascia flap.

    Science.gov (United States)

    Beer, Gertrude M; Manestar, Andrew; Manestar, Mirjana

    2008-09-01

    Despite the great number of pedicled and free flaps that are available for defect and contour repair, the number of fascia flaps with an axial blood supply are sparse. Such flaps with their gliding function are mandatory, whenever coverage with very thin, well-vascularized tissue is necessary. To the currently established fascia flaps, (the temporoparietal fascia flap, the radial forearm fascia flap, the lateral arm fascia flap, and the serratus anterior fascia flap), we want to add a new fascia flap, the interpectoral fascia flap. We dissected the interpectoral fascia flap from 20 cadavers. In each of the 40 hemichests, the trunk of the thoracoacromial vessels was selectively injected with red polyurethane and the tissue containing the pectoral branches was separated from the overlying pectoralis major muscle and converted into an independent fascia flap. The maximum flap length was 13.5 cm and the maximum breadth was 10.3 cm. The length of the vascular pedicle before entering the flap was 3.9 cm +/- 1.4 cm with a range of 1.5-6.8 cm. Concerning the arc of rotation, all 40 flaps reached the posterior axillary fold, and 29 flaps (73%) reached the mandibular border. This new fascia flap has applications as pedicled and as free flap. The pedicled flap is used in the neck region, in the axillary region and as gliding tissue between the nipple-areola complex and the pectoralis major muscle. The usage of the fascia flap as a free flap has similar characteristics as the other fascia flaps.

  3. Structural analysis of wind turbine rotors for NSF-NASA Mod-0 wind power system

    Science.gov (United States)

    Spera, D. A.

    1976-01-01

    Preliminary estimates are presented of vibratory loads and stresses in hingeless and teetering rotors for the proposed NSF-NASA Mod-0 wind power system. Preliminary blade design utilizes a tapered tubular aluminum spar which supports nonstructural aluminum ribs and skin and is joined to the rotor hub by a steel shank tube. Stresses in the shank of the blade are calculated for static, rated, and overload operating conditions. Blade vibrations were limited to the fundamental flapping modes, which were elastic cantilever bending for hingeless rotor blades and rigid-body rotation for teetering rotor blades. The MOSTAB-C computer code was used to calculate aerodynamic and mechanical loads. The teetering rotor has substantial advantages over the hingeless rotor with respect to shank stresses, fatigue life, and tower loading. The hingeless rotor analyzed does not appear to be structurally stable during overloads.

  4. Hydrodynamic Effects on Modeling and Control of a High Temperature Active Magnetic Bearing Pump with a Canned Rotor

    Energy Technology Data Exchange (ETDEWEB)

    Melin, Alexander M [ORNL; Kisner, Roger A [ORNL; Fugate, David L [ORNL; Holcomb, David Eugene [ORNL

    2015-01-01

    Embedding instrumentation and control Embedding instrumentation and control (I\\&C) at the component level in nuclear power plants can improve component performance, lifetime, and resilience by optimizing operation, reducing the constraints on physical design, and providing on-board prognostics and diagnostics. However, the extreme environments that many nuclear power plant components operate in makes embedding instrumentation and control at the component level difficult. Successfully utilizing embedded I\\&C requires developing a deep understanding of the system's dynamics and using that knowledge to overcome material and physical limitations imposed by the environment. In this paper, we will develop a coupled dynamic model of a high temperature (700 $^\\circ$C) canned rotor pump that incorporates rotordynamics, hydrodynamics, and active magnetic bearing dynamics. Then we will compare two control design methods, one that uses a simplified decoupled model of the system and another that utilizes the full coupled system model. It will be seen that utilizing all the available knowledge of the system dynamics in the controller design yield an order of magnitude improvement in the magnitude of the magnetic bearing response to disturbances at the same level of control effort, a large reduction in the settling time of the system, and a smoother control action.

  5. Investigation of Maximum Blade Loading Capability of Lift-Offset Rotors

    Science.gov (United States)

    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.

  6. Open Rotor Development

    Science.gov (United States)

    Van Zante, Dale E.; Rizzi, Stephen A.

    2016-01-01

    The ERA project executed a comprehensive test program for Open Rotor aerodynamic and acoustic performance. System studies used the data to estimate the fuel burn savings and acoustic margin for an aircraft system with open rotor propulsion. The acoustic measurements were used to produce an auralization that compares the legacy blades to the current generation of open rotor designs.

  7. Wind energy conversion. Volume VI. Nonlinear response of wind turbine rotor

    Energy Technology Data Exchange (ETDEWEB)

    Chopra, I.

    1978-09-01

    The nonlinear equations of motor for a rigid rotor restrained by three flexible springs representing, respectively, the flapping, lagging, and feathering motions are derived using Lagrange's equations, for arbitrary angular rotations. These are reduced to a consistent set of nonlinear equations using nonlinear terms up to third order. The complete analysis is divided into three parts, A, B, and C. Part A consists of forced response of two-degree flapping-lagging rotor under the excitation of pure gravitational field (i.e., no aerodynamic forces). In Part B, the effect of aerodynamic forces on the dynamic response of two-degree flapping-lagging rotor is investigated. In Part C, the effect of third degree of motion, feathering, is considered.

  8. Control of a flexible rotor active magnetic bearing test rig:a characteristic model based all-coefficient adaptive control approach

    Institute of Scientific and Technical Information of China (English)

    Long DI; Zongli LIN

    2014-01-01

    Active magnetic bearings (AMBs) have found a wide range of applications in high-speed rotating machinery industry. The instability and nonlinearity of AMBs make controller designs difficult, and when AMBs are coupled with a flexible rotor, the resulting complex dynamics make the problems of stabilization and disturbance rejection, which are critical for a stable and smooth operation of the rotor AMB system, even more difficult. Proportional-integral-derivative (PID) control dominates the current AMB applications in the field. Even though PID controllers are easy to implement, there are critical performance limitations associated with them that prevent the more advanced applications of AMBs, which usually require stronger robustness and performance offered by modern control methods such as H-infinity control andμ-synthesis. However, these advanced control designs rely heavily on the relatively accurate plant models and uncertainty characterizations, which are sometimes difficult to obtain. In this paper, we explore and report on the use of the characteristic model based all-coefficient adaptive control method to stabilize a flexible rotor AMB test rig. In spite of the simple structure of such a characteristic model based all-coefficient adaptive controller, both simulation and experimental results show its strong performance.

  9. A VORTEX MODEL OF A HELICOPTER ROTOR

    Directory of Open Access Journals (Sweden)

    Valentin BUTOESCU

    2009-06-01

    Full Text Available A vortex model of a helicopter rotor is presented. Each blade of the rotor has three degrees of freedom: flapping, lagging and feathering. The motions after each degree of freedom are also known for all blades. The blade is modelled as a thin vortex surface. The wakes are free fluid surfaces. A system of five equations are obtained: the first one is the integral equation of the lifting surface (rotor, the next three describe the wakes motion, and the last one relates the vortex strength on the wakes and the variation of vorticity on the rotor. A numerical solution of this system is presented. To avoid the singularities that can occur due to the complexity of vortex system, a desingularized model of the vortex core was adopted. A Mathcad worksheet containing the method has been written.The original contribution of the work. The calculation method of the motion of the wakes free vortex system, the development of the vortex cores in time and a new method to approximate the aerodynamic influence of remoted wake regions.

  10. Numerical Analysis of Helicopter Rotor Hovering in Close Proximity to the Ground with a Wall

    Science.gov (United States)

    Itoga, Noriaki; Iboshi, Naohiro; Horimoto, Mitsumasa; Saito, Shigeru; Tanabe, Yasutada

    In rescue operations and emergency medical services, helicopters are frequently required to operate near the ground with obstacles such as buildings and sidewalls of highway. In this paper, numerical analysis of helicopter rotor hovering in close proximity to the ground with an obstacle is done by solving unsteady 3D compressible Euler equations with an overlapped grid system. The obstacle is simulated by a wall vertically set up on the ground. The parameters for numerical analysis are the rotor height and distance from the rotor-hub-center to the wall. The effects of combinations of these parameters on the flowfields around the rotor, inflow distributions on the rotor disc and behaviors of blade flapping motion are discussed. It is also clarified the cause that the helicopter rotor hovering in close proximity to the ground with a wall does not have the enough ground effect depending on the combinations of these parameters.

  11. Molecular Rotors as Switches

    Directory of Open Access Journals (Sweden)

    Kang L. Wang

    2012-08-01

    Full Text Available The use of a functional molecular unit acting as a state variable provides an attractive alternative for the next generations of nanoscale electronics. It may help overcome the limits of conventional MOSFETd due to their potential scalability, low-cost, low variability, and highly integratable characteristics as well as the capability to exploit bottom-up self-assembly processes. This bottom-up construction and the operation of nanoscale machines/devices, in which the molecular motion can be controlled to perform functions, have been studied for their functionalities. Being triggered by external stimuli such as light, electricity or chemical reagents, these devices have shown various functions including those of diodes, rectifiers, memories, resonant tunnel junctions and single settable molecular switches that can be electronically configured for logic gates. Molecule-specific electronic switching has also been reported for several of these device structures, including nanopores containing oligo(phenylene ethynylene monolayers, and planar junctions incorporating rotaxane and catenane monolayers for the construction and operation of complex molecular machines. A specific electrically driven surface mounted molecular rotor is described in detail in this review. The rotor is comprised of a monolayer of redox-active ligated copper compounds sandwiched between a gold electrode and a highly-doped P+ Si. This electrically driven sandwich-type monolayer molecular rotor device showed an on/off ratio of approximately 104, a read window of about 2.5 V, and a retention time of greater than 104 s. The rotation speed of this type of molecular rotor has been reported to be in the picosecond timescale, which provides a potential of high switching speed applications. Current-voltage spectroscopy (I-V revealed a temperature-dependent negative differential resistance (NDR associated with the device. The analysis of the device

  12. Multicyclic jet-flap control for alleviation of helicopter blade stresses and fuselage vibration

    Science.gov (United States)

    Mccloud, J. L., III; Kretz, M.

    1974-01-01

    Results of wind tunnel tests of a 12-meter-diameter rotor utilizing multicyclic jet-flap control deflection are presented. Analyses of these results are shown, and experimental transfer functions are determined by which optimal control vectors are developed. These vectors are calculated to eliminate specific harmonic bending stresses, minimize rms levels (a measure of the peak-to-peak stresses), or minimize vertical vibratory loads that would be transmitted to the fuselage. Although the specific results and the ideal control vectors presented are for a specific jet-flap driven rotor, the method employed for the analyses is applicable to similar investigations. A discussion of possible alternative methods of multicyclic control by mechanical flaps or nonpropulsive jet-flaps is presented.

  13. Development of an aeroelastic methodology for surface morphing rotors

    Science.gov (United States)

    Cook, James R.

    Helicopter performance capabilities are limited by maximum lift characteristics and vibratory loading. In high speed forward flight, dynamic stall and transonic flow greatly increase the amplitude of vibratory loads. Experiments and computational simulations alike have indicated that a variety of active rotor control devices are capable of reducing vibratory loads. For example, periodic blade twist and flap excitation have been optimized to reduce vibratory loads in various rotors. Airfoil geometry can also be modified in order to increase lift coefficient, delay stall, or weaken transonic effects. To explore the potential benefits of active controls, computational methods are being developed for aeroelastic rotor evaluation, including coupling between computational fluid dynamics (CFD) and computational structural dynamics (CSD) solvers. In many contemporary CFD/CSD coupling methods it is assumed that the airfoil is rigid to reduce the interface by single dimension. Some methods retain the conventional one-dimensional beam model while prescribing an airfoil shape to simulate active chord deformation. However, to simulate the actual response of a compliant airfoil it is necessary to include deformations that originate not only from control devices (such as piezoelectric actuators), but also inertial forces, elastic stresses, and aerodynamic pressures. An accurate representation of the physics requires an interaction with a more complete representation of loads and geometry. A CFD/CSD coupling methodology capable of communicating three-dimensional structural deformations and a distribution of aerodynamic forces over the wetted blade surface has not yet been developed. In this research an interface is created within the Fully Unstructured Navier-Stokes (FUN3D) solver that communicates aerodynamic forces on the blade surface to University of Michigan's Nonlinear Active Beam Solver (UM/NLABS -- referred to as NLABS in this thesis). Interface routines are developed for

  14. Dynamic Analysis of a Helicopter Rotor by Dymore Program

    Science.gov (United States)

    Doğan, Vedat; Kırca, Mesut

    The dynamic behavior of hingeless and bearingless blades of a light commercial helicopter which has been under design process at ITU (İstanbul Technical University, Rotorcraft Research and Development Centre) is investigated. Since the helicopter rotor consists of several parts connected to each other by joints and hinges; rotors in general can be considered as an assembly of the rigid and elastic parts. Dynamics of rotor system in rotation is complicated due to coupling of elastic forces (bending, torsion and tension), inertial forces, control and aerodynamic forces on the rotor blades. In this study, the dynamic behavior of the rotor for a real helicopter design project is analyzed by using DYMORE. Blades are modeled as elastic beams, hub as a rigid body, torque tubes as rigid bodies, control links as rigid bodies plus springs and several joints. Geometric and material cross-sectional properties of blades (Stiffness-Matrix and Mass-Matrix) are calculated by using VABS programs on a CATIA model. Natural frequencies and natural modes of the rotating (and non-rotating) blades are obtained by using DYMORE. Fan-Plots which show the variation of the natural frequencies for different modes (Lead-Lag, Flapping, Feathering, etc.) vs. rotor RPM are presented.

  15. Development of a Wind Turbine Rotor Flow Panel Method

    Energy Technology Data Exchange (ETDEWEB)

    Van Garrel, A. [ECN Wind Energy, Petten (Netherlands)

    2011-12-15

    The ongoing trend towards larger wind turbines intensifies the demand for more physically realistic wind turbine rotor aerodynamics models that can predict the detailed transient pressure loadings on the rotor blades better than current engineering models. In this report the mathematical, numerical, and practical aspects of a new wind turbine rotor flow simulation code is described. This wind turbine simulation code is designated ROTORFLOW. In this method the fluid dynamics problem is solved through a boundary integral equation which reduces the problem to the surface of the configuration. The derivation of the integral equations is described as well as the assumptions made to arrive at them starting with the full Navier-Stokes equations. The basic numerical aspects in the solution method are described and a verification study is performed to confirm the validity of the implementation. Example simulations with the code show the flow solutions for a stationary wing and for a rotating wing in yawed conditions. With the ROTORFLOW code developed in this project it is possible to simulate the unsteady flow around wind turbine rotors in yawed conditions and obtain detailed pressure distributions, and thus blade loadings, at the surface of the blades. General rotor blade geometries can be handled, opening the way to the detailed flow analysis of winglets, partial span flaps, swept blade tips, etc. The ROTORFLOW solver only requires a description of the rotor surface which keeps simulation preparation time short, and makes it feasible to use the solver in the design iteration process.

  16. The submental island flap.

    Science.gov (United States)

    Sterne, G D; Januszkiewicz, J S; Hall, P N; Bardsley, A F

    1996-03-01

    The submental island flap is a reliable source of skin of excellent colour, contour and texture match for facial resurfacing and leaves a well hidden donor site. The flap is safe, rapid and simple to raise. We report on its use in 12 cases of facial or intraoral reconstruction. Complications were few. However, there was one case of complete flap loss following its use in a reverse flow manner, due to the presence of an unreported, but constant, valve in the venous system of the face. We believe this flap to be a worthwhile addition to the existing surgical armamentarium.

  17. Propeller TAP flap

    DEFF Research Database (Denmark)

    Thomsen, Jørn Bo; Bille, Camilla; Wamberg, Peter

    2013-01-01

    The aim of this study was to examine if a propeller thoracodorsal artery perforator (TAP) flap can be used for breast reconstruction. Fifteen women were reconstructed using a propeller TAP flap, an implant, and an ADM. Preoperative colour Doppler ultrasonography was used for patient selection...... major complications needing additional surgery. One flap was lost due to a vascular problem. Breast reconstruction can be performed by a propeller TAP flap without cutting the descending branch of the thoracodorsal vessels. However, the authors would recommend that a small cuff of muscle is left around...

  18. Open Rotor Aeroacoustic Modelling

    Science.gov (United States)

    Envia, Edmane

    2012-01-01

    Owing to their inherent fuel efficiency, there is renewed interest in developing open rotor propulsion systems that are both efficient and quiet. The major contributor to the overall noise of an open rotor system is the propulsor noise, which is produced as a result of the interaction of the airstream with the counter-rotating blades. As such, robust aeroacoustic prediction methods are an essential ingredient in any approach to designing low-noise open rotor systems. To that end, an effort has been underway at NASA to assess current open rotor noise prediction tools and develop new capabilities. Under this effort, high-fidelity aerodynamic simulations of a benchmark open rotor blade set were carried out and used to make noise predictions via existing NASA open rotor noise prediction codes. The results have been compared with the aerodynamic and acoustic data that were acquired for this benchmark open rotor blade set. The emphasis of this paper is on providing a summary of recent results from a NASA Glenn effort to validate an in-house open noise prediction code called LINPROP which is based on a high-blade-count asymptotic approximation to the Ffowcs-Williams Hawkings Equation. The results suggest that while predicting the absolute levels may be difficult, the noise trends are reasonably well predicted by this approach.

  19. Cervicofacial flap revisited

    Directory of Open Access Journals (Sweden)

    Dhananjay V. Nakade

    2016-11-01

    Conclusions: Cervicofacial flap is simple, easy to operate, consume less operating time as compared to microvascular flap. It is less complicated and especially useful in diabetic, hypertensives and old debilitated patients with high risk of anaesthesia. [Int J Res Med Sci 2016; 4(11.000: 4669-4674

  20. Pedicled perforator flaps

    DEFF Research Database (Denmark)

    Demirtas, Yener; Ozturk, Nuray; Kelahmetoglu, Osman;

    2009-01-01

    Described in this study is a surgical concept that supports the "consider and use a pedicled perforator flap whenever possible and indicated" approach to reconstruct a particular skin defect. The operation is entirely free-style; the only principle is to obtain a pedicled perforator flap to recon......Described in this study is a surgical concept that supports the "consider and use a pedicled perforator flap whenever possible and indicated" approach to reconstruct a particular skin defect. The operation is entirely free-style; the only principle is to obtain a pedicled perforator flap...... more practical and creative to use a free-style manner during pedicled perforator flap surgery, instead of being obliged to predefined templates for this type of procedure....

  1. Large Rotor Test Apparatus

    Data.gov (United States)

    Federal Laboratory Consortium — This test apparatus, when combined with the National Full-Scale Aerodynamics Complex, produces a thorough, full-scale test capability. The Large Rotor Test Apparatus...

  2. Reducing rotor weight

    Energy Technology Data Exchange (ETDEWEB)

    Cheney, M.C. [PS Enterprises, Inc., Glastonbury, CT (United States)

    1997-12-31

    The cost of energy for renewables has gained greater significance in recent years due to the drop in price in some competing energy sources, particularly natural gas. In pursuit of lower manufacturing costs for wind turbine systems, work was conducted to explore an innovative rotor designed to reduce weight and cost over conventional rotor systems. Trade-off studies were conducted to measure the influence of number of blades, stiffness, and manufacturing method on COE. The study showed that increasing number of blades at constant solidity significantly reduced rotor weight and that manufacturing the blades using pultrusion technology produced the lowest cost per pound. Under contracts with the National Renewable Energy Laboratory and the California Energy Commission, a 400 kW (33m diameter) turbine was designed employing this technology. The project included tests of an 80 kW (15.5m diameter) dynamically scaled rotor which demonstrated the viability of the design.

  3. Translational damping on high-frequency flapping wings

    Science.gov (United States)

    Parks, Perry A.

    Flapping fliers such as insects and birds depend on passive translational and rotational damping to terminate quick maneuvers and to provide a source of partial stability in an otherwise unstable dynamic system. Additionally, passive translational and rotational damping reduce the amount of active kinematic changes that must be made to terminate maneuvers and maintain stability. The study of flapping-induced damping phenomena also improves the understanding of micro air vehicle (MAV) dynamics needed for the synthesis of effective flight control strategies. Aerodynamic processes which create passive translational and rotational damping as a direct result of symmetric flapping with no active changes in wing kinematics have been previously studied and were termed flapping counter-force (FCF) and flapping counter-torque (FCT), respectively. In this first study of FCF measurement in air, FCF generation is measured using a pendulum system designed to isolate and measure the relationship of translational flapping-induced damping with wingbeat frequency for a 2.86 gram mechanical flapper equipped with real cicada wings. Analysis reveals that FCF generation and wingbeat frequency are directly proportional, as expected from previous work. The quasi-steady FCF model using Blade-Element-Theory is used as an estimate for translational flapping-induced damping. In most cases, the model proves to be accurate in predicting the relationship between flapping-induced damping and wingbeat frequency. "Forward-backward" motion proves to have the strongest flapping-induced damping while "up-down" motion has the weakest.

  4. Repair of large full-thickness cartilage defect by activating endogenous peripheral blood stem cells and autologous periosteum flap transplantation combined with patellofemoral realignment.

    Science.gov (United States)

    Fu, Wei-Li; Ao, Ying-Fang; Ke, Xiao-Yan; Zheng, Zhuo-Zhao; Gong, Xi; Jiang, Dong; Yu, Jia-Kuo

    2014-03-01

    Minimal-invasive procedure and one-step surgery offer autologous mesenchymal stem cells derived from peripheral blood (PB-MSCs) a promising prospective in the field of cartilage regeneration. We report a case of a 19-year-old male athlete of kickboxing with ICRS grade IV chondral lesions at the 60° region of lateral femoral trochlea, which was repaired by activating endogenous PB-MSCs plus autologous periosteum flap transplantation combined with correcting the patellofemoral malalignment. After a 7.5 year follow-up, the result showed that the patient returned to competitive kickboxing. Second-look under arthroscopy showed a smooth surface at 8 months postoperation. The IKDC 2000 subjective score, Lysholm score and Tegner score were 95, 98 and 9 respectively at the final follow up. CT and MRI evaluations showed a significant improvement compared with those of pre-operation. © 2013.

  5. Response studies of rotors and rotor blades with application to aeroelastic tailoring

    Science.gov (United States)

    Friedmann, P. P.

    1982-01-01

    Various tools for the aeroelastic stability and response analysis of rotor blades in hover and forward flight were developed and incorporated in a comprehensive package capable of performing aeroelastic tailoring of rotor blades in forward flight. The results indicate that substantial vibration reductions, of order 15-40%, in the vibratory hub shears can be achieved by relatively small modifications of the initial design. Furthermore the optimized blade can be up to 20% lighter than the original design. Accomplishments are reported for the following tasks: (1) finite element modeling of rotary-wing aeroelastic problems in hover and forward flight; (2) development of numerical methods for calculating the aeroelastic response and stability of rotor blades in forward fight; (3) formulation of the helicopter air resonance problem in hover with active controls; and (4) optimum design of rotor blades for vibration reduction in forward flight.

  6. Spontaneous Flapping Flight

    Science.gov (United States)

    Vandenberghe, Nicolas; Zhang, Jun; Childress, Stephen

    2004-11-01

    As shown in an earlier work [Vandenberghe, et. al. JFM, Vol 506, 147, 2004], a vertically flapping wing can spontaneously move horizontally as a result of symmetry breaking. In the current experimental study, we investigate the dependence of resultant velocity on flapping amplitude. We also describe the forward thrust generation and how the system dynamically selects a Strouhal number by balancing fluid and body forces. We further compare our model system with examples of biological locomotion, such as bird flight and fish swimming.

  7. Field Balancing and Harmonic Vibration Suppression in Rigid AMB-Rotor Systems with Rotor Imbalances and Sensor Runout

    Directory of Open Access Journals (Sweden)

    Xiangbo Xu

    2015-08-01

    Full Text Available Harmonic vibrations of high-speed rotors in momentum exchange devices are primary disturbances for attitude control of spacecraft. Active magnetic bearings (AMBs, offering the ability to control the AMB-rotor dynamic behaviors, are preferred in high-precision and micro-vibration applications, such as high-solution Earth observation satellites. However, undesirable harmonic displacements, currents, and vibrations also occur in the AMB-rotor system owing to the mixed rotor imbalances and sensor runout. To compensate the rotor imbalances and to suppress the harmonic vibrations, two control methods are presented. Firstly, a four degrees-of-freedom AMB-rotor model with the static imbalance, dynamic imbalance, and the sensor runout are described. Next, a synchronous current reduction approach with a variable-phase notch feedback is proposed, so that the rotor imbalances can be identified on-line through the analysis of the synchronous displacement relationships of the geometric, inertial, and rotational axes of the rotor. Then, the identified rotor imbalances, which can be represented at two prescribed balancing planes of the rotor, are compensated by discrete add-on weights whose masses are calculated in the vector form. Finally, a repetitive control algorithm is utilized to suppress the residual harmonic vibrations. The proposed field balancing and harmonic vibration suppression strategies are verified by simulations and experiments performed on a control moment gyro test rig with a rigid AMB-rotor system. Compared with existing methods, the proposed strategies do not require trial weights or an accurate model of the AMB-rotor system. Moreover, the harmonic displacements, currents, and vibrations can be well-attenuated simultaneously.

  8. Field Balancing and Harmonic Vibration Suppression in Rigid AMB-Rotor Systems with Rotor Imbalances and Sensor Runout.

    Science.gov (United States)

    Xu, Xiangbo; Chen, Shao

    2015-08-31

    Harmonic vibrations of high-speed rotors in momentum exchange devices are primary disturbances for attitude control of spacecraft. Active magnetic bearings (AMBs), offering the ability to control the AMB-rotor dynamic behaviors, are preferred in high-precision and micro-vibration applications, such as high-solution Earth observation satellites. However, undesirable harmonic displacements, currents, and vibrations also occur in the AMB-rotor system owing to the mixed rotor imbalances and sensor runout. To compensate the rotor imbalances and to suppress the harmonic vibrations, two control methods are presented. Firstly, a four degrees-of-freedom AMB-rotor model with the static imbalance, dynamic imbalance, and the sensor runout are described. Next, a synchronous current reduction approach with a variable-phase notch feedback is proposed, so that the rotor imbalances can be identified on-line through the analysis of the synchronous displacement relationships of the geometric, inertial, and rotational axes of the rotor. Then, the identified rotor imbalances, which can be represented at two prescribed balancing planes of the rotor, are compensated by discrete add-on weights whose masses are calculated in the vector form. Finally, a repetitive control algorithm is utilized to suppress the residual harmonic vibrations. The proposed field balancing and harmonic vibration suppression strategies are verified by simulations and experiments performed on a control moment gyro test rig with a rigid AMB-rotor system. Compared with existing methods, the proposed strategies do not require trial weights or an accurate model of the AMB-rotor system. Moreover, the harmonic displacements, currents, and vibrations can be well-attenuated simultaneously.

  9. Rotor balancing apparatus and system

    Science.gov (United States)

    Lyman, Frank (Inventor); Lyman, Joseph (Inventor)

    1976-01-01

    Rotor balancing apparatus and a system comprising balance probes for measuring unbalance at the ends of a magnetically suspended rotor are disclosed. Each balance probe comprises a photocell which is located in relationship to the magnetically suspended rotor such that unbalance of the rotor changes the amount of light recorded by each photocell. The signal from each photocell is electrically amplified and displayed by a suitable device, such as an oscilloscope.

  10. Free craniotomy versus osteoplastic craniotomy, assessment of flap viability using 99mTC MDP SPECT.

    Science.gov (United States)

    Shelef, Ilan; Golan, Haim; Merkin, Vladimir; Melamed, Israel; Benifla, Mony

    2016-09-01

    There are currently two accepted neurosurgical methods to perform a bony flap. In an osteoplastic flap, the flap is attached to surrounding muscle. In a free flap, the flap is not attached to adjacent tissues. The former is less common due to its complexity and the extensive time required for the surgery; yet the rate of infection is significantly lower, a clear explanation for which is unknown. The objective of this study was to test the hypothesis that the osteoplastic flap acts as a live implant that resumes its blood flow and metabolic activity; contrasting with the free flap, which does not have sufficient blood flow, and therefore acts as a foreign body. Seven patients who underwent craniotomy with osteoplastic flaps and five with free flaps had planar bone and single photon emission computed tomography (SPECT) scans of the skull at 3-7days postoperative, after injection of the radioisotope, 99m-technetium-methylene diphosphonate (99m-Tc-MDP). We compared radioactive uptake as a measure of metabolic activity between osteoplastic and free flaps. Mean normalized radioactive uptakes in the centers of the flaps, calculated as the ratios of uptakes in the flap centers to uptakes in normal contralateral bone, were [mean: 1.7 (SD: 0.8)] and [0.6 (0.1)] for the osteoplastic and free flap groups respectively and were [2.4 (0.8)] and [1.3 (0.4)] in the borders of the flaps. Our analyses suggest that in craniotomy, the use of an osteoplastic flap, in contrast to free flap, retains bone viability.

  11. Breast Reconstruction with Flap Surgery

    Science.gov (United States)

    Breast reconstruction with flap surgery Overview By Mayo Clinic Staff Breast reconstruction is a surgical procedure that restores shape to ... breast tissue to treat or prevent breast cancer. Breast reconstruction with flap surgery is a type of breast ...

  12. Summary of Full-Scale Blade Displacement Measurements of the UH- 60A Airloads Rotor

    Science.gov (United States)

    Abrego, Anita I.; Meyn, Larry; Burner, Alpheus W.; Barrows, Danny A.

    2016-01-01

    Blade displacement measurements using multi-camera photogrammetry techniques were acquired for a full-scale UH-60A rotor, tested in the National Full-Scale Aerodynamic Complex 40-Foot by 80-Foot Wind Tunnel. The measurements, acquired over the full rotor azimuth, encompass a range of test conditions that include advance ratios from 0.15 to 1.0, thrust coefficient to rotor solidity ratios from 0.01 to 0.13, and rotor shaft angles from -10.0 to 8.0 degrees. The objective was to measure the blade displacements and deformations of the four rotor blades and provide a benchmark blade displacement database to be utilized in the development and validation of rotorcraft prediction techniques. An overview of the blade displacement measurement methodology, system development, and data analysis techniques are presented. Sample results based on the final set of camera calibrations, data reduction procedures and estimated corrections that account for registration errors due to blade elasticity are shown. Differences in blade root pitch, flap and lag between the previously reported results and the current results are small. However, even small changes in estimated root flap and pitch can lead to significant differences in the blade elasticity values.

  13. Variability of extreme flap loads during turbine operation

    Energy Technology Data Exchange (ETDEWEB)

    Ronold, K.O. [Det Norske Veritas, Hoevik (Norway); Larsen, G.C. [Risoe National Lab., Wind Energy and Atmospheric Physics Dept., Roskilde (Denmark)

    1999-03-01

    The variability of extreme flap loads is of utmost importance for design of wind-turbine rotor blades. The flap loads of interest consist of the flap-wise bendin moment response at the blade root whose variability in the short-term, for a given wind climate, can be represented by a stationary process. A model for the short-term bending moment process is presented, and the distribution of its associated maxima is derived. A model for the wind climate is given in terms of the probability distributions for the 10-minute mean wind speed and the standard deviation of the arbitrary wind speed. This is used to establish the distribution of the largest flap-wise bending moment in a specific reference period, and it is outlined how a characteristic bending moment for use in design can be extracted from this distribution. The application of the presented distribution models is demonstrated by a numerical example for a site-specific wind turbine. (au)

  14. Effects of vascular endothelial growth factor on survival of surgical flaps: a review of experimental studies.

    Science.gov (United States)

    Fang, Taolin; Lineaweaver, William C; Chen, Michael B; Kisner, Carson; Zhang, Feng

    2014-01-01

    Partial or complete necrosis of skin flaps remains a significant problem in plastic and reconstructive surgery. Growth factors have shown promise in improving flap survival through increased angiogenesis and blood supply to the flap. Vascular endothelial growth factor (VEGF) is the most widely investigated and successful one. But the mechanisms of the effects are still not very clear. In the course of a series of experiments, we indicated that tissue survival of surgical flaps could be improved by both preoperative (sustained phase effect) and intraoperative (acute phase effect) application of VEGF. We reviewed both experimental and clinical investigations on the use of VEGF with surgical flaps to summarize the evidence of both phases of VEGF activity in promotion of flaps survival in detail. With the combinations of acute and sustained phases of effects, VEGF protein and gene, VEGF morphologic actions, and VEGF histochemical modulations suggest a pattern of VEGF activity that can be superimposed on classic descriptive mechanisms of tissue survival of flaps.

  15. Manufacturing Error Effects on Mechanical Properties and Dynamic Characteristics of Rotor Parts under High Acceleration

    Science.gov (United States)

    Jia, Mei-Hui; Wang, Cheng-Lin; Ren, Bin

    2017-07-01

    Stress, strain and vibration characteristics of rotor parts should be changed significantly under high acceleration, manufacturing error is one of the most important reason. However, current research on this problem has not been carried out. A rotor with an acceleration of 150,000 g is considered as the objective, the effects of manufacturing errors on rotor mechanical properties and dynamic characteristics are executed by the selection of the key affecting factors. Through the force balance equation of the rotor infinitesimal unit establishment, a theoretical model of stress calculation based on slice method is proposed and established, a formula for the rotor stress at any point derives. A finite element model (FEM) of rotor with holes is established with manufacturing errors. The changes of the stresses and strains of a rotor in parallelism and symmetry errors are analyzed, which verify the validity of the theoretical model. The pre-stressing modal analysis is performed based on the aforementioned static analysis. The key dynamic characteristics are analyzed. The results demonstrated that, as the parallelism and symmetry errors increase, the equivalent stresses and strains of the rotor slowly increase linearly, the highest growth rate does not exceed 4%, the maximum change rate of natural frequency is 0.1%. The rotor vibration mode is not significantly affected. The FEM construction method of the rotor with manufacturing errors can be utilized for the quantitative research on rotor characteristics, which will assist in the active control of rotor component reliability under high acceleration.

  16. Concepts for a theoretical and experimental study of lifting rotor random loads and vibrations, Phase 2

    Science.gov (United States)

    Hohenemser, K. H.; Gaonkar, G. H.

    1968-01-01

    A comparison with NASA conducted simulator studies has shown that the approximate digital method for computing rotor blade flapping responses to random inputs, tentatively suggested in Phase I Report, gives with increasing rotor advance ratio the wrong trend. Consequently, three alternative methods of solution have been considered and are described: (1) an approximate method based on the functional relation between input and output double frequency spectra, (2) a numerical method based on the system responses to deterministic inputs and (3) a perturbation approach. Among these the perturbation method requires the least amount of computation and has been developed in two forms - the first form to obtain the response correlation function and the second for the time averaged spectra of flapping oscillations.

  17. Rotor for a pyrolysis centrifuge reactor

    DEFF Research Database (Denmark)

    2015-01-01

    The present invention relates to a rotor for a pyrolysis centrifuge reactor, said rotor comprising a rotor body having a longitudinal centre axis, and at least one pivotally mounted blade being adapted to pivot around a pivot axis under rotation of the rotor body around the longitudinal centre axis....... Moreover, the present invention relates to a pyrolysis centrifuge reactor applying such a rotor....

  18. SMART Wind Turbine Rotor: Design and Field Test

    Energy Technology Data Exchange (ETDEWEB)

    Berg, Jonathan C. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Resor, Brian R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Paquette, Joshua A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); White, Jonathan R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2014-01-29

    This report documents the design, fabrication, and testing of the SMART Rotor. This work established hypothetical approaches for integrating active aerodynamic devices (AADs) into the wind turbine structure and controllers.

  19. Lessons from Rotor 37

    Institute of Scientific and Technical Information of China (English)

    J.D.Denton

    1997-01-01

    NASA rotor 37 was used as a blind test case for turbomachinery CFD by the Turbomachinery Committee of the IGTI.The rotor is a transonic compressor with a tip speed of 454 m/s(1500ft/s)and a relatively high pressure ratio of 2.1.It was tested in isolation with a circumferentially uniform inlet flow so that the flow through it should be steady apart from and effects of passage to passage geometry variation and mechanical vibration.As such it represents the simplest possible type of test for three-dimensional turbomachinery flow solvers.Howerver,the rotor still presents a real challenge to 3D viscous flow solvers because the shock wave-boudary layer interaction is strong and the effects of viscosity are dominant in determining the flow deviation and hence the pressure ration.Eleven blind solutions were submittewd and in addition a non-blind solution was used to prepare for the exercies.This paper reviews the flow in the test case and the comparisons of the CFD solutions with the test data.Lessons for both the Flow physics in transonic fans and for the application of CFD to such machines are pointed out.

  20. Adaptive unbalance compensation control of active magnetic bearing supporting rotor system%主动电磁轴承转子系统自适应不平衡补偿控制

    Institute of Scientific and Technical Information of China (English)

    蒋科坚; 祝长生

    2011-01-01

    为了抑制振动,提高转子旋转精度,提出一种基于振动识别的不平衡补偿控制方法.该方法无需控制对象的传递函数,通过对主动电磁轴承施加试探性补偿信号,同时检测转子位移响应中不平衡振动的幅值和相位变化,直接计算出不平衡振动的Fourier系数,产生精确的补偿电磁力,实现不平衡补偿控制.在控制性能测试的实验中,振动响应的功率谱显示转速频率的振动能量有近30 dB的下降.实验结果表明,该方法对不平衡振动的抑制效果是显著的.%For suppressing vibrations and improving the rotor's rotating precision, a novel unbalance compensation method was proposed, which does not need the transfer function of plant model. The proposed method can directly obtain the Fourier coefficients of unbalance vibration and generate the accurate magnetic force to achieve unbalance compensation by injecting a trial signal into the active magnetic bearing (AMB) and meanwhile measuring the variety in magnitude and phase of the rotor's displacement response.Finally, in an experiment for testing the algorithm's efficiency and precision, approximately 30 dB reduction in unbalance vibrations was obtained in the power spectrum of rotor vibration. The experimental results indicate that the proposed algorithm is effective for suppressing rotor unbalance vibration.

  1. Homopolar motor with dual rotors

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, John S. (Oak Ridge, TN)

    1998-01-01

    A homopolar motor (10) has a field rotor (15) mounted on a frame (11) for rotation in a first rotational direction and for producing an electromagnetic field, and an armature rotor (17) mounted for rotation on said frame (11) within said electromagnetic field and in a second rotational direction counter to said first rotational direction of said field rotor (15). The two rotors (15, 17) are coupled through a 1:1 gearing mechanism (19), so as to travel at the same speed but in opposite directions. This doubles the output voltage and output power, as compared to a motor in which only the armature is rotated. Several embodiments are disclosed.

  2. Homopolar motor with dual rotors

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, J.S.

    1998-12-01

    A homopolar motor has a field rotor mounted on a frame for rotation in a first rotational direction and for producing an electromagnetic field, and an armature rotor mounted for rotation on said frame within said electromagnetic field and in a second rotational direction counter to said first rotational direction of said field rotor. The two rotors are coupled through a 1:1 gearing mechanism, so as to travel at the same speed but in opposite directions. This doubles the output voltage and output power, as compared to a motor in which only the armature is rotated. Several embodiments are disclosed. 7 figs.

  3. Rotor/body aerodynamic interactions

    Science.gov (United States)

    Betzina, M. D.; Smith, C. A.; Shinoda, P.

    1985-01-01

    A wind tunnel investigation was conducted in which independent, steady state aerodynamic forces and moments were measured on a 2.24 m diam. two bladed helicopter rotor and on several different bodies. The mutual interaction effects for variations in velocity, thrust, tip-path-plane angle of attack, body angle of attack, rotor/body position, and body geometry were determined. The results show that the body longitudinal aerodynamic characteristics are significantly affected by the presence of a rotor and hub, and that the hub interference may be a major part of such interaction. The effects of the body on the rotor performance are presented.

  4. Variable Speed Rotor System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Variable speed rotors will give helicopters several advantages: higher top speed, greater fuel efficiency, momentary emergency over-power, resonance detuning...

  5. Resonant vibration control of three-bladed wind turbine rotors

    DEFF Research Database (Denmark)

    Krenk, Steen; Svendsen, Martin Nymann; Høgsberg, Jan Becker

    2012-01-01

    Rotors with blades, as in wind turbines, are prone to vibrations due to the flexibility of the blades and the support. In the present paper a theory is developed for active control of a combined set of vibration modes in three-bladed rotors. The control system consists of identical collocated...... to influence of other nonresonant modes. The efficiency of the method isdemonstrated byapplication to a rotor with 42 m blades, where the sensor/actuator system is implemented in the form of an axial extensible strut near the root of each blade. The load is provided by a simple but fully threedimensional...

  6. Blade Displacement Measurement Technique Applied to a Full-Scale Rotor Test

    Science.gov (United States)

    Abrego, Anita I.; Olson, Lawrence E.; Romander, Ethan A.; Barrows, Danny A.; Burner, Alpheus W.

    2012-01-01

    Blade displacement measurements using multi-camera photogrammetry were acquired during the full-scale wind tunnel test of the UH-60A Airloads rotor, conducted in the National Full-Scale Aerodynamics Complex 40- by 80-Foot Wind Tunnel. The objectives were to measure the blade displacement and deformation of the four rotor blades as they rotated through the entire rotor azimuth. These measurements are expected to provide a unique dataset to aid in the development and validation of rotorcraft prediction techniques. They are used to resolve the blade shape and position, including pitch, flap, lag and elastic deformation. Photogrammetric data encompass advance ratios from 0.15 to slowed rotor simulations of 1.0, thrust coefficient to rotor solidity ratios from 0.01 to 0.13, and rotor shaft angles from -10.0 to 8.0 degrees. An overview of the blade displacement measurement methodology and system development, descriptions of image processing, uncertainty considerations, preliminary results covering static and moderate advance ratio test conditions and future considerations are presented. Comparisons of experimental and computational results for a moderate advance ratio forward flight condition show good trend agreements, but also indicate significant mean discrepancies in lag and elastic twist. Blade displacement pitch measurements agree well with both the wind tunnel commanded and measured values.

  7. Toward comparing experiment and theory for corroborative research on hingeless rotor stability in forward flight

    Science.gov (United States)

    Gaonkar, G.

    1987-01-01

    For flap lag stability of isolated rotors, experimental and analytical investigations were conducted in hover and forward flight on the adequacy of a linear quasisteady aerodynamics theory with dynamic flow. Forward flight effects on lag regressing mode were emphasized. A soft inplane hingeless rotor with three blades was tested at advance ratios as high as 0.55 and at shaft angles as high as 20 deg. The 1.62 m model rotor was untrimmed with an essentially unrestricted tilt of the tip path plane. In combination with lag natural frequencies, collective pitch settings and flap lag coupling parameters, the data base comprises nearly 1200 test points (damping and frequency) in forward flight and 200 test points in hover. By computerized symbolic manipulation, a linear model was developed in substall to predict stability margins with mode identification. To help explain the correlation between theory and data it also predicted substall and stall regions of the rotor disk from equilibrium values. The correlation showed both the strengths and weaknesses of the theory in substall ((angle of attack) equal to or less than 12 deg).

  8. Large Wind Turbine Rotor Design using an Aero-Elastic / Free-Wake Panel Coupling Code

    Science.gov (United States)

    Sessarego, Matias; Ramos-García, Néstor; Shen, Wen Zhong; Nørkær Sørensen, Jens

    2016-09-01

    Despite the advances in computing resources in the recent years, the majority of large wind-turbine rotor design problems still rely on aero-elastic codes that use blade element momentum (BEM) approaches to model the rotor aerodynamics. The present work describes an approach to wind-turbine rotor design by incorporating a higher-fidelity free-wake panel aero-elastic coupling code called MIRAS-FLEX. The optimization procedure includes a series of design load cases and a simple structural design code. Due to the heavy MIRAS-FLEX computations, a surrogate-modeling approach is applied to mitigate the overall computational cost of the optimization. Improvements in cost of energy, annual energy production, maximum flap-wise root bending moment, and blade mass were obtained for the NREL 5MW baseline wind turbine.

  9. The Efficiency of a Hybrid Flapping Wing Structure—A Theoretical Model Experimentally Verified

    Directory of Open Access Journals (Sweden)

    Yuval Keren

    2016-07-01

    Full Text Available To propel a lightweight structure, a hybrid wing structure was designed; the wing’s geometry resembled a rotor blade, and its flexibility resembled an insect’s flapping wing. The wing was designed to be flexible in twist and spanwise rigid, thus maintaining the aeroelastic advantages of a flexible wing. The use of a relatively “thick” airfoil enabled the achievement of higher strength to weight ratio by increasing the wing’s moment of inertia. The optimal design was based on a simplified quasi-steady inviscid mathematical model that approximately resembles the aerodynamic and inertial behavior of the flapping wing. A flapping mechanism that imitates the insects’ flapping pattern was designed and manufactured, and a set of experiments for various parameters was performed. The simplified analytical model was updated according to the tests results, compensating for the viscid increase of drag and decrease of lift, that were neglected in the simplified calculations. The propelling efficiency of the hovering wing at various design parameters was calculated using the updated model. It was further validated by testing a smaller wing flapping at a higher frequency. Good and consistent test results were obtained in line with the updated model, yielding a simple, yet accurate tool, for flapping wings design.

  10. Deep inferior epigastric perforator flap for breast reconstruction: experience with 43 flaps

    Institute of Scientific and Technical Information of China (English)

    YAN Xiao-qing; YANG Hong-yan; ZHAO Yu-ming; YOU Lei; XU Jun

    2007-01-01

    Background In the past decade, there has been increasing breast reconstructions after mastectomy. The ideal material for reconstruction of a breast is fat and skin. The transverse rectus abdominis myocutaneous (TRAM) flap has been the gold standard for breast reconstruction until recently. Abdominal wall function is a major concern for plastic surgeons in breast reconstruction with TRAM flaps. The deep inferior epigastric perforator (DIEP) free flap spares the whole rectus abdominis muscle, includes skin and fat only, and therefore preserves adequate abdominal wall competence. The aim of this study was to summarize our experience in breast reconstruction with DIEP flap.Methods Between March 2000 and August 2005, a total of 43 breast reconstructions were performed on 40 patients by our surgeons using DIEP flap (3 patients had bilateral procedures), 14 of them were immediate surgeries and 26 were delayed. Abdominal function, satisfaction with the donor site and reconstructed breast, and the sensation recovery was assessed respectively during follow-up.Results The mean age of the patients was 38.6 years (range, 28-50). The size of the flaps was 11 cm×26 cm in average (height 10-12 cm, width 15-33 cm). The mean length of the vascular pedicles was 9.3 cm (range, 7-12). The patients were followed up for a mean of 16 months (range, 6-30 months). During the follow-up, 2 (5%) patients had total flap loss, 2 (5%) had partial necrosis, 4 (9%) had wound edge necrosis in the abdomen, and 1 had axillary seroma. None of the patients had hernia, and all of them were able to resume their daily activities after the operation. Patient satisfaction with the reconstructed breast rated high, 95% of the patients achieved spontaneous return of sensation in the reconstructed breast, but none of them had a sensation equivalent or approximate to the normal.Conclusions The DIEP flap has the same benefits as the TRAM flap without destroying the continuity of the rectus muscle. It can reduce

  11. The Gradual Expansion Muscle Flap

    Science.gov (United States)

    2014-01-01

    defects can usu- ally be obtained with a rotational flap , larger size defects commonly require free tissue transfer. A number of techni- ques have...feasible.21,22 Because limb salvage situations occur in which rota- tional muscle coverage is inadequate and free flap coverage is less desirable, we...larger defects which previously would have required free tissue transfer. Surgical Technique The GEM flap for large soft tissue defects of the leg requires

  12. Sliding flap tracheoplasty.

    Science.gov (United States)

    Gates, G A; Tucker, J A

    1989-12-01

    The optimal method for surgical management of subglottic stenosis is based upon careful assessment of the location, caliber, length, and maturity of the stenotic segment, as well as associated conditions. For patients with a mature stenosis of short length, excision of the anterior arch of the cricoid and first ring and immediate reconstruction by means of a sliding flap of the next two to three rings of trachea offer a one-stage definitive treatment without the need for grafting. We report four cases of subglottic stenosis and one case of cricoid chondroblastoma in which reconstruction of the airway was successful and prompt. For carefully selected cases, sliding flap tracheoplasty may be a useful alternative to procedures in which the airway is expanded by means of grafting.

  13. Input Shaping enhanced Active Disturbance Rejection Control for a twin rotor multi-input multi-output system (TRMS).

    Science.gov (United States)

    Yang, Xiaoyan; Cui, Jianwei; Lao, Dazhong; Li, Donghai; Chen, Junhui

    2016-05-01

    In this paper, a composite control based on Active Disturbance Rejection Control (ADRC) and Input Shaping is presented for TRMS with two degrees of freedom (DOF). The control tasks consist of accurately tracking desired trajectories and obtaining disturbance rejection in both horizontal and vertical planes. Due to un-measurable states as well as uncertainties stemming from modeling uncertainty and unknown disturbance torques, ADRC is employed, and feed-forward Input Shaping is used to improve the dynamical response. In the proposed approach, because the coupling effects are maintained in controller derivation, there is no requirement to decouple the TRMS into horizontal and vertical subsystems, which is usually performed in the literature. Finally, the proposed method is implemented on the TRMS platform, and the results are compared with those of PID and ADRC in a similar structure. The experimental results demonstrate the effectiveness of the proposed method. The operation of the controller allows for an excellent set-point tracking behavior and disturbance rejection with system nonlinearity and complex coupling conditions.

  14. Cross finger flaps.

    Science.gov (United States)

    Kisner, W H

    1979-01-01

    Proper fingertip reconstruction requires good skin and soft tissue coverage, preservation of function and as normal an appearance as possible. The cross finger flap results in negligible joint stiffness, minimal morbidity and little work-time loss. An important factor is the conservation of finger length permitted by this technique. This method of repair is underutilized. It is indicated in several types of fingertip amputations where bone shortening would be detrimental.

  15. The Versatile Modiolus Perforator Flap

    DEFF Research Database (Denmark)

    Gunnarsson, Gudjon Leifur; Thomsen, Jorn Bo

    2016-01-01

    BACKGROUND: Perforator flaps are well established, and their usefulness as freestyle island flaps is recognized. The whereabouts of vascular perforators and classification of perforator flaps in the face are a debated subject, despite several anatomical studies showing similar consistency. In our....... The color Doppler ultrasonography study detected a sizeable perforator at the level of the modiolus lateral to the angle of the mouth within a radius of 1 cm. This confirms the anatomical findings of previous authors and indicates that the modiolus perforator is a consistent anatomical finding, and flaps...

  16. The Simplified Posterior Interosseous Flap.

    Science.gov (United States)

    Cavadas, Pedro C; Thione, Alessandro; Rubí, Carlos

    2016-09-01

    Several technical modifications have been described to avoid complications and simplify dissection. The authors describe some technical tips that make posterior interosseous flap dissection safer and more straightforward.

  17. Keystone flaps in coloured skin: Flap technology for the masses?

    Directory of Open Access Journals (Sweden)

    Satish P Bhat

    2013-01-01

    Full Text Available Introduction: Viscoelastic properties of skin in coloured ethnic groups are less favourable compared to Caucasians for executing Keystone flaps. Keystone flaps have so far been evaluated and reported only in Caucasians. The potential of Keystone flaps in a coloured ethnic group is yet unknown. Aim: This article reviews the experience to reconstruct skin defects presenting in a coloured ethnic group, by using Keystone flaps, with a review of existing literature. Design: Uncontrolled case series. Materials and Methods: This retrospective review involves 55 consecutive Keystone flaps used from 2009 to 2012, for skin defects in various locations. Patient demographic data, medical history, co-morbidity, surgical indication, defect features, complications, and clinical outcomes are evaluated and presented. Results: In this population group with Fitzpatrick type 4 and 5 skin, the average patient age was 35.73. Though 60% of flaps (33/55 in the series involved specific risk factors, only two flaps failed. Though seven flaps had complications, sound healing was achieved by suitable intervention giving a success rate of 96.36%. Skin grafts were needed in only four cases. Conclusions: Keystone flaps achieve primary wound healing for a wide spectrum of defects with an acceptable success rate in a coloured skin population with unfavorable biophysical properties. By avoiding conventional local flaps and at times even microsurgical flaps, good aesthetic outcome is achieved without additional skin grafts or extensive operative time. All advantages seen in previous studies were verified. These benefits can be most appreciated in coloured populations, with limited resources and higher proportion of younger patients and unfavorable defects.

  18. Papilla Preservation Flap as Aesthetic Consideration in Periodontal Flap Surgery

    Directory of Open Access Journals (Sweden)

    Sandra Olivia

    2013-07-01

    Full Text Available Flap surgery is treatment for periodontal disease with alveolar bone destruction. Surgical periodontal flap with conventional incision will result in gingival recession and loss of interdental papillae after treatment. Dilemma arises in areas required high aesthetic value or regions with a fixed denture. It is challenging to perform periodontal flap with good aesthetic results and minimal gingival recession. This case report aimed to inform and to explain the work procedures, clinical and radiographic outcomes of surgical papilla preservation flap in the area that requires aesthetic. Case 1 was a surgical incision flap with preservation of papillae on the anterior region of teeth 11 and 12, with a full veneer crown on tooth 12. Case 2 was a surgical incision flap with preservation of papillae on the posterior region of tooth 46 with inlay restoration. Evaluation for both cases were obtained by incision papilla preservation of primary closure was perfect, good aesthetic results, minimal gingival recession and the interdental papillae can be maintained properly. In conclusion, periodontal flap surgery on the anterior region or regions that require high aesthetic value could be addressed with papilla preservation incision. Incision papilla preservation should be the primary consideration in periodontal flap surgery if possible.DOI: 10.14693/jdi.v19i3.144

  19. Peroneal Flap for Tongue Reconstruction.

    Science.gov (United States)

    Lin, Ying-Sheng; Liu, Wen-Chung; Lin, Yaoh-Shiang; Chen, Lee-Wei; Yang, Kuo-Chung

    2017-07-01

    Background For large tongue defects, reconstructive surgeons have devised a variety of feasible options, such as radial forearm free flap and anterolateral thigh (ALT) flap. In our institution, peroneal flap has been the workhorse flap for the soft tissue defect in head and neck reconstruction. We present our experience using peroneal flap in tongue reconstruction. Patients and Methods The study included 47 patients who had undergone tongue reconstructions with peroneal flaps after tumor resection. The size and location of the defect after tumor resection determined whether the peroneal flaps could be harvested as pure septocutaneous flaps to solely reconstruct the neotongue or to carry an additional muscle bulk to fill the adjacent defect. Retrospective chart review was used to look for postoperative complications and to perform functional assessments (which were also performed through telephone inquiry). Results Of the 47 patients, 3 (6%) had flap failure and 1 (2.1%) had partial flap necrosis. The hemiglossectomy group had better results than the total glossectomy group with respect to speech and diet, but neither of these results reached statistical significance (p = 1.0 for speech and p = 0.06 for diet). The results of the subtotal glossectomy group were better than those of the total glossectomy group with respect to diet (p = 0.03). No statistically significant differences were noted among the three groups with respect to cosmetic aspect (p = 0.64). Conclusions Considering its reasonable postoperative complication rates and functional results, peroneal flap can be considered a feasible option for tongue reconstruction. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

  20. A high voltage DC-DC converter driving a Dielectric Electro Active Polymer actuator for wind turbine flaps

    DEFF Research Database (Denmark)

    Thummala, Prasanth; Zhang, Zhe; Andersen, Michael A. E.;

    2012-01-01

    The Dielectric Electro Active Polymer (DEAP) material is a very thin (~80 μm) silicone elastomer film with a compliant metallic electrode layer on both sides. The DEAP is fundamentally a capacitor that is capable of very high strain. The property that the polymer changes its shape, as a result...

  1. The properties of isolated and coupled Savonius rotors

    Science.gov (United States)

    Bowden, G. J.; McAleese, S. A.

    Some measurments on the Queensland optimum S-shaped rotor are presented. In particular it is shown that the efficiency of the turbine is about 18 percent, which is lower than the figure of about 23 percent given by earlier workers. In addition, detailed measurements of the pulsating wind-flow around a Savonius rotor are presented. These results were obtained using (1) tell-tales and a stroboscope, (2) a hot-wire anemometer (0-5 kHz response), and (3) a turbulence meter. This data can be used to suggest that 'active coupling' between Savonius rotors might be useful in 'redirecting' the wind-flow more efficiently. In particular, it is shown that if two counter-rotating rotors are placed side by side in a wind-tunnel, a natural phase locking occurs.

  2. Self-propulsion of flapping bodies in viscous fluids:Recent advances and perspectives

    Institute of Scientific and Technical Information of China (English)

    Shizhao Wang; Guowei He; Xing Zhang

    2016-01-01

    Flapping-powered propulsion is used by many animals to locomote through air or water. Here we review recent experimental and numerical studies on self-propelled mechanical systems powered by a flapping motion. These studies improve our understanding of the mutual interaction between actively flapping bodies and surrounding fluids. The results obtained in these works provide not only new insights into biolocomotion but also useful information for the bio-mimetic design of artificial flyers and swimmers.

  3. Self-propulsion of flapping bodies in viscous fluids: Recent advances and perspectives

    Science.gov (United States)

    Wang, Shizhao; He, Guowei; Zhang, Xing

    2016-12-01

    Flapping-powered propulsion is used by many animals to locomote through air or water. Here we review recent experimental and numerical studies on self-propelled mechanical systems powered by a flapping motion. These studies improve our understanding of the mutual interaction between actively flapping bodies and surrounding fluids. The results obtained in these works provide not only new insights into biolocomotion but also useful information for the biomimetic design of artificial flyers and swimmers.

  4. 14 CFR 27.1509 - Rotor speed.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Rotor speed. 27.1509 Section 27.1509... Rotor speed. (a) Maximum power-off (autorotation). The maximum power-off rotor speed must be established... minimum power-off rotor speed must be established so that it is not less than 105 percent of the...

  5. 14 CFR 29.1509 - Rotor speed.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Rotor speed. 29.1509 Section 29.1509....1509 Rotor speed. (a) Maximum power-off (autorotation). The maximum power-off rotor speed must be... minimum power-off rotor speed must be established so that it is not less than 105 percent of the...

  6. Performance tests on helical Savonius rotors

    Energy Technology Data Exchange (ETDEWEB)

    Kamoji, M.A.; Kedare, S.B. [Department of Energy Science and Engineering, Indian Institute of Technology, Bombay (India); Prabhu, S.V. [Department of Mechanical Engineering, Indian Institute of Technology, Bombay (India)

    2009-03-15

    Conventional Savonius rotors have high coefficient of static torque at certain rotor angles and a negative coefficient of static torque from 135 to 165 and from 315 to 345 in one cycle of 360 . In order to decrease this variation in static torque from 0 to 360 , a helical Savonius rotor with a twist of 90 is proposed. In this study, tests on helical Savonius rotors are conducted in an open jet wind tunnel. Coefficient of static torque, coefficient of torque and coefficient of power for each helical Savonius rotor are measured. The performance of helical rotor with shaft between the end plates and helical rotor without shaft between the end plates at different overlap ratios namely 0.0, 0.1 and 0.16 is compared. Helical Savonius rotor without shaft is also compared with the performance of the conventional Savonius rotor. The results indicate that all the helical Savonius rotors have positive coefficient of static torque at all the rotor angles. The helical rotors with shaft have lower coefficient of power than the helical rotors without shaft. Helical rotor without shaft at an overlap ratio of 0.0 and an aspect ratio of 0.88 is found to have almost the same coefficient of power when compared with the conventional Savonius rotor. Correlation for coefficient of torque and power is developed for helical Savonius rotor for a range of Reynolds numbers studied. (author)

  7. Active Control of Flow Separation on a High-Lift System with Slotted Flap at High Reynolds Number

    Science.gov (United States)

    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.

  8. IDENTIFICATION OF CRACKED ROTOR BY WAVELET TRANSFORM

    Institute of Scientific and Technical Information of China (English)

    邹剑; 陈进; 蒲亚鹏

    2002-01-01

    The dynamic equation of cracked rotor in rotational frame was modelled, the numerical simulation solutions of the cracked rotor and the uncracked rotor were obtained. By the wavelet transform, the time-frequency properties of the cracked rotor and the uncracked rotor were discussed, the difference of the time-frequency properties between the cracked rotor and the uncracked rotor was compared. A new detection algorithm using wavelet transform to identify crack was proposed. The experiments verify the availability and validity of the wavelet transform in identification of crack.

  9. Rotor blade assembly having internal loading features

    Energy Technology Data Exchange (ETDEWEB)

    Soloway, Daniel David

    2017-05-16

    Rotor blade assemblies and wind turbines are provided. A rotor blade assembly includes a rotor blade having exterior surfaces defining a pressure side, a suction side, a leading edge and a trailing edge each extending between a tip and a root, the rotor blade defining a span and a chord, the exterior surfaces defining an interior of the rotor blade. The rotor blade assembly further includes a loading assembly, the loading assembly including a weight disposed within the interior and movable generally along the span of the rotor blade, the weight connected to a rotor blade component such that movement of the weight towards the tip causes application of a force to the rotor blade component by the weight. Centrifugal force due to rotation of the rotor blade biases the weight towards the tip.

  10. 14 CFR 23.701 - Flap interconnection.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Flap interconnection. 23.701 Section 23.701... Systems § 23.701 Flap interconnection. (a) The main wing flaps and related movable surfaces as a system must— (1) Be synchronized by a mechanical interconnection between the movable flap surfaces that...

  11. Skin flaps and grafts - self-care

    Science.gov (United States)

    ... Regional flaps - self-care; Distant flaps - self-care; Free flap - self-care; Skin autografting - self-care; Pressure ulcer ... your wound To care for the graft or flap site: You may need to rest ... around it clean and free from dirt or sweat. DO NOT let the ...

  12. Simulation of Moving Trailing Edge Flaps on a Wind Turbine Blade using a Navier-Stokes based Immersed Boundary Method

    DEFF Research Database (Denmark)

    Behrens, Tim

    As the rotor diameter of wind turbines increases, turbine blades with distributed aerodynamic control surfaces promise significant load reductions. Therefore, they are coming into focus in relation to research in academia and industry. Trailing edge flaps are of particular interest in terms...... conforming meshes. A more flexible method would open up an opportunity to investigate the flow features of complex moving flap geometries in great detail. The immersed boundary method offers this flexibility, as the geometry is represented through the introduction of additional forcing terms in the governing...

  13. Feedback Control of Rotor Overspeed

    Science.gov (United States)

    Churchill, G. B.

    1984-01-01

    Feedback system for automatically governing helicopter rotor speed promises to lessen pilot's workload, enhance maneuverability, and protect airframe. With suitable modifications, concept applied to control speed of electrical generators, automotive engines and other machinery.

  14. Design of composite flywheel rotor

    Institute of Scientific and Technical Information of China (English)

    Yue BAI; Qingjia GAO; Haiwen LI; Yihui WU; Ming XUAN

    2008-01-01

    A design method for a flywheel rotor com-posed of a composite rim and a metal hub is proposed by studying the connection between the rotor and the driving machine. The influence of some factors such as the rotor material, configuration, connection, and frac-ture techniques on energy density is analyzed. The results show that the ratio of the inner radius to outer radius of the rim is the key factor, and is determined by the rim material. Optimizing the hub can further efficiently improve energy density. The composite flywheel rotor is produced and its rotation stress has been tested at the speed of 20 krpm. The emulation results are consistent with testing results, which proves that the introduced design method is useful.

  15. On Cup Anemometer Rotor Aerodynamics

    OpenAIRE

    Santiago Pindado; Sergio Avila-Sanchez; Javier Pérez

    2012-01-01

    The influence of anemometer rotor shape parameters, such as the cups’ front area or their center rotation radius on the anemometer’s performance was analyzed. This analysis was based on calibrations performed on two different anemometers (one based on magnet system output signal, and the other one based on an opto-electronic system output signal), tested with 21 different rotors. The results were compared to the ones resulting from classical analytical models. The results clearly showed a lin...

  16. Control of Magnetic Bearings for Rotor Unbalance With Plug-In Time-Varying Resonators.

    Science.gov (United States)

    Kang, Christopher; Tsao, Tsu-Chin

    2016-01-01

    Rotor unbalance, common phenomenon of rotational systems, manifests itself as a periodic disturbance synchronized with the rotor's angular velocity. In active magnetic bearing (AMB) systems, feedback control is required to stabilize the open-loop unstable electromagnetic levitation. Further, feedback action can be added to suppress the repeatable runout but maintain closed-loop stability. In this paper, a plug-in time-varying resonator is designed by inverting cascaded notch filters. This formulation allows flexibility in designing the internal model for appropriate disturbance rejection. The plug-in structure ensures that stability can be maintained for varying rotor speeds. Experimental results of an AMB-rotor system are presented.

  17. Flap Edge Noise Reduction Fins

    Science.gov (United States)

    Khorrami, Mehdi R. (Inventor); Choudhan, Meelan M. (Inventor)

    2015-01-01

    A flap of the type that is movably connected to an aircraft wing to provide control of an aircraft in flight includes opposite ends, wherein at least a first opposite end includes a plurality of substantially rigid, laterally extending protrusions that are spaced apart to form a plurality of fluidly interconnected passageways. The passageways have openings adjacent to upper and lower sides of the flap, and the passageways include a plurality of bends such that high pressure fluid flows from a high pressure region to a low pressure region to provide a boundary condition that inhibits noise resulting from airflow around the end of the flap.

  18. Dancing girl flap: a new flap suitable for web release.

    Science.gov (United States)

    Shinya, K

    1999-12-01

    To create a deep web, a flap must be designed to have a high elongation effect in one direction along the mid-lateral line of the finger and also to have a shortening effect in the other direction, crossing at a right angle to the mid-lateral line. The dancing girl flap is a modification of a four-flap Z-plasty with two additional Z-plasties. It has a high elongation effect in one direction (>550%) and a shortening effect in the other direction at a right angle (<33%), creating a deep, U-shaped surface. This new flap can be used to release severe scar contracture with a web, and is most suitable for incomplete syndactyly with webs as high as the proximal interphalangeal joint.

  19. Vaginoplasty with an M-Shaped Perineo- Scrotal Flap in a Male-to-female Transsexual

    Directory of Open Access Journals (Sweden)

    Nasu,Yasutomo

    2007-12-01

    Full Text Available To date, many techniques have been reported for vaginoplasty in male-to-female trans-sexual (MTFTS patients, such as the use of a rectum transfer, a penile-scrotal flap and a reversed penile flap. However, none of these procedures is without its disadvantages. We developed a newly kind of flap for vaginoplasty, the M-shaped perineo-scrotal flap (M-shaped flap, using skin from both sides of the scrotum, shorn of hair by preoperative laser treatment. We applied this new type of flap in 7 MTFTS patients between January 2006 and January 2007. None of the flaps developed necrosis, and the patients could engage in sexual activity within 3 months of the operation. The M-shaped flap has numerous advantages: it can be elevated safely while retaining good vascularity, it provides for the construction of a sufficient deep vagina without a skin graft, the size of the flap is not influenced entirely by the length of the penis, and it utilizes skin from both sides of the scrotal area, which is usually excised.

  20. A New Fine Damping Method for Solid ESG Rotor

    Institute of Scientific and Technical Information of China (English)

    LIU Chun-ning; TIAN Wei-feng; JIN Zhi-hua

    2006-01-01

    For the electrostatically suspended gyro(ESG) with solid rotor, because the equatorial photoelectric sensor won't sense the equatorial marking line and output the correct damping control information when the nutation angle is small, the active damping with equatorial marking line will bring considerable error. The passive damping method by applying strong DC magnetic field requires too much time. So an active damping method by longitude marking lines is proposed to fulfill the fine damping for solid ESG rotor. The shape of rotor marking lines and the principle of fine damping are introduced. The simulation results prove that this fine damping method can effectively solve the problem of damping error introduced by active damping with equatorial marking line. The estimating results for damping time indicate that the fine damping time is less than 10 percent of passive damping time.

  1. Rotor-Router Aggregation on the Comb

    OpenAIRE

    Huss, Wilfried; Sava, Ecaterina

    2011-01-01

    We prove a shape theorem for rotor-router aggregation on the comb, for a specific initial rotor configuration and clockwise rotor sequence for all vertices. Furthermore, as an application of rotor-router walks, we describe the harmonic measure of the rotor-router aggregate and related shapes, which is useful in the study of other growth models on the comb. We also identify the shape for which the harmonic measure is uniform. This gives the first known example where the rotor-router cluster ha...

  2. Physiological, aerodynamic and geometric constraints of flapping account for bird gaits, and bounding and flap-gliding flight strategies.

    Science.gov (United States)

    Usherwood, James Richard

    2016-11-01

    Aerodynamically economical flight is steady and level. The high-amplitude flapping and bounding flight style of many small birds departs considerably from any aerodynamic or purely mechanical optimum. Further, many large birds adopt a flap-glide flight style in cruising flight which is not consistent with purely aerodynamic economy. Here, an account is made for such strategies by noting a well-described, general, physiological cost parameter of muscle: the cost of activation. Small birds, with brief downstrokes, experience disproportionately high costs due to muscle activation for power during contraction as opposed to work. Bounding flight may be an adaptation to modulate mean aerodynamic force production in response to (1) physiological pressure to extend the duration of downstroke to reduce power demands during contraction; (2) the prevention of a low-speed downstroke due to the geometric constraints of producing thrust; (3) an aerodynamic cost to flapping with very low lift coefficients. In contrast, flap-gliding birds, which tend to be larger, adopt a strategy that reduces the physiological cost of work due both to activation and contraction efficiency. Flap-gliding allows, despite constraints to modulation of aerodynamic force lever-arm, (1) adoption of moderately large wing-stroke amplitudes to achieve suitable muscle strains, thereby reducing the activation costs for work; (2) reasonably quick downstrokes, enabling muscle contraction at efficient velocities, while being (3) prevented from very slow weight-supporting upstrokes due to the cost of performing 'negative' muscle work.

  3. Monolithically Integrated Micro Flapping Vehicles

    Science.gov (United States)

    2012-08-01

    Mechanical Logic • Memory Mm-Scale Ground Mobility Actuation & Mechanisms Ultrasonic Motors Reversible Adhesion Platform Design...MEMS Mm-Scale Ground Mobility PiezoMEMS Haltere Actuation & Mechanisms Ultrasonic Motors Reversible Adhesion Platform Design Flapping

  4. [Repairing degloving injury of distal phalanx with homodigital bilobed flaps tiled].

    Science.gov (United States)

    Jiang, Qiting; Feng, Mingsheng; Jiang, Zhiwei; Liu, Jinzhu

    2012-07-01

    To study the methods and effectiveness of repairing degloving injury of the distal phalanx with homodigital bilobed flaps tiled. Between April 2008 and June 2011, 40 patients (40 fingers) with degloving injury of the distal phalanx were treated, which were caused by machine. There were 30 males and 10 females, aged from 18 to 56 years (mean, 30 years). The time from injury to operation was 1-5 hours (mean, 2.5 hours). Affected fingers included index in 13 cases, middle finger in 11 cases, ring finger in 9 cases, and little finger in 7 cases. The defect area ranged from 3.0 cm x 2.0 cm to 5.5 cm x 3.8 cm. All cases complicated by pollution and exposure of tendon and phalanx, 5 cases by phalangeal fractures, and tendon insertion had no rupture. The end dorsal branches of digital artery island flaps and digital arterial island flaps were used in 14 cases, the end dorsal branches of digital artery island flaps and near dorsal branches of digital artery island flaps in 18 cases, and the end dorsal branches of digital artery island flaps and superficial palmar digital veins arterilization island flaps in 8 cases. The area of the upper flaps ranged from 2.0 cm x 1.5 cm to 2.6 cm x 2.2 cm and the area of the next leaf flaps ranged from 2.5 cm x 2.0 cm to 3.5 cm x 2.5 cm. The donor sites were covered with free flaps. Flap blister occurred in 13 cases and vascular crisis in 3 cases. The flaps survived in 40 cases, wound healing by first intention was achieved in 38 cases, and by second intention in 2 cases. The donor skin-grafting was survival. After operation, 30 patients were followed up 8 to 20 months with an average of 10.6 months. The flaps had satisfactory appearance and soft texture, and the finger tip had no touch pain. The sensory function of the flaps was restored at 4-6 weeks after operation; two-point discrimination was 6.0 to 10.0 mm in 24 flaps at 12-15 months. According to the total active movement (TAM) evaluation system introduced by the American Society for

  5. Higher harmonic control analysis for vibration reduction of helicopter rotor systems

    Science.gov (United States)

    Nguyen, Khanh Q.

    1994-01-01

    operating in a transition flight regime and for an articulated rotor operating at the level-flight boundary (high speed and high thrust conditions) indicate that blade parameters including flap, lag, torsion stiffness distributions, linear pretwist, chordwise offset of center-of-mass from elastic axis and chordwise offset of elastic axis from aerodynamic center can be selected to minimize the actuator power requirements for HHC.

  6. The rat saphenous flap: a fasciocutaneous free flap model without panniculus carnosus.

    Science.gov (United States)

    Mutaf, M; Tasaki, Y; Tanaka, K; Fujii, T

    1995-10-01

    The rat saphenous flap is described as a new experimental model for free flap studies. This is a fasciocutaneous free flap based on the saphenofemoral vascular pedicle. The flap may include the entire medial aspect of the lower leg between the knee and ankle. Thirty flaps were harvested from 15 inbred rats. Each flap was transferred to the anterior neck of a recipient rat of the same inbred strain so that 15 flaps were vascularized free flaps using the standard end-to-end microvascular technique and the other 15 flaps were nonvascularized free grafts. All but two (technical failure) of the vascularized flaps showed complete survival, whereas all nonvascularized flaps completely necrosed 2 weeks after transfer. It was concluded that the rat saphenous flap has several advantages such as a long and consistent vascular pedicle, ease of harvest, and an all-or-none survival pattern. Furthermore, as a unique feature of this flap, histological analysis revealed that the rat saphenous flap is composed of the skin and underlying fascia without panniculus carnosus. We therefore suggest that the rat saphenous flap is the first true fasciocutaneous free flap model in the rat. In this paper, in addition to illustrating the anatomy of the saphenous vessels and describing a new fasciocutaneous free flap model based on these vessels, we have documented some anatomical details of the rat leg that have never been described in the literature related to the rat anatomy.

  7. The evolution of perforator flap breast reconstruction: twenty years after the first DIEP flap.

    Science.gov (United States)

    Healy, Claragh; Allen, Robert J

    2014-02-01

    It is over 20 years since the inaugural deep inferior epigastric perforator (DIEP) flap breast reconstruction. We review the type of flap utilized and indications in 2,850 microvascular breast reconstruction over the subsequent 20 years in the senior author's practice (Robert J. Allen). Data were extracted from a personal logbook of all microsurgical free flap breast reconstructions performed between August 1992 and August 2012. Indication for surgery; mastectomy pattern in primary reconstruction; flap type, whether unilateral or bilateral; recipient vessels; and adjunctive procedures were recorded. The DIEP was the most commonly performed flap (66%), followed by the superior gluteal artery perforator flap (12%), superficial inferior epigastric artery perforator flap (9%), inferior gluteal artery perforator flap (6%), profunda artery perforator flap (3%), and transverse upper gracilis flap (3%). Primary reconstruction accounted for 1,430 flaps (50%), secondary 992 (35%), and tertiary 425 (15%). As simultaneous bilateral reconstructions, 59% flaps were performed. With each flap, there typically ensues a period of enthusiasm which translated into surge in flap numbers. However, each flap has its own nuances and characteristics that influence patient and physician choice. Of note, each newly introduced flap, either buttock or thigh, results in a sharp decline in its predecessor. In this practice, the DIEP flap has remained the first choice in autologous breast reconstruction. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

  8. Buried free flaps in head and neck reconstruction: higher risk of free flap failure?

    Science.gov (United States)

    Reiter, M; Harréus, U; Kisser, U; Betz, C S; Baumeister, Ph

    2017-01-01

    Thrombosis of the pedicle is central to free flap failure, and early revision of a compromised flap is the key to successfully salvage a flap. Therefore, the majority of free flaps in reconstructive head and neck surgery are used with the ability to visually examine the flap. Sometimes, due to intra-operative circumstances, it is necessary to use a flap that cannot be monitored externally. These flaps are called buried flaps and have the reputation of being put at risk. The current literature provides only limited data to support or disprove this position. A single institution retrospective review of patient charts between 2007 and 2015 was performed. Flap monitoring was carried out with hand-held Doppler of the pedicle hourly for the first 72 h in all cases. Additional duplex ultrasound was performed in the majority of buried flaps. A total of 437 flaps were included into the study. 37 flaps (7.8 %) were identified to fulfill the criteria of a buried free flap. In total, four patients had complications, three of which required operative reexploration. All interventions were successful, resulting in no flap loss in our series. An accurate operation technique combined with meticulous monitoring protocols supported by duplex ultrasound can result in satisfactory outcome of buried flaps. No enhanced risk of flap loss of buried flaps was found in our cohort.

  9. Liquid Self-Balancing Device Effects on Flexible Rotor Stability

    Directory of Open Access Journals (Sweden)

    Leonardo Urbiola-Soto

    2013-01-01

    Full Text Available Nearly a century ago, the liquid self-balancing device was first introduced by M. LeBlanc for passive balancing of turbine rotors. Although of common use in many types or rotating machines nowadays, little information is available on the unbalance response and stability characteristics of this device. Experimental fluid flow visualization evidences that radial and traverse circulatory waves arise due to the interaction of the fluid backward rotation and the baffle boards within the self-balancer annular cavity. The otherwise destabilizing force induced by trapped fluids in hollow rotors, becomes a stabilizing mechanism when the cavity is equipped with adequate baffle boards. Further experiments using Particle Image Velocimetry (PIV enable to assess the active fluid mass fraction to be one-third of the total fluid mass. An analytical model is introduced to study the effects of the active fluid mass fraction on a flexible rotor supported by flexible supports excited by bwo different destabilizing mechanisms; rotor internal friction damping and aerodynamic cross-coupling. It is found that the fluid radial and traverse forces contribute to the balancing action and to improve the rotor stability, respectively.

  10. Parametric study of fluid flow manipulation with piezoelectric macrofiber composite flaps

    Science.gov (United States)

    Sadeghi, O.; Tarazaga, P.; Stremler, M.; Shahab, S.

    2017-04-01

    Active Fluid Flow Control (AFFC) has received great research attention due to its significant potential in engineering applications. It is known that drag reduction, turbulence management, flow separation delay and noise suppression through active control can result in significantly increased efficiency of future commercial transport vehicles and gas turbine engines. In microfluidics systems, AFFC has mainly been used to manipulate fluid passing through the microfluidic device. We put forward a conceptual approach for fluid flow manipulation by coupling multiple vibrating structures through flow interactions in an otherwise quiescent fluid. Previous investigations of piezoelectric flaps interacting with a fluid have focused on a single flap. In this work, arrays of closely-spaced, free-standing piezoelectric flaps are attached perpendicular to the bottom surface of a tank. The coupling of vibrating flaps due to their interacting with the surrounding fluid is investigated in air (for calibration) and under water. Actuated flaps are driven with a harmonic input voltage, which results in bending vibration of the flaps that can work with or against the flow-induced bending. The size and spatial distribution of the attached flaps, and the phase and frequency of the input actuation voltage are the key parameters to be investigated in this work. Our analysis will characterize the electrohydroelastic dynamics of active, interacting flaps and the fluid motion induced by the system.

  11. Experimental Study of Active Techniques for Blade/Vortex Interaction Noise Reduction

    Science.gov (United States)

    Kobiki, Noboru; Murashige, Atsushi; Tsuchihashi, Akihiko; Yamakawa, Eiichi

    This paper presents the experimental results of the effect of Higher Harmonic Control (HHC) and Active Flap on the Blade/Vortex Interaction (BVI) noise. Wind tunnel tests were performed with a 1-bladed rotor system to evaluate the simplified BVI phenomenon avoiding the complicated aerodynamic interference which is characteristically and inevitably caused by a multi-bladed rotor. Another merit to use this 1-bladed rotor system is that the several objective active techniques can be evaluated under the same condition installed in the same rotor system. The effects of the active techniques on the BVI noise reduction were evaluated comprehensively by the sound pressure, the blade/vortex miss distance obtained by Laser light Sheet (LLS), the blade surface pressure distribution and the tip vortex structure by Particle Image Velocimetry (PIV). The correlation among these quantities to describe the effect of the active techniques on the BVI conditions is well obtained. The experiments show that the blade/vortex miss distance is more dominant for BVI noise than the other two BVI governing factors, such as blade lift and vortex strength at the moment of BVI.

  12. Rotor/Wing Interactions in Hover

    Science.gov (United States)

    Young, Larry A.; Derby, Michael R.

    2002-01-01

    Hover predictions of tiltrotor aircraft are hampered by the lack of accurate and computationally efficient models for rotor/wing interactional aerodynamics. This paper summarizes the development of an approximate, potential flow solution for the rotor-on-rotor and wing-on-rotor interactions. This analysis is based on actuator disk and vortex theory and the method of images. The analysis is applicable for out-of-ground-effect predictions. The analysis is particularly suited for aircraft preliminary design studies. Flow field predictions from this simple analytical model are validated against experimental data from previous studies. The paper concludes with an analytical assessment of the influence of rotor-on-rotor and wing-on-rotor interactions. This assessment examines the effect of rotor-to-wing offset distance, wing sweep, wing span, and flaperon incidence angle on tiltrotor inflow and performance.

  13. The Diver with a Rotor

    CERN Document Server

    Bharadwaj, Sudarsh; Dullin, Holger R; Leung, Karen; Tong, William

    2015-01-01

    We present and analyse a simple model for the twisting somersault. The model is a rigid body with a rotor attached which can be switched on and off. This makes it simple enough to devise explicit analytical formulas whilst still maintaining sufficient complexity to preserve the shape-changing dynamics essential for twisting somersaults in springboard and platform diving. With `rotor on' and with `rotor off' the corresponding Euler-type equations can be solved, and the essential quantities characterising the dynamics, such as the periods and rotation numbers, can be computed in terms of complete elliptic integrals. Thus we arrive at explicit formulas for how to achieve a dive with m somersaults and n twists in a given total time. This can be thought of as a special case of a geometric phase formula due to Cabrera 2007.

  14. On cup anemometer rotor aerodynamics.

    Science.gov (United States)

    Pindado, Santiago; Pérez, Javier; Avila-Sanchez, Sergio

    2012-01-01

    The influence of anemometer rotor shape parameters, such as the cups' front area or their center rotation radius on the anemometer's performance was analyzed. This analysis was based on calibrations performed on two different anemometers (one based on magnet system output signal, and the other one based on an opto-electronic system output signal), tested with 21 different rotors. The results were compared to the ones resulting from classical analytical models. The results clearly showed a linear dependency of both calibration constants, the slope and the offset, on the cups' center rotation radius, the influence of the front area of the cups also being observed. The analytical model of Kondo et al. was proved to be accurate if it is based on precise data related to the aerodynamic behavior of a rotor's cup.

  15. Treatment of degloving injury involving multiple fingers with combined abdominal superficial fascial flap, dorsalis pedis flap, dorsal toe flap, and toe-web flap.

    Science.gov (United States)

    Han, Fengshan; Wang, Guangnan; Li, Gaoshan; Ping, Juan; Mao, Zhi

    2015-01-01

    Our aim was to summarize the treatment of degloving injury involving multiple fingers using combined abdominal superficial fascial flap, dorsalis pedis flap, dorsal toe flap, and toe-web flap. Each degloved finger was debrided under microscopic guidance and embedded in the superficial layer of the abdominal fascia. The abdominal skin was sutured to the skin on the back and side of the hand to promote circumferential healing. After removal, the only remaining injured region was on the flexor surface, and this was repaired by multiple dorsal toe flaps, toe-web flaps, and dorsalis pedis flaps to provide blood vessels and sensory nerves. All fingers had proper flap thickness 3-6 months after surgery, and required only lateral Z-plasty modification with web deepening and widening to narrow the fingers and extend their relative length. We completed flap-graft and finger narrowing for 25 fingers in eight patients. Abdominal skin flaps and dorsal toe flaps were grafted, and resulted in both firmness and softness, providing finger flexibility. The dorsal toe flap provided good blood circulation and sensory nerves, and was used to cover the finger-flexor surface to regain sensation and stability when holding objects. During the 1-8 years of follow-up, sensation on the finger-flexor side recovered to the S3-4 level, and patient satisfaction based on the Michigan Hand Outcomes Questionnaire was 4-5. Flap ulcers or bone/tendon necrosis were not observed. Treatment of degloving injury involving multiple fingers with combined abdominal superficial fascial flap, dorsalis pedis flap, dorsal toe flap, and toe-web flap was effective and reliable.

  16. PIV Measurements on a Blowing Flap

    Science.gov (United States)

    Hutcheson, Florence V.; Stead, Daniel J.

    2004-01-01

    PIV measurements of the flow in the region of a flap side edge are presented for several blowing flap configurations. The test model is a NACA 63(sub 2)-215 Hicks Mod-B main-element airfoil with a half-span Fowler flap. Air is blown from small slots located along the flap side edge on either the top, bottom or side surfaces. The test set up is described and flow measurements for a baseline and three blowing flap configurations are presented. The effects that the flap tip jets have on the structure of the flap side edge flow are discussed for each of the flap configurations tested. The results indicate that blowing air from a slot located along the top surface of the flap greatly weakened the top vortex system and pushed it further off the top surface. Blowing from the bottom flap surface kept the strong side vortex further outboard while blowing from the side surface only strengthened the vortex system or accelerated the merging of the side vortex to the flap top surface. It is concluded that blowing from the top or bottom surfaces of the flap may lead to a reduction of flap side edge noise.

  17. Transonic Axial Splittered Rotor Tandem Stator Stage

    Science.gov (United States)

    2016-12-01

    compressor rotor was designed incorporating a splitter vane between the principal blades . Historical experiments conducted by Dr. Arthur J...conventional rotor design . The stage is composed of the rotor and stator. The flow of the air passing through the rotor is turned, and the flow is required...derived results achieved the best blade geometry for design continuation. The best circumferential and axial placement for the splitter blade was

  18. Beneficial Effects of Aminoguanidine on Skin Flap Survival in Diabetic Rats

    Directory of Open Access Journals (Sweden)

    Ayse Ozturk

    2012-01-01

    Full Text Available Random flaps in DM patients have poor reliability for wound coverage, and flap loss remains a complex challenge. The protective effects of aminoguanidine (AG administration on the survival of dorsal random flaps and oxidative stress were studied in diabetic rats. Two months after the onset of DM, dorsal McFarlane flaps were raised. Forty rats were divided into four groups: (1 control, (2 AG, (3 DM, and (4 DM + AG groups. Flap viability, determined with the planimetric method, and free-radical measurements were investigated. In addition, HbA1c and blood glucose levels, body weight measurements, and histopathological examinations were evaluated. The mean flap necrotic areas (% in Groups I to IV were 50.9 ± 13.0, 32.9 ± 12.5, 65.2 ± 11.5, and 43.5 ± 14.7, respectively. The malondialdehyde (MDA and nitric oxide (NO levels were higher in the DM group than in the nondiabetic group, while the reduced glutathione (GSH levels and superoxide dismutase (SOD activity were reduced as a result of flap injury. In the diabetic and nondiabetic groups, AG administration significantly reduced the MDA and NO levels and significantly increased GSH content and SOD enzyme activity. We concluded that AG plays an important role in preventing random pattern flap necrosis.

  19. Free digital artery flap: an ideal flap for large finger defects in situations where local flaps are precluded.

    Science.gov (United States)

    Wong, Chin-Ho; Teoh, Lam-Chuan; Lee, Jonathan Y-L; Yam, Andrew K-T; Khoo, David B-A; Yong, Fok-Chuan

    2008-03-01

    The heterodigital arterialized flap is increasingly accepted as a flap of choice for reconstruction of large finger wounds. However, in situations where the adjacent fingers sustained concomitant injuries, the use of this flap as a local flap is precluded. This paper describes our experience with the free digital artery flap as an evolution of the heterodigital arterialized flap. Four patients with large finger wounds were reconstructed with free digital artery flap. Our indications for digital artery free flap were concomitant injuries to adjacent fingers that precluded their use as donor sites. The arterial supply of the flap was from the digital artery and the venous drainage was from the dominant dorsal vein of the finger. The flap was harvested from the ulnar side of the finger. The digital nerve was left in situ to minimize donor morbidity. The donor site was covered with a full-thickness skin graft and secured with bolster dressings. Early intensive mobilization was implemented for all patients. All flaps survived. No venous congestion was noted and primary healing was achieved in all flaps. In addition to providing well-vascularized tissue for coverage of vital structures, the digital artery was also used as a flow-through flap for finger revascularization in one patient. Donor-site morbidity was minimal, with all fingers retaining protective pulp sensation and the distal and proximal interphalangeal joints retaining full ranges of motion. In conclusion, the free digital artery flap is a versatile flap that is ideal for coverage of large-sized finger defects in situations where local flaps are unavailable. Donor-site morbidity can be minimized by preservation of the digital nerve, firmly securing the skin graft with bolster dressings, and early mobilization of the donor finger.

  20. Combined posterior flap and anterior suspended flap dacryocystorhinostomy: A modification of external dacryocystorhinostomy

    Directory of Open Access Journals (Sweden)

    Amarendra Deka

    2010-01-01

    Conclusion : We believe that combined posterior flap and anterior suspended flap DCR technique is simple to perform and has the advantage of both double flap DCR and anterior suspension of anterior flaps. The results of the study showed the efficacy of this simple modification.

  1. Results of the AVATAR project for the validation of 2D aerodynamic models with experimental data of the DU95W180 airfoil with unsteady flap

    Science.gov (United States)

    Ferreira, C.; Gonzalez, A.; Baldacchino, D.; Aparicio, M.; Gómez, S.; Munduate, X.; Garcia, N. R.; Sørensen, J. N.; Jost, E.; Knecht, S.; Lutz, T.; Chassapogiannis, P.; Diakakis, K.; Papadakis, G.; Voutsinas, S.; Prospathopoulos, J.; Gillebaart, T.; van Zuijlen, A.

    2016-09-01

    The FP7 AdVanced Aerodynamic Tools for lArge Rotors - Avatar project aims to develop and validate advanced aerodynamic models, to be used in integral design codes for the next generation of large scale wind turbines (10-20MW). One of the approaches towards reaching rotors for 10-20MW size is the application of flow control devices, such as flaps. In Task 3.2: Development of aerodynamic codes for modelling of flow devices on aerofoils and, rotors of the Avatar project, aerodynamic codes are benchmarked and validated against the experimental data of a DU95W180 airfoil in steady and unsteady flow, for different angle of attack and flap settings, including unsteady oscillatory trailing-edge-flap motion, carried out within the framework of WP3: Models for Flow Devices and Flow Control, Task 3.1: CFD and Experimental Database. The aerodynamics codes are: AdaptFoil2D, Foil2W, FLOWer, MaPFlow, OpenFOAM, Q3UIC, ATEFlap. The codes include unsteady Eulerian CFD simulations with grid deformation, panel models and indicial engineering models. The validation cases correspond to 18 steady flow cases, and 42 unsteady flow cases, for varying angle of attack, flap deflection and reduced frequency, with free and forced transition. The validation of the models show varying degrees of agreement, varying between models and flow cases.

  2. Assessment Report on Innovative Rotor Blades (MAREWINT WP1,D1.3)

    DEFF Research Database (Denmark)

    McGugan, Malcolm; Leble, Vladimir; Pereira, Gilmar Ferreira

    the innovative concept development for wind turbine blades. This covers models and experiments with damage measurement systems embedded within the composite material/structure and numerical methods investigating the effects of leading and trailing edge flaps on modifying the aerodynamic loads on the operating......The offshore wind energy industry faces many challenges in the short to medium term if it is to meet the ambitions of the global community for sustainable energy supply in the future. Not least among these challenges is the issue of rotor blades. Innovative design for “smart” rotor blades...... with embedded sensors and actuation are being developed that will deliver an improved whole-life performance, and a structural health management based operational concept. In this report, the work of two early stage researchers within the Initial Training Network MAREWINT is presented that support...

  3. Comparison of outcomes of pressure sore reconstructions among perforator flaps, perforator-based rotation fasciocutaneous flaps, and musculocutaneous flaps.

    Science.gov (United States)

    Kuo, Pao-Jen; Chew, Khong-Yik; Kuo, Yur-Ren; Lin, Pao-Yuan

    2014-10-01

    Pressure sore reconstruction remains a significant challenge for plastic surgeons due to its high postoperative complication and recurrence rates. Free-style perforator flap, fasciocutaeous flap, and musculocutaneous flap are the most common options in pressure sore reconstructions. Our study compared the postoperative complications among these three flaps at Kaohsiung Chang Gung Memorial Hospital. From 2003 to 2012, 99 patients (54 men and 45 women) with grade III or IV pressure sores received regional flap reconstruction, consisting of three cohorts: group A, 35 free-style perforator-based flaps; group B, 37 gluteal rotation fasciocutaneous flaps; and group C, 27 musculocutaneous or muscle combined with fasciocutaneous flap. Wound complications such as wound infection, dehiscence, seroma formation of the donor site, partial or complete flap loss, and recurrence were reviewed. The mean follow-up period for group A was 24.2 months, 20.8 months in group B, and 19.0 months for group C. The overall complication rate was 22.9%, 32.4%, and 22.2% in groups A, B, and C, respectively. The flap necrosis rate was 11.4%, 13.5%, and 0% in groups A, B, and C, respectively. There was no statistical significance regarding complication rate and flap necrosis rate among different groups. In our study, the differences of complication rates and flap necrosis rate between these groups were not statistically significant. Further investigations should be conducted. © 2014 Wiley Periodicals, Inc.

  4. Traumatic Forefoot Reconstructions With Free Perforator Flaps.

    Science.gov (United States)

    Zhu, Yue-Liang; He, Xiao-Qing; Wang, Yi; Lv, Qian; Fan, Xin-Yv; Xu, Yong-Qing

    2015-01-01

    The forefoot is critical to normal walking; thus, any reconstruction of forefoot defects, including the soft tissues, must be carefully done. The free perforator flap, with its physiologic circulation, lower donor site morbidity, and minimal thickness is the most popular technique in plastic and microsurgery, and is theoretically the most suitable for such forefoot reconstruction. However, these flaps are generally recognized as more difficult and time-consuming to create than other flaps. In 41 patients with traumatic forefoot defects, we reconstructed the forefoot integument using 5 types of free perforator flaps. The overall functional and cosmetic outcomes were excellent. Three flaps required repeat exploration; one survived. The most common complications were insufficient perfusion and the need for second debulking. The key to our success was thoroughly debriding devitalized bone and soft tissue before attaching the flap. Forefoot reconstruction with a free perforator flap provides better function, better cosmesis, better weightbearing, and better gait than the other flaps we have used.

  5. [Development and current status of perforator flaps].

    Science.gov (United States)

    Xu, Dachuan; Zhang, Shimin; Tang, Maolin; Ouyang, Jun

    2011-09-01

    To provide a comprehensive review for development and existing problems of the perforator flaps. The related home and abroad literature concerning perforator flaps was extensively reviewed. The perforator flaps are defined as the axial flaps nourished solely by small cutaneous perforating vessels (perforating arteries and veins), which are exclusively composed of skin and subcutaneous fat. The perforator flaps have the advantages as follows: less injury at donor site, less damage to the contour of the donor site, good reconstruction and appearance of the recipient site flexible design, and short time of postoperative recovery, which have been widely used in reconstructive surgery. The perforator flaps are the new development of the microsurgery, which usher an era of small axial flaps; However, the controversies of the definition, vascular classification, the nomenclature, and the clinical application of the perforator flaps still exist, which are therefore the hot spot for future study.

  6. An analytical investigation of the performance of wind-turbines with gyrocopter-like rotors

    Energy Technology Data Exchange (ETDEWEB)

    Kentfield, J.A.C.; Brophy, D.C. [Univ. of Calgary, Alberta (Canada)

    1997-12-31

    The performance was predicted of a wind-turbine, intended for electrical power generation, the rotor of which is similar in configuration to the rotor of an autogyro or gyrocopter as originated by Cierva. Hence the rotor axis of spin is tilted downwind, for maximum power production, by an angle of 40{degrees} to 50{degrees} relative to the vertical with power regulation by modulation of the tilt angle. Because the rotor of a Cierva turbine generates lift the simple, non-twisted, fixed-pitch blades {open_quotes}fly{close_quotes} and are self supporting thereby eliminating flap-wise bending moments when the blades are hinged at their roots. It was found from the analysis that it is possible to reduce tower bending moments substantially relative to a conventional horizontal axis turbine of equal power output and also, for equal maximum hub heights and blade tip altitudes, a Cierva turbine is capable, at a prescribed wind speed, of a greater power output than a conventional horizontal axis machine.

  7. Fibular flap for mandible reconstruction in osteoradionecrosis of the jaw: selection criteria of fibula flap

    OpenAIRE

    Kim, Ji-Wan; Hwang, Jong-Hyun; Ahn, Kang-Min

    2016-01-01

    Background Osteoradionecrosis is the most dreadful complication after head and neck irradiation. Orocutaneous fistula makes patients difficult to eat food. Fibular free flap is the choice of the flap for mandibular reconstruction. Osteocutaneous flap can reconstruct both hard and soft tissues simultaneously. This study was to investigate the success rate and results of the free fibular flap for osteoradionecrosis of the mandible and which side of the flap should be harvested for better recons...

  8. Phosphate steering by Flap Endonuclease 1 promotes 5′-flap specificity and incision to prevent genome instability

    KAUST Repository

    Tsutakawa, Susan E.

    2017-06-27

    DNA replication and repair enzyme Flap Endonuclease 1 (FEN1) is vital for genome integrity, and FEN1 mutations arise in multiple cancers. FEN1 precisely cleaves single-stranded (ss) 5\\'-flaps one nucleotide into duplex (ds) DNA. Yet, how FEN1 selects for but does not incise the ss 5\\'-flap was enigmatic. Here we combine crystallographic, biochemical and genetic analyses to show that two dsDNA binding sites set the 5\\'polarity and to reveal unexpected control of the DNA phosphodiester backbone by electrostatic interactions. Via phosphate steering\\', basic residues energetically steer an inverted ss 5\\'-flap through a gateway over FEN1\\'s active site and shift dsDNA for catalysis. Mutations of these residues cause an 18,000-fold reduction in catalytic rate in vitro and large-scale trinucleotide (GAA) repeat expansions in vivo, implying failed phosphate-steering promotes an unanticipated lagging-strand template-switch mechanism during replication. Thus, phosphate steering is an unappreciated FEN1 function that enforces 5\\'-flap specificity and catalysis, preventing genomic instability.

  9. Lightning protection of flap system for wind turbine blades

    DEFF Research Database (Denmark)

    Candela Garolera, Anna; Madsen, Søren Find

    The aim of this PhD project was to investigate the behaviour of a Controllable Rubber Trailing Edge Flap (CRTEF) in a wind turbine blade when it is exposed to lightning discharges, and find the best technical solution to protect the CRTEF and the controlling system against lightning, based...... on the results of simulation models and high voltage tests. Wind turbines are a common target of lightning due to their height and location, and blades are the components most exposed to direct discharges. Protecting the blades against lightning is specially challenging, mainly because of the combination...... of a broader, EUDP funded project, whose overall objective was to develop a prototype active trailing edge flap system for a wind turbine blade which constitutes a complete, reliable and robust load control flap system for a full scale turbine, ready for prototype testing....

  10. Genetics Home Reference: Rotor syndrome

    Science.gov (United States)

    ... of these proteins. Without the function of either transport protein, bilirubin is less efficiently taken up by the ... Schinkel AH. Complete OATP1B1 and OATP1B3 deficiency causes human Rotor syndrome by interrupting conjugated bilirubin reuptake into ...

  11. The effect of platelet rich plasma on angiogenesis in ischemic flaps in VEGFR2-luc mice.

    Science.gov (United States)

    Sönmez, Tolga Taha; Vinogradov, Alexandra; Zor, Fatih; Kweider, Nisreen; Lippross, Sebastian; Liehn, Elisa Anamaria; Naziroglu, Mustafa; Hölzle, Frank; Wruck, Christoph; Pufe, Thomas; Tohidnezhad, Mersedeh

    2013-04-01

    To improve skin flap healing, one promising strategy in reconstructive surgery might be to optimize platelet rich plasma (PRP) bioactivity and the ischemia-altered expression of genes. We studied both the effect of PRP on ischemic flaps, and whether in vivo bioluminescence imaging (BLI) is a suitable method for the longitudinal monitoring of angiogenesis in surgical wounds. Axial murine skin flaps were created in four experimental groups. In vivo measurements of VEGFR2 expression levels were made every other day until the 14th day. The local VEGF level and microvessel density were quantified on the 14th day via ELISA and immunohistochemistry, and flap survival rates were measured. We demonstrated that PRP and induced ischemia have a beneficial influence on angiogenesis and flap healing. Combining the two resulted in a significantly robust increase in angiogenesis and flap survival rate that was corroborated by bioluminescence imaging of VEGFR2 activity. This study shows that angiogenic effects of PRP may be potentialized by the stimulus of induced ischemia during free flap harvesting, and thus the two procedures appear to have a synergistic effect on flap healing. This study further demonstrates that BLI of modulated genes in reconstructive surgery is a valuable model for longitudinal in vivo evaluation of angiogenesis.

  12. Flap-lag damping in hover and forward flight with a three-dimensional wake

    Science.gov (United States)

    Manjunath, A. R.; Hagabhushanam, J.; Gaonkar, Gopal H.; Peters, David A.; Su, AY

    1992-01-01

    Prediction of lag damping is difficult owing to the delicate balance of drag, induced drag and Coriolis forces in the in-plane direction. Moreover, induced drag is sensitive to dynamic wake, both shed and trailing components, and thus its prediction requires adequate unsteady-wake representation. Accordingly, rigid-blade flap-lag equations are coupled with a three-dimensional finite-state wake model; three isolated rotor configurations with three, four and five blades are treated over a range of thrust levels, Lock numbers, lag frequencies and advance ratios. The investigation includes convergence characteristics of damping with respect to the number of shape functions and harmonics of the wake model for multiblade modes of low frequency (less than 1/rev.) to high frequency (greater than l/rev.). Predicted flap and lag damping levels are then compared with similar predictions with (1) rigid wake (no unsteady induced flow), (2) Loewy lift deficiency, and (3) dynamic inflow.

  13. Rotor damage detection by using piezoelectric impedance

    Science.gov (United States)

    Qin, Y.; Tao, Y.; Mao, Y. F.

    2016-04-01

    Rotor is a core component of rotary machinery. Once the rotor has the damage, it may lead to a major accident. Thus the quantitative rotor damage detection method based on piezoelectric impedance is studied in this paper. With the governing equation of piezoelectric transducer (PZT) in a cylindrical coordinate, the displacement along the radius direction is derived. The charge of PZT is calculated by the electric displacement. Then, by the use of the obtained displacement and charge, an analytic piezoelectric impedance model of the rotor is built. Given the circular boundary condition of a rotor, annular elements are used as the analyzed objects and spectral element method is used to set up the damage detection model. The Electro-Mechanical (E/M) coupled impedance expression of an undamaged rotor is deduced with the application of a low-cost impedance test circuit. A Taylor expansion method is used to obtain the approximate E/M coupled impedance expression for the damaged rotor. After obtaining the difference between the undamaged and damaged rotor impedance, a rotor damage detection method is proposed. This method can directly calculate the change of bending stiffness of the structural elements, it follows that the rotor damage can be effectively detected. Finally, a preset damage configuration is used for the numerical simulation. The result shows that the quantitative damage detection algorithm based on spectral element method and piezoelectric impedance proposed in this paper can identify the location and the severity of the damaged rotor accurately.

  14. Advances in tilt rotor noise prediction

    Science.gov (United States)

    George, A. R.; Coffen, C. D.; Ringler, T. D.

    The two most serious tilt rotor external noise problems, hover noise and blade-vortex interaction noise, are studied. The results of flow visualization and inflow velocity measurements document a complex, recirculating highly unsteady and turbulent flow due to the rotor-wing-body interactions characteristic of tilt rotors. The wing under the rotor is found to obstruct the inflow, causing a deficit in the inflow velocities over the inboard region of the rotor. Discrete frequency harmonic thickness and loading noise mechanisms in hover are examined by first modeling tilt rotor hover aerodynamics and then applying various noise prediction methods using the WOPWOP code. The analysis indicates that the partial ground plane created by the wing below the rotor results in a primary sound source for hover.

  15. Control of Rotor-Blade Coupled Vibrations Using Shaft-Based Actuation

    DEFF Research Database (Denmark)

    Christensen, Rene H.; Santos, Ilmar

    2006-01-01

    When implementing active control into bladed rotating machines aiming at reducing blade vibrations, it can be shown that blade as well as rotor vibrations can in fact be controlled by the use of only shaft-based actuation. Thus the blades have to be deliberately mistuned. This paper investigates...... of modal controllability and observability converge toward steady levels as the degree of mistuning is increased. Finally, experimental control results are presented to prove the theoretical conclusions and to show the feasibility of controlling rotor and blade vibrations by means of shaft-based actuation...... the dynamical characteristics of a mistuned bladed rotor and shows how, why and when a bladed rotor becomes controllable and observable if properly mistuned. As part of such investigation modal controllability and observability of a tuned as well as a mistuned coupled rotor-blade system are analysed...

  16. Rotor position and vibration control for aerospace flywheel energy storage devices and other vibration based devices

    Science.gov (United States)

    Alexander, B. X. S.

    Flywheel energy storage has distinct advantages over conventional energy storage methods such as electrochemical batteries. Because the energy density of a flywheel rotor increases quadratically with its speed, the foremost goal in flywheel design is to achieve sustainable high speeds of the rotor. Many issues exist with the flywheel rotor operation at high and varying speeds. A prominent problem is synchronous rotor vibration, which can drastically limit the sustainable rotor speed. In a set of projects, the novel Active Disturbance Rejection Control (ADRC) is applied to various problems of flywheel rotor operation. These applications include rotor levitation, steady state rotation at high speeds and accelerating operation. Several models such as the lumped mass model and distributed three-mass models have been analyzed. In each of these applications, the ADRC has been extended to cope with disturbance, noise, and control effort optimization; it also has been compared to various industry-standard controllers such as PID and PD/observer, and is proven to be superior. The control performance of the PID controller and the PD/observer currently used at NASA Glenn has been improved by as much as an order of magnitude. Due to the universality of the second order system, the results obtained in the rotor vibration problem can be straightforwardly extended to other vibrational systems, particularly, the MEMS gyroscope. Potential uses of a new nonlinear controller, which inherits the ease of use of the traditional PID, are also discussed.

  17. Predictions of Control Inputs, Periodic Responses and Damping Levels of an Isolated Experimental Rotor in Trimmed Flight

    Science.gov (United States)

    Gaonkar, G. H.; Subramanian, S.

    1996-01-01

    Since the early 1990s the Aeroflightdynamics Directorate at the Ames Research Center has been conducting tests on isolated hingeless rotors in hover and forward flight. The primary objective is to generate a database on aeroelastic stability in trimmed flight for torsionally soft rotors at realistic tip speeds. The rotor test model has four soft inplane blades of NACA 0012 airfoil section with low torsional stiffness. The collective pitch and shaft tilt are set prior to each test run, and then the rotor is trimmed in the following sense: the longitudinal and lateral cyclic pitch controls are adjusted through a swashplate to minimize the 1/rev flapping moment at the 12 percent radial station. In hover, the database comprises lag regressive-mode damping with pitch variations. In forward flight the database comprises cyclic pitch controls, root flap moment and lag regressive-mode damping with advance ratio, shaft angle and pitch variations. This report presents the predictions and their correlation with the database. A modal analysis is used, in which nonrotating modes in flap bending, lag bending and torsion are computed from the measured blade mass and stiffness distributions. The airfoil aerodynamics is represented by the ONERA dynamic stall models of lift, drag and pitching moment, and the wake dynamics is represented by a state-space wake model. The trim analysis of finding, the cyclic controls and the corresponding, periodic responses is based on periodic shooting with damped Newton iteration; the Floquet transition matrix (FTM) comes out as a byproduct. The stabillty analysis of finding the frequencies and damping levels is based on the eigenvalue-eigenvector analysis of the FTM. All the structural and aerodynamic states are included from modeling to trim analysis. A major finding is that dynamic wake dramatically improves the correlation for the lateral cyclic pitch control. Overall, the correlation is fairly good.

  18. Suspension Bridge Flutter for Girder with Separate Control Flaps

    DEFF Research Database (Denmark)

    Huynh, T.; Thoft-Christensen, Palle

    Active vibration control of long span suspension bridge flutter using separated control flaps (SFSC) has shown to increase effectively the critical wind speed of bridges. In this paper, an SFSC calculation based on modal equations of the vertical and torsional motions of the bridge girder including...

  19. Swashplateless Helicopter Experimental Investigation: Primary Control with Trailing Edge Flaps Actuated with Piezobenders

    Science.gov (United States)

    Copp, Peter

    Helicopter rotor primary control is conventionally carried out using a swashplate with pitch links. Eliminating the swashplate promises to reduce the helicopter's parasitic power in high speed forward flight, as well as may lead to a hydraulic-less vehicle. A Mach-scale swashplateless rotor is designed with integrated piezobender-actuated trailing edge flaps and systematically tested on the benchtop, in the vacuum chamber and on the hoverstand. The blade is nominally based on the UH-60 rotor with a hover tip Mach number of 0.64. The blade diameter is 66 inches requiring 2400 RPM for Mach scale simulation. The rotor hub is modified to reduce the blade fundamental torsional frequency to less than 2.0/rev by replacing the rigid pitch links with linear springs, which results in an increase of the blade pitching response to the trailing edge flaps. Piezoelectric multilayer benders provide the necessary bandwidth, stroke and stiffness to drive the flaps for primary control while fitting inside the blade profile and withstanding the high centrifugal forces. This work focuses on several key issues. A piezobender designed from a soft piezoelectric material, PZT-5K4, is constructed. The new material is used to construct multi-layer benders with increased stroke for the same stiffness relative to hard materials such as PZT-5H2. Each layer has a thickness of 10 mils. The soft material with gold electrodes requires a different bonding method than hard material with nickel electrodes. With this new bonding method, the measured stiffness matches precisely the predicted stiffness for a 12 layer bender with 1.26 inch length and 1.0 inch width with a stiffness of 1.04 lb/mil. The final in-blade bender has a length of 1.38 inches and 1.0 inch width with a stiffness of 0.325 lb/mil and stroke of 20.2 mils for an energy output of 66.3 lb-mil. The behavior of piezobenders under very high electric fields is investigated. High field means +18.9 kV/cm (limited by arcing in air) and -3.54k

  20. Dynamic flaps in HIV-1 protease adopt unique ordering at different stages in the catalytic cycle.

    Science.gov (United States)

    Karthik, Suresh; Senapati, Sanjib

    2011-06-01

    The flexibility of HIV-1 protease flaps is known to be essential for the enzymatic activity. Here we attempt to capture a multitude of conformations of the free and substrate-bound HIV-1 protease that differ drastically in their flap arrangements. The substrate binding process suggests the opening of active site gate in conjunction with a reversal of flap tip ordering, from the native semiopen state. The reversed-flap, open-gated enzyme readily transforms to a closed conformation after proper placement of the substrate into the binding cleft. After substrate processing, the closed state protease which possessed opposite flap ordering relative to the semiopen state, encounters another flap reversal via a second open conformation that facilitates the evolution of native semiopen state of correct flap ordering. The complicated transitional pathway, comprising of many high and low energy states, is explored by combining standard and activated molecular dynamics (MD) simulation techniques. The study not only complements the existing findings from X-ray, NMR, EPR, and MD studies but also provides a wealth of detailed information that could help the structure-based drug design process. Copyright © 2011 Wiley-Liss, Inc.

  1. [Functional hemitongue reconstruction with free forearm flap].

    Science.gov (United States)

    Liao, Gui-Qing; Su, Yu-Xiong; Liu, Hai-Chao; Li, Jin; Fahmha, Numan; Ou, De-Ming; Wang, Qin

    2008-07-01

    To investigate the clinical application of free forearm flap in the functional hemitongue reconstruction. From July 2002 to November 2006, 40 patients with tongue cancer underwent hemiglossectomy and primary hemitongue reconstruction with free forearm flaps. In some cases, the lateral antebrachial cutaneous nerves of the flaps were anastomosed with the lingual nerve to restore the flap sensation. All patients recovered uneventfully after surgery with no morbidity in the donor site. All free flaps survived. The average follow-up period was 2 years and 6 months. The aesthetic and functional results were both satisfactory. The swallowing and speech function were almost normal. The flap sensation was partially restored. Good functional hemitongue reconstruction can be achieved with free forearm flaps.

  2. A Survey of Theoretical and Experimental Coaxial Rotor Aerodynamic Research

    Science.gov (United States)

    Coleman, Colin P.

    1997-01-01

    The recent appearance of the Kamov Ka-50 helicopter and the application of coaxial rotors to unmanned aerial vehicles have renewed international interest in the coaxial rotor configuration. This report addresses the aerodynamic issues peculiar to coaxial rotors by surveying American, Russian, Japanese, British, and German research. (Herein, 'coaxial rotors' refers to helicopter, not propeller, rotors. The intermeshing rotor system was not investigated.) Issues addressed are separation distance, load sharing between rotors, wake structure, solidity effects, swirl recovery, and the effects of having no tail rotor. A general summary of the coaxial rotor configuration explores the configuration's advantages and applications.

  3. Internal Mammary Artery Perforator flap

    NARCIS (Netherlands)

    Schellekens, P.P.A.

    2012-01-01

    Reconstructive surgery evolved as a result of the enormous numbers of World War I and II victims, long before profound knowledge of the vascularity of flaps was present. Sophisticated imaging techniques have given us at present a thorough understanding of the vascularity of tissues so that randomly

  4. Sternocleidomastoid Muscle Flap after Parotidectomy.

    Science.gov (United States)

    Nofal, Ahmad Abdel-Fattah; Mohamed, Morsi

    2015-10-01

    Introduction Most patients after either superficial or total parotidectomy develop facial deformity and Frey syndrome, which leads to a significant degree of patient dissatisfaction. Objective Assess the functional outcome and esthetic results of the superiorly based sternocleidomastoid muscle (SCM) flap after superficial or total parotidectomy. Methods A prospective cohort study for 11 patients subjected to parotidectomy using a partial-thickness superiorly based SCM flap. The functional outcome (Frey syndrome, facial nerve involvement, and ear lobule sensation) and the esthetic results were evaluated subjectively and objectively. Results Facial nerve palsy occurred in 5 cases (45%), and all of them recovered completely within 6 months. The Minor starch iodine test was positive in 3 patients (27%), although only 1 (9%) subjectively complained of gustatory sweating. The designed visual analog score completed by the patients themselves ranged from 0 to 3 with a mean of 1.55 ± 0.93; the scores from the blinded evaluators ranged from 1 to 3 with a mean 1.64 ± 0.67. Conclusion The partial-thickness superiorly based SCM flap offers a reasonable cosmetic option for reconstruction following either superficial or total parotidectomy by improving the facial deformity. The flap also lowers the incidence of Frey syndrome objectively and subjectively with no reported hazard of the spinal accessory nerve.

  5. Sternocleidomastoid Muscle Flap after Parotidectomy

    Directory of Open Access Journals (Sweden)

    Nofal, Ahmad Abdel-Fattah

    2015-04-01

    Full Text Available Introduction Most patients after either superficial or total parotidectomy develop facial deformity and Frey syndrome, which leads to a significant degree of patient dissatisfaction. Objective Assess the functional outcome and esthetic results of the superiorly based sternocleidomastoid muscle (SCM flap after superficial or total parotidectomy. Methods A prospective cohort study for 11 patients subjected to parotidectomy using a partial-thickness superiorly based SCM flap. The functional outcome (Frey syndrome, facial nerve involvement, and ear lobule sensation and the esthetic results were evaluated subjectively and objectively. Results Facial nerve palsy occurred in 5 cases (45%, and all of them recovered completely within 6 months. The Minor starch iodine test was positive in 3 patients (27%, although only 1 (9% subjectively complained of gustatory sweating. The designed visual analog score completed by the patients themselves ranged from 0 to 3 with a mean of 1.55 ± 0.93; the scores from the blinded evaluators ranged from 1 to 3 with a mean 1.64 ± 0.67. Conclusion The partial-thickness superiorly based SCM flap offers a reasonable cosmetic option for reconstruction following either superficial or total parotidectomy by improving the facial deformity. The flap also lowers the incidence of Frey syndrome objectively and subjectively with no reported hazard of the spinal accessory nerve.

  6. The freestyle pedicle perforator flap

    DEFF Research Database (Denmark)

    Gunnarsson, Gudjon Leifur; Jackson, Ian T; Westvik, Tormod S;

    2015-01-01

    not widely performed by the general plastic surgeons. The aim of this paper is to present the simplicity of pedicled perforator flap reconstruction of moderate-sized defects of the extremities and torso. METHODS: We retrospectively reviewed the charts of 34 patients reconstructed using 34 freestyle pedicled...

  7. Robust design of multiple trailing edge flaps for helicopter vibration reduction: A multi-objective bat algorithm approach

    Science.gov (United States)

    Mallick, Rajnish; Ganguli, Ranjan; Seetharama Bhat, M.

    2015-09-01

    The objective of this study is to determine an optimal trailing edge flap configuration and flap location to achieve minimum hub vibration levels and flap actuation power simultaneously. An aeroelastic analysis of a soft in-plane four-bladed rotor is performed in conjunction with optimal control. A second-order polynomial response surface based on an orthogonal array (OA) with 3-level design describes both the objectives adequately. Two new orthogonal arrays called MGB2P-OA and MGB4P-OA are proposed to generate nonlinear response surfaces with all interaction terms for two and four parameters, respectively. A multi-objective bat algorithm (MOBA) approach is used to obtain the optimal design point for the mutually conflicting objectives. MOBA is a recently developed nature-inspired metaheuristic optimization algorithm that is based on the echolocation behaviour of bats. It is found that MOBA inspired Pareto optimal trailing edge flap design reduces vibration levels by 73% and flap actuation power by 27% in comparison with the baseline design.

  8. The possibility for use of venous flaps in plastic surgery

    Energy Technology Data Exchange (ETDEWEB)

    Baytinger, V. F., E-mail: baitinger@mail.tomsknet.ru; Kurochkina, O. S., E-mail: kurochkinaos@yandex.ru; Selianinov, K. V.; Baytinger, A. V. [Research Institute of Microsurgery, Tomsk (Russian Federation); Dzyuman, A. N. [Siberian State Medical University, Tomsk (Russian Federation)

    2015-11-17

    The use of venous flaps is controversial. The mechanism of perfusion of venous flaps is still not fully understood. The research was conducted on 56 white rats. In our experimental work we studied two different models of venous flaps: pedicled venous flap (PVF) and pedicled arterialized venous flap (PAVF). Our results showed that postoperative congestion was present in all flaps. However 66.7% of all pedicled venous flaps and 100% of all pedicled arterialized venous flaps eventually survived. Histological examination revealed that postoperatively the blood flow in the skin of the pedicled arterialized venous flap became «re-reversed» again; there were no differences between mechanism of survival of venous flaps and other flaps. On the 7-14th day in the skin of all flaps were processes of neoangiogenesis and proliferation. Hence the best scenario for the clinical use of venous flaps unfolds when both revascularization and skin coverage are required.

  9. The possibility for use of venous flaps in plastic surgery

    Science.gov (United States)

    Baytinger, V. F.; Kurochkina, O. S.; Selianinov, K. V.; Baytinger, A. V.; Dzyuman, A. N.

    2015-11-01

    The use of venous flaps is controversial. The mechanism of perfusion of venous flaps is still not fully understood. The research was conducted on 56 white rats. In our experimental work we studied two different models of venous flaps: pedicled venous flap (PVF) and pedicled arterialized venous flap (PAVF). Our results showed that postoperative congestion was present in all flaps. However 66.7% of all pedicled venous flaps and 100% of all pedicled arterialized venous flaps eventually survived. Histological examination revealed that postoperatively the blood flow in the skin of the pedicled arterialized venous flap became «re-reversed» again; there were no differences between mechanism of survival of venous flaps and other flaps. On the 7-14th day in the skin of all flaps were processes of neoangiogenesis and proliferation. Hence the best scenario for the clinical use of venous flaps unfolds when both revascularization and skin coverage are required.

  10. Attitude Control of Small Quad-rotor Based on Active Disturbance Rejection Control Theory%基于自抗扰理论的小型四旋翼飞行器姿态控制

    Institute of Scientific and Technical Information of China (English)

    张广昱; 袁昌盛

    2014-01-01

    To solve the attitude control problem of small quad-rotor according to its complex coupling ,non-linear and serious internal/external disturbance feature ,a control scheme based on active disturbance rejection control technique is proposed .The dynamic model is established with Newton-Euler equations ,and the uncertainty , coupling and parameter perturbation are considered as total disturbance .Extended state observer is used to esti-mate and compensate the total disturbance .The non-linear state error feedback is used to restrain the compen-sate error ,and did simulation experiment of attitude control for small quad-rotor .The result of the simulation shows that the extended state observer of the active disturbance rejection control technique can estimate/com-pensate disturbance well under circumstance of parameter perturbation and disturbance .The attitude controller based on active disturbance rejection control theory shows good dynamic quality ,steady-state accuracy and strong robustness .%针对四旋翼飞行器的强耦合性、非线性、易受外界干扰等控制难点,研究利用自抗扰控制器对四旋翼飞行器进行姿态控制的技术问题。通过牛顿-欧拉方程建立四旋翼飞行器动力学模型,将不确定性、耦合及参数摄动等干扰作为“总和干扰”,利用扩张状态观测器进行估计并动态反馈补偿,再利用非线性反馈抑制补偿残差,进行四旋翼飞行器姿态控制仿真实验。结果表明:在存在模型参数摄动和外界扰动的情况下,扩张状态观测器很好地实时估计和补偿了四旋翼飞行器的总和干扰,基于自抗扰的四旋翼飞行器姿态控制系统具有较好的动态品质、稳态精度以及较强的鲁棒性。

  11. On Cup Anemometer Rotor Aerodynamics

    Directory of Open Access Journals (Sweden)

    Santiago Pindado

    2012-05-01

    Full Text Available The influence of anemometer rotor shape parameters, such as the cups’ front area or their center rotation radius on the anemometer’s performance was analyzed. This analysis was based on calibrations performed on two different anemometers (one based on magnet system output signal, and the other one based on an opto-electronic system output signal, tested with 21 different rotors. The results were compared to the ones resulting from classical analytical models. The results clearly showed a linear dependency of both calibration constants, the slope and the offset, on the cups’ center rotation radius, the influence of the front area of the cups also being observed. The analytical model of Kondo et al. was proved to be accurate if it is based on precise data related to the aerodynamic behavior of a rotor’s cup.

  12. User`s Guide for the NREL Teetering Rotor Analysis Program (STRAP)

    Energy Technology Data Exchange (ETDEWEB)

    Wright, A D

    1992-08-01

    The following report gives the reader an overview of instructions on the proper use of the National Renewable Energy Laboratory (formerly the Solar Energy Research Institute, or SERI) teetering Rotor Analysis Program (STRAP version 2.20). STRAP is a derivative of the Force and Loads Analysis program (FLAP). It is intended as a tool for prediction of rotor and blade loads and response for only two-bladed teetering hub wind turbines. The effects of delta-3, undersling, hub mass, and wind turbulence are accounted for. The objectives of the report are to give an overview of the code and also show the methods of data input and correct code execution steps in order to model an example two-bladed teetering hub turbine. A large portion of the discussion (Sections 6.0, 7.0, and 8.0) is devoted to the subject of inputting and running the code for wind turbulence effects. The ability to include turbulent wind effects is perhaps the biggest change in the code since the release of FLAP version 2.01 in 1988. This report is intended to be a user`s guide. It does not contain a theoretical discussion on equations of motion, assumptions, underlying theory, etc. It is intended to be used in conjunction with Wright, Buhl, and Thresher (1988).

  13. Design of plywood and paper flywheel rotors

    Science.gov (United States)

    Hagen, D. L.

    Technical and economic design factors of cellulosic rotors are compared with conventional materials for stationary flywheel energy storage systems. Wood species, operation in a vacuum, assembly and costs of plywood rotors are evaluated. Wound kraft paper, twine and veneer rotors are examined. Two bulb attachments are designed. Support stiffness is shown to be constrained by the material strength, rotor configuration and speed ratio. Plywood moisture equilibrium during manufacture and assembly is critical. Disk shaping and rotor assembly are described. Potential self-centering dynamic balancing methods and equipment are described. Detailed measurements of the distribution of strengths, densities and specific energy of conventional Finnish Birch plywood and of custom made hexagonal Birch plywood are detailed. High resolution tensile tests were performed while monitoring the acoustic emissions with micoprocessor controlled data acquisition. Preliminary duration of load tests were performed on vacuum dried hexagonal birch plywood. Economics of cellulosic and conventional rotors were examined.

  14. Forward flight of swallowtail butterfly with simple flapping motion.

    Science.gov (United States)

    Tanaka, Hiroto; Shimoyama, Isao

    2010-06-01

    Unlike other flying insects, the wing motion of swallowtail butterflies is basically limited to flapping because their fore wings partly overlap their hind wings, structurally restricting the feathering needed for active control of aerodynamic force. Hence, it can be hypothesized that the flight of swallowtail butterflies is realized with simple flapping, requiring little feedback control of the feathering angle. To verify this hypothesis, we fabricated an artificial butterfly mimicking the wing motion and wing shape of a swallowtail butterfly and analyzed its flights using images taken with a high-speed video camera. The results demonstrated that stable forward flight could be realized without active feathering or feedback control of the wing motion. During the flights, the artificial butterfly's body moved up and down passively in synchronization with the flapping, and the artificial butterfly followed an undulating flight trajectory like an actual swallowtail butterfly. Without feedback control of the wing motion, the body movement is directly affected by change of aerodynamic force due to the wing deformation; the degree of deformation was determined by the wing venation. Unlike a veinless wing, a mimic wing with veins generated a much higher lift coefficient during the flapping flight than in a steady flow due to the large body motion.

  15. Forward flight of swallowtail butterfly with simple flapping motion

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, Hiroto [School of Engineering and Applied Sciences, Harvard University, 60 Oxford Street, Cambridge, MA 02138 (United States); Shimoyama, Isao, E-mail: isao@i.u-tokyo.ac.j [Department of Mechano-Informatics, Graduate School of Information Science and Technology, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656 (Japan)

    2010-06-15

    Unlike other flying insects, the wing motion of swallowtail butterflies is basically limited to flapping because their fore wings partly overlap their hind wings, structurally restricting the feathering needed for active control of aerodynamic force. Hence, it can be hypothesized that the flight of swallowtail butterflies is realized with simple flapping, requiring little feedback control of the feathering angle. To verify this hypothesis, we fabricated an artificial butterfly mimicking the wing motion and wing shape of a swallowtail butterfly and analyzed its flights using images taken with a high-speed video camera. The results demonstrated that stable forward flight could be realized without active feathering or feedback control of the wing motion. During the flights, the artificial butterfly's body moved up and down passively in synchronization with the flapping, and the artificial butterfly followed an undulating flight trajectory like an actual swallowtail butterfly. Without feedback control of the wing motion, the body movement is directly affected by change of aerodynamic force due to the wing deformation; the degree of deformation was determined by the wing venation. Unlike a veinless wing, a mimic wing with veins generated a much higher lift coefficient during the flapping flight than in a steady flow due to the large body motion.

  16. Flywheel Rotor Safe-Life Technology

    Science.gov (United States)

    Ratner, J. K. H.; Chang, J. B.; Christopher, D. A.; McLallin, Kerry L. (Technical Monitor)

    2002-01-01

    Since the 1960s, research has been conducted into the use of flywheels as energy storage systems. The-proposed applications include energy storage for hybrid and electric automobiles, attitude control and energy storage for satellites, and uninterruptible power supplies for hospitals and computer centers. For many years, however, the use of flywheels for space applications was restricted by the total weight of a system employing a metal rotor. With recent technological advances in the manufacturing of composite materials, however, lightweight composite rotors have begun to be proposed for such applications. Flywheels with composite rotors provide much higher power and energy storage capabilities than conventional chemical batteries. However, the failure of a high speed flywheel rotor could be a catastrophic event. For this reason, flywheel rotors are classified by the NASA Fracture Control Requirements Standard as fracture critical parts. Currently, there is no industry standard to certify a composite rotor for safe and reliable operation forth( required lifetime of the flywheel. Technical problems hindering the development of this standard include composite manufacturing inconsistencies, insufficient nondestructive evaluation (NDE) techniques for detecting defects and/or impact damage, lack of standard material test methods for characterizing composite rotor design allowables, and no unified proof (over-spin) test for flight rotors. As part of a flywheel rotor safe-life certification pro-ram funded b the government, a review of the state of the art in composite rotors is in progress. The goal of the review is to provide a clear picture of composite flywheel rotor technologies. The literature review has concentrated on the following topics concerning composites and composite rotors: durability (fatigue) and damage tolerance (safe-life) analysis/test methods, in-service NDE and health monitoring techniques, spin test methods/ procedures, and containment options

  17. Optimization of wind turbine rotors

    Energy Technology Data Exchange (ETDEWEB)

    Nygaard, Tor Anders

    1999-07-01

    The Constrained Steepest Descent method has been applied to the optimization of wind turbine rotors through the development of a numerical model. The model consists of an optimization kernel, an aerodynamic model, a structural dynamic model of a rotating beam, and a cost model for the wind turbine. The cost of energy is minimized directly by varying the blade design, the rotational speed and the resulting design of the drive-train and tower. The aerodynamic model is a combination of a fast engineering model based on strip-theory and two and three-dimensional Euler solvers. The two-dimensional Euler solver is used for generation of pre-stall airfoil data. Comparisons with experimental data verify that the engineering model effectively approximates non-stalled flow, except at the blade tip. The three-dimensional Euler solver is in good agreement with the experimental data at the tip, and is therefore a useful supplement for corrections of the tip-loss model, and evaluation of an optimized design. The structural dynamic model evaluates stresses and deformations for the blade. It is based on constitutive relations for a slender beam that are solved with the equations of motions using a finite-difference method. The cost model evaluates the design change of the wind turbine and the resulting costs that occur when a change in blade design modifies the blade mass and the overall forces. The cost model is based on engineering design rules for the drive-train and tower. The model was applied using a Danish 600 kW wind turbine as a reference. Two rotors were optimized using traditional NACA airfoils and a new low-lift airfoil family developed specifically for wind turbine purposes. The cost of energy decreased four percent for the NACA rotor, and seven percent for the low-lift rotor. Optimizations with a high number of degrees of freedom show that a designer has considerable flexibility in choosing some primary parameters such as rated power and rotor diameter, if the rest

  18. Energy from Swastika-Shaped Rotors

    Directory of Open Access Journals (Sweden)

    McCulloch M. E.

    2015-04-01

    Full Text Available It is suggested here that a swastika-shaped rotor exposed to waves will rotate in the di- rection its arms are pointing (towards the arm-tips due to a sheltering effect. A formula is derived to predict the motion obtainable from swastika rotors of different sizes given the ocean wave height and phase speed and it is suggested that the rotor could provide a new, simpler method of wave energy generation. It is also proposed that the swastika rotor could generate energy on a smaller scale from sound waves and Brownian motion, and potentially the zero point field.

  19. Rotor thermal stress monitoring in steam turbines

    Science.gov (United States)

    Antonín, Bouberle; Jan, Jakl; Jindřich, Liška

    2015-11-01

    One of the issues of steam turbines diagnostics is monitoring of rotor thermal stress that arises from nonuniform temperature field. The effort of steam turbine operator is to operate steam turbine in such conditions, that rotor thermal stress doesn't exceed the specified limits. If rotor thermal stress limits are exceeded for a long time during machine operation, the rotor fatigue life is shortened and this may lead to unexpected machine failure. Thermal stress plays important role during turbine cold startup, when occur the most significant differences of temperatures through rotor cross section. The temperature field can't be measured directly in the entire rotor cross section and standardly the temperature is measured by thermocouple mounted in stator part. From this reason method for numerical solution of partial differential equation of heat propagation through rotor cross section must be combined with method for calculation of temperature on rotor surface. In the first part of this article, the application of finite volume method for calculation of rotor thermal stress is described. The second part of article deals with optimal trend generation of thermal flux, that could be used for optimal machine loading.

  20. Helicopter Rotor Blade Monitoring using Autonomous Wireless Sensor Network

    NARCIS (Netherlands)

    Sanchez Ramirez, Andrea; Loendersloot, Richard; Tinga, Tiedo; Basu, B.

    2013-01-01

    The advancement on Wireless Sensor Networks for vibration monitoring presents important possibilities for helicopter rotor health and usage monitoring. While main rotor blades account for the main source of lift for helicopters, rotor induced vibration establishes an important source for

  1. Adjoint-based optimization of flapping plates hinged with a trailing-edge flap

    Directory of Open Access Journals (Sweden)

    Min Xu

    2015-01-01

    Full Text Available It is important to understand the impact of wing-morphing on aerodynamic performance in the study of flapping-wing flight of birds and insects. We use a flapping plate hinged with a trailing-edge flap as a simplified model for flexible/morphing wings in hovering. The trailing-edge flapping motion is optimized by an adjoint-based approach. The optimized configuration suggests that the trailing-edge flap can substantially enhance the overall lift. Further analysis indicates that the lift enhancement by the trailing-edge flapping is from the change of circulation in two ways: the local circulation change by the rotational motion of the flap, and the modification of vortex shedding process by the relative location between the trailing-edge flap and leading-edge main plate.

  2. Reverse flow first dorsal metacarpal artery flap for covering the defect of distal thumb.

    Science.gov (United States)

    Checcucci, Giuseppe; Galeano, Mariarosaria; Zucchini, Maura; Zampetti, Pier Giuseppe; Ceruso, Massimo

    2014-05-01

    Reconstruction of distal thumb injuries still remains a challenge for hand surgeons. Surgical treatment includes the use of local, regional, and free flaps. The purpose of this report is to present the results of the use of a sensitive reverse flow first dorsal metacarpal artery (FDMA) flap. The skin flap was designed on the radial side of the proximal phalanx of the index finger based on the ulnar and radial branch of the FDMA and a sensory branch of the superficial radial nerve. This neurovascular flap was used in five patients to cover distal soft-tissue thumb defects. All flaps achieved primary healing except for one patient in whom superficial partial necrosis of the flap occurred, and the defect healed by second intention. All patients maintained the thumb original length and were able to return to their previous daily activities. The reverse flow FDMA flap is a reliable option to cover immediate and delayed defects of distal thumb, offering acceptable functional and cosmetic outcomes in respect to sensibility, durability, and skin-match.

  3. The place of nasolabial flap in orofacial reconstruction: A review

    Directory of Open Access Journals (Sweden)

    Amin Rahpeyma

    2016-12-01

    Conclusion: Nasolabial flap is an old flap for reconstructive purposes. Over time different modifications have been introduced to expand its usage. Clear definition of the terms used with this flap is given.

  4. Freestyle Local Perforator Flaps for Facial Reconstruction

    Directory of Open Access Journals (Sweden)

    Jun Yong Lee

    2015-01-01

    Full Text Available For the successful reconstruction of facial defects, various perforator flaps have been used in single-stage surgery, where tissues are moved to adjacent defect sites. Our group successfully performed perforator flap surgery on 17 patients with small to moderate facial defects that affected the functional and aesthetic features of their faces. Of four complicated cases, three developed venous congestion, which resolved in the subacute postoperative period, and one patient with partial necrosis underwent minor revision. We reviewed the literature on freestyle perforator flaps for facial defect reconstruction and focused on English articles published in the last five years. With the advance of knowledge regarding the vascular anatomy of pedicled perforator flaps in the face, we found that some perforator flaps can improve functional and aesthetic reconstruction for the facial defects. We suggest that freestyle facial perforator flaps can serve as alternative, safe, and versatile treatment modalities for covering small to moderate facial defects.

  5. Dermatosurgery Rounds - The Island SKIN Infraorbital Flap

    Directory of Open Access Journals (Sweden)

    Georgi Tchernev

    2017-07-01

    Full Text Available The main objective in dermatologic surgery is complete excision of the tumour while achieving the best possible functional and cosmetic outcome. Also we must take into account age, sex, and tumour size and site. We should also consider the patient's expectations, the preservation of the different cosmetic units, and the final cosmetic outcome. Various reconstructive methods ranging from secondary healing to free flap applications are usedfor the reconstruction of perinasal or facial defects caused by trauma or tumour surgery. Herein, we describe the nasal infraorbital island skin flap for the reconstruction in a patient with basal cell carcinoma. No complications were observed in operation field. The infraorbital island skin flap which we describe for the perinasal area reconstruction is a safe, easily performed and versatile flap. The multidimensional use of this flap together with a relatively easy reconstruction plan and surgical procedure would be effective in flap choice.

  6. Freestyle Local Perforator Flaps for Facial Reconstruction.

    Science.gov (United States)

    Lee, Jun Yong; Kim, Ji Min; Kwon, Ho; Jung, Sung-No; Shim, Hyung Sup; Kim, Sang Wha

    2015-01-01

    For the successful reconstruction of facial defects, various perforator flaps have been used in single-stage surgery, where tissues are moved to adjacent defect sites. Our group successfully performed perforator flap surgery on 17 patients with small to moderate facial defects that affected the functional and aesthetic features of their faces. Of four complicated cases, three developed venous congestion, which resolved in the subacute postoperative period, and one patient with partial necrosis underwent minor revision. We reviewed the literature on freestyle perforator flaps for facial defect reconstruction and focused on English articles published in the last five years. With the advance of knowledge regarding the vascular anatomy of pedicled perforator flaps in the face, we found that some perforator flaps can improve functional and aesthetic reconstruction for the facial defects. We suggest that freestyle facial perforator flaps can serve as alternative, safe, and versatile treatment modalities for covering small to moderate facial defects.

  7. Free flaps for pressure sore coverage.

    Science.gov (United States)

    Lemaire, Vincent; Boulanger, Kevin; Heymans, Oliver

    2008-06-01

    Management of pressure sores still represents a major challenge in plastic surgery practice due to recurrence. The surgeon may have to face multiple or recurrent pressure ulcerations without any local flap left. In this very limited indication, free flap surgery appears to be a useful adjunct in the surgical treatment. We reviewed our charts looking for patients operated for a pressure sore of the sacral, ischial, or trochanteric region. We found 88 consecutive patients representing 108 different pressure sores and 141 flap procedures. Among these patients, 6 presented large sores that could not be covered with a pedicled flap and benefited from free flap surgery (4.2% of all procedures). Stable coverage was achieved in 80% of these patients after a mean follow-up of 32 months. Comparison between pedicled and free flaps groups showed a trend in the latest concerning the presence of diabetes, incontinence, paraplegia, and male sex.

  8. Elastic multiple-mass model for rotordynamic analysis of flexible electrical rotors

    Energy Technology Data Exchange (ETDEWEB)

    Werner, U. [Siemens AG, Nuernberg (Germany). Industry, Drive Technologies, Large Drives, Products R and D

    2011-12-15

    The paper presents an elastic multiple-mass model for rotordynamic analysis of flexible electrical rotors supported in sleeve bearings, considering mechanical unbalances and electromagnetic forces. This model has been especially developed for flexible electrical rotors, which operate near below or near above the first critical bending speed of the rotor. Using this simplified model, a static rotor active part eccentricity can be simulated and the orbital movement of the rotor can be calculated. Additionally, the influence of different balancing concepts - elastic balancing versus rigid balancing - on the shaft vibrations is analyzed. To verify the model, a finite element analysis was performed, which indicates a satisfactory match. On the one hand, the aim of the paper is to derive an elastic multiple-mass model for rotordynamic analysis of flexible electrical rotors for special boundary conditions. On the other hand, the aim is to show the mathematical coherences - based on a simplified model - between the rotordynamics, the oil film characteristics of the sleeve bearings, the elasticity of the rotor structure, the electromagnetics and the balancing concept. (orig.)

  9. Head and neck reconstruction with pedicled flaps in the free flap era

    NARCIS (Netherlands)

    Mahieu, R.; Colletti, G.; Bonomo, P.; Parrinello, G.; Iavarone, A.; Dolivet, G.; Livi, L.; Deganello, A.

    2016-01-01

    Nowadays, the transposition of microvascular free flaps is the most popular method for management of head and neck defects. However, not all patients are suitable candidates for free flap reconstruction. In addition, not every defect requires a free flap transfer to achieve good functional results.

  10. Resternal closure versus pectoral muscle flap following omental flap in treatment of deep sternal wound infection

    Directory of Open Access Journals (Sweden)

    Fouad Rassekh

    2016-05-01

    Conclusion: Omental flap is safe, easy and effective technique in management of mediastinitis with DSWI following open heart surgery in CABG patients either this procedure was followed by reclosure of the sternum or bilateral pectoral flap. However, reclosure of the sternum is more physiological and less invasive than doing bilateral pectoral flap leaving the sternum unclosed.

  11. Pectoralis major flap for head and neck reconstruction in era of free flaps.

    Science.gov (United States)

    Kekatpure, V D; Trivedi, N P; Manjula, B V; Mathan Mohan, A; Shetkar, G; Kuriakose, M A

    2012-04-01

    The aim of this study was to evaluate factors affecting the selection of pectoralis major flap in the era of free tissue reconstruction for post ablative head and neck defects and flap associated complications. The records of patients who underwent various reconstructive procedures between July 2009 and December 2010 were retrospectively analysed. 147 reconstructive procedures including 79 free flaps and 58 pectoralis major flaps were performed. Pectoralis major flap was selected for reconstruction in 21 patients (36%) due to resource constrains, in 12 (20%) patients for associated medical comorbidities, in 11 (19%) undergoing extended/salvage neck dissections, and in 5 patients with vessel depleted neck and free flap failure salvage surgery. None of the flaps was lost, 41% of patients had flap related complications. Most complications were self-limiting and were managed conservatively. Data from this study suggest that pectoralis major flap is a reliable option for head and neck reconstruction and has a major role even in this era of free flaps. The selection of pectoralis major flap over free flap was influenced by patient factors in most cases. Resource constraints remain a major deciding factor in a developing country setting.

  12. Posterior interosseous free flap: various types.

    Science.gov (United States)

    Park, J J; Kim, J S; Chung, J I

    1997-10-01

    The posterior interosseous artery is located in the intermuscular septum between the extensor carpi ulnaris and extensor digiti minimi muscles. The posterior interosseous artery is anatomically united through two main anastomoses: one proximal (at the level of the distal border of the supinator muscle) and one distal (at the most distal part of the interosseous space). In the distal part, the posterior interosseous artery joins the anterior interosseous artery to form the distal anastomosis between them. The posterior interosseous flap can be widely used as a reverse flow island flap because it is perfused by anastomoses between the anterior and the posterior interosseous arteries at the level of the wrist. The flap is not reliable whenever there is injury to the distal forearm or the wrist. To circumvent this limitation and to increase the versatility of this flap, we have refined its use as a direct flow free flap. The three types of free flaps used were (1) fasciocutaneous, (2) fasciocutaneous-fascia, and (3) fascia only. Described are 23 posterior interosseous free flaps: 13 fasciocutaneous flaps, 6 fasciocutaneous-fascial flaps, and 4 fascial flaps. There were 13 sensory flaps using the posterior antebrachial cutaneous nerve. The length and external diameter of the pedicle were measured in 35 cases. The length of the pedicle was on average 3.5 cm (range, 3.0 to 4.0 cm) and the external diameter of the artery averaged 2.2 mm (range, 2.0 to 2.5 mm). The hand was the recipient in 21 patients, and the foot in 2. All 23 flaps covered the defect successfully.

  13. Free flap pulse oximetry utilizing reflectance photoplethysmography

    OpenAIRE

    Zaman, T.; Kyriacou, P. A.; Pal, S.

    2013-01-01

    The successful salvage of a free flap is dependent on the continuous monitoring of perfusion. To date there is no widely accepted and readily available post-operative monitoring technique to reliably assess the viability of free flaps by continuously monitoring free flap blood oxygen saturation. In an attempt to overcome the limitations of the current techniques a reflectance photoplethysmographic (PPG) processing system has been developed with the capability of real-time estimation of arteri...

  14. Results of the AVATAR project for the validation of 2D aerodynamic models with experimental data of the DU95W180 airfoil with unsteady flap

    DEFF Research Database (Denmark)

    Ferreira, C.; Gonzalez, A.; Baldacchino, D.;

    2016-01-01

    The FP7 AdVanced Aerodynamic Tools for lArge Rotors - Avatar project aims to develop and validate advanced aerodynamic models, to be used in integral design codes for the next generation of large scale wind turbines (10-20MW). One of the approaches towards reaching rotors for 10-20MW size...... is the application of flow control devices, such as flaps. In Task 3.2: Development of aerodynamic codes for modelling of flow devices on aerofoils and, rotors of the Avatar project, aerodynamic codes are benchmarked and validated against the experimental data of a DU95W180 airfoil in steady and unsteady flow......, for different angle of attack and flap settings, including unsteady oscillatory trailing-edge-flap motion, carried out within the framework of WP3: Models for Flow Devices and Flow Control, Task 3.1: CFD and Experimental Database. The aerodynamics codes are: AdaptFoil2D, Foil2W, FLOWer, MaPFlow, OpenFOAM, Q3UIC...

  15. Four Flaps Technique for Neoumbilicoplasty

    Directory of Open Access Journals (Sweden)

    Young Taek Lee

    2015-05-01

    Full Text Available The absence or disfigurement of the umbilicus is both cosmetically and psychologically distressing to patients. The goal of aesthetically pleasing umbilical reconstruction is to create a neoumbilicus with sufficient depth and good morphology, with natural-looking superior hooding and minimal scarring. Although many reports have presented techniques for creating new and attractive umbilici, we developed a technique that we term the "four flaps technique" for creating a neoumbilicus in circumstances such as the congenital absence of the umbilicus or the lack of remaining umbilical tissue following the excision of a hypertrophic or scarred umbilicus. This method uses the neighboring tissue by simply elevating four flaps and can yield sufficient depth and an aesthetically pleasing shape with appropriate superior hooding.

  16. Dynamic stall in flapping flight

    Science.gov (United States)

    Hubel, Tatjana; Tropea, Cameron

    2007-11-01

    We report on experiments concerning unsteady effects in flapping flight, conducted in the low-speed wind tunnel of the TU Darmstadt using a mechanical flapping-wing model. Particle Image Velocimetry (PIV) was used for qualitative and quantitative analysis parallel and perpendicular to the flow field. A sensitivity analysis of the main flight parameters has been performed, with specific attention to the flight envelope of 26,500 dynamic stall effect could be verified by the direct force measurement as well as the flow visualization. The observation of the leading-edge vortex for typical bird flight reduced frequencies shows that this flow cannot be approximated as being quasi- steady. This in effect proves that adaptive wings are necessary to fully control these unsteady flow features, such as dynamic stall.

  17. 基于DSP的微型直升机主动旋翼控制系统硬件设计%Hardware Design of Mini-helicopter Rotor Active Control System Based on DSP

    Institute of Scientific and Technical Information of China (English)

    刘宏; 罗华; 杨淑凤

    2012-01-01

    针对共轴双桨直升机主动旋翼控制的工作原理及其硬件设计方案进行了介绍.该系统主要由三轴加速度计ADXL345和三轴陀螺L3G4200D及TMS320F28335 DSP组成捷联惯导系统.并在捷联惯导姿态控制中增加了旋翼受力反馈环路,提高了惯导对外界扰动的响应速度.通过实验验证,该系统对于提高悬停稳定性和高度控制响应速度具有较好的效果.%The sculls coaxial helicopter active control of the working principle and hardware design solutions were introduced.The system consists of three-axis accelerometer ADXL345 three-axis gyro and L3G4200D and TMS320F28335 DSP components.And attitude control in strap down inertial navigation system(SINS) was added to rotor force feedback loop to improve the response to external disturbances.Experiments show that the system with good results to the hover stability and response speed of height control.

  18. Performance tests of a Benesh wind turbine rotor and a Savonius rotor

    Energy Technology Data Exchange (ETDEWEB)

    Moutsoglou, A.; Yan Weng [South Dakota State Univ., Brookings, SD (United States). Dept. of Mechanical Engineering

    1995-12-31

    A study was conducted to compare the performance of a Benesh rotor against a Savonius rotor as a wind power generating device. Rotors of similar dimensions were tested at the exit of a 1.22 m x 0.91 wind tunnel, at two different shaft heights above the ground. In all the tests, the maximum power coefficient for the Benesh rotor was considerably greater than for the Savonius and occurred at a lower tip speed ratio. The Benesh rotor also displayed better starting characteristics throughout. Finally, the present data compared very favourably with the experimental data of Backwell et al. (Author)

  19. Flapping Wing Flight Dynamic Modeling

    Science.gov (United States)

    2011-08-22

    von Karman, T. and Burgers, J. M., Gerneral Aerodynamic Theory - Perfect Fluids , Vol. II, Julius Springer , Berlin, 1935. [24] Pesavento, U. and Wang...L., Methods of Analytical Dynamics , McGraw-Hill Book Company, New York, 1970. [34] Deng, X., Schenato, L., Wu, W. C., and Sastry, S. S., Flapping...Micro air vehicle- motivated computational biomechanics in bio ights: aerodynamics, ight dynamics and maneuvering stability, Acta Mechanica

  20. Optimal propulsive flapping in Stokes flows

    CERN Document Server

    Was, Loic

    2014-01-01

    Swimming fish and flying insects use the flapping of fins and wings to generate thrust. In contrast, microscopic organisms typically deform their appendages in a wavelike fashion. Since a flapping motion with two degrees of freedom is able, in theory, to produce net forces from a time-periodic actuation at all Reynolds number, we compute in this paper the optimal flapping kinematics of a rigid spheroid in a Stokes flow. The hydrodynamics for the force generation and energetics of the flapping motion is solved exactly. We then compute analytically the gradient of a flapping efficiency in the space of all flapping gaits and employ it to derive numerically the optimal flapping kinematics as a function of the shape of the flapper and the amplitude of the motion. The kinematics of optimal flapping are observed to depend weakly on the flapper shape and are very similar to the figure-eight motion observed in the motion of insect wings. Our results suggest that flapping could be a exploited experimentally as a propul...

  1. Microsurgical free flaps at Kathmandu Model Hospital.

    Science.gov (United States)

    Rai, S M; Grinsell, D; Hunter-Smith, D; Corlett, R; Nakarmi, K; Basnet, S J; Shakya, P; Nagarkoti, K; Ghartimagar, M; Karki, B

    2014-01-01

    Microsurgery is an emerging subspecialty in Nepal. Microsurgery was started at Kathmandu Model Hospital in 2007 with the support from Interplast Australia and New Zealand. This study will be useful for establishing a baseline for future comparisons of outcome variables and for defining the challenges of performing microsurgical free flaps in Nepal. A retrospective cross sectional study was conducted using the clinical records of all the microsurgical free flaps performed at Kathmandu Model Hospital from April 2007 to April 2014. Fifty-six free flaps were performed. The commonest indication was neoplasm followed by post-burn contracture, infection and trauma. Radial artery forearm flap was the commonest flap followed by fibula, antero-lateral thigh, rectus, tensor facia lata, lattisimus dorsi, deep inferior epigastric artery perforator, and deep circumflex iliac artery flap. Radial artery forearm flaps and anterolateral thigh flaps were mostly used for burn contracture reconstructions. Twelve of the 13 (92%) fibulae were used for mandibular reconstruction for oral cancer and ameloblastoma. Rectus flaps were used mainly for covering defects over tibia. Hospital stay ranged from six to 67 days with an average of fourteen. Fifteen patients (26%) developed complications. The duration of operation ranged from six hours to 10.5 hours with an average of nine hours. The longest follow up was for four years. Microsurgery can be started even in very resource-poor center if there is support from advanced centers and if there is commitment of the institution and surgical team.

  2. Extended locoregional use of intercostal artery perforator propeller flaps.

    Science.gov (United States)

    Baghaki, Semih; Diyarbakirlioglu, Murat; Sahin, Ugur; Kucuksucu, Muge Anil; Turna, Akif; Baca, Bilgi; Aydın, Yağmur

    2017-05-01

    Besides conventional flaps, intercostal artery perforator flaps have been reported to cover trunk defects. In this report the use of anterior intercostal artery perforator (AICAP) flap, lateral intercostal artery perforator (LICAP) flap and dorsal intercostal artery perforator (DICAP) flap for thoracic, abdominal, cervical, lumbar and sacral defects with larger dimensions and extended indications beyond the reported literature were reevaluated. Thirty-nine patients underwent surgery between August 2012 and August 2014. The age of the patients ranged between 16 and 79 with a mean of 49 years. The distribution of defects were as follows; 12 thoracic, 8 parascapular, 3 cervical, 8 abdominal, 4 sacral and 4 lumbar. AICAP, LICAP and DICAP flaps were used for reconstruction. Fifty-two ICAP flaps were performed on 39 patients. Flap dimensions ranged between 6 × 9 cm and 14 × 35 cm. Twenty-six patients had single flap coverage and 13 patients had double flap coverage. Forty-six flaps have been transferred as propeller flaps and 6 flaps have been transferred as perforator plus flap. Forty flaps (75%) went through transient venous congestion. In one DICAP flap, 30% of flap was lost. No infection, hematoma or seroma were observed in any patient. Follow-up period ranged between 3 and 32 months with a mean of 9 months. The ICAP flaps provide reliable and versatile options in reconstructive surgery and can be used for challenging defects in trunk. © 2016 Wiley Periodicals, Inc.

  3. The isolated perfused human skin flap model: A missing link in skin penetration studies?

    OpenAIRE

    Ternullo, Selenia; de Weerd, Louis; Flaten, Gøril Eide; Holsæter, Ann Mari; Skalko-Basnet, Natasa

    2016-01-01

    Development of effective (trans)dermal drug delivery systems requires reliable skinmodels to evaluate skin drug penetration. The isolated perfused human skin flap remainsmetabolically active tissue for up to 6 h during in vitro perfusion. We introduce the isolated perfused human skin flap as a close-to-in vivo skin penetration model. To validate the model's ability to evaluate skin drug penetration the solutions of a hydrophilic (calcein) and a lipophilic (rhodamine) fluorescence ...

  4. Innovative multi rotor wind turbine designs

    Energy Technology Data Exchange (ETDEWEB)

    Kale, S.A.; Sapali, S.N. [College of Engineering. Mechanical Engineering Dept, Pune (India)

    2012-07-01

    Among the renewable energy sources, today wind energy is the most recognized and cost effective. Developers and researchers in this sector are optimistic and continuously working innovatively to improve the technology. The wind power obtained is proportional to the swept area of wind turbine. The swept area is increased by using a single rotor of large diameter or multi rotors in array. The rotor size is growing continuously with mature technology. Multi rotor technology has a long history and the multi rotor concept persists in a variety of modern innovative systems but the concept has fallen out of consideration in mainstream design from the perception that is complex and unnecessary as very large single rotor units are now technically feasible. This work addresses the evaluation of different multi rotor wind turbine systems. These innovative wind turbines are evaluated on the basis of feasibility, technological advantages, security of expected power performance, cost, reliability, impact of innovative system, comparison with existing wind turbine design. The findings of this work will provide guidelines for the practical and economical ways for further research on the multi rotor wind turbines. (Author)

  5. Rotor theories by Professor Joukowsky: Momentum theories

    DEFF Research Database (Denmark)

    van Kuik, G. A. M.; Sørensen, Jens Nørkær; Okulov, V. L.

    2015-01-01

    This paper is the first of two papers on the history of rotor aerodynamics with special emphasis on the role of Joukowsky. The present one focuses on the development of the momentum theory while the second one surveys the development of vortex theory for rotors. Joukowsky has played a major role ...

  6. Pneumatic boot for helicopter rotor deicing

    Science.gov (United States)

    Blaha, B. J.; Evanich, P. L.

    1981-01-01

    Pneumatic deicer boots for helicopter rotor blades were tested. The tests were conducted in the 6 by 9 ft icing research tunnel on a stationary section of a UH-IH helicopter main rotor blade. The boots were effective in removing ice and in reducing aerodynamic drag due to ice.

  7. Computational Analysis of Multi-Rotor Flows

    Science.gov (United States)

    Yoon, Seokkwan; Lee, Henry C.; Pulliam, Thomas H.

    2016-01-01

    Interactional aerodynamics of multi-rotor flows has been studied for a quadcopter representing a generic quad tilt-rotor aircraft in hover. The objective of the present study is to investigate the effects of the separation distances between rotors, and also fuselage and wings on the performance and efficiency of multirotor systems. Three-dimensional unsteady Navier-Stokes equations are solved using a spatially 5th order accurate scheme, dual-time stepping, and the Detached Eddy Simulation turbulence model. The results show that the separation distances as well as the wings have significant effects on the vertical forces of quadroror systems in hover. Understanding interactions in multi-rotor flows would help improve the design of next generation multi-rotor drones.

  8. Open Rotor - Analysis of Diagnostic Data

    Science.gov (United States)

    Envia, Edmane

    2011-01-01

    NASA is researching open rotor propulsion as part of its technology research and development plan for addressing the subsonic transport aircraft noise, emission and fuel burn goals. The low-speed wind tunnel test for investigating the aerodynamic and acoustic performance of a benchmark blade set at the approach and takeoff conditions has recently concluded. A high-speed wind tunnel diagnostic test campaign has begun to investigate the performance of this benchmark open rotor blade set at the cruise condition. Databases from both speed regimes will comprise a comprehensive collection of benchmark open rotor data for use in assessing/validating aerodynamic and noise prediction tools (component & system level) as well as providing insights into the physics of open rotors to help guide the development of quieter open rotors.

  9. Rotors stress analysis and design

    CERN Document Server

    Vullo, Vincenzo

    2013-01-01

    Stress and strain analysis of rotors subjected to surface and body loads, as well as to thermal loads deriving from temperature variation along the radius, constitutes a classic subject of machine design. Nevertheless attention is limited to rotor profiles for which governing equations are solvable in closed form. Furthermore very few actual engineering issues may relate to structures for which stress and strain analysis in the linear elastic field and, even more, under non-linear conditions (i.e. plastic or viscoelastic conditions) produces equations to be solved in closed form. Moreover, when a product is still in its design stage, an analytical formulation with closed-form solution is of course simpler and more versatile than numerical methods, and it allows to quickly define a general configuration, which may then be fine-tuned using such numerical methods. In this view, all subjects are based on analytical-methodological approach, and some new solutions in closed form are presented. The analytical formul...

  10. ATEFlap aerodynamic model, a dynamic stall model including the effects of trailing edge flap deflection

    Energy Technology Data Exchange (ETDEWEB)

    Bergami, L.; Gaunaa, M.

    2012-02-15

    The report presents the ATEFlap aerodynamic model, which computes the unsteady lift, drag and moment on a 2D airfoil section equipped with Adaptive Trailing Edge Flap. The model captures the unsteady response related to the effects of the vorticity shed into the wake, and the dynamics of flow separation a thin-airfoil potential flow model is merged with a dynamic stall model of the Beddoes-Leishmann type. The inputs required by the model are steady data for lift, drag, and moment coefficients as function of angle of attack and flap deflection. Further steady data used by the Beddoes- Leishmann dynamic stall model are computed in an external preprocessor application, which gives the user the possibility to verify, and eventually correct, the steady data passed to the aerodynamic model. The ATEFlap aerodynamic model is integrated in the aeroelastic simulation tool HAWC2, thus al- lowing to simulate the response of a wind turbine with trailing edge flaps on the rotor. The algorithms used by the preprocessor, and by aerodynamic model are presented, and modifications to previous implementations of the aerodynamic model are briefly discussed. The performance and the validity of the model are verified by comparing the dynamic response computed by the ATEFlap with solutions from CFD simulations. (Author)

  11. Rotor speed estimation for indirect stator flux oriented induction motor drive based on MRAS scheme

    Directory of Open Access Journals (Sweden)

    Youssef Agrebi

    2007-09-01

    Full Text Available In this paper, a conventional indirect stator flux oriented controlled (ISFOC induction motor drive is presented. In order to eliminate the speed sensor, an adaptation algorithm for tuning the rotor speed is proposed. Based on the model reference adaptive system (MRAS scheme, the rotor speed is tuned to obtain an exact ISFOC induction motor drive. The reference and adjustable models, developed in stationary stator reference frame, are used in the MRAS scheme to estimate induction rotor peed from measured terminal voltages and currents. The IP gains speed controller and PI gains current controller are calculated and tuned at each sampling time according to the new estimated rotor speed. The proposed algorithm has been tested by numerical simulation, showing the capability of driving active load; and stability is preserved. Experimental results obtained with a general-purpose 1-kW induction machine are presented showing the effectiveness of the proposed approach in terms of dynamic performance.

  12. STUDY ON CATASTROPHIC MECHANISM FOR ROTOR DROP TRANSIENT VIBRATION FOLLOWING MAGNETIC BEARING FAILURE

    Institute of Scientific and Technical Information of China (English)

    方之楚

    2002-01-01

    The nonlinear and transient vibration of a rotor, which dropped onto back-up bearings when its active magnetic bearings were out of order, was investigated. After strictly deriving its equations of motion and performing numerical simulations, the timehistories of rotating speed of the dropping rotor, and normal force at the rubbing contact point as well as the frequency spectrum of the vibration displacement of back-up bearings are fully analyzed. It is found that the strong and unsteady forced bending vibration of the unbalanced and damped rotor decelerating through its first bending vibtation of the unbalanced and damped rotor decelerating through its first critical speed as well as chattering at high frequencies caused by the nonlinearity at the rubbing contact point between the journal and back-up bearings may lead to the catastrophic damage of the system.

  13. Reconstruction of Complex Facial Defects Using Cervical Expanded Flap Prefabricated by Temporoparietal Fascia Flap.

    Science.gov (United States)

    Zhang, Ling; Yang, Qinghua; Jiang, Haiyue; Liu, Ge; Huang, Wanlu; Dong, Weiwei

    2015-09-01

    Reconstruction of complex facial defects using cervical expanded flap prefabricated by temporoparietal fascia flap. Complex facial defects are required to restore not only function but also aesthetic appearance, so it is vital challenge for plastic surgeons. Skin grafts and traditional flap transfer cannot meet the reconstructive requirements of color and texture with recipient. The purpose of this sturdy is to create an expanded prefabricated temporoparietal fascia flap to repair complex facial defects. Two patients suffered severe burns on the face underwent complex facial resurfacing with prefabricated cervical flap. The vasculature of prefabricated flap, including the superficial temporal vessel and surrounding fascia, was used as the vascular carrier. The temporoparietal fascia flap was sutured underneath the cervical subcutaneous tissue, and expansion was begun in postoperative 1 week. After 4 to 6 months of expansion, the expander was removed, facial scars were excised, and cervical prefabricated flap was elevated and transferred to repair the complex facial defects. Two complex facial defects were repaired successfully by prefabricated temporoparietal fascia flap, and prefabricated flaps survived completely. On account of donor site's skin was thinner and expanded too fast, 1 expanded skin flap was rupture during expansion, but necrosis was not occurred after the 2nd operation. Venous congestion was observed in 1 patient, but after dressing, flap necrosis was not happened. Donor site was closed primarily. Postoperative follow-up 6 months, the color, texture of prefabricated flap was well-matched with facial skin. This method of expanded prefabricated flap may provide a reliable solution to the complex facial resurfacing.

  14. Experimental modal tests applied to rotor balancing; Pruebas modales experimentales aplicadas al balanceo de rotores

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez Solis, Jose Antonio; Munoz Quezada, Rodolfo; Franco Nava, Jose Manuel [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

    1993-01-01

    At the Instituto de Investigaciones Electricas (IIE), the experimental modal tests were initiated in order to validate the numerical models used by computer programs for the study of the rotor dynamic behavior. In order to contribute to the application of the rotor balancing methods based in the calculation of their modal forms, currently the capacity to determine these modal forms and the natural frequencies of turbogenerator rotors, is being developed, through experimental modal tests. In this paper a short description is made of the technique and the results of its application in an experimental rotor and in one of the rotors of a turbogenerator, are presented. [Espanol] En el Instituto de Investigaciones Electricas (IIE), las pruebas modales experimentales se iniciaron con la finalidad de validar los modelos numericos empleados por programas de computo para el estudio del comportamiento dinamico de rotores. Con objeto de contribuir a la aplicacion de los metodos de balanceo de rotores basados en el calculo de sus formas modales, actualmente esta desarrollandose la capacidad para determinar esas formas modales y las frecuencias naturales de rotores de turbogeneradores, a traves de las pruebas modales experimentales. En este trabajo se describe brevemente la tecnica y se presentan los resultados de su aplicacion en un rotor experimental y en uno de los tres rotores de un turbogenerador.

  15. DNA and Protein Requirements for Substrate Conformational Changes Necessary for Human Flap Endonuclease-1-catalyzed Reaction.

    Science.gov (United States)

    Algasaier, Sana I; Exell, Jack C; Bennet, Ian A; Thompson, Mark J; Gotham, Victoria J B; Shaw, Steven J; Craggs, Timothy D; Finger, L David; Grasby, Jane A

    2016-04-08

    Human flap endonuclease-1 (hFEN1) catalyzes the essential removal of single-stranded flaps arising at DNA junctions during replication and repair processes. hFEN1 biological function must be precisely controlled, and consequently, the protein relies on a combination of protein and substrate conformational changes as a prerequisite for reaction. These include substrate bending at the duplex-duplex junction and transfer of unpaired reacting duplex end into the active site. When present, 5'-flaps are thought to thread under the helical cap, limiting reaction to flaps with free 5'-terminiin vivo Here we monitored DNA bending by FRET and DNA unpairing using 2-aminopurine exciton pair CD to determine the DNA and protein requirements for these substrate conformational changes. Binding of DNA to hFEN1 in a bent conformation occurred independently of 5'-flap accommodation and did not require active site metal ions or the presence of conserved active site residues. More stringent requirements exist for transfer of the substrate to the active site. Placement of the scissile phosphate diester in the active site required the presence of divalent metal ions, a free 5'-flap (if present), a Watson-Crick base pair at the terminus of the reacting duplex, and the intact secondary structure of the enzyme helical cap. Optimal positioning of the scissile phosphate additionally required active site conserved residues Tyr(40), Asp(181), and Arg(100)and a reacting duplex 5'-phosphate. These studies suggest a FEN1 reaction mechanism where junctions are bound and 5'-flaps are threaded (when present), and finally the substrate is transferred onto active site metals initiating cleavage.

  16. Analysis of biplane flapping flight with tail

    NARCIS (Netherlands)

    Tay, W.B.; Bijl, H.; Van Oudheusden, B.W.

    2012-01-01

    Numerical simulations have been performed to examine the interference effects between an upstream flapping biplane airfoil arrangement and a downstream stationary tail at a Reynolds number of 1000, which is around the regime of small flapping micro aerial vehicles. The objective is to investigate th

  17. A study of the use of the supraclavicular artery flap for resurfacing of head, neck, and upper torso defects

    Directory of Open Access Journals (Sweden)

    Telang Parag

    2009-01-01

    Full Text Available The head and neck region is an aesthetically demanding area to resurface because of its high visibility. Tissue defects in this area often require distant flaps or free flaps to achieve an aesthetically acceptable result. The use of the Supraclavicular artery flap represents an extremely versatile and useful option for the resurfacing of head, neck and upper torso defects. Furthermore, islanding the flap gives it a wide arc of rotation and the color and texture match is superior to that of free flaps harvested from distant sites. In our study, we used the flap (both unexpanded and expanded predominantly for resurfacing neck defects resulting from the release of post-burn contractures. However, its applicability in other indications would also be similar. Except one, all our flaps survived almost completely and the post-operative morbidity was very low. We conclude that the supraclavicular artery flap not only provides a reasonably good color and texture match but also maintains the multi-directional activity in the neck region.

  18. A soft rotor concept - design, verification and potentials

    Energy Technology Data Exchange (ETDEWEB)

    Rasmussen, F.; Thirstrup Petersen, J. [Risoe National Lab., Roskilde (Denmark)

    1999-03-01

    This paper contains results from development and testing of a two-bladed soft rotor for an existing 15 kW flexible wind turbine. The new concept is characterised as a free yawing down wind turbine with nacelle tilting flexibility and a two-bladed teetering rotor with three-point supported flexible blades with built-in structural couplings. The power and the loads are controlled by active stall and active coning. The concept has been developed by extensive application of aero-elastic predictions, numerical optimisation and stability analysis in order to obtain optimal aero-elastic response and minimal loads. The flexible blades and the principle of active coning allow the blades to deflect with the wind to such an extent that the loads are reduced to between 25 and 50% of the loads for a similar rigid rotor. All conceptual design principles have been focused on application to large MW turbines, and aero-elastic predictions for an upscale 1 MW version show that this would have approximately identical characteristisc, without being particularly optimised for the actual size. (au)

  19. Piezoelectrically actuated insect scale flapping wing

    Science.gov (United States)

    Mukherjee, Sujoy; Ganguli, Ranjan

    2010-04-01

    An energy method is used in order to derive the non-linear equations of motion of a smart flapping wing. Flapping wing is actuated from the root by a PZT unimorph in the piezofan configuration. Dynamic characteristics of the wing, having the same size as dragonfly Aeshna Multicolor, are analyzed using numerical simulations. It is shown that flapping angle variations of the smart flapping wing are similar to the actual dragonfly wing for a specific feasible voltage. An unsteady aerodynamic model based on modified strip theory is used to obtain the aerodynamic forces. It is found that the smart wing generates sufficient lift to support its own weight and carry a small payload. It is therefore a potential candidate for flapping wing of micro air vehicles.

  20. Energy management - The delayed flap approach

    Science.gov (United States)

    Bull, J. S.

    1976-01-01

    Flight test evaluation of a Delayed Flap approach procedure intended to provide reductions in noise and fuel consumption is underway using the NASA CV-990 test aircraft. Approach is initiated at a high airspeed (240 kt) and in a drag configuration that allows for low thrust. The aircraft is flown along the conventional ILS glide slope. A Fast/Slow message display signals the pilot when to extend approach flaps, landing gear, and land flaps. Implementation of the procedure in commercial service may require the addition of a DME navigation aid co-located with the ILS glide slope transmitter. The Delayed Flap approach saves 250 lb of fuel over the Reduced Flap approach, with a 95 EPNdB noise contour only 43% as large.

  1. Blood flow autoregulation in pedicled flaps

    DEFF Research Database (Denmark)

    Bonde, Christian T; Holstein-Rathlou, Niels-Henrik; Elberg, Jens J

    2009-01-01

    INTRODUCTION: Clinical work on the blood perfusion in skin and muscle flaps has suggested that some degree of blood flow autoregulation exists in such flaps. An autoregulatory mechanism would enable the flap to protect itself from changes in the perfusion pressure. The purpose of the present study...... was to evaluate if, and to what extent, a tissue flap could compensate a reduction in blood flow due to an acute constriction of the feed artery. Further, we wanted to examine the possible role of smooth muscle L-type calcium channels in the autoregulatory mechanism by pharmacological intervention with the L......-type calcium channel blocker nimodipine and the vasodilator papaverine. MATERIAL AND METHODS: Pedicled flaps were raised in pigs. Flow in the pedicle was reduced by constriction of the feed artery (n=34). A transit time flow probe measured the effect on blood flow continuously. Following this, three different...

  2. Energy management - The delayed flap approach

    Science.gov (United States)

    Bull, J. S.

    1976-01-01

    Flight test evaluation of a Delayed Flap approach procedure intended to provide reductions in noise and fuel consumption is underway using the NASA CV-990 test aircraft. Approach is initiated at a high airspeed (240 kt) and in a drag configuration that allows for low thrust. The aircraft is flown along the conventional ILS glide slope. A Fast/Slow message display signals the pilot when to extend approach flaps, landing gear, and land flaps. Implementation of the procedure in commercial service may require the addition of a DME navigation aid co-located with the ILS glide slope transmitter. The Delayed Flap approach saves 250 lb of fuel over the Reduced Flap approach, with a 95 EPNdB noise contour only 43% as large.

  3. White light spectroscopy for free flap monitoring.

    Science.gov (United States)

    Fox, Paige M; Zeidler, Kamakshi; Carey, Joseph; Lee, Gordon K

    2013-03-01

    White light spectroscopy non-invasively measures hemoglobin saturation at the capillary level rendering an end-organ measurement of perfusion. We hypothesized this technology could be used after microvascular surgery to allow for early detection of ischemia and thrombosis. The Spectros T-Stat monitoring device, which utilizes white light spectroscopy, was compared with traditional flap monitoring techniques including pencil Doppler and clinical exam. Data were prospectively collected and analyzed. Results from 31 flaps revealed a normal capillary hemoglobin saturation of 40-75% with increase in saturation during the early postoperative period. One flap required return to the operating room 12 hours after microvascular anastomosis. The T-stat system recorded an acute decrease in saturation from ~50% to less than 30% 50 min prior to identification by clinical exam. Prompt treatment resulted in flap salvage. The Spectros T-Stat monitor may be a useful adjunct for free flap monitoring providing continuous, accurate perfusion assessment postoperatively.

  4. 14 CFR 27.1461 - Equipment containing high energy rotors.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Equipment containing high energy rotors. 27... Equipment containing high energy rotors. (a) Equipment containing high energy rotors must meet paragraph (b), (c), or (d) of this section. (b) High energy rotors contained in equipment must be able to...

  5. 14 CFR 29.1461 - Equipment containing high energy rotors.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Equipment containing high energy rotors. 29... § 29.1461 Equipment containing high energy rotors. (a) Equipment containing high energy rotors must meet paragraph (b), (c), or (d) of this section. (b) High energy rotors contained in equipment must...

  6. 14 CFR 25.1461 - Equipment containing high energy rotors.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Equipment containing high energy rotors. 25... § 25.1461 Equipment containing high energy rotors. (a) Equipment containing high energy rotors must meet paragraph (b), (c), or (d) of this section. (b) High energy rotors contained in equipment must...

  7. Wind rotor with vertical axis. Vindrotor med vertikal axel

    Energy Technology Data Exchange (ETDEWEB)

    Colling, J.; Sjoenell, B.

    1987-06-15

    This rotor is of dual type i.e. a paddle wheel shaped rotor close to the vertical axis and a second rotor consisting of vertical blades with wing profile and attached to radial spokes which are fixed to the axis together with the paddle wheel rotor. (L.F.).

  8. On the torque mechanism of Savonius rotors

    Energy Technology Data Exchange (ETDEWEB)

    Fujisawa, N. (Dept. of Mechanical Univ., Kiryu (Japan))

    1992-07-01

    The aerodynamic performance and the flow fields of Savonius rotors at various overlap ratios have been investigated by measuring the pressure distributions on the blades and by visualizing the flow fields in and around the rotors with and without rotation. Experiments have been performed on four rotors having two semicircular blades but with different overlap ratios ranging 0 to 0.5. The static torque performance is improved by increasing the overlap ratio especially on the returning blade, which is due to the pressure recovery effect by the flow through the overlap. On the other hand, the torque and the power performance of the rotating rotor reaches a maximum at an overlap of 0.15. This effect is largely created by the Coanda-like flow on the convex side of the advancing blade, which is strengthened by the flow through the overlap at this small overlap ratio. However, this phenomena is weakened as the overlap ratio is further increased, suggesting a deteriorated performance of the rotor. Observations of the flow inside the rotor indicate an increased recirculation region at such large overlap ratios, which also suggests a reduced aerodynamic efficiency for rotors with large overlap. 11 figs., 16 refs.

  9. DIEP flap sentinel skin paddle positioning algorithm.

    Science.gov (United States)

    Laporta, Rosaria; Longo, Benedetto; Sorotos, Michail; Pagnoni, Marco; Santanelli Di Pompeo, Fabio

    2015-02-01

    Although clinical examination alone or in combination with other techniques is the only ubiquitous method for flap monitoring, it becomes problematic with buried free-tissue transfer. We present a DIEP flap sentinel skin paddle (SSP) positioning algorithm and its reliability is also investigated using a standardized monitoring protocol. All DIEP flaps were monitored with hand-held Doppler examination and clinical observation beginning immediately after surgery in recovery room and continued postoperatively at the ward. Skin paddle (SP) position was preoperatively drawn following mastectomy type incisions; in skin-sparing mastectomies types I-III a small SP (sSP) replaces nipple-areola complex; in skin-sparing mastectomy type IV, SSP is positioned between wise-pattern branches while in type V between medial/lateral branches. In case of nipple-sparing mastectomy SSP is positioned at inframammary fold or in lateral/medial branches of omega/inverted omega incision if used. Three hundred forty-seven DIEP flap breast reconstructions were reviewed and stratified according to SP type into group A including 216 flaps with large SP and group B including 131 flaps with SSP and sSP. Sixteen flaps (4.6%) were taken back for pedicle compromise, 13 of which were salvaged (81.25%), 11 among 13 from group A and 2 among 3 from group B. There was no statistical difference between the groups concerning microvascular complication rate (P = 0.108), and time until take-back (P = 0.521) and flap salvage rate (P = 0.473) resulted independent of SP type. Our results suggest that early detection of perfusion impairment and successful flaps salvage could be achieved using SSP for buried DIEP flap monitoring, without adjunctive expensive monitoring tests.

  10. Exotic wakes of flapping fins

    DEFF Research Database (Denmark)

    Schnipper, Teis

    We present, in 8 chapters, experiments on and numerical simulations of bodies flapping in a fluid. Focus is predominantly on a rigid foil, a model fish, that performs prescribed pitching oscillations where the foil rotates around its leading edge. In a flowing soap film is measured, with unpreced...... of frequencies. Drag reductions up to a factor 3 are measured. Many results presented are obtained through flow visualisations. A great effort is made to produce visualisations of primarily high scientific quality, but often also with a certain aesthetic appeal....

  11. Use of rotation scalp flaps for treatment of occipital baldness.

    Science.gov (United States)

    Juri, J; Juri, C; Arufe, H N

    1978-01-01

    We have used 25 rotation scalp flaps to treat occipital baldness associated with fronto-parietal baldness (the third flap), and 35 such flaps for the correction of isolated occipital baldness. We have not had any flap necrosis, and our patients have been well satisfied with the results of this surgery.

  12. Discrete analog computing with rotor-routers.

    Science.gov (United States)

    Propp, James

    2010-09-01

    Rotor-routing is a procedure for routing tokens through a network that can implement certain kinds of computation. These computations are inherently asynchronous (the order in which tokens are routed makes no difference) and distributed (information is spread throughout the system). It is also possible to efficiently check that a computation has been carried out correctly in less time than the computation itself required, provided one has a certificate that can itself be computed by the rotor-router network. Rotor-router networks can be viewed as both discrete analogs of continuous linear systems and deterministic analogs of stochastic processes.

  13. Multiple piece turbine rotor blade

    Energy Technology Data Exchange (ETDEWEB)

    Kimmel, Keith D.; Plank, William L.

    2016-07-19

    A spar and shell turbine rotor blade with a spar and a tip cap formed as a single piece, the spar includes a bottom end with dovetail or fir tree slots that engage with slots on a top end of a root section, and a platform includes an opening on a top surface for insertion of the spar in which a shell made from an exotic high temperature resistant material is secured between the tip cap and the platform. The spar is tapered to form thinner walls at the tip end to further reduce the weight and therefore a pulling force due to blade rotation. The spar and tip cap piece is made from a NiAL material to further reduce the weight and the pulling force.

  14. Study on wave rotor refrigerators

    Institute of Scientific and Technical Information of China (English)

    Yuqiang DAI; Dapeng HU; Meixia DING

    2009-01-01

    As a novel generation of a rotational gas wave machine, the wave rotor refrigerator (WRR) is an unsteady flow device used for refrigeration, in whose passages pressured streams directly contact and exchange energy due to the movement of pressure waves. In this paper, the working mechanism and refrigeration principle are inves-tigated based on the one-dimensional unsteady flow theory.A basic limitation on main structural parameters and operating parameters is deduced and the wave diagram of WRR to guide designing is sketched. The main influential factors are studied through an experiment. In the DUT Gas Wave Refrigeration Studying and Development Center (GWRSDC) lab, the isentropic efficiency can now reach about 65%. The results show that the WRR is a feasible and promising technology in pressured gas refrigeration cases.

  15. Rotor-Flying Manipulator: Modeling, Analysis, and Control

    Directory of Open Access Journals (Sweden)

    Bin Yang

    2014-01-01

    Full Text Available Equipping multijoint manipulators on a mobile robot is a typical redesign scheme to make the latter be able to actively influence the surroundings and has been extensively used for many ground robots, underwater robots, and space robotic systems. However, the rotor-flying robot (RFR is difficult to be made such redesign. This is mainly because the motion of the manipulator will bring heavy coupling between itself and the RFR system, which makes the system model highly complicated and the controller design difficult. Thus, in this paper, the modeling, analysis, and control of the combined system, called rotor-flying multijoint manipulator (RF-MJM, are conducted. Firstly, the detailed dynamics model is constructed and analyzed. Subsequently, a full-state feedback linear quadratic regulator (LQR controller is designed through obtaining linearized model near steady state. Finally, simulations are conducted and the results are analyzed to show the basic control performance.

  16. Total endoscopic free flap harvest of a serratus anterior fascia flap for microsurgical lower leg reconstruction

    Directory of Open Access Journals (Sweden)

    Erdmann, Alfons

    2014-04-01

    Full Text Available [english] Background: A tremendous number of free flaps have been developed in the past. As the surgical result depends not only on a successful flap transfer but also on the harvest, this paper details the procedures for undertaking the first total endoscopic harvest of a serratus fascia flap for free flap transplantation to the lower leg. Patient and methods: In September 2012 we performed the first total endoscopic serratus anterior fascia free flap harvest. The incision of 2.5 cm length was made 10 cm in front of anterior muscle border of the latissimus dorsi at level with the midthorax. After insertion of a flexible laparoscopic single port system we started CO gas insufflation. We used this setting to meticulously prepare a neo cavity between atissimus dorsi and M. serratus anterior. The vessels were dissected and the thoraco-dorsal nerve was separated. With a second auxiliary incision we used a clamp to support the raising of the fascia flap from the underlying muscle. Finally we clipped the vessels to the latissimus dorsi muscle and the flap vessels at the Arteria and Vena axillaris. The flap was extracted via the 2.5 cm incision.Results: We were able to perform a total endoscopic harvest of a serratus fascia flap for free flap reconstruction of soft tissues. With this new operative technique we were able to avoid a long skin incision, which in our view lowers the morbidity at the harvest area.Conclusion: We describe a new method for the total endoscopic harvest of the serratus fascia flap for free flap transfer. The flap was harvested within reasonable time and following surgery leaves the patient with minimal donor site morbidity compared to the open technique.

  17. Predesign study for a modern 4-bladed rotor for the NASA rotor systems research aircraft

    Science.gov (United States)

    Bishop, H. E.; Burkam, J. E.; Heminway, R. C.; Keys, C. N.; Smith, K. E.; Smith, J. H.; Staley, J. A.

    1981-01-01

    Trade-off study results and the rationale for the final selection of an existing modern four-bladed rotor system that can be adapted for installation on the Rotor Systems Research Aircraft (RSRA) are reported. The results of the detailed integration studies, parameter change studies, and instrumentation studies and the recommended plan for development and qualification of the rotor system is also given. Its parameter variants, integration on the RSRA, and support of ground and flight test programs are also discussed.

  18. The DelFly design, aerodynamics, and artificial intelligence of a flapping wing robot

    CERN Document Server

    de Croon, G C H E; Remes, B D W; Ruijsink, R; De Wagter, C

    2016-01-01

    This book introduces the topics most relevant to autonomously flying flapping wing robots: flapping-wing design, aerodynamics, and artificial intelligence. Readers can explore these topics in the context of the "Delfly", a flapping wing robot designed at Delft University in The Netherlands. How are tiny fruit flies able to lift their weight, avoid obstacles and predators, and find food or shelter? The first step in emulating this is the creation of a micro flapping wing robot that flies by itself. The challenges are considerable: the design and aerodynamics of flapping wings are still active areas of scientific research, whilst artificial intelligence is subject to extreme limitations deriving from the few sensors and minimal processing onboard. This book conveys the essential insights that lie behind success such as the DelFly Micro and the DelFly Explorer. The DelFly Micro, with its 3.07 grams and 10 cm wing span, is still the smallest flapping wing MAV in the world carrying a camera, whilst the DelFly Expl...

  19. Aerodynamic characteristics of a wing with Fowler flaps including flap loads, downwash, and calculated effect on take-off

    Science.gov (United States)

    Platt, Robert C

    1936-01-01

    This report presents the results of wind tunnel tests of a wing in combination with each of three sizes of Fowler flap. The purpose of the investigation was to determine the aerodynamic characteristics as affected by flap chord and position, the air loads on the flaps, and the effect of flaps on the downwash.

  20. HARP model rotor test at the DNW. [Hughes Advanced Rotor Program

    Science.gov (United States)

    Dawson, Seth; Jordan, David; Smith, Charles; Ekins, James; Silverthorn, Lou

    1989-01-01

    Data from a test of a dynamically scaled model of the Hughes Advanced Rotor Program (HARP) bearingless model main rotor and 369K tail rotor are reported. The history of the HARP program and its goals are reviewed, and the main and tail rotor models are described. The test facilities and instrumentation are described, and wind tunnel test data are presented on hover, forward flight performance, and blade-vortex interaction. Performance data, acoustic data, and dynamic data from near field/far field and shear layer studies are presented.

  1. The Savonius rotor. A construction guide. 11. ed.; Der Savonius-Rotor. Eine Bauanleitung

    Energy Technology Data Exchange (ETDEWEB)

    Schulz, Heinz

    2009-07-01

    The Savonius rotor is particularly suited for medium and low wind velocities and low capacities (up to 500 W). It can be constructed of commercial components and using simple techniques. It requires little wind to start, and the useful energy is transmitted via a shaft. In this lavishly illustrated book, the author describes the construction and operation of a robust Savonius rotor. He also shows how this rotor can be developed into a flow-through rotor for bigger plants, and he presents recommendations for appropriate machinery like pumps and slow generators.

  2. Hydrodynamic schooling of flapping swimmers

    Science.gov (United States)

    Becker, Alexander D.; Masoud, Hassan; Newbolt, Joel W.; Shelley, Michael; Ristroph, Leif

    2015-10-01

    Fish schools and bird flocks are fascinating examples of collective behaviours in which many individuals generate and interact with complex flows. Motivated by animal groups on the move, here we explore how the locomotion of many bodies emerges from their flow-mediated interactions. Through experiments and simulations of arrays of flapping wings that propel within a collective wake, we discover distinct modes characterized by the group swimming speed and the spatial phase shift between trajectories of neighbouring wings. For identical flapping motions, slow and fast modes coexist and correspond to constructive and destructive wing-wake interactions. Simulations show that swimming in a group can enhance speed and save power, and we capture the key phenomena in a mathematical model based on memory or the storage and recollection of information in the flow field. These results also show that fluid dynamic interactions alone are sufficient to generate coherent collective locomotion, and thus might suggest new ways to characterize the role of flows in animal groups.

  3. Ontogeny of aerial righting and wing flapping in juvenile birds

    CERN Document Server

    Evangelista, Dennis; Huynh, Tony; Krivitskiy, Igor; Dudley, Robert

    2014-01-01

    Mechanisms of aerial righting in juvenile Chukar Partridge (Alectoris chukar) were studied from hatching through 14 days post hatching (dph). Asymmetric movements of the wings were used from 1 to 8 dph to effect progressively more successful righting behaviour via body roll. Following 8 dph, wing motions transitioned to bilaterally symmetric flapping that yielded aerial righting via nose down pitch, along with substantial increases in vertical force production during descent. Ontogenetically, the use of such wing motions to effect aerial righting precedes both symmetric flapping and a previously documented behaviour in chukar (i.e., wing assisted incline running) hypothesized to be relevant to incipient flight evolution in birds. These findings highlight the importance of asymmetric wing activation and controlled aerial manoeuvres during bird development, and are potentially relevant to understanding the origins of avian flight.

  4. A Method to Transit the Rotor-to-Stator Rubbing to Normal Motion Using the Phase Characteristic

    Directory of Open Access Journals (Sweden)

    Jieqiong Xu

    2014-01-01

    Full Text Available A method is proposed to transit the rotor-to-stator rubbing to no-rub motion through active auxiliary bearing. The key point of this technique is to express the attractive domain of no-rub motion based on the phase characteristic and to represent the desired status. The feedback actuation is applied by an active auxiliary bearing to drive the rotor approaching the desired status. After that, the control actuation is turned off. Although the desired status is still in rubbing, it is in the attractive domain of no-rub motion, and the response of the rotor is automatically attracted to no-rub motion.

  5. Aerodynamics of Rotor Blades for Quadrotors

    CERN Document Server

    Bangura, Moses; Naldi, Roberto; Mahony, Robert

    2016-01-01

    In this report, we present the theory on aerodynamics of quadrotors using the well established momentum and blade element theories. From a robotics perspective, the theoretical development of the models for thrust and horizontal forces and torque (therefore power) are carried out in the body fixed frame of the quadrotor. Using momentum theory, we propose and model the existence of a horizontal force along with its associated power. Given the limitations associated with momentum theory and the inadequacy of the theory to account for the different powers represented in a proposed bond graph lead to the use of blade element theory. Using this theory, models are then developed for the different quadrotor rotor geometries and aerodynamic properties including the optimum hovering rotor used on the majority of quadrotors. Though this rotor is proven to be the most optimum rotor, we show that geometric variations are necessary for manufacturing of the blades. The geometric variations are also dictated by a desired th...

  6. Valve-aided twisted Savonius rotor

    Energy Technology Data Exchange (ETDEWEB)

    Jaya Rajkumar, M.; Saha, U.K.

    2006-05-15

    Accessories, such as end plates, deflecting plates, shielding and guide vanes, may increase the power of a Savonius rotor, but make the system structurally complex. In such cases, the rotor can develop a relatively large torque at small rotational speeds and is cheap to build, however it harnesses only a small fraction of the incident wind energy. Another proposition for increasing specific output is to place non-return valves inside the concave side of the blades. Such methods have been studied experimentally with a twisted-blade Thus improving a Savonius rotor's energy capture. This new concept has been named as the 'Valve-Aided Twisted Savonius'rotor. Tests were conducted in a low-speed wind tunnel to evaluate performance. This mechanism is found to be independent of flow direction, and shows potential for large machines. [Author].

  7. Reconstruction of lateral forefoot using reversed medial plantar flap with free anterolateral thigh flap.

    Science.gov (United States)

    Fujioka, Masaki; Hayashida, Kenji; Senju, Chikako

    2014-01-01

    Skin defects of the heel have frequently been reconstructed using the medial plantar flap; however, forefoot coverage has remained a challenge, because the alternatives for flap coverage have been very limited. We describe a case of malignant melanoma on the lateral forefoot that was radically removed and reconstructed successfully with a distally based medial plantar flap, together with a free anterolateral thigh flap. The advantages of this flap include that it does not reduce the vascular supply to the foot owing to reconstruction of the medial plantar vascular systems, reduces the risk of flap congestion, minimizes donor site morbidity, and enables the transport of structurally similar tissues to the plantar forefoot. We believe this technique is a reasonable reconstructive option for large lateral plantar forefoot defects.

  8. Pedicled Supraclavicular Artery Island Flap Versus Free Radial Forearm Flap for Tongue Reconstruction Following Hemiglossectomy.

    Science.gov (United States)

    Zhang, Senlin; Chen, Wei; Cao, Gang; Dong, Zhen

    2015-09-01

    This study investigated the tongue function and donor-site morbidity of patients with malignant tumors who had undergone immediate flap reconstruction surgery. Twenty-seven patients who had undergone immediate reconstruction after hemiglossectomy were observed. Twelve patients were reconstructed using the pedicled supraclavicular artery island flap (PSAIF) and 15 patients using the free radial forearm flap (FRFF). Flap survival, speech and swallowing function, and donor-site morbidity at the 6-month follow-up were evaluated. All the flaps were successfully transferred. No obvious complications were found in either the transferred flaps or donor regions. Age, sex, defect extent, speech and swallowing function were comparable between the 2 groups. Donor-site complications were less frequent with PSAIF reconstruction than FRFF reconstruction. The PSAIF is reliable and well suited for hemiglossectomy defect. It has few significant complications, and allows preservation of oral function.

  9. Monitoring of free TRAM flaps with microdialysis.

    Science.gov (United States)

    Udesen, A; Løntoft, E; Kristensen, S R

    2000-02-01

    The aim of this investigation was to follow the metabolism of free TRAM flaps using microdialysis. Microdialysis is a new sampling technique that provide opportunities to follow the biochemistry in specific organs or tissues. A double-lumen microdialysis catheter or probe, with a dialysis membrane at the end, is introduced into the specific tissue. Perfusion fluid is slowly pumped through the catheter and equilibrates across the membrane with surrounding extracellular concentrations of low molecular weight substances. The dialysate is collected in microvials and analyzed by an instrument using very small volumes. Glucose, glycerol, and lactate concentrations were measured in the flaps and compared with those in a reference catheter that was placed subcutaneously in the femur. The investigation continued 72 hr postoperatively. The study group consisted of 14 women who underwent reconstruction with a free TRAM flap, and one woman with a double TRAM flap. During flap ischemia, the concentration of glucose was reduced, while the lactate and glycerol levels increased. The differences between the flaps and controls were statistically highly significant. After reperfusion of the flaps, the concentrations of glucose, lactate, and glycerol approached normal. One flap failed because of an arterial anastomosis thrombosis. This was clearly demonstrated by the samples from the microdialysis: the concentration of glucose fell to an unmeasurable level; the concentration of lactate increased for a period before it stopped due to lack of glucose; and the concentration of glycerol increased to a very high level, probably because ischemia caused damage to the cell membranes of which glycerol is an important part. The authors concluded that microdialysis can detect ischemia in free flaps at an early stage, making early surgical intervention possible.

  10. Edge states of periodically kicked quantum rotors

    CERN Document Server

    Floß, Johannes

    2015-01-01

    We present a quantum localization phenomenon that exists in periodically kicked 3D rotors, but is absent in the commonly studied 2D ones: edge localization. We show that under the condition of a fractional quantum resonance there are states of the kicked rotor that are strongly localized near the edge of the angular momentum space at $J=0$. These states are analogs of surface states in crystalline solids, and they significantly affect resonant excitation of molecular rotation by laser pulse trains.

  11. Rotor dynamic analysis of main coolant pump

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Chong Won; Seo, Jeong Hwan; Kim, Choong Hwan; Shin, Jae Chul; Wang, Lei Tian [Korea Advanced Institute of Science and Technology, Taejon (Korea)

    1999-03-01

    A rotor dynamic analysis program DARBS/MCP, for the main coolant pump of the integral reactor, has been developed. The dynamic analysis model of the main coolant pump includes a vertical shaft, three grooved radial journal bearings and gaps that represent the structure-fluid interaction effects between the rotor and the lubricant fluid. The electromagnetic force from the motor and the hydro-dynamic force induced by impeller are the major sources of vibration that may affect the rotor system stability. DARBS/MCP is a software that is developed to effectively analyze the dynamics of MCP rotor systems effectively by applying powerful numerical algorithms such as FEM with modal truncation and {lambda}-matrix method for harmonic analysis. Main design control parameters, that have much influence to the dynamic stability, have been found by Taguchi's sensitivity analysis method. Design suggestions to improve the stability of MCP rotor system have been documented. The dynamic bearing parameters of the journal bearings used for main coolant pump have been determined by directly solving the Reynolds equation using FDM method. Fluid-structure interaction effect that occurs at the small gaps between the rotor and the stator were modeled as equivalent seals, the electromagnetic force effect was regarded as a linear negative radial spring and the impeller was modeled as a rigid disk with hydrodynamic and static radial force. Although there exist critical speeds in the range of operational speeds for type I and II rotor systems, the amplitude of vibration appears to be less than the vibration limit set by the API standards. Further more, it has been verified that the main design parameters such as the clearance and length of journal bearings, and the static radial force of impeller should be properly adjusted, in order to the improve dynamic stability of the rotor system. (author). 39 refs., 81 figs., 17 tabs.

  12. Regional flaps in head and neck reconstruction: a reappraisal.

    Science.gov (United States)

    Colletti, Giacomo; Tewfik, Karim; Bardazzi, Alessandro; Allevi, Fabiana; Chiapasco, Matteo; Mandalà, Marco; Rabbiosi, Dimitri

    2015-03-01

    Starting from our experience with 45 consecutive cases of regional pedicled flaps, we have underlined the effectiveness and reliability of a variety of flaps. The marketing laws as applied to surgical innovations are reviewed to help in the understanding of why regional flaps are regaining wide popularity in head and neck reconstruction. From January 2009 to January 2014, 45 regional flaps were harvested at San Paolo Hospital to reconstruct head and neck defects. These included 35 pectoralis major muscular and myocutaneous flaps, 4 lower trapezius island or pedicled flaps, 3 supraclavicular flaps, 2 latissimus dorsi pedicled flaps, and 1 fasciocutaneous temporal flap. The basic literature of marketing regarding the diffusion of new products was also reviewed. Two myocutaneous pectoralis major flaps were complicated by necrosis of the cutaneous paddle (one complete and one partial). No complete loss of any of the 45 flaps was observed. At 6 months of follow-up, 2 patients had died of multiple organ failure after prolonged sepsis. The 43 remaining patients had acceptable morphologic and functional results. Regional and free flaps appear to compete in many cases for the same indications. From the results of the present case series, regional flaps can be considered reliable reconstructive choices that are less expensive than their free flap alternatives. The "resurrection" of regional flaps can be partially justified by the changes in the global economy and the required adaptation of developed and developing countries. Copyright © 2015 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

  13. Fatigue Test Technology of Slat and Flap with Active Driving and Servo Loading Device%一种主动驱动随动加载的前缘缝翼和襟翼疲劳试验技术

    Institute of Scientific and Technical Information of China (English)

    李小军; 陆慧莲; 李凯

    2014-01-01

    前缘缝翼、襟翼活动面及其支承结构的疲劳试验是民用飞机取证前要开展的一项重要工作。在试验中采用主动驱动和随动加载方法加载,不仅能缩小试验规模,同时可提高试验精度。国内某型机采用此技术成功进行了前缘缝翼、襟翼及其悬挂结构的疲劳试验。从试验件及其支承设计、系统构成和载荷与运行三方面,介绍了一种适用于大中型固定翼飞机前缘缝翼和襟翼的疲劳试验技术。%The fatigue tests on slat, flap and their supporting structures are very important work to be launched for a new airplane before technology certification ( TC) being granted. The loading which adopts active driving and ser-vo loading not only reduces the test scale but also enhances the test accuracy. This technology has been applied to make the fatigue test on some civil aircraft successfully. This paper presents the new fatigue test technology in three aspects:test article with its suspension, test system, load and implementation respectively.

  14. The Clinical Application of Anterolateral Thigh Flap

    Directory of Open Access Journals (Sweden)

    Yao-Chou Lee

    2011-01-01

    Furthermore, several modifications widen its clinical applications: the fascia lata can be included for sling or tendon reconstruction, the bulkiness could be created by including vastus lateralis muscle or deepithelization of skin flap, the pliability could be increased by suprafascial dissection or primary thinning, the pedicle length could be lengthening by proximally eccentric placement of the perforator, and so forth. Combined with these technical and conceptual advancements, the anterolateral thigh flap has become the workhorse flap for soft-tissue reconstructions from head to toe.

  15. New drag laws for flapping flight

    Science.gov (United States)

    Agre, Natalie; Zhang, Jun; Ristroph, Leif

    2014-11-01

    Classical aerodynamic theory predicts that a steadily-moving wing experiences fluid forces proportional to the square of its speed. For bird and insect flight, however, there is currently no model for how drag is affected by flapping motions of the wings. By considering simple wings driven to oscillate while progressing through the air, we discover that flapping significantly changes the magnitude of drag and fundamentally alters its scaling with speed. These measurements motivate a new aerodynamic force law that could help to understand the free-flight dynamics, control, and stability of insects and flapping-wing robots.

  16. Investigation of rotor control system loads

    Institute of Scientific and Technical Information of China (English)

    Sun Tao; Tan Jianfeng; Wang Haowen

    2013-01-01

    This paper concentrates on the aeroelasticity analysis of rotor blade and rotor control systems. A new multi-body dynamics model is established to predict both rotor pitch link loads and swashplate servo loads. Two helicopter rotors of UH-60A and SA349/2, both operating in two critical flight conditions, high-speed flight and high-thrust flight, are studied. The analysis shows good agreements with the flight test data and the calculation results using CAMRAD II. The mechanisms of rotor control loads are then analyzed in details based on the present predictions and the flight test data. In high-speed conditions, the pitch link loads are dominated by the integral of blade pitching moments, which are generated by cyclic pitch control. In high-thrust conditions, the positive pitching loads in the advancing side are caused by high collective pitch angle, and dynamic stall in the retreating side excites high-frequency responses. The swashplate servo loads are predominated by the rotor pitch link loads, and the inertia of the swashplate has significant effects on high-frequency harmonics of the servo loads.

  17. Forces exciting generation roll at rotor vibrations when rotor-to-stator rubbing

    Science.gov (United States)

    Shatokhin, V. F.

    2017-07-01

    The consequences of emergencies of turbosets for different application are revealed, the cause of forced shutdown and even catastrophic destructions of which many researchers consider the rotor-to-stator rubbing and development—to a greater or lesser extent—of the phenomena of the rotor generation roll over the stator. The synchronous or asynchronous generation roll is determined by the rotor precession direction, coinciding or not coinciding with the self-rotation direction of the rotor. Asynchronous generation roll is the most dangerous form of the rotor-stator contact interaction with the vibrations with rubbing. The basic equations of rotor vibrations are presented: symmetric rotor fixed on two supports and that fixed on several supports after abrupt imbalance with and without rotor coming in contact with a flexible stator. The vibration process is considered as the rotor motion in a backlash with subsequent contact with the stator, loss of contact, or development of generation roll. The latter essentially depends on the properties of the "rotor-support-stator" dynamic system. The stator stiffness characteristic is specified in "force-deformation" coordinates that make it possible to take into account damping in the supports and power loss in the stator. The diagram of elastic-damping device was presented, which makes it possible to ensure a certain level of power loss at the stator displacements. The exciting forces promoting development of self-exciting vibrations of the rotor in the form of asynchronous generation roll were compared with the exciting forces of oil film of sliding bearings and forces of aerodynamic excitation in the turbine flow path and sealings. For the rotor systems of high and medium pressure of a 300 MW capacity turboset, the simulation results of the process of development of asynchronous generation roll at the vibrations with rubbing were revealed, and the basic characteristics of development of generation roll in a span between

  18. RESEARCH OF THE HIGH HARMONICS INDIVIDUAL BLADE CONTROL EFFECT ON VIBRATIONS CAUSED BY THE HELICOPTER MAIN ROTOR THRUST

    Directory of Open Access Journals (Sweden)

    2016-01-01

    Full Text Available The paper presents numerical results analysis of main rotor vibration due to helicopter main rotor thrust pulsation.The calculation method, the object of research and numerical research results with the aim to reduce the amplitude of the vibrations transmitted to the hub from the helicopters main rotor by the individual blade control in azimuth by the installation angle of blades cyclic changes are set out in the article. The individual blades control law for a five-blade main rotor based on the blade frequencies is made. It allows reducing the vibration from thrust. Research takes into account the main rotor including and excluding the blade flapping motion. The minimal vibrations regime is identified.Numerical study of variable loads caused by unsteady flow around the main rotor blades at high relative speeds of flight, which transmitted to the rotor hub, is made. The scheme of a thin lifting surface and the rotor vortex theory are used for simulation of the aerodynamic loads on blades. Non - uniform loads caused by the thrust, decomposed on the blade harmonic and its overtones. The largest values of deviation from the mean amplitude thrust are received. The analysis of variable loads with a traditional control system is made. Algorithms of higher harmonics individual blade control capable of reducing the thrust pulsation under the average value of thrust are developed.Numerical research shows that individual blade control of high harmonics reduces variable loads. The necessary change in the blade installation is about ± 0,2 degree that corresponds to the maximum displacement of the additional con- trol stick is about 1 mm.To receive the overall picture is necessary to consider all six components of forces and moments. Control law with own constants will obtained for each of them. It is supposed, that each of six individual blade control laws have an impact on other components. Thus, the problem reduces to the optimization issue. The

  19. Teknik Rekonstruksi Turndown Flap Tendon Achilles dan Flap Fasiokutan Sural pada Ruptur Tendon Achilles yang Disertai Kerusakan Masif Jaringan Lunak: Laporan Kasus

    Directory of Open Access Journals (Sweden)

    Hermawan Nagar Rasyid

    2016-03-01

    Full Text Available Achilles tendon rupture is the most common ruptur of tendon in the lower limb despite being one of the toughest tendons. This rupture presents a complex problem to the treating surgeon especially if it is associated with tendon and soft tissue loss. The case in this study is one patient (male, age 30-year old with a spectrum of acute and infected open tendon-achilles rupture that includes loss of tendon of up to 5 cm, tendon defect with no distal attachment, and partial loss of the calcaneum. The skin defect measured after debridement ranged from 8 x 5 cm to 15 x 10 cm. The ruptured tendon was sutured using gastrocnemius-soleus turn down flap technic to calcaneus bone. A reverse sural artery was used to provide soft tissue cover. The flap survived. The patient had normal gait, were able to stand on tip toes, had active plantar flexion, and had returned to his original occupation 2 months after reconstruction. He had full range of movement at the ankle. Augmented repair of Achilles tendon rupture with large soft tissue defect using gastrocnemius- soleus turn down flap and sural artery flap are stable enough to allow early weight-bearing with favorable clinical result for this patient. Conclusions is single stage tendon reconstruction and reverse flow sural artery flap give good functional outcome in complex Achilles tendon rupture with tendon and soft tissue loss.

  20. Paramedian forehead flap combined with hinge flap for nasal tip reconstruction*

    Science.gov (United States)

    Cerci, Felipe Bochnia; Dellatorre, Gerson

    2016-01-01

    The paramedian forehead flap is a great option for restoration of complex nasal defects. For full-thickness defects, it may be used alone or in combination with other methods. We present a patient with a basal cell carcinoma on the distal nose treated by Mohs micrographic surgery, and a resulting full-thickness defect repaired with paramedian forehead flap combined with a hinge flap. For optimal results with the paramedian forehead flap, adequate surgical planning, patient orientation and meticulous surgical technique are imperative.

  1. Helicopter Rotor Sailing by Non-Smooth Dynamics Co-Simulation

    Directory of Open Access Journals (Sweden)

    Fancello Matteo

    2014-08-01

    Full Text Available This paper presents the application of a co-simulation approach for the simulation of frictional contact in general-purpose multibody dynamics to a rotorcraft dynamics problem. The proposed approach is based on the co-simulation of a main problem, which is described and solved as a set of differential algebraic equations, with a subproblem that is characterized by nonsmooth dynamics events and solved using a timestepping technique. The implementation and validation of the formulation is presented. The method is applied to the analysis of the droop and anti-flap contacts of helicopter rotor blades. Simulations focusing on the problem of blade sailing are conducted to understand the behavior and assess the validity of the method. For this purpose, the results obtained using a contact model based on Hertzian reaction forces at the interface are compared with those of the proposed approach.

  2. User's Guide for the NREL Teetering Rotor Analysis Program (STRAP). [National Renewable Energy Laboratory (NREL)

    Energy Technology Data Exchange (ETDEWEB)

    Wright, A.D.

    1992-08-01

    The following report gives the reader an overview of instructions on the proper use of the National Renewable Energy Laboratory (formerly the Solar Energy Research Institute, or SERI) teetering Rotor Analysis Program (STRAP version 2.20). STRAP is a derivative of the Force and Loads Analysis program (FLAP). It is intended as a tool for prediction of rotor and blade loads and response for only two-bladed teetering hub wind turbines. The effects of delta-3, undersling, hub mass, and wind turbulence are accounted for. The objectives of the report are to give an overview of the code and also show the methods of data input and correct code execution steps in order to model an example two-bladed teetering hub turbine. A large portion of the discussion (Sections 6.0, 7.0, and 8.0) is devoted to the subject of inputting and running the code for wind turbulence effects. The ability to include turbulent wind effects is perhaps the biggest change in the code since the release of FLAP version 2.01 in 1988. This report is intended to be a user's guide. It does not contain a theoretical discussion on equations of motion, assumptions, underlying theory, etc. It is intended to be used in conjunction with Wright, Buhl, and Thresher (1988).

  3. [Outcome of relaying anterolateral thigh perforator flap in resurfacing the donor site wound following free anteromedial thigh perforator flap transfer for reconstruction of defect after oral tumor radical resection].

    Science.gov (United States)

    Song, D J; Li, Z; Zhou, X; Zhang, Y X; Peng, X W; Zhou, B; Lyu, C L; Yang, L C; Peng, W

    2017-02-20

    -point discrimination distances of the sites repaired with relaying ALT perforator flaps were ranged from 7 to 12 mm. The function of thigh was not obviously affected, and patients could walk normally and do related daily activities. Conclusions: Reconstruction of defect after oral tumor radical resection with free AMT perforator flap can achieve good outcome, and wound in the donor site of free AMT perforator flap repaired with relaying ALT perforator flap can achieve good appearance and function recovery.

  4. Feedback-Controlled Lubrication for Reducing the Lateral Vibration of Flexible Rotors supported by Tilting-Pad Journal Bearings

    DEFF Research Database (Denmark)

    Salazar, Jorge Andrés González; Santos, Ilmar

    2014-01-01

    In this work, the feedback-controlled lubrication regime, based on a model-free designed proportional-derivative (PD) controller, is studied and experimentally tested in a flexible rotor mounted on an actively-lubricated tilting-pad journal bearing (active TPJB). With such a lubrication regime......-controlled lubrication regime featured via PD controllers. Good experimental results are obtained, and a significant improvement of the flexible rotor-bearing system dynamic performance can be experimentally demonstrated....

  5. Management of Vortices Trailing Flapped Wings via Separation Control

    Science.gov (United States)

    Greenblatt, David

    2005-01-01

    A pilot study was conducted on a flapped semi-span model to investigate the concept and viability of near-wake vortex management via separation control. Passive control was achieved by means of a simple fairing and active control was achieved via zero mass-flux blowing slots. Vortex sheet strength, estimated by integrating surface pressure ports, was used to predict vortex characteristics by means of inviscid rollup relations. Furthermore, vortices trailing the flaps were mapped using a seven-hole probe. Separation control was found to have a marked effect on vortex location, strength, tangential velocity, axial velocity and size over a wide range of angles of attack and control conditions. In general, the vortex trends were well predicted by the inviscid rollup relations. Manipulation of the separated flow near the flap edges exerted significant control over both outboard and inboard edge vortices while producing negligible lift excursions. Dynamic separation and attachment control was found to be an effective means for dynamically perturbing the vortex from arbitrarily long wavelengths down to wavelengths less than a typical wingspan. In summary, separation control has the potential for application to time-independent or time-dependent wake alleviation schemes, where the latter can be deployed to minimize adverse effects on ride-quality and dynamic structural loading.

  6. Modeling the Motion of a Flapping Wing Aerial Vehicle

    Directory of Open Access Journals (Sweden)

    Vorochaeva L.Y.

    2017-01-01

    Full Text Available The article discusses the vertical flight of a flapping wing aerial vehicle, which is also called an ornithopter. The robot is a chain of five links connected in series by active cylindrical hinges with the central link being the body and the remainder forming folding wings in pairs. The distinctive feature of this device is that the flaps of its wings imitate those of a seagull i.e. the device has a biological prototype. We construct a mathematical model of this device; much attention is given to the model of the interaction of the wings with the air environment and we determine the positions and velocities of points of application of the reduced aerodynamic forces to each of the links. Based on the results of numerical modelling of the vertical flight of the robot three modes of flight were established: ascent, hovering at a certain height and descent. The device can operate in these modes based on the oscillation parameters of the wings in particular flapping frequency and amplitude, the ratio of the amplitudes of two links and one wing and the shift of the equilibrium oscillation position of the wings relative to zero.

  7. A rotor for a high-rise building; Ein Rotor fuer das Hochhaus

    Energy Technology Data Exchange (ETDEWEB)

    Zastrow, F. [Hochschule Bremerhaven (Germany). Inst. fuer Automatisierungs- und Elektrotechnik; Okoth, G.; Boehm, K.; El Naggar, S. [Alfred-Wegener Inst. fuer Polar- und Meeresforschung, Bremerhaven (Germany)

    2004-08-30

    The typical characteristics of the H rotor recommend it not only for use in extreme climate zones but also for installation on buildings and in built-on terrain. It is difficult, however, to make small H rotors efficient and economical. (orig.)

  8. Behind the performance of flapping flyers

    CERN Document Server

    Ramananarivo, Sophie; Thiria, Benjamin

    2010-01-01

    Saving energy and enhancing performance are secular preoccupations shared by both nature and human beings. In animal locomotion, flapping flyers or swimmers rely on the flexibility of their wings or body to passively increase their efficiency using an appropriate cycle of storing and releasing elastic energy. Despite the convergence of many observations pointing out this feature, the underlying mechanisms explaining how the elastic nature of the wings is related to propulsive efficiency remain unclear. Here we use an experiment with a self-propelled simplified insect model allowing to show how wing compliance governs the performance of flapping flyers. Reducing the description of the flapping wing to a forced oscillator model, we pinpoint different nonlinear effects that can account for the observed behavior ---in particular a set of cubic nonlinearities coming from the clamped-free beam equation used to model the wing and a quadratic damping term representing the fluid drag associated to the fast flapping mo...

  9. Periodic and Chaotic Flapping of Insectile Wings

    CERN Document Server

    Huang, Yangyang

    2015-01-01

    Insects use flight muscles attached at the base of the wings to produce impressive wing flapping frequencies. The maximum power output of these flight muscles is insufficient to maintain such wing oscillations unless there is good elastic storage of energy in the insect flight system. Here, we explore the intrinsic self-oscillatory behavior of an insectile wing model, consisting of two rigid wings connected at their base by an elastic torsional spring. We study the wings behavior as a function of the total energy and spring stiffness. Three types of behavior are identified: end-over-end rotation, chaotic motion, and periodic flapping. Interestingly, the region of periodic flapping decreases as energy increases but is favored as stiffness increases. These findings are consistent with the fact that insect wings and flight muscles are stiff. They further imply that, by adjusting their muscle stiffness to the desired energy level, insects can maintain periodic flapping mechanically for a range of operating condit...

  10. Vascular anatomy of the anteromedial thigh flap

    Directory of Open Access Journals (Sweden)

    Jeremy Mingfa Sun

    2017-09-01

    Conclusion: The anatomy of the RFB, which is critical in the blood supply of the AMT flap, is constant and predictable. The location of the perforators is predictable, which aids preoperative planning.

  11. A dynamical system for interacting flapping swimmers

    Science.gov (United States)

    Oza, Anand; Ramananarivo, Sophie; Ristroph, Leif; Shelley, Michael

    2015-11-01

    We present the results of a theoretical investigation into the dynamics of interacting flapping swimmers. Our study is motivated by the recent experiments of Becker et al., who studied a one-dimensional array of self-propelled flapping wings that swim within each other's wakes in a water tank. They discovered that the system adopts certain ``schooling modes'' characterized by specific spatial phase relationships between swimmers. To rationalize these phenomena, we develop a discrete dynamical system in which the swimmers are modeled as heaving airfoils that shed point vortices during each flapping cycle. We then apply our model to recent experiments in the Applied Math Lab, in which two tandem flapping airfoils are free to choose both their speed and relative positions. We expect that our model may be used to understand how schooling behavior is influenced by hydrodynamics in more general contexts. Thanks to the NSF for its support.

  12. The flow around a flapping foil

    Science.gov (United States)

    Mandujano, Francisco; Malaga, Carlos

    2016-11-01

    The flow around a two-dimensional flapping foil immersed in a uniform stream is studied numerically using a Lattice-Boltzmann model, for Reynolds numbers between 100 and 250, and flapping Strouhal numbers between 0 . 01 and 0 . 6 . The computation of the hydrodynamic force on the foil is related to the wake structure. When the foil's is fixed in space, numerical results suggest a relation between drag coefficient behaviour and the flapping frequency which determines the transition from the von Kármán to the inverted von Kármán wake. When the foil is free of translational motion up-stream swimming at constant speed is observed at certain values of the flapping Strouhal. This work was partially supported by UNAM-DGAPA-PAPIIT Grant Number IN115316.

  13. Preliminary Design and Evaluation of an Airfoil with Continuous Trailing-Edge Flap

    Science.gov (United States)

    Shen, Jinwei; Thornburgh, Robert P.; Kreshock, Andrew R.; Wilbur, Matthew L.; Liu, Yi

    2012-01-01

    This paper presents the preliminary design and evaluation of an airfoil with active continuous trailing-edge flap (CTEF) as a potential rotorcraft active control device. The development of structural cross-section models of a continuous trailing-edge flap airfoil is described. The CTEF deformations with MFC actuation are predicted by NASTRAN and UM/VABS analyses. Good agreement is shown between the predictions from the two analyses. Approximately two degrees of CTEF deflection, defined as the rotation angle of the trailing edge, is achieved with the baseline MFC-PZT bender. The 2D aerodynamic characteristics of the continuous trailing-edge flap are evaluated using a CFD analysis. The aerodynamic efficiency of a continuous trailing-edge flap is compared to that of a conventional discrete trailing-edge flap (DTEF). It is found that the aerodynamic characteristics of a CTEF are equivalent to those of a conventional DTEF with the same deflection angle but with a smaller flap chord. A fluid structure interaction procedure is implemented to predict the deflection of the continuous trailingedge flap under aerodynamic pressure. The reductions in CTEF deflection are overall small when aerodynamic pressure is applied: 2.7% reduction is shown with a CTEF deflection angle of two degrees and at angle of attack of six degrees. In addition, newly developed MFC-PMN actuator is found to be a good supplement to MFC-PZT when applied as the bender outside layers. A mixed MFC-PZT and MFC-PMN bender generates 3% more CTEF deformation than an MFC-PZT only bender and 5% more than an MFC-PMN only bender under aerodynamic loads.

  14. Electric Drive Control with Rotor Resistance and Rotor Speed Observers Based on Fuzzy Logic

    Directory of Open Access Journals (Sweden)

    C. Ben Regaya

    2014-01-01

    Full Text Available Many scientific researchers have proposed the control of the induction motor without speed sensor. These methods have the disadvantage that the variation of the rotor resistance causes an error of estimating the motor speed. Thus, simultaneous estimation of the rotor resistance and the motor speed is required. In this paper, a scheme for estimating simultaneously the rotor resistance and the rotor speed of an induction motor using fuzzy logic has been developed. We present a method which is based on two adaptive observers using fuzzy logic without affecting each other and a simple algorithm in order to facilitate the determination of the optimal values of the controller gains. The control algorithm is proved by the simulation tests. The results analysis shows the characteristic robustness of the two observers of the proposed method even in the case of variation of the rotor resistance.

  15. Optimum blade loading for a powered rotor in descent

    Institute of Scientific and Technical Information of China (English)

    Ramin Modarres; David A. Peters

    2016-01-01

    The optimum loading for rotors has previously been found for hover, climb and wind turbine conditions;but, up to now, no one has determined the optimum rotor loading in descent. This could be an important design consideration for rotary-wing parachutes and low-speed des-cents. In this paper, the optimal loading for a powered rotor in descent is found from momentum theory based on a variational principle. This loading is compared with the optimal loading for a rotor in hover or climb and with the Betz rotor loading (which is optimum for a lightly-loaded rotor). Wake contraction for each of the various loadings is also presented.

  16. THE DESIGN OF AXIAL PUMP ROTORS USING THE NUMERICAL METHODS

    Directory of Open Access Journals (Sweden)

    Ali BEAZIT

    2010-06-01

    Full Text Available The researches in rotor theory, the increasing use of computers and the connection between design and manufacturing of rotors, have determined the revaluation and completion of classical rotor geometry. This paper presents practical applications of mathematical description of rotor geometry. A program has been created to describe the rotor geometry for arbitrary shape of the blade. The results can be imported by GAMBIT - a processor for geometry with modeling and mesh generations, to create a mesh needed in hydrodynamics analysis of rotor CFD. The results obtained are applicable in numerical methods and are functionally convenient for CAD/CAM systems.

  17. Interpreting laser Doppler recordings from free flaps.

    Science.gov (United States)

    Svensson, H; Holmberg, J; Svedman, P

    1993-01-01

    Although the transfer of free flaps is nowadays accomplished with an increasing degree of safety, thrombosis of the microvascular anastomoses is still a problem. In order to avoid delay in re-operating, various methods for objective blood flow monitoring have been tried, among them Laser Doppler Flowmetry (LDF). When one reviews the literature, it is apparent that opinions differ about whether or not LDF is a reliable technique for this purpose. To focus on the need to interpret continuous recordings, this paper reports our findings in six latissimus dorsi free flaps chosen from our series of LDF monitoring procedures. One uneventful flap, no. 1, had an immediate postoperative LDF value of 4.5 perfusion units (PU). LDF values improved during the recovery period and the graphic recording showed fluctuations due to normal physiological variations of the blood flow in the flap. Another uneventful flap, no. 4, showed the same pattern, though at an appreciably lower level, 2 PU, on average. Flap no. 2 had an acceptably high value of 3.5 PU despite suffering a venous thrombosis. However, the LDF recording showed no fluctuations and the value declined gradually. Another flap, no. 3, showed fluctuations and blood flow was normal although the value decreased to 2.5 PU. In flap no. 5, any value between 2 and 3.5 PU could be obtained merely by adjusting the position of the probe in the holder. In no. 6, the LDF value suddenly dropped, accompanied by a decrease in the total amount of backscattered light, indicating venous obstruction which was confirmed at re-operation.(ABSTRACT TRUNCATED AT 250 WORDS)

  18. Freestyle Local Perforator Flaps for Facial Reconstruction

    OpenAIRE

    Jun Yong Lee; Ji Min Kim; Ho Kwon; Sung-No Jung; Hyung Sup Shim; Sang Wha Kim

    2015-01-01

    For the successful reconstruction of facial defects, various perforator flaps have been used in single-stage surgery, where tissues are moved to adjacent defect sites. Our group successfully performed perforator flap surgery on 17 patients with small to moderate facial defects that affected the functional and aesthetic features of their faces. Of four complicated cases, three developed venous congestion, which resolved in the subacute postoperative period, and one patient with partial necrosi...

  19. On the nonlinear steady-state response of rigid rotors supported by air foil bearings-Theory and experiments

    Science.gov (United States)

    Larsen, Jon S.; Santos, Ilmar F.

    2015-06-01

    The demand for oil-free turbo compressors is increasing. Current trends are divided between active magnetic bearings and air foil bearings (AFB), the latter being important due to mechanical simplicity. AFB supported rotors are sensitive to unbalance due to low damping and nonlinear characteristics, hence accurate prediction of their response is important. This paper gives theoretical and experimental contributions by implementing and validating a new method to simulate the nonlinear steady-state response of a rotor supported by three pads segmented AFBs. The fluid film pressures, foil deflections and rotor movements are simultaneously solved, considering foil stiffness and damping coefficients estimated using a structural model, previously described and validated against experiments.

  20. Rotor Wake Development During the First Revolution

    Science.gov (United States)

    McAlister, Kenneth W.

    2003-01-01

    The wake behind a two-bladed model rotor in light climb was measured using particle image velocimetry, with particular emphasis on the development of the trailing vortex during the first revolution of the rotor. The distribution of vorticity was distinguished from the slightly elliptical swirl pattern. Peculiar dynamics within the void region may explain why the peak vorticity appeared to shift away from the center as the vortex aged, suggesting the onset of instability. The swirl and axial velocities (which reached 44 and 12 percent of the rotor-tip speed, respectively) were found to be asymmetric relative to the vortex center. In particular, the axial flow was composed of two concentrated zones moving in opposite directions. The radial distribution of the circulation rapidly increased in magnitude until reaching a point just beyond the core radius, after which the rate of growth decreased significantly. The core-radius circulation increased slightly with wake age, but the large-radius circulation appeared to remain relatively constant. The radial distributions of swirl velocity and vorticity exhibit self-similar behaviors, especially within the core. The diameter of the vortex core was initially about 10 percent of the rotor-blade chord, but more than doubled its size after one revolution of the rotor. According to vortex models that approximate the measured data, the core-radius circulation was about 79 percent of the large-radius circulation, and the large-radius circulation was about 67 percent of the maximum bound circulation on the rotor blade. On average, about 53 percent of the maximum bound circulation resides within the vortex core during the first revolution of the rotor.

  1. Radial forearm free flap pharyngoesophageal reconstruction.

    Science.gov (United States)

    Azizzadeh, B; Yafai, S; Rawnsley, J D; Abemayor, E; Sercarz, J A; Calcaterra, T C; Berke, G S; Blackwell, K E

    2001-05-01

    This study evaluates the outcome of pharyngoesophageal reconstruction using radial forearm free flaps with regard to primary wound healing, speech, and swallowing in patients requiring laryngopharyngectomy. Retrospective review in the setting of a tertiary, referral, and academic center. Twenty patients underwent reconstruction of the pharyngoesophageal segment using fasciocutaneous radial forearm free flaps. All free flap transfers were successful. An oral diet was resumed in 85% of the patients after surgery. Postoperative pharyngocutaneous fistulas occurred in 4 patients (20%) with 3 resolving spontaneously. Distal strictures also occurred in 20% of the patients. Five patients who underwent tracheoesophageal puncture achieved useful speech. Advantages of radial forearm free flaps for microvascular pharyngoesophageal function include high flap reliability, limited donor site morbidity, larger vascular pedicle caliber, and the ability to achieve good quality tracheoesophageal speech. The swallowing outcome is similar to that achieved after jejunal flap pharyngoesophageal reconstruction. The main disadvantage of this technique relates to a moderately high incidence of pharyngocutaneous fistulas, which contributes to delayed oral intake in affected patients.

  2. Mastoid fascia kite flap for cryptotia correction.

    Science.gov (United States)

    Simon, François; Celerier, Charlotte; Garabedian, Erea-Noël; Denoyelle, Françoise

    2016-11-01

    Cryptotia is one of the most common malformations of the upper auricle with aesthetic and functional consequences, however there is no standard treatment. We present the surgical technique and results of a kite flap procedure which can be used in the different cryptotia subtypes. We reviewed all patients treated in our department from 2010 to 2015, using a mastoid fascia kite flap technique. The incision of this local flap follows the retro-auricular sulcus along the rim of the helix superiorly and drawing a skin paddle inferiorly. The mastoid fascia is exposed and a superiorly and posteriorly based flap is drawn and detached from the skull. Finally, the skin paddle is rotated and sutured between the superior helix and temporal skin creating the superior sulcus. The retro-auricular incision is closed directly inferiorly. Six patients (mean age 12) and seven ears were studied. One patient had bilateral cryptotia and only two had a normal contralateral ear. Mean follow-up was of 45 months. There was no skin necrosis, no complications reported and no revision surgery. We describe a reliable flap with a simple design and improved aesthetic result, as the thickness of the flap projects the helix well, the scar is entirely hidden in the retro-auricular sulcus and the direct suture induces a harmonious medialization of the inferior part of the ear and earlobe. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  3. Dorsal hand coverage with free serratus fascia flap

    DEFF Research Database (Denmark)

    Fotopoulos, Peter; Holmer, Per; Leicht, Pernille

    2003-01-01

    serratus fascia flap, the connective tissue over the serratus muscle, for dorsal hand coverage. The flap consists of thin and well-vascularized pliable tissue, with gliding properties excellent for covering exposed tendons. It is based on the branches of the thoracodorsal artery, which are raised...... in the flap, leaving the long thoracic nerve intact on the serratus muscle. Coverage of the flap with split-thickness skin graft is done immediately. The free serratus fascia flap is an ideal flap for dorsal hand coverage when the extensor tendons are exposed, especially because of low donor-site morbidity....

  4. Lower Extremity Reconstruction Using Vastus Lateralis Myocutaneous Flap versus Anterolateral Thigh Fasciocutaneous Flap

    Directory of Open Access Journals (Sweden)

    Min Jae Lee

    2012-07-01

    Full Text Available BackgroundThe anterolateral thigh (ALT perforator flap has become a popular option for treating soft tissue defects of lower extremity reconstruction and can be combined with a segment of the vastus lateralis muscle. We present a comparison of the use of the ALT fasciocutaneous (ALT-FC and myocutaneous flaps.MethodsWe retrospectively reviewed patients in whom free-tissue transfer was performed between 2005 and 2011 for the reconstruction of lower extremity soft-tissue defects. Twenty-four patients were divided into two groups: reconstruction using an ALT-FC flap (12 cases and reconstruction using a vastus lateralis myocutaneous (VL-MC flap (12 cases. Postoperative complications, functional results, cosmetic results, and donor-site morbidities were studied.ResultsComplete flap survival was 100% in both groups. A flap complication was noted in one case (marginal dehiscence of the ALT-FC group, and no complications were noted in the VL-MC group. In both groups, one case of partial skin graft loss occurred at the donor site, and debulking surgeries were needed for two cases. There were no significant differences in the mean scores for either functional or cosmetic outcomes in either group.ConclusionsThe VL-MC flap is able to fill occasional dead space and has comparable survival rates to ALT-FC with minimal donor-site morbidity. Additionally, the VL-MC flap is easily elevated without myocutaneous perforator injury.

  5. Lower Extremity Reconstruction Using Vastus Lateralis Myocutaneous Flap versus Anterolateral Thigh Fasciocutaneous Flap

    Directory of Open Access Journals (Sweden)

    Min Jae Lee

    2012-07-01

    Full Text Available Background The anterolateral thigh (ALT perforator flap has become a popular option fortreating soft tissue defects of lower extremity reconstruction and can be combined witha segment of the vastus lateralis muscle. We present a comparison of the use of the ALTfasciocutaneous (ALT-FC and myocutaneous flaps.Methods We retrospectively reviewed patients in whom free-tissue transfer was performedbetween 2005 and 2011 for the reconstruction of lower extremity soft-tissue defects. Twentyfourpatients were divided into two groups: reconstruction using an ALT-FC flap (12 cases andreconstruction using a vastus lateralis myocutaneous (VL-MC flap (12 cases. Postoperativecomplications, functional results, cosmetic results, and donor-site morbidities were studied.Results Complete flap survival was 100% in both groups. A flap complication was noted inone case (marginal dehiscence of the ALT-FC group, and no complications were noted in theVL-MC group. In both groups, one case of partial skin graft loss occurred at the donor site,and debulking surgeries were needed for two cases. There were no significant differences inthe mean scores for either functional or cosmetic outcomes in either group.Conclusions The VL-MC flap is able to fill occasional dead space and has comparable survivalrates to ALT-FC with minimal donor-site morbidity. Additionally, the VL-MC flap is easily elevatedwithout myocutaneous perforator injury.

  6. Rescue of Primary Incomplete Microkeratome Flap with Secondary Femtosecond Laser Flap in LASIK

    Directory of Open Access Journals (Sweden)

    E. A. Razgulyaeva

    2014-01-01

    Full Text Available For laser-assisted in situ keratomileusis (LASIK retreatments with a previous unsuccessful mechanical microkeratome-assisted surgery, some surgical protocols have been described as feasible, such as relifting of the flap or the creation of a new flap and even the change to a surface ablation procedure (photorefractive keratectomy (PRK. This case shows the use of femtosecond technology for the creation of a secondary flap to perform LASIK in a cornea with a primary incomplete flap obtained with a mechanical microkeratome. As we were unable to characterize the interface of the first partial lamellar cut, a thick flap was planned and created using a femtosecond laser platform. As the primary cut was very thick in the nasal quadrant, a piece of loose corneal tissue appeared during flap lifting which was fitted in its position and not removed. Despite this condition and considering the regularity of the new femtosecond laser cut, the treatment was uneventful. This case report shows the relevance of a detailed corneal analysis with an advanced imaging technique before performing a secondary flap in a cornea with a primary incomplete flap. The femtosecond laser technology seems to be an excellent tool to manage such cases successfully.

  7. The Internal Pudendal Artery Perforator Thigh Flap: A New Freestyle Pedicle Flap for the Ischial Region

    Directory of Open Access Journals (Sweden)

    Ichiro Hashimoto, MD

    2014-05-01

    Conclusions: The perforator vessels of the internal pudendal artery are very close to the ischial tuberosity. Blood flow to the flap is reliable when careful debridement of the pressure sore is performed. The iPap thigh flap is a new option for soft-tissue defects in the ischial region, including ischial pressure sores.

  8. The prepuce free flap in 10 patients : modifications in flap design and surgical technique

    NARCIS (Netherlands)

    Werker, Paul M N

    The prepuce free flap was used in 10 oral and oropharyngeal reconstructions. During the course of this study, various modifications took place. Residual penile skin necrosis and skin island necrosis early in the series led to modification of flap design. This solved the donor-site problem by placing

  9. The prepuce free flap in 10 patients : modifications in flap design and surgical technique

    NARCIS (Netherlands)

    Werker, Paul M N

    2002-01-01

    The prepuce free flap was used in 10 oral and oropharyngeal reconstructions. During the course of this study, various modifications took place. Residual penile skin necrosis and skin island necrosis early in the series led to modification of flap design. This solved the donor-site problem by placing

  10. Inlet Guide Vane Wakes Including Rotor Effects

    Science.gov (United States)

    Johnston, R. T.; Fleeter, S.

    2001-02-01

    Fundamental experiments are described directed at the investigation of forcing functions generated by an inlet guide vane (IGV) row, including interactions with the downstream rotor, for application to turbomachine forced response design systems. The experiments are performed in a high-speed research fan facility comprised of an IGV row upstream of a rotor. IGV-rotor axial spacing is variable, with the IGV row able to be indexed circumferentially, thereby allowing measurements to be made across several IGV wakes. With an IGV relative Mach number of 0.29, measurements include the IGV wake pressure and velocity fields for three IGV-rotor axial spacings. The decay characteristics of the IGV wakes are compared to the Majjigi and Gliebe empirical correlations. After Fourier decomposition, a vortical-potential gust splitting analysis is implemented to determine the vortical and potential harmonic wake gust forcing functions both upstream and downstream of the rotor. Higher harmonics of the vortical gust component of the IGV wakes are found to decay at a uniform rate due to viscous diffusion.

  11. Performance investigation of the S-Rotors

    Science.gov (United States)

    Bhayo, B. A.; Al-Kayiem, H. H.; Yahaya, N. Z.

    2015-12-01

    This paper presents and discusses results from an experimental investigation of three models of wind S-rotors. Models 1 is modified from conventional Savonius rotor with a single stage and zero offsets zero overlaps; model 2 is three blade single stage wind rotor; and model 3 is double stage conventional Savonius rotor. The three models were designed, fabricated and characterized in terms of their coefficient of performance and dynamic torque coefficient. A special open wind simulator was designed for the test. The optimum parameters for the models were based on previous studies. The results showed that the model 1, model 2 and model 3 has the maximum power coefficient of 0.26, 0.17, and 0.21 at the correspondence tip speed ratio (TSR) of 0.42, 0.39 and 0.46, respectively. Model 1 is further optimized in terms of the aspect ratio resulting in improved power coefficient by 24%. The maximum dynamic torque coefficient of model 1, model 2 and model 3 was found as 0.81, 0.56 and 0.67 at the correspondence minimum TSR of 0.28, 0.21 and 0.17, respectively. It was noted that the all three models have high torque coefficient because the models were tested at higher applied torque on the rotors.

  12. A bio-inspired study on tidal energy extraction with flexible flapping wings.

    Science.gov (United States)

    Liu, Wendi; Xiao, Qing; Cheng, Fai

    2013-09-01

    Previous research on the flexible structure of flapping wings has shown an improved propulsion performance in comparison to rigid wings. However, not much is known about this function in terms of power efficiency modification for flapping wing energy devices. In order to study the role of the flexible wing deformation in the hydrodynamics of flapping wing energy devices, we computationally model the two-dimensional flexible single and twin flapping wings in operation under the energy extraction conditions with a large Reynolds number of 106. The flexible motion for the present study is predetermined based on a priori structural result which is different from a passive flexibility solution. Four different models are investigated with additional potential local distortions near the leading and trailing edges. Our simulation results show that the flexible structure of a wing is beneficial to enhance power efficiency by increasing the peaks of lift force over a flapping cycle, and tuning the phase shift between force and velocity to a favourable trend. Moreover, the impact of wing flexibility on efficiency is more profound at a low nominal effective angle of attack (AoA). At a typical flapping frequency f * = 0.15 and nominal effective AoA of 10°, a flexible integrated wing generates 7.68% higher efficiency than a rigid wing. An even higher increase, around six times that of a rigid wing, is achievable if the nominal effective AoA is reduced to zero degrees at feathering condition. This is very attractive for a semi-actuated flapping energy system, where energy input is needed to activate the pitching motion. The results from our dual-wing study found that a parallel twin-wing device can produce more power compared to a single wing due to the strong flow interaction between the two wings.

  13. A comparative molecular dynamics study on BACE1 and BACE2 flap flexibility.

    Science.gov (United States)

    Kumalo, H M; Soliman, Mahmoud E

    2016-10-01

    Beta-amyloid precursor protein cleavage enzyme1 (BACE1) and beta-amyloid precursor protein cleavage enzyme2 (BACE2), members of aspartyl protease family, are close homologs and have high similarity in their protein crystal structures. However, their enzymatic properties are different, which leads to different clinical outcomes. In this study, we performed sequence analysis and all-atom molecular dynamic (MD) simulations for both enzymes in their ligand-free states in order to compare their dynamical flap behaviors. This is to enhance our understanding of the relationship between sequence, structure and the dynamics of this protein family. Sequence analysis shows that in BACE1 and BACE2, most of the ligand-binding sites are conserved, indicative of their enzymatic property as aspartyl protease members. The other conserved residues are more or less unsystematically localized throughout the structure. Herein, we proposed and applied different combined parameters to define the asymmetric flap motion; the distance, d1, between the flap tip and the flexible region; the dihedral angle, φ, to account for the twisting motion and the TriCα angle, θ2 and θ1. All four combined parameters were found to appropriately define the observed "twisting" motion during the flaps different conformational states. Additional analysis of the parameters indicated that the flaps can exist in an ensemble of conformations, i.e. closed, semi-open and open conformations for both systems. However, the behavior of the flap tips during simulations is different between BACE1 and BACE2. The BACE1 active site cavity is more spacious as compared to that of BACE2. The analysis of 10S loop and 113S loop showed a similar trend to that of flaps, with the BACE1 loops being more flexible and less stable than those of BACE2. We believe that the results, methods and perspectives highlighted in this report would assist researchers in the discovery of BACE inhibitors as potential Alzheimer's disease therapies.

  14. Versatility of the Anterolateral Thigh Free Flap: The Four Seasons Flap

    Science.gov (United States)

    Di Candia, Michele; Lie, Kwok; Kumiponjera, Devor; Simcock, Jeremy; Cormack, George C.; Malata, Charles M.

    2012-01-01

    Presented at the following academic meetings: ○ 56th Meeting of the Italian Society of Plastic, Reconstructive and Aesthetic Surgery (SICPRE) Fasano (Brindisi), Italy, September 26-29, 2007 ○ 42nd Meeting of the European Society for Surgical Research (ESSR), Warsaw, Poland, May 21-24, 2008 ○ Winter Meeting, British Association of Plastic, Reconstructive and Aesthetic Surgeons, (BAPRAS) London, December 1-3, 2009 Background: The anterolateral free flap has become increasingly popular at our institution year on year. We decided to review our experience with this flap and study the reasons for this trend. Methods: A retrospective review of all anterolateral thigh free flaps performed at Addenbrooke's University Hospital from the available charts was carried out. This chart review included patients' demographics, indications, flap size, recipient vessels used, ischemia time, flap, and donor site outcomes. All flap perforator vessels were located preoperatively using a handheld Doppler ultrasound probe. Results: From October 1999 to December 2008, 55 anterolateral thigh flaps were performed in 55 patients to reconstruct a variety of soft-tissue defects (upper and lower limbs, chest wall, skull base, head and neck). Flap size ranged 12 to 35 cm in length and 4 to 11 cm in width. During flap elevation, the main supply to the flap was found to be a direct septocutaneous perforator in 41% (n = 23) of the cases as opposed to a musculocutaneous perforator, which was found in 59% (n = 32). The mean ischemia time was 82 minutes (range, 62-103). The overall flap success rate was 100%. Two flaps were successfully salvaged after reexploration for venous congestion. The donor site morbidity was minimal. The mean follow-up time was 18 months (range, 2-48). Discussion and Conclusion: The anterolateral thigh free flap was found to be a very reliable flap (100% success) across a wide range of clinical indications. It facilitates microvascular anastomoses as evidenced by the short

  15. [Flap techniques in secondary alveoloplasty: a comparison between two types of flap].

    Science.gov (United States)

    Hugentobler, M; Dojcinovic, I; Richter, M

    2006-06-01

    The aim of this study was to compare two surgical soft tissue coverage techniques of secondary alveolar grafts in cleft lip and palate patients: the gingival mucoperiostal slidind flap and the mucosal rotation flap. Fifty-two secondary alveolar bone grafts were retrospectively included in the study. Four clinical parameters were evaluated: post-operative dehiscence, oro-nasal fistula relapse, canine eruption through the graft and postoperative secondary periodontal procedures. Gingival mucoperiostal flaps had less postoperative dehiscence, more fistula relapse and needed less secondary periodontal procedures. Based on this study and on literature data, gingival mucoperiostal flap provides better quality of soft tissue coverage. Flap design doesn't influence canine eruption. Bone graft complications are increased with poor oral hygiene, if canine eruption occurred before surgery and in older patients.

  16. Functional results of microvascular reconstruction after hemiglossectomy: free anterolateral thigh flap versus free forearm flap.

    Science.gov (United States)

    Tarsitano, A; Vietti, M V; Cipriani, R; Marchetti, C

    2013-12-01

    The aim of the present study is to assess functional outcomes after hemiglossectomy and microvascular reconstruction. Twenty-six patients underwent primary tongue microvascular reconstruction after hemiglossectomy. Twelve patients were reconstructed using a free radial forearm flap and 14 with an anterolateral thigh flap. Speech intelligibility, swallowing capacity and quality of life scores were assessed. Factors such as tumour extension, surgical resection and adjuvant radiotherapy appeared to be fundamental to predict post-treatment functional outcomes. The data obtained in the present study indicate that swallowing capacity after hemiglossectomy is better when an anterolateral thigh flap is used. No significant differences were seen for speech intelligibility or quality of life between free radial forearm flap and anterolateral thigh flap.

  17. First dorsal metacarpal artery flap for thumb reconstruction: a retrospective clinical study

    Science.gov (United States)

    Muyldermans, Thomas

    2009-01-01

    patient. The mean Kapandji score of the reconstructed thumb was 7.43 over 10. Using the SF-36, mean physical health of the patients scored 66.88% and mean mental health scored 70.55%. Disturbing pain and paresthesia of the flap are exceptional. The static 2-PD is more than 10 mm, and is clinically over the limit. Cortical reorientation was incomplete in all but one patient. Touch on thumb is felt on the dorsum of the index finger; however, sensation is not disturbing or interfering with the patient’s activities. Foucher described the technique débranchement–rébranchement in order to improve this problem. The postoperative total amount of motion of the reconstructed thumb was very good. The results demonstrated that the FDMCA flap has a constant anatomy and easy dissection. It has a low donor site morbidity if FTSG is used. It also shows good functional and aesthetic results. Therefore, the FDMCA flap is a first treatment of choice for defects of the proximal phalanx and proximal part of the distal phalanx of the thumb. PMID:19340522

  18. Aerodynamic flight performance in flap-gliding birds and bats.

    Science.gov (United States)

    Muijres, Florian T; Henningsson, Per; Stuiver, Melanie; Hedenström, Anders

    2012-08-07

    Many birds use a flight mode called undulating or flap-gliding flight, where they alternate between flapping and gliding phases, while only a few bats make use of such a flight mode. Among birds, flap-gliding is commonly used by medium to large species, where it is regarded to have a lower energetic cost than continuously flapping flight. Here, we introduce a novel model for estimating the energetic flight economy of flap-gliding animals, by determining the lift-to-drag ratio for flap-gliding based on empirical lift-to-drag ratio estimates for continuous flapping flight and for continuous gliding flight, respectively. We apply the model to flight performance data of the common swift (Apus apus) and of the lesser long-nosed bat (Leptonycteris yerbabuenae). The common swift is a typical flap-glider while-to the best of our knowledge-the lesser long-nosed bat does not use flap-gliding. The results show that, according to the model, the flap-gliding common swift saves up to 15% energy compared to a continuous flapping swift, and that this is primarily due to the exceptionally high lift-to-drag ratio in gliding flight relative to that in flapping flight for common swifts. The lesser long-nosed bat, on the other hand, seems not to be able to reduce energetic costs by flap-gliding. The difference in relative costs of flap-gliding flight between the common swift and the lesser long-nosed bat can be explained by differences in morphology, flight style and wake dynamics. The model presented here proves to be a valuable tool for estimating energetic flight economy in flap-gliding animals. The results show that flap-gliding flight that is naturally used by common swifts is indeed the most economic one of the two flight modes, while this is not the case for the non-flap-gliding lesser long-nosed bat.

  19. Lateral thoracic artery perforator (LTAP) flap in partial breast reconstruction.

    Science.gov (United States)

    McCulley, Stephen J; Schaverien, Mark V; Tan, Veronique K M; Macmillan, R Douglas

    2015-05-01

    Partial breast reconstruction using pedicled perforator flaps from the thoracodorsal (TDAP) and lateral intercostal arteries (LICAP) is well described. The article introduces the lateral thoracic artery perforator (LTAP) flap as an additional valuable option from the lateral chest wall and reports clinical experience and outcomes. The anatomy of the LTAP flap is reviewed and the results of a consecutive series are reported. In a series of 75 consecutive cases of lateral chest wall perforator flaps used for reconstruction of partial breast defects, 12 (17%) were raised as pure LTAP flaps, and a further 19 (27%) as combined LTAP/LICAP flaps. The LTAP was therefore used in 44% of flaps overall. One LTAP flap (delayed case) had early venous compromise that settled spontaneously. The LTAP flap is a reliable option for partial breast reconstruction from the lateral chest wall, particularly in the immediate setting. It allows comparable flap size to be harvested compared to LICAP flaps. The LTAP flap can be raised on its own pedicle allowing greater mobilization or it can be incorporated into the more commonly used LICAP flap to augment perfusion. Copyright © 2015 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.

  20. RESEARCH ON KNOWLEDGE-BASED CAPP SYSTEM FOR ROTOR FORGING

    Institute of Scientific and Technical Information of China (English)

    Wang Leigang; Deng Dongrnei; Liu Zhubai

    2000-01-01

    Guided by developing forging technology theory,designing rules on rotor forging process are summed up.Knowledge-based CAPP system for rotor forging is created.The system gives a rational and optimum process.

  1. Estimation of dynamic rotor loads for the rotor systems research aircraft: Methodology development and validation

    Science.gov (United States)

    Duval, R. W.; Bahrami, M.

    1985-01-01

    The Rotor Systems Research Aircraft uses load cells to isolate the rotor/transmission systm from the fuselage. A mathematical model relating applied rotor loads and inertial loads of the rotor/transmission system to the load cell response is required to allow the load cells to be used to estimate rotor loads from flight data. Such a model is derived analytically by applying a force and moment balance to the isolated rotor/transmission system. The model is tested by comparing its estimated values of applied rotor loads with measured values obtained from a ground based shake test. Discrepancies in the comparison are used to isolate sources of unmodeled external loads. Once the structure of the mathematical model has been validated by comparison with experimental data, the parameters must be identified. Since the parameters may vary with flight condition it is desirable to identify the parameters directly from the flight data. A Maximum Likelihood identification algorithm is derived for this purpose and tested using a computer simulation of load cell data. The identification is found to converge within 10 samples. The rapid convergence facilitates tracking of time varying parameters of the load cell model in flight.

  2. STABILITY OF ROTOR-BEARING SYSTEMS

    Directory of Open Access Journals (Sweden)

    Uğur YÜCEL

    2003-03-01

    Full Text Available In various industrial applications there is a need for higher speed, yet reliably operating rotating machinery. A key factor in achieving this type of machinery continues to be the ability to accurately predict the dynamic response and stability of a rotor-bearing system. This paper introduces and explains the nature of rotordynamic phenomena from comparatively simple analytic models. Starting with the most simple rotor model that is supported in two rigid bearings at its ends, the more realistic and more involved cases are considered by incorporating the effects of flexible bearings. Knowledge of these phenomena is fundamental to an understanding of the behavior of complex models, which corresponds to the real rotors of turbomachines.

  3. Diagnosis of wind turbine rotor system

    DEFF Research Database (Denmark)

    Niemann, Hans Henrik; Mirzaei, Mahmood; Henriksen, Lars Christian

    2016-01-01

    This paper describes a model free method for monitoring and fault diagnosis of the elements in a rotor system for a wind turbine. The diagnosis as well as the monitoring is done without using any model of the wind turbine and the applied controller or a description of the wind profile. The method...... is based on available standard sensors on wind turbines. The method can be used both on-line as well as off-line. Faults or changes in the rotor system will result in asymmetries, which can be monitored and diagnosed. This can be done by using the multi-blade coordinate transformation. Changes in the rotor...... system that can be diagnosed and monitored are: actuator faults, sensor faults and internal blade changes as e.g. change in mass of a blade....

  4. Eigenfrequency sensitivity analysis of flexible rotors

    Directory of Open Access Journals (Sweden)

    Šašek J.

    2007-10-01

    Full Text Available This paper deals with sensitivity analysis of eigenfrequencies from the viewpoint of design parameters. The sensitivity analysis is applied to a rotor which consists of a shaft and a disk. The design parameters of sensitivity analysis are the disk radius and the disk width. The shaft is modeled as a 1D continuum using shaft finite elements. The disks of rotating systems are commonly modeled as rigid bodies. The presented approach to the disk modeling is based on a 3D flexible continuum discretized using hexahedral finite elements. The both components of the rotor are connected together by special proposed couplings. The whole rotor is modeled in rotating coordinate system with considering rotation influences (gyroscopic and dynamics stiffness matrices.

  5. Analysis on structural characteristics of rotors in twin-rotor cylinder-embedded piston engine

    Institute of Scientific and Technical Information of China (English)

    陈虎; 潘存云; 徐海军; 邓豪; 韩晨

    2014-01-01

    Twin-rotor cylinder-embedded piston engine is proposed for dealing with the sealing problems of rotors in twin-rotor piston engine where the existent mature sealing technologies for traditional reciprocating engine can be applied. The quantity and forms of its sealing surfaces are reduced and simplified, and what’s more, the advantages of twin-rotor piston engine are inherited, such as high power density and no valve mechanism. Given the motion law of two rotors, its kinematic model is established, and the general expression for some parameters related to engine performance, such as the trajectory, displacement, velocity and acceleration of the piston and centroid trajectory, angular displacement, velocity and acceleration of the rod are presented. By selecting different variation patterns of relative angle of two rotors, the relevant variables are compared. It can be concluded that by designing the relative angle function of two rotors, the volume variation of working chamber can be changed. However, a comprehensive consideration for friction and vibration is necessary because velocity and acceleration are quite different in the different functions, the swing magnitude of rod is proportional to link ratioλ, and the position of rod swing center is controlled by eccentricitye. In order to reduce the lateral force, a smaller value ofλshould be selected in the case of the structure, and the value ofe should be near 0.95. There is no relationship between the piston stroke and the variation process of relative angle of two rotors, the former is only proportional to the amplitude of relative angle of two rotors.

  6. Morbidity after flap reconstruction of hypopharyngeal defects.

    Science.gov (United States)

    Clark, Jonathan R; Gilbert, Ralph; Irish, Jonathan; Brown, Dale; Neligan, Peter; Gullane, Patrick J

    2006-02-01

    Laryngopharyngeal reconstruction continues to challenge in terms of operative morbidity and optimal functional results. The primary aim of this study is to determine whether complications can be predicted on the basis of reconstruction in patients undergoing pharyngectomy for tumors involving the hypopharynx. In addition, we detail a reconstructive algorithm for management of partial and total laryngopharyngectomy defects. A retrospective review was performed of 153 patients undergoing flap reconstruction for 85 partial and 68 circumferential pharyngectomies at a single institution over a 10-year period. There were 118 males and 35 females, the median age was 62 years, and mean follow up was 3.1 years. Pharyngectomy was performed for recurrence after radiotherapy in 80 patients and as primary surgery in 73. Free flap reconstruction was used in 42%, with 30 jejunal, 15 radial forearm, 11 anterolateral thigh, five rectus abdominis, and three gastro-omental flaps. Gastric transposition and pectoralis major pedicle flap was used in 14% and 44% of patients, respectively. Morbidity was analyzed according to extent of defect, regional versus free flap, enteric versus fasciocutaneous free flap reconstruction, and the effect of laparotomy. The total operative morbidity and mortality rate was 71% and 3%, respectively. The most common complications were hypocalcemia in 45%, pharyngocutaneous fistula in 33%, and wound complications in 25%. The late complication and stricture rate was 26% and 15%, respectively. On univariate analysis, circumferential defects were associated with increased total (P=.046) and flap-related morbidity (P=.037), hypocalcemia (Pspeech was the method of voice restoration in 44% of patients. Oral diet was achieved in 93% of patients; however, 16% required gastrostomy tube feeds for either total or supplemental nutrition. The operative morbidity associated with pharyngeal reconstruction is substantial in terms of early and late complications. We were

  7. Comprehensive Modeling and Analysis of Rotorcraft Variable Speed Propulsion System With Coupled Engine/Transmission/Rotor Dynamics

    Science.gov (United States)

    DeSmidt, Hans A.; Smith, Edward C.; Bill, Robert C.; Wang, Kon-Well

    2013-01-01

    This project develops comprehensive modeling and simulation tools for analysis of variable rotor speed helicopter propulsion system dynamics. The Comprehensive Variable-Speed Rotorcraft Propulsion Modeling (CVSRPM) tool developed in this research is used to investigate coupled rotor/engine/fuel control/gearbox/shaft/clutch/flight control system dynamic interactions for several variable rotor speed mission scenarios. In this investigation, a prototypical two-speed Dual-Clutch Transmission (DCT) is proposed and designed to achieve 50 percent rotor speed variation. The comprehensive modeling tool developed in this study is utilized to analyze the two-speed shift response of both a conventional single rotor helicopter and a tiltrotor drive system. In the tiltrotor system, both a Parallel Shift Control (PSC) strategy and a Sequential Shift Control (SSC) strategy for constant and variable forward speed mission profiles are analyzed. Under the PSC strategy, selecting clutch shift-rate results in a design tradeoff between transient engine surge margins and clutch frictional power dissipation. In the case of SSC, clutch power dissipation is drastically reduced in exchange for the necessity to disengage one engine at a time which requires a multi-DCT drive system topology. In addition to comprehensive simulations, several sections are dedicated to detailed analysis of driveline subsystem components under variable speed operation. In particular an aeroelastic simulation of a stiff in-plane rotor using nonlinear quasi-steady blade element theory was conducted to investigate variable speed rotor dynamics. It was found that 2/rev and 4/rev flap and lag vibrations were significant during resonance crossings with 4/rev lagwise loads being directly transferred into drive-system torque disturbances. To capture the clutch engagement dynamics, a nonlinear stick-slip clutch torque model is developed. Also, a transient gas-turbine engine model based on first principles mean

  8. A Study of Coaxial Rotor Performance and Flow Field Characteristics

    Science.gov (United States)

    2016-01-22

    A Study of Coaxial Rotor Performance and Flow Field Characteristics Natasha L. Barbely Aerospace Engineer NASA Ames Research Center Moffett Field...The pressure field generated by the two airfoils aided our interpretation of the more complex coaxial rotor system flow field. The pressure fields...velocity (ft/sec) Z vertical distance between rotors (ft) αS pitch angle (deg), negative pitch down κint coaxial rotor induced power interference

  9. On aerodynamic design of the Savonius windmill rotor

    Science.gov (United States)

    Mojola, O. O.

    This paper examines under field conditions the performance characteristics of the Savonius windmill rotor. Test data were collected on the speed, torque and power of the rotor at a large number of wind speeds for each of seven values of the rotor overlap ratio. Field testing procedures are critically appraised and a unified approach is suggested. The performance data of the Savonius rotor are also fully discussed and design criteria established.

  10. Rotor Performance Enhancement Using Slats on the Inner Part of a 10MW Rotor

    DEFF Research Database (Denmark)

    Gaunaa, Mac; Zahle, Frederik; Sørensen, Niels N.

    2013-01-01

    The present work continues the investigations of using slats on the inner parts of wind turbine rotors by using an updated version of the 2D CFD based airfoil/slat design tool earlier used by the authors in combination with the rotor design methods from [8] to design slats for 0:1 > r=R > 0......, thus allowing for a much broader design space than in the previous works where only the position, size and additional camber of the slat airfoil could be adjusted. The aerodynamic performance of a slatted rotor is for the first time evaluated using 3D CFD in this work, and the results are compared...

  11. Rotor Performance Enhancement Using Slats on the Inner Part of a 10MW Rotor

    DEFF Research Database (Denmark)

    The present work continues the investigations of using slats on the inner parts of wind turbine rotors by using an updated version of the 2D CFD based airfoil/slat design tool earlier used by the authors in combination with the rotor design methods from [8] to design slats for 0:1 > r=R > 0......, thus allowing for a much broader design space than in the previous works where only the position, size and additional camber of the slat airfoil could be adjusted. The aerodynamic performance of a slatted rotor is for the first time evaluated using 3D CFD in this work, and the results are compared...

  12. Microsurgical free flap reconstructions of the head and neck region: Shanghai experience of 34 years and 4640 flaps.

    Science.gov (United States)

    Zhang, C; Sun, J; Zhu, H; Xu, L; Ji, T; He, Y; Yang, W; Hu, Y; Yang, X; Zhang, Z

    2015-06-01

    This study represents the surgical experience of 4481 microvascular free flap cases performed at the authors' institution in China, between 1979 and 2013. Four thousand four hundred and eighty-one patients underwent reconstruction with 4640 flaps: 56% radial forearm flaps, 8% iliac crest flaps, 13% fibula flaps, 10% anterolateral thigh flaps, and other flaps. In the overwhelming majority of cases, the flap transfer was required following tumour resection (97.5%). Three hundred and twenty minor complications (6.9%) occurred. One hundred and eighteen major complications (2.5%) were encountered: 114 cases of failure (2.4%) and four deaths. Among the 118 cases with major complications, 26 - 22.0% - had received radiotherapy; this proportion was higher than the 6.9% in the minor complications group and 8.1% in the non-intervention group. Venous thrombosis was the most common complication at the recipient site and was the main cause of flap failure. When a compromised flap is identified, surgical re-exploration should not be delayed. This study confirms that free flaps are reliable in achieving successful reconstruction in the head and neck region; however this technique requires extensive clinical experience. Owing to the large number of flap options, microsurgeons should always pay attention to the details of the different surgical defects and choose the most appropriate flap.

  13. Intraoperative flap complications in lasik surgery performed by ophthalmology residents

    Directory of Open Access Journals (Sweden)

    Lorena Romero-Diaz-de-Leon

    2016-01-01

    Conclusion: Flap-related complications are common intraoperative event during LASIK surgery performed by in-training ophthalmologists. Keratometries and surgeon's first procedure represent a higher probability for flap related complications than some other biometric parameters of patient's eye.

  14. Anterior Palatal Island Advancement Flap for Bone Graft Coverage ...

    African Journals Online (AJOL)

    2015 Journal of Surgical Technique and Case Report | Published by Wolters Kluwer - Medknow. 42. Anterior Palatal Island ... prosthodontic treatments should have ideal characteristics, as .... are rotated palatal flap and palatal advanced flap.

  15. Modified cup flap for volar oblique fingertip amputations

    Directory of Open Access Journals (Sweden)

    Ahmadli, A.

    2016-02-01

    Full Text Available We describe a modified volar “V-Y cup” flap for volar fingertip defects that do not exceed more than half of the distal phalanx for better aesthetic and functional outcome. In seven cases out of eight, the flap was elevated with a subdermal pedicle, whereas in one case, the flap was elevated as an island on the bilateral neurovascular bundle. The fingertips have been evaluated for sensibility using standard tests, hook nail deformity and patient satisfaction. Seven flaps have survived completely. The flap with skeletonized bilateral digital neurovascular bundle has shown signs of venous insufficiency on the 5 postoperative day with consecutive necrosis. Suturing the distal edges of the flap in a “cupping” fashion provided a normal pulp contour. The modified flap can be used for defects as mentioned above. Subdermally dissected pedicle-based flap is safe and easy to elevate. The aesthetic and functional outcomes have been reported to be satisfactory.

  16. APPLICATION OF MECHANIZED MATHEMATICS TO ROTOR DYNAMICS

    Institute of Scientific and Technical Information of China (English)

    胡超; 王岩; 王立国; 黄文虎

    2002-01-01

    Based on the mechanized mathematics and WU Wen-tsun elimination method,using oil film forces of short-bearing model and Muszynska's dynamic model, the dynamical behavior of rotor-bearing system and its stability of motion are investigated. As example,the concept of Wu characteristic set and Maple software, whirl parameters of short- bearing model, which is usually solved by the numerical method, are analyzed. At the same time,stability of zero solution of Jeffcott rotor whirl equation and stability of self-excited vibration are studied. The conditions of stable motion are obtained by using theory of nonlinear vibration.

  17. Fine tuning of molecular rotor function in photochemical molecular switches

    NARCIS (Netherlands)

    ter Wiel, Matthijs K. J.; Feringa, Ben L.

    2009-01-01

    Molecular switches are used as scaffolds for the construction of controlled molecular rotors. The internal position of the switching entity in the molecule controls the dynamic behaviour of the rotor moiety in the molecule. Six new molecular motors with o-xylyl rotor moieties were prepared on the ba

  18. 14 CFR 23.1461 - Equipment containing high energy rotors.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Equipment containing high energy rotors. 23... Equipment Miscellaneous Equipment § 23.1461 Equipment containing high energy rotors. (a) Equipment, such as Auxiliary Power Units (APU) and constant speed drive units, containing high energy rotors must...

  19. Helicopter Rotor Blade Monitoring using Autonomous Wireless Sensor Network

    NARCIS (Netherlands)

    Sanchez Ramirez, Andrea; Loendersloot, Richard; Tinga, Tiedo; Basu, B.

    2013-01-01

    The advancement on Wireless Sensor Networks for vibration monitoring presents important possibilities for helicopter rotor health and usage monitoring. While main rotor blades account for the main source of lift for helicopters, rotor induced vibration establishes an important source for understandi

  20. 14 CFR 33.92 - Rotor locking tests.

    Science.gov (United States)

    2010-01-01

    ... Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES Block Tests; Turbine Aircraft Engines § 33.92 Rotor locking tests. If continued rotation is prevented by a means to lock the rotor(s), the engine must be subjected to a test that...

  1. On the Classification of Universal Rotor-Routers

    CERN Document Server

    He, Xiaoyu

    2011-01-01

    The combinatorial theory of rotor-routers has connections with problems of statistical mechanics, graph theory, chaos theory, and computer science. A rotor-router network defines a deterministic walk on a digraph G in which a particle walks from a source vertex until it reaches one of several target vertices. Motivated by recent results due to Giacaglia et al., we study rotor-router networks in which all non-target vertices have the same type. A rotor type r is universal if every hitting sequence can be achieved by a homogeneous rotor-router network consisting entirely of rotors of type r. We give a conjecture that completely classifies universal rotor types. Then, this problem is simplified by a theorem we call the Reduction Theorem that allows us to consider only two-state rotors. A rotor-router network called the compressor, because it tends to shorten rotor periods, is introduced along with an associated algorithm that determines the universality of almost all rotors. New rotor classes, including boppy ro...

  2. A Recurrent Rotor-Router Configuration in Z^3

    CERN Document Server

    A, Tulasi Ram Reddy

    2010-01-01

    Rotor Router models were first introduced by James Propp in 2002. A recurrent Rotor configuration is the one in which every state is visited infinitely often. In this project we investigated whether there is a recurrent Rotor configuration in Z^d (d>2).

  3. 14 CFR 29.547 - Main and tail rotor structure.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Main and tail rotor structure. 29.547 Section 29.547 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION... Requirements § 29.547 Main and tail rotor structure. (a) A rotor is an assembly of rotating components, which...

  4. Acute Deep Hand Burns Covered by a Pocket Flap-Graft

    Science.gov (United States)

    Pradier, Jean-Philippe; Oberlin, Christophe; Bey, Eric

    2007-01-01

    Objective: We evaluated the long-term outcome of the “pocket flap-graft” technique, used to cover acute deep burns of the dorsum of the hand, and analyzed surgical alternatives. Methods: This was a 6-year, retrospective study of 8 patients with extensive burns and 1 patient with a single burn (11 hands in all) treated by defatted abdominal wall pockets. We studied the medical records of the patients, and conducted a follow-up examination. Results: All hands had fourth-degree thermal burns caused by flames, with exposure of tendons, bones, and joints, and poor functional prognosis. One third of patients had multiple injuries. Burns affected an average of 36% of the hand surface, and mean coverage was 92.8 cm2. One patient died. The 8 others were seen at 30-month follow-up: the skin quality of the flap was found to be good in 55% of the cases, the score on the Vancouver Scar Scale was 2.4, the Kapandji score was 4.5, and total active motion was 37% of that of a normal hand. Hand function was limited in only 2 cases, 8 patients were able to drive, and 3 patients had gone back to work. Conclusion: The pocket flap-graft allows preservation of hand function following severe burns, when local or free flaps are impossible to perform. Debulking of the flap at the time of elevation limits the need for secondary procedures. PMID:17268577

  5. Reconstruction of Postburn Contracture of the Forefoot Using the Anterolateral Thigh Flap.

    Science.gov (United States)

    Lee, Sang Hyun; An, Sung Jin; Kim, Nu Ri; Kim, Um Ji; Kim, Jeung Il

    2016-12-01

    Severe forefoot deformities, particularly those involving the dorsum of the foot, cause inconvenience in daily activities of living including moderate pain on the dorsal aspect of the contracted foot while walking and difficulty in wearing nonsupportive shoes due to toe contractures. This paper presents clinical results of reconstruction of severe forefoot deformity using the anterolateral thigh (ALT) free flap. Severe forefoot deformities were reconstructed using ALT flaps in 7 patients (8 cases) between March 2012 and December 2015. The mean contracture duration was 28.6 years. All the flaps survived completely. The size of the flaps ranged from 8 cm × 5 cm to 19 cm × 8 cm. The mean follow-up period was 10 months (range, 7 to 15 months). There was no specific complication at both the recipient and donor sites. There was one case where the toe contracture could not be completely treated after surgery. All of the patients were able to wear shoes and walk without pain. Also, the patients were highly satisfied with cosmetic results. The ALT flap may be considered ideal for the treatment of severe forefoot deformity.

  6. The isolated perfused human skin flap model: A missing link in skin penetration studies?

    Science.gov (United States)

    Ternullo, Selenia; de Weerd, Louis; Flaten, Gøril Eide; Holsæter, Ann Mari; Škalko-Basnet, Nataša

    2017-01-01

    Development of effective (trans)dermal drug delivery systems requires reliable skin models to evaluate skin drug penetration. The isolated perfused human skin flap remains metabolically active tissue for up to 6h during in vitro perfusion. We introduce the isolated perfused human skin flap as a close-to-in vivo skin penetration model. To validate the model's ability to evaluate skin drug penetration the solutions of a hydrophilic (calcein) and a lipophilic (rhodamine) fluorescence marker were applied. The skin flaps were perfused with modified Krebs-Henseleit buffer (pH7.4). Infrared technology was used to monitor perfusion and to select a well-perfused skin area for administration of the markers. Flap perfusion and physiological parameters were maintained constant during the 6h experiments and the amount of markers in the perfusate was determined. Calcein was detected in the perfusate, whereas rhodamine was not detectable. Confocal images of skin cross-sections shoved that calcein was uniformly distributed through the skin, whereas rhodamine accumulated in the stratum corneum. For comparison, the penetration of both markers was evaluated on ex vivo human skin, pig skin and cellophane membrane. The proposed perfused flap model enabled us to distinguish between the penetrations of the two markers and could be a promising close-to-in vivo tool in skin penetration studies and optimization of formulations destined for skin administration.

  7. Flow field of flexible flapping wings

    Science.gov (United States)

    Sallstrom, Erik

    The agility and maneuverability of natural fliers would be desirable to incorporate into engineered micro air vehicles (MAVs). However, there is still much for engineers to learn about flapping flight in order to understand how such vehicles can be built for efficient flying. The goal of this study is to develop a methodology for capturing high quality flow field data around flexible flapping wings in a hover environment and to interpret it to gain a better understanding of how aerodynamic forces are generated. The flow field data was captured using particle image velocimetry (PIV) and required that measurements be taken around a repeatable flapping motion to obtain phase-averaged data that could be studied throughout the flapping cycle. Therefore, the study includes the development of flapping devices with a simple repeatable single degree of freedom flapping motion. The acquired flow field data has been examined qualitatively and quantitatively to investigate the mechanisms behind force production in hovering flight and to relate it to observations in previous research. Specifically, the flow fields have been investigated around a rigid wing and several carbon fiber reinforced flexible membrane wings. Throughout the whole study the wings were actuated with either a sinusoidal or a semi-linear flapping motion. The semi-linear flapping motion holds the commanded angular velocity nearly constant through half of each half-stroke while the sinusoidal motion is always either accelerating or decelerating. The flow fields were investigated by examining vorticity and vortex structures, using the Q criterion as the definition for the latter, in two and three dimensions. The measurements were combined with wing deflection measurements to demonstrate some of the key links in how the fluid-structure interactions generated aerodynamic forces. The flow fields were also used to calculate the forces generated by the flapping wings using momentum balance methods which yielded

  8. 14 CFR 25.1511 - Flap extended speed.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Flap extended speed. 25.1511 Section 25... Limitations § 25.1511 Flap extended speed. The established flap extended speed V FE must be established so that it does not exceed the design flap speed V F chosen under §§ 25.335(e) and 25.345, for...

  9. Paramedian forehead flap thinning using a flexible razor blade.

    Science.gov (United States)

    Justiniano, Hilda; Edwards, Julia; Eisen, Daniel B

    2009-03-15

    Paramedian forehead flaps are sometimes required to resurface large or deep nasal defects. The flap often needs to be thinned to match the contour of the surrounding skin at the recipient site. We describe a technique to thin the distal potion of the paramedian forehead flap using a flexible razor blade, the Dermablade. Once familiar with it, this same technique may be applied to thin other interpolation flaps.

  10. The aerodynamic and structural study of flapping wing vehicles

    OpenAIRE

    2013-01-01

    This thesis reports on the aerodynamic and structural study carried out on flapping wings and flapping vehicles. Theoretical and experimental investigation of aerodynamic forces acting on flapping wings in simple harmonic oscillations is undertaken in order to help conduct and optimize the aerodynamic and structural design of flapping wing vehicles. The research is focused on the large scale ornithopter design of similar size and configuration to a hang glider. By means of Theodorsen’s th...

  11. "A Free thenar flap – A case report"

    OpenAIRE

    Chow Shew; Fung Boris KK; Garg Rajesh; Ip Wing

    2007-01-01

    Abstract We present a case report of a free thenar flap surgery done for a volar right hand middle finger, distal and middle phalanx degloving injury. A free thenar flap is a fasciocutaneous sensate flap supplied by a constant branch of the superficial radial artery and its variable nerve supply. It has a distinct advantage of low donor site morbidity, better cosmesis and texture of the flap. No immobilization is required postop. The donor site can be closed primiarily.

  12. The forked flap repair for hypospadias

    Directory of Open Access Journals (Sweden)

    Anil Chadha

    2012-01-01

    Full Text Available Context: Despite the abundance of techniques for the repair of Hypospadias, its problems still persist and a satisfactory design to correct the penile curvature with the formation of neourethra from the native urethral tissue or genital or extragenital tissues, with minimal postoperative complications has yet to evolve. Aim: Persisting with such an endeavor, a new technique for the repair of distal and midpenile hypospadias is described. Materials and Methods: The study has been done in 70 cases over the past 11 years. The "Forked-Flap" repair is a single stage method for the repair of such Hypospadias with chordee. It takes advantage of the rich vascular communication at the corona and capitalizes on the established reliability of the meatal based flip-flap. The repair achieves straightening of the curvature of the penis by complete excision of chordee tissue from the ventral surface of the penis beneath the urethral plate. The urethra is reconstructed using the native plate with forked flap extensions and genital tissue relying on the concept of meatal based flaps. Water proofing by dartos tissue and reinforcement by Nesbit′s prepucial tissue transfer completes the one stage procedure. Statistical Analysis: An analysis of 70 cases of this single stage technique of repair of penile hypospadias with chordee, operated at 3 to 5 years of age over the past 11 years is presented. Results and Conclusion: The Forked Flap gives comparable and replicable results; except for a urethrocutaneous fistula rate of 4% no other complications were observed.

  13. Comparative Study Between Two Flaps—Trapezoidal flap (TZF) and Ocshenbein-Leubke Flap (OLF) in Periapical Surgeries

    National Research Council Canada - National Science Library

    Ahmed, Mohd Viqar; Rastogi, Sanjay; Baad, Rajendra K; Gupta, Anurag K; Nishad, Sumita G; Bansal, Mansi; Kumar, Sanjeev; Oswal, Rakesh; Mahendra, P; Bhatnagar, Alok

    2013-01-01

    .... The large variety of flaps available for periapical surgeries reflects the number of variables to be considered before choosing an appropriate flap design. In this study; Ocshenbein-Leubke (OL) and trapezoidal (TZ...

  14. [Boomerang flap. A true single-stage pedicled cross finger flap].

    Science.gov (United States)

    Legaillard, P; Grangier, Y; Casoli, V; Martin, D; Baudet, J

    1996-06-01

    The indications for cover of long fingers have been considerably modified over recent years as a result of the concept of retrograde flow flaps. However, in some cases in which the dorsal digital networks cannot be used, cross-finger flaps are still indicated for cover of long fingers beyond the PIP joint. The authors present a new flap eliminating the need for this rather complicated procedure. The donor site takes advantage of the rich dorsal collateral arterial network of P1 of an adjacent healthy finger. The flap can be raised due to the constant existence of a bifurcation between the collateral dorsal digital arterial networks and the anastomoses situated at various levels between the dorsal and palmar collateral networks of the long fingers, which are constant as far as the PIP joint. A dorsolateral flap can therefore be raised from a healthy finger and transferred to the injured finger by raising the fatty connective tissue, including the dorsal collateral pedicles, in the shape of a boomerang. This flap covers distal defects from the PIP joint to the fingertip. The authors describe the anatomical basis for raising of the flap, the operative technique and report six clinical cases with a mean follow-up of 11 months.

  15. [Reconstruction of the oral cavity: the free radial forearm flap versus the free jejunal flap].

    Science.gov (United States)

    Belli, E; Cicconetti, A; Matteini, C

    1995-05-01

    The concentration in a restricted area such as the oral cavity of the essential anatomic structures for mastication, deglutition, speech, salivary drainage and respiration makes it indispensable to ensure not only the structural reconstruction of the region but also, and above all, a functional reconstruction of the anatomic unit affected by resection. The use of revascularised flaps has extended both the quantity and quality of reconstructive methods available. In the context of the oral cavity the most widely used flaps are the radial forearm free flap and jejunum free flap. In this paper the authors report their personal experience in a group of 13 patients (6 radial forearm and 7 jejunum) undergoing oral cavity reconstruction using free flap. For each flap the authors describe the microsurgical procedure, the clinical characteristics of the post-operative period, the locoregional complications, the donor site and lastly the long-term clinical, anatomopathological and functional modifications 6-12 months after primary treatment. Moreover, they highlight the varying characteristics of the two flaps and make a critical assessment of the advantages and disadvantages of using one or other method. Lastly, in the light of their experience and a review of international literature, the authors underline the importance of making a careful choice and personalized reconstruction, and finally outline their own criteria of choice.

  16. Prospective evaluation of outcome measures in free-flap surgery.

    LENUS (Irish Health Repository)

    Kelly, John L

    2004-08-01

    Free-flap failure is usually caused by venous or arterial thrombosis. In many cases, lack of experience and surgical delay also contribute to flap loss. The authors prospectively analyzed the outcome of 57 free flaps over a 28-month period (January, 1999 to April, 2001). The setting was a university hospital tertiary referral center. Anastomotic technique, ischemia time, choice of anticoagulant, and the grade of surgeon were recorded. The type of flap, medications, and co-morbidities, including preoperative radiotherapy, were also documented. Ten flaps were re-explored (17 percent). There were four cases of complete flap failure (6.7 percent) and five cases of partial failure (8.5 percent). In patients who received perioperative systemic heparin or dextran, there was no evidence of flap failure (p = .08). The mean ischemia time was similar in flaps that failed (95 +\\/- 29 min) and in those that survived (92 +\\/- 34 min). Also, the number of anastomoses performed by trainees in flaps that failed (22 percent), was similar to the number in flaps that survived (28 percent). Nine patients received preoperative radiotherapy, and there was complete flap survival in each case. This study reveals that closely supervised anastomoses performed by trainees may have a similar outcome to those performed by more senior surgeons. There was no adverse effect from radiotherapy or increased ischemia time on flap survival.

  17. 14 CFR 23.1511 - Flap extended speed.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Flap extended speed. 23.1511 Section 23.1511 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT... Information § 23.1511 Flap extended speed. (a) The flap extended speed V FE must be established so that it...

  18. Haemodynamics and viability of skin and muscle flaps

    Energy Technology Data Exchange (ETDEWEB)

    Clarke, H.M.

    1985-01-01

    In reconstructive surgery, occasional free flap failures occur despite the clinical and technical advances in microsurgery of the past few years. To minimize these losses a better understanding of basic flap physiology must be achieved. The objectives of this work were the investigation of the haemodynamic characteristics of skin and muscle flaps in normal and compromised circumstances, the viability of skin and muscle flaps after pedicle ligation or ischaemia, and the possible interrelationship of haemodynamics and viability. A Wistar rat groin island skin flap model was used to assess flap survival following vascular compromise produced by vessel ligation. Survival was seen earliest following loss of the artery and was not dependent on circulation through the vascular pedicle after 5 days. A study using free groin flaps in rats gave similar results. Normal free groin flaps were then transferred to irradiated Fischer F344 rats. Delayed neovascularization was shown at a time corresponding to the onset of the late phase of the response to skin radiation. A canine inferior epigastric free skin flap model was established to determine the normal haemodynamic parameters during free flap transfer. A canine gracilis free muscle flap model was developed. Normal haemodynamic parameters are given. These parameters were examined after ischaemia. Survival of the muscle followed ischaemia of 4 hours or less. Flap survival is not dependent solely on arterial input or venous drainage. More complex phenomena such as the reactive hyperaemia following ischaemia are implicated in survival.

  19. Posttraumatic eyebrow reconstruction with hair-bearing temporoparietal fascia flap.

    Science.gov (United States)

    Denadai, Rafael; Raposo-Amaral, Cassio Eduardo; Marques, Frederico Figueiredo; Raposo-Amaral, Cesar Augusto

    2015-01-01

    The temporoparietal fascia flap has been extensively used in craniofacial reconstructions. However, its use for eyebrow reconstruction has been sporadically reported. We describe a successfully repaired hair-bearing temporoparietal fascia flap after traumatic avulsion of eyebrow. Temporoparietal fascia flap is a versatile tool and should be considered as a therapeutic option by all plastic surgeons.

  20. Posttraumatic eyebrow reconstruction with hair-bearing temporoparietal fascia flap

    Science.gov (United States)

    Denadai, Rafael; Raposo-Amaral, Cassio Eduardo; Marques, Frederico Figueiredo; Raposo-Amaral, Cesar Augusto

    2015-01-01

    The temporoparietal fascia flap has been extensively used in craniofacial reconstructions. However, its use for eyebrow reconstruction has been sporadically reported. We describe a successfully repaired hair-bearing temporoparietal fascia flap after traumatic avulsion of eyebrow. Temporoparietal fascia flap is a versatile tool and should be considered as a therapeutic option by all plastic surgeons. PMID:25993077

  1. Flap effectiveness appraisal for winged re-entry vehicles

    Science.gov (United States)

    de Rosa, Donato; Pezzella, Giuseppe; Donelli, Raffaele S.; Viviani, Antonio

    2016-05-01

    The interactions between shock waves and boundary layer are commonplace in hypersonic aerodynamics. They represent a very challenging design issue for hypersonic vehicle. A typical example of shock wave boundary layer interaction is the flowfield past aerodynamic surfaces during control. As a consequence, such flow interaction phenomena influence both vehicle aerodynamics and aerothermodynamics. In this framework, the present research effort describes the numerical activity performed to simulate the flowfield past a deflected flap in hypersonic flowfield conditions for a winged re-entry vehicle.

  2. Numerical and Experimental Modal Control of Flexible Rotor Using Electromagnetic Actuator

    Directory of Open Access Journals (Sweden)

    Edson Hideki Koroishi

    2014-01-01

    Full Text Available The present work is dedicated to active modal control applied to flexible rotors. The effectiveness of the corresponding techniques for controlling a flexible rotor is tested numerically and experimentally. Two different approaches are used to determine the appropriate controllers. The first uses the linear quadratic regulator and the second approach is the fuzzy modal control. This paper is focused on the electromagnetic actuator, which in this case is part of a hybrid bearing. Due to numerical reasons it was necessary to reduce the size of the model of the rotating system so that the design of the controllers and estimator could be performed. The role of the Kalman estimator in the present contribution is to estimate the modal states of the system and to determine the displacement of the rotor at the position of the hybrid bearing. Finally, numerical and experimental results demonstrate the success of the methodology conveyed.

  3. An efficient method and device for transfer of semisolid materials into solid-state NMR spectroscopy rotors.

    Science.gov (United States)

    Hisao, Grant S; Harland, Michael A; Brown, Robert A; Berthold, Deborah A; Wilson, Thomas E; Rienstra, Chad M

    2016-04-01

    The study of mass-limited biological samples by magic angle spinning (MAS) solid-state NMR spectroscopy critically relies upon the high-yield transfer of material from a biological preparation into the MAS rotor. This issue is particularly important for maintaining biological activity and hydration of semi-solid samples such as membrane proteins in lipid bilayers, pharmaceutical formulations, microcrystalline proteins and protein fibrils. Here we present protocols and designs for rotor-packing devices specifically suited for packing hydrated samples into Pencil-style 1.6 mm, 3.2 mm standard, and 3.2 mm limited speed MAS rotors. The devices are modular and therefore readily adaptable to other rotor and/or ultracentrifugation tube geometries.

  4. Effect of Rotor Diameter on the Thermal Stresses of a Turbine Rotor Model

    Science.gov (United States)

    Dávalos, J. O.; García, J. C.; Urquiza, G.; Castro-Gómez, L. L.; Rodríguez, J. A.; De Santiago, O.

    2016-04-01

    Thermal stresses in a simplified steam turbine rotor model during a cold startup are analyzed using finite element analysis (FEA). In order to validate the numerical model, an experimental array is developed in which a hollow cylinder is heated with hot air in the external surface. At the thick wall of the cylinder, temperature distribution is measured in real time, while at the same time an algorithm computes thermal stresses. Additional computational fluid dynamics (CFD) calculations are made to obtain magnitudes of velocity and pressure in order to compute convective heat transfer coefficient. The experimental results show good agreement with the FEA computations. To evaluate the effect of rotor diameter size, FEA computations with variation in external and internal diameters are performed. Results show that thermal stresses are proportional to rotor diameter size. Also, zones of higher stress concentration are found in the external and internal surfaces of the rotor.

  5. Treatment of Ischial Pressure Sores with Both Profunda Femoris Artery Perforator Flaps and Muscle Flaps

    Science.gov (United States)

    Kim, Chae Min; Yun, In Sik; Lee, Dong Won; Lew, Dae Hyun; Rah, Dong Kyun

    2014-01-01

    Background Reconstruction of ischial pressure sore defects is challenging due to extensive bursas and high recurrence rates. In this study, we simultaneously applied a muscle flap that covered the exposed ischium and large bursa with sufficient muscular volume and a profunda femoris artery perforator fasciocutaneous flap for the management of ischial pressure sores. Methods We retrospectively analyzed data from 14 patients (16 ischial sores) whose ischial defects had been reconstructed using both a profunda femoris artery perforator flap and a muscle flap between January 2006 and February 2014. We compared patient characteristics, operative procedure, and clinical course. Results All flaps survived the entire follow-up period. Seven patients (50%) had a history of surgery at the site of the ischial pressure sore. The mean age of the patients included was 52.8 years (range, 18-85 years). The mean follow-up period was 27.9 months (range, 3-57 months). In two patients, a biceps femoris muscle flap was used, while a gracilis muscle flap was used in the remaining patients. In four cases (25%), wound dehiscence occurred, but healed without further complication after resuturing. Additionally, congestion occurred in one case (6%), but resolved with conservative treatment. Among 16 cases, there was only one (6%) recurrence at 34 months. Conclusions The combination of a profunda femoris artery perforator fasciocutaneous flap and muscle flap for the treatment of ischial pressure sores provided pliability, adequate bulkiness and few long-term complications. Therefore, this may be used as an alternative treatment method for ischial pressure sores. PMID:25075362

  6. Treatment of Ischial Pressure Sores with Both Profunda Femoris Artery Perforator Flaps and Muscle Flaps

    Directory of Open Access Journals (Sweden)

    Chae Min Kim

    2014-07-01

    Full Text Available Background Reconstruction of ischial pressure sore defects is challenging due to extensive bursas and high recurrence rates. In this study, we simultaneously applied a muscle flap that covered the exposed ischium and large bursa with sufficient muscular volume and a profunda femoris artery perforator fasciocutaneous flap for the management of ischial pressure sores. Methods We retrospectively analyzed data from 14 patients (16 ischial sores whose ischial defects had been reconstructed using both a profunda femoris artery perforator flap and a muscle flap between January 2006 and February 2014. We compared patient characteristics, operative procedure, and clinical course. Results All flaps survived the entire follow-up period. Seven patients (50% had a history of surgery at the site of the ischial pressure sore. The mean age of the patients included was 52.8 years (range, 18-85 years. The mean follow-up period was 27.9 months (range, 3-57 months. In two patients, a biceps femoris muscle flap was used, while a gracilis muscle flap was used in the remaining patients. In four cases (25%, wound dehiscence occurred, but healed without further complication after resuturing. Additionally, congestion occurred in one case (6%, but resolved with conservative treatment. Among 16 cases, there was only one (6% recurrence at 34 months. Conclusions The combination of a profunda femoris artery perforator fasciocutaneous flap and muscle flap for the treatment of ischial pressure sores provided pliability, adequate bulkiness and few long-term complications. Therefore, this may be used as an alternative treatment method for ischial pressure sores.

  7. Experimental Investigation for Dynamic Characteristics of the Active Magnetic Bearing Rotor System with Zero Bias Current%零偏置电流磁轴承转子系统动态性能的试验研究

    Institute of Scientific and Technical Information of China (English)

    谢振宇; 龙亚文; 徐欣

    2013-01-01

    建立5自由度磁悬浮轴承转子试验系统,分析有偏置和零偏置电流方式的工作原理,将5自由度零偏置电流方式应用于试验系统中,采用锤击法模态试验、基于频率响应函数的模型修正方法和系统高速旋转试验等方法研究该系统的动态性能,并与有偏置电流方式进行比较.研究结果表明,与有偏置电流方式相比,零偏置电流方式将导致控制参数的稳定区域、系统的模态阻尼以及磁轴承的刚度和阻尼明显减小,系统在各阶临界转速时的振幅较大,但系统仍然可以安全稳定越过第一阶弯曲临界转速.在实际应用中,合理的设计仍可保证零偏置电流磁悬浮轴承转子系统安全稳定运行,特别是在低速或载荷平稳等应用场合,零偏置电流方式能够使得系统具有较好的综合性能.%An experimental setup of five degree-of-freedom active magnetic bearing (AMB) rotor system is built up.The modes of bias current and zero bias current are presented.Dynamic characteristics of the system with zero bias current are investigated by stamping modal test,method of model updating based on frequency response function (FRF) and actual operation of the system,and compared with the results of the system with bias current.The results show that,for the system with zero bias current,the stability region of control parameters,modal damping and stiffness and damping of AMB are reduced obviously and its vibration amplitudes in motion on the critical speeds are larger than the system with bias current,however it can still get across the first bending critical speed safely.If the design of the system is proper,the mode of zero bias current can be adopted in actual application,especially in the application of low rotation speed and stable load,so that the system has better over-all properties.

  8. Computational Study of Flow Interactions in Coaxial Rotors

    Science.gov (United States)

    Yoon, Seokkwan; Lee, Henry C.; Pulliam, Thomas H.

    2016-01-01

    Although the first idea of coaxial rotors appeared more than 150 years ago, most helicopters have used single main-rotor/tail-rotor combination. Since reactive moments of coaxial rotors are canceled by contra-rotation, no tail rotor is required to counter the torque generated by the main rotor. Unlike the single main rotor design that distributes power to both main and tail rotors, all of the power for coaxial rotors is used for vertical thrust. Thus, no power is wasted for anti-torque or directional control. The saved power helps coaxial rotors reach a higher hover ceiling than single rotor helicopters. Another advantage of coaxial rotors is that the overall rotor diameter can be reduced for a given vehicle gross weight because each rotor provides a maximum contribution to vertical thrust to overcome vehicle weight. However, increased mechanical complexity of the hub has been one of the challenges for manufacturing coaxial rotorcraft. Only the Kamov Design Bureau of Russia had been notably successful in production of coaxial helicopters until Sikorsky built X2, an experimental compound helicopter. Recent developments in unmanned aircraft systems and high-speed rotorcraft have renewed interest in the coaxial configuration. Multi-rotors are frequently used for small electric unmanned rotorcraft partly due to mechanical simplicity. The use of multiple motors provides redundancy as well as cost-efficiency. The multi-rotor concept has rarely been used until recently because of its inherent stability and control problems. However, advances in inexpensive electronic flight control systems have opened the floodgates for small drones using multirotors. Coaxial rotors have started to appear in some multi-rotor configurations. Small coaxial rotors have often been designed using a hundred year old approach that is "sketch, build, fly, and iterate." In that approach, there is no systematic way to explore trade-offs or determine logical next steps. It is neither possible to

  9. Nonlinear Vibration of Rotor Rubbing Stator Caused by Initial Perturbation

    Institute of Scientific and Technical Information of China (English)

    张小章; 隆锦胜; 李正光

    2001-01-01

    The vibration of a rotor rubbing a stator caused by an initial perturbation was studied analytically.The analytical model consists of a simple disc shaft rotor and a fixed stator. The perturbation is aninstantaneous change of the radial velocity when the rotor is operating in its normal steady state. The analysisshowed that the rotor may continue rubbing the stator for small clearance, even if the initial perturbation nolonger exists. For the interest of engineering applications, we investigated various rotating speeds,perturbation amplitudes and clearances between the rotor and the stator. Various friction coefficients on thecontact surface were also considered. The graphical results can be used for the design of rotating machines.``

  10. Time Frequency Features of Rotor Systems with Slowly Varying Mass

    Directory of Open Access Journals (Sweden)

    Tao Yu

    2011-01-01

    Full Text Available With the analytic method and numerical method respectively, the asymptotic solutions and finite element model of rotor system with single slowly varying mass is obtained to investigate the time frequency features of such rotor system; furthermore, with given model of slowly varying mass, the rotor system with dual slowly varying mass is studied. For the first order approximate solution is used, there exists difference between the results with analytic method and numerical method. On the base of common characteristics of rotor system with dual slowly varying mass, the general rules and formula describing the frequency distribution of rotor system with multiple slowly varying mass are proposed.

  11. Equivalence Between Squirrel Cage and Sheet Rotor Induction Motor

    Science.gov (United States)

    Dwivedi, Ankita; Singh, S. K.; Srivastava, R. K.

    2016-06-01

    Due to topological changes in dual stator induction motor and high cost of its fabrication, it is convenient to replace the squirrel cage rotor with a composite sheet rotor. For an experimental machine, the inner and outer stator stampings are normally available whereas the procurement of rotor stampings is quite cumbersome and is not always cost effective. In this paper, the equivalence between sheet/solid rotor induction motor and squirrel cage induction motor has been investigated using layer theory of electrical machines, so as to enable one to utilize sheet/solid rotor in dual port experimental machines.

  12. Numerical evaluation of tandem rotor for highly loaded transonic fan

    Institute of Scientific and Technical Information of China (English)

    ZHAO Bin; LIU Bao-jie

    2011-01-01

    Transonic tandem rotor was designed for highly loaded fan at a corrected tip speed of 381 m/s and another conventional rotor was designed as a baseline to evaluate the loading superiority of tandem rotor with three-dimensional (3-D) numerical simulation. The aft blade solidity and its impact on total loading level were studied in depth. The result indicates that tandem rotor has potential to achieve higher loading level and attain favorable aerodynamic performance in a wide range of loading coefficient 0. 55 ~ 0.68, comparing with the conventional rotor which produced a total pressure ratio of 2.0 and loading coefficient of 0. 42.

  13. T700 power turbine rotor multiplane/multispeed balancing demonstration

    Science.gov (United States)

    Burgess, G.; Rio, R.

    1979-01-01

    Research was conducted to demonstrate the ability of influence coefficient based multispeed balancing to control rotor vibration through bending criticals. Rotor dynamic analyses were conducted of the General Electric T700 power turbine rotor. The information was used to generate expected rotor behavior for optimal considerations in designing a balance rig and a balance technique. The rotor was successfully balanced 9500 rpm. Uncontrollable coupling behavior prevented observations through the 16,000 rpm service speed. The balance technique is practical and with additional refinement it can meet production standards.

  14. On the flow field around a Savonius rotor

    Science.gov (United States)

    Bergeles, G.; Athanassiadis, N.

    A model of a two-bucket Savonius rotor windmill was constructed and tested in a wind tunnel. The flow field around the rotor was examined visually and also quantitatively with the use of a hot wire. The flow visualization revealed an upstream influence on the flow field up to 3 rotor diameters away and a strong downwash downstream. Hot wire measurements showed a large velocity deficit behind the rotor and a quick velocity recovery downstream due to strong mixing; the latter was associated with high levels of turbulence. Energy spectra revealed that all turbulence was concentrated in a single harmonic corresponding to twice the rotational speed of the rotor.

  15. The angel flap for nipple reconstruction.

    Science.gov (United States)

    Wong, Wendy W; Hiersche, Matthew A; Martin, Mark C

    2013-01-01

    Creation of an aesthetically pleasing nipple plays a significant role in breast reconstruction as a determining factor in patient satisfaction. The goals for nipple reconstruction include minimal donor site morbidity and appropriate, long-lasting projection. Currently, the most popular techniques used are associated with a significant loss of projection postoperatively. Accordingly, the authors introduce the angel flap, which is designed to achieve nipple projection with lasting results. The lateral edges of the flap and the area surrounding the top of the nipple are de-epithelialized and the flaps are wrapped to create a nipple mound composed primarily of dermis. Decreasing the amount of fat within core of the nipple and enhancing dermal content promotes long-lasting projection. Furthermore, the incision pattern fits within a desired areolar size, preventing unnecessary superfluous extension of the incisions. Thus, the technique described herein achieves the goals of nipple reconstruction, including adequate and long-lasting projection, without extension of the lateral limb scars.

  16. Double papilla flap technique for dual purpose

    Directory of Open Access Journals (Sweden)

    P Mohan Kumar

    2012-01-01

    Full Text Available Marginal tissue recession exposes the anatomic root on the teeth, which gives rise to -common patient complaints. It is associated with sensitivity, tissue irritation, cervical abrasions, and esthetic concerns. Various types of soft tissue grafts may be performed when recession is deep and marginal tissue health cannot be maintained. Double papilla flap is an alternative technique to cover isolated recessions and correct gingival defects in areas of insufficient attached gingiva, not suitable for a lateral sliding flap. This technique offers the advantages of dual blood supply and denudation of interdental bone only, which is less susceptible to permanent damage after surgical exposure. It also offers the advantage of quicker healing in the donor site and reduces the risk of facial bone height loss. This case report presents the advantages of double papilla flap in enhancing esthetic and functional outcome of the patient.

  17. Rotor Design for Diffuser Augmented Wind Turbines

    Directory of Open Access Journals (Sweden)

    Søren Hjort

    2015-09-01

    Full Text Available Diffuser augmented wind turbines (DAWTs can increase mass flow through the rotor substantially, but have often failed to fulfill expectations. We address high-performance diffusers, and investigate the design requirements for a DAWT rotor to efficiently convert the available energy to shaft energy. Several factors can induce wake stall scenarios causing significant energy loss. The causality between these stall mechanisms and earlier DAWT failures is discussed. First, a swirled actuator disk CFD code is validated through comparison with results from a far wake swirl corrected blade-element momentum (BEM model, and horizontal-axis wind turbine (HAWT reference results. Then, power efficiency versus thrust is computed with the swirled actuator disk (AD code for low and high values of tip-speed ratios (TSR, for different centerbodies, and for different spanwise rotor thrust loading distributions. Three different configurations are studied: The bare propeller HAWT, the classical DAWT, and the high-performance multi-element DAWT. In total nearly 400 high-resolution AD runs are generated. These results are presented and discussed. It is concluded that dedicated DAWT rotors can successfully convert the available energy to shaft energy, provided the identified design requirements for swirl and axial loading distributions are satisfied.

  18. Eigenvalue assignment strategies in rotor systems

    Science.gov (United States)

    Youngblood, J. N.; Welzyn, K. J.

    1986-01-01

    The work done to establish the control and direction of effective eigenvalue excursions of lightly damped, speed dependent rotor systems using passive control is discussed. Both second order and sixth order bi-axis, quasi-linear, speed dependent generic models were investigated. In every case a single, bi-directional control bearing was used in a passive feedback stabilization loop to resist modal destabilization above the rotor critical speed. Assuming incomplete state measurement, sub-optimal control strategies were used to define the preferred location of the control bearing, the most effective measurement locations, and the best set of control gains to extend the speed range of stable operation. Speed dependent control gains were found by Powell's method to maximize the minimum modal damping ratio for the speed dependent linear model. An increase of 300 percent in stable speed operation was obtained for the sixth order linear system using passive control. Simulations were run to examine the effectiveness of the linear control law on nonlinear rotor models with bearing deadband. The maximum level of control effort (force) required by the control bearing to stabilize the rotor at speeds above the critical was determined for the models with bearing deadband.

  19. 14 CFR 33.34 - Turbocharger rotors.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Turbocharger rotors. 33.34 Section 33.34 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES Design and Construction; Reciprocating Aircraft Engines § 33.34...

  20. Flywheel system using wire-wound rotor

    Energy Technology Data Exchange (ETDEWEB)

    Chiao, Edward Young; Bender, Donald Arthur; Means, Andrew E.; Snyder, Philip K.

    2016-06-07

    A flywheel is described having a rotor constructed of wire wound onto a central form. The wire is prestressed, thus mitigating stresses that occur during operation. In another aspect, the flywheel incorporates a low-loss motor using electrically non-conducting permanent magnets.

  1. Rotor Systems of Aircraft Jet Engines

    Directory of Open Access Journals (Sweden)

    Ján Kamenický

    2000-01-01

    engine's both coaxial rotors, their supports (including their hydrodynamic dampers, and its casing as well. Besides the short description of the engine design peculiarities and of its calculating model, there is also a short description of the used method of calculations, with focus on its peculiarities as well. Finally, some results of calculations and conclusions that follow from them are presented.

  2. Development of the optimum rotor theories

    DEFF Research Database (Denmark)

    Okulov, Valery; Sørensen, Jens Nørkær; van Kuik, Gijs A.M.

    The purpose of this study is the examination of optimum rotor theories with ideal load distributions along the blades, to analyze some of the underlying ideas and concepts, as well as to illuminate them. The book gives the historical background of the issue and presents the analysis of the proble...

  3. rotor of the SC rotating condenser

    CERN Multimedia

    1974-01-01

    The rotor of the rotating condenser was installed instead of the tuning fork as the modulating element of the radiofrequency system, when the SC accelerator underwent extensive improvements between 1973 to 1975 (see object AC-025). The SC was the first accelerator built at CERN. It operated from August 1957 until it was closed down at the end of 1990.

  4. Wind rotors and birds; Windraeder: neue Vogelperspektiven

    Energy Technology Data Exchange (ETDEWEB)

    Loenker, O.; Jensen, D.

    2005-01-01

    Although most birds are not shy of wind rotors, authorities tend to use environmental protection arguments in their attempt to prevent wind power projects. Planners should be careful to establish ecological expert opinions for envisaged sites at an early stage. (orig.)

  5. MODIFIED SAVONIUS ROTOR FOR DOMESTIC POWER PRODUCTION

    Directory of Open Access Journals (Sweden)

    VINAY P V

    2012-07-01

    Full Text Available Conventional fuels which are fast depleting, have ever fluctuating price and polluting characteristic of theirs is pushing mankind towards energies which are renewable and green. Wind being one of the renewable energies among solar, geothermal, biomass, ocean and others is being more patronized in places where wind is copious by governmental and with private partnership to generate electricity. Vertical axis rotor was selected over the horizontal ones due to its simplicity and reliability. At a selected location a prototype was built and installed. The design and development process and the need of the new type of machine will be described in this paper. This paper produces an investigational exploration of a vertical axis rotor (Savonius rotor wind turbine adapted for household/domestic electricity generation. The model machine collects wind energy and generates a 12 volt output which is used to charge one heavy duty battery. As a result, the home is served simultaneously by the wind turbine and the utility. The wind turbine responds well to low wind velocities and also various materials for vanes, various transmission mechanisms were also tried to evaluate the performance of the rotor.

  6. [Reconstruction of full-thickness nasal alar defect with combined nasolabial flap and free auricular composite flap].

    Science.gov (United States)

    Peng, Weihai; Rong, Li; Wang, Wangshu; Liu, Chao; Zhang, Duo

    2014-05-01

    To investigate the technique and its effect of combined nasolabial flap and free auricular composite flap for full-thickness nasal alar defect. From March 2010 to March 2013, 9 patients with full-thickness nasal alar defects were treated with combined nasolabial flaps and free auricular composite flaps. Composite auricular flap was used as inner lining and cartilage framework. The nasolabial flap at the same side was used as outer lining. All the patients were followed up for 6-18 months (average, 12 months). All the 9 composite auricular flaps survived completely. Epidermal necrosis happened at the distal end of 1 nasolabial flap. Alar rim was almost normal and symmetric nose was achieved in 6 cases. The arc and the thickness of the alar rim was not enough in 3 cases, resulting in asymmetric appearance. The survival area of auricular composite flap can be enlarged with nasolabial flap. The auricular helix edge can be reserved to reconstruct nasal alar rim with smooth and natural arc. Large full-thickness nasal alar defedts can be reconstructed with combined nasolabial flaps and free auricular composite flaps.

  7. Perforator anatomy of the radial forearm free flap versus the ulnar forearm free flap for head and neck reconstruction

    NARCIS (Netherlands)

    Hekner, D.D.; Roeling, TAP; van Cann, EM

    2016-01-01

    The aim of this study was to investigate the vascular anatomy of the distal forearm in order to optimize the choice between the radial forearm free flap and the ulnar forearm free flap and to select the best site to harvest the flap. The radial and ulnar arteries of seven fresh cadavers were injecte

  8. Utilization of rotor kinetic energy storage for hybrid vehicles

    Science.gov (United States)

    Hsu, John S.

    2011-05-03

    A power system for a motor vehicle having an internal combustion engine, the power system comprises an electric machine (12) further comprising a first excitation source (47), a permanent magnet rotor (28) and a magnetic coupling rotor (26) spaced from the permanent magnet rotor and at least one second excitation source (43), the magnetic coupling rotor (26) also including a flywheel having an inertial mass to store kinetic energy during an initial acceleration to an operating speed; and wherein the first excitation source is electrically connected to the second excitation source for power cycling such that the flywheel rotor (26) exerts torque on the permanent magnet rotor (28) to assist braking and acceleration of the permanent magnet rotor (28) and consequently, the vehicle. An axial gap machine and a radial gap machine are disclosed and methods of the invention are also disclosed.

  9. Rotor for a line start permanent magnet machine

    Energy Technology Data Exchange (ETDEWEB)

    Melfi, Mike; Schiferl, Rich; Umans, Stephen

    2017-07-11

    A rotor comprises laminations with a plurality of rotor bar slots with an asymmetric arrangement about the rotor. The laminations also have magnet slots equiangularly spaced about the rotor. The magnet slots extend near to the rotor outer diameter and have permanent magnets disposed in the magnet slots creating magnetic poles. The magnet slots may be formed longer than the permanent magnets disposed in the magnets slots and define one or more magnet slot apertures. The permanent magnets define a number of poles and a pole pitch. The rotor bar slots are spaced from adjacent magnet slots by a distance that is at least 4% of the pole pitch. Conductive material is disposed in the rotor bar slots, and in some embodiments, may be disposed in the magnet slot apertures.

  10. The transversely split gracilis twin free flaps

    Directory of Open Access Journals (Sweden)

    Upadhyaya Divya

    2010-01-01

    Full Text Available The gracilis muscle is a Class II muscle that is often used in free tissue transfer. The muscle has multiple secondary pedicles, of which the first one is the most consistent in terms of position and calibre. Each pedicle can support a segment of the muscle thus yielding multiple small flaps from a single, long muscle. Although it has often been split longitudinally along the fascicles of its nerve for functional transfer, it has rarely been split transversely to yield multiple muscle flaps that can be used to cover multiple wounds in one patient without subjecting him/her to the morbidity of multiple donor areas .

  11. Dynamical localization of coupled relativistic kicked rotors

    Science.gov (United States)

    Rozenbaum, Efim B.; Galitski, Victor

    2017-02-01

    A periodically driven rotor is a prototypical model that exhibits a transition to chaos in the classical regime and dynamical localization (related to Anderson localization) in the quantum regime. In a recent work [Phys. Rev. B 94, 085120 (2016), 10.1103/PhysRevB.94.085120], A. C. Keser et al. considered a many-body generalization of coupled quantum kicked rotors, and showed that in the special integrable linear case, dynamical localization survives interactions. By analogy with many-body localization, the phenomenon was dubbed dynamical many-body localization. In the present work, we study nonintegrable models of single and coupled quantum relativistic kicked rotors (QRKRs) that bridge the gap between the conventional quadratic rotors and the integrable linear models. For a single QRKR, we supplement the recent analysis of the angular-momentum-space dynamics with a study of the spin dynamics. Our analysis of two and three coupled QRKRs along with the proved localization in the many-body linear model indicate that dynamical localization exists in few-body systems. Moreover, the relation between QRKR and linear rotor models implies that dynamical many-body localization can exist in generic, nonintegrable many-body systems. And localization can generally result from a complicated interplay between Anderson mechanism and limiting integrability, since the many-body linear model is a high-angular-momentum limit of many-body QRKRs. We also analyze the dynamics of two coupled QRKRs in the highly unusual superballistic regime and find that the resonance conditions are relaxed due to interactions. Finally, we propose experimental realizations of the QRKR model in cold atoms in optical lattices.

  12. Pre-expanded Intercostal Perforator Super-Thin Skin Flap.

    Science.gov (United States)

    Liao, Yunjun; Luo, Yong; Lu, Feng; Hyakusoku, Hiko; Gao, Jianhua; Jiang, Ping

    2017-01-01

    This article introduces pre-expanded super-thin intercostal perforator flaps, particularly the flap that has a perforator from the first to second intercostal spaces. The key techniques, advantages and disadvantages, and complications and management of this flap are described. At present, the thinnest possible flap is achieved by thinning the pre-expanded flap that has a perforator from the first to second intercostal spaces. It is used to reconstruct large defects on the face and neck, thus restoring function and cosmetic appearance. Copyright © 2016 Elsevier Inc. All rights reserved.

  13. Fascia-only anterolateral thigh flap for extremity reconstruction.

    Science.gov (United States)

    Fox, Paige; Endress, Ryan; Sen, Subhro; Chang, James

    2014-05-01

    The ability to use the anterolateral thigh (ALT) flap as a vascularized fascial flap, without skin or muscle, was first documented by Koshima et al in 1989. The authors mention the possibility of using the fascia alone for dural reconstruction. Despite its description more than 20 years ago, little literature exists on the application of the ALT flap as a vascularized fascial flap. In our experience, the ALT flap can be used as a fascia-only flap for thin, pliable coverage in extremity reconstruction. After approval from the institutional review board, the medical records and photographs of patients who had undergone fascia-only ALT free flaps for extremity reconstruction were reviewed. Photographic images of patients were then matched to patients who had undergone either a muscle-only or a fasciocutaneous free flap reconstruction of an extremity. Photographs of the final reconstruction were then given to medical and nonmedical personnel for analysis, focusing on aesthetics including color and contour. Review of cases performed over a 2-year period demonstrated similar ease of harvest for fascia-only ALT flaps compared to standard fasciocutaneous ALT flaps. Fascia-only flaps were used for thin, pliable coverage in the upper and lower extremities. There was no need for secondary procedures for debulking or aesthetic flap revision. In contrast to muscle flaps, which require muscle atrophy over time to achieve their final appearance, there was a similar flap contour from approximately 1 month postoperatively throughout the duration of follow-up. When a large flap is required, the fascia-only ALT has the advantage of a single-line donor-site scar. Photograph comparison to muscle flaps with skin grafts and fasciocutaneous flaps demonstrated improved color, contour, and overall aesthetic appearance of the fascia-only ALT over muscle and fasciocutaneous flaps. The fascia-only ALT flap provides reliable, thin, and pliable coverage with improved contour and color over

  14. Dynamics of fluidic devices with applications to rotor pitch links

    Science.gov (United States)

    Scarborough, Lloyd H., III

    impedance. At low frequency, the pitch link must have high impedance to pass through the pilot's collective and cyclic commands to control the aircraft. At higher frequencies, however, the pitch-link impedance can be tuned to change the blade pitching response to higher harmonic loads. Active blade control to produce higher harmonic pitch motions has been shown to reduce hub loads and increase rotor efficiency. This work investigates whether fluidic pitch links can passively provide these benefits. An analytical model of a fluidic pitch link is derived and incorporated into a rotor aeroelastic simulation for a rotor similar to that of the UH-60. Eighty-one simulations with varied fluidic pitch link parameters demonstrate that their impedance can be tailored to reduce rotor power and all six hub forces and moments. While no impedance was found that simultaneously reduced all components, the results include cases with reductions in the lateral 4/rev hub force of up to 91% and 4/rev hub pitching moment of up to 67%, and main rotor power of up to 5%.

  15. The study of expanded tri-lobed flap in a rabbit model: possible flap model in ear reconstruction?

    Directory of Open Access Journals (Sweden)

    Yüreklý Yakup

    2003-12-01

    Full Text Available Abstract Background Local flaps are widely used in reconstructive surgery. Tri-lobed skin flap is a relatively new flap and there has been no experimental model of this flap. This flap can be used for repair of full thickness defects in the face, ears and alar region. Based on the size of ears in a rabbit, we designed a model of ear reconstruction using expanded tri-lobed flap. Local flaps are more advantageous in that they provide excellent color and texture matching up with those of the face, adequately restore ear contour, place scars in a favorable location and ideally accomplish these goals in a single stage with minimal donor site morbidity. Methods Eight adult New Zealand rabbits were divided into two groups. 50 ml round tissue expander were implanted to four rabbits. After completion of the expansion, a superiorly based tri-lobed flap was elevated and a new ear was created from the superior dorsal skin of each rabbit. Scintigraphy with Technetium-99m pertecnetate was performed to evaluate flap viability. Results Subtotal flap necrosis was seen in all animals in non-expanded group. New ear in dimensions of the original ear was created in expanded group without complication. Perfusion and viability of the flaps were proved by Technetium-99m pertecnetate scintigraphy. Conclusion According to our knowledge this study is the first to demonstrate animal model in tri-lobed flap. Also, our technique is the first application of the trilobed flap to the possible ear reconstruction. We speculated that this flap may be used mastoid based without hair, in human. Also, tri-lobed flap may be an alternative in reconstruction of cylindrical organs such as penis or finger.

  16. Experimental study of main rotor tip geometry and tail rotor interactions in hover. Volume 2: Run log and tabulated data

    Science.gov (United States)

    Balch, D. T.; Lombardi, J.

    1985-01-01

    A model scale hover test was conducted in the Sikorsky Aircraft Model Rotor hover Facility to identify and quantify the impact of the tail rotor on the demonstrated advantages of advanced geometry tip configurations. The existence of mutual interference between hovering main rotor and a tail rotor was acknowledged in the test. The test was conducted using the Basic Model Test Rig and two scaled main rotor systems, one representing a 1/5.727 scale UH-60A BLACK HAWK and the others a 1/4.71 scale S-76. Eight alternate rotor tip configurations were tested, 3 on the BLACK HAWK rotor and 6 on the S-76 rotor. Four of these tips were then selected for testing in close proximity to an operating tail rotor (operating in both tractor and pusher modes) to determine if the performance advantages that could be obtained from the use of advanced geometry tips in a main rotor only environment would still exist in the more complex flow field involving a tail rotor. This volume contains the test run log and tabulated data.

  17. Perforator-based fasciocutaneous flap for pressure sore reconstruction.

    Science.gov (United States)

    Lin, Chih-Hsun; Ma, Hsu

    2012-12-01

    Pressure sore reconstruction is always a challenge for plastic surgeons due to its high recurrence rate. In addition to the myocutaneous flap, the perforator-based fasciocutaneous flap has become a new entity used for pressure sore reconstruction. This study presents a series of 26 perforator-based fasciocutaneous flaps for pressure sore reconstruction, with good outcomes in 21 patients from July 2008 to April 2011. The flaps were advanced, transposed, or rotated to obliterate the defects. Twenty of 26 flaps healed uneventfully without complication. One patient had a flap that totally necrosed, one had partial flap necrosis (flap rotated 180° in the above two cases), one had infection and healed by a secondary flap, one had minor wound dehiscence, one died of pneumonia 1 week postoperatively, and recurrence developed in one patient. The perforator-based fasciocutaneous flap is a reliable method and produced good results in this series. These flaps are well vascularised, have enough soft tissue bulk, and have a high degree of mobilisation freedom.

  18. 电控旋翼气动特性建模与风洞试验验证%Aerodynamic characteristic modeling of electrically controlled rotor and wind tunnel test verification

    Institute of Scientific and Technical Information of China (English)

    陆洋; 王超

    2013-01-01

    Firstly, the unsteady aerodynamic model of the airfoil with trailing-edge flap was developed. Secondly, the finite state wake model of electrically controlled rotor (ECR) based on the Peters-He generalized dynamic wake theory was developed, in which the effect of the trailing-edge flap on the rotor aerodynamic environment was considered. Combined with the relationship among the blade flapping angle, the blade pitch and the deflection angle of the trailing-edge flap, the model of calculating the aerodynamic characteristics of ECR was established finally. Then, wind tunnel tests were conducted, in which the aerodynamic force, the blade pitch, the deflection angle of the trailing-edge flap and the blade flapping angle varying with different test statuses were measured. Theoretical results basically coincided with the experimental data, which verified the correction of the theoretical model. Conclusions are drawn as follows: with the fixed rotor speed, there is a linear relationship between blade pitch response and flap control; rotor thrust decreases with the increase of flap collective control, and actual aerodynamic efficiency of the flap decreases under large collective control; in forward flight, flap collective control can cause changes of blade cyclic pitch.%首先建立了带襟翼翼型的非定常气动力模型,继而基于Peters-He广义动态尾迹理论,考虑襟翼偏转对电控旋翼叶素环境的影响,建立了电控旋翼有限状态尾迹模型;进一步基于Theodorsen理论推导出电控旋翼桨叶挥舞响应与桨叶变距和襟翼操纵量的关系,综合以上建立了电控旋翼气动特性分析模型.以改进型电控旋翼试验系统为平台进行了风洞试验,测量了不同风速、不同襟翼操纵条件下的电控旋翼气动力、桨距、襟翼偏角及旋翼挥舞角的变化情况.理论计算结果与试验数据符合情况良好,验证了所建立的分析模型的正确性,并得出以下结论:旋翼转速一定

  19. Effect of Systemic Antioxidant Allopurinol Therapy on Skin Flap Survival

    Science.gov (United States)

    Rasti Ardakani, Mehdi; Al-Dam, Ahmed; Rashad, Ashkan; Shayesteh Moghadam, Ali

    2017-01-01

    BACKGROUND It has been reported that systemic administration of allopurinol improves cell survival. This study was aimed to evaluate effects of allopurinol on skin flaps in dogs. METHODS Twenty dogs underwent one skin flap surgery with a 2-week interval. The first procedure was performed according to the standard protocols. The second phase was started by a 1-week pretreatment with allopurinol. Length of the necrotic zone was measured and recorded daily. At each phase, flaps were removed and sent for histopathological study after 1 week observation. RESULTS Mean length of the necrotic zone in allopurinol treated skin flaps has been significantly less than normal flaps over all 7 days of observation (p<0.0001). Histopathology study showed less inflammation and more normal tissue structure in the allopurinol treated skin flaps. CONCLUSION It was demonstrated that systemic administration of allopurinol significantly improved skin flap survival. PMID:28289614

  20. Breast reconstruction by pedicled transverse rectus abdominis myocutaneous flap

    Directory of Open Access Journals (Sweden)

    Kozarski Jefta

    2004-01-01

    Full Text Available Reconstruction of the amputated breast in female patients after surgical management of breast carcinoma is possible with the use of autologous tissue, synthetic implants, or by combining autologous tissue and synthetic materials. Autologous tissue provides soft and sufficiently elastic tissue which is usable for breast reconstruction and eventually obtains original characteristics of the surrounding tissue on the chest wall. The use of the TRAM flap for breast reconstruction was introduced in 1982 by Hartrampf Scheflan, and Black. The amount of the TRAM flap tissue allows breast reconstruction in the shape most adequate to the remaining breast. The possibilities of using the TRAM flap as pedicled myocutaneous flap or as free TRAM flap make this flap a superior choice for breast reconstruction in comparison with other flaps.

  1. Surgical procedure of Free Flap. Main nursing care

    Directory of Open Access Journals (Sweden)

    Manuel Molina López

    2010-05-01

    Full Text Available The free flap surgical technique is used to cover extensive skin loss areas and situations where no flap is available, or in axial zones. The great breackthrough in the field of reconstructive surgical techniques and the creation of new units where these complex techniques are used, means that the nursing staff who work in these hospital units are adquiring greater protagonism in caring for, and the subsequent success of this type of surgery in which the problems of collaboration in all the perioperative phases depend entirely on the nursing team.The collaborative nursing problems could be defined as real or potential health problems, where users need nursing staff to follow the treatment and control procedures prescribed by other professional, generally doctors, who control and are responsible for the final outcome.While planning collaborative objectives and activities it should be taken into account that the function of the nursing staff is twofold: on the one hand, the patient must be taken care of as prescribed by other professionals and, on the other hand, it should bring into play cognitive elements (knowledge and know-how and clinical judgment when executing these in controlling the patients evolution.In this article our intention is to give an interesting and comprehensive description of the free flap surgical technique, its pros and cons, and identify the principal collaborative problems which nursing will have to deal with in each one of the perioperative phases, the number and specific nature of such oblige nursing on many occasions, to update and/or acquire new skills.

  2. Functional results of microvascular reconstruction after hemiglossectomy: free anterolateral thigh flap versus free forearm flap

    OpenAIRE

    TARSITANO, A.; VIETTI, M.V.; Cipriani, R; MARCHETTI, C.

    2013-01-01

    SUMMARY The aim of the present study is to assess functional outcomes after hemiglossectomy and microvascular reconstruction. Twenty-six patients underwent primary tongue microvascular reconstruction after hemiglossectomy. Twelve patients were reconstructed using a free radial forearm flap and 14 with an anterolateral thigh flap. Speech intelligibility, swallowing capacity and quality of life scores were assessed. Factors such as tumour extension, surgical resection and adjuvant radiotherapy ...

  3. Spectral analysis of blood perfusion in the free latissimus dorsi myocutaneous flap and in normal skin

    Energy Technology Data Exchange (ETDEWEB)

    Liu Xudong [Department of Orthopaedic Surgery, Shanghai No. 6 People' s Hospital, Shanghai Jiao Tong University, 600 Yishan Road, Shanghai 200233 (China); Zeng Bingfang [Department of Orthopaedic Surgery, Shanghai No. 6 People' s Hospital, Shanghai Jiao Tong University, 600 Yishan Road, Shanghai 200233 (China); Fan Cunyi [Department of Orthopaedic Surgery, Shanghai No. 6 People' s Hospital, Shanghai Jiao Tong University, 600 Yishan Road, Shanghai 200233 (China); Jiang Peizhu [Department of Orthopaedic Surgery, Shanghai No. 6 People' s Hospital, Shanghai Jiao Tong University, 600 Yishan Road, Shanghai 200233 (China); Hu Xiao [Department of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai 200030 (China)

    2006-01-07

    To find the properties in the oscillatory components of the cutaneous blood flow on the successful free flap, a wavelet transform was applied to the laser Doppler flowmetry (LDF) signals which were measured simultaneously on the surfaces of the free latissimus dorsi myocutaneous flap and on the adjacent intact skin of the healthy limb, of 18 patients. The frequency interval from 0.0095 to 1.6 Hz was examined and was divided into five subintervals (I: 0.0095-0.021 Hz; II: 0.021-0.052 Hz; III: 0.052-0.145 Hz; IV: 0.145-0.6 Hz and V: 0.6-1.6 Hz) corresponding to endothelial metabolic, neurogenic, myogenic, respiratory and cardiac origins. The average amplitude and total power in the frequency range 0.0095-1.6 Hz as well as within subintervals I, II, IV and V were significantly lower for signals measured on the free flap than those obtained in the healthy limb. However in interval III, they were significantly higher. The normalized spectral amplitude and power in the free flap were significantly lower in only two intervals, I and II, yet in interval III they were significantly higher; no statistical significance was observed in intervals IV and V. The distinctive finding made in this study, aside from the decrease of endothelial metabolic processes and sympathetic control, was the significant increase of myogenic activity in the free flap. It is hoped that this work will contribute towards knowledge on blood circulation in free flaps and make the monitoring by LDF more reliable.

  4. Dorsalis Pedis Free Flap: The Salvage Option following Failure of the Radial Forearm Flap in Total Lower Lip Reconstruction

    OpenAIRE

    Theodoros Stathas; Georgios Tsinias; Dimitra Tsiliboti; Aris Tsiros; Nicholas Mastronikolis; Panos Goumas

    2014-01-01

    Reconstruction after resection of large tumors of the lower lip requires the use of free flaps in order to restore the shape and the function of the lip, with the free radial forearm flap being the most popular. In this study we describe our experience in using the dorsalis pedis free flap as a salvage option in reconstruction of total lower lip defect in a patient with an extended lower lip carcinoma after failure of the radial forearm free flap, that was initially used. The flap was integra...

  5. To flap or not to flap: a discussion between a fish and a jellyfish

    Science.gov (United States)

    Martin, Nathan; Roh, Chris; Idrees, Suhail; Gharib, Morteza

    2016-11-01

    Fish and jellyfish are known to swim by flapping and by periodically contracting respectively, but which is the more effective propulsion mechanism? In an attempt to answer this question, an experimental comparison is made between simplified versions of these motions to determine which generates the greatest thrust for the least power. The flapping motion is approximated by pitching plates while periodic contractions are approximated by clapping plates. A machine is constructed to operate in either a flapping or a clapping mode between Reynolds numbers 1,880 and 11,260 based on the average plate tip velocity and span. The effect of the total sweep angle, total sweep time, plate flexibility, and duty cycle are investigated. The average thrust generated and power required per cycle are compared between the two modes when their total sweep angle and total sweep time are identical. In general, operating in the clapping mode required significantly more power to generate a similar thrust compared to the flapping mode. However, modifying the duty cycle for clapping caused the effectiveness to approach that of flapping with an unmodified duty cycle. These results suggest that flapping is the more effective propulsion mechanism within the range of Reynolds numbers tested. This work was supported by the Charyk Bio-inspired Laboratory at the California Institute of Technology, the National Science Foundation Graduate Research Fellowship under Grant No. DGE-1144469, and the Summer Undergraduate Research Fellowships program.

  6. Artificial Neural Network Based Rotor Capacitive Reactance Control for Energy Efficient Wound Rotor Induction Motor

    Directory of Open Access Journals (Sweden)

    K. Siva Kumar

    2012-01-01

    Full Text Available Problem statement: The Rotor reactance control by inclusion of external capacitance in the rotor circuit has been in recent research for improving the performances of Wound Rotor Induction Motor (WRIM. The rotor capacitive reactance is adjusted such that for any desired load torque the efficiency of the WRIM is maximized. The rotor external capacitance can be controlled using a dynamic capacitor in which the duty ratio is varied for emulating the capacitance value. This study presents a novel technique for tracking maximum efficiency point in the entire operating range of WRIM using Artificial Neural Network (ANN. The data for ANN training were obtained on a three phase WRIM with dynamic capacitor control and rotor short circuit at different speed and load torque values. Approach: A novel neural network model based on the back-propagation algorithm has been developed and trained in determining the maximum efficiency of the motor with no prior knowledge of the machine parameters. The input variables to the ANN are stator current (Is, Speed (N and Torque (Tm and the output variable is the duty ratio (D. Results: The target is pre-set and the accuracy of the ANN model is measured using Mean Square Error (MSE and R2 parameters. The result of R2 value of the proposed ANN model is found to be 0.99980. Conclusion: The optimal duty ratio and corresponding optimal rotor capacitance for improving the performances of the motor are predicted for low, medium and full loads by using proposed ANN model.

  7. Flap Endonuclease 1 Limits Telomere Fragility on the Leading Strand.

    Science.gov (United States)

    Teasley, Daniel C; Parajuli, Shankar; Nguyen, Mai; Moore, Hayley R; Alspach, Elise; Lock, Ying Jie; Honaker, Yuchi; Saharia, Abhishek; Piwnica-Worms, Helen; Stewart, Sheila A

    2015-06-12

    The existence of redundant replication and repair systems that ensure genome stability underscores the importance of faithful DNA replication. Nowhere is this complexity more evident than in challenging DNA templates, including highly repetitive or transcribed sequences. Here, we demonstrate that flap endonuclease 1 (FEN1), a canonical lagging strand DNA replication protein, is required for normal, complete leading strand replication at telomeres. We find that the loss of FEN1 nuclease activity, but not DNA repair activities, results in leading strand-specific telomere fragility. Furthermore, we show that FEN1 depletion-induced telomere fragility is increased by RNA polymerase II inhibition and is rescued by ectopic RNase H1 expression. These data suggest that FEN1 limits leading strand-specific telomere fragility by processing RNA:DNA hybrid/flap intermediates that arise from co-directional collisions occurring between the replisome and RNA polymerase. Our data reveal the first molecular mechanism for leading strand-specific telomere fragility and the first known role for FEN1 in leading strand DNA replication. Because FEN1 mutations have been identified in human cancers, our findings raise the possibility that unresolved RNA:DNA hybrid structures contribute to the genomic instability associated with cancer. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

  8. Flap Endonuclease 1 Limits Telomere Fragility on the Leading Strand*

    Science.gov (United States)

    Teasley, Daniel C.; Parajuli, Shankar; Nguyen, Mai; Moore, Hayley R.; Alspach, Elise; Lock, Ying Jie; Honaker, Yuchi; Saharia, Abhishek; Piwnica-Worms, Helen; Stewart, Sheila A.

    2015-01-01

    The existence of redundant replication and repair systems that ensure genome stability underscores the importance of faithful DNA replication. Nowhere is this complexity more evident than in challenging DNA templates, including highly repetitive or transcribed sequences. Here, we demonstrate that flap endonuclease 1 (FEN1), a canonical lagging strand DNA replication protein, is required for normal, complete leading strand replication at telomeres. We find that the loss of FEN1 nuclease activity, but not DNA repair activities, results in leading strand-specific telomere fragility. Furthermore, we show that FEN1 depletion-induced telomere fragility is increased by RNA polymerase II inhibition and is rescued by ectopic RNase H1 expression. These data suggest that FEN1 limits leading strand-specific telomere fragility by processing RNA:DNA hybrid/flap intermediates that arise from co-directional collisions occurring between the replisome and RNA polymerase. Our data reveal the first molecular mechanism for leading strand-specific telomere fragility and the first known role for FEN1 in leading strand DNA replication. Because FEN1 mutations have been identified in human cancers, our findings raise the possibility that unresolved RNA:DNA hybrid structures contribute to the genomic instability associated with cancer. PMID:25922071

  9. Microsurgery flap in endodontic surgery: case report.

    Science.gov (United States)

    Cecchetti, F; Ricci, S; DI Giorgio, G; Pisacane, C; Ottria, L

    2009-01-01

    In periodontal plastic surgery it is increasingly more evident the relavance of the protection of the gingival marginal anatomy through the realization of a conservative flap. Minimizing the recession of the treated tissue. A correct healing always needs to take into account the diameter and type of the suture and the time of removal from the wound.

  10. Pearls for perfecting the mastoid interpolation flap.

    Science.gov (United States)

    Justiniano, Hilda; Eisen, Daniel B

    2009-06-15

    Helical rim ear defects can present a reconstructive challenge to the Mohs surgeon. Multiple options exist including wedge excision, helical rim advancement flaps, bilobed flap, and grafts, to name a few. Wedge excision of the ear may result in a noticeable anteverted, smaller ear, and disrupts auricular cartilage with the possibility of chondritis and excess pain. Helical rim advancements can result in anteversion of the ear and a smaller lobule. Mastoid interpolation flaps, which are also called retroauricular to auricular flaps, can be a useful alternative in patients who are willing to return for a second procedure. They are easy to perform and can result in a highly aesthetic reconstruction in which the ear size and form are maintained. The donor skin comes from an area that is hidden from view and heals with minimal complications. We present our suggestions for performing these reconstructions. Ways to optimize results, potential pitfalls, and postoperative care instructions are discussed. Step by step videos are included with this manuscript.

  11. Flapping wing aerodynamics: from insects to vertebrates.

    Science.gov (United States)

    Chin, Diana D; Lentink, David

    2016-04-01

    More than a million insects and approximately 11,000 vertebrates utilize flapping wings to fly. However, flapping flight has only been studied in a few of these species, so many challenges remain in understanding this form of locomotion. Five key aerodynamic mechanisms have been identified for insect flight. Among these is the leading edge vortex, which is a convergent solution to avoid stall for insects, bats and birds. The roles of the other mechanisms - added mass, clap and fling, rotational circulation and wing-wake interactions - have not yet been thoroughly studied in the context of vertebrate flight. Further challenges to understanding bat and bird flight are posed by the complex, dynamic wing morphologies of these species and the more turbulent airflow generated by their wings compared with that observed during insect flight. Nevertheless, three dimensionless numbers that combine key flow, morphological and kinematic parameters - the Reynolds number, Rossby number and advance ratio - govern flapping wing aerodynamics for both insects and vertebrates. These numbers can thus be used to organize an integrative framework for studying and comparing animal flapping flight. Here, we provide a roadmap for developing such a framework, highlighting the aerodynamic mechanisms that remain to be quantified and compared across species. Ultimately, incorporating complex flight maneuvers, environmental effects and developmental stages into this framework will also be essential to advancing our understanding of the biomechanics, movement ecology and evolution of animal flight.

  12. [Treatment of organic waste gas by adsorption rotor].

    Science.gov (United States)

    Zhu, Run-Ye; Zheng, Liang-Wei; Mao, Yu-Bo; Wang, Jia-De

    2013-12-01

    The adsorption rotor is applicable to treating organic waste gases with low concentration and high air volume. The performance of adsorption rotor for purifying organic waste gases was investigated in this paper. Toluene was selected as the simulative gaseous pollutant and the adsorption rotor was packed with honeycomb modified 13X molecular sieves (M-13X). Experimental results of the fixed adsorption and the rotor adsorption were analyzed and compared. The results indicated that some information on the fixed adsorption was useful for the rotor adsorption. Integrating the characteristics of the adsorbents, waste gases and the structures of the rotor adsorption, the formulas on optimal rotor speed and cycle removal efficiency of the adsorption rotor were deduced, based on the mass and heat balances of the adsorbing process. The numerical results were in good agreement with the experimental data, which meant that the formulas on optimal rotor speed and cycle removal efficiency could be effectively applied in design and operation of the adsorption rotor.

  13. Integral Twist Actuation of Helicopter Rotor Blades for Vibration Reduction

    Science.gov (United States)

    Shin, SangJoon; Cesnik, Carlos E. S.

    2001-01-01

    Active integral twist control for vibration reduction of helicopter rotors during forward flight is investigated. The twist deformation is obtained using embedded anisotropic piezocomposite actuators. An analytical framework is developed to examine integrally-twisted blades and their aeroelastic response during different flight conditions: frequency domain analysis for hover, and time domain analysis for forward flight. Both stem from the same three-dimensional electroelastic beam formulation with geometrical-exactness, and axe coupled with a finite-state dynamic inflow aerodynamics model. A prototype Active Twist Rotor blade was designed with this framework using Active Fiber Composites as the actuator. The ATR prototype blade was successfully tested under non-rotating conditions. Hover testing was conducted to evaluate structural integrity and dynamic response. In both conditions, a very good correlation was obtained against the analysis. Finally, a four-bladed ATR system is built and tested to demonstrate its concept in forward flight. This experiment was conducted at NASA Langley Tansonic Dynamics Tunnel and represents the first-of-a-kind Mach-scaled fully-active-twist rotor system to undergo forward flight test. In parallel, the impact upon the fixed- and rotating-system loads is estimated by the analysis. While discrepancies are found in the amplitude of the loads under actuation, the predicted trend of load variation with respect to its control phase correlates well. It was also shown, both experimentally and numerically, that the ATR blade design has the potential for hub vibratory load reduction of up to 90% using individual blade control actuation. Using the numerical framework, system identification is performed to estimate the harmonic transfer functions. The linear time-periodic system can be represented by a linear time-invariant system under the three modes of blade actuation: collective, longitudinal cyclic, and lateral cyclic. A vibration

  14. [Vestibularly displaced flap with bone augmentation].

    Science.gov (United States)

    Bakalian, V L

    2009-01-01

    The aim of this study is to achieve esthetic gingival contours with the help of less traumatic mucogingival surgeries. 9 Patients were operated with horizontal deficiencies in 9 edentulous sites, planned to be restored with fixed partial dentures. In all cases there was lack of keratinized tissues. Temporary bridges were fabricated to all patients. Before surgery the bridges were removed and the abutment teeth were additionally cleaned with ultrasonic device. A horizontal incision was made from lingual (palatal) side between the abutment teeth, which was connected with two vertical releasing incisions to the mucogingival junction from the vestibular side. The horizontal incision was made on a distance 6-10 mm from the crest of the alveolar ridge. A partial thickness flap in the beginning 3-5 mm, then a full thickness flap up to the mucogingival junction, then a partial thickness flap was made. The flap was mobilized and displaced vestibularly. In the apical part the cortical bone was perforated, graft material was put and the flap was sutured. In all 9 cases the horizontal defect was partially or fully eliminated. The width of the keratinized tissues was also augmented in all cases. The postoperative healing was without complications, discomfort and painless. The donor sites also healed without complications. The application of Solcoseryl Dental Adhesive Paste 3 times a day for 7-10 days helped for painless healing of the donor site. The offered method of soft tissue and bone augmentation is effective in the treatment of horizontal defects of edentulous alveolar ridges of not big sizes. It makes possible to achieve esthetic results without traumatizing an additional donor-site.

  15. Recurrent squamous cell carcinoma of the scalp treated with serial free flaps

    DEFF Research Database (Denmark)

    Ikander, Peder; Sørensen, Jens Ahm

    2015-01-01

    dorsi flaps and one anterolateral thigh flap. No total flap loss was seen, but partial flap necrosis called for secondarily reconstruction. The final result was cosmetically acceptable and the patient is of good health. In conclusion, serial free microvascular flaps may be used with good results when...

  16. Reconstruction of the anterior floor of the mouth with the inferiorly based nasolabial flap

    NARCIS (Netherlands)

    van Wijk, MP; Damen, A; Nauta, JM; Lichtendahl, DHE; Dhar, BK

    2000-01-01

    The results of reconstruction of the anterior floor of the mouth, using 105 nasolabial flaps in 79 patients were reviewed in a retrospective study. Of those flaps, 82% healed uneventfully; flap survival was 95%. Considerable flap loss occurred in 5%. Primary dehiscence was observed in 5% of all flap

  17. Rotor-rotor interaction for counter-rotating fans. Part 1: Three-dimensional flowfield measurements

    Science.gov (United States)

    Shin, Hyoun-Woo; Whitfield, Charlotte E.; Wisler, David C.

    1994-11-01

    The rotor wake/vortex flowfield generated in a scale model simulator of General Electric's counter-rotating unducted fan (UDF) engine was investigated using three-dimensional hot-wire anemometry. The purpose was to obtain a set of benchmark experimental aerodynamic data defining the rotor wake and vortex structure, particularly in the tip region, and to relate this observed flow structure to its acoustic signature. The tests were conducted in a large, freejet anechoic chamber. Measurements of the three components of velocity were made at axial stations upstream and downstream of each rotor for conditions that simulate takeoff, cutback, and approach power. Two different forward blade designs were evaluated. The tip vortices, the axial velocity defect in the vortex core, and differences in the interaction of the wakes and vortices generated by the forward and aft rotor are used to explain differences in noise generated by the two different rotor designs. Part 1 presents the three-dimensional flowfield measurements. Part 2 (aeroacoustic prediction and analysis), which will be presented later, will give an acoustic prediction using the measured data.

  18. Aerodynamic design of the National Rotor Testbed.

    Energy Technology Data Exchange (ETDEWEB)

    Kelley, Christopher Lee [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-10-01

    A new wind turbine blade has been designed for the National Rotor Testbed (NRT) project and for future experiments at the Scaled Wind Farm Technology (SWiFT) facility with a specific focus on scaled wakes. This report shows the aerodynamic design of new blades that can produce a wake that has similitude to utility scale blades despite the difference in size and location in the atmospheric boundary layer. Dimensionless quantities circulation, induction, thrust coefficient, and tip-speed-ratio were kept equal between rotor scales in region 2 of operation. The new NRT design matched the aerodynamic quantities of the most common wind turbine in the United States, the GE 1.5sle turbine with 37c model blades. The NRT blade design is presented along with its performance subject to the winds at SWiFT. The design requirements determined by the SWiFT experimental test campaign are shown to be met.

  19. The Dynamics of Rotor with Rubbing

    Directory of Open Access Journals (Sweden)

    Jerzy T. Sawicki

    1999-01-01

    characteristics of rub-induced rotor response, initial conditions, as well as appropriate ranges of system parameters. Of special interest are the changes in the apparent nonlinearity of the system dynamics as rubs are induced at different rotor speeds. In particular, starting with 2nd order sub/superharmonics, which are symptomatic of quadratic nonlinearity, progressively higher order polynomial behavior is excited, i.e., cubic, giving rise to 3rd order sub/superharmonics. As the speed is transitioned between such apparent nonlinearities, chaotic like behavior is induced because of the lack of whole or rational tone tuning between the apparent system frequency and the external source noise. The cause of such behavior will be discussed in detail along with the results of several parametric studies.

  20. CFD simulations of the MEXICO rotor

    DEFF Research Database (Denmark)

    Bechmann, Andreas; Sørensen, Niels N.; Zahle, Frederik

    2011-01-01

    The wake behind a wind turbine model is investigated using Computational Fluid Dynamics (CFD), and results are compared with measurements. The turbine investigated is the three‐bladed test rotor (D = 4.5 m) used in the Model Experiments in Controlled Conditions (MEXICO) wind tunnel experiment....... During the MEXICO experiment, particle image velocimetry measurements of the induction upstream and downstream of the rotor were performed for different operating conditions, giving a unique dataset to verify theoretical models and CFD models. The present paper first describes the efforts in reproducing...... the experimental results using the Reynold‐Averaged Navier‐Stokes method. Second, three‐dimensional airfoil characteristics are extracted that allow simulations with simpler wake models. Copyright © 2011 John Wiley & Sons, Ltd....