WorldWideScience

Sample records for nonlinear panel flutter

  1. Nonlinear panel flutter in a rarefied atmosphere - Aerodynamic shear stress effects

    Science.gov (United States)

    Resende, Hugo B.

    1991-01-01

    The panel flutter phenomenon is studied assuming free-molecule flow. This kind of analysis is relevant in the case of hypersonic flight vehicles traveling at high altitudes, especially in the leeward portion of the vehicle. In these conditions the aerodynamic shear can be expected to be considerably larger than the pressure at a given point, so that the effects of such a loading are incorporated into the structural model. This is accomplished by introducing distributed longitudinal and bending moment loads. The former can lead to buckling of the panel, with the second mode in the case of a simply-supported panel playing a important role, and becoming the dominant mode in the solution. The presence of equivalent springs in the longitudinal direction at the panel's ends also becomes of relative importance, even for the evaluation of the linear flutter parameter. Finally, the behavior of the system is studied in the presence of applied compressive forces, that is, classical buckling.

  2. New Look at Nonlinear Aerodynamics in Analysis of Hypersonic Panel Flutter

    Directory of Open Access Journals (Sweden)

    Dan Xie

    2017-01-01

    Full Text Available A simply supported plate fluttering in hypersonic flow is investigated considering both the airflow and structural nonlinearities. Third-order piston theory is used for nonlinear aerodynamic loading, and von Karman plate theory is used for modeling the nonlinear strain-displacement relation. The Galerkin method is applied to project the partial differential governing equations (PDEs into a set of ordinary differential equations (ODEs in time, which is then solved by numerical integration method. In observation of limit cycle oscillations (LCO and evolution of dynamic behaviors, nonlinear aerodynamic loading produces a smaller positive deflection peak and more complex bifurcation diagrams compared with linear aerodynamics. Moreover, a LCO obtained with the linear aerodynamics is mostly a nonsimple harmonic motion but when the aerodynamic nonlinearity is considered more complex motions are obtained, which is important in the evaluation of fatigue life. The parameters of Mach number, dynamic pressure, and in-plane thermal stresses all affect the aerodynamic nonlinearity. For a specific Mach number, there is a critical dynamic pressure beyond which the aerodynamic nonlinearity has to be considered. For a higher temperature, a lower critical dynamic pressure is required. Each nonlinear aerodynamic term in the full third-order piston theory is evaluated, based on which the nonlinear aerodynamic formulation has been simplified.

  3. Stability analysis of nonlinear autonomous systems - General theory and application to flutter

    Science.gov (United States)

    Smith, L. L.; Morino, L.

    1975-01-01

    The analysis makes use of a singular perturbation method, the multiple time scaling. Concepts of stable and unstable limit cycles are introduced. The solution is obtained in the form of an asymptotic expansion. Numerical results are presented for the nonlinear flutter of panels and airfoils in supersonic flow. The approach used is an extension of a method for analyzing nonlinear panel flutter reported by Morino (1969).

  4. Panel Flutter Emulation Using a Few Concentrated Forces

    Science.gov (United States)

    Dhital, Kailash; Han, Jae-Hung

    2018-04-01

    The objective of this paper is to study the feasibility of panel flutter emulation using a few concentrated forces. The concentrated forces are considered to be equivalent to aerodynamic forces. The equivalence is carried out using surface spline method and principle of virtual work. The structural modeling of the plate is based on the classical plate theory and the aerodynamic modeling is based on the piston theory. The present approach differs from the linear panel flutter analysis in scheming the modal aerodynamics forces with unchanged structural properties. The solutions for the flutter problem are obtained numerically using the standard eigenvalue procedure. A few concentrated forces were considered with an optimization effort to decide their optimal locations. The optimization process is based on minimizing the error between the flutter bounds from emulated and linear flutter analysis method. The emulated flutter results for the square plate of four different boundary conditions using six concentrated forces are obtained with minimal error to the reference value. The results demonstrated the workability and viability of using concentrated forces in emulating real panel flutter. In addition, the paper includes the parametric studies of linear panel flutter whose proper literatures are not available.

  5. Supersonic Panel Flutter Test Results for Flat Fiber-Glass Sandwich Panels with Foamed Cores

    Science.gov (United States)

    Tuovila, W. J.; Presnell, John G., Jr.

    1961-01-01

    Flutter tests have been made on flat panels having a 1/4 inch-thick plastic-foam core covered with thin fiber-glass laminates. The testing was done in the Langley Unitary Plan wind tunnel at Mach numbers from 1.76 t o 2.87. The flutter boundary for these panels was found to be near the flutter boundary of thin metal panels when compared on the basis of an equivalent panel stiffness. The results also demonstrated that the depth of the cavity behind the panel has a pronounced influence on flutter. Changing the cavity depth from 1 1/2 inches to 1/2 inch reduced the dynamic pressure at start of flutter by 40 percent. No flutter was obtained when the spacers on the back of the panel were against the bottom of the cavity.

  6. Nonlinear Characteristics of Randomly Excited Transonic Flutter

    DEFF Research Database (Denmark)

    Christiansen, Lasse Engbo; Lehn-Schiøler, Tue; Mosekilde, Erik

    2002-01-01

    . When this model is extended by the introduction of nonlinear terms, it can reproduce the subcritical Hopf bifurcation. We hereafter consider the effects of subjecting simplified versions of the model to random external excitations representing the fluctuations present in the airflow. These models can......The paper describes the effects of random external excitations on the onset and dynamical characteristics of transonic flutter (i.e. large-amplitude, self-sustained oscillations) for a high aspect ratio wing. Wind tunnel experiments performed at the National Aerospace Laboratory (NAL) in Japan have...

  7. Flutter and Thermal Buckling Analysis for Composite Laminated Panel Embedded with Shape Memory Alloy Wires in Supersonic Flow

    Directory of Open Access Journals (Sweden)

    Chonghui Shao

    2016-01-01

    Full Text Available The flutter and thermal buckling behavior of laminated composite panels embedded with shape memory alloy (SMA wires are studied in this research. The classical plate theory and nonlinear von-Karman strain-displacement relation are employed to investigate the aeroelastic behavior of the smart laminated panel. The thermodynamic behaviors of SMA wires are simulated based on one-dimensional Brinson SMA model. The aerodynamic pressure on the panel is described by the nonlinear piston theory. Nonlinear governing partial differential equations of motion are derived for the panel via the Hamilton principle. The effects of ply angle of the composite panel, SMA layer location and orientation, SMA wires temperature, volume fraction and prestrain on the buckling, flutter boundary, and amplitude of limit cycle oscillation of the panel are analyzed in detail.

  8. Preliminary Evaluation of Nonlinear Effects on TCA Flutter

    Science.gov (United States)

    Arslan, Alan E.; Hartwich, Peter M.; Baker, Myles L.

    1998-01-01

    The objective of this study is to investigate the effect of nonlinear aerodynamics, especially at high angles-of-attack with leading-edge separation, on the TCA flutter properties at transonic speeds. In order to achieve that objective, flutter simulations with Navier-Stokes CFD must be performed. To this end, time-marching Navier-Stokes solutions are computed for the TCA wing/body configuration at high angles-of-attack in transonic flight regimes. The approach is to perform non-linear flutter calculations on the TCA at two angles-of-attack, the first one being a case with attached flow (a=2.8 degrees) and the second one being a high angle-of-attack case with a wing leading edge vortex (a=12.11 degrees). Comparisons of the resulting histories and frequency damping information for both angles-of-attack will evaluate the impact of high-alpha aerodynamics on flutter.

  9. Nonlinear dynamics approach of modeling the bifurcation for aircraft wing flutter in transonic speed

    DEFF Research Database (Denmark)

    Matsushita, Hiroshi; Miyata, T.; Christiansen, Lasse Engbo

    2002-01-01

    The procedure of obtaining the two-degrees-of-freedom, finite dimensional. nonlinear mathematical model. which models the nonlinear features of aircraft flutter in transonic speed is reported. The model enables to explain every feature of the transonic flutter data of the wind tunnel tests...... conducted at National Aerospace Laboratory in Japan for a high aspect ratio wing. It explains the nonlinear features of the transonic flutter such as the subcritical Hopf bifurcation of a limit cycle oscillation (LCO), a saddle-node bifurcation, and an unstable limit cycle as well as a normal (linear...

  10. Environmental Effects on Flutter Characteristics of Laminated Composite Rectangular and Skew Panels

    Directory of Open Access Journals (Sweden)

    T.V.R. Chowdary

    1996-01-01

    Full Text Available A finite element method is presented for predicting the flutter response of laminated composite panels subjected to moisture concentration and temperature. The analysis accounts for material properties at elevated temperature and moisture concentration. The analysis is based on the first-order approximation to the linear piston theory and laminated plate theory that includes shear deformation. Both rectangular and skew panels are considered. Stability boundaries at moisture concentrations and temperatures for various lamination schemes and boundary conditions are discussed.

  11. An efficient iterative model reduction method for aeroviscoelastic panel flutter analysis in the supersonic regime

    Science.gov (United States)

    Cunha-Filho, A. G.; Briend, Y. P. J.; de Lima, A. M. G.; Donadon, M. V.

    2018-05-01

    The flutter boundary prediction of complex aeroelastic systems is not an easy task. In some cases, these analyses may become prohibitive due to the high computational cost and time associated with the large number of degrees of freedom of the aeroelastic models, particularly when the aeroelastic model incorporates a control strategy with the aim of suppressing the flutter phenomenon, such as the use of viscoelastic treatments. In this situation, the use of a model reduction method is essential. However, the construction of a modal reduction basis for aeroviscoelastic systems is still a challenge, owing to the inherent frequency- and temperature-dependent behavior of the viscoelastic materials. Thus, the main contribution intended for the present study is to propose an efficient and accurate iterative enriched Ritz basis to deal with aeroviscoelastic systems. The main features and capabilities of the proposed model reduction method are illustrated in the prediction of flutter boundary for a thin three-layer sandwich flat panel and a typical aeronautical stiffened panel, both under supersonic flow.

  12. Aerothermoelastic analysis of panel flutter based on the absolute nodal coordinate formulation

    Energy Technology Data Exchange (ETDEWEB)

    Abbas, Laith K., E-mail: laithabbass@yahoo.com; Rui, Xiaoting, E-mail: ruixt@163.com [Nanjing University of Science and Technology, Institute of Launch Dynamics (China); Marzocca, Piergiovanni, E-mail: pmarzocc@clarkson.edu [Clarkson University, Mechanical and Aeronautical Engineering Department (United States)

    2015-02-15

    Panels of reentry vehicles are subjected to a wide range of flow conditions during ascent and reentry phases. The flow can vary from subsonic continuum flow to hypersonic rarefied flow with wide ranging dynamic pressure and associated aerodynamic heating. One of the main design considerations is the assurance of safety against panel flutter under the flow conditions characterized by sever thermal environment. This paper deals with supersonic/hypersonic flutter analysis of panels exposed to a temperature field. A 3-D rectangular plate element of variable thickness based on absolute nodal coordinate formulation (ANCF) has been developed for the structural model and subjected to an assumed thermal profile that can result from any residual heat seeping into the metallic panels through the thermal protection systems. A continuum mechanics approach for the definition of the elastic forces within the finite element is considered. Both shear strain and transverse normal strain are taken into account. The aerodynamic force is evaluated by considering the first-order piston theory to linearize the potential flow and is coupled with the structural model to account for pressure loading. A provision is made to take into account the effect of arbitrary flow directions with respect to the panel edges. Aerothermoelastic equations using ANCF are derived and solved numerically. Values of critical dynamic pressure are obtained by a modal approach, in which the mode shapes are obtained by ANCF. A detailed parametric study is carried out to observe the effects of different temperature loadings, flow angle directions, and aspect ratios on the flutter boundary.

  13. Aerothermoelastic analysis of panel flutter based on the absolute nodal coordinate formulation

    International Nuclear Information System (INIS)

    Abbas, Laith K.; Rui, Xiaoting; Marzocca, Piergiovanni

    2015-01-01

    Panels of reentry vehicles are subjected to a wide range of flow conditions during ascent and reentry phases. The flow can vary from subsonic continuum flow to hypersonic rarefied flow with wide ranging dynamic pressure and associated aerodynamic heating. One of the main design considerations is the assurance of safety against panel flutter under the flow conditions characterized by sever thermal environment. This paper deals with supersonic/hypersonic flutter analysis of panels exposed to a temperature field. A 3-D rectangular plate element of variable thickness based on absolute nodal coordinate formulation (ANCF) has been developed for the structural model and subjected to an assumed thermal profile that can result from any residual heat seeping into the metallic panels through the thermal protection systems. A continuum mechanics approach for the definition of the elastic forces within the finite element is considered. Both shear strain and transverse normal strain are taken into account. The aerodynamic force is evaluated by considering the first-order piston theory to linearize the potential flow and is coupled with the structural model to account for pressure loading. A provision is made to take into account the effect of arbitrary flow directions with respect to the panel edges. Aerothermoelastic equations using ANCF are derived and solved numerically. Values of critical dynamic pressure are obtained by a modal approach, in which the mode shapes are obtained by ANCF. A detailed parametric study is carried out to observe the effects of different temperature loadings, flow angle directions, and aspect ratios on the flutter boundary

  14. Flutter analysis of an airfoil with nonlinear damping using equivalent linearization

    Directory of Open Access Journals (Sweden)

    Chen Feixin

    2014-02-01

    Full Text Available The equivalent linearization method (ELM is modified to investigate the nonlinear flutter system of an airfoil with a cubic damping. After obtaining the linearization quantity of the cubic nonlinearity by the ELM, an equivalent system can be deduced and then investigated by linear flutter analysis methods. Different from the routine procedures of the ELM, the frequency rather than the amplitude of limit cycle oscillation (LCO is chosen as an active increment to produce bifurcation charts. Numerical examples show that this modification makes the ELM much more efficient. Meanwhile, the LCOs obtained by the ELM are in good agreement with numerical solutions. The nonlinear damping can delay the occurrence of secondary bifurcation. On the other hand, it has marginal influence on bifurcation characteristics or LCOs.

  15. Flutter analysis of an airfoil with multiple nonlinearities and uncertainties

    Directory of Open Access Journals (Sweden)

    Haitao Liao

    2013-09-01

    Full Text Available An original method for calculating the limit cycle oscillations of nonlinear aero-elastic system is presented. The problem of determining the maximum vibration amplitude of limit cycle is transformed into a nonlinear optimization problem. The harmonic balance method and the Floquet theory are selected to construct the general nonlinear equality and inequality constraints. The resulting constrained maximization problem is then solved by using the MultiStart algorithm. Finally, the proposed approach is validated and used to analyse the limit cycle oscillations of an airfoil with multiple nonlinearities and uncertainties. Numerical examples show that the coexistence of multiple nonlinearities may lead to low amplitude limit cycle oscillation.

  16. A parametric study on supersonic/hypersonic flutter behavior of aero-thermo-elastic geometrically imperfect curved skin panel

    NARCIS (Netherlands)

    Abbas, L.K.; Rui, X.; Marzocca, P.; Abdalla, M.; De Breuker, R.

    2011-01-01

    In this paper, the effect of the system parameters on the flutter of a curved skin panel forced by a supersonic/hypersonic unsteady flow is numerically investigated. The aeroelastic model investigated includes the third-order piston theory aerodynamics for modeling the flow-induced forces and the

  17. Active control law design for flutter suppression and gust alleviation of a panel with piezoelectric actuators

    International Nuclear Information System (INIS)

    Ahmad Fazelzadeh, S; Mohammad Jafari, S

    2008-01-01

    This paper presents an active optimal integral/feedforward control for a supersonic panel under gust disturbance effects with piezoelectric actuators. Classical laminate theory with induced strain actuation and a generalized form of Hamilton's principle are used to formulate the governing equations of motion. The total charge developed on the sensor layer is calculated from the direct piezoelectric equation. The piezoelectric sensor distributed output is also integrated, since the output voltage is dependent on the integrated strain rates over the sensor area. Aerodynamic modeling is accomplished by first-order piston theory with gust velocity effects. The model reduction is performed to the state space system of equations for the control design and the time domain simulation. Moreover, the disturbance dynamics are modeled through the addition to the equations of motion for various conditions. The optimal control problem is set up to minimize the panel deflection using a linear quadratic regulator (LQR). Using an integral control model as a part of the feedback loop, together with a feedforward of the disturbances, greatly enhances the transient response, and the steady state error characteristics of this system are observed. Also, parametric studies for three piezoelectric actuator configurations are demonstrated. Simulation results show that the controller model is effective for flutter suppression and gust alleviation for various piezo configurations

  18. Influence of magnetic flutter on tearing growth in linear and nonlinear theory

    Science.gov (United States)

    Kreifels, L.; Hornsby, W. A.; Weikl, A.; Peeters, A. G.

    2018-06-01

    Recent simulations of tearing modes in turbulent regimes show an unexpected enhancement in the growth rate. In this paper the effect is investigated analytically. The enhancement is linked to the influence of turbulent magnetic flutter, which is modelled by diffusion terms in magnetohydrodynamics (MHD) momentum balance and Ohm’s law. Expressions for the linear growth rate as well as the island width in nonlinear theory for small amplitudes are derived. The results indicate an enhanced linear growth rate and a larger linear layer width compared with resistive MHD. Also the island width in the nonlinear regime grows faster in the diffusive model. These observations correspond well to simulations in which the effect of turbulence on the magnetic island width and tearing mode growth is analyzed.

  19. Optimal locations of piezoelectric patches for supersonic flutter control of honeycomb sandwich panels, using the NSGA-II method

    International Nuclear Information System (INIS)

    Nezami, M; Gholami, B

    2016-01-01

    The active flutter control of supersonic sandwich panels with regular honeycomb interlayers under impact load excitation is studied using piezoelectric patches. A non-dominated sorting-based multi-objective evolutionary algorithm, called non-dominated sorting genetic algorithm II (NSGA-II) is suggested to find the optimal locations for different numbers of piezoelectric actuator/sensor pairs. Quasi-steady first order supersonic piston theory is employed to define aerodynamic loading and the p-method is applied to find the flutter bounds. Hamilton’s principle in conjunction with the generalized Fourier expansions and Galerkin method are used to develop the dynamical model of the structural systems in the state-space domain. The classical Runge–Kutta time integration algorithm is then used to calculate the open-loop aeroelastic response of the system. The maximum flutter velocity and minimum voltage applied to actuators are calculated according to the optimal locations of piezoelectric patches obtained using the NSGA-II and then the proportional feedback is used to actively suppress the closed loop system response. Finally the control effects, using the two different controllers, are compared. (paper)

  20. Interaction of a Mach 2.25 turbulent boundary layer with a fluttering panel using direct numerical simulation

    Science.gov (United States)

    Bodony, Daniel; Ostoich, Christopher; Geubelle, Philippe

    2013-11-01

    The interaction between a thin metallic panel and a Mach 2.25 turbulent boundary layer is investigated using a direct numerical simulation approach for coupled fluid-structure problems. The solid solution uses a finite-strain, finite-deformation formulation, while the direct numerical simulation of the boundary layer uses a finite-difference compressible Navier-Stokes solver. The initially laminar boundary layer contains low amplitude unstable eigenmodes that grow in time and excite traveling bending waves in the panel. As the boundary layer transitions to a fully turbulent state, with Reθ ~ 1200 , the panel's bending waves coalesce into a standing wave pattern exhibiting flutter with a final amplitude approximately 20 times the panel thickness. The corresponding panel deflection is roughly 25 wall units and reaches across the sonic line in the boundary layer profile. Once it reaches a limit cycle state, the panel/boundary layer system is examined in detail where it is found that turbulence statistics, especially the main Reynolds stress - , appear to be modified by the presence of the compliant panel, the effect of which is forgotten within one integral length downstream of the panel. Supported by the U.S. Air Force Research Laboratory Air Vehicles Directorate under contract number FA8650-06-2-3620.

  1. Flutter Sensitivity to Boundary Layer Thickness, Structural Damping, and Static Pressure Differential for a Shuttle Tile Overlay Repair Concept

    Science.gov (United States)

    Scott, Robert C.; Bartels, Robert E.

    2009-01-01

    This paper examines the aeroelastic stability of an on-orbit installable Space Shuttle patch panel. CFD flutter solutions were obtained for thick and thin boundary layers at a free stream Mach number of 2.0 and several Mach numbers near sonic speed. The effect of structural damping on these flutter solutions was also examined, and the effect of structural nonlinearities associated with in-plane forces in the panel was considered on the worst case linear flutter solution. The results of the study indicated that adequate flutter margins exist for the panel at the Mach numbers examined. The addition of structural damping improved flutter margins as did the inclusion of nonlinear effects associated with a static pressure difference across the panel.

  2. A weakly nonlinear model with exact coefficients for the fluttering and spiraling motions of buoyancy-driven bodies

    Science.gov (United States)

    Magnaudet, Jacques; Tchoufag, Joel; Fabre, David

    2015-11-01

    Gravity/buoyancy-driven bodies moving in a slightly viscous fluid frequently follow fluttering or helical paths. Current models of such systems are largely empirical and fail to predict several of the key features of their evolution, especially close to the onset of path instability. Using a weakly nonlinear expansion of the full set of governing equations, we derive a new generic reduced-order model of this class of phenomena based on a pair of amplitude equations with exact coefficients that drive the evolution of the first pair of unstable modes. We show that the predictions of this model for the style (eg. fluttering or spiraling) and characteristics (eg. frequency and maximum inclination angle) of path oscillations compare well with various recent data for both solid disks and air bubbles.

  3. Weakly Nonlinear Model with Exact Coefficients for the Fluttering and Spiraling Motion of Buoyancy-Driven Bodies

    Science.gov (United States)

    Tchoufag, Joël; Fabre, David; Magnaudet, Jacques

    2015-09-01

    Gravity- or buoyancy-driven bodies moving in a slightly viscous fluid frequently follow fluttering or helical paths. Current models of such systems are largely empirical and fail to predict several of the key features of their evolution, especially close to the onset of path instability. Here, using a weakly nonlinear expansion of the full set of governing equations, we present a new generic reduced-order model based on a pair of amplitude equations with exact coefficients that drive the evolution of the first pair of unstable modes. We show that the predictions of this model for the style (e.g., fluttering or spiraling) and characteristics (e.g., frequency and maximum inclination angle) of path oscillations compare well with various recent data for both solid disks and air bubbles.

  4. Supersonic flutter suppression of electrorheological fluid-based adaptive panels resting on elastic foundations using sliding mode control

    International Nuclear Information System (INIS)

    Hasheminejad, Seyyed M; Nezami, M; Aryaee Panah, M E

    2012-01-01

    Brief reviews on suppressing panel flutter vibrations by various active control strategies as well as utilization tunable electrorheological fluids (ERFs) for vibration control of structural systems are presented. Active suppression of the supersonic flutter motion of a simply supported sandwich panel with a tunable ERF interlayer, and coupled to an elastic foundation, is subsequently investigated. The structural formulation is based on the classical beam theory along with the Winkler–Pasternak foundation model, the ER fluid core is modeled as a first-order Kelvin–Voigt material, and the quasi-steady first-order supersonic piston theory is employed to describe the aerodynamic loading. Hamilton’s principle is used to derive a set of fully coupled dynamic equations of motion. The generalized Fourier expansions in conjunction with the Galerkin method are then employed to formulate the governing equations in the state space domain. The critical dynamic pressures at which unstable panel oscillations (coalescence of eigenvalues) occur are obtained via the p-method for selected applied electric field strengths (E = 0,2,4 kV mm −1 ). The classical Runge–Kutta time integration algorithm is subsequently used to calculate the open-loop aeroelastic response of the system in various basic loading configurations (i.e. uniformly distributed blast, gust, sonic boom, and step loads), with or without an interacting soft/stiff elastic foundation. Finally, a sliding mode control synthesis (SMC) involving the first six natural modes of the structural system is set up to actively suppress the closed-loop system response in supersonic flight conditions and under the imposed excitations. Simulation results demonstrate performance, effectiveness, and insensitivity with respect to the spillover of the proposed SMC-based control system. Limiting cases are considered and good agreements with the data available in the literature as well as with the computations made by using the

  5. On One Means of Hard Excitation of Oscillations in Nonlinear Flutter Systems

    Directory of Open Access Journals (Sweden)

    S. D. Glyzin

    2014-01-01

    Full Text Available Considered are so-called finite-dimensional flutter systems, i.e. systems of ordinary differential equations, arising from Galerkin approximations of certain boundary value problems of aeroelasticity theory as well as from a number of radiophysics applications. We study small oscillations of these equations in case of 1 : 3 resonance. By combining analytical and numerical methods, it is concluded that the mentioned resonance can cause a hard excitation of oscillations. Namely, for flutter systems shown is the possibility of coexistence, along with the stable zero state, of stable invariant tori of arbitrary finite dimension as well as chaotic attractors.

  6. Suppression of panel flutter of near-space aircraft based on non-probabilistic reliability theory

    Directory of Open Access Journals (Sweden)

    Ye-Wei Zhang

    2016-03-01

    Full Text Available The vibration active control of the composite panels with the uncertain parameters in the hypersonic flow is studied using the non-probabilistic reliability theory. Using the piezoelectric patches as active control actuators, dynamic equations of panel are established by finite element method and Hamilton’s principle. And the control model of panel with uncertain parameters is obtained. According to the non-probabilistic reliability index, and besides being based on H∞ robust control theory and non-probabilistic reliability theory, the non-probabilistic reliability performance function is given. Moreover, the relationships between the robust controller and H∞ performance index and reliability are established. Numerical results show that the control method under the influence of reliability, H∞ performance index, and approaching velocity is effective to the vibration suppression of panel in the whole interval of uncertain parameters.

  7. Non-linear Behavior of Curved Sandwich Panels

    DEFF Research Database (Denmark)

    Berggreen, Carl Christian; Jolma, P.; Karjalainen, J. P.

    2003-01-01

    In this paper the non-linear behavior of curved sandwich panels is investigated both numerically and experimentally. Focus is on various aspects of finite element modeling and calculation procedures. A simply supported, singly curved, CFRP/PVC sandwich panel is analyzed under uniform pressure loa...

  8. Flutter and limit cycle oscillation suppression using linear and nonlinear tuned vibration absorbers

    OpenAIRE

    Verstraelen, Edouard; Kerschen, Gaëtan; Dimitriadis, Grigorios

    2017-01-01

    Aircraft are more than ever pushed to their limits for performance reasons. Consequently, they become increasingly nonlinear and they are more prone to undergo aeroelastic limit cycle oscillations. Structural nonlinearities affect aircraft such as the F-16, which can undergo store-induced limit cycle oscillations (LCOs). Furthermore, transonic buzz can lead to LCOs because of moving shock waves in transonic flight conditions on many aircraft. This study presents a numerical investigation o...

  9. ATRIAL FLUTTER*

    African Journals Online (AJOL)

    1971-01-02

    Jan 2, 1971 ... Athero- sclerotic cardiovascular disease was present in 23 patients, of whom 3 had ... primum defect, atrial flutter was precipitated by cardiac catheterization. ..... Heart J., 70, 505. UNDERSTANDING REACTIVE DEPRESSION*

  10. Estimation of Nonlinear Dynamic Panel Data Models with Individual Effects

    Directory of Open Access Journals (Sweden)

    Yi Hu

    2014-01-01

    Full Text Available This paper suggests a generalized method of moments (GMM based estimation for dynamic panel data models with individual specific fixed effects and threshold effects simultaneously. We extend Hansen’s (Hansen, 1999 original setup to models including endogenous regressors, specifically, lagged dependent variables. To address the problem of endogeneity of these nonlinear dynamic panel data models, we prove that the orthogonality conditions proposed by Arellano and Bond (1991 are valid. The threshold and slope parameters are estimated by GMM, and asymptotic distribution of the slope parameters is derived. Finite sample performance of the estimation is investigated through Monte Carlo simulations. It shows that the threshold and slope parameter can be estimated accurately and also the finite sample distribution of slope parameters is well approximated by the asymptotic distribution.

  11. Atrial fibrillation or flutter

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/000184.htm Atrial fibrillation or flutter To use the sharing features on this page, please enable JavaScript. Atrial fibrillation or flutter is a common type of abnormal ...

  12. Localized Effects in the Nonlinear Behavior of Sandwich Panels with a Transversely Flexible Core

    DEFF Research Database (Denmark)

    Frostig, Y.; Thomsen, Ole Thybo

    2005-01-01

    This paper presents the results of an investigation of the role of localized effects within the geometrically nonlinear domain on structural sandwich panels with a "compliant" core. Special emphasis is focused on the nonlinear response near concentrated loads and stiffened core regions. The adopted...... nonlinear analysis approach incorporates the effects of the vertical flexibility of the core, and it is based on the approach of the High-order Sandwich Panel Theory (HSAPT). The results demonstrate that the effects of localized loads, when taken into the geometrically nonlinear domain, change the response...... of the panel from a strength problem controlled by stress constraints into a stability problem with unstable limit point behavior when force-controlled loads are applied. The stability problem emerge as the nonlinear response develops with the formation of a small number of buckling waves in the compressed...

  13. On the numerical simulation of flutter and its suppression by active control

    International Nuclear Information System (INIS)

    Dong, B.; Mook, D.T.

    1994-01-01

    The classic problem of predicting the motion (flutter) of a rigid airfoil mounted on an elastic support in a steady freestream is revisited. In the classic approach, the equations of motion were linearized, the supports were linear springs, the motion was assumed to be periodic, the aerodynamic loads were predicted by Wagner's function, and the solution was obtained in the so-called frequency domain. In the present approach, the equations of motion are in their fully nonlinear form, the supports may be nonlinear springs, the motion is not assumed to be periodic, the loads are predicted by a general unsteady vorticity-panel method, and the solution is obtained in the so-called time domain. After it is demonstrated that the present approach predicts the onset of flutter and the post-flutter behavior for flat-plate as well as thick airfoils, the airfoil -is modified by the addition of a flap at the trailing edge. The flap is part of an actively controlled servomechanism, and it is demonstrated that flutter can be readily controlled with very little effort by a variety of feedback-control laws. In the present approach, emphasis is placed on considering the airfoil, its supports, the flowing air and the control/servo mechanism collectively to be a single dynamic system. All the equations of motion and control laws are solved simultaneously and interactively; thus, complete interactions among the various subsystems are captured. The present simulation of an oscillating airfoil provides some characteristics of the flutter phenomenon that were missed in previous studies: for example, it is shown that, in the absence of flaps, the motion in heave (the translational part of the motion) is responsible for adding energy to (exciting) the structural subsystem while the motion in pitch is responsible for extracting energy from (damping) the structural subsystem. Below the critical speed, there is more dissipation than excitation and hence all initial disturbances decay

  14. Efficient Estimation of Non-Linear Dynamic Panel Data Models with Application to Smooth Transition Models

    DEFF Research Database (Denmark)

    Gørgens, Tue; Skeels, Christopher L.; Wurtz, Allan

    This paper explores estimation of a class of non-linear dynamic panel data models with additive unobserved individual-specific effects. The models are specified by moment restrictions. The class includes the panel data AR(p) model and panel smooth transition models. We derive an efficient set...... of moment restrictions for estimation and apply the results to estimation of panel smooth transition models with fixed effects, where the transition may be determined endogenously. The performance of the GMM estimator, both in terms of estimation precision and forecasting performance, is examined in a Monte...

  15. Nonlinear Analysis and Post-Test Correlation for a Curved PRSEUS Panel

    Science.gov (United States)

    Gould, Kevin; Lovejoy, Andrew E.; Jegley, Dawn; Neal, Albert L.; Linton, Kim, A.; Bergan, Andrew C.; Bakuckas, John G., Jr.

    2013-01-01

    The Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS) concept, developed by The Boeing Company, has been extensively studied as part of the National Aeronautics and Space Administration's (NASA s) Environmentally Responsible Aviation (ERA) Program. The PRSEUS concept provides a light-weight alternative to aluminum or traditional composite design concepts and is applicable to traditional-shaped fuselage barrels and wings, as well as advanced configurations such as a hybrid wing body or truss braced wings. Therefore, NASA, the Federal Aviation Administration (FAA) and The Boeing Company partnered in an effort to assess the performance and damage arrestments capabilities of a PRSEUS concept panel using a full-scale curved panel in the FAA Full-Scale Aircraft Structural Test Evaluation and Research (FASTER) facility. Testing was conducted in the FASTER facility by subjecting the panel to axial tension loads applied to the ends of the panel, internal pressure, and combined axial tension and internal pressure loadings. Additionally, reactive hoop loads were applied to the skin and frames of the panel along its edges. The panel successfully supported the required design loads in the pristine condition and with a severed stiffener. The panel also demonstrated that the PRSEUS concept could arrest the progression of damage including crack arrestment and crack turning. This paper presents the nonlinear post-test analysis and correlation with test results for the curved PRSEUS panel. It is shown that nonlinear analysis can accurately calculate the behavior of a PRSEUS panel under tension, pressure and combined loading conditions.

  16. Nonlinear vibration and radiation from a panel with transition to chaos induced by acoustic waves

    Science.gov (United States)

    Maestrello, Lucio; Frendi, Abdelkader; Brown, Donald E.

    1992-01-01

    The dynamic response of an aircraft panel forced at resonance and off-resonance by plane acoustic waves at normal incidence is investigated experimentally and numerically. Linear, nonlinear (period doubling) and chaotic responses are obtained by increasing the sound pressure level of the excitation. The response time history is sensitive to the input level and to the frequency of excitation. The change in response behavior is due to a change in input conditions, triggered either naturally or by modulation of the bandwidth of the incident waves. Off-resonance, bifurcation is diffused and difficult to maintain, thus the panel response drifts into a linear behavior. The acoustic pressure emanated by the panel is either linear or nonlinear as is the vibration response. The nonlinear effects accumulate during the propagation with distance. Results are also obtained on the control of the panel response using damping tape on aluminum panel and using a graphite epoxy panel having the same size and weight. Good agreement is obtained between the experimental and numerical results.

  17. Homogenized global nonlinear constitutive model for RC panels under cyclic loadings

    International Nuclear Information System (INIS)

    Huguet, Miquel; Voldoire, Francois; Kotronis, Panagiotis; Erlicher, Silvano

    2014-01-01

    A new nonlinear stress resultant global constitutive model for RC panels is presented. Concrete damage, concrete stress transfer at cracks and bond-slip stress are the main nonlinear effects identified at the local scale that constitute the basis for the construction of the stress resultant global model through an analytical homogenization technique. The closed form solution is obtained using general functions for the previous phenomena. (authors)

  18. Nonlinear FE analysis of reinforced concrete panels subjected to in-plane force

    International Nuclear Information System (INIS)

    Lee, H. P.; Lee, S. J.; Jun, Y. S.; Su, J. M.

    2003-01-01

    Reinforced concrete structures subjected to in-plane force exhibit strong nonlinear behaviour due to complex material properties, cracks, interactions between concrete and steel and shear transfer exists in crack surface. Especially if there is crack formations, nonlinear behaviour increases. Thus the prediction of nonlinear behaviour of reinforced concrete includes failure or crushing is very difficult task. Various constitutive equations for concrete stress-strain relationship to predict nonlinear behaviour of reinforced concrete have been proposed. But the study for reinforced concrete analysis model using plastic material model is still demanded. So the purpose of this research is to formulate standard 8-node shell element using plasticity material model for concrete and to analyze nonlinear behaviour of RC panel subjected to in-plane force

  19. Nonlinear Modeling and Identification of an Aluminum Honeycomb Panel with Multiple Bolts

    Directory of Open Access Journals (Sweden)

    Yongpeng Chu

    2016-01-01

    Full Text Available This paper focuses on the nonlinear dynamics modeling and parameter identification of an Aluminum Honeycomb Panel (AHP with multiple bolted joints. Finite element method using eight-node solid elements is exploited to model the panel and the bolted connection interface as a homogeneous, isotropic plate and as a thin layer of nonlinear elastic-plastic material, respectively. The material properties of a thin layer are defined by a bilinear elastic plastic model, which can describe the energy dissipation and softening phenomena in the bolted joints under nonlinear states. Experimental tests at low and high excitation levels are performed to reveal the dynamic characteristics of the bolted structure. In particular, the linear material parameters of the panel are identified via experimental tests at low excitation levels, whereas the nonlinear material parameters of the thin layer are updated by using the genetic algorithm to minimize the residual error between the measured and the simulation data at a high excitation level. It is demonstrated by comparing the frequency responses of the updated FEM and the experimental system that the thin layer of bilinear elastic-plastic material is very effective for modeling the nonlinear joint interface of the assembled structure with multiple bolts.

  20. The non-linear link between electricity consumption and temperature in Europe: A threshold panel approach

    Energy Technology Data Exchange (ETDEWEB)

    Bessec, Marie [CGEMP, Universite Paris-Dauphine, Place du Marechal de Lattre de Tassigny Paris (France); Fouquau, Julien [LEO, Universite d' Orleans, Faculte de Droit, d' Economie et de Gestion, Rue de Blois, BP 6739, 45067 Orleans Cedex 2 (France)

    2008-09-15

    This paper investigates the relationship between electricity demand and temperature in the European Union. We address this issue by means of a panel threshold regression model on 15 European countries over the last two decades. Our results confirm the non-linearity of the link between electricity consumption and temperature found in more limited geographical areas in previous studies. By distinguishing between North and South countries, we also find that this non-linear pattern is more pronounced in the warm countries. Finally, rolling regressions show that the sensitivity of electricity consumption to temperature in summer has increased in the recent period. (author)

  1. Geared-elevator flutter study. [transonic flutter characteristics of empennage

    Science.gov (United States)

    Ruhlin, C. L.; Doggett, R. V., Jr.; Gregory, R. A.

    1976-01-01

    The paper describes an experimental and analytical study of the transonic flutter characteristics of an empennage flutter model having an all-movable horizontal tail with a geared elevator. Two configurations were flutter tested: one with a geared elevator and one with a locked elevator with the model cantilever-mounted on a sting in the wind tunnel. The geared-elevator configuration fluttered experimentally at about 20% higher dynamic pressures than the locked-elevator configuration. The experimental flutter boundary was nearly flat at transonic speeds for both configurations. It was found that an analysis which treated the elevator as a discrete surface predicted flutter dynamic pressure levels better than analyses which treated the stabilizer and elevator as a warped surface. Warped-surface methods, however, predicted more closely the experimental flutter frequencies and Mach number trends.

  2. Macroeconomic effects on mortality revealed by panel analysis with nonlinear trends.

    Science.gov (United States)

    Ionides, Edward L; Wang, Zhen; Tapia Granados, José A

    2013-10-03

    Many investigations have used panel methods to study the relationships between fluctuations in economic activity and mortality. A broad consensus has emerged on the overall procyclical nature of mortality: perhaps counter-intuitively, mortality typically rises above its trend during expansions. This consensus has been tarnished by inconsistent reports on the specific age groups and mortality causes involved. We show that these inconsistencies result, in part, from the trend specifications used in previous panel models. Standard econometric panel analysis involves fitting regression models using ordinary least squares, employing standard errors which are robust to temporal autocorrelation. The model specifications include a fixed effect, and possibly a linear trend, for each time series in the panel. We propose alternative methodology based on nonlinear detrending. Applying our methodology on data for the 50 US states from 1980 to 2006, we obtain more precise and consistent results than previous studies. We find procyclical mortality in all age groups. We find clear procyclical mortality due to respiratory disease and traffic injuries. Predominantly procyclical cardiovascular disease mortality and countercyclical suicide are subject to substantial state-to-state variation. Neither cancer nor homicide have significant macroeconomic association.

  3. Sustainable Education: Analyzing the Determinants of University Student Dropout by Nonlinear Panel Data Models

    Directory of Open Access Journals (Sweden)

    Donggeun Kim

    2018-03-01

    Full Text Available University dropout is a serious problem. It affects not only the individual who drops out but also the university and society. However, most previous studies have focused only on the subjective/individual level. University dropout is a very important issue in South Korea, but it has not received much research attention so far. This study examined the possible causes of university dropout in South Korea at the aggregate level, focusing on four fundamental categories: students, resources, faculty, and university characteristics. Three-year balanced panel data from 2013 to 2015 were constructed and estimated by using nonlinear panel data models. The findings show that cost and burden for students, financial resources, qualitative and quantitative features of faculty, and type/size of the university have significant effects on university dropout.

  4. Empirical Flutter Prediction Method.

    Science.gov (United States)

    1988-03-05

    been used in this way to discover species or subspecies of animals, and to discover different types of voter or comsumer requiring different persuasions...respect to behavior or performance or response variables. Once this were done, corresponding clusters might be sought among descriptive or predictive or...jump in a response. The first sort of usage does not apply to the flutter prediction problem. Here the types of behavior are the different kinds of

  5. Impact damage detection in light composite sandwich panels using piezo-based nonlinear vibro-acoustic modulations

    International Nuclear Information System (INIS)

    Pieczonka, L; Ukowski, P; Klepka, A; Staszewski, W J; Uhl, T; Aymerich, F

    2014-01-01

    The nonlinear vibro-acoustic modulation technique is used for impact damage detection in light composite sandwich panels. The method utilizes piezo-based low-frequency vibration and high-frequency ultrasonic excitations. The work presented focuses on the analysis of modulation intensity. The results show that the method can be used for impact damage detection reliably separating damage-related from vibro-acoustic modulations from other intrinsic nonlinear modulations. (paper)

  6. Time domain simulation of the response of geometrically nonlinear panels subjected to random loading

    Science.gov (United States)

    Moyer, E. Thomas, Jr.

    1988-01-01

    The response of composite panels subjected to random pressure loads large enough to cause geometrically nonlinear responses is studied. A time domain simulation is employed to solve the equations of motion. An adaptive time stepping algorithm is employed to minimize intermittent transients. A modified algorithm for the prediction of response spectral density is presented which predicts smooth spectral peaks for discrete time histories. Results are presented for a number of input pressure levels and damping coefficients. Response distributions are calculated and compared with the analytical solution of the Fokker-Planck equations. RMS response is reported as a function of input pressure level and damping coefficient. Spectral densities are calculated for a number of examples.

  7. Nonlinear finite element formulation for analyzing shape memory alloy cylindrical panels

    International Nuclear Information System (INIS)

    Mirzaeifar, R; Shakeri, M; Sadighi, M

    2009-01-01

    In this paper, a general incremental displacement based finite element formulation capable of modeling material nonlinearities based on first-order shear deformation theory (FSDT) is developed for cylindrical shape memory alloy (SMA) shells. The Boyd–Lagoudas phenomenological model with polynomial hardening in conjunction with 3D incremental convex cutting plane explicit algorithm is implemented for preparing the SMA constitutive model in the finite element formulation. Several numerical examples are presented for demonstrating the performance of the proposed formulation in stress, deflection and phase transformation analysis of pseudoelastic behavior of shape memory cylindrical panels with various boundary conditions. Also, it is shown that the presented formulation can be implemented for studying plates and beams with rectangular cross section

  8. Surface Acoustic Wave Vibration Sensors for Measuring Aircraft Flutter

    Science.gov (United States)

    Wilson, William C.; Moore, Jason P.; Juarez, Peter D.

    2016-01-01

    Under NASA's Advanced Air Vehicles Program the Advanced Air Transport Technology (AATT) Project is investigating flutter effects on aeroelastic wings. To support that work a new method for measuring vibrations due to flutter has been developed. The method employs low power Surface Acoustic Wave (SAW) sensors. To demonstrate the ability of the SAW sensor to detect flutter vibrations the sensors were attached to a Carbon fiber-reinforced polymer (CFRP) composite panel which was vibrated at six frequencies from 1Hz to 50Hz. The SAW data was compared to accelerometer data and was found to resemble sine waves and match each other closely. The SAW module design and results from the tests are presented here.

  9. Applicability of a panel method, which includes nonlinear effects, to a forward-swept-wing aircraft

    Science.gov (United States)

    Ross, J. C.

    1984-01-01

    The ability of a lower order panel method VSAERO, to accurately predict the lift and pitching moment of a complete forward-swept-wing/canard configuration was investigated. The program can simulate nonlinear effects including boundary-layer displacement thickness, wake roll up, and to a limited extent, separated wakes. The predictions were compared with experimental data obtained using a small-scale model in the 7- by 10- Foot Wind Tunnel at NASA Ames Research Center. For the particular configuration under investigation, wake roll up had only a small effect on the force and moment predictions. The effect of the displacement thickness modeling was to reduce the lift curve slope slightly, thus bringing the predicted lift into good agreement with the measured value. Pitching moment predictions were also improved by the boundary-layer simulation. The separation modeling was found to be sensitive to user inputs, but appears to give a reasonable representation of a separated wake. In general, the nonlinear capabilities of the code were found to improve the agreement with experimental data. The usefullness of the code would be enhanced by improving the reliability of the separated wake modeling and by the addition of a leading edge separation model.

  10. Non-linear Dynamic Analysis of Steel Hollow I-core Sandwich Panel under Air Blast Loading

    Directory of Open Access Journals (Sweden)

    Asghar Vatani Oskouei

    2015-12-01

    Full Text Available In this paper, the non-linear dynamic response of novel steel sandwich panel with hollow I-core subjected to blast loading was studied. Special emphasis is placed on the evaluation of midpoint displacements and energy dissipation of the models. Several parameters such as boundary conditions, strain rate, mesh dependency and asymmetrical loading are considered in this study. The material and geometric non-linearities are also considered in the numerical simulation. The results obtained are compared with available experimental data to verify the developed FE model. Modeling techniques are described in detail. According to the results, sandwich panels with hollow I-core allowed more plastic deformation and energy dissipation and less midpoint displacement than conventional I-core sandwich panels and also equivalent solid plate with the same weight and material.

  11. An alternative to the flutter derivatives

    DEFF Research Database (Denmark)

    Andersen, Michael Styrk; Brandt, Anders

    A new simplified framework to study flutter and assess the full scale flutter wind speed is suggested. The flutter instability problem is reduced from a problem involving 8 flutter derivatives to only 4 coefficients. With this method it is possible to estimate the self-excited forces with increased...... precision by using stability diagrams. Furthermore, the physical transparency of the aerodynamic damping and stiffness terms is increased because the development in vertical and torsional damping and stiffness is analysed instead of flutter derivatives....

  12. Residual Strength Pressure Tests and Nonlinear Analyses of Stringer- and Frame-Stiffened Aluminum Fuselage Panels with Longitudinal Cracks

    Science.gov (United States)

    Young, Richard D.; Rouse, Marshall; Ambur, Damodar R.; Starnes, James H., Jr.

    1999-01-01

    The results of residual strength pressure tests and nonlinear analyses of stringer- and frame-stiffened aluminum fuselage panels with longitudinal cracks are presented. Two types of damage are considered: a longitudinal crack located midway between stringers, and a longitudinal crack adjacent to a stringer and along a row of fasteners in a lap joint that has multiple-site damage (MSD). In both cases, the longitudinal crack is centered on a severed frame. The panels are subjected to internal pressure plus axial tension loads. The axial tension loads are equivalent to a bulkhead pressure load. Nonlinear elastic-plastic residual strength analyses of the fuselage panels are conducted using a finite element program and the crack-tip-opening-angle (CTOA) fracture criterion. Predicted crack growth and residual strength results from nonlinear analyses of the stiffened fuselage panels are compared with experimental measurements and observations. Both the test and analysis results indicate that the presence of MSD affects crack growth stability and reduces the residual strength of stiffened fuselage shells with long cracks.

  13. A new arrangement with nonlinear sidewalls for tanker ship storage panels

    Science.gov (United States)

    Ketabdari, M. J.; Saghi, H.

    2013-03-01

    Sloshing phenomenon in a moving container is a complicated free surface flow problem. It has a wide range of engineering applications, especially in tanker ships and Liquefied Natural Gas (LNG) carriers. When the tank in these vehicles is partially filled, it is essential to be able to evaluate the fluid dynamic loads on tank perimeter. Different geometric shapes such as rectangular, cylindrical, elliptical, spherical and circular conical have been suggested for ship storage tanks by previous researchers. In this paper a numerical model is developed based on incompressible and inviscid fluid motion for the liquid sloshing phenomenon. The coupled BEM-FEM is used to solve the governing equations and nonlinear free surface boundary conditions. The results are validated for rectangular container using data obtained for a horizontal periodic sway motion. Using the results of this model a new arrangement of trapezoidal shapes with quadratic sidewalls is suggested for tanker ship storage panels. The suggested geometric shape not only has a maximum surrounded tank volume to the constant available volume, but also reduces the sloshing effects more efficiently than the existing geometric shapes.

  14. Thermoelectrically induced nonlinear free vibration analysis of piezo laminated composite conical shell panel with random fiber orientation

    Directory of Open Access Journals (Sweden)

    Lal Achchhe

    2017-09-01

    Full Text Available This paper presents the free vibration response of piezo laminated composite geometrically nonlinear conical shell panel subjected to a thermo-electrical loading. The temperature field is assumed to be a uniform distribution over the shell surface and through the shell thickness and the electric field is assumed to be the transverse component E2 only. The material properties are assumed to be independent of the temperature and the electric field. The basic formulation is based on higher order shear deformation plate theory (HSDT with von-Karman nonlinearity. A C0 nonlinear finite element method based on direct iterative approach is outlined and applied to solve nonlinear generalized eigenvalue problem. Parametric studies are carried out to examine the effect of amplitude ratios, stacking sequences, cone angles, piezoelectric layers, applied voltages, circumferential length to thickness ratios, change in temperatures and support boundary conditions on the nonlinear natural frequency of laminated conical shell panels. The present outlined approach has been validated with those available results in the literature.

  15. Dynamic relaxation method for nonlinear buckling analysis of moderately thick FG cylindrical panels with various boundary conditions

    Energy Technology Data Exchange (ETDEWEB)

    Golmakani, M. E.; Far, M. N. Sadraee; Moravej, M. [Dept. of Mechanical Engineering, Mashhad Branch, Islamic Azad University, Mashhad (Iran, Islamic Republic of)

    2016-12-15

    Using new approach proposed by Dynamic relaxation (DR) method, buckling analysis of moderately thick Functionally graded (FG) cylindrical panels subjected to axial compression is investigated for various boundary conditions. The mechanical properties of FG panel are assumed to vary continuously along the thickness direction by the simple rule of mixture and Mori-Tanaka model. The incremental form of nonlinear formulations are derived based on First-order shear deformation theory (FSDT) and large deflection von Karman equations. The DR method combined with the finite difference discretization technique is employed to solve the incremental form of equilibrium equations. The critical mechanical buckling load is determined based on compressive load-displacement curve by adding the incremental displacements in each load step to the displacements obtained from the previous ones. A detailed parametric study is carried out to investigate the influences of the boundary conditions, rule of mixture, grading index, radius-to-thickness ratio, length-to-radius ratio and panel angle on the mechanical buckling load. The results reveal that with increase of grading index the effect of radius-to-thickness ratio on the buckling load decreases. It is also observed that effect of distribution rules on the buckling load is dependent to the type of boundary conditions.

  16. A formalization of the flutter shutter

    Science.gov (United States)

    Tendero, Yohann; Rougé, Bernard; Morel, Jean-Michel

    2012-09-01

    Acquiring good quality images of moving objects by a digital camera remains a valid question. If the velocity of the photographed object is not known, it is virtually impossible to tune an optimal exposure time. For this reason the recent Agrawal et al. flutter shutter apparatus has generated much interest. In this communication, we propose a mathematical formalization of a general flutter shutter method, also permitting non-binary shutter sequences. Thanks to this formalization, the question of the optimal flutter shutter code can be defined and solved. The method gives analytic formulas for the best attainable SNR for the restored image. It also gives a way to compute optimal flutter shutter codes.

  17. Investigation of the Flutter Suppression by Fuzzy Logic Control for Hypersonic Wing

    Science.gov (United States)

    Li, Dongxu; Luo, Qing; Xu, Rui

    This paper presents a fundamental study of flutter characteristics and control performance of an aeroelastic system based on a two-dimensional double wedge wing in the hypersonic regime. Dynamic equations were established based on the modified third order nonlinear piston theory and some nonlinear structural effects are also included. A set of important parameters are observed. And then aeroelastic control law is designed to suppress the amplitude of the LCOs for the system in the sub/supercritical speed range by applying fuzzy logic control on the input of the deflection of the flap. The overall effects of the parameters on the aeroelastic system were outlined. Nonlinear aeroelastic responses in the open- and closed-loop system are obtained through numerical methods. The simulations show fuzzy logic control methods are effective in suppressing flutter and provide a smart approach for this complicated system.

  18. Investigations on precursor measures for aeroelastic flutter

    Science.gov (United States)

    Venkatramani, J.; Sarkar, Sunetra; Gupta, Sayan

    2018-04-01

    Wind tunnel experiments carried out on a pitch-plunge aeroelastic system in the presence of fluctuating flows reveal that flutter instability is presaged by a regime of intermittency. It is observed that as the flow speed gradually increases towards the flutter speed, there appears intermittent bursts of periodic oscillations which become more frequent as the wind speed increases and eventually the dynamics transition into fully developed limit cycle oscillations, marking the onset of flutter. The signature from these intermittent oscillations are exploited to develop measures that forewarn a transition to flutter and can serve as precursors. This study investigates a suite of measures that are obtained directly from the time history of measurements and are hence model independent. The dependence of these precursors on the size of the measured data set and the time required for their computation is investigated. These measures can be useful in structural health monitoring of aeroelastic structures.

  19. [Typical atrial flutter: Diagnosis and therapy].

    Science.gov (United States)

    Thomas, Dierk; Eckardt, Lars; Estner, Heidi L; Kuniss, Malte; Meyer, Christian; Neuberger, Hans-Ruprecht; Sommer, Philipp; Steven, Daniel; Voss, Frederik; Bonnemeier, Hendrik

    2016-03-01

    Typical, cavotricuspid-dependent atrial flutter is the most common atrial macroreentry tachycardia. The incidence of atrial flutter (typical and atypical forms) is age-dependent with 5/100,000 in patients less than 50 years and approximately 600/100,000 in subjects > 80 years of age. Concomitant heart failure or pulmonary disease further increases the risk of typical atrial flutter.Patients with atrial flutter may present with symptoms of palpitations, reduced exercise capacity, chest pain, or dyspnea. The risk of thromboembolism is probably similar to atrial fibrillation; therefore, the same antithrombotic prophylaxis is required in atrial flutter patients. Acutely symptomatic cases may be subjected to cardioversion or pharmacologic rate control to relieve symptoms. Catheter ablation of the cavotricuspid isthmus represents the primary choice in long-term therapy, associated with high procedural success (> 97 %) and low complication rates (0.5 %).This article represents the third part of a manuscript series designed to improve professional education in the field of cardiac electrophysiology. Mechanistic and clinical characteristics as well as management of isthmus-dependent atrial flutter are described in detail. Electrophysiological findings and catheter ablation of the arrhythmia are highlighted.

  20. Effects of large bending deflections on blade flutter limits

    Energy Technology Data Exchange (ETDEWEB)

    Kallesoee, Bjarne Skovmose; Hartvig Hansen, Morten

    2008-04-15

    The coupling of bending and torsion due to large blade bending are assumed to have some effects of the flutter limits of wind turbines. In the present report, the aeroelastic blade model suggested by Kallesoee, which is similar to a second order model, is used to investigate the aeroelastic stability limits of the RWT blade with and without the effects of the large blade deflection. The investigation shows no significant change of the flutter limit on the rotor speed due to the blade deflection,whereas the first edgewise bending mode becomes negatively damped due to the coupling with blade torsion which causes a change of the effective direction of blade vibration. These observations are confirmed by nonlinear aeroelastic simulations using HAWC2. This work is part of the UpWind project funded by the European Commission under the contract number SES6-CT-2005-019945 which is gratefully acknowledged. This report is the deliverable D2.3 of the UpWind project. (au)

  1. EFFECT OF EXERCISE ON CYCLE LENGTH IN ATRIAL-FLUTTER

    NARCIS (Netherlands)

    VANDENBERG, MP; CRIJNS, HJGM; SZABO, BM; BROUWER, J; LIE, KI

    Objective-To examine the effect of exercise on cycle length in atrial flutter. Patients-15 patients with chronic atrial flutter. Seven patients were taking digoxin and six verapamil; two were not taking medication. Methods-All patients underwent bicycle ergometry. Flutter cycle length was measured

  2. Flutter Analysis of the Thermal Protection Layer on the NASA HIAD

    Science.gov (United States)

    Goldman, Benjamin D.; Dowell, Earl H.; Scott, Robert C.

    2013-01-01

    A combination of classical plate theory and a supersonic aerodynamic model is used to study the aeroelastic flutter behavior of a proposed thermal protection system (TPS) for the NASA HIAD. The analysis pertains to the rectangular configurations currently being tested in a NASA wind-tunnel facility, and may explain why oscillations of the articles could be observed. An analysis using a linear flat plate model indicated that flutter was possible well within the supersonic flow regime of the wind tunnel tests. A more complex nonlinear analysis of the TPS, taking into account any material curvature present due to the restraint system or substructure, indicated that significantly greater aerodynamic forcing is required for the onset of flutter. Chaotic and periodic limit cycle oscillations (LCOs) of the TPS are possible depending on how the curvature is imposed. When the pressure from the base substructure on the bottom of the TPS is used as the source of curvature, the flutter boundary increases rapidly and chaotic behavior is eliminated.

  3. Digoxin for atrial fibrillation and atrial flutter

    DEFF Research Database (Denmark)

    Sethi, Naqash J; Nielsen, Emil E; Safi, Sanam

    2018-01-01

    BACKGROUND: During recent years, systematic reviews of observational studies have compared digoxin to no digoxin in patients with atrial fibrillation or atrial flutter, and the results of these reviews suggested that digoxin seems to increase the risk of all-cause mortality regardless...... of concomitant heart failure. Our objective was to assess the benefits and harms of digoxin for atrial fibrillation and atrial flutter based on randomized clinical trials. METHODS: We searched CENTRAL, MEDLINE, Embase, LILACS, SCI-Expanded, BIOSIS for eligible trials comparing digoxin versus placebo......, no intervention, or other medical interventions in patients with atrial fibrillation or atrial flutter in October 2016. Our primary outcomes were all-cause mortality, serious adverse events, and quality of life. Our secondary outcomes were heart failure, stroke, heart rate control, and conversion to sinus rhythm...

  4. Radiofrequency catheter oblation in atrial flutter

    International Nuclear Information System (INIS)

    Yan Ji; Wang Heping; Xu Jian; Liu Fuyuan; Fan Xizhen; An Chunsheng; Han Xiaoping; Ding Xiaomei; Wang Jiasheng; Gu Tongyuan

    2002-01-01

    Objective: To evaluate the radiofrequency catheter ablation for type I atrial flutter through application of Holo catheter labelling with anatomic imaging localization to ablate the isthmus of IVCTA during complete double-way block. Methods: Eleven cases with type I atrial flutter undergone Holo catheter labelling technique and consecution with conduction time change of coronary venous sinus orifice with-right atrial lower lateral wall pace excitation, were performed with radiofrequency catheter ablation for the isthmus outcoming with complete double-way conduction block. Results: All together 11 cases with 4 of atrial flutter and 7 of sinus rhythm were undergone radiofrequency catheter ablation resulting with double-way conduction block of the isthmus accompanied by prolongation of right atrial conduction time 56.0 ± 2.3 ms and 53.0 ± 4.6 ms respectively. The right atrial excitation appeared to be in clockwise and counter-clockwise of single direction. No recurrence occurred during 3-34 months follow up with only one showing atrial fibrillation. Conclusions: The application of Holo catheter labelling technique with anatomic imaging localization to achieve the double-way conduction block by radiofrequency catheter ablation of TVC-TA isthmus, is a reliable method for treating atrial flutter

  5. Magnetic-flutter-induced pedestal plasma transport

    International Nuclear Information System (INIS)

    Callen, J.D.; Hegna, C.C.; Cole, A.J.

    2013-01-01

    Plasma toroidal rotation can limit reconnection of externally applied resonant magnetic perturbation (RMP) fields δB on rational magnetic flux surfaces. Hence it causes the induced radial perturbations δB ρ to be small there, thereby inhibiting magnetic island formation and stochasticity at the top of pedestals in high (H-mode) confinement tokamak plasmas. However, the δB ρ s induced by RMPs increase away from rational surfaces and are shown to induce significant sinusoidal radial motion (flutter) of magnetic field lines with a radial extent that varies linearly with δB ρ and inversely with distance from the rational surface because of the magnetic shear. This produces a radial electron thermal diffusivity that is (1/2)(δB ρ /B 0 ) 2 times a kinetically derived, electron-collision-induced, magnetic-shear-reduced, effective parallel electron thermal diffusivity in the absence of magnetic stochasticity. These low collisionality flutter-induced transport processes and thin magnetic island effects are shown to be highly peaked in the vicinity of rational surfaces at the top of low collisionality pedestals. However, the smaller but finite level of magnetic-flutter-induced electron heat transport midway between rational surfaces is the primary factor that determines the electron temperature difference between rational surfaces at the pedestal top. The magnetic-flutter-induced non-ambipolar electron density transport can be large enough to push the plasma toward an electron density transport root. Requiring ambipolar density transport is shown to determine the radial electric field, the plasma toroidal rotation (via radial force balance), a reduced electron thermal diffusivity and increased ambipolar density transport in the pedestal. At high collisionality the various flutter effects are less strongly peaked at rational surfaces and generally less significant. They are thus less likely to exhibit flutter-induced resonant behaviour and transition toward an

  6. Magnetic-flutter-induced pedestal plasma transport

    Science.gov (United States)

    Callen, J. D.; Hegna, C. C.; Cole, A. J.

    2013-11-01

    Plasma toroidal rotation can limit reconnection of externally applied resonant magnetic perturbation (RMP) fields δB on rational magnetic flux surfaces. Hence it causes the induced radial perturbations δBρ to be small there, thereby inhibiting magnetic island formation and stochasticity at the top of pedestals in high (H-mode) confinement tokamak plasmas. However, the δBρs induced by RMPs increase away from rational surfaces and are shown to induce significant sinusoidal radial motion (flutter) of magnetic field lines with a radial extent that varies linearly with δBρ and inversely with distance from the rational surface because of the magnetic shear. This produces a radial electron thermal diffusivity that is (1/2)(δBρ/B0)2 times a kinetically derived, electron-collision-induced, magnetic-shear-reduced, effective parallel electron thermal diffusivity in the absence of magnetic stochasticity. These low collisionality flutter-induced transport processes and thin magnetic island effects are shown to be highly peaked in the vicinity of rational surfaces at the top of low collisionality pedestals. However, the smaller but finite level of magnetic-flutter-induced electron heat transport midway between rational surfaces is the primary factor that determines the electron temperature difference between rational surfaces at the pedestal top. The magnetic-flutter-induced non-ambipolar electron density transport can be large enough to push the plasma toward an electron density transport root. Requiring ambipolar density transport is shown to determine the radial electric field, the plasma toroidal rotation (via radial force balance), a reduced electron thermal diffusivity and increased ambipolar density transport in the pedestal. At high collisionality the various flutter effects are less strongly peaked at rational surfaces and generally less significant. They are thus less likely to exhibit flutter-induced resonant behaviour and transition toward an electron

  7. Rational Design of Composite Panels

    DEFF Research Database (Denmark)

    Riber, Hans Jørgen

    1996-01-01

    A non-linear structural model for composite panels is presented. The non-linear terms in the lateral displacements are modelled as an additional set of lateral loads acting on the panel. Hence the solution is reduced to that of an equivalent panel with small displacements In order to treat sandwich...... Norske Veritas', DNV, building rules concerning high-speed light craft, in which the panel scantlings are often restricted by a maximum lateral deflection connected with the panel span....

  8. Nonlinear stability control and λ-bifurcation

    International Nuclear Information System (INIS)

    Erneux, T.; Reiss, E.L.; Magnan, J.F.; Jayakumar, P.K.

    1987-01-01

    Passive techniques for nonlinear stability control are presented for a model of fluidelastic instability. They employ the phenomena of λ-bifurcation and a generalization of it. λ-bifurcation occurs when a branch of flutter solutions bifurcates supercritically from a basic solution and terminates with an infinite period orbit at a branch of divergence solutions which bifurcates subcritically from the basic solution. The shape of the bifurcation diagram then resembles the greek letter λ. When the system parameters are in the range where flutter occurs by λ-bifurcation, then as the flow velocity increase the flutter amplitude also increases, but the frequencies of the oscillations decrease to zero. This diminishes the damaging effects of structural fatigue by flutter, and permits the flow speed to exceed the critical flutter speed. If generalized λ-bifurcation occurs, then there is a jump transition from the flutter states to a divergence state with a substantially smaller amplitude, when the flow speed is sufficiently larger than the critical flutter speed

  9. Non-Linear Relationship between Economic Growth and CO₂ Emissions in China: An Empirical Study Based on Panel Smooth Transition Regression Models.

    Science.gov (United States)

    Wang, Zheng-Xin; Hao, Peng; Yao, Pei-Yi

    2017-12-13

    The non-linear relationship between provincial economic growth and carbon emissions is investigated by using panel smooth transition regression (PSTR) models. The research indicates that, on the condition of separately taking Gross Domestic Product per capita (GDPpc), energy structure (Es), and urbanisation level (Ul) as transition variables, three models all reject the null hypothesis of a linear relationship, i.e., a non-linear relationship exists. The results show that the three models all contain only one transition function but different numbers of location parameters. The model taking GDPpc as the transition variable has two location parameters, while the other two models separately considering Es and Ul as the transition variables both contain one location parameter. The three models applied in the study all favourably describe the non-linear relationship between economic growth and CO₂ emissions in China. It also can be seen that the conversion rate of the influence of Ul on per capita CO₂ emissions is significantly higher than those of GDPpc and Es on per capita CO₂ emissions.

  10. Structural resonance and mode of flutter of hummingbird tail feathers.

    Science.gov (United States)

    Clark, Christopher J; Elias, Damian O; Girard, Madeline B; Prum, Richard O

    2013-09-15

    Feathers can produce sound by fluttering in airflow. This flutter is hypothesized to be aeroelastic, arising from the coupling of aerodynamic forces to one or more of the feather's intrinsic structural resonance frequencies. We investigated how mode of flutter varied among a sample of hummingbird tail feathers tested in a wind tunnel. Feather vibration was measured directly at ~100 points across the surface of the feather with a scanning laser Doppler vibrometer (SLDV), as a function of airspeed, Uair. Most feathers exhibited multiple discrete modes of flutter, which we classified into types including tip, trailing vane and torsional modes. Vibratory behavior within a given mode was usually stable, but changes in independent variables such as airspeed or orientation sometimes caused feathers to abruptly 'jump' from one mode to another. We measured structural resonance frequencies and mode shapes directly by measuring the free response of 64 feathers stimulated with a shaker and recorded with the SLDV. As predicted by the aeroelastic flutter hypothesis, the mode shape (spatial distribution) of flutter corresponded to a bending or torsional structural resonance frequency of the feather. However, the match between structural resonance mode and flutter mode was better for tip or torsional mode shapes, and poorer for trailing vane modes. Often, the 3rd bending structural harmonic matched the expressed mode of flutter, rather than the fundamental. We conclude that flutter occurs when airflow excites one or more structural resonance frequencies of a feather, most akin to a vibrating violin string.

  11. Reduced-Order Modeling for Flutter/LCO Using Recurrent Artificial Neural Network

    Science.gov (United States)

    Yao, Weigang; Liou, Meng-Sing

    2012-01-01

    The present study demonstrates the efficacy of a recurrent artificial neural network to provide a high fidelity time-dependent nonlinear reduced-order model (ROM) for flutter/limit-cycle oscillation (LCO) modeling. An artificial neural network is a relatively straightforward nonlinear method for modeling an input-output relationship from a set of known data, for which we use the radial basis function (RBF) with its parameters determined through a training process. The resulting RBF neural network, however, is only static and is not yet adequate for an application to problems of dynamic nature. The recurrent neural network method [1] is applied to construct a reduced order model resulting from a series of high-fidelity time-dependent data of aero-elastic simulations. Once the RBF neural network ROM is constructed properly, an accurate approximate solution can be obtained at a fraction of the cost of a full-order computation. The method derived during the study has been validated for predicting nonlinear aerodynamic forces in transonic flow and is capable of accurate flutter/LCO simulations. The obtained results indicate that the present recurrent RBF neural network is accurate and efficient for nonlinear aero-elastic system analysis

  12. Implementation of the non-flutter design principle

    DEFF Research Database (Denmark)

    Andersen, Michael Styrk; Sahin, Emrah; Laustsen, Benjamin

    2014-01-01

    The non-flutter design principle is introduced. Aerodynamically stable section model tests performed by three different research groups indicate, that flutter might be avoided if the torsional-to-vertical frequency ratio is kept below 1. A case study of a suspension bridge spanning 3:7 km...

  13. Non-Flutter Design Principle for long Span Bridges

    DEFF Research Database (Denmark)

    Johansson, Jens; Andersen, Michael Styrk; Starch Øvre, Michele

    velocity for a thin airfoil shows an asymptotical behavior. In traditional bridge design the torsional-to-vertical frequency ratio is increased to obtain higher flutter wind velocities. In the present study, we investigate, what we will label the non-flutter design principle, in which the torsional...

  14. Analysis of tiltrotor whirl flutter in time and frequency domain

    DEFF Research Database (Denmark)

    Kim, Taeseong; Shin, SanJoon; Kim, Taehyoun

    2009-01-01

    The whirl flutter phenomenon in a rotor is induced by in-plane hub forces, and imposes a serious limit on the forward speed. In this paper, based on Greenberg’s model, quasi-steady and unsteady aerodynamic forces are formulated to examine the whirl flutter stability for a three-bladed rotor witho...

  15. Robust Nonlinear Control of Stall and Flutter in Aeroengines

    National Research Council Canada - National Science Library

    Murray, Richard

    2001-01-01

    ... (bleed valves and air injection). The goal of the third activity, begun after the initial student supported by the grant left Caltech, was to develop modeling and control approaches for complex, physical systems, including control...

  16. Flutter analysis of low aspect ratio wings

    Science.gov (United States)

    Parnell, L. A.

    1986-01-01

    Several very low aspect ratio flat plate wing configurations are analyzed for their aerodynamic instability (flutter) characteristics. All of the wings investigated are delta planforms with clipped tips, made of aluminum alloy plate and cantilevered from the supporting vehicle body. Results of both subsonic and supersonic NASTRAN aeroelastic analyses as well as those from another version of the program implementing the supersonic linearized aerodynamic theory are presented. Results are selectively compared with the experimental data; however, supersonic predictions of the Mach Box method in NASTRAN are found to be erratic and erroneous, requiring the use of a separate program.

  17. RMP-Flutter-Induced Pedestal Plasma Transport

    Energy Technology Data Exchange (ETDEWEB)

    Callen, J. D.; Hegna, C., E-mail: callen@engr.wisc.edu [University of Wisconsin, Madison (United States); Cole, A. J. [Columbia University, New York (United States)

    2012-09-15

    Full text: Plasma toroidal rotation can prevent or limit reconnection of externally applied resonant magnetic perturbation (RMP) fields {delta}B on rational magnetic flux surfaces. Hence, it causes the induced radial perturbations to vanish or be small there, and thereby inhibits magnetic island formation and stochasticity in the edge of high (H-mode) confinement tokamak plasmas. However, the radial component of the spatial magnetic flutter induced by RMP fields off rational surfaces causes a radial electron thermal diffusivity of (1/2)({delta}B{sub p}/B){sup 2} times a magnetic-shear-influenced effective parallel electron thermal diffusivity. The resultant RMP-flutter-induced electron thermal diffusivity can be comparable to experimentally inferred values at the top of H-mode pedestals. This process also causes a factor of about 3 smaller RMP-induced electron density diffusivity there. Because this electron density transport is non-ambipolar, it produces a toroidal torque on the plasma, which is usually in the co-current direction. Kinetic-based cylindrical screw-pinch and toroidal models of these RMP-flutter-induced plasma transport effects have been developed. The RMP-induced increases in these diffusive plasma transport processes are typically spatially inhomogeneous in that they are strongly peaked near the rational surfaces in low collisionality pedestals, which may lead to resonant sensitivities to the local safety factor q. The effects can be large enough to reduce the radially averaged gradients of the electron temperature and density at the top of H-mode edge pedestals, and modify the plasma toroidal rotation and radial electric field there. At high collisionality the various effects are less strongly peaked at rational surfaces and thus less likely to exhibit RMP-induced resonant behavior. These RMP-flutter-induced plasma transport processes provide a new paradigm for developing an understanding of how RMPs modify the pedestal structure to stabilize

  18. Aero-servo-viscoelasticity theory: Lifting surfaces, plates, velocity transients, flutter, and instability

    Science.gov (United States)

    Merrett, Craig G.

    -partial differential equations. The spatial component of the governing equations is eliminated using a series expansion of basis functions and by applying Galerkin's method. The number of terms in the series expansion affects the convergence of the spatial component, and convergence is best determined by the von Koch rules that previously appeared for column buckling problems. After elimination of the spatial component, an ordinary integral-differential equation in time remains. The dynamic stability of elastic and viscoelastic problems is assessed using the determinant of the governing system of equations and the time component of the solution in the form exp (lambda t). The determinant is in terms of lambda where the values of lambda are the latent roots of the aero-servo-viscoelastic system. The real component of lambda dictates the stability of the system. If all the real components are negative, the system is stable. If at least one real component is zero and all others are negative, the system is neutrally stable. If one or more real components are positive, the system is unstable. In aero-servo-viscoelasticity, the neutrally stable condition is termed flutter. For an aero-servo-viscoelastic lifting surface, the unstable condition is historically termed torsional divergence. The more general aero-servo-viscoelastic theory has produced a number of important results, enumerated in the following list: 1. Subsonic panel flutter can occur before panel instability. This result overturned a long held assumption in aeroelasticity, and was produced by the novel application of the von Koch rules for convergence. Further, experimental results from the 1950s by the Air Force were retrieved to provide additional proof. 2. An expanded definition for flutter of a lifting surface. The legacy definition is that flutter is the first occurrence of simple harmonic motion of a structure, and the flight velocity at which this motion occurs is taken as the flutter speed. The expanded definition

  19. Non-symmetric forms of non-linear vibrations of flexible cylindrical panels and plates under longitudinal load and additive white noise

    Science.gov (United States)

    Krysko, V. A.; Awrejcewicz, J.; Krylova, E. Yu; Papkova, I. V.; Krysko, A. V.

    2018-06-01

    Parametric non-linear vibrations of flexible cylindrical panels subjected to additive white noise are studied. The governing Marguerre equations are investigated using the finite difference method (FDM) of the second-order accuracy and the Runge-Kutta method. The considered mechanical structural member is treated as a system of many/infinite number of degrees of freedom (DoF). The dependence of chaotic vibrations on the number of DoFs is investigated. Reliability of results is guaranteed by comparing the results obtained using two qualitatively different methods to reduce the problem of PDEs (partial differential equations) to ODEs (ordinary differential equations), i.e. the Faedo-Galerkin method in higher approximations and the 4th and 6th order FDM. The Cauchy problem obtained by the FDM is eventually solved using the 4th-order Runge-Kutta methods. The numerical experiment yielded, for a certain set of parameters, the non-symmetric vibration modes/forms with and without white noise. In particular, it has been illustrated and discussed that action of white noise on chaotic vibrations implies quasi-periodicity, whereas the previously non-symmetric vibration modes are closer to symmetric ones.

  20. Holistic approach to flutter clearance using classical methods

    CSIR Research Space (South Africa)

    Van Zyl, Lourens H

    2006-09-01

    Full Text Available is validated by determining and eigenvalue solution from the state-space model and comparing it to the frequency domain solution. This model is then used to generate time histories of the responses of the different sensors that will be used in flutter... flight testing for a given excitation configuration. The time histories are processed by the flutter flight test software to assess how well the vibration modes are excited and to determine the effect of the finite frequency resolution...

  1. A MODELING METHOD OF FLUTTERING LEAVES BASED ON POINT CLOUD

    OpenAIRE

    J. Tang; Y. Wang; Y. Zhao; Y. Zhao; W. Hao; X. Ning; K. Lv; Z. Shi; M. Zhao

    2017-01-01

    Leaves falling gently or fluttering are common phenomenon in nature scenes. The authenticity of leaves falling plays an important part in the dynamic modeling of natural scenes. The leaves falling model has a widely applications in the field of animation and virtual reality. We propose a novel modeling method of fluttering leaves based on point cloud in this paper. According to the shape, the weight of leaves and the wind speed, three basic trajectories of leaves falling are defined, which ar...

  2. Proposed aeroelastic and flutter tests for the National Transonic Facility

    Science.gov (United States)

    Stevenson, J. R.

    1981-01-01

    Tests that can exploit the capability of the NTF and the transonic cryogenic tunnel, or lead to improvements that could enhance testing in the NTF are discussed. Shock induced oscillation, supersonic single degree control surface flutter, and transonic flutter speed as a function of the Reynolds number are considered. Honeycombs versus screens to smooth the tunnel flow and a rapid tunnel dynamic pressure reducer are recommended to improve tunnel performance.

  3. Atrial flutter: from ECG to electroanatomical 3D mapping

    Directory of Open Access Journals (Sweden)

    Livio Dei Cas

    2009-08-01

    Full Text Available Atrial flutter is a common arrhythmia that may cause significant symptoms, including palpitations, dyspnea, chest pain and even syncope. Frequently it’s possible to diagnose atrial flutter with a 12-lead surface ECG, looking for distinctive waves in leads II, III, aVF, aVL, V1,V2. Puech and Waldo developed the first classification of atrial flutter in the 1970s. These authors divided the arrhythmia into type I and type II. Therefore, in 2001 the European Society of Cardiology and the North American Society of Pacing and Electrophysiology developed a new classification of atrial flutter, based not only on the ECG, but also on the electrophysiological mechanism. New developments in endocardial mapping, including the electroanatomical 3D mapping system, have greatly expanded our understanding of the mechanism of arrhythmias. More recently, Scheinman et al, provided an updated classification and nomenclature. The terms like common, uncommon, typical, reverse typical or atypical flutter are abandoned because they may generate confusion. The authors worked out a new terminology, which differentiates atrial flutter only on the basis of electrophysiological mechanism. (Heart International 2006; 3-4: 161-70

  4. On-Line Flutter Prediction Tool for Wind Tunnel Flutter Testing using Parameter Varying Estimation Methodology, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — ZONA Technology, Inc. (ZONA) proposes to develop an on-line flutter prediction tool for wind tunnel model using the parameter varying estimation (PVE) technique to...

  5. A Comparative Assessment of Aerodynamic Models for Buffeting and Flutter of Long-Span Bridges

    Directory of Open Access Journals (Sweden)

    Igor Kavrakov

    2017-12-01

    Full Text Available Wind-induced vibrations commonly represent the leading criterion in the design of long-span bridges. The aerodynamic forces in bridge aerodynamics are mainly based on the quasi-steady and linear unsteady theory. This paper aims to investigate different formulations of self-excited and buffeting forces in the time domain by comparing the dynamic response of a multi-span cable-stayed bridge during the critical erection condition. The bridge is selected to represent a typical reference object with a bluff concrete box girder for large river crossings. The models are viewed from a perspective of model complexity, comparing the influence of the aerodynamic properties implied in the aerodynamic models, such as aerodynamic damping and stiffness, fluid memory in the buffeting and self-excited forces, aerodynamic nonlinearity, and aerodynamic coupling on the bridge response. The selected models are studied for a wind-speed range that is typical for the construction stage for two levels of turbulence intensity. Furthermore, a simplified method for the computation of buffeting forces including the aerodynamic admittance is presented, in which rational approximation is avoided. The critical flutter velocities are also compared for the selected models under laminar flow. Keywords: Buffeting, Flutter, Long-span bridges, Bridge aerodynamics, Bridge aeroelasticity, Erection stage

  6. Isthmus Dependent Atrial Flutter Cycle Length Correlates with Right Atrial Cross-Sectional Area

    Directory of Open Access Journals (Sweden)

    Kousik Krishnan

    2009-05-01

    Full Text Available Background: Right atrial flutter cycle length can prolong in the presence of antiarrhythmic drug therapy. We hypothesized that the cycle length of right atrial isthmus dependent flutter would correlate with right atrial cross-sectional area measurements. Methods: 60 patients who underwent ablation for electrophysiologically proven isthmus dependent right atrial flutter, who were not on Class I or Class III antiarrhythmic drugs and had recent 2-dimensional echocardiographic data comprised the study group. Right atrial length and width were measured in the apical four chamber view. Cross-sectional area was estimated by multiplying the length and width. 35 patients had an atrial flutter rate ≥250 bpm (Normal Flutter Group and 25 patients had an atrial flutter rate < 250 bpm (Slow Flutter Group. Results: Mean atrial flutter rate was 283 bpm in the normal flutter group and 227 bpm in the slow flutter group. Mean atrial flutter cycle length was 213 ms in the Normal Flutter Group and 265 ms in the Slow Flutter Group (p<0.0001. Mean right atrial cross sectional area was 1845 mm2 in the Normal Flutter group and 2378 mm2 in the Slow Flutter Group, (p< 0.0001. Using linear regression, CSA was a significant predictor of cycle length (β =0.014 p = 0.0045. For every 1 mm2 increase in cross-sectional area, cycle length is 0.014 ms longer.Conclusion: In the absence of antiarrhythmic medications, right atrial cross sectional area enlargement correlates with atrial flutter cycle length. These findings provide further evidence that historical rate-related definitions of typical isthmus dependent right atrial are not mechanistically valid.

  7. Bending mode flutter in a transonic linear cascade

    Science.gov (United States)

    Govardhan, Raghuraman; Jutur, Prahallada

    2017-11-01

    Vibration related issues like flutter pose a serious challenge to aircraft engine designers. The phenomenon has gained relevance for modern engines that employ thin and long fan blade rows to satisfy the growing need for compact and powerful engines. The tip regions of such blade rows operate with transonic relative flow velocities, and are susceptible to bending mode flutter. In such cases, the flow field around individual blades of the cascade is dominated by shock motions generated by the blade motions. In the present work, a new transonic linear cascade facility with the ability to oscillate a blade at realistic reduced frequencies has been developed. The facility operates at a Mach number of 1.3, with the central blade being oscillated in heave corresponding to the bending mode of the rotor. The susceptibility of the blade to undergo flutter at different reduced frequencies is quantified by the cycle-averaged power transfer to the blade calculated using the measured unsteady load on the oscillating blade. These measurements show fluid excitation (flutter) at low reduced frequencies and fluid damping (no flutter) at higher reduced frequencies. Simultaneous measurements of the unsteady shock motions are done with high speed shadowgraphy to elucidate the differences in shock motions between the excitation and damping cases.

  8. Gravity effects on wind-induced flutter of leaves

    Science.gov (United States)

    Clemmer, Nickalaus; Kopperstad, Karsten; Solano, Tomas; Shoele, Kourosh; Ordonez, Juan

    2017-11-01

    Wind-Induced flutter of leaves depends on both wind velocity and the gravity. To study the gravitational effects on the oscillatory behavior of leaves in the wind, a wind tunnel that can be tilted about the center of the test section is created. This unique rotation capability allows systematic investigation of gravitational effects on the fluttering response of leaves. The flow-induced vibration will be studied for three different leaves at several different tilting angles including the wind travels horizontally, vertically downward and vertically upward. In each situation, the long axis of a leaf is placed parallel to the wind direction and its response is studied at different flow speed. Oscillation of the leaf is recorded via high-speed camera at each of setup, and the effect of the gravity on stabilizing or destabilizing the fluttering response is investigated. Summer REU student at Florida State University.

  9. Beam Flutter and Energy Harvesting in Internal Flow

    Science.gov (United States)

    Tosi, Luis Phillipe; Colonius, Tim; Sherrit, Stewart; Lee, Hyeong Jae

    2017-11-01

    Aeroelastic flutter, largely studied for causing engineering failures, has more recently been used as a means of extracting energy from the flow. Particularly, flutter of a cantilever or an elastically mounted plate in a converging-diverging flow passage has shown promise as an energy harvesting concept for internal flow applications. The instability onset is observed as a function of throat velocity, internal wall geometry, fluid and structure material properties. To enable these devices, our work explores features of the fluid-structure coupled dynamics as a function of relevant nondimensional parameters. The flutter boundary is examined through stability analysis of a reduced order model, and corroborated with numerical simulations at low Reynolds number. Experiments for an energy harvester design are qualitatively compared to results from analytical and numerical work, suggesting a robust limit cycle ensues due to a subcritical Hopf bifurcation. Bosch Corporation.

  10. Equivalent linearization method for limit cycle flutter analysis of plate-type structure in axial flow

    International Nuclear Information System (INIS)

    Lu Li; Yang Yiren

    2009-01-01

    The responses and limit cycle flutter of a plate-type structure with cubic stiffness in viscous flow were studied. The continuous system was dispersed by utilizing Galerkin Method. The equivalent linearization concept was performed to predict the ranges of limit cycle flutter velocities. The coupled map of flutter amplitude-equivalent linear stiffness-critical velocity was used to analyze the stability of limit cycle flutter. The theoretical results agree well with the results of numerical integration, which indicates that the equivalent linearization concept is available to the analysis of limit cycle flutter of plate-type structure. (authors)

  11. Large Scale Flutter Data for Design of Rotating Blades Using Navier-Stokes Equations

    Science.gov (United States)

    Guruswamy, Guru P.

    2012-01-01

    A procedure to compute flutter boundaries of rotating blades is presented; a) Navier-Stokes equations. b) Frequency domain method compatible with industry practice. Procedure is initially validated: a) Unsteady loads with flapping wing experiment. b) Flutter boundary with fixed wing experiment. Large scale flutter computation is demonstrated for rotating blade: a) Single job submission script. b) Flutter boundary in 24 hour wall clock time with 100 cores. c) Linearly scalable with number of cores. Tested with 1000 cores that produced data in 25 hrs for 10 flutter boundaries. Further wall-clock speed-up is possible by performing parallel computations within each case.

  12. Results of Two Free-fall Experiments on Flutter of Thin Unswept Wings in the Transonic Speed Range

    Science.gov (United States)

    Lauten, William T , Jr; Nelson, Herbert C

    1957-01-01

    Results of four thin, unswept, flutter airfoils attached to two freely falling bodies are reported. Two airfoils fluttered at a Mach number of 0.85, a third airfoil fluttered at a Mach number of 1.03, and a fourth fluttered at a Mach number of 1.07. Results of calculations of flutter speed using incompressible and compressible air-force coefficients, including a Mach number of 1.0, are presented.

  13. Determination of Flutter Derivatives for the Great Belt Bridge

    DEFF Research Database (Denmark)

    Poulsen, Niels Kjølstad; Damsgaard, Aage; Reinhold, Thim A.

    1992-01-01

    A new method which combines control theory and system identification techniques has been used to extract flutter derivatives from section model tests for the Great Belt East Bridge. Tests were conducted by exciting the section model simultaneously in vertical and torsional modes of vibration. Tests...

  14. Quinidine-induced ventricular flutter and fibrillation without digitalis therapy

    NARCIS (Netherlands)

    Koster, R. W.; Wellens, H. J.

    1976-01-01

    Three cases are described with documented ventricular flutter and fibrillation during quinidine medication without concomitant digitalis therapy. In all three patients the arrhythmia developed while they were receiving moderate doses of quinidine. Although no changes in QRS width were observed after

  15. Cardiac Arrhythmia: Atrial Flutter in a Newborn. Case Study

    Directory of Open Access Journals (Sweden)

    T.M. Klimenko

    2014-09-01

    Full Text Available The article gives case report of rare in neonatal period cardiac arrhythmia — atrial flutter. The disease is one of the manifestations of life-threatening heart rhythm disorders, has no characteristic clinical picture, is diagnosed only by means of an electrocardiogram.

  16. Cardiorespiratory interactions in patients with atrial flutter.

    Science.gov (United States)

    Masè, Michela; Disertori, Marcello; Ravelli, Flavia

    2009-01-01

    Respiratory sinus arrhythmia (RSA) is generally known as the autonomically mediated modulation of the sinus node pacemaker frequency in synchrony with respiration. Cardiorespiratory interactions have been largely investigated during sinus rhythm, whereas little is known about interactions during reentrant arrhythmias. In this study, cardiorespiratory interactions at the atrial and ventricular level were investigated during atrial flutter (AFL), a supraventricular arrhythmia based on a reentry, by using cross-spectral analysis and computer modeling. The coherence and phase between respiration and atrial (gamma(AA)(2), phi(AA)) and ventricular (gamma(RR)(2), phi(RR)) interval series were estimated in 20 patients with typical AFL (68.0 +/- 8.8 yr) and some degree of atrioventricular (AV) conduction block. In all patients, atrial intervals displayed oscillations strongly coupled and in phase with respiration (gamma(AA)(2)= 0.97 +/- 0.05, phi(AA) = 0.71 +/- 0.31 rad), corresponding to a paradoxical lengthening of intervals during inspiration. The modulation pattern was frequency independent, with in-phase oscillations and short time delays (0.40 +/- 0.15 s) for respiratory frequencies in the range 0.1-0.4 Hz. Ventricular patterns were affected by AV conduction type. In patients with fixed AV conduction, ventricular intervals displayed oscillations strongly coupled (gamma(RR)(2)= 0.97 +/- 0.03) and in phase with respiration (phi(RR) = 1.08 +/- 0.80 rad). Differently, in patients with variable AV conduction, respiratory oscillations were secondary to Wencheback rhythmicity, resulting in a decreased level of coupling (gamma(RR)(2)= 0.50 +/- 0.21). Simulations with a simplified model of AV conduction showed ventricular patterns to originate from the combination of a respiratory modulated atrial input with the functional properties of the AV node. The paradoxical frequency-independent modulation pattern of atrial interval, the short time delays, and the complexity of

  17. Simple quasi-analytical holonomic homogenization model for the non-linear analysis of in-plane loaded masonry panels: Part 1, meso-scale

    Science.gov (United States)

    Milani, G.; Bertolesi, E.

    2017-07-01

    A simple quasi analytical holonomic homogenization approach for the non-linear analysis of masonry walls in-plane loaded is presented. The elementary cell (REV) is discretized with 24 triangular elastic constant stress elements (bricks) and non-linear interfaces (mortar). A holonomic behavior with softening is assumed for mortar. It is shown how the mechanical problem in the unit cell is characterized by very few displacement variables and how homogenized stress-strain behavior can be evaluated semi-analytically.

  18. Nonlinear Structural Analysis

    Indian Academy of Sciences (India)

    The Structures Panel of the Aeronautics Research and Development Board of India ... A great variety of topics was covered, including themes such as nonlinear finite ... or shell structures, and three are on the composite form of construction, ...

  19. a Modeling Method of Fluttering Leaves Based on Point Cloud

    Science.gov (United States)

    Tang, J.; Wang, Y.; Zhao, Y.; Hao, W.; Ning, X.; Lv, K.; Shi, Z.; Zhao, M.

    2017-09-01

    Leaves falling gently or fluttering are common phenomenon in nature scenes. The authenticity of leaves falling plays an important part in the dynamic modeling of natural scenes. The leaves falling model has a widely applications in the field of animation and virtual reality. We propose a novel modeling method of fluttering leaves based on point cloud in this paper. According to the shape, the weight of leaves and the wind speed, three basic trajectories of leaves falling are defined, which are the rotation falling, the roll falling and the screw roll falling. At the same time, a parallel algorithm based on OpenMP is implemented to satisfy the needs of real-time in practical applications. Experimental results demonstrate that the proposed method is amenable to the incorporation of a variety of desirable effects.

  20. A MODELING METHOD OF FLUTTERING LEAVES BASED ON POINT CLOUD

    Directory of Open Access Journals (Sweden)

    J. Tang

    2017-09-01

    Full Text Available Leaves falling gently or fluttering are common phenomenon in nature scenes. The authenticity of leaves falling plays an important part in the dynamic modeling of natural scenes. The leaves falling model has a widely applications in the field of animation and virtual reality. We propose a novel modeling method of fluttering leaves based on point cloud in this paper. According to the shape, the weight of leaves and the wind speed, three basic trajectories of leaves falling are defined, which are the rotation falling, the roll falling and the screw roll falling. At the same time, a parallel algorithm based on OpenMP is implemented to satisfy the needs of real-time in practical applications. Experimental results demonstrate that the proposed method is amenable to the incorporation of a variety of desirable effects.

  1. Flutter instability of freely hanging articulated pipes conveying fluid

    Science.gov (United States)

    Schouveiler, Lionel; Chermette, Félix

    2018-03-01

    We experimentally investigate the stability of freely hanging articulated pipes made of rigid segments connected by flexible joints and with their displacements constrained in a vertical plane. When the velocity of the fluid conveyed by the pipe is increased, flutter-type instability occurs above a critical value. The critical velocity and the characteristics of the flutter modes (frequency, amplitude, and shape) are determined as a function of the number n of segments into the pipe which is varied from 2 to 5. Experimental results are compared to predictions from linear stability analysis extending previous studies by taking into account damping due to the dissipation in the joints. Qualitative agreement is found and the limits of the analysis are discussed.

  2. Aeroelastic flutter energy harvesters self-polarized by triboelectric effects

    Science.gov (United States)

    Perez, M.; Boisseau, S.; Geisler, M.; Gasnier, P.; Willemin, J.; Despesse, G.; Reboud, J. L.

    2018-01-01

    This paper presents the performances of several electrostatic flutter energy harvesters tested in a wind tunnel between 0 and 20 m s-1. The main idea is to use the flutter capability of thin flexible films confined between lateral walls to induce simultaneously the capacitance variations and the electrostatic polarization required by the triboelectric/electrostatic conversion. This technology provides thin and flexible devices and solve the electret’s stability issue (Perez et al 2015 Smart Mater. Struct., Perez et al 2015 New Circuits and Systems). Our prototypes (management circuit has finally been used to supply an 868 MHz wireless sensor node with temperature and acceleration measurements, validating the complete energy harvesting chain.

  3. Aeroelastic Flutter of Subsonic Aircraft Wing Section with Control Surface

    Directory of Open Access Journals (Sweden)

    Aeroelastic Flutter of Subsonic Aircraft Wing Section with Control Surface

    2015-12-01

    Full Text Available Aeroelastic flutter in aircraft mechanisms is unavoidable, essentially in the wing and control surface. In this work a three degree-of-freedom aeroelastic wing section with trailing edge flap is modeled numerically and theoretically. FLUENT code based on the steady finite volume is used for the prediction of the steady aerodynamic characteristics (lift, drag, pitching moment, velocity, and pressure distribution as well as the Duhamel formulation is used to model the aerodynamic loads theoretically. The system response (pitch, flap pitch and plunge was determined by integration the governing equations using MATLAB with a standard Runge–Kutta algorithm in conjunction with Henon’s method. The results are compared with previous experimental data. The results show that the aerodynamic loads and wing-flap system response are increased when increasing the flow speed. On the other hand the aeroelastic response led up to limit cycle oscillation when the flow equals or more than flutter speed.

  4. Flutter Analysis of RX-420 Balistic Rocket Fin Involving Rigid Body Modes of Rocket Structures

    Directory of Open Access Journals (Sweden)

    Novi Andria

    2013-03-01

    Full Text Available Flutter is a phenomenon that has brought a catastrophic failure to the flight vehicle structure. In this experiment, flutter was analyzed for its symmetric and antisymmetric configuration to understand the effect of rocket rigid modes to the fin flutter characteristic. This research was also expected to find out the safety level of RX-420 structure design. The analysis was performed using half rocket model. Fin structure used in this research was a fin which has semispan 600 mm, thickness 12 mm, chord root 700 mm, chord tip 400 mm, made by Al 6061-T651, double spar configuration with skin thickness of 2 mm. Structural dynamics and flutter stability were analyzed using finite element software implemented on MSC. Nastran. The analysis shows that the antisymmetric flutter mode is more critical than symmetric flutter mode. At sea level altitude, antisymmetric flutter occurs at 6.4 Mach, and symmetric flutter occurs at 10.15 Mach. Compared to maximum speed of RX-420 which is 4.5 Mach at altitude 11 km or equivalent to 2.1 Mach at sea level, it can be concluded that the RX-420 structure design is safe, and flutter will not occur during flight.

  5. Application of a flight test and data analysis technique to flutter of a drone aircraft

    Science.gov (United States)

    Bennett, R. M.

    1981-01-01

    Modal identification results presented were obtained from recent flight flutter tests of a drone vehicle with a research wing (DAST ARW-1 for Drones for Aerodynamic and Structural Testing, Aeroelastic Research Wing-1). This vehicle is equipped with an active flutter suppression system (FSS). Frequency and damping of several modes are determined by a time domain modal analysis of the impulse response function obtained by Fourier transformations of data from fast swept sine wave excitation by the FSS control surface on the wing. Flutter points are determined for two different altitudes with the FSS off. Data are given for near the flutter boundary with the FSS on.

  6. The influence of trailed vorticity on flutter speed estimations

    International Nuclear Information System (INIS)

    Pirrung, Georg R; Madsen, Helge Aa; Kim, Taeseong

    2014-01-01

    This paper briefly describes the implementation of a coupled near and far wake model for wind turbine rotor induction in the aeroelastic code HAWC2 and its application for flutter analysis of the NREL 5 MW wind turbine. The model consists of a far wake part based on Blade Element Momentum (BEM) theory, which is coupled with Beddoes' near wake model for trailed vorticity. The first part of this work outlines the implementation in HAWC2, with a focus on the interaction of the induction from the blade based near wake model with the induction from the polar grid based BEM model in HAWC2. The influence of the near wake model on the aeroelastic stability of the blades of the NREL 5 MW turbine in overspeed conditions is investigated in the second part of the paper. The analysis is based on a runaway case in which the turbine is free to speed up without generator torque and vibrations start building up at a critical rotor speed. Blades with modified torsional and flapwise stiffness are also investigated. A flutter analysis is often part of the stability investigations for new blades but is normally carried out with engineering models that do not include the influence of unsteady trailed vorticity. Including this influence results in a slightly increased safety margin against classical flutter in all simulated cases

  7. Flutter and divergence instability of supported piezoelectric nanotubes conveying fluid

    Science.gov (United States)

    Bahaadini, Reza; Hosseini, Mohammad; Jamali, Behnam

    2018-01-01

    In this paper, divergence and flutter instabilities of supported piezoelectric nanotubes containing flowing fluid are investigated. To take the size effects into account, the nonlocal elasticity theory is implemented in conjunction with the Euler-Bernoulli beam theory incorporating surface stress effects. The Knudsen number is applied to investigate the slip boundary conditions between the flow and wall of nanotube. The nonlocal governing equations of nanotube are obtained using Newtonian method, including the influence of piezoelectric voltage, surface effects, Knudsen number and nonlocal parameter. Applying Galerkin approach to transform resulting equations into a set of eigenvalue equations under the simple-simple (S-S) and clamped-clamped (C-C) boundary conditions. The effects of the piezoelectric voltage, surface effects, Knudsen number, nonlocal parameter and boundary conditions on the divergence and flutter boundaries of nanotubes are discussed. It is observed that the fluid-conveying nanotubes with both ends supported lose their stability by divergence first and then by flutter with increase in fluid velocity. Results indicate the importance of using piezoelectric voltage, nonlocal parameter and Knudsen number in decrease of critical flow velocities of system. Moreover, the surface effects have a significant role on the eigenfrequencies and critical fluid velocity.

  8. Vibration and flutter of mistuned bladed-disk assemblies

    Science.gov (United States)

    Kaza, K. R. V.; Kielb, R. E.

    1984-01-01

    An analytical model for investigating vibration and flutter of mistuned bladed disk assemblies is presented. This model accounts for elastic, inertial and aerodynamic coupling between bending and torsional motions of each individual blade, elastic and inertial couplings between the blades and the disk, and aerodynamic coupling among the blades. The disk was modeled as a circular plate with constant thickness and each blade was represented by a twisted, slender, straight, nonuniform, elastic beam with a symmetric cross section. The elastic axis, inertia axis, and the tension axis were taken to be noncoincident and the structural warping of the section was explicitly considered. The blade aerodynamic loading in the subsonic and supersonic flow regimes was obtained from two-dimensional unsteady, cascade theories. All the possible standing wave modes of the disk and traveling wave modes of the blades were included. The equations of motion were derived by using the energy method in conjunction with the assumed mode shapes for the disk and the blades. Continuities of displacement and slope at the blade-disk junction were maintained. The equations were solved to investigate the effects of blade-disk coupling and blade frequency mistuning on vibration and flutter. Results showed that the flexibility of practical disks such as those used for current generation turbofans did not have a significant influence on either the tuned or mistuned flutter characteristics. However, the disk flexibility may have a strong influence on some of the system frequencies and on forced response.

  9. Panel Analysis

    DEFF Research Database (Denmark)

    Brænder, Morten; Andersen, Lotte Bøgh

    2014-01-01

    Based on our 2013-article, ”Does Deployment to War Affect Soldiers' Public Service Motivation – A Panel Study of Soldiers Before and After their Service in Afghanistan”, we present Panel Analysis as a methodological discipline. Panels consist of multiple units of analysis, observed at two or more...... in research settings where it is not possible to distribute units of analysis randomly or where the independent variables cannot be manipulated. The greatest disadvantage in regard to using panel studies is that data may be difficult to obtain. This is most clearly vivid in regard to the use of panel surveys...... points in time. In comparison with traditional cross-sectional studies, the advantage of using panel studies is that the time dimension enables us to study effects. Whereas experimental designs may have a clear advantage in regard to causal inference, the strength of panel studies is difficult to match...

  10. Effects of flutter and PEP mask physiotherapy on symptoms and lung function in children with cystic fibrosis

    NARCIS (Netherlands)

    C.M. van Winden; A. Visser (Adriaan); P.J. Sterk (Peter); S. Beckers; J.C. de Jongste (Johan); W.C.J. Hop (Wim)

    1998-01-01

    textabstractRecently, the flutter was introduced as a new device to improve sputum expectoration. Preliminary data suggested a significant improvement in expectoration and lung function during flutter treatment in patients with cystic fibrosis (CF). The aim of the

  11. Labyrinth Seal Flutter Analysis and Test Validation in Support of Robust Rocket Engine Design

    Science.gov (United States)

    El-Aini, Yehia; Park, John; Frady, Greg; Nesman, Tom

    2010-01-01

    High energy-density turbomachines, like the SSME turbopumps, utilize labyrinth seals, also referred to as knife-edge seals, to control leakage flow. The pressure drop for such seals is order of magnitude higher than comparable jet engine seals. This is aggravated by the requirement of tight clearances resulting in possible unfavorable fluid-structure interaction of the seal system (seal flutter). To demonstrate these characteristics, a benchmark case of a High Pressure Oxygen Turbopump (HPOTP) outlet Labyrinth seal was studied in detail. First, an analytical assessment of the seal stability was conducted using a Pratt & Whitney legacy seal flutter code. Sensitivity parameters including pressure drop, rotor-to-stator running clearances and cavity volumes were examined and modeling strategies established. Second, a concurrent experimental investigation was undertaken to validate the stability of the seal at the equivalent operating conditions of the pump. Actual pump hardware was used to construct the test rig, also referred to as the (Flutter Rig). The flutter rig did not include rotational effects or temperature. However, the use of Hydrogen gas at high inlet pressure provided good representation of the critical parameters affecting flutter especially the speed of sound. The flutter code predictions showed consistent trends in good agreement with the experimental data. The rig test program produced a stability threshold empirical parameter that separated operation with and without flutter. This empirical parameter was used to establish the seal build clearances to avoid flutter while providing the required cooling flow metering. The calibrated flutter code along with the empirical flutter parameter was used to redesign the baseline seal resulting in a flutter-free robust configuration. Provisions for incorporation of mechanical damping devices were introduced in the redesigned seal to ensure added robustness

  12. Model Reduction of Nonlinear Aeroelastic Systems Experiencing Hopf Bifurcation

    KAUST Repository

    Abdelkefi, Abdessattar

    2013-06-18

    In this paper, we employ the normal form to derive a reduced - order model that reproduces nonlinear dynamical behavior of aeroelastic systems that undergo Hopf bifurcation. As an example, we consider a rigid two - dimensional airfoil that is supported by nonlinear springs in the pitch and plunge directions and subjected to nonlinear aerodynamic loads. We apply the center manifold theorem on the governing equations to derive its normal form that constitutes a simplified representation of the aeroelastic sys tem near flutter onset (manifestation of Hopf bifurcation). Then, we use the normal form to identify a self - excited oscillator governed by a time - delay ordinary differential equation that approximates the dynamical behavior while reducing the dimension of the original system. Results obtained from this oscillator show a great capability to predict properly limit cycle oscillations that take place beyond and above flutter as compared with the original aeroelastic system.

  13. Simple quasi-analytical holonomic homogenization model for the non-linear analysis of in-plane loaded masonry panels: Part 2, structural implementation and validation

    Science.gov (United States)

    Milani, G.; Bertolesi, E.

    2017-07-01

    The simple quasi analytical holonomic homogenization approach for the non-linear analysis of in-plane loaded masonry presented in Part 1 is here implemented at a structural leveland validated. For such implementation, a Rigid Body and Spring Mass model (RBSM) is adopted, relying into a numerical modelling constituted by rigid elements interconnected by homogenized inelastic normal and shear springs placed at the interfaces between adjoining elements. Such approach is also known as HRBSM. The inherit advantage is that it is not necessary to solve a homogenization problem at each load step in each Gauss point, and a direct implementation into a commercial software by means of an external user supplied subroutine is straightforward. In order to have an insight into the capabilities of the present approach to reasonably reproduce masonry behavior at a structural level, non-linear static analyses are conducted on a shear wall, for which experimental and numerical data are available in the technical literature. Quite accurate results are obtained with a very limited computational effort.

  14. Influence of Shock Wave on the Flutter Behavior of Fan Blades Investigated

    Science.gov (United States)

    Srivastava, Rakesh; Bakhle, Milind A.; Stefko, George L.

    2003-01-01

    Modern fan designs have blades with forward sweep; a lean, thin cross section; and a wide chord to improve performance and reduce noise. These geometric features coupled with the presence of a shock wave can lead to flutter instability. Flutter is a self-excited dynamic instability arising because of fluid-structure interaction, which causes the energy from the surrounding fluid to be extracted by the vibrating structure. An in-flight occurrence of flutter could be catastrophic and is a significant design issue for rotor blades in gas turbines. Understanding the flutter behavior and the influence of flow features on flutter will lead to a better and safer design. An aeroelastic analysis code, TURBO, has been developed and validated for flutter calculations at the NASA Glenn Research Center. The code has been used to understand the occurrence of flutter in a forward-swept fan design. The forward-swept fan, which consists of 22 inserted blades, encountered flutter during wind tunnel tests at part speed conditions.

  15. Parametric Flutter Analysis of the TCA Configuration and Recommendation for FFM Design and Scaling

    Science.gov (United States)

    Baker, Myles; Lenkey, Peter

    1997-01-01

    The current HSR Aeroelasticity plan to design, build, and test a full span, free flying transonic flutter model in the TDT has many technical obstacles that must be overcome for a successful program. One technical obstacle is the determination of a suitable configuration and point in the sky to use in setting the scaling point for the ASE models program. Determining this configuration and point in the sky requires balancing several conflicting requirements, including model buildability, tunnel test safety, and the ability of the model to represent the flutter mechanisms of interest. As will be discussed in detail in subsequent sections, the current TCA design exhibits several flutter mechanisms of interest. It has been decided that the ASE models program will focus on the low frequency symmetric flutter mechanism, and will make no attempt to investigate high frequency flutter mechanisms. There are several reasons for this choice. First, it is believed that the high frequency flutter mechanisms are similar in nature to classical wing bending/torsion flutter, and therefore there is more confidence that this mechanism can be predicted using current techniques. The low frequency mode, on the other hand, is a highly coupled mechanism involving wing, body, tail, and engine motion which may be very difficult to predict. Second, the high frequency flutter modes result in very small weight penalties (several hundred pounds), while suppression of the low frequency mechanism inside the flight envelope causes thousands of pounds to be added to the structure. In order to successfully test the low frequency flutter mode of interest, a suitable starting configuration and point in the sky must be identified. The configuration and point in the sky must result in a wind tunnel model that (1) represents the low-frequency wing/body/engine/empennage flutter mechanisms that are unique to HSCT configurations, (2) flutters at an acceptably low frequency in the tunnel, (3) flutters at an

  16. Long-term endurance sport is a risk factor for development of lone atrial flutter.

    Science.gov (United States)

    Claessen, Guido; Colyn, Erwin; La Gerche, André; Koopman, Pieter; Alzand, Becker; Garweg, Christophe; Willems, Rik; Nuyens, Dieter; Heidbuchel, Hein

    2011-06-01

    To evaluate whether in a population of patients with 'lone atrial flutter', the proportion of those engaged in long-term endurance sports is higher than that observed in the general population. An age and sex-matched retrospective case-control study. A database with 638 consecutive patients who underwent ablation for atrial flutter at the University of Leuven. Sixty-one patients (55 men, 90%) fitted the inclusion criteria of 'lone atrial flutter', ie, aged 65 years or less, without documented atrial fibrillation and without identifiable underlying disease (including hypertension). Sex, age and inclusion criteria-matched controls, two for each flutter patient, were selected in a general practice in the same geographical region. Sports activity was evaluated by detailed questionnaires, which were available in 58 flutter patients (95%). A transthoracic echocardiogram was performed in all lone flutter patients. Types of sports, number of years of participation and average number of hours per week. The proportion of regular sportsmen (≥3 h of sports practice per week) among patients with lone atrial flutter was significantly higher than that observed in the general population (50% vs 17%; pendurance sports (participation in cycling, running or swimming for ≥3 h/week) was also significantly higher in lone flutter patients than in controls (31% vs 8%; p=0.0003). Those flutter patients performing endurance sports had a larger left atrium than non-sportsmen (p=0.04, by one-way analysis of variance). A history of endurance sports and subsequent left atrial remodelling may be a risk factor for the development of atrial flutter.

  17. Integrated analysis on static/dynamic aeroelasticity of curved panels based on a modified local piston theory

    Science.gov (United States)

    Yang, Zhichun; Zhou, Jian; Gu, Yingsong

    2014-10-01

    A flow field modified local piston theory, which is applied to the integrated analysis on static/dynamic aeroelastic behaviors of curved panels, is proposed in this paper. The local flow field parameters used in the modification are obtained by CFD technique which has the advantage to simulate the steady flow field accurately. This flow field modified local piston theory for aerodynamic loading is applied to the analysis of static aeroelastic deformation and flutter stabilities of curved panels in hypersonic flow. In addition, comparisons are made between results obtained by using the present method and curvature modified method. It shows that when the curvature of the curved panel is relatively small, the static aeroelastic deformations and flutter stability boundaries obtained by these two methods have little difference, while for curved panels with larger curvatures, the static aeroelastic deformation obtained by the present method is larger and the flutter stability boundary is smaller compared with those obtained by the curvature modified method, and the discrepancy increases with the increasing of curvature of panels. Therefore, the existing curvature modified method is non-conservative compared to the proposed flow field modified method based on the consideration of hypersonic flight vehicle safety, and the proposed flow field modified local piston theory for curved panels enlarges the application range of piston theory.

  18. Structural testing for static failure, flutter and other scary things

    Science.gov (United States)

    Ricketts, R. H.

    1983-01-01

    Ground test and flight test methods are described that may be used to highlight potential structural problems that occur on aircraft. Primary interest is focused on light-weight general aviation airplanes. The structural problems described include static strength failure, aileron reversal, static divergence, and flutter. An example of each of the problems is discussed to illustrate how the data acquired during the tests may be used to predict the occurrence of the structural problem. While some rules of thumb for the prediction of structural problems are given the report is not intended to be used explicitly as a structural analysis handbook.

  19. 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...... the flaps is presented. The length of the flaps attached to the girder, the flap configuration and the flap rotational angles are parameters used to increase the critical wind speed of the bridge. To illustrate the theory a numerical example is shown for a suspension bridge of 1000m+2500m+1000m span based...... on the Great Belt Bridge streamlined girder....

  20. New Flutter Analysis Technique for Time-Domain Computational Aeroelasticity

    Science.gov (United States)

    Pak, Chan-Gi; Lung, Shun-Fat

    2017-01-01

    A new time-domain approach for computing flutter speed is presented. Based on the time-history result of aeroelastic simulation, the unknown unsteady aerodynamics model is estimated using a system identification technique. The full aeroelastic model is generated via coupling the estimated unsteady aerodynamic model with the known linear structure model. The critical dynamic pressure is computed and used in the subsequent simulation until the convergence of the critical dynamic pressure is achieved. The proposed method is applied to a benchmark cantilevered rectangular wing.

  1. Development of Active Flutter Suppression Wind Tunnel Testing Technology

    Science.gov (United States)

    1975-01-01

    inch stainless steel precision haft ng out to the aileron surfaces. Torque was then transmitted aft through another crank-pushrod linkage...NMMltetiM Clllir llllisi Sl> ptT »I»" CmrN StiiiH tli!ii<ti> »ir|wu ŗK kUfej •*! AFFDL-TR-74-126 o 00 DEVELOPMENT OF ACTIVE FLUTTER...Installations . . 28 14. Outboard Aileron Installation 30 15. Airplane FMCS Block Diagram 35 16. Model FMCS Block Diagram 36 17. Model FMCS

  2. Contributions of Transonic Dynamics Tunnel Testing to Airplane Flutter Clearance

    Science.gov (United States)

    Rivera, Jose A.; Florance, James R.

    2000-01-01

    The Transonic Dynamics Tunnel (TDT) became in operational in 1960, and since that time has achieved the status of the world's premier wind tunnel for testing large in aeroelastically scaled models at transonic speeds. The facility has many features that contribute to its uniqueness for aeroelastic testing. This paper will briefly describe these capabilities and features, and their relevance to aeroelastic testing. Contributions to specific airplane configurations and highlights from the flutter tests performed in the TDT aimed at investigating the aeroelastic characteristics of these configurations are presented.

  3. Experimental Methods Applied in a Study of Stall Flutter in an Axial Flow Fan

    Directory of Open Access Journals (Sweden)

    John D. Gill

    2004-01-01

    Full Text Available Flutter testing is an integral part of aircraft gas turbine engine development. In typical flutter testing blade mounted sensors in the form of strain gages and casing mounted sensors in the form of light probes (NSMS are used. Casing mounted sensors have the advantage of being non-intrusive and can detect the vibratory response of each rotating blade. Other types of casing mounted sensors can also be used to detect flutter of rotating blades. In this investigation casing mounted high frequency response pressure transducers are used to characterize the part-speed stall flutter response of a single stage unshrouded axial-flow fan. These dynamic pressure transducers are evenly spaced around the circumference at a constant axial location upstream of the fan blade leading edge plane. The pre-recorded experimental data at 70% corrected speed is analyzed for the case where the fan is back-pressured into the stall flutter zone. The experimental data is analyzed using two probe and multi-probe techniques. The analysis techniques for each method are presented. Results from these two analysis methods indicate that flutter occurred at a frequency of 411 Hz with a dominant nodal diameter of 2. The multi-probe analysis technique is a valuable method that can be used to investigate the initiation of flutter in turbomachines.

  4. Effects of winglet on transonic flutter characteristics of a cantilevered twin-engine-transport wing model

    Science.gov (United States)

    Ruhlin, C. L.; Bhatia, K. G.; Nagaraja, K. S.

    1986-01-01

    A transonic model and a low-speed model were flutter tested in the Langley Transonic Dynamics Tunnel at Mach numbers up to 0.90. Transonic flutter boundaries were measured for 10 different model configurations, which included variations in wing fuel, nacelle pylon stiffness, and wingtip configuration. The winglet effects were evaluated by testing the transonic model, having a specific wing fuel and nacelle pylon stiffness, with each of three wingtips, a nonimal tip, a winglet, and a nominal tip ballasted to simulate the winglet mass. The addition of the winglet substantially reduced the flutter speed of the wing at transonic Mach numbers. The winglet effect was configuration-dependent and was primarily due to winglet aerodynamics rather than mass. Flutter analyses using modified strip-theory aerodynamics (experimentally weighted) correlated reasonably well with test results. The four transonic flutter mechanisms predicted by analysis were obtained experimentally. The analysis satisfactorily predicted the mass-density-ratio effects on subsonic flutter obtained using the low-speed model. Additional analyses were made to determine the flutter sensitivity to several parameters at transonic speeds.

  5. Panel Session

    DEFF Research Database (Denmark)

    Bertelsen, Olav Wedege

    2004-01-01

    In this panel session, four researchers will discuss the role of a theoretical foundation, in particular AT, in the design of information technology based artefacts. The general discussion will take of from a specific examination of the ActAD approach.......In this panel session, four researchers will discuss the role of a theoretical foundation, in particular AT, in the design of information technology based artefacts. The general discussion will take of from a specific examination of the ActAD approach....

  6. Semi-empirical model for prediction of unsteady forces on an airfoil with application to flutter

    Science.gov (United States)

    Mahajan, A. J.; Kaza, K. R. V.; Dowell, E. H.

    1993-01-01

    A semi-empirical model is described for predicting unsteady aerodynamic forces on arbitrary airfoils under mildly stalled and unstalled conditions. Aerodynamic forces are modeled using second order ordinary differential equations for lift and moment with airfoil motion as the input. This model is simultaneously integrated with structural dynamics equations to determine flutter characteristics for a two degrees-of-freedom system. Results for a number of cases are presented to demonstrate the suitability of this model to predict flutter. Comparison is made to the flutter characteristics determined by a Navier-Stokes solver and also the classical incompressible potential flow theory.

  7. Experimental transonic flutter characteristics of two 72 deg-sweep delta-wing models

    Science.gov (United States)

    Doggett, Robert V., Jr.; Soistmann, David L.; Spain, Charles V.; Parker, Ellen C.; Silva, Walter A.

    1989-01-01

    Transonic flutter boundaries are presented for two simple, 72 deg. sweep, low-aspect-ratio wing models. One model was an aspect-ratio 0.65 delta wing; the other model was an aspect-ratio 0.54 clipped-delta wing. Flutter boundaries for the delta wing are presented for the Mach number range of 0.56 to 1.22. Flutter boundaries for the clipped-delta wing are presented for the Mach number range of 0.72 to 0.95. Selected vibration characteristics of the models are also presented.

  8. Supercavitation hydrofoil performance and torsional flutter margin; Supercavitation yokugata no teijo hiteijo tokusei to nejiri flutter genkai

    Energy Technology Data Exchange (ETDEWEB)

    Matsudaira, Y.; Obara, H. [Tokyo Metropolitan Institute of Technology, Tokyo (Japan); Nakagawa, H. [Sumitomo Heavy Industries, Ltd., Tokyo (Japan); Yoshida, H. [Tokyo Metropolitan Institute of Technology, Tokyo (Japan)

    2000-08-25

    Supercavitation hydrofoil applied to high-speed marine propeller or hydro-machinery blade runs into unsteady behaviors such as cavitation breakdown and hydraulic flutter in some operation range. The hydrofoil performance was experimentally estimated and compared with the wedge performance using the cavitation tunnel and the torsional vibration apparatus with three component load cells, This experiment was carried out at several angles of attack in the region from subcavitation to supercavitation. At a general steady state but including some cavitation breakdowns, the hydrofoil has the most superior time mean lift/drag ratio about 6 < C{sub l}/C{sub d} < 8 at in all cavitation regions. But, the ratio drastically decreases as the angle of attack increases. Fluctuating lift coefficient C{sub l}{sup '} due to the cavitation breakdown reaches up to about 10% of time mean lift coefficient C{sub l}. At the hydrofoil pitching motion, the torsional flutter margin of the hydrofoil extends to higher reduced frequency side as the angle of attack increases and has the nearly same margin of the wedge in all cavitation regions. (author)

  9. Real Time Predictive Flutter Analysis and Continuous Parameter Identification of Accelerating Aircraft

    National Research Council Canada - National Science Library

    Farhat, Charles

    1998-01-01

    ... Parameter Identification of Accelerating Aircraft. Flutter clearance, which is part of any new aircraft or fighter weapon system development, is a lengthy and tedious process from both computational and flight testing viewpoint...

  10. Coupled-Mode Flutter of Wind Turbines and its Suppression Using Torsional Viscous Damper

    DEFF Research Database (Denmark)

    Zhang, Zili; Chen, Bei; Nielsen, Søren R. K.

    2017-01-01

    The trend towards lighter and more flexible blades may lead to aeroelastic instability of wind turbines under certain circumstances, resulting in rapid destructive failure or limit-cycle oscillations of the structural components. For pitch-regulated wind turbines, classical flutter is believed...... between blade vibrations with tower and drivetrain motions are also considered, making this model capable for coupled-mode flutter analysis of a complete wind turbine system. The parameters of the model have been calibrated to the DTU 10MW wind turbine, and the critical flutter speed of the rotor is shown...... to be about 1.6 times its nominal rotational speed. A novel torsional viscous damper is then proposed to suppress torsional blade vibration and to enhance flutter stability of wind turbines....

  11. Lipid Panel

    Science.gov (United States)

    ... A routine cardiac risk assessment typically includes a fasting lipid panel. Beyond that, research continues into the usefulness of other non-traditional markers of cardiac risk, such as Lp-PLA 2 . A health practitioner may choose to evaluate one or more ...

  12. Physics-Based Identification, Modeling and Risk Management for Aeroelastic Flutter and Limit-Cycle Oscillations (LCO), Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed research program will develop a physics-based identification, modeling and risk management infrastructure for aeroelastic transonic flutter and...

  13. Panel discussion

    International Nuclear Information System (INIS)

    Anon.

    1980-01-01

    The panel discussion at the 10th Allianz Forum on 'Technology and Insurance' dealt with the following topics: New technologies: energy conversion (coal, petroleum, natural gas, nuclear energy, solar energy); infrastructure (transport, data processing); basic products (metallic materials, chemical products, pharmaceutical products); integrated products (microprocessors, production line machines) as well as new risks: political; general economic (financing, market structure); insurance-related, dangers to persons and property; reduction of risks. (orig.) [de

  14. Clinical Differences between Subtypes of Atrial Fibrillation and Flutter: Cross-Sectional Registry of 407 Patients

    Directory of Open Access Journals (Sweden)

    Eduardo Dytz Almeida

    2015-01-01

    Full Text Available Introduction: Atrial fibrillation and atrial flutter account for one third of hospitalizations due to arrhythmias, determining great social and economic impacts. In Brazil, data on hospital care of these patients is scarce. Objective: To investigate the arrhythmia subtype of atrial fibrillation and flutter patients in the emergency setting and compare the clinical profile, thromboembolic risk and anticoagulants use. Methods: Cross-sectional retrospective study, with data collection from medical records of every patient treated for atrial fibrillation and flutter in the emergency department of Instituto de Cardiologia do Rio Grande do Sul during the first trimester of 2012. Results: We included 407 patients (356 had atrial fibrillation and 51 had flutter. Patients with paroxysmal atrial fibrillation were in average 5 years younger than those with persistent atrial fibrillation. Compared to paroxysmal atrial fibrillation patients, those with persistent atrial fibrillation and flutter had larger atrial diameter (48.6 ± 7.2 vs. 47.2 ± 6.2 vs. 42.3 ± 6.4; p < 0.01 and lower left ventricular ejection fraction (66.8 ± 11 vs. 53.9 ± 17 vs. 57.4 ± 16; p < 0.01. The prevalence of stroke and heart failure was higher in persistent atrial fibrillation and flutter patients. Those with paroxysmal atrial fibrillation and flutter had higher prevalence of CHADS2 score of zero when compared to those with persistent atrial fibrillation (27.8% vs. 18% vs. 4.9%; p < 0.01. The prevalence of anticoagulation in patients with CHA2DS2-Vasc ≤ 2 was 40%. Conclusions: The population in our registry was similar in its comorbidities and demographic profile to those of North American and European registries. Despite the high thromboembolic risk, the use of anticoagulants was low, revealing difficulties for incorporating guideline recommendations. Public health strategies should be adopted in order to improve these rates.

  15. A Nonlinear Modal Aeroelastic Solver for FUN3D

    Science.gov (United States)

    Goldman, Benjamin D.; Bartels, Robert E.; Biedron, Robert T.; Scott, Robert C.

    2016-01-01

    A nonlinear structural solver has been implemented internally within the NASA FUN3D computational fluid dynamics code, allowing for some new aeroelastic capabilities. Using a modal representation of the structure, a set of differential or differential-algebraic equations are derived for general thin structures with geometric nonlinearities. ODEPACK and LAPACK routines are linked with FUN3D, and the nonlinear equations are solved at each CFD time step. The existing predictor-corrector method is retained, whereby the structural solution is updated after mesh deformation. The nonlinear solver is validated using a test case for a flexible aeroshell at transonic, supersonic, and hypersonic flow conditions. Agreement with linear theory is seen for the static aeroelastic solutions at relatively low dynamic pressures, but structural nonlinearities limit deformation amplitudes at high dynamic pressures. No flutter was found at any of the tested trajectory points, though LCO may be possible in the transonic regime.

  16. Panel surveys

    OpenAIRE

    MADRE, JL; ZUMKELLER, D; CHLOND, B; ARMOOGUM, J

    2004-01-01

    l'analyse du comportement humain constitue un enjeu important dans le domaine des transports, lequel se transforme radicalement sous la pression des évolutions économique, écologique et démographique. les premières grandes études ont commence il y a plus d'une dizaine d'années : parc auto sofres en france, puget sound panel a seattle. cet article fait le bilan de ces expériences et met en évidence les principaux problèmes méthodologiques rencontres tout en proposant de nouvelles directions d'...

  17. Time simulation of flutter with large stiffness changes

    Science.gov (United States)

    Karpel, Mordechay; Wieseman, Carol D.

    1992-01-01

    Time simulation of flutter, involving large local structural changes, is formulated with a state-space model that is based on a relatively small number of generalized coordinates. Free-free vibration modes are first calculated for a nominal finite-element model with relatively large fictitious masses located at the area of structural changes. A low-frequency subset of these modes is then transformed into a set of structural modal coordinates with which the entire simulation is performed. These generalized coordinates and the associated oscillatory aerodynamic force coefficient matrices are used to construct an efficient time-domain, state-space model for a basic aeroelastic case. The time simulation can then be performed by simply changing the mass, stiffness, and damping coupling terms when structural changes occur. It is shown that the size of the aeroelastic model required for time simulation with large structural changes at a few apriori known locations is similar to that required for direct analysis of a single structural case. The method is applied to the simulation of an aeroelastic wind-tunnel model. The diverging oscillations are followed by the activation of a tip-ballast decoupling mechanism that stabilizes the system but may cause significant transient overshoots.

  18. Validation of double-spike electrograms as markers of conduction delay or block in atrial flutter.

    Science.gov (United States)

    Cosio, F G; Arribas, F; Barbero, J M; Kallmeyer, C; Goicolea, A

    1988-04-01

    Recent mapping studies of atrial flutter have shown that fragmented electrograms can be found in most cases from the posterior, posteroseptal and posterolateral walls of the right atrium. The fragmentation pattern most often consists of a double spike. To further assess double-spike electrograms as a possible marker of conduction delay, bipolar electrograms were continuously recorded during atrial overdrive pacing of common flutter from the right atrium (7 patients) and from the proximal coronary sinus (5). Baseline double-spike separation of 50 to 130 ms was unchanged in 1 patient and slightly increased (5 to 25 ms) in 4 by coronary sinus pacing. The electrogram sequence was unchanged and the surface morphology was similar to that of basal flutter. Right atrial pacing decreased double-spike separation by 25 to 85 ms from basal values of 45 to 175 ms (23 to 83%), suggesting fusion in the area of fragmented electrograms. These findings suggest that double-spike electrograms represent activation on both sides of a conduction delay zone. The changes induced in these electrograms by pacing from the anterior right atrium and the coronary sinus are consistent with flutter circuits rotating counterclockwise (frontal plane) in the posterior right atrial wall in common atrial flutter.

  19. Effects of flutter and PEP mask physiotherapy on symptoms and lung function in children with cystic fibrosis

    NARCIS (Netherlands)

    van Winden, C. M.; Visser, A.; Hop, W.; Sterk, P. J.; Beckers, S.; de Jongste, J. C.

    1998-01-01

    Recently, the flutter was introduced as a new device to improve sputum expectoration. Preliminary data suggested a significant improvement in expectoration and lung function during flutter treatment in patients with cystic fibrosis (CF). The aim of the present study was to compare the effects of the

  20. Panel cutting method: new approach to generate panels on a hull in Rankine source potential approximation

    Directory of Open Access Journals (Sweden)

    Hee-Jong Choi

    2011-12-01

    Full Text Available In the present study, a new hull panel generation algorithm, namely panel cutting method, was developed to predict flow phenomena around a ship using the Rankine source potential based panel method, where the iterative method was used to satisfy the nonlinear free surface condition and the trim and sinkage of the ship was taken into account. Numerical computations were performed to investigate the validity of the proposed hull panel generation algorithm for Series 60 (CB=0.60 hull and KRISO container ship (KCS, a container ship designed by Maritime and Ocean Engineering Research Institute (MOERI. The computational results were validated by comparing with the existing experimental data.

  1. Panel cutting method: new approach to generate panels on a hull in Rankine source potential approximation

    Science.gov (United States)

    Choi, Hee-Jong; Chun, Ho-Hwan; Park, Il-Ryong; Kim, Jin

    2011-12-01

    In the present study, a new hull panel generation algorithm, namely panel cutting method, was developed to predict flow phenomena around a ship using the Rankine source potential based panel method, where the iterative method was used to satisfy the nonlinear free surface condition and the trim and sinkage of the ship was taken into account. Numerical computations were performed to investigate the validity of the proposed hull panel generation algorithm for Series 60 (CB=0.60) hull and KRISO container ship (KCS), a container ship designed by Maritime and Ocean Engineering Research Institute (MOERI). The computational results were validated by comparing with the existing experimental data.

  2. The application of digital computers to near-real-time processing of flutter test data

    Science.gov (United States)

    Hurley, S. R.

    1976-01-01

    Procedures used in monitoring, analyzing, and displaying flight and ground flutter test data are presented. These procedures include three digital computer programs developed to process structural response data in near real time. Qualitative and quantitative modal stability data are derived from time history response data resulting from rapid sinusoidal frequency sweep forcing functions, tuned-mode quick stops, and pilot induced control pulses. The techniques have been applied to both fixed and rotary wing aircraft, during flight, whirl tower rotor systems tests, and wind tunnel flutter model tests. An hydraulically driven oscillatory aerodynamic vane excitation system utilized during the flight flutter test programs accomplished during Lockheed L-1011 and S-3A development is described.

  3. Work related physical activity and risk of a hospital discharge diagnosis of atrial fibrillation or flutter

    DEFF Research Database (Denmark)

    Frost, L; Frost, P; Vestergaard, P

    2005-01-01

    of atrial fibrillation or flutter associated with sedentary work in a standing position, light workload, or heavy workload in men or women. CONCLUSION: No evidence was found of an association between physical activities during working hours and risk of a hospital discharge diagnosis of atrial fibrillation......, Cancer, and Health Study. The physical strain during working hours was categorised as sedentary, light, or heavy, and analysed using proportional hazard models. Subjects were followed up in the Danish National Registry of Patients and in the Danish Civil Registration System. RESULTS: During follow up...... (mean 5.7 years) a hospital discharge diagnosis of atrial fibrillation or flutter occurred in 305 men and 113 women. When using the risk of atrial fibrillation or flutter associated with sedentary work at a sitting position as a reference, no excess risk (unadjusted as well as adjusted) was found...

  4. Comparison of analysis and flight test data for a drone aircraft with active flutter suppression

    Science.gov (United States)

    Newsom, J. R.; Pototzky, A. S.

    1981-01-01

    A drone aircraft equipped with an active flutter suppression system is considered with emphasis on the comparison of modal dampings and frequencies as a function of Mach number. Results are presented for both symmetric and antisymmetric motion with flutter suppression off. Only symmetric results are given for flutter suppression on. Frequency response functions of the vehicle are presented from both flight test data and analysis. The analysis correlation is improved by using an empirical aerodynamic correction factor which is proportional to the ratio of experimental to analytical steady-state lift curve slope. The mathematical models are included and existing analytical techniques are described as well as an alternative analytical technique for obtaining closed-loop results.

  5. Flutter analysis of hybrid metal-composite low aspect ratio trapezoidal wings in supersonic flow

    Directory of Open Access Journals (Sweden)

    Shokrollahi Saeed

    2017-02-01

    Full Text Available An effective 3D supersonic Mach box approach in combination with non-classical hybrid metal-composite plate theory has been used to investigate flutter boundaries of trapezoidal low aspect ratio wings. The wing structure is composed of two main components including aluminum material (in-board section and laminated composite material (out-board section. A global Ritz method is used with simple polynomials being employed as the trial functions. The most important objective of the present research is to study the effect of composite to metal proportion of hybrid wing structure on flutter boundaries in low supersonic regime. In addition, the effect of some important geometrical parameters such as sweep angle, taper ratio and aspect ratio on flutter boundaries were studied. The results obtained by present approach for special cases like pure metallic wings and results for high supersonic regime based on piston theory show a good agreement with those obtained by other investigators.

  6. Uncertainty Quantification of the FUN3D-Predicted NASA CRM Flutter Boundary

    Science.gov (United States)

    Stanford, Bret K.; Massey, Steven J.

    2017-01-01

    A nonintrusive point collocation method is used to propagate parametric uncertainties of the flexible Common Research Model, a generic transport configuration, through the unsteady aeroelastic CFD solver FUN3D. A range of random input variables are considered, including atmospheric flow variables, structural variables, and inertial (lumped mass) variables. UQ results are explored for a range of output metrics (with a focus on dynamic flutter stability), for both subsonic and transonic Mach numbers, for two different CFD mesh refinements. A particular focus is placed on computing failure probabilities: the probability that the wing will flutter within the flight envelope.

  7. Geared-elevator flutter study. [wind tunnel tests of transonic flutter effects on control surfaces of supersonic transport tail assemblies, conducted in a NASA-Langley transonic wind tunnel

    Science.gov (United States)

    Ruhlin, C. L.; Doggett, R. V., Jr.; Gregory, R. A.

    1976-01-01

    An experimental and analytical study was made of the transonic flutter characteristics of a supersonic transport tail assembly model having an all-movable, horizontal tail with a geared elevator. Two model configurations, namely, one with a gear-elevator (2.8 to 1.0 gear ratio) and one with locked-elevator (1.0 to 1.0 gear ratio), were flutter tested in the Langley transonic dynamics tunnel with an empennage cantilever-mounted on a sting. The geared-elevator configuration fluttered experimentally at about 20% higher dynamic pressures than the locked-elevator configuration. The experimental flutter dynamic pressure boundaries for both configurations were nearly flat over a Mach number range from 0.9 to 1.1. Flutter calculations (mathematical models) were made for the geared-elevator configuration using three subsonic lifting-surface methods. In one method, the elevator was treated as a discrete surface, and in the other two methods, the stabilizer and elevator were treated as a single warped-surface with the primary difference between these two methods being in the mathematical implementation used. A comparison of the experimental and analytical results shows that the discrete-elevator method predicted best the experimental flutter dynamic pressure level. However, the single warped-surface methods predicts more closely the experimental flutter frequencies and Mach number trends.

  8. Panel Discussion

    Science.gov (United States)

    Langer, James

    1997-03-01

    Panelists: Arthur Bienenstock, Stanford University Cherry Ann Murray, Lucent Technologies Venkatesh Narayanamurti, University of California-Santa Barbara Paul Peercy, SEMI-SEMATECH Robert Richardson, Cornell University James Roberto, Oak Ridge National Laboratory The Board on Physics and Astronomy is undertaking a series of reassessments of all branches of physics as the foundation of a new physics survey. As part of this project, a Committee on Condensed Matter and Materials Physics has been established under the leadership of Venkatesh Narayanamurti of the University of California-Santa Barbara. The committee has been working since June on a study that will include an illustrative recounting of major recent achievements; identification of new opportunities and challenges facing the field; and articulation-for leaders in government, industry, universities, and the public at large-of the important roles played by the field in modern society. An especially urgent issue is how to maintain the intellectual vitality of condensed matter and materials physics, and its contributions to the well-being of the United States, in an era of limited resources. The forum will feature a panel of materials researchers who are members of the Committee on Condensed Matter and Materials Physics. They will give a brief report on the status of the study and engage in a dialogue with the audience about issues facing the condensed matter and materials physics community. Broad community input is vital to the success of the study. Please come and make your voice heard!

  9. Elevated-Temperature Tests Under Static and Aerodynamic Conditions on Honeycomb-Core Sandwich Panels

    Science.gov (United States)

    Groen, Joseph M.; Johnson, Aldie E., Jr.

    1959-01-01

    Stainless-steel honeycomb-core sandwich panels which differed primarily in skin thicknesses were tested at elevated temperatures under static and aerodynamic conditions. The results of these tests were evaluated to determine the insulating effectiveness and structural integrity of the panels. The static radiant-heating tests were performed in front of a quartz-tube radiant heater at panel skin temperatures up to 1,5000 F. The aerodynamic tests were made in a Mach 1.4 heated blowdown wind tunnel. The tunnel temperature was augmented by additional heat supplied by a radiant heater which raised the panel surface temperature above 8000 F during air flow. Static radiant-heating tests of 2 minutes duration showed that all the panels protected the load-carrying structure about equally well. Thin-skin panels showed an advantage for this short-time test over thick-skin panels from a standpoint of weight against insulation. Permanent inelastic strains in the form of local buckles over each cell of the honeycomb core caused an increase in surface roughness. During the aero- dynamic tests all of the panels survived with little or no damage, and panel flutter did not occur.

  10. Hepatic (Liver) Function Panel

    Science.gov (United States)

    ... Educators Search English Español Blood Test: Hepatic (Liver) Function Panel KidsHealth / For Parents / Blood Test: Hepatic (Liver) ... kidneys ) is working. What Is a Hepatic (Liver) Function Panel? A liver function panel is a blood ...

  11. Comprehensive metabolic panel

    Science.gov (United States)

    Metabolic panel - comprehensive; Chem-20; SMA20; Sequential multi-channel analysis with computer-20; SMAC20; Metabolic panel 20 ... Chernecky CC, Berger BJ. Comprehensive metabolic panel (CMP) - blood. In: ... Tests and Diagnostic Procedures . 6th ed. St Louis, MO: ...

  12. Transonic flutter study of a wind-tunnel model of a supercritical wing with/without winglet

    Science.gov (United States)

    Ruhlin, C. L.; Rauch, F. J., Jr.; Waters, C.

    1982-01-01

    The scaled flutter model was a 1/6.5-size, semispan version of a supercritical wing (SCW) proposed for an executive-jet-transport airplane. The model was tested cantilever-mounted with a normal wingtip, a wingtip with winglet, and a normal wingtip ballasted to simulate the winglet mass properties. Flutter and aerodynamic data were acquired at Mach numbers from 0.6 to 0.95. The measured transonic flutter speed boundary for each wingtip configuration had roughly the same shape with a minimum flutter speed near M = 0.82. The winglet addition and wingtip mass ballast decreased the wing flutter speed by about 7 and 5%, respectively; thus, the winglet effect on flutter was more a mass effect than an aerodynamic effect. Flutter characteristics calculated using a doublet-lattice analysis (which included interference effects) were in good agreement with the experimental results up to M = 0.82. Comparisons of measured static aerodynamic data with predicted data indicated that the model was aerodynamically representative of the airplane SCW.

  13. Active aeroelastic flutter analysis and vibration control of supersonic beams using the piezoelectric actuator/sensor pairs

    International Nuclear Information System (INIS)

    Song, Zhi-Guang; Li, Feng-Ming

    2011-01-01

    The active vibration control of all kinds of structures by using the piezoelectric material has been extensively investigated. In this paper, the active aeroelastic flutter characteristics and vibration control of supersonic beams applying the piezoelectric material are studied further. The piezoelectric materials are bonded on the top and bottom surfaces of the beams to act as the actuator and sensor so that the active aeroelastic flutter suppression for the supersonic beams can be conducted. The supersonic piston theory is adopted to evaluate the aerodynamic pressure. Hamilton's principle with the assumed mode method is used to develop the dynamical model of the structural systems. By using the standard eigenvalue methodology, the solutions for the complex eigenvalue problem are obtained. A negative velocity feedback control strategy is used to obtain active damping. The aeroelastic flutter bounds are calculated and the active aeroelastic flutter characteristics are analyzed. The impulse responses of the structural system are obtained by using the Houbolt numerical algorithm to study the active aeroelastic vibration control. The influences of the non-dimensional aerodynamic pressure on the active flutter control are analyzed. From the numerical results it is observed that the aeroelastic flutter characteristics of the supersonic beams can be significantly improved and that the aeroelastic vibration amplitudes can be remarkably reduced, especially at the flutter points, by using the piezoelectric actuator/sensor pairs which can provide an active damping. Within a certain value of the feedback control gain, with the increase of it, the flutter aerodynamic pressure (or flutter velocity) can be increased and the control results are also improved

  14. Effect of blade flutter and electrical loading on small wind turbine noise

    Science.gov (United States)

    The effect of blade flutter and electrical loading on the noise level of two different size wind turbines was investigated at the Conservation and Production Research Laboratory (CPRL) near Bushland, TX. Noise and performance data were collected on two blade designs tested on a wind turbine rated a...

  15. Comparison of driven and simulated "free" stall flutter in a wind tunnel

    Science.gov (United States)

    Culler, Ethan; Farnsworth, John; Fagley, Casey; Seidel, Jurgen

    2016-11-01

    Stall flutter and dynamic stall have received a significant amount of attention over the years. To experimentally study this problem, the body undergoing stall flutter is typically driven at a characteristic, single frequency sinusoid with a prescribed pitching amplitude and mean angle of attack offset. This approach allows for testing with repeatable kinematics, however it effectively decouples the structural motion from the aerodynamic forcing. Recent results suggest that this driven approach could misrepresent the forcing observed in a "free" stall flutter scenario. Specifically, a dynamically pitched rigid NACA 0018 wing section was tested in the wind tunnel under two modes of operation: (1) Cyber-Physical where "free" stall flutter was physically simulated through a custom motor-control system modeling a torsional spring and (2) Direct Motor-Driven Dynamic Pitch at a single frequency sinusoid representative of the cyber-physical motion. The time-resolved pitch angle and moment were directly measured and compared for each case. It was found that small deviations in the pitch angle trajectory between these two operational cases generate significantly different aerodynamic pitching moments on the wing section, with the pitching moments nearly 180o out of phase in some cases. This work is supported by the Air Force Office of Scientific Research through the Flow Interactions and Control Program and by the National Defense Science and Engineering Graduate Fellowship Program.

  16. Measuring of the profile vibration on the flutter critic flow velocity

    Czech Academy of Sciences Publication Activity Database

    Zolotarev, Igor; Vlček, Václav; Kozánek, Jan

    2015-01-01

    Roč. 4, č. 2 (2015), s. 45-45 ISSN 2168-9792. [International Conference and Exhibition on MECHANICAL & AEROSPACE ENGINEERING /3./. 05.10.2015-07.10.2015, San Francisco] R&D Projects: GA ČR GA13-10527S Institutional support: RVO:61388998 Keywords : aeroelasticity * flutter * subsonic flow Subject RIV: BI - Acoustics

  17. The flow field acting on the fluttering profile, kinematics, forces and total moment

    Czech Academy of Sciences Publication Activity Database

    Kozánek, Jan; Vlček, Václav; Zolotarev, Igor

    2013-01-01

    Roč. 13, č. 7 (2013), s. 1-7 ISSN 0219-4554 R&D Projects: GA ČR GA101/09/1522 Institutional support: RVO:61388998 Keywords : fluttering profile * interferometry visualization * acting forces and moment Subject RIV: JU - Aeronautics, Aerodynamics, Aircrafts Impact factor: 1.059, year: 2013

  18. Atrial flutter ablation in a case of diuretic resistant constrictive pericarditis

    Directory of Open Access Journals (Sweden)

    James F. Pittaway

    2015-07-01

    This is the first reported case of symptomatic improvement in a patient with constrictive pericarditis and persistent atrial flutter with targeted treatment of the dysrhythmia. This offers a possible short-term palliation option in a group of patients where definitive surgical management carries too high a risk.

  19. Critical and post-critical behaviour of two-degree-of-freedom flutter-based generators

    Science.gov (United States)

    Pigolotti, Luca; Mannini, Claudio; Bartoli, Gianni; Thiele, Klaus

    2017-09-01

    Energy harvesting from flow-induced vibrations is a recent research field, which considers a diverse range of systems, among which two-degree-of-freedom flutter-based solutions were individuated as good candidates to obtain high energy performance. In the present work, numerical linear analyses and wind-tunnel tests were conducted on a flat-plate sectional model. The aim is to identify some design guidelines for generators exploiting the classical-flutter instability, through the investigation of the critical condition and the response during the post-critical regime. Many sets of governing parameters of interest from the energy-harvesting point of view were considered, including high levels of heaving damping to simulate the operation of a conversion apparatus. In particular, eccentricity of the elastic centre and small downstream mass unbalance can be introduced as solutions aiming at optimal operative ranges. The collected results suggest the high potentiality of flutter-based generators, and a significant enhancement of performance can be envisaged. Moreover, they contribute to improve the knowledge of the flutter excitation mechanism and to widen the dataset of measurements in the post-critical regime.

  20. Digoxin versus placebo, no intervention, or other medical interventions for atrial fibrillation and atrial flutter

    DEFF Research Database (Denmark)

    Sethi, Naqash; Safi, Sanam; Feinberg, Joshua

    2017-01-01

    BACKGROUND: Atrial fibrillation is the most common arrhythmia of the heart with a prevalence of approximately 2% in the western world. Atrial flutter, another arrhythmia, occurs less often with an incidence of approximately 200,000 new patients per year in the USA. Patients with atrial fibrillati...

  1. Congenital toxoplasmosis presenting with fetal atrial flutter after maternal ingestion of infected moose meat.

    Science.gov (United States)

    Colosimo, Sarah M; Montoya, Jose G; Westley, Benjamin P; Jacob, Jack; Isada, Nelson B

    2013-09-01

    Consumption of undercooked game meat during pregnancy is considered a risk factor for congenital toxoplasmosis, but cases definitively linking ingestion of infected meat to clinical disease are lacking. We report a confirmed case of congenital toxoplasmosis identified because of atrial flutter in the fetus and linked to maternal consumption of Toxoplasma gondii PCR-positive moose meat.

  2. Flutter suppression and stability analysis for a variable-span wing via morphing technology

    Science.gov (United States)

    Li, Wencheng; Jin, Dongping

    2018-01-01

    A morphing wing can enhance aerodynamic characteristics and control authority as an alternative to using ailerons. To use morphing technology for flutter suppression, the dynamical behavior and stability of a variable-span wing subjected to the supersonic aerodynamic loads are investigated numerically in this paper. An axially moving cantilever plate is employed to model the variable-span wing, in which the governing equations of motion are established via the Kane method and piston theory. A morphing strategy based on axially moving rates is proposed to suppress the flutter that occurs beyond the critical span length, and the flutter stability is verified by Floquet theory. Furthermore, the transient stability during the morphing motion is analyzed and the upper bound of the morphing rate is obtained. The simulation results indicate that the proposed morphing law, which is varying periodically with a proper amplitude, could accomplish the flutter suppression. Further, the upper bound of the morphing speed decreases rapidly once the span length is close to its critical span length.

  3. Pharmacologic versus direct-current electrical cardioversion of atrial flutter and fibrillation

    NARCIS (Netherlands)

    Van Gelder, IC; Tuinenburg, AE; Schoonderwoerd, BS; Tieleman, RG; Crijns, HJGM

    1999-01-01

    Conversion of atrial flutter and atrial fibrillation (AF) can be achieved by either pharmacologic or direct-current (DC) electrical cardioversion. DC electrical cardioversion is more effective and restores sinus rhythm instantaneously; however, general anesthesia is necessary, which can cause severe

  4. The influence of Flutter®VRP1 components on mucus transport of patients with bronchiectasis.

    Science.gov (United States)

    Tambascio, Joana; de Souza, Léa Tatiana; Lisboa, Roberta M; Passarelli, Rita de Cássia V; de Souza, Hugo Celso Dutra; Gastaldi, Ada Clarice

    2011-09-01

    The Flutter(®)VRP1 combines high frequency oscillation and positive expiratory pressure (PEP). To separately evaluate the effect of the Flutter(®)VRP1 components (high frequency oscillation and PEP) on mucus transportability in patients with bronchiectasis. Eighteen patients with bronchiectasis received sessions with the Flutter(®)VRP1 or PEP for 30 min daily in a randomized, crossover study. The treatment duration was four weeks with one of the therapies, one week of a "wash-out" period and followed by four more weeks with the other treatment. Weekly secretion samples were collected and evaluated for mucociliary relative transport velocity (RTV), displacement in a simulated cough machine (SCM) and contact angle measurement (CAM). For the proposed comparisons, a linear regression model was used with mixed effects with a significance level of 5%. The Flutter(®)VRP1 treatment resulted in greater displacement in SCM and lower CAM when comparing results from the first (9.6 ± 3.4 cm and 29.4 ± 5.7°, respectively) and fourth weeks of treatment (12.44 ± 10.5 cm and 23.28 ± 6.2°, respectively; p component. Copyright © 2011 Elsevier Ltd. All rights reserved.

  5. Numerical analysis of flow-induced nonlinear vibrations of an airfoil with three degrees of freedom

    Czech Academy of Sciences Publication Activity Database

    Feistauer, M.; Horáček, Jaromír; Růžička, M.; Sváček, P.

    2011-01-01

    Roč. 49, č. 1 (2011), s. 110-127 ISSN 0045-7930 R&D Projects: GA ČR(CZ) GAP101/11/0207 Institutional research plan: CEZ:AV0Z20760514 Keywords : aeroelasticity * Navier-Stokes equation * non-linear oscillations * flutter instability Subject RIV: BI - Acoustics Impact factor: 1.810, year: 2011 http://www.sciencedirect.com/science/article/pii/S0045793011001538

  6. Multirate flutter suppression system design for the Benchmark Active Controls Technology Wing

    Science.gov (United States)

    Berg, Martin C.; Mason, Gregory S.

    1994-01-01

    To study the effectiveness of various control system design methodologies, the NASA Langley Research Center initiated the Benchmark Active Controls Project. In this project, the various methodologies will be applied to design a flutter suppression system for the Benchmark Active Controls Technology (BACT) Wing (also called the PAPA wing). Eventually, the designs will be implemented in hardware and tested on the BACT wing in a wind tunnel. This report describes a project at the University of Washington to design a multirate flutter suppression system for the BACT wing. The objective of the project was two fold. First, to develop a methodology for designing robust multirate compensators, and second, to demonstrate the methodology by applying it to the design of a multirate flutter suppression system for the BACT wing. The contributions of this project are (1) development of an algorithm for synthesizing robust low order multirate control laws (the algorithm is capable of synthesizing a single compensator which stabilizes both the nominal plant and multiple plant perturbations; (2) development of a multirate design methodology, and supporting software, for modeling, analyzing and synthesizing multirate compensators; and (3) design of a multirate flutter suppression system for NASA's BACT wing which satisfies the specified design criteria. This report describes each of these contributions in detail. Section 2.0 discusses our design methodology. Section 3.0 details the results of our multirate flutter suppression system design for the BACT wing. Finally, Section 4.0 presents our conclusions and suggestions for future research. The body of the report focuses primarily on the results. The associated theoretical background appears in the three technical papers that are included as Attachments 1-3. Attachment 4 is a user's manual for the software that is key to our design methodology.

  7. Appraisal of Method of Flutter Analysis Based on Chosen Modes by Comparison with Experiment for Cases of Large Mass Coupling

    National Research Council Canada - National Science Library

    Woolston, Donald

    1949-01-01

    The present paper reports the results of a series of flutter studies including comparisons of experimental results with calculations based on a Rayleigh type analysis, in which chosen modes are assumed...

  8. Influence of gravity on flutter of cantilevered pipes conveying fluid

    Science.gov (United States)

    Rivero, Javier; Perez-Saborid, Miguel

    2012-11-01

    We have considered the dynamics of the nonlinear interaction between a flexible pipe and the conveyed fluid in the presence of gravity. The stability of the system (fllutter and buckling) depends on parameters such as the dimensionless fluid flow rate, the gravity to bending stiffness ratio and the fluid to pipe mass ratio and it has been studied in detail both numerically and experimentally. It has also been found that the stabilizing or destabilizing effects of fluid flow depends crucially on the direction of gravity respect to the undeformed midline of the pipe. We have also computed the post-critical behavior of the system by solving the full nonlinear equations of the problem and analyzed the transfer of energy within the system in the nonlinear regime. We have formulated the problem in terms of the angles of the midline of the pipe instead of its transverse displacements, so that we can deal with large deflections without recurring to the quasi-linear approximations concerning the pipe curvature usually made in the literature. Supported by the Ministerio de Educación, Cultura y Deportes of Spain under grant DPI 2010-20450 C03-02.

  9. Nonlinear optics

    International Nuclear Information System (INIS)

    Boyd, R.W.

    1992-01-01

    Nonlinear optics is the study of the interaction of intense laser light with matter. This book is a textbook on nonlinear optics at the level of a beginning graduate student. The intent of the book is to provide an introduction to the field of nonlinear optics that stresses fundamental concepts and that enables the student to go on to perform independent research in this field. This book covers the areas of nonlinear optics, quantum optics, quantum electronics, laser physics, electrooptics, and modern optics

  10. 1C-INDUCED ATRIAL FLUTTER IN A PATIENT WITH WPW SYNDROME: CASE REPORT AND REVIEW

    Directory of Open Access Journals (Sweden)

    R. R. Mamatkazina

    2015-12-01

    Full Text Available The clinical case of a rare proarrhythmic effect of antiarrhythmic drugs with a poor prognosis (medication-induced atrial flutter in a patient with "malignant" Kent’s bundle is presented. Radiofrequency ablation (RFA is the most justified treatment method in patients with WPW-syndrome and "malignant" Kent’s bundle. RFA in descripted case has been postponed due to technical reasons. While waiting for RFA and after consideration of the potential risks and benefits the decision to use antiarrhythmic drugs to block the additional bundle was made. Paroxysm of broad-complex tachycardia developed on the third day of the treatment. It was regarded as a paroxysm of atrial fibrillation/flutter in the patient with WPW syndrome induced by taking antiarrhythmic drugs class 1C (allapinine. Review of the literature on the atrial fibrillation induced by antiarrhythmic of 1C class, and association of atrial fibrillation with WPW-syndrome is presented.

  11. 1C-INDUCED ATRIAL FLUTTER IN A PATIENT WITH WPW SYNDROME: CASE REPORT AND REVIEW

    Directory of Open Access Journals (Sweden)

    R. R. Mamatkazina

    2012-01-01

    Full Text Available The clinical case of a rare proarrhythmic effect of antiarrhythmic drugs with a poor prognosis (medication-induced atrial flutter in a patient with "malignant" Kent’s bundle is presented. Radiofrequency ablation (RFA is the most justified treatment method in patients with WPW-syndrome and "malignant" Kent’s bundle. RFA in descripted case has been postponed due to technical reasons. While waiting for RFA and after consideration of the potential risks and benefits the decision to use antiarrhythmic drugs to block the additional bundle was made. Paroxysm of broad-complex tachycardia developed on the third day of the treatment. It was regarded as a paroxysm of atrial fibrillation/flutter in the patient with WPW syndrome induced by taking antiarrhythmic drugs class 1C (allapinine. Review of the literature on the atrial fibrillation induced by antiarrhythmic of 1C class, and association of atrial fibrillation with WPW-syndrome is presented.

  12. Computational and experimental investigation of free vibration and flutter of bridge decks

    Science.gov (United States)

    Helgedagsrud, Tore A.; Bazilevs, Yuri; Mathisen, Kjell M.; Øiseth, Ole A.

    2018-06-01

    A modified rigid-object formulation is developed, and employed as part of the fluid-object interaction modeling framework from Akkerman et al. (J Appl Mech 79(1):010905, 2012. https://doi.org/10.1115/1.4005072) to simulate free vibration and flutter of long-span bridges subjected to strong winds. To validate the numerical methodology, companion wind tunnel experiments have been conducted. The results show that the computational framework captures very precisely the aeroelastic behavior in terms of aerodynamic stiffness, damping and flutter characteristics. Considering its relative simplicity and accuracy, we conclude from our study that the proposed free-vibration simulation technique is a valuable tool in engineering design of long-span bridges.

  13. Flight Flutter Testing of Rotary Wing Aircraft Using a Control System Oscillation Technique

    Science.gov (United States)

    Yen, J. G.; Viswanathan, S.; Matthys, C. G.

    1976-01-01

    A flight flutter testing technique is described in which the rotor controls are oscillated by series actuators to excite the rotor and airframe modes of interest, which are then allowed to decay. The moving block technique is then used to determine the damped frequency and damping variation with rotor speed. The method proved useful for tracking the stability of relatively well damped modes. The results of recently completed flight tests of an experimental soft-in-plane rotor are used to illustrate the technique. Included is a discussion of the application of this technique to investigation of the propeller whirl flutter stability characteristics of the NASA/Army XV-15 VTOL tilt rotor research aircraft.

  14. Nonlinear optics

    CERN Document Server

    Bloembergen, Nicolaas

    1996-01-01

    Nicolaas Bloembergen, recipient of the Nobel Prize for Physics (1981), wrote Nonlinear Optics in 1964, when the field of nonlinear optics was only three years old. The available literature has since grown by at least three orders of magnitude.The vitality of Nonlinear Optics is evident from the still-growing number of scientists and engineers engaged in the study of new nonlinear phenomena and in the development of new nonlinear devices in the field of opto-electronics. This monograph should be helpful in providing a historical introduction and a general background of basic ideas both for expe

  15. Comparison of Temporal Parameters of Swimming Rescue Elements When Performed Using Dolphin and Flutter Kick with Fins - Didactical Approach

    Science.gov (United States)

    Rejman, Marek; Wiesner, Wojciech; Silakiewicz, Piotr; Klarowicz, Andrzej; Abraldes, J. Arturo

    2012-01-01

    The aim of this study was an analysis of the time required to swim to a victim and tow them back to shore, while perfoming the flutter-kick and the dolphin-kick using fins. It has been hypothesized that using fins while using the dolphin-kick when swimming leads to reduced rescue time. Sixteen lifeguards took part in the study. The main tasks performed by them, were to approach and tow (double armpit) a dummy a distance of 50m while applying either the flutter-kick, or the dolphin-kick with fins. The analysis of the temporal parameters of both techniques of kicking demonstrates that, during the approach to the victim, neither the dolphin (tmean = 32.9s) or the flutter kick (tmean = 33.0s) were significantly faster than the other. However, when used for towing a victim the flutter kick (tmean = 47.1s) was significantly faster when compared to the dolphin-kick (tmean = 52.8s). An assessment of the level of technical skills in competitive swimming, and in approaching and towing the victim, were also conducted. Towing time was significantly correlated with the parameter that linked the temporal and technical dimensions of towing and swimming (difference between flutter kick towing time and dolphin-kick towing time, 100m medley time and the four swimming strokes evaluation). No similar interdependency has been discovered in flutter kick towing time. These findings suggest that the dolphin-kick is a more difficult skill to perform when towing the victim than the flutter-kick. Since the hypothesis stated was not confirmed, postulates were formulated on how to improve dolphin-kick technique with fins, in order to reduce swimming rescue time. Key points The source of reduction of swimming rescue time was researched. Time required to approach and to tow the victim while doing the flutter kick and the dolphin-kick with fins was analyzed. The propulsion generated by dolphin-kick did not make the approach and tow faster than the flutter kick. More difficult skill to realize of

  16. Predictors of Sick Sinus Syndrome in Patients after Successful Radiofrequency Catheter Ablation of Atrial Flutter

    OpenAIRE

    Song, Changho; Jin, Moo-Nyun; Lee, Jung-Hee; Kim, In-Soo; Uhm, Jae-Sun; Pak, Hui-Nam; Lee, Moon-Hyoung; Joung, Boyoung

    2014-01-01

    Purpose The identification of sick sinus syndrome (SSS) in patients with atrial flutter (AFL) is difficult before the termination of AFL. This study investigated the patient characteristics used in predicting a high risk of SSS after AFL ablation. Materials and Methods Out of 339 consecutive patients who had undergone radiofrequency ablation for AFL from 1991 to 2012, 27 (8%) had SSS (SSS group). We compared the clinical characteristics of patients with and without SSS (n=312, no-SSS group). ...

  17. Robust Switching Control and Subspace Identification for Flutter of Flexible Wing

    Directory of Open Access Journals (Sweden)

    Yizhe Wang

    2018-01-01

    Full Text Available Active flutter suppression and subspace identification for a flexible wing model using micro fiber composite actuator were experimentally studied in a low speed wind tunnel. NACA0006 thin airfoil model was used for the experimental object to verify the performance of identification algorithm and designed controller. The equation of the fluid, vibration, and piezoelectric coupled motion was theoretically analyzed and experimentally identified under the open-loop and closed-loop condition by subspace method for controller design. A robust pole placement algorithm in terms of linear matrix inequality that accommodates the model uncertainty caused by identification deviation and flow speed variation was utilized to stabilize the divergent aeroelastic system. For further enlarging the flutter envelope, additional controllers were designed subject to the models beyond the flutter speed. Wind speed was measured online as the decision parameter of switching between the controllers. To ensure the stability of arbitrary switching, Common Lyapunov function method was applied to design the robust pole placement controllers for different models to ensure that the closed-loop system shared a common Lyapunov function. Wind tunnel result showed that the designed controllers could stabilize the time varying aeroelastic system over a wide range under arbitrary switching.

  18. Atrial flutter with 1:1 conduction in undiagnosed Wolff-Parkinson-White syndrome.

    Science.gov (United States)

    Nelson, Jessie G; Zhu, Dennis W

    2014-05-01

    Atrial flutter with 1:1 atrioventricular conduction via an accessory pathway is an uncommon presentation of Wolff-Parkinson-White syndrome not previously reported in the emergency medicine literature. Wolff-Parkinson-White syndrome, a form of ventricular preexcitation sometimes initially seen and diagnosed in the emergency department (ED), can present with varied tachydysrhythmias for which certain treatments are contraindicated. For instance, atrial fibrillation with preexcited conduction needs specific consideration of medication choice to avoid potential degeneration into ventricular fibrillation. We describe an adult female presenting with a very rapid, regular wide complex tachycardia successfully cardioverted in the ED followed by a normal electrocardiogram (ECG). Electrophysiology study confirmed atrial flutter with 1:1 conduction and revealed an accessory pathway consistent with Wolff-Parkinson-White syndrome, despite lack of ECG findings of preexcitation during sinus rhythm. Why should an emergency physician be aware of this? Ventricular tachycardia must be the first consideration in patients with regular wide complex tachycardia. However, clinicians should consider atrial flutter with 1:1 conduction related to an accessory pathway when treating patients with the triad of very rapid rate (>250 beats/min), wide QRS complex, and regular rhythm, especially when considering pharmacologic treatment. Emergency physicians also should be aware of electrocardiographically concealed accessory pathways, and that lack of delta waves does not rule out preexcitation syndromes such as Wolff-Parkinson-White syndrome. Copyright © 2014 Elsevier Inc. All rights reserved.

  19. Influence of upstream stator on rotor flutter stability in a low pressure steam turbine stage

    Energy Technology Data Exchange (ETDEWEB)

    Huang, X.; He, L. [University of Durham (United Kingdom). School of Engineering; Bell, D. [ALSTOM Power Ltd., Rugby (United Kingdom)

    2006-07-01

    Conventional blade flutter prediction is normally based on an isolated blade row model, however, little is known about the influence of adjacent blade rows. In this article, an investigation is presented into the influence of the upstream stator row on the aero-elastic stability of rotor blades in the last stage of a low pressure (LP) steam turbine. The influence of the upstream blade row is computed directly by a time-marching, unsteady, Navier-Stokes flow solver in a stator-rotor coupled computational domain. The three-dimensional flutter solution is obtained, with adequate mesh resolution, in a single passage domain through application of the Fourier-Transform based Shape-Correction method. The capability of this single-passage method is examined through comparison with predictions obtained from a complete annulus model, and the results demonstrate a good level of accuracy, while achieving a speed up factor of 25. The present work shows that the upstream stator blade row can significantly change the aero-elastic behaviour of an LP steam turbine rotor. Caution is, therefore, advised when using an isolated blade row model for blade flutter prediction. The results presented also indicated that the intra-row interaction is of a strong three-dimensional nature. (author)

  20. Identification of reduced-order model for an aeroelastic system from flutter test data

    Directory of Open Access Journals (Sweden)

    Wei Tang

    2017-02-01

    Full Text Available Recently, flutter active control using linear parameter varying (LPV framework has attracted a lot of attention. LPV control synthesis usually generates controllers that are at least of the same order as the aeroelastic models. Therefore, the reduced-order model is required by synthesis for avoidance of large computation cost and high-order controller. This paper proposes a new procedure for generation of accurate reduced-order linear time-invariant (LTI models by using system identification from flutter testing data. The proposed approach is in two steps. The well-known poly-reference least squares complex frequency (p-LSCF algorithm is firstly employed for modal parameter identification from frequency response measurement. After parameter identification, the dominant physical modes are determined by clear stabilization diagrams and clustering technique. In the second step, with prior knowledge of physical poles, the improved frequency-domain maximum likelihood (ML estimator is presented for building accurate reduced-order model. Before ML estimation, an improved subspace identification considering the poles constraint is also proposed for initializing the iterative procedure. Finally, the performance of the proposed procedure is validated by real flight flutter test data.

  1. Hepatitis virus panel

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/003558.htm Hepatitis virus panel To use the sharing features on this page, please enable JavaScript. The hepatitis virus panel is a series of blood tests used ...

  2. Antinuclear antibody panel

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/003535.htm Antinuclear antibody panel To use the sharing features on this page, please enable JavaScript. The antinuclear antibody panel is a blood test that looks at ...

  3. Paneling architectural freeform surfaces

    KAUST Repository

    Eigensatz, Michael; Kilian, Martin; Schiftner, Alexander; Mitra, Niloy J.; Pottmann, Helmut; Pauly, Mark

    2010-01-01

    with a selected technology at reasonable cost, while meeting the design intent and achieving the desired aesthetic quality of panel layout and surface smoothness. The production of curved panels is mostly based on molds. Since the cost of mold fabrication

  4. Bifurcation and chaos analysis for aeroelastic airfoil with freeplay structural nonlinearity in pitch

    International Nuclear Information System (INIS)

    De-Min, Zhao; Qi-Chang, Zhang

    2010-01-01

    The dynamics character of a two degree-of-freedom aeroelastic airfoil with combined freeplay and cubic stiffness nonlinearities in pitch submitted to supersonic and hypersonic flow has been gaining significant attention. The Poincaré mapping method and Floquet theory are adopted to analyse the limit cycle oscillation flutter and chaotic motion of this system. The result shows that the limit cycle oscillation flutter can be accurately predicted by the Floquet multiplier. The phase trajectories of both the pitch and plunge motion are obtained and the results show that the plunge motion is much more complex than the pitch motion. It is also proved that initial conditions have important influences on the dynamics character of the airfoil system. In a certain range of airspeed and with the same system parameters, the stable limit cycle oscillation, chaotic and multi-periodic motions can be detected under different initial conditions. The figure of the Poincaré section also approves the previous conclusion

  5. Nonlinear Science

    CERN Document Server

    Yoshida, Zensho

    2010-01-01

    This book gives a general, basic understanding of the mathematical structure "nonlinearity" that lies in the depths of complex systems. Analyzing the heterogeneity that the prefix "non" represents with respect to notions such as the linear space, integrability and scale hierarchy, "nonlinear science" is explained as a challenge of deconstruction of the modern sciences. This book is not a technical guide to teach mathematical tools of nonlinear analysis, nor a zoology of so-called nonlinear phenomena. By critically analyzing the structure of linear theories, and cl

  6. Nonlinear oscillations

    CERN Document Server

    Nayfeh, Ali Hasan

    1995-01-01

    Nonlinear Oscillations is a self-contained and thorough treatment of the vigorous research that has occurred in nonlinear mechanics since 1970. The book begins with fundamental concepts and techniques of analysis and progresses through recent developments and provides an overview that abstracts and introduces main nonlinear phenomena. It treats systems having a single degree of freedom, introducing basic concepts and analytical methods, and extends concepts and methods to systems having degrees of freedom. Most of this material cannot be found in any other text. Nonlinear Oscillations uses sim

  7. Paneling architectural freeform surfaces

    KAUST Repository

    Eigensatz, Michael

    2010-07-26

    The emergence of large-scale freeform shapes in architecture poses big challenges to the fabrication of such structures. A key problem is the approximation of the design surface by a union of patches, socalled panels, that can be manufactured with a selected technology at reasonable cost, while meeting the design intent and achieving the desired aesthetic quality of panel layout and surface smoothness. The production of curved panels is mostly based on molds. Since the cost of mold fabrication often dominates the panel cost, there is strong incentive to use the same mold for multiple panels. We cast the major practical requirements for architectural surface paneling, including mold reuse, into a global optimization framework that interleaves discrete and continuous optimization steps to minimize production cost while meeting user-specified quality constraints. The search space for optimization is mainly generated through controlled deviation from the design surface and tolerances on positional and normal continuity between neighboring panels. A novel 6-dimensional metric space allows us to quickly compute approximate inter-panel distances, which dramatically improves the performance of the optimization and enables the handling of complex arrangements with thousands of panels. The practical relevance of our system is demonstrated by paneling solutions for real, cutting-edge architectural freeform design projects. © 2010 ACM.

  8. Paneling architectural freeform surfaces

    KAUST Repository

    Eigensatz, Michael

    2010-07-25

    The emergence of large-scale freeform shapes in architecture poses big challenges to the fabrication of such structures. A key problem is the approximation of the design surface by a union of patches, so-called panels, that can be manufactured with a selected technology at reasonable cost, while meeting the design intent and achieving the desired aesthetic quality of panel layout and surface smoothness. The production of curved panels is mostly based on molds. Since the cost of mold fabrication often dominates the panel cost, there is strong incentive to use the same mold for multiple panels. We cast the major practical requirements for architectural surface paneling, including mold reuse, into a global optimization framework that interleaves discrete and continuous optimization steps to minimize production cost while meeting user-specified quality constraints. The search space for optimization is mainly generated through controlled deviation from the design surface and tolerances on positional and normal continuity between neighboring panels. A novel 6-dimensional metric space allows us to quickly compute approximate inter-panel distances, which dramatically improves the performance of the optimization and enables the handling of complex arrangements with thousands of panels. The practical relevance of our system is demonstrated by paneling solutions for real, cutting-edge architectural freeform design projects.

  9. Nonlinear systems

    CERN Document Server

    Palmero, Faustino; Lemos, M; Sánchez-Rey, Bernardo; Casado-Pascual, Jesús

    2018-01-01

    This book presents an overview of the most recent advances in nonlinear science. It provides a unified view of nonlinear properties in many different systems and highlights many  new developments. While volume 1 concentrates on mathematical theory and computational techniques and challenges, which are essential for the study of nonlinear science, this second volume deals with nonlinear excitations in several fields. These excitations can be localized and transport energy and matter in the form of breathers, solitons, kinks or quodons with very different characteristics, which are discussed in the book. They can also transport electric charge, in which case they are known as polarobreathers or solectrons. Nonlinear excitations can influence function and structure in biology, as for example, protein folding. In crystals and other condensed matter, they can modify transport properties, reaction kinetics and interact with defects. There are also engineering applications in electric lattices, Josephson junction a...

  10. Enhanced aeroelastic energy harvesting by exploiting combined nonlinearities: theory and experiment

    International Nuclear Information System (INIS)

    Sousa, V C; De M Anicézio, M; De Marqui Jr, C; Erturk, A

    2011-01-01

    Converting aeroelastic vibrations into electricity for low power generation has received growing attention over the past few years. In addition to potential applications for aerospace structures, the goal is to develop alternative and scalable configurations for wind energy harvesting to use in wireless electronic systems. This paper presents modeling and experiments of aeroelastic energy harvesting using piezoelectric transduction with a focus on exploiting combined nonlinearities. An airfoil with plunge and pitch degrees of freedom (DOF) is investigated. Piezoelectric coupling is introduced to the plunge DOF while nonlinearities are introduced through the pitch DOF. A state-space model is presented and employed for the simulations of the piezoaeroelastic generator. A two-state approximation to Theodorsen aerodynamics is used in order to determine the unsteady aerodynamic loads. Three case studies are presented. First the interaction between piezoelectric power generation and linear aeroelastic behavior of a typical section is investigated for a set of resistive loads. Model predictions are compared to experimental data obtained from the wind tunnel tests at the flutter boundary. In the second case study, free play nonlinearity is added to the pitch DOF and it is shown that nonlinear limit-cycle oscillations can be obtained not only above but also below the linear flutter speed. The experimental results are successfully predicted by the model simulations. Finally, the combination of cubic hardening stiffness and free play nonlinearities is considered in the pitch DOF. The nonlinear piezoaeroelastic response is investigated for different values of the nonlinear-to-linear stiffness ratio. The free play nonlinearity reduces the cut-in speed while the hardening stiffness helps in obtaining persistent oscillations of acceptable amplitude over a wider range of airflow speeds. Such nonlinearities can be introduced to aeroelastic energy harvesters (exploiting

  11. Transonic flutter study of a wind-tunnel model of a supercritical wing with/without winglet. [conducted in Langley Transonic Dynamics Tunnel

    Science.gov (United States)

    Ruhlin, C. L.; Rauch, F. J., Jr.; Waters, C.

    1982-01-01

    The model was a 1/6.5-size, semipan version of a wing proposed for an executive-jet-transport airplane. The model was tested with a normal wingtip, a wingtip with winglet, and a normal wingtip ballasted to simulate the winglet mass properties. Flutter and aerodynamic data were acquired at Mach numbers (M) from 0.6 to 0.95. The measured transonic flutter speed boundary for each wingtip configuration had roughly the same shape with a minimum flutter speed near M=0.82. The winglet addition and wingtip mass ballast decreased the wing flutter speed by about 7 and 5 percent, respectively; thus, the winglet effect on flutter was more a mass effect than an aerodynamic effect.

  12. REINFORCED COMPOSITE PANEL

    DEFF Research Database (Denmark)

    2003-01-01

    A composite panel having front and back faces, the panel comprising facing reinforcement, backing reinforcement and matrix material binding to the facing and backing reinforcements, the facing and backing reinforcements each independently comprising one or more reinforcing sheets, the facing rein...... by matrix material, the facing and backing reinforcements being interconnected to resist out-of-plane relative movement. The reinforced composite panel is useful as a barrier element for shielding structures, equipment and personnel from blast and/or ballistic impact damage....

  13. Evaluation of Thin Kevlar-Epoxy Fabric Panels Subjected to Shear Loading

    Science.gov (United States)

    Baker, Donald J.

    1996-01-01

    The results of an analytical and experimental investigation of 4-ply Kevlar-49-epoxy panels loaded by in-plane shear are presented. Approximately one-half of the panels are thin-core sandwich panels and the other panels are solid-laminate panels. Selected panels were impacted with an aluminum sphere at a velocity of either 150 or 220 ft/sec. The strength of panels impacted at 150 ft/sec was not reduced when compared to the strength of the undamaged panels, but the strength of panels impacted at 220 ft/sec was reduced by 27 to 40 percent. Results are presented for panels that were cyclically loaded from a load less than the buckling load to a load in the postbuckling load range. The thin-core sandwich panels had a lower fatigue life than the solid panels. The residual strength of the solid and sandwich panels cycled more than one million cycles exceeded the baseline undamaged panel strengths. The effect of hysteresis in the response of the sandwich panels is not significant. Results of a nonlinear finite element analysis conducted for each panel design are presented.

  14. Solar reflection panels

    Science.gov (United States)

    Diver, Jr., Richard B.; Grossman, James W [Albuquerque, NM; Reshetnik, Michael [Boulder, CO

    2006-07-18

    A solar collector comprising a glass mirror, and a composite panel, wherein the back of the mirror is affixed to a front surface of the composite panel. The composite panel comprises a front sheet affixed to a surface of a core material, preferably a core material comprising a honeycomb structure, and a back sheet affixed to an opposite surface of the core material. The invention may further comprise a sealing strip, preferably comprising EPDM, positioned between the glass mirror and the front surface of the composite panel. The invention also is of methods of making such solar collectors.

  15. Optimization of structures to satisfy a flutter velocity constraint by use of quadratic equation fitting. M.S. Thesis

    Science.gov (United States)

    Motiwalla, S. K.

    1973-01-01

    Using the first and the second derivative of flutter velocity with respect to the parameters, the velocity hypersurface is made quadratic. This greatly simplifies the numerical procedure developed for determining the values of the design parameters such that a specified flutter velocity constraint is satisfied and the total structural mass is near a relative minimum. A search procedure is presented utilizing two gradient search methods and a gradient projection method. The procedure is applied to the design of a box beam, using finite-element representation. The results indicate that the procedure developed yields substantial design improvement satisfying the specified constraint and does converge to near a local optimum.

  16. Nonlinear optics

    CERN Document Server

    Boyd, Robert W

    2013-01-01

    Nonlinear Optics is an advanced textbook for courses dealing with nonlinear optics, quantum electronics, laser physics, contemporary and quantum optics, and electrooptics. Its pedagogical emphasis is on fundamentals rather than particular, transitory applications. As a result, this textbook will have lasting appeal to a wide audience of electrical engineering, physics, and optics students, as well as those in related fields such as materials science and chemistry.Key Features* The origin of optical nonlinearities, including dependence on the polarization of light* A detailed treatment of the q

  17. Flutter and galloping of cable-supported bridges with porous wind barriers

    Czech Academy of Sciences Publication Activity Database

    Buljac, A.; Kozmar, H.; Pospíšil, S.; Macháček, Michael

    2017-01-01

    Roč. 171, December (2017), s. 304-318 ISSN 0167-6105 R&D Projects: GA ČR(CZ) GA15-01035S; GA MŠk(CZ) LO1219 Keywords : cable-supported bridges * porous wind barriers * aerodynamic forces and moments * flutter * galloping * wind-tunnel experiments Subject RIV: JM - Building Engineering OBOR OECD: Construction engineering , Municipal and structural engineering Impact factor: 2.049, year: 2016 http://www.sciencedirect.com/science/ article /pii/S016761051730435X

  18. Stochastic Nonlinear Aeroelasticity

    Science.gov (United States)

    2009-01-01

    ORGANIZATION NAME(S) AND ADDRESS(ES) 8. PERFORMING ORGANIZATION Design and Analysis Methods Branch (AFRL/RBSD) Structures Division, Air Force... coff U∞ cs ea lw cw Figure 6: Wing and store geometry (left), wing box structural model (middle), flutter distribution (right

  19. Stressed skin panels

    Energy Technology Data Exchange (ETDEWEB)

    Anon

    2001-07-01

    Advantages and disadvantages of stressed skin panels, also known as structural insulated panels (SIPs), are discussed as material and labour-saving alternatives to traditional stick framing. Stressed skin panels are manufactured 'sandwich' assemblies with a rigid insulating polystyrene foam core, whose interior and exterior surfaces are bonded into panels. The skins distribute and carry the structural loading while the bonded foam core provides insulation and keeps the two skins aligned. Since there are fewer framing members, there is little thermal bridging and the R-value remains high. SIPs are usually manufactured in four feet by eight feet panels, although some manufacturers can produce panels up to eight feet by forty feet. SIPs are resource efficient as they use less wood than conventional framing (about 25 per cent less); can structurally cover large spans, requiring less supplementary framing. Use of SIPs eliminate the need for headers over small openings; provide the ability to nail anywhere; create less scrap and waste; lessen vulnerability to unfavourable weather and other job-site hazards, can reduce delays, and often can produce significant savings in material and labour costs. Limitations include the more complex approaches to plumbing and electrical systems, although this can be minimized by designers by incorporating much of the plumbing and electrical work on interior (non-panel) walls. Most stressed skin panels require one-half inch interior gypsum drywall. If become wet, stressed skin panels take a long time to dry out and may harbour mold growth. Larger stressed-skin panels used in floors and roofs, may require cranes or other machinery for handling because of their weight. Although not without some environmental impact, overall, stressed skin panels are judged to be a resource-efficient building technology with significant energy-efficiency benefits and distinct advantages over stick framing. 3 photos.

  20. Nonlinear systems

    National Research Council Canada - National Science Library

    Drazin, P. G

    1992-01-01

    This book is an introduction to the theories of bifurcation and chaos. It treats the solution of nonlinear equations, especially difference and ordinary differential equations, as a parameter varies...

  1. Nonlinear analysis

    CERN Document Server

    Gasinski, Leszek

    2005-01-01

    Hausdorff Measures and Capacity. Lebesgue-Bochner and Sobolev Spaces. Nonlinear Operators and Young Measures. Smooth and Nonsmooth Analysis and Variational Principles. Critical Point Theory. Eigenvalue Problems and Maximum Principles. Fixed Point Theory.

  2. Recent advance in nonlinear aeroelastic analysis and control of the aircraft

    Directory of Open Access Journals (Sweden)

    Xiang Jinwu

    2014-02-01

    Full Text Available A review on the recent advance in nonlinear aeroelasticity of the aircraft is presented in this paper. The nonlinear aeroelastic problems are divided into three types based on different research objects, namely the two dimensional airfoil, the wing, and the full aircraft. Different nonlinearities encountered in aeroelastic systems are discussed firstly, where the emphases is placed on new nonlinear model to describe tested nonlinear relationship. Research techniques, especially new theoretical methods and aeroelastic flutter control methods are investigated in detail. The route to chaos and the cause of chaotic motion of two-dimensional aeroelastic system are summarized. Various structural modeling methods for the high-aspect-ratio wing with geometric nonlinearity are discussed. Accordingly, aerodynamic modeling approaches have been developed for the aeroelastic modeling of nonlinear high-aspect-ratio wings. Nonlinear aeroelasticity about high-altitude long-endurance (HALE and fight aircrafts are studied separately. Finally, conclusions and the challenges of the development in nonlinear aeroelasticity are concluded. Nonlinear aeroelastic problems of morphing wing, energy harvesting, and flapping aircrafts are proposed as new directions in the future.

  3. Solar panel foundation device

    Energy Technology Data Exchange (ETDEWEB)

    Hawley, W.W.

    1983-03-29

    A transportable solar panel foundation device which has a bottom member, at least one upstanding side member, and an essentially open top. The side members are angled to permit nesting of a plurality of the foundation devices, and reinforcement pads are carried by the foundation device to support legs for one or more solar panels.

  4. Panel 5: Microbiology and Immunology Panel

    Science.gov (United States)

    Murphy, Timothy F.; Chonmaitree, Tasnee; Barenkamp, Stephen; Kyd, Jennelle; Nokso-Koivisto, Johanna; Patel, Janak A.; Heikkinen, Terho; Yamanaka, Noboru; Ogra, Pearay; Swords, W. Edward; Sih, Tania; Pettigrew, Melinda M.

    2014-01-01

    Objective The objective is to perform a comprehensive review of the literature from January 2007 through June 2011 on the virology, bacteriology, and immunology related to otitis media. Data Sources PubMed database of the National Library of Medicine. Review Methods Three subpanels with co-chairs comprising experts in the virology, bacteriology, and immunology of otitis media were formed. Each of the panels reviewed the literature in their respective fields and wrote draft reviews. The reviews were shared with all panel members, and a second draft was created. The entire panel met at the 10th International Symposium on Recent Advances in Otitis Media in June 2011 and discussed the review and refined the content further. A final draft was created, circulated, and approved by the panel. Conclusion Excellent progress has been made in the past 4 years in advancing an understanding of the microbiology and immunology of otitis media. Advances include laboratory-based basic studies, cell-based assays, work in animal models, and clinical studies. Implications for Practice The advances of the past 4 years formed the basis of a series of short-term and long-term research goals in an effort to guide the field. Accomplishing these goals will provide opportunities for the development of novel interventions, including new ways to better treat and prevent otitis media. PMID:23536533

  5. RECIPANEL: RECYCLED PAPER PANELS

    Directory of Open Access Journals (Sweden)

    HERNÁN CAÑOLA

    2012-01-01

    Full Text Available En este artículo se estudia la fabricación y el comportamiento mecánico de paneles a base de papel reciclado. El objetivo principal del proyecto es producir un prototipo de panel que emplee elementos provenientes de residuos sólidos (papel periódico y de un material conglomerante (cemento Portland blanco. El panel debe ser económico, debe tener buenas propiedades mecánicas y debe tener dimensiones comerciales para su uso en muros tabiques y en cielos falsos en la industria de la construcción. El Recipanel es un panel no estructural a base de papel reciclado. El Recipanel cumple las normas colombianas en lo relativo a los paneles de uso no estructural y presenta además unas excelentes características mecánicas.

  6. Puncture panel optimization

    International Nuclear Information System (INIS)

    Glass, R.E.; Longenbaugh, R.S.

    1986-01-01

    Sandia National Laboratories developed the TRansUranic PACkage Transporter (TRUPACT) to transport defense contact-handled transuranic wastes. The package has been designed to meet the normal and hypothetical accident conditions in 10CFR71 which includes the demonstrated ability to survive a 1-meter drop onto a mild steel pin. The puncture protection is provided by puncture resistant panels. In conjunction with the development of TRUPACT, a series of experiments has been conducted to reduce the weight of the puncture resistant panels. The initial scoping tests resulted in a preliminary design incorporating 30 layers of Kevlar. This design has been shown to meet the regulatory puncture test. To reduce the weight of this panel, subscale tests were conducted on panels utilizing Kevlar yarns with varying mass per unit length (denier) as well as different resins. This paper reviews the testing undertaken in the original panel development and discusses the results obtained from the recent subscale and full-scale optimization tests

  7. Solar panel cleaning robot

    Science.gov (United States)

    Nalladhimmu, Pavan Kumar Reddy; Priyadarshini, S.

    2018-04-01

    As the demand of electricity is increasing, there is need to using the renewable sources to produce the energy at present of power shortage, the use of solar energy could be beneficial to great extent and easy to get the maximum efficiency. There is an urgent in improving the efficiency of solar power generation. Current solar panels setups take a major power loss when unwanted obstructions cover the surface of the panels. To make solar energy more efficiency of solar array systems must be maximized efficiency evaluation of PV panels, that has been discussed with particular attention to the presence of dust on the efficiency of the PV panels have been highlighted. This paper gives the how the solar panel cleaning system works and designing of the cleaning system.

  8. Rotor Design Options for Improving XV-15 Whirl-Flutter Stability Margins

    Science.gov (United States)

    Acree, C. W., Jr.; Peyran, R. J.; Johnson, Wayne

    2004-01-01

    Rotor design changes intended to improve tiltrotor whirl-flutter stability margins were analyzed. A baseline analytical model of the XV-15 was established, and then a thinner, composite wing was designed to be representative of a high-speed tiltrotor. The rotor blade design was modified to increase the stability speed margin for the thin-wing design. Small rearward offsets of the aerodynamic-center locus with respect to the blade elastic axis created large increases in the stability boundary. The effect was strongest for offsets at the outboard part of the blade, where an offset of the aerodynamic center by 10% of tip chord improved the stability margin by over 100 knots. Forward offsets of the blade center of gravity had similar but less pronounced effects. Equivalent results were seen for swept-tip blades. Appropriate combinations of sweep and pitch stiffness completely eliminated whirl flutter within the speed range examined; alternatively, they allowed large increases in pitch-flap coupling (delta-three) for a given stability margin. A limited investigation of the rotor loads in helicopter and airplane configuration showed only minor increases in loads.

  9. Malfunction of a Heimlich flutter valve causing tension pneumothorax: case report of a rare complication

    Directory of Open Access Journals (Sweden)

    Braunstein Volker A

    2010-06-01

    Full Text Available Abstract Background Thoracic injuries play an important role in major trauma patients due to their high incidence and critical relevance. A serious consequence of thoracic trauma is pneumothorax, a condition that quickly can become life-threatening and requires immediate treatment. Decompression is the state of the art for treating tension pneumothorax. There are many different methods of decompression using different techniques, devices, valves and drainage systems. Referring to our case report we would like to discuss the utilization of these devices. Case presentation We report of a patient suffering from tension pneumothorax despite insertion of a chest drain at the accident scene. The decompression was by tube thoracostomy which was connected to a Heimlich flutter valve. During air transportation the patient suffered from cardiorespiratory arrest with asystole and was admitted to the trauma room undergoing manual chest compressions. The initial chest film showed a persisting tension pneumothorax, despite the chest tube that had been correctly placed and connected properly to the Heimlich valve. We assume that the Heimlich valve leaves did not open up and thus tension pneumothorax was not released. Conclusion We would like to raise awareness to the fact that if a Heimlich flutter valve is applied in the pre-hospital setting it should be used with caution. Failure in this type of valve may lead to recurrent tension pneumothorax.

  10. Risk of pacemaker implantation after uneventful successful cavotricuspid isthmus radiofrequency ablation in patients with common atrial flutter.

    Science.gov (United States)

    Rodríguez-Mañero, Moisés; González-Melchor, Layla; Ballesteros, Gabriel; Raposeiras-Roubín, Sergio; García-Seara, Javier; López, Xesús Alberte Fernández; Cambeiro, Cristina González; Alcalde, Oscar; García-Bolao, Ignacio; Martínez-Sande, Luis; González-Juanatey, José Ramón

    2016-01-01

    Little is known about the risk of pacemaker implantation after common atrial flutter ablation in the long-term. We retrospectively reviewed the electrophysiology laboratory database at two Spanish University Hospitals from 1998 to 2012 to identify patients who had undergone successful ablation for cavotricuspid dependent atrial flutter. Cox regression analysis was used to examine the risk of pacemaker implantation. A total of 298 patients were considered eligible for inclusion. The mean age of the enrolled patients was 65.7±11. During 57.7±42.8 months, 30 patients (10.1%) underwent pacemaker implantation. In the stepwise multivariate models only heart rate at the time of the ablation (OR: 0.96; 95% CI: 0.93-0.98; ppacemaker implantation. A heart rate of ≤65 bpm was identified as the optimal cut-off value to predict the need of pacemaker implantation in the follow-up (sensitivity: 79%, specificity: 74%) by ROC curve analyses. This is the first study of an association between the slow conducting common atrial flutter and subsequent risk of pacemaker implantation. In light of these findings, assessing it prior to ablation can be helpful for the risk stratification of sinus node disease or atrioventricular conduction disease requiring a pacemaker implantation in patients with persistent atrial flutter. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  11. Make Your Own Solar Panel.

    Science.gov (United States)

    Suzuki, David

    1992-01-01

    Presents an activity in which students make a simulated solar panel to learn about the principles behind energy production using solar panels. Provides information about how solar panels function to produce energy. (MCO)

  12. Nonlinear optimization

    CERN Document Server

    Ruszczynski, Andrzej

    2011-01-01

    Optimization is one of the most important areas of modern applied mathematics, with applications in fields from engineering and economics to finance, statistics, management science, and medicine. While many books have addressed its various aspects, Nonlinear Optimization is the first comprehensive treatment that will allow graduate students and researchers to understand its modern ideas, principles, and methods within a reasonable time, but without sacrificing mathematical precision. Andrzej Ruszczynski, a leading expert in the optimization of nonlinear stochastic systems, integrates the theory and the methods of nonlinear optimization in a unified, clear, and mathematically rigorous fashion, with detailed and easy-to-follow proofs illustrated by numerous examples and figures. The book covers convex analysis, the theory of optimality conditions, duality theory, and numerical methods for solving unconstrained and constrained optimization problems. It addresses not only classical material but also modern top...

  13. Blue Ribbon Panel Report

    Science.gov (United States)

    An NCI Cancer Currents blog by the NCI acting director thanking the cancer community for contributing to the Cancer Moonshot Blue Ribbon Panel report, which was presented to the National Cancer Advisory Board on September 7.

  14. Panel acoustic contribution analysis.

    Science.gov (United States)

    Wu, Sean F; Natarajan, Logesh Kumar

    2013-02-01

    Formulations are derived to analyze the relative panel acoustic contributions of a vibrating structure. The essence of this analysis is to correlate the acoustic power flow from each panel to the radiated acoustic pressure at any field point. The acoustic power is obtained by integrating the normal component of the surface acoustic intensity, which is the product of the surface acoustic pressure and normal surface velocity reconstructed by using the Helmholtz equation least squares based nearfield acoustical holography, over each panel. The significance of this methodology is that it enables one to analyze and rank relative acoustic contributions of individual panels of a complex vibrating structure to acoustic radiation anywhere in the field based on a single set of the acoustic pressures measured in the near field. Moreover, this approach is valid for both interior and exterior regions. Examples of using this method to analyze and rank the relative acoustic contributions of a scaled vehicle cabin are demonstrated.

  15. Autoimmune liver disease panel

    Science.gov (United States)

    Liver disease test panel - autoimmune ... Autoimmune disorders are a possible cause of liver disease. The most common of these diseases are autoimmune hepatitis and primary biliary cholangitis (formerly called primary biliary cirrhosis). This group of tests ...

  16. Hexagon solar power panel

    Science.gov (United States)

    Rubin, I. (Inventor)

    1978-01-01

    A solar energy panel support is described upon which silicon cells are arrayed. The cells are wafer thin and of two geometrical types, both of the same area and electrical rating, namely hexagon cells and hourglass cells. The hourglass cells are composites of half hexagons. A near perfect nesting relationship of the cells achieves a high density packing whereby optimum energy production per panel area is achieved.

  17. Propulsion Systems Panel deliberations

    Science.gov (United States)

    Bianca, Carmelo J.; Miner, Robert; Johnston, Lawrence M.; Bruce, R.; Dennies, Daniel P.; Dickenson, W.; Dreshfield, Robert; Karakulko, Walt; Mcgaw, Mike; Munafo, Paul M.

    1993-01-01

    The Propulsion Systems Panel was established because of the specialized nature of many of the materials and structures technology issues related to propulsion systems. This panel was co-chaired by Carmelo Bianca, MSFC, and Bob Miner, LeRC. Because of the diverse range of missions anticipated for the Space Transportation program, three distinct propulsion system types were identified in the workshop planning process: liquid propulsion systems, solid propulsion systems and nuclear electric/nuclear thermal propulsion systems.

  18. Honeycomb metal panel

    International Nuclear Information System (INIS)

    1979-01-01

    Product constituted by a honeycomb metal panel that can be employed to advantage for manufacturing lagging by sandwiching it between two plane sheets, utilized in particular in the nuclear industry where lagging has to have a very long life strength. The honeycomb metal panel is made of an expanded metal extrusion previously cut so as to form, after additional drawing, a honeycomb structure with square or rectangular cells with a plane surface [fr

  19. Nonlinear free vibration of single walled Carbone NanoTubes conveying fluid

    Directory of Open Access Journals (Sweden)

    Azrar A.

    2014-04-01

    Full Text Available Nonlinear free vibration of single-walled carbon nanotubes (CNTs conveying fluid are modeled and numerically simulated based on von Kármán geometric nonlinearity and Eringen’s nonlocal elasticity theory. The CNTs are modelled as nanobeams where the effects of transverse shear deformation and rotary inertia are considered within the framework of Timoshenko beam theory. The governing equations and boundary conditions are derived using the Hamilton’s principle and the nonlinear equation of motion is solved by the Galerkin’s method. The small scale parameter and the fluid-tube interaction effects on the dynamic behaviours of the CNT-fluid system as well as the instabilities induced by the fluid-velocity can be investigated. The critical fluid-velocity and frequency-amplitude relationships as well as the flutter and divergence instability types and the associated time responses are obtained based on the presented methodological approach.

  20. Option Panels in Pure-Jump Settings

    DEFF Research Database (Denmark)

    Andersen, Torben Gustav; Fusari, Nicola; Todorov, Viktor

    We develop parametric inference procedures for large panels of noisy option data in the setting where the underlying process is of pure-jump type, i.e., evolve only through a sequence of jumps. The panel consists of options written on the underlying asset with a (different) set of strikes...... specification for the risk-neutral asset return dynamics, the option prices are nonlinear functions of a time-invariant parameter vector and a time-varying latent state vector (or factors). Furthermore, no-arbitrage restrictions impose a direct link between some of the quantities that may be identified from...... the return and option data. These include the so-called jump activity index as well as the time-varying jump intensity. We propose penalized least squares estimation in which we minimize L_2 distance between observed and model-implied options and further penalize for the deviation of model-implied quantities...

  1. TYPES OF RADIOFREQUENCY ABLATION AND CLINICAL SYMPTOMS IN PATIENTS WITH ATRIAL FIBRILLATION AND FLUTTER

    Directory of Open Access Journals (Sweden)

    Zolotarova T. V.

    2017-12-01

    Full Text Available The study involved 76 patients with atrial fibrillation and atrial flutter (AF/AFL who were divided into groups depending on conducted surgery (radiofrequency ablation of pulmonary veins (RFA PV, cavo-tricuspid isthmus (CTI, a combined strategy (PV + CTI. We evaluated the sex and age of patients, AF and AFL form, duration of AF/AFL, classification of AF / AFL by the different scales, stage and degree of hypertension (AT; types of coronary heart disease (CHD; diabetes mellitus type 2; acute cerebrovascular accident history; functional class and stage of chronic heart failure (FC CHF. The frequency distribution of basic cardiovascular diseases and their clinical signs are observed equally in patients with AF/AFL, regardless of the type of surgery carried out and they do not influence the choice of the latter. Male patients often held RFA CTI and women – RFA PV. Patients with persistent AF often require alternative treatments, especially catheter ablation of arrhythmic substrate.

  2. The effects of rhythm control strategies versus rate control strategies for atrial fibrillation and atrial flutter

    DEFF Research Database (Denmark)

    Sethi, Naqash; Safi, Sanam; Nielsen, Emil E

    2017-01-01

    by Jakobsen and colleagues. We plan to include all relevant randomised clinical trials assessing the effects of any rhythm control strategy versus any rate control strategy. We plan to search the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, LILACS, Science Citation Index Expanded...... on Web of Science, and BIOSIS to identify relevant trials. Any eligible trial will be assessed and classified as either high risk of bias or low risk of bias, and our conclusions will be based on trials with low risk of bias. The analyses of the extracted data will be performed using Review Manager 5....... This protocol for a systematic review aims at identifying the best overall treatment strategy for atrial fibrillation and atrial flutter. METHODS: This protocol for a systematic review was performed following the recommendations of the Cochrane Collaboration and the eight-step assessment procedure suggested...

  3. Parallel numerical simulation of oscillating airfoil NACA0015 in the channel due to flutter instability

    Directory of Open Access Journals (Sweden)

    Řidký Václav

    2014-03-01

    Full Text Available The work is devoted to 3D and 2D parallel numerical computation of pressure and velocity fields around an elastically supported airfoil self-oscillating due to interaction with the airflow. Numerical solution is computed in the OpenFOAM package, an open-source software package based on finite volume method. Movement of airfoil is described by translation and rotation, identified from experimental data. A new boundary condition for the 2DOF motion of the airfoil was implemented. The results of numerical simulations (velocity are compared with data measured in a wind tunnel, where a physical model of NACA0015 airfoil was mounted and tuned to exhibit the flutter instability. The experimental results were obtained previously in the Institute of Thermomechanics by interferographic measurements in a subsonic wind tunnel in Nový Knín.

  4. Sustained Spatial Attention to Vibrotactile Stimulation in the Flutter Range: Relevant Brain Regions and Their Interaction

    Science.gov (United States)

    Goltz, Dominique; Pleger, Burkhard; Thiel, Sabrina; Villringer, Arno; Müller, Matthias M.

    2013-01-01

    The present functional magnetic resonance imaging (fMRI) study was designed to get a better understanding of the brain regions involved in sustained spatial attention to tactile events and to ascertain to what extent their activation was correlated. We presented continuous 20 Hz vibrotactile stimuli (range of flutter) concurrently to the left and right index fingers of healthy human volunteers. An arrow cue instructed subjects in a trial-by-trial fashion to attend to the left or right index finger and to detect rare target events that were embedded in the vibrotactile stimulation streams. We found blood oxygen level-dependent (BOLD) attentional modulation in primary somatosensory cortex (SI), mainly covering Brodmann area 1, 2, and 3b, as well as in secondary somatosensory cortex (SII), contralateral to the to-be-attended hand. Furthermore, attention to the right (dominant) hand resulted in additional BOLD modulation in left posterior insula. All of the effects were caused by an increased activation when attention was paid to the contralateral hand, except for the effects in left SI and insula. In left SI, the effect was related to a mixture of both a slight increase in activation when attention was paid to the contralateral hand as well as a slight decrease in activation when attention was paid to the ipsilateral hand (i.e., the tactile distraction condition). In contrast, the effect in left posterior insula was exclusively driven by a relative decrease in activation in the tactile distraction condition, which points to an active inhibition when tactile information is irrelevant. Finally, correlation analyses indicate a linear relationship between attention effects in intrahemispheric somatosensory cortices, since attentional modulation in SI and SII were interrelated within one hemisphere but not across hemispheres. All in all, our results provide a basis for future research on sustained attention to continuous vibrotactile stimulation in the range of flutter

  5. Reflecting variable opening insulating panel

    International Nuclear Information System (INIS)

    Nungesser, W.T.

    1976-01-01

    A description is given of a reflecting variable opening insulating panel assembly, comprising a static panel assembly of reflecting insulation sheets forming a cavity along one side of the panel and a movable panel opening out by sliding from the cavity of the static panel, and a locking device for holding the movable panel in a position extending from the cavity of the static panel. This can apply to a nuclear reactor of which the base might require maintenance and periodical checking and for which it is desirable to have available certain processes for the partial dismantling of the insulation [fr

  6. Effects of atrial fibrillation/atrial flutter on the short and medium-term prognosis of patients with acute myocardial infarction

    International Nuclear Information System (INIS)

    Cui Kejian; Gu Shuiming; Ding Yueyou; Zheng Hongchao; Zhang Yachen; Li Yigang

    2008-01-01

    Objective: To evaluate the influnce of atrial fibrillation(AF)/atrial flutter on the mortality and prognosis of patients with AMI. Methods: A total of 297 consecutive patients were studied from Jan. 2001 to Dec. 2005 and were categorized into 2 groups according to the presence or absence of AF/atrial flutter. The 30 d and 6 mo mortalities, Killip Grades, cardiogenic shock, arrhythmia and left ventricular ejectory functional (LVEF) 6 months after AMI with Doppler US between the 2 groups were compared. Results: The incidence of AF/atrial fluttler was 12.5% with older age, higher Killip Gorade, higher CPK peak, higher rates of previous myocardial infarction and multivascular involvement than those without AF/ atrial flutter. The short and medium-term mortalities in AF/atriat flutter group were both significantly higher than those of non-AF/atrial flutter group (P<0.05). Conclusions: The short and medium-term mortalities increase obviously in AMI complicated with AF/atrial flutter, probably related to the severity of atherosclerosis. (authors)

  7. Basic research on nonlinear instability phenomena of liquid surface. Fiscal year 1996 report on preceding basic engineering field

    International Nuclear Information System (INIS)

    Madarame, Haruki; Okamoto, Koji; Iida, Masao

    1997-03-01

    Various nonlinear behaviors caused by nonlinear boundary conditions have been observed, and it is feared that in large vessels like FBRs, the instability phenomena such as self-exciting sloshing may occur in the free liquid surface of coolant. In this research, the nonlinear instability phenomena in free liquid surface were examined by the basic experiment and the analysis. As to the self-exciting oscillation 'jet flutter' of upward plane jet that collides against liquid surface, in order to know the mechanism of determining the frequency and supplying energy, the amplitude and phase relation of various variable quantities were investigated. The simplified model for calculating the displacement of jet was made, and compared with the experiment. The jet flutter phenomena are explained. The interaction of free liquid surface and turbulent flow, which is important for considering the nonlinearity in free liquid surface, was measured by LDV and visualization, and the turbulent flow phenomena in free liquid surface were investigated. In the experiment, turbulent flow energy was given to the free liquid surfaces of water and polymers, and the effect that the Toms effect exerted to interface turbulent flow was observed. The results of these studies are reported. (K.I.) studies are reported. (K.I.)

  8. Panels of microporous insulation

    Energy Technology Data Exchange (ETDEWEB)

    McWilliams, J.A.; Morgan, D.E.; Jackson, J.D.J.

    1990-08-07

    Microporous thermal insulation materials have a lattice structure in which the average interstitial dimension is less than the mean free path of the molecules of air or other gas in which the material is arranged. This results in a heat flow which is less than that attributable to the molecular heat diffusion of the gas. According to this invention, a method is provided for manufacturing panels of microporous thermal insulation, in particular such panels in which the insulation material is bonded to a substrate. The method comprises the steps of applying a film of polyvinyl acetate emulsion to a non-porous substrate, and compacting powdery microporous thermal insulation material against the film so as to cause the consolidated insulation material to bond to the substrate and form a panel. The polyvinyl acetate may be applied by brushing or spraying, and is preferably allowed to dry prior to compacting the insulation material. 1 fig.

  9. Advanced solar panel designs

    Science.gov (United States)

    Ralph, E. L.; Linder, E.

    1995-01-01

    This paper describes solar cell panel designs that utilize new hgih efficiency solar cells along with lightweight rigid panel technology. The resulting designs push the W/kg and W/sq m parameters to new high levels. These new designs are well suited to meet the demand for higher performance small satellites. This paper reports on progress made on two SBIR Phase 1 contracts. One panel design involved the use of large area (5.5 cm x 6.5 cm) GaAs/Ge solar cells of 19% efficiency combined with a lightweight rigid graphite fiber epoxy isogrid substrate configuration. A coupon (38 cm x 38 cm) was fabricated and tested which demonstrated an array specific power level of 60 W/kg with a potential of reaching 80 W/kg. The second panel design involved the use of newly developed high efficiency (22%) dual junction GaInP2/GaAs/Ge solar cells combined with an advanced lightweight rigid substrate using aluminum honeycomb core with high strength graphite fiber mesh facesheets. A coupon (38 cm x 38 cm) was fabricated and tested which demonstrated an array specific power of 105 W/kg and 230 W/sq m. This paper will address the construction details of the panels and an a analysis of the component weights. A strawman array design suitable for a typical small-sat mission is described for each of the two panel design technologies being studied. Benefits in respect to weight reduction, area reduction, and system cost reduction are analyzed and compared to conventional arrays.

  10. Evaluation of the constant pressure panel method (CPM) for unsteady air loads prediction

    Science.gov (United States)

    Appa, Kari; Smith, Michael J. C.

    1988-01-01

    This paper evaluates the capability of the constant pressure panel method (CPM) code to predict unsteady aerodynamic pressures, lift and moment distributions, and generalized forces for general wing-body configurations in supersonic flow. Stability derivatives are computed and correlated for the X-29 and an Oblique Wing Research Aircraft, and a flutter analysis is carried out for a wing wind tunnel test example. Most results are shown to correlate well with test or published data. Although the emphasis of this paper is on evaluation, an improvement in the CPM code's handling of intersecting lifting surfaces is briefly discussed. An attractive feature of the CPM code is that it shares the basic data requirements and computational arrangements of the doublet lattice method. A unified code to predict unsteady subsonic or supersonic airloads is therefore possible.

  11. Panel 3 - characterization

    Energy Technology Data Exchange (ETDEWEB)

    Erck, R.A.; Erdemir, A.; Janghsing Hsieh; Lee, R.H.; Xian Zheng Pan; Deming Shu [Argonne National Lab., IL (United States); Feldman, A. [National Inst. of Standards and Technology, Gaithersburg, MD (United States); Glass, J.T. [North Carolina State Univ., Raleigh (United States); Kleimer, R. [Coors Ceramics Co., Golden, CO (United States); Lawton, E.A. [JPL/Caltech, Pasadena, CA (United States); McHargue, C.J. [Univ. of Tennessee, Knoxville (United States)

    1993-01-01

    The task of this panel was to identify and prioritize needs in the area of characterization of diamond and diamond-like-carbon (DLC) films for use in the transportation industry. Until recent advances in production of inexpensive films of diamonds and DLC, it was not feasible that these materials could be mass produced. The Characterization Panel is restricting itself to identifying needs in areas that would be most useful to manufacturers and users in producing and utilizing diamond and DLC coatings in industry. These characterization needs include in-situ monitoring during growth, relation of structure to performance, and standards and definitions.

  12. Analysis of Panel Data

    Science.gov (United States)

    Hsiao, Cheng

    2003-02-01

    Panel data models have become increasingly popular among applied researchers due to their heightened capacity for capturing the complexity of human behavior, as compared to cross-sectional or time series data models. This second edition represents a substantial revision of the highly successful first edition (1986). Recent advances in panel data research are presented in an accessible manner and are carefully integrated with the older material. The thorough discussion of theory and the judicious use of empirical examples make this book useful to graduate students and advanced researchers in economics, business, sociology and political science.

  13. Airplane wing deformation and flight flutter detection method by using three-dimensional speckle image correlation technology.

    Science.gov (United States)

    Wu, Jun; Yu, Zhijing; Wang, Tao; Zhuge, Jingchang; Ji, Yue; Xue, Bin

    2017-06-01

    Airplane wing deformation is an important element of aerodynamic characteristics, structure design, and fatigue analysis for aircraft manufacturing, as well as a main test content of certification regarding flutter for airplanes. This paper presents a novel real-time detection method for wing deformation and flight flutter detection by using three-dimensional speckle image correlation technology. Speckle patterns whose positions are determined through the vibration characteristic of the aircraft are coated on the wing; then the speckle patterns are imaged by CCD cameras which are mounted inside the aircraft cabin. In order to reduce the computation, a matching technique based on Geodetic Systems Incorporated coded points combined with the classical epipolar constraint is proposed, and a displacement vector map for the aircraft wing can be obtained through comparing the coordinates of speckle points before and after deformation. Finally, verification experiments containing static and dynamic tests by using an aircraft wing model demonstrate the accuracy and effectiveness of the proposed method.

  14. Nonlinear Elliptic Differential Equations with Multivalued Nonlinearities

    Indian Academy of Sciences (India)

    In this paper we study nonlinear elliptic boundary value problems with monotone and nonmonotone multivalued nonlinearities. First we consider the case of monotone nonlinearities. In the first result we assume that the multivalued nonlinearity is defined on all R R . Assuming the existence of an upper and of a lower ...

  15. Oral bisphosphonates and risk of atrial fibrillation and flutter in women: a self-controlled case-series safety analysis.

    Directory of Open Access Journals (Sweden)

    Anthony Grosso

    Full Text Available A recent trial unexpectedly reported that atrial fibrillation, when defined as serious, occurred more often in participants randomized to an annual infusion of the relatively new parenteral bisphosphonate, zoledronic acid, than among those given placebo, but had limited power. Two subsequent population-based case-control studies of patients receiving a more established oral bisphosphonate, alendronic acid, reported conflicting results, possibly due to uncontrolled confounding factors.We used the United Kingdom General Practice Research Database to assess the risk of atrial fibrillation and flutter in women exposed to the oral bisphosphonates, alendronic acid and risedronate sodium. The self-controlled case-series method was used to minimise the potential for confounding. The age-adjusted incidence rate ratio for atrial fibrillation or flutter in individuals during their exposure to these oral bisphosphonates (n = 2195 was 1.07 (95% CI 0.94-1.21. The age-adjusted incidence rate ratio for alendronic acid (n = 1489 and risedronate sodium (n = 649 exposed individuals were 1.09 (95% CI 0.93-1.26 and 0.99 (95% CI 0.78-1.26 respectively. In post-hoc analyses, an increased risk of incident atrial fibrillation or flutter was detected for patients during their first few months of alendronic acid therapy.We found no robust evidence of an overall long-term increased risk of atrial fibrillation or flutter associated with continued exposure to the oral bisphosphonates, alendronic acid and risedronate sodium. A possible signal for an increase in risk during the first few months of therapy with alendronic acid needs to be re-assessed in additional studies.

  16. In-Flight Aeroelastic Stability of the Thermal Protection System on the NASA HIAD, Part II: Nonlinear Theory and Extended Aerodynamics

    Science.gov (United States)

    Goldman, Benjamin D.; Dowell, Earl H.; Scott, Robert C.

    2015-01-01

    Conical shell theory and a supersonic potential flow aerodynamic theory are used to study the nonlinear pressure buckling and aeroelastic limit cycle behavior of the thermal protection system for NASA's Hypersonic Inflatable Aerodynamic Decelerator. The structural model of the thermal protection system consists of an orthotropic conical shell of the Donnell type, resting on several circumferential elastic supports. Classical Piston Theory is used initially for the aerodynamic pressure, but was found to be insufficient at low supersonic Mach numbers. Transform methods are applied to the convected wave equation for potential flow, and a time-dependent aerodynamic pressure correction factor is obtained. The Lagrangian of the shell system is formulated in terms of the generalized coordinates for all displacements and the Rayleigh-Ritz method is used to derive the governing differential-algebraic equations of motion. Aeroelastic limit cycle oscillations and buckling deformations are calculated in the time domain using a Runge-Kutta method in MATLAB. Three conical shell geometries were considered in the present analysis: a 3-meter diameter 70 deg. cone, a 3.7-meter 70 deg. cone, and a 6-meter diameter 70 deg. cone. The 6-meter configuration was loaded statically and the results were compared with an experimental load test of a 6-meter HIAD. Though agreement between theoretical and experimental strains was poor, the circumferential wrinkling phenomena observed during the experiments was captured by the theory and axial deformations were qualitatively similar in shape. With Piston Theory aerodynamics, the nonlinear flutter dynamic pressures of the 3-meter configuration were in agreement with the values calculated using linear theory, and the limit cycle amplitudes were generally on the order of the shell thickness. The effect of axial tension was studied for this configuration, and increasing tension was found to decrease the limit cycle amplitudes when the circumferential

  17. Advanced Solar Panel Designs

    Science.gov (United States)

    Ralph, E. L.; Linder, E. B.

    1995-01-01

    Solar panel designs that utilize new high-efficiency solar cells and lightweight rigid panel technologies are described. The resulting designs increase the specific power (W/kg) achievable in the near-term and are well suited to meet the demands of higher performance small satellites (smallsats). Advanced solar panel designs have been developed and demonstrated on two NASA SBIR contracts at Applied Solar. The first used 19% efficient, large area (5.5 cm x 6.5 cm) GaAs/Ge solar cells with a lightweight rigid graphite epoxy isogrid substrate configuration. A 1,445 sq cm coupon was fabricated and tested to demonstrate 60 W/kg with a high potential of achieving 80 W/kg. The second panel design used new 22% efficiency, dual-junction GaInP2/GaAs/Ge solar cells combined with a lightweight aluminum core/graphite fiber mesh facesheet substrate. A 1,445 sq cm coupon was fabricated and tested to demonstrate 105 W/kg with the potential of achieving 115 W/kg.

  18. INTERNATIONAL COLLABORATION: Panelling

    International Nuclear Information System (INIS)

    Anon.

    1991-01-01

    At the meeting of the International Committee for Future Accelerators (ICFA), in Geneva in July, Chairman A.N. Skrinsky of Novosibirsk reviewed ICFA progress, particularly the activities of the specialist Panels which pursue specific Committee objectives in guiding worldwide collaboration in high energy physics

  19. INTERNATIONAL COLLABORATION: Panelling

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    1991-10-15

    At the meeting of the International Committee for Future Accelerators (ICFA), in Geneva in July, Chairman A.N. Skrinsky of Novosibirsk reviewed ICFA progress, particularly the activities of the specialist Panels which pursue specific Committee objectives in guiding worldwide collaboration in high energy physics.

  20. Law Panel in action.

    Science.gov (United States)

    Odulana, J

    In September 1976 the Africa Regional Council (ARC) of IPPF created a Law Panel to 1) advise the ARC on the emphasis of laws and parenthood programs in the region, 2) investigate legal obstacles to family planning and ways of removing them, 3) institute a monitoring service on laws and court decisions affecting planned parenthood, and 4) prepare a list of lawyers and legal reformers by country. The panel has 1) recommended adoption of an IPPF Central Medical Committee and Central Law Panel statement on sterilization, adolescent fertility control, and the use of medical and auxiliary personnel in family planning services with guidelines for Africa; 2) appointed National Legal Correspondents to carry on the monitoring service mentioned above in 18 countries; and 3) discussed solutions to problems in delivering family planning services with family planning associations in Tanzania, Zambia, Mauritius, Madagascar, and Kenya. Laws governing family planning education and services, marriage, divorce, and maternity benefits in these countries are summarized. In 1978 the panel will hold 2 workshops on law and the status of women.

  1. Paneling architectural freeform surfaces

    KAUST Repository

    Eigensatz, Michael; Kilian, Martin; Schiftner, Alexander; Mitra, Niloy J.; Pottmann, Helmut; Pauly, Mark

    2010-01-01

    The emergence of large-scale freeform shapes in architecture poses big challenges to the fabrication of such structures. A key problem is the approximation of the design surface by a union of patches, socalled panels, that can be manufactured with a

  2. Photovoltaic-Panel Laminator

    Science.gov (United States)

    Keenan, R.

    1985-01-01

    Two-piece unit heats and presses protective layers to form laminate. Rubber diaphragm between upper and lower vacuum chambers alternates between neutral position and one that presses against solar-cell array, supplying distributed force necessary to press layers of laminate together. Encapsulation helps to protect cells from environment and to ensure long panel life while allowing efficient generation of electricity from Sunlight.

  3. Dynamic panel data models

    NARCIS (Netherlands)

    Bun, M.J.G.; Sarafidis, V.

    2013-01-01

    This Chapter reviews the recent literature on dynamic panel data models with a short time span and a large cross-section. Throughout the discussion we considerlinear models with additional endogenous covariates. First we give a broad overview of available inference methods placing emphasis on GMM.

  4. Nonlocal and surface effects on the flutter instability of cantilevered nanotubes conveying fluid subjected to follower forces

    Energy Technology Data Exchange (ETDEWEB)

    Bahaadini, Reza [Department of Mechanical Engineering, Sirjan University of Technology, 78137-33385 Sirjan, Islamic Republic of Iran (Iran, Islamic Republic of); Hosseini, Mohammad, E-mail: hosseini@sirjantech.ac.ir [Department of Mechanical Engineering, Sirjan University of Technology, 78137-33385 Sirjan, Islamic Republic of Iran (Iran, Islamic Republic of); Jamalpoor, Ali [Department of Mechanical Engineering, Iran University of Science and Technology, Tehran, Islamic Republic of Iran (Iran, Islamic Republic of)

    2017-03-15

    On the basis of nonlocal elasticity theory, this paper studies the dynamic structural instability behavior of cantilever nanotubes conveying fluid incorporating end concentrated follower force and distributed tangential load, resting on the visco-Pasternak substrate. In order to improve the accuracy of the results, surface effects, i.e. surface elasticity and residual stresses are considered. Extended Hamilton’s principle is implemented to obtain the nonlocal governing partial differential equation and related boundary conditions. Then, the extended Galerkin technique is used to convert partial differential equations into a general set of ordinary differential equations. Numerical results are expressed to reveal the variations of the critical flow velocity for flutter phenomenon of cantilever nanotubes with the various values of nonlocal parameter, mass ratios, nanotubes thickness, surface effects, various parameters of the visco-Pasternak medium, constant follower force and distributed compressive tangential load. Some numerical results of this research illustrated that the values of critical flutter flow velocity and stable region increase by considering surface effects. Also, critical flutter flow velocity decreases towards zero by increasing the value of the distributed compressive tangential load and constant follower force.

  5. Numerical investigation of the effects of compressibility on the flutter of a cantilevered plate in an inviscid, subsonic, open flow

    Science.gov (United States)

    Colera, Manuel; Pérez-Saborid, Miguel

    2018-06-01

    We have carried out a numerical study of the influence of the upstream Mach number on the flutter of a two-dimensional, cantilevered, flexible plate subject to a subsonic, inviscid, open flow. We have assumed a linear elastic model for the plate and that the fluid flow is governed by the linearized potential theory. The fluid equations are solved with a novel frequency-domain, finite differences method to obtain the generalized aerodynamic forces as a function of the plate displacements. Then, these generalized forces are coupled to the equation of motion of the plate and an eigenvalue analysis is performed to find the flutter point. The obtained results are in good agreement with those of related theoretical and experimental studies found in the literature. To the best of our knowledge, the analysis performed here is the first self-consistent, parametric study of the influence of the compressibility on the flutter point of a two-dimensional cantilevered plate in subsonic flow.

  6. Composite panel development at JPL

    Science.gov (United States)

    Mcelroy, Paul; Helms, Rich

    1988-01-01

    Parametric computer studies can be use in a cost effective manner to determine optimized composite mirror panel designs. An InterDisciplinary computer Model (IDM) was created to aid in the development of high precision reflector panels for LDR. The materials properties, thermal responses, structural geometries, and radio/optical precision are synergistically analyzed for specific panel designs. Promising panels designs are fabricated and tested so that comparison with panel test results can be used to verify performance prediction models and accommodate design refinement. The iterative approach of computer design and model refinement with performance testing and materials optimization has shown good results for LDR panels.

  7. Aerospace Safety Advisory Panel

    Science.gov (United States)

    1999-01-01

    This report covers the activities of the Aerospace Safety Advisory Panel (ASAP) for calendar year 1998-a year of sharp contrasts and significant successes at NASA. The year opened with the announcement of large workforce cutbacks. The slip in the schedule for launching the International Space Station (ISS) created a five-month hiatus in Space Shuttle launches. This slack period ended with the successful and highly publicized launch of the STS-95 mission. As the year closed, ISS assembly began with the successful orbiting and joining of the Functional Cargo Block (FGB), Zarya, from Russia and the Unity Node from the United States. Throughout the year, the Panel maintained its scrutiny of NASA's safety processes. Of particular interest were the potential effects on safety of workforce reductions and the continued transition of functions to the Space Flight Operations Contractor. Attention was also given to the risk management plans of the Aero-Space Technology programs, including the X-33, X-34, and X-38. Overall, the Panel concluded that safety is well served for the present. The picture is not as clear for the future. Cutbacks have limited the depth of talent available. In many cases, technical specialties are 'one deep.' The extended hiring freeze has resulted in an older workforce that will inevitably suffer significant departures from retirements in the near future. The resulting 'brain drain' could represent a future safety risk unless appropriate succession planning is started expeditiously. This and other topics are covered in the section addressing workforce. The major NASA programs are also limited in their ability to plan property for the future. This is of particular concern for the Space Shuttle and ISS because these programs are scheduled to operate well into the next century. In the case of the Space Shuttle, beneficial and mandatory safety and operational upgrades are being delayed because of a lack of sufficient present funding. Likewise, the ISS has

  8. Investigation on Wall Panel Sandwiched With Lightweight Concrete

    Science.gov (United States)

    Lakshmikandhan, K. N.; Harshavardhan, B. S.; Prabakar, J.; Saibabu, S.

    2017-08-01

    The rapid population growth and urbanization have made a massive demand for the shelter and construction materials. Masonry walls are the major component in the housing sector and it has brittle characteristics and exhibit poor performance against the uncertain loads. Further, the structure requires heavier sections for carrying the dead weight of masonry walls. The present investigations are carried out to develop a simple, lightweight and cost effective technology for replacing the existing wall systems. The lightweight concrete is developed for the construction of sandwich wall panel. The EPS (Expanded Polystyrene) beads of 3 mm diameter size are mixed with concrete and developed a lightweight concrete with a density 9 kN/m3. The lightweight sandwich panel is cast with a lightweight concrete inner core and ferrocement outer skins. This lightweight wall panel is tested for in-plane compression loading. A nonlinear finite element analysis with damaged plasticity model is carried out with both material and geometrical nonlinearities. The experimental and analytical results were compared. The finite element study predicted the ultimate load carrying capacity of the sandwich panel with reasonable accuracy. The present study showed that the lightweight concrete is well suitable for the lightweight sandwich wall panels.

  9. Panel and planar experimental shear behavior of wood panels ...

    African Journals Online (AJOL)

    Panel shear strength along the thickness and planar shear along the length of wood panels laminated softwood oriented OSB 10 mm thick, conditioned at different moisture contents (anhydrous medium, ambient temperature and humid medium) was measured on standardized test specimens, cut in half lengthwise panel ...

  10. Nonlinear dynamics of attractive magnetic bearings

    Science.gov (United States)

    Hebbale, K. V.; Taylor, D. L.

    1987-01-01

    The nonlinear dynamics of a ferromagnetic shaft suspended by the force of attraction of 1, 2, or 4 independent electromagnets is presented. Each model includes a state variable feedback controller which has been designed using the pole placement method. The constitutive relationships for the magnets are derived analytically from magnetic circuit theory, and the effects of induced eddy currents due to the rotation of the journal are included using Maxwell's field relations. A rotor suspended by four electro-magnets with closed loop feedback is shown to have nine equilibrium points within the bearing clearance space. As the rotor spin speed increases, the system is shown to pass through a Hopf bifurcation (a flutter instability). Using center manifold theory, this bifurcation can be shown to be of the subcritical type, indicating an unstable limit cycle below the critical speed. The bearing is very sensitive to initial conditions, and the equilibrium position is easily upset by transient excitation. The results are confirmed by numerical simulation.

  11. FEMA DFIRM Panel Scheme Polygons

    Data.gov (United States)

    Minnesota Department of Natural Resources — This layer contains information about the Flood Insurance Rate Map (FIRM) panel areas. The spatial entities representing FIRM panels are polygons. The polygon for...

  12. Report of Industry Panel Group

    Science.gov (United States)

    Gallimore, Simon; Gier, Jochen; Heitland, Greg; Povinelli, Louis; Sharma, Om; VandeWall, Allen

    2006-01-01

    A final report is presented from the industry panel group. The contents include: 1) General comments; 2) Positive progress since Minnowbrook IV; 3) Industry panel outcome; 4) Prioritized turbine projects; 5) Prioritized compressor projects; and 6) Miscellaneous.

  13. Mounting clips for panel installation

    Science.gov (United States)

    Cavieres, Andres; Al-Haddad, Tristan; Goodman, Joseph

    2017-07-11

    A photovoltaic panel mounting clip comprising a base, central indexing tabs, flanges, lateral indexing tabs, and vertical indexing tabs. The mounting clip removably attaches one or more panels to a beam or the like structure, both mechanically and electrically. It provides secure locking of the panels in all directions, while providing guidance in all directions for accurate installation of the panels to the beam or the like structure.

  14. Nonlinear Elasticity

    Science.gov (United States)

    Fu, Y. B.; Ogden, R. W.

    2001-05-01

    This collection of papers by leading researchers in the field of finite, nonlinear elasticity concerns itself with the behavior of objects that deform when external forces or temperature gradients are applied. This process is extremely important in many industrial settings, such as aerospace and rubber industries. This book covers the various aspects of the subject comprehensively with careful explanations of the basic theories and individual chapters each covering a different research direction. The authors discuss the use of symbolic manipulation software as well as computer algorithm issues. The emphasis is placed firmly on covering modern, recent developments, rather than the very theoretical approach often found. The book will be an excellent reference for both beginners and specialists in engineering, applied mathematics and physics.

  15. Nonlinear resonances

    CERN Document Server

    Rajasekar, Shanmuganathan

    2016-01-01

    This introductory text presents the basic aspects and most important features of various types of resonances and anti-resonances in dynamical systems. In particular, for each resonance, it covers the theoretical concepts, illustrates them with case studies, and reviews the available information on mechanisms, characterization, numerical simulations, experimental realizations, possible quantum analogues, applications and significant advances made over the years. Resonances are one of the most fundamental phenomena exhibited by nonlinear systems and refer to specific realizations of maximum response of a system due to the ability of that system to store and transfer energy received from an external forcing source. Resonances are of particular importance in physical, engineering and biological systems - they can prove to be advantageous in many applications, while leading to instability and even disasters in others. The book is self-contained, providing the details of mathematical derivations and techniques invo...

  16. Experience with citizens panels

    International Nuclear Information System (INIS)

    Selwyn, J.

    2002-01-01

    In May 1999, 200 delegates attended a four-day UK Consensus Conference on radioactive waste management, which was organised by the UK Centre for Economic and Environmental Development (UK CEED) and supported by the government, industry and environmental groups. The event brought together a Citizens' Panel of fifteen people, randomly selected to represent a cross section of the British public, together with the major players in the debate. The four-day conference saw the panel cross-examine expert witnesses from organisations such as NIREX, British Nuclear Fuels Limited, the Ministry of Defence, Greenpeace and Friends of the Earth. The findings of their investigations were put together in a report containing detailed recommendations for government and industry and presented to the Minister on the final day. (author)

  17. Right atrial angiographic evaluation of the posterior isthmus: relevance for ablation of typical atrial flutter.

    Science.gov (United States)

    Heidbüchel, H; Willems, R; van Rensburg, H; Adams, J; Ector, H; Van de Werf, F

    2000-05-09

    Gaining anatomic information about the posterior isthmus is not generally part of flutter ablation procedures. We postulated that right atrial (RA) angiography could rationalize the ablation approach by revealing the conformation of the isthmus. In 100 consecutive patients, biplane RA angiography was performed before ablation to guide catheter contact with the isthmus along its length. Angiography showed a wide variation in the width of the isthmus (17 to 54 mm; 31.3+/-7.9), its angle with the inferior vena cava in the right anterior oblique projection (68 degrees to 114 degrees; 90.3+/-9.0 degrees ), and its lateral position relative to the inferior vena cava in the left anterior oblique projection. A deep sub-Eustachian recess was revealed in 47%, with a mean depth of 4.3+/-2.1 mm (1.5 to 9.4). A Eustachian valve was visualized in 24%. Ablation resulted in bidirectional conduction block (which could be transient) in all, with a median of 2 dragging radiofrequency (RF) applications (2.3+/-2.5 RF applications; 57 degrees C, deep pouches. The number of RF applications decreased statistically throughout the study, indicating a learning curve. No patient had a recurrence after a follow-up of 13+/-11 months. Right atrial angiography reveals a highly variable isthmus anatomy, often showing particular configurations that can make ablation more laborious. Rational adaptation of the ablation approach to these anatomic findings may contribute to successful ablation.

  18. LPV Modeling and Control for Active Flutter Suppression of a Smart Airfoil

    Science.gov (United States)

    Al-Hajjar, Ali M. H.; Al-Jiboory, Ali Khudhair; Swei, Sean Shan-Min; Zhu, Guoming

    2018-01-01

    In this paper, a novel technique of linear parameter varying (LPV) modeling and control of a smart airfoil for active flutter suppression is proposed, where the smart airfoil has a groove along its chord and contains a moving mass that is used to control the airfoil pitching and plunging motions. The new LPV modeling technique is proposed that uses mass position as a scheduling parameter to describe the physical constraint of the moving mass, in addition the hard constraint at the boundaries is realized by proper selection of the parameter varying function. Therefore, the position of the moving mass and the free stream airspeed are considered the scheduling parameters in the study. A state-feedback based LPV gain-scheduling controller with guaranteed H infinity performance is presented by utilizing the dynamics of the moving mass as scheduling parameter at a given airspeed. The numerical simulations demonstrate the effectiveness of the proposed LPV control architecture by significantly improving the performance while reducing the control effort.

  19. Evaluation of diffuse-illumination holographic cinematography in a flutter cascade

    Science.gov (United States)

    Decker, A. J.

    1986-01-01

    Since 1979, the Lewis Research Center has examined holographic cinematography for three-dimensional flow visualization. The Nd:YAG lasers used were Q-switched, double-pulsed, and frequency-doubled, operating at 20 pulses per second. The primary subjects for flow visualization were the shock waves produced in two flutter cascades. Flow visualization was by diffuse-illumination, double-exposure, and holographic interferometry. The performances of the lasers, holography, and diffuse-illumination interferometry are evaluated in single-window wind tunnels. The fringe-contrast factor is used to evaluate the results. The effects of turbulence on shock-wave visualization in a transonic flow are discussed. The depth of field for visualization of a turbulent structure is demonstrated to be a measure of the relative density and scale of that structure. Other items discussed are the holographic emulsion, tests of coherence and polarization, effects of windows and diffusers, hologram bleaching, laser configurations, influence and handling of specular reflections, modes of fringe localization, noise sources, and coherence requirements as a function of the pulse energy. Holography and diffuse illumination interferometry are also reviewed.

  20. Panel data analysis using EViews

    CERN Document Server

    Agung, I Gusti Ngurah

    2013-01-01

    A comprehensive and accessible guide to panel data analysis using EViews software This book explores the use of EViews software in creating panel data analysis using appropriate empirical models and real datasets. Guidance is given on developing alternative descriptive statistical summaries for evaluation and providing policy analysis based on pool panel data. Various alternative models based on panel data are explored, including univariate general linear models, fixed effect models and causal models, and guidance on the advantages and disadvantages of each one is given. Panel Data Analysis

  1. Lightweight, Thermally Insulating Structural Panels

    Science.gov (United States)

    Eisen, Howard J.; Hickey, Gregory; Wen, Liang-Chi; Layman, William E.; Rainen, Richard A.; Birur, Gajanana C.

    1996-01-01

    Lightweight, thermally insulating panels that also serve as structural members developed. Honeycomb-core panel filled with low-thermal-conductivity, opacified silica aerogel preventing convection and minimizes internal radiation. Copper coating on face sheets reduces radiation. Overall thermal conductivities of panels smaller than state-of-art commercial non-structurally-supporting foam and fibrous insulations. On Earth, panels suitable for use in low-air-pressure environments in which lightweight, compact, structurally supporting insulation needed; for example, aboard high-altitude aircraft or in partially evacuated panels in refrigerators.

  2. Large thermal protection system panel

    Science.gov (United States)

    Weinberg, David J. (Inventor); Myers, Franklin K. (Inventor); Tran, Tu T. (Inventor)

    2003-01-01

    A protective panel for a reusable launch vehicle provides enhanced moisture protection, simplified maintenance, and increased temperature resistance. The protective panel includes an outer ceramic matrix composite (CMC) panel, and an insulative bag assembly coupled to the outer CMC panel for isolating the launch vehicle from elevated temperatures and moisture. A standoff attachment system attaches the outer CMC panel and the bag assembly to the primary structure of the launch vehicle. The insulative bag assembly includes a foil bag having a first opening shrink fitted to the outer CMC panel such that the first opening and the outer CMC panel form a water tight seal at temperatures below a desired temperature threshold. Fibrous insulation is contained within the foil bag for protecting the launch vehicle from elevated temperatures. The insulative bag assembly further includes a back panel coupled to a second opening of the foil bag such that the fibrous insulation is encapsulated by the back panel, the foil bag, and the outer CMC panel. The use of a CMC material for the outer panel in conjunction with the insulative bag assembly eliminates the need for waterproofing processes, and ultimately allows for more efficient reentry profiles.

  3. [Nonlinear magnetohydrodynamics

    International Nuclear Information System (INIS)

    1994-01-01

    Resistive MHD equilibrium, even for small resistivity, differs greatly from ideal equilibrium, as do the dynamical consequences of its instabilities. The requirement, imposed by Faraday's law, that time independent magnetic fields imply curl-free electric fields, greatly restricts the electric fields allowed inside a finite-resistivity plasma. If there is no flow and the implications of the Ohm's law are taken into account (and they need not be, for ideal equilibria), the electric field must equal the resistivity times the current density. The vanishing of the divergence of the current density then provides a partial differential equation which, together with boundary conditions, uniquely determines the scalar potential, the electric field, and the current density, for any given resistivity profile. The situation parallels closely that of driven shear flows in hydrodynamics, in that while dissipative steady states are somewhat more complex than ideal ones, there are vastly fewer of them to consider. Seen in this light, the vast majority of ideal MHD equilibria are just irrelevant, incapable of being set up in the first place. The steady state whose stability thresholds and nonlinear behavior needs to be investigated ceases to be an arbitrary ad hoc exercise dependent upon the whim of the investigator, but is determined by boundary conditions and choice of resistivity profile

  4. Testing for Unit Roots in Small Panels with Short-run and Long-run Cross-sectional Dependencies

    OpenAIRE

    Yoosoon Chang; Wonho Song

    2009-01-01

    An IV approach, using as instruments non-linear transformations of the lagged levels, is explored to test for unit roots in panels with general dependency and heterogeneity across cross-sectional units. We allow not only for the cross-sectional dependencies of innovations, but also for the presence of co-integration across cross-sectional levels. Unbalanced panels and panels with differing individual short-run dynamics and cross-sectionally related dynamics are also permitted. We also more ca...

  5. Thermal insulating panel

    Energy Technology Data Exchange (ETDEWEB)

    Hughes, J.T.

    1985-09-11

    A panel of thermal insulation material has at least one main portion which comprises a dry particulate insulation material compressed within a porous envelope so that it is rigid or substantially rigid and at least one auxiliary portion which is secured to and extends along at least one of the edges of the main portions. The auxiliary portions comprise a substantially uncompressed dry particulate insulation material contained within an envelope. The insulation material of the auxiliary portion may be the same as or may be different from the insulation material of the main portion. The envelope of the auxiliary portion may be made of a porous or a non-porous material. (author).

  6. Concentrating photovoltaic solar panel

    Science.gov (United States)

    Cashion, Steven A; Bowser, Michael R; Farrelly, Mark B; Hines, Braden E; Holmes, Howard C; Johnson, Jr., Richard L; Russell, Richard J; Turk, Michael F

    2014-04-15

    The present invention relates to photovoltaic power systems, photovoltaic concentrator modules, and related methods. In particular, the present invention features concentrator modules having interior points of attachment for an articulating mechanism and/or an articulating mechanism that has a unique arrangement of chassis members so as to isolate bending, etc. from being transferred among the chassis members. The present invention also features adjustable solar panel mounting features and/or mounting features with two or more degrees of freedom. The present invention also features a mechanical fastener for secondary optics in a concentrator module.

  7. Photovoltaic panel clamp

    Science.gov (United States)

    Mittan, Margaret Birmingham [Oakland, CA; Miros, Robert H. J. [Fairfax, CA; Brown, Malcolm P [San Francisco, CA; Stancel, Robert [Loss Altos Hills, CA

    2012-06-05

    A photovoltaic panel clamp includes an upper and lower section. The interface between the assembled clamp halves and the module edge is filled by a flexible gasket material, such as EPDM rubber. The gasket preferably has small, finger like protrusions that allow for easy insertion onto the module edge while being reversed makes it more difficult to remove them from the module once installed. The clamp includes mounting posts or an integral axle to engage a bracket. The clamp also may include a locking tongue to secure the clamp to a bracket.

  8. Optimization of Sensing and Feedback Control for Vibration/Flutter of Rotating Disk by PZT Actuators via Air Coupled Pressure

    Directory of Open Access Journals (Sweden)

    Bingfeng Ju

    2011-03-01

    Full Text Available In this paper, a feedback control mechanism and its optimization for rotating disk vibration/flutter via changes of air-coupled pressure generated using piezoelectric patch actuators are studied. A thin disk rotates in an enclosure, which is equipped with a feedback control loop consisting of a micro-sensor, a signal processor, a power amplifier, and several piezoelectric (PZT actuator patches distributed on the cover of the enclosure. The actuator patches are mounted on the inner or the outer surfaces of the enclosure to produce necessary control force required through the airflow around the disk. The control mechanism for rotating disk flutter using enclosure surfaces bonded with sensors and piezoelectric actuators is thoroughly studied through analytical simulations. The sensor output is used to determine the amount of input to the actuator for controlling the response of the disk in a closed loop configuration. The dynamic stability of the disk-enclosure system, together with the feedback control loop, is analyzed as a complex eigenvalue problem, which is solved using Galerkin’s discretization procedure. The results show that the disk flutter can be reduced effectively with proper configurations of the control gain and the phase shift through the actuations of PZT patches. The effectiveness of different feedback control methods in altering system characteristics and system response has been investigated. The control capability, in terms of control gain, phase shift, and especially the physical configuration of actuator patches, are also evaluated by calculating the complex eigenvalues and the maximum displacement produced by the actuators. To achieve a optimal control performance, sizes, positions and shapes of PZT patches used need to be optimized and such optimization has been achieved through numerical simulations.

  9. Optimization of sensing and feedback control for vibration/flutter of rotating disk by PZT actuators via air coupled pressure.

    Science.gov (United States)

    Yan, Tianhong; Xu, Xinsheng; Han, Jianqiang; Lin, Rongming; Ju, Bingfeng; Li, Qing

    2011-01-01

    In this paper, a feedback control mechanism and its optimization for rotating disk vibration/flutter via changes of air-coupled pressure generated using piezoelectric patch actuators are studied. A thin disk rotates in an enclosure, which is equipped with a feedback control loop consisting of a micro-sensor, a signal processor, a power amplifier, and several piezoelectric (PZT) actuator patches distributed on the cover of the enclosure. The actuator patches are mounted on the inner or the outer surfaces of the enclosure to produce necessary control force required through the airflow around the disk. The control mechanism for rotating disk flutter using enclosure surfaces bonded with sensors and piezoelectric actuators is thoroughly studied through analytical simulations. The sensor output is used to determine the amount of input to the actuator for controlling the response of the disk in a closed loop configuration. The dynamic stability of the disk-enclosure system, together with the feedback control loop, is analyzed as a complex eigenvalue problem, which is solved using Galerkin's discretization procedure. The results show that the disk flutter can be reduced effectively with proper configurations of the control gain and the phase shift through the actuations of PZT patches. The effectiveness of different feedback control methods in altering system characteristics and system response has been investigated. The control capability, in terms of control gain, phase shift, and especially the physical configuration of actuator patches, are also evaluated by calculating the complex eigenvalues and the maximum displacement produced by the actuators. To achieve a optimal control performance, sizes, positions and shapes of PZT patches used need to be optimized and such optimization has been achieved through numerical simulations.

  10. Sick sinus syndrome, progressive cardiac conduction disease, atrial flutter and ventricular tachycardia caused by a novel SCN5A mutation

    DEFF Research Database (Denmark)

    Holst, Anders G; Liang, Bo; Jespersen, Thomas

    2010-01-01

    father carried the same mutation, but had a milder phenotype, presenting with progressive cardiac conduction later in life. The mutation was found to result in a loss-of-function in the sodium current. In conclusion, the same SCN5A mutation can result in a wide array of clinical phenotypes and perhaps......Mutations in the cardiac sodium channel encoded by the gene SCN5A can result in a wide array of phenotypes. We report a case of a young male with a novel SCN5A mutation (R121W) afflicted by sick sinus syndrome, progressive cardiac conduction disorder, atrial flutter and ventricular tachycardia. His...

  11. Nonlinear beam mechanics

    NARCIS (Netherlands)

    Westra, H.J.R.

    2012-01-01

    In this Thesis, nonlinear dynamics and nonlinear interactions are studied from a micromechanical point of view. Single and doubly clamped beams are used as model systems where nonlinearity plays an important role. The nonlinearity also gives rise to rich dynamic behavior with phenomena like

  12. Thromboprophylaxis for Patients with High-risk Atrial Fibrillation and Flutter Discharged from the Emergency Department

    Directory of Open Access Journals (Sweden)

    E. Margaret Warton

    2018-02-01

    Full Text Available Introduction: Many patients with atrial fibrillation or atrial flutter (AF/FL who are high risk for ischemic stroke are not receiving evidence-based thromboprophylaxis. We examined anticoagulant prescribing within 30 days of receiving dysrhythmia care for non-valvular AF/FL in the emergency department (ED. Methods: This prospective study included non-anticoagulated adults at high risk for ischemic stroke (ATRIA score ≥7 who received emergency AF/FL care and were discharged home from seven community EDs between May 2011 and August 2012. We characterized oral anticoagulant prescribing patterns and identified predictors of receiving anticoagulants within 30 days of the index ED visit. We also describe documented reasons for withholding anticoagulation. Results: Of 312 eligible patients, 128 (41.0% were prescribed anticoagulation at ED discharge or within 30 days. Independent predictors of anticoagulation included age (adjusted odds ratio [aOR] 0.89 per year, 95% confidence interval [CI] 0.82–0.96; ED cardiology consultation (aOR 1.89, 95% CI [1.10–3.23]; and failure of sinus restoration by time of ED discharge (aOR 2.65, 95% CI [1.35–5.21]. Reasons for withholding anticoagulation at ED discharge were documented in 139 of 227 cases (61.2%, the most common of which were deferring the shared decision-making process to the patient’s outpatient provider, perceived bleeding risk, patient refusal, and restoration of sinus rhythm. Conclusion: Approximately 40% of non-anticoagulated AF/FL patients at high risk for stroke who presented for emergency dysrhythmia care were prescribed anticoagulation within 30 days. Physicians were less likely to anticoagulate older patients and those with ED sinus restoration. Opportunities exist to improve rates of thromboprophylaxis in this high-risk population.

  13. Solar panel parallel mounting configuration

    Science.gov (United States)

    Mutschler, Jr., Edward Charles (Inventor)

    1998-01-01

    A spacecraft includes a plurality of solar panels interconnected with a power coupler and an electrically operated device to provide power to the device when the solar cells are insolated. The solar panels are subject to bending distortion when entering or leaving eclipse. Spacecraft attitude disturbances are reduced by mounting each of the solar panels to an elongated boom made from a material with a low coefficient of thermal expansion, so that the bending of one panel is not communicated to the next. The boom may be insulated to reduce its bending during changes in insolation. A particularly advantageous embodiment mounts each panel to the boom with a single mounting, which may be a hinge. The single mounting prevents transfer of bending moments from the panel to the boom.

  14. Reliability Study in Solar Panels

    OpenAIRE

    Español Lifante, Albert

    2012-01-01

    Crystalline silicon Modules are formed by single silicon photovoltaic cells. Since each one of these cells individually contributes to the overall electric power of the panel, the failure of one of them directly affects to its benefits and performance. To Minimize these negative effects, junction boxes with few bypass diodes are usually included in Photovoltaic Solar panels. A still experimental way to built solar panels is to integrate bypass diodes in every single cell, which would in...

  15. ALDS 1978 panel review. [PNL

    Energy Technology Data Exchange (ETDEWEB)

    Hall, D.L. (ed.)

    1979-08-01

    Pacific Northwest Laboratory (PNL) is examining the analysis of large data sets (ALDS). After one year's work, a panel was convened to evaluate the project. This document is the permanent record of that panel review. It consists of edited transcripts of presentations made to the panel by the PNL staff, a summary of the responses of the panel to these presentations, and PNL's plans for the development of the ALDS project. The representations of the PNL staff described various aspects of the project and/or the philosophy surrounding the project. Supporting materials appear in appendixes. 20 figures, 4 tables. (RWR)

  16. Robust Determinants of Growth in Asian Developing Economies: A Bayesian Panel Data Model Averaging Approach

    OpenAIRE

    LEON-GONZALEZ, Roberto; VINAYAGATHASAN, Thanabalasingam

    2013-01-01

    This paper investigates the determinants of growth in the Asian developing economies. We use Bayesian model averaging (BMA) in the context of a dynamic panel data growth regression to overcome the uncertainty over the choice of control variables. In addition, we use a Bayesian algorithm to analyze a large number of competing models. Among the explanatory variables, we include a non-linear function of inflation that allows for threshold effects. We use an unbalanced panel data set of 27 Asian ...

  17. Proficiency testing for sensory profile panels : measuring panel performance

    NARCIS (Netherlands)

    Mcewan, J.A.; Hunter, E.A.; Gemert, L.J. van; Lea, P.

    2002-01-01

    Proficiency testing in sensory analysis is an important step towards demonstrating that results from one sensory panel are consistent with the results of other sensory panels. The uniqueness of sensory analysis poses some specific problems for measuring the proficiency of the human instrument

  18. Panel summary report

    International Nuclear Information System (INIS)

    Anon.

    1979-01-01

    Previous Advisory Group Meetings have led to IAEA Technical Reports No.15=5 (1974) on thermal discharge, 118 (1970) and 169 (1975) on sampling, storage and analysis methods for marine radioactivity studies, 167 (1975) on design of marine biological studies permitting comparative evaluation, and 172 (1976) on the effects of ionizing radiation on aquative organisms and eco-systems. The aim of the present report was a bringing into perspective not only problems designing radioecological experiments but to describe reliable experimental methodology suitable for a successful evaluation of radioactivity cycling, and of the effects of such radioactive additions to aquatic environments, as a result of nuclear activities. Specific examples are described. Individual studies presented to the Panel have been treated in detail, and constitute 19 separate INIS entries

  19. Non-linear aeroelastic prediction for aircraft applications

    Science.gov (United States)

    de C. Henshaw, M. J.; Badcock, K. J.; Vio, G. A.; Allen, C. B.; Chamberlain, J.; Kaynes, I.; Dimitriadis, G.; Cooper, J. E.; Woodgate, M. A.; Rampurawala, A. M.; Jones, D.; Fenwick, C.; Gaitonde, A. L.; Taylor, N. V.; Amor, D. S.; Eccles, T. A.; Denley, C. J.

    2007-05-01

    Current industrial practice for the prediction and analysis of flutter relies heavily on linear methods and this has led to overly conservative design and envelope restrictions for aircraft. Although the methods have served the industry well, it is clear that for a number of reasons the inclusion of non-linearity in the mathematical and computational aeroelastic prediction tools is highly desirable. The increase in available and affordable computational resources, together with major advances in algorithms, mean that non-linear aeroelastic tools are now viable within the aircraft design and qualification environment. The Partnership for Unsteady Methods in Aerodynamics (PUMA) Defence and Aerospace Research Partnership (DARP) was sponsored in 2002 to conduct research into non-linear aeroelastic prediction methods and an academic, industry, and government consortium collaborated to address the following objectives: To develop useable methodologies to model and predict non-linear aeroelastic behaviour of complete aircraft. To evaluate the methodologies on real aircraft problems. To investigate the effect of non-linearities on aeroelastic behaviour and to determine which have the greatest effect on the flutter qualification process. These aims have been very effectively met during the course of the programme and the research outputs include: New methods available to industry for use in the flutter prediction process, together with the appropriate coaching of industry engineers. Interesting results in both linear and non-linear aeroelastics, with comprehensive comparison of methods and approaches for challenging problems. Additional embryonic techniques that, with further research, will further improve aeroelastics capability. This paper describes the methods that have been developed and how they are deployable within the industrial environment. We present a thorough review of the PUMA aeroelastics programme together with a comprehensive review of the relevant research

  20. NUMERICAL AND EXPERIMENTAL INVESTIGATION ON THE FLUTTER OF CANTILEVERED PLATES WITH FREE LEADING EDGE IN AXIAL FLOW

    Directory of Open Access Journals (Sweden)

    I. P. G. SOPAN RAHTIKA

    2017-10-01

    Full Text Available This paper reports the results of the numerical and experimental investigation on the flutter of cantilevered thin flat plates with free leading edge in axial flow. Three methods of in-vacuo modal analyses of the plates are presented and compared in this paper, namely the finite element modal analysis using ANSYS STUDENT Modal, the analytical beam model, and the experimental modal analysis. In this study, the numerical Fluid Structure Interaction was performed using the ANSYS STUDENT Structural Transient Analysis and ANSYS STUDENT CFX to obtain the system response in the time domain. Furthermore, the experimental investigation was conducted in the smooth flow of a wind tunnel to observe the flutter speeds of the plates and their vibration characteristics. The plates’ vibration behaviors were mapped on the normalized air speed. The normalized air speed can be divided into four speed zones based on the experimental plates’ vibration characteristics. A new finding observed during the experiments is the presence of intermittent vibration behavior that is unique to the free leading edge configuration and has not been reported by other researchers in the earlier references of the clamped leading edge configuration. The potential application of this Fluid Structure Interaction configuration to wind harvesting is inquired.

  1. Assessing Fan Flutter Stability in Presence of Inlet Distortion Using One-Way and Two-Way Coupled Methods

    Science.gov (United States)

    Herrick, Gregory P.

    2014-01-01

    Concerns regarding noise, propulsive efficiency, and fuel burn are inspiring aircraft designs wherein the propulsive turbomachines are partially (or fully) embedded within the airframe; such designs present serious concerns with regard to aerodynamic and aeromechanic performance of the compression system in response to inlet distortion. Previously, a preliminary design of a forward-swept high-speed fan exhibited flutter concerns in clean-inlet flows, and the present author then studied this fan further in the presence of off-design distorted in-flows. Continuing this research, a three-dimensional, unsteady, Navier-Stokes computational fluid dynamics code is again applied to analyze and corroborate fan performance with clean inlet flow and now with a simplified, sinusoidal distortion of total pressure at the aerodynamic interface plane. This code, already validated in its application to assess aerodynamic damping of vibrating blades at various flow conditions using a one-way coupled energy-exchange approach, is modified to include a two-way coupled timemarching aeroelastic simulation capability. The two coupling methods are compared in their evaluation of flutter stability in the presence of distorted in-flows.

  2. Assessing Fan Flutter Stability in the Presence of Inlet Distortion Using One-way and Two-way Coupled Methods

    Science.gov (United States)

    Herrick, Gregory P.

    2014-01-01

    Concerns regarding noise, propulsive efficiency, and fuel burn are inspiring aircraft designs wherein the propulsive turbomachines are partially (or fully)embedded within the airframe; such designs present serious concerns with regard to aerodynamic and aeromechanic performance of the compression system in response to inlet distortion. Previously, a preliminary design of a forward-swept high-speed fan exhibited flutter concerns in clean-inlet flows, and the present author then studied this fan further in the presence of off-design distorted in-flows. A three-dimensional, unsteady, Navier-Stokes computational fluid dynamics code is applied to analyze and corroborate fan performance with clean inlet flow. This code, already validated in its application to assess aerodynamic damping of vibrating blades at various flow conditions using a loosely-coupled approach, is modified to include a tightly-coupled aeroelastic simulation capability, and then loosely-coupled and tightly-coupled methods arecompared in their evaluation of flutter stability in distorted in-flows.

  3. Anatomic characterization of cavotricuspid isthmus by 3D transesophageal echocardiography in patients undergoing radiofrequency ablation of typical atrial flutter.

    Science.gov (United States)

    Regoli, François; Faletra, Francesco; Marcon, Serena; Leo, Laura Anna; Dequarti, Maria Cristina; Caputo, Maria Luce; Conte, Giulio; Moccetti, Tiziano; Auricchio, Angelo

    2018-01-01

    Radiofrequency ablation (RFA) is the treatment of choice of cavotricuspid isthmus (CTI)-dependent atrial flutter. Procedural time is highly variable due to anatomical structures. This study aimed to characterize CTI anatomy by transesophageal 3D echocardiography imaging (3D-TEE) to identify anatomic structures related to longer ablation time. Thirty-one consecutive patients (mean age 67.3 ± 11.5 years, 22 males) underwent CTI-ablation procedure. Before ablation, TEE was performed and 3D-TEE images were acquired to evaluate CTI anatomy qualitatively as well as perform measures of CTI morphological features. The electrophysiologist performing RFA was blinded to 3D-TEE data. Bidirectional block of CTI was achieved in all patients without procedural complications after a median ablation time of 11 (IQR 7-14) min. Patients with RFA time ≥11 min (Group 2) presented lower left ventricular ejection fraction (51.1 ± 17.0 vs. 59.5 ± 6.6%, P 3D-TEE imaging is extremely helpful in qualitative and quantitative evaluation of CTI anatomy in patients undergoing RFA for symptomatic typical atrial flutter. Detection of a deep right atrial pouch was found to be associated with significantly prolonged CTI ablation time to achieve bidirectional block. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2017. For permissions, please email: journals.permissions@oup.com.

  4. Flutter instability of cantilevered carbon nanotubes caused by magnetic fluid flow subjected to a longitudinal magnetic field

    Science.gov (United States)

    Sadeghi-Goughari, Moslem; Jeon, Soo; Kwon, Hyock-Ju

    2018-04-01

    CNT (Carbon nanotube)-based fluidic systems hold a great potential for emerging medical applications such as drug delivery for cancer therapy. CNTs can be used to deliver anticancer drugs into a target site under a magnetic field guidance. One of the critical issues in designing such systems is how to avoid the vibration induced by the fluid flow, which is undesirable and may even promote the structural instability. The main objective of the present research is to develop a fluid structure interaction (FSI) model to investigate the flutter instability of a cantilevered CNT induced by a magnetic fluid flow under a longitudinal magnetic field. The CNT is assumed to be embedded in a viscoelastic matrix to consider the effect of biological medium around it. To obtain a dynamical model for the system, the Navier-Stokes theory of magnetic-fluid flow is coupled to the Euler-Bernoulli beam model for CNT. The small size effects of the magnetic fluid and CNT are considered through the small scale parameters including Knudsen number (Kn) and the nonlocal parameter. Then, the extended Galerkin's method is applied to solve the FSI governing equations, and to derive the stability diagrams of the system. Results show how the magnetic properties of the fluid flow have an effect on improving the stability of the cantilevered CNT by increasing the flutter velocity.

  5. Strong increase of solar panels

    International Nuclear Information System (INIS)

    Segers, R.; Janssen, S.

    2012-01-01

    The number of installed solar panels in 2011 has increased again. 40 megawatt of new panels have been installed. This increase is twice as high as the year before. The production of solar power increased to 90 million kWh in 2011 as a result of this expansion. However, the share of solar power in total energy use is still very limited. [nl

  6. Panel Smooth Transition Regression Models

    DEFF Research Database (Denmark)

    González, Andrés; Terasvirta, Timo; Dijk, Dick van

    We introduce the panel smooth transition regression model. This new model is intended for characterizing heterogeneous panels, allowing the regression coefficients to vary both across individuals and over time. Specifically, heterogeneity is allowed for by assuming that these coefficients are bou...

  7. Matlab Software for Spatial Panels

    NARCIS (Netherlands)

    Elhorst, J.Paul

    2014-01-01

    Elhorst provides Matlab routines to estimate spatial panel data models at his website. This article extends these routines to include the bias correction procedure proposed by Lee and Yu if the spatial panel data model contains spatial and/or time-period fixed effects, the direct and indirect

  8. Mounting clips for panel installation

    Science.gov (United States)

    Cavieres, Andres; Al-Haddad, Tristan; Goodman, Joseph; Valdes, Francisco

    2017-02-14

    An exemplary mounting clip for removably attaching panels to a supporting structure comprises a base, spring locking clips, a lateral flange, a lever flange, and a spring bonding pad. The spring locking clips extend upwardly from the base. The lateral flange extends upwardly from a first side of the base. The lateral flange comprises a slot having an opening configured to receive at least a portion of one of the one or more panels. The lever flange extends outwardly from the lateral flange. The spring bonding flange extends downwardly from the lever flange. At least a portion of the first spring bonding flange comprises a serrated edge for gouging at least a portion of the one or more panels when the one or more panels are attached to the mounting clip to electrically and mechanically couple the one or more panels to the mounting clip.

  9. Electrocardiographic and clinical predictors of torsades de pointes induced by almokalant infusion in patients with chronic atrial fibrillation or flutter : A prospective study

    NARCIS (Netherlands)

    Houltz, B; Darpo, B; Edvardsson, N; Blomstrom, P; Brachmann, J; Crijns, Harry J. G. M.; Jensen, Steen M.; Svernhage, E; Vallin, H; Swedberg, K

    The aim of this study was to identify predictors of torsades de pointes (TdP) in patients with atrial fibrillation (AF) or flutter exposed to the Class III antiarrhythmic drug almokalant. TdP can be caused by drugs that prolong myocardial repolarization. One hundred patients received almokalant

  10. Flutter-by Interactive Butterfly Using interactivity to excite and educate children about butterflies and the National Museum of Play at The Strong's Dancing Wings Butterfly Garden

    Science.gov (United States)

    Powers, Lydia

    The National Museum of Play at The Strong's Dancing Wings Butterfly Garden is a tropical rainforest that allows visitors to step into the world of butterflies, but lacks a more comprehensive educational element to teach visitors additional information about butterflies. Flutter-by Interactive Butterfly is a thesis project designed to enhance younger visitors' experience of the Dancing Wings Butterfly Garden with an interactive educational application that aligns with The Strong's mission of encouraging learning, creativity, and discovery. This was accomplished through a series of fun and educational games and animations, designed for use as a kiosk outside the garden and as a part of The Strong's website. Content, planning, and organization of this project has been completed through research and observation of the garden in the following areas: its visitors, butterflies, best usability practices for children, and game elements that educate and engage children. Flutter-by Interactive Butterfly teaches users about the butterfly's life cycle, anatomy, and characteristics as well as their life in the Dancing Wings Butterfly Garden. Through the use of the design programs Adobe Illustrator, Flash, and After Effects; the programming language ActionScript3.0; a child-friendly user interface and design; audio elements and user takeaways, Flutter-by Interactive Butterfly appeals to children of all ages, interests, and learning styles. The project can be viewed at lydiapowers.com/Thesis/FlutterByButterfly.html

  11. THE VALUE OF CLASS-IC ANTIARRHYTHMIC DRUGS FOR ACUTE CONVERSION OF PAROXYSMAL ATRIAL-FIBRILLATION OR FLUTTER TO SINUS RHYTHM

    NARCIS (Netherlands)

    SUTTORP, MJ; KINGMA, JH; JESSURUN, ER; LIEAHUEN, L; VANHEMEL, NM; LIE, KI

    1990-01-01

    In a single-blind randomized study, the efficacy and safety of intravenous propafenone (2 mg/kg body weight per 10 min) versus flecainide (2 mg/kg per 10 min) were assessed in 50 patients with atrial fibrillation or flutter. Treatment was considered successful if sinus rhythm occurred within 1 h.

  12. Innovation of the experimental facility for the study of flutter in the Institute of Thermomechanics AS CR and some results obtained from initial experiments

    Czech Academy of Sciences Publication Activity Database

    Vlček, Václav; Štěpán, M.; Zolotarev, Igor; Kozánek, Jan

    2016-01-01

    Roč. 821, č. 2016 (2016), s. 144-151 ISSN 1660-9336 R&D Projects: GA ČR GA13-10527S Institutional support: RVO:61388998 Keywords : aeroelasticity * flutter * interferometry * subsonic flow Subject RIV: BI - Acoustics

  13. Panel discussion: Nuclear cardiology

    International Nuclear Information System (INIS)

    Schwaiger, M.

    1991-01-01

    The panel discussion opened with a question concerning whether true quantification of myocardial sympathetic presynaptic function or receptor density can be obtained with currently available radiopharmaceuticals. What are the relative advantages of the two general approaches that have been proposed for quantification: (1) The assessment of tracer distribution volume in tissue following bolus injection and (2) quantification based on tracer displacement kinetics following administration of excess unlabeled tracer. It was pointed out that tracer kinetics for the delineation of presynaptic and postsynaptic binding sites by radiopharmaceuticals or radiolabeled receptor antagonists are rather complex, reflecting several physiologic processes that are difficult to separate. Several approaches were examined. The possibility of regional definition of receptor density by PET was questioned and it was noted that regions of interest can be applied to calculate regional receptor kinetics. However, due to the limited spatial resolution of PET, only average transmural values can be determined. The discussion then turned to the discrepancy between the known sparse parasympathetic innervation of the heart and the high density of muscarinic receptors observed with PET. Experiences with MIBG imaging were reported, including uptake in the transplanted heart and interaction of drugs with MIBG uptake

  14. On Poisson Nonlinear Transformations

    Directory of Open Access Journals (Sweden)

    Nasir Ganikhodjaev

    2014-01-01

    Full Text Available We construct the family of Poisson nonlinear transformations defined on the countable sample space of nonnegative integers and investigate their trajectory behavior. We have proved that these nonlinear transformations are regular.

  15. Creation and Implementation of an Outpatient Pathway for Atrial Fibrillation in the Emergency Department Setting: Results of an Expert Panel.

    Science.gov (United States)

    Baugh, Christopher W; Clark, Carol L; Wilson, Jason W; Stiell, Ian G; Kocheril, Abraham G; Luck, Krista K; Myers, Troy D; Pollack, Charles V; Roumpf, Steven K; Tomassoni, Gery F; Williams, James M; Patel, Brian B; Wu, Fred; Pines, Jesse M

    2018-03-10

    Atrial fibrillation and flutter (AF) is a common condition among emergency department (ED) patients in the United States. Traditionally, ED care for primary complaints related to AF focus on rate control, and patients are often admitted to an inpatient setting for further care. Inpatient care may include further telemetry monitoring and diagnostic testing, rhythm control, a search for identification of AF etiology, and stroke prophylaxis. However, many patients are eligible for safe and effective outpatient management pathways. They are widely used in Canada and other countries but less widely adopted in the United States. In this project, we convened an expert panel to create a practical framework for the process of creating, implementing, and maintaining an outpatient AF pathway for emergency physicians to assess and treat AF patients, safely reduce hospitalization rates, ensure appropriate stroke prophylaxis, and effectively transition patients to longitudinal outpatient treatment settings from the ED and/or observation unit. To support local pathway creation, the panel also reached agreement on a protocol development plan, a sample pathway, consensus recommendations for pathway components, sample pathway metrics, and a structured literature review framework using a modified Delphi technique by a technical expert panel of emergency medicine, cardiology, and other stakeholder groups. © 2018 by the Society for Academic Emergency Medicine.

  16. Development of non-linear TWB parts

    Energy Technology Data Exchange (ETDEWEB)

    Lee, J.; Yoon, C.S.; Lim, J.D. [Hyundai Motor Company and Kia Motors Corp. (Korea). Advanced Technology Center; Park, H.C. [Hyundai Hysco (Korea). Technical Research Lab.

    2005-07-01

    New manufacturing methods have applied for automotive parts to reduce total weight of car, resulting in improvement of fuel efficiency. TWB technique is applied to auto body parts, especially door inner, side inner and outer panel, and center floor panel to accomplish this goal. We applied non-linear (circular welded) TWB to shock absorber housing (to reduce total weight of shock absorber housing assembly). Welding line and shape of blank were determined by FEM analysis. High formability steel sheet and 440MPa grade high strength steel sheet were laser welded and press formed to final shock absorber housing (S/ABS HSG) panel and assembled with other sub parts. As a result, more than 10% of total weight of shock absorber housing assembly could be reduced compared with the mass of same part manufactured by conventional method. Also circular welding technique made it possible to design optimum welding line of TWB part. This paper is about result of FEM analysis and development procedure of non-linear TWB part (shock absorber housing assembly). (orig.)

  17. An Improved Nonlinear Five-Point Model for Photovoltaic Modules

    Directory of Open Access Journals (Sweden)

    Sakaros Bogning Dongue

    2013-01-01

    Full Text Available This paper presents an improved nonlinear five-point model capable of analytically describing the electrical behaviors of a photovoltaic module for each generic operating condition of temperature and solar irradiance. The models used to replicate the electrical behaviors of operating PV modules are usually based on some simplified assumptions which provide convenient mathematical model which can be used in conventional simulation tools. Unfortunately, these assumptions cause some inaccuracies, and hence unrealistic economic returns are predicted. As an alternative, we used the advantages of a nonlinear analytical five-point model to take into account the nonideal diode effects and nonlinear effects generally ignored, which PV modules operation depends on. To verify the capability of our method to fit PV panel characteristics, the procedure was tested on three different panels. Results were compared with the data issued by manufacturers and with the results obtained using the five-parameter model proposed by other authors.

  18. 1994 Panel 1 Utilization Plan

    International Nuclear Information System (INIS)

    1994-01-01

    The Waste Isolation Pilot Plant (WIPP) is intended to receive, handle, and permanently dispose of transuranic (TRU) waste. To fulfill this mission, the U.S. Department of Energy (DOE) constructed a full-scale facility to demonstrate both technical and operational principles of the permanent isolation of TRU waste. The WIPP consists of surface and underground facilities. Panel 1 is situated in the underground facility horizon which is located approximately 2,150 feet below the surface in the predominantly halite Salado Formation. The Panel 1 Utilization Plan provides a strategy for the optimum use of Panel 1 which is consistent with the priorities established by the DOE to accomplish the WIPP mission. These priorities, which include maintaining personnel safety, conducting performance assessment, and continued operational enhancements, are the guiding premise for the decisions on the planned usage of the WIPP underground facility. The continuation of ongoing investigations along with the planned testing and training to be carried out in Panel 1 will enhance the current knowledge and understanding of the operational and geotechnical aspects of the panel configuration. This enhancement will ultimately lead to safer, more efficient, and more cost-effective methods of operation. Excavation of the waste storage area began in May 1986 with the mining of entries to Panel 1. The original design for the waste storage rooms at the WIPP provided a limited period of time during which to mine the openings and to emplace waste. Each panel, consisting of seven storage rooms, was scheduled to be mined and filled in less than 5 years. Panel 1 was developed to receive waste for a demonstration phase that was scheduled to start in October 1988. The demonstration phase was deferred, and the experimental test program was modified to use contact-handled (CH) transuranic waste in bin-scale tests, planned for Room 1, Panel 1

  19. Advances in nonlinear optics

    CERN Document Server

    Chen, Xianfeng; Zeng, Heping; Guo, Qi; She, Weilong

    2015-01-01

    This book presents an overview of the state of the art of nonlinear optics from weak light nonlinear optics, ultrafast nonlinear optics to electro-optical theory and applications. Topics range from the fundamental studies of the interaction between matter and radiation to the development of devices, components, and systems of tremendous commercial interest for widespread applications in optical telecommunications, medicine, and biotechnology.

  20. Thermal Analysis of Solar Panels

    Science.gov (United States)

    Barth, Nicolas; de Correia, João Pedro Magalhães; Ahzi, Saïd; Khaleel, Mohammad Ahmed

    In this work, we propose to analyze the thermal behavior of PV panels using finite element simulations (FEM). We applied this analysis to compute the temperature distribution in a PV panel BP 350 subjected to different atmospheric conditions. This analysis takes into account existing formulations in the literature and, based on NOCT conditions, meteorological data was used to validate our approach for different wind speed and solar irradiance. The electrical performance of the PV panel was also studied. The proposed 2D FEM analysis is applied to different region's climates and was also used to consider the role of thermal inertia on the optimization of the PV device efficiency.

  1. Nonlinear damage detection in composite structures using bispectral analysis

    Science.gov (United States)

    Ciampa, Francesco; Pickering, Simon; Scarselli, Gennaro; Meo, Michele

    2014-03-01

    Literature offers a quantitative number of diagnostic methods that can continuously provide detailed information of the material defects and damages in aerospace and civil engineering applications. Indeed, low velocity impact damages can considerably degrade the integrity of structural components and, if not detected, they can result in catastrophic failure conditions. This paper presents a nonlinear Structural Health Monitoring (SHM) method, based on ultrasonic guided waves (GW), for the detection of the nonlinear signature in a damaged composite structure. The proposed technique, based on a bispectral analysis of ultrasonic input waveforms, allows for the evaluation of the nonlinear response due to the presence of cracks and delaminations. Indeed, such a methodology was used to characterize the nonlinear behaviour of the structure, by exploiting the frequency mixing of the original waveform acquired from a sparse array of sensors. The robustness of bispectral analysis was experimentally demonstrated on a damaged carbon fibre reinforce plastic (CFRP) composite panel, and the nonlinear source was retrieved with a high level of accuracy. Unlike other linear and nonlinear ultrasonic methods for damage detection, this methodology does not require any baseline with the undamaged structure for the evaluation of the nonlinear source, nor a priori knowledge of the mechanical properties of the specimen. Moreover, bispectral analysis can be considered as a nonlinear elastic wave spectroscopy (NEWS) technique for materials showing either classical or non-classical nonlinear behaviour.

  2. Aeroelastic oscillations of a cantilever with structural nonlinearities: theory and numerical simulation.

    Energy Technology Data Exchange (ETDEWEB)

    Robinson, Brandon [Carleton Univ., Ottawa, ON (Canada). Dept. of Civil and Environmental Engineering; Rocha da Costa, Leandro Jose [Carleton Univ., Ottawa, ON (Canada). Dept. of Civil and Environmental Engineering; Poirel, Dominique [Royal Military College of Canada, Kingston (Canada). Dept. of Mechanical and Aerospace Engineering; Pettit, Chris [US Naval Academy, Annapolis, MD (United States). Dept. of Mechanical and Aerospace Engineering; Khalil, Mohammad [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Sarkar, Abhijit [Carleton Univ., Ottawa, ON (Canada). Dept. of Civil and Environmental Engineering

    2017-09-01

    Our study details the derivation of the nonlinear equations of motion for the axial, biaxial bending and torsional vibrations of an aeroelastic cantilever undergoing rigid body (pitch) rotation at the base. The primary attenstion is focussed on the geometric nonlinearities of the system, whereby the aeroelastic load is modeled by the theory of linear quasisteady aerodynamics. This modelling effort is intended to mimic the wind-tunnel experimental setup at the Royal Military College of Canada. While the derivation closely follows the work of Hodges and Dowell [1] for rotor blades, this aeroelastic system contains new inertial terms which stem from the fundamentally different kinematics than those exhibited by helicopter or wind turbine blades. Using the Hamilton’s principle, a set of coupled nonlinear partial differential equations (PDEs) and an ordinary differential equation (ODE) are derived which describes the coupled axial-bending-bending-torsion-pitch motion of the aeroelastic cantilever with the pitch rotation. The finite dimensional approximation of the coupled system of PDEs are obtained using the Galerkin projection, leading to a coupled system of ODEs. Subsequently, these nonlinear ODEs are solved numerically using the built-in MATLAB implicit ODE solver and the associated numerical results are compared with those obtained using Houbolt’s method. It is demonstrated that the system undergoes coalescence flutter, leading to a limit cycle oscillation (LCO) due to coupling between the rigid body pitching mode and teh flexible mode arising from the flapwise bending motion.

  3. Quantum Nonlinear Optics

    CERN Document Server

    Hanamura, Eiichi; Yamanaka, Akio

    2007-01-01

    This graduate-level textbook gives an introductory overview of the fundamentals of quantum nonlinear optics. Based on the quantum theory of radiation, Quantum Nonlinear Optics incorporates the exciting developments in novel nonlinear responses of materials (plus laser oscillation and superradiance) developed over the past decade. It deals with the organization of radiation field, interaction between electronic system and radiation field, statistics of light, mutual manipulation of light and matter, laser oscillation, dynamics of light, nonlinear optical response, and nonlinear spectroscopy, as well as ultrashort and ultrastrong laser pulse. Also considered are Q-switching, mode locking and pulse compression. Experimental and theoretical aspects are intertwined throughout.

  4. Nonlinear dynamics and complexity

    CERN Document Server

    Luo, Albert; Fu, Xilin

    2014-01-01

    This important collection presents recent advances in nonlinear dynamics including analytical solutions, chaos in Hamiltonian systems, time-delay, uncertainty, and bio-network dynamics. Nonlinear Dynamics and Complexity equips readers to appreciate this increasingly main-stream approach to understanding complex phenomena in nonlinear systems as they are examined in a broad array of disciplines. The book facilitates a better understanding of the mechanisms and phenomena in nonlinear dynamics and develops the corresponding mathematical theory to apply nonlinear design to practical engineering.

  5. Exascale Workshop Panel Report Meeting

    Energy Technology Data Exchange (ETDEWEB)

    Khaleel, Mohammad A.

    2010-07-01

    The Exascale Review Panel consists of 12 scientists and engineers with experience in various aspects of high-performance computing and its application, development, and management. The Panel hear presentations by several representatives of the workshops and town meetings convened over the past few years to examine the need for exascale computation capability and the justification for a U.S. Department of Energy (DOE) program to develop such capability. This report summarizes information provided by the presenters and substantial written reports to the Panel in advance of the meeting in Washington D.C. on January 19-20, 2010. The report also summarizes the Panel's conclusions with regard to the justification of a DOE-led exascale initiative.

  6. Generalized Dynamic Panel Data Models with Random Effects for Cross-Section and Time

    NARCIS (Netherlands)

    Mesters, G.; Koopman, S.J.

    2014-01-01

    An exact maximum likelihood method is developed for the estimation of parameters in a nonlinear non-Gaussian dynamic panel data model with unobserved random individual-specific and time-varying effects. We propose an estimation procedure based on the importance sampling technique. In particular, a

  7. Distributed nonlinear optical response

    DEFF Research Database (Denmark)

    Nikolov, Nikola Ivanov

    2005-01-01

    of bound states of out of phase bright solitons and dark solitons. Also, the newly introduced analogy between the nonlocal cubic nonlinear and the quadratic nonlinear media, presented in paper B and Chapter 3 is discussed. In particular it supplies intuitive physical meaning of the formation of solitons...... in quadratic nonlinear media. In the second part of the report (Chapter 4), the possibility to obtain light with ultrabroad spectrum due to the interplay of many nonlinear effects based on cubic nonlinearity is investigated thoroughly. The contribution of stimulated Raman scattering, a delayed nonlinear...... a modified nonlinear Schroedinger model equation. Chapter 4 and papers D and E are dedicated to this part of the research....

  8. Analysis Of Dynamic Dent Resistance Of Auto Body Panel

    International Nuclear Information System (INIS)

    Deolgaonkar, S. S.; Nandedkar, V. M.

    2007-01-01

    In automotive industry there is increasing demand for higher quality exterior panels, better functional properties and lower weight. The demand for weight reduction has led to thinner sheets, greater use of high strength steels and a change from steel to aluminum grades. This thickness reduction, which causes decrease in the dent resistance, promoted examination of the dent resistance against static and dynamic concentrated loads. This paper describes an investigation of the suitability of explicit dynamic FE analysis as a mean to determine the dynamic dent properties of the panel. This investigation is carried out on the body panel of utility vehicle and covers two parts, in first experimental analysis is carried out on developed test rig, which is interfaced with the computer. This test rig measures deflection with accuracy of .001mm. The experimental results are then compared with the simulation results, which is the second part. Simulation is carried with non-linear transient dynamic explicit analysis using Ansys -Ls Dyna. The experimental results show great accuracy with simulation results. The effect of change in thickness and geometry of the existing fender is then studied with help of simulation technique. By considering the best possible option overall weight of fender is reduced by 7.07 % by keeping the dent resistance of the panel constant

  9. Analysis of 3-panel and 4-panel microscale ionization sources

    International Nuclear Information System (INIS)

    Natarajan, Srividya; Parker, Charles B.; Glass, Jeffrey T.; Piascik, Jeffrey R.; Gilchrist, Kristin H.; Stoner, Brian R.

    2010-01-01

    Two designs of a microscale electron ionization (EI) source are analyzed herein: a 3-panel design and a 4-panel design. Devices were fabricated using microelectromechanical systems technology. Field emission from carbon nanotube provided the electrons for the EI source. Ion currents were measured for helium, nitrogen, and xenon at pressures ranging from 10 -4 to 0.1 Torr. A comparison of the performance of both designs is presented. The 4-panel microion source showed a 10x improvement in performance compared to the 3-panel device. An analysis of the various factors affecting the performance of the microion sources is also presented. SIMION, an electron and ion optics software, was coupled with experimental measurements to analyze the ion current results. The electron current contributing to ionization and the ion collection efficiency are believed to be the primary factors responsible for the higher efficiency of the 4-panel microion source. Other improvements in device design that could lead to higher ion source efficiency in the future are also discussed. These microscale ion sources are expected to find application as stand alone ion sources as well as in miniature mass spectrometers.

  10. The Efficiency of Split Panel Designs in an Analysis of Variance Model

    Science.gov (United States)

    Wang, Wei-Guo; Liu, Hai-Jun

    2016-01-01

    We consider split panel design efficiency in analysis of variance models, that is, the determination of the cross-sections series optimal proportion in all samples, to minimize parametric best linear unbiased estimators of linear combination variances. An orthogonal matrix is constructed to obtain manageable expression of variances. On this basis, we derive a theorem for analyzing split panel design efficiency irrespective of interest and budget parameters. Additionally, relative estimator efficiency based on the split panel to an estimator based on a pure panel or a pure cross-section is present. The analysis shows that the gains from split panel can be quite substantial. We further consider the efficiency of split panel design, given a budget, and transform it to a constrained nonlinear integer programming. Specifically, an efficient algorithm is designed to solve the constrained nonlinear integer programming. Moreover, we combine one at time designs and factorial designs to illustrate the algorithm’s efficiency with an empirical example concerning monthly consumer expenditure on food in 1985, in the Netherlands, and the efficient ranges of the algorithm parameters are given to ensure a good solution. PMID:27163447

  11. Analysis and Tests of Reinforced Carbon-Epoxy/Foam-Core Sandwich Panels with Cutouts

    Science.gov (United States)

    Baker, Donald J.; Rogers, Charles

    1996-01-01

    The results of a study of a low-cost structurally efficient minimum-gage shear-panel design that can be used in light helicopters are presented. The shear-panel design is based on an integrally stiffened syntactic-foam stabilized-skin with an all-bias-ply tape construction for stabilized-skin concept with an all-bias-ply tape construction for the skins. This sandwich concept is an economical way to increase the panel bending stiffness weight penalty. The panels considered in the study were designed to be buckling resistant up to 100 lbs/in. of shear load and to have an ultimate strength of 300 lbs/in. The panel concept uses unidirectional carbon-epoxy tape on a syntactic adhesive as a stiffener that is co-cured with the skin and is an effective concept for improving panel buckling strength. The panel concept also uses pultruded carbon-epoxy rods embedded in a syntactic adhesive and over-wrapped with a bias-ply carbon-epoxy tape to form a reinforcing beam which is an effective method for redistributing load around rectangular cutout. The buckling strength of the reinforced panels is 83 to 90 percent of the predicted buckling strength based on a linear buckling analysis. The maximum experimental deflection exceeds the maximum deflection predicted by a nonlinear analysis by approximately one panel thickness. The failure strength of the reinforced panels was two and a half to seven times of the buckling strength. This efficient shear-panel design concept exceeds the required ultimate strength requirement of 300 lbs/in by more than 100 percent.

  12. High temperature structural sandwich panels

    Science.gov (United States)

    Papakonstantinou, Christos G.

    High strength composites are being used for making lightweight structural panels that are being employed in aerospace, naval and automotive structures. Recently, there is renewed interest in use of these panels. The major problem of most commercial available sandwich panels is the fire resistance. A recently developed inorganic matrix is investigated for use in cases where fire and high temperature resistance are necessary. The focus of this dissertation is the development of a fireproof composite structural system. Sandwich panels made with polysialate matrices have an excellent potential for use in applications where exposure to high temperatures or fire is a concern. Commercial available sandwich panels will soften and lose nearly all of their compressive strength temperatures lower than 400°C. This dissertation consists of the state of the art, the experimental investigation and the analytical modeling. The state of the art covers the performance of existing high temperature composites, sandwich panels and reinforced concrete beams strengthened with Fiber Reinforced Polymers (FRP). The experimental part consists of four major components: (i) Development of a fireproof syntactic foam with maximum specific strength, (ii) Development of a lightweight syntactic foam based on polystyrene spheres, (iii) Development of the composite system for the skins. The variables are the skin thickness, modulus of elasticity of skin and high temperature resistance, and (iv) Experimental evaluation of the flexural behavior of sandwich panels. Analytical modeling consists of a model for the flexural behavior of lightweight sandwich panels, and a model for deflection calculations of reinforced concrete beams strengthened with FRP subjected to fatigue loading. The experimental and analytical results show that sandwich panels made with polysialate matrices and ceramic spheres do not lose their load bearing capability during severe fire exposure, where temperatures reach several

  13. Nonlinear Dirac Equations

    Directory of Open Access Journals (Sweden)

    Wei Khim Ng

    2009-02-01

    Full Text Available We construct nonlinear extensions of Dirac's relativistic electron equation that preserve its other desirable properties such as locality, separability, conservation of probability and Poincaré invariance. We determine the constraints that the nonlinear term must obey and classify the resultant non-polynomial nonlinearities in a double expansion in the degree of nonlinearity and number of derivatives. We give explicit examples of such nonlinear equations, studying their discrete symmetries and other properties. Motivated by some previously suggested applications we then consider nonlinear terms that simultaneously violate Lorentz covariance and again study various explicit examples. We contrast our equations and construction procedure with others in the literature and also show that our equations are not gauge equivalent to the linear Dirac equation. Finally we outline various physical applications for these equations.

  14. Nonlinear graphene plasmonics

    Science.gov (United States)

    Ooi, Kelvin J. A.; Tan, Dawn T. H.

    2017-10-01

    The rapid development of graphene has opened up exciting new fields in graphene plasmonics and nonlinear optics. Graphene's unique two-dimensional band structure provides extraordinary linear and nonlinear optical properties, which have led to extreme optical confinement in graphene plasmonics and ultrahigh nonlinear optical coefficients, respectively. The synergy between graphene's linear and nonlinear optical properties gave rise to nonlinear graphene plasmonics, which greatly augments graphene-based nonlinear device performance beyond a billion-fold. This nascent field of research will eventually find far-reaching revolutionary technological applications that require device miniaturization, low power consumption and a broad range of operating wavelengths approaching the far-infrared, such as optical computing, medical instrumentation and security applications.

  15. Stationary nonlinear Airy beams

    International Nuclear Information System (INIS)

    Lotti, A.; Faccio, D.; Couairon, A.; Papazoglou, D. G.; Panagiotopoulos, P.; Tzortzakis, S.; Abdollahpour, D.

    2011-01-01

    We demonstrate the existence of an additional class of stationary accelerating Airy wave forms that exist in the presence of third-order (Kerr) nonlinearity and nonlinear losses. Numerical simulations and experiments, in agreement with the analytical model, highlight how these stationary solutions sustain the nonlinear evolution of Airy beams. The generic nature of the Airy solution allows extension of these results to other settings, and a variety of applications are suggested.

  16. Generalized Nonlinear Yule Models

    OpenAIRE

    Lansky, Petr; Polito, Federico; Sacerdote, Laura

    2016-01-01

    With the aim of considering models with persistent memory we propose a fractional nonlinear modification of the classical Yule model often studied in the context of macrovolution. Here the model is analyzed and interpreted in the framework of the development of networks such as the World Wide Web. Nonlinearity is introduced by replacing the linear birth process governing the growth of the in-links of each specific webpage with a fractional nonlinear birth process with completely general birth...

  17. Nonlinear evolution equations

    CERN Document Server

    Uraltseva, N N

    1995-01-01

    This collection focuses on nonlinear problems in partial differential equations. Most of the papers are based on lectures presented at the seminar on partial differential equations and mathematical physics at St. Petersburg University. Among the topics explored are the existence and properties of solutions of various classes of nonlinear evolution equations, nonlinear imbedding theorems, bifurcations of solutions, and equations of mathematical physics (Navier-Stokes type equations and the nonlinear Schrödinger equation). The book will be useful to researchers and graduate students working in p

  18. Nonlinear Physics of Plasmas

    CERN Document Server

    Kono, Mitsuo

    2010-01-01

    A nonlinearity is one of the most important notions in modern physics. A plasma is rich in nonlinearities and provides a variety of behaviors inherent to instabilities, coherent wave structures and turbulence. The book covers the basic concepts and mathematical methods, necessary to comprehend nonlinear problems widely encountered in contemporary plasmas, but also in other fields of physics and current research on self-organized structures and magnetized plasma turbulence. The analyses make use of strongly nonlinear models solved by analytical techniques backed by extensive simulations and available experiments. The text is written for senior undergraduates, graduate students, lecturers and researchers in laboratory, space and fusion plasmas.

  19. Nonlinear optics at interfaces

    International Nuclear Information System (INIS)

    Chen, C.K.

    1980-12-01

    Two aspects of surface nonlinear optics are explored in this thesis. The first part is a theoretical and experimental study of nonlinear intraction of surface plasmons and bulk photons at metal-dielectric interfaces. The second part is a demonstration and study of surface enhanced second harmonic generation at rough metal surfaces. A general formulation for nonlinear interaction of surface plasmons at metal-dielectric interfaces is presented and applied to both second and third order nonlinear processes. Experimental results for coherent second and third harmonic generation by surface plasmons and surface coherent antiStokes Raman spectroscopy (CARS) are shown to be in good agreement with the theory

  20. Nonlinear drift tearing mode

    International Nuclear Information System (INIS)

    Zelenyj, L.M.; Kuznetsova, M.M.

    1989-01-01

    Nonlinear study of magnetic perturbation development under single-mode conditions in collision-free plasma in configurations with the magnetic field shear is investigated. Results are obtained with regard of transverse component of electrical field and its effect on ion dynamics within wide range of ion Larmor radius value and values of magnetic field shear. Increments of nonlinear drift tearing mode are obtained and it is shown that excitation drastic conditions of even linearly stable modes are possible. Mechanism of instability nonlinear stabilization is considered and the value of magnetic island at the saturation threshold is estimeted. Energy of nonlinear drift tearing mode is discussed

  1. Solar Panel based Milk Pasteurization

    DEFF Research Database (Denmark)

    Nielsen, Kirsten Mølgaard; Pedersen, Tom Søndergaard

    This paper treats the subject of analysis, design and development of the control system for a solar panel based milk pasteurization system to be used in small villages in Tanzania. The analysis deals with the demands for an acceptable pasteurization, the varying energy supply and the low cost, low...... complexity, simple user interface and high reliability demands. Based on these demands a concept for the pasteurization system is established and a control system is developed. A solar panel has been constructed and the energy absorption has been tested in Tanzania. Based on the test, the pasteurization...... system is dimensioned. A functional prototype of the pasteurization facility with a capacity of 200 l milk/hour has been developed and tested. The system is prepared for solar panels as the main energy source and is ready for a test in Tanzania....

  2. Solar Panel based Milk Pasteurization

    DEFF Research Database (Denmark)

    Nielsen, Kirsten Mølgaard; Pedersen, Tom Søndergaard

    2002-01-01

    This paper treats the subject of analysis, design and development of the control system for a solar panel based milk pasteurization system to be used in small villages in Tanzania. The analysis deals with the demands for an acceptable pasteurization, the varying energy supply and the low cost, low...... complexity, simple user interface and high reliability demands. Based on these demands a concept for the pasteurization system is established and a control system is developed. A solar panel has been constructed and the energy absorption has been tested in Tanzania. Based on the test, the pasteurization...... system is dimensioned. A functional prototype of the pasteurization facility with a capacity of 200 l milk/hour has been developed and tested. The system is prepared for solar panels as the main energy source and is ready for a test in Tanzania....

  3. Ultimate uniaxial compressive strength of stiffened panel with opening under lateral pressure

    Directory of Open Access Journals (Sweden)

    Chang-Li Yu

    2015-03-01

    Full Text Available This paper concentrated on the ultimate uniaxial compressive strength of stiffened panel with opening under lateral load and also studied the design-oriented formulae. For this purpose, three series of well executed experiments on longitudinal stiffened panel with rectangular opening subjected to the combined load have been selected as test models. The finite element analysis package, ABAQUS, is used for simulation with considering the large elasticplastic deflection behavior of stiffened panels. The feasibility of the numerical procedure is verified by a good agreement of experimental results and numerical results. More cases studies are executed employing nonlinear finite element method to analyze the influence of design variables on the ultimate strength of stiffened panel with opening under combined pressure. Based on data, two design formulae corresponding to different opening types are fitted, and accuracy of them is illustrated to demonstrate that they could be applied to basic design of practical engineering structure.

  4. Polarization Nonlinear Optics of Quadratically Nonlinear Azopolymers

    International Nuclear Information System (INIS)

    Konorov, S.O.; Akimov, D.A.; Ivanov, A.A.; Petrov, A.N.; Alfimov, M.V.; Yakimanskii, A.V.; Smirnov, N.N.; Ivanova, V.N.; Kudryavtsev, V.V.; Podshivalov, A.A.; Sokolova, I.M.; Zheltikov, A.M.

    2005-01-01

    The polarization properties of second harmonic and sum-frequency signals generated by femtosecond laser pulses in films of polymers containing covalent groups of an azobenzothiazole chromophore polarized by an external electric field are investigated. It is shown that the methods of polarization nonlinear optics make it possible to determine the structure of oriented molecular dipoles and reveal important properties of the motion of collectivized πelectrons in organic molecules with strong optical nonlinearities. The polarization measurements show that the tensor of quadratic nonlinear optical susceptibility of chromophore fragments oriented by an external field in macromolecules of the noted azopolymers has a degenerate form. This is indicative of a predominantly one-dimensional character of motion of collectivized π electrons along an extended group of atoms in such molecules

  5. Finite element modeling of tornado missile impact on reinforced concrete wall panels

    International Nuclear Information System (INIS)

    Zhang, Y.; Vallabhan, C.V.G.; McDonald, J.R.

    1993-01-01

    This paper describes a finite element model for the impact of large tornado-generated missiles with reinforced concrete wall panels. The analysis predicts the dynamic response of a wall panel when impacted by a missile with a large contact area such as an automobile. Quadratic finite elements are used to discretize the domain of the wall panel. Fundamental assumptions are based on the Mindlin and the related Reinsser plate theories. An 'embedded' model is employed to account for the reinforcing bars. The nonlinear behavior of concrete and steel bars are analyzed by means of time-dependent constitutive relationships. A model is proposed to describe the initial and subsequent yield surfaces of concrete material, which avoids underestimation of the effect of high hydrostatic stresses on the yielding behavior of concrete. Ottosen's four-parameter failure criterion is used to define the failure surface of concrete. A crack monitoring algorithm accounts for post-cracking and post-crushing behavior of concrete. Explicit time step integration of nonlinear dynamic equations are carried out using the finite element discretization of a concrete wall panel. As a practical application of the analysis technique, the contact failure pressure for a particular panel geometry can be calculated. The contact failure pressure and the elapsed time to failure after missile contact define a rectangular or triangular impulse loading to produce failure of the panel. Since automobile crashes are known to produce triangular impulse loads, the two pulses (failure and impact) can be compared to determine if a particular impact will fail the panels. Thus, a particular concrete panel can be analyzed to determine if it will fail under a postulated missile impact

  6. Solar panel truss mounting systems and methods

    Energy Technology Data Exchange (ETDEWEB)

    Al-Haddad, Tristan Farris; Cavieres, Andres; Gentry, Russell; Goodman, Joseph; Nolan, Wade; Pitelka, Taylor; Rahimzadeh, Keyan; Brooks, Bradley; Lohr, Joshua; Crooks, Ryan; Porges, Jamie; Rubin, Daniel

    2016-06-28

    An exemplary embodiment of the present invention provides a solar panel truss mounting system comprising a base and a truss assembly coupled to the base. The truss assembly comprises a first panel rail mount, second panel rail mount parallel to the first panel rail mount, base rail mount parallel to the first and second panel rail mounts, and a plurality of support members. A first portion of the plurality of support members extends between the first and second panel rail mounts. A second portion of the plurality of support members extends between the first panel rail mount and the base rail mount. A third portion of the plurality of support members extends between the second panel rail mount and the base rail mount. The system can further comprise a plurality of connectors for coupling a plurality of photovoltaic solar panels to the truss assembly.

  7. Solar panel truss mounting systems and methods

    Energy Technology Data Exchange (ETDEWEB)

    Al-Haddad, Tristan Farris; Cavieres, Andres; Gentry, Russell; Goodman, Joseph; Nolan, Wade; Pitelka, Taylor; Rahimzadeh, Keyan; Brooks, Bradley; Lohr, Joshua; Crooks, Ryan; Porges, Jamie; Rubin, Daniel

    2018-01-30

    An exemplary embodiment of the present invention provides a solar panel truss mounting system comprising a base and a truss assembly coupled to the base. The truss assembly comprises a first panel rail mount, second panel rail mount parallel to the first panel rail mount, base rail mount parallel to the first and second panel rail mounts, and a plurality of support members. A first portion of the plurality of support members extends between the first and second panel rail mounts. A second portion of the plurality of support members extends between the first panel rail mount and the base rail mount. A third portion of the plurality of support members extends between the second panel rail mount and the base rail mount. The system can further comprise a plurality of connectors for coupling a plurality of photovoltaic solar panels to the truss assembly.

  8. Solar panel truss mounting systems and methods

    Science.gov (United States)

    Al-Haddad, Tristan Farris; Cavieres, Andres; Gentry, Russell; Goodman, Joseph; Nolan, Wade; Pitelka, Taylor; Rahimzadeh, Keyan; Brooks, Bradley; Lohr, Joshua; Crooks, Ryan; Porges, Jamie; Rubin, Daniel

    2015-10-20

    An exemplary embodiment of the present invention provides a solar panel truss mounting system comprising a base and a truss assembly coupled to the base. The truss assembly comprises a first panel rail mount, second panel rail mount parallel to the first panel rail mount, base rail mount parallel to the first and second panel rail mounts, and a plurality of support members. A first portion of the plurality of support members extends between the first and second panel rail mounts. A second portion of the plurality of support members extends between the first panel rail mount and the base rail mount. A third portion of the plurality of support members extends between the second panel rail mount and the base rail mount. The system can further comprise a plurality of connectors for coupling a plurality of photovoltaic solar panels to the truss assembly.

  9. Nonlinear dynamics in Nuclotron

    International Nuclear Information System (INIS)

    Dinev, D.

    1997-01-01

    The paper represents an extensive study of the nonlinear beam dynamics in the Nuclotron. Chromatic effects, including the dependence of the betatron tunes on the amplitude, and chromatic perturbations have been investigated taking into account the measured field imperfections. Beam distortion, smear, dynamic aperture and nonlinear acceptance have been calculated for different particle energies and betatron tunes

  10. Nonlinear Optics and Applications

    Science.gov (United States)

    Abdeldayem, Hossin A. (Editor); Frazier, Donald O. (Editor)

    2007-01-01

    Nonlinear optics is the result of laser beam interaction with materials and started with the advent of lasers in the early 1960s. The field is growing daily and plays a major role in emerging photonic technology. Nonlinear optics play a major role in many of the optical applications such as optical signal processing, optical computers, ultrafast switches, ultra-short pulsed lasers, sensors, laser amplifiers, and many others. This special review volume on Nonlinear Optics and Applications is intended for those who want to be aware of the most recent technology. This book presents a survey of the recent advances of nonlinear optical applications. Emphasis will be on novel devices and materials, switching technology, optical computing, and important experimental results. Recent developments in topics which are of historical interest to researchers, and in the same time of potential use in the fields of all-optical communication and computing technologies, are also included. Additionally, a few new related topics which might provoke discussion are presented. The book includes chapters on nonlinear optics and applications; the nonlinear Schrodinger and associated equations that model spatio-temporal propagation; the supercontinuum light source; wideband ultrashort pulse fiber laser sources; lattice fabrication as well as their linear and nonlinear light guiding properties; the second-order EO effect (Pockels), the third-order (Kerr) and thermo-optical effects in optical waveguides and their applications in optical communication; and, the effect of magnetic field and its role in nonlinear optics, among other chapters.

  11. Nonlinear optical systems

    CERN Document Server

    Lugiato, Luigi; Brambilla, Massimo

    2015-01-01

    Guiding graduate students and researchers through the complex world of laser physics and nonlinear optics, this book provides an in-depth exploration of the dynamics of lasers and other relevant optical systems, under the umbrella of a unitary spatio-temporal vision. Adopting a balanced approach, the book covers traditional as well as special topics in laser physics, quantum electronics and nonlinear optics, treating them from the viewpoint of nonlinear dynamical systems. These include laser emission, frequency generation, solitons, optically bistable systems, pulsations and chaos and optical pattern formation. It also provides a coherent and up-to-date treatment of the hierarchy of nonlinear optical models and of the rich variety of phenomena they describe, helping readers to understand the limits of validity of each model and the connections among the phenomena. It is ideal for graduate students and researchers in nonlinear optics, quantum electronics, laser physics and photonics.

  12. Mobile response in web panels

    NARCIS (Netherlands)

    de Bruijne, M.A.; Wijnant, A.

    2014-01-01

    This article investigates unintended mobile access to surveys in online, probability-based panels. We find that spontaneous tablet usage is drastically increasing in web surveys, while smartphone usage remains low. Further, we analyze the bias of respondent profiles using smartphones and tablets

  13. Keuringspanele ("Screening Panels") as Gepaste ...

    African Journals Online (AJOL)

    In this particular article attention is paid to screening panels as pre-trial mechanism with the exclusive purpose to select malpractice disputes, discourage unfounded disputes and to encourage an early settlement in case of a prima facie case. Several objections have been raised by critics in this regard, for instance, ...

  14. ASIST 2003: Part II: Panels.

    Science.gov (United States)

    Proceedings of the ASIST Annual Meeting, 2003

    2003-01-01

    Forty-six panels address topics including women in information science; users and usability; information studies; reference services; information policies; standards; interface design; information retrieval; information networks; metadata; shared access; e-commerce in libraries; knowledge organization; information science theories; digitization;…

  15. Risk-based decisionmaking (Panel)

    Energy Technology Data Exchange (ETDEWEB)

    Smith, T.H.

    1995-12-31

    By means of a panel discussion and extensive audience interaction, explore the current challenges and progress to date in applying risk considerations to decisionmaking related to low-level waste. This topic is especially timely because of the proposed legislation pertaining to risk-based decisionmaking and because of the increased emphasis placed on radiological performance assessments of low-level waste disposal.

  16. Buckling and postbuckling of composite panels with cutouts subjected to combined edge shear and temperature change

    Science.gov (United States)

    Noor, Ahmed K.; Kim, Yong H.

    1995-01-01

    The results of a detailed study of the buckling and postbuckling responses of composite panels with central circular cutouts are presented. The panels are subjected to combined edge shear and temperature change. The panels are discretized by using a two-field degenerate solid element with each of the displacement components having a linear variation throughout the thickness of the panel. The fundamental unknowns consist of the average mechanical strains through the thickness and the displacement components. The effects of geometric nonlinearities and laminated anisotropic material behavior are included. The stability boundary, postbuckling response and the hierarchical sensitivity coefficients are evaluated. The hierarchical sensitivity coefficients measure the sensitivity of the buckling and postbuckling responses to variations in the panel stiffnesses, and the material properties of both the individual layers and the constituents (fibers and matrix). Numerical results are presented for composite panels with central circular cutouts subjected to combined edge shear and temperature change, showing the effects of variations in the hole diameter, laminate stacking sequence and fiber orientation, on the stability boundary and postbuckling response and their sensitivity to changes in the various panel parameters.

  17. Buckling Testing and Analysis of Honeycomb Sandwich Panel Arc Segments of a Full-Scale Fairing Barrel. Part 3; 8-ply Out-of-Autoclave Facesheets

    Science.gov (United States)

    Pineda, Evan J.; Myers, David E.; Kosareo, Daniel N.; Kellas, Sotiris

    2014-01-01

    Four honeycomb sandwich panels, representing 1/16th arc segments of a 10 m diameter barrel section of the heavy lift launch vehicle, were manufactured under the NASA Composites for Exploration program and the NASA Constellation Ares V program. Two configurations were chosen for the panels: 6-ply facesheets with 1.125 in. honeycomb core and 8-ply facesheets with 1.000 in. honeycomb core. Additionally, two separate carbon fiber/epoxy material systems were chosen for the facesheets: inautoclave IM7/977-3 and out-of-autoclave T40-800B/5320-1. Smaller 3- by 5-ft panels were cut from the 1/16th barrel sections. These panels were tested under compressive loading at the NASA Langley Research Center. Furthermore, linear eigenvalue and geometrically nonlinear finite element analyses were performed to predict the compressive response of the 3- by 5-ft panels. This manuscript summarizes the experimental and analytical modeling efforts pertaining to the panel composed of 8-ply, T40-800B/5320-1 facesheets (referred to as Panel C). To improve the robustness of the geometrically nonlinear finite element model, measured surface imperfections were included in the geometry of the model. Both the linear and nonlinear, two-dimensional (2-D) and three-dimensional (3-D), models yield good qualitative and quantitative predictions. Additionally, it was predicted correctly that the panel would fail in buckling prior to failing in strength.

  18. Use of Internet panels to conduct surveys.

    Science.gov (United States)

    Hays, Ron D; Liu, Honghu; Kapteyn, Arie

    2015-09-01

    The use of Internet panels to collect survey data is increasing because it is cost-effective, enables access to large and diverse samples quickly, takes less time than traditional methods to obtain data for analysis, and the standardization of the data collection process makes studies easy to replicate. A variety of probability-based panels have been created, including Telepanel/CentERpanel, Knowledge Networks (now GFK KnowledgePanel), the American Life Panel, the Longitudinal Internet Studies for the Social Sciences panel, and the Understanding America Study panel. Despite the advantage of having a known denominator (sampling frame), the probability-based Internet panels often have low recruitment participation rates, and some have argued that there is little practical difference between opting out of a probability sample and opting into a nonprobability (convenience) Internet panel. This article provides an overview of both probability-based and convenience panels, discussing potential benefits and cautions for each method, and summarizing the approaches used to weight panel respondents in order to better represent the underlying population. Challenges of using Internet panel data are discussed, including false answers, careless responses, giving the same answer repeatedly, getting multiple surveys from the same respondent, and panelists being members of multiple panels. More is to be learned about Internet panels generally and about Web-based data collection, as well as how to evaluate data collected using mobile devices and social-media platforms.

  19. Nonlinear photonic metasurfaces

    Science.gov (United States)

    Li, Guixin; Zhang, Shuang; Zentgraf, Thomas

    2017-03-01

    Compared with conventional optical elements, 2D photonic metasurfaces, consisting of arrays of antennas with subwavelength thickness (the 'meta-atoms'), enable the manipulation of light-matter interactions on more compact platforms. The use of metasurfaces with spatially varying arrangements of meta-atoms that have subwavelength lateral resolution allows control of the polarization, phase and amplitude of light. Many exotic phenomena have been successfully demonstrated in linear optics; however, to meet the growing demand for the integration of more functionalities into a single optoelectronic circuit, the tailorable nonlinear optical properties of metasurfaces will also need to be exploited. In this Review, we discuss the design of nonlinear photonic metasurfaces — in particular, the criteria for choosing the materials and symmetries of the meta-atoms — for the realization of nonlinear optical chirality, nonlinear geometric Berry phase and nonlinear wavefront engineering. Finally, we survey the application of nonlinear photonic metasurfaces in optical switching and modulation, and we conclude with an outlook on their use for terahertz nonlinear optics and quantum information processing.

  20. Nonlinear crack mechanics

    International Nuclear Information System (INIS)

    Khoroshun, L.P.

    1995-01-01

    The characteristic features of the deformation and failure of actual materials in the vicinity of a crack tip are due to their physical nonlinearity in the stress-concentration zone, which is a result of plasticity, microfailure, or a nonlinear dependence of the interatomic forces on the distance. Therefore, adequate models of the failure mechanics must be nonlinear, in principle, although linear failure mechanics is applicable if the zone of nonlinear deformation is small in comparison with the crack length. Models of crack mechanics are based on analytical solutions of the problem of the stress-strain state in the vicinity of the crack. On account of the complexity of the problem, nonlinear models are bason on approximate schematic solutions. In the Leonov-Panasyuk-Dugdale nonlinear model, one of the best known, the actual two-dimensional plastic zone (the nonlinearity zone) is replaced by a narrow one-dimensional zone, which is then modeled by extending the crack with a specified normal load equal to the yield point. The condition of finite stress is applied here, and hence the length of the plastic zone is determined. As a result of this approximation, the displacement in the plastic zone at the abscissa is nonzero

  1. Nonlinear impact of the marketing mix on brand sales performance

    OpenAIRE

    Porto, Rafael Barreiros; Lima, Nolah Schutte da Rocha

    2016-01-01

    The pattern of the impact that marketing activities exert on sales has not been widely examined in the literature. Many studies have adopted restricted linear perspectives, disregarding the empirical evidence. We investigated the nonlinear impact of the marketing mix on the volume of sales, volume of consumers and level of purchasing by each consumer, through a longitudinal study with panel data of brands and consumers simultaneously. We analyzed 121 brands during 13 months, with 793 purchase...

  2. Nonlinear Dynamics and Bifurcation Analysis of a Boost Converter for Battery Charging in Photovoltaic Applications

    Science.gov (United States)

    Al-Hindawi, Mohammed M.; Abusorrah, Abdullah; Al-Turki, Yusuf; Giaouris, Damian; Mandal, Kuntal; Banerjee, Soumitro

    Photovoltaic (PV) systems with a battery back-up form an integral part of distributed generation systems and therefore have recently attracted a lot of interest. In this paper, we consider a system of charging a battery from a PV panel through a current mode controlled boost dc-dc converter. We analyze its complete nonlinear/nonsmooth dynamics, using a piecewise model of the converter and realistic nonlinear v-i characteristics of the PV panel. Through this study, it is revealed that system design without taking into account the nonsmooth dynamics of the converter combined with the nonlinear v-i characteristics of the PV panel can lead to unpredictable responses of the overall system with high current ripple and other undesirable phenomena. This analysis can lead to better designed converters that can operate under a wide variation of the solar irradiation and the battery's state of charge. We show that the v-i characteristics of the PV panel combined with the battery's output voltage variation can increase or decrease the converter's robustness, both under peak current mode control and average current mode control. We justify the observation in terms of the change in the discrete-time map caused by the nonlinear v-i characteristics of the PV panel. The theoretical results are validated experimentally.

  3. Experimental Investigation of Discharge Coefficient in Mesh Panel Bottom Intakes

    Directory of Open Access Journals (Sweden)

    keivan bina

    2012-04-01

    Full Text Available Bottom racks is a hydraulic structure which is placed in the bed of stream through which, part of flow in the main channel is diverted. These structures have very wide application in industry, irrigation, drainage and etc. Of course much attention had been paid to the study of such structures, but characteristics of flow through bottom racks are complex. The present study was directed to estimate the discharge coefficient of a new kind of bottom racks including both transverse and longitudinal bars that named "mesh panel racks" without considering any solids in the fluid. This kind of bottom intake has advantages from structural point of view and has less deformation under static and dynamic loads. Laboratory setup with three mesh panel intakes was built and the effects of various parameters such as racks slope, porosity and geometry were explored. A dimensional analysis using Buckingham theory showed the effective hydraulic and geometric factors that affect the discharge coefficient (Cd of bottom racks. Then, a statistical approach to determine the discharge coefficient of a rack structure was developed with linear and nonlinear regression using SPSS software. The efficiency of the proposed technique is high enough that the associated error is limited to 10%. Finally, hydraulic performance of mesh panel intakes was compared with regular type of bottom intakes, which consist of longitudinal bars. For this purpose, diverted discharge through both type of intakes calculated in same situation

  4. El Salvador - Rural Electrification - Solar Panels

    Data.gov (United States)

    Millennium Challenge Corporation — This is a summative qualitative performance evaluation (PE) of the solar panel component of the solar panel component of the RE Sub-Activity. The final report will...

  5. Installation package for concentrating solar collector panels

    Science.gov (United States)

    1978-01-01

    The concentrating solar collector panels comprise a complete package array consisting of collector panels using modified Fresnel prismatic lenses for a 10 to 1 concentrating ratio, supporting framework, fluid manifolding and tracking drive system, and unassembled components for field erection.

  6. Retaining Ring Fastener for Solar Panels

    Science.gov (United States)

    Wilson, A. H.

    1983-01-01

    Simple articulating linkage secures solar panels into supporting framework. Five element linkage collapses into W-shape for easy placement into framework, then expands to form rectangle of same dimensions as those of panel.

  7. Nonlinear wave equations

    CERN Document Server

    Li, Tatsien

    2017-01-01

    This book focuses on nonlinear wave equations, which are of considerable significance from both physical and theoretical perspectives. It also presents complete results on the lower bound estimates of lifespan (including the global existence), which are established for classical solutions to the Cauchy problem of nonlinear wave equations with small initial data in all possible space dimensions and with all possible integer powers of nonlinear terms. Further, the book proposes the global iteration method, which offers a unified and straightforward approach for treating these kinds of problems. Purely based on the properties of solut ions to the corresponding linear problems, the method simply applies the contraction mapping principle.

  8. PV panel model based on datasheet values

    DEFF Research Database (Denmark)

    Sera, Dezso; Teodorescu, Remus; Rodriguez, Pedro

    2007-01-01

    This work presents the construction of a model for a PV panel using the single-diode five-parameters model, based exclusively on data-sheet parameters. The model takes into account the series and parallel (shunt) resistance of the panel. The equivalent circuit and the basic equations of the PV cell....... Based on these equations, a PV panel model, which is able to predict the panel behavior in different temperature and irradiance conditions, is built and tested....

  9. Grounds of two positions photovoltaic panels

    OpenAIRE

    Castán Fortuño, Fernando

    2008-01-01

    The objective of this Master Thesis is to find the optimum positioning for a two positions photovoltaic panel. Hence, it will be implemented a model in order to optimize the energy of the sun that the photovoltaic panel is receiving by its positioning. Likewise this project will include the comparison with other photovoltaic panel systems as the single position photovoltaics panels. Ultimately, it is also going to be designed a system array for the optimized model of two positions photovoltai...

  10. A systematic review of propulsion from the flutter kick - What can we learn from the dolphin kick?

    Science.gov (United States)

    Andersen, Jordan T; Sanders, Ross H

    2018-02-12

    Propulsion, one of the most important factors in front crawl swimming performance, is generated from both the upper and lower limbs, yet little is known about the mechanisms of propulsion from the alternating movements of the lower limbs in the flutter kick (FK). The purpose of this systematic review was to review the literature relating to the mechanisms of propulsion from FK in front crawl. There was limited information about the mechanisms of propulsion in FK. Since movements of the lower limbs are similar between FK and the dolphin kick (DK), mechanisms of propulsion from DK were reviewed to better understand propulsion from FK. Recent evidence suggests that propulsion in DK is generated in conjunction with formation and shedding of vortices. Similar vortex structures have been observed in FK. Visualisation and simulation techniques, such as particle image velocimetry (PIV) and computational fluid dynamics (CFD), are non-invasive tools that can effectively model water flow without impacting swimming technique. These technologies allow researchers to estimate the acceleration of water and, consequently, the propulsive reaction forces acting on the swimmer. Future research should use these technologies to investigate propulsion from FK.

  11. Applying non-linear dynamics to atrial appendage flow data to understand and characterize atrial arrhythmia

    International Nuclear Information System (INIS)

    Chandra, S.; Grimm, R.A.; Katz, R.; Thomas, J.D.

    1996-01-01

    The aim of this study was to better understand and characterize left atrial appendage flow in atrial fibrillation. Atrial fibrillation and flutter are the most common cardiac arrhythmias affecting 15% of the older population. The pulsed Doppler velocity profile data was recorded from the left atrial appendage of patients using transesophageal echocardiography. The data was analyzed using Fourier analysis and nonlinear dynamical tools. Fourier analysis showed that appendage mechanical frequency (f f ) for patients in sinus rhythm was always lower (around1 Hz) than that in atrial fibrillation (5-8 Hz). Among patients with atrial fibrillation spectral power below f f was significantly different suggesting variability within this group of patients. Results that suggested the presence of nonlinear dynamics were: a) the existence of two arbitrary peak frequencies f 1 , f 2 , and other peak frequencies as linear combinations thereof (mf 1 ±nf 2 ), and b) the similarity between the spectrum of patient data and that obtained using the Lorenz equation. Nonlinear analysis tools, including Phase plots and differential radial plots, were also generated from the velocity data using a delay of 10. In the phase plots, some patients displayed a torus-like structure, while others had a more random-like pattern. In the differential radial plots, the first set of patients (with torus-like phase plots) showed fewer values crossing an arbitrary threshold of 10 than did the second set (8 vs. 27 in one typical example). The outcome of cardioversion was different for these two set of patients. Fourier analysis helped to: differentiate between sinus rhythm and atrial fibrillation, understand the characteristics of the wide range of atrial fibrillation patients, and provide hints that atrial fibrillation could be a nonlinear process. Nonlinear dynamical tools helped to further characterize and sub-classify atrial fibrillation

  12. Control panel for CMC 8080 crate controller

    International Nuclear Information System (INIS)

    Masayuki Inokuchi

    1978-01-01

    The main features of Control Panel for CAMAC Crate Controller CMC 8080 are described. The control panel can be directly connected with CRATE CONTROLLER's front panel connector with a 50 lines cable without any changes in CMC 8080 system circuits. (author)

  13. 78 FR 63501 - Meetings of Humanities Panel

    Science.gov (United States)

    2013-10-24

    ... NATIONAL FOUNDATION ON THE ARTS AND THE HUMANITIES Meetings of Humanities Panel AGENCY: National Endowment for the Humanities. ACTION: Notice of meetings. SUMMARY: Pursuant to section 10(a)(2) of the... Humanities Panel will be held during November, 2013 as follows. The purpose of the meetings is for panel...

  14. 78 FR 74175 - Meetings of Humanities Panel

    Science.gov (United States)

    2013-12-10

    ... NATIONAL FOUNDATION ON THE ARTS AND THE HUMANITIES Meetings of Humanities Panel AGENCY: National Endowment for the Humanities. ACTION: Notice of meetings. SUMMARY: Pursuant to section 10(a)(2) of the... Humanities Panel will be held during January 2014 as follows. The purpose of the meetings is for panel review...

  15. Solar panel assembly and support pad

    Energy Technology Data Exchange (ETDEWEB)

    Hawley, W.W.

    1980-10-07

    A solar panel assembly is described comprising at least one solar panel, support means for carrying said panel, and at least one support pad having a base plate, upstanding longitudinal sides, and spaced apart flange means for connection to said support means, said upstanding sides and opposed flange means defining an interior volume for receiving and holding weighting material.

  16. Flat panel planar optic display

    Energy Technology Data Exchange (ETDEWEB)

    Veligdan, J.T. [Brookhaven National Lab., Upton, NY (United States). Dept. of Advanced Technology

    1994-11-01

    A prototype 10 inch flat panel Planar Optic Display, (POD), screen has been constructed and tested. This display screen is comprised of hundreds of planar optic class sheets bonded together with a cladding layer between each sheet where each glass sheet represents a vertical line of resolution. The display is 9 inches wide by 5 inches high and approximately 1 inch thick. A 3 milliwatt HeNe laser is used as the illumination source and a vector scanning technique is employed.

  17. Panel 4 - applications to transportation

    Energy Technology Data Exchange (ETDEWEB)

    Nichols, F. [Argonne National Lab., IL (United States); Au, J. [Sundstrand Aerospace, Rockford, IL (United States); Bhattacharya, R. [Universal Energy Systems, Inc., Dayton, OH (United States); Bhushan, B. [Ohio State Univ., Columbus (United States); Blunier, D. [Caterpillar, Inc., Peoria, IL (United States); Boardman, B. [Deere & Co., Moline, IL (United States); Brombolich, L. [Compu-Tec Engineering, Chesterfield, MO (United States); Davidson, J. [Vanderbilt Univ., Nashville, TN (United States); Graham, M. [Northwestern Univ., Evanston, IL (United States); Hakim, N. [Detroit Diesel Corp., MI (United States); Harris, K. [Dubbeldee Harris Diamond Corp., Mt. Arlington, NJ (United States); Hay, R. [Norton Diamond Film, Northboro, MA (United States); Herk, L. [Southwest Research Inst., Southfield, MI (United States); Hojnacki, H.; Rourk, D. [Intelligent Structures Incorporated, Canton, MI (United States); Kamo, R. [Adiabatics, Inc., Columbus, IN (United States); Nieman, B. [Allied-Signal Inc., Des Plaines, IL (United States); O`Neill, D. [3M, St. Paul, MN (United States); Peterson, M.B. [Wear Sciences, Arnold, MD (United States); Pfaffenberger, G. [Allison Gas Turbine, Indianapolis, IN (United States); Pryor, R.W. [Wayne State Univ., Detroit, MI (United States); Russell, J. [Superconductivity Publications, Inc., Somerset, NJ (United States); Syniuta, W. [Advanced Mechanical Technology, Inc., Newton, MA (United States); Tamor, M. [Ford Motor Co., Dearborn, MI (United States); Vojnovich, T. [Dept. of Energy, Washington, DC (United States); Yarbrough, W. [Pennsylvania State Univ., University Park (United States); Yust, C.S. [Oak Ridge National Lab., TN (United States)

    1993-01-01

    The aim of this group was to compile a listing of current and anticipated future problem areas in the transportation industry where the properties of diamond and DLC films make them especially attractive and where the panel could strongly endorse the establishment of DOE/Transportation Industry cooperative research efforts. This section identifies the problem areas for possible applications of diamond/DLC technology and presents indications of current approaches to these problems.

  18. Nonlinear Aeroelastic Analysis of the HIAD TPS Coupon in the NASA 8' High Temperature Tunnel: Theory and Experiment

    Science.gov (United States)

    Goldman, Benjamin D.; Scott, Robert C,; Dowell, Earl H.

    2014-01-01

    The purpose of this work is to develop a set of theoretical and experimental techniques to characterize the aeroelasticity of the thermal protection system (TPS) on the NASA Hypersonic Inflatable Aerodynamic Decelerator (HIAD). A square TPS coupon experiences trailing edge oscillatory behavior during experimental testing in the 8' High Temperature Tunnel (HTT), which may indicate the presence of aeroelastic flutter. Several theoretical aeroelastic models have been developed, each corresponding to a different experimental test configuration. Von Karman large deflection theory is used for the plate-like components of the TPS, along with piston theory for the aerodynamics. The constraints between the individual TPS layers and the presence of a unidirectional foundation at the back of the coupon are included by developing the necessary energy expressions and using the Rayleigh Ritz method to derive the nonlinear equations of motion. Free vibrations and limit cycle oscillations are computed and the frequencies and amplitudes are compared with accelerometer and photogrammetry data from the experiments.

  19. Photostable nonlinear optical polycarbonates

    NARCIS (Netherlands)

    Faccini, M.; Balakrishnan, M.; Diemeer, Mart; Torosantucci, Riccardo; Driessen, A.; Reinhoudt, David; Verboom, Willem

    2008-01-01

    Highly thermal and photostable nonlinear optical polymers were obtained by covalently incorporating the tricyanovinylidenediphenylaminobenzene (TCVDPA) chromophore to a polycarbonate backbone. NLO polycarbonates with different chromophore attachment modes and flexibilities were synthesized. In spite

  20. Nonlinear singular elliptic equations

    International Nuclear Information System (INIS)

    Dong Minh Duc.

    1988-09-01

    We improve the Poincare inequality, the Sobolev imbedding theorem and the Trudinger imbedding theorem and prove a Mountain pass theorem. Applying these results we study a nonlinear singular mixed boundary problem. (author). 22 refs

  1. Nonlinear Optical Terahertz Technology

    Data.gov (United States)

    National Aeronautics and Space Administration — We develop a new approach to generation of THz radiation. Our method relies on mixing two optical frequency beams in a nonlinear crystalline Whispering Gallery Mode...

  2. Nonlinear differential equations

    CERN Document Server

    Struble, Raimond A

    2017-01-01

    Detailed treatment covers existence and uniqueness of a solution of the initial value problem, properties of solutions, properties of linear systems, stability of nonlinear systems, and two-dimensional systems. 1962 edition.

  3. Terahertz semiconductor nonlinear optics

    DEFF Research Database (Denmark)

    Turchinovich, Dmitry; Hvam, Jørn Märcher; Hoffmann, Matthias

    2013-01-01

    In this proceedings we describe our recent results on semiconductor nonlinear optics, investigated using single-cycle THz pulses. We demonstrate the nonlinear absorption and self-phase modulation of strong-field THz pulses in doped semiconductors, using n-GaAs as a model system. The THz...... nonlinearity in doped semiconductors originates from the near-instantaneous heating of free electrons in the ponderomotive potential created by electric field of the THz pulse, leading to ultrafast increase of electron effective mass by intervalley scattering. Modification of effective mass in turn leads...... to a decrease of plasma frequency in semiconductor and produces a substantial modification of THz-range material dielectric function, described by the Drude model. As a result, the nonlinearity of both absorption coefficient and refractive index of the semiconductor is observed. In particular we demonstrate...

  4. Ultrafast nonlinear optics

    CERN Document Server

    Leburn, Christopher; Reid, Derryck

    2013-01-01

    The field of ultrafast nonlinear optics is broad and multidisciplinary, and encompasses areas concerned with both the generation and measurement of ultrashort pulses of light, as well as those concerned with the applications of such pulses. Ultrashort pulses are extreme events – both in terms of their durations, and also the high peak powers which their short durations can facilitate. These extreme properties make them powerful experiment tools. On one hand, their ultrashort durations facilitate the probing and manipulation of matter on incredibly short timescales. On the other, their ultrashort durations can facilitate high peak powers which can drive highly nonlinear light-matter interaction processes. Ultrafast Nonlinear Optics covers a complete range of topics, both applied and fundamental in nature, within the area of ultrafast nonlinear optics. Chapters 1 to 4 are concerned with the generation and measurement of ultrashort pulses. Chapters 5 to 7 are concerned with fundamental applications of ultrasho...

  5. Nonlinear surface Alfven waves

    International Nuclear Information System (INIS)

    Cramer, N.F.

    1991-01-01

    The problem of nonlinear surface Alfven waves propagating on an interface between a plasma and a vacuum is discussed, with dispersion provided by the finite-frequency effect, i.e. the finite ratio of the frequency to the ion-cyclotron frequency. A set of simplified nonlinear wave equations is derived using the method of stretched co-ordinates, and another approach uses the generation of a second-harmonic wave and its interaction with the first harmonic to obtain a nonlinear dispersion relation. A nonlinear Schroedinger equation is then derived, and soliton solutions found that propagate as solitary pulses in directions close to parallel and antiparallel to the background magnetic field. (author)

  6. A nonlinear oscillatory problem

    International Nuclear Information System (INIS)

    Zhou Qingqing.

    1991-10-01

    We have studied the nonlinear oscillatory problem of orthotropic cylindrical shell, we have analyzed the character of the oscillatory system. The stable condition of the oscillatory system has been given. (author). 6 refs

  7. Degenerate nonlinear diffusion equations

    CERN Document Server

    Favini, Angelo

    2012-01-01

    The aim of these notes is to include in a uniform presentation style several topics related to the theory of degenerate nonlinear diffusion equations, treated in the mathematical framework of evolution equations with multivalued m-accretive operators in Hilbert spaces. The problems concern nonlinear parabolic equations involving two cases of degeneracy. More precisely, one case is due to the vanishing of the time derivative coefficient and the other is provided by the vanishing of the diffusion coefficient on subsets of positive measure of the domain. From the mathematical point of view the results presented in these notes can be considered as general results in the theory of degenerate nonlinear diffusion equations. However, this work does not seek to present an exhaustive study of degenerate diffusion equations, but rather to emphasize some rigorous and efficient techniques for approaching various problems involving degenerate nonlinear diffusion equations, such as well-posedness, periodic solutions, asympt...

  8. Introduction to nonlinear science

    CERN Document Server

    Nicolis, G

    1995-01-01

    One of the most unexpected results in science in recent years is that quite ordinary systems obeying simple laws can give rise to complex, nonlinear or chaotic, behavior. In this book, the author presents a unified treatment of the concepts and tools needed to analyze nonlinear phenomena and to outline some representative applications drawn from the physical, engineering, and biological sciences. Some of the interesting topics covered include: dynamical systems with a finite number of degrees of freedom, linear stability analysis of fixed points, nonlinear behavior of fixed points, bifurcation analysis, spatially distributed systems, broken symmetries, pattern formation, and chaotic dynamics. The author makes a special effort to provide a logical connection between ordinary dynamical systems and spatially extended systems, and to balance the emphasis on chaotic behavior and more classical nonlinear behavior. He also develops a statistical approach to complex systems and compares it to traditional deterministi...

  9. Comparisons between various cavity and panel noise reduction control in double-panel structures

    NARCIS (Netherlands)

    Ho, J.H.; Kalverboer, J.; Berkhoff, A.P.

    2012-01-01

    This paper presents comparisons between various panel and cavity resonance control methods to reduce the transmitted sound in a double-panel structure. The double-panel, which consists of two panels with air in the gap, has the advantages of low weight and effective transmission-loss at high

  10. Panel Resonance Control and Cavity Control in Double-Panel Structures for Active Noise Reduction

    NARCIS (Netherlands)

    Ho, J.; Berkhoff, Arthur P.

    2011-01-01

    An analytical and experimental investigation of panel resonance control and cavity control in a double-panel structure is presented in this paper. The double-panel structure, which consists of two panels with air in the gap, is widely adopted in many applications such as aerospace due to its low

  11. Noise Reduction in Double‿Panel Structures by Cavity and Panel Resonance Control

    NARCIS (Netherlands)

    Ho, J.; Berkhoff, Arthur P.

    2011-01-01

    This paper presents an investigation of the cavity and the panel resonance control in a double‿panel structure. The double‿panel structure, which consists of two panels with air in the gap, is widely adopted in many applications such as aerospace due to its light weight and effective

  12. Noise reduction in double-panel structures by cavity and panel resonance control

    NARCIS (Netherlands)

    Ho, J.-H.; Berkhoff, A.P

    2011-01-01

    This paper presents an investigation of the cavity and the panel resonance control in a double‐panel structure. The double‐panel structure, which consists of two panels with air in the gap, is widely adopted in many applications such as aerospace due to its light weight and effective

  13. Cavity Control and Panel Control Strategies in Double-Panel Structures for Transmitted Noise Reduction

    NARCIS (Netherlands)

    Ho, J.; Kalverboer, J.; Berkhoff, Arthur P.

    2012-01-01

    Investigation and comparisons of the cavity control and the panel control in a double-panel structure are presented in this paper. The double-panel structure, which comprises two panels with air in the gap, provides the advantages of low sound-transmission at high frequency, low heat-transmission

  14. Nonlinear Wave Propagation

    Science.gov (United States)

    2015-05-07

    associated with the lattice background; the nonlinearity is derived from the inclusion of cubic nonlinearity. Often the background potential is periodic...dispersion branch we can find discrete evolution equations for the envelope associated with the lattice NLS equation (1) by looking for solutions of...spatial operator in the above NLS equation can be elliptic, hyperbolic or parabolic . We remark that further reduction is possible by going into a moving

  15. Nonlinear dynamics and astrophysics

    International Nuclear Information System (INIS)

    Vallejo, J. C.; Sanjuan, M. A. F.

    2000-01-01

    Concepts and techniques from Nonlinear Dynamics, also known as Chaos Theory, have been applied successfully to several astrophysical fields such as orbital motion, time series analysis or galactic dynamics, providing answers to old questions but also opening a few new ones. Some of these topics are described in this review article, showing the basis of Nonlinear Dynamics, and how it is applied in Astrophysics. (Author)

  16. Pescara benchmarks: nonlinear identification

    Science.gov (United States)

    Gandino, E.; Garibaldi, L.; Marchesiello, S.

    2011-07-01

    Recent nonlinear methods are suitable for identifying large systems with lumped nonlinearities, but in practice most structural nonlinearities are distributed and an ideal nonlinear identification method should cater for them as well. In order to extend the current NSI method to be applied also on realistic large engineering structures, a modal counterpart of the method is proposed in this paper. The modal NSI technique is applied on one of the reinforced concrete beams that have been tested in Pescara, under the project titled "Monitoring and diagnostics of railway bridges by means of the analysis of the dynamic response due to train crossing", financed by Italian Ministry of Research. The beam showed a softening nonlinear behaviour, so that the nonlinearity concerning the first mode is characterized and its force contribution is quantified. Moreover, estimates for the modal parameters are obtained and the model is validated by comparing the measured and the reconstructed output. The identified estimates are also used to accurately predict the behaviour of the same beam, when subject to different initial conditions.

  17. Nonlinear Multiantenna Detection Methods

    Directory of Open Access Journals (Sweden)

    Chen Sheng

    2004-01-01

    Full Text Available A nonlinear detection technique designed for multiple-antenna assisted receivers employed in space-division multiple-access systems is investigated. We derive the optimal solution of the nonlinear spatial-processing assisted receiver for binary phase shift keying signalling, which we refer to as the Bayesian detector. It is shown that this optimal Bayesian receiver significantly outperforms the standard linear beamforming assisted receiver in terms of a reduced bit error rate, at the expense of an increased complexity, while the achievable system capacity is substantially enhanced with the advent of employing nonlinear detection. Specifically, when the spatial separation expressed in terms of the angle of arrival between the desired and interfering signals is below a certain threshold, a linear beamformer would fail to separate them, while a nonlinear detection assisted receiver is still capable of performing adequately. The adaptive implementation of the optimal Bayesian detector can be realized using a radial basis function network. Two techniques are presented for constructing block-data-based adaptive nonlinear multiple-antenna assisted receivers. One of them is based on the relevance vector machine invoked for classification, while the other on the orthogonal forward selection procedure combined with the Fisher ratio class-separability measure. A recursive sample-by-sample adaptation procedure is also proposed for training nonlinear detectors based on an amalgam of enhanced -means clustering techniques and the recursive least squares algorithm.

  18. Pescara benchmarks: nonlinear identification

    International Nuclear Information System (INIS)

    Gandino, E; Garibaldi, L; Marchesiello, S

    2011-01-01

    Recent nonlinear methods are suitable for identifying large systems with lumped nonlinearities, but in practice most structural nonlinearities are distributed and an ideal nonlinear identification method should cater for them as well. In order to extend the current NSI method to be applied also on realistic large engineering structures, a modal counterpart of the method is proposed in this paper. The modal NSI technique is applied on one of the reinforced concrete beams that have been tested in Pescara, under the project titled M onitoring and diagnostics of railway bridges by means of the analysis of the dynamic response due to train crossing , financed by Italian Ministry of Research. The beam showed a softening nonlinear behaviour, so that the nonlinearity concerning the first mode is characterized and its force contribution is quantified. Moreover, estimates for the modal parameters are obtained and the model is validated by comparing the measured and the reconstructed output. The identified estimates are also used to accurately predict the behaviour of the same beam, when subject to different initial conditions.

  19. Introduction to nonlinear acoustics

    Science.gov (United States)

    Bjørnø, Leif

    2010-01-01

    A brief review of the basic principles of fluid mechanics needed for development of linear and nonlinear ultrasonic concepts will be given. The fundamental equations of nonlinear ultrasonics will be derived and their physical properties explained. It will be shown how an originally monochromatic finite-amplitude ultrasonic wave, due to nonlinear effects, will distort during its propagation in time and space to form higher harmonics to its fundamental frequency. The concepts of shock formation will be presented. The material nonlinearity, described by the nonlinearity parameter B/A of the material, and the convective nonlinearity, described by the ultrasonic Mach Number, will be explained. Two procedures for determination of B/A will briefly be described and some B/A-values characterizing biological materials will be presented. Shock formation, described by use of the Goldberg Number,and Ultrasonic Saturation will be discussed.. An introduction to focused ultrasonic fields will be given and it will be shown how the ultrasonic intensity will vary axially and laterally in and near the focal region and how the field parameters of interest to biomedical applications may be described by use of the KZK-Model. Finally, an introduction will be given to the parametric acoustic array formed by mixing and interaction of two monochromatic, finite-amplitude ultrasonic waves in a liquid and the potentials of this mixing process in biomedical ultrasound will briefly be mentioned.

  20. Fundamentals of nonlinear optical materials

    Indian Academy of Sciences (India)

    Nonlinear optics; nonlinear polarization; optical fiber communication; optical switch- ing. PACS Nos 42.65Tg; ... The importance of nonlinear optics is to understand the nonlinear behavior in the induced polarization and to ..... but much work in material development and characterization remains to be done. 16. Conclusion.

  1. Efeitos da ELTGOL e do Flutter® nos volumes pulmonares dinâmicos e estáticos e na remoção de secreção de pacientes com bronquiectasia Effects of ELTGOL and Flutter VRP1® on the dynamic and static pulmonary volumes and on the secretion clearance of patients with bronchiectasis

    Directory of Open Access Journals (Sweden)

    Fernando S. Guimarães

    2012-04-01

    Full Text Available Contextualização: Embora a fisioterapia respiratória seja considerada fundamental para o tratamento de pacientes hipersecretivos, há poucas evidências acerca de seus efeitos fisiológicos e terapêuticos em indivíduos com bronquiectasia. Objetivos: Avaliar os efeitos fisiológicos imediatos da ELTGOL e do Flutter® nos volumes pulmonares dinâmicos e estáticos em pacientes com bronquiectasia e, secundariamente, determinar o efeito dessas técnicas na remoção de secreção brônquica. Métodos: Participaram do estudo pacientes com diagnóstico clínico e radiológico de bronquiectasia. Os pacientes foram submetidos a três intervenções de forma randomizada e com um intervalo (washout de uma semana entre elas. Inicialmente os pacientes inalaram dois jatos de 100µcg de salbutamol. Após 5 minutos de tosse iniciais e após 5 minutos de tosse que sucederam o protocolo controle e as intervenções (ELTGOL e Flutter®, os pacientes realizaram as avaliações dos volumes pulmonares dinâmicos e estáticos por meio da espirometria e pletismografia corporal. A secreção expectorada foi coletada durante as intervenções e durante a segunda série de tosse, sendo quantificada por meio de seu peso seco. Resultados: Foram avaliados dez pacientes, dois do sexo masculino e oito do sexo feminino (média de idade de 55,9±18,1 anos. Após a utilização do Flutter® e da ELTGOL, observou-se diminuição significativa do volume residual (VR, da capacidade residual funcional (CRF e da CPT (pBackground: Although respiratory physical therapy is considered fundamental in the treatment of hypersecretive patients, there is little evidence of its physiological and therapeutic effects in bronchiectasis patients. Objective: To evaluate the acute physiological effects of ELTGOL and Flutter VRP1® in dynamic and static lung volumes in patients with bronchiectasis and, secondarily, to study the effect of these techniques in sputum elimination. Methods: Patients

  2. Flat panel display - Impurity doping technology for flat panel displays

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, Toshiharu [Advanced Technology Planning, Sumitomo Eaton Nova Corporation, SBS Tower 9F, 10-1, Yoga 4-chome, Setagaya-ku, 158-0097 Tokyo (Japan)]. E-mail: suzuki_tsh@senova.co.jp

    2005-08-01

    Features of the flat panel displays (FPDs) such as liquid crystal display (LCD) and organic light emitting diode (OLED) display, etc. using low temperature poly-Si (LTPS) thin film transistors (TFTs) are briefly reviewed comparing with other FPDs. The requirements for fabricating TFTs used for high performance FPDs and system on glass (SoG) are addressed. This paper focuses on the impurity doping technology, which is one of the key technologies together with crystallization by laser annealing, formation of high quality gate insulator and gate-insulator/poly-Si interface. The issues to be solved in impurity doping technology for state of the art and future TFTs are clarified.

  3. Flat panel display - Impurity doping technology for flat panel displays

    International Nuclear Information System (INIS)

    Suzuki, Toshiharu

    2005-01-01

    Features of the flat panel displays (FPDs) such as liquid crystal display (LCD) and organic light emitting diode (OLED) display, etc. using low temperature poly-Si (LTPS) thin film transistors (TFTs) are briefly reviewed comparing with other FPDs. The requirements for fabricating TFTs used for high performance FPDs and system on glass (SoG) are addressed. This paper focuses on the impurity doping technology, which is one of the key technologies together with crystallization by laser annealing, formation of high quality gate insulator and gate-insulator/poly-Si interface. The issues to be solved in impurity doping technology for state of the art and future TFTs are clarified

  4. Nonlinear Approaches in Engineering Applications

    CERN Document Server

    Jazar, Reza

    2012-01-01

    Nonlinear Approaches in Engineering Applications focuses on nonlinear phenomena that are common in the engineering field. The nonlinear approaches described in this book provide a sound theoretical base and practical tools to design and analyze engineering systems with high efficiency and accuracy and with less energy and downtime. Presented here are nonlinear approaches in areas such as dynamic systems, optimal control and approaches in nonlinear dynamics and acoustics. Coverage encompasses a wide range of applications and fields including mathematical modeling and nonlinear behavior as applied to microresonators, nanotechnologies, nonlinear behavior in soil erosion,nonlinear population dynamics, and optimization in reducing vibration and noise as well as vibration in triple-walled carbon nanotubes. This book also: Provides a complete introduction to nonlinear behavior of systems and the advantages of nonlinearity as a tool for solving engineering problems Includes applications and examples drawn from the el...

  5. High Efficiency, High Density Terrestrial Panel. [for solar cell modules

    Science.gov (United States)

    Wohlgemuth, J.; Wihl, M.; Rosenfield, T.

    1979-01-01

    Terrestrial panels were fabricated using rectangular cells. Packing densities in excess of 90% with panel conversion efficiencies greater than 13% were obtained. Higher density panels can be produced on a cost competitive basis with the standard salami panels.

  6. Thermally induced vibrations of smart solar panel in a low-orbit satellite

    Science.gov (United States)

    Azadi, E.; Fazelzadeh, S. Ahmad; Azadi, M.

    2017-03-01

    In this paper, a smart flexible satellite moving in a circular orbit with two flexible panels are studied. The panels have been modeled as clamped-free-free-free rectangular plates with attached piezoelectric actuators. It is assumed that the satellite has a pitch angle rotation maneuver. Rapid temperature changes at day-night transitions in orbit generate time dependent bending moments. Satellite maneuver and temperature varying induce vibrations in the appendages. So, to simulate the system, heat radiation effects on the appendages have been considered. The nonlinear equations of motion and the heat transfer equations are coupled and solved simultaneously. So, the governing equations of motion are nonlinear and very complicated ones. Finally, the whole system is simulated and the effects of the heat radiation, radius of the orbit, piezoelectric voltages, and piezoelectric locations on the response of the system are studied.

  7. Equilibrium moisture content of OSB panels produced with veneer inclusion and different types of adhesive

    Directory of Open Access Journals (Sweden)

    Lourival Marin Mendes

    2014-03-01

    Full Text Available The aim of this study was to evaluate different statistical models to estimate the equilibrium moisture content of OSB panels exposed to different conditions of air temperature and relative humidity, And also to evaluate the influence of the adhesive and veneer inclusion in the equilibrium moisture content. The panels were produced with three different adhesive types (phenol-formaldehyde - FF, melamine-urea-formaldehyde - MUF, and phenol-melamine-urea-formaldehyde - PMUF and with and without veneer inclusion. The evaluation of the equilibrium moisture content of the panels was carried out at temperatures of 30, 40 and 50°C and relative humidity of 40, 50, 60, 70, 80 and 90%. The modeling of equilibrium moisture content was performed using the statistical non-linear and polynomial models. In general, the polynomial models are most indicated for determining the equilibrium moisture content of OSB. The models adjusted only with air relative humidity presented the best precision measurements. The type of adhesive affected the equilibrium moisture content of the panels, being observed for adhesives PMUF and FF the same trend of variation, and the highest values obtained for the panels produced with adhesive MUF. The veneer inclusion decreased the equilibrium moisture content only in the panels with MUF adhesive.

  8. 50 years of nonlinear optics

    International Nuclear Information System (INIS)

    Shen Yuanrang

    2011-01-01

    This article presents a brief introduction to the birth and early investigations of nonlinear optics, such as second harmonic generation,sum and difference frequency generation, stimulated Raman scattering,and self-action of light etc. Several important research achievements and applications of nonlinear optics are presented as well, including nonlinear optical spectroscopy, phase conjugation and adaptive optics, coherent nonlinear optics, and high-order harmonic generation. In the end, current and future research topics in nonlinear optics are summarized. (authors)

  9. Visualizing Flutter Mechanism as Traveling Wave Through Animation of Simulation Results for the Semi-Span Super-Sonic Transport Wind-Tunnel Model

    Science.gov (United States)

    Christhilf, David M.

    2014-01-01

    It has long been recognized that frequency and phasing of structural modes in the presence of airflow play a fundamental role in the occurrence of flutter. Animation of simulation results for the long, slender Semi-Span Super-Sonic Transport (S4T) wind-tunnel model demonstrates that, for the case of mass-ballasted nacelles, the flutter mode can be described as a traveling wave propagating downstream. Such a characterization provides certain insights, such as (1) describing the means by which energy is transferred from the airflow to the structure, (2) identifying airspeed as an upper limit for speed of wave propagation, (3) providing an interpretation for a companion mode that coalesces in frequency with the flutter mode but becomes very well damped, (4) providing an explanation for bursts of response to uniform turbulence, and (5) providing an explanation for loss of low frequency (lead) phase margin with increases in dynamic pressure (at constant Mach number) for feedback systems that use sensors located upstream from active control surfaces. Results from simulation animation, simplified modeling, and wind-tunnel testing are presented for comparison. The simulation animation was generated using double time-integration in Simulink of vertical accelerometer signals distributed over wing and fuselage, along with time histories for actuated control surfaces. Crossing points for a zero-elevation reference plane were tracked along a network of lines connecting the accelerometer locations. Accelerometer signals were used in preference to modal displacement state variables in anticipation that the technique could be used to animate motion of the actual wind-tunnel model using data acquired during testing. Double integration of wind-tunnel accelerometer signals introduced severe drift even with removal of both position and rate biases such that the technique does not currently work. Using wind-tunnel data to drive a Kalman filter based upon fitting coefficients to

  10. Nonlinear Pricing in Energy and Environmental Markets

    Science.gov (United States)

    Ito, Koichiro

    This dissertation consists of three empirical studies on nonlinear pricing in energy and environmental markets. The first investigates how consumers respond to multi-tier nonlinear price schedules for residential electricity. Chapter 2 asks a similar research question for residential water pricing. Finally, I examine the effect of nonlinear financial rewards for energy conservation by applying a regression discontinuity design to a large-scale electricity rebate program that was implemented in California. Economic theory generally assumes that consumers respond to marginal prices when making economic decisions, but this assumption may not hold for complex price schedules. The chapter "Do Consumers Respond to Marginal or Average Price? Evidence from Nonlinear Electricity Pricing" provides empirical evidence that consumers respond to average price rather than marginal price when faced with nonlinear electricity price schedules. Nonlinear price schedules, such as progressive income tax rates and multi-tier electricity prices, complicate economic decisions by creating multiple marginal prices for the same good. Evidence from laboratory experiments suggests that consumers facing such price schedules may respond to average price as a heuristic. I empirically test this prediction using field data by exploiting price variation across a spatial discontinuity in electric utility service areas. The territory border of two electric utilities lies within several city boundaries in southern California. As a result, nearly identical households experience substantially different nonlinear electricity price schedules. Using monthly household-level panel data from 1999 to 2008, I find strong evidence that consumers respond to average price rather than marginal or expected marginal price. I show that even though this sub-optimizing behavior has a minimal impact on individual welfare, it can critically alter the policy implications of nonlinear pricing. The second chapter " How Do

  11. Technology Integration (Task 20) Aeroservoelastic Modeling and Design Studies. Part A; Evaluation of Aeroservoelastic Effects on Flutter and Dynamic Gust Response

    Science.gov (United States)

    Nagaraja, K. S.; Kraft, R. H.

    1999-01-01

    The HSCT Flight Controls Group has developed longitudinal control laws, utilizing PTC aeroelastic flexible models to minimize aeroservoelastic interaction effects, for a number of flight conditions. The control law design process resulted in a higher order controller and utilized a large number of sensors distributed along the body for minimizing the flexibility effects. Processes were developed to implement these higher order control laws for performing the dynamic gust loads and flutter analyses. The processes and its validation were documented in Reference 2, for selected flight condition. The analytical results for additional flight conditions are presented in this document for further validation.

  12. Impact of congestive heart failure and left ventricular systolic function on the prognostic significance of atrial fibrillation and atrial flutter following acute myocardial infarction

    DEFF Research Database (Denmark)

    Pedersen, Ole Dyg; Bagger, Henning; Køber, Lars

    2005-01-01

    fibrillation in acute myocardial infarction patients that might explain previous discrepancies. METHODS: The study population was 6676 patients consecutively admitted to hospital with acute myocardial infarction. Information on the presence of atrial fibrillation/flutter, left ventricular systolic function......BACKGROUND: Reports on the prognostic importance of atrial fibrillation following myocardial infarction have provided considerable variation in results. Thus, this study examined the impact of left ventricular systolic function and congestive heart failure on the prognostic importance of atrial...... and congestive heart failure were prospectively collected. Mortality was followed for 5 years. RESULTS: In patients with left ventricular ejection fraction

  13. Laboratory panel and radiometer calibration

    CSIR Research Space (South Africa)

    Deadman, AJ

    2011-07-01

    Full Text Available stream_source_info Griffith1_2011.pdf.txt stream_content_type text/plain stream_size 16659 Content-Encoding ISO-8859-1 stream_name Griffith1_2011.pdf.txt Content-Type text/plain; charset=ISO-8859-1 LABORATORY PANEL... of Land surface imaging through a ground reference standard test site?, on http://qa4eo.org/documentation.html, 2009. [2] K. J. Thome, D. L. Helder, D. Aaron, and J. D. Dewald, ?Landsat-5 TM and Landsat-7 ETM+ Absolute Radiometric Calibration Using...

  14. Role of fluttering dislocations in the thermal interface resistance between a silicon crystal and plastic solid 4He

    Science.gov (United States)

    Amrit, Jay; Ramiere, Aymeric; Volz, Sebastian

    2018-01-01

    A quantum solid (solid 4He) in contact with a classical solid defines a new class of interfaces. In addition to its quantum nature, solid 4He is indeed a very plastic medium. We examine the thermal interface resistance upon solidification of superfluid 4He in contact with a silicon crystal surface (111) and show that dislocations play a crucial role in the thermal interface transport. The growth of solid 4He and the measurements are conducted at the minimum of the melting curve of helium (0.778 K and ˜25 bar ). The results display a first-order transition in the Kapitza resistance from a value of RK ,L=(80 ±8 ) c m2K /W at a pressure of 24.5 bar to a value of RK ,S=(41.7 ±8 ) c m2K /W after the formation of solid helium at ˜25.2 bar . The drop in RK ,S is only of a factor of ˜2 , although transverse phonon modes in solid 4He now participate in heat transmission at the interface. We provide an explanation for the measured RK ,S by considering the interaction of thermal phonons with vibrating dislocations in solid 4He. We demonstrate that this mechanism, also called fluttering, induces a thermal resistance RF l∝NdT-6 , where T is the temperature and Nd is the density of dislocations. We estimate that for dislocation densities on the order of ˜107c m-2 , RF l predominates over the boundary resistance RK ,S. These fundamental findings shed light on the role of dislocations and provide a quantitative explanation for previous experiments which showed no measurable change in the Kapitza resistance between Cu and superfluid 4He upon solidification of the latter. This demonstrates the possibility of using dislocations as an additional means to tailor thermal resistances at interfaces, formed especially with a plastic material.

  15. Experimental and Numerical Investigations on Deformation of Cylindrical Shell Panels to Underwater Explosion

    Directory of Open Access Journals (Sweden)

    K. Ramajeyathilagam

    2001-01-01

    Full Text Available Experimental and numerical investigations on cylindrical shell panels subjected to underwater explosion loading are presented. Experiments were conducted on panels of size 0.8 × 0.6 × 0.00314 m and shell rise-to-span ratios h/l = 0.0, 0.05, 0.1 , using a box model set-up under air backed conditions in a shock tank. Small charges of PEK I explosive were employed. The plastic deformation of the panels was measured for three loading conditions. Finite element analysis was carried out using the CSA/GENSA [DYNA3D] software to predict the plastic deformation for various loading conditions. The analysis included material and geometric non-linearities, with strain rate effects incorporated based on the Cowper-Symonds relation. The numerical results for plastic deformation are compared with those from experiments.

  16. Optimum design of composite panel with photovoltaic-thermo module. Absorbing effect of cooling panel; Hikari netsu fukugo panel no saiteki sekkei. Reikyaku panel no kyunetsu koka

    Energy Technology Data Exchange (ETDEWEB)

    Sato, M; Kikuchi, S; Tani, T [Science University of Tokyo, Tokyo (Japan); Kadotani, K; Imaizumi, H [Komatsu Ltd., Tokyo (Japan)

    1996-10-27

    The composite panel with photovoltaic-thermo module becomes higher in energy-saving than the conventional air-conditioning system by the independent radiational heating and cooling effect obtained when the generating panel using a solar cell module is combined with the heating and cooling panel using a thermo-element module. The output of a solar cell module can be directly used because the solar cell module operates in AC. This paper reports the relation between the absorbed value and power consumption of the cooling panel, while paying attention to the cooling panel. The performance coefficient of the maximum absorbed value from an non-absorbing substance to a cooling panel is 2 to 3. Assume that the cooling panel during non-adiabatic operation is operated using a solar cell module of 800 W/m{sup 2} in solar intensity and 15% in conversion efficiency. The cooling-surface temperature difference is 12.12 K, and the maximum absorbed value of a non-absorbing substance to a cooling panel is 39.12 W/m{sup 2}. The absorbed value of the outer temperature to the cooling panel is 74.4 W/m{sup 2}, and each performance coefficient is 3.26 and 0.62. The absorbed value must be calculated for evaluation from the cooling-surface temperature difference measured directly from the cooling panel. 4 refs., 8 figs., 1 tab.

  17. Testing Weak Form Market Efficiency for Emerging Economies: A Nonlinear Approach

    OpenAIRE

    Omay, Nazli C.; Karadagli, Ece C.

    2010-01-01

    In this paper, we address weak form stock market efficiency of Emerging Economies, by testing whether the price series of these markets contain unit root. Nonlinear behavior of stock prices is well documented in the literature, and thus linear unit root tests may not be appropriate in this case. For this purpose, we employ the nonlinear unit root test procedure recently developed by Kapetanios et al. (2003) and nonlinear panel unit root test Ucar and Omay (2009) that has a better power than s...

  18. Nonlinear dynamics of structures

    CERN Document Server

    Oller, Sergio

    2014-01-01

    This book lays the foundation of knowledge that will allow a better understanding of nonlinear phenomena that occur in structural dynamics.   This work is intended for graduate engineering students who want to expand their knowledge on the dynamic behavior of structures, specifically in the nonlinear field, by presenting the basis of dynamic balance in non‐linear behavior structures due to the material and kinematics mechanical effects.   Particularly, this publication shows the solution of the equation of dynamic equilibrium for structure with nonlinear time‐independent materials (plasticity, damage and frequencies evolution), as well as those time dependent non‐linear behavior materials (viscoelasticity and viscoplasticity). The convergence conditions for the non‐linear dynamic structure solution  are studied, and the theoretical concepts and its programming algorithms are presented.  

  19. Nonlinear Dot Plots.

    Science.gov (United States)

    Rodrigues, Nils; Weiskopf, Daniel

    2018-01-01

    Conventional dot plots use a constant dot size and are typically applied to show the frequency distribution of small data sets. Unfortunately, they are not designed for a high dynamic range of frequencies. We address this problem by introducing nonlinear dot plots. Adopting the idea of nonlinear scaling from logarithmic bar charts, our plots allow for dots of varying size so that columns with a large number of samples are reduced in height. For the construction of these diagrams, we introduce an efficient two-way sweep algorithm that leads to a dense and symmetrical layout. We compensate aliasing artifacts at high dot densities by a specifically designed low-pass filtering method. Examples of nonlinear dot plots are compared to conventional dot plots as well as linear and logarithmic histograms. Finally, we include feedback from an expert review.

  20. Multidimensional nonlinear descriptive analysis

    CERN Document Server

    Nishisato, Shizuhiko

    2006-01-01

    Quantification of categorical, or non-numerical, data is a problem that scientists face across a wide range of disciplines. Exploring data analysis in various areas of research, such as the social sciences and biology, Multidimensional Nonlinear Descriptive Analysis presents methods for analyzing categorical data that are not necessarily sampled randomly from a normal population and often involve nonlinear relations. This reference not only provides an overview of multidimensional nonlinear descriptive analysis (MUNDA) of discrete data, it also offers new results in a variety of fields. The first part of the book covers conceptual and technical preliminaries needed to understand the data analysis in subsequent chapters. The next two parts contain applications of MUNDA to diverse data types, with each chapter devoted to one type of categorical data, a brief historical comment, and basic skills peculiar to the data types. The final part examines several problems and then concludes with suggestions for futu...

  1. Nonlinear Source Emulator

    DEFF Research Database (Denmark)

    Nguyen-Duy, Khiem

    of a proposed NSE system with high dynamic performance. The goal of the work is to achieve a state-of-the art transient time of 10 µs. In order to produce the arbitrary nonlinear curve, the exponential function of a typical diode is used, but the diode can be replaced by other nonlinear curve reference...... of conductive common-mode current produced by the high rate of change of voltage over time (high dv/dt) at the NSE output. v/xvii The contributions of the thesis are based on the development of both units: the low Cio isolated power supply and the high dynamic performance NSE. Both units are investigated......-of-the-art dynamic performance among devices of the same kind. It also offers a complete solution for simulation of nonlinear source systems of different sizes, both in terrestrial and non-terrestrial applications. Key words: Current transformers, dc-dc power converters, hysteresis, parasitic capacitance, system...

  2. Nonlinear elastic waves in materials

    CERN Document Server

    Rushchitsky, Jeremiah J

    2014-01-01

    The main goal of the book is a coherent treatment of the theory of propagation in materials of nonlinearly elastic waves of displacements, which corresponds to one modern line of development of the nonlinear theory of elastic waves. The book is divided on five basic parts: the necessary information on waves and materials; the necessary information on nonlinear theory of elasticity and elastic materials; analysis of one-dimensional nonlinear elastic waves of displacement – longitudinal, vertically and horizontally polarized transverse plane nonlinear elastic waves of displacement; analysis of one-dimensional nonlinear elastic waves of displacement – cylindrical and torsional nonlinear elastic waves of displacement; analysis of two-dimensional nonlinear elastic waves of displacement – Rayleigh and Love nonlinear elastic surface waves. The book is addressed first of all to people working in solid mechanics – from the students at an advanced undergraduate and graduate level to the scientists, professional...

  3. Dynamic assessment of nonlinear typical section aeroviscoelastic systems using fractional derivative-based viscoelastic model

    Science.gov (United States)

    Sales, T. P.; Marques, Flávio D.; Pereira, Daniel A.; Rade, Domingos A.

    2018-06-01

    Nonlinear aeroelastic systems are prone to the appearance of limit cycle oscillations, bifurcations, and chaos. Such problems are of increasing concern in aircraft design since there is the need to control nonlinear instabilities and improve safety margins, at the same time as aircraft are subjected to increasingly critical operational conditions. On the other hand, in spite of the fact that viscoelastic materials have already been successfully used for the attenuation of undesired vibrations in several types of mechanical systems, a small number of research works have addressed the feasibility of exploring the viscoelastic effect to improve the behavior of nonlinear aeroelastic systems. In this context, the objective of this work is to assess the influence of viscoelastic materials on the aeroelastic features of a three-degrees-of-freedom typical section with hardening structural nonlinearities. The equations of motion are derived accounting for the presence of viscoelastic materials introduced in the resilient elements associated to each degree-of-freedom. A constitutive law based on fractional derivatives is adopted, which allows the modeling of temperature-dependent viscoelastic behavior in time and frequency domains. The unsteady aerodynamic loading is calculated based on the classical linear potential theory for arbitrary airfoil motion. The aeroelastic behavior is investigated through time domain simulations, and subsequent frequency transformations, from which bifurcations are identified from diagrams of limit cycle oscillations amplitudes versus airspeed. The influence of the viscoelastic effect on the aeroelastic behavior, for different values of temperature, is also investigated. The numerical simulations show that viscoelastic damping can increase the flutter speed and reduce the amplitudes of limit cycle oscillations. These results prove the potential that viscoelastic materials have to increase aircraft components safety margins regarding aeroelastic

  4. Nonlinear excitations in biomolecules

    International Nuclear Information System (INIS)

    Peyrard, M.

    1995-01-01

    The aim of the workshop entitled ''Nonlinear Excitations in Biomolecules'' is to attempt to bridge the gap between the physicists and biologists communities which is mainly due to language and cultural barriers. The progress of nonlinear science in the last few decades which have shown that the combination of nonlinearity, which characterize most biological phenomena, and cooperative effects in a system having a large number of degrees of freedom, can give rise to coherent excitations with remarkable properties. New concepts, such as solitons nd nonlinear energy localisation have become familiar to physicists and applied mathematicians. It is thus tempting to make an analogy between these coherent excitations and the exceptional stability of some biological processes, such as for instance DNA transcription, which require the coordination of many events in the ever changing environment of a cell. Physicists are now invoking nonlinear excitations to describe and explain many bio-molecular processes while biologists often doubt that the seemingly infinite variety of phenomena that they are attempting to classify can be reduced to such simple concepts. A large part of the meeting is devoted to tutorial lectures rather than to latest research results. The book provides a pedagogical introduction to the two topics forming the backbone of the meeting: the theory of nonlinear excitations and solitons, and their application in biology; and the structure and function of biomolecules, as well as energy and charge transport in biophysics. In order to emphasize the link between physics and biology, the volume is not divided along these two topics but according to biological subjects. Each chapter starts with a short introduction attempting to help the reader to find his way among the contributions and point out the connection between them. 23 lectures over the 32 presented have been selected and refers to quantum properties of macro-molecules. (J.S.)

  5. Oscillations in nonlinear systems

    CERN Document Server

    Hale, Jack K

    2015-01-01

    By focusing on ordinary differential equations that contain a small parameter, this concise graduate-level introduction to the theory of nonlinear oscillations provides a unified approach to obtaining periodic solutions to nonautonomous and autonomous differential equations. It also indicates key relationships with other related procedures and probes the consequences of the methods of averaging and integral manifolds.Part I of the text features introductory material, including discussions of matrices, linear systems of differential equations, and stability of solutions of nonlinear systems. Pa

  6. Nonlinearity in nanomechanical cantilevers

    DEFF Research Database (Denmark)

    Villanueva Torrijo, Luis Guillermo; Karabalin, R. B.; Matheny, M. H.

    2013-01-01

    Euler-Bernoulli beam theory is widely used to successfully predict the linear dynamics of micro-and nanocantilever beams. However, its capacity to characterize the nonlinear dynamics of these devices has not yet been rigorously assessed, despite its use in nanoelectromechanical systems developmen....... These findings underscore the delicate balance between inertial and geometric nonlinear effects in the fundamental mode, and strongly motivate further work to develop theories beyond the Euler-Bernoulli approximation. DOI: 10.1103/PhysRevB.87.024304...

  7. Coupled nonlinear oscillators

    Energy Technology Data Exchange (ETDEWEB)

    Chandra, J; Scott, A C

    1983-01-01

    Topics discussed include transitions in weakly coupled nonlinear oscillators, singularly perturbed delay-differential equations, and chaos in simple laser systems. Papers are presented on truncated Navier-Stokes equations in a two-dimensional torus, on frequency locking in Josephson point contacts, and on soliton excitations in Josephson tunnel junctions. Attention is also given to the nonlinear coupling of radiation pulses to absorbing anharmonic molecular media, to aspects of interrupted coarse-graining in stimulated excitation, and to a statistical analysis of long-term dynamic irregularity in an exactly soluble quantum mechanical model.

  8. Engineered nonlinear lattices

    DEFF Research Database (Denmark)

    Clausen, Carl A. Balslev; Christiansen, Peter Leth; Torner, L.

    1999-01-01

    We show that with the quasi-phase-matching technique it is possible to fabricate stripes of nonlinearity that trap and guide light like waveguides. We investigate an array of such stripes and find that when the stripes are sufficiently narrow, the beam dynamics is governed by a quadratic nonlinear...... discrete equation. The proposed structure therefore provides an experimental setting for exploring discrete effects in a controlled manner. In particular, we show propagation of breathers that are eventually trapped by discreteness. When the stripes are wide the beams evolve in a structure we term...

  9. Nonlinear fiber optics

    CERN Document Server

    Agrawal, Govind

    2012-01-01

    Since the 4e appeared, a fast evolution of the field has occurred. The 5e of this classic work provides an up-to-date account of the nonlinear phenomena occurring inside optical fibers, the basis of all our telecommunications infastructure as well as being used in the medical field. Reflecting the big developments in research, this new edition includes major new content: slow light effects, which offers a reduction in noise and power consumption and more ordered network traffic-stimulated Brillouin scattering; vectorial treatment of highly nonlinear fibers; and a brand new chapter o

  10. Is the investment-uncertainty relationship nonlinear? An empirical analysis for the Netherlands

    NARCIS (Netherlands)

    Bo, H; Lensin, R

    We examine the investment-uncertainty relationship for a panel of Dutch non-financial firms. The system generalized method of moments (GMM) estimates suggest that the effect of uncertainty on investment is nonlinear: for low levels of uncertainty an increase in uncertainty has a positive effect on

  11. Control design on the basis of approximate nonlinear models: the inverted pendulum example

    DEFF Research Database (Denmark)

    Jouffroy, Jerome; Lottin, Jacques

    The main interest of linear models is the wide panel of control structures that are available. This also motivated a large amount of work to extend these structures to nonlinear plants, either by local or exact linearization, or by introducing robustness properties. At the same time other works d...

  12. Solar-Panel Dust Accumulation and Cleanings

    Science.gov (United States)

    2005-01-01

    Air-fall dust accumulates on the solar panels of NASA's Mars Exploration Rovers, reducing the amount of sunlight reaching the solar arrays. Pre-launch models predicted steady dust accumulation. However, the rovers have been blessed with occasional wind events that clear significant amounts of dust from the solar panels. This graph shows the effects of those panel-cleaning events on the amount of electricity generated by Spirit's solar panels. The horizontal scale is the number of Martian days (sols) after Spirit's Jan. 4, 2005, (Universal Time) landing on Mars. The vertical scale indicates output from the rover's solar panels as a fraction of the amount produced when the clean panels first opened. Note that the gradual declines are interrupted by occasional sharp increases, such as a dust-cleaning event on sol 420.

  13. Solar Panel Installations on Existing Structures

    OpenAIRE

    Tim D. Sass; Pe; Leed

    2013-01-01

    The rising price of fossil fuels, government incentives and growing public aware-ness for the need to implement sustainable energy supplies has resulted in a large in-crease in solar panel installations across the country. For many sites the most eco-nomical solar panel installation uses existing, southerly facing rooftops. Adding solar panels to an existing roof typically means increased loads that must be borne by the building-s structural elements. The structural desig...

  14. Geothermal Technologies Program Blue Ribbon Panel Recommendations

    Energy Technology Data Exchange (ETDEWEB)

    none,

    2011-06-17

    The Geothermal Technologies Program assembled a geothermal Blue Ribbon Panel on March 22-23, 2011 in Albuquerque, New Mexico for a guided discussion on the future of geothermal energy in the United States and the role of the DOE Program. The Geothermal Blue Ribbon Panel Report captures the discussions and recommendations of the experts. An addendum is available here: http://www.eere.energy.gov/geothermal/pdfs/gtp_blue_ribbon_panel_report_addendum10-2011.pdf

  15. Sound transmission loss of composite sandwich panels

    Science.gov (United States)

    Zhou, Ran

    Light composite sandwich panels are increasingly used in automobiles, ships and aircraft, because of the advantages they offer of high strength-to-weight ratios. However, the acoustical properties of these light and stiff structures can be less desirable than those of equivalent metal panels. These undesirable properties can lead to high interior noise levels. A number of researchers have studied the acoustical properties of honeycomb and foam sandwich panels. Not much work, however, has been carried out on foam-filled honeycomb sandwich panels. In this dissertation, governing equations for the forced vibration of asymmetric sandwich panels are developed. An analytical expression for modal densities of symmetric sandwich panels is derived from a sixth-order governing equation. A boundary element analysis model for the sound transmission loss of symmetric sandwich panels is proposed. Measurements of the modal density, total loss factor, radiation loss factor, and sound transmission loss of foam-filled honeycomb sandwich panels with different configurations and thicknesses are presented. Comparisons between the predicted sound transmission loss values obtained from wave impedance analysis, statistical energy analysis, boundary element analysis, and experimental values are presented. The wave impedance analysis model provides accurate predictions of sound transmission loss for the thin foam-filled honeycomb sandwich panels at frequencies above their first resonance frequencies. The predictions from the statistical energy analysis model are in better agreement with the experimental transmission loss values of the sandwich panels when the measured radiation loss factor values near coincidence are used instead of the theoretical values for single-layer panels. The proposed boundary element analysis model provides more accurate predictions of sound transmission loss for the thick foam-filled honeycomb sandwich panels than either the wave impedance analysis model or the

  16. Case Study - Monitoring the Photovoltaic Panels

    OpenAIRE

    PACURAR Ana Talida; TOADER Dumitru; PACURAR Cristian

    2014-01-01

    The photovoltaic cell represents one of the most dynamic and attractive way to converts renewable energy sources in electricity production. That means to convert solar energy into electricity. In this paper is presented a analogy between two types of photovoltaic panels installed, with educational role for students. Also the objective of this paper is to estimate the performance of photovoltaic panels and to provide the best solution for industry. These two types of photovoltaic panels wer...

  17. Uncertainties in predicting solar panel power output

    Science.gov (United States)

    Anspaugh, B.

    1974-01-01

    The problem of calculating solar panel power output at launch and during a space mission is considered. The major sources of uncertainty and error in predicting the post launch electrical performance of the panel are considered. A general discussion of error analysis is given. Examples of uncertainty calculations are included. A general method of calculating the effect on the panel of various degrading environments is presented, with references supplied for specific methods. A technique for sizing a solar panel for a required mission power profile is developed.

  18. Orbiter radiator panel solar focusing test

    Science.gov (United States)

    Howell, H. R.; Rankin, J. G.

    1983-01-01

    Test data are presented which define the area around the Orbiter radiator panels for which the solar reflections are concentrated to one-sun or more. The concave shape of the panels and their specular silver/Teflon coating causes focusing of the reflected solar energy which could have adverse heating effects on equipment or astronaut extravehicular activity (EVA) in the vicinity of the radiator panels. A room ambient test method was utilized with a one-tenth scale model of the radiator panels.

  19. Interagency Security Classification Appeals Panel (ISCAP) Decisions

    Data.gov (United States)

    National Archives and Records Administration — This online collection includes documents decided upon by the Interagency Security Classification Appeals Panel (ISCAP) starting in Fiscal Year 2012. The documents...

  20. Development of Electrostatically Clean Solar Array Panels

    Science.gov (United States)

    Stern, Theodore G.

    2000-01-01

    Certain missions require Electrostatically Clean Solar Array (ECSA) panels to establish a favorable environment for the operation of sensitive scientific instruments. The objective of this program was to demonstrate the feasibility of an ECSA panel that minimizes panel surface potential below 100mV in LEO and GEO charged particle environments, prevents exposure of solar cell voltage and panel insulating surfaces to the ambient environment, and provides an equipotential, grounded structure surrounding the entire panel. An ECSA panel design was developed that uses a Front Side Aperture-Shield (FSA) that covers all inter-cell areas with a single graphite composite laminate, composite edge clips for connecting the FSA to the panel substrate, and built-in tabs that interconnect the FSA to conductive coated coverglasses using a conductive adhesive. Analysis indicated the ability of the design to meet the ECSA requirements. Qualification coupons and a 0.5m x 0.5m prototype panel were fabricated and tested for photovoltaic performance and electrical grounding before and after exposure to acoustic and thermal cycling environments. The results show the feasibility of achieving electrostatic cleanliness with a small penalty in mass, photovoltaic performance and cost, with a design is structurally robust and compatible with a wide range of current solar panel technologies.

  1. Nonlinear silicon photonics

    Science.gov (United States)

    Tsia, Kevin K.; Jalali, Bahram

    2010-05-01

    An intriguing optical property of silicon is that it exhibits a large third-order optical nonlinearity, with orders-ofmagnitude larger than that of silica glass in the telecommunication band. This allows efficient nonlinear optical interaction at relatively low power levels in a small footprint. Indeed, we have witnessed a stunning progress in harnessing the Raman and Kerr effects in silicon as the mechanisms for enabling chip-scale optical amplification, lasing, and wavelength conversion - functions that until recently were perceived to be beyond the reach of silicon. With all the continuous efforts developing novel techniques, nonlinear silicon photonics is expected to be able to reach even beyond the prior achievements. Instead of providing a comprehensive overview of this field, this manuscript highlights a number of new branches of nonlinear silicon photonics, which have not been fully recognized in the past. In particular, they are two-photon photovoltaic effect, mid-wave infrared (MWIR) silicon photonics, broadband Raman effects, inverse Raman scattering, and periodically-poled silicon (PePSi). These novel effects and techniques could create a new paradigm for silicon photonics and extend its utility beyond the traditionally anticipated applications.

  2. Nonlinear Regression with R

    CERN Document Server

    Ritz, Christian; Parmigiani, Giovanni

    2009-01-01

    R is a rapidly evolving lingua franca of graphical display and statistical analysis of experiments from the applied sciences. This book provides a coherent treatment of nonlinear regression with R by means of examples from a diversity of applied sciences such as biology, chemistry, engineering, medicine and toxicology.

  3. Nonlinear silicon photonics

    Science.gov (United States)

    Borghi, M.; Castellan, C.; Signorini, S.; Trenti, A.; Pavesi, L.

    2017-09-01

    Silicon photonics is a technology based on fabricating integrated optical circuits by using the same paradigms as the dominant electronics industry. After twenty years of fervid development, silicon photonics is entering the market with low cost, high performance and mass-manufacturable optical devices. Until now, most silicon photonic devices have been based on linear optical effects, despite the many phenomenologies associated with nonlinear optics in both bulk materials and integrated waveguides. Silicon and silicon-based materials have strong optical nonlinearities which are enhanced in integrated devices by the small cross-section of the high-index contrast silicon waveguides or photonic crystals. Here the photons are made to strongly interact with the medium where they propagate. This is the central argument of nonlinear silicon photonics. It is the aim of this review to describe the state-of-the-art in the field. Starting from the basic nonlinearities in a silicon waveguide or in optical resonator geometries, many phenomena and applications are described—including frequency generation, frequency conversion, frequency-comb generation, supercontinuum generation, soliton formation, temporal imaging and time lensing, Raman lasing, and comb spectroscopy. Emerging quantum photonics applications, such as entangled photon sources, heralded single-photon sources and integrated quantum photonic circuits are also addressed at the end of this review.

  4. Generalized Nonlinear Yule Models

    Science.gov (United States)

    Lansky, Petr; Polito, Federico; Sacerdote, Laura

    2016-11-01

    With the aim of considering models related to random graphs growth exhibiting persistent memory, we propose a fractional nonlinear modification of the classical Yule model often studied in the context of macroevolution. Here the model is analyzed and interpreted in the framework of the development of networks such as the World Wide Web. Nonlinearity is introduced by replacing the linear birth process governing the growth of the in-links of each specific webpage with a fractional nonlinear birth process with completely general birth rates. Among the main results we derive the explicit distribution of the number of in-links of a webpage chosen uniformly at random recognizing the contribution to the asymptotics and the finite time correction. The mean value of the latter distribution is also calculated explicitly in the most general case. Furthermore, in order to show the usefulness of our results, we particularize them in the case of specific birth rates giving rise to a saturating behaviour, a property that is often observed in nature. The further specialization to the non-fractional case allows us to extend the Yule model accounting for a nonlinear growth.

  5. Intramolecular and nonlinear dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Davis, M.J. [Argonne National Laboratory, IL (United States)

    1993-12-01

    Research in this program focuses on three interconnected areas. The first involves the study of intramolecular dynamics, particularly of highly excited systems. The second area involves the use of nonlinear dynamics as a tool for the study of molecular dynamics and complex kinetics. The third area is the study of the classical/quantum correspondence for highly excited systems, particularly systems exhibiting classical chaos.

  6. Balancing for nonlinear systems

    NARCIS (Netherlands)

    Scherpen, J.M.A.

    1993-01-01

    We present a method of balancing for nonlinear systems which is an extension of balancing for linear systems in the sense that it is based on the input and output energy of a system. It is a local result, but gives 'broader' results than we obtain by just linearizing the system. Furthermore, the

  7. Laser Displacement Measurements of Fan Blades in Resonance and Flutter During the Boundary Layer Ingesting Inlet and Distortion-Tolerant Fan Test

    Science.gov (United States)

    Duffy, Kirsten P.; Provenza, Andrew J.; Bakhle, Milind A.; Min, James B.; Abdul-Aziz, Ali

    2018-01-01

    NASA's Advanced Air Transport Technology Project is investigating boundary layer ingesting propulsors for future subsonic commercial aircraft to improve aircraft efficiency, thereby reducing fuel burn. To that end, a boundary layer ingesting inlet and distortion-tolerant fan stage was designed, fabricated, and tested within the 8' x 6' Supersonic Wind Tunnel at NASA Glenn Research Center. Because of the distortion in the air flow over the fan, the blades were designed to withstand a much higher aerodynamic forcing than for a typical clean flow. The blade response for several resonance modes were measured during start-up and shutdown, as well as at near 85% design speed. Flutter in the first bending mode was also observed in the fan at the design speed, at an off-design condition, although instabilities were difficult to instigate with this fan in general. Blade vibrations were monitored through twelve laser displacement probes that were placed around the inner circumference of the casing, at the blade leading and trailing edges. These probes captured the movement of all the blades during the entire test. Results are presented for various resonance mode amplitudes, frequencies and damping, as well as flutter amplitudes and frequency. Benefits and disadvantages of laser displacement probe measurements versus strain gage measurements are discussed.

  8. Laser illuminated flat panel display

    Energy Technology Data Exchange (ETDEWEB)

    Veligdan, J.T.

    1995-12-31

    A 10 inch laser illuminated flat panel Planar Optic Display (POD) screen has been constructed and tested. This POD screen technology is an entirely new concept in display technology. Although the initial display is flat and made of glass, this technology lends itself to applications where a plastic display might be wrapped around the viewer. The display screen is comprised of hundreds of planar optical waveguides where each glass waveguide represents a vertical line of resolution. A black cladding layer, having a lower index of refraction, is placed between each waveguide layer. Since the cladding makes the screen surface black, the contrast is high. The prototype display is 9 inches wide by 5 inches high and approximately I inch thick. A 3 milliwatt HeNe laser is used as the illumination source and a vector scanning technique is employed.

  9. Microclimate boxes for panel paintings

    DEFF Research Database (Denmark)

    Wadum, Jørgen

    1998-01-01

    The use of microclimate boxes to protect vulnerable panel paintings is, therefore, not a new phenomenon of the past two or three decades. Rather, it has been a concern for conservators and curators to protect these objects of art at home and in transit since the end of the nineteenth century....... The increased number of travelling exhibitions in recent years has heightened the need to protect paintings during circulation (Thomson 1961; Mecklenburg 1991). The use and design of microclimate boxes have been evolving since 1892. These boxes may be divided into three broad groups: those using an active...... buffer material to stabilize the internal RH, a more recent box containing no added buffer material, and, in recent times, boxes with an altered gas content. Another concern is the appearance (aesthetics) of the box....

  10. Identification of nonlinear anelastic models

    International Nuclear Information System (INIS)

    Draganescu, G E; Bereteu, L; Ercuta, A

    2008-01-01

    A useful nonlinear identification technique applied to the anelastic and rheologic models is presented in this paper. First introduced by Feldman, the method is based on the Hilbert transform, and is currently used for identification of the nonlinear vibrations

  11. Nonlinear chaos control and synchronization

    NARCIS (Netherlands)

    Huijberts, H.J.C.; Nijmeijer, H.; Schöll, E.; Schuster, H.G.

    2007-01-01

    This chapter contains sections titled: Introduction Nonlinear Geometric Control Some Differential Geometric Concepts Nonlinear Controllability Chaos Control Through Feedback Linearization Chaos Control Through Input-Output Linearization Lyapunov Design Lyapunov Stability and Lyapunov's First Method

  12. AQUEOUS HOMOGENEOUS REACTORTECHNICAL PANEL REPORT

    Energy Technology Data Exchange (ETDEWEB)

    Diamond, D.J.; Bajorek, S.; Bakel, A.; Flanagan, G.; Mubayi, V.; Skarda, R.; Staudenmeier, J.; Taiwo, T.; Tonoike, K.; Tripp, C.; Wei, T.; Yarsky, P.

    2010-12-03

    Considerable interest has been expressed for developing a stable U.S. production capacity for medical isotopes and particularly for molybdenum- 99 (99Mo). This is motivated by recent re-ductions in production and supply worldwide. Consistent with U.S. nonproliferation objectives, any new production capability should not use highly enriched uranium fuel or targets. Conse-quently, Aqueous Homogeneous Reactors (AHRs) are under consideration for potential 99Mo production using low-enriched uranium. Although the Nuclear Regulatory Commission (NRC) has guidance to facilitate the licensing process for non-power reactors, that guidance is focused on reactors with fixed, solid fuel and hence, not applicable to an AHR. A panel was convened to study the technical issues associated with normal operation and potential transients and accidents of an AHR that might be designed for isotope production. The panel has produced the requisite AHR licensing guidance for three chapters that exist now for non-power reactor licensing: Reac-tor Description, Reactor Coolant Systems, and Accident Analysis. The guidance is in two parts for each chapter: 1) standard format and content a licensee would use and 2) the standard review plan the NRC staff would use. This guidance takes into account the unique features of an AHR such as the fuel being in solution; the fission product barriers being the vessel and attached systems; the production and release of radiolytic and fission product gases and their impact on operations and their control by a gas management system; and the movement of fuel into and out of the reactor vessel.

  13. Buckling Testing and Analysis of Honeycomb Sandwich Panel Arc Segments of a Full-Scale Fairing Barrel: Comparison of In- and Out-of-Autoclave Facesheet Configurations

    Science.gov (United States)

    Pineda, Evan Jorge; Myers, David E.; Kosareo, Daniel N.; Zalewski, Bart F.; Kellas, Sotiris; Dixon, Genevieve D.; Krivanek, Thomas M.; Gyekenyesi, Thomas G.

    2014-01-01

    Four honeycomb sandwich panels, representing 1/16th arc segments of a 10-m diameter barrel section of the Heavy Lift Launch Vehicle, were manufactured and tested under the NASA Composites for Exploration and the NASA Constellation Ares V programs. Two configurations were chosen for the panels: 6-ply facesheets with 1.125 in. honeycomb core and 8-ply facesheets with 1.0 in. honeycomb core. Additionally, two separate carbon fiber/epoxy material systems were chosen for the facesheets: in-autoclave IM7/977-3 and out-of-autoclave T40-800b/5320-1. Smaller 3 ft. by 5 ft. panels were cut from the 1/16th barrel sections and tested under compressive loading. Furthermore, linear eigenvalue and geometrically nonlinear finite element analyses were performed to predict the compressive response of each 3 ft. by 5 ft. panel. To improve the robustness of the geometrically nonlinear finite element model, measured surface imperfections were included in the geometry of the model. Both the linear and nonlinear models yielded good qualitative and quantitative predictions. Additionally, it was correctly predicted that the panel would fail in buckling prior to failing in strength. Furthermore, several imperfection studies were performed to investigate the influence of geometric imperfections, fiber angle misalignments, and three-dimensional effects on the compressive response of the panel.

  14. Nonlinearity and disorder: Classification and stability of nonlinear impurity modes

    DEFF Research Database (Denmark)

    Sukhorukov, Andrey A.; Kivshar, Yuri S.; Bang, Ole

    2001-01-01

    We study the effects produced by competition of two physical mechanisms of energy localization in inhomogeneous nonlinear systems. As an example, we analyze spatially localized modes supported by a nonlinear impurity in the generalized nonlinear Schrödinger equation and describe three types of no...... the case of a power-law nonlinearity in detail. We discuss several scenarios of the instability-induced dynamics of the nonlinear impurity modes, including the mode decay or switching to a new stable state, and collapse at the impurity site....

  15. Terahertz Nonlinear Optics in Semiconductors

    DEFF Research Database (Denmark)

    Turchinovich, Dmitry; Hvam, Jørn Märcher; Hoffmann, Matthias C.

    2013-01-01

    We demonstrate the nonlinear optical effects – selfphase modulation and saturable absorption of a single-cycle THz pulse in a semiconductor. Resulting from THz-induced modulation of Drude plasma, these nonlinear optical effects, in particular, lead to self-shortening and nonlinear spectral...... breathing of a single-cycle THz pulse in a semiconductor....

  16. FRF decoupling of nonlinear systems

    Science.gov (United States)

    Kalaycıoğlu, Taner; Özgüven, H. Nevzat

    2018-03-01

    Structural decoupling problem, i.e. predicting dynamic behavior of a particular substructure from the knowledge of the dynamics of the coupled structure and the other substructure, has been well investigated for three decades and led to several decoupling methods. In spite of the inherent nonlinearities in a structural system in various forms such as clearances, friction and nonlinear stiffness, all decoupling studies are for linear systems. In this study, decoupling problem for nonlinear systems is addressed for the first time. A method, named as FRF Decoupling Method for Nonlinear Systems (FDM-NS), is proposed for calculating FRFs of a substructure decoupled from a coupled nonlinear structure where nonlinearity can be modeled as a single nonlinear element. Depending on where nonlinear element is, i.e., either in the known or unknown subsystem, or at the connection point, the formulation differs. The method requires relative displacement information between two end points of the nonlinear element, in addition to point and transfer FRFs at some points of the known subsystem. However, it is not necessary to excite the system from the unknown subsystem even when the nonlinear element is in that subsystem. The validation of FDM-NS is demonstrated with two different case studies using nonlinear lumped parameter systems. Finally, a nonlinear experimental test structure is used in order to show the real-life application and accuracy of FDM-NS.

  17. Rogue waves in nonlinear science

    International Nuclear Information System (INIS)

    Yan Zhenya

    2012-01-01

    Rogue waves, as a special type of solitary waves, play an important role in nonlinear optics, Bose-Einstein condensates, ocean, atmosphere, and even finance. In this report, we mainly review on the history of the rogue wave phenomenon and recent development of rogue wave solutions in some nonlinear physical models arising in the fields of nonlinear science.

  18. H∞ Balancing for Nonlinear Systems

    NARCIS (Netherlands)

    Scherpen, Jacquelien M.A.

    1996-01-01

    In previously obtained balancing methods for nonlinear systems a past and a future energy function are used to bring the nonlinear system in balanced form. By considering a different pair of past and future energy functions that are related to the H∞ control problem for nonlinear systems we define

  19. Thermal and Mechanical Buckling and Postbuckling Responses of Selected Curved Composite Panels

    Science.gov (United States)

    Breivik, Nicole L.; Hyer, Michael W.; Starnes, James H., Jr.

    1998-01-01

    The results of an experimental and numerical study of the buckling and postbuckling responses of selected unstiffened curved composite panels subjected to mechanical end shortening and a uniform temperature increase are presented. The uniform temperature increase induces thermal stresses in the panel when the axial displacement is constrained. An apparatus for testing curved panels at elevated temperature is described, numerical results generated by using a geometrically nonlinear finite element analysis code are presented. Several analytical modeling refinements that provide more accurate representation of the actual experimental conditions, and the relative contribution of each refinement, are discussed. Experimental results and numerical predictions are presented and compared for three loading conditions including mechanical end shortening alone, heating the panels to 250 F followed by mechanical end shortening, and heating the panels to 400 F. Changes in the coefficients of thermal expansion were observed as temperature was increased above 330 F. The effects of these changes on the experimental results are discussed for temperatures up to 400 F.

  20. Static and fatigue experimental tests on a full scale fuselage panel and FEM analyses

    Directory of Open Access Journals (Sweden)

    Raffaele Sepe

    2016-02-01

    Full Text Available A fatigue test on a full scale panel with complex loading condition and geometry configuration has been carried out using a triaxial test machine. The demonstrator is made up of two skins which are linked by a transversal butt-joint, parallel to the stringer direction. A fatigue load was applied in the direction normal to the longitudinal joint, while a constant load was applied in the longitudinal joint direction. The test panel was instrumented with strain gages and previously quasi-static tests were conducted to ensure a proper load transferring to the panel. In order to support the tests, geometric nonlinear shell finite element analyses were conducted to predict strain and stress distributions. The demonstrator broke up after about 177000 cycles. Subsequently, a finite element analysis (FEA was carried out in order to correlate failure events; due to the biaxial nature of the fatigue loads, Sines criterion was used. The analysis was performed taking into account the different materials by which the panel is composed. The numerical results show a good correlation with experimental data, successfully predicting failure locations on the panel.

  1. Touch panel system for control applications

    International Nuclear Information System (INIS)

    Crook, K.; Johnson, R.

    1976-12-01

    The use of finger-sensitive touch panels in association with computer-generated displays for control and monitoring of the Stanford linear accelerator is discussed. This control concept has proven to be very effective. The hardware and software aspects of the Touch Panel portion of the control system are described

  2. Electronic unit for fotovoltaic solar panelling validation

    International Nuclear Information System (INIS)

    Vazquez, J.; Valverde, J.; Garcia, J.M.

    1988-01-01

    A low cost and easy to use electronic system for photovoltaic solar panelling validation is described. It measures, with a certain periodicity, voltage and current given by the panel, determines the supplied power, and every so often, its maximum valves. The unit is fitted with a data storage system which allows data recording for later analysis. (Author)

  3. Outgassing tests on iras solar panel samples

    Science.gov (United States)

    Premat, G.; Zwaal, A.; Pennings, N. H.

    1980-01-01

    Several outgassing tests were carried out on representative solar panel samples in order to determine the extent of contamination that could be expected from this source. The materials for the construction of the solar panels were selected as a result of contamination obtained in micro volatile condensable materials tests.

  4. 49 CFR 845.22 - Technical panel.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 7 2010-10-01 2010-10-01 false Technical panel. 845.22 Section 845.22... Technical panel. The Director, Bureau of Accident Investigation, or the Director, Bureau of Field Operations, shall designate members of the Board's technical staff to participate in the hearing and initially...

  5. Dynamic spatial panels : models, methods, and inferences

    NARCIS (Netherlands)

    Elhorst, J. Paul

    This paper provides a survey of the existing literature on the specification and estimation of dynamic spatial panel data models, a collection of models for spatial panels extended to include one or more of the following variables and/or error terms: a dependent variable lagged in time, a dependent

  6. 78 FR 74174 - Humanities Panel Advisory Committee

    Science.gov (United States)

    2013-12-10

    ... NATIONAL FOUNDATION ON THE ARTS AND THE HUMANITIES Humanities Panel Advisory Committee AGENCY: National Endowment for the Humanities. ACTION: Notice of Charter Renewal for Humanities Panel Advisory... its implementing regulations, 41 CFR 102-3.65, the National Endowment for the Humanities (NEH) gives...

  7. 76 FR 6828 - Meetings of Humanities Panel

    Science.gov (United States)

    2011-02-08

    ... THE NATIONAL FOUNDATION ON THE ARTS AND THE HUMANITIES Meetings of Humanities Panel AGENCY: The National Endowment for the Humanities. ACTION: Notice of Meetings. SUMMARY: Pursuant to the provisions of... following meetings of Humanities Panels will be held at the Old Post Office, 1100 Pennsylvania Avenue, NW...

  8. 75 FR 18906 - Meetings of Humanities Panel

    Science.gov (United States)

    2010-04-13

    ... NATIONAL FOUNDATION ON THE ARTS AND THE HUMANITIES Meetings of Humanities Panel AGENCY: The National Endowment for the Humanities. ACTION: Notice of Meetings. SUMMARY: Pursuant to the provisions of... following meetings of Humanities Panels will be held at the Old Post Office, 1100 Pennsylvania Avenue, NW...

  9. 76 FR 14434 - Meetings of Humanities Panel

    Science.gov (United States)

    2011-03-16

    ... THE NATIONAL FOUNDATION ON THE ARTS AND THE HUMANITIES Meetings of Humanities Panel AGENCY: The National Endowment for the Humanities, National Foundation on the Arts and the Humanities. ACTION: Notice...-463, as amended), notice is hereby given that the following meetings of Humanities Panels will be held...

  10. 75 FR 50007 - Meetings of Humanities Panel

    Science.gov (United States)

    2010-08-16

    ... THE NATIONAL FOUNDATION ON THE ARTS AND THE HUMANITIES Meetings of Humanities Panel AGENCY: The National Endowment for the Humanities. ACTION: Notice of Meetings. SUMMARY: Pursuant to the provisions of... following meetings of Humanities Panels will be held at the Old Post Office, 1100 Pennsylvania Avenue, NW...

  11. 75 FR 26285 - Meetings of Humanities Panel

    Science.gov (United States)

    2010-05-11

    ... THE NATIONAL FOUNDATION ON THE ARTS AND THE HUMANITIES Meetings of Humanities Panel AGENCY: The National Endowment for the Humanities. ACTION: Notice of meetings. SUMMARY: Pursuant to the provisions of... following meetings of Humanities Panels will be held at the Old Post Office, 1100 Pennsylvania Avenue, NW...

  12. 76 FR 77559 - Meeting of Humanities Panel

    Science.gov (United States)

    2011-12-13

    ... THE NATIONAL FOUNDATION ON THE ARTS AND THE HUMANITIES Meeting of Humanities Panel AGENCY: The National Endowment for the Humanities. ACTION: Notice of Meeting. SUMMARY: Pursuant to the provisions of... of the Humanities Panel will be held at the Old Post Office, 1100 Pennsylvania Avenue NW., Washington...

  13. 77 FR 22359 - Meetings of Humanities Panel

    Science.gov (United States)

    2012-04-13

    ... THE NATIONAL FOUNDATION ON THE ARTS AND THE HUMANITIES Meetings of Humanities Panel AGENCY: The National Endowment for the Humanities. ACTION: Notice of Meetings. SUMMARY: Pursuant to the provisions of... following meetings of Humanities Panels will be held at the Old Post Office, 1100 Pennsylvania Avenue NW...

  14. 76 FR 20375 - Meetings of Humanities Panel

    Science.gov (United States)

    2011-04-12

    ... NATIONAL FOUNDATION ON THE ARTS AND THE HUMANITIES Meetings of Humanities Panel AGENCY: The National Endowment for the Humanities ACTION: Notice of additional meeting. SUMMARY: Pursuant to the... the following meeting of the Humanities Panel will be held at the Old Post Office, 1100 Pennsylvania...

  15. 76 FR 70168 - Meetings of Humanities Panel

    Science.gov (United States)

    2011-11-10

    ... NATIONAL FOUNDATION ON THE ARTS AND THE HUMANITIES Meetings of Humanities Panel AGENCY: The National Endowment for the Humanities. ACTION: Notice of additional meeting. SUMMARY: Pursuant to the... the following meeting of the Humanities Panel will be held at the Old Post Office, 1100 Pennsylvania...

  16. 76 FR 41826 - Meetings of Humanities Panel

    Science.gov (United States)

    2011-07-15

    ... NATIONAL FOUNDATION ON THE ARTS AND THE HUMANITIES Meetings of Humanities Panel AGENCY: The National Endowment for the Humanities. ACTION: Notice of additional meeting. SUMMARY: Pursuant to the... the following meeting of the Humanities Panel will be held at the Old Post Office, 1100 Pennsylvania...

  17. 76 FR 52697 - Meetings of Humanities Panel

    Science.gov (United States)

    2011-08-23

    ... NATIONAL FOUNDATION ON THE ARTS AND THE HUMANITIES Meetings of Humanities Panel AGENCY: The National Endowment for the Humanities. ACTION: Notice of meetings. SUMMARY: Pursuant to the provisions of... following meetings of Humanities Panels will be held at the Old Post Office, 1100 Pennsylvania Avenue, NW...

  18. 76 FR 56242 - Meetings of Humanities Panel

    Science.gov (United States)

    2011-09-12

    ... THE NATIONAL FOUNDATION ON THE ARTS AND THE HUMANITIES Meetings of Humanities Panel AGENCY: The National Endowment for the Humanities, The National Foundation on the Arts and the Humanities. ACTION... Humanities Panel at the Old Post Office, 1100 Pennsylvania Avenue, NW., Washington, DC 20506 which was...

  19. 76 FR 70765 - Meetings of Humanities Panel

    Science.gov (United States)

    2011-11-15

    ... NATIONAL FOUNDATION ON THE ARTS AND THE HUMANITIES Meetings of Humanities Panel AGENCY: The National Endowment for the Humanities, National Foundation on the Arts and the Humanities. ACTION: Notice...-463, as amended), notice is hereby given that the following meetings of Humanities Panels will be held...

  20. 76 FR 63664 - Meetings of Humanities Panel

    Science.gov (United States)

    2011-10-13

    ... NATIONAL FOUNDATION ON THE ARTS AND THE HUMANITIES Meetings of Humanities Panel AGENCY: The National Endowment for the Humanities. ACTION: Notice of meetings. SUMMARY: Pursuant to the provisions of... following meetings of Humanities Panels will be held at the Old Post Office, 1100 Pennsylvania Avenue, NW...

  1. 77 FR 17102 - Meetings of Humanities Panel

    Science.gov (United States)

    2012-03-23

    ... THE NATIONAL FOUNDATION ON THE ARTS AND THE HUMANITIES Meetings of Humanities Panel AGENCY: The National Endowment for the Humanities, National Foundation on the Arts and the Humanities ACTION... Humanities Panel at the Old Post Office, 1100 Pennsylvania Avenue NW., Washington, DC 20506, which was...

  2. An intersection test for panel unit roots

    NARCIS (Netherlands)

    Hanck, C.

    2013-01-01

    This article proposes a new panel unit root test based on Simes' ( 1986) classical intersection test. The test is robust to general patterns of cross-sectional dependence and yet is straightforward to implement, only requiring p-values of time series unit root tests of the series in the panel, and

  3. Blood Test: Comprehensive Metabolic Panel (CMP)

    Science.gov (United States)

    ... Staying Safe Videos for Educators Search English Español Blood Test: Comprehensive Metabolic Panel (CMP) KidsHealth / For Parents / Blood ... de sangre: panel metabólico ampliado What Is a Blood Test? A blood test is when a sample of ...

  4. Documentation Panels Enhance Teacher Education Programs

    Science.gov (United States)

    Warash, Bobbie Gibson

    2005-01-01

    Documentation of children's projects is advantageous to their learning process and is also a good method for student teachers to observe the process of learning. Documentation panels are a unique way to help student teachers understand how children learn. Completing a panel requires a student teacher to think through a process. Teachers must learn…

  5. Delamination tolerance studies in laminated composite panels

    Indian Academy of Sciences (India)

    Abstract. Determination of levels of tolerance in delaminated composite panels is an important issue in composite structures technology. The primary intention is to analyse delaminated composite panels and estimate Strain. Energy Release Rate (SERR) parameters at the delamination front to feed into acceptability criteria.

  6. Response problems in a vacation panel study

    Science.gov (United States)

    Christine A. Vogt; Susan I. Stewart

    2001-01-01

    This paper investigates response problems encountered in a panel study of travel behavior. Though the overall response rate to the three-wave panel study was acceptable (over 60%), three types of response problems were encountered: refusal, non-response, and attrition. In a follow-up phone survey, a sample of individuals from each problem response group was questioned...

  7. 78 FR 42982 - Arts Advisory Panel Meeting

    Science.gov (United States)

    2013-07-18

    ... NATIONAL FOUNDATION ON THE ARTS AND THE HUMANITIES Arts Advisory Panel Meeting AGENCY: National Endowment for the Arts, National Foundation on the Arts and Humanities. ACTION: Notice of Meetings SUMMARY... hereby given one meeting of the Arts Advisory Panel to the National Council on the Arts will be held at...

  8. 77 FR 61643 - Arts Advisory Panel Meeting

    Science.gov (United States)

    2012-10-10

    ... NATIONAL FOUNDATION ON THE ARTS AND THE HUMANITIES Arts Advisory Panel Meeting AGENCY: National Endowment for the Arts, National Foundation on the Arts and Humanities. ACTION: Notice of meeting. SUMMARY... hereby given that sixteen meetings of the Arts Advisory Panel to the National Council on the Arts will be...

  9. 78 FR 17942 - Arts Advisory Panel Meeting

    Science.gov (United States)

    2013-03-25

    ... NATIONAL FOUNDATION ON THE ARTS AND THE HUMANITIES Arts Advisory Panel Meeting AGENCY: National Endowment for the Arts, National Foundation on the Arts and Humanities. ACTION: Notice of meetings. SUMMARY... hereby given that five meetings of the Arts Advisory Panel to the National Council on the Arts will be...

  10. 78 FR 59978 - Arts Advisory Panel Meeting

    Science.gov (United States)

    2013-09-30

    ... NATIONAL FOUNDATION ON THE ARTS AND THE HUMANITIES Arts Advisory Panel Meeting AGENCY: National Endowment for the Arts, National Foundation on the Arts and Humanities. ACTION: Notice of meeting. SUMMARY... hereby given that one meeting of the Arts Advisory Panel to the National Council on the Arts will be held...

  11. 77 FR 49026 - Arts Advisory Panel Meeting

    Science.gov (United States)

    2012-08-15

    ... NATIONAL FOUNDATION ON THE ARTS AND THE HUMANITIES Arts Advisory Panel Meeting AGENCY: National Endowment for the Arts, National Foundation on the Arts and Humanities. ACTION: Notice of meeting. SUMMARY... hereby given that one meeting of the Arts Advisory Panel to the National Council on the Arts will be held...

  12. 78 FR 21978 - Arts Advisory Panel Meeting

    Science.gov (United States)

    2013-04-12

    ... NATIONAL FOUNDATION ON THE ARTS AND THE HUMANITIES Arts Advisory Panel Meeting AGENCY: National Endowment for the Arts, National Foundation on the Arts and Humanities. ACTION: Notice of meeting. SUMMARY... is hereby given that one meeting of the Arts Advisory Panel to the National Council on the Arts will...

  13. 78 FR 26399 - Arts Advisory Panel Meeting

    Science.gov (United States)

    2013-05-06

    ... NATIONAL FOUNDATION ON THE ARTS AND THE HUMANITIES Arts Advisory Panel Meeting AGENCY: National Endowment for the Arts, National Foundation on the Arts and Humanities. ACTION: Notice of Meeting. SUMMARY... hereby given that one meeting of the Arts Advisory Panel to the National Council on the Arts will be held...

  14. 77 FR 13154 - Arts Advisory Panel Meeting

    Science.gov (United States)

    2012-03-05

    ... NATIONAL FOUNDATION ON THE ARTS AND THE HUMANITIES Arts Advisory Panel Meeting AGENCY: National Endowment for the Arts, National Foundation on the Arts and Humanities. ACTION: Notice--meeting. Pursuant to... given that a meeting of the Arts Advisory Panel to the National Council on the Arts will be held by...

  15. 77 FR 67836 - Arts Advisory Panel Meeting

    Science.gov (United States)

    2012-11-14

    ... NATIONAL FOUNDATION ON THE ARTS AND THE HUMANITIES Arts Advisory Panel Meeting AGENCY: National Endowment for the Arts, National Foundation on the Arts and Humanities. ACTION: Notice of Meeting. SUMMARY... hereby given that fifteen meetings of the Arts Advisory Panel to the National Council on the Arts will be...

  16. 78 FR 5213 - Arts Advisory Panel Meeting

    Science.gov (United States)

    2013-01-24

    ... NATIONAL FOUNDATION ON THE ARTS AND THE HUMANITIES Arts Advisory Panel Meeting AGENCY: National Endowment for the Arts, National Foundation on the Arts and Humanities. ACTION: Notice of meeting. SUMMARY... hereby given that one meeting of the Arts Advisory Panel to the National Council on the Arts will be held...

  17. 77 FR 75672 - Arts Advisory Panel Meeting

    Science.gov (United States)

    2012-12-21

    ... NATIONAL FOUNDATION ON THE ARTS AND THE HUMANITIES Arts Advisory Panel Meeting AGENCY: National Endowment for the Arts, National Foundation on the Arts and Humanities. ACTION: Notice of Meeting. SUMMARY... hereby given that seven meetings of the Arts Advisory Panel to the National Council on the Arts will be...

  18. 77 FR 41808 - Arts Advisory Panel Meeting

    Science.gov (United States)

    2012-07-16

    ... NATIONAL FOUNDATION ON THE ARTS AND THE HUMANITIES Arts Advisory Panel Meeting AGENCY: National Endowment for the Arts, National Foundation on the Arts and Humanities. ACTION: Notice of meeting. SUMMARY... hereby given that two meetings of the Arts Advisory Panel to the National Council on the Arts will be...

  19. 78 FR 68099 - Arts Advisory Panel Meeting

    Science.gov (United States)

    2013-11-13

    ... NATIONAL FOUNDATION ON THE ARTS AND THE HUMANITIES Arts Advisory Panel Meeting AGENCY: National Endowment for the Arts, National Foundation on the Arts and Humanities. ACTION: Notice of Meeting. SUMMARY... hereby given that twenty- one meetings of the Arts Advisory Panel to the National Council on the Arts...

  20. 78 FR 50451 - Arts Advisory Panel Meeting

    Science.gov (United States)

    2013-08-19

    ... NATIONAL FOUNDATION ON THE ARTS AND THE HUMANITIES Arts Advisory Panel Meeting AGENCY: National Endowment for the Arts, National Foundation on the Arts and Humanities. ACTION: Notice of Meetings. SUMMARY... hereby given that one meeting of the Arts Advisory Panel to the National Council on the Arts will be held...

  1. 77 FR 56875 - Arts Advisory Panel Meeting

    Science.gov (United States)

    2012-09-14

    ... NATIONAL FOUNDATION ON THE ARTS AND THE HUMANITIES Arts Advisory Panel Meeting AGENCY: National Endowment for the Arts, National Foundation on the Arts and Humanities. ACTION: Notice of meeting. SUMMARY... hereby given that two meetings of the Arts Advisory Panel to the National Council on the Arts will be...

  2. 77 FR 13367 - Arts Advisory Panel Meeting

    Science.gov (United States)

    2012-03-06

    ... NATIONAL FOUNDATION ON THE ARTS AND THE HUMANITIES Arts Advisory Panel Meeting AGENCY: National Endowment for the Arts, National Foundation on the Arts and Humanities. ACTION: Notice of meeting. SUMMARY... hereby given that a meeting of the Arts Advisory Panel to the National Council on the Arts will be held...

  3. Research challenges for energy data management (panel)

    DEFF Research Database (Denmark)

    Pedersen, Torben Bach; Lehner, Wolfgang

    2013-01-01

    This panel paper aims at initiating discussion at the Second International Workshop on Energy Data Management (EnDM 2013) about the important research challenges within Energy Data Management. The authors are the panel organizers, extra panelists will be recruited before the workshop...

  4. Robust block bootstrap panel predictability tests

    NARCIS (Netherlands)

    Westerlund, J.; Smeekes, S.

    2013-01-01

    Most panel data studies of the predictability of returns presume that the cross-sectional units are independent, an assumption that is not realistic. As a response to this, the current paper develops block bootstrap-based panel predictability tests that are valid under very general conditions. Some

  5. Air loads on solar panels during launch

    NARCIS (Netherlands)

    Beltman, W.M.; van der Hoogt, Peter; Spiering, R.M.E.J.; Tijdeman, H.

    1996-01-01

    The dynamical behaviour of solar panels during launch is significantly affected by the thin layers of air trapped between the panels. For narrow gaps the air manifests itself not only as a considerable added mass, but its viscosity can result in a substantial amount of damping. A model has been

  6. Circuits in the Sun: Solar Panel Physics

    Science.gov (United States)

    Gfroerer, Tim

    2013-01-01

    Typical commercial solar panels consist of approximately 60 individual photovoltaic cells connected in series. Since the usual Kirchhoff rules apply, the current is uniform throughout the circuit, while the electric potential of the individual devices is cumulative. Hence, a solar panel is a good analog of a simple resistive series circuit, except…

  7. Differing professional opinions: 1987 special review panel

    International Nuclear Information System (INIS)

    1988-01-01

    In November 1987, the five-member Differing Professional Opinions Special Review Panel established by the Executive Director for Operations of the US Nuclear Regulatory Commission to review agency policies and procedures for handling differing professional opinions (DPOs) presented its findings and recommendations in NUREG-1290. The issuance of that report completed the first task of the panel's charter. In accordance with Manual chapter 4125, Section L, and the charter of the Special Review Panel, the panel's second task was to ''...review...the DPOs submitted subsequent to the previous Panel's review, in order to identify any employee whose DPO made a significant contribution to the Agency or to the public safety but who has not yet been recognized for such contribution.'' This Addendum provides the findings of that review

  8. Graphite/epoxy orthogrid panel fabrication

    Science.gov (United States)

    Lager, J. R.

    1978-01-01

    The structural concept considered for a spacecraft body structure is a grid stiffened skin with a skin laminate configuration and the stiffener grid geometry selected to best suit the design requirements. The orthogrid panel developed weighs 0.55 lb/sq ft and resisted an ultimate in-plane shear load of 545 lbf/in. The basic concept of a grid stiffener composite panel is that a relatively thin skin is reinforced with a gridwork of stiffeners so that the overall panel can resist design loads without becoming structurally unstable or being overstressed. The main feature of the orthogrid panel design is that it provides the potential for low cost structural panels when advanced to the production phase. The most innovative part of the fabrication method is the foam/fiberglass stiffener web grid billet fabrication and machining to size.

  9. The Atomic Safety and Licensing Board Panel

    International Nuclear Information System (INIS)

    1998-01-01

    Through the Atomic Energy Act, Congress made is possible for the public to get a full and fair hearing on civilian nuclear matters. Individuals who are directly affected by any licensing action involving a facility producing or utilizing nuclear materials may participate in a formal hearing, on the record, before independent judges on the Atomic Safety and Licensing Board Panel (ASLBP or Panel). Frequently, in deciding whether a license, permit, amendment, or extension should be granted to a particular applicant, the Panel members must be more than mere umpires. If appropriate, they are authorized to go beyond the issues the parties place before them in order to identify, explore, and resolve significant questions involving threats to the public health and safety that come to a board's attention during the proceedings. This brochure explains the purpose of the panel. Also addressed are: type of hearing handled; method of public participation; formality of hearings; high-level waste; other panel responsibilities and litigation technology

  10. Thin film photovoltaic panel and method

    Science.gov (United States)

    Ackerman, Bruce; Albright, Scot P.; Jordan, John F.

    1991-06-11

    A thin film photovoltaic panel includes a backcap for protecting the active components of the photovoltaic cells from adverse environmental elements. A spacing between the backcap and a top electrode layer is preferably filled with a desiccant to further reduce water vapor contamination of the environment surrounding the photovoltaic cells. The contamination of the spacing between the backcap and the cells may be further reduced by passing a selected gas through the spacing subsequent to sealing the backcap to the base of the photovoltaic panels, and once purged this spacing may be filled with an inert gas. The techniques of the present invention are preferably applied to thin film photovoltaic panels each formed from a plurality of photovoltaic cells arranged on a vitreous substrate. The stability of photovoltaic conversion efficiency remains relatively high during the life of the photovoltaic panel, and the cost of manufacturing highly efficient panels with such improved stability is significantly reduced.

  11. Report of the Federal Internetworking Requirements Panel

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1994-05-31

    The Federal Internetworking Requirements Panel (FIRP) was established by the National Institute of Standards and Technology (NIST) to reassess Federal requirements for open systems networks and to recommend policy on the Government`s use of networking standards. The Panel was chartered to recommend actions which the Federal Government can take to address the short and long-term issues of interworking and convergence of networking protocols--particularly the Internet Protocol Suite (IPS) and Open Systems Interconnection (OSI) protocol suite and, when appropriate, proprietary protocols. The Panel was created at the request of the Office of Management and Budget in collaboration with the Federal Networking Council and the Federal Information Resources Management Policy Council. The Panel`s membership and charter are contained in an appendix to this report.

  12. Photoelectric panel with equatorial mounting of drive

    Science.gov (United States)

    Kukhta, M. S.; Krauinsh, P. Y.; Krauinsh, D. P.; Sokolov, A. P.; Mainy, S. B.

    2018-03-01

    The relevance of the work is determined by the need to create effective models for sunny energy. The article considers a photoelectric panel equipped with a system for tracking the sun. Efficiency of the system is provided by equatorial mounting, which compensates for the rotation of the Earth by rotating the sunny panel in the plane of the celestial equator. The specificity of climatic and geographical conditions of Tomsk is estimated. The dynamics of power variations of photoelectric panels with equatorial mounting during seasonal fluctuations in Tomsk is calculated. A mobile photovoltaic panel with equatorial mounting of the drive has been developed. The methods of design strategy for placing photovoltaic panels in the architectural environment of the city are presented. Key words: sunny energy, photovoltaics, equatorial mounting, mechatronic model, wave reducer, electric drive.

  13. Gene panel testing for inherited cancer risk.

    Science.gov (United States)

    Hall, Michael J; Forman, Andrea D; Pilarski, Robert; Wiesner, Georgia; Giri, Veda N

    2014-09-01

    Next-generation sequencing technologies have ushered in the capability to assess multiple genes in parallel for genetic alterations that may contribute to inherited risk for cancers in families. Thus, gene panel testing is now an option in the setting of genetic counseling and testing for cancer risk. This article describes the many gene panel testing options clinically available to assess inherited cancer susceptibility, the potential advantages and challenges associated with various types of panels, clinical scenarios in which gene panels may be particularly useful in cancer risk assessment, and testing and counseling considerations. Given the potential issues for patients and their families, gene panel testing for inherited cancer risk is recommended to be offered in conjunction or consultation with an experienced cancer genetic specialist, such as a certified genetic counselor or geneticist, as an integral part of the testing process. Copyright © 2014 by the National Comprehensive Cancer Network.

  14. Micro-inverter solar panel mounting

    Science.gov (United States)

    Morris, John; Gilchrist, Phillip Charles

    2016-02-02

    Processes, systems, devices, and articles of manufacture are provided. Each may include adapting micro-inverters initially configured for frame-mounting to mounting on a frameless solar panel. This securement may include using an adaptive clamp or several adaptive clamps secured to a micro-inverter or its components, and using compressive forces applied directly to the solar panel to secure the adaptive clamp and the components to the solar panel. The clamps can also include compressive spacers and safeties for managing the compressive forces exerted on the solar panels. Friction zones may also be used for managing slipping between the clamp and the solar panel during or after installation. Adjustments to the clamps may be carried out through various means and by changing the physical size of the clamps themselves.

  15. Nonlinear differential equations

    Energy Technology Data Exchange (ETDEWEB)

    Dresner, L.

    1988-01-01

    This report is the text of a graduate course on nonlinear differential equations given by the author at the University of Wisconsin-Madison during the summer of 1987. The topics covered are: direction fields of first-order differential equations; the Lie (group) theory of ordinary differential equations; similarity solutions of second-order partial differential equations; maximum principles and differential inequalities; monotone operators and iteration; complementary variational principles; and stability of numerical methods. The report should be of interest to graduate students, faculty, and practicing scientists and engineers. No prior knowledge is required beyond a good working knowledge of the calculus. The emphasis is on practical results. Most of the illustrative examples are taken from the fields of nonlinear diffusion, heat and mass transfer, applied superconductivity, and helium cryogenics.

  16. Nonlinear (Anharmonic Casimir Oscillator

    Directory of Open Access Journals (Sweden)

    Habibollah Razmi

    2011-01-01

    Full Text Available We want to study the dynamics of a simple linear harmonic micro spring which is under the influence of the quantum Casimir force/pressure and thus behaves as a (an nonlinear (anharmonic Casimir oscillator. Generally, the equation of motion of this nonlinear micromechanical Casimir oscillator has no exact solvable (analytical solution and the turning point(s of the system has (have no fixed position(s; however, for particular values of the stiffness of the micro spring and at appropriately well-chosen distance scales and conditions, there is (are approximately sinusoidal solution(s for the problem (the variable turning points are collected in a very small interval of positions. This, as a simple and elementary plan, may be useful in controlling the Casimir stiction problem in micromechanical devices.

  17. Limits to Nonlinear Inversion

    DEFF Research Database (Denmark)

    Mosegaard, Klaus

    2012-01-01

    For non-linear inverse problems, the mathematical structure of the mapping from model parameters to data is usually unknown or partly unknown. Absence of information about the mathematical structure of this function prevents us from presenting an analytical solution, so our solution depends on our......-heuristics are inefficient for large-scale, non-linear inverse problems, and that the 'no-free-lunch' theorem holds. We discuss typical objections to the relevance of this theorem. A consequence of the no-free-lunch theorem is that algorithms adapted to the mathematical structure of the problem perform more efficiently than...... pure meta-heuristics. We study problem-adapted inversion algorithms that exploit the knowledge of the smoothness of the misfit function of the problem. Optimal sampling strategies exist for such problems, but many of these problems remain hard. © 2012 Springer-Verlag....

  18. Nonlinear Photonics 2014: introduction.

    Science.gov (United States)

    Akhmediev, N; Kartashov, Yaroslav

    2015-01-12

    International Conference "Nonlinear Photonics-2014" took place in Barcelona, Spain on July 27-31, 2014. It was a part of the "Advanced Photonics Congress" which is becoming a traditional notable event in the world of photonics. The current focus issue of Optics Express contains contributions from the participants of the Conference and the Congress. The articles in this focus issue by no means represent the total number of the congress contributions (around 400). However, it demonstrates wide range of topics covered at the event. The next conference of this series is to be held in 2016 in Australia, which is the home of many researchers working in the field of photonics in general and nonlinear photonics in particular.

  19. Nonlinear data assimilation

    CERN Document Server

    Van Leeuwen, Peter Jan; Reich, Sebastian

    2015-01-01

    This book contains two review articles on nonlinear data assimilation that deal with closely related topics but were written and can be read independently. Both contributions focus on so-called particle filters. The first contribution by Jan van Leeuwen focuses on the potential of proposal densities. It discusses the issues with present-day particle filters and explorers new ideas for proposal densities to solve them, converging to particle filters that work well in systems of any dimension, closing the contribution with a high-dimensional example. The second contribution by Cheng and Reich discusses a unified framework for ensemble-transform particle filters. This allows one to bridge successful ensemble Kalman filters with fully nonlinear particle filters, and allows a proper introduction of localization in particle filters, which has been lacking up to now.

  20. Essentials of nonlinear optics

    CERN Document Server

    Murti, Y V G S

    2014-01-01

    Current literature on Nonlinear Optics varies widely in terms of content, style, and coverage of specific topics, relative emphasis of areas and the depth of treatment. While most of these books are excellent resources for the researchers, there is a strong need for books appropriate for presenting the subject at the undergraduate or postgraduate levels in Universities. The need for such a book to serve as a textbook at the level of the bachelors and masters courses was felt by the authors while teaching courses on nonlinear optics to students of both science and engineering during the past two decades. This book has emerged from an attempt to address the requirement of presenting the subject at college level. A one-semester course covering the essentials can effectively be designed based on this.