On simple aerodynamic sensitivity derivatives for use in interdisciplinary optimization
NASA Technical Reports Server (NTRS)
Doggett, Robert V., Jr.
1991-01-01
Low-aspect-ratio and piston aerodynamic theories are reviewed as to their use in developing aerodynamic sensitivity derivatives for use in multidisciplinary optimization applications. The basic equations relating surface pressure (or lift and moment) to normal wash are given and discussed briefly for each theory. The general means for determining selected sensitivity derivatives are pointed out. In addition, some suggestions in very general terms are included as to sample problems for use in studying the process of using aerodynamic sensitivity derivatives in optimization studies.
Sherman, L.L.; Taylor, A.C. III; Hou, G.W.; Korivi, V.M.
1996-12-01
The straightforward automatic-differentiation and the hand-differentiated incremental iterative methods are interwoven to produce a hybrid scheme that captures some of the strengths of each strategy. With this compromise, discrete aerodynamic sensitivity derivatives are calculated with the efficient incremental iterative solution algorithm of the original flow code. Moreover, the principal advantage of automatic differentiation is retained. The basic equations for second-order sensitivity derivatives are presented, which results in a comparison of four different methods. Each of these four schemes for second-order derivatives requires that large systems are solved first for the first-order adjoint variables. Of these latter three schemes, two require no solutions of large systems thereafter. For the other two for which additional systems are solved, the equations and solution procedures are analogous to those for the first-order derivatives. From a practical viewpoint, implementation of the second-order methods is feasible only with software tools such as automatic differentiation, because of the extreme complexity and large number of terms. First- and second-order sensitivities are calculated accurately for two airfoil problems, including a turbulent-flow example. In each of these two sample problems, three dependent variables (coefficients of lift, drag, and pitching-moment) and six independent variables (three geometric-shape and three flow-condition design variables) are considered. Several different procedures are tested, and results are compared on the basis of accuracy, computational time, and computer memory. For first-order derivatives, the hybrid incremental iterative scheme obtained with automatic differentiation is competitive with the best hand-differentiated method. Furthermore, it is at least two to four times faster than central finite differences, without an overwhelming penalty in computer memory. 23 refs., 14 tabs.
Sensitivity analysis in computational aerodynamics
NASA Technical Reports Server (NTRS)
Bristow, D. R.
1984-01-01
Information on sensitivity analysis in computational aerodynamics is given in outline, graphical, and chart form. The prediction accuracy if the MCAERO program, a perturbation analysis method, is discussed. A procedure for calculating perturbation matrix, baseline wing paneling for perturbation analysis test cases and applications of an inviscid sensitivity matrix are among the topics covered.
Derivation of aerodynamic kernel functions
NASA Technical Reports Server (NTRS)
Dowell, E. H.; Ventres, C. S.
1973-01-01
The method of Fourier transforms is used to determine the kernel function which relates the pressure on a lifting surface to the prescribed downwash within the framework of Dowell's (1971) shear flow model. This model is intended to improve upon the potential flow aerodynamic model by allowing for the aerodynamic boundary layer effects neglected in the potential flow model. For simplicity, incompressible, steady flow is considered. The proposed method is illustrated by deriving known results from potential flow theory.
Grid sensitivity for aerodynamic optimization and flow analysis
NASA Technical Reports Server (NTRS)
Sadrehaghighi, I.; Tiwari, S. N.
1993-01-01
After reviewing relevant literature, it is apparent that one aspect of aerodynamic sensitivity analysis, namely grid sensitivity, has not been investigated extensively. The grid sensitivity algorithms in most of these studies are based on structural design models. Such models, although sufficient for preliminary or conceptional design, are not acceptable for detailed design analysis. Careless grid sensitivity evaluations, would introduce gradient errors within the sensitivity module, therefore, infecting the overall optimization process. Development of an efficient and reliable grid sensitivity module with special emphasis on aerodynamic applications appear essential. The organization of this study is as follows. The physical and geometric representations of a typical model are derived in chapter 2. The grid generation algorithm and boundary grid distribution are developed in chapter 3. Chapter 4 discusses the theoretical formulation and aerodynamic sensitivity equation. The method of solution is provided in chapter 5. The results are presented and discussed in chapter 6. Finally, some concluding remarks are provided in chapter 7.
Some Advanced Concepts in Discrete Aerodynamic Sensitivity Analysis
NASA Technical Reports Server (NTRS)
Taylor, Arthur C., III; Green, Lawrence L.; Newman, Perry A.; Putko, Michele M.
2003-01-01
An efficient incremental iterative approach for differentiating advanced flow codes is successfully demonstrated on a two-dimensional inviscid model problem. The method employs the reverse-mode capability of the automatic differentiation software tool ADIFOR 3.0 and is proven to yield accurate first-order aerodynamic sensitivity derivatives. A substantial reduction in CPU time and computer memory is demonstrated in comparison with results from a straightforward, black-box reverse-mode applicaiton of ADIFOR 3.0 to the same flow code. An ADIFOR-assisted procedure for accurate second-rder aerodynamic sensitivity derivatives is successfully verified on an inviscid transonic lifting airfoil example problem. The method requires that first-order derivatives are calculated first using both the forward (direct) and reverse (adjoinct) procedures; then, a very efficient noniterative calculation of all second-order derivatives can be accomplished. Accurate second derivatives (i.e., the complete Hesian matrices) of lift, wave drag, and pitching-moment coefficients are calculated with respect to geometric shape, angle of attack, and freestream Mach number.
Some Advanced Concepts in Discrete Aerodynamic Sensitivity Analysis
NASA Technical Reports Server (NTRS)
Taylor, Arthur C., III; Green, Lawrence L.; Newman, Perry A.; Putko, Michele M.
2001-01-01
An efficient incremental-iterative approach for differentiating advanced flow codes is successfully demonstrated on a 2D inviscid model problem. The method employs the reverse-mode capability of the automatic- differentiation software tool ADIFOR 3.0, and is proven to yield accurate first-order aerodynamic sensitivity derivatives. A substantial reduction in CPU time and computer memory is demonstrated in comparison with results from a straight-forward, black-box reverse- mode application of ADIFOR 3.0 to the same flow code. An ADIFOR-assisted procedure for accurate second-order aerodynamic sensitivity derivatives is successfully verified on an inviscid transonic lifting airfoil example problem. The method requires that first-order derivatives are calculated first using both the forward (direct) and reverse (adjoint) procedures; then, a very efficient non-iterative calculation of all second-order derivatives can be accomplished. Accurate second derivatives (i.e., the complete Hessian matrices) of lift, wave-drag, and pitching-moment coefficients are calculated with respect to geometric- shape, angle-of-attack, and freestream Mach number
Variational Methods in Sensitivity Analysis and Optimization for Aerodynamic Applications
NASA Technical Reports Server (NTRS)
Ibrahim, A. H.; Hou, G. J.-W.; Tiwari, S. N. (Principal Investigator)
1996-01-01
Variational methods (VM) sensitivity analysis, which is the continuous alternative to the discrete sensitivity analysis, is employed to derive the costate (adjoint) equations, the transversality conditions, and the functional sensitivity derivatives. In the derivation of the sensitivity equations, the variational methods use the generalized calculus of variations, in which the variable boundary is considered as the design function. The converged solution of the state equations together with the converged solution of the costate equations are integrated along the domain boundary to uniquely determine the functional sensitivity derivatives with respect to the design function. The determination of the sensitivity derivatives of the performance index or functional entails the coupled solutions of the state and costate equations. As the stable and converged numerical solution of the costate equations with their boundary conditions are a priori unknown, numerical stability analysis is performed on both the state and costate equations. Thereafter, based on the amplification factors obtained by solving the generalized eigenvalue equations, the stability behavior of the costate equations is discussed and compared with the state (Euler) equations. The stability analysis of the costate equations suggests that the converged and stable solution of the costate equation is possible only if the computational domain of the costate equations is transformed to take into account the reverse flow nature of the costate equations. The application of the variational methods to aerodynamic shape optimization problems is demonstrated for internal flow problems at supersonic Mach number range. The study shows, that while maintaining the accuracy of the functional sensitivity derivatives within the reasonable range for engineering prediction purposes, the variational methods show a substantial gain in computational efficiency, i.e., computer time and memory, when compared with the finite
Evaluation of aerodynamic derivatives from a magnetic balance system
NASA Technical Reports Server (NTRS)
Raghunath, B. S.; Parker, H. M.
1972-01-01
The dynamic testing of a model in the University of Virginia cold magnetic balance wind-tunnel facility is expected to consist of measurements of the balance forces and moments, and the observation of the essentially six degree of freedom motion of the model. The aerodynamic derivatives of the model are to be evaluated from these observations. The basic feasibility of extracting aerodynamic information from the observation of a model which is executing transient, complex, multi-degree of freedom motion is demonstrated. It is considered significant that, though the problem treated here involves only linear aerodynamics, the methods used are capable of handling a very large class of aerodynamic nonlinearities. The basic considerations include the effect of noise in the data on the accuracy of the extracted information. Relationships between noise level and the accuracy of the evaluated aerodynamic derivatives are presented.
A PDE Sensitivity Equation Method for Optimal Aerodynamic Design
NASA Technical Reports Server (NTRS)
Borggaard, Jeff; Burns, John
1996-01-01
The use of gradient based optimization algorithms in inverse design is well established as a practical approach to aerodynamic design. A typical procedure uses a simulation scheme to evaluate the objective function (from the approximate states) and its gradient, then passes this information to an optimization algorithm. Once the simulation scheme (CFD flow solver) has been selected and used to provide approximate function evaluations, there are several possible approaches to the problem of computing gradients. One popular method is to differentiate the simulation scheme and compute design sensitivities that are then used to obtain gradients. Although this black-box approach has many advantages in shape optimization problems, one must compute mesh sensitivities in order to compute the design sensitivity. In this paper, we present an alternative approach using the PDE sensitivity equation to develop algorithms for computing gradients. This approach has the advantage that mesh sensitivities need not be computed. Moreover, when it is possible to use the CFD scheme for both the forward problem and the sensitivity equation, then there are computational advantages. An apparent disadvantage of this approach is that it does not always produce consistent derivatives. However, for a proper combination of discretization schemes, one can show asymptotic consistency under mesh refinement, which is often sufficient to guarantee convergence of the optimal design algorithm. In particular, we show that when asymptotically consistent schemes are combined with a trust-region optimization algorithm, the resulting optimal design method converges. We denote this approach as the sensitivity equation method. The sensitivity equation method is presented, convergence results are given and the approach is illustrated on two optimal design problems involving shocks.
Overview of Sensitivity Analysis and Shape Optimization for Complex Aerodynamic Configurations
NASA Technical Reports Server (NTRS)
Newman, Perry A.; Newman, James C., III; Barnwell, Richard W.; Taylor, Arthur C., III; Hou, Gene J.-W.
1998-01-01
This paper presents a brief overview of some of the more recent advances in steady aerodynamic shape-design sensitivity analysis and optimization, based on advanced computational fluid dynamics. The focus here is on those methods particularly well- suited to the study of geometrically complex configurations and their potentially complex associated flow physics. When nonlinear state equations are considered in the optimization process, difficulties are found in the application of sensitivity analysis. Some techniques for circumventing such difficulties are currently being explored and are included here. Attention is directed to methods that utilize automatic differentiation to obtain aerodynamic sensitivity derivatives for both complex configurations and complex flow physics. Various examples of shape-design sensitivity analysis for unstructured-grid computational fluid dynamics algorithms are demonstrated for different formulations of the sensitivity equations. Finally, the use of advanced, unstructured-grid computational fluid dynamics in multidisciplinary analyses and multidisciplinary sensitivity analyses within future optimization processes is recommended and encouraged.
Overview of Sensitivity Analysis and Shape Optimization for Complex Aerodynamic Configurations
NASA Technical Reports Server (NTRS)
Newman, James C., III; Taylor, Arthur C., III; Barnwell, Richard W.; Newman, Perry A.; Hou, Gene J.-W.
1999-01-01
This paper presents a brief overview of some of the more recent advances in steady aerodynamic shape-design sensitivity analysis and optimization, based on advanced computational fluid dynamics (CFD). The focus here is on those methods particularly well-suited to the study of geometrically complex configurations and their potentially complex associated flow physics. When nonlinear state equations are considered in the optimization process, difficulties are found in the application of sensitivity analysis. Some techniques for circumventing such difficulties are currently being explored and are included here. Attention is directed to methods that utilize automatic differentiation to obtain aerodynamic sensitivity derivatives for both complex configurations and complex flow physics. Various examples of shape-design sensitivity analysis for unstructured-grid CFD algorithms are demonstrated for different formulations of the sensitivity equations. Finally, the use of advanced, unstructured-grid CFDs in multidisciplinary analyses and multidisciplinary sensitivity analyses within future optimization processes is recommended and encouraged.
Grid Sensitivity and Aerodynamic Optimization of Generic Airfoils
NASA Technical Reports Server (NTRS)
Sadrehaghighi, Ideen; Smith, Robert E.; Tiwari, Surendra N.
1995-01-01
An algorithm is developed to obtain the grid sensitivity with respect to design parameters for aerodynamic optimization. The procedure is advocating a novel (geometrical) parameterization using spline functions such as NURBS (Non-Uniform Rational B- Splines) for defining the airfoil geometry. An interactive algebraic grid generation technique is employed to generate C-type grids around airfoils. The grid sensitivity of the domain with respect to geometric design parameters has been obtained by direct differentiation of the grid equations. A hybrid approach is proposed for more geometrically complex configurations such as a wing or fuselage. The aerodynamic sensitivity coefficients are obtained by direct differentiation of the compressible two-dimensional thin-layer Navier-Stokes equations. An optimization package has been introduced into the algorithm in order to optimize the airfoil surface. Results demonstrate a substantially improved design due to maximized lift/drag ratio of the airfoil.
An initial investigation into methods of computing transonic aerodynamic sensitivity coefficients
NASA Technical Reports Server (NTRS)
Carlson, Leland A.
1994-01-01
The primary accomplishments of the project are as follows: (1) Using the transonic small perturbation equation as a flowfield model, the project demonstrated that the quasi-analytical method could be used to obtain aerodynamic sensitivity coefficients for airfoils at subsonic, transonic, and supersonic conditions for design variables such as Mach number, airfoil thickness, maximum camber, angle of attack, and location of maximum camber. It was established that the quasi-analytical approach was an accurate method for obtaining aerodynamic sensitivity derivatives for airfoils at transonic conditions and usually more efficient than the finite difference approach. (2) The usage of symbolic manipulation software to determine the appropriate expressions and computer coding associated with the quasi-analytical method for sensitivity derivatives was investigated. Using the three dimensional fully conservative full potential flowfield model, it was determined that symbolic manipulation along with a chain rule approach was extremely useful in developing a combined flowfield and quasi-analytical sensitivity derivative code capable of considering a large number of realistic design variables. (3) Using the three dimensional fully conservative full potential flowfield model, the quasi-analytical method was applied to swept wings (i.e. three dimensional) at transonic flow conditions. (4) The incremental iterative technique has been applied to the three dimensional transonic nonlinear small perturbation flowfield formulation, an equivalent plate deflection model, and the associated aerodynamic and structural discipline sensitivity equations; and coupled aeroelastic results for an aspect ratio three wing in transonic flow have been obtained.
NASA Technical Reports Server (NTRS)
Lacasse, James M.
1995-01-01
A multiblock sensitivity analysis method is applied in a numerical aerodynamic shape optimization technique. The Sensitivity Analysis Domain Decomposition (SADD) scheme which is implemented in this study was developed to reduce the computer memory requirements resulting from the aerodynamic sensitivity analysis equations. Discrete sensitivity analysis offers the ability to compute quasi-analytical derivatives in a more efficient manner than traditional finite-difference methods, which tend to be computationally expensive and prone to inaccuracies. The direct optimization procedure couples CFD analysis based on the two-dimensional thin-layer Navier-Stokes equations with a gradient-based numerical optimization technique. The linking mechanism is the sensitivity equation derived from the CFD discretized flow equations, recast in adjoint form, and solved using direct matrix inversion techniques. This investigation is performed to demonstrate an aerodynamic shape optimization technique on a multiblock domain and its applicability to complex geometries. The objectives are accomplished by shape optimizing two aerodynamic configurations. First, the shape optimization of a transonic airfoil is performed to investigate the behavior of the method in highly nonlinear flows and the effect of different grid blocking strategies on the procedure. Secondly, shape optimization of a two-element configuration in subsonic flow is completed. Cases are presented for this configuration to demonstrate the effect of simultaneously reshaping interfering elements. The aerodynamic shape optimization is shown to produce supercritical type airfoils in the transonic flow from an initially symmetric airfoil. Multiblocking effects the path of optimization while providing similar results at the conclusion. Simultaneous reshaping of elements is shown to be more effective than individual element reshaping due to the inclusion of mutual interference effects.
Sensitivity Analysis and Optimization of Aerodynamic Configurations with Blend Surfaces
NASA Technical Reports Server (NTRS)
Thomas, A. M.; Tiwari, S. N.
1997-01-01
A novel (geometrical) parametrization procedure using solutions to a suitably chosen fourth order partial differential equation is used to define a class of airplane configurations. Inclusive in this definition are surface grids, volume grids, and grid sensitivity. The general airplane configuration has wing, fuselage, vertical tail and horizontal tail. The design variables are incorporated into the boundary conditions, and the solution is expressed as a Fourier series. The fuselage has circular cross section, and the radius is an algebraic function of four design parameters and an independent computational variable. Volume grids are obtained through an application of the Control Point Form method. A graphic interface software is developed which dynamically changes the surface of the airplane configuration with the change in input design variable. The software is made user friendly and is targeted towards the initial conceptual development of any aerodynamic configurations. Grid sensitivity with respect to surface design parameters and aerodynamic sensitivity coefficients based on potential flow is obtained using an Automatic Differentiation precompiler software tool ADIFOR. Aerodynamic shape optimization of the complete aircraft with twenty four design variables is performed. Unstructured and structured volume grids and Euler solutions are obtained with standard software to demonstrate the feasibility of the new surface definition.
Grid and aerodynamic sensitivity analyses of airplane components
NASA Technical Reports Server (NTRS)
Sadrehaghighi, Ideen; Smith, Robert E.; Tiwari, Surendra N.
1993-01-01
An algorithm is developed to obtain the grid sensitivity with respect to design parameters for aerodynamic optimization. The procedure is advocating a novel (geometrical) parameterization using spline functions such as NURBS (Non-Uniform Rational B-Splines) for defining the wing-section geometry. An interactive algebraic grid generation technique, known as Two-Boundary Grid Generation (TBGG) is employed to generate C-type grids around wing-sections. The grid sensitivity of the domain with respect to geometric design parameters has been obtained by direct differentiation of the grid equations. A hybrid approach is proposed for more geometrically complex configurations such as a wing or fuselage. The aerodynamic sensitivity coefficients are obtained by direct differentiation of the compressible two-dimensional thin-layer Navier-Stokes equations. An optimization package has been introduced into the algorithm in order to optimize the wing-section surface. Results demonstrate a substantially improved design due to maximized lift/drag ratio of the wing-section.
NASA Technical Reports Server (NTRS)
Yates, E. Carson, Jr.
1987-01-01
The technique of implicit differentiation has been used in combination with linearized lifting-surface theory to derive analytical expressions for aerodynamic sensitivities (i.e., rates of change of lifting pressures with respect to general changes in aircraft geometry, including planform variations) for steady or oscillating planar or nonplanar lifting surfaces in subsonic, sonic, or supersonic flow. The geometric perturbation is defined in terms of a single variable, and the user need only provide simple expressions or similar means for defining the continuous or discontinuous global or local perturbation of interest. Example expressions are given for perturbations of the sweep, taper, and aspect ratio of a wing with trapezoidal semispan planform. In addition to direct computational use, the analytical method presented here should provide benchmark criteria for assessing the accuracy of aerodynamic sensitivities obtained by approximate methods such as finite geometry perturbation and differencing. The present process appears to be readily adaptable to more general surface-panel methods.
Aerodynamic Characteristics of Two Waverider-Derived Hypersonic Cruise Configurations
NASA Technical Reports Server (NTRS)
Cockrell, Charles E., Jr.; Huebner, Lawrence D.; Finley, Dennis B.
1996-01-01
An evaluation was made on the effects of integrating the required aircraft components with hypersonic high-lift configurations known as waveriders to create hypersonic cruise vehicles. Previous studies suggest that waveriders offer advantages in aerodynamic performance and propulsion/airframe integration (PAI) characteristics over conventional non-waverider hypersonic shapes. A wind-tunnel model was developed that integrates vehicle components, including canopies, engine components, and control surfaces, with two pure waverider shapes, both conical-flow-derived waveriders for a design Mach number of 4.0. Experimental data and limited computational fluid dynamics (CFD) solutions were obtained over a Mach number range of 1.6 to 4.63. The experimental data show the component build-up effects and the aerodynamic characteristics of the fully integrated configurations, including control surface effectiveness. The aerodynamic performance of the fully integrated configurations is not comparable to that of the pure waverider shapes, but is comparable to previously tested hypersonic models. Both configurations exhibit good lateral-directional stability characteristics.
The transformation of aerodynamic stability derivatives by symbolic mathematical computation
NASA Technical Reports Server (NTRS)
Howard, J. C.
1975-01-01
The formulation of mathematical models of aeronautical systems for simulation or other purposes, involves the transformation of aerodynamic stability derivatives. It is shown that these derivatives transform like the components of a second order tensor having one index of covariance and one index of contravariance. Moreover, due to the equivalence of covariant and contravariant transformations in orthogonal Cartesian systems of coordinates, the transformations can be treated as doubly covariant or doubly contravariant, if this simplifies the formulation. It is shown that the tensor properties of these derivatives can be used to facilitate their transformation by symbolic mathematical computation, and the use of digital computers equipped with formula manipulation compilers. When the tensor transformations are mechanised in the manner described, man-hours are saved and the errors to which human operators are prone can be avoided.
Aerodynamic derivatives of a cone with a semi-apex angle 20° at supersonic velocities
NASA Astrophysics Data System (ADS)
Adamov, N. P.; Kharitonov, A. M.; Chasovnikov, E. A.
2014-12-01
The paper deals with an experimental study of stationary and nonstationary aerodynamic characteristics of a circular cone in the range of Mach numbers 1.75-7. The experimental equipment and the method of determining the aerodynamic characteristics are briefly described. The integral aerodynamic characteristics of the model in tests with force measurements and the aerodynamic derivatives of the pitching moment in dynamic tests on a setup with free oscillations are obtained. The experimental data are compared with numerical predictions.
NASA Technical Reports Server (NTRS)
Pei, Jing; Wall, John
2013-01-01
This paper describes the techniques involved in determining the aerodynamic stability derivatives for the frequency domain analysis of the Space Launch System (SLS) vehicle. Generally for launch vehicles, determination of the derivatives is fairly straightforward since the aerodynamic data is usually linear through a moderate range of angle of attack. However, if the wind tunnel data lacks proper corrections then nonlinearities and asymmetric behavior may appear in the aerodynamic database coefficients. In this case, computing the derivatives becomes a non-trivial task. Errors in computing the nominal derivatives could lead to improper interpretation regarding the natural stability of the system and tuning of the controller parameters, which would impact both stability and performance. The aerodynamic derivatives are also provided at off nominal operating conditions used for dispersed frequency domain Monte Carlo analysis. Finally, results are shown to illustrate that the effects of aerodynamic cross axis coupling can be neglected for the SLS configuration studied
Characteristics of Pressure Sensitive Paint Intrusiveness Effects on Aerodynamic Data
NASA Technical Reports Server (NTRS)
Amer, Tahani R.; Liu, Tianshu; Oglesby, Donald M.
2001-01-01
One effect of using pressure sensitive paint (PSP) is the potential intrusiveness to the aerodynamic characteristics of the model. The paint thickness and roughness may affect the pressure distribution, and therefore, the forces and moments on the wind tunnel model. A study of these potential intrusive effects was carried out at NASA Langley Research Center where a series of wind tunnel tests were conducted using the Modem Design of Experiments (MDOE) test approach. The PSP effects on the integrated forces were measured on two different models at different test conditions in both the Low Turbulence Pressure Tunnel (LTPT) and the Unitary Plan Wind Tunnel (UPWT) at Langley. The paint effect was found to be very small over a range of Reynolds numbers, Mach numbers and angles of attack. This is due to the very low surface roughness of the painted surface. The surface roughness, after applying the NASA Langley developed PSP, was lower than that of the clean wing. However, the PSP coating had a localized effects on the pressure taps, which leads to an appreciable decrease in the pressure tap reading.
Quantifying the Effect of Pressure Sensitive Paint On Aerodynamic Data
NASA Technical Reports Server (NTRS)
Amer, T. R.; Obara, C. J.; Liu, T.
2003-01-01
A thin pressure sensitive paint (PSP) coating can slightly modify the overall shape of a wind-tunnel model and produce surface roughness or smoothness that does not exist on the unpainted model. These undesirable changes in model geometry may alter flow over the model, and affect the pressure distribution and aerodynamic forces and moments on the model. This study quantifies the effects of PSP on three models in low-speed, transonic and supersonic flow regimes. At a 95% confidence level, the PSP effects on the integrated forces are insignificant for a slender arrow-wing-fuselage model and delta wing model with two different paints at Mach 0.2, 1.8, and 2.16 relative to the total balance accuracy limit. The data displayed a repeatability of 2.5 drag counts, while the balance accuracy limit was about 5.5 drag counts. At transonic speeds, the paint has a localized effect at high angles of attack and has a resolvable effect on the normal force, which is significant relative to the balance accuracy limit. For low speeds, the PSP coating has a localized effect on the pressure tap measurements, which leads to an appreciable decrease in the pressure tap reading. Moreover, the force and moment measurements had a poor precision, which precluded the ability to measure the PSP effect for this particular test.
Characterization of Pressure Sensitive Paint Intrusiveness Effects on Aerodynamic Data
NASA Technical Reports Server (NTRS)
Amer, Tahani R.; Liu, Tianshu; Oglesby, Donald M.
2001-01-01
One effect of using pressure sensitive paint (PSP) is the potential intrusiveness to the aerodynamic characteristics of the model. The paint thickness and roughness may affect the pressure distribution. and therefore, the forces and moments on the wind tunnel model. A study of these potential intrusive effects was carried out at NASA Langley Research Center where a series of wind tunnel tests were conducted using the Modem Design of Experiments (MDOE) test approach. The PSP effects on the integrated forces were measured on two different models at different test conditions in both the Low Turbulence Pressure Tunnel (LTPT) and the Unitary Plan Wind Tunnel (UPWT) at Langley. The paint effect was found to be very small over a range of Reynolds numbers, Mach numbers and angles of attack. This is due to the very low surface roughness of the painted surface. The surface roughness, after applying the NASA Langley developed PSP, was lower than that of the clean wing. However, the PSP coating had a localized effects on the pressure taps, which leads to an appreciable decrease in the pressure tap reading.
An initial investigation into methods of computing transonic aerodynamic sensitivity coefficients
NASA Technical Reports Server (NTRS)
Carlson, Leland A.
1992-01-01
Research conducted during the period from July 1991 through December 1992 is covered. A method based upon the quasi-analytical approach was developed for computing the aerodynamic sensitivity coefficients of three dimensional wings in transonic and subsonic flow. In addition, the method computes for comparison purposes the aerodynamic sensitivity coefficients using the finite difference approach. The accuracy and validity of the methods are currently under investigation.
NASA Technical Reports Server (NTRS)
Yates, E. Carson, Jr.; Desmarais, Robert N.
1990-01-01
The technique of implicit differentiation has been used in combination with linearized lifting-surface theory to derive analytical expressions for aerodynamic sensitivities (i.e., rates of change of lifting pressures with respect to general changes in aircraft geometry, including planform variations) for steady or oscillating planar or nonplanar lifting surfaces in subsonic, sonic, or supersonic flow. The geometric perturbation is defined in terms of a single variable, and the user need only provide simple expressions or similar means for defining the continuous or discontinuous global or local perturbation of interest. Example expressions are given for perturbations of the sweep, taper, and aspect ratio of a wing with trapezoidal semispan planform. The present process appears to be readily adaptable to more general surface-panel methods.
NASA Technical Reports Server (NTRS)
Elbanna, Hesham M.; Carlson, Leland A.
1992-01-01
The quasi-analytical approach is applied to the three-dimensional full potential equation to compute wing aerodynamic sensitivity coefficients in the transonic regime. Symbolic manipulation is used to reduce the effort associated with obtaining the sensitivity equations, and the large sensitivity system is solved using 'state of the art' routines. Results are compared to those obtained by the direct finite difference approach and both methods are evaluated to determine their computational accuracy and efficiency. The quasi-analytical approach is shown to be accurate and efficient for large aerodynamic systems.
Preconditioned domain decomposition scheme for three-dimensional aerodynamic sensitivity analysis
NASA Technical Reports Server (NTRS)
Eleshaky, Mohammed E.; Baysal, Oktay
1993-01-01
A preconditioned domain decomposition scheme is introduced for the solution of the 3D aerodynamic sensitivity equation. This scheme uses the iterative GMRES procedure to solve the effective sensitivity equation of the boundary-interface cells in the sensitivity analysis domain-decomposition scheme. Excluding the dense matrices and the effect of cross terms between boundary-interfaces is found to produce an efficient preconditioning matrix.
Coupled Aerodynamic and Structural Sensitivity Analysis of a High-Speed Civil Transport
NASA Technical Reports Server (NTRS)
Mason, B. H.; Walsh, J. L.
2001-01-01
An objective of the High Performance Computing and Communication Program at the NASA Langley Research Center is to demonstrate multidisciplinary shape and sizing optimization of a complete aerospace vehicle configuration by using high-fidelity, finite-element structural analysis and computational fluid dynamics aerodynamic analysis. In a previous study, a multi-disciplinary analysis system for a high-speed civil transport was formulated to integrate a set of existing discipline analysis codes, some of them computationally intensive, This paper is an extension of the previous study, in which the sensitivity analysis for the coupled aerodynamic and structural analysis problem is formulated and implemented. Uncoupled stress sensitivities computed with a constant load vector in a commercial finite element analysis code are compared to coupled aeroelastic sensitivities computed by finite differences. The computational expense of these sensitivity calculation methods is discussed.
NASA Astrophysics Data System (ADS)
Dyadkin, A. A.; Khatuntseva, O. N.
2014-12-01
Analysis of experimental data shows that the nature of the oscillating motion of an aircraft does not depend uniquely on the value of the coefficients of aerodynamic damping derivatives. The present work makes an attempt to explain this phenomenon and develops a methodology to adequately characterize the oscillating motion of aircraft based on the analysis of the coefficients of aerodynamic damping derivatives.
Recent advances in steady compressible aerodynamic sensitivity analysis
NASA Technical Reports Server (NTRS)
Taylor, Arthur C., III; Newman, Perry A.; Hou, Gene J.-W.; Jones, Henry E.
1992-01-01
Sensitivity analysis methods are classified as belonging to either of the two broad categories: the discrete (quasi-analytical) approach and the continuous approach. The two approaches differ by the order in which discretization and differentiation of the governing equations and boundary conditions is undertaken. The discussion focuses on the discrete approach. Basic equations are presented, and the major difficulties are reviewed in some detail, as are the proposed solutions. Recent research activity concerned with the continuous approach is also discussed.
NASA Technical Reports Server (NTRS)
Lyle, Karen H.
2014-01-01
Acceptance of new spacecraft structural architectures and concepts requires validated design methods to minimize the expense involved with technology validation via flighttesting. This paper explores the implementation of probabilistic methods in the sensitivity analysis of the structural response of a Hypersonic Inflatable Aerodynamic Decelerator (HIAD). HIAD architectures are attractive for spacecraft deceleration because they are lightweight, store compactly, and utilize the atmosphere to decelerate a spacecraft during re-entry. However, designers are hesitant to include these inflatable approaches for large payloads or spacecraft because of the lack of flight validation. In the example presented here, the structural parameters of an existing HIAD model have been varied to illustrate the design approach utilizing uncertainty-based methods. Surrogate models have been used to reduce computational expense several orders of magnitude. The suitability of the design is based on assessing variation in the resulting cone angle. The acceptable cone angle variation would rely on the aerodynamic requirements.
Aerodynamic parameter studies and sensitivity analysis for rotor blades in axial flight
NASA Technical Reports Server (NTRS)
Chiu, Y. Danny; Peters, David A.
1991-01-01
The analytical capability is offered for aerodynamic parametric studies and sensitivity analyses of rotary wings in axial flight by using a 3-D undistorted wake model in curved lifting line theory. The governing equations are solved by both the Multhopp Interpolation technique and the Vortex Lattice method. The singularity from the bound vortices is eliminated through the Hadamard's finite part concept. Good numerical agreement between both analytical methods and finite differences methods are found. Parametric studies were made to assess the effects of several shape variables on aerodynamic loads. It is found, e.g., that a rotor blade with out-of-plane and inplane curvature can theoretically increase lift in the inboard and outboard regions respectively without introducing an additional induced drag.
NASA Technical Reports Server (NTRS)
Taylor, Arthur C., III; Newman, James C., III; Barnwell, Richard W.
1997-01-01
A three-dimensional unstructured grid approach to aerodynamic shape sensitivity analysis and design optimization has been developed and is extended to model geometrically complex configurations. The advantage of unstructured grids (when compared with a structured-grid approach) is their inherent ability to discretize irregularly shaped domains with greater efficiency and less effort. Hence, this approach is ideally suited for geometrically complex configurations of practical interest. In this work the nonlinear Euler equations are solved using an upwind, cell-centered, finite-volume scheme. The discrete, linearized systems which result from this scheme are solved iteratively by a preconditioned conjugate-gradient-like algorithm known as GMRES for the two-dimensional geometry and a Gauss-Seidel algorithm for the three-dimensional; similar procedures are used to solve the accompanying linear aerodynamic sensitivity equations in incremental iterative form. As shown, this particular form of the sensitivity equation makes large-scale gradient-based aerodynamic optimization possible by taking advantage of memory efficient methods to construct exact Jacobian matrix-vector products. Simple parameterization techniques are utilized for demonstrative purposes. Once the surface has been deformed, the unstructured grid is adapted by considering the mesh as a system of interconnected springs. Grid sensitivities are obtained by differentiating the surface parameterization and the grid adaptation algorithms with ADIFOR (which is an advanced automatic-differentiation software tool). To demonstrate the ability of this procedure to analyze and design complex configurations of practical interest, the sensitivity analysis and shape optimization has been performed for a two-dimensional high-lift multielement airfoil and for a three-dimensional Boeing 747-200 aircraft.
NASA Astrophysics Data System (ADS)
Oloso, Amidu Olawale
A hybrid automatic differentiation/incremental iterative method was implemented in the general purpose advanced computational fluid dynamics code (CFL3D Version 4.1) to yield a new code (CFL3D.ADII) that is capable of computing consistently discrete first order sensitivity derivatives for complex geometries. With the exception of unsteady problems, the new code retains all the useful features and capabilities of the original CFL3D flow analysis code. The superiority of the new code over a carefully applied method of finite-differences is demonstrated. A coarse grain, scalable, distributed-memory, parallel version of CFL3D.ADII was developed based on "derivative stripmining". In this data-parallel approach, an identical copy of CFL3D.ADII is executed on each processor with different derivative input files. The effect of communication overhead on the overall parallel computational efficiency is negligible. However, the fraction of CFL3D.ADII duplicated on all processors has significant impact on the computational efficiency. To reduce the large execution time associated with the sequential 1-D line search in gradient-based aerodynamic optimization, an alternative parallel approach was developed. The execution time of the new approach was reduced effectively to that of one flow analysis, regardless of the number of function evaluations in the 1-D search. The new approach was found to yield design results that are essentially identical to those obtained from the traditional sequential approach but at much smaller execution time. The parallel CFL3D.ADII and the parallel 1-D line search are demonstrated in shape improvement studies of a realistic High Speed Civil Transport (HSCT) wing/body configuration represented by over 100 design variables and 200,000 grid points in inviscid supersonic flow on the 16 node IBM SP2 parallel computer at the Numerical Aerospace Simulation (NAS) facility, NASA Ames Research Center. In addition to making the handling of such a large
Supersonic aerodynamic characteristics of an advanced F-16 derivative aircraft configuration
NASA Technical Reports Server (NTRS)
Fox, Mike C.; Forrest, Dana K.
1993-01-01
A supersonic wind tunnel investigation was conducted in the NASA Langley Unitary Plan Wind Tunnel on an advanced derivative configuration of the United States Air Force F-16 fighter. Longitudinal and lateral directional force and moment data were obtained at Mach numbers of 1.60 to 2.16 to evaluate basic performance parameters and control effectiveness. The aerodynamic characteristics for the F-16 derivative model were compared with the data obtained for the F-16C model and also with a previously tested generic wing model that features an identical plan form shape and similar twist distribution.
NASA Technical Reports Server (NTRS)
Campbell, John P; Mckinney, Marion O
1952-01-01
A summary of methods for making dynamic lateral stability and response calculations and for estimating the aerodynamic stability derivatives required for use in these calculations is presented. The processes of performing calculations of the time histories of lateral motions, of the period and damping of these motions, and of the lateral stability boundaries are presented as a series of simple straightforward steps. Existing methods for estimating the stability derivatives are summarized and, in some cases, simple new empirical formulas are presented. Detailed estimation methods are presented for low-subsonic-speed conditions but only a brief discussion and a list of references are given for transonic and supersonic speed conditions.
NASA Technical Reports Server (NTRS)
Nielsen, Jack N.
1988-01-01
The fundamental aerodynamics of slender bodies is examined in the reprint edition of an introductory textbook originally published in 1960. Chapters are devoted to the formulas commonly used in missile aerodynamics; slender-body theory at supersonic and subsonic speeds; vortices in viscid and inviscid flow; wing-body interference; downwash, sidewash, and the wake; wing-tail interference; aerodynamic controls; pressure foredrag, base drag, and skin friction; and stability derivatives. Diagrams, graphs, tables of terms and formulas are provided.
NASA Astrophysics Data System (ADS)
Cochrane, Alexander P.; Merrett, Craig G.; Hilton, Harry H.
2014-12-01
The advent of new structural concepts employing composites in primary load carrying aerospace structures in UAVs, MAVs, Boeing 787s, Airbus A380s, etc., necessitates the inclusion of flexibility as well as viscoelasticity in static structural and aero-viscoelastic analyses. Differences and similarities between aeroelasticity and aero-viscoelasticity have been investigated in [2]. An investigation is undertaken as to the dependence and sensitivity of aerodynamic and stability derivatives to elastic and viscoelastic structural flexibility and as to time dependent flight and maneuver velocities. Longitudinal, lateral and directional stabilities are investigated. It has been a well established fact that elastic lifting surfaces are subject to loss of control effectiveness and control reversal at certain flight speeds, which depend on aerodynamic, structural and material properties [5]. Such elastic analyses are extended to linear viscoelastic materials under quasi-static, dynamic, and sudden and gradual loading conditions. In elastic wings one of the critical static parameters is the velocity at which control reversal takes place (VREVE). Since elastic formulations constitute viscoelastic initial conditions, viscoelastic reversal may occur at speeds VREV<≧VREVE, but furthermore does so in time at 0 < tREV ≤ ∞. The influence of the twin effects of viscoelastic and elastic materials and of variable flight velocities on longitudinal, lateral, directional and spin stabilities are also investigated. It has been a well established fact that elastic lifting surfaces are subject to loss of control effectiveness and control reversal at certain flight speeds, which depend on aerodynamic, structural and material properties [5]. Such elastic analyses are here extended to linear viscoelastic materials under quasi-static, dynamic, and sudden and gradual loading conditions. In elastic wings the critical parameter is the velocity at which control reversal takes place (VREVE
Cochrane, Alexander P.; Merrett, Craig G.; Hilton, Harry H.
2014-12-10
The advent of new structural concepts employing composites in primary load carrying aerospace structures in UAVs, MAVs, Boeing 787s, Airbus A380s, etc., necessitates the inclusion of flexibility as well as viscoelasticity in static structural and aero-viscoelastic analyses. Differences and similarities between aeroelasticity and aero-viscoelasticity have been investigated in [2]. An investigation is undertaken as to the dependence and sensitivity of aerodynamic and stability derivatives to elastic and viscoelastic structural flexibility and as to time dependent flight and maneuver velocities. Longitudinal, lateral and directional stabilities are investigated. It has been a well established fact that elastic lifting surfaces are subject to loss of control effectiveness and control reversal at certain flight speeds, which depend on aerodynamic, structural and material properties [5]. Such elastic analyses are extended to linear viscoelastic materials under quasi-static, dynamic, and sudden and gradual loading conditions. In elastic wings one of the critical static parameters is the velocity at which control reversal takes place (V{sub REV}{sup E}). Since elastic formulations constitute viscoelastic initial conditions, viscoelastic reversal may occur at speeds V{sub REV<}{sup ≧}V{sub REV}{sup E}, but furthermore does so in time at 0 < t{sub REV} ≤ ∞. The influence of the twin effects of viscoelastic and elastic materials and of variable flight velocities on longitudinal, lateral, directional and spin stabilities are also investigated. It has been a well established fact that elastic lifting surfaces are subject to loss of control effectiveness and control reversal at certain flight speeds, which depend on aerodynamic, structural and material properties [5]. Such elastic analyses are here extended to linear viscoelastic materials under quasi-static, dynamic, and sudden and gradual loading conditions. In elastic wings the critical parameter is the velocity at
NASA Astrophysics Data System (ADS)
Weibust, E.
Improvements to a missile aerodynamics program which enable it to (a) calculate aerodynamic coefficients as input for a flight mechanics model, (b) check manufacturers' data or estimate performance from photographs, (c) reduce wind tunnel testing, and (d) aid optimization studies, are discussed. Slender body theory is used for longitudinal damping derivatives prediction. Program predictions were compared to known values. Greater accuracy is required in the estimation of drag due to excrescences on actual missile configurations, the influence of a burning motor, and nonlinear effects in the stall region. Prediction of pressure centers on wings and on bodies in presence of wings must be improved.
NASA Technical Reports Server (NTRS)
Hodge, W. F.
1980-01-01
Flight tests for verifying an analytical aerodynamic derivative model of a CH-47 helicopter were conducted for low cruise speeds and transition to hover portions of curved, decelerating landing approach trajectories. All testing was performed on a closed loop basis with the stability augmentation system of the helicopter operating, and response data were obtained using both manual and computer generated input maneuvers. The results indicate some differences between the measured response time histories and those predicted by both analytical and flight test identified derivatives. With some exceptions the discrepancies are not severe, and the overall agreement between the measured and computed time histories is reasonably good. No adverse effects attributable to closed loop testing were noted, and the use of computer generated inputs proved to be superior to manual ones.
NASA Technical Reports Server (NTRS)
Kempel, R. W.; Thompson, R. C.
1971-01-01
Aerodynamic derivatives were obtained for the M2-F2 lifting body flight vehicle in the subsonic flight region between Mach numbers of 0.41 and 0.64 and altitudes of 7000 feet to 45,000 feet. The derivatives were determined by a flight time history curve-fitting process utilizing a hybrid computer. The flight-determined derivatives are compared with wind-tunnel and predicted values. Modal-response characteristics, calculated from the flight derivatives, are presented.
Aerodynamic shape optimization directed toward a supersonic transport using sensitivity analysis
NASA Technical Reports Server (NTRS)
Baysal, Oktay
1995-01-01
This investigation was conducted from March 1994 to August 1995, primarily, to extend and implement the previously developed aerodynamic design optimization methodologies for the problems related to a supersonic transport design. These methods had demonstrated promise to improve the designs (more specifically, the shape) of aerodynamic surfaces, by coupling optimization algorithms (OA) with Computational Fluid Dynamics (CFD) algorithms via sensitivity analyses (SA) with surface definition methods from Computer Aided Design (CAD). The present extensions of this method and their supersonic implementations have produced wing section designs, delta wing designs, cranked-delta wing designs, and nacelle designs, all of which have been reported in the open literature. Despite the fact that these configurations were highly simplified to be of any practical or commercial use, they served the algorithmic and proof-of-concept objectives of the study very well. The primary cause for the configurational simplifications, other than the usual simplify-to-study the fundamentals reason, were the premature closing of the project. Only after the first of the originally intended three-year term, both the funds and the computer resources supporting the project were abruptly cut due to their severe shortages at the funding agency. Nonetheless, it was shown that the extended methodologies could be viable options in optimizing the design of not only an isolated single-component configuration, but also a multiple-component configuration in supersonic and viscous flow. This allowed designing with the mutual interference of the components being one of the constraints all along the evolution of the shapes.
NASA Technical Reports Server (NTRS)
Riley, Donald C.
2015-01-01
This paper contains a collection of some results of four individual studies presenting calculated numerical values for airfoil aerodynamic stability derivatives in unseparated inviscid incompressible flow due separately to angle-of-attack, pitch rate, flap deflection, and airfoil camber using a discrete vortex method. Both steady conditions and oscillatory motion were considered. Variables include the number of vortices representing the airfoil, the pitch axis / moment center chordwise location, flap chord to airfoil chord ratio, and circular or parabolic arc camber. Comparisons with some experimental and other theoretical information are included. The calculated aerodynamic numerical results obtained using a limited number of vortices provided in each study compared favorably with thin airfoil theory predictions. Of particular interest are those aerodynamic results calculated herein (such as induced drag) that are not readily available elsewhere.
NASA Technical Reports Server (NTRS)
Roskam, J.
1972-01-01
Expressions are derived for computing the aerodynamic influence coefficient matrix for nonplanar wing-body-tail configurations. An aerodynamic influence coefficient is defined as the load in lbs. induced on a panel as a result of a unit angle of attack on another panel. Fuselage, wing and tail thickness are assumed to be small with the result that the thickness effect on the flow-field is negligible. The method for determining the aerodynamic influence coefficient matrix is based on the lifting solution to the small perturbation, steady potential flow equation.
NASA Technical Reports Server (NTRS)
1983-01-01
Analytical design and wind tunnel test evaluations covering the feasibility of applying wing tip extensions, winglets, and active control wing had alleviation to the model B747 are described. Aerodynamic improvement offered by wing tip extension and winglet individually, and the combined aerodynamic and weight improvements when wing load alleviation is combined with the tip extension or the winglet are evaluated. Results are presented in the form of incremental effects on weight mission range, fuel usage, cost, and airline operating economics.
Computation of Sensitivity Derivatives of Navier-Stokes Equations using Complex Variables
NASA Technical Reports Server (NTRS)
Vatsa, Veer N.
2004-01-01
Accurate computation of sensitivity derivatives is becoming an important item in Computational Fluid Dynamics (CFD) because of recent emphasis on using nonlinear CFD methods in aerodynamic design, optimization, stability and control related problems. Several techniques are available to compute gradients or sensitivity derivatives of desired flow quantities or cost functions with respect to selected independent (design) variables. Perhaps the most common and oldest method is to use straightforward finite-differences for the evaluation of sensitivity derivatives. Although very simple, this method is prone to errors associated with choice of step sizes and can be cumbersome for geometric variables. The cost per design variable for computing sensitivity derivatives with central differencing is at least equal to the cost of three full analyses, but is usually much larger in practice due to difficulty in choosing step sizes. Another approach gaining popularity is the use of Automatic Differentiation software (such as ADIFOR) to process the source code, which in turn can be used to evaluate the sensitivity derivatives of preselected functions with respect to chosen design variables. In principle, this approach is also very straightforward and quite promising. The main drawback is the large memory requirement because memory use increases linearly with the number of design variables. ADIFOR software can also be cumber-some for large CFD codes and has not yet reached a full maturity level for production codes, especially in parallel computing environments.
Fast computation of derivative based sensitivities of PSHA models via algorithmic differentiation
NASA Astrophysics Data System (ADS)
Leövey, Hernan; Molkenthin, Christian; Scherbaum, Frank; Griewank, Andreas; Kuehn, Nicolas; Stafford, Peter
2015-04-01
Probabilistic seismic hazard analysis (PSHA) is the preferred tool for estimation of potential ground-shaking hazard due to future earthquakes at a site of interest. A modern PSHA represents a complex framework which combines different models with possible many inputs. Sensitivity analysis is a valuable tool for quantifying changes of a model output as inputs are perturbed, identifying critical input parameters and obtaining insight in the model behavior. Differential sensitivity analysis relies on calculating first-order partial derivatives of the model output with respect to its inputs. Moreover, derivative based global sensitivity measures (Sobol' & Kucherenko '09) can be practically used to detect non-essential inputs of the models, thus restricting the focus of attention to a possible much smaller set of inputs. Nevertheless, obtaining first-order partial derivatives of complex models with traditional approaches can be very challenging, and usually increases the computation complexity linearly with the number of inputs appearing in the models. In this study we show how Algorithmic Differentiation (AD) tools can be used in a complex framework such as PSHA to successfully estimate derivative based sensitivities, as is the case in various other domains such as meteorology or aerodynamics, without no significant increase in the computation complexity required for the original computations. First we demonstrate the feasibility of the AD methodology by comparing AD derived sensitivities to analytically derived sensitivities for a basic case of PSHA using a simple ground-motion prediction equation. In a second step, we derive sensitivities via AD for a more complex PSHA study using a ground motion attenuation relation based on a stochastic method to simulate strong motion. The presented approach is general enough to accommodate more advanced PSHA studies of higher complexity.
An incremental strategy for calculating consistent discrete CFD sensitivity derivatives
NASA Technical Reports Server (NTRS)
Korivi, Vamshi Mohan; Taylor, Arthur C., III; Newman, Perry A.; Hou, Gene W.; Jones, Henry E.
1992-01-01
In this preliminary study involving advanced computational fluid dynamic (CFD) codes, an incremental formulation, also known as the 'delta' or 'correction' form, is presented for solving the very large sparse systems of linear equations which are associated with aerodynamic sensitivity analysis. For typical problems in 2D, a direct solution method can be applied to these linear equations which are associated with aerodynamic sensitivity analysis. For typical problems in 2D, a direct solution method can be applied to these linear equations in either the standard or the incremental form, in which case the two are equivalent. Iterative methods appear to be needed for future 3D applications; however, because direct solver methods require much more computer memory than is currently available. Iterative methods for solving these equations in the standard form result in certain difficulties, such as ill-conditioning of the coefficient matrix, which can be overcome when these equations are cast in the incremental form; these and other benefits are discussed. The methodology is successfully implemented and tested in 2D using an upwind, cell-centered, finite volume formulation applied to the thin-layer Navier-Stokes equations. Results are presented for two laminar sample problems: (1) transonic flow through a double-throat nozzle; and (2) flow over an isolated airfoil.
NASA Technical Reports Server (NTRS)
Findlay, J. T.; Compton, H. R.
1983-01-01
Aerodynamic performance data from the first four Shuttle reentry flights are compared with preflight predictions covering hypersonic longitudinal mode down to Mach 2. The extraction of the flight coefficients, as measured by the spacecraft angular rates and the linear accelerations, derived from the inertial measurement unit, the best estimate trajectory, and the remotely measured atmosphere are discussed. The ground predictions were developed from 30,000 hr of wind tunnel testing. Actual flight data are presented for 80-260 kft, from Mach 2-26, comprising the dynamic pressure, the vehicle air relative attitude angles, control surface deflections, reaction jet activity, and body axis rates and accelerations. The second and fourth flights gave results which deviated from predictions between 230-260 kft. The accuracy limits of the derived atmospheric densities are considered, together with potential data base updates in the light of limitations imposed on the corrections by available flight data.
NASA Technical Reports Server (NTRS)
1980-01-01
The feasibility of applying wing tip extensions, winglets, and active control wing load alleviation to the Boeing 747 is investigated. Winglet aerodynamic design methods and high speed wind tunnel test results of winglets and of symmetrically deflected ailerons are presented. Structural resizing analyses to determine weight and aeroelastic twist increments for all the concepts and flutter model test results for the wing with winglets are included. Control law development, system mechanization/reliability studies, and aileron balance tab trade studies for active wing load alleviation systems are discussed. Results are presented in the form of incremental effects on L/D, structural weight, block fuel savings, stability and control, airplane price, and airline operating economics.
Experimental Aerodynamic Derivatives of a Sinusoidally Oscillating Airfoil in Two-Dimensional Flow
NASA Technical Reports Server (NTRS)
Halfman, Robert L
1952-01-01
Experimental measurements of the aerodynamic reactions on a symmetrical airfoil oscillating harmonically in a two-dimensional flow are presented and analyzed. Harmonic motions include pure pitch and pure translation, for several amplitudes and superimposed on an initial angle of attack, as well as combined pitch and translation. The apparatus and testing program are described briefly and the necessary theoretical background is presented. In general, the experimental results agree remarkably well with the theory, especially in the case of the pure motions. The net work per cycle for a motion corresponding to flutter is experimentally determined to be zero. Considerable consistent data for pure pitch were obtained from a search of available reference material, and several definite Reynolds number effects are evident.
Aerodynamic roughness of ice surfaces derived from high resolution topographic data
NASA Astrophysics Data System (ADS)
Smith, Mark; Quincey, Duncan; Dixon, Timothy; Bingham, Robert; Carrivick, Jonathan; Irvine-Fynn, Tristram; Rippin, David
2016-04-01
The aerodynamic roughness of glacier surfaces is an important component of energy balance models and meltwater runoff estimates through its influence on turbulent fluxes of latent and sensible heat. In a warming climate these fluxes are predicted to become more significant in contributing to overall melt volumes. Ice aerodynamic roughness (z0) is commonly estimated from measurements of ice surface microtopography, typically from topographic profiles taken perpendicular to the prevailing wind direction. Recent advances in surveying permit rapid acquisition of high resolution topographic data allowing revision of assumptions underlying conventional topographic profile-based z0 measurement. This poster presents alternative methods of estimating z0 directly from Digital Elevation Models (DEMs) or three-dimensional point clouds, and examines the spatial and temporal variability of z0 across the ablation zone of a small Arctic glacier. Using Structure-from-Motion (SfM) photogrammetry to survey ice surfaces with millimeter-scale accuracy, z0 variation over three orders of magnitude was observed but was unrelated to large scale topographic variables such as elevation or slope. Different surface-types demonstrated different temporal trajectories in z0 through three days of intense melt, though the observed temporal z0 variability was lower than the spatial variability. A glacier-scale topographic model was obtained through Terrestrial Laser Scanning (TLS) and sub-grid roughness was significantly related to z0 calculated from a 2 m resolution DEM. Thus, glacier scale TLS or SfM surveys can characterize z0 variability over a glacier surface and allow distributed representations of z0 in surface energy balance models.
Aerodynamic roughness of glacial ice surfaces derived from high-resolution topographic data
NASA Astrophysics Data System (ADS)
Smith, Mark W.; Quincey, Duncan J.; Dixon, Timothy; Bingham, Robert G.; Carrivick, Jonathan L.; Irvine-Fynn, Tristram D. L.; Rippin, David M.
2016-04-01
This paper presents new methods of estimating the aerodynamic roughness (z0) of glacier ice directly from three-dimensional point clouds and digital elevation models (DEMs), examines temporal variability of z0, and presents the first fully distributed map of z0 estimates across the ablation zone of an Arctic glacier. The aerodynamic roughness of glacier ice surfaces is an important component of energy balance models and meltwater runoff estimates through its influence on turbulent fluxes of latent and sensible heat. In a warming climate these fluxes are predicted to become more significant in contributing to overall melt volumes. Ice z0 is commonly estimated from measurements of ice surface microtopography, typically from topographic profiles taken perpendicular to the prevailing wind direction. Recent advances in surveying permit rapid acquisition of high-resolution topographic data allowing revision of assumptions underlying conventional z0 measurement. Using Structure from Motion (SfM) photogrammetry with Multi-View Stereo (MVS) to survey ice surfaces with millimeter-scale accuracy, z0 variation over 3 orders of magnitude was observed. Different surface types demonstrated different temporal trajectories in z0 through 3 days of intense melt. A glacier-scale 2 m resolution DEM was obtained through terrestrial laser scanning (TLS), and subgrid roughness was significantly related to plot-scale z0. Thus, we show for the first time that glacier-scale TLS or SfM-MVS surveys can characterize z0 variability over a glacier surface potentially leading to distributed representations of z0 in surface energy balance models.
An initial investigation into methods of computing transonic aerodynamic sensitivity coefficients
NASA Technical Reports Server (NTRS)
Carlson, Leland A.
1991-01-01
The three dimensional quasi-analytical sensitivity analysis and the ancillary driver programs are developed needed to carry out the studies and perform comparisons. The code is essentially contained in one unified package which includes the following: (1) a three dimensional transonic wing analysis program (ZEBRA); (2) a quasi-analytical portion which determines the matrix elements in the quasi-analytical equations; (3) a method for computing the sensitivity coefficients from the resulting quasi-analytical equations; (4) a package to determine for comparison purposes sensitivity coefficients via the finite difference approach; and (5) a graphics package.
NASA Astrophysics Data System (ADS)
Miles, Evan; Steiner, Jakob; Brun, Fanny; Detert, Martin; Buri, Pascal; Pellicciotti, Francesca
2016-04-01
Aerodynamic surface roughness is an essential parameter in surface energy balance studies. While actual measurements on bare ice glaciers are rare, a wide range of literature values exist for ice and snow surfaces. There are very few values suggested for debris covered glaciers and actual measurements are even scarcer - studies instead optimize z0 or use a reference value. The increased use of photogrammetry on glaciers provides an opportunity to characterize the range of z0 values meaningful for debris-covered glaciers. We apply Agisoft's Structure-from-Motion process chain to produce high resolution DEMs for five 1m x 1m plots (1mm resolution) with differing grain-size distributions, as well as a large ~180m x ~180m depression (5cm) on Lirung Glacier in the Nepalese Himalayas. For each plot, we calculate z0 according to transect-based microtopographic parameterisations. We compare individual-transect z0 estimates based on profile position and direction, and develop a grid version of the algorithms aggregating height data from all bidirectional transects. This grid approach is applied to our larger DEM to characterize the variability of z0 across the study site for each algorithm. For the plot DEMs, z0 estimated by any algorithm varies by an order of magnitude based on transect position. Although the algorithms reproduce the same variability among transects and plots, z0 estimates vary by an order of magnitude between algorithms. For any algorithm, however, we find minimal difference between cross- and down-glacier profile directions. At the basin scale, results from different algorithms are strongly correlated and results are more closely clustered with the exception of the Rounce (2015) algorithm, while any algorithm's values range by two orders of magnitude across the study depression. The Rounce algorithm consistently produced the highest z0 values, while the Lettau (1969) and Munro (1989) methods produced the lowest values, and use of the Nield (2013
Sensitivity of aerodynamic forces in laminar and turbulent flow past a square cylinder
NASA Astrophysics Data System (ADS)
Meliga, Philippe; Boujo, Edouard; Pujals, Gregory; Gallaire, François
2014-10-01
We use adjoint-based gradients to analyze the sensitivity of the drag force on a square cylinder. At Re = 40, the flow settles down to a steady state. The quantity of interest in the adjoint formulation is the steady asymptotic value of drag reached after the initial transient, whose sensitivity is computed solving a steady adjoint problem from knowledge of the stable base solution. At Re = 100, the flow develops to the time-periodic, vortex-shedding state. The quantity of interest is rather the time-averaged mean drag, whose sensitivity is computed integrating backwards in time an unsteady adjoint problem from knowledge of the entire history of the vortex-shedding solution. Such theoretical frameworks allow us to identify the sensitive regions without computing the actually controlled states, and provide a relevant and systematic guideline on where in the flow to insert a secondary control cylinder in the attempt to reduce drag, as established from comparisons with dedicated numerical simulations of the two-cylinder system. For the unsteady case at Re = 100, we also compute an approximation to the mean drag sensitivity solving a steady adjoint problem from knowledge of only the mean flow solution, and show the approach to carry valuable information in view of guiding relevant control strategy, besides reducing tremendously the related numerical effort. An extension of this simplified framework to turbulent flow regime is examined revisiting the widely benchmarked flow at Reynolds number Re = 22 000, the theoretical predictions obtained in the frame of unsteady Reynolds-averaged Navier-Stokes modeling being consistent with experimental data from the literature. Application of the various sensitivity frameworks to alternative control objectives such as increasing the lift and reducing the fluctuating drag and lift is also discussed and illustrated with a few selected examples.
Evolution of Geometric Sensitivity Derivatives from Computer Aided Design Models
NASA Technical Reports Server (NTRS)
Jones, William T.; Lazzara, David; Haimes, Robert
2010-01-01
The generation of design parameter sensitivity derivatives is required for gradient-based optimization. Such sensitivity derivatives are elusive at best when working with geometry defined within the solid modeling context of Computer-Aided Design (CAD) systems. Solid modeling CAD systems are often proprietary and always complex, thereby necessitating ad hoc procedures to infer parameter sensitivity. A new perspective is presented that makes direct use of the hierarchical associativity of CAD features to trace their evolution and thereby track design parameter sensitivity. In contrast to ad hoc methods, this method provides a more concise procedure following the model design intent and determining the sensitivity of CAD geometry directly to its respective defining parameters.
NASA Technical Reports Server (NTRS)
Ranaudo, R. J.; Batterson, J. G.; Reehorst, A. L.; Bond, T. H.; Omara, T. M.
1989-01-01
A flight test was performed with the NASA Lewis Research Center's DH-6 icing research aircraft. The purpose was to employ a flight test procedure and data analysis method, to determine the accuracy with which the effects of ice on aircraft stability and control could be measured. For simplicity, flight testing was restricted to the short period longitudinal mode. Two flights were flown in a clean (baseline) configuration, and two flights were flown with simulated horizontal tail ice. Forty-five repeat doublet maneuvers were performed in each of four test configurations, at a given trim speed, to determine the ensemble variation of the estimated stability and control derivatives. Additional maneuvers were also performed in each configuration, to determine the variation in the longitudinal derivative estimates over a wide range of trim speeds. Stability and control derivatives were estimated by a Modified Stepwise Regression (MSR) technique. A measure of the confidence in the derivative estimates was obtained by comparing the standard error for the ensemble of repeat maneuvers, to the average of the estimated standard errors predicted by the MSR program. A multiplicative relationship was determined between the ensemble standard error, and the averaged program standard errors. In addition, a 95 percent confidence interval analysis was performed for the elevator effectiveness estimates, C sub m sub delta e. This analysis identified the speed range where changes in C sub m sub delta e could be attributed to icing effects. The magnitude of icing effects on the derivative estimates were strongly dependent on flight speed and aircraft wing flap configuration. With wing flaps up, the estimated derivatives were degraded most at lower speeds corresponding to that configuration. With wing flaps extended to 10 degrees, the estimated derivatives were degraded most at the higher corresponding speeds. The effects of icing on the changes in longitudinal stability and control
Integrated structural-aerodynamic design optimization
NASA Technical Reports Server (NTRS)
Haftka, R. T.; Kao, P. J.; Grossman, B.; Polen, D.; Sobieszczanski-Sobieski, J.
1988-01-01
This paper focuses on the processes of simultaneous aerodynamic and structural wing design as a prototype for design integration, with emphasis on the major difficulty associated with multidisciplinary design optimization processes, their enormous computational costs. Methods are presented for reducing this computational burden through the development of efficient methods for cross-sensitivity calculations and the implementation of approximate optimization procedures. Utilizing a modular sensitivity analysis approach, it is shown that the sensitivities can be computed without the expensive calculation of the derivatives of the aerodynamic influence coefficient matrix, and the derivatives of the structural flexibility matrix. The same process is used to efficiently evaluate the sensitivities of the wing divergence constraint, which should be particularly useful, not only in problems of complete integrated aircraft design, but also in aeroelastic tailoring applications.
On the Exploitation of Sensitivity Derivatives for Improving Sampling Methods
NASA Technical Reports Server (NTRS)
Cao, Yanzhao; Hussaini, M. Yousuff; Zang, Thomas A.
2003-01-01
Many application codes, such as finite-element structural analyses and computational fluid dynamics codes, are capable of producing many sensitivity derivatives at a small fraction of the cost of the underlying analysis. This paper describes a simple variance reduction method that exploits such inexpensive sensitivity derivatives to increase the accuracy of sampling methods. Three examples, including a finite-element structural analysis of an aircraft wing, are provided that illustrate an order of magnitude improvement in accuracy for both Monte Carlo and stratified sampling schemes.
NASA Astrophysics Data System (ADS)
Basart, Sara; Jorba, Oriol; Pérez García-Pando, Carlos; Prigent, Catherine; Baldasano, Jose M.
2014-05-01
Aeolian aerodynamic roughness length in arid regions is a key parameter to predict the vulnerability of the surface to wind erosion, and, as a consequence, the related production of mineral aerosol (e.g. Laurent et al., 2008). Recently, satellite-derived roughness length at the global scale have emerged and provide the opportunity to use them in advanced emission schemes in global and regional models (i.e. Menut et al., 2013). A global map of the aeolian aerodynamic roughness length at high resolution (6 km) is derived, for arid and semi-arid regions merging PARASOL and ASCAT data to estimate aeolian roughness length. It shows very good consistency with the existing information on the properties of these surfaces. The dataset is available to the community, for use in atmospheric dust transport models. The present contribution analyses the behaviour of the NMMB/BSC-Dust model (Pérez et al., 2011) when the ASCAT/PARASOL satellite-derived global roughness length (Prigent et al, 2012) and the State Soil Geographic database Food and Agriculture Organization of the United Nations (STATSGO-FAO) soil texture data set (based on wet techniques) is used. We explore the sensitivity of the drag partition scheme (a critical component of the dust emission scheme) and the dust vertical fluxes (intensity and spatial patterns) to the roughness length. An annual evaluation of NMMB/BSC-Dust (for the year 2011) over Northern Africa and the Middle East using observed aerosol optical depths (AODs) from Aerosol Robotic Network sites and aerosol satellite products (MODIS and MISR) will be discussed. Laurent, B., Marticorena, B., Bergametti, G., Leon, J. F., and Mahowald, N. M.: Modeling mineral dust emissions from the Sahara desert using new surface properties and soil database, J. Geophys. Res., 113, D14218, doi:10.1029/2007JD009484, 2008. Menut, L., C. Pérez, K. Haustein, B. Bessagnet, C. Prigent, and S. Alfaro, Impact of surface roughness and soil texture on mineral dust emission
NASA Technical Reports Server (NTRS)
Cockrell, Charles E., Jr.; Huebner, Lawrence D.; Finley, Dennis B.
1995-01-01
The component integration of a class of hypersonic high-lift configurations known as waveriders into hypersonic cruise vehicles was evaluated. A wind-tunnel model was developed which integrates realistic vehicle components with two waverider shapes, referred to as the straight-wing and cranked-wing shapes. Both shapes were conical-flow-derived waveriders for a design Mach number of 4.0. Experimental data and limited computational fluid dynamics (CFD) predictions were obtained over a Mach number range of 1.6 to 4.63 at a Reynolds number of 2.0 x 10(exp 6) per foot. The CFD predictions and flow visualization data confirmed the shock attachment characteristics of the baseline waverider shapes and illustrated the waverider flow-field properties. Experimental data showed that no significant performance degradations, in terms of maximum lift-to-drag ratios, occur at off-design Mach numbers for the waverider shapes and the integrated configurations. A comparison of the fully-integrated waverider vehicles to the baseline shapes showed that the performance was significantly degraded when all of the components were added to the waveriders, with the most significant degradation resulting from aftbody closure and the addition of control surfaces. Both fully-integrated configurations were longitudinally unstable over the Mach number range studied with the selected center of gravity location and for unpowered conditions. The cranked-wing configuration provided better lateral-directional stability characteristics than the straight-wing configuration.
Calculation of Sensitivity Derivatives in an MDAO Framework
NASA Technical Reports Server (NTRS)
Moore, Kenneth T.
2012-01-01
During gradient-based optimization of a system, it is necessary to generate the derivatives of each objective and constraint with respect to each design parameter. If the system is multidisciplinary, it may consist of a set of smaller "components" with some arbitrary data interconnection and process work ow. Analytical derivatives in these components can be used to improve the speed and accuracy of the derivative calculation over a purely numerical calculation; however, a multidisciplinary system may include both components for which derivatives are available and components for which they are not. Three methods to calculate the sensitivity of a mixed multidisciplinary system are presented: the finite difference method, where the derivatives are calculated numerically; the chain rule method, where the derivatives are successively cascaded along the system's network graph; and the analytic method, where the derivatives come from the solution of a linear system of equations. Some improvements to these methods, to accommodate mixed multidisciplinary systems, are also presented; in particular, a new method is introduced to allow existing derivatives to be used inside of finite difference. All three methods are implemented and demonstrated in the open-source MDAO framework OpenMDAO. It was found that there are advantages to each of them depending on the system being solved.
Reynolds number effects on the transonic aerodynamics of a slender wing-body configuration
NASA Technical Reports Server (NTRS)
Luckring, James M.; Fox, Charles H., Jr.; Cundiff, Jeffrey S.
1989-01-01
Aerodynamic forces and moments for a slender wing-body configuration are summarized from an investigation in the Langley National Transonic Facility (NTF). The results include both longitudinal and lateral-directional aerodynamic properties as well as slideslip derivatives. Results were selected to emphasize Reynolds number effects at a transonic speed although some lower speed results are also presented for context. The data indicate nominal Reynolds number effects on the longitudinal aerodynamic coefficients and more pronounced effects for the lateral-directional aerodynamic coefficients. The Reynolds number sensitivities for the lateral-directional coefficients were limited to high angles of attack.
NASA Technical Reports Server (NTRS)
Roskam, J.; Lan, C.; Mehrotra, S.
1972-01-01
The computer program used to determine the rigid and elastic stability derivatives presented in the summary report is listed in this appendix along with instructions for its use, sample input data and answers. This program represents the airplane at subsonic and supersonic speeds as (a) thin surface(s) (without dihedral) composed of discrete panels of constant pressure according to the method of Woodward for the aerodynamic effects and slender beam(s) for the structural effects. Given a set of input data, the computer program calculates an aerodynamic influence coefficient matrix and a structural influence coefficient matrix.
MacKinnon, D.J.; Clow, G.D.; Tigges, R.K.; Reynolds, R.L.; Chavez, P.S., Jr.
2004-01-01
The vulnerability of dryland surfaces to wind erosion depends importantly on the absence or the presence and character of surface roughness elements, such as plants, clasts, and topographic irregularities that diminish wind speed near the surface. A model for the friction velocity ratio has been developed to account for wind sheltering by many different types of co-existing roughness elements. Such conditions typify a monitored area in the central Mojave Desert, California, that experiences frequent sand movement and dust emission. Two additional models are used to convert the friction velocity ratio to the surface roughness length (zo) for momentum. To calculate roughness lengths from these models, measurements were made at 11 sites within the monitored area to characterize the surface roughness element. Measurements included (1) the number of roughness species (e.g., plants, small-scale topography, clasts), and their associated heights and widths, (2) spacing among species, and (3) vegetation porosity (a measurement of the spatial distribution of woody elements of a plant). Documented or estimated values of drag coefficients for different species were included in the modeling. At these sites, wind-speed profiles were measured during periods of neutral atmospheric stability using three 9-m towers with three or four calibrated anemometers on each. Modeled roughness lengths show a close correspondence (correlation coefficient, 0.84-0.86) to the aerodynamically determined values at the field sites. The geometric properties of the roughness elements in the model are amenable to measurement at much higher temporal and spatial resolutions using remote-sensing techniques than can be accomplished through laborious ground-based methods. A remote-sensing approach to acquire values of the modeled roughness length is particularly important for the development of linked surface/atmosphere wind-erosion models sensitive to climate variability and land-use changes in areas such
Parallel Calculation of Sensitivity Derivatives for Aircraft Design using Automatic Differentiation
NASA Technical Reports Server (NTRS)
Bischof, c. H.; Green, L. L.; Haigler, K. J.; Knauff, T. L., Jr.
1994-01-01
Sensitivity derivative (SD) calculation via automatic differentiation (AD) typical of that required for the aerodynamic design of a transport-type aircraft is considered. Two ways of computing SD via code generated by the ADIFOR automatic differentiation tool are compared for efficiency and applicability to problems involving large numbers of design variables. A vector implementation on a Cray Y-MP computer is compared with a coarse-grained parallel implementation on an IBM SP1 computer, employing a Fortran M wrapper. The SD are computed for a swept transport wing in turbulent, transonic flow; the number of geometric design variables varies from 1 to 60 with coupling between a wing grid generation program and a state-of-the-art, 3-D computational fluid dynamics program, both augmented for derivative computation via AD. For a small number of design variables, the Cray Y-MP implementation is much faster. As the number of design variables grows, however, the IBM SP1 becomes an attractive alternative in terms of compute speed, job turnaround time, and total memory available for solutions with large numbers of design variables. The coarse-grained parallel implementation also can be moved easily to a network of workstations.
Involute composite design evaluation using global design sensitivity derivatives
NASA Technical Reports Server (NTRS)
Hart, J. K.; Stanton, E. L.
1989-01-01
An optimization capability for involute structures has been developed. Its key feature is the use of global material geometry variables which are so chosen that all combinations of design variables within a set of lower and upper bounds correspond to manufacturable designs. A further advantage of global variables is that their number does not increase with increasing mesh density. The accuracy of the sensitivity derivatives has been verified both through finite difference tests and through the successful use of the derivatives by an optimizer. The state of the art in composite design today is still marked by point design algorithms linked together using ad hoc methods not directly related to a manufacturing procedure. The global design sensitivity approach presented here for involutes can be applied to filament wound shells and other composite constructions using material form features peculiar to each construction. The present involute optimization technology is being applied to the Space Shuttle SRM nozzle boot ring redesigns by PDA Engineering.
Sensitivity Equation Derivation for Transient Heat Transfer Problems
NASA Technical Reports Server (NTRS)
Hou, Gene; Chien, Ta-Cheng; Sheen, Jeenson
2004-01-01
The focus of the paper is on the derivation of sensitivity equations for transient heat transfer problems modeled by different discretization processes. Two examples will be used in this study to facilitate the discussion. The first example is a coupled, transient heat transfer problem that simulates the press molding process in fabrication of composite laminates. These state equations are discretized into standard h-version finite elements and solved by a multiple step, predictor-corrector scheme. The sensitivity analysis results based upon the direct and adjoint variable approaches will be presented. The second example is a nonlinear transient heat transfer problem solved by a p-version time-discontinuous Galerkin's Method. The resulting matrix equation of the state equation is simply in the form of Ax = b, representing a single step, time marching scheme. A direct differentiation approach will be used to compute the thermal sensitivities of a sample 2D problem.
NASA Technical Reports Server (NTRS)
Lan, C. E.; Mehrotra, S. C.; Fox, C. H., Jr.
1978-01-01
The necessary information for using a computer program to calculate the aerodynamic characteristics under symmetrical flight conditions and the lateral-directional stability derivatives of wing-body combinations with upper-surface-blowing (USB) or over-wing-blowing (OWB) jets are described. The following new features were added to the program: (1) a fuselage of arbitrary body of revolution has been included. The effect of wing-body interference can now be investigated, and (2) all nine lateral-directional stability derivatives can be calculated. The program is written in FORTRAN language and runs on CDC Cyber 175 and Honeywell 66/60 computers.
NASA Technical Reports Server (NTRS)
Taylor, Arthur C., III
2004-01-01
This final report will document the accomplishments of the work of this project. 1) The incremental-iterative (II) form of the reverse-mode (adjoint) method for computing first-order (FO) aerodynamic sensitivity derivatives (SDs) has been successfully implemented and tested in a 2D CFD code (called ANSERS) using the reverse-mode capability of ADIFOR 3.0. These preceding results compared very well with similar SDS computed via a black-box (BB) application of the reverse-mode capability of ADIFOR 3.0, and also with similar SDs calculated via the method of finite differences. 2) Second-order (SO) SDs have been implemented in the 2D ASNWERS code using the very efficient strategy that was originally proposed (but not previously tested) of Reference 3, Appendix A. Furthermore, these SO SOs have been validated for accuracy and computational efficiency. 3) Studies were conducted in Quasi-1D and 2D concerning the smoothness (or lack of smoothness) of the FO and SO SD's for flows with shock waves. The phenomenon is documented in the publications of this study (listed subsequently), however, the specific numerical mechanism which is responsible for this unsmoothness phenomenon was not discovered. 4) The FO and SO derivatives for Quasi-1D and 2D flows were applied to predict aerodynamic design uncertainties, and were also applied in robust design optimization studies.
Numerical Model Sensitivity to Heterogeneous Satellite Derived Vegetation Roughness
NASA Technical Reports Server (NTRS)
Jasinski, Michael; Eastman, Joseph; Borak, Jordan
2011-01-01
The sensitivity of a mesoscale weather prediction model to a 1 km satellite-based vegetation roughness initialization is investigated for a domain within the south central United States. Three different roughness databases are employed: i) a control or standard lookup table roughness that is a function only of land cover type, ii) a spatially heterogeneous roughness database, specific to the domain, that was previously derived using a physically based procedure and Moderate Resolution Imaging Spectroradiometer (MODIS) imagery, and iii) a MODIS climatologic roughness database that like (i) is a function only of land cover type, but possesses domain specific mean values from (ii). The model used is the Weather Research and Forecast Model (WRF) coupled to the Community Land Model within the Land Information System (LIS). For each simulation, a statistical comparison is made between modeled results and ground observations within a domain including Oklahoma, Eastern Arkansas, and Northwest Louisiana during a 4-day period within IHOP 2002. Sensitivity analysis compares the impact the three roughness initializations on time-series temperature, precipitation probability of detection (POD), average wind speed, boundary layer height, and turbulent kinetic energy (TKE). Overall, the results indicate that, for the current investigation, replacement of the standard look-up table values with the satellite-derived values statistically improves model performance for most observed variables. Such natural roughness heterogeneity enhances the surface wind speed, PBL height and TKE production up to 10 percent, with a lesser effect over grassland, and greater effect over mixed land cover domains.
NASA Technical Reports Server (NTRS)
Roskam, J.; Lan, C.
1973-01-01
Summarized are the aerodynamic center, alpha and q- aeroelastic effects on fighter-type aircraft in the 18,700 N gross range. The results indicate that with proper tailoring of planform (fixed or variable sweep), stiffner and elastic axis location it is possible to minimize trim requirements between selected extreme conditions. The inertial effects were found to be small for this class of aircraft.
Aerodynamic design using numerical optimization
NASA Technical Reports Server (NTRS)
Murman, E. M.; Chapman, G. T.
1983-01-01
The procedure of using numerical optimization methods coupled with computational fluid dynamic (CFD) codes for the development of an aerodynamic design is examined. Several approaches that replace wind tunnel tests, develop pressure distributions and derive designs, or fulfill preset design criteria are presented. The method of Aerodynamic Design by Numerical Optimization (ADNO) is described and illustrated with examples.
Not Available
1993-01-01
In this article two integral computational fluid dynamics methods for steady-state and transient vehicle aerodynamic simulations are described using a Chevrolet Corvette ZR-1 surface panel model. In the last decade, road-vehicle aerodynamics have become an important design consideration. Originally, the design of low-drag shapes was given high priority due to worldwide fuel shortages that occurred in the mid-seventies. More recently, there has been increased interest in the role aerodynamics play in vehicle stability and passenger safety. Consequently, transient aerodynamics and the aerodynamics of vehicle in yaw have become important issues at the design stage. While there has been tremendous progress in Navier-Stokes methodology in the last few years, the physics of bluff-body aerodynamics are still very difficult to model correctly. Moreover, the computational effort to perform Navier-Stokes simulations from the geometric stage to complete flow solutions requires much computer time and impacts the design cycle time. In the short run, therefore, simpler methods must be used for such complicated problems. Here, two methods are described for the simulation of steady-state and transient vehicle aerodynamics.
Employing Sensitivity Derivatives for Robust Optimization under Uncertainty in CFD
NASA Technical Reports Server (NTRS)
Newman, Perry A.; Putko, Michele M.; Taylor, Arthur C., III
2004-01-01
A robust optimization is demonstrated on a two-dimensional inviscid airfoil problem in subsonic flow. Given uncertainties in statistically independent, random, normally distributed flow parameters (input variables), an approximate first-order statistical moment method is employed to represent the Computational Fluid Dynamics (CFD) code outputs as expected values with variances. These output quantities are used to form the objective function and constraints. The constraints are cast in probabilistic terms; that is, the probability that a constraint is satisfied is greater than or equal to some desired target probability. Gradient-based robust optimization of this stochastic problem is accomplished through use of both first and second-order sensitivity derivatives. For each robust optimization, the effect of increasing both input standard deviations and target probability of constraint satisfaction are demonstrated. This method provides a means for incorporating uncertainty when considering small deviations from input mean values.
Integrated aerodynamic-structural design of a transport wing
NASA Technical Reports Server (NTRS)
Grossman, B.; Haftka, R. T.; Kao, P.-J.; Polen, D. M.; Rais-Rohani, M.; Sobieszczanski-Sobieski, J.
1989-01-01
The integrated aerodynamic-structural design of a subsonic transport wing for minimum weight subject to required range is formulated and solved. The problem requires large computational resources, and two methods are used to alleviate the computational burden. First, a modular sensitivity method that permits the usage of black-box disciplinary software packages, is used to reduce the cost of sensitivity derivatives. In particular, it is shown that derivatives of the aeroelastic response and divergence speed can be calculated without the costly computation of derivatives of aerodynamic influence coefficient and structural stiffness matrices. A sequential approximate optimization is used to further reduce computational cost. The optimization procedure is shown to require a relatively small number of analysis and sensitivity calculations.
Photogrammetry-Derived National Shoreline: Uncertainty and Sensitivity Analyses
NASA Astrophysics Data System (ADS)
Yao, F.; Parrish, C. E.; Calder, B. R.; Peeri, S.; Rzhanov, Y.
2013-12-01
Tidally-referenced shoreline data serve a multitude of purposes, ranging from nautical charting, to coastal change analysis, wetland migration studies, coastal planning, resource management and emergency management. To assess the suitability of the shoreline for a particular application, end users need not only the best available shoreline, but also reliable estimates of the uncertainty in the shoreline position. NOAA's National Geodetic Survey (NGS) is responsible for mapping the national shoreline depicted on NOAA nautical charts. Previous studies have focused on modeling the uncertainty in NGS shoreline derived from airborne lidar data, but, to date, these methods have not been extended to aerial imagery and photogrammetric shoreline extraction methods, which remain the primary shoreline mapping methods used by NGS. The aim of this study is to develop a rigorous total propagated uncertainty (TPU) model for shoreline compiled from both tide-coordinated and non-tide-coordinated aerial imagery and compiled using photogrammetric methods. The project site encompasses the strait linking Dennys Bay, Whiting Bay and Cobscook Bay in the 'Downeast' Maine coastal region. This area is of interest, due to the ecosystem services it provides, as well as its complex geomorphology. The region is characterized by a large tide range, strong tidal currents, numerous embayments, and coarse-sediment pocket beaches. Statistical methods were used to assess the uncertainty of shoreline in this site mapped using NGS's photogrammetric workflow, as well as to analyze the sensitivity of the mapped shoreline position to a variety of parameters, including elevation gradient in the intertidal zone. The TPU model developed in this work can easily be extended to other areas and may be facilitate estimation of uncertainty in inundation models and marsh migration models.
Sensitivity analysis of the GNSS derived Victoria plate motion
NASA Astrophysics Data System (ADS)
Apolinário, João; Fernandes, Rui; Bos, Machiel
2014-05-01
Fernandes et al. (2013) estimated the angular velocity of the Victoria tectonic block from geodetic data (GNSS derived velocities) only.. GNSS observations are sparse in this region and it is therefore of the utmost importance to use the available data (5 sites) in the most optimal way. Unfortunately, the existing time-series were/are affected by missing data and offsets. In addition, some time-series were close to the considered minimal threshold value to compute one reliable velocity solution: 2.5-3.0 years. In this research, we focus on the sensitivity of the derived angular velocity to changes in the data (longer data-span for some stations) by extending the used data-span: Fernandes et al. (2013) used data until September 2011. We also investigate the effect of adding other stations to the solution, which is now possible since more stations became available in the region. In addition, we study if the conventional power-law plus white noise model is indeed the best stochastic model. In this respect, we apply different noise models using HECTOR (Bos et al. (2013), which can use different noise models and estimate offsets and seasonal signals simultaneously. The seasonal signal estimation is also other important parameter, since the time-series are rather short or have large data spans at some stations, which implies that the seasonal signals still can have some effect on the estimated trends as shown by Blewitt and Lavellee (2002) and Bos et al. (2010). We also quantify the magnitude of such differences in the estimation of the secular velocity and their effect in the derived angular velocity. Concerning the offsets, we investigate how they can, detected and undetected, influence the estimated plate motion. The time of offsets has been determined by visual inspection of the time-series. The influence of undetected offsets has been done by adding small synthetic random walk signals that are too small to be detected visually but might have an effect on the
Boundary formulations for sensitivity analysis without matrix derivatives
NASA Technical Reports Server (NTRS)
Kane, J. H.; Guru Prasad, K.
1993-01-01
A new hybrid approach to continuum structural shape sensitivity analysis employing boundary element analysis (BEA) is presented. The approach uses iterative reanalysis to obviate the need to factor perturbed matrices in the determination of surface displacement and traction sensitivities via a univariate perturbation/finite difference (UPFD) step. The UPFD approach makes it possible to immediately reuse existing subroutines for computation of BEA matrix coefficients in the design sensitivity analysis process. The reanalysis technique computes economical response of univariately perturbed models without factoring perturbed matrices. The approach provides substantial computational economy without the burden of a large-scale reprogramming effort.
Sensitivity analysis of complex coupled systems extended to second and higher order derivatives
NASA Technical Reports Server (NTRS)
Sobieszczanski-Sobieski, Jaroslaw
1989-01-01
In design of engineering systems, the what if questions often arise such as: what will be the change of the aircraft payload, if the wing aspect ratio is incremented by 10 percent. Answers to such questions are commonly sought by incrementing the pertinent variable, and reevaluating the major disciplinary analyses involved. These analyses are contributed by engineering disciplines that are, usually, coupled, as are the aerodynamics, structures, and performance in the context of the question above. The what if questions can be answered precisely by computation of the derivatives. A method for calculation of the first derivatives has been developed previously. An algorithm is presented for calculation of the second and higher order derivatives.
Calculation of sensitivity derivatives in thermal problems by finite differences
NASA Technical Reports Server (NTRS)
Haftka, R. T.; Malkus, D. S.
1981-01-01
The optimum design of a structure subject to temperature constraints is considered. When mathematical optimization techniques are used, derivatives of the temperature constraints with respect to the design variables are usually required. In the case of large aerospace structures, such as the Space Shuttle, the computation of these derivatives can become prohibitively expensive. Analytical methods and a finite difference approach have been considered in studies conducted to improve the efficiency of the calculation of the derivatives. The present investigation explores two possibilities for enhancing the effectiveness of the finite difference approach. One procedure involves the simultaneous solution of temperatures and derivatives. The second procedure makes use of the optimum selection of the magnitude of the perturbations of the design variables to achieve maximum accuracy.
NASA Technical Reports Server (NTRS)
Noor, A. K.; Burton, W. S.
1992-01-01
Analytic three-dimensional thermoelasticity solutions are presented for the thermal buckling of multilayered angle-ply composite plates with temperature-dependent thermoelastic properties. Both the critical temperatures and the sensitivity derivatives are computed. The sensitivity derivatives measure the sensitivity of the buckling response to variations in the different lamination and material parameters of the plate. The plates are assumed to have rectangular geometry and an antisymmetric lamination with respect to the middle plane. The temperature is assumed to be independent of the surface coordinates, but has an arbitrary symmetric variation through the thickness of the plate. The prebuckling deformations are accounted for. Numerical results are presented, for plates subjected to uniform temperature increase, showing the effects of temperature-dependent material properties on the prebuckling stresses, critical temperatures, and their sensitivity derivatives.
Noor, A.K.; Burton, W.S. )
1992-12-01
Analytic three-dimensional thermoelasticity solutions are presented for the thermal buckling of multilayered angle-ply composite plates with temperature-dependent thermoelastic properties. Both the critical temperatures and the sensitivity derivatives are computed. The sensitivity derivatives measure the sensitivity of the buckling response to variations in the different lamination and material parameters of the plate. The plates are assumed to have rectangular geometry and an antisymmetric lamination with respect to the middle plane. The temperature is assumed to be independent of the surface coordinates, but has an arbitrary symmetric variation through the thickness of the plate. The prebuckling deformations are accounted for. Numerical results are presented, for plates subjected to uniform temperature increase, showing the effects of temperature-dependent material properties on the prebuckling stresses, critical temperatures, and their sensitivity derivatives. 15 refs.
Sensitivity analysis of a wing aeroelastic response
NASA Technical Reports Server (NTRS)
Kapania, Rakesh K.; Eldred, Lloyd B.; Barthelemy, Jean-Francois M.
1991-01-01
A variation of Sobieski's Global Sensitivity Equations (GSE) approach is implemented to obtain the sensitivity of the static aeroelastic response of a three-dimensional wing model. The formulation is quite general and accepts any aerodynamics and structural analysis capability. An interface code is written to convert one analysis's output to the other's input, and visa versa. Local sensitivity derivatives are calculated by either analytic methods or finite difference techniques. A program to combine the local sensitivities, such as the sensitivity of the stiffness matrix or the aerodynamic kernel matrix, into global sensitivity derivatives is developed. The aerodynamic analysis package FAST, using a lifting surface theory, and a structural package, ELAPS, implementing Giles' equivalent plate model are used.
NASA Astrophysics Data System (ADS)
Todarello, Giovanni; Vonck, Floris; Bourasseau, Sébastien; Peter, Jacques; Désidéri, Jean-Antoine
2016-05-01
A new goal-oriented mesh adaptation method for finite volume/finite difference schemes is extended from the structured mesh framework to a more suitable setting for adaptation of unstructured meshes. The method is based on the total derivative of the goal with respect to volume mesh nodes that is computable after the solution of the goal discrete adjoint equation. The asymptotic behaviour of this derivative is assessed on regularly refined unstructured meshes. A local refinement criterion is derived from the requirement of limiting the first order change in the goal that an admissible node displacement may cause. Mesh adaptations are then carried out for classical test cases of 2D Euler flows. Efficiency and local density of the adapted meshes are presented. They are compared with those obtained with a more classical mesh adaptation method in the framework of finite volume/finite difference schemes [46]. Results are very close although the present method only makes usage of the current grid.
PREFACE: Aerodynamic sound Aerodynamic sound
NASA Astrophysics Data System (ADS)
Akishita, Sadao
2010-02-01
The modern theory of aerodynamic sound originates from Lighthill's two papers in 1952 and 1954, as is well known. I have heard that Lighthill was motivated in writing the papers by the jet-noise emitted by the newly commercialized jet-engined airplanes at that time. The technology of aerodynamic sound is destined for environmental problems. Therefore the theory should always be applied to newly emerged public nuisances. This issue of Fluid Dynamics Research (FDR) reflects problems of environmental sound in present Japanese technology. The Japanese community studying aerodynamic sound has held an annual symposium since 29 years ago when the late Professor S Kotake and Professor S Kaji of Teikyo University organized the symposium. Most of the Japanese authors in this issue are members of the annual symposium. I should note the contribution of the two professors cited above in establishing the Japanese community of aerodynamic sound research. It is my pleasure to present the publication in this issue of ten papers discussed at the annual symposium. I would like to express many thanks to the Editorial Board of FDR for giving us the chance to contribute these papers. We have a review paper by T Suzuki on the study of jet noise, which continues to be important nowadays, and is expected to reform the theoretical model of generating mechanisms. Professor M S Howe and R S McGowan contribute an analytical paper, a valuable study in today's fluid dynamics research. They apply hydrodynamics to solve the compressible flow generated in the vocal cords of the human body. Experimental study continues to be the main methodology in aerodynamic sound, and it is expected to explore new horizons. H Fujita's study on the Aeolian tone provides a new viewpoint on major, longstanding sound problems. The paper by M Nishimura and T Goto on textile fabrics describes new technology for the effective reduction of bluff-body noise. The paper by T Sueki et al also reports new technology for the
Aerodynamics for the Mars Phoenix Entry Capsule
NASA Technical Reports Server (NTRS)
Edquist, Karl T.; Desai, Prasun N.; Schoenenberger, Mark
2008-01-01
Pre-flight aerodynamics data for the Mars Phoenix entry capsule are presented. The aerodynamic coefficients were generated as a function of total angle-of-attack and either Knudsen number, velocity, or Mach number, depending on the flight regime. The database was constructed using continuum flowfield computations and data from the Mars Exploration Rover and Viking programs. Hypersonic and supersonic static coefficients were derived from Navier-Stokes solutions on a pre-flight design trajectory. High-altitude data (free-molecular and transitional regimes) and dynamic pitch damping characteristics were taken from Mars Exploration Rover analysis and testing. Transonic static coefficients from Viking wind tunnel tests were used for capsule aerodynamics under the parachute. Static instabilities were predicted at two points along the reference trajectory and were verified by reconstructed flight data. During the hypersonic instability, the capsule was predicted to trim at angles as high as 2.5 deg with an on-axis center-of-gravity. Trim angles were predicted for off-nominal pitching moment (4.2 deg peak) and a 5 mm off-axis center-ofgravity (4.8 deg peak). Finally, hypersonic static coefficient sensitivities to atmospheric density were predicted to be within uncertainty bounds.
Integrated aerodynamic-structural-control wing design
NASA Technical Reports Server (NTRS)
Rais-Rohani, M.; Haftka, R. T.; Grossman, B.; Unger, E. R.
1992-01-01
The aerodynamic-structural-control design of a forward-swept composite wing for a high subsonic transport aircraft is considered. The structural analysis is based on a finite-element method. The aerodynamic calculations are based on a vortex-lattice method, and the control calculations are based on an output feedback control. The wing is designed for minimum weight subject to structural, performance/aerodynamic and control constraints. Efficient methods are used to calculate the control-deflection and control-effectiveness sensitivities which appear as second-order derivatives in the control constraint equations. To suppress the aeroelastic divergence of the forward-swept wing, and to reduce the gross weight of the design aircraft, two separate cases are studied: (1) combined application of aeroelastic tailoring and active controls; and (2) aeroelastic tailoring alone. The results of this study indicated that, for this particular example, aeroelastic tailoring is sufficient for suppressing the aeroelastic divergence, and the use of active controls was not necessary.
Imidazoacridinone Derivatives as Efficient Sensitizers in Photoantimicrobial Chemotherapy
Taraszkiewicz, Aleksandra; Grinholc, Mariusz; Bielawski, Krzysztof P.; Kawiak, Anna
2013-01-01
The objective of this study was to investigate a new potential photosensitizer (PS) in the photodynamic inactivation (PDI) of microorganisms in vitro (11 reference strains and 13 clinical isolates, representing common Gram-positive and Gram-negative human pathogens), with special emphasis on Candida albicans. We studied the light-induced cytotoxicity of the imidazoacridinone derivative C1330 toward fungal cells grown in planktonic form. We examined the influence of various parameters (time of incubation, PDI quencher effect, and C1330 accumulation in C. albicans cells) on the efficacy of light-dependent cytotoxicity. Additionally, we checked for the potential cyto- and phototoxic activity of C1330 against human dermal keratinocytes. In our research, we used a broadband incoherent blue light source (380 to 470 nm) with an output power of 100 mW/cm2. In vitro studies showed that the C1330 action against C. albicans was a light-dependent process. C1330 was an efficient photosensitizer in the photodynamic inactivation of C. albicans, which reduced the growth of planktonic cells by 6.1 log10 units. Efficient accumulation of PS in the nucleus and vacuoles was observed after 30 min of incubation, which correlated with the highest photokilling efficacy. Significant changes in intracellular structure were observed upon illumination of C1330-incubated C. albicans cells. In the case of the human HaCaT cell line, approximately 40% of cells survived the treatment, which indicates the potential benefit of further study of the application of C1330 in photoantimicrobial chemotherapy. These data suggest that PDI may be a viable approach for the treatment of localized C. albicans infections. PMID:23563951
Val'vachev, N I; Vilenchik, G I; Rimzha, M I
1976-03-01
Sensitivity of 267 strains of pathogenic staphylococci isolated in 1974 was studied with respect to some antibiotics and nitrofuran derivatives by the method of serial dilutions on solid media. Sensitivity to penicillin, oxacillin, olemorphocycline, ristomycin and nitrofuran derivatives (furagin and salafur) was observed in 30.7 +/- 2.8, 61.8 +/-3, 29.2 +/-2.8 and 98.9 +/- 0.8 per cent of the cultures respectively. PMID:132136
NASA Technical Reports Server (NTRS)
Lewis, Robert Michael; Patera, Anthony T.; Peraire, Jaume
1998-01-01
We present a Neumann-subproblem a posteriori finite element procedure for the efficient and accurate calculation of rigorous, 'constant-free' upper and lower bounds for sensitivity derivatives of functionals of the solutions of partial differential equations. The design motivation for sensitivity derivative error control is discussed; the a posteriori finite element procedure is described; the asymptotic bounding properties and computational complexity of the method are summarized; and illustrative numerical results are presented.
Missile Aerodynamics for Ascent and Re-entry
NASA Technical Reports Server (NTRS)
Watts, Gaines L.; McCarter, James W.
2012-01-01
Aerodynamic force and moment equations are developed for 6-DOF missile simulations of both the ascent phase of flight and a tumbling re-entry. The missile coordinate frame (M frame) and a frame parallel to the M frame were used for formulating the aerodynamic equations. The missile configuration chosen as an example is a cylinder with fixed fins and a nose cone. The equations include both the static aerodynamic coefficients and the aerodynamic damping derivatives. The inclusion of aerodynamic damping is essential for simulating a tumbling re-entry. Appended information provides insight into aerodynamic damping.
NASA Technical Reports Server (NTRS)
Parkinson, John B; Olson, Roland E; Draley, Eugene C; Luoma, Arvo A
1943-01-01
A series of related forms of flying-boat hulls representing various degrees of compromise between aerodynamic and hydrodynamic requirements was tested in Langley Tank No. 1 and in the Langley 8-foot high-speed tunnel. The purpose of the investigation was to provide information regarding the penalties in water performance resulting from further aerodynamic refinement and, as a corollary, to provide information regarding the penalties in range or payload resulting from the retention of certain desirable hydrodynamic characteristics. The information should form a basis for over-all improvements in hull form.
Okada, Junichi; Shimokawa, Noriaki; Koibuchi, Noriyuki
2005-07-01
Polychlorinated biphenyls (PCBs) are known as environmental pollutants that may cause adverse health problems. However, little is known about the effects of PCBs on acid-sensitive neurons of the medulla oblongata, which regulate respiration. Therefore, the present study was designed to examine whether PCB alters acid-sensitivity of cultured neurons derived from the rat medulla oblongata. When extracellular pH was shifted from 7.4 to 7.0, acid-sensitive neurons showed depolarization, which was measured by voltage-sensitive fluorescent dye. Exposure to PCB (Aroclor 1254) decreased the amplitude of depolarization in low pH and increased the resting membrane potential in a dose-dependent manner. Taken together, our results indicate that PCB potentially influences acid-sensitivity through alteration of the membrane potential of acid-sensitive neurons, which could affect the regulation of respiration. PMID:15833269
Approach for Input Uncertainty Propagation and Robust Design in CFD Using Sensitivity Derivatives
NASA Technical Reports Server (NTRS)
Putko, Michele M.; Taylor, Arthur C., III; Newman, Perry A.; Green, Lawrence L.
2002-01-01
An implementation of the approximate statistical moment method for uncertainty propagation and robust optimization for quasi 3-D Euler CFD code is presented. Given uncertainties in statistically independent, random, normally distributed input variables, first- and second-order statistical moment procedures are performed to approximate the uncertainty in the CFD output. Efficient calculation of both first- and second-order sensitivity derivatives is required. In order to assess the validity of the approximations, these moments are compared with statistical moments generated through Monte Carlo simulations. The uncertainties in the CFD input variables are also incorporated into a robust optimization procedure. For this optimization, statistical moments involving first-order sensitivity derivatives appear in the objective function and system constraints. Second-order sensitivity derivatives are used in a gradient-based search to successfully execute a robust optimization. The approximate methods used throughout the analyses are found to be valid when considering robustness about input parameter mean values.
Technology Transfer Automated Retrieval System (TEKTRAN)
The surface aerodynamic temperature (SAT) is related to the atmospheric forcing conditions (radiation, wind speed and air temperature) and surface conditions. SAT is required in the bulk surface resistance equation to calculate the rate of sensible heat flux exchange. SAT cannot be measured directly...
Discrete sensitivity derivatives of the Navier-Stokes equations with a parallel Krylov solver
NASA Technical Reports Server (NTRS)
Ajmani, Kumud; Taylor, Arthur C., III
1994-01-01
This paper solves an 'incremental' form of the sensitivity equations derived by differentiating the discretized thin-layer Navier Stokes equations with respect to certain design variables of interest. The equations are solved with a parallel, preconditioned Generalized Minimal RESidual (GMRES) solver on a distributed-memory architecture. The 'serial' sensitivity analysis code is parallelized by using the Single Program Multiple Data (SPMD) programming model, domain decomposition techniques, and message-passing tools. Sensitivity derivatives are computed for low and high Reynolds number flows over a NACA 1406 airfoil on a 32-processor Intel Hypercube, and found to be identical to those computed on a single-processor Cray Y-MP. It is estimated that the parallel sensitivity analysis code has to be run on 40-50 processors of the Intel Hypercube in order to match the single-processor processing time of a Cray Y-MP.
NASA Technical Reports Server (NTRS)
Jones, R. T. (Compiler)
1979-01-01
A collection of papers on modern theoretical aerodynamics is presented. Included are theories of incompressible potential flow and research on the aerodynamic forces on wing and wing sections of aircraft and on airship hulls.
Aerodynamic Shape Optimization Based on Free-form Deformation
NASA Technical Reports Server (NTRS)
Samareh, Jamshid A.
2004-01-01
This paper presents a free-form deformation technique suitable for aerodynamic shape optimization. Because the proposed technique is independent of grid topology, we can treat structured and unstructured computational fluid dynamics grids in the same manner. The proposed technique is an alternative shape parameterization technique to a trivariate volume technique. It retains the flexibility and freedom of trivariate volumes for CFD shape optimization, but it uses a bivariate surface representation. This reduces the number of design variables by an order of magnitude, and it provides much better control for surface shape changes. The proposed technique is simple, compact, and efficient. The analytical sensitivity derivatives are independent of the design variables and are easily computed for use in a gradient-based optimization. The paper includes the complete formulation and aerodynamics shape optimization results.
Riley, Mark R; Boesewetter, Dianne E; Turner, Rachael A; Kim, Aana M; Collier, Jayne M; Hamilton, Amy
2005-04-01
While the effects of inhalation of combustion-derived particulate matter have received extensive study, there remains no reliable means to rapidly quantify inhalation toxicity outside of a laboratory setting. Cell-based biosensors provide a potential solution, but few comparisons have been made of the sensitivity of various cell lines to the wide range of inhalation health hazards that are likely to be encountered. This work compares the response of three immortalized lung cell lines (A549 human epithelia, RLE-6TN rat type II epithelia, and NR8383 rat alveolar macrophages) to metals commonly present in combustion-derived particulate matter. Quantifications of the cell response involved measurement of inhibition of cell culture metabolism (mitochondrial succinate dehydrogenase activity) and cell death (release of lactate dehydrogenase). While these three cell types generally ranked metals in ED50 values similarly (V
NASA Technical Reports Server (NTRS)
Zumwalt, Kenneth W.; El-Sayed, Mohamed E. M.
1990-01-01
This paper presents an analytical approach for incorporating design sensitivity calculations directly into the finite element analysis. The formulation depends on the implicit differentiation approach and requires few additional calculations to obtain the design sensitivity derivatives. In order to evaluate this approach, it is compared with the semi-analytical approach which is based on commonly used finite difference formulations. Both approaches are implemented to calculate the design sensitivities for continuum and structural isoparametric elements. To demonstrate the accuracy and robustness of the developed analytical approach compared to the semi-analytical approach, some test cases using different structural and continuum element types are presented.
NASA Technical Reports Server (NTRS)
Williams, Louis J.; Hessenius, Kristin A.; Corsiglia, Victor R.; Hicks, Gary; Richardson, Pamela F.; Unger, George; Neumann, Benjamin; Moss, Jim
1992-01-01
The annual accomplishments is reviewed for the Aerodynamics Division during FY 1991. The program includes both fundamental and applied research directed at the full spectrum of aerospace vehicles, from rotorcraft to planetary entry probes. A comprehensive review is presented of the following aerodynamics elements: computational methods and applications; CFD validation; transition and turbulence physics; numerical aerodynamic simulation; test techniques and instrumentation; configuration aerodynamics; aeroacoustics; aerothermodynamics; hypersonics; subsonics; fighter/attack aircraft and rotorcraft.
BRCA1 and BRCA2 mutations sensitize to chemotherapy in patient-derived pancreatic cancer xenografts
Lohse, I; Borgida, A; Cao, P; Cheung, M; Pintilie, M; Bianco, T; Holter, S; Ibrahimov, E; Kumareswaran, R; Bristow, R G; Tsao, M-S; Gallinger, S; Hedley, D W
2015-01-01
Background: Germline mutations of the BRCA tumour suppressors have been associated with increased risk of pancreatic cancer. Clinical evidence suggests that these patients may be more sensitive to treatment with cisplatin. As the frequency of germline BRCA mutations is low, definitive experimental data to support the clinical observations are still missing. Methods: We tested gemcitabine and cisplatin sensitivity of four BRCA1 and BRCA2 mutant and three BRCA1 and BRCA2 wild-type (WT) patient-derived pancreatic cancer xenografts. Results: We observed treatment sensitivity to gemcitabine and cisplatin in the BRCA WT and mutant models. The BRCA1 and BRCA2 mutant xenografts were significantly more sensitive to cisplatin although these models also showed sensitivity to gemcitabine. The BRCA1 and BRCA2 WT models showed sensitivity to gemcitabine but not cisplatin. Treatment sensitivity in the xenograft models closely resembled treatment response in the corresponding patients. Discussion: We have characterised a panel of xenografts derived from pancreatic cancer patients carrying germline BRCA mutations, and shown that their genetic features resemble the patient donor. Our results support further clinical testing of treatment regimens combining gemcitabine and platinum drugs in this patient population, as well as preclinical research aiming to identify mechanisms of cisplatin resistance in BRCA mutant pancreatic cancers. PMID:26180923
NASA Technical Reports Server (NTRS)
Fetterman, Timothy L.; Noor, Ahmed K.
1987-01-01
Computational procedures are presented for evaluating the sensitivity derivatives of the vibration frequencies and eigenmodes of framed structures. Both a displacement and a mixed formulation are used. The two key elements of the computational procedure are: (a) Use of dynamic reduction techniques to substantially reduce the number of degrees of freedom; and (b) Application of iterative techniques to improve the accuracy of the derivatives of the eigenmodes. The two reduction techniques considered are the static condensation and a generalized dynamic reduction technique. Error norms are introduced to assess the accuracy of the eigenvalue and eigenvector derivatives obtained by the reduction techniques. The effectiveness of the methods presented is demonstrated by three numerical examples.
NASA Technical Reports Server (NTRS)
Holmes, Bruce J.; Schairer, Edward; Hicks, Gary; Wander, Stephen; Blankson, Isiaiah; Rose, Raymond; Olson, Lawrence; Unger, George
1990-01-01
Presented here is a comprehensive review of the following aerodynamics elements: computational methods and applications, computational fluid dynamics (CFD) validation, transition and turbulence physics, numerical aerodynamic simulation, drag reduction, test techniques and instrumentation, configuration aerodynamics, aeroacoustics, aerothermodynamics, hypersonics, subsonic transport/commuter aviation, fighter/attack aircraft and rotorcraft.
Li, Yu-Sheng; Oldendick, James E; Chang, Wei
2013-01-01
Pinhole collimators are widely used for SPECT imaging of small organs and animals. There also has been renewed interest in using pinhole arrays for clinical cardiac SPECT imaging to achieve high sensitivity and complete data sampling. Overall sensitivity of a pinhole array is critical in determining a system’s performance. Conventionally, a point source model has been used to evaluate the sensitivity and optimize the system design. This model is simple but far from realistic. This work addresses the use of more realistic source models to assess the sensitivity performance of pinhole collimation. We have derived an analytical formula for pinhole collimation sensitivity with a general source distribution model using spherical harmonics. As special cases of this general model, we provided the pinhole sensitivity formulae for line, disk and sphere sources. These results show that the point source model is just the zeroth-order approximation of the other source models. The point source model overestimates or underestimates the sensitivity relative to the more realistic model. The sphere source model yields the same sensitivity as a point source located at the center of the sphere when attenuation is not taken into account. In the presence of attenuation, the average path length of emitted gamma-rays is 3/4 of the radius of the sphere source. The calculated sensitivities based on these formulae show good agreement with separate Monte Carlo simulations in simple cases. The general and special sensitivity formulae derived here can be useful for the design and optimization of SPECT systems that utilize pinhole collimators. PMID:20400812
Sensitivity to Change of Objectively-Derived Measures of Sedentary Behavior
ERIC Educational Resources Information Center
Chastin, Sebastien F. M.; Winkler, Elisabeth A. H.; Eakin, Elizabeth G.; Gardiner, Paul A.; Dunstan, David W.; Owen, Neville; Healy, Genevieve N.
2015-01-01
The aim of this study was to examine the sensitivity to change of measures of sedentary behavior derived from body worn sensors in different intervention designs. Results from two intervention studies: "Stand up for Your Health" (pre-post home-based study with older adults not in paid employment) and "Stand Up Comcare"…
Analytically-derived sensitivities in one-dimensional models of solute transport in porous media
Knopman, D.S.
1987-01-01
Analytically-derived sensitivities are presented for parameters in one-dimensional models of solute transport in porous media. Sensitivities were derived by direct differentiation of closed form solutions for each of the odel, and by a time integral method for two of the models. Models are based on the advection-dispersion equation and include adsorption and first-order chemical decay. Boundary conditions considered are: a constant step input of solute, constant flux input of solute, and exponentially decaying input of solute at the upstream boundary. A zero flux is assumed at the downstream boundary. Initial conditions include a constant and spatially varying distribution of solute. One model simulates the mixing of solute in an observation well from individual layers in a multilayer aquifer system. Computer programs produce output files compatible with graphics software in which sensitivities are plotted as a function of either time or space. (USGS)
NASA Technical Reports Server (NTRS)
Korivi, Vamshi Mohan; Taylor, Arthur C., III; Newman, Perry A.; Jones, Henry E.
1994-01-01
In a recent work, an incremental strategy was proposed to iteratively solve the very large systems of linear equations that are required to obtain quasianalytical sensitivity derivatives from advanced computational fluid dynamics (CFD) codes. The technique was sucessfully demonstrated for two large two-dimensional problems: a subsonic and a transonic airfoil. The principal feature of this incremental iterative stategy is that it allows the use of the identical approximate coefficient matrix operator and algorithm to solve the nonlinear flow and the linear sensitivity equations; at convergence, the accuracy of the sensitivity derivatives is not compromised. This feature allows a comparatively straightforward extension of the methodology to three-dimensional problems; this extension is successfully demonstrated in the present study for a space-marching solution of the three-dimensional Euler equations over a Mach 2.4 blended wing-body configuration.
Liu, Hui; Wang, Fang; Wang, Gui-Xiang; Gong, Xue-Dong
2012-08-15
The -NH(2), -NO(2), -N(3), -NHNO(2), and -ONO(2) substitution derivatives of PYX (2,6-bis(picrylamino)-3,5-dinitropyridine) were studied at the B3LYP/6-31G** level of density functional theory. The sublimation enthalpies and heats of formation (HOFs) in gas phase and solid state of these compounds were calculated. The theoretical predicted density (ρ), detonation pressure (P), and detonation velocity (D) showed that these derivatives have better detonation performance than PYX. The effects of substituent groups on HOF, ρ, P, and D were discussed. The order of contribution of various groups to P and D was -ONO(2) > -NO(2) > -NHNO(2) > -N(3) > -NH(2). Sensitivity was evaluated using the frontier orbital energies, bond orders, bond dissociation enthalpies (BDEs), and characteristic heights (h(50)). The trigger bonds in the pyrolysis process for these PYX derivatives may be Ring-NO(2), NH-NO(2), or O-NO(2) varying with the substituents. The h(50) of most compounds are larger than that of CL-20, and those of -NH(2), -NO(2), and most -ONO(2) derivatives are larger than that of RDX. The BDEs of the trigger bonds of all but the -ONO(2) derivatives are sufficiently large. Taking both detonation performance and sensitivity into consideration, some derivatives of PYX may be good candidates of explosives. PMID:22618376
Training Data Requirement for a Neural Network to Predict Aerodynamic Coefficients
NASA Technical Reports Server (NTRS)
Korsmeyer, David (Technical Monitor); Rajkumar, T.; Bardina, Jorge
2003-01-01
Basic aerodynamic coefficients are modeled as functions of angle of attack, speed brake deflection angle, Mach number, and side slip angle. Most of the aerodynamic parameters can be well-fitted using polynomial functions. We previously demonstrated that a neural network is a fast, reliable way of predicting aerodynamic coefficients. We encountered few under fitted and/or over fitted results during prediction. The training data for the neural network are derived from wind tunnel test measurements and numerical simulations. The basic questions that arise are: how many training data points are required to produce an efficient neural network prediction, and which type of transfer functions should be used between the input-hidden layer and hidden-output layer. In this paper, a comparative study of the efficiency of neural network prediction based on different transfer functions and training dataset sizes is presented. The results of the neural network prediction reflect the sensitivity of the architecture, transfer functions, and training dataset size.
Nostril Aerodynamics of Scenting Animals
NASA Astrophysics Data System (ADS)
Settles, G. S.
1997-11-01
Dogs and other scenting animals detect airborne odors with extraordinary sensitivity. Aerodynamic sampling plays a key role, but the literature on olfaction contains little on the external aerodynamics thereof. To shed some light on this, the airflows generated by a scenting dog were visualized using the schlieren technique. It was seen that the dog stops panting in order to scent, since panting produces a turbulent jet which disturbs scent-bearing air currents. Inspiratory airflow enters the nostrils from straight ahead, while expiration is directed to the sides of the nose and downward, as was found elsewhere in the case of rats and rabbits. The musculature and geometry of the dog's nose thus modulates the airflow during scenting. The aerodynamics of a nostril which must act reversibly as both inlet and outlet is briefly discussed. The eventual practical goal of this preliminary work is to achieve a level of understanding of the aerodynamics of canine olfaction sufficient for the design of a mimicking device. (Research supported by the DARPA Unexploded Ordnance Detection and Neutralization Program.)
Global climate sensitivity derived from ~784,000 years of SST data
NASA Astrophysics Data System (ADS)
Friedrich, T.; Timmermann, A.; Tigchelaar, M.; Elison Timm, O.; Ganopolski, A.
2015-12-01
Global mean temperatures will increase in response to future increasing greenhouse gas concentrations. The magnitude of this warming for a given radiative forcing is still subject of debate. Here we provide estimates for the equilibrium climate sensitivity using paleo-proxy and modeling data from the last eight glacial cycles (~784,000 years). First of all, two reconstructions of globally averaged surface air temperature (SAT) for the last eight glacial cycles are obtained from two independent sources: one mainly based on a transient model simulation, the other one derived from paleo- SST records and SST network/global SAT scaling factors. Both reconstructions exhibit very good agreement in both amplitude and timing of past SAT variations. In the second step, we calculate the radiative forcings associated with greenhouse gas concentrations, dust concentrations, and surface albedo changes for the last 784, 000 years. The equilibrium climate sensitivity is then derived from the ratio of the SAT anomalies and the radiative forcing changes. Our results reveal that this estimate of the Charney climate sensitivity is a function of the background climate with substantially higher values for warmer climates. Warm phases exhibit an equilibrium climate sensitivity of ~3.70 K per CO2-doubling - more than twice the value derived for cold phases (~1.40 K per 2xCO2). We will show that the current CMIP5 ensemble-mean projection of global warming during the 21st century is supported by our estimate of climate sensitivity derived from climate paleo data of the past 784,000 years.
Manfredi, N; Cecconi, B; Calabrese, V; Minotti, A; Peri, F; Ruffo, R; Monai, M; Romero-Ocaña, I; Montini, T; Fornasiero, P; Abbotto, A
2016-05-19
A thiophene-based donor-acceptor phenothiazine dye has been functionalized with a peripheral glucose unit (PTZ-GLU) to bust its affinity to water and enhance dye-sensitized photogeneration of hydrogen. Compared to the corresponding alkyl derivative (PTZ-ALK), as well as the common hydrophilic triethylene glycol substitution (PTZ-TEG), the sugar derivative shows a lower contact angle; PTZ-GLU performed twice more efficient than PTZ-TEG in the photogeneration of hydrogen in terms of evolved gas and turnover number. PMID:27063187
NASA Technical Reports Server (NTRS)
Richard, M.; Harrison, B. A.
1979-01-01
The program input presented consists of configuration geometry, aerodynamic parameters, and modal data; output includes element geometry, pressure difference distributions, integrated aerodynamic coefficients, stability derivatives, generalized aerodynamic forces, and aerodynamic influence coefficient matrices. Optionally, modal data may be input on magnetic file (tape or disk), and certain geometric and aerodynamic output may be saved for subsequent use.
Accuracy of the domain method for the material derivative approach to shape design sensitivities
NASA Technical Reports Server (NTRS)
Yang, R. J.; Botkin, M. E.
1987-01-01
Numerical accuracy for the boundary and domain methods of the material derivative approach to shape design sensitivities is investigated through the use of mesh refinement. The results show that the domain method is generally more accurate than the boundary method, using the finite element technique. It is also shown that the domain method is equivalent, under certain assumptions, to the implicit differentiation approach not only theoretically but also numerically.
Biomass-derived carbon quantum dot sensitizers for solid-state nanostructured solar cells.
Briscoe, Joe; Marinovic, Adam; Sevilla, Marta; Dunn, Steve; Titirici, Magdalena
2015-04-01
New hybrid materials consisting of ZnO nanorods sensitized with three different biomass-derived carbon quantum dots (CQDs) were synthesized, characterized, and used for the first time to build solid-state nanostructured solar cells. The performance of the devices was dependent on the functional groups found on the CQDs. The highest efficiency was obtained using a layer-by-layer coating of two different types of CQDs. PMID:25704873
Approach for Uncertainty Propagation and Robust Design in CFD Using Sensitivity Derivatives
NASA Technical Reports Server (NTRS)
Putko, Michele M.; Newman, Perry A.; Taylor, Arthur C., III; Green, Lawrence L.
2001-01-01
This paper presents an implementation of the approximate statistical moment method for uncertainty propagation and robust optimization for a quasi 1-D Euler CFD (computational fluid dynamics) code. Given uncertainties in statistically independent, random, normally distributed input variables, a first- and second-order statistical moment matching procedure is performed to approximate the uncertainty in the CFD output. Efficient calculation of both first- and second-order sensitivity derivatives is required. In order to assess the validity of the approximations, the moments are compared with statistical moments generated through Monte Carlo simulations. The uncertainties in the CFD input variables are also incorporated into a robust optimization procedure. For this optimization, statistical moments involving first-order sensitivity derivatives appear in the objective function and system constraints. Second-order sensitivity derivatives are used in a gradient-based search to successfully execute a robust optimization. The approximate methods used throughout the analyses are found to be valid when considering robustness about input parameter mean values.
Liao, Yanlong; Hu, Jiaomei; Xie, Qiufang; Peng, Dahai; Liu, Ye; Zhu, Chunxiao; Zhong, Chaofan
2016-01-15
Four novel donor-acceptor (D-A) type conjugated polymeric metal complexes (P1-P4) bearing benzodithiophene or carbazole derivative as donors were synthesized, characterized and applied as dye sensitizers in dye-sensitized solar cells (DSSCs). Salicylaldehyde derivative complexes acted as electron acceptors, Zn(II) or Cd(II) was chosen as the coordinated metal ion, and diaminomaleonitrile was ancillary ligand in these structures. The thermal, photophysical, electrochemical and photovoltaic properties of these polymeric metal complexes were investigated by FT-IR, GPC, TGA, DSC, UV-Vis absorption spectroscopy, elemental analysis, cyclic voltammetry (CV), J-V curves and IPCE plots. These polymer dyes exhibit good thermal stability for their application in DSSCs. The DSSC device based on P2 which contains benzodithiophene derivative as donor and Cd(II) as coordination ion, exhibited the highest power conversion efficiency of 2.43% (J(sc)=4.95 mA/cm(2), V(oc) =0.71 V, FF=69.3%) under AM 1.5 G solar irradiation. It indicates a new way to design dye sensitizers for DSSCs. PMID:26474240
NASA Astrophysics Data System (ADS)
Liao, Yanlong; Hu, Jiaomei; Xie, Qiufang; Peng, Dahai; Liu, Ye; Zhu, Chunxiao; Zhong, Chaofan
2016-01-01
Four novel donor-acceptor (D-A) type conjugated polymeric metal complexes (P1-P4) bearing benzodithiophene or carbazole derivative as donors were synthesized, characterized and applied as dye sensitizers in dye-sensitized solar cells (DSSCs). Salicylaldehyde derivative complexes acted as electron acceptors, Zn(II) or Cd(II) was chosen as the coordinated metal ion, and diaminomaleonitrile was ancillary ligand in these structures. The thermal, photophysical, electrochemical and photovoltaic properties of these polymeric metal complexes were investigated by FT-IR, GPC, TGA, DSC, UV-Vis absorption spectroscopy, elemental analysis, cyclic voltammetry (CV), J-V curves and IPCE plots. These polymer dyes exhibit good thermal stability for their application in DSSCs. The DSSC device based on P2 which contains benzodithiophene derivative as donor and Cd(II) as coordination ion, exhibited the highest power conversion efficiency of 2.43% (Jsc = 4.95 mA/cm2, Voc = 0.71 V, FF = 69.3%) under AM 1.5 G solar irradiation. It indicates a new way to design dye sensitizers for DSSCs.
Xu, Li; Zhu, Zece; Wei, Danqing; Zhou, Xiang; Qin, Jingui; Yang, Chuluo
2014-10-22
A series of new amino-functionalized tetraphenylethene (TPE) derivatives were designed and synthesized to study the effect of molecular structures on the detection of nucleic acid. Contrastive studies revealed that the number of binding groups, the length of hydrophobic linking arm and the configuration of TPE molecule all play important roles on the sensitivity of the probes in nucleic acid detection. Z-TPE3 with two binding amino groups, long linking arms, and cis configuration was found to be the most sensitive dye in both solution and gel matrix. Z-TPE3 is able to stain dsDNA with the lowest amount of 1 ng and exclusively stain 40 ng of short oligonucleotide with only 10 nt. This work is of important significance for the further design of TPE probes as biosensors with higher sensitivity. PMID:25279446
Villeneuve, D.L.; Blankenship, A.L.; Giesy, J.P.; Richter, C.A.
1999-05-01
Rainbow trout hepatoma cells, stably transfected with a luciferase reporter gene under control of dioxin-responsive elements (RLT 2.0 cells) were used to derive relative potencies (RPs) for a variety of halogenated aromatic hydrocarbons (HAHs) that are structurally similar to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). This in vitro bioassay utilizes 96-well microplates, which provide high sample throughput and assay efficiency without affecting sensitivity. The RLT 2.0-derived potencies for dioxin and furan congeners, relative to 2,3,7,8-TCDD, ranged from 0.917 for 1,2,3,4,7,8-hexachlorodibenzofuran to 0.208 or 1,2,3,7,8-pentachlorodibenzofuran. All mono- and di-ortho polychlorinated biphenyls (PCBs) tested had RPs that were orders of magnitude less than TCDD, but point estimates could not be determined. The RLT 2.0-derived RPs were found to be comparable to both other rainbow trout-specific RPs and RPs based on mammalian bioassays. Sensitivity analysis suggested that the range of uncertainty associated with TCDD equivalent (TEQ) estimates based on RLT 2.0-derived RPs is approximately 10-fold. Within this degree of uncertainty and the context of this study, the RLT 2.0 bioassay showed no definitive biases or inaccuracies relative to similar mammalian- or fish-specific in vitro bioassays. Thus, the RLT 2.0 bioassay appears to be a useful tool for evaluating dioxin-like potency of HAHs to fish.
Role of Allergen Source-Derived Proteases in Sensitization via Airway Epithelial Cells
Matsumura, Yasuhiro
2012-01-01
Protease activity is a characteristic common to many allergens. Allergen source-derived proteases interact with lung epithelial cells, which are now thought to play vital roles in both innate and adaptive immune responses. Allergen source-derived proteases act on airway epithelial cells to induce disruption of the tight junctions between epithelial cells, activation of protease-activated receptor-2, and the production of thymic stromal lymphopoietin. These facilitate allergen delivery across epithelial layers and enhance allergenicity or directly activate the immune system through a nonallergic mechanism. Furthermore, they cleave regulatory cell surface molecules involved in allergic reactions. Thus, allergen source-derived proteases are a potentially critical factor in the development of allergic sensitization and appear to be strongly associated with heightened allergenicity. PMID:22523502
NASA Astrophysics Data System (ADS)
Abe, G.; Fentzke, J.; Hsu, V. W.; Brum, C. G.
2012-12-01
This work describes the microphysical properties and variability of meteoric smoke particles (MSPs) at high latitude using the Poker Flat ISR (65.1N, 147.5W). In addition, we present a novel technique for determining height resolved daytime D region neutral temperatures, which takes into account the presence of charged dust. We discuss the temporal/spatial variability and the relation to meteoric input observed and MSP microphysical properties in the polar mesopause region. The derived nanometer sized MSPs are consistent with size profiles derived previously using radar/rocket techniques and we note that our results imply a lack of heavy cluster ions below 85 km during the observing period. We examine the sensitivity of the derived sizes and temperatures to background atmospheric models and compare the results with available data sets. We find that he sizes in the range of approximately 0.5 to 1.5nm are in good general agreement with previous radar/rocket studies, but that the variability both temporally and with altitude are greater than at lower latitudes. The observed neutral temperatures are in the nominal range of 130 - 160 K between 70-90 km with several instances of larger departures up to 200 K indicating that wave activity may be present. This work provides a template for potential use at many other radar sites for the determination of microphysical properties of MSPs and day-time neutral temperature in the D region that show good general agreement with NRL-MSISE-00 temperatures during the observing period.
The basic aerodynamics of floatation
Davies, M.J.; Wood, D.H.
1983-09-01
The original derivation of the basic theory governing the aerodynamics of both hovercraft and modern floatation ovens, requires the validity of some extremely crude assumptions. However, the basic theory is surprisingly accurate. It is shown that this accuracy occurs because the final expression of the basic theory can be derived by approximating the full Navier-Stokes equations in a manner that clearly shows the limitations of the theory. These limitations are used in discussing the relatively small discrepancies between the theory and experiment, which may not be significant for practical purposes.
MicroRNA-21 Increases Proliferation and Cisplatin Sensitivity of Osteosarcoma-Derived Cells.
Vanas, Vanita; Haigl, Barbara; Stockhammer, Verena; Sutterlüty-Fall, Hedwig
2016-01-01
Osteosarcoma is the most common primary bone tumor and poor prognosis for osteosarcoma patients is mainly due to chemotherapy resistance. MicroRNAs are important to maintain pathophysiological mechanisms of cancer and influence cell sensitivity to chemotherapy. In this study, we tested the functions of microRNA-21 for malignant features as well as for drug resistance of osteosarcoma. We used Northern blot to measure microRNA-21 levels in osteosarcoma-derived cell lines. MicroRNA-21 activity was modulated by either expressing a sponge to decrease its activity in an osteosarcoma-derived cell line expressing high levels of microRNA-21 or by introducing pri-microRNA-21 in a cell line with low endogenous levels. Cell migration was determined in a scratch assay and cell proliferation was measured by performing growth curve analysis. Sensitivity of the cells towards chemotherapeutics was investigated by performing cell viability assays and calculating the IC50 values. While cell migration was unaffected by modulated microRNA-21 levels, microRNA-21 inhibition slowed proliferation and exogenously expressed microRNA-21 promoted this process. Modulated microRNA-21 activity failed to effect sensitivity of osteosarcoma-derived cell lines to doxorubicin or methotrexate. Contrarily, reduction of microRNA-21 activity resulted in enhanced resistance towards cisplatin while ectopic expression of microRNA-21 showed the opposite effect. Increased microRNA-21 levels repressed the expression of Sprouty2 and ectopic expression of Sprouty2 was able to largely rescue the observed effects of microRNA-21 in osteosarcoma. In summary, our data indicate that in osteosarcoma microRNA-21 expression is an important component for regulation of cell proliferation and for determining sensitivity to cisplatin. PMID:27513462
MicroRNA-21 Increases Proliferation and Cisplatin Sensitivity of Osteosarcoma-Derived Cells
Vanas, Vanita; Haigl, Barbara; Stockhammer, Verena; Sutterlüty-Fall, Hedwig
2016-01-01
Osteosarcoma is the most common primary bone tumor and poor prognosis for osteosarcoma patients is mainly due to chemotherapy resistance. MicroRNAs are important to maintain pathophysiological mechanisms of cancer and influence cell sensitivity to chemotherapy. In this study, we tested the functions of microRNA-21 for malignant features as well as for drug resistance of osteosarcoma. We used Northern blot to measure microRNA-21 levels in osteosarcoma-derived cell lines. MicroRNA-21 activity was modulated by either expressing a sponge to decrease its activity in an osteosarcoma-derived cell line expressing high levels of microRNA-21 or by introducing pri-microRNA-21 in a cell line with low endogenous levels. Cell migration was determined in a scratch assay and cell proliferation was measured by performing growth curve analysis. Sensitivity of the cells towards chemotherapeutics was investigated by performing cell viability assays and calculating the IC50 values. While cell migration was unaffected by modulated microRNA-21 levels, microRNA-21 inhibition slowed proliferation and exogenously expressed microRNA-21 promoted this process. Modulated microRNA-21 activity failed to effect sensitivity of osteosarcoma-derived cell lines to doxorubicin or methotrexate. Contrarily, reduction of microRNA-21 activity resulted in enhanced resistance towards cisplatin while ectopic expression of microRNA-21 showed the opposite effect. Increased microRNA-21 levels repressed the expression of Sprouty2 and ectopic expression of Sprouty2 was able to largely rescue the observed effects of microRNA-21 in osteosarcoma. In summary, our data indicate that in osteosarcoma microRNA-21 expression is an important component for regulation of cell proliferation and for determining sensitivity to cisplatin. PMID:27513462
Ding, Changfeng; Ma, Yibing; Li, Xiaogang; Zhang, Taolin; Wang, Xingxiang
2016-02-13
The combination of food quality standard and soil-plant transfer models can be used to derive critical limits of heavy metals for agricultural soils. In this paper, a robust methodology is presented, taking the variations of plant species and cultivars and soil properties into account to derive soil thresholds for lead (Pb) applying species sensitivity distribution (SSD). Three species of root vegetables (four cultivars each for radish, carrot, and potato) were selected to investigate their sensitivity differences for accumulating Pb through greenhouse experiment. Empirical soil-plant transfer model was developed from carrot New Kuroda grown in twenty-one soils covering a wide variation in physicochemical properties and was used to normalize the bioaccumulation data of non-model cultivars. The relationship was then validated to be reliable and would not cause over-protection using data from field experimental sites and published independent studies. The added hazardous concentration for protecting 95% of the cultivars not exceeding the food quality standard (HC5add) were then calculated from the Burr Type III function fitted SSD curves. The derived soil Pb thresholds based on the added risk approach (total soil concentration subtracting the natural background part) were presented as continuous or scenario criteria depending on the combination of soil pH and CEC. PMID:26513560
Numerical Aerodynamic Simulation
NASA Technical Reports Server (NTRS)
1989-01-01
An overview of historical and current numerical aerodynamic simulation (NAS) is given. The capabilities and goals of the Numerical Aerodynamic Simulation Facility are outlined. Emphasis is given to numerical flow visualization and its applications to structural analysis of aircraft and spacecraft bodies. The uses of NAS in computational chemistry, engine design, and galactic evolution are mentioned.
Uncertainty in Computational Aerodynamics
NASA Technical Reports Server (NTRS)
Luckring, J. M.; Hemsch, M. J.; Morrison, J. H.
2003-01-01
An approach is presented to treat computational aerodynamics as a process, subject to the fundamental quality assurance principles of process control and process improvement. We consider several aspects affecting uncertainty for the computational aerodynamic process and present a set of stages to determine the level of management required to meet risk assumptions desired by the customer of the predictions.
Computation of dragonfly aerodynamics
NASA Astrophysics Data System (ADS)
Gustafson, Karl; Leben, Robert
1991-04-01
Dragonflies are seen to hover and dart, seemingly at will and in remarkably nimble fashion, with great bursts of speed and effectively discontinuous changes of direction. In their short lives, their gossamer flight provides us with glimpses of an aerodynamics of almost extraterrestrial quality. Here we present the first computer simulations of such aerodynamics.
NASA Technical Reports Server (NTRS)
Green, Lawrence L.; Newman, Perry A.; Haigler, Kara J.
1993-01-01
The computational technique of automatic differentiation (AD) is applied to a three-dimensional thin-layer Navier-Stokes multigrid flow solver to assess the feasibility and computational impact of obtaining exact sensitivity derivatives typical of those needed for sensitivity analyses. Calculations are performed for an ONERA M6 wing in transonic flow with both the Baldwin-Lomax and Johnson-King turbulence models. The wing lift, drag, and pitching moment coefficients are differentiated with respect to two different groups of input parameters. The first group consists of the second- and fourth-order damping coefficients of the computational algorithm, whereas the second group consists of two parameters in the viscous turbulent flow physics modelling. Results obtained via AD are compared, for both accuracy and computational efficiency with the results obtained with divided differences (DD). The AD results are accurate, extremely simple to obtain, and show significant computational advantage over those obtained by DD for some cases.
Oxalyl-CPG: a labile support for synthesis of sensitive oligonucleotide derivatives.
Alul, R H; Singman, C N; Zhang, G R; Letsinger, R L
1991-01-01
A procedure is described for linking nucleosides covalently to controlled pore glass or cross-linked polystyrene supports by means of an oxalyl anchor. Though stable to triethylamine and diisopropylamine, the nucleoside-oxalyl link can be cleaved within a few minutes at room temperature with ammonium hydroxide in methanol. This new anchor can be used in automated synthesis of conventional oligonucleotides. The primary value, however, is that it enables one to employ solid support methodology to synthesize a variety of base-sensitive oligonucleotide derivatives, as illustrated here by synthesis of oligomers with base protecting groups intact and with methyl phosphotriester groups at the internucleoside links. PMID:2027761
Testing sensitivity of the LISFLOOD subgrid hydraulic model to SAR image derived information
NASA Astrophysics Data System (ADS)
Wood, Melissa; Bates, Paul; Neal, Jeff; Hostache, Renaud; Matgen, Patrick; Chini, Marco; Giustarini, Laura
2013-04-01
There has been much interest in the use of Synthetic Aperture Radar (SAR) images to indirectly estimate flood extent and flood elevation to aid the understanding of fluvial flood inundation processes. SAR remote sensing satellites are capable of all-weather day/night observations that can discriminate between land and smooth open water surfaces over large scales. By combining SAR derived information with 2D hydraulic models and terrain data, the mechanisms of flooding can be better simulated therefore enabling more accurate and reliable flood forecasting. The objective of this study is to test the sensitivity of a LISFLOOD subgrid 2D model to its main parameters (i.e. roughness coefficient, river bathymetry) using SAR derived flood extent maps. Because of SAR imaging techniques and processing steps used to derive the flood information, any SAR-derived flood extent image will contain inherent uncertainty. We therefore use the uncertainty of the SAR information to obtain a range of plausible parameters to test sensitivity of the hydraulic model. LISFLOOD is a distributed 2D model developed at the University of Bristol and designed for use with larger ungauged river catchments. The version used employs a subgrid procedure which allows any size of river channel below that of the grid resolution to be represented. This procedure has been shown to improve hydraulic connectivity within the modelled flooded area and thus improve flood prediction for data sparse areas. A hydrodynamic LISFLOOD subgrid model of the River Severn at Tewkesbury covering a domain area of 50x70km and including the confluence with a major tributary (the River Avon) will be utilised. A complete storm hydrograph will be used as inflow to the model to simulate the full flood event. Surveyed cross section and gauged daily flows are also available for the River Severn. Therefore, the model results using variable parameters can be compared against results obtained from ground observations to further
Applied aerodynamics: Challenges and expectations
NASA Technical Reports Server (NTRS)
Peterson, Victor L.; Smith, Charles A.
1993-01-01
Aerospace is the leading positive contributor to this country's balance of trade, derived largely from the sale of U.S. commercial aircraft around the world. This powerfully favorable economic situation is being threatened in two ways: (1) the U.S. portion of the commercial transport market is decreasing, even though the worldwide market is projected to increase substantially; and (2) expenditures are decreasing for military aircraft, which often serve as proving grounds for advanced aircraft technology. To retain a major share of the world market for commercial aircraft and continue to provide military aircraft with unsurpassed performance, the U.S. aerospace industry faces many technological challenges. The field of applied aerodynamics is necessarily a major contributor to efforts aimed at meeting these technological challenges. A number of emerging research results that will provide new opportunities for applied aerodynamicists are discussed. Some of these have great potential for maintaining the high value of contributions from applied aerodynamics in the relatively near future. Over time, however, the value of these contributions will diminish greatly unless substantial investments continue to be made in basic and applied research efforts. The focus: to increase understanding of fluid dynamic phenomena, identify new aerodynamic concepts, and provide validated advanced technology for future aircraft.
Mathematical modeling of the aerodynamic characteristics in flight dynamics
NASA Technical Reports Server (NTRS)
Tobak, M.; Chapman, G. T.; Schiff, L. B.
1984-01-01
Basic concepts involved in the mathematical modeling of the aerodynamic response of an aircraft to arbitrary maneuvers are reviewed. The original formulation of an aerodynamic response in terms of nonlinear functionals is shown to be compatible with a derivation based on the use of nonlinear functional expansions. Extensions of the analysis through its natural connection with ideas from bifurcation theory are indicated.
In silico modeling predicts drug sensitivity of patient-derived cancer cells
2014-01-01
Background Glioblastoma (GBM) is an aggressive disease associated with poor survival. It is essential to account for the complexity of GBM biology to improve diagnostic and therapeutic strategies. This complexity is best represented by the increasing amounts of profiling (“omics”) data available due to advances in biotechnology. The challenge of integrating these vast genomic and proteomic data can be addressed by a comprehensive systems modeling approach. Methods Here, we present an in silico model, where we simulate GBM tumor cells using genomic profiling data. We use this in silico tumor model to predict responses of cancer cells to targeted drugs. Initially, we probed the results from a recent hypothesis-independent, empirical study by Garnett and co-workers that analyzed the sensitivity of hundreds of profiled cancer cell lines to 130 different anticancer agents. We then used the tumor model to predict sensitivity of patient-derived GBM cell lines to different targeted therapeutic agents. Results Among the drug-mutation associations reported in the Garnett study, our in silico model accurately predicted ~85% of the associations. While testing the model in a prospective manner using simulations of patient-derived GBM cell lines, we compared our simulation predictions with experimental data using the same cells in vitro. This analysis yielded a ~75% agreement of in silico drug sensitivity with in vitro experimental findings. Conclusions These results demonstrate a strong predictability of our simulation approach using the in silico tumor model presented here. Our ultimate goal is to use this model to stratify patients for clinical trials. By accurately predicting responses of cancer cells to targeted agents a priori, this in silico tumor model provides an innovative approach to personalizing therapy and promises to improve clinical management of cancer. PMID:24884660
Brain imaging: Reduced sensitivity of RARE-derived techniques to susceptibility effects
Reimer, P.; Allkemper, T.; Schuierer, G.; Peters, P.E.
1996-03-01
Our goal was to evaluate the decreased sensitivity of RARE-derived pulse sequences to susceptibility effects. A variety of RARE-derived T2-weighted fast SE echo (FSE) sequences with echo trains from 6 to 16 were compared with conventional SE (CSE) sequences by means of MRI in phantoms (iron oxides), volunteers (n = 10), and patients (n = 13) with old hemorrhagic brain lesions. All experiments were performed on a 1.5 T clinical MR system (Magnetom SP 4000; Siemens AG, Erlangen, Germany) with constant imaging parameters. Contrast-to-noise ratios (CNRs) of tubes doped with iron oxides at different concentrations and brain areas with physiological iron deposition (red nucleus, substantia nigra) were calculated for CSE and FSE pulse sequences. Areas of old brain hemorrhage were analyzed for lesion conspicuity by blinded analysis with CSE as an internal standard. CNR of iron oxide tubes (TE 90 ins, CSE 45.0 {+-} 3.5, FSE 16 echo trains 28.5 {+-} 3. 1; p {le} 0.01) and iron-containing brain areas decreased with increasing echo trains of FSE sequences. A significantly lower number of old hemorrhagic brain lesions was visible in patients scanned with FSE sequences (6 echo trains: n = 28; 16 echo trains: n = 26) than CSE (n = 40). Our results demonstrate that the sensitivity of RARE-derived techniques to susceptibility effects is significantly decreased compared with CSE. CSE sequences or GE sequences should still be preferred in patients with a history of seizures or intracranial hemorrhage. 25 refs., 3 figs., 1 tabs.
Sensitivity derivatives and optimization of nodal point locations for vibration reduction
NASA Technical Reports Server (NTRS)
Pritchard, Jocelyn I.; Adelman, Howard M.; Haftka, Raphael T.
1987-01-01
A method is developed for sensitivity analysis and optimization of nodal point locations in connection with vibration reduction. A straightforward derivation of the expression for the derivative of nodal locations is given, and the role of the derivative in assessing design trends is demonstrated. An optimization process is developed which uses added lumped masses on the structure as design variables to move the node to a preselected location; for example, where low response amplitude is required or to a point which makes the mode shape nearly orthogonal to the force distribution, thereby minimizing the generalized force. The optimization formulation leads to values for added masses that adjust a nodal location while minimizing the total amount of added mass required to do so. As an example, the node of the second mode of a cantilever box beam is relocated to coincide with the centroid of a prescribed force distribution, thereby reducing the generalized force substantially without adding excessive mass. A comparison with an optimization formulation that directly minimizes the generalized force indicates that nodal placement gives essentially a minimum generalized force when the node is appropriately placed.
ERIC Educational Resources Information Center
Weltner, Klaus
1990-01-01
Describes some experiments showing both qualitatively and quantitatively that aerodynamic lift is a reaction force. Demonstrates reaction forces caused by the acceleration of an airstream and the deflection of an airstream. Provides pictures of demonstration apparatus and mathematical expressions. (YP)
NASA Technical Reports Server (NTRS)
Friedmann, P. P.; Venkatesan, C.
1985-01-01
The aeromechanical stability of a helicopter in ground resonance was analyzed, by incorporating five different aerodynamic models in the coupled rotor/fuselage analysis. The sensitivity of the results to changes in aerodynamic modelling was carefully examined. The theoretical results were compared with experimental data and useful conclusions are drawn regarding the role of aerodynamic modeling on this aeromechanical stability problem. The aerodynamic model which provided the best all around correlation with the experimental data was identified.
Freundlich, Joel S.; Wang, Feng; Vilchèze, Catherine; Gulten, Gulcin; Langley, Robert; Schiehser, Guy A.; Jacobus, David P.; Jacobs, Jr., William R.; Sacchettini, James C.
2009-06-30
Isoniazid (INH) is a frontline antitubercular drug that inhibits the enoyl acyl carrier protein reductase InhA. Novel inhibitors of InhA that are not cross-resistant to INH represent a significant goal in antitubercular chemotherapy. The design, synthesis, and biological activity of a series of triclosan-based inhibitors is reported, including their promising efficacy against INH-resistant strains of M. tuberculosis. Triclosan has been previously shown to inhibit InhA, an essential enoyl acyl carrier protein reductase involved in mycolic acid biosynthesis, the inhibition of which leads to the lysis of Mycobacterium tuberculosis. Using a structure-based drug design approach, a series of 5-substituted triclosan derivatives was developed. Two groups of derivatives with alkyl and aryl substituents, respectively, were identified with dramatically enhanced potency against purified InhA. The most efficacious inhibitor displayed an IC{sub 50} value of 21 nM, which was 50-fold more potent than triclosan. X-ray crystal structures of InhA in complex with four triclosan derivatives revealed the structural basis for the inhibitory activity. Six selected triclosan derivatives were tested against isoniazid-sensitive and resistant strains of M. tuberculosis. Among those, the best inhibitor had an MIC value of 4.7 {mu}g mL{sup -1} (13 {mu}M), which represents a tenfold improvement over the bacteriocidal activity of triclosan. A subset of these triclosan analogues was more potent than isoniazid against two isoniazid-resistant M. tuberculosis strains, demonstrating the significant potential for structure-based design in the development of next generation antitubercular drugs.
NASA Technical Reports Server (NTRS)
Horstman, Raymond H.
1992-01-01
Aerodynamic flow achieved by adding fixed fairings to butterfly valve. When valve fully open, fairings align with butterfly and reduce wake. Butterfly free to turn, so valve can be closed, while fairings remain fixed. Design reduces turbulence in flow of air in internal suction system. Valve aids in development of improved porous-surface boundary-layer control system to reduce aerodynamic drag. Applications primarily aerospace. System adapted to boundary-layer control on high-speed land vehicles.
Aerodynamics of Heavy Vehicles
NASA Astrophysics Data System (ADS)
Choi, Haecheon; Lee, Jungil; Park, Hyungmin
2014-01-01
We present an overview of the aerodynamics of heavy vehicles, such as tractor-trailers, high-speed trains, and buses. We introduce three-dimensional flow structures around simplified model vehicles and heavy vehicles and discuss the flow-control devices used for drag reduction. Finally, we suggest important unsteady flow structures to investigate for the enhancement of aerodynamic performance and future directions for experimental and numerical approaches.
An aerodynamic load criterion for airships
NASA Technical Reports Server (NTRS)
Woodward, D. E.
1975-01-01
A simple aerodynamic bending moment envelope is derived for conventionally shaped airships. This criterion is intended to be used, much like the Naval Architect's standard wave, for preliminary estimates of longitudinal strength requirements. It should be useful in tradeoff studies between speed, fineness ratio, block coefficient, structure weight, and other such general parameters of airship design.
Hematoporphyrin-derivative photodynamic in-vitro sensitivity testing for brain tumors
NASA Astrophysics Data System (ADS)
Plattner, Michael; Bernwick, Walter; Kostron, Herwig
1993-03-01
Brain tumors of various histologies were subjected to an in-vitro photodynamic-sensitivity test. The studies were performed on primary cultures of human glioblastomas, meningiomas, and ependymomas, which were exposed to increasing concentrations of hematoporphyrin derivative and 60 J/cm2 delivered by an argon-dye laser at 632 nm. A growth inhibition of 75% was demonstrated at a concentration of 25 (mu) g and 10 (mu) g HPD/ml medium for two different glioblastomas, respectively. A growth inhibition of 75% was observed in the ependymoma line at 10 and 50 (mu) g HPD/ml with and without light, respectively. The meningioma demonstrated a 75% inhibition already at (mu) g and 75 (mu) g/ml medium with and without light, respectively. These results demonstrate a significant difference in the response of brain tumors to photodynamic treatment (PDT). In vitro-PDT-assay should be taken into account if clinical application of PDT is considered.
2,5-PRODAN derivatives as highly sensitive sensors of low solvent acidity.
Yoon, Alexandra H; Whitworth, Laura C; Wagner, Joel D; Abelt, Christopher J
2014-01-01
Two 5-acyl-2-dimethylaminonaphthalene derivatives, one with a propionyl group and the other with a fused cyclohexanone ring, are investigated as sensors of H-bond-donating ability in protic solvents of low solvent acidity. Their fluorescence is highly quenched in protic solvents, and the quenching order of magnitude is linearly related to the H-bond-donating ability of the solvent as quantified by the solvent acidity (SA) scale. As the solvent acidity increases from 0.15 to 0.40, the fluorescence for both is quenched by more than a factor of ten; thus, they are extremely sensitive sensors of the hydrogen-bond-donating ability in this weakly acidic range. Preferential solvation studies suggest that quenching occurs from a doubly H-bonded excited state. PMID:24853615
Kleidon, Alex; Kravitz, Benjamin S.; Renner, Maik
2015-01-16
We derive analytic expressions of the transient response of the hydrological cycle to surface warming from an extremely simple energy balance model in which turbulent heat fluxes are constrained by the thermodynamic limit of maximum power. For a given magnitude of steady-state temperature change, this approach predicts the transient response as well as the steady-state change in surface energy partitioning and the hydrologic cycle. We show that the transient behavior of the simple model as well as the steady state hydrological sensitivities to greenhouse warming and solar geoengineering are comparable to results from simulations using highly complex models. Many of the global-scale hydrological cycle changes can be understood from a surface energy balance perspective, and our thermodynamically-constrained approach provides a physically robust way of estimating global hydrological changes in response to altered radiative forcing.
NASA Astrophysics Data System (ADS)
Ma, Shengbo; Ting, Hungkit; Ma, Yingzhuang; Zheng, Lingling; Zhang, Miwei; Xiao, Lixin; Chen, Zhijian
2015-05-01
In this paper, smart photovoltaic (SPV) devices, integrating both functions of solar cells and smart windows, was fabricated based on dye-sensitized solar cells using photochromic spiropyran derivatives SIBT as photosensitizers. SPV devices have self-regulated power conversion efficiency (PCE) and light transmission responding to the incident spectra due to the photoisomerization of SIBT. SIBT isomerize from closed-ring form to open-ring form under UV illumination, accompanied with enhanced visible light absorption and electron delocalization. Therefore, increased PCE and absorption in SPV devices were observed under UV treatment and the devices can be restored gradually to the initial status when kept in dark. The SPV devices have self-regulation of PCE and sunlight transmission responding to the changing sun spectra in different times of a day, providing a proper energy usage and a better sun-shading.
Ma, Shengbo; Ting, Hungkit; Ma, Yingzhuang; Zheng, Lingling; Zhang, Miwei; Xiao, Lixin E-mail: lxxiao@pku.edu.cn; Chen, Zhijian E-mail: lxxiao@pku.edu.cn
2015-05-15
In this paper, smart photovoltaic (SPV) devices, integrating both functions of solar cells and smart windows, was fabricated based on dye-sensitized solar cells using photochromic spiropyran derivatives SIBT as photosensitizers. SPV devices have self-regulated power conversion efficiency (PCE) and light transmission responding to the incident spectra due to the photoisomerization of SIBT. SIBT isomerize from closed-ring form to open-ring form under UV illumination, accompanied with enhanced visible light absorption and electron delocalization. Therefore, increased PCE and absorption in SPV devices were observed under UV treatment and the devices can be restored gradually to the initial status when kept in dark. The SPV devices have self-regulation of PCE and sunlight transmission responding to the changing sun spectra in different times of a day, providing a proper energy usage and a better sun-shading.
Aerodynamic Design Optimization on Unstructured Meshes Using the Navier-Stokes Equations
NASA Technical Reports Server (NTRS)
Nielsen, Eric J.; Anderson, W. Kyle
1998-01-01
A discrete adjoint method is developed and demonstrated for aerodynamic design optimization on unstructured grids. The governing equations are the three-dimensional Reynolds-averaged Navier-Stokes equations coupled with a one-equation turbulence model. A discussion of the numerical implementation of the flow and adjoint equations is presented. Both compressible and incompressible solvers are differentiated and the accuracy of the sensitivity derivatives is verified by comparing with gradients obtained using finite differences. Several simplifying approximations to the complete linearization of the residual are also presented, and the resulting accuracy of the derivatives is examined. Demonstration optimizations for both compressible and incompressible flows are given.
Manini, A F; Ilgen, J; Noble, V E; Bamberg, F; Koenig, W; Bohan, J S; Hoffmann, U
2016-01-01
Objectives In patients with acute chest pain, we derived a cutpoint for ischaemia-modified albumin (IMA) and prospectively validated this cutpoint to predict 30-day major adverse cardiac events (MACEs). Methods We prospectively recruited a derivation cohort (18-month period) to establish a serum IMA cutpoint targeting 80% sensitivity. This was followed by a prospective validation cohort study of emergency department patients with acute chest pain at two university hospitals over a 3-month period. A MACE was defined as myocardial infarction, revascularisation or death at 30-day follow-up. Results In the derivation cohort of 151 patients, the IMA cutpoint that achieved 80% sensitivity for MACEs was 75 KU/litre. The sensitivity was prospectively validated in 171 patients consecutively enrolled, of whom 106 underwent multiple-biomarker analysis (19.8% MACE rate, 81% sensitivity of IMA). Furthermore, IMA by itself (81%, p<0.01) and in combination with initial highly sensitive cardiac troponin T (hsTnT) (90%, p<0.001) had significantly higher sensitivity than initial hsTnT (29%) for prediction of MACEs. Conclusions We prospectively validated the sensitive IMA cutpoint of 75 KU/litre with 80% sensitivity for MACEs in patients with acute chest pain. Our data suggest that IMA alone and in combination with initial hsTnT are more sensitive than the initial hsTnT for MACEs. PMID:19850803
Reference values and improvement of aerodynamic drag in professional cyclists.
García-López, Juan; Rodríguez-Marroyo, José Antonio; Juneau, Carl-Etienne; Peleteiro, José; Martínez, Alfredo Córdova; Villa, José Gerardo
2008-02-01
The aims of this study were to measure the aerodynamic drag in professional cyclists, to obtain aerodynamic drag reference values in static and effort positions, to improve the cyclists' aerodynamic drag by modifying their position and cycle equipment, and to evaluate the advantages and disadvantages of these modifications. The study was performed in a wind tunnel with five professional cyclists. Four positions were assessed with a time-trial bike and one position with a standard racing bike. In all positions, aerodynamic drag and kinematic variables were recorded. The drag area for the time-trial bike was 31% higher in the effort than static position, and lower than for the standard racing bike. Changes in the cyclists' position decreased the aerodynamic drag by 14%. The aero-helmet was not favourable for all cyclists. The reliability of aerodynamic drag measures in the wind tunnel was high (r > 0.96, coefficient of variation < 2%). In conclusion, we measured and improved the aerodynamic drag in professional cyclists. Our results were better than those of other researchers who did not assess aerodynamic drag during effort at race pace and who employed different wheels. The efficiency of the aero-helmet, and the validity, reliability, and sensitivity of the wind tunnel and aerodynamic field testing were addressed. PMID:17943597
Saravanan, Kanagarathinam; Srinivasan, Natesan; Thanikachalam, Venugopal; Jayabharathi, Jayaraman
2011-01-01
Some novel imidazole derivatives were developed for highly sensitive chemisensors for transition metal ions. Since these compounds are sensitive to different external stimulations such as UV irradiation, heat, increasing pressure and changing the environmental pH causing colour change and so they can be used as a 'multi-way' optically switchable material. A prominent fluorescence enhancement was found in the presence of transition metal ions such as Hg(2+), Pb(2+) and Cu(2+) and this was suggested to result from the suppression of radiationless transitions from the n-π* state in the chemisensors. The existence of C-H….O intramolecular hydrogen bonding in dmphnpi is confirmed by the Natural Bond Orbital analysis (NBO). The Mulliken, NBO charge analysis and the HOMO-LUMO energies were also calculated. The electric dipole moment (μ) and the first-hyperpolarisability (β) value of the investigated molecules have been studied both experimentally and theoretically which reveal that the synthesized molecules have microscopic non-linear optical (NLO) behaviour with non-zero values. Ground and excited state DFT calculation were carried out in order to find out dipole moment and energy. PMID:20623166
Limantara, Leenawaty; Koehler, Peter; Wilhelm, Brigitte; Porra, Robert J; Scheer, Hugo
2006-01-01
The photostabilities of bacteriochlorophyll a and several of its derivatives, which are of interest as potential sensitizers in photodynamic tumor therapy, were investigated. The pigments were irradiated with light >630 nm in organic solvents (acetone, tetrahydrofuran, pyridine, methanol, ethanol, n-propanol, 2-propanol and toluene) and in aqueous detergent solutions (cetyl-trimethyl-ammonium bromide [CTAB], lauryldimethyl-aminoxide [LDAO] or sodium dodecyl-sulfate [SDS] and Triton X-100 [TX100]). Their stabilities in these different solvents were determined in the presence and absence of an external sensitizer (pyromethyl-pheophorbide a), oxygen, sodium ascorbate and inert gas (Ar) or vacuum. The photodegradation products of bacteriochlorophyll a in acetone solution were isolated, purified by HPLC and analyzed by their absorption spectra and mass spectroscopy. Besides the well-known dehydrogenation products, such as [3-acetyl]-chlorophyll a, which were obtained as by-products, the major products had low absorption in the visible-near infrared spectral range. The spectral signature of the major component of these products was characteristic of linear open-chain tetrapyrroles, but they lacked the characteristic protonation-deprotonation behavior and reactivity of bilins with Zn(++). PMID:16438618
2013-01-01
Background Arecae semen, the dried slice of areca nuts, is a traditional Chinese medicine used to treat intestinal parasitosis, rectal tenesmus and diarrhea. Areca nuts contain a rich amount of polyphenols that have been shown to modulate the functionality of mast cells and T cells. The objective of this study is to investigate the effect of polyphenol-enriched areca nut extracts (PANE) against food allergy, a T cell-mediated immune disorder. Methods BALB/c mice were left untreated or administered with PANE (0.05% and 0.1%) via drinking water throughout the entire experiment. The mice were sensitized with ovalbumin (OVA) twice by intraperitoneal injection, and then repeatedly challenged with OVA by gavage to induce food allergic responses. Results PANE administration attenuated OVA-induced allergic responses, including the occurrence of diarrhea and the infiltration and degranulation of mast cells in the duodenum. The serum level of OVA-specific IgE and the expression of interleukin-4 in the duodenum were suppressed by PANE treatment. In addition, PANE administration induced Gr-1+, IL-10+ and Gr-1+IL-10+ cells in the duodenum. Conclusion These results demonstrate that oral intake of areca-derived polyphenols attenuates food allergic responses accompanied with a decreased Th2 immunity and an enhanced induction of functional myeloid-derived suppressor cells. PMID:23816049
Fercher, Andreas; Ponomarev, Gelii V; Yashunski, Dmitri; Papkovsky, Dmitri
2010-03-01
Several new derivatives of the phosphorescent Pt(II)-coproporphyrin (PtCP) were evaluated with respect to the sensing of intracellular oxygen by phosphorescence quenching. Despite the more favorable molecular charge compared to PtCP, self-loading into mammalian cells was rather inefficient for all the dyes, while cell loading by facilitated transport using transfection reagents produced promising results. The PtCP-NH(2) derivative, which gave best loading efficiency and S/N ratio, was investigated in detail including the optimisation of loading conditions, studies of sub-cellular localization, cytotoxicity, oxygen sensitivity and long-term signal stability. Being spectrally similar to the macromolecular MitoXpress™ probe currently used in this application, the PtCP-NH(2) demonstrated higher loading efficiency and phosphorescent signals, suitability for several problematic cell lines and a slightly increased lifetime scale for the physiological range (0-200 μM O(2)). In physiological experiments with different cell types, mitochondrial uncouplers and inhibitors performed on a time-resolved fluorescence plate reader, this probe produced the anticipated profiles of intracellular oxygen concentration and responses to cell stimulation. Therefore, PtCP-NH(2) represents a convenient probe for the experiments and applications in which monitoring of cellular oxygen levels is required. PMID:20063150
NASA Technical Reports Server (NTRS)
Taylor, Arthur C., III; Hou, Gene W.
1992-01-01
Fundamental equations of aerodynamic sensitivity analysis and approximate analysis for the two dimensional thin layer Navier-Stokes equations are reviewed, and special boundary condition considerations necessary to apply these equations to isolated lifting airfoils on 'C' and 'O' meshes are discussed in detail. An efficient strategy which is based on the finite element method and an elastic membrane representation of the computational domain is successfully tested, which circumvents the costly 'brute force' method of obtaining grid sensitivity derivatives, and is also useful in mesh regeneration. The issue of turbulence modeling is addressed in a preliminary study. Aerodynamic shape sensitivity derivatives are efficiently calculated, and their accuracy is validated on two viscous test problems, including: (1) internal flow through a double throat nozzle, and (2) external flow over a NACA 4-digit airfoil. An automated aerodynamic design optimization strategy is outlined which includes the use of a design optimization program, an aerodynamic flow analysis code, an aerodynamic sensitivity and approximate analysis code, and a mesh regeneration and grid sensitivity analysis code. Application of the optimization methodology to the two test problems in each case resulted in a new design having a significantly improved performance in the aerodynamic response of interest.
Summary analysis of the Gemini entry aerodynamics
NASA Technical Reports Server (NTRS)
Whitnah, A. M.; Howes, D. B.
1972-01-01
The aerodynamic data that were derived in 1967 from the analysis of flight-generated data for the Gemini entry module are presented. These data represent the aerodynamic characteristics exhibited by the vehicle during the entry portion of Gemini 2, 3, 5, 8, 10, 11, and 12 missions. For the Gemini, 5, 8, 10, 11, and 12 missions, the flight-generated lift-to-drag ratios and corresponding angles of attack are compared with the wind tunnel data. These comparisons show that the flight generated lift-to-drag ratios are consistently lower than were anticipated from the tunnel data. Numerous data uncertainties are cited that provide an insight into the problems that are related to an analysis of flight data developed from instrumentation systems, the primary functions of which are other than the evaluation of flight aerodynamic performance.
Rarefield-Flow Shuttle Aerodynamics Flight Model
NASA Technical Reports Server (NTRS)
Blanchard, Robert C.; Larman, Kevin T.; Moats, Christina D.
1994-01-01
A model of the Shuttle Orbiter rarefied-flow aerodynamic force coefficients has been derived from the ratio of flight acceleration measurements. The in-situ, low-frequency (less than 1Hz), low-level (approximately 1 x 10(exp -6) g) acceleration measurements are made during atmospheric re-entry. The experiment equipment designed and used for this task is the High Resolution Accelerometer Package (HiRAP), one of the sensor packages in the Orbiter Experiments Program. To date, 12 HiRAP re-entry mission data sets spanning a period of about 10 years have been processed. The HiRAP-derived aerodynamics model is described in detail. The model includes normal and axial hypersonic continuum coefficient equations as function of angle of attack, body-flap deflection, and elevon deflection. Normal and axial free molecule flow coefficient equations as a function of angle of attack are also presented, along with flight-derived rarefied-flow transition bridging formulae. Comparisons are made between the aerodynamics model, data from the latest Orbiter Operational Aerodynamic Design Data Book, applicable computer simulations, and wind-tunnel data.
Dirksen, K; Verzijl, T; van den Ingh, T S G A M; Vernooij, J C M; van der Laan, L J W; Burgener, I A; Spee, B; Fieten, H
2016-05-01
Common parenchymal liver diseases in dogs include reactive hepatopathies and primary hepatitis (acute or chronic). In chronic hepatitis, there is usually a long subclinical phase. Specific clinical signs become overt only when liver damage is severe and in this phase, treatment is usually less effective. Limited data are available regarding the sensitivity of liver enzyme activity or biomarkers for early detection of subclinical hepatitis. Hepatocyte-derived microRNAs (HDmiRs) were recently identified as promising biomarkers for hepatocellular injury in multiple species. Here, the potential of the HDmiRs miR-122 and miR-148a as sensitive diagnostic biomarkers for hepatocellular injury in Labrador retrievers was investigated. Samples from 66 Labrador retrievers with histologically normal livers, high hepatic copper, and with various forms of liver injury were evaluated for serum alanine aminotransferase (ALT) activity and microRNA values. Median values of HDmiR-122 were 34.6 times higher in dogs with liver injury and high ALT than in normal dogs (95% confidence intervals [CI], 13-95; P <0.001). HDmiR-122 values were significantly increased in dogs with liver injury and normal ALT (4.2 times; 95% CI, 2-12; P <0.01) and in dogs with high hepatic copper concentrations and unremarkable histopathology (2.9 times; 95% CI, 1.1-8.0; P <0.05). Logistic regression analyses demonstrated that miR-122 and miR-148a were both predictors of hepatocellular injury. The sensitivity of miR-122 was 84% (95% CI, 73-93%), making it superior to ALT (55%; 95% CI, 41-68%) for the detection of hepatocellular injury in Labrador retrievers (P <0.001). This study demonstrated that serum HDmiR, particularly miR-122, is a highly sensitive marker for the detection of hepatocellular injury in Labrador retrievers and is a promising new biomarker that may be used for early detection of subclinical hepatitis in dogs. PMID:27021912
Sujith, Ravindran; Kumar, Ravi
2014-01-15
Investigation on the room temperature strain rate sensitivity using depth sensing nanoindentation is carried out on precursor derived HfO{sub 2}/Si-C-N(O) ceramic nanocomposite sintered using pulsed electric current sintering. Using constant load method the strain rate sensitivity values are estimated. Lower strain rate sensitivity of ∼ 3.7 × 10{sup −3} is observed and the limited strain rate sensitivity of these ceramic nanocomposites is explained in terms of cluster model. It is concluded that presence of amorphous Si-C-N(O) clusters are responsible for the limited flowability in these ceramics.
Species sensitivity distributions (SSD) require a large number of measured toxicity values to define a chemical’s toxicity to multiple species. This investigation comprehensively evaluated the accuracy of SSDs generated from toxicity values predicted from interspecies correlation...
NASA Technical Reports Server (NTRS)
Hemsch, Michael J. (Editor); Nielsen, Jack N. (Editor)
1986-01-01
The present conference on tactical missile aerodynamics discusses autopilot-related aerodynamic design considerations, flow visualization methods' role in the study of high angle-of-attack aerodynamics, low aspect ratio wing behavior at high angle-of-attack, supersonic airbreathing propulsion system inlet design, missile bodies with noncircular cross section and bank-to-turn maneuvering capabilities, 'waverider' supersonic cruise missile concepts and design methods, asymmetric vortex sheding phenomena from bodies-of-revolution, and swept shock wave/boundary layer interaction phenomena. Also discussed are the assessment of aerodynamic drag in tactical missiles, the analysis of supersonic missile aerodynamic heating, the 'equivalent angle-of-attack' concept for engineering analysis, the vortex cloud model for body vortex shedding and tracking, paneling methods with vorticity effects and corrections for nonlinear compressibility, the application of supersonic full potential method to missile bodies, Euler space marching methods for missiles, three-dimensional missile boundary layers, and an analysis of exhaust plumes and their interaction with missile airframes.
Yang, Linlin; Guo, Lianshun; Chen, Qianqian; Sun, Huafei; Yan, Hui; Zeng, Qinghua; Zhang, Xianxi; Pan, Xu; Dai, Songyuan
2012-09-01
A series of unsymmetrical phthalocyanine sensitizer candidates with different donor and acceptor substituents, namely ZnPcBPh, ZnPcBOPh, ZnPcBtBu, ZnPcBN(Ph)₂, ZnPcBNHPh, ZnPcBNH₂, ZnPcBNHCH₃ and ZnPcBN(CH₃)₂, were designed and calculated using density functional theory (DFT) and time-dependent DFT calculations. The molecular orbital energy levels, the molecular orbital spatial distributions and the electronic absorption spectra of the ZnPcB series molecules were compared with those of TT7 and TT8 to reveal the substituent effects of different donor and acceptor groups on the phthalocyanine compounds and select good sesitizer candidates. The results show that some of these compounds have considerably smaller orbital energy gaps, red-shifted absorption bands and better charge-separated states, causing them to absorb photons in the lower energy region. Several new absorption bands emerge in the 400-600 nm region, which makes it possible for them to become panchromatic sensitizers. This characteristic is superior to the phthalocyanine sensitizers reported previously, including the current record holder, PcS6. The sensitizer candidates screened in the current work are very promising for providing good performance and might even challenge the photon-to-electricity conversion efficiency record of 4.6% for phthalocyanine sensitizers. PMID:23085158
Stockman, A; Sharpe, L T; Fach, C
1999-08-01
We used two methods to estimate short-wave (S) cone spectral sensitivity. Firstly, we measured S-cone thresholds centrally and peripherally in five trichromats, and in three blue-cone monochromats, who lack functioning middle-wave (M) and long-wave (L) cones. Secondly, we analyzed standard color-matching data. Both methods yielded equivalent results, on the basis of which we propose new S-cone spectral sensitivity functions. At short and middle-wavelengths, our measurements are consistent with the color matching data of Stiles and Burch (1955, Optica Acta, 2, 168-181; 1959, Optica Acta, 6, 1-26), and other psychophysically measured functions, such as pi 3 (Stiles, 1953, Coloquio sobre problemas opticos de la vision, 1, 65-103). At longer wavelengths, S-cone sensitivity has previously been over-estimated. PMID:10492818
Inner workings of aerodynamic sweep
Wadia, A.R.; Szucs, P.N.; Crall, D.W.
1998-10-01
The recent trend in using aerodynamic sweep to improve the performance of transonic blading has been one of the more significant technological evolutions for compression components in turbomachinery. This paper reports on the experimental and analytical assessment of the pay-off derived from both aft and forward sweep technology with respect to aerodynamic performance and stability. The single-stage experimental investigation includes two aft-swept rotors with varying degree and type of aerodynamic sweep and one swept forward rotor. On a back-to-back test basis, the results are compared with an unswept rotor with excellent performance and adequate stall margin. Although designed to satisfy identical design speed requirements as the unswept rotor, the experimental results reveal significant variations in efficiency and stall margin with the swept rotors. At design speed, all the swept rotors demonstrated a peak stage efficiency level that was equal to that of the unswept rotor. However, the forward-swept rotor achieved the highest rotor-alone peak efficiency. At the same time, the forward-swept rotor demonstrated a significant improvement in stall margin relative to the already satisfactory level achieved by the unswept rotor. Increasing the level of aft sweep adversely affected the stall margin. A three-dimensional viscous flow analysis was used to assist in the interpretation of the data. The reduced shock/boundary layer interaction, resulting from reduced axial flow diffusion and less accumulation of centrifuged blade surface boundary layer at the tip, was identified as the prime contributor to the enhanced performance with forward sweep. The impact of tip clearance on the performance and stability for one of the aft-swept rotors was also assessed.
NASA Technical Reports Server (NTRS)
Liu, Tianshu; Bencic, T.; Sullivan, J. P.
1999-01-01
This article reviews new advances and applications of pressure sensitive paints in aerodynamic testing. Emphasis is placed on important technical aspects of pressure sensitive paint including instrumentation, data processing, and uncertainty analysis.
Mensah, Paul K; Palmer, Caroline G; Muller, Wilhelmine J
2013-10-01
Glyphosate-based herbicides are among the leading products used in South Africa to control weeds and invading alien plant species. Although these herbicides ultimately find their way into aquatic ecosystems, South Africa has no water quality guideline based on indigenous species to protect the country's aquatic biota against these biocides. In this study, South African water quality guidelines (SAWQGs) for Roundup(®) based on species sensitivity distribution (SSD) using indigenous aquatic biota were developed. Short-term and long-term toxicity tests were conducted with eight different aquatic species belonging to five different taxonomic groups. Static non-renewal experimental methods were employed for short-term lethal tests (≤4 days), and static renewal for long-term sublethal tests (≥4 days ≤21 days). LC50 values for animal exposure and EC50 values for algae were calculated using probit analysis and linear regression of transformed herbicide concentration as natural logarithm data against percentage growth inhibition, respectively. No effect concentration (NEC) was determined based on the dynamic energy budget model, using survival data. The LC50, EC50 and NEC values were used to develop species sensitivity distribution (SSD) concentrations for Roundup(®). Based on the SSD concentrations, the short-term and long-term SAWQGs for Roundup(®) were derived as 0.250 (0.106-0.589) mg/L, and 0.002 (0.000-0.021) mg/L, respectively. These WQGs may be useful in protecting South African aquatic life against transient or long-term exposure to glyphosate-based chemicals as part of integrated water resources management. PMID:23856119
Applied computational aerodynamics
Henne, P.A.
1990-01-01
The present volume discusses the original development of the panel method, the mapping solutions and singularity distributions of linear potential schemes, the capabilities of full-potential, Euler, and Navier-Stokes schemes, the use of the grid-generation methodology in applied aerodynamics, subsonic airfoil design, inverse airfoil design for transonic applications, the divergent trailing-edge airfoil innovation in CFD, Euler and potential computational results for selected aerodynamic configurations, and the application of CFD to wing high-lift systems. Also discussed are high-lift wing modifications for an advanced-capability EA-6B aircraft, Navier-Stokes methods for internal and integrated propulsion system flow predictions, the use of zonal techniques for analysis of rotor-stator interaction, CFD applications to complex configurations, CFD applications in component aerodynamic design of the V-22, Navier-Stokes computations of a complete F-16, CFD at supersonic/hypersonic speeds, and future CFD developments.
Powered-Lift Aerodynamics and Acoustics. [conferences
NASA Technical Reports Server (NTRS)
1976-01-01
Powered lift technology is reviewed. Topics covered include: (1) high lift aerodynamics; (2) high speed and cruise aerodynamics; (3) acoustics; (4) propulsion aerodynamics and acoustics; (5) aerodynamic and acoustic loads; and (6) full-scale and flight research.
Aerodynamics of thrust vectoring
NASA Technical Reports Server (NTRS)
Tseng, J. B.; Lan, C. Edward
1989-01-01
Thrust vectoring as a means to enhance maneuverability and aerodynamic performane of a tactical aircraft is discussed. This concept usually involves the installation of a multifunction nozzle. With the nozzle, the engine thrust can be changed in direction without changing the attitude of the aircraft. Change in the direction of thrust induces a significant change in the aerodynamic forces on the aircraft. Therefore, this device can be used for lift-augmenting as well as stability and control purposes. When the thrust is deflected in the longitudinal direction, the lift force and the pitching stability can be manipulated, while the yawing stability can be controlled by directing the thrust in the lateral direction.
NASA Technical Reports Server (NTRS)
Hou, Jean W.; Sheen, Jeen S.
1987-01-01
The aim of this study is to find a reliable numerical algorithm to calculate thermal design sensitivities of a transient problem with discontinuous derivatives. The thermal system of interest is a transient heat conduction problem related to the curing process of a composite laminate. A logical function which can smoothly approximate the discontinuity is introduced to modify the system equation. Two commonly used methods, the adjoint variable method and the direct differentiation method, are then applied to find the design derivatives of the modified system. The comparisons of numerical results obtained by these two methods demonstrate that the direct differentiation method is a better choice to be used in calculating thermal design sensitivity.
Orion Crew Module Aerodynamic Testing
NASA Technical Reports Server (NTRS)
Murphy, Kelly J.; Bibb, Karen L.; Brauckmann, Gregory J.; Rhode, Matthew N.; Owens, Bruce; Chan, David T.; Walker, Eric L.; Bell, James H.; Wilson, Thomas M.
2011-01-01
The Apollo-derived Orion Crew Exploration Vehicle (CEV), part of NASA s now-cancelled Constellation Program, has become the reference design for the new Multi-Purpose Crew Vehicle (MPCV). The MPCV will serve as the exploration vehicle for all near-term human space missions. A strategic wind-tunnel test program has been executed at numerous facilities throughout the country to support several phases of aerodynamic database development for the Orion spacecraft. This paper presents a summary of the experimental static aerodynamic data collected to-date for the Orion Crew Module (CM) capsule. The test program described herein involved personnel and resources from NASA Langley Research Center, NASA Ames Research Center, NASA Johnson Space Flight Center, Arnold Engineering and Development Center, Lockheed Martin Space Sciences, and Orbital Sciences. Data has been compiled from eight different wind tunnel tests in the CEV Aerosciences Program. Comparisons are made as appropriate to highlight effects of angle of attack, Mach number, Reynolds number, and model support system effects.
Computer graphics in aerodynamic analysis
NASA Technical Reports Server (NTRS)
Cozzolongo, J. V.
1984-01-01
The use of computer graphics and its application to aerodynamic analyses on a routine basis is outlined. The mathematical modelling of the aircraft geometries and the shading technique implemented are discussed. Examples of computer graphics used to display aerodynamic flow field data and aircraft geometries are shown. A future need in computer graphics for aerodynamic analyses is addressed.
NASA Astrophysics Data System (ADS)
Katz, Joseph
2006-01-01
Race car performance depends on elements such as the engine, tires, suspension, road, aerodynamics, and of course the driver. In recent years, however, vehicle aerodynamics gained increased attention, mainly due to the utilization of the negative lift (downforce) principle, yielding several important performance improvements. This review briefly explains the significance of the aerodynamic downforce and how it improves race car performance. After this short introduction various methods to generate downforce such as inverted wings, diffusers, and vortex generators are discussed. Due to the complex geometry of these vehicles, the aerodynamic interaction between the various body components is significant, resulting in vortex flows and lifting surface shapes unlike traditional airplane wings. Typical design tools such as wind tunnel testing, computational fluid dynamics, and track testing, and their relevance to race car development, are discussed as well. In spite of the tremendous progress of these design tools (due to better instrumentation, communication, and computational power), the fluid dynamic phenomenon is still highly nonlinear, and predicting the effect of a particular modification is not always trouble free. Several examples covering a wide range of vehicle shapes (e.g., from stock cars to open-wheel race cars) are presented to demonstrate this nonlinear nature of the flow field.
Aerodynamics Improve Wind Wheel
NASA Technical Reports Server (NTRS)
Ramsey, V. W.
1982-01-01
Modifications based on aerodynamic concepts would raise efficiency of wind-wheel electric-power generator. Changes smooth airflow, to increase power output, without increasing size of wheel. Significant improvements in efficiency anticipated without any increase in size or number of moving parts and without departing from simplicity of original design.
Prediction and Validation of Mars Pathfinder Hypersonic Aerodynamic Data Base
NASA Technical Reports Server (NTRS)
Gnoffo, Peter A.; Braun, Robert D.; Weilmuenster, K. James; Mitcheltree, Robert A.; Engelund, Walter C.; Powell, Richard W.
1998-01-01
Postflight analysis of the Mars Pathfinder hypersonic, continuum aerodynamic data base is presented. Measured data include accelerations along the body axis and axis normal directions. Comparisons of preflight simulation and measurements show good agreement. The prediction of two static instabilities associated with movement of the sonic line from the shoulder to the nose and back was confirmed by measured normal accelerations. Reconstruction of atmospheric density during entry has an uncertainty directly proportional to the uncertainty in the predicted axial coefficient. The sensitivity of the moment coefficient to freestream density, kinetic models and center-of-gravity location are examined to provide additional consistency checks of the simulation with flight data. The atmospheric density as derived from axial coefficient and measured axial accelerations falls within the range required for sonic line shift and static stability transition as independently determined from normal accelerations.
Zhang, Cai-Rong; Liu, Li; Liu, Zi-Jiang; Shen, Yu-Lin; Sun, Yi-Tong; Wu, You-Zhi; Chen, Yu-Hong; Yuan, Li-Hua; Wang, Wei; Chen, Hong-Shan
2012-09-01
The photon to current conversion efficiency of dye-sensitized solar cells (DSCs) can be significantly affected by dye sensitizers. The design of novel dye sensitizers with good performance in DSCs depend on the dye's information about electronic structures and optical properties. Here, the geometries, electronic structures, as well as the dipole moments and polarizabilities of organic dye sensitizers C343 and 20 kinds of NKX derivatives were calculated using density functional theory (DFT), and the computations of the time dependent DFT with different functionals were performed to explore the electronic absorption properties. Based upon the calculated results and the reported experimental work, we analyzed the role of different conjugate bridges, chromophores, and electron acceptor groups in tuning the geometries, electronic structures, optical properties of dye sensitizers, and the effects on the parameters of DSCs were also investigated. PMID:23117291
Aerodynamic heated steam generating apparatus
Kim, K.
1986-08-12
An aerodynamic heated steam generating apparatus is described which consists of: an aerodynamic heat immersion coil steam generator adapted to be located on the leading edge of an airframe of a hypersonic aircraft and being responsive to aerodynamic heating of water by a compression shock airstream to produce steam pressure; an expansion shock air-cooled condensor adapted to be located in the airframe rearward of and operatively coupled to the aerodynamic heat immersion coil steam generator to receive and condense the steam pressure; and an aerodynamic heated steam injector manifold adapted to distribute heated steam into the airstream flowing through an exterior generating channel of an air-breathing, ducted power plant.
Hypersonic Arbitrary-Body Aerodynamics (HABA) for conceptual design
Salguero, D.E.
1990-03-15
The Hypersonic Arbitrary-Body Aerodynamics (HABA) computer program predicts static and dynamic aerodynamic derivatives at hypersonic speeds for any vehicle geometry. It is intended to be used during conceptual design studies where fast computational speed is required. It uses the same geometry and hypersonic aerodynamic methods as the Mark IV Supersonic/Hypersonic Arbitrary-Body Program (SHABP) developed under sponsorship of the Air Force Flight Dynamics Laboratory; however, the input and output formats have been improved to make it easier to use. This program is available as part of the Department 9140 CAE software.
Prediction of Aerodynamic Coefficients using Neural Networks for Sparse Data
NASA Technical Reports Server (NTRS)
Rajkumar, T.; Bardina, Jorge; Clancy, Daniel (Technical Monitor)
2002-01-01
Basic aerodynamic coefficients are modeled as functions of angles of attack and sideslip with vehicle lateral symmetry and compressibility effects. Most of the aerodynamic parameters can be well-fitted using polynomial functions. In this paper a fast, reliable way of predicting aerodynamic coefficients is produced using a neural network. The training data for the neural network is derived from wind tunnel test and numerical simulations. The coefficients of lift, drag, pitching moment are expressed as a function of alpha (angle of attack) and Mach number. The results produced from preliminary neural network analysis are very good.
Image processing of aerodynamic data
NASA Technical Reports Server (NTRS)
Faulcon, N. D.
1985-01-01
The use of digital image processing techniques in analyzing and evaluating aerodynamic data is discussed. An image processing system that converts images derived from digital data or from transparent film into black and white, full color, or false color pictures is described. Applications to black and white images of a model wing with a NACA 64-210 section in simulated rain and to computed low properties for transonic flow past a NACA 0012 airfoil are presented. Image processing techniques are used to visualize the variations of water film thicknesses on the wing model and to illustrate the contours of computed Mach numbers for the flow past the NACA 0012 airfoil. Since the computed data for the NACA 0012 airfoil are available only at discrete spatial locations, an interpolation method is used to provide values of the Mach number over the entire field.
The basic aerodynamics of floatation
NASA Astrophysics Data System (ADS)
Davies, M. J.; Wood, D. H.
1983-09-01
It is pointed out that the basic aerodynamics of modern floatation ovens, in which the continuous, freshly painted metal strip is floated, dried, and cured, is the two-dimensional analog of that of hovercraft. The basic theory for the static lift considered in connection with the study of hovercraft has had spectacular success in describing the experimental results. This appears surprising in view of the crudity of the theory. The present investigation represents an attempt to explore the reasons for this success. An outline of the basic theory is presented and an approach is shown for deriving the resulting expressions for the lift from the full Navier-Stokes equations in a manner that clearly indicates the limitations on the validity of the expressions. Attention is given to the generally good agreement between the theory and the axisymmetric (about the centerline) results reported by Jaumotte and Kiedrzynski (1965).
Kiyohara, Yumiko; Yoshino, Kiyoshi; Kubota, Satoshi; Okuyama, Hiroaki; Endo, Hiroko; Ueda, Yutaka; Kimura, Toshihiro; Kimura, Tadashi; Kamiura, Shoji; Inoue, Masahiro
2016-04-01
Several molecular targeting drugs are being evaluated for endometrial cancer; selecting patients whose cancers are sensitive to these agents is of paramount importance. Previously, we developed the cancer tissue-originated spheroid method for primary cancer cells taken from patients' tumors as well as patient-derived xenografts. In this study, we successfully prepared and cultured cancer tissue-originated spheroids from endometrial cancers. Characteristics of the original tumors were well retained in cancer tissue-originated spheroids including morphology and expression of p53 or neuroendocrine markers. We screened 79 molecular targeting drugs using two cancer tissue-originated spheroid lines derived from endometrioid adenocarcinoma grade 3 and serous adenocarcinoma. Among several hits, we focused on everolimus, a mammalian target of rapamycin complex 1 inhibitor, and YM155, a survivin inhibitor. When sensitivity to everolimus or YM155 was assessed in 12 or 11 cancer tissue-originated spheroids, respectively, from different endometrial cancer patients, the sensitivity varied substantially. The cancer tissue-originated spheroids sensitive to everolimus showed remarkable suppression of proliferation. The phosphorylation status of the mammalian target of rapamycin complex 1 downstream molecules before and after everolimus treatment did not predict the effect of the drug. In contrast, the cancer tissue-originated spheroids sensitive to YM155 showed remarkable cell death. The effect of YM155 was also confirmed in vivo. The histological type correlated with YM155 sensitivity; non-endometrioid adenocarcinomas were sensitive and endometrioid adenocarcinomas were resistant. Non-canonical autophagic cell death was the most likely cause of cell death in a sensitive cancer tissue-originated spheroid. Thus, sensitivity assays using cancer tissue-originated spheroids from endometrial cancers may be useful for screening drugs and finding biomarkers. PMID:26825848
Unsteady aerodynamic modeling for arbitrary motions. [for active control techniques
NASA Technical Reports Server (NTRS)
Edwards, J. W.
1977-01-01
Results indicating that unsteady aerodynamic loads derived under the assumption of simple harmonic motions executed by airfoil or wing can be extended to arbitrary motions are summarized. The generalized Theodorsen (1953) function referable to loads due to simple harmonic oscillations of a wing section in incompressible flow, the Laplace inversion integral for unsteady aerodynamic loads, calculations of root loci of aeroelastic loads, and analysis of generalized compressible transient airloads are discussed.
Efficient Global Aerodynamic Modeling from Flight Data
NASA Technical Reports Server (NTRS)
Morelli, Eugene A.
2012-01-01
A method for identifying global aerodynamic models from flight data in an efficient manner is explained and demonstrated. A novel experiment design technique was used to obtain dynamic flight data over a range of flight conditions with a single flight maneuver. Multivariate polynomials and polynomial splines were used with orthogonalization techniques and statistical modeling metrics to synthesize global nonlinear aerodynamic models directly and completely from flight data alone. Simulation data and flight data from a subscale twin-engine jet transport aircraft were used to demonstrate the techniques. Results showed that global multivariate nonlinear aerodynamic dependencies could be accurately identified using flight data from a single maneuver. Flight-derived global aerodynamic model structures, model parameter estimates, and associated uncertainties were provided for all six nondimensional force and moment coefficients for the test aircraft. These models were combined with a propulsion model identified from engine ground test data to produce a high-fidelity nonlinear flight simulation very efficiently. Prediction testing using a multi-axis maneuver showed that the identified global model accurately predicted aircraft responses.
NASA Astrophysics Data System (ADS)
Cain, T.; Owen, R.; Walton, C.
2005-02-01
The scramjet flight test Hyshot-2, flew on the 30 July 2002. The programme, led by the University of Queensland, had the primary objective of obtaining supersonic combustion data in flight for comparison with measurements made in shock tunnels. QinetiQ was one of the sponsors, and also provided aerodynamic data and trajectory predictions for the ballistic re-entry of the spinning sounding rocket. The unconventional missile geometry created by the nose-mounted asymmetric-scramjet in conjunction with the high angle of attack during re-entry makes the problem interesting. This paper presents the wind tunnel measurements and aerodynamic calculations used as input for the trajectory prediction. Indirect comparison is made with data obtained in the Hyshot-2 flight using a 6 degree-of-freedom trajectory simulation.
Advanced Aerodynamic Control Effectors
NASA Technical Reports Server (NTRS)
Wood, Richard M.; Bauer, Steven X. S.
1999-01-01
A 1990 research program that focused on the development of advanced aerodynamic control effectors (AACE) for military aircraft has been reviewed and summarized. Data are presented for advanced planform, flow control, and surface contouring technologies. The data show significant increases in lift, reductions in drag, and increased control power, compared to typical aerodynamic designs. The results presented also highlighted the importance of planform selection in the design of a control effector suite. Planform data showed that dramatic increases in lift (greater than 25%) can be achieved with multiple wings and a sawtooth forebody. Passive porosity and micro drag generator control effector data showed control power levels exceeding that available from typical effectors (moving surfaces). Application of an advanced planform to a tailless concept showed benefits of similar magnitude as those observed in the generic studies.
NASA Technical Reports Server (NTRS)
Cole, Jennifer Hansen
2010-01-01
This slide presentation reviews some of the basic principles of aerodynamics. Included in the presentation are: a few demonstrations of the principles, an explanation of the concepts of lift, drag, thrust and weight, a description of Bernoulli's principle, the concept of the airfoil (i.e., the shape of the wing) and how that effects lift, and the method of controlling an aircraft by manipulating the four forces using control surfaces.
NASA Technical Reports Server (NTRS)
Karman, Steve L., Jr.
2011-01-01
The Aeronautics Research Mission Directorate (ARMD) sent out an NASA Research Announcement (NRA) for proposals soliciting research and technical development. The proposed research program was aimed at addressing the desired milestones and outcomes of ROA (ROA-2006) Subtopic A.4.1.1 Advanced Computational Methods. The second milestone, SUP.1.06.02 Robust, validated mesh adaptation and error quantification for near field Computational Fluid Dynamics (CFD), was addressed by the proposed research. Additional research utilizing the direct links to geometry through a CAD interface enabled by this work will allow for geometric constraints to be applied and address the final milestone, SUP2.07.06 Constrained low-drag supersonic aerodynamic design capability. The original product of the proposed research program was an integrated system of tools that can be used for the mesh mechanics required for rapid high fidelity analysis and for design of supersonic cruise vehicles. These Euler and Navier-Stokes volume grid manipulation tools were proposed to efficiently use parallel processing. The mesh adaptation provides a systematic approach for achieving demonstrated levels of accuracy in the solutions. NASA chose to fund only the mesh generation/adaptation portion of the proposal. So this report describes the completion of the proposed tasks for mesh creation, manipulation and adaptation as it pertains to sonic boom prediction of supersonic configurations.
Rarefied-flow Shuttle aerodynamics model
NASA Technical Reports Server (NTRS)
Blanchard, Robert C.; Larman, Kevin T.; Moats, Christina D.
1993-01-01
A rarefied-flow shuttle aerodynamic model spanning the hypersonic continuum to the free molecule-flow regime was formulated. The model development has evolved from the High Resolution Accelerometer Package (HiRAP) experiment conducted on the Orbiter since 1983. The complete model is described in detail. The model includes normal and axial hypersonic continuum coefficient equations as functions of angle-of-attack, body flap deflection, and elevon deflection. Normal and axial free molecule flow coefficient equations as a function of angle-of-attack are presented, along with flight derived rarefied-flow transition bridging formulae. Comparisons are made with data from the Operational Aerodynamic Design Data Book (OADDB), applicable wind-tunnel data, and recent flight data from STS-35 and STS-40. The flight-derived model aerodynamic force coefficient ratio is in good agreement with the wind-tunnel data and predicts the flight measured force coefficient ratios on STS-35 and STS-40. The model is not, however, in good agreement with the OADDB. But, the current OADDB does not predict the flight data force coefficient ratios of either STS-35 or STS-40 as accurately as the flight-derived model. Also, the OADDB differs with the wind-tunnel force coefficient ratio data.
NASA Astrophysics Data System (ADS)
Liao, Yanlong; Hu, Jiaomei; Zhu, Chunxiao; Liu, Ye; Chen, Xu; Chen, Chenqi; Zhong, Chaofan
2016-03-01
Four donor-acceptor (D-A) types of novel conjugated polymeric metal complex dyes (P1-P4) with Zn (II) or Cd (II) complexes as the electron acceptors and benzodithiophene or carbazole derivative as the electron donors were designed and prepared, as promising sensitizers for dye-sensitized solar cells (DSSCs). Diaminomaleonitrile acted as ancillary ligand. The structures of the polymers were confirmed, and their thermal, optical, electrochemical, and photovoltaic properties were investigated. All conjugated polymers exhibit good thermal stability with onset decomposition temperatures with 5% weight loss over 315 °C, broad absorption with the onset of absorption at 588 nm in the visible region, and relatively lower HOMO energy levels from -5.54 to -5.71 eV. The DSSC device based on P2 which containing Cd(II) as coordination metal ion and benzodithiophene derivative as donor exhibited the highest power conversion efficiency of 2.18% under the AM 1.5 G (100 mW cm-2) sunlight illumination with an open-circuit voltage of Voc = 0.68 V, a short current density of Jsc = 4.85 mA cm-2, and a fill factor of FF = 66.2%, respectively. Therefore, these results provide a new way to design dye sensitizers for DSSCs.
NASA Technical Reports Server (NTRS)
Camarda, C. J.; Adelman, H. M.
1984-01-01
The implementation of static and dynamic structural-sensitivity derivative calculations in a general purpose, finite-element computer program denoted the Engineering Analysis Language (EAL) System is described. Derivatives are calculated with respect to structural parameters, specifically, member sectional properties including thicknesses, cross-sectional areas, and moments of inertia. Derivatives are obtained for displacements, stresses, vibration frequencies and mode shapes, and buckling loads and mode shapes. Three methods for calculating derivatives are implemented (analytical, semianalytical, and finite differences), and comparisons of computer time and accuracy are made. Results are presented for four examples: a swept wing, a box beam, a stiffened cylinder with a cutout, and a space radiometer-antenna truss.
NASA Astrophysics Data System (ADS)
Yi, Donghui; Zwally, H. Jay; Cornejo, Helen G.; Barbieri, Kristine A.; DiMarzio, John P.
2011-02-01
Radar-altimeter-measured surface elevations over ice sheets are sensitive to changes in the surface backscatter power that vary temporally and geographically. A correction is needed to extract the real elevation change (dH/dt) from the altimetry- measured ranges using either the backscatter coefficient (σ0) or the Automatic Gain control (AGC) as a measure of the backscatter power. We derive sensitivities between observed changes in elevation and changes in the backscatter power using three methods, which give different sensitivities (short-term, mixed-term, and long-term) and different correlation coefficients. The short-term sensitivities tend to be larger than the mixed term sensitivities and give larger corrections. The resulting corrected H(t) series show significant differences from the uncorrected H(t). In particular, the apparent seasonal cycle in the corrected H(t) is much smoother and smaller in amplitude. Also, in many locations the derived dH/dt from the corrected H(t) is quite different than from the uncorrected H(t).
Zhang, Cai-Rong; Ma, Jin-Gang; Zhe, Jian-Wu; Jin, Neng-Zhi; Shen, Yu-Lin; Wu, You-Zhi; Chen, Yu-Hong; Liu, Zi-Jiang; Chen, Hong-Shan
2015-11-01
The design and development of novel dye sensitizers are effective method to improve the performance of dye-sensitized solar cells (DSSCs) because dye sensitizers have significant influence on photo-to-current conversion efficiency. In the procedure of dye sensitizer design, it is very important to understand how to tune their electronic structures and related properties through the substitution of electronic donors, acceptors, and conjugated bridges in dye sensitizers. Here, the electronic structures and excited-state properties of organic JK dye sensitizers are calculated by using density functional theory (DFT) and time dependent DFT methods. Based upon the calculated results, we investigated the role of different electronic donors, acceptors, and π-conjugated bridges in the modification of electronic structures, absorption properties, as well as the free energy variations for electron injection and dye regeneration. In terms of the analysis of transition configurations and molecular orbitals, the effective chromophores which are favorable for electron injection in DSSCs are addressed. Meanwhile, considering the absorption spectra and free energy variation, the promising electronic donors, π-conjugated bridges, and acceptors are presented to design dye sensitizers. PMID:26116996
Aerodynamic shape optimization using control theory
NASA Technical Reports Server (NTRS)
Reuther, James
1996-01-01
Aerodynamic shape design has long persisted as a difficult scientific challenge due its highly nonlinear flow physics and daunting geometric complexity. However, with the emergence of Computational Fluid Dynamics (CFD) it has become possible to make accurate predictions of flows which are not dominated by viscous effects. It is thus worthwhile to explore the extension of CFD methods for flow analysis to the treatment of aerodynamic shape design. Two new aerodynamic shape design methods are developed which combine existing CFD technology, optimal control theory, and numerical optimization techniques. Flow analysis methods for the potential flow equation and the Euler equations form the basis of the two respective design methods. In each case, optimal control theory is used to derive the adjoint differential equations, the solution of which provides the necessary gradient information to a numerical optimization method much more efficiently then by conventional finite differencing. Each technique uses a quasi-Newton numerical optimization algorithm to drive an aerodynamic objective function toward a minimum. An analytic grid perturbation method is developed to modify body fitted meshes to accommodate shape changes during the design process. Both Hicks-Henne perturbation functions and B-spline control points are explored as suitable design variables. The new methods prove to be computationally efficient and robust, and can be used for practical airfoil design including geometric and aerodynamic constraints. Objective functions are chosen to allow both inverse design to a target pressure distribution and wave drag minimization. Several design cases are presented for each method illustrating its practicality and efficiency. These include non-lifting and lifting airfoils operating at both subsonic and transonic conditions.
NASA Technical Reports Server (NTRS)
Haviland, J. K.; Yoo, Y. S.
1976-01-01
Expressions for calculation of subsonic and supersonic, steady and unsteady aerodynamic forces are derived, using the concept of aerodynamic elements applied to the downwash velocity potential method. Aerodynamic elements can be of arbitrary out of plane polygon shape, although numerical calculations are restricted to rectangular elements, and to the steady state case in the supersonic examples. It is suggested that the use of conforming, in place of rectangular elements, would give better results. Agreement with results for subsonic oscillating T tails is fair, but results do not converge as the number of collocation points is increased. This appears to be due to the form of expression used in the calculations. The methods derived are expected to facilitate automated flutter analysis on the computer. In particular, the aerodynamic element concept is consistent with finite element methods already used for structural analysis. The method is universal for the complete Mach number range, and, finally, the calculations can be arranged so that they do not have to be repeated completely for every reduced frequency.
NASA Astrophysics Data System (ADS)
Sun, Xun; Li, Yafeng; Dou, Jie; Shen, Deli; Wei, Mingdeng
2016-08-01
Metal-organic frameworks, ZIF-8, derived carbon materials are firstly applied as a counter electrode of dye-sensitized solar cells due to their easy fabrication, large specific surface area and high catalytic activities towards the reduction of I3- ions. An efficiency of 7.32% is achieved under the illumination of 1 sun (AM 1.5, 100 mW/cm2), which is comparable to that of the solar cell based on Pt electrode.
Kim, David M.; Zhang, Hairong; Zhou, Haiying; Du, Tommy; Wu, Qian; Mockler, Todd C.; Berezin, Mikhail Y.
2015-01-01
The optical signature of leaves is an important monitoring and predictive parameter for a variety of biotic and abiotic stresses, including drought. Such signatures derived from spectroscopic measurements provide vegetation indices – a quantitative method for assessing plant health. However, the commonly used metrics suffer from low sensitivity. Relatively small changes in water content in moderately stressed plants demand high-contrast imaging to distinguish affected plants. We present a new approach in deriving sensitive indices using hyperspectral imaging in a short-wave infrared range from 800 nm to 1600 nm. Our method, based on high spectral resolution (1.56 nm) instrumentation and image processing algorithms (quantitative histogram analysis), enables us to distinguish a moderate water stress equivalent of 20% relative water content (RWC). The identified image-derived indices 15XX nm/14XX nm (i.e. 1529 nm/1416 nm) were superior to common vegetation indices, such as WBI, MSI, and NDWI, with significantly better sensitivity, enabling early diagnostics of plant health. PMID:26531782
Kim, David M; Zhang, Hairong; Zhou, Haiying; Du, Tommy; Wu, Qian; Mockler, Todd C; Berezin, Mikhail Y
2015-01-01
The optical signature of leaves is an important monitoring and predictive parameter for a variety of biotic and abiotic stresses, including drought. Such signatures derived from spectroscopic measurements provide vegetation indices - a quantitative method for assessing plant health. However, the commonly used metrics suffer from low sensitivity. Relatively small changes in water content in moderately stressed plants demand high-contrast imaging to distinguish affected plants. We present a new approach in deriving sensitive indices using hyperspectral imaging in a short-wave infrared range from 800 nm to 1600 nm. Our method, based on high spectral resolution (1.56 nm) instrumentation and image processing algorithms (quantitative histogram analysis), enables us to distinguish a moderate water stress equivalent of 20% relative water content (RWC). The identified image-derived indices 15XX nm/14XX nm (i.e. 1529 nm/1416 nm) were superior to common vegetation indices, such as WBI, MSI, and NDWI, with significantly better sensitivity, enabling early diagnostics of plant health. PMID:26531782
NASA Astrophysics Data System (ADS)
Kim, David M.; Zhang, Hairong; Zhou, Haiying; Du, Tommy; Wu, Qian; Mockler, Todd C.; Berezin, Mikhail Y.
2015-11-01
The optical signature of leaves is an important monitoring and predictive parameter for a variety of biotic and abiotic stresses, including drought. Such signatures derived from spectroscopic measurements provide vegetation indices - a quantitative method for assessing plant health. However, the commonly used metrics suffer from low sensitivity. Relatively small changes in water content in moderately stressed plants demand high-contrast imaging to distinguish affected plants. We present a new approach in deriving sensitive indices using hyperspectral imaging in a short-wave infrared range from 800 nm to 1600 nm. Our method, based on high spectral resolution (1.56 nm) instrumentation and image processing algorithms (quantitative histogram analysis), enables us to distinguish a moderate water stress equivalent of 20% relative water content (RWC). The identified image-derived indices 15XX nm/14XX nm (i.e. 1529 nm/1416 nm) were superior to common vegetation indices, such as WBI, MSI, and NDWI, with significantly better sensitivity, enabling early diagnostics of plant health.
Aerodynamic control with passively pitching wings
NASA Astrophysics Data System (ADS)
Gravish, Nick; Wood, Robert
Flapping wings may pitch passively under aerodynamic and inertial loads. Such passive pitching is observed in flapping wing insect and robot flight. The effect of passive wing pitch on the control dynamics of flapping wing flight are unexplored. Here we demonstrate in simulation and experiment the critical role wing pitching plays in yaw control of a flapping wing robot. We study yaw torque generation by a flapping wing allowed to passively rotate in the pitch axis through a rotational spring. Yaw torque is generated through alternating fast and slow upstroke and and downstroke. Yaw torque sensitively depends on both the rotational spring force law and spring stiffness, and at a critical spring stiffness a bifurcation in the yaw torque control relationship occurs. Simulation and experiment reveal the dynamics of this bifurcation and demonstrate that anomalous yaw torque from passively pitching wings is the result of aerodynamic and inertial coupling between the pitching and stroke-plane dynamics.
Freight Wing Trailer Aerodynamics
Graham, Sean; Bigatel, Patrick
2004-10-17
Freight Wing Incorporated utilized the opportunity presented by this DOE category one Inventions and Innovations grant to successfully research, develop, test, patent, market, and sell innovative fuel and emissions saving aerodynamic attachments for the trucking industry. A great deal of past scientific research has demonstrated that streamlining box shaped semi-trailers can significantly reduce a truck's fuel consumption. However, significant design challenges have prevented past concepts from meeting industry needs. Market research early in this project revealed the demands of truck fleet operators regarding aerodynamic attachments. Products must not only save fuel, but cannot interfere with the operation of the truck, require significant maintenance, add significant weight, and must be extremely durable. Furthermore, SAE/TMC J1321 tests performed by a respected independent laboratory are necessary for large fleets to even consider purchase. Freight Wing used this information to create a system of three practical aerodynamic attachments for the front, rear and undercarriage of standard semi trailers. SAE/TMC J1321 Type II tests preformed by the Transportation Research Center (TRC) demonstrated a 7% improvement to fuel economy with all three products. If Freight Wing is successful in its continued efforts to gain market penetration, the energy and environmental savings would be considerable. Each truck outfitted saves approximately 1,100 gallons of fuel every 100,000 miles, which prevents over 12 tons of CO2 from entering the atmosphere. If all applicable trailers used the technology, the country could save approximately 1.8 billion gallons of diesel fuel, 18 million tons of emissions and 3.6 billion dollars annually.
Numerical Aerodynamic Simulation (NAS)
NASA Technical Reports Server (NTRS)
Peterson, V. L.; Ballhaus, W. F., Jr.; Bailey, F. R.
1983-01-01
The history of the Numerical Aerodynamic Simulation Program, which is designed to provide a leading-edge capability to computational aerodynamicists, is traced back to its origin in 1975. Factors motivating its development and examples of solutions to successively refined forms of the governing equations are presented. The NAS Processing System Network and each of its eight subsystems are described in terms of function and initial performance goals. A proposed usage allocation policy is discussed and some initial problems being readied for solution on the NAS system are identified.
Ren, Xue-Feng; Kang, Guo-Jun; He, Qiong-Qiong
2016-01-01
A new series of triphenylamine-based indoline dye sensitizers were molecularly designed and investigated for their potential use in dye-sensitized solar cells (DSSCs). Theoretical calculations revealed that modifying donor part of D149 by triphenylamine significantly altered the electronic structures, MO energies, and intramolecular charge transfer (ICT) absorption band. Key parameters associated with the light-harvesting efficiency at a given wavelength LHE(λ), the driving force ΔG inject, and the open-circuit photovoltage V oc were characterized. More importantly, these designed (dimeric) dye sensitizers were found to have similar broad absorption spectra to their corresponding monomers, indicating that modifying the donor part with triphenylamine may stop unfavorable dye aggregation. Further analyses of the dye-(TiO2)9 cluster interaction confirmed that there was strong electronic coupling at the interface. These results are expected to provide useful guidance in the molecular design of new highly efficient metal-free organic dyes. PMID:26659403
NASA Technical Reports Server (NTRS)
Roskam, J.; Hamler, F. R.; Reynolds, D.
1972-01-01
The procedures used to establish the mass matrices characteristics for the fighter type wings studied are given. A description of the procedure used to find the mass associated with a specific aerodynamic panel is presented and some examples of the application of the procedure are included.
NASA Technical Reports Server (NTRS)
Walter, Bernadette P.; Heimann, Martin
1999-01-01
Methane emissions from natural wetlands constitutes the largest methane source at present and depends highly on the climate. In order to investigate the response of methane emissions from natural wetlands to climate variations, a 1-dimensional process-based climate-sensitive model to derive methane emissions from natural wetlands is developed. In the model the processes leading to methane emission are simulated within a 1-dimensional soil column and the three different transport mechanisms diffusion, plant-mediated transport and ebullition are modeled explicitly. The model forcing consists of daily values of soil temperature, water table and Net Primary Productivity, and at permafrost sites the thaw depth is included. The methane model is tested using observational data obtained at 5 wetland sites located in North America, Europe and Central America, representing a large variety of environmental conditions. It can be shown that in most cases seasonal variations in methane emissions can be explained by the combined effect of changes in soil temperature and the position of the water table. Our results also show that a process-based approach is needed, because there is no simple relationship between these controlling factors and methane emissions that applies to a variety of wetland sites. The sensitivity of the model to the choice of key model parameters is tested and further sensitivity tests are performed to demonstrate how methane emissions from wetlands respond to climate variations.
Larras, Floriane; Montuelle, Bernard; Rimet, Frédéric; Chèvre, Nathalie; Bouchez, Agnès
2014-08-01
Seasonal changes in the structure and composition of a benthic microalgal community may lead to different responses to herbicide contamination during different seasons. Consequently, the thresholds derived from risk assessment tools such as species sensitivity distributions (SSDs) must allow for these changes. We built a single-substance SSD for each of four herbicides (atrazine, terbutryn, diuron and isoproturon), which was specific to the sensitivity of the benthic diatoms found in Lake Geneva, in order to derive protective thresholds for a mixture of these four herbicides using the concentration addition model. We then investigated (1) the structural parameters of a Lake Geneva benthic microalgal community during two contrasting seasons (summer 2012 and winter 2013), (2) the response of these communities to a herbicide mixture, and (3) the protective levels of the thresholds derived. The winter community was characterized by having greater biomass, diatom species richness, and diversity metrics, and lower non-diatom species richness than the summer community. The differences in the diatom communities composition in these seasons appeared to be primarily driven by the environmental nitrate concentrations and the temperature. Moreover, the species in the winter community were more resistant to herbicides than those found in the summer community. Consequently, the protective threshold for this herbicide mixture obtained in this study was in fact protective for the winter community, but not for the summer community based on their structural parameters. Thus, the protective level against herbicides of the threshold for the benthic microalgal community should take into account changes in the environmental physico-chemical conditions that strongly influence the structure and composition of the community. The fact that the succession of species over time (i.e., over the seasons) is difficult to predict introduces uncertainties into the estimation of protective
Sensitivity Analysis in Engineering
NASA Technical Reports Server (NTRS)
Adelman, Howard M. (Compiler); Haftka, Raphael T. (Compiler)
1987-01-01
The symposium proceedings presented focused primarily on sensitivity analysis of structural response. However, the first session, entitled, General and Multidisciplinary Sensitivity, focused on areas such as physics, chemistry, controls, and aerodynamics. The other four sessions were concerned with the sensitivity of structural systems modeled by finite elements. Session 2 dealt with Static Sensitivity Analysis and Applications; Session 3 with Eigenproblem Sensitivity Methods; Session 4 with Transient Sensitivity Analysis; and Session 5 with Shape Sensitivity Analysis.
NASA Astrophysics Data System (ADS)
Mehta, R. D.
Research data on the aerodynamic behavior of baseballs and cricket and golf balls are summarized. Cricket balls and baseballs are roughly the same size and mass but have different stitch patterns. Both are thrown to follow paths that avoid a batter's swing, paths that can curve if aerodynamic forces on the balls' surfaces are asymmetric. Smoke tracer wind tunnel tests and pressure taps have revealed that the unbalanced side forces are induced by tripping the boundary layer on the seam side and producing turbulence. More particularly, the greater pressures are perpendicular to the seam plane and only appear when the balls travel at velocities high enough so that the roughness length matches the seam heigh. The side forces, once tripped, will increase with spin velocity up to a cut-off point. The enhanced lift coefficient is produced by the Magnus effect. The more complex stitching on a baseball permits greater variations in the flight path curve and, in the case of a knuckleball, the unsteady flow effects. For golf balls, the dimples trip the boundary layer and the high spin rate produces a lift coefficient maximum of 0.5, compared to a baseball's maximum of 0.3. Thus, a golf ball travels far enough for gravitational forces to become important.
NASA Technical Reports Server (NTRS)
Mehta, R. D.
1985-01-01
Research data on the aerodynamic behavior of baseballs and cricket and golf balls are summarized. Cricket balls and baseballs are roughly the same size and mass but have different stitch patterns. Both are thrown to follow paths that avoid a batter's swing, paths that can curve if aerodynamic forces on the balls' surfaces are asymmetric. Smoke tracer wind tunnel tests and pressure taps have revealed that the unbalanced side forces are induced by tripping the boundary layer on the seam side and producing turbulence. More particularly, the greater pressures are perpendicular to the seam plane and only appear when the balls travel at velocities high enough so that the roughness length matches the seam heigh. The side forces, once tripped, will increase with spin velocity up to a cut-off point. The enhanced lift coefficient is produced by the Magnus effect. The more complex stitching on a baseball permits greater variations in the flight path curve and, in the case of a knuckleball, the unsteady flow effects. For golf balls, the dimples trip the boundary layer and the high spin rate produces a lift coefficient maximum of 0.5, compared to a baseball's maximum of 0.3. Thus, a golf ball travels far enough for gravitational forces to become important.
NASA Technical Reports Server (NTRS)
Hooks, I.; Homan, D.; Romere, P. O.
1985-01-01
The approach and landing test (ALT) of the Space Shuttle Orbiter presented a number of unique challenges in the area of aerodynamics. The purpose of the ALT program was both to confirm the use of the Boeing 747 as a transport vehicle for ferrying the Orbiter across the country and to demonstrate the flight characteristics of the Orbiter in its approach and landing phase. Concerns for structural fatigue and performance dictated a tailcone be attached to the Orbiter for ferry and for the initial landing tests. The Orbiter with a tailcone attached presented additional challenges to the normal aft sting concept of wind tunnel testing. The landing tests required that the Orbiter be separated from the 747 at approximately 20,000 feet using aerodynamic forces to fly the vehicles apart. The concept required a complex test program to determine the relative effects of the two vehicles on each other. Also of concern, and tested, was the vortex wake created by the 747 and the means for the Orbiter to avoid it following separation.
On Wings: Aerodynamics of Eagles.
ERIC Educational Resources Information Center
Millson, David
2000-01-01
The Aerodynamics Wing Curriculum is a high school program that combines basic physics, aerodynamics, pre-engineering, 3D visualization, computer-assisted drafting, computer-assisted manufacturing, production, reengineering, and success in a 15-hour, 3-week classroom module. (JOW)
Aerodynamics of a Party Balloon
ERIC Educational Resources Information Center
Cross, Rod
2007-01-01
It is well-known that a party balloon can be made to fly erratically across a room, but it can also be used for quantitative measurements of other aspects of aerodynamics. Since a balloon is light and has a large surface area, even relatively weak aerodynamic forces can be readily demonstrated or measured in the classroom. Accurate measurements…
Pellett, Sabine; Du, Zhong-wei; Pier, Christina L; Tepp, William H; Zhang, Su-chun; Johnson, Eric A
2011-01-01
Botulinum neurotoxins (BoNTs), the most poisonous protein toxins known, represent a serious bioterrorism threat but are also used as a unique and important bio-pharmaceutical to treat an increasing myriad of neurological disorders. The only currently accepted detection method by the United States Food and Drug Administration for biological activity of BoNTs and for potency determination of pharmaceutical preparations is the mouse bioassay (MBA). Recent advances have indicated that cell-based assays using primary neuronal cells can provide an equally sensitive and robust detection platform as the MBA to reliably and quantitatively detect biologically active BoNTs. This study reports for the first time a BoNT detection assay using mouse embryonic stem cells to produce a neuronal cell culture. The data presented indicate that this assay can reliably detect BoNT/A with a similar sensitivity as the MBA. PMID:21130748
Wegner, Florian; Kraft, Robert; Busse, Kathy; Härtig, Wolfgang; Ahrens, Jörg; Leffler, Andreas; Dengler, Reinhard; Schwarz, Johannes
2012-01-01
Background Human fetal midbrain-derived neural progenitor cells (NPCs) may deliver a tissue source for drug screening and regenerative cell therapy to treat Parkinson’s disease. While glutamate and GABAA receptors play an important role in neurogenesis, the involvement of glycine receptors during human neurogenesis and dopaminergic differentiation as well as their molecular and functional characteristics in NPCs are largely unknown. Methodology/Principal Findings Here we investigated NPCs in respect to their glycine receptor function and subunit expression using electrophysiology, calcium imaging, immunocytochemistry, and quantitative real-time PCR. Whole-cell recordings demonstrate the ability of NPCs to express functional strychnine-sensitive glycine receptors after differentiation for 3 weeks in vitro. Pharmacological and molecular analyses indicate a predominance of glycine receptor heteromers containing α2β subunits. Intracellular calcium measurements of differentiated NPCs suggest that glycine evokes depolarisations mediated by strychnine-sensitive glycine receptors and not by D-serine-sensitive excitatory glycine receptors. Culturing NPCs with additional glycine, the glycine-receptor antagonist strychnine, or the Na+-K+-Cl− co-transporter 1 (NKCC1)-inhibitor bumetanide did not significantly influence cell proliferation and differentiation in vitro. Conclusions/Significance These data indicate that NPCs derived from human fetal midbrain tissue acquire essential glycine receptor properties during neuronal maturation. However, glycine receptors seem to have a limited functional impact on neurogenesis and dopaminergic differentiation of NPCs in vitro. PMID:22606311
Momen-Heravi, Fatemeh; Bala, Shashi; Kodys, Karen; Szabo, Gyongyi
2015-01-01
Hepatocyte damage and inflammation in monocytes/macrophages are central to the pathogenesis of alcoholic hepatitis (AH). MicroRNAs (miRNAs) regulate all of these processes. MiRNA-122 is abundantly expressed in hepatocytes while monocytes/macrophages have low levels. The role of exosomes in AH and possible cross talk between hepatocyte-derived exosomes and immune cells is not explored yet. Here, we show that the number of exosomes significantly increases in the sera of healthy individuals after alcohol binge drinking and in mice after binge or chronic alcohol consumption. Exosomes isolated from sera after alcohol consumption or from in vitro ethanol-treated hepatocytes contained miRNA-122. Exosomes derived from ethanol-treated Huh7.5 cells were taken up by the recipients THP1 monocytes and horizontally transferred a mature form of liver-specific miRNA-122. In vivo, liver mononuclear cells and Kupffer cells from alcohol-fed mice had increased miRNA-122 levels. In monocytes, miRNA-122 transferred via exosomes inhibited the HO-1 pathway and sensitized to LPS stimulation and increased levels of pro-inflammatory cytokines. Finally, inflammatory effects of exosomes from ethanol-treated hepatocytes were prevented by using RNA interference via exosome-mediated delivery of a miRNA-122 inhibitor. These results demonstrate that first, exosomes mediate communication between hepatocytes and monocytes/macrophages and second, hepatocyte-derived miRNA-122 can reprogram monocytes inducing sensitization to LPS. PMID:25973575
Momen-Heravi, Fatemeh; Bala, Shashi; Kodys, Karen; Szabo, Gyongyi
2015-01-01
Hepatocyte damage and inflammation in monocytes/macrophages are central to the pathogenesis of alcoholic hepatitis (AH). MicroRNAs (miRNAs) regulate all of these processes. MiRNA-122 is abundantly expressed in hepatocytes while monocytes/macrophages have low levels. The role of exosomes in AH and possible cross talk between hepatocyte-derived exosomes and immune cells is not explored yet. Here, we show that the number of exosomes significantly increases in the sera of healthy individuals after alcohol binge drinking and in mice after binge or chronic alcohol consumption. Exosomes isolated from sera after alcohol consumption or from in vitro ethanol-treated hepatocytes contained miRNA-122. Exosomes derived from ethanol-treated Huh7.5 cells were taken up by the recipients THP1 monocytes and horizontally transferred a mature form of liver-specific miRNA-122. In vivo, liver mononuclear cells and Kupffer cells from alcohol-fed mice had increased miRNA-122 levels. In monocytes, miRNA-122 transferred via exosomes inhibited the HO-1 pathway and sensitized to LPS stimulation and increased levels of pro-inflammatory cytokines. Finally, inflammatory effects of exosomes from ethanol-treated hepatocytes were prevented by using RNA interference via exosome-mediated delivery of a miRNA-122 inhibitor. These results demonstrate that first, exosomes mediate communication between hepatocytes and monocytes/macrophages and second, hepatocyte-derived miRNA-122 can reprogram monocytes inducing sensitization to LPS. PMID:25973575
NASA Technical Reports Server (NTRS)
Gregg, Watson; Casey, Nancy
2010-01-01
Ocean biogeochemistry models are typically forced by atmospheric and oceanic data derived from reanalysis products. For the NASA Ocean Biogeochemistry Model (NOBM) such reanalysis forcing fields include: surface wind stress, sea surface temperature, ice distributions, shortwave radiation, surface wind speeds and surface atmospheric pressure. Additionally, proper computation of ocean irradiance requires reanalysis products of relative humidity and precipitable water (in addition to aerosol and cloud information which is derived from satellite data). The question posed here is, does the choice of reanalysis products make a difference in the representation of ocean biology and biogeochemistry? NOBM was forced by NCEP and MERRA reanalysis products for the period 2002-2009. We find that in 2009 global distributions and abundances of biological variables (total chlorophyll and nutrients) and carbon (dissolved inorganic and organic carbon and surface pCO2) were similar between the two different forcing fields. Global statistical comparisons with satellite and in situ data also showed negligible differences.
NASA Technical Reports Server (NTRS)
Ibrahim, A. H.; Tiwari, S. N.; Smith, R. E.
1997-01-01
Variational methods (VM) sensitivity analysis employed to derive the costate (adjoint) equations, the transversality conditions, and the functional sensitivity derivatives. In the derivation of the sensitivity equations, the variational methods use the generalized calculus of variations, in which the variable boundary is considered as the design function. The converged solution of the state equations together with the converged solution of the costate equations are integrated along the domain boundary to uniquely determine the functional sensitivity derivatives with respect to the design function. The application of the variational methods to aerodynamic shape optimization problems is demonstrated for internal flow problems at supersonic Mach number range. The study shows, that while maintaining the accuracy of the functional sensitivity derivatives within the reasonable range for engineering prediction purposes, the variational methods show a substantial gain in computational efficiency, i.e., computer time and memory, when compared with the finite difference sensitivity analysis.
NASA Astrophysics Data System (ADS)
Wang, Xiao-Feng; Xiang, Junfeng; Wang, Peng; Koyama, Yasushi; Yanagida, Shozo; Wada, Yuji; Hamada, Kazunori; Sasaki, Shin-ichi; Tamiaki, Hitoshi
2005-06-01
Titania-based Grätzel-type solar cells were fabricated by the use of a chlorophyll a derivative (methyl 3-carboxy-3-devinyl-pyropheophorobide a) as the dye sensitizer. A 10% each of carotenoids, including neurosporene, spheroidene, lycopene, anhydrorhodovibrin and spirilloxanthin with numbers of conjugated double bonds, n = 9-13, was added as a conjugated spacer in order to neutralize the dye radical cation and to block the reverse electron transfer. The short-circuit current density ( Jsc) and the solar energy-to-electricity conversion efficiency ( η) systematically increased, with increasing n, from the values of 10.1 mA cm -2 and 3.1% (with no carotenoid) up to 11.5 mA cm -2 and 4.0% (with spirilloxanthin, n = 13), i.e., an enhancement of ≈30%.
NASA Technical Reports Server (NTRS)
Nissim, E.
1977-01-01
Control laws are derived, by using realizable transfer functions, which permit relaxation of the stability requirements of the aerodynamic energy concept. The resulting aerodynamic eigenvalues indicate that both the trailing edge and the leading edge-trailing edge control systems can be made more effective. These control laws permit the introduction of aerodynamic damping and stiffness terms in accordance with the requirements of any specific system. Flutter suppression and gust alleviation problems can now be treated by either a trailing edge control system or by a leading edge-trailing edge control system by using the aerodynamic energy concept. Results are applicable to a wide class of aircraft operating at subsonic Mach numbers.
Landi, Silvio; Tseng, Men C.; Held, Hans R.
1974-01-01
Tuberculin purified protein derivative labeled with 14C ([14C]PPD) with a biological potency equivalent to the International Standard for tuberculin PPD was used to study the retention of tuberculin PPD in the skin of sensitized and nonsensitized animals. We found that [14C]PPD was almost entirely cleared from the skin test site during the first 18 to 24 h after injection and that when approximately 5% of the initial concentration of [14C]PPD was present in the skin test site, the size of the tuberculin skin reaction in sensitized guinea pigs was at its maximum. Furthermore, the addition of 5 or 50 μg of Tween 80 per ml to a solution of PPD did not change either the rate of clearance of PPD from the skin test sites of sensitized guinea pigs or the size of the tuberculin skin reactions. There was no difference in the rate of clearance of [14C]PPD from the skin test sites between sensitized and nonsensitized guinea pigs and between guinea pigs of different age. However, there was a significant difference in the rate of clearance of [14C]PPD between the guinea pig and the mouse. Finally, the percentage of [14C]PPD retained in the site of injection at 24 h was in the neighborhood of 5% of the initial concentration of the solution of PPD injected. The significance of these phenomena is discussed. Images PMID:4208638
Reciprocity relations in aerodynamics
NASA Technical Reports Server (NTRS)
Heaslet, Max A; Spreiter, John R
1953-01-01
Reverse flow theorems in aerodynamics are shown to be based on the same general concepts involved in many reciprocity theorems in the physical sciences. Reciprocal theorems for both steady and unsteady motion are found as a logical consequence of this approach. No restrictions on wing plan form or flight Mach number are made beyond those required in linearized compressible-flow analysis. A number of examples are listed, including general integral theorems for lifting, rolling, and pitching wings and for wings in nonuniform downwash fields. Correspondence is also established between the buildup of circulation with time of a wing starting impulsively from rest and the buildup of lift of the same wing moving in the reverse direction into a sharp-edged gust.
New aircraft configurations handling qualities studies based on the aerodynamic invariant concept
NASA Astrophysics Data System (ADS)
Bazile, J.
2013-12-01
This paper proposes an innovative approach to go deeper in the Handling Qualities knowledge for New Aircraft Configurations based on the Aerodynamic Invariant Concept. By manipulating the Doublet Lattice Method for aerodynamic derivatives computation, an Aerodynamic Invariant can be highlighted. It contributes to many aircraft dynamics parameters and can be considered as "key driver" of the longitudinal aircraft dynamics. The aim of this new approach is to study the impact of this aerodynamic invariant on aircraft Handling Qualities and to ask the question: "Could this aerodynamic invariant be used in parallel with Performance in the conceptual design phase to "seek" New Aircraft configurations capable of achieving further Handling Qualities improvement with Performance benefits?" The enclosed results highlight that the aerodynamic invariant could allow to improve and to optimize the aircraft Handling Qualities by relaxing the aircraft dynamics stability.
Physico-chemical studies of fused phenanthrimidazole derivative as sensitive NLO material
NASA Astrophysics Data System (ADS)
Jayabharathi, Jayaraman; Thanikachalam, Venugopal; Sathishkumar, Ramalingam; Jayamoorthy, Karunamoorthy
2013-01-01
Heterocyclic phenanthrimidazole derivative, 2-(4-fluorophenyl)-1-p-tolyl-1H-imidazo[4,5-f] [1,10] phenanthroline (FPTIP) has been synthesized and characterised by NMR, mass and CHN analysis. The FPTIP was evaluated concerning their solvatochromic properties and molecular optical nonlinearities. Their electric dipole moment (μ), polarizability (α) and hyperpolarizability (β) have been calculated theoretically and the results indicate that the extension of the π-framework of the ligands has an effect on the NLO properties. The energies of the HOMO and LUMO levels and the molecular electrostatic potential (MEP) energy surface studies have exploited the existence of intramolecular charge transfer (ICT) within the molecule.
Novel Ru (II) complex with TPA derivatives as a donor for dye-sensitized solar cells
NASA Astrophysics Data System (ADS)
Kwon, Dong Yuel; Chang, Dong Min; Kim, Young Sik
2015-01-01
Novel heteroleptic ruthenium(II) complex [Ru(CF3-ppyd-TPA)(tctpy)]+ (ppyd = 2-phenyl-6-(pyridin-2-yl)pyridine, TPA = triphenylamine, and tctpy = 4,4',4″-tricarboxy-2,2':6',2″-terpyridine) was designed and investigated to increase its molar absorptivity compared to [Ru(ppd)(tctpy)]+ (ppd = 2-(3-(pyridin-2-yl)phenyl)pyridine). Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations were performed to gain insight into the factors responsible for the photovoltaic properties of a dye sensitizer. [Ru(CF3-ppyd-TPA)(tctpy)]+ showed a broad absorption spectrum and enhanced the molar extinction coefficient. Significant improvements to light absorption were exhibited by enhancing the metal-to-ligand charge transfer (MLCT) characteristics through the addition of the electron-withdrawing group-CF3 para to the organometallic bond and by increasing the transition dipole moment through the addition of TPA as an electron-donating group compared to the [Ru(ppd)(tctpy)]+. This study suggests that a ruthenium-based dye sensitizer would show improved photovoltaic performance in conversion efficiency for DSSCs by adding electron-donating and electron-withdrawing groups.
Skylon Aerodynamics and SABRE Plumes
NASA Technical Reports Server (NTRS)
Mehta, Unmeel; Afosmis, Michael; Bowles, Jeffrey; Pandya, Shishir
2015-01-01
An independent partial assessment is provided of the technical viability of the Skylon aerospace plane concept, developed by Reaction Engines Limited (REL). The objectives are to verify REL's engineering estimates of airframe aerodynamics during powered flight and to assess the impact of Synergetic Air-Breathing Rocket Engine (SABRE) plumes on the aft fuselage. Pressure lift and drag coefficients derived from simulations conducted with Euler equations for unpowered flight compare very well with those REL computed with engineering methods. The REL coefficients for powered flight are increasingly less acceptable as the freestream Mach number is increased beyond 8.5, because the engineering estimates did not account for the increasing favorable (in terms of drag and lift coefficients) effect of underexpanded rocket engine plumes on the aft fuselage. At Mach numbers greater than 8.5, the thermal environment around the aft fuselage is a known unknown-a potential design and/or performance risk issue. The adverse effects of shock waves on the aft fuselage and plumeinduced flow separation are other potential risks. The development of an operational reusable launcher from the Skylon concept necessitates the judicious use of a combination of engineering methods, advanced methods based on required physics or analytical fidelity, test data, and independent assessments.
The aerodynamics of supersonic parachutes
Peterson, C.W.
1987-06-01
A discussion of the aerodynamics and performance of parachutes flying at supersonic speeds is the focus of this paper. Typical performance requirements for supersonic parachute systems are presented, followed by a review of the literature on supersonic parachute configurations and their drag characteristics. Data from a recent supersonic wind tunnel test series is summarized. The value and limitations of supersonic wind tunnel data on hemisflo and 20-degree conical ribbon parachutes behind several forebody shapes and diameters are discussed. Test techniques were derived which avoided many of the opportunities to obtain erroneous supersonic parachute drag data in wind tunnels. Preliminary correlations of supersonic parachute drag with Mach number, forebody shape and diameter, canopy porosity, inflated canopy diameter and stability are presented. Supersonic parachute design considerations are discussed and applied to a M = 2 parachute system designed and tested at Sandia. It is shown that the performance of parachutes in supersonic flows is a strong function of parachute design parameters and their interactions with the payload wake.
Cho, Min; Lee, Jaesang; Mackeyev, Yuri; Wilson, Lon J; Alvarez, Pedro J J; Hughes, Joseph B; Kim, Jae-Hong
2010-09-01
Recently, we reported the successful synthesis of various hexakis C60 derivatives (i.e., C60 with six functional groups containing NH3+-, CO2H-, or OH-terminals) with enhanced stability in water for aqueous phase application (Lee et al., Environ. Sci. Technol. 2009, 43, pp 6604-6610). Among these newly synthesized C60 derivatives, the cationic hexakis C60 derivative with amine functionality, C60(CR2)6 (R=CO2(CH2)2NH3+CF3CO2-), was found to exhibit remarkable efficiency to inactivate Escherichia coli and MS-2 bacteriophage under UVA irradiation. Herein, we report that this amine-functionalized C60 derivative is also photoactive in response to visible light from both commercial fluorescence lamps and sunlight. Efficient production of 1O2, facile reaction of 1O2 with proteins in MS-2 phage capsid and electrostatic attraction between positively charged C60 derivative and negatively charged MS-2 phage collectively contributed to high efficiency of MS-2 phage inactivation in this photocatalytic disinfection system. The rate of 1O2 production was evaluated using a probe compound, furfuryl alcohol, and 1O2 CT (the product of 1O2 concentration and exposure time) required to achieve a target level of virus inactivation was quantitatively analyzed. The unique visible-light sensitized virucidal property makes this C60 derivative highly desirable for the development of sustainable disinfection strategies that do not require continuous chemical addition nor an external energy source other than ambient light. PMID:20687548
NASA Technical Reports Server (NTRS)
Harrison, B. A.; Richard, M.
1979-01-01
The information necessary for execution of the digital computer program L216 on the CDC 6600 is described. L216 characteristics are based on the doublet lattice method. Arbitrary aerodynamic configurations may be represented with combinations of nonplanar lifting surfaces composed of finite constant pressure panel elements, and axially summetric slender bodies composed of constant pressure line elements. Program input consists of configuration geometry, aerodynamic parameters, and modal data; output includes element geometry, pressure difference distributions, integrated aerodynamic coefficients, stability derivatives, generalized aerodynamic forces, and aerodynamic influence coefficient matrices. Optionally, modal data may be input on magnetic field (tape or disk), and certain geometric and aerodynamic output may be saved for subsequent use.
Unsteady aerodynamics of conventional and supercritical airfoils
NASA Technical Reports Server (NTRS)
Davis, S. S.; Malcolm, G. N.
1980-01-01
The unsteady aerodynamics of a conventional and a supercritical airfoil are compared by examining measured chordwise unsteady pressure time-histories from four selected flow conditions. Although an oscillating supercritical airfoil excites more harmonics, the strength of the airfoil's shock wave is the more important parameter governing the complexity of the unsteady flow. Whether they are conventional or supercritical, airfoils that support weak shock waves induce unsteady loads that are qualitatively predictable with classical theories; flows with strong shock waves are sensitive to details of the shock-wave and boundary-layer interaction and cannot be adequately predicted.
Tang, Lijun; He, Ping; Zhong, Keli; Hou, Shuhua; Bian, Yanjiang
2016-12-01
A new reactive probe, 1-(benzo[d]thiazol-2-yl)naphthalen-2-yl-picolinate (BTNP), was designed and synthesized. BTNP acts as a highly selective probe to Cu(2+) in DMSO/H2O (7/3, v/v, Tris-HCl 10mM, pH=7.4) solution based on Cu(2+) catalyzed hydrolysis of the picolinate ester moiety in BTNP, which leads to the formation of an ESIPT active product with dual wavelength emission enhancement. The probe also possesses the advantages of simple synthesis, rapid response and high sensitivity. The pseudo-first-order reaction rate constant was calculated to be 0.205min(-1). Moreover, application of BTNP to Cu(2+) detection in living cells and real water samples was also explored. PMID:27391231
Sensitivity of the Derived B(E2) Transition Strength to Nuclear Structure Models
NASA Astrophysics Data System (ADS)
Weppner, Stephen
2005-04-01
Identifying the structure of exotic nuclei via scattering observables is an interesting theoretical challenge. Starting with a microscopic optical model, which has a clear delineation between structure and the interaction introduced at the onset, we have a natural tool to examine the role of the structure in the calculation. In the past this model was used to ascertain the sensitivities of the elastic scattering observables to the structure of the nucleus, with the differences between models being minimal at intermediate scattering energies. We now examine the role of the nucleur structure model in the calculation of an inelastic proton-nucleus scattering observable: the differential cross-section for the first 0+->2+ transition of the nucleus. We will study how this observable and the related B(E2) matrix element and deformation parameter are affected by the use of a variety of different structure inputs used in the calculation.
NASA Astrophysics Data System (ADS)
Tang, Lijun; He, Ping; Zhong, Keli; Hou, Shuhua; Bian, Yanjiang
2016-12-01
A new reactive probe, 1-(benzo[d]thiazol-2-yl)naphthalen-2-yl-picolinate (BTNP), was designed and synthesized. BTNP acts as a highly selective probe to Cu2 + in DMSO/H2O (7/3, v/v, Tris-HCl 10 mM, pH = 7.4) solution based on Cu2 + catalyzed hydrolysis of the picolinate ester moiety in BTNP, which leads to the formation of an ESIPT active product with dual wavelength emission enhancement. The probe also possesses the advantages of simple synthesis, rapid response and high sensitivity. The pseudo-first-order reaction rate constant was calculated to be 0.205 min- 1. Moreover, application of BTNP to Cu2 + detection in living cells and real water samples was also explored.
Aerodynamics of High-Speed Trains
NASA Astrophysics Data System (ADS)
Schetz, Joseph A.
This review highlights the differences between the aerodynamics of high-speed trains and other types of transportation vehicles. The emphasis is on modern, high-speed trains, including magnetic levitation (Maglev) trains. Some of the key differences are derived from the fact that trains operate near the ground or a track, have much greater length-to-diameter ratios than other vehicles, pass close to each other and to trackside structures, are more subject to crosswinds, and operate in tunnels with entry and exit events. The coverage includes experimental techniques and results and analytical and numerical methods, concentrating on the most recent information available.
NASA Astrophysics Data System (ADS)
Deppenmeier, Anna-Lena; Hazeleger, Wilco; Haarsma, Rein; Prodhomme, Chloé; Exarchou, Eleftheria; Doblas-Reyes, Francisco J.
2016-04-01
State-of-the-art coupled general circulation models (CGCMs) still fail to simulate the mean state and variability of the tropical Atlantic (TA) climate correctly. We investigate the importance of air-sea interaction at different regions in the TA by means of performing partially coupled sensitivity experiments with the state-of-the-art CGCM EC-Earth3.1. All simulations are intialised from the observed climate state. By studying the initial drift in sensitivity experiments we obtain insight into the tropical dynamics and sources of model bias. We test the influence of realistic wind stress forcing over different regions of the TA on the development of SST as well as other oceanic biases. A series of hindcasts fully initialised in May and run until the end of August are performed with prescribed ERA-Interim zonal and meridional wind stresses over three different regions: firstly, we force the entire TA from 15N - 30S. Secondly, we force the equatorial band only between 5N - 5S, and finally we force the coastal area of the Angola Benguela upwelling region between 0W and the coast and between 5S - 30N. Our setup only affects the oceanic forcing and leaves the atmosphere free to adapt, such that we can identify the air-sea interaction processes in the different regions and their effect on the SST bias in the fully coupled system. The differences between forcing the entire TA and the equatorial region only are very small, which hints to the great importance of the relatively narrow equatorial region. The coastal upwelling area does not strongly affect the equatorial region in our model. We identify the equatorial band as most susceptible to errors in the wind stress forcing and, due to the strong atmosphere-ocean coupling, as source of the main biases in our model. The partially coupled experiments with initialised seasonal hindcasts appear to be a powerful tool to identify the sources of model biases and to identify relevant air-sea interaction processes in the TA.
Dave, Shruti D.; Vanikar, Aruna V.; Trivedi, Hargovind L
2012-01-01
Background: Diabetics are incapable of producing insulin/have autoimmune mechanisms making it ineffective to control glucose secretion. We present a prospective study of glucose-sensitive insulin-secreting mesenchymal stem cells (IS-MSC) generated from human adipose tissue (h-AD) sans xenogenic material. Materials and Methods: Ten grams h-AD from donor anterior abdominal wall was collected in proliferation medium composed of α-Minimum Essential Media (α-MEM), albumin, fibroblast-growth factor and antibiotics, minced, incubated in collagenase-I at 37°C with shaker and centrifuged. Supernatant and pellets were separately cultured in proliferation medium on cell+ plates at 37°C with 5% CO2 for 10 days. Cells were harvested by trypsinization, checked for viability, sterility, counts, flow-cytometry (CD45-/90+/73+), and differentiated into insulin-expressing cells using medium composed of DMEM, gene expressing up-regulators and antibiotics for 3 days. They were studied for transcriptional factors Pax-6, Isl-1, pdx-1 (immunofluorescence). C-peptide and insulin were measured by chemiluminescence. In vitro glucose sensitivity assay was carried out by measuring levels of insulin and C-peptide secretion in absence of glucose followed by 2 hours incubation after glucose addition. Results: Mean IS-AD-MSC quantum was 3.21 ml, cell count, 1.5 ×103 cells/μl), CD45-/90+/73+ cells were 44.37% /25.52%. All of them showed presence of pax-6, pdx-1, and Isl-1. Mean C-Peptide and insulin levels were 0.36 ng/ml and 234 μU/ml, respectively, pre-glucose and 0.87 ng/ml and 618.3 μU/ml post-glucose additions. The mean rise in secretion levels was 2.42 and 2.65 fold, respectively. Conclusion: Insulin-secreting h-AD-MSC can be generated safely and effectively showing in vitro glucose responsive alteration in insulin and C-peptide secretion levels. PMID:22701849
Computational aerodynamics and artificial intelligence
NASA Technical Reports Server (NTRS)
Kutler, P.; Mehta, U. B.
1984-01-01
Some aspects of artificial intelligence are considered and questions are speculated on, including how knowledge-based systems can accelerate the process of acquiring new knowledge in aerodynamics, how computational fluid dynamics may use 'expert' systems and how expert systems may speed the design and development process. The anatomy of an idealized expert system called AERODYNAMICIST is discussed. Resource requirements are examined for using artificial intelligence in computational fluid dynamics and aerodynamics. Considering two of the essentials of computational aerodynamics - reasoniing and calculating - it is believed that a substantial part of the reasoning can be achieved with artificial intelligence, with computers being used as reasoning machines to set the stage for calculating. Expert systems will probably be new assets of institutions involved in aeronautics for various tasks of computational aerodynamics.
Computational aerodynamics and artificial intelligence
NASA Technical Reports Server (NTRS)
Mehta, U. B.; Kutler, P.
1984-01-01
The general principles of artificial intelligence are reviewed and speculations are made concerning how knowledge based systems can accelerate the process of acquiring new knowledge in aerodynamics, how computational fluid dynamics may use expert systems, and how expert systems may speed the design and development process. In addition, the anatomy of an idealized expert system called AERODYNAMICIST is discussed. Resource requirements for using artificial intelligence in computational fluid dynamics and aerodynamics are examined. Three main conclusions are presented. First, there are two related aspects of computational aerodynamics: reasoning and calculating. Second, a substantial portion of reasoning can be achieved with artificial intelligence. It offers the opportunity of using computers as reasoning machines to set the stage for efficient calculating. Third, expert systems are likely to be new assets of institutions involved in aeronautics for various tasks of computational aerodynamics.
Hoang-Minh, Lan B.; Deleyrolle, Loic P.; Siebzehnrubl, Dorit; Ugartemendia, George; Futch, Hunter; Griffith, Benjamin; Breunig, Joshua J.; De Leon, Gabriel; Mitchell, Duane A.; Semple-Rowland, Susan; Reynolds, Brent A.; Sarkisian, Matthew R.
2016-01-01
KIF3A, a component of the kinesin-2 motor, is necessary for the progression of diverse tumor types. This is partly due to its role in regulating ciliogenesis and cell responsiveness to sonic hedgehog (SHH). Notably, primary cilia have been detected in human glioblastoma multiforme (GBM) tumor biopsies and derived cell lines. Here, we asked whether disrupting KIF3A in GBM cells affected ciliogenesis, in vitro growth and responsiveness to SHH, or tumorigenic behavior in vivo. We used a lentiviral vector to create three patient-derived GBM cell lines expressing a dominant negative, motorless form of Kif3a (dnKif3a). In all unmodified lines, we found that most GBM cells were capable of producing ciliated progeny and that dnKif3a expression in these cells ablated ciliogenesis. Interestingly, unmodified and dnKif3a-expressing cell lines displayed differential sensitivities and pathway activation to SHH and variable tumor-associated survival following mouse xenografts. In one cell line, SHH-induced cell proliferation was prevented in vitro by either expressing dnKif3a or inhibiting SMO signaling using cyclopamine, and the survival times of mice implanted with dnKif3a-expressing cells were increased. In a second line, expression of dnKif3a increased the cells' baseline proliferation while, surprisingly, sensitizing them to SHH-induced cell death. The survival times of mice implanted with these dnKif3a-expressing cells were decreased. Finally, expression of dnKif3a in a third cell line had no effect on cell proliferation, SHH sensitivity, or mouse survival times. These findings indicate that KIF3A is essential for GBM cell ciliogenesis, but its role in modulating GBM cell behavior is highly variable. PMID:26760767
Li, Xiaocheng; Wang, Bin; Wang, Xiaolin; Zhou, Xiaoqing; Chen, Zhimin; He, Chunying; Yu, Zheying; Wu, Yiqun
2015-12-01
Three kinds of novel hybrid materials were prepared by noncovalent functionalized reduced graphene oxide (rGO) with tetra-α-iso-pentyloxyphthalocyanine copper (CuPc), tetra-α-iso-pentyloxyphthalocyanine nickel (NiPc) and tetra-α-iso-pentyloxyphthalocyanine lead (PbPc) and characterized by Fourier transform infrared spectroscopy (FT-IR), ultraviolet-visible spectroscopy (UV-vis), Raman spectra, X-ray photoelectron spectroscopy (XPS), transmission electron microscope (TEM), and atomic force microscope (AFM). The as-synthesized MPc/rGO hybrids show excellent NH3 gas-sensing performance with high response value and fast recovery time compared with bare rGO. The enhancement of the sensing response is mainly attributed to the synergism of gas adsorption of MPc to NH3 gas and conducting network of rGO with greater electron transfer efficiency. Strategies for combining the good properties of rGO and MPc derivatives will open new opportunities for preparing and designing highly efficient rGO chemiresistive gas-sensing hybrid materials for potential applications in gas sensor field. PMID:26403926
NASA Astrophysics Data System (ADS)
Li, Xiaocheng; Wang, Bin; Wang, Xiaolin; Zhou, Xiaoqing; Chen, Zhimin; He, Chunying; Yu, Zheying; Wu, Yiqun
2015-09-01
Three kinds of novel hybrid materials were prepared by noncovalent functionalized reduced graphene oxide (rGO) with tetra-α-iso-pentyloxyphthalocyanine copper (CuPc), tetra-α-iso-pentyloxyphthalocyanine nickel (NiPc) and tetra-α-iso-pentyloxyphthalocyanine lead (PbPc) and characterized by Fourier transform infrared spectroscopy (FT-IR), ultraviolet-visible spectroscopy (UV-vis), Raman spectra, X-ray photoelectron spectroscopy (XPS), transmission electron microscope (TEM), and atomic force microscope (AFM). The as-synthesized MPc/rGO hybrids show excellent NH3 gas-sensing performance with high response value and fast recovery time compared with bare rGO. The enhancement of the sensing response is mainly attributed to the synergism of gas adsorption of MPc to NH3 gas and conducting network of rGO with greater electron transfer efficiency. Strategies for combining the good properties of rGO and MPc derivatives will open new opportunities for preparing and designing highly efficient rGO chemiresistive gas-sensing hybrid materials for potential applications in gas sensor field.
García-Estévez, D A; Araújo-Vilar, D; Fiestras-Janeiro, G; Saavedra-González, A; Cabezas-Cerrato, J
2003-01-01
Some techniques for the evaluation of insulin resistance (IR), such as the clamp technique, are not viable for the study of large populations; and for this reason, alternative approaches based on fasting plasma glucose (FPG) and plasma insulin (FPI) have been proposed. The aim of this study was to compare the IR calculations obtained from FPI and FPG values with the insulin sensitivity (IS) index derived from the minimal model. Eighty-seven healthy subjects with a wide range of body mass index (18 - 44 kg x m -2) and 16 DM2 non-obese patients were included in the study. All of the patients underwent a frequently sampled intravenous glucose tolerance test (FSIGTT), and the minimal model of glucose was used for the estimation of insulin sensitivity (IS MINIMAL ). The HOMA-IR index, the Avignon index, and the quotient FPG/FPI were used to calculate basal steady-state IR. The basal IR value that best correlated with IS was Log (1/HOMA-IR) (r = 0.70, p < 0.001). All of the basal indices showed a high correlation with each other. In conclusions, insulin sensitivity indices as determined from the basal glycaemia and insulinemia values are not good estimators for metabolic reality from the perspective of the minimal model. Nevertheless, they might well have an IR screening value for epidemiological studies, as long as there is no pancreatic beta-cell dysfunction. PMID:12669265
Zhang, Xinai; Lu, Wenjie; Shen, Jianzhong; Jiang, Yuxiang; Han, En; Dong, Xiaoya; Huang, Jiali
2015-12-15
Accurate and highly sensitive detection of glycan expression on cell surface is extremely important for cancer diagnosis and therapy. Herein, a carbohydrate derivative-functionalized biosensor was developed for electrochemical detection of the expression level of cell surface glycan (mannose used as model). Thiomannosyl dimer was synthesized to design the thiomannosyl-functionalized biosensor by direct and rapid one-step protocols. The biosensing surface-confined mannose could effectively mimic the presentation of cell surface mannose and was responsible for competing with mannose on cancer cells in incubation solution. Greatly enhanced sensitivity was achieved by exploiting the excellent conductivity of multiwalled carbon nanotube/Au nanoparticle (MWNT/AuNP), the amplification effect of MWNTs, and the favorable catalytic ability of horseradish peroxidase (HRP). Using competitive strategy, the developed biosensor exhibits attractive performances for the analysis of mannose expression with rapid response, high sensitivity and accuracy, and possesses great promise for evaluation of cell surface glycan expression by using a greater variety of lectins. PMID:26143470
Koren, Klaus; Hutter, Lukas; Enko, Barbara; Pein, Andreas; Borisov, Sergey M.; Klimant, Ingo
2013-01-01
Ten different polystyrene-derivatives were tested with respect to their potential use as matrix materials for optical oxygen sensors in combination with the platinum(II) meso-tetra(4-fluorophenyl)tetrabenzoporphyrin as indicator dye. Either halogen atoms or bulky residues were introduced as substituents on the phenyl ring. A fine-tuning of the sensor sensitivity was achieved, without compromising solubility of the indicator in the matrix by providing a chemical environment very similar to polystyrene (PS), a standard matrix in optical oxygen sensors. To put the results into perspective, the studied materials were compared to PS regarding sensitivity of the sensor, molecular weight and glass-transition temperature. The materials promise to be viable alternatives to PS with respect to the requirements posed in various sensor application fields. Some of the polymers (e.g. poly(2,6-dichlorostyrene)) promise to be of use in applications requiring measurements from 0 to 100% oxygen due to linearity across this range. Poly(4-tert-butylstyrene) and poly(2,6-fluorostyrene), on the other hand, yield sensors with increased sensitivity. Sensor stability was evaluated as a function of the matrix, a topic which has not received a lot of interest so far. PMID:23576846
Bedut, Stephane; Seminatore-Nole, Christine; Lamamy, Veronique; Caignard, Sarah; Boutin, Jean A; Nosjean, Olivier; Stephan, Jean-Philippe; Coge, Francis
2016-07-01
Cardiomyocytes derived from human embryonic stem cells (hESCs) or induced pluripotent stem cells (hiPSCs) are increasingly used for in vitro assays and represent an interesting opportunity to increase the data throughput for drug development. In this work, we describe a 96-well recording of synchronous electrical activities from spontaneously beating hiPSC-derived cardiomyocyte monolayers. The signal was obtained with a fast-imaging plate reader using a submillisecond-responding membrane potential recording assay, FluoVolt, based on a newly derived voltage-sensitive fluorescent dye. In our conditions, the toxicity of the dye was moderate and compatible with episodic recordings for >3 h. We show that the waveforms recorded from a whole well or from a single cell-sized zone are equivalent and make available critical functional parameters that are usually accessible only with gold standard techniques like intracellular microelectrode recording. This approach allows accurate identification of the electrophysiological effects of reference drugs on the different phases of the cardiac action potential as follows: fast depolarization (lidocaine), early repolarization (nifedipine, Bay K8644, and veratridine), late repolarization (dofetilide), and diastolic slow depolarization (ivabradine). Furthermore, the data generated with the FluoVolt dye can be pertinently complemented with a calcium-sensitive dye for deeper characterization of the pharmacological responses. In a semiautomated plate reader, the two probes used simultaneously in 96-well plates provide an easy and powerful multiparametric assay to rapidly and precisely evaluate the cardiotropic profile of compounds for drug discovery or cardiac safety. PMID:27199128
NASA Astrophysics Data System (ADS)
Peña, Marco A.; Brenning, Alexander; Sagredo, Ariel
2012-11-01
Satellite hyperspectral data were used to construct empirical spectral indices related to the canopy structure of a Cordilleran Cypress (Austrocedrus chilensis) forest located in the Andes of central Chile. Measurements of tree diameter at breast height (DBH) and tree height (TH) were performed for a set of plots located within a pure and unevenly aged stand of A. chilensis with moderate cover. Normalized difference vegetation indices (NDIs) related to DBH and TH were constructed from the corresponding hyperspectral data in Hyperion imagery. NDIs construction utilized the original spectral reflectance curve, its first derivative, and the continuum-removed reflectance in a two-step procedure that ranks NDIs based on their Spearman correlation with the response variable while controlling the false discovery rate. Several reflectance-based NDIs as well as a larger group of derivative-based NDIs were significantly related to DBH or TH (ρ > 0.70). The NDIs most strongly related to the field variables were based on derivative bands located within the same spectral regions used by the broadband greenness index known as green normalized difference vegetation index. Most other significant NDIs used NIR bands, which are well-known for their sensitivity to foliage amount changes. The results obtained in this exploratory study mostly agreed with the spectral regions expected to be most sensitive to changes in the canopy structure of vegetation. Further research in other A. chilensis forests subject to different site and environmental conditions is needed in order to assess the applicability of the NDIs over a wider range of this endemic species.
Dynamic soaring: aerodynamics for albatrosses
NASA Astrophysics Data System (ADS)
Denny, Mark
2009-01-01
Albatrosses have evolved to soar and glide efficiently. By maximizing their lift-to-drag ratio L/D, albatrosses can gain energy from the wind and can travel long distances with little effort. We simplify the difficult aerodynamic equations of motion by assuming that albatrosses maintain a constant L/D. Analytic solutions to the simplified equations provide an instructive and appealing example of fixed-wing aerodynamics suitable for undergraduate demonstration.
Supersonic aerodynamics of delta wings
NASA Technical Reports Server (NTRS)
Wood, Richard M.
1988-01-01
Through the empirical correlation of experimental data and theoretical analysis, a set of graphs has been developed which summarize the inviscid aerodynamics of delta wings at supersonic speeds. The various graphs which detail the aerodynamic performance of delta wings at both zero-lift and lifting conditions were then employed to define a preliminary wing design approach in which both the low-lift and high-lift design criteria were combined to define a feasible design space.
NASA Astrophysics Data System (ADS)
Utvich, Alexis; Jemmott, Colin; Logan, Sheldon; Rossmann, Jenn
2003-11-01
A team of undergraduate students has performed experiments on Wiffle balls in the Harvey Mudd College wind tunnel facility. Wiffle balls are of particular interest because they can attain a curved trajectory with little or no pitcher-imparted spin. The reasons behind this have not previously been quantified formally. A strain gauge device was designed and constructed to measure the lift and drag forces on the Wiffle ball; a second device to measure lift and drag on a spinning ball was also developed. Experiments were conducted over a range of Reynolds numbers corresponding to speeds of roughly 0-40 mph. Lift forces of up to 0.2 N were measured for a Wiffle ball at 40 mph. This is believed to be due to air flowing into the holes on the Wiffle ball in addition to the effect of the holes on external boundary layer separation. A fog-based flow visualization system was developed in order to provide a deeper qualitative understanding of what occurred in the flowfield surrounding the ball. The data and observations obtained in this study support existing assumptions about Wiffle ball aerodynamics and begin to elucidate the mechanisms involved in Wiffle ball flight.
Aerodynamics of badminton shuttlecocks
NASA Astrophysics Data System (ADS)
Verma, Aekaansh; Desai, Ajinkya; Mittal, Sanjay
2013-08-01
A computational study is carried out to understand the aerodynamics of shuttlecocks used in the sport of badminton. The speed of the shuttlecock considered is in the range of 25-50 m/s. The relative contribution of various parts of the shuttlecock to the overall drag is studied. It is found that the feathers, and the net in the case of a synthetic shuttlecock, contribute the maximum. The gaps, in the lower section of the skirt, play a major role in entraining the surrounding fluid and causing a difference between the pressure inside and outside the skirt. This pressure difference leads to drag. This is confirmed via computations for a shuttlecock with no gaps. The synthetic shuttle experiences more drag than the feather model. Unlike the synthetic model, the feather shuttlecock is associated with a swirling flow towards the end of the skirt. The effect of the twist angle of the feathers on the drag as well as the flow has also been studied.
The aerodynamics of propellers
NASA Astrophysics Data System (ADS)
Wald, Quentin R.
2006-02-01
The theory and the design of propellers of minimum induced loss is treated. The pioneer analysis of this problem was presented more than half a century ago by Theodorsen, but obscurities in his treatment and inaccuracies and limited coverage in his tables of the Goldstein circulation function for helicoidal vortex sheets have not been remedied until the present work which clarifies and extends his work. The inverse problem, the prediction of the performance of a given propeller of arbitrary form, is also treated. The theory of propellers of minimum energy loss is dependent on considerations of a regular helicoidal trailing vortex sheet; consequently, a more detailed discussion of the dynamics of vortex sheets and the consequences of their instability and roll up is presented than is usually found in treatments of propeller aerodynamics. Complete and accurate tables of the circulation function are presented. Interference effects between a fuselage or a nacelle and the propeller are considered. The regimes of propeller, vortex ring, and windmill operation are characterized.
NASA Astrophysics Data System (ADS)
Dvořák, Rudolf
2016-03-01
Unlike airplanes birds must have either flapping or oscillating wings (the hummingbird). Only such wings can produce both lift and thrust - two sine qua non attributes of flying.The bird wings have several possibilities how to obtain the same functions as airplane wings. All are realized by the system of flight feathers. Birds have also the capabilities of adjusting the shape of the wing according to what the immediate flight situation demands, as well as of responding almost immediately to conditions the flow environment dictates, such as wind gusts, object avoidance, target tracking, etc. In bird aerodynamics also the tail plays an important role. To fly, wings impart downward momentum to the surrounding air and obtain lift by reaction. How this is achieved under various flight situations (cruise flight, hovering, landing, etc.), and what the role is of the wing-generated vortices in producing lift and thrust is discussed.The issue of studying bird flight experimentally from in vivo or in vitro experiments is also briefly discussed.
Efficient optimization of integrated aerodynamic-structural design
NASA Technical Reports Server (NTRS)
Haftka, R. T.; Grossman, B.; Eppard, W. M.; Kao, P. J.; Polen, D. M.
1989-01-01
Techniques for reducing the computational complexity of multidisciplinary design optimization (DO) of aerodynamic structures are described and demonstrated. The basic principles of aerodynamic and structural DO are reviewed; the formulation of the combined DO problem is outlined; and particular attention is given to (1) the application of perturbation methods to cross-sensitivity computations and (2) numerical approximation procedures. Trial DOs of a simple sailplane design are presented in tables and graphs and discussed in detail. The IBM 3090 CPU time for the entire integrated DO was reduced from an estimated 10 h to about 6 min.
NASA Technical Reports Server (NTRS)
Dill, C. C.; Young, J. C.; Roberts, B. B.; Craig, M. K.; Hamilton, J. T.; Boyle, W. W.
1985-01-01
The phase B Space Shuttle systems definition studies resulted in a generic configuration consisting of a delta wing orbiter, and two solid rocket boosters (SRB) attached to an external fuel tank (ET). The initial challenge facing the aerodynamic community was aerodynamically optimizing, within limits, this configuration. As the Shuttle program developed and the sensitivities of the vehicle to aerodynamics were better understood the requirements of the aerodynamic data base grew. Adequately characterizing the vehicle to support the various design studies exploded the size of the data base to proportions that created a data modeling/management challenge for the aerodynamicist. The ascent aerodynamic data base originated primarily from wind tunnel test results. The complexity of the configuration rendered conventional analytic methods of little use. Initial wind tunnel tests provided results which included undesirable effects from model support tructure, inadequate element proximity, and inadequate plume simulation. The challenge to improve the quality of test results by determining the extent of these undesirable effects and subsequently develop testing techniques to eliminate them was imposed on the aerodynamic community. The challenges to the ascent aerodynamics community documented are unique due to the aerodynamic complexity of the Shuttle launch. Never before was such a complex vehicle aerodynamically characterized. The challenges were met with innovative engineering analyses/methodology development and wind tunnel testing techniques.
Yu, Yan-Qing; Zhang, Hai-Yu; Chai, Ya-Qin; Yuan, Ruo; Zhuo, Ying
2016-11-15
Herein, a novel signal amplification strategy was designed using the perylene derivative as the co-reaction accelerator toward graphene-CdTe quantum dots (G-CdTe)/S2O8(2-) system to construct a highly sensitive electrochemiluminescent (ECL) aptasensor for thrombin (TB) detection. Firstly, the G-CdTe nanocomposites were prepared by one-step method of in situ generating CdTe quantum dots onto the surface of the graphene oxide by using 3-mercaptopropionic acid as the CdTe QDs stabilizer. Then, a kind of perylene derivative (PTC-Lys), was synthesized by covalently binding L-lysine to 3,4,9,10-perylenetetracarboxylic acid, which was further immobilized onto the G-CdTe by the π-π* stacking and cross-linked the detection thrombin aptamer (TBA II) to obtain the TBA II/PTC-Lys/G-CdTe signal probes. It is worth pointing out that PTC-Lys acting as an efficient co-reaction accelerator interacted with the co-reactant of S2O8(2-) rather than G-CdTe to promote the more oxidant mediators of SO4(•-), which could further react with G-CdTe to produce excited state species G-CdTe* for emitting light. Compared with the G-CdTe/S2O8(2-) ECL system, our proposed strategy with the introduction of co-reaction accelerator of PTC-Lys exhibited ultra-high sensitivity to quantify the concentration of TB from 1.0×10(-7)nM to 10nM with a detection limit of 34aM. PMID:27148827
Aerodynamic Indicial Functions and Their Use in Aeroelastic Formulation of Lifting Surfaces
NASA Technical Reports Server (NTRS)
Marzocca, Piergiovanni; Librescu, Liviu; Silva, Walter A.
2000-01-01
An investigation related to the use of linear indicial functions in the time and frequency domains, enabling one to derive the proper aerodynamic loads as to study the subcritical response and flutter of swept lifting surfaces, respectively, of the open/closed loop aeroelastic system is presented. The expressions of the lift and aerodynamic moment in the frequency domain are given in terms of the Theodorsen's function, while, in the time domain, these are obtained directly with the help of the Wagner's function. Closed form solutions of aerodynamic derivatives are obtained, graphical representations are supplied and conclusions and prospects for further developments are outlined.
Global Nonlinear Parametric Modeling with Application to F-16 Aerodynamics
NASA Technical Reports Server (NTRS)
Morelli, Eugene A.
1997-01-01
A global nonlinear parametric modeling technique is described and demonstrated. The technique uses multivariate orthogonal modeling functions generated from the data to determine nonlinear model structure, then expands each retained modeling function into an ordinary multivariate polynomial. The final model form is a finite multivariate power series expansion for the dependent variable in terms of the independent variables. Partial derivatives of the identified models can be used to assemble globally valid linear parameter varying models. The technique is demonstrated by identifying global nonlinear parametric models for nondimensional aerodynamic force and moment coefficients from a subsonic wind tunnel database for the F-16 fighter aircraft. Results show less than 10% difference between wind tunnel aerodynamic data and the nonlinear parameterized model for a simulated doublet maneuver at moderate angle of attack. Analysis indicated that the global nonlinear parametric models adequately captured the multivariate nonlinear aerodynamic functional dependence.
Global Nonlinear Parametric Modeling with Application to F-16 Aerodynamics
NASA Technical Reports Server (NTRS)
Morelli, Eugene A.
1998-01-01
A global nonlinear parametric modeling technique is described and demonstrated. The technique uses multivariate orthogonal modeling functions generated from the data to determine nonlinear model structure, then expands each retained modeling function into an ordinary multivariate polynomial. The final model form is a finite multivariate power series expansion for the dependent variable in terms of the independent variables. Partial derivatives of the identified models can be used to assemble globally valid linear parameter varying models. The technique is demonstrated by identifying global nonlinear parametric models for nondimensional aerodynamic force and moment coefficients from a subsonic wind tunnel database for the F-16 fighter aircraft. Results show less than 10% difference between wind tunnel aerodynamic data and the nonlinear parameterized model for a simulated doublet maneuver at moderate angle of attack. Analysis indicated that the global nonlinear parametric models adequately captured the multivariate nonlinear aerodynamic functional dependence.
Exploring the aerodynamic drag of a moving cyclist
NASA Astrophysics Data System (ADS)
Theilmann, Florian; Reinhard, Christopher
2016-01-01
Although the physics of cycling itself is a complex mixture of aerodynamics, physiology, mechanics, and heuristics, using cycling as a context for teaching physics has a tradition of certainly more than 30 years. Here, a possible feature is the discussion of the noticeable resistant forces such as aerodynamic drag and the associated power consumption of cycling. We use an energy-based approach to model the power input for driving a bike at a constant speed. This approach uses a numerical simulation of the slowing down of a bike moving without pedaling which is implementable with standard spreadsheet software. The simulation can be compared directly to simple measurements with real bikes as well as to an analytic solution of the underlying differential equation. It is possible to derive realistic values for the aerodynamic drag coefficient {{c}\\text{D}} and the total power consumption within a secondary physics course. We also report experiences from teaching such a course to class 8 students.
Aerodynamic comparisons of STS-1 Space Shuttle entry vehicle
NASA Technical Reports Server (NTRS)
Young, J. C.
1982-01-01
A conventional flight-test program, which slowly and cautiously approaches more severe flight conditions, was not possible with the Orbiter. On the first flight, the Orbiter entered the atmosphere at Mach 28 and decelerated through the Mach range. (The subsonic portion of flight was also flown by another orbiter vehicle during the Approach and Landing Test Program.) Certification for the first flight was achieved by an extensive wind-tunnel test and analysis program and by restricting the flight maneuvers severely. The initial flights of the orbiter were heavily instrumented for the purpose of obtaining accurate aerodynamic data. Even without maneuvers to excite the system, the first flight provided comparisons between flight and wind-tunnel-derived predicted data in the areas of aerodynamic performance, longitudinal trim, and reaction-control jet interaction. The aerodynamic performance comparisons are presented.
Makino, Yasushi; Omichi, Kaoru
2009-07-01
The action of glycogen phosphorylase (GP) is essentially reversible, although GP is generally classified as a glycogen-degrading enzyme. In this study, we developed a highly sensitive and convenient assay for GP activity by analysing its chain-lengthening action on a fluorogenic maltooligosaccharide derivative in a glucose-1-phosphate-rich medium. Characterization of the substrate specificity of GP using pyridylaminated (PA-) maltooligosaccharides of various sizes revealed that a maltotetraosyl (Glc(4)) residue comprising the non-reducing-end of a PA-maltooligosaccharide is indispensable for the chain-lengthening action of GP, and PA-maltohexaose is the most suitable substrate for the purpose of this study. By using a high-performance liquid chromatograph equipped with a fluorescence spectrophotometer, PA-maltoheptaose produced by the chain elongation of PA-maltohexaose could be isolated and quantified at 10 fmol. This method was used to measure the GP activities of crude and purified GP preparations, and was demonstrated to have about 1,000 times greater sensitivity than the spectrophotometric orthophosphate assay. PMID:19279194
Mangiamele, Lisa A; Fuxjager, Matthew J; Schuppe, Eric R; Taylor, Rebecca S; Hödl, Walter; Preininger, Doris
2016-05-17
Physical gestures are prominent features of many species' multimodal displays, yet how evolution incorporates body and leg movements into animal signaling repertoires is unclear. Androgenic hormones modulate the production of reproductive signals and sexual motor skills in many vertebrates; therefore, one possibility is that selection for physical signals drives the evolution of androgenic sensitivity in select neuromotor pathways. We examined this issue in the Bornean rock frog (Staurois parvus, family: Ranidae). Males court females and compete with rivals by performing both vocalizations and hind limb gestural signals, called "foot flags." Foot flagging is a derived display that emerged in the ranids after vocal signaling. Here, we show that administration of testosterone (T) increases foot flagging behavior under seminatural conditions. Moreover, using quantitative PCR, we also find that adult male S. parvus maintain a unique androgenic phenotype, in which androgen receptor (AR) in the hind limb musculature is expressed at levels ∼10× greater than in two other anuran species, which do not produce foot flags (Rana pipiens and Xenopus laevis). Finally, because males of all three of these species solicit mates with calls, we accordingly detect no differences in AR expression in the vocal apparatus (larynx) among taxa. The results show that foot flagging is an androgen-dependent gestural signal, and its emergence is associated with increased androgenic sensitivity within the hind limb musculature. Selection for this novel gestural signal may therefore drive the evolution of increased AR expression in key muscles that control signal production to support adaptive motor performance. PMID:27143723
Bertin, Daniel; Dubucquoi, Sylvain; Lakomy, Daniela; Deleplancque, Anne-Sophie; Desplat-Jégo, Sophie
2016-04-01
Autoantibodies are a common feature of rheumatoid arthritis (RA), and their detection is used as a diagnostic tool in medical practice. Rheumatoid factor (RF) and/or anti-citrullinated protein antibodies (ACPA) detection in patients' sera are now included in 2010 ACR/EULAR criteria for RA diagnosis. In this study, we evaluated a new vimentin-derived ACPA ELISA, the anti-cyclic citrullinated peptide high sensitive (CCP hs) test, and we compared its performance with the RF IgM and anti-CCP3 tests on a French multicenter cohort of 84 RA patients, 107 non-RA patients and 100 healthy controls. Sensitivities for RA diagnosis were 71.4, 84.5 and 64.3 % and specificities were 88.4, 86.9 and 87.3 % for CCP hs, CCP3 and RF IgM, respectively. There was a moderate correlation between CCP hs and CCP3 titers (Pearson's r = 0.43; p < 0.0001). These results support the contention that anti-CCP hs antibodies are new reliable ACPA with high specificity for RA. PMID:26350265
Aerodynamics via acoustics - Application of acoustic formulas for aerodynamic calculations
NASA Technical Reports Server (NTRS)
Farassat, F.; Myers, M. K.
1986-01-01
Prediction of aerodynamic loads on bodies in arbitrary motion is considered from an acoustic point of view, i.e., in a frame of reference fixed in the undisturbed medium. An inhomogeneous wave equation which governs the disturbance pressure is constructed and solved formally using generalized function theory. When the observer is located on the moving body surface there results a singular linear integral equation for surface pressure. Two different methods for obtaining such equations are discussed. Both steady and unsteady aerodynamic calculations are considered. Two examples are presented, the more important being an application to propeller aerodynamics. Of particular interest for numerical applications is the analytical behavior of the kernel functions in the various integral equations.
Aerodynamics Via Acoustics: Application of Acoustic Formulas for Aerodynamic Calculations
NASA Technical Reports Server (NTRS)
Farassat, F.; Myers, M. K.
1986-01-01
Prediction of aerodynamic loads on bodies in arbitrary motion is considered from an acoustic point of view, i.e., in a frame of reference fixed in the undisturbed medium. An inhomogeneous wave equation which governs the disturbance pressure is constructed and solved formally using generalized function theory. When the observer is located on the moving body surface there results a singular linear integral equation for surface pressure. Two different methods for obtaining such equations are discussed. Both steady and unsteady aerodynamic calculations are considered. Two examples are presented, the more important being an application to propeller aerodynamics. Of particular interest for numerical applications is the analytical behavior of the kernel functions in the various integral equations.
Fiorica, Calogero; Pitarresi, Giovanna; Palumbo, Fabio Salvatore; Di Stefano, Mauro; Calascibetta, Filippo; Giammona, Gaetano
2013-11-30
Atom transfer radical polymerization (ATRP) has been successfully employed to obtain a new derivative of hyaluronic acid (HA) able to change its solubility as a function of external pH and then to be potentially useful for intestinal release of bioactive molecules, included enzymes and proteins. In particular, a macroinitiator has been prepared by linking 2-bromo-2-methypropionic acid (BMP) to the amino groups of ethylenediamino derivative of tetrabutyl ammonium salt of HA (HA-TBA-EDA). This macroinititor, named HA-TBA-EDA-BMP has been used for the ATRP of sodium methacrylate (MANa) using a complex of Cu(I) and 2,2'-bipyridyl (Byp) as a catalyst. The resulting copolymer, named HA-EDA-BMP-MANa, has been characterized by (1)H NMR and size exclusion chromatography (SEC) analyses. A turbidimetric analysis has showed its pH sensitive behavior, being insoluble in simulated gastric fluid but soluble when pH increases more than 2.5. To confirm the ability of HA-EDA-BMP-MANa in protecting peptides or proteins from denaturation in acidic medium, α-chymotrypsin has been chosen as a model of protein molecule and its activity has been evaluated after entrapment into HA-EDA-BMP-MANa chains and treatment under simulated gastric conditions. Finally, cell compatibility has been evaluated by performing a MTS assay on murine dermal fibroblasts cultured with HA-EDA-BMP-MANa solutions. PMID:24060369
Configuration Aerodynamics: Past - Present - Future
NASA Technical Reports Server (NTRS)
Wood, Richard M.; Agrawal, Shreekant; Bencze, Daniel P.; Kulfan, Robert M.; Wilson, Douglas L.
1999-01-01
The Configuration Aerodynamics (CA) element of the High Speed Research (HSR) program is managed by a joint NASA and Industry team, referred to as the Technology Integration Development (ITD) team. This team is responsible for the development of a broad range of technologies for improved aerodynamic performance and stability and control characteristics at subsonic to supersonic flight conditions. These objectives are pursued through the aggressive use of advanced experimental test techniques and state of the art computational methods. As the HSR program matures and transitions into the next phase the objectives of the Configuration Aerodynamics ITD are being refined to address the drag reduction needs and stability and control requirements of High Speed Civil Transport (HSCT) aircraft. In addition, the experimental and computational tools are being refined and improved to meet these challenges. The presentation will review the work performed within the Configuration Aerodynamics element in 1994 and 1995 and then discuss the plans for the 1996-1998 time period. The final portion of the presentation will review several observations of the HSR program and the design activity within Configuration Aerodynamics.
Aerodynamic drag on intermodal railcars
NASA Astrophysics Data System (ADS)
Kinghorn, Philip; Maynes, Daniel
2014-11-01
The aerodynamic drag associated with transport of commodities by rail is becoming increasingly important as the cost of diesel fuel increases. This study aims to increase the efficiency of intermodal cargo trains by reducing the aerodynamic drag on the load carrying cars. For intermodal railcars a significant amount of aerodynamic drag is a result of the large distance between loads that often occurs and the resulting pressure drag resulting from the separated flow. In the present study aerodynamic drag data have been obtained through wind tunnel testing on 1/29 scale models to understand the savings that may be realized by judicious modification to the size of the intermodal containers. The experiments were performed in the BYU low speed wind tunnel and the test track utilizes two leading locomotives followed by a set of five articulated well cars with double stacked containers. The drag on a representative mid-train car is measured using an isolated load cell balance and the wind tunnel speed is varied from 20 to 100 mph. We characterize the effect that the gap distance between the containers and the container size has on the aerodynamic drag of this representative rail car and investigate methods to reduce the gap distance.
Xie, Qiang; Zhou, Yangliang; Lan, Guoqiang; Yang, Liye; Zheng, Wenjie; Liang, Yuanwei; Chen, Tianfeng
2014-06-20
Highlights: • Selenadiazole derivatives could be used as an effective and low toxic sensitizer for radiotherapy. • Selenadiazole derivatives enhances radiation-induced growth inhibition on A375 cells through induction of G2/M arrest. • ROS-mediated signaling pathways play important roles in radiosensitization of selenadiazole derivatives. - Abstract: X-ray-based radiotherapy represents one of the most effective ways in treating human cancers. However, radioresistance and side effect remain as the most challenging issue. This study describes the design and application of novel selenadiazole derivatives as radiotherapy sensitizers to enhance X-ray-induced inhibitory effects on A375 human melanoma and Hela human cervical carcinoma cells. The results showed that, pretreatment of the cells with selenadiazole derivatives dramatically enhance X-ray-induced growth inhibition and colony formation. Flow cytometry analysis indicates that the sensitization by selenadiazole derivatives was mainly caused by induction of G2/M cell cycle arrest. Results of Western blotting demonstrated that the combined treatment-induced A375 cells growth inhibition was achieved by triggering reactive oxygen species-mediated DNA damage involving inactivation of AKT and MAPKs. Further investigation revealed that selenadiazole derivative in combination with X-ray could synergistically inhibit the activity of thioredoxin reductase-1 in A375 cells. Taken together, these results suggest that selenadiazole derivatives can act as novel radiosensitizer with potential application in combating human cancers.
Study of aerodynamic technology for VSTOL fighter/attack aircraft, phase 1
NASA Technical Reports Server (NTRS)
Driggers, H. H.
1978-01-01
A conceptual design study was performed of a vertical attitude takeoff and landing (VATOL) fighter/attack aircraft. The configuration has a close-coupled canard-delta wing, side two-dimensional ramp inlets, and two augmented turbofan engines with thrust vectoring capability. Performance and sensitivities to objective requirements were calculated. Aerodynamic characteristics were estimated based on contractor and NASA wind tunnel data. Computer simulations of VATOL transitions were performed. Successful transitions can be made, even with series post-stall instabilities, if reaction controls are properly phased. Principal aerodynamic uncertainties identified were post-stall aerodynamics, transonic aerodynamics with thrust vectoring and inlet performance in VATOL transition. A wind tunnel research program was recommended to resolve the aerodynamic uncertainties.
New technology in turbine aerodynamics.
NASA Technical Reports Server (NTRS)
Glassman, A. J.; Moffitt, T. P.
1972-01-01
Cursory review of some recent work that has been done in turbine aerodynamic research. Topics discussed include the aerodynamic effect of turbine coolant, high work-factor (ratio of stage work to square of blade speed) turbines, and computer methods for turbine design and performance prediction. Experimental cooled-turbine aerodynamics programs using two-dimensional cascades, full annular cascades, and cold rotating turbine stage tests are discussed with some typical results presented. Analytically predicted results for cooled blade performance are compared to experimental results. The problems and some of the current programs associated with the use of very high work factors for fan-drive turbines of high-bypass-ratio engines are discussed. Computer programs have been developed for turbine design-point performance, off-design performance, supersonic blade profile design, and the calculation of channel velocities for subsonic and transonic flowfields. The use of these programs for the design and analysis of axial and radial turbines is discussed.
Recent advances in computational aerodynamics
NASA Astrophysics Data System (ADS)
Agarwal, Ramesh K.; Desse, Jerry E.
1991-04-01
The current state of the art in computational aerodynamics is described. Recent advances in the discretization of surface geometry, grid generation, and flow simulation algorithms have led to flowfield predictions for increasingly complex and realistic configurations. As a result, computational aerodynamics is emerging as a crucial enabling technology for the development and design of flight vehicles. Examples illustrating the current capability for the prediction of aircraft, launch vehicle and helicopter flowfields are presented. Unfortunately, accurate modeling of turbulence remains a major difficulty in the analysis of viscosity-dominated flows. In the future inverse design methods, multidisciplinary design optimization methods, artificial intelligence technology and massively parallel computer technology will be incorporated into computational aerodynamics, opening up greater opportunities for improved product design at substantially reduced costs.
Multidisciplinary Aerodynamic-Structural Shape Optimization Using Deformation (MASSOUD)
NASA Technical Reports Server (NTRS)
Samareh, Jamshid A.
2000-01-01
This paper presents a multidisciplinary shape parameterization approach. The approach consists of two basic concepts: (1) parameterizing the shape perturbations rather than the geometry itself and (2) performing the shape deformation by means of the soft object animation algorithms used in computer graphics. Because the formulation presented in this paper is independent of grid topology, we can treat computational fluid dynamics and finite element grids in the same manner. The proposed approach is simple, compact, and efficient. Also, the analytical sensitivity derivatives are easily computed for use in a gradient-based optimization. This algorithm is suitable for low-fidelity (e.g., linear aerodynamics and equivalent laminate plate structures) and high-fidelity (e.g., nonlinear computational fluid dynamics and detailed finite element modeling) analysis tools. This paper contains the implementation details of parameterizing for planform, twist, dihedral, thickness, camber, and free-form surface. Results are presented for a multidisciplinary application consisting of nonlinear computational fluid dynamics, detailed computational structural mechanics, and a simple performance module.
Aerodynamics Research Revolutionizes Truck Design
NASA Technical Reports Server (NTRS)
2008-01-01
During the 1970s and 1980s, researchers at Dryden Flight Research Center conducted numerous tests to refine the shape of trucks to reduce aerodynamic drag and improved efficiency. During the 1980s and 1990s, a team based at Langley Research Center explored controlling drag and the flow of air around a moving body. Aeroserve Technologies Ltd., of Ottawa, Canada, with its subsidiary, Airtab LLC, in Loveland, Colorado, applied the research from Dryden and Langley to the development of the Airtab vortex generator. Airtabs create two counter-rotating vortices to reduce wind resistance and aerodynamic drag of trucks, trailers, recreational vehicles, and many other vehicles.
Orion Aerodynamics for Hypersonic Free Molecular to Continuum Conditions
NASA Technical Reports Server (NTRS)
Moss, James N.; Greene, Francis A.; Boyles, Katie A.
2006-01-01
Numerical simulations are performed for the Orion Crew Module, previously known as the Crew Exploration Vehicle (CEV) Command Module, to characterize its aerodynamics during the high altitude portion of its reentry into the Earth's atmosphere, that is, from free molecular to continuum hypersonic conditions. The focus is on flow conditions similar to those that the Orion Crew Module would experience during a return from the International Space Station. The bulk of the calculations are performed with two direct simulation Monte Carlo (DSMC) codes, and these data are anchored with results from both free molecular and Navier-Stokes calculations. Results for aerodynamic forces and moments are presented that demonstrate their sensitivity to rarefaction, that is, for free molecular to continuum conditions (Knudsen numbers of 111 to 0.0003). Also included are aerodynamic data as a function of angle of attack for different levels of rarefaction and results that demonstrate the aerodynamic sensitivity of the Orion CM to a range of reentry velocities (7.6 to 15 km/s).
Aerodynamics Of Missiles: Present And Future
NASA Technical Reports Server (NTRS)
Nielsen, Jack N.
1991-01-01
Paper reviews variety of topics in aerodynamics of missiles. Describes recent developments and suggests areas in which future research fruitful. Emphasis on stability and control of tactical missiles. Aerodynamic problems discussed in general terms without reference to particular missiles.
Experimental aerodynamics research on a hypersonic vehicle
Oberkampf, W.L.; Aeschliman, D.P.; Tate, R.E.; Henfling, J.F.
1993-04-01
Aerodynamic force and moment measurements and flow visualization results are presented for a hypersonic vehicle configuration at Mach 8. The basic vehicle configuration is a spherically blunted 10[degree] half-angle cone with a slice parallel with the axis of the vehicle. On the slice portion of the vehicle, a flap could be attached so that deflection angles of 10[degree], 20[degree] and 30[degree] could be obtained. All of the experimental results were obtained in the Sandia Mach 8 hypersonic wind tunnel for laminar boundary layer conditions. Flow visualization results include shear stress sensitive liquid crystal photographs, surface streak flow photographs (using liquid crystals), and spark schlieren photographs and video. The liquid crystals were used as an aid in verifying that a laminar boundary layer existed over the entire body. The surface flow photo-graphs show attached and separated flow on both the leeside of the vehicle and near the flap. A detailed uncertainty analysis was conducted to estimate the contributors to body force and moment measurement uncertainty. Comparisons are made with computational results to evaluate both the experimental and numerical results. This extensive set of high-quality experimental force and moment measurements is recommended for use in the calibration and validation of relevant computational aerodynamics codes.
Experimental aerodynamics research on a hypersonic vehicle
Oberkampf, W.L.; Aeschliman, D.P.; Tate, R.E.; Henfling, J.F.
1993-04-01
Aerodynamic force and moment measurements and flow visualization results are presented for a hypersonic vehicle configuration at Mach 8. The basic vehicle configuration is a spherically blunted 10{degree} half-angle cone with a slice parallel with the axis of the vehicle. On the slice portion of the vehicle, a flap could be attached so that deflection angles of 10{degree}, 20{degree} and 30{degree} could be obtained. All of the experimental results were obtained in the Sandia Mach 8 hypersonic wind tunnel for laminar boundary layer conditions. Flow visualization results include shear stress sensitive liquid crystal photographs, surface streak flow photographs (using liquid crystals), and spark schlieren photographs and video. The liquid crystals were used as an aid in verifying that a laminar boundary layer existed over the entire body. The surface flow photo-graphs show attached and separated flow on both the leeside of the vehicle and near the flap. A detailed uncertainty analysis was conducted to estimate the contributors to body force and moment measurement uncertainty. Comparisons are made with computational results to evaluate both the experimental and numerical results. This extensive set of high-quality experimental force and moment measurements is recommended for use in the calibration and validation of relevant computational aerodynamics codes.
Mangiamele, Lisa A.; Fuxjager, Matthew J.; Schuppe, Eric R.; Taylor, Rebecca S.; Hödl, Walter; Preininger, Doris
2016-01-01
Physical gestures are prominent features of many species’ multimodal displays, yet how evolution incorporates body and leg movements into animal signaling repertoires is unclear. Androgenic hormones modulate the production of reproductive signals and sexual motor skills in many vertebrates; therefore, one possibility is that selection for physical signals drives the evolution of androgenic sensitivity in select neuromotor pathways. We examined this issue in the Bornean rock frog (Staurois parvus, family: Ranidae). Males court females and compete with rivals by performing both vocalizations and hind limb gestural signals, called “foot flags.” Foot flagging is a derived display that emerged in the ranids after vocal signaling. Here, we show that administration of testosterone (T) increases foot flagging behavior under seminatural conditions. Moreover, using quantitative PCR, we also find that adult male S. parvus maintain a unique androgenic phenotype, in which androgen receptor (AR) in the hind limb musculature is expressed at levels ∼10× greater than in two other anuran species, which do not produce foot flags (Rana pipiens and Xenopus laevis). Finally, because males of all three of these species solicit mates with calls, we accordingly detect no differences in AR expression in the vocal apparatus (larynx) among taxa. The results show that foot flagging is an androgen-dependent gestural signal, and its emergence is associated with increased androgenic sensitivity within the hind limb musculature. Selection for this novel gestural signal may therefore drive the evolution of increased AR expression in key muscles that control signal production to support adaptive motor performance. PMID:27143723
Unsteady aerodynamics modeling for flight dynamics application
NASA Astrophysics Data System (ADS)
Wang, Qing; He, Kai-Feng; Qian, Wei-Qi; Zhang, Tian-Jiao; Cheng, Yan-Qing; Wu, Kai-Yuan
2012-02-01
In view of engineering application, it is practicable to decompose the aerodynamics into three components: the static aerodynamics, the aerodynamic increment due to steady rotations, and the aerodynamic increment due to unsteady separated and vortical flow. The first and the second components can be presented in conventional forms, while the third is described using a one-order differential equation and a radial-basis-function (RBF) network. For an aircraft configuration, the mathematical models of 6-component aerodynamic coefficients are set up from the wind tunnel test data of pitch, yaw, roll, and coupled yawroll large-amplitude oscillations. The flight dynamics of an aircraft is studied by the bifurcation analysis technique in the case of quasi-steady aerodynamics and unsteady aerodynamics, respectively. The results show that: (1) unsteady aerodynamics has no effect upon the existence of trim points, but affects their stability; (2) unsteady aerodynamics has great effects upon the existence, stability, and amplitudes of periodic solutions; and (3) unsteady aerodynamics changes the stable regions of trim points obviously. Furthermore, the dynamic responses of the aircraft to elevator deflections are inspected. It is shown that the unsteady aerodynamics is beneficial to dynamic stability for the present aircraft. Finally, the effects of unsteady aerodynamics on the post-stall maneuverability are analyzed by numerical simulation.
Langley Symposium on Aerodynamics, volume 1
NASA Technical Reports Server (NTRS)
Stack, Sharon H. (Compiler)
1986-01-01
The purpose of this work was to present current work and results of the Langley Aeronautics Directorate covering the areas of computational fluid dynamics, viscous flows, airfoil aerodynamics, propulsion integration, test techniques, and low-speed, high-speed, and transonic aerodynamics. The following sessions are included in this volume: theoretical aerodynamics, test techniques, fluid physics, and viscous drag reduction.
Delorenzi, Mauro; Jensen, Thomas; Jensen, Peter Buhl; Bosman, Fred; Tejpar, Sabine; Roth, Arnaud; Brunner, Nils; Hansen, Anker; Knudsen, Steen
2016-01-01
Purpose This study evaluates whether gene signatures for chemosensitivity for irinotecan and 5-fluorouracil (5-FU) derived from in vitro grown cancer cell lines can predict clinical sensitivity to these drugs. Methods To test if an irinotecan signature and a SN-38 signature could identify patients who benefitted from the addition of irinotecan to 5-FU, we used gene expression profiles based on cell lines and clinical tumor material. These profiles were applied to expression data obtained from pretreatment formalin fixed paraffin embedded (FFPE) tumor tissue from 636 stage III colon cancer patients enrolled in the PETACC-3 prospective randomized clinical trial. A 5-FU profile developed similarly was assessed by comparing the PETACC-3 cohort with a cohort of 359 stage II colon cancer patients who underwent surgery but received no adjuvant therapy. Results There was no statistically significant association between the irinotecan or SN-38 profiles and benefit from irinotecan. The 5-FU sensitivity profile showed a statistically significant association with relapse free survival (RFS) (hazard ratio (HR) = 0.54 (0.41–0.71), p<1e-05) and overall survival (HR = 0.47 (0.34–0.63), p<1e-06) in the PETACC-3 subpopulation. The effect of the 5-FU profile remained significant in a multivariable Cox Proportional Hazards model, adjusting for several relevant clinicopathological parameters. No statistically significant effect of the 5-FU profile was observed in the untreated cohort of 359 patients (relapse free survival, p = 0.671). Conclusion The irinotecan predictor had no predictive value. The 5-FU predictor was prognostic in stage III patients in PETACC-3 but not in stage II patients with no adjuvant therapy. This suggests a potential predictive ability of the 5-FU sensitivity profile to identify colon cancer patients who may benefit from 5-FU, however, any biomarker predicting benefit for adjuvant 5-FU must be rigorously evaluated in independent cohorts. Given differences
Experimental Study Of SHEFEX II Hypersonic Aerodynamics And Canard Efficiency In H2K
NASA Astrophysics Data System (ADS)
Neeb, D.; Gulhan, A.
2011-05-01
One main objective of the DLR SHEFEX programme is to prove that sharp edged vehicles are capable of performing a re-entry into earth atmosphere by using a simple thermal protection system consisting of flat ceramic tiles. In comparison to blunt nose configurations like the Space shuttle, which are normally used for re-entry configurations, the SHEFEX TPS design is able to significantly reduce the costs and complexity of TPS structures and simultaneously increase the aerodynamic performance of the flight vehicle [1], [2]. To study its characteristics and perform several defined in-flight experiments during re-entry, the vehicle’s attitude will be controlled actively by canards [3]. In the framework of the SHEFEX II project an experimental investigation has been conducted in the hypersonic wind tunnel H2K to characterize the aerodynamic performance of the vehicle in hypersonic flow regime. The model has a modular design to enable the study of a variety of different influencing parameters. Its 4 circumferential canards have been made independently adjustable to account for the simulation of different manoeuvre conditions. To study the control behaviour of the vehicle and validate CFD data, a variation of canard deflections, angle of attack and angle of sideslip have been applied. Tests have been carried out at Mach 7 and 8.7 with a Reynolds number sensitivity study at the lower Mach number. The model was equipped with a six component internal balance to realize accurate coefficient measurements. The flow topology has been analyzed using Schlieren images. Beside general aerodynamic performance and canard efficiencies, flow phenomena like shock impingement on the canards could be determined by Schlieren images as well as by the derived coefficients.
Semianalytic modeling of aerodynamic shapes
NASA Technical Reports Server (NTRS)
Barger, R. L.; Adams, M. S.
1985-01-01
Equations for the semianalytic representation of a class of surfaces that vary smoothly in cross-sectional shape are presented. Some methods of fitting together and superimposing such surfaces are described. A brief discussion is also included of the application of the theory in various contexts such as computerized lofting of aerodynamic surfaces and grid generation.
Aerodynamic laboratory at Cuatro Vientos
NASA Technical Reports Server (NTRS)
JUBERA
1922-01-01
This report presents a listing of the many experiments in aerodynamics taking place at Cuatro Vientos. Some of the studies include: testing spheres, in order to determine coefficients; mechanical and chemical tests of materials; and various tests of propeller strength and flexibility.
New technology in turbine aerodynamics
NASA Technical Reports Server (NTRS)
Glassman, A. J.; Moffitt, T. P.
1972-01-01
A cursory review is presented of some of the recent work that has been done in turbine aerodynamic research at NASA-Lewis Research Center. Topics discussed include the aerodynamic effect of turbine coolant, high work-factor (ratio of stage work to square of blade speed) turbines, and computer methods for turbine design and performance prediction. An extensive bibliography is included. Experimental cooled-turbine aerodynamics programs using two-dimensional cascades, full annular cascades, and cold rotating turbine stage tests are discussed with some typical results presented. Analytically predicted results for cooled blade performance are compared to experimental results. The problems and some of the current programs associated with the use of very high work factors for fan-drive turbines of high-bypass-ratio engines are discussed. Turbines currently being investigated make use of advanced blading concepts designed to maintain high efficiency under conditions of high aerodynamic loading. Computer programs have been developed for turbine design-point performance, off-design performance, supersonic blade profile design, and the calculation of channel velocities for subsonic and transonic flow fields. The use of these programs for the design and analysis of axial and radial turbines is discussed.
Dynamic Soaring: Aerodynamics for Albatrosses
ERIC Educational Resources Information Center
Denny, Mark
2009-01-01
Albatrosses have evolved to soar and glide efficiently. By maximizing their lift-to-drag ratio "L/D", albatrosses can gain energy from the wind and can travel long distances with little effort. We simplify the difficult aerodynamic equations of motion by assuming that albatrosses maintain a constant "L/D". Analytic solutions to the simplified…
POEMS in Newton's Aerodynamic Frustum
ERIC Educational Resources Information Center
Sampedro, Jaime Cruz; Tetlalmatzi-Montiel, Margarita
2010-01-01
The golden mean is often naively seen as a sign of optimal beauty but rarely does it arise as the solution of a true optimization problem. In this article we present such a problem, demonstrating a close relationship between the golden mean and a special case of Newton's aerodynamical problem for the frustum of a cone. Then, we exhibit a parallel…
Aerodynamic design via control theory
NASA Technical Reports Server (NTRS)
Jameson, Antony
1988-01-01
The question of how to modify aerodynamic design in order to improve performance is addressed. Representative examples are given to demonstrate the computational feasibility of using control theory for such a purpose. An introduction and historical survey of the subject is included.
Shuttle reentry aerodynamic heating test
NASA Technical Reports Server (NTRS)
Pond, J. E.; Mccormick, P. O.; Smith, S. D.
1971-01-01
The research for determining the space shuttle aerothermal environment is reported. Brief summaries of the low Reynolds number windward side heating test, and the base and leeward heating and high Reynolds number heating test are included. Also discussed are streamline divergence and the resulting effect on aerodynamic heating, and a thermal analyzer program that is used in the Thermal Environment Optimization Program.
Rotary wing aerodynamically generated noise
NASA Technical Reports Server (NTRS)
Schmitz, F. J.; Morse, H. A.
1982-01-01
The history and methodology of aerodynamic noise reduction in rotary wing aircraft are presented. Thickness noise during hover tests and blade vortex interaction noise are determined and predicted through the use of a variety of computer codes. The use of test facilities and scale models for data acquisition are discussed.
Hedlund, Eva-Maria Eleonora; Yang, Xiaojuan; Zhang, Yin; Yang, Yunlong; Shibuya, Masabumi; Zhong, Weide; Sun, Baocun; Liu, Yizhi; Hosaka, Kayoko; Cao, Yihai
2013-01-01
The role of placental growth factor (PlGF) in modulation of tumor angiogenesis and tumor growth remains an enigma. Furthermore, anti-PlGF therapy in tumor angiogenesis and tumor growth remains controversial in preclinical tumor models. Here we show that in both human and mouse tumors, PlGF induced the formation of dilated and normalized vascular networks that were hypersensitive to anti-VEGF and anti–VEGFR-2 therapy, leading to dormancy of a substantial number of avascular tumors. Loss-of-function using plgf shRNA in a human choriocarcinoma significantly accelerated tumor growth rates and acquired resistance to anti-VEGF drugs, whereas gain-of-function of PlGF in a mouse tumor increased anti-VEGF sensitivity. Further, we show that VEGFR-2 and VEGFR-1 blocking antibodies displayed opposing effects on tumor angiogenesis. VEGFR-1 blockade and genetic deletion of the tyrosine kinase domain of VEGFR-1 resulted in enhanced tumor angiogenesis. These findings demonstrate that tumor-derived PlGF negatively modulates tumor angiogenesis and tumor growth and may potentially serve as a predictive marker of anti-VEGF cancer therapy. PMID:23267058
Tang, Jia-Liang; Li, Chun-Yan; Li, Yong-Fei; Lu, Xi; Qi, Hong-Rui
2015-08-12
A rhodamine spirolactam derivative (1) is developed as a colormetric and fluorescent probe for trivalent aluminum ions (Al(3+)). It exhibits a highly sensitive "turn-on" fluorescent response toward Al(3+) with a 70-fold fluorescence intensity enhancement under 2 equiv. of Al(3+) added. The probe can be applied to the quantification of Al(3+) with a linear range covering from 5.0 × 10(-7) to 2.0 × 10(-5) M and a detection limit of 4.0 × 10(-8) M. Most importantly, the fluorescence changes of the probe are remarkably specific for Al(3+) in the presence of other metal ions, which meet the selective requirements for practical application. Moreover, the experiment results show that the response behavior of 1 towards Al(3+) is pH independent in neutral condition (pH 6.0-8.0) and the response of the probe is fast (response time less than 3 min). In addition, the proposed probe has been used to detect Al(3+) in water samples and image Al(3+) in living cells with satisfying results. PMID:26320971
Sol-gel derived copper-doped silica glass as a sensitive material for X-ray beam dosimetry
NASA Astrophysics Data System (ADS)
Capoen, Bruno; Hamzaoui, Hicham El; Bouazaoui, Mohamed; Ouerdane, Youcef; Boukenter, Aziz; Girard, Sylvain; Marcandella, Claude; Duhamel, Olivier
2016-01-01
The light emission from a sol-gel-derived Cu-doped silica glass was studied under 10 keV X-ray irradiation using a fibered setup. Both radioluminescence (RL) and optically stimulated luminescence (OSL) were analyzed at different high dose rates up to 50 Gy/s and for different exposure times, yielding accumulated doses up to 50 kGy (in SiO2). Even if a darkening effect appears at this dose level, the material remains X-sensitive after exposure to several kGy. At low dose rate, the scintillation mechanisms are similar to photoluminescence, involving the Cu+ ions electronic levels, contrary to the nonlinear domain (for dose rates higher than 30 Gy/s). This RL, as well as the OSL, could be exploited in their linear domain to measure doses as high as 3 kGy. A thorough study of the OSL signal has shown that it must be employed with caution in order to take the fading phenomenon and the response dependency on stimulation source intensity into consideration.
NASA Technical Reports Server (NTRS)
Bartels, Robert E.
2011-01-01
Launch vehicles frequently experience a reduced stability margin through the transonic Mach number range. This reduced stability margin is caused by an undamping of the aerodynamics in one of the lower frequency flexible or rigid body modes. Analysis of the behavior of a flexible vehicle is routinely performed with quasi-steady aerodynamic lineloads derived from steady rigid computational fluid dynamics (CFD). However, a quasi-steady aeroelastic stability analysis can be unconservative at the critical Mach numbers where experiment or unsteady computational aeroelastic (CAE) analysis show a reduced or even negative aerodynamic damping. This paper will present a method of enhancing the quasi-steady aeroelastic stability analysis of a launch vehicle with unsteady aerodynamics. The enhanced formulation uses unsteady CFD to compute the response of selected lower frequency modes. The response is contained in a time history of the vehicle lineloads. A proper orthogonal decomposition of the unsteady aerodynamic lineload response is used to reduce the scale of data volume and system identification is used to derive the aerodynamic stiffness, damping and mass matrices. The results of the enhanced quasi-static aeroelastic stability analysis are compared with the damping and frequency computed from unsteady CAE analysis and from a quasi-steady analysis. The results show that incorporating unsteady aerodynamics in this way brings the enhanced quasi-steady aeroelastic stability analysis into close agreement with the unsteady CAE analysis.
Transonic Blunt Body Aerodynamic Coefficients Computation
NASA Astrophysics Data System (ADS)
Sancho, Jorge; Vargas, M.; Gonzalez, Ezequiel; Rodriguez, Manuel
2011-05-01
In the framework of EXPERT (European Experimental Re-entry Test-bed) accurate transonic aerodynamic coefficients are of paramount importance for the correct trajectory assessment and parachute deployment. A combined CFD (Computational Fluid Dynamics) modelling and experimental campaign strategy was selected to obtain accurate coefficients. A preliminary set of coefficients were obtained by CFD Euler inviscid computation. Then experimental campaign was performed at DNW facilities at NLR. A profound review of the CFD modelling was done lighten up by WTT results, aimed to obtain reliable values of the coefficients in the future (specially the pitching moment). Study includes different turbulence modelling and mesh sensitivity analysis. Comparison with the WTT results is explored, and lessons learnt are collected.
DSMC Simulations of Apollo Capsule Aerodynamics for Hypersonic Rarefied Conditions
NASA Technical Reports Server (NTRS)
Moss, James N.; Glass, Christopher E.; Greene, Francis A.
2006-01-01
Direct simulation Monte Carlo DSMC simulations are performed for the Apollo capsule in the hypersonic low density transitional flow regime. The focus is on ow conditions similar to that experienced by the Apollo Command Module during the high altitude portion of its reentry Results for aerodynamic forces and moments are presented that demonstrate their sensitivity to rarefaction that is for free molecular to continuum conditions. Also aerodynamic data are presented that shows their sensitivity to a range of reentry velocity encompasing conditions that include reentry from low Earth orbit lunar return and Mars return velocities to km/s. The rarefied results are anchored in the continuum regime with data from Navier Stokes simulations
Unsteady aerodynamic modeling and active aeroelastic control
NASA Technical Reports Server (NTRS)
Edwards, J. W.
1977-01-01
Unsteady aerodynamic modeling techniques are developed and applied to the study of active control of elastic vehicles. The problem of active control of a supercritical flutter mode poses a definite design goal stability, and is treated in detail. The transfer functions relating the arbitrary airfoil motions to the airloads are derived from the Laplace transforms of the linearized airload expressions for incompressible two dimensional flow. The transfer function relating the motions to the circulatory part of these loads is recognized as the Theodorsen function extended to complex values of reduced frequency, and is termed the generalized Theodorsen function. Inversion of the Laplace transforms yields exact transient airloads and airfoil motions. Exact root loci of aeroelastic modes are calculated, providing quantitative information regarding subcritical and supercritical flutter conditions.
Aerodynamics of a linear oscillating cascade
NASA Technical Reports Server (NTRS)
Buffum, Daniel H.; Fleeter, Sanford
1990-01-01
The steady and unsteady aerodynamics of a linear oscillating cascade are investigated using experimental and computational methods. Experiments are performed to quantify the torsion mode oscillating cascade aerodynamics of the NASA Lewis Transonic Oscillating Cascade for subsonic inlet flowfields using two methods: simultaneous oscillation of all the cascaded airfoils at various values of interblade phase angle, and the unsteady aerodynamic influence coefficient technique. Analysis of these data and correlation with classical linearized unsteady aerodynamic analysis predictions indicate that the wind tunnel walls enclosing the cascade have, in some cases, a detrimental effect on the cascade unsteady aerodynamics. An Euler code for oscillating cascade aerodynamics is modified to incorporate improved upstream and downstream boundary conditions and also the unsteady aerodynamic influence coefficient technique. The new boundary conditions are shown to improve the unsteady aerodynamic influence coefficient technique. The new boundary conditions are shown to improve the unsteady aerodynamic predictions of the code, and the computational unsteady aerodynamic influence coefficient technique is shown to be a viable alternative for calculation of oscillating cascade aerodynamics.
Tang, Rui; Xie, Zhirun; Zhou, Shujie; Zhang, Yanan; Yuan, Zhimin; Zhang, Luyuan; Yin, Longwei
2016-08-31
We present a facile hot injection and hydrothermal method to synthesize Cu2ZnSnS4 (CZTS) nanoparticles sensitized metal-organic frameworks (MOFs)-derived mesoporous TiO2. The MOFs-derived TiO2 inherits the large specific surface area and abundantly porous structures of the MOFs structure, which is of great benefit to effectively enhance the dye loading capacity, prolong the incident light traveling length by enhancing the multiple interparticle light-scattering process, and therefore improve the light absorption capacity. The sensitization of CZTS nanoparticles effectively enlarges the photoresponse range of TiO2 to the visible light region and facilitates photoinduced carrier transport. The formed heterostructure between CZTS nanoparticles and MOFs-derived TiO2 with matched band gap structure effectively suppresses the recombination rates of photogenerated electron/hole pairs and prolongs the lifespan of the carriers. Photoanodes based upon CZTS/MOFs-derived TiO2 photoanodes can achieve the maximal photocurrent of 17.27 mA cm(-2) and photoelectric conversion performance of 8.10%, nearly 1.93 and 2.21 times higher than those of TiO2-based photoanode. The related mechanism and model are investigated. The strikingly improved photoelectric properties are ascribed to a synergistic action between the MOFs-derived TiO2 and the sensitization of CZTS nanoparticles. PMID:27494761
Evaluation of thermographic phosphor technology for aerodynamic model testing
Cates, M.R.; Tobin, K.W.; Smith, D.B.
1990-08-01
The goal for this project was to perform technology evaluations applicable to the development of higher-precision, higher-temperature aerodynamic model testing at Arnold Engineering Development Center (AEDC) in Tullahmoa, Tennessee. With the advent of new programs for design of aerospace craft that fly at higher speeds and altitudes, requirements for detailed understanding of high-temperature materials become very important. Model testing is a natural and critical part of the development of these new initiatives. The well-established thermographic phosphor techniques of the Applied Technology Division at Oak Ridge National Laboratory are highly desirable for diagnostic evaluation of materials and aerodynamic shapes as studied in model tests. Combining this state-of-the-art thermographic technique with modern, higher-temperature models will greatly improve the practicability of tests for the advanced aerospace vehicles and will provide higher precision diagnostic information for quantitative evaluation of these tests. The wavelength ratio method for measuring surface temperatures of aerodynamic models was demonstrated in measurements made for this project. In particular, it was shown that the appropriate phosphors could be selected for the temperature range up to {approximately}700 {degree}F or higher and emission line ratios of sufficient sensitivity to measure temperature with 1% precision or better. Further, it was demonstrated that two-dimensional image- processing methods, using standard hardware, can be successfully applied to surface thermography of aerodynamic models for AEDC applications.
Cerezo, Javier; Avila Ferrer, Francisco J; Santoro, Fabrizio
2015-05-01
We simulate from first-principles the absorption spectra of five structure-related coumarin derivatives utilized in dye sensitized solar cells (DSSCs), investigating the vibronic and solvent contributions to the position and width of the spectra in ethanol. Ground and excited state potential energy surfaces (PESs) are modeled by Density Functional Theory (DFT) and its time-dependent (TD) expression for the excited state (TD-DFT). The solute vibronic structure associated with the spectrum is calculated by a TD formalism, accounting for both Duschinsky and temperature effects, while solvent inhomogeneous broadening is evaluated according to Marcus' theory, computing the solvent reorganization energy by the state-specific implementation of the polarizable continuum model (PCM) within TD-DFT. We adopted both the standard hybrid PBE0 and the range separated CAM-B3LYP functionals showing that the latter performs better both concerning the vibronic and solvent-induced contributions to the absorption lineshape. The different predictions of the two functionals are then rationalized in terms of the charge transfer (CT) character of the transitions showing that, in this class of compounds, it is strongly dependent on the nuclear structure. Such a dependence introduces a bias in the PBE0 PES that has a drastic impact on the vibronic spectra. We show that both the intrinsic vibronic structure and the solvent broadening play a relevant role in differentiating the absorption width of the five dyes. In this sense, our results provide a guide to understand the sources of spectral broadening of this family of dyes, a valuable help for a rational design of new molecules to improve DSSC devices. PMID:25848730
Zajdlik, Barry Alan
2016-04-01
The species sensitivity distribution (SSD) distribution approach to estimating water quality guidelines (WQGs) is the preferred method in all jurisdictions reviewed (Australia, Canada, New Zealand, Organisation for Economic Co-operation and Development [OECD] members, South Africa, United States) and is one of the recommended methods for European Commission members for 33 priority and priority hazardous substances. In the event that jurisdiction-specific criteria for data quality, quantity, and taxonomic representation are not met, all of these jurisdictions endorse the use of additional safety factors (SFs) applied to either the SSD-based WQG or, the lowest suitable toxicity test endpoint. In Canada, the British Columbia Ministry of Environment endorses this latter approach as the preferred approach in the belief that so-derived WQGs are more protective than SSD-based WQGs. The level of protection afforded by the latter SF approach was evaluated by statistically sampling minima from random samples of the following distributions: normal, Gumbel, logistic, and Weibull, using a range of coefficients of variation (cVs) and applying the SFs of 2 or 10 used in British Columbia. The simulations indicate that the potentially affected fraction of species (PAF) can be as high as 20%, or, approach 0%. The PAF varies with sample size and CV. Because CVs can vary systematically with mode of toxic action, the PAF using SF-based WQGs can also vary systematically with analyte class. The varying levels of protection afforded by SF-based WQGs are generally inconsistent with the common water quality management goal that allows for a small degree of change under long-term exposure. The findings suggest that further efforts be made to develop high-quality WQGs that support informed decision making and are consistent with the environmental management goal instead of using SFs in the hope of achieving an acceptable but unknown, degree of environmental protection. PMID:26272692
Magagnoli, C; Manetti, R; Fontana, M R; Giannelli, V; Giuliani, M M; Rappuoli, R; Pizza, M
1996-12-01
Heat-labile toxin (LT) is a protein related to cholera toxin, produced by enterotoxigenic Escherichia coli strains, that is organized as an AB5 complex. A number of nontoxic derivatives of LT, useful for new or improved vaccines against diarrheal diseases or as mucosal adjuvants, have been constructed by site-directed mutagenesis. Here we have studied the biochemical properties of the nontoxic mutants LT-K7 (Arg-7-->Lys), LT-D53 (Val-53-->Asp), LT-K63 (Ser-63-->Lys), LT-K97 (Val-97-->Lys), LT-K104 (Tyr-104-->Lys), LT-K114 (Ser-114-->Lys), and LT-K7/K97 (Arg-7-->Lys and Val-97-->Lys). We have found that mutations in the A subunit may have profound effects on the ability to form the AB5 structure and on the stability and trypsin sensitivity of the purified proteins. Unstable mutants, during long-term storage at 4 degrees C, showed a decrease in the amount of the assembled protein in solution and a parallel appearance of soluble monomeric B subunit. This finding suggests that the stability of the B pentamer is influenced by the A subunit which is associated with it. Among the seven nontoxic mutants tested, LT-K63 was found to be efficient in AB5 production, extremely stable during storage, resistant to proteolytic attack, and very immunogenic. In conclusion, LT-K63 is a good candidate for the development of antidiarrheal vaccines and mucosal adjuvants. PMID:8945604
A New Aerodynamic Data Dispersion Method for Launch Vehicle Design
NASA Technical Reports Server (NTRS)
Pinier, Jeremy T.
2011-01-01
A novel method for implementing aerodynamic data dispersion analysis is herein introduced. A general mathematical approach combined with physical modeling tailored to the aerodynamic quantity of interest enables the generation of more realistically relevant dispersed data and, in turn, more reasonable flight simulation results. The method simultaneously allows for the aerodynamic quantities and their derivatives to be dispersed given a set of non-arbitrary constraints, which stresses the controls model in more ways than with the traditional bias up or down of the nominal data within the uncertainty bounds. The adoption and implementation of this new method within the NASA Ares I Crew Launch Vehicle Project has resulted in significant increases in predicted roll control authority, and lowered the induced risks for flight test operations. One direct impact on launch vehicles is a reduced size for auxiliary control systems, and the possibility of an increased payload. This technique has the potential of being applied to problems in multiple areas where nominal data together with uncertainties are used to produce simulations using Monte Carlo type random sampling methods. It is recommended that a tailored physics-based dispersion model be delivered with any aerodynamic product that includes nominal data and uncertainties, in order to make flight simulations more realistic and allow for leaner spacecraft designs.
Computational Aerodynamic Simulations of a Spacecraft Cabin Ventilation Fan Design
NASA Technical Reports Server (NTRS)
Tweedt, Daniel L.
2010-01-01
Quieter working environments for astronauts are needed if future long-duration space exploration missions are to be safe and productive. Ventilation and payload cooling fans are known to be dominant sources of noise, with the International Space Station being a good case in point. To address this issue cost effectively, early attention to fan design, selection, and installation has been recommended, leading to an effort by NASA to examine the potential for small-fan noise reduction by improving fan aerodynamic design. As a preliminary part of that effort, the aerodynamics of a cabin ventilation fan designed by Hamilton Sundstrand has been simulated using computational fluid dynamics codes, and the computed solutions analyzed to quantify various aspects of the fan aerodynamics and performance. Four simulations were performed at the design rotational speed: two at the design flow rate and two at off-design flow rates. Following a brief discussion of the computational codes, various aerodynamic- and performance-related quantities derived from the computed flow fields are presented along with relevant flow field details. The results show that the computed fan performance is in generally good agreement with stated design goals.
Sensitivity Analysis of the Static Aeroelastic Response of a Wing
NASA Technical Reports Server (NTRS)
Eldred, Lloyd B.
1993-01-01
A technique to obtain the sensitivity of the static aeroelastic response of a three dimensional wing model is designed and implemented. The formulation is quite general and accepts any aerodynamic and structural analysis capability. A program to combine the discipline level, or local, sensitivities into global sensitivity derivatives is developed. A variety of representations of the wing pressure field are developed and tested to determine the most accurate and efficient scheme for representing the field outside of the aerodynamic code. Chebyshev polynomials are used to globally fit the pressure field. This approach had some difficulties in representing local variations in the field, so a variety of local interpolation polynomial pressure representations are also implemented. These panel based representations use a constant pressure value, a bilinearly interpolated value. or a biquadraticallv interpolated value. The interpolation polynomial approaches do an excellent job of reducing the numerical problems of the global approach for comparable computational effort. Regardless of the pressure representation used. sensitivity and response results with excellent accuracy have been produced for large integrated quantities such as wing tip deflection and trim angle of attack. The sensitivities of such things as individual generalized displacements have been found with fair accuracy. In general, accuracy is found to be proportional to the relative size of the derivatives to the quantity itself.
Shape sensitivity analysis of flutter response of a laminated wing
NASA Technical Reports Server (NTRS)
Bergen, Fred D.; Kapania, Rakesh K.
1988-01-01
A method is presented for calculating the shape sensitivity of a wing aeroelastic response with respect to changes in geometric shape. Yates' modified strip method is used in conjunction with Giles' equivalent plate analysis to predict the flutter speed, frequency, and reduced frequency of the wing. Three methods are used to calculate the sensitivity of the eigenvalue. The first method is purely a finite difference calculation of the eigenvalue derivative directly from the solution of the flutter problem corresponding to the two different values of the shape parameters. The second method uses an analytic expression for the eigenvalue sensitivities of a general complex matrix, where the derivatives of the aerodynamic, mass, and stiffness matrices are computed using a finite difference approximation. The third method also uses an analytic expression for the eigenvalue sensitivities, but the aerodynamic matrix is computed analytically. All three methods are found to be in good agreement with each other. The sensitivities of the eigenvalues were used to predict the flutter speed, frequency, and reduced frequency. These approximations were found to be in good agreement with those obtained using a complete reanalysis.
Missile autopilot design considering uncertainties in aerodynamics and actuator dynamics
NASA Astrophysics Data System (ADS)
Song, Yong D.; Hou, J.; Fogson, F.
2000-07-01
This work presents a method for missile autopilot design in the presence of actuator and uncertain dynamics. Nonlinear control algorithms are derived based on both missile aerodynamics and actuator dynamics. To account for system nonlinearities and uncertainties due to varying flight conditions, a memory-based compensation unit is developed and integrated into the strategy. Simulation on EMRAAT missile validates the effectiveness of the proposed control method.
Control of helicopter rotorblade aerodynamics
NASA Technical Reports Server (NTRS)
Fabunmi, James A.
1991-01-01
The results of a feasibility study of a method for controlling the aerodynamics of helicopter rotorblades using stacks of piezoelectric ceramic plates are presented. A resonant mechanism is proposed for the amplification of the displacements produced by the stack. This motion is then converted into linear displacement for the actuation of the servoflap of the blades. A design which emulates the actuation of the servoflap on the Kaman SH-2F is used to demonstrate the fact that such a system can be designed to produce the necessary forces and velocities needed to control the aerodynamics of the rotorblades of such a helicopter. Estimates of the electrical power requirements are also presented. A Small Business Innovation Research (SBIR) Phase 2 Program is suggested, whereby a bench-top prototype of the device can be built and tested. A collaborative effort between AEDAR Corporation and Kaman Aerospace Corporation is anticipated for future effort on this project.
Computer Simulation of Aircraft Aerodynamics
NASA Technical Reports Server (NTRS)
Inouye, Mamoru
1989-01-01
The role of Ames Research Center in conducting basic aerodynamics research through computer simulations is described. The computer facilities, including supercomputers and peripheral equipment that represent the state of the art, are described. The methodology of computational fluid dynamics is explained briefly. Fundamental studies of turbulence and transition are being pursued to understand these phenomena and to develop models that can be used in the solution of the Reynolds-averaged Navier-Stokes equations. Four applications of computer simulations for aerodynamics problems are described: subsonic flow around a fuselage at high angle of attack, subsonic flow through a turbine stator-rotor stage, transonic flow around a flexible swept wing, and transonic flow around a wing-body configuration that includes an inlet and a tail.
Viking entry aerodynamics and heating
NASA Technical Reports Server (NTRS)
Polutchko, R. J.
1974-01-01
The characteristics of the Mars entry including the mission sequence of events and associated spacecraft weights are described along with the Viking spacecraft. Test data are presented for the aerodynamic characteristics of the entry vehicle showing trimmed alpha, drag coefficient, and trimmed lift to drag ratio versus Mach number; the damping characteristics of the entry configuration; the angle of attack time history of Viking entries; stagnation heating and pressure time histories; and the aeroshell heating distribution as obtained in tests run in a shock tunnel for various gases. Flight tests which demonstrate the aerodynamic separation of the full-scale aeroshell and the flying qualities of the entry configuration in an uncontrolled mode are documented. Design values selected for the heat protection system based on the test data and analysis performed are presented.
Aerodynamic instability: A case history
NASA Technical Reports Server (NTRS)
Eisenmann, R. C.
1985-01-01
The identification, diagnosis, and final correction of complex machinery malfunctions typically require the correlation of many parameters such as mechanical construction, process influence, maintenance history, and vibration response characteristics. The progression is reviewed of field testing, diagnosis, and final correction of a specific machinery instability problem. The case history presented addresses a unique low frequency instability problem on a high pressure barrel compressor. The malfunction was eventually diagnosed as a fluidic mechanism that manifested as an aerodynamic disturbance to the rotor assembly.
Aerodynamic Design Using Neural Networks
NASA Technical Reports Server (NTRS)
Rai, Man Mohan; Madavan, Nateri K.
2003-01-01
The design of aerodynamic components of aircraft, such as wings or engines, involves a process of obtaining the most optimal component shape that can deliver the desired level of component performance, subject to various constraints, e.g., total weight or cost, that the component must satisfy. Aerodynamic design can thus be formulated as an optimization problem that involves the minimization of an objective function subject to constraints. A new aerodynamic design optimization procedure based on neural networks and response surface methodology (RSM) incorporates the advantages of both traditional RSM and neural networks. The procedure uses a strategy, denoted parameter-based partitioning of the design space, to construct a sequence of response surfaces based on both neural networks and polynomial fits to traverse the design space in search of the optimal solution. Some desirable characteristics of the new design optimization procedure include the ability to handle a variety of design objectives, easily impose constraints, and incorporate design guidelines and rules of thumb. It provides an infrastructure for variable fidelity analysis and reduces the cost of computation by using less-expensive, lower fidelity simulations in the early stages of the design evolution. The initial or starting design can be far from optimal. The procedure is easy and economical to use in large-dimensional design space and can be used to perform design tradeoff studies rapidly. Designs involving multiple disciplines can also be optimized. Some practical applications of the design procedure that have demonstrated some of its capabilities include the inverse design of an optimal turbine airfoil starting from a generic shape and the redesign of transonic turbines to improve their unsteady aerodynamic characteristics.
X-34 Vehicle Aerodynamic Characteristics
NASA Technical Reports Server (NTRS)
Brauckmann, Gregory J.
1998-01-01
The X-34, being designed and built by the Orbital Sciences Corporation, is an unmanned sub-orbital vehicle designed to be used as a flying test bed to demonstrate key vehicle and operational technologies applicable to future reusable launch vehicles. The X-34 will be air-launched from an L-1011 carrier aircraft at approximately Mach 0.7 and 38,000 feet altitude, where an onboard engine will accelerate the vehicle to speeds above Mach 7 and altitudes to 250,000 feet. An unpowered entry will follow, including an autonomous landing. The X-34 will demonstrate the ability to fly through inclement weather, land horizontally at a designated site, and have a rapid turn-around capability. A series of wind tunnel tests on scaled models was conducted in four facilities at the NASA Langley Research Center to determine the aerodynamic characteristics of the X-34. Analysis of these test results revealed that longitudinal trim could be achieved throughout the design trajectory. The maximum elevon deflection required to trim was only half of that available, leaving a margin for gust alleviation and aerodynamic coefficient uncertainty. Directional control can be achieved aerodynamically except at combined high Mach numbers and high angles of attack, where reaction control jets must be used. The X-34 landing speed, between 184 and 206 knots, is within the capabilities of the gear and tires, and the vehicle has sufficient rudder authority to control the required 30-knot crosswind.
NASA Technical Reports Server (NTRS)
Edquist, Karl T.
2006-01-01
Comparisons are made between the LAURA Navier-Stokes code and Viking Lander Capsule hypersonic aerodynamics data from ground and flight measurements. Wind tunnel data are available for a 3.48 percent scale model at Mach 6 and a 2.75 percent scale model at Mach 10.35, both under perfect gas air conditions. Viking Lander 1 aerodynamics flight data also exist from on-board instrumentation for velocities between 2900 and 4400 m/sec (Mach 14 to 23.3). LAURA flowfield solutions are obtained for the geometry as tested or flown, including sting effects at tunnel conditions and finite-rate chemistry effects in flight. Using the flight vehicle center-of-gravity location (trim angle approx. equals -11.1 deg), the computed trim angle at tunnel conditions is within 0.31 degrees of the angle derived from Mach 6 data and 0.13 degrees from the Mach 10.35 trim angle. LAURA Mach 6 trim lift and drag force coefficients are within 2 percent of measured data, and computed trim lift-to-drag ratio is within 4 percent of the data. Computed trim lift and drag force coefficients at Mach 10.35 are within 5 percent and 3 percent, respectively, of wind tunnel data. Computed trim lift-to-drag ratio is within 2 percent of the Mach 10.35 data. Using the nominal density profile and center-of-gravity location, LAURA trim angle at flight conditions is within 0.5 degrees of the total angle measured from on-board instrumentation. LAURA trim lift and drag force coefficients at flight conditions are within 7 and 5 percent, respectively, of the flight data. Computed trim lift-to-drag ratio is within 4 percent of the data. Computed aerodynamics sensitivities to center-of-gravity location, atmospheric density, and grid refinement are generally small. The results will enable a better estimate of aerodynamics uncertainties for future Mars entry vehicles where non-zero angle-of-attack is required.
Reuter, Hendrik; Gerlach, Silke; Spieker, Jochem; Ryan, Cindy; Bauch, Caroline; Mangez, Claire; Winkler, Petra; Landsiedel, Robert; Templier, Marie; Mignot, Aurelien; Gerberick, Frank; Wenck, Horst; Aeby, Pierre; Schepky, Andreas
2015-08-01
Allergic contact dermatitis is a delayed T-cell mediated allergic response associated with relevant social and economic impacts. Animal experiments (e.g. the local lymph node assay) are still supplying most of the data used to assess the sensitization potential of new chemicals. However, the 7th amendment to the EU Cosmetic Directive have introduced a testing ban for cosmetic ingredients after March 2013. We have developed and optimized a stable and reproducible in vitro protocol based on human peripheral blood monocyte derived dendritic cells to assess the sensitization potential of chemicals. To evaluate the transferability and the predictivity of this PBMDCs based test protocol, a ring study was organized with five laboratories using seven chemicals with a known sensitization potential (one none-sensitizer and six sensitizers, including one pro-hapten). The results indicated that this optimized test protocol could be successfully transferred to all participating laboratories and allowed a correct assessment of the sensitization potential of the tested set of chemicals. This should allow a wider acceptance of PBMDCs as a reliable test system for the detection of human skin sensitizers and the inclusion of this protocol in the toolbox of in vitro methods for the evaluation of the skin sensitization potential of chemicals. PMID:25868915
Guo, Ping; Ma, Ruimin; Guo, Lianshun; Yang, Linlin; Liu, Jifeng; Zhang, Xianxi; Pan, Xu; Dai, Songyuan
2010-11-01
Ten novel sensitizer candidates Ru2, Ru4, Ru5, Ru6, Ru7, Ru8, Ru9, Ru10, Ru11 and Ru12 derived from the sensitizers N3 and K8 were designed and studied using the density functional theory and time-dependent density functional theory calculations. The influences of the C=C double bonds between the carboxyl groups and the bipyridine ring as well as the numbers and positions of the -CN groups adjacent to the carboxyl groups on the properties of the sensitizer candidates were discussed. The energy levels and the spatial distributions of the frontier molecular orbitals as well as the electronic absorption spectra of these complexes were compared with those of N3 and K8. Ru10 and Ru7 were found promising to provide superior photon-to-current conversion efficiency to those of N3 and K8 in ruthenium complex sensitized solar cells. PMID:21036083
Dynamic stability of an aerodynamically efficient motorcycle
NASA Astrophysics Data System (ADS)
Sharma, Amrit; Limebeer, David J. N.
2012-08-01
Motorcycles exhibit two potentially dangerous oscillatory modes known as 'wobble' and 'weave'. The former is reminiscent of supermarket castor shimmy, while the latter is a low frequency 'fish-tailing' motion that involves a combination of rolling, yawing, steering and side-slipping motions. These unwanted dynamic features, which can occur when two-wheeled vehicles are operated at speed, have been studied extensively. The aim of this paper is to use mathematical analysis to identify important stability trends in the on-going design of a novel aerodynamically efficient motorcycle known as the ECOSSE Spirit ES1. A mathematical model of the ES1 is developed using a multi-body dynamics software package called VehicleSim [Anon, VehicleSim Lisp Reference Manual Version 1.0, Mechanical Simulation Corporation, 2008. Available at http://www.carsim.com]. This high-fidelity motorcycle model includes realistic tyre-road contact geometry, a comprehensive tyre model, tyre relaxation and a flexible frame. A parameter set representative of a modern high-performance machine and rider is used. Local stability is investigated via the eigenvalues of the linearised models that are associated with equilibrium points of interest. A comprehensive study of the effects of frame flexibilities, acceleration, aerodynamics and tyre variations is presented, and an optimal passive steering compensator is derived. It is shown that the traditional steering damper cannot be used to stabilise the ES1 over its entire operating speed range. A simple passive compensator, involving an inerter is proposed. Flexibility can be introduced deliberately into various chassis components to change the stability characteristics of the vehicle; the implications of this idea are studied.
Pellett, Sabine; Schwartz, Michael P.; Tepp, William H.; Josephson, Richard; Scherf, Jacob M.; Pier, Christina L.; Thomson, James A.; Murphy, William L.; Johnson, Eric A.
2015-01-01
Botulinum neurotoxin (BoNT) detection provides a useful model for validating cell-based neurotoxicity screening approaches, as sensitivity is dependent on functionally competent neurons and clear quantitative endpoints are available for correlating results to approved animal testing protocols. Here, human induced pluripotent stem cell (iPSC)-derived neuronal cells were cultured on chemically-defined poly(ethylene glycol) (PEG) hydrogels formed by “thiol-ene” photopolymerization and tested as a cell-based neurotoxicity assay by determining sensitivity to active BoNT/A1. BoNT/A1 sensitivity was comparable to the approved in vivo mouse bioassay for human iPSC-derived neurons and neural stem cells (iPSC-NSCs) cultured on PEG hydrogels or treated tissue culture polystyrene (TCP) surfaces. However, maximum sensitivity for BoNT detection was achieved two weeks earlier for iPSC-NSCs that were differentiated and matured on PEG hydrogels compared to TCP. Therefore, chemically-defined synthetic hydrogels offer benefits over standard platforms when optimizing culture conditions for cell-based screening and achieve sensitivities comparable to an approved animal testing protocol. PMID:26411797
Pellett, Sabine; Schwartz, Michael P; Tepp, William H; Josephson, Richard; Scherf, Jacob M; Pier, Christina L; Thomson, James A; Murphy, William L; Johnson, Eric A
2015-01-01
Botulinum neurotoxin (BoNT) detection provides a useful model for validating cell-based neurotoxicity screening approaches, as sensitivity is dependent on functionally competent neurons and clear quantitative endpoints are available for correlating results to approved animal testing protocols. Here, human induced pluripotent stem cell (iPSC)-derived neuronal cells were cultured on chemically-defined poly(ethylene glycol) (PEG) hydrogels formed by "thiol-ene" photopolymerization and tested as a cell-based neurotoxicity assay by determining sensitivity to active BoNT/A1. BoNT/A1 sensitivity was comparable to the approved in vivo mouse bioassay for human iPSC-derived neurons and neural stem cells (iPSC-NSCs) cultured on PEG hydrogels or treated tissue culture polystyrene (TCP) surfaces. However, maximum sensitivity for BoNT detection was achieved two weeks earlier for iPSC-NSCs that were differentiated and matured on PEG hydrogels compared to TCP. Therefore, chemically-defined synthetic hydrogels offer benefits over standard platforms when optimizing culture conditions for cell-based screening and achieve sensitivities comparable to an approved animal testing protocol. PMID:26411797
Hou, Jun; Zhao, Qianyuan; Wang, Peifang; Wang, Chao; Miao, Lingzhan; Feng, Chenglian
2016-07-01
An alternative method for species sensitivity distribution (SSD) that considers the interaction between species and the community importance is illustrated in this article. First, a food web based on the relationship between predator and prey was constructed, and the keystone indices of species were obtained based on the food web. Then, the probability density distribution of the sensitivity for each species was derived from all of the available endpoints of each species. Finally, the species sensitivity distribution for ecosystem was constructed by sampling a specific number of values from the probability density distribution of the sensitivity for each species. Data of copper toxicity to the aquatic organisms in Tai Lake were selected to derived site-specific water quality criteria (WQC). Ninety-seven endpoints of acute toxicity for 47 species and 188 endpoints of chronic toxicity for 29 species were included, and the acute and chronic WQC developed by keystone indices probabilistic species sensitivity distribution (K-PSSD) were 4.982 μg/L and 0.965 μg/L, respectively. Results showed that the aquatic organisms of Tai Lake might be underprotected. Compared with the SSD, the K-PSSD coped with the interactions between species, the community importance, and the intraspecies and interspecies variation more effectively and was better at depicting the tendency and information of raw data. The K-PSSD was especially applicable to site-specific WQC and provided an alternative or supplement to the SSD. PMID:26996916
Simulation on a car interior aerodynamic noise control based on statistical energy analysis
NASA Astrophysics Data System (ADS)
Chen, Xin; Wang, Dengfeng; Ma, Zhengdong
2012-09-01
How to simulate interior aerodynamic noise accurately is an important question of a car interior noise reduction. The unsteady aerodynamic pressure on body surfaces is proved to be the key effect factor of car interior aerodynamic noise control in high frequency on high speed. In this paper, a detail statistical energy analysis (SEA) model is built. And the vibra-acoustic power inputs are loaded on the model for the valid result of car interior noise analysis. The model is the solid foundation for further optimization on car interior noise control. After the most sensitive subsystems for the power contribution to car interior noise are pointed by SEA comprehensive analysis, the sound pressure level of car interior aerodynamic noise can be reduced by improving their sound and damping characteristics. The further vehicle testing results show that it is available to improve the interior acoustic performance by using detailed SEA model, which comprised by more than 80 subsystems, with the unsteady aerodynamic pressure calculation on body surfaces and the materials improvement of sound/damping properties. It is able to acquire more than 2 dB reduction on the central frequency in the spectrum over 800 Hz. The proposed optimization method can be looked as a reference of car interior aerodynamic noise control by the detail SEA model integrated unsteady computational fluid dynamics (CFD) and sensitivity analysis of acoustic contribution.
Blunt Body Aerodynamics for Hypersonic Low Density Flows
NASA Technical Reports Server (NTRS)
Moss, James N.; Glass, Christopher E.; Greene, Francis A.
2006-01-01
Numerical simulations are performed for the Apollo capsule from the hypersonic rarefied to the continuum regimes. The focus is on flow conditions similar to those experienced by the Apollo 6 Command Module during the high altitude portion of its reentry. The present focus is to highlight some of the current activities that serve as a precursor for computational tool assessments that will be used to support the development of aerodynamic data bases for future capsule flight environments, particularly those for the Crew Exploration Vehicle (CEV). Results for aerodynamic forces and moments are presented that demonstrate their sensitivity to rarefaction; that is, free molecular to continuum conditions. Also, aerodynamic data are presented that shows their sensitivity to a range of reentry velocities, encompassing conditions that include reentry from low Earth orbit, lunar return, and Mars return velocities (7.7 to 15 km/s). The rarefied results obtained with direct simulation Monte Carlo (DSMC) codes are anchored in the continuum regime with data from Navier-Stokes simulations.
The role of unsteady aerodynamics in aeroacoustics
NASA Technical Reports Server (NTRS)
Pao, S. Paul
1988-01-01
The role of acoustics and unsteady aerodynamics research in understanding the fundamental physics of time-dependent fluid phenomena is reviewed. The key issues are illustrated by considering the sound radiation of turbulent jets and the aeroacoustics of rotating bodies such as helicopter rotors. The importance of computational methods as a link between aerodynamics and acoustics is also discussed. It is noted that where acoustic analogy techniques are sufficiently accurate, unsteady aerodynamics can be used for acoustic prediction. In supersonic problems where acoustics and aerodynamics are coupled, an integrated nonlinear analysis can provide an accurate problem solution.
HIAD-2 (Hypersonic Inflatable Aerodynamic Decelerator)
The Hypersonic Inflatable Aerodynamic Decelerator (HIAD) project is a disruptive technology that will accommodate the atmospheric entry of heavy payloads to planetary bodies such as Mars. HIAD over...
Computational aerodynamics applications to transport aircraft design
NASA Technical Reports Server (NTRS)
Henne, P. A.
1983-01-01
Examples are cited in assessing the effect that computational aerodynamics has had on the design of transport aircraft. The application of computational potential flow methods to wing design and to high-lift system design is discussed. The benefits offered by computational aerodynamics in reducing design cost, time, and risk are shown to be substantial.These aerodynamic methods have proved to be particularly effective in exposing inferior or poor aerodynamic designs. Particular attention is given to wing design, where the results have been dramatic.
Muscoplat, C C; Setcavage, T M; Thoen, C O; Kim, Y B
1976-01-01
Addition of purified protein derivate (PPD) to suspension cultures of spleen cells from swine sensitized to Mycobacterium bovis and Mycobacterium avium resulted in marked enhancement of antisheep erythrocyte plaque-forming cells after stimulation with sheep erythrocytes. The enhancing effect appeared early in the response and was specific for the sensitizing antigen. The enhancing effect was dependent upon the presence of both sheep erythrocytes and PPD in the culture system. PPD had no effect in the absence of sheep erythrocytes. Addition of PPD to cells from nonsensitized animals did not produce any enhancing effect. PMID:797671
Printsevskaya, Svetlana S; Pavlov, Andrey Y; Olsufyeva, Evgenia N; Mirchink, Elena P; Isakova, Elena B; Reznikova, Marina I; Goldman, Robert C; Branstrom, Arthur A; Baizman, Eugene R; Longley, Clifford B; Sztaricskai, Ferenc; Batta, Gyula; Preobrazhenskaya, Maria N
2002-03-14
Des-(N-methyl-D-leucyl)eremomycin was obtained by Edman degradation of eremomycin. Derivatives with a hydrophobic substituent at the exterior of the molecule were then synthesized, and their antibacterial activities were compared with similar derivatives of eremomycin. Comparison of derivatives of eremomycin containing the n-decyl or p-(p-chlorophenyl)benzyl substituent in the eremosamine moiety (N') and n-decyl or p-(p-chlorophenyl)benzylamides with similar derivatives of eremomycin possessing the damaged peptide core (a defective binding pocket) showed that compounds of both types are almost equally active against glycopeptide-resistant strains of enterococci (GRE), whereas eremomycin derivatives are more active against staphylococci. Hydrophobic 7d-alkylaminomethylated derivatives of eremomycin (9, 10) demonstrated similar antibacterial properties. Since the basic mode of action of glycopeptide antibiotics involves binding to cell wall intermediates terminating in -D-Ala-D-Ala and this interaction is seriously decreased in the hexapeptide derivatives (lacking the critical N-methyl-D-leucine), we suggest that these hydrophobic derivatives may inhibit peptidoglycan synthesis in the absence of dipeptide binding. NMR binding experiments using Ac-D-Ala-D-Ala show that binding constants of these hexapeptide derivativies are decreased in comparison with the corresponding heptapeptides with intact binding pocket. This is in agreement with the decreased biological activity of the hexapeptide derivatives against vancomycin-sensitive strains in comparison with the activity of parent compounds. Binding to the lactate cell wall analogue Ac-D-Ala-D-Lac with decylamide of eremomycin 8 was not observed, demonstrating that the interaction with this target in GRE does not occur. While hydrophobic glycopeptide derivatives retain the ability to inhibit the synthesis of peptidoglycan in manner of natural glycopeptides, biochemical investigation supports the hypothesis that they
Aerodynamic optimization by simultaneously updating flow variables and design parameters
NASA Technical Reports Server (NTRS)
Rizk, M. H.
1990-01-01
The application of conventional optimization schemes to aerodynamic design problems leads to inner-outer iterative procedures that are very costly. An alternative approach is presented based on the idea of updating the flow variable iterative solutions and the design parameter iterative solutions simultaneously. Two schemes based on this idea are applied to problems of correcting wind tunnel wall interference and optimizing advanced propeller designs. The first of these schemes is applicable to a limited class of two-design-parameter problems with an equality constraint. It requires the computation of a single flow solution. The second scheme is suitable for application to general aerodynamic problems. It requires the computation of several flow solutions in parallel. In both schemes, the design parameters are updated as the iterative flow solutions evolve. Computations are performed to test the schemes' efficiency, accuracy, and sensitivity to variations in the computational parameters.
Aerodynamic Design on Unstructured Grids for Turbulent Flows
NASA Technical Reports Server (NTRS)
Anderson, W. Kyle; Bonhaus, Daryl L.
1997-01-01
An aerodynamic design algorithm for turbulent flows using unstructured grids is described. The current approach uses adjoint (costate) variables for obtaining derivatives of the cost function. The solution of the adjoint equations is obtained using an implicit formulation in which the turbulence model is fully coupled with the flow equations when solving for the costate variables. The accuracy of the derivatives is demonstrated by comparison with finite-difference gradients and a few example computations are shown. In addition, a user interface is described which significantly reduces the time required for setting up the design problems. Recommendations on directions of further research into the Navier Stokes design process are made.
Micro air vehicle motion tracking and aerodynamic modeling
NASA Astrophysics Data System (ADS)
Uhlig, Daniel V.
Aerodynamic performance of small-scale fixed-wing flight is not well understood, and flight data are needed to gain a better understanding of the aerodynamics of micro air vehicles (MAVs) flying at Reynolds numbers between 10,000 and 30,000. Experimental studies have shown the aerodynamic effects of low Reynolds number flow on wings and airfoils, but the amount of work that has been conducted is not extensive and mostly limited to tests in wind and water tunnels. In addition to wind and water tunnel testing, flight characteristics of aircraft can be gathered through flight testing. The small size and low weight of MAVs prevent the use of conventional on-board instrumentation systems, but motion tracking systems that use off-board triangulation can capture flight trajectories (position and attitude) of MAVs with minimal onboard instrumentation. Because captured motion trajectories include minute noise that depends on the aircraft size, the trajectory results were verified in this work using repeatability tests. From the captured glide trajectories, the aerodynamic characteristics of five unpowered aircraft were determined. Test results for the five MAVs showed the forces and moments acting on the aircraft throughout the test flights. In addition, the airspeed, angle of attack, and sideslip angle were also determined from the trajectories. Results for low angles of attack (less than approximately 20 deg) showed the lift, drag, and moment coefficients during nominal gliding flight. For the lift curve, the results showed a linear curve until stall that was generally less than finite wing predictions. The drag curve was well described by a polar. The moment coefficients during the gliding flights were used to determine longitudinal and lateral stability derivatives. The neutral point, weather-vane stability and the dihedral effect showed some variation with different trim speeds (different angles of attack). In the gliding flights, the aerodynamic characteristics
General Theory of Aerodynamic Instability and the Mechanism of Flutter
NASA Technical Reports Server (NTRS)
Theodorsen, Theodore
1979-01-01
The aerodynamic forces on an oscillating airfoil or airfoil-aileron combination of three independent degrees of freedom were determined. The problem resolves itself into the solution of certain definite integrals, which were identified as Bessel functions of the first and second kind, and of zero and first order. The theory, based on potential flow and the Kutta condition, is fundamentally equivalent to the conventional wing section theory relating to the steady case. The air forces being known, the mechanism of aerodynamic instability was analyzed. An exact solution, involving potential flow and the adoption of the Kutta condition, was derived. The solution is of a simple form and is expressed by means of an auxiliary parameter k. The flutter velocity, treated as the unknown quantity, was determined as a function of a certain ratio of the frequencies in the separate degrees of freedom for any magnitudes and combinations of the airfoil-aileron parameters.
Aerodynamic preliminary analysis system. Part 1: Theory. [linearized potential theory
NASA Technical Reports Server (NTRS)
Bonner, E.; Clever, W.; Dunn, K.
1978-01-01
A comprehensive aerodynamic analysis program based on linearized potential theory is described. The solution treats thickness and attitude problems at subsonic and supersonic speeds. Three dimensional configurations with or without jet flaps having multiple non-planar surfaces of arbitrary planform and open or closed slender bodies of non-circular contour may be analyzed. Longitudinal and lateral-directional static and rotary derivative solutions may be generated. The analysis was implemented on a time sharing system in conjunction with an input tablet digitizer and an interactive graphics input/output display and editing terminal to maximize its responsiveness to the preliminary analysis problem. Nominal case computation time of 45 CPU seconds on the CDC 175 for a 200 panel simulation indicates the program provides an efficient analysis for systematically performing various aerodynamic configuration tradeoff and evaluation studies.
The aerodynamic analysis of the gyroplane rotating-wing system
NASA Technical Reports Server (NTRS)
Wheatley, John B
1934-01-01
An aerodynamic analysis of the gyroplane rotating-wing system is presented herein. This system consists of a freely rotating rotor in which opposite blades are rigidly connected and allowed to rotate or feather freely about their span axis. Equations have been derived for the lift, the lift-drag ratio, the angle of attack, the feathering angles, and the rolling and pitching moments of a gyroplane rotor in terms of its basic parameters. Curves of lift-drag ratio against lift coefficient have been calculated for a typical case, showing the effect of varying the pitch angle, the solidarity, and the average blade-section drag coefficient. The analysis expresses satisfactorily the qualitative relations between the rotor characteristics and the rotor parameters. As disclosed by this investigation, the aerodynamic principles of the gyroplane are sound, and further research on this wing system is justified.
Progress in computational unsteady aerodynamics
NASA Technical Reports Server (NTRS)
Obayashi, Shigeru
1993-01-01
After vigorous development for over twenty years, Computational Fluid Dynamics (CFD) in the field of aerospace engineering has arrived at a turning point toward maturity. This paper discusses issues related to algorithm development for the Euler/Navier Stokes equations, code validation and recent applications of CFD for unsteady aerodynamics. Algorithm development is a fundamental element for a good CFD program. Code validation tries to bridge the reliability gap between CFD and experiment. Many of the recent applications also take a multidisciplinary approach, which is a future trend for CFD applications. As computers become more affordable, CFD is expected to be a better scientific and engineering tool.
Simulation of iced wing aerodynamics
NASA Technical Reports Server (NTRS)
Potapczuk, M. G.; Bragg, M. B.; Kwon, O. J.; Sankar, L. N.
1991-01-01
The sectional and total aerodynamic load characteristics of moderate aspect ratio wings with and without simulated glaze leading edge ice were studied both computationally, using a three dimensional, compressible Navier-Stokes solver, and experimentally. The wing has an untwisted, untapered planform shape with NACA 0012 airfoil section. The wing has an unswept and swept configuration with aspect ratios of 4.06 and 5.0. Comparisons of computed surface pressures and sectional loads with experimental data for identical configurations are given. The abrupt decrease in stall angle of attack for the wing, as a result of the leading edge ice formation, was demonstrated numerically and experimentally.
Aerodynamics. [Numerical simulation using supercomputers
Graves, R.A. Jr.
1988-01-01
A projection is made of likely improvements in the economics of commercial aircraft operation due to developments in aerodynamics in the next half-century. Notable among these improvements are active laminar flow control techniques' application to third-generation SSTs, in order to achieve an L/D value of about 20; this is comparable to current subsonic transports, and has the further consequence of reducing cabin noise. Wave-cancellation systems may also be used to eliminate sonic boom overpressures, and rapid-combustion systems may be able to eliminate all pollutants from jet exhausts other than CO/sub 2/.
Aerodynamic applications of infrared thermography
NASA Technical Reports Server (NTRS)
Daryabeigi, Kamran; Alderfer, David W.
1989-01-01
A series of wind tunnel experiments were conducted as part of a systematic study for evaluation of infrared thermography as a viable non-intrusive thermal measurement technique for aerodynamic applications. The experiments consisted of obtaining steady-state surface temperature and convective heat transfer rates for a uniformly heated cylinder in transverse flow with a Reynolds number range of 46,000 to 250,000. The calculated convective heat transfer rates were in general agreement with classical data. Furthermore, IR thermography provided valuable real-time fluid dynamic information such as visualization of flow separation, transition and vortices.
Cong, Weitao; Zhou, Ayi; Liu, Zhiguo; Shen, Jiayi; Zhou, Xuan; Ye, Weijian; Zhu, Zhongxin; Zhu, Xinliang; Lin, Jianjun; Jin, Litai
2015-02-01
A new hydrazide derivative was synthesized and used for the first time as a specific, brief, and economical probe to selectively visualize glycoproteins in 1-D and 2-D sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) with high sensitivity. The detection limit of the newly developed staining method is 2- and 4-fold higher than that of the widely used Pro-Q Emerald 300 and 488 stains, respectively. PMID:25565298
Introduction to Generalized Functions with Applications in Aerodynamics and Aeroacoustics
NASA Technical Reports Server (NTRS)
Farassat, F.
1994-01-01
Generalized functions have many applications in science and engineering. One useful aspect is that discontinuous functions can be handled as easily as continuous or differentiable functions and provide a powerful tool in formulating and solving many problems of aerodynamics and acoustics. Furthermore, generalized function theory elucidates and unifies many ad hoc mathematical approaches used by engineers and scientists. We define generalized functions as continuous linear functionals on the space of infinitely differentiable functions with compact support, then introduce the concept of generalized differentiation. Generalized differentiation is the most important concept in generalized function theory and the applications we present utilize mainly this concept. First, some results of classical analysis, are derived with the generalized function theory. Other applications of the generalized function theory in aerodynamics discussed here are the derivations of general transport theorems for deriving governing equations of fluid mechanics, the interpretation of the finite part of divergent integrals, the derivation of the Oswatitsch integral equation of transonic flow, and the analysis of velocity field discontinuities as sources of vorticity. Applications in aeroacoustics include the derivation of the Kirchhoff formula for moving surfaces, the noise from moving surfaces, and shock noise source strength based on the Ffowcs Williams-Hawkings equation.
Hines, K.L.; Bates, J.N.; Fisher, R.A. )
1991-03-11
Recent studies in the authors laboratory demonstrated that infusion of antigen into perfused livers from sensitized rats produces increases in hepatic portal pressure, increases in hepatic glucose output and decreases in hepatic oxygen consumption. In the present study, effects of NO on these hepatic responses to antigen challenge were investigated. Infusion of NO into perfused livers from sensitized rats attenuated ovalbumin induced increases in hepatic portal pressure and glucose output approximately 85% and 90%, respectively, and abolished ovalbumin-induced decreases in hepatic oxygen consumption. The duration of ovalbumin-stimulated increases in hepatic portal pressure was reduced nearly 90% by NO. Similarly, infusion of NO into perfused livers from sensitized rats inhibited increases in hepatic portal pressure and glucose output in response to platelet-activating factor (PAF) nearly 80 and 90%, respectively. In contrast, NO inhibited completely hepatic vasoconstriction in response to phenylephrine without altering glycogenolytic responses to this {alpha}-adrenergic agonist. These results provide evidence for regulatory effects of NO on hemodynamic and glycogenolytic responses to antigen in perfused livers from sensitized rats. These observations support previous findings which suggest that hepatic responses to sensitizing antigen may be mediated by PAF or other autacoid mediators which stimulate glycogenolysis in liver by indirect mechanisms involving hepatic vasoconstriction.
X-33 Hypersonic Aerodynamic Characteristics
NASA Technical Reports Server (NTRS)
Murphy, Kelly J.; Nowak, Robert J.; Thompson, Richard A.; Hollis, Brian R.; Prabhu, Ramadas K.
1999-01-01
Lockheed Martin Skunk Works, under a cooperative agreement with NASA, will design, build, and fly the X-33, a half-scale prototype of a rocket-based, single-stage-to-orbit (SSTO), reusable launch vehicle (RLV). A 0.007-scale model of the X-33 604BOO02G configuration was tested in four hypersonic facilities at the NASA Langley Research Center to examine vehicle stability and control characteristics and to populate the aerodynamic flight database for the hypersonic regime. The vehicle was found to be longitudinally controllable with less than half of the total body flap deflection capability across the angle of attack range at both Mach 6 and Mach 10. Al these Mach numbers, the vehicle also was shown to be longitudinally stable or neutrally stable for typical (greater than 20 degrees) hypersonic flight attitudes. This configuration was directionally unstable and the use of reaction control jets (RCS) will be necessary to control the vehicle at high angles of attack in the hypersonic flight regime. Mach number and real gas effects on longitudinal aerodynamics were shown to be small relative to X-33 control authority.
X-33 Hypersonic Aerodynamic Characteristics
NASA Technical Reports Server (NTRS)
Murphy, Kelly J.; Nowak, Robert J.; Thompson, Richard A.; Hollis, Brian R.; Prabhu, Ramadas K.
1999-01-01
Lockheed Martin Skunk Works, under a cooperative agreement with NASA, will build and fly the X-33, a half-scale prototype of a rocket-based, single-stage-to-orbit (SSTO), reusable launch vehicle (RLV). A 0.007-scale model of the X-33 604B0002G configuration was tested in four hypersonic facilities at the NASA Langley Research Center to examine vehicle stability and control characteristics and to populate an aerodynamic flight database in the hypersonic regime. The vehicle was found to be longitudinally controllable with less than half of the total body flap deflection capability across the angle of attack range at both Mach 6 and Mach 10. At these Mach numbers, the vehicle also was shown to be longitudinally stable or neutrally stable for typical (greater than 20 degrees) hypersonic flight attitudes. This configuration was directionally unstable and the use of reaction control jets (RCS) will be necessary to control the vehicle at high angles of attack in the hypersonic flight regime. Mach number and real gas effects on longitudinal aerodynamics were shown to be small relative to X-33 control authority.
X-33 Hypersonic Aerodynamic Characteristics
NASA Technical Reports Server (NTRS)
Murphy, Kelly J.; Nowak, Robert J.; Thompson, Richard A.; Hollis, Brian R.; Prabhu, Ramadas K.
1999-01-01
Lockheed Martin Skunk Works, under a cooperative agreement with NASA, will build and fly the X-33, a half-scale prototype of a rocket-based, single-stage-to-orbit (SSTO), reusable launch vehicle (RLV). A 0.007-scale model of the X-33 604B0002G configuration was tested in four hypersonic facilities at the NASA Langley Research Center to examine vehicle stability and control characteristics and to populate an aerodynamic flight database i n the hypersonic regime. The vehicle was found to be longitudinally controllable with less than half of the total body flap deflection capability across the angle of attack range at both Mach 6 and Mach 10. At these Mach numbers, the vehicle also was shown to be longitudinally stable or neutrally stable for typical (greater than 20 degrees) hypersonic flight attitudes. This configuration was directionally unstable and the use of reaction control jets (RCS) will be necessary to control the vehicle at high angles of attack in the hypersonic flight regime. Mach number and real gas effects on longitudinal aerodynamics were shown to be small relative to X-33 control authority.
X-33 Hypersonic Aerodynamic Characteristics
NASA Technical Reports Server (NTRS)
Murphy, Kelly J.; Nowak, Robert J.; Thompson, Richard A.; Hollis, Brian R.; Prabhu, Ramadas K.
1999-01-01
Lockheed Martin Skunk Works, under a cooperative agreement with NASA, will build and fly the X-33, a half-scale prototype of a rocket-based, single-stage-to-orbit (SSTO), reusable launch vehicle (RLV). A 0.007-scale model of the X-33 604B0002G configuration was tested in four hypersonic facilities at the NASA Langley Research Center to examine vehicle stability and control characteristics and to populate an aerodynamic flight database in the hypersonic regime, The vehicle was found to be longitudinally controllable with less than half of the total body flap deflection capability across the angle of attack range at both Mach 6 and Mach 10. At these Mach numbers, the vehicle also was shown to be longitudinally stable or neutrally stable for typical (greater than 20 degrees) hypersonic flight attitudes. This configuration was directionally unstable and the use of reaction control jets (RCS) will be necessary to control the vehicle at high angles of attack in the hypersonic flight regime. Mach number and real gas effects on longitudinal aerodynamics were shown to be small relative to X-33 control authority.
Liu, Yan; Gong, Xuedong; Wang, Lianjun; Wang, Guixiang; Xiao, Heming
2011-03-10
To look for superior and safe high energy density compounds (HEDCs), 2,2',4,4',6,6'-hexanitroazobenzene (HNAB) and its -NO(2), -NH(2), -CN, -NC, -ONO(2), -N(3), or -NF(2) derivatives were studied at the B3LYP/6-31G* level of density functional theory (DFT). The isodesmic reactions were applied to calculate the heats of formation (HOFs) for these compounds. The theoretical molecular density (ρ), detonation energy (E(d)), detonation pressure (P), and detonation velocity (D), estimated using the Kamlet-Jacobs equations, showed that the detonation properties of these compounds were excellent. The effects of substituent groups on HOF, ρ, E(d), P, and D were studied. The order of contribution of the substituent groups to P and D was -NF(2) > -ONO(2) > -NO(2) > -N(3) > -NH(2). Sensitivity was evaluated using the nitro group charges, frontier orbital energies, and bond dissociation enthalpies (BDEs). The trigger bonds in the pyrolysis process for all these HNAB derivatives may be Ring-NO(2), Ring-N═N, Ring-NF(2), or O-NO(2) varying with the attachment of different substituents. BDEs of trigger bonds except those of -ONO(2) derivatives are relatively large, which means these compounds suffice the stability request of explosives. Taking both detonation properties and sensitivities into consideration, some -NF(2) and -NO(2) derivatives may be potential candidates for HEDCs. PMID:21314160
Distributed Aerodynamic Sensing and Processing Toolbox
NASA Technical Reports Server (NTRS)
Brenner, Martin; Jutte, Christine; Mangalam, Arun
2011-01-01
A Distributed Aerodynamic Sensing and Processing (DASP) toolbox was designed and fabricated for flight test applications with an Aerostructures Test Wing (ATW) mounted under the fuselage of an F-15B on the Flight Test Fixture (FTF). DASP monitors and processes the aerodynamics with the structural dynamics using nonintrusive, surface-mounted, hot-film sensing. This aerodynamic measurement tool benefits programs devoted to static/dynamic load alleviation, body freedom flutter suppression, buffet control, improvement of aerodynamic efficiency through cruise control, supersonic wave drag reduction through shock control, etc. This DASP toolbox measures local and global unsteady aerodynamic load distribution with distributed sensing. It determines correlation between aerodynamic observables (aero forces) and structural dynamics, and allows control authority increase through aeroelastic shaping and active flow control. It offers improvements in flutter suppression and, in particular, body freedom flutter suppression, as well as aerodynamic performance of wings for increased range/endurance of manned/ unmanned flight vehicles. Other improvements include inlet performance with closed-loop active flow control, and development and validation of advanced analytical and computational tools for unsteady aerodynamics.
Aerodynamic design on high-speed trains
NASA Astrophysics Data System (ADS)
Ding, San-San; Li, Qiang; Tian, Ai-Qin; Du, Jian; Liu, Jia-Li
2016-01-01
Compared with the traditional train, the operational speed of the high-speed train has largely improved, and the dynamic environment of the train has changed from one of mechanical domination to one of aerodynamic domination. The aerodynamic problem has become the key technological challenge of high-speed trains and significantly affects the economy, environment, safety, and comfort. In this paper, the relationships among the aerodynamic design principle, aerodynamic performance indexes, and design variables are first studied, and the research methods of train aerodynamics are proposed, including numerical simulation, a reduced-scale test, and a full-scale test. Technological schemes of train aerodynamics involve the optimization design of the streamlined head and the smooth design of the body surface. Optimization design of the streamlined head includes conception design, project design, numerical simulation, and a reduced-scale test. Smooth design of the body surface is mainly used for the key parts, such as electric-current collecting system, wheel truck compartment, and windshield. The aerodynamic design method established in this paper has been successfully applied to various high-speed trains (CRH380A, CRH380AM, CRH6, CRH2G, and the Standard electric multiple unit (EMU)) that have met expected design objectives. The research results can provide an effective guideline for the aerodynamic design of high-speed trains.
The aerodynamics of small Reynolds numbers
NASA Technical Reports Server (NTRS)
Schmitz, F. W.
1980-01-01
Aerodynamic characteristics of wing model gliders and bird wings in particular are discussed. Wind tunnel measurements and aerodynamics of small Reynolds numbers are enumerated. Airfoil behavior in the critical transition from laminar to turbulent boundary layer, which is more important to bird wing models than to large airplanes, was observed. Experimental results are provided, and an artificial bird wing is described.
Future Computer Requirements for Computational Aerodynamics
NASA Technical Reports Server (NTRS)
1978-01-01
Recent advances in computational aerodynamics are discussed as well as motivations for and potential benefits of a National Aerodynamic Simulation Facility having the capability to solve fluid dynamic equations at speeds two to three orders of magnitude faster than presently possible with general computers. Two contracted efforts to define processor architectures for such a facility are summarized.
Aerodynamic seal assemblies for turbo-machinery
Bidkar, Rahul Anil; Wolfe, Christopher; Fang, Biao
2015-09-29
The present application provides an aerodynamic seal assembly for use with a turbo-machine. The aerodynamic seal assembly may include a number of springs, a shoe connected to the springs, and a secondary seal positioned about the springs and the shoe.
Aerodynamic design on high-speed trains
NASA Astrophysics Data System (ADS)
Ding, San-San; Li, Qiang; Tian, Ai-Qin; Du, Jian; Liu, Jia-Li
2016-04-01
Compared with the traditional train, the operational speed of the high-speed train has largely improved, and the dynamic environment of the train has changed from one of mechanical domination to one of aerodynamic domination. The aerodynamic problem has become the key technological challenge of high-speed trains and significantly affects the economy, environment, safety, and comfort. In this paper, the relationships among the aerodynamic design principle, aerodynamic performance indexes, and design variables are first studied, and the research methods of train aerodynamics are proposed, including numerical simulation, a reduced-scale test, and a full-scale test. Technological schemes of train aerodynamics involve the optimization design of the streamlined head and the smooth design of the body surface. Optimization design of the streamlined head includes conception design, project design, numerical simulation, and a reduced-scale test. Smooth design of the body surface is mainly used for the key parts, such as electric-current collecting system, wheel truck compartment, and windshield. The aerodynamic design method established in this paper has been successfully applied to various high-speed trains (CRH380A, CRH380AM, CRH6, CRH2G, and the Standard electric multiple unit (EMU)) that have met expected design objectives. The research results can provide an effective guideline for the aerodynamic design of high-speed trains.
Review of aerodynamic design in the Netherlands
NASA Technical Reports Server (NTRS)
Labrujere, Th. E.
1991-01-01
Aerodynamic design activities in the Netherlands, which take place mainly at Fokker, the National Aerospace Laboratory (NLR), and Delft University of Technology (TUD), are discussed. The survey concentrates on the development of the Fokker 100 wing, glider design at TUD, and research at NLR in the field of aerodynamic design. Results are shown to illustrate these activities.
Python, Francois; Goebel, Carsten; Aeby, Pierre
2009-09-15
The number of studies involved in the development of in vitro skin sensitization tests has increased since the adoption of the EU 7th amendment to the cosmetics directive proposing to ban animal testing for cosmetic ingredients by 2013. Several studies have recently demonstrated that sensitizers induce a relevant up-regulation of activation markers such as CD86, CD54, IL-8 or IL-1{beta} in human myeloid cell lines (e.g., U937, MUTZ-3, THP-1) or in human peripheral blood monocyte-derived dendritic cells (PBMDCs). The present study aimed at the identification of new dendritic cell activation markers in order to further improve the in vitro evaluation of the sensitizing potential of chemicals. We have compared the gene expression profiles of PBMDCs and the human cell line MUTZ-3 after a 24-h exposure to the moderate sensitizer cinnamaldehyde. A list of 80 genes modulated in both cell types was obtained and a set of candidate marker genes was selected for further analysis. Cells were exposed to selected sensitizers and non-sensitizers for 24 h and gene expression was analyzed by quantitative real-time reverse transcriptase-polymerase chain reaction. Results indicated that PIR, TRIM16 and two Nrf2-regulated genes, CES1 and NQO1, are modulated by most sensitizers. Up-regulation of these genes could also be observed in our recently published DC-activation test with U937 cells. Due to their role in DC activation, these new genes may help to further refine the in vitro approaches for the screening of the sensitizing properties of a chemical.
The compressible aerodynamics of rotating blades based on an acoustic formulation
NASA Technical Reports Server (NTRS)
Long, L. N.
1983-01-01
An acoustic formula derived for the calculation of the noise of moving bodies is applied to aerodynamic problems. The acoustic formulation is a time domain result suitable for slender wings and bodies moving at subsonic speeds. A singular integral equation is derived in terms of the surface pressure which must then be solved numerically for aerodynamic purposes. However, as the 'observer' is moved onto the body surface, the divergent integrals in the acoustic formulation are semiconvergent. The procedure for regularization (or taking principal values of divergent integrals) is explained, and some numerical examples for ellipsoids, wings, and lifting rotors are presented. The numerical results show good agreement with available measured surface pressure data.
Aerodynamic effects of flexibility in flapping wings
Zhao, Liang; Huang, Qingfeng; Deng, Xinyan; Sane, Sanjay P.
2010-01-01
Recent work on the aerodynamics of flapping flight reveals fundamental differences in the mechanisms of aerodynamic force generation between fixed and flapping wings. When fixed wings translate at high angles of attack, they periodically generate and shed leading and trailing edge vortices as reflected in their fluctuating aerodynamic force traces and associated flow visualization. In contrast, wings flapping at high angles of attack generate stable leading edge vorticity, which persists throughout the duration of the stroke and enhances mean aerodynamic forces. Here, we show that aerodynamic forces can be controlled by altering the trailing edge flexibility of a flapping wing. We used a dynamically scaled mechanical model of flapping flight (Re ≈ 2000) to measure the aerodynamic forces on flapping wings of variable flexural stiffness (EI). For low to medium angles of attack, as flexibility of the wing increases, its ability to generate aerodynamic forces decreases monotonically but its lift-to-drag ratios remain approximately constant. The instantaneous force traces reveal no major differences in the underlying modes of force generation for flexible and rigid wings, but the magnitude of force, the angle of net force vector and centre of pressure all vary systematically with wing flexibility. Even a rudimentary framework of wing veins is sufficient to restore the ability of flexible wings to generate forces at near-rigid values. Thus, the magnitude of force generation can be controlled by modulating the trailing edge flexibility and thereby controlling the magnitude of the leading edge vorticity. To characterize this, we have generated a detailed database of aerodynamic forces as a function of several variables including material properties, kinematics, aerodynamic forces and centre of pressure, which can also be used to help validate computational models of aeroelastic flapping wings. These experiments will also be useful for wing design for small robotic
NASA Technical Reports Server (NTRS)
Ghaffari, Farhad
1999-01-01
Unstructured grid Euler computations, performed at supersonic cruise speed, are presented for a High Speed Civil Transport (HSCT) configuration, designated as the Technology Concept Airplane (TCA) within the High Speed Research (HSR) Program. The numerical results are obtained for the complete TCA cruise configuration which includes the wing, fuselage, empennage, diverters, and flow through nacelles at M (sub infinity) = 2.4 for a range of angles-of-attack and sideslip. Although all the present computations are performed for the complete TCA configuration, appropriate assumptions derived from the fundamental supersonic aerodynamic principles have been made to extract aerodynamic predictions to complement the experimental data obtained from a 1.675%-scaled truncated (aft fuselage/empennage components removed) TCA model. The validity of the computational results, derived from the latter assumptions, are thoroughly addressed and discussed in detail. The computed surface and off-surface flow characteristics are analyzed and the pressure coefficient contours on the wing lower surface are shown to correlate reasonably well with the available pressure sensitive paint results, particularly, for the complex flow structures around the nacelles. The predicted longitudinal and lateral/directional performance characteristics for the truncated TCA configuration are shown to correlate very well with the corresponding wind-tunnel data across the examined range of angles-of-attack and sideslip. The complementary computational results for the longitudinal and lateral/directional performance characteristics for the complete TCA configuration are also presented along with the aerodynamic effects due to empennage components. Results are also presented to assess the computational method performance, solution sensitivity to grid refinement, and solution convergence characteristics.
NASA Astrophysics Data System (ADS)
Nakahara, Hisashi; Emoto, Kentaro
2016-08-01
Recently, coda-wave interferometry has been used to monitor temporal changes in subsurface structures. Seismic velocity changes have been detected by coda-wave interferometry in association with large earthquakes and volcanic eruptions. To constrain the spatial extent of the velocity changes, spatial homogeneity is often assumed. However, it is important to locate the region of the velocity changes correctly to understand physical mechanisms causing them. In this paper, we are concerned with the sensitivity kernels relating travel times of coda waves to velocity changes. In previous studies, sensitivity kernels have been formulated for two-dimensional single scattering and multiple scattering, three-dimensional multiple scattering, and diffusion. In this paper, we formulate and derive analytical expressions of the sensitivity kernels for three-dimensional single-scattering case. These sensitivity kernels show two peaks at both source and receiver locations, which is similar to the previous studies using different scattering models. The two peaks are more pronounced for later lapse time. We validate our formulation by comparing it with finite-difference simulations of acoustic wave propagation. Our formulation enables us to evaluate the sensitivity kernels analytically, which is particularly useful for the analysis of body waves from deeper earthquakes.
Unsteady aerodynamics and flow control for flapping wing flyers
NASA Astrophysics Data System (ADS)
Ho, Steven; Nassef, Hany; Pornsinsirirak, Nick; Tai, Yu-Chong; Ho, Chih-Ming
2003-11-01
variation to achieve active flow control for MAVs. Finally, an explanation for aerodynamic gains seen in flexible versus rigid membrane wings, derived from an unsteady three-dimensional computational fluid dynamics model with an integrated distributed control algorithm, is presented.
NASA Technical Reports Server (NTRS)
Abdol-Hamid, Khaled S.; Ghaffari, Farhad
2011-01-01
Numerical predictions of the longitudinal aerodynamic characteristics for the Ares I class of vehicles, along with the associated error estimate derived from an iterative convergence grid refinement, are presented. Computational results are based on the unstructured grid, Reynolds-averaged Navier-Stokes flow solver USM3D, with an assumption that the flow is fully turbulent over the entire vehicle. This effort was designed to complement the prior computational activities conducted over the past five years in support of the Ares I Project with the emphasis on the vehicle s last design cycle designated as the A106 configuration. Due to a lack of flight data for this particular design s outer mold line, the initial vehicle s aerodynamic predictions and the associated error estimates were first assessed and validated against the available experimental data at representative wind tunnel flow conditions pertinent to the ascent phase of the trajectory without including any propulsion effects. Subsequently, the established procedures were then applied to obtain the longitudinal aerodynamic predictions at the selected flight flow conditions. Sample computed results and the correlations with the experimental measurements are presented. In addition, the present analysis includes the relevant data to highlight the balance between the prediction accuracy against the grid size and, thus, the corresponding computer resource requirements for the computations at both wind tunnel and flight flow conditions. NOTE: Some details have been removed from selected plots and figures in compliance with the sensitive but unclassified (SBU) restrictions. However, the content still conveys the merits of the technical approach and the relevant results.
NASA Astrophysics Data System (ADS)
Parajuli, Sagar Prasad; Zobeck, Ted M.; Kocurek, Gary; Yang, Zong-Liang; Stenchikov, Georgiy L.
2016-02-01
Numerous parameterizations have been developed for predicting wind erosion, yet the physical mechanism of dust emission is not fully understood. Sandblasting is thought to be the primary mechanism, but recent studies suggest that dust emission by direct aerodynamic entrainment can be significant under certain conditions. In this work, using wind tunnel experiments, we investigated some of the lesser understood aspects of dust emission in sandblasting and aerodynamic entrainment for three soil types, namely, clay, silty clay loam, and clay loam. First, we explored the role of erodible surface roughness on dust emitted by aerodynamic entrainment. Second, we compared the emitted dust concentration in sandblasting and aerodynamic entrainment under a range of wind friction velocities. Finally, we explored the sensitivity of emitted dust particle size distribution (PSD) to soil type and wind friction velocity in these two processes. The dust concentration in aerodynamic entrainment showed strong positive correlation, no significant correlation, and weak negative correlation, for the clay, silty clay loam, and clay loam, respectively, with the erodible soil surface roughness. The dust in aerodynamic entrainment was significant constituting up to 28.3, 41.4, and 146.4% compared to sandblasting for the clay, silty clay loam, and clay loam, respectively. PSD of emitted dust was sensitive to soil type in both sandblasting and aerodynamic entrainment. PSD was sensitive to the friction velocity in aerodynamic entrainment but not in sandblasting. Our results highlight the need to consider the details of sandblasting and direct aerodynamic entrainment processes in parameterizing dust emission in global/regional climate models.
NASA Technical Reports Server (NTRS)
Batterson, J. G.
1986-01-01
The successful parametric modeling of the aerodynamics for an airplane operating at high angles of attack or sideslip is performed in two phases. First the aerodynamic model structure must be determined and second the associated aerodynamic parameters (stability and control derivatives) must be estimated for that model. The purpose of this paper is to document two versions of a stepwise regression computer program which were developed for the determination of airplane aerodynamic model structure and to provide two examples of their use on computer generated data. References are provided for the application of the programs to real flight data. The two computer programs that are the subject of this report, STEP and STEPSPL, are written in FORTRAN IV (ANSI l966) compatible with a CDC FTN4 compiler. Both programs are adaptations of a standard forward stepwise regression algorithm. The purpose of the adaptation is to facilitate the selection of a adequate mathematical model of the aerodynamic force and moment coefficients of an airplane from flight test data. The major difference between STEP and STEPSPL is in the basis for the model. The basis for the model in STEP is the standard polynomial Taylor's series expansion of the aerodynamic function about some steady-state trim condition. Program STEPSPL utilizes a set of spline basis functions.
Aerodynamic design optimization by using a continuous adjoint method
NASA Astrophysics Data System (ADS)
Luo, JiaQi; Xiong, JunTao; Liu, Feng
2014-07-01
This paper presents the fundamentals of a continuous adjoint method and the applications of this method to the aerodynamic design optimization of both external and internal flows. General formulation of the continuous adjoint equations and the corresponding boundary conditions are derived. With the adjoint method, the complete gradient information needed in the design optimization can be obtained by solving the governing flow equations and the corresponding adjoint equations only once for each cost function, regardless of the number of design parameters. An inverse design of airfoil is firstly performed to study the accuracy of the adjoint gradient and the effectiveness of the adjoint method as an inverse design method. Then the method is used to perform a series of single and multiple point design optimization problems involving the drag reduction of airfoil, wing, and wing-body configuration, and the aerodynamic performance improvement of turbine and compressor blade rows. The results demonstrate that the continuous adjoint method can efficiently and significantly improve the aerodynamic performance of the design in a shape optimization problem.
Maiaugree, Wasan; Lowpa, Seksan; Towannang, Madsakorn; Rutphonsan, Phikun; Tangtrakarn, Apishok; Pimanpang, Samuk; Maiaugree, Prapen; Ratchapolthavisin, Nattawat; Sang-aroon, Wichien; Jarernboon, Wirat; Amornkitbamrung, Vittaya
2015-01-01
Mangosteen peel is an inedible portion of a fruit. We are interested in using these residues as components of a dye sensitized solar cell (DSSC). Carbonized mangosteen peel was used with mangosteen peel dye as a natural counter electrode and a natural photosensitizer, respectively. A distinctive mesoporous honeycomb-like carbon structure with a rough nanoscale surface was found in carbonized mangosteen peels. The efficiency of a dye sensitized solar cell using carbonized mangosteen peel was compared to that of DSSCs with Pt and PEDOT-PSS counter electrodes. The highest solar conversion efficiency (2.63%) was obtained when using carbonized mangosteen peel and an organic disulfide/thiolate (T2/T−) electrolyte. PMID:26458745
NASA Astrophysics Data System (ADS)
Maiaugree, Wasan; Lowpa, Seksan; Towannang, Madsakorn; Rutphonsan, Phikun; Tangtrakarn, Apishok; Pimanpang, Samuk; Maiaugree, Prapen; Ratchapolthavisin, Nattawat; Sang-Aroon, Wichien; Jarernboon, Wirat; Amornkitbamrung, Vittaya
2015-10-01
Mangosteen peel is an inedible portion of a fruit. We are interested in using these residues as components of a dye sensitized solar cell (DSSC). Carbonized mangosteen peel was used with mangosteen peel dye as a natural counter electrode and a natural photosensitizer, respectively. A distinctive mesoporous honeycomb-like carbon structure with a rough nanoscale surface was found in carbonized mangosteen peels. The efficiency of a dye sensitized solar cell using carbonized mangosteen peel was compared to that of DSSCs with Pt and PEDOT-PSS counter electrodes. The highest solar conversion efficiency (2.63%) was obtained when using carbonized mangosteen peel and an organic disulfide/thiolate (T2/T-) electrolyte.
Maiaugree, Wasan; Lowpa, Seksan; Towannang, Madsakorn; Rutphonsan, Phikun; Tangtrakarn, Apishok; Pimanpang, Samuk; Maiaugree, Prapen; Ratchapolthavisin, Nattawat; Sang-Aroon, Wichien; Jarernboon, Wirat; Amornkitbamrung, Vittaya
2015-01-01
Mangosteen peel is an inedible portion of a fruit. We are interested in using these residues as components of a dye sensitized solar cell (DSSC). Carbonized mangosteen peel was used with mangosteen peel dye as a natural counter electrode and a natural photosensitizer, respectively. A distinctive mesoporous honeycomb-like carbon structure with a rough nanoscale surface was found in carbonized mangosteen peels. The efficiency of a dye sensitized solar cell using carbonized mangosteen peel was compared to that of DSSCs with Pt and PEDOT-PSS counter electrodes. The highest solar conversion efficiency (2.63%) was obtained when using carbonized mangosteen peel and an organic disulfide/thiolate (T2/T(-)) electrolyte. PMID:26458745
Rarefaction Effects in Hypersonic Aerodynamics
NASA Astrophysics Data System (ADS)
Riabov, Vladimir V.
2011-05-01
The Direct Simulation Monte-Carlo (DSMC) technique is used for numerical analysis of rarefied-gas hypersonic flows near a blunt plate, wedge, two side-by-side plates, disk, torus, and rotating cylinder. The role of various similarity parameters (Knudsen and Mach numbers, geometrical and temperature factors, specific heat ratios, and others) in aerodynamics of the probes is studied. Important kinetic effects that are specific for the transition flow regime have been found: non-monotonic lift and drag of plates, strong repulsive force between side-by-side plates and cylinders, dependence of drag on torus radii ratio, and the reverse Magnus effect on the lift of a rotating cylinder. The numerical results are in a good agreement with experimental data, which were obtained in a vacuum chamber at low and moderate Knudsen numbers from 0.01 to 10.
Aerodynamic research on tipvane windturbines
NASA Astrophysics Data System (ADS)
Vanbussel, G. J. W.; Vanholten, T.; Vankuik, G. A. M.
1982-09-01
Tipvanes are small auxiliary wings mounted at the tips of windturbine blades in such a way that a diffuser effect is generated, resulting in a mass flow augmentation through the turbine disc. For predicting aerodynamic loads on the tipvane wind turbine, the acceleration potential is used and an expansion method is applied. In its simplest form, this method can essentially be classified as a lifting line approach, however, with a proper choice of the basis load distributions of the lifting line, the numerical integration of the pressurefield becomes one dimensional. the integration of the other variable can be performed analytically. The complete analytical expression for the pressure field consists of two series of basic pressure fields. One series is related to the basic load distributions over the turbineblade, and the other series to the basic load distribution over the tipvane.
Aerodynamic seals for rotary machine
Bidkar, Rahul Anil; Cirri, Massimiliano; Thatte, Azam Mihir; Williams, John Robert
2016-02-09
An aerodynamic seal assembly for a rotary machine includes multiple sealing device segments disposed circumferentially intermediate to a stationary housing and a rotor. Each of the segments includes a shoe plate with a forward-shoe section and an aft-shoe section having multiple labyrinth teeth therebetween facing the rotor. The sealing device segment also includes multiple flexures connected to the shoe plate and to a top interface element, wherein the multiple flexures are configured to allow the high pressure fluid to occupy a forward cavity and the low pressure fluid to occupy an aft cavity. Further, the sealing device segments include a secondary seal attached to the top interface element at one first end and positioned about the flexures and the shoe plate at one second end.
Aerodynamic characteristics of aerofoils I
NASA Technical Reports Server (NTRS)
1921-01-01
The object of this report is to bring together the investigations of the various aerodynamic laboratories in this country and Europe upon the subject of aerofoils suitable for use as lifting or control surfaces on aircraft. The data have been so arranged as to be of most use to designing engineers and for the purposes of general reference. The absolute system of coefficients has been used, since it is thought by the National Advisory Committee for Aeronautics that this system is the one most suited for international use, and yet is one for which a desired transformation can be easily made. For this purpose a set of transformation constants is included in this report.
On Cup Anemometer Rotor Aerodynamics
Pindado, Santiago; Pérez, Javier; Avila-Sanchez, Sergio
2012-01-01
The influence of anemometer rotor shape parameters, such as the cups' front area or their center rotation radius on the anemometer's performance was analyzed. This analysis was based on calibrations performed on two different anemometers (one based on magnet system output signal, and the other one based on an opto-electronic system output signal), tested with 21 different rotors. The results were compared to the ones resulting from classical analytical models. The results clearly showed a linear dependency of both calibration constants, the slope and the offset, on the cups' center rotation radius, the influence of the front area of the cups also being observed. The analytical model of Kondo et al. was proved to be accurate if it is based on precise data related to the aerodynamic behavior of a rotor's cup. PMID:22778638
CHEN, CHIEN-MIN; SYU, JHIH-PU; WAY, TZONG-DER; HUANG, LI-JIAU; KUO, SHENG-CHU; LIN, CHUNG-TIEN; LIN, CHIH-LI
2015-01-01
Glioblastoma multiforme (GBM) is the most fatal form of human brain cancer. Although temozolomide (TMZ), an oral alkylating chemotherapeutic agent, improves the survival rate, the prognosis of patients with GBM remains poor. Naturally occurring carbazole alkaloids isolated from curry leaves (Murraya koenigii Spreng.) have been shown to possess a wide range of anticancer properties. However, the effects of carbazole derivatives on glioblastoma cells remain poorly understood. In the present study, anti-glioblastoma profiles of a series of synthetic carbazole derivatives were evaluated in vitro. The most promising derivative in this series was BC3EE2,9B, which showed significant anti-proliferative effects in GBM8401 and GBM8901 cells. BC3EE2,9B also triggered cell-cycle arrest, most prominently at the G1 stage, and suppressed glioblastoma cell invasion and migration. Furthermore, BC3EE2,9B induced autophagy-mediated cell death and synergistically sensitized GBM cells to TMZ cytotoxicity. The possible mechanism underlying BC3EE2,9B-induced autophagy may involve activation of adenosine monophosphate-activated protein kinase and the attenuation of the Akt and mammalian target of the rapamycin downstream signaling pathway. Taken together, the present results provide molecular evidence for the mode of action governing the ability of BC3EE2,9B to sensitize drug-resistant glioblastoma cells to the chemotherapeutic agent TMZ. PMID:26329365
Moreno, Javier; Gerecke, Mario; Grubert, Lutz; Kovalenko, Sergey A; Hecht, Stefan
2016-01-22
Two-NIR-photon-triggered Z→E isomerization of an azobenzene was accomplished by covalently linking a two-photon-harvesting triarylamine antenna to a thermally stable ortho-fluorinated azobenzene derivative. The obtained photoswitch is fully addressable with visible and NIR light by using one-photon and two-photon excitation, respectively, with the latter offering enhanced penetration depth and improved spatial resolution. PMID:26679769
NASA Astrophysics Data System (ADS)
Avdan, Ugur; Gorum, Tolga; Comert, Resul; Nefeslioglu, Hakan
2015-04-01
The main purpose of this study is to evaluate the spatial resolutions for the Digital Terrain Models (DTMs) derived from Unmanned Aerial Vehicle (UAV) in gully erosion mapping. For the purpose, Nallihan badland area (Ankara, Turkey) was selected to be the experimental site. The investigations were carried out in 3 stages; (i) production of the DTMs having 3 cm and 9 cm spatial resolutions by using the orthophoto imagery acquired from the UAV at 97.5 m and 292.4 m altitudes, respectively, (ii) Terrestrial Laser Scanning (TLS) of the experimental site and production of the DTMs derived from the TLS data resampled at 3 cm and 9 cm spatial resolutions, and (iii) spatial and profile comparisons of the derived data. The average altitude differences were obtained on the intervals (-0.1, 0.1) m and (-0.2, 0.2) m for the comparisons between TLS-3cm and UAV-3cm, and TLS-9cm and UAV-9cm data, respectively. Additionally, considering the profile comparisons, it is revealed that depending on the decreasing of spatial resolution, the erosion rates calculated from the DTMs increase artificially.
Aerodynamic Noise Generated by Shinkansen Cars
NASA Astrophysics Data System (ADS)
KITAGAWA, T.; NAGAKURA, K.
2000-03-01
The noise value (A -weighted sound pressure level, SLOW) generated by Shinkansen trains, now running at 220-300 km/h, should be less than 75 dB(A) at the trackside. Shinkansen noise, such as rolling noise, concrete support structure noise, and aerodynamic noise are generated by various parts of Shinkansen trains. Among these aerodynamic noise is important because it is the major contribution to the noise generated by the coaches running at high speed. In order to reduce the aerodynamic noise, a number of improvements to coaches have been made. As a result, the aerodynamic noise has been reduced, but it still remains significant. In addition, some aerodynamic noise generated from the lower parts of cars remains. In order to investigate the contributions of these noises, a method of analyzing Shinkansen noise has been developed and applied to the measured data of Shinkansen noise at speeds between 120 and 315 km/h. As a result, the following conclusions have been drawn: (1) Aerodynamic noise generated from the upper parts of cars was reduced considerably by smoothing car surfaces. (2) Aerodynamic noise generated from the lower parts of cars has a major influence upon the wayside noise.
DOE Project on Heavy Vehicle Aerodynamic Drag
McCallen, R; Salari, K; Ortega, J; Castellucci, P; Pointer, D; Browand, F; Ross, J; Storms, B
2007-01-04
Class 8 tractor-trailers consume 11-12% of the total US petroleum use. At highway speeds, 65% of the energy expenditure for a Class 8 truck is in overcoming aerodynamic drag. The project objective is to improve fuel economy of Class 8 tractor-trailers by providing guidance on methods of reducing drag by at least 25%. A 25% reduction in drag would present a 12% improvement in fuel economy at highway speeds, equivalent to about 130 midsize tanker ships per year. Specific goals include: (1) Provide guidance to industry in the reduction of aerodynamic drag of heavy truck vehicles; (2) Develop innovative drag reducing concepts that are operationally and economically sound; and (3) Establish a database of experimental, computational, and conceptual design information, and demonstrate the potential of new drag-reduction devices. The studies described herein provide a demonstration of the applicability of the experience developed in the analysis of the standard configuration of the Generic Conventional Model. The modeling practices and procedures developed in prior efforts have been applied directly to the assessment of new configurations including a variety of geometric modifications and add-on devices. Application to the low-drag 'GTS' configuration of the GCM has confirmed that the error in predicted drag coefficients increases as the relative contribution of the base drag resulting from the vehicle wake to the total drag increases and it is recommended that more advanced turbulence modeling strategies be applied under those circumstances. Application to a commercially-developed boat tail device has confirmed that this restriction does not apply to geometries where the relative contribution of the base drag to the total drag is reduced by modifying the geometry in that region. Application to a modified GCM geometry with an open grille and radiator has confirmed that the underbody flow, while important for underhood cooling, has little impact on the drag coefficient of
Sebastian, Katrin; Ott, Hagen; Zwadlo-Klarwasser, Gabriele; Skazik-Voogt, Claudia; Marquardt, Yvonne; Czaja, Katharina; Merk, Hans F; Baron, Jens Malte
2012-08-01
Since the 7th amendment to the EU cosmetics directive foresees a complete ban on animal testing, alternative in vitro methods have been established to evaluate the sensitizing potential of small molecular weight compounds. To find out whether these novel in vitro assays are also capable to predict the sensitizing potential of small molecular weight drugs, model compounds such as beta-lactams and sulfonamides - which are the most frequent cause of adverse drug reactions - were co-incubated with THP-1, MUTZ-LC, or primary monocyte-derived dendritic cells for 48 h and subsequent expression of selected marker genes (IL-8, IL-1β, CES1, NQO1, GCLM, PIR and TRIM16) was studied by real time PCR. Benzylpenicillin and phenoxymethylpenicillin were recognized as sensitizing compounds because they are capable to induce the mRNA expression of these genes in moDCs and, except for IL-8, in THP-1 cells but not in MUTZ-LC. Ampicillin stimulated the expression of some marker genes in moDCs and THP-1 cells. SMX did not affect the expression of these genes in THP-1, however, in moDCs, at least PIR was enhanced and there was an increase of the release of IL-8. These data reveal that novel in vitro DC based assays might play a role in the evaluation of the allergenic potential of novel drug compounds, but these systems seem to lack the ability to detect the sensitizing potential of prohaptens that require metabolic activation prior to sensitization and moDCs seem to be superior with regard to the sensitivity compared with THP-1 and MUTZ-3 cell lines. PMID:22609641
Active Control of Aerodynamic Noise Sources
NASA Technical Reports Server (NTRS)
Reynolds, Gregory A.
2001-01-01
Aerodynamic noise sources become important when propulsion noise is relatively low, as during aircraft landing. Under these conditions, aerodynamic noise from high-lift systems can be significant. The research program and accomplishments described here are directed toward reduction of this aerodynamic noise. Progress toward this objective include correction of flow quality in the Low Turbulence Water Channel flow facility, development of a test model and traversing mechanism, and improvement of the data acquisition and flow visualization capabilities in the Aero. & Fluid Dynamics Laboratory. These developments are described in this report.
Transpiration Control Of Aerodynamics Via Porous Surfaces
NASA Technical Reports Server (NTRS)
Banks, Daniel W.; Wood, Richard M.; Bauer, Steven X. S.
1993-01-01
Quasi-active porous surface used to control pressure loading on aerodynamic surface of aircraft or other vehicle, according to proposal. In transpiration control, one makes small additions of pressure and/or mass to cavity beneath surface of porous skin on aerodynamic surface, thereby affecting rate of transpiration through porous surface. Porous skin located on forebody or any other suitable aerodynamic surface, with cavity just below surface. Device based on concept extremely lightweight, mechanically simple, occupies little volume in vehicle, and extremely adaptable.
NASA Astrophysics Data System (ADS)
Milutinović, Svetlana; Behrenfeld, Michael J.; Johannessen, Johnny A.; Johannessen, Truls
2009-12-01
Mixed layer depth (MLD) has long been recognized as having an important influence on underwater light budget and, thus, net primary productivity (NPP) of phytoplankton. The depth- and wavelength-integrated carbon-based productivity model (DWI CbPM) is one of a few productivity algorithms that explicitly use information on MLD to estimate ocean NPP from remote sensing observations. This study evaluates the sensitivity of NPP estimates from the DWI CbPM to MLD input by using MLD fields from four different ocean models. Owing to the effect of MLD on light availability, the model NPP is generally inversely related to MLD, but the strength of this relationship is highly variable. In most of the ocean, it exhibits a seasonal character. In summer, NPP at middle and high latitudes can show substantial sensitivity to subtle changes in MLD, but is largely robust to strong MLD variability in winter. An opposite seasonal pattern is encountered in subtropical ocean gyres. A lack of seasonality is observed in tropical areas, among which only the equatorial Pacific displays strong response of NPP to small or moderate changes in MLD. We find that the spatial and temporal variability of the MLD-NPP relationship can be explained by nonlinearity and light saturation/limitation thresholds indicated in the DWI CbPM, as well as the influence of surface irradiance (I0) and diffuse attenuation coefficient for downwelling light at 490 nm (Kd(490)). NPP is sensitive to varying MLD only if coincidental I0 and Kd(490) values are such that combined with the coexisting differences in MLD estimates, they have potential to give effective differences in light saturation/limitation of photosynthesis.
Hu, Gaoshuang; Sheng, Wei; Zhang, Yan; Wu, Xuening; Wang, Shuo
2015-11-01
A novel fluorescence immunoassay to detect fluoroquinolones in animal-derived foods was developed for the first time by use of upconversion nanoparticles as signal-probe labels. The bioassay system was established by the use of coating-antigen-modified polystyrene particles as immune-sensing probes for separation and anti-norfloxacin monoclonal antibody conjugated with carboxyl-functionalized NaYF4:Yb,Er upconversion nanoparticles which were prepared via a pyrolysis method and a subsequent ligand exchange process as fluorescent-signal probes (emission intensity recorded at 542 nm with excitation at 980 nm). Under optimized conditions, detection of fluoroquinolones was performed easily. The detection limit of this fluorescence immunoassay for norfloxacin, for example, was 10 pg mL(-1), within a wide linear range of 10 pg mL(-1) to 10 ng mL(-1) (R (2) = 0.9959). For specificity analysis, the data obtained indicate this method could be applied in broad-spectrum detection of fluoroquinolones. The recoveries of norfloxacin-spiked animal-derived foods ranged from 82.37 to 132.22 %, with coefficients of variation of 0.24-25.06 %. The extraction procedure was rapid and simple, especially for milk samples, which could be analyzed directly without any pretreatment. In addition, the results obtained with the method were in good agreement with those obtained with commercial ELISA kits. The fluorescence immunoassay was more sensitive, especially with regard to the detection limit in milk samples (0.01 ng mL(-1) for norfloxacin): it was 50-fold more sensitive than commercial ELISA kits (0.5 ng mL(-1) for norfloxacin). The results show the proposed fluorescence immunoassay was facile, sensitive, and interference free, and is an alternative method for the quantitative detection of fluoroquinolone residues in animal-derived foods. PMID:26337749
Exploring Discretization Error in Simulation-Based Aerodynamic Databases
NASA Technical Reports Server (NTRS)
Aftosmis, Michael J.; Nemec, Marian
2010-01-01
This work examines the level of discretization error in simulation-based aerodynamic databases and introduces strategies for error control. Simulations are performed using a parallel, multi-level Euler solver on embedded-boundary Cartesian meshes. Discretization errors in user-selected outputs are estimated using the method of adjoint-weighted residuals and we use adaptive mesh refinement to reduce these errors to specified tolerances. Using this framework, we examine the behavior of discretization error throughout a token database computed for a NACA 0012 airfoil consisting of 120 cases. We compare the cost and accuracy of two approaches for aerodynamic database generation. In the first approach, mesh adaptation is used to compute all cases in the database to a prescribed level of accuracy. The second approach conducts all simulations using the same computational mesh without adaptation. We quantitatively assess the error landscape and computational costs in both databases. This investigation highlights sensitivities of the database under a variety of conditions. The presence of transonic shocks or the stiffness in the governing equations near the incompressible limit are shown to dramatically increase discretization error requiring additional mesh resolution to control. Results show that such pathologies lead to error levels that vary by over factor of 40 when using a fixed mesh throughout the database. Alternatively, controlling this sensitivity through mesh adaptation leads to mesh sizes which span two orders of magnitude. We propose strategies to minimize simulation cost in sensitive regions and discuss the role of error-estimation in database quality.
NASA Technical Reports Server (NTRS)
Baize, Daniel G. (Editor)
1999-01-01
The High-Speed Research Program and NASA Langley Research Center sponsored the NASA High-Speed Research Program Aerodynamic Performance Workshop on February 25-28, 1997. The workshop was designed to bring together NASA and industry High-Speed Civil Transport (HSCT) Aerodynamic Performance technology development participants in areas of Configuration Aerodynamics (transonic and supersonic cruise drag prediction and minimization), High-Lift, Flight Controls, Supersonic Laminar Flow Control, and Sonic Boom Prediction. The workshop objectives were to (1) report the progress and status of HSCT aerodynamic performance technology development; (2) disseminate this technology within the appropriate technical communities; and (3) promote synergy among the scientist and engineers working HSCT aerodynamics. In particular, single- and multi-point optimized HSCT configurations, HSCT high-lift system performance predictions, and HSCT Motion Simulator results were presented along with executive summaries for all the Aerodynamic Performance technology areas.
Anbarasan, P. M.
2010-08-06
New technologies for direct solar energy conversion have gained more attention in the last few years. In particular, Dye Sensitized Solar Cells (DSSCs) are promising in terms of efficiency and low cost [1,2]. Benefited from systematic device engineering and continuous material innovation, a state of the art DSC with a ruthenium sensitizer has achieved a validated efficiency of 11.1%[3] measured under the air mass 1.5 global (AM1.5G) conditions.The optimized geometries of the 3, 4-Pyridinedicarbonitrile, 3-Aminophthalonitrile, 4-Aminophthalonitrile and 4-Methylphthalonitrile are shown in Fig. 1(a). The frontier molecular orbitals (MO) energies of the dyes 3, 4 Pyridinedicarbonitrile, 3-Nitrophthalonitrile, 4-Aminophthalonitrile and 4-Methylphthalonitrile are shown in Fig. 1(b). The HOMO-LUMO gap of the dye 3, 4 Pyridinedicarbonitrile, 3-Aminophthalonitrile, 4-Aminophthalonitrile and 4-Methylphthalonitrile in vacuum is 5.96 eV, 5.54 eV, 5.57 eV, 5.76 eV respectively. The geometries, electronic structures, polarizabilities, and hyperpolarizabilities of dyes 3, 4-Pyridinedicarbonitrile, 4-Aminophthalonitrile and 4-Methylphthalonitrile were studied by using density functional theory with hybrid functional B3LYP, and the UV-Vis spectra were investigated by using TDDFT methods. The NBO results suggest that 3, 4-Pyridinedicarbonitrile, 3-Aminophthalonitrile 4-Aminophthalonitrile and 4-Methylphthalonitrile are all (D-pi-A) systems. The calculated isotropic polarizability of 3, 4-Pyridinedicarbonitrile, 3-Aminophthalonitrile, 4-Aminophthalonitrile and 4-Methylphthalonitrile is. 85.76, 112.72, 26.63 and 115.13 a.u., respectively. The calculated polarizability anisotropy invariant of 3, 4-Pyridinedicarbonitrile, 3-Aminophthalonitrile, 4-Aminophthalonitrile and 4-Methylphthalonitrile is 74.451, 83.533, 62.653 and 88.526 a.u., respectively. The hyperpolarizabilities of 3, 4-Pyridinedicarbonitrile, 3-Aminophthalonitrile, 4-Aminophthalonitrile and 4-Methylphthalonitrile is 0
Martin-Garcia, Julio . E-mail: julio.martin-garcia@drexelmed.edu; Cao, Wei; Varela-Rohena, Angel; Plassmeyer, Matthew L.; Gonzalez-Scarano, Francisco
2006-03-01
We previously described envelope glycoproteins of an HIV-1 isolate adapted in vitro for growth in microglia that acquired a highly fusogenic phenotype and lower CD4 dependence, as well as resistance to inhibition by anti-CD4 antibodies. Here, we investigated whether similar phenotypic changes are present in vivo. Envelope clones from the brain and spleen of an HIV-1-infected individual with neurological disease were amplified, cloned, and sequenced. Phylogenetic analysis demonstrated clustering of sequences according to the tissue of origin, as expected. Functional clones were then used in cell-to-cell fusion assays to test for CD4 and co-receptor utilization and for sensitivity to various antibodies and inhibitors. Both brain- and spleen-derived envelope clones mediated fusion in cells expressing both CD4 and CCR5 and brain envelopes also used CCR3 as co-receptor. We found that the brain envelopes had a lower CD4 dependence, since they efficiently mediated fusion in the presence of low levels of CD4 on the target cell membrane, and they were significantly more resistant to blocking by anti-CD4 antibodies than the spleen-derived envelopes. In contrast, we observed no difference in sensitivity to the CCR5 antagonist TAK-779. However, brain-derived envelopes were significantly more resistant than those from spleen to the fusion inhibitor T-1249 and concurrently showed slightly greater fusogenicity. Our results suggest an increased affinity for CD4 of brain-derived envelopes that may have originated from in vivo adaptation to replication in microglial cells. Interestingly, we note the presence of envelopes more resistant to a fusion inhibitor in the brain of an untreated, HIV-1-infected individual.
NASA Astrophysics Data System (ADS)
Song, Ting; Zhu, Xuefeng; Zhou, Shenghai; Yang, Guang; Gan, Wei; Yuan, Qunhui
2015-08-01
Inspired by the high affinity between heavy metal ions and bio-molecules as well as the low toxicity of carbon-based quantum dots, we demonstrated the first application of a DNA derived carbonaceous quantum dots, namely bio-dots, in metal ion sensing. The present DNA-derived bio-dots contain graphitic carbon layers with 0.242 nm lattice fringes, exhibit excellent fluorescence property and can be obtained via a facile hydrothermal preparation procedure. Hg(II) and Ag(I) are prone to be captured by the bio-dots due to the existence of residual thymine (T) and cytosine (C) groups, resulting in a quenched fluorescence while other heavy metal ions would cause negligible changes on the fluorescent signals of the bio-dots. The bio-dots could be used as highly selective toxic-free biosensors, with two detecting linear ranges of 0-0.5 μM and 0.5-6 μM for Hg(II) and one linear range of 0-10 μM for Ag(I). The detection limits (at a signal-to-noise ratio of 3) were estimated to be 48 nM for Hg(II) and 0.31 μM for Ag(I), respectively. The detection of Hg(II) and Ag(I) could also be realized in the real water sample analyses, with satisfying recoveries ranging from 87% to 100%.
NASA Technical Reports Server (NTRS)
Messina, Michael D.
1995-01-01
The method described in this report is intended to present an overview of a process developed to extract the forebody aerodynamic increments from flight tests. The process to determine the aerodynamic increments (rolling pitching, and yawing moments, Cl, Cm, Cn, respectively) for the forebody strake controllers added to the F/A - 18 High Alpha Research Vehicle (HARV) aircraft was developed to validate the forebody strake aerodynamic model used in simulation.
NASA Technical Reports Server (NTRS)
Hahne, David E. (Editor)
1999-01-01
NASA's High-Speed Research Program sponsored the 1999 Aerodynamic Performance Technical Review on February 8-12, 1999 in Anaheim, California. The review was designed to bring together NASA and industry High-Speed Civil Transport (HSCT) Aerodynamic Performance technology development participants in the areas of Configuration Aerodynamics (transonic and supersonic cruise drag prediction and minimization), High Lift, and Flight Controls. The review objectives were to: (1) report the progress and status of HSCT aerodynamic performance technology development; (2) disseminate this technology within the appropriate technical communities; and (3) promote synergy among the scientists and engineers working on HSCT aerodynamics. In particular, single and midpoint optimized HSCT configurations, HSCT high-lift system performance predictions, and HSCT simulation results were presented, along with executive summaries for all the Aerodynamic Performance technology areas. The HSR Aerodynamic Performance Technical Review was held simultaneously with the annual review of the following airframe technology areas: Materials and Structures, Environmental Impact, Flight Deck, and Technology Integration. Thus, a fourth objective of the Review was to promote synergy between the Aerodynamic Performance technology area and the other technology areas of the HSR Program. This Volume 1/Part 1 publication covers configuration aerodynamics.
NASA Technical Reports Server (NTRS)
Pamadi , Bandu N.; Brauckmann, Gregory J.
1999-01-01
An overview of the aerodynamic characteristics and the process of developing the preflight aerodynamic database of the NASA/ Orbital X-34 reusable launch vehicle is presented in this paper. Wind tunnel tests from subsonic to hypersonic Mach numbers including ground effect tests at low subsonic speeds were conducted in various facilities at the NASA Langley Research Center. The APAS (Aerodynamic Preliminary Analysis System) code was used for engineering level analysis and to fill the gaps in the wind tunnel test data. This aerodynamic database covers the range of Mach numbers, angles of attack, sideslip and control surface deflections anticipated in the complete flight envelope.
Müller, Ludmila; Knights, Ashley; Pawelec, Graham
2003-01-01
The Wilms' tumour 1 (WT1) molecule was screened in silico for the presence of 15-mer sequences predicted to bind HLA-DRB1(*)0401 (www.syfpeithi.de). Two peptides with the highest binding scores were synthesized (WT12e, PQQMGSDVRDLNALL and WT331, NKRYFKLSHLQMHSR). In vitro sensitization experiments using PBMC and the 15-mer peptides yielded peptide-specific responses against both WT12e and WT331 from six of seven healthy donors. Moreover, four of four different primary CML cell preparations were directly recognized by five different T cell lines, as assessed by IFN-gamma release. These responses were to a great extent blocked by anti-DR monoclonal antibody. These results suggest that WT1 peptides can be selected that are immunogenic for class II-restricted T-cell responses to native tumor cells, and indicate that they may find application in active immunotherapy of CML. PMID:12692522
NASA Astrophysics Data System (ADS)
Niu, Qingfen; Wu, Xingxing; Zhang, Shanshan; Li, Tianduo; Cui, Yuezhi; Li, Xiaoyan
2016-01-01
A fast-responsive fluorescent phenylamine-oligothiophene sensor 3TDDA was reported. This sensor exhibited highly selective and sensitive detection of Hg2 + ion in aqueous solution (THF/CH3CN/H2O, 45/50/5, v/v) through fluorescence quenching. The detection was not affected by the coexistence of other competitive metal ions such as Na+, K+, Ag+, Ca2 +, Fe3 +, Al3 +, Co2 +, Ni2 +, Zn2 +, Pb2 +, Cd2 +, Fe2 + and Cr3 +. A stoichiometric ratio (1:1) of the sensor and Hg2 + was determined by a Job's plot and mole-ratio curves. The binding of sensor 3TDDA and Hg2 + was also chemically reversible with EDTA. The detection limit was calculated as low as 4.392 × 10- 7 M.
Sebastian, Katrin; Ott, Hagen; Zwadlo-Klarwasser, Gabriele; Skazik-Voogt, Claudia; Marquardt, Yvonne; Czaja, Katharina; Merk, Hans F.; Baron, Jens Malte
2012-08-01
Since the 7th amendment to the EU cosmetics directive foresees a complete ban on animal testing, alternative in vitro methods have been established to evaluate the sensitizing potential of small molecular weight compounds. To find out whether these novel in vitro assays are also capable to predict the sensitizing potential of small molecular weight drugs, model compounds such as beta-lactams and sulfonamides – which are the most frequent cause of adverse drug reactions – were co-incubated with THP-1, MUTZ-LC, or primary monocyte‐derived dendritic cells for 48 h and subsequent expression of selected marker genes (IL-8, IL-1β, CES1, NQO1, GCLM, PIR and TRIM16) was studied by real time PCR. Benzylpenicillin and phenoxymethylpenicillin were recognized as sensitizing compounds because they are capable to induce the mRNA expression of these genes in moDCs and, except for IL-8, in THP-1 cells but not in MUTZ-LC. Ampicillin stimulated the expression of some marker genes in moDCs and THP-1 cells. SMX did not affect the expression of these genes in THP-1, however, in moDCs, at least PIR was enhanced and there was an increase of the release of IL-8. These data reveal that novel in vitro DC based assays might play a role in the evaluation of the allergenic potential of novel drug compounds, but these systems seem to lack the ability to detect the sensitizing potential of prohaptens that require metabolic activation prior to sensitization and moDCs seem to be superior with regard to the sensitivity compared with THP-1 and MUTZ-3 cell lines. -- Highlights: ► We tested the sensitizing potential of small molecular weight drugs in vitro. ► In vitro assays were performed with moDCs and THP-1 cells. ► Beta-lactam antibiotics can be recognized as sensitizing compounds. ► They affect the expression of metabolic enzymes, cytokines and transcription factors. ► Sulfamethoxazole has no measurable effect on THP-1 cells and moDCs.
HSR Aerodynamic Performance Status and Challenges
NASA Technical Reports Server (NTRS)
Gilbert, William P.; Antani, Tony; Ball, Doug; Calloway, Robert L.; Snyder, Phil
1999-01-01
This paper describes HSR (High Speed Research) Aerodynamic Performance Status and Challenges. The topics include: 1) Aero impact on HSR; 2) Goals and Targets; 3) Progress and Status; and 4) Remaining Challenges. This paper is presented in viewgraph form.
Aerodynamic analysis of Pegasus - Computations vs reality
NASA Technical Reports Server (NTRS)
Mendenhall, Michael R.; Lesieutre, Daniel J.; Whittaker, C. H.; Curry, Robert E.; Moulton, Bryan
1993-01-01
Pegasus, a three-stage, air-launched, winged space booster was developed to provide fast and efficient commercial launch services for small satellites. The aerodynamic design and analysis of Pegasus was conducted without benefit of wind tunnel tests using only computational aerodynamic and fluid dynamic methods. Flight test data from the first two operational flights of Pegasus are now available, and they provide an opportunity to validate the accuracy of the predicted pre-flight aerodynamic characteristics. Comparisons of measured and predicted flight characteristics are presented and discussed. Results show that the computational methods provide reasonable aerodynamic design information with acceptable margins. Post-flight analyses illustrate certain areas in which improvements are desired.
Switchable and Tunable Aerodynamic Drag on Cylinders
NASA Astrophysics Data System (ADS)
Guttag, Mark; Lopez Jimenez, Francisco; Reis, Pedro
2015-11-01
We report results on the performance of Smart Morphable Surfaces (Smporhs) that can be mounted onto cylindrical structures to actively reduce their aerodynamic drag. Our system comprises of an elastomeric thin shell with a series of carefully designed subsurface cavities that, once depressurized, lead to a dramatic deformation of the surface topography, on demand. Our design is inspired by the morphology of the giant cactus (Carnegiea gigantea) which possesses an array of axial grooves, which are thought to help reduce aerodynamic drag, thereby enhancing the structural robustness of the plant under wind loading. We perform systematic wind tunnel tests on cylinders covered with our Smorphs and characterize their aerodynamic performance. The switchable and tunable nature of our system offers substantial advantages for aerodynamic performance when compared to static topographies, due to their operation over a wider range of flow conditions.
Switchable and Tunable Aerodynamic Drag on Cylinders
NASA Astrophysics Data System (ADS)
Guttag, Mark; Lopéz Jiménez, Francisco; Upadhyaya, Priyank; Kumar, Shanmugam; Reis, Pedro
We report results on the performance of Smart Morphable Surfaces (Smporhs) that can be mounted onto cylindrical structures to actively reduce their aerodynamic drag. Our system comprises of an elastomeric thin shell with a series of carefully designed subsurface cavities that, once depressurized, lead to a dramatic deformation of the surface topography, on demand. Our design is inspired by the morphology of the giant cactus (Carnegiea gigantea) which possesses an array of axial grooves, thought to help reduce aerodynamic drag, thereby enhancing the structural robustness of the plant under wind loading. We perform systematic wind tunnel tests on cylinders covered with our Smorphs and characterize their aerodynamic performance. The switchable and tunable nature of our system offers substantial advantages for aerodynamic performance when compared to static topographies, due to their operation over a wider range of flow conditions.
Aerodynamics and performance testing of the VAWT
Klimas, P.C.
1981-01-01
Early investigations suggest that reductions in cost of energy (COE) and increases in reliability for VAWT systems may be brought about through relatively inexpensive changes to the current aerodynamic design. This design uses blades of symmetrical cross-section mounted such that the radius from the rotating tower centerline is normal to the blade chord at roughly the 40% chord point. The envisioned changes to this existing design are intended to: (1) lower cut-in windspeed; (2) increase maximum efficiency; (3) limit maximum aerodynamic power; and (4) limit peak aerodynamic torques. This paper describes certain experiments designed to both better understand the aerodynamics of a section operating in an unsteady, curvilinear flowfield and achieve some of the desired changes in section properties. The common goal of all of these experiments is to lower VAWT COE and increase system reliability.
Aerodynamic Characterization of a Modern Launch Vehicle
NASA Technical Reports Server (NTRS)
Hall, Robert M.; Holland, Scott D.; Blevins, John A.
2011-01-01
A modern launch vehicle is by necessity an extremely integrated design. The accurate characterization of its aerodynamic characteristics is essential to determine design loads, to design flight control laws, and to establish performance. The NASA Ares Aerodynamics Panel has been responsible for technical planning, execution, and vetting of the aerodynamic characterization of the Ares I vehicle. An aerodynamics team supporting the Panel consists of wind tunnel engineers, computational engineers, database engineers, and other analysts that address topics such as uncertainty quantification. The team resides at three NASA centers: Langley Research Center, Marshall Space Flight Center, and Ames Research Center. The Panel has developed strategies to synergistically combine both the wind tunnel efforts and the computational efforts with the goal of validating the computations. Selected examples highlight key flow physics and, where possible, the fidelity of the comparisons between wind tunnel results and the computations. Lessons learned summarize what has been gleaned during the project and can be useful for other vehicle development projects.
Aerodynamic Analyses Requiring Advanced Computers, Part 1
NASA Technical Reports Server (NTRS)
1975-01-01
Papers are presented which deal with results of theoretical research on aerodynamic flow problems requiring the use of advanced computers. Topics discussed include: viscous flows, boundary layer equations, turbulence modeling and Navier-Stokes equations, and internal flows.
Hypervelocity Free-Flight Aerodynamic Facility (HFFAF)
The HFFAF is the only aeroballistic range the nation currently capable of testing in gases other than air and at sub-atmospheric pressures. It is used primarily to study the aerodynamics, Aerotherm...
Aerodynamic Analyses Requiring Advanced Computers, part 2
NASA Technical Reports Server (NTRS)
1975-01-01
Papers given at the conference present the results of theoretical research on aerodynamic flow problems requiring the use of advanced computers. Topics discussed include two-dimensional configurations, three-dimensional configurations, transonic aircraft, and the space shuttle.
High-sensitivity measurement of diverse vascular plant-derived biomarkers in high-altitude ice cores
NASA Astrophysics Data System (ADS)
Makou, Matthew C.; Thompson, Lonnie G.; Montluçon, Daniel B.; Eglinton, Timothy I.
2009-07-01
Semi-volatile organic compounds derived from burned and fresh vascular plant sources and preserved in high-altitude ice fields were detected and identified through use of recently developed analytical tools. Specifically, stir bar sorptive extraction and thermal desorption coupled with gas chromatography/time-of-flight mass spectrometry allowed measurement of multiple biomarkers in small sample volumes (≤30 ml). Among other compounds of interest, several diterpenoids, which suggest inputs from conifers and conifer burning, were identified in post-industrial era and older Holocene ice from the Sajama site in the Bolivian Andes, but not in a glacial period sample, consistent with aridity changes. Differences in biomarker assemblages between sites support the use of these compounds as regionally constrained recorders of vegetation and climate change. This study represents the first application of these analytical techniques to ice core research and the first indication that records of vegetation fires may be reconstructed from diterpenoids in ice.
Vardy, Eyal; Sassano, Maria F.; Rennekamp, Andrew J.; Kroeze, Wesley K.; Mosier, Philip D.; Westkaemper, Richard B.; Stevens, Craig W.; Katritch, Vsevolod; Stevens, Raymond C.; Peterson, Randel T.; Roth, Bryan L.
2015-01-01
It has been suggested that the evolution of vertebrate opioid receptors (ORs) follow a vector of increased functionality. Here we test this idea comparing human and frog ORs. Interestingly, some of the most potent opioid peptides known have been isolated from amphibian skin secretions. Here we show that such peptides (dermorphin and deltorphin) are highly potent in the human receptors and inactive in frog ORs. The molecular basis for the insensitivity of the frog ORs to these peptides was studied using chimeras and molecular modeling. Interestingly, the insensitivity of the delta opioid receptor (DOR) to deltorphin was due to variation of a single amino acid– Trp7.35—which is a leucine in mammalian DORs. Notably, Trp7.35 is completely conserved in all known DOR sequences from lamprey, fish and amphibians. The deltorphin-insensitive phenotype was verified in fish. Our results provide a molecular explanation for the species selectivity of skin-derived opioid peptides. PMID:26091169
Correlation-based Transition Modeling for External Aerodynamic Flows
NASA Astrophysics Data System (ADS)
Medida, Shivaji
Conventional turbulence models calibrated for fully turbulent boundary layers often over-predict drag and heat transfer on aerodynamic surfaces with partially laminar boundary layers. A robust correlation-based model is developed for use in Reynolds-Averaged Navier-Stokes simulations to predict laminar-to-turbulent transition onset of boundary layers on external aerodynamic surfaces. The new model is derived from an existing transition model for the two-equation k-omega Shear Stress Transport (SST) turbulence model, and is coupled with the one-equation Spalart-Allmaras (SA) turbulence model. The transition model solves two transport equations for intermittency and transition momentum thickness Reynolds number. Experimental correlations and local mean flow quantities are used in the model to account for effects of freestream turbulence level and pressure gradients on transition onset location. Transition onset is triggered by activating intermittency production using a vorticity Reynolds number criterion. In the new model, production and destruction terms of the intermittency equation are modified to improve consistency in the fully turbulent boundary layer post-transition onset, as well as ensure insensitivity to freestream eddy viscosity value specified in the SA model. In the original model, intermittency was used to control production and destruction of turbulent kinetic energy. Whereas, in the new model, only the production of eddy viscosity in SA model is controlled, and the destruction term is not altered. Unlike the original model, the new model does not use an additional correction to intermittency for separation-induced transition. Accuracy of drag predictions are improved significantly with the use of the transition model for several two-dimensional single- and multi-element airfoil cases over a wide range of Reynolds numbers. The new model is able to predict the formation of stable and long laminar separation bubbles on low-Reynolds number airfoils that
The oscillating wing with aerodynamically balanced elevator
NASA Technical Reports Server (NTRS)
Kussner, H G; Schwartz, I
1941-01-01
The two-dimensional problem of the oscillating wing with aerodynamically balanced elevator is treated in the manner that the wing is replaced by a plate with bends and stages and the airfoil section by a mean line consisting of one or more straights. The computed formulas and tables permit, on these premises, the prediction of the pressure distribution and of the aerodynamic reactions of oscillating elevators and tabs with any position of elevator hinge in respect to elevator leading edge.
Means for controlling aerodynamically induced twist
NASA Technical Reports Server (NTRS)
Elber, W. (Inventor)
1982-01-01
A control mechanism which provides active compensation for aerodynamically induced twist deformation of high aspect ratio wings consists of a torque tube, internal to each wing and rigidly attached near the tip of each wing, which is moved by an actuator located in the aircraft fuselage. As changes in the aerodynamic loads on the wings occur the torque tube is rotated to compensate for the induced wing twist.
Chen, Yu; Wang, Wen; Liu, Fen; Tang, Luosheng; Tang, Renhong; Li, Wenjie
2015-10-01
Diabetic retinopathy (DR) is one of the most common complications of diabetes mellitus. But few efficient therapeutic methods have been reported. This study discussed the functions of 9-cis-retinoic acid (9-cis-RA) in sensitizing retinal pericytes to platelet-derived growth factor (PDGF)-BB. Using streptozotocin (STZ)-induced diabetic mice and high glucose-treated bovine retinal pericytes (BRPC), we analyzed the impacts of 9-cis-RA by detecting cell apoptosis via DNA fragmentation assay and detecting related factors through adenovirus or lentivirus infection and western blot. Results showed that in retinas of STZ-induced diabetic mice, 9-cis-RA significantly inhibited expression of SHP-1 (P < 0.01), thus promoting p-AKT and p-ERK1/2, which reflected the improved sensitivity to PDGF-BB. In BRPC, 9-cis-RA also improved sensitivity to PDGF-BB and suppressed cell apoptosis (P < 0.01) via down-regulating SHP-1. Further mechanism analyses showed that the efficient functioning of 9-cis-RA relied on the existence of its receptor, retinoic X receptor α (RXRα), independent of the previous reported protein kinase C delta (PKCδ)/SHP-1 axis. Because 9-cis-RA could not inhibit SHP-1 or improve sensitivity to PDGF-BB when RXRα was knocked down, while it still suppressed SHP-1 after overexpression of PKCδ. Taken together, these results indicated the vital roles of 9-cis-RA in improving sensitivity to PDGF-BB of retinal pericytes in DR, and provided basic evidences of new therapeutic targets like RXRα for further DR treatment. PMID:26310807
Longitudinal aerodynamic parameters of the Kestrel aircraft (XV-6A) extracted from flight data
NASA Technical Reports Server (NTRS)
Suit, W. T.; Williams, J. L.
1973-01-01
Flight-test data have been used to extract the longitudinal aerodynamic parameters of a vectored-thrust aircraft. The results show that deflecting the thrust past 15 has an effect on the pitching-moment derivatives and tends to reduce the static stability. The trend toward reduction in the longitudinal stability also been noted by the pilots conducting the flight tests.
Guarisco, Chiara; Palmisano, Giovanni; Calogero, Giuseppe; Ciriminna, Rosaria; Di Marco, Gaetano; Loddo, Vittorio; Pagliaro, Mario; Parrino, Francesco
2014-10-01
Sensitized P25 TiO2 was prepared by wet impregnation with a home-prepared perylene dye, i.e., N,N'-bis(2-(1-piperazino)ethyl)-3,4,9,10-perylene-tetracarboxylic acid diimide dichloride (PZPER). Energy levels of PZPER were found to be compatible with those of TiO2 allowing fast electron transfer. The obtained catalyst has been characterized and used in the gas-phase partial oxidation of aliphatic primary and secondary alcohols, i.e., methanol, ethanol, and 2-propanol. The reaction was carried out under cut-off (λ > 400 nm) simulated solar radiation in O2 atmosphere. The perylene derivative allowed a good absorbance of visible radiation thanks to its low optical energy gap (2.6 eV) which was evaluated by cyclic voltammetry. The optimal organic sensitizing amount was found to be 5.6 % w/w in terms of yield in carbonyl derivatives. Moreover, no change in reactivity/selectivity was observed after 10-h irradiation thus confirming the catalyst stability. Yields into formaldehyde, acetaldehyde, and acetone were 67, 70, and 96 %, respectively. No significant amounts of organic byproducts were detected but for methanol oxidation, whereas a minor amount of the substrate degraded to CO2. PMID:24469771
Darrieus rotor aerodynamics in turbulent wind
Brahimi, M.T.; Paraschivoiu, I.
1995-05-01
The earlier aerodynamic models for studying vertical axis wind turbines (VAWT`s) are based on constant incident wind conditions and are thus capable of predicting only periodic variations in the loads. The purpose of the present study is to develop a model capable of predicting the aerodynamic loads on the Darrieus rotor in a turbulent wind. This model is based on the double-multiple streamtube method (DMS) and incorporates a stochastic wind model. The method used to simulate turbulent velocity fluctuations is based on the power spectral density. The problem consists in generating a region of turbulent flow with a relevant spectrum and spatial correlation. The first aerodynamic code developed is based on a one-dimensional turbulent wind model. However, since this model ignores the structure of the turbulence in the crossflow plane, an extension to three dimensions has been made. The computer code developed, CARDAAS, has been used to predict aerodynamic loads for the Sandia-17m rotor and compared to CARDAAV results and experimental data. Results have shown that the computed aerodynamic loads have been improved by including stochastic wind into the aerodynamic model.
Fourier functional analysis for unsteady aerodynamic modeling
NASA Technical Reports Server (NTRS)
Lan, C. Edward; Chin, Suei
1991-01-01
A method based on Fourier analysis is developed to analyze the force and moment data obtained in large amplitude forced oscillation tests at high angles of attack. The aerodynamic models for normal force, lift, drag, and pitching moment coefficients are built up from a set of aerodynamic responses to harmonic motions at different frequencies. Based on the aerodynamic models of harmonic data, the indicial responses are formed. The final expressions for the models involve time integrals of the indicial type advocated by Tobak and Schiff. Results from linear two- and three-dimensional unsteady aerodynamic theories as well as test data for a 70-degree delta wing are used to verify the models. It is shown that the present modeling method is accurate in producing the aerodynamic responses to harmonic motions and the ramp type motions. The model also produces correct trend for a 70-degree delta wing in harmonic motion with different mean angles-of-attack. However, the current model cannot be used to extrapolate data to higher angles-of-attack than that of the harmonic motions which form the aerodynamic model. For linear ramp motions, a special method is used to calculate the corresponding frequency and phase angle at a given time. The calculated results from modeling show a higher lift peak for linear ramp motion than for harmonic ramp motion. The current model also shows reasonably good results for the lift responses at different angles of attack.
Sharp Hypervelocity Aerodynamic Research Probe
NASA Technical Reports Server (NTRS)
Bull, Jeffrey; Kolodziej, Paul; Rasky, Daniel J. (Technical Monitor)
1996-01-01
The objective of this flight demonstration is to deploy a slender-body hypervelocity aerodynamic research probe (SHARP) from an orbiting platform using a tether, deorbit and fly it along its aerothermal performance constraint, and recover it intact in mid-air. To accomplish this objective, two flight demonstrations are proposed. The first flight uses a blunt-body, tethered reentry experiment vehicle (TREV) to prove out tethered deployment technology for accurate entries, a complete SHARP electronics suite, and a new soft mid-air helicopter recovery technique. The second flight takes advantage of this launch and recovery capability to demonstrate revolutionary sharp body concepts for hypervelocity vehicles, enabled by new Ultra-High Temperature Ceramics (UHTCs) recently developed by Ames Research Center. Successful demonstration of sharp body hypersonic vehicle technologies could have radical impact on space flight capabilities, including: enabling global reentry cross range capability from Station, eliminating reentry communications blackout, and allowing new highly efficient launch systems incorporating air breathing propulsion and zeroth staging.
Aerodynamic characteristics of French consonants
NASA Astrophysics Data System (ADS)
Demolin, Didier; Hassid, Sergio; Soquet, Alain
2001-05-01
This paper reports some aerodynamic measurements made on French consonants with a group of ten speakers. Speakers were recorded while saying nonsense words in phrases such as papa, dis papa encore. The nonsense words in the study combined each of the French consonants with three vowels /i, a, u/ to from two syllables words with the first syllable being the same as the second. In addition to the audio signal, recordings were made of the oral airflow, the pressure of the air in the pharynx above the vocal folds and the pressure of the air in the trachea just below the vocal folds. The pharyngeal pressure was recorded via a catheter (i.d. 5 mm) passed through the nose so that its open end could be seen in the pharynx below the uvula. The subglottal pressure was recorded via a tracheal puncture between the first and the second rings of the trachea or between the cricoid cartilage and the first tracheal ring. Results compare subglottal presssure, pharyngeal pressure, and airflow values. Comparisons are made between values obtained with male and female subjects and various types of consonants (voiced versus voiceless at the same place of articulation, stops, fricatives, and nasals).
Parachute Aerodynamics From Video Data
NASA Technical Reports Server (NTRS)
Schoenenberger, Mark; Queen, Eric M.; Cruz, Juan R.
2005-01-01
A new data analysis technique for the identification of static and dynamic aerodynamic stability coefficients from wind tunnel test video data is presented. This new technique was applied to video data obtained during a parachute wind tunnel test program conducted in support of the Mars Exploration Rover Mission. Total angle-of-attack data obtained from video images were used to determine the static pitching moment curve of the parachute. During the original wind tunnel test program the static pitching moment curve had been determined by forcing the parachute to a specific total angle-of -attack and measuring the forces generated. It is shown with the new technique that this parachute, when free to rotate, trims at an angle-of-attack two degrees lower than was measured during the forced-angle tests. An attempt was also made to extract pitch damping information from the video data. Results suggest that the parachute is dynamically unstable at the static trim point and tends to become dynamically stable away from the trim point. These trends are in agreement with limit-cycle-like behavior observed in the video. However, the chaotic motion of the parachute produced results with large uncertainty bands.
Aerodynamics of a hybrid airship
NASA Astrophysics Data System (ADS)
Andan, Amelda Dianne; Asrar, Waqar; Omar, Ashraf A.
2012-06-01
The objective of this paper is to present the results of a numerical study of the aerodynamic parameters of a wingless and a winged-hull airship. The total forces and moment coefficients of the airships have been computed over a range of angles. The results obtained show that addition of a wing to a conventional airship increases the lift has three times the lifting force at positive angle of attack as compared to a wingless airship whereas the drag increases in the range of 19% to 58%. The longitudinal and directional stabilities were found to be statically stable, however, both the conventional airship and the hybrid or winged airships were found to have poor rolling stability. Wingless airship has slightly higher longitudinal stability than a winged airship. The winged airship has better directional stability than the wingless airship. The wingless airship only possesses static rolling stability in the range of yaw angles of -5° to 5°. On the contrary, the winged airship initially tested does not possess rolling stability at all. Computational fluid dynamics (CFD) simulations show that modifications to the wing placement and its dihedral have strong positive effect on the rolling stability. Raising the wings to the center of gravity and introducing a dihedral angle of 5° stabilizes the rolling motion of the winged airship.
Aerodynamics of Unsteady Sailing Kinetics
NASA Astrophysics Data System (ADS)
Keil, Colin; Schutt, Riley; Borshoff, Jennifer; Alley, Philip; de Zegher, Maximilien; Williamson, Chk
2015-11-01
In small sailboats, the bodyweight of the sailor is proportionately large enough to induce significant unsteady motion of the boat and sail. Sailors use a variety of kinetic techniques to create sail dynamics which can provide an increment in thrust, thereby increasing the boatspeed. In this study, we experimentally investigate the unsteady aerodynamics associated with two techniques, ``upwind leech flicking'' and ``downwind S-turns''. We explore the dynamics of an Olympic class Laser sailboat equipped with a GPS, IMU, wind sensor, and camera array, sailed expertly by a member of the US Olympic team. The velocity heading of a sailing boat is oriented at an apparent wind angle to the flow. In contrast to classic flapping propulsion, the heaving of the sail section is not perpendicular to the sail's motion through the air. This leads to heave with components parallel and perpendicular to the incident flow. The characteristic motion is recreated in a towing tank where the vortex structures generated by a representative 2-D sail section are observed using Particle Image Velocimetry and the measurement of thrust and lift forces. Amongst other results, we show that the increase in driving force, generated due to heave, is larger for greater apparent wind angles.
Cobb, Laura J.; Lee, Changhan; Xiao, Jialin; Yen, Kelvin; Wong, Richard G.; Nakamura, Hiromi K.; Mehta, Hemal H.; Gao, Qinglei; Ashur, Carmel; Huffman, Derek M.; Wan, Junxiang; Muzumdar, Radhika; Barzilai, Nir; Cohen, Pinchas
2016-01-01
Mitochondria are key players in aging and in the pathogenesis of age-related diseases. Recent mitochondrial transcriptome analyses revealed the existence of multiple small mRNAs transcribed from mitochondrial DNA (mtDNA). Humanin (HN), a peptide encoded in the mtDNA 16S ribosomal RNA region, is a neuroprotective factor. An in silico search revealed six additional peptides in the same region of mtDNA as humanin; we named these peptides small humanin-like peptides (SHLPs). We identified the functional roles for these peptides and the potential mechanisms of action. The SHLPs differed in their ability to regulate cell viability in vitro. We focused on SHLP2 and SHLP3 because they shared similar protective effects with HN. Specifically, they significantly reduced apoptosis and the generation of reactive oxygen species, and improved mitochondrial metabolism in vitro. SHLP2 and SHLP3 also enhanced 3T3-L1 pre-adipocyte differentiation. Systemic hyperinsulinemic-euglycemic clamp studies showed that intracerebrally infused SHLP2 increased glucose uptake and suppressed hepatic glucose production, suggesting that it functions as an insulin sensitizer both peripherally and centrally. Similar to HN, the levels of circulating SHLP2 were found to decrease with age. These results suggest that mitochondria play critical roles in metabolism and survival through the synthesis of mitochondrial peptides, and provide new insights into mitochondrial biology with relevance to aging and human biology. PMID:27070352
Cobb, Laura J; Lee, Changhan; Xiao, Jialin; Yen, Kelvin; Wong, Richard G; Nakamura, Hiromi K; Mehta, Hemal H; Gao, Qinglei; Ashur, Carmel; Huffman, Derek M; Wan, Junxiang; Muzumdar, Radhika; Barzilai, Nir; Cohen, Pinchas
2016-04-01
Mitochondria are key players in aging and in the pathogenesis of age-related diseases. Recent mitochondrial transcriptome analyses revealed the existence of multiple small mRNAs transcribed from mitochondrial DNA (mtDNA). Humanin (HN), a peptide encoded in the mtDNA 16S ribosomal RNA region, is a neuroprotective factor. An in silico search revealed six additional peptides in the same region of mtDNA as humanin; we named these peptides small humanin-like peptides (SHLPs). We identified the functional roles for these peptides and the potential mechanisms of action. The SHLPs differed in their ability to regulate cell viability in vitro. We focused on SHLP2 and SHLP3 because they shared similar protective effects with HN. Specifically, they significantly reduced apoptosis and the generation of reactive oxygen species, and improved mitochondrial metabolism in vitro. SHLP2 and SHLP3 also enhanced 3T3-L1 pre-adipocyte differentiation. Systemic hyperinsulinemic-euglycemic clamp studies showed that intracerebrally infused SHLP2 increased glucose uptake and suppressed hepatic glucose production, suggesting that it functions as an insulin sensitizer both peripherally and centrally. Similar to HN, the levels of circulating SHLP2 were found to decrease with age. These results suggest that mitochondria play critical roles in metabolism and survival through the synthesis of mitochondrial peptides, and provide new insights into mitochondrial biology with relevance to aging and human biology. PMID:27070352
Takayama, Kazuo; Morisaki, Yuta; Kuno, Shuichi; Nagamoto, Yasuhito; Harada, Kazuo; Furukawa, Norihisa; Ohtaka, Manami; Nishimura, Ken; Imagawa, Kazuo; Sakurai, Fuminori; Tachibana, Masashi; Sumazaki, Ryo; Noguchi, Emiko; Nakanishi, Mahito; Hirata, Kazumasa; Kawabata, Kenji; Mizuguchi, Hiroyuki
2014-01-01
Interindividual differences in hepatic metabolism, which are mainly due to genetic polymorphism in its gene, have a large influence on individual drug efficacy and adverse reaction. Hepatocyte-like cells (HLCs) differentiated from human induced pluripotent stem (iPS) cells have the potential to predict interindividual differences in drug metabolism capacity and drug response. However, it remains uncertain whether human iPSC-derived HLCs can reproduce the interindividual difference in hepatic metabolism and drug response. We found that cytochrome P450 (CYP) metabolism capacity and drug responsiveness of the primary human hepatocytes (PHH)-iPS-HLCs were highly correlated with those of PHHs, suggesting that the PHH-iPS-HLCs retained donor-specific CYP metabolism capacity and drug responsiveness. We also demonstrated that the interindividual differences, which are due to the diversity of individual SNPs in the CYP gene, could also be reproduced in PHH-iPS-HLCs. We succeeded in establishing, to our knowledge, the first PHH-iPS-HLC panel that reflects the interindividual differences of hepatic drug-metabolizing capacity and drug responsiveness. PMID:25385620
Amatore, Donatella; Sgarbanti, Rossella; Aquilano, Katia; Baldelli, Sara; Limongi, Dolores; Civitelli, Livia; Nencioni, Lucia; Garaci, Enrico; Ciriolo, Maria Rosa; Palamara, Anna Teresa
2015-01-01
An overproduction of reactive oxygen species (ROS) mediated by NADPH oxidase 2 (NOX2) has been related to airway inflammation typical of influenza infection. Virus-induced oxidative stress may also control viral replication, but the mechanisms underlying ROS production, as well as their role in activating intracellular pathways and specific steps of viral life cycle under redox control have to be fully elucidated. In this study, we demonstrate that influenza A virus infection of lung epithelial cells causes a significant ROS increase that depends mainly on NOX4, which is upregulated at both mRNA and protein levels, while the expression of NOX2, the primary source of ROS in inflammatory cells, is downregulated. Inhibition of NOX4 activity through chemical inhibitors or RNA silencing blocks the ROS increase, prevents MAPK phosphorylation, and inhibits viral ribonucleoprotein (vRNP) nuclear export and viral release. Overall these data, obtained in cell lines and primary culture, describe a so far unrecognized role for NOX4-derived ROS in activating redox-regulated intracellular pathways during influenza virus infection and highlight their relevance in controlling specific steps of viral replication in epithelial cells. Pharmacological modulation of NOX4-mediated ROS production may open the way for new therapeutic approaches to fighting influenza by targeting cell and not the virus. PMID:25154738
Joshi, Prakash C; Keane, Thomas C
2010-10-01
DNA and RNA undergo photodegradation in UVC (200-290nm) due to direct absorption by the purine and pyrimidine bases. Limited effects are observed under UVB (290-320nm) or UVA (320-400nm). We have observed that an endogenous photosensitizer, riboflavin (RF), upon exposure to UVB or UVA can extensively damage the DNA and RNA bases. Guanine, uracil, thymine, adenine and cytosine were degraded by 100%, 82%, 60.4%, 46.3% and 10.3% under UVA (12J) and by 100%, 54.1%, 38.9%, 42.2% and <1.0% under UVB (6J), respectively. Guanosine and deoxyguanosine were degraded by 98±1.0% and 80±1.0% under UVA (4J) and UVB (12J), respectively. With an exception of GMP (53-82%), dGMP (51-88%) and to some extent TMP (3-4%) the remaining nucleosides and nucleotides were resistant to RF-induced photodecomposition. The photodegradation of G derivatives by RF was 2-fold higher than a well known photodynamic agent rose bengal. A comparison of the intensities of UVA and UVB sources used in this study with natural sunlight suggests that exposure with the latter along with an endogenous photosensitizer can have similar effects on DNA and RNA depending upon the duration of exposure. PMID:20816939
Ponzoni, Luisa; Sala, Mariaelvina; Braida, Daniela
2016-11-01
Little is known about the pharmacological effects of amphetamine derivatives. In the present study, the effect on social preference and anxiety-like behavior of 2,5-dimetoxy-4-bromo-amphetamine hydrobromide (DOB) and para-methoxyamphetamine (PMA), in comparison with 3,4 methylenedioxymethamphetamine (MDMA) was investigated in zebrafish, an emerging model to study emotional behavior in an inexpensive and quick manner. DOB (0.05-2mg/kg), PMA (0.0005-2mg/kg) or MDMA (0.25-20mg/kg), given i.m. to adult zebrafish, progressively increased the time spent in the proximity of nacre fish picture in a social preference test. However, high doses were ineffective. Similarly, in the novel tank diving and light-dark tests the compounds elicited a progressive anxiolytic effect in terms of time spent in the upper half of the tank and in the light compartment, respectively. All the above effects were interpolated by symmetrical parabolas. The 5-HT2A/C antagonist ritanserin (0.025-2.5mg/kg) in association with the maximal effective dose of MDMA, DOB and PMA blocked both the social and anxiolytic effect. Taken together these findings demonstrate for the first time the prosocial and anxiolytic properties of DOB and PMA and focus on the mechanisms of their action through the serotonergic-like system suggesting a potential clinical application. PMID:27506653
Mebane, C.A.
2010-01-01
Criteria to protect aquatic life are intended to protect diverse ecosystems, but in practice are usually developed from compilations of single-species toxicity tests using standard test organisms that were tested in laboratory environments. Species sensitivity distributions (SSDs) developed from these compilations are extrapolated to set aquatic ecosystem criteria. The protectiveness of the approach was critically reviewed with a chronic SSD for cadmium comprising 27 species within 21 genera. Within the data set, one genus had lower cadmium effects concentrations than the SSD fifth percentile-based criterion, so in theory this genus, the amphipod Hyalella, could be lost or at least allowed some level of harm by this criteria approach. However, population matrix modeling projected only slightly increased extinction risks for a temperate Hyalella population under scenarios similar to the SSD fifth percentile criterion. The criterion value was further compared to cadmium effects concentrations in ecosystem experiments and field studies. Generally, few adverse effects were inferred from ecosystem experiments at concentrations less than the SSD fifth percentile criterion. Exceptions were behavioral impairments in simplified food web studies. No adverse effects were apparent in field studies under conditions that seldom exceeded the criterion. At concentrations greater than the SSD fifth percentile, the magnitudes of adverse effects in the field studies were roughly proportional to the laboratory-based fraction of species with adverse effects in the SSD. Overall, the modeling and field validation comparisons of the chronic criterion values generally supported the relevance and protectiveness of the SSD fifth percentile approach with cadmium. ?? 2009 Society for Risk Analysis.
NASA Technical Reports Server (NTRS)
Baker, A. J.; Iannelli, G. S.; Manhardt, Paul D.; Orzechowski, J. A.
1993-01-01
This report documents the user input and output data requirements for the FEMNAS finite element Navier-Stokes code for real-gas simulations of external aerodynamics flowfields. This code was developed for the configuration aerodynamics branch of NASA ARC, under SBIR Phase 2 contract NAS2-124568 by Computational Mechanics Corporation (COMCO). This report is in two volumes. Volume 1 contains the theory for the derived finite element algorithm and describes the test cases used to validate the computer program described in the Volume 2 user guide.
X-38 NASA/DLR/ESA-Dassault Aviation Integrated Aerodynamic and Aerothermodynamic Activities
NASA Technical Reports Server (NTRS)
Labbe, Steve G.; Perez, Leo F.; Fitzgerald, Steve; Longo, Jose; Rapuc, Marc; Molina, Rafael; Nicholson, Leonard S. (Technical Monitor)
1999-01-01
The characterization of the aeroshape selected for the X-38 [Crew Return Vehicle (CRV) demonstrator] is presently being performed as a cooperative endeavour between NASA, DLR (through its TETRA Program), and European Space Agency (ESA) with Dassault Aviation integrating the aerodynamic and aerothermodynamic activities. The methodologies selected for characterizing the aerodynamic and aerothermodynamic environment of the X-38 are presented. Also, the implications for related disciplines such as Guidance Navigation and Control (GN&C) with its corresponding Flight Control System (FCS), Structural, and Thermal Protection System (TPS) design are discussed. An attempt is made at defining the additional activities required to support the design of a derived operational CRV.
Missile aerodynamics; Proceedings of the Conference, Monterey, CA, Oct. 31-Nov. 2, 1988
Mendenhall, M.R.; Nixon, D.; Dillenius, M.F.E.
1989-01-01
The present conference discusses the development status of predictive capabilities for missile aerodynamic characteristics, the application of experimental techniques to missile-release problems, prospective high-performance missile designs, the use of lateral jet controls for missile guidance, and the integration of stores on modern tactical aircraft. Also discussed are semiempirical aerodynamic methods for preliminary design, high angle-of-attack behavior for an advanced missile, and the dynamic derivatives of missiles and fighter-type configurations at high angles-of-attack.
An arbitrary grid CFD algorithm for configuration aerodynamics analysis. Volume 2: FEMNAS user guide
NASA Technical Reports Server (NTRS)
Manhardt, Paul D.; Orzechowski, J. A.; Baker, A. J.
1992-01-01
This report documents the user input and output data requirements for the FEMNAS finite element Navier-Stokes code for real-gas simulations of external aerodynamics flowfields. This code was developed for the configuration aerodynamics branch of NASA ARC, under SBIR Phase 2 contract NAS2-124568 by Computational Mechanics Corporation (COMCO). This report is in two volumes. Volume 1 contains the theory for the derived finite element algorithm and describes the test cases used to validate the computer program described in the Volume 2 user guide.
Martin, Emily B.; Williams, Angela; Heidel, Eric; Macy, Sallie; Kennel, Stephen J.; Wall, Jonathan S.
2013-06-21
Highlights: •Polybasic peptide p5 binds human light chain amyloid extracts. •The binding of p5 with amyloid involves both glycosaminoglycans and fibrils. •Heparinase treatment led to a correlation between p5 binding and fibril content. •p5 binding to AL amyloid requires electrostatic interactions. -- Abstract: In previously published work, we have described heparin-binding synthetic peptides that preferentially recognize amyloid deposits in a mouse model of reactive systemic (AA) amyloidosis and can be imaged by using positron and single photon emission tomographic imaging. We wanted to extend these findings to the most common form of visceral amyloidosis, namely light chain (AL); however, there are no robust experimental animal models of AL amyloidosis. To further define the binding of the lead peptide, p5, to AL amyloid, we characterized the reactivity in vitro of p5 with in situ and patient-derived AL amyloid extracts which contain both hypersulfated heparan sulfate proteoglycans as well as amyloid fibrils. Histochemical staining demonstrated that the peptide specifically localized with tissue-associated AL amyloid deposits. Although we anticipated that p5 would undergo electrostatic interactions with the amyloid-associated glycosaminoglycans expressing heparin-like side chains, no significant correlation between peptide binding and glycosaminoglycan content within amyloid extracts was observed. In contrast, following heparinase I treatment, although overall binding was reduced, a positive correlation between peptide binding and amyloid fibril content became evident. This interaction was further confirmed using synthetic light chain fibrils that contain no carbohydrates. These data suggest that p5 can bind to both the sulfated glycosaminoglycans and protein fibril components of AL amyloid. Understanding these complex electrostatic interactions will aid in the optimization of synthetic peptides for use as amyloid imaging agents and potentially as
NASA Technical Reports Server (NTRS)
Lummus, J. R.; Joyce, G. T.; Omalley, C. D.
1980-01-01
The ability of current methodologies to accurately predict the aerodynamic characteristics identified as uncertainties was evaluated for two aircraft configurations. The two wind tunnel models studied horizontal altitude takeoff and landing V/STOL fighter aircraft derivatives.
Modeling Powered Aerodynamics for the Orion Launch Abort Vehicle Aerodynamic Database
NASA Technical Reports Server (NTRS)
Chan, David T.; Walker, Eric L.; Robinson, Philip E.; Wilson, Thomas M.
2011-01-01
Modeling the aerodynamics of the Orion Launch Abort Vehicle (LAV) has presented many technical challenges to the developers of the Orion aerodynamic database. During a launch abort event, the aerodynamic environment around the LAV is very complex as multiple solid rocket plumes interact with each other and the vehicle. It is further complicated by vehicle separation events such as between the LAV and the launch vehicle stack or between the launch abort tower and the crew module. The aerodynamic database for the LAV was developed mainly from wind tunnel tests involving powered jet simulations of the rocket exhaust plumes, supported by computational fluid dynamic simulations. However, limitations in both methods have made it difficult to properly capture the aerodynamics of the LAV in experimental and numerical simulations. These limitations have also influenced decisions regarding the modeling and structure of the aerodynamic database for the LAV and led to compromises and creative solutions. Two database modeling approaches are presented in this paper (incremental aerodynamics and total aerodynamics), with examples showing strengths and weaknesses of each approach. In addition, the unique problems presented to the database developers by the large data space required for modeling a launch abort event illustrate the complexities of working with multi-dimensional data.
NASA Technical Reports Server (NTRS)
McMillin, S. Naomi (Editor)
1999-01-01
NASA's High-Speed Research Program sponsored the 1998 Aerodynamic Performance Technical Review on February 9-13, in Los Angeles, California. The review was designed to bring together NASA and industry High-Speed Civil Transport (HSCT) Aerodynamic Performance technology development participants in areas of Configuration Aerodynamics (transonic and supersonic cruise drag prediction and minimization), High-Lift, and Flight Controls. The review objectives were to (1) report the progress and status of HSCT aerodynamic performance technology development; (2) disseminate this technology within the appropriate technical communities; and (3) promote synergy among the scientists and engineers working HSCT aerodynamics. In particular, single and multi-point optimized HSCT configurations, HSCT high-lift system performance predictions, and HSCT simulation results were presented along with executive summaries for all the Aerodynamic Performance technology areas. The HSR Aerodynamic Performance Technical Review was held simultaneously with the annual review of the following airframe technology areas: Materials and Structures, Environmental Impact, Flight Deck, and Technology Integration. Thus, a fourth objective of the Review was to promote synergy between the Aerodynamic Performance technology area and the other technology areas of the HSR Program.
NASA Technical Reports Server (NTRS)
Hahne, David E. (Editor)
1999-01-01
NASA's High-Speed Research Program sponsored the 1999 Aerodynamic Performance Technical Review on February 8-12, 1999 in Anaheim, California. The review was designed to bring together NASA and industry High-Speed Civil Transport (HSCT) Aerodynamic Performance technology development participants in the areas of Configuration Aerodynamics (transonic and supersonic cruise drag prediction and minimization), High Lift, and Flight Controls. The review objectives were to (1) report the progress and status of HSCT aerodynamic performance technology development; (2) disseminate this technology within the appropriate technical communities; and (3) promote synergy among the scientists and engineers working on HSCT aerodynamics. In particular, single and midpoint optimized HSCT configurations, HSCT high-lift system performance predictions, and HSCT simulation results were presented, along with executive summaries for all the Aerodynamic Performance technology areas. The HSR Aerodynamic Performance Technical Review was held simultaneously with the annual review of the following airframe technology areas: Materials and Structures, Environmental Impact, Flight Deck, and Technology Integration. Thus, a fourth objective of the Review was to promote synergy between the Aerodynamic Performance technology area and the other technology areas of the HSR Program. This Volume 1/Part 2 publication covers the design optimization and testing sessions.
NASA Technical Reports Server (NTRS)
McMillin, S. Naomi (Editor)
1999-01-01
NASA's High-Speed Research Program sponsored the 1998 Aerodynamic Performance Technical Review on February 9-13, in Los Angeles, California. The review was designed to bring together NASA and industry HighSpeed Civil Transport (HSCT) Aerodynamic Performance technology development participants in areas of. Configuration Aerodynamics (transonic and supersonic cruise drag prediction and minimization), High-Lift, and Flight Controls. The review objectives were to: (1) report the progress and status of HSCT aerodynamic performance technology development; (2) disseminate this technology within the appropriate technical communities; and (3) promote synergy among the scientists and engineers working HSCT aerodynamics. In particular, single and multi-point optimized HSCT configurations, HSCT high-lift system performance predictions, and HSCT simulation results were presented along with executive summaries for all the Aerodynamic Performance technology areas. The HSR Aerodynamic Performance Technical Review was held simultaneously with the annual review of the following airframe technology areas: Materials and Structures, Environmental Impact, Flight Deck, and Technology Integration. Thus, a fourth objective of the Review was to promote synergy between the Aerodynamic Performance technology area and the other technology areas of the HSR Program.
Sensitivity Analysis of Wing Aeroelastic Responses
NASA Technical Reports Server (NTRS)
Issac, Jason Cherian
1995-01-01
Design for prevention of aeroelastic instability (that is, the critical speeds leading to aeroelastic instability lie outside the operating range) is an integral part of the wing design process. Availability of the sensitivity derivatives of the various critical speeds with respect to shape parameters of the wing could be very useful to a designer in the initial design phase, when several design changes are made and the shape of the final configuration is not yet frozen. These derivatives are also indispensable for a gradient-based optimization with aeroelastic constraints. In this study, flutter characteristic of a typical section in subsonic compressible flow is examined using a state-space unsteady aerodynamic representation. The sensitivity of the flutter speed of the typical section with respect to its mass and stiffness parameters, namely, mass ratio, static unbalance, radius of gyration, bending frequency, and torsional frequency is calculated analytically. A strip theory formulation is newly developed to represent the unsteady aerodynamic forces on a wing. This is coupled with an equivalent plate structural model and solved as an eigenvalue problem to determine the critical speed of the wing. Flutter analysis of the wing is also carried out using a lifting-surface subsonic kernel function aerodynamic theory (FAST) and an equivalent plate structural model. Finite element modeling of the wing is done using NASTRAN so that wing structures made of spars and ribs and top and bottom wing skins could be analyzed. The free vibration modes of the wing obtained from NASTRAN are input into FAST to compute the flutter speed. An equivalent plate model which incorporates first-order shear deformation theory is then examined so it can be used to model thick wings, where shear deformations are important. The sensitivity of natural frequencies to changes in shape parameters is obtained using ADIFOR. A simple optimization effort is made towards obtaining a minimum weight
NASA Astrophysics Data System (ADS)
Kurylyk, B. L.; MacQuarrie, K. T. B.; Caissie, D.; McKenzie, J. M.
2015-05-01
Climate change is expected to increase stream temperatures and the projected warming may alter the spatial extent of habitat for cold-water fish and other aquatic taxa. Recent studies have proposed that stream thermal sensitivities, derived from short-term air temperature variations, can be employed to infer future stream warming due to long-term climate change. However, this approach does not consider the potential for streambed heat fluxes to increase due to gradual warming of the shallow subsurface. The temperature of shallow groundwater is particularly important for the thermal regimes of groundwater-dominated streams and rivers. Also, recent studies have investigated how land surface perturbations, such as wildfires or timber harvesting, can influence stream temperatures by changing stream surface heat fluxes, but these studies have typically not considered how these surface disturbances can also alter shallow groundwater temperatures and streambed heat fluxes. In this study, several analytical solutions to the one-dimensional unsteady advection-diffusion equation for subsurface heat transport are employed to estimate the timing and magnitude of groundwater temperature changes due to seasonal and long-term variability in land surface temperatures. Groundwater thermal sensitivity formulae are proposed that accommodate different surface warming scenarios. The thermal sensitivity formulae suggest that shallow groundwater will warm in response to climate change and other surface perturbations, but the timing and magnitude of the subsurface warming depends on the rate of surface warming, subsurface thermal properties, bulk aquifer depth, and groundwater velocity. The results also emphasize the difference between the thermal sensitivity of shallow groundwater to short-term (e.g., seasonal) and long-term (e.g., multi-decadal) land surface-temperature variability, and thus demonstrate the limitations of using short-term air and water temperature records to project
Aerodynamic Parameter Identification of a Venus Lander
NASA Astrophysics Data System (ADS)
Sykes, Robert A.
An analysis was conducted to identify the parameters of an aerodynamic model for a Venus lander based on experimental free-flight data. The experimental free-flight data were collected in the NASA Langley 20-ft Vertical Spin Tunnel with a 25-percent Froude-scaled model. The experimental data were classified based on the wind tunnel run type: runs where the lander model was unperturbed over the course of the run, and runs were the model was perturbed (principally in pitch, yaw, and roll) by the wind tunnel operator. The perturbations allow for data to be obtained at higher wind angles and rotation rates than those available from the unperturbed data. The model properties and equations of motion were used to determine experimental values for the aerodynamic coefficients. An aerodynamic model was selected using a priori knowledge of axisymmetric blunt entry vehicles. The least squares method was used to estimate the aerodynamic parameters. Three sets of results were obtained from the following data sets: perturbed, unperturbed, and the combination of both. The combined data set was selected for the final set of aerodynamic parameters based on the quality of the results. The identified aerodynamic parameters are consistent with that of the static wind tunnel data. Reconstructions, of experimental data not used in the parameter identification analyses, achieved similar residuals as those with data used to identify the parameters. Simulations of the experimental data, using the identified parameters, indicate that the aerodynamic model used is incapable of replicating the limit cycle oscillations with stochastic peak amplitudes observed during the test.
NASA Technical Reports Server (NTRS)
Baize, Daniel G. (Editor)
1999-01-01
The High-Speed Research Program and NASA Langley Research Center sponsored the NASA High-Speed Research Program Aerodynamic Performance Workshop on February 25-28, 1997. The workshop was designed to bring together NASA and industry High-Speed Civil Transport (HSCT) Aerodynamic Performance technology development participants in area of Configuration Aerodynamics (transonic and supersonic cruise drag prediction and minimization), High-Lift, Flight Controls, Supersonic Laminar Flow Control, and Sonic Boom Prediction. The workshop objectives were to (1) report the progress and status of HSCT aerodyamic performance technology development; (2) disseminate this technology within the appropriate technical communities; and (3) promote synergy among the scientist and engineers working HSCT aerodynamics. In particular, single- and multi-point optimized HSCT configurations, HSCT high-lift system performance predictions, and HSCT Motion Simulator results were presented along with executive summaries for all the Aerodynamic Performance technology areas.
The predicted effect of aerodynamic detuning on coupled bending-torsion unstalled supersonic flutter
NASA Technical Reports Server (NTRS)
Hoyniak, D.; Fleeter, S.
1986-01-01
A mathematical model is developed to predict the enhanced coupled bending-torsion unstalled supersonic flutter stability due to alternate circumferential spacing aerodynamic detuning of a turbomachine rotor. The translational and torsional unsteady aerodynamic coefficients are developed in terms of influence coefficients, with the coupled bending-torsion stability analysis developed by considering the coupled equations of motion together with the unsteady aerodynamic loading. The effect of this aerodynamic detuning on coupled bending-torsion unstalled supersonic flutter as well as the verification of the modeling are then demonstrated by considering an unstable 12 bladed rotor, with Verdon's uniformly spaced Cascade B flow geometry as a baseline. However, with the elastic axis and center of gravity at 60 percent of the chord, this type of aerodynamic detuning has a minimal effect on stability. For both uniform and nonuniform circumferentially space rotors, a single degree of freedom torsion mode analysis was shown to be appropriate for values of the bending-torsion natural frequency ratio lower than 0.6 and higher 1.2. When the elastic axis and center of gravity are not coincident, the effect of detuning on cascade stability was found to be very sensitive to the location of the center of gravity with respect to the elastic axis. In addition, it was determined that when the center of gravity was forward of an elastic axis located at midchord, a single degree of freedom torsion model did not accurately predict cascade stability.
Aerodynamic heating in hypersonic flows
NASA Technical Reports Server (NTRS)
Reddy, C. Subba
1993-01-01
Aerodynamic heating in hypersonic space vehicles is an important factor to be considered in their design. Therefore the designers of such vehicles need reliable heat transfer data in this respect for a successful design. Such data is usually produced by testing the models of hypersonic surfaces in wind tunnels. Most of the hypersonic test facilities at present are conventional blow-down tunnels whose run times are of the order of several seconds. The surface temperatures on such models are obtained using standard techniques such as thin-film resistance gages, thin-skin transient calorimeter gages and coaxial thermocouple or video acquisition systems such as phosphor thermography and infrared thermography. The data are usually reduced assuming that the model behaves like a semi-infinite solid (SIS) with constant properties and that heat transfer is by one-dimensional conduction only. This simplifying assumption may be valid in cases where models are thick, run-times short, and thermal diffusivities small. In many instances, however, when these conditions are not met, the assumption may lead to significant errors in the heat transfer results. The purpose of the present paper is to investigate this aspect. Specifically, the objectives are as follows: (1) to determine the limiting conditions under which a model can be considered a semi-infinite body; (2) to estimate the extent of errors involved in the reduction of the data if the models violate the assumption; and (3) to come up with correlation factors which when multiplied by the results obtained under the SIS assumption will provide the results under the actual conditions.
The aerodynamics of insect flight.
Sane, Sanjay P
2003-12-01
The flight of insects has fascinated physicists and biologists for more than a century. Yet, until recently, researchers were unable to rigorously quantify the complex wing motions of flapping insects or measure the forces and flows around their wings. However, recent developments in high-speed videography and tools for computational and mechanical modeling have allowed researchers to make rapid progress in advancing our understanding of insect flight. These mechanical and computational fluid dynamic models, combined with modern flow visualization techniques, have revealed that the fluid dynamic phenomena underlying flapping flight are different from those of non-flapping, 2-D wings on which most previous models were based. In particular, even at high angles of attack, a prominent leading edge vortex remains stably attached on the insect wing and does not shed into an unsteady wake, as would be expected from non-flapping 2-D wings. Its presence greatly enhances the forces generated by the wing, thus enabling insects to hover or maneuver. In addition, flight forces are further enhanced by other mechanisms acting during changes in angle of attack, especially at stroke reversal, the mutual interaction of the two wings at dorsal stroke reversal or wing-wake interactions following stroke reversal. This progress has enabled the development of simple analytical and empirical models that allow us to calculate the instantaneous forces on flapping insect wings more accurately than was previously possible. It also promises to foster new and exciting multi-disciplinary collaborations between physicists who seek to explain the phenomenology, biologists who seek to understand its relevance to insect physiology and evolution, and engineers who are inspired to build micro-robotic insects using these principles. This review covers the basic physical principles underlying flapping flight in insects, results of recent experiments concerning the aerodynamics of insect flight, as well
Aircraft aerodynamic prediction method for V/STOL transition including flow separation
NASA Technical Reports Server (NTRS)
Gilmer, B. R.; Miner, G. A.; Bristow, D. R.
1983-01-01
A numerical procedure was developed for the aerodynamic force and moment analysis of V/STOL aircraft operating in the transition regime between hover and conventional forward flight. The trajectories, cross sectional area variations, and mass entrainment rates of the jets are calculated by the Adler-Baron Jet-in-Crossflow Program. The inviscid effects of the interaction between the jets and airframe on the aerodynamic properties are determined by use of the MCAIR 3-D Subsonic properties are determined by use of the MCAIR 3-D Subsonic Potential Flow Program, a surface panel method. In addition, the MCAIR 3-D Geometry influence Coefficient Program is used to calculate a matrix of partial derivatives that represent the rate of change of the inviscid aerodynamic properties with respect to arbitrary changes in the effective wing shape.
Unsteady aerodynamic analysis of space shuttle vehicles. Part 1: Summary report
NASA Technical Reports Server (NTRS)
Ericsson, L. E.; Reding, J. P.
1973-01-01
An analysis of the unsteady aerodynamics of space shuttle vehicles was performed. The results show that slender wing theory can be modified to give the potential flow static and dynamic characteristics over a large Mach number range from M = 0 to M 1. A semi-empirical analytic approximation is derived for the loads induced by the leading edge vortex; and it is shown that the developed analytic technique gives good prediction of experimentally determined steady and unsteady delta wing aerodynamics, including the effects of leading edge roundness. At supersonic speeds, attached leading edge flow is established and shock-induced flow separation effects become of concern. Analysis of experimental results for a variety of boost configurations led to a definition of the main features of the flow interference effects between orbiter (delta wing) and booster. The effects of control deflection on the unsteady aerodynamics of the delta-wing orbiter were also evaluated.
The aerodynamic cost of flight in bats--comparing theory with measurement
NASA Astrophysics Data System (ADS)
von Busse, Rhea; Waldman, Rye M.; Swartz, Sharon M.; Breuer, Kenneth S.
2012-11-01
Aerodynamic theory has long been used to predict the aerodynamic power required for animal flight. However, even though the actuator disk model does not account for the flapping motion of a wing, it is used for lack of any better model. The question remains: how close are these predictions to reality? We designed a study to compare predicted aerodynamic power to measured power from the kinetic energy contained in the wake shed behind a bat flying in a wind tunnel. A high-accuracy displaced light-sheet stereo PIV system was used in the Trefftz plane to capture the wake behind four bats flown over a range of flight speeds (1-6m/s). The total power in the wake was computed from the wake vorticity and these estimates were compared with the power predicted using Pennycuick's model for bird flight as well as estimates derived from measurements of the metabolic cost of flight, previously acquired from the same individuals.
Wing motion transformation to evaluate aerodynamic coupling in flapping wing flight.
Faruque, Imraan A; Humbert, J Sean
2014-12-21
Whether the remarkable flight performance of insects is because the animals leverage inherent physics at this scale or because they employ specialized neural feedback mechanisms is an active research question. In this study, an empirically derived aerodynamics model is used with a transformation involving a delay and a rotation to identify a class of kinematics that provide favorable roll-yaw coupling. The transformation is also used to transform both synthetic and experimentally measured wing motions onto the manifold representing proverse yaw and to quantify the degree to which freely flying insects make use of passive aerodynamic mechanisms to provide proverse roll-yaw turn coordination. The transformation indicates that recorded insect kinematics do act to provide proverse yaw for a variety of maneuvers. This finding suggests that passive aerodynamic mechanisms can act to reduce the neural feedback demands of an insect׳s flight control strategy. PMID:25128237
NASA Technical Reports Server (NTRS)
Rais-Rohani, Masoud
1991-01-01
In this paper an effort is made to improve the analytical open-loop flutter predictions for the Active Flexible Wing wind-tunnel model using a sensitivity based optimization approach. The sensitivity derivatives of the flutter frequency and dynamic pressure of the model with respect to the lag terms appearing in the Roger's unsteady aerodynamics approximations are evaluated both analytical and by finite differences. Then, the Levenberg-Marquardt method is used to find the optimum values for these lag-terms. The results obtained here agree much better with the experimental (wind tunnel) results than those found in the previous studies.
Domain decomposition for aerodynamic and aeroacoustic analyses, and optimization
NASA Technical Reports Server (NTRS)
Baysal, Oktay
1995-01-01
The overarching theme was the domain decomposition, which intended to improve the numerical solution technique for the partial differential equations at hand; in the present study, those that governed either the fluid flow, or the aeroacoustic wave propagation, or the sensitivity analysis for a gradient-based optimization. The role of the domain decomposition extended beyond the original impetus of discretizing geometrical complex regions or writing modular software for distributed-hardware computers. It induced function-space decompositions and operator decompositions that offered the valuable property of near independence of operator evaluation tasks. The objectives have gravitated about the extensions and implementations of either the previously developed or concurrently being developed methodologies: (1) aerodynamic sensitivity analysis with domain decomposition (SADD); (2) computational aeroacoustics of cavities; and (3) dynamic, multibody computational fluid dynamics using unstructured meshes.
Norberg, U M
1976-08-01
The kinematics, aerodynamics, and energetics of Plecotus auritus in slow horizontal flight, 2-35 m s-1, are analysed. At this speed the inclination of the stroke path is ca. 58 degrees to the horizontal, the stroke angle ca. 91 degrees, and the stroke frequency ca. 11-9 Hz. A method, based on steady-state aerodynamic and momenthum theories, is derived to calculate the lift and drag coefficients as averaged over the whole wing the whole wing-stroke for horizontal flapping flight. This is a further development of Pennycuick's (1968) and Weis-Fogh's (1972) expressions for calculating the lift coefficient. The lift coefficient obtained varies between 1-4 and 1-6, the drag coefficient between 0-4 and 1-2, and the lift:drag ratio between 1-2 and 4-0. The corresponding, calculated, total specific mechanical power output of the wing muscles varies between 27-0 and 40-4 W kg-1 body mass. A maximum estimate of mechanical efficiency is 0-26. The aerodynamic efficiency varies between 0-07 and 0-10. The force coefficient, total mechanical power output, and mechanical and aerodynamic efficiencies are all plausible, demonstrating that the slow flapping flight of Plecotus is thus explicable by steady-state aerodynamics. The downstroke is the power stroke for the vertical upward forces and the upstroke for the horizontal forward forces. PMID:993701
Bat flight: aerodynamics, kinematics and flight morphology.
Hedenström, Anders; Johansson, L Christoffer
2015-03-01
Bats evolved the ability of powered flight more than 50 million years ago. The modern bat is an efficient flyer and recent research on bat flight has revealed many intriguing facts. By using particle image velocimetry to visualize wake vortices, both the magnitude and time-history of aerodynamic forces can be estimated. At most speeds the downstroke generates both lift and thrust, whereas the function of the upstroke changes with forward flight speed. At hovering and slow speed bats use a leading edge vortex to enhance the lift beyond that allowed by steady aerodynamics and an inverted wing during the upstroke to further aid weight support. The bat wing and its skeleton exhibit many features and control mechanisms that are presumed to improve flight performance. Whereas bats appear aerodynamically less efficient than birds when it comes to cruising flight, they have the edge over birds when it comes to manoeuvring. There is a direct relationship between kinematics and the aerodynamic performance, but there is still a lack of knowledge about how (and if) the bat controls the movements and shape (planform and camber) of the wing. Considering the relatively few bat species whose aerodynamic tracks have been characterized, there is scope for new discoveries and a need to study species representing more extreme positions in the bat morphospace. PMID:25740899
Aerodynamic Simulation of Ice Accretion on Airfoils
NASA Technical Reports Server (NTRS)
Broeren, Andy P.; Addy, Harold E., Jr.; Bragg, Michael B.; Busch, Greg T.; Montreuil, Emmanuel
2011-01-01
This report describes recent improvements in aerodynamic scaling and simulation of ice accretion on airfoils. Ice accretions were classified into four types on the basis of aerodynamic effects: roughness, horn, streamwise, and spanwise ridge. The NASA Icing Research Tunnel (IRT) was used to generate ice accretions within these four types using both subscale and full-scale models. Large-scale, pressurized windtunnel testing was performed using a 72-in.- (1.83-m-) chord, NACA 23012 airfoil model with high-fidelity, three-dimensional castings of the IRT ice accretions. Performance data were recorded over Reynolds numbers from 4.5 x 10(exp 6) to 15.9 x 10(exp 6) and Mach numbers from 0.10 to 0.28. Lower fidelity ice-accretion simulation methods were developed and tested on an 18-in.- (0.46-m-) chord NACA 23012 airfoil model in a small-scale wind tunnel at a lower Reynolds number. The aerodynamic accuracy of the lower fidelity, subscale ice simulations was validated against the full-scale results for a factor of 4 reduction in model scale and a factor of 8 reduction in Reynolds number. This research has defined the level of geometric fidelity required for artificial ice shapes to yield aerodynamic performance results to within a known level of uncertainty and has culminated in a proposed methodology for subscale iced-airfoil aerodynamic simulation.
Numadate, Akiyoshi; Mita, Yusuke; Matsumoto, Yotaro; Fujii, Shinya; Hashimoto, Yuichi
2014-01-01
An established inhibitor of dynamin-related protein 1 (Drp1), 3-(2,4-dichloro-5-methoxyphenyl)-2-thioxoquinazoline-4-one (mdivi-1), was recently reported also to show potent puromycin-sensitive aminopeptidase (PSA)-inhibitory activity. Herein, we report structural development of mdivi-1 derivatives and structure-activity relationship (SAR) analysis of the synthesized compounds, as well as the structurally related PSA-specific inhibitor 3-(2,6-diethylphenyl)quinazoline-2,4-dione (PAQ-22), with the aim of identifying key structural features for inhibitory activity in order to develop selective inhibitors of Drp1, which is a potential target for treatment of Huntington's disease. Among the synthesized compounds, 3-(4-chloro-3-methoxyphenyl)-2-thioxoquinazoline-4-one (10g) exhibited more potent Drp1-inhibitory activity than mdivi-1 with high selectivity for Drp1 over PSA. PMID:25273056
Soto-Rojo, Rody; Baldenebro-López, Jesús; Glossman-Mitnik, Daniel
2015-06-01
A group of dyes derived from coumarin was studied, which consisted of nine molecules using a very similar manufacturing process of dye sensitized solar cells (DSSCs). Optimized geometries, energy levels of the highest occupied molecular orbital and the lowest unoccupied molecular orbital, and ultraviolet-visible spectra were obtained using theoretical calculations, and they were also compared with experimental conversion efficiencies of the DSSC. The representation of an excited state in terms of natural transition orbitals (NTOs) was studied. Chemical reactivity parameters were calculated and correlated with the experimental data linked to the efficiency of the DSSC. A new proposal was obtained to design new molecular systems and to predict their potential use as a dye in DSSCs. PMID:25959071
Analysis of the Hessian for Aerodynamic Optimization: Inviscid Flow
NASA Technical Reports Server (NTRS)
Arian, Eyal; Ta'asan, Shlomo
1996-01-01
In this paper we analyze inviscid aerodynamic shape optimization problems governed by the full potential and the Euler equations in two and three dimensions. The analysis indicates that minimization of pressure dependent cost functions results in Hessians whose eigenvalue distributions are identical for the full potential and the Euler equations. However the optimization problems in two and three dimensions are inherently different. While the two dimensional optimization problems are well-posed the three dimensional ones are ill-posed. Oscillations in the shape up to the smallest scale allowed by the design space can develop in the direction perpendicular to the flow, implying that a regularization is required. A natural choice of such a regularization is derived. The analysis also gives an estimate of the Hessian's condition number which implies that the problems at hand are ill-conditioned. Infinite dimensional approximations for the Hessians are constructed and preconditioners for gradient based methods are derived from these approximate Hessians.
Lopez-Izquierdo, Angelica; Warren, Mark; Riedel, Michael; Cho, Scott; Lai, Shuping; Lux, Robert L.; Spitzer, Kenneth W.; Benjamin, Ivor J.; Jou, Chuanchau J.
2014-01-01
Human induced pluripotent stem cell-derived cardiomyocyte (iPSC-CM)-based assays are emerging as a promising tool for the in vitro preclinical screening of QT interval-prolonging side effects of drugs in development. A major impediment to the widespread use of human iPSC-CM assays is the low throughput of the currently available electrophysiological tools. To test the precision and applicability of the near-infrared fluorescent voltage-sensitive dye 1-(4-sulfanatobutyl)-4-{β[2-(di-n-butylamino)-6-naphthyl]butadienyl}quinolinium betaine (di-4-ANBDQBS) for moderate-throughput electrophysiological analyses, we compared simultaneous transmembrane voltage and optical action potential (AP) recordings in human iPSC-CM loaded with di-4-ANBDQBS. Optical AP recordings tracked transmembrane voltage with high precision, generating nearly identical values for AP duration (AP durations at 10%, 50%, and 90% repolarization). Human iPSC-CMs tolerated repeated laser exposure, with stable optical AP parameters recorded over a 30-min study period. Optical AP recordings appropriately tracked changes in repolarization induced by pharmacological manipulation. Finally, di-4-ANBDQBS allowed for moderate-throughput analyses, increasing throughput >10-fold over the traditional patch-clamp technique. We conclude that the voltage-sensitive dye di-4-ANBDQBS allows for high-precision optical AP measurements that markedly increase the throughput for electrophysiological characterization of human iPSC-CMs. PMID:25172899
Lopez-Izquierdo, Angelica; Warren, Mark; Riedel, Michael; Cho, Scott; Lai, Shuping; Lux, Robert L; Spitzer, Kenneth W; Benjamin, Ivor J; Tristani-Firouzi, Martin; Jou, Chuanchau J
2014-11-01
Human induced pluripotent stem cell-derived cardiomyocyte (iPSC-CM)-based assays are emerging as a promising tool for the in vitro preclinical screening of QT interval-prolonging side effects of drugs in development. A major impediment to the widespread use of human iPSC-CM assays is the low throughput of the currently available electrophysiological tools. To test the precision and applicability of the near-infrared fluorescent voltage-sensitive dye 1-(4-sulfanatobutyl)-4-{β[2-(di-n-butylamino)-6-naphthyl]butadienyl}quinolinium betaine (di-4-ANBDQBS) for moderate-throughput electrophysiological analyses, we compared simultaneous transmembrane voltage and optical action potential (AP) recordings in human iPSC-CM loaded with di-4-ANBDQBS. Optical AP recordings tracked transmembrane voltage with high precision, generating nearly identical values for AP duration (AP durations at 10%, 50%, and 90% repolarization). Human iPSC-CMs tolerated repeated laser exposure, with stable optical AP parameters recorded over a 30-min study period. Optical AP recordings appropriately tracked changes in repolarization induced by pharmacological manipulation. Finally, di-4-ANBDQBS allowed for moderate-throughput analyses, increasing throughput >10-fold over the traditional patch-clamp technique. We conclude that the voltage-sensitive dye di-4-ANBDQBS allows for high-precision optical AP measurements that markedly increase the throughput for electrophysiological characterization of human iPSC-CMs. PMID:25172899
Jeannin, P; Pestel, J; Bossus, M; Lassalle, P; Tartar, A; Tonnel, A B
1993-04-01
The ability of four uncoupled synthetic peptides (p52-71, p117-133, p176-187, p188-199) derived from Der p I, a major allergen from the house dust mite Dermatophagoides pteronyssinus (Dpt) to stimulate Fc epsilon R+ cells from Dpt-sensitive patients was comparatively analysed. Each free peptide may specifically stimulate basophils (Fc epsilon RI+ cells) and platelets (Fc epsilon RII+ cells) from patients with significant levels of anti-Der p I IgE antibodies; p52-71 and p117-133 appear the best cell stimulation inducers. Both concentration-dependent biological activities of Der p I-peptide on Fc epsilon R+ cells are enhanced by coupling peptide to a carrier (as human serum albumin). Interestingly each Der p I-sensitive patient tested presents an individual pattern of response to peptide. Thus, from our results it appears that different Der p I sequences could be involved in the immune response to Der p I. PMID:7682161
Jeannin, P; Pestel, J; Bossus, M; Lassalle, P; Tartar, A; Tonnel, A B
1993-01-01
The ability of four uncoupled synthetic peptides (p52-71, p117-133, p176-187, p188-199) derived from Der p I, a major allergen from the house dust mite Dermatophagoides pteronyssinus (Dpt) to stimulate Fc epsilon R+ cells from Dpt-sensitive patients was comparatively analysed. Each free peptide may specifically stimulate basophils (Fc epsilon RI+ cells) and platelets (Fc epsilon RII+ cells) from patients with significant levels of anti-Der p I IgE antibodies; p52-71 and p117-133 appear the best cell stimulation inducers. Both concentration-dependent biological activities of Der p I-peptide on Fc epsilon R+ cells are enhanced by coupling peptide to a carrier (as human serum albumin). Interestingly each Der p I-sensitive patient tested presents an individual pattern of response to peptide. Thus, from our results it appears that different Der p I sequences could be involved in the immune response to Der p I. PMID:7682161
Mizuno, Yosuke; Yisilamu, Yilihamu; Yamaguchi, Tomoya; Tomura, Masaaki; Funaki, Takashi; Sugihara, Hideki; Ono, Katsuhiko
2014-10-01
(Dibenzoylmethanato)boron difluoride derivatives containing triphenylamine moieties were synthesized as a new type of electron-donor/π-acceptor system. These new compounds exhibited long-wavelength absorptions in the UV/Vis spectra, and reversible oxidation and reduction waves in cyclic voltammetry experiments. Their amphoteric redox properties are based on their resonance hybrid forms, in which a positive charge is delocalized on the triphenylamine moieties and a negative charge is localized on the boron atoms. Molecular orbital (MO) calculations indicate that their HOMO and LUMO energies vary with the number of phenylene rings connected to the difluoroboron-chelating ring. This is useful for optimizing the HOMO and LUMO levels to an iodine redox (I(-)/I3(-)) potential and a titanium dioxide conduction band, respectively. Dye-sensitized solar cells fabricated by using these compounds as dye sensitizers exhibited solar-to-electric power conversion efficiencies of 2.7-4.4 % under AM 1.5 solar light. PMID:25170797
A New Aerodynamic Parametrization for Real Urban Surfaces
NASA Astrophysics Data System (ADS)
Kanda, Manabu; Inagaki, Atsushi; Miyamoto, Takashi; Gryschka, Micha; Raasch, Siegfried
2013-08-01
This study conducted large-eddy simulations (LES) of fully developed turbulent flow within and above explicitly resolved buildings in Tokyo and Nagoya, Japan. The more than 100 LES results, each covering a 1,000 × 1,000 m2 area with 2-m resolution, provide a database of the horizontally-averaged turbulent statistics and surface drag corresponding to various urban morphologies. The vertical profiles of horizontally-averaged wind velocity mostly follow a logarithmic law even for districts with high-rise buildings, allowing estimates of aerodynamic parameters such as displacement height and roughness length using the von Karman constant = 0.4. As an alternative derivation of the aerodynamic parameters, a regression of roughness length and variable Karman constant was also attempted, using a displacement height physically determined as the central height of drag action. Although both the regression methods worked, the former gives larger (smaller) values of displacement height (roughness length) by 20-25 % than the latter. The LES database clearly illustrates the essential difference in bulk flow properties between real urban surfaces and simplified arrays. The vertical profiles of horizontally-averaged momentum flux were influenced by the maximum building height and the standard deviation of building height, as well as conventional geometric parameters such as the average building height, frontal area index, and plane area index. On the basis of these investigations, a new aerodynamic parametrization of roughness length and displacement height in terms of the five geometric parameters described above was empirically proposed. The new parametrizations work well for both real urban morphologies and simplified model geometries.
Kwak, Jin Il; Cui, Rongxue; Nam, Sun-Hwa; Kim, Shin Woong; Chae, Yooeun; An, Youn-Joo
2016-06-01
With increasing concerns about the release of silver nanoparticles (AgNPs) into the environment and the risks they pose to ecological and human health, a number of studies of AgNP toxicity to aquatic organisms have been conducted. USEPA and EU JRC have published risk assessment reports for AgNPs. However, most previous studies have focused on the adverse effects of AgNPs on individual species. Hazardous concentration (HC) of AgNPs for protection of aquatic ecosystems that are based on species sensitivity distributions (SSDs) have not yet been derived because sufficient data have not been available. In this study, we conducted multispecies toxicity tests, including acute assays using eight species from five different taxonomic groups (bacteria, algae, flagellates, crustaceans and fish) and chronic assays using six species from four different taxonomic groups (algae, flagellates, crustaceans and fish). Using the results of these assays, we used a SSD approach to derive an AgNP aquatic HC5 (Hazard concentrations at the 5% species) of 0.614 μg/L. To our knowledge, this is the first report of a proposed HC of AgNPs for the protection of aquatic ecosystems that is based on SSDs and uses chronic toxicity data. PMID:26634622
Bennett, James A; Mesfin, Fassil B; Andersen, Thomas T; Gierthy, John F; Jacobson, Herbert I
2002-02-19
An 8-mer peptide (EMTOVNOG) derived from alpha-fetoprotein was compared with tamoxifen for activity against growth of human breast cancer xenografts implanted in immune-deficient mice. Both peptide and tamoxifen prevented growth of estrogen-receptor-positive MCF-7 and T47D human breast cancer xenografts. A subline of MCF-7, made resistant to tamoxifen by a 6-month exposure to this drug in culture, was found to be resistant to tamoxifen in vivo. Peptide completely prevented the xenograft growth of this tamoxifen-resistant subline of MCF-7. Neither peptide nor tamoxifen was effective in slowing the xenograft growth of the estrogen-receptor-negative MDA-MB-231 human breast cancer. A worrisome side effect of tamoxifen is its hypertrophic effect on the uterus. In this study, tamoxifen was shown to stimulate the growth of the immature mouse uterus in vivo, and the peptide significantly inhibited tamoxifen's uterotrophic effect. The mechanism of action of peptide is different from that of tamoxifen in that the peptide does not interfere with the binding of [(3)H]estradiol to the estrogen receptor. In conclusion, alpha-fetoprotein-derived peptide appears to be a novel agent that interferes with the growth of tamoxifen-sensitive as well as tamoxifen-resistant estrogen-receptor-positive human breast cancers; it inhibits the uterotrophic side effect of tamoxifen and, thus, it may be useful in combination with or in place of tamoxifen for treatment of estrogen-receptor-positive human breast cancers. PMID:11830647
NASA Astrophysics Data System (ADS)
Huang, Hongli; Chen, Huajie; Long, Jun; Wang, Guo; Tan, Songting
2016-09-01
Organic dyes with a 3-dimensional (3D) structure is helpful for retarding dyes aggregation and charge recombination as well as improving the power conversion efficiency (PCE) of dye-sensitized solar cells (DSSCs). In this contribution, a novel 3D triarylamine derivative (IDTTPA) featuring an indenothiophenene unit has been designed, synthesized, and applied to develop a 3D organic dyes. Two novel D-A-π-A organic dyes (CD1 and CD2) based on IDTTPA as the electron donors, 2,1,3-benzothiadiazole derivatives as the auxiliary acceptors, and formic acid as the anchoring groups have been successfully synthesized and applied in DSSCs. The effects of the fluoro substitute groups on the photophysical, electrochemical, and photovoltaic properties are investigated. The results indicate that the fluoro-containing dye CD2 exhibits higher molar extinction coefficient, stronger light-capturing ability, and better photovoltaic performance than those of CD1 dye without fluoro substitute. Investigation of the DSSCs performance shows that CD2-based DSSCs exhibit a high PCE value of 7.91%, higher than that of CD1-based DSSCs (6.29%), even higher than that of the reference DSSCs based on N719 (7.49%). This works has demonstrated that this kind of 3D unit (IDTTPA) is a strong and promising electron donor unit to develop high efficiency metal-free organic dyes.
NASA Astrophysics Data System (ADS)
Jiang, Xinya; Wang, Huijun; Wang, Haijun; Zhuo, Ying; Yuan, Ruo; Chai, Yaqin
2016-04-01
Herein, a self-enhanced N-(aminobutyl)-N-(ethylisoluminol) (ABEI) derivative-based electrochemiluminescence (ECL) immunosensor was constructed for the determination of laminin (LN) using PdIr cubes as a mimic peroxidase for signal amplification. Initially, PdIr cubes with efficient peroxidase mimicking properties, large specific surface areas, and good stability and uniformity were synthesized. Then, l-cysteine (l-Cys) and ABEI were immobilized on the PdIr cubes to form the self-enhanced ECL nanocomplex (PdIr-l-Cys-ABEI). In this nanocomplex, PdIr cubes, whose catalytic constant is higher than that of horseradish peroxidase (HRP), could effectively catalyze H2O2 decomposition and thus enhance the ECL intensity of ABEI. Moreover, PdIr cubes can be easily modified with functional groups, which make them adaptable to desired supported platforms. On the other hand, l-Cys as a coreactant of ABEI could effectively enhance the luminous efficiency due to the intramolecular ECL reaction which could reduce the energy loss between l-Cys and ABEI by giving a shorter electron transfer distance. The developed strategy combined an ABEI derivative as a self-enhanced ECL luminophore and PdIr cubes as a mimic peroxidase, resulting in a significantly enhanced ECL signal output. Also, the strategy showed high sensitivity and selectivity for LN, which suggested that our new approach could be potentially applied in monitoring different proteins.
Ochkur, Sergei I; Kim, John Dongil; Protheroe, Cheryl A; Colbert, Dana; Condjella, Rachel M; Bersoux, Sophie; Helmers, Richard A; Moqbel, Redwan; Lacy, Paige; Kelly, Elizabeth A; Jarjour, Nizar N; Kern, Robert; Peters, Anju; Schleimer, Robert P; Furuta, Glenn T; Nair, Parameswaran; Lee, James J; Lee, Nancy A
2012-10-31
Quantitative high throughput assays of eosinophil-mediated activities in fluid samples from patients in a clinical setting have been limited to ELISA assessments for the presence of the prominent granule ribonucleases, ECP and EDN. However, the demonstration that these ribonucleases are expressed by leukocytes other than eosinophils, as well as cells of non-hematopoietic origin, limits the usefulness of these assays. Two novel monoclonal antibodies recognizing eosinophil peroxidase (EPX) were used to develop an eosinophil-specific and sensitive sandwich ELISA. The sensitivity of this EPX-based ELISA was shown to be similar to that of the commercially available ELISA kits for ECP and EDN. More importantly, evidence is also presented confirming that among these granule protein detection options, EPX-based ELISA is the only eosinophil-specific assay. The utility of this high throughput assay to detect released EPX was shown in ex vivo degranulation studies with isolated human eosinophils. In addition, EPX-based ELISA was used to detect and quantify eosinophil degranulation in several in vivo patient settings, including bronchoalveolar lavage fluid obtained following segmental allergen challenge of subjects with allergic asthma, induced sputum derived from respiratory subjects following hypotonic saline inhalation, and nasal lavage of chronic rhinosinusitis patients. This unique EPX-based ELISA thus provides an eosinophil-specific assay that is sensitive, reproducible, and quantitative. In addition, this assay is adaptable to high throughput formats (e.g., automated assays utilizing microtiter plates) using the diverse patient fluid samples typically available in research and clinical settings. PMID:22750539
Ochkur, Sergei I.; Kim, John Dongil; Protheroe, Cheryl A.; Colbert, Dana; Condjella, Rachel M.; Bersoux, Sophie; Helmers, Richard A.; Moqbel, Redwan; Lacy, Paige; Kelly, Elizabeth A.; Jarjour, Nizar N.; Kern, Robert; Peters, Anju; Schleimer, Robert P.; Furuta, Glenn T.; Nair, Parameswaran; Lee, James J.; Lee, Nancy A.
2012-01-01
Quantitative high throughput assays of eosinophil-mediated activities in fluid samples from patients in a clinical setting have been limited to ELISA assessments for the presence of the prominent granule ribonucleases, ECP and EDN. However, the demonstration that these ribonucleases are expressed by leukocytes other than eosinophils, as well as cells of non-hematopoietic origin, limits the usefulness of these assays. Two novel monoclonal antibodies recognizing eosinophil peroxidase (EPX) were used to develop an eosinophil-specific and sensitive sandwich ELISA. The sensitivity of this EPX-based ELISA was shown to be similar to that of the commercially available ELISA kits for ECP and EDN. More importantly, evidence is also presented confirming that among these granule protein detection options, EPX-based ELISA is the only eosinophil-specific assay. The utility of this high throughput assay to detect released EPX was shown in ex vivo degranulation studies with isolated human eosinophils. In addition, EPX-based ELISA was used to detect and quantify eosinophil degranulation in several in vivo patient settings, including bronchoalveolar lavage fluid obtained following segmental allergen challenge of subjects with allergic asthma, induced sputum derived from respiratory subjects following hypotonic saline inhalation, and nasal lavage of chronic rhinosinusitis patients. This unique EPX-based ELISA thus provides an eosinophil-specific assay that is sensitive, reproducible, and quantitative. In addition, this assay is adaptable to high throughput formats (e.g., automated assays utilizing microtiter plates) using the diverse patient fluid samples typically available in research and clinical settings. PMID:22750539
Rasmussen, Jerod M; Lakatos, Anita; van Erp, Theo G M; Kruggel, Frithjof; Keator, David B; Fallon, James T; Macciardi, Fabio; Potkin, Steven G
2012-03-01
Careful selection of the reference region for non-quantitative positron emission tomography (PET) analyses is critically important for Region of Interest (ROI) data analyses. We introduce an empirical method of deriving the most suitable reference region for computing neurodegeneration sensitive (18)fluorodeoxyglucose (FDG) PET ratios based on the dataset collected by the Alzheimer's Disease Neuroimaging Initiative (ADNI) study. Candidate reference regions are selected based on a heat map of the difference in coefficients of variation (COVs) of FDG ratios over time for each of the Automatic Anatomical Labeling (AAL) atlas regions normalized by all other AAL regions. Visual inspection of the heat map suggests that the portion of the cerebellum and vermis superior to the horizontal fissure is the most sensitive reference region. Analyses of FDG ratio data show increases in significance on the order of ten-fold when using the superior portion of the cerebellum as compared with the traditionally used full cerebellum. The approach to reference region selection in this paper can be generalized to other radiopharmaceuticals and radioligands as well as to other disorders where brain changes over time are hypothesized and longitudinal data is available. Based on the empirical evidence presented in this study, we demonstrate the usefulness of the COV heat map method and conclude that intensity normalization based on the superior portion of the cerebellum may be most sensitive to measuring change when performing longitudinal analyses of FDG-PET ratios as well as group comparisons in Alzheimer's disease. This article is part of a Special Issue entitled: Imaging Brain Aging and Neurodegenerative disease. PMID:21958592
Turbine disk cavity aerodynamics and heat transfer
NASA Astrophysics Data System (ADS)
Johnson, B. V.; Daniels, W. A.
1992-07-01
Experiments were conducted to define the nature of the aerodynamics and heat transfer for the flow within the disk cavities and blade attachments of a large-scale model, simulating the Space Shuttle Main Engine (SSME) turbopump drive turbines. These experiments of the aerodynamic driving mechanisms explored the following: (1) flow between the main gas path and the disk cavities; (2) coolant flow injected into the disk cavities; (3) coolant density; (4) leakage flows through the seal between blades; and (5) the role that each of these various flows has in determining the adiabatic recovery temperature at all of the critical locations within the cavities. The model and the test apparatus provide close geometrical and aerodynamic simulation of all the two-stage cavity flow regions for the SSME High Pressure Fuel Turbopump and the ability to simulate the sources and sinks for each cavity flow.
Aerodynamics of magnetic levitation (MAGLEV) trains
NASA Technical Reports Server (NTRS)
Schetz, Joseph A.; Marchman, James F., III
1996-01-01
High-speed (500 kph) trains using magnetic forces for levitation, propulsion and control offer many advantages for the nation and a good opportunity for the aerospace community to apply 'high tech' methods to the domestic sector. One area of many that will need advanced research is the aerodynamics of such MAGLEV (Magnetic Levitation) vehicles. There are important issues with regard to wind tunnel testing and the application of CFD to these devices. This talk will deal with the aerodynamic design of MAGLEV vehicles with emphasis on wind tunnel testing. The moving track facility designed and constructed in the 6 ft. Stability Wind Tunnel at Virginia Tech will be described. Test results for a variety of MAGLEV vehicle configurations will be presented. The last topic to be discussed is a Multi-disciplinary Design approach that is being applied to MAGLEV vehicle configuration design including aerodynamics, structures, manufacturability and life-cycle cost.
Physics of badminton shuttlecocks. Part 1 : aerodynamics
NASA Astrophysics Data System (ADS)
Cohen, Caroline; Darbois Texier, Baptiste; Quéré, David; Clanet, Christophe
2011-11-01
We study experimentally shuttlecocks dynamics. In this part we show that shuttlecock trajectory is highly different from classical parabola. When one takes into account the aerodynamic drag, the flight of the shuttlecock quickly curves downwards and almost reaches a vertical asymptote. We solve the equation of motion with gravity and drag at high Reynolds number and find an analytical expression of the reach. At high velocity, this reach does not depend on velocity anymore. Even if you develop your muscles you will not manage to launch the shuttlecock very far because of the ``aerodynamic wall.'' As a consequence you can predict the length of the field. We then discuss the extend of the aerodynamic wall to other projectiles like sports balls and its importance.
Miniature Trailing Edge Effector for Aerodynamic Control
NASA Technical Reports Server (NTRS)
Lee, Hak-Tae (Inventor); Bieniawski, Stefan R. (Inventor); Kroo, Ilan M. (Inventor)
2008-01-01
Improved miniature trailing edge effectors for aerodynamic control are provided. Three types of devices having aerodynamic housings integrated to the trailing edge of an aerodynamic shape are presented, which vary in details of how the control surface can move. A bucket type device has a control surface which is the back part of a C-shaped member having two arms connected by the back section. The C-shaped section is attached to a housing at the ends of the arms, and is rotatable about an axis parallel to the wing trailing edge to provide up, down and neutral states. A flip-up type device has a control surface which rotates about an axis parallel to the wing trailing edge to provide up, down, neutral and brake states. A rotating type device has a control surface which rotates about an axis parallel to the chord line to provide up, down and neutral states.
Aerodynamic tests of Darrieus wind turbine blades
Migliore, P.G.; Walters, R.E.; Wolfe, W.P.
1983-03-01
An indoor facility for the aerodynamic testing of Darrieus turbine blades was developed. Lift, drag, and moment coefficients were measured for two blades whose angle of attack and chord-to-radius ratio were varied. The first blade used an NACA 0015 airfoil section; the second used a 15% elliptical cross section with a modified circular arc trailing edge. Blade aerodynamic coefficients were corrected to section coefficients for comparison to published rectilinear flow data. Although the airfoil sections were symmetrical, moment coefficients were not zero and the lift and drag curves were asymmetrical about zero lift coefficient and angle of attack. These features verified the predicted virtual camber and incidence phenomena. Boundary-layer centrifugal effects were manifested by discontinuous lift curves and large differences in the angle of zero lift between th NACA 0015 and elliptical airfoils. It was concluded that rectilinear flow aerodynamic data are not applicable to Darrieus turbine blades, even for small chord-to-radius ratios.
History of the numerical aerodynamic simulation program
NASA Technical Reports Server (NTRS)
Peterson, Victor L.; Ballhaus, William F., Jr.
1987-01-01
The Numerical Aerodynamic Simulation (NAS) program has reached a milestone with the completion of the initial operating configuration of the NAS Processing System Network. This achievement is the first major milestone in the continuing effort to provide a state-of-the-art supercomputer facility for the national aerospace community and to serve as a pathfinder for the development and use of future supercomputer systems. The underlying factors that motivated the initiation of the program are first identified and then discussed. These include the emergence and evolution of computational aerodynamics as a powerful new capability in aerodynamics research and development, the computer power required for advances in the discipline, the complementary nature of computation and wind tunnel testing, and the need for the government to play a pathfinding role in the development and use of large-scale scientific computing systems. Finally, the history of the NAS program is traced from its inception in 1975 to the present time.
Wind turbine aerodynamics research needs assessment
NASA Astrophysics Data System (ADS)
Stoddard, F. S.; Porter, B. K.
1986-01-01
A prioritized list is developed for wind turbine aerodynamic research needs and opportunities which could be used by the Department of Energy program management team in detailing the DOE Five-Year Wind Turbine Research Plan. The focus of the Assessment was the basic science of aerodynamics as applied to wind turbines, including all relevant phenomena, such as turbulence, dynamic stall, three-dimensional effects, viscosity, wake geometry, and others which influence aerodynamic understanding and design. The study was restricted to wind turbines that provide electrical energy compatible with the utility grid, and included both horizontal axis wind turbines (HAWT) and vertical axis wind turbines (VAWT). Also, no economic constraints were imposed on the design concepts or recommendations since the focus of the investigation was purely scientific.
Photogrammetry of a Hypersonic Inflatable Aerodynamic Decelerator
NASA Technical Reports Server (NTRS)
Kushner, Laura Kathryn; Littell, Justin D.; Cassell, Alan M.
2013-01-01
In 2012, two large-scale models of a Hypersonic Inflatable Aerodynamic decelerator were tested in the National Full-Scale Aerodynamic Complex at NASA Ames Research Center. One of the objectives of this test was to measure model deflections under aerodynamic loading that approximated expected flight conditions. The measurements were acquired using stereo photogrammetry. Four pairs of stereo cameras were mounted inside the NFAC test section, each imaging a particular section of the HIAD. The views were then stitched together post-test to create a surface deformation profile. The data from the photogram- metry system will largely be used for comparisons to and refinement of Fluid Structure Interaction models. This paper describes how a commercial photogrammetry system was adapted to make the measurements and presents some preliminary results.
Identification of aerodynamic models for maneuvering aircraft
NASA Technical Reports Server (NTRS)
Lan, C. Edward; Hu, C. C.
1992-01-01
A Fourier analysis method was developed to analyze harmonic forced-oscillation data at high angles of attack as functions of the angle of attack and its time rate of change. The resulting aerodynamic responses at different frequencies are used to build up the aerodynamic models involving time integrals of the indicial type. An efficient numerical method was also developed to evaluate these time integrals for arbitrary motions based on a concept of equivalent harmonic motion. The method was verified by first using results from two-dimensional and three-dimensional linear theories. The developed models for C sub L, C sub D, and C sub M based on high-alpha data for a 70 deg delta wing in harmonic motions showed accurate results in reproducing hysteresis. The aerodynamic models are further verified by comparing with test data using ramp-type motions.
Aerodynamic optimization studies on advanced architecture computers
NASA Technical Reports Server (NTRS)
Chawla, Kalpana
1995-01-01
The approach to carrying out multi-discipline aerospace design studies in the future, especially in massively parallel computing environments, comprises of choosing (1) suitable solvers to compute solutions to equations characterizing a discipline, and (2) efficient optimization methods. In addition, for aerodynamic optimization problems, (3) smart methodologies must be selected to modify the surface shape. In this research effort, a 'direct' optimization method is implemented on the Cray C-90 to improve aerodynamic design. It is coupled with an existing implicit Navier-Stokes solver, OVERFLOW, to compute flow solutions. The optimization method is chosen such that it can accomodate multi-discipline optimization in future computations. In the work , however, only single discipline aerodynamic optimization will be included.
2014-01-01
Background Inhibition of the activated epidermal growth factor receptor (EGFR) with either enzymatic kinase inhibitors or anti-EGFR antibodies such as cetuximab, is an effective modality of treatment for multiple human cancers. Enzymatic EGFR inhibitors are effective for lung adenocarcinomas with somatic kinase domain EGFR mutations while, paradoxically, anti-EGFR antibodies are more effective in colon and head and neck cancers where EGFR mutations occur less frequently. In colorectal cancer, anti-EGFR antibodies are routinely used as second-line therapy of KRAS wild-type tumors. However, detailed mechanisms and genomic predictors for pharmacological response to these antibodies in colon cancer remain unclear. Findings We describe a case of colorectal adenocarcinoma, which was found to harbor a kinase domain mutation, G724S, in EGFR through whole genome sequencing. We show that G724S mutant EGFR is oncogenic and that it differs from classic lung cancer derived EGFR mutants in that it is cetuximab responsive in vitro, yet relatively insensitive to small molecule kinase inhibitors. Through biochemical and cellular pharmacologic studies, we have determined that cells harboring the colon cancer-derived G719S and G724S mutants are responsive to cetuximab therapy in vitro and found that the requirement for asymmetric dimerization of these mutant EGFR to promote cellular transformation may explain their greater inhibition by cetuximab than small-molecule kinase inhibitors. Conclusion The colon-cancer derived G719S and G724S mutants are oncogenic and sensitive in vitro to cetuximab. These data suggest that patients with these mutations may benefit from the use of anti-EGFR antibodies as part of the first-line therapy. PMID:24894453
Airfoil Ice-Accretion Aerodynamics Simulation
NASA Technical Reports Server (NTRS)
Bragg, Michael B.; Broeren, Andy P.; Addy, Harold E.; Potapczuk, Mark G.; Guffond, Didier; Montreuil, E.
2007-01-01
NASA Glenn Research Center, ONERA, and the University of Illinois are conducting a major research program whose goal is to improve our understanding of the aerodynamic scaling of ice accretions on airfoils. The program when it is completed will result in validated scaled simulation methods that produce the essential aerodynamic features of the full-scale iced-airfoil. This research will provide some of the first, high-fidelity, full-scale, iced-airfoil aerodynamic data. An initial study classified ice accretions based on their aerodynamics into four types: roughness, streamwise ice, horn ice, and spanwise-ridge ice. Subscale testing using a NACA 23012 airfoil was performed in the NASA IRT and University of Illinois wind tunnel to better understand the aerodynamics of these ice types and to test various levels of ice simulation fidelity. These studies are briefly reviewed here and have been presented in more detail in other papers. Based on these results, full-scale testing at the ONERA F1 tunnel using cast ice shapes obtained from molds taken in the IRT will provide full-scale iced airfoil data from full-scale ice accretions. Using these data as a baseline, the final step is to validate the simulation methods in scale in the Illinois wind tunnel. Computational ice accretion methods including LEWICE and ONICE have been used to guide the experiments and are briefly described and results shown. When full-scale and simulation aerodynamic results are available, these data will be used to further develop computational tools. Thus the purpose of the paper is to present an overview of the program and key results to date.
Unsteady Aerodynamics - Subsonic Compressible Inviscid Case
NASA Technical Reports Server (NTRS)
Balakrishnan, A. V.
1999-01-01
This paper presents a new analytical treatment of Unsteady Aerodynamics - the linear theory covering the subsonic compressible (inviscid) case - drawing on some recent work in Operator Theory and Functional Analysis. The specific new results are: (a) An existence and uniqueness proof for the Laplace transform version of the Possio integral equation as well as a new closed form solution approximation thereof. (b) A new representation for the time-domain solution of the subsonic compressible aerodynamic equations emphasizing in particular the role of the initial conditions.
Method of reducing drag in aerodynamic systems
NASA Technical Reports Server (NTRS)
Hrach, Frank J. (Inventor)
1993-01-01
In the present method, boundary layer thickening is combined with laminar flow control to reduce drag. An aerodynamic body is accelerated enabling a ram turbine on the body to receive air at velocity V sub 0. The discharge air is directed over an aft portion of the aerodynamic body producing boundary layer thickening. The ram turbine also drives a compressor by applying torque to a shaft connected between the ram turbine and the compressor. The compressor sucks in lower boundary layer air through inlets in the shell of the aircraft producing laminar flow control and reducing drag. The discharge from the compressor is expanded in a nozzle to produce thrust.
Air flow testing on aerodynamic truck
NASA Technical Reports Server (NTRS)
1975-01-01
After leasing a cab-over tractor-trailer from a Southern California firm, Dryden researchers added sheet metal modifications like those shown here. They rounded the front corners and edges, and placed a smooth fairing on the cab's roofs and sides extending back to the trailer. During the investigation of truck aerodynamics, the techniques honed in flight research proved highly applicable. By closing the gap between the cab and the trailer, for example, researchers discovered a significant reduction in aerodynamic drag, one resulting in 20 to 25 percent less fuel consumption than the standard design. Many truck manufacturers subsequently incorporated similar modifications on their products.
Unstructured mesh algorithms for aerodynamic calculations
NASA Technical Reports Server (NTRS)
Mavriplis, D. J.
1992-01-01
The use of unstructured mesh techniques for solving complex aerodynamic flows is discussed. The principle advantages of unstructured mesh strategies, as they relate to complex geometries, adaptive meshing capabilities, and parallel processing are emphasized. The various aspects required for the efficient and accurate solution of aerodynamic flows are addressed. These include mesh generation, mesh adaptivity, solution algorithms, convergence acceleration, and turbulence modeling. Computations of viscous turbulent two-dimensional flows and inviscid three-dimensional flows about complex configurations are demonstrated. Remaining obstacles and directions for future research are also outlined.
Aerodynamic Modeling for Aircraft in Unsteady Flight Conditions
NASA Technical Reports Server (NTRS)
Lan, C. Edward
2000-01-01
This report summarizes the activities in unsteady aerodynamic modeling and application of unsteady aerodynamic models to flight dynamics. A public on briefing was presented on July 21, 1999 at Langley Research Center.
Aerodynamic detuning analysis of an unstalled supersonic turbofan cascade
NASA Technical Reports Server (NTRS)
Hoyniak, D.; Fleeter, S.
1985-01-01
An approach to passive flutter control is aerodynamic detuning, defined as designed passage-to-passage differences in the unsteady aerodynamic flow field of a rotor blade row. Thus, aerodynamic detuning directly affects the fundamental driving mechanism for flutter. A model to demonstrate the enhanced supersonic aeroelastic stability associated with aerodynamic detuning is developed. The stability of an aerodynamically detuned cascade operating in a supersonic inlet flow field with a subsonic leading edge locus is analyzed, with the aerodynamic detuning accomplished by means of nonuniform circumferential spacing of adjacent rotor blades. The unsteady aerodynamic forces and moments on the blading are defined in terms of influence coefficients in a manner that permits the stability of both a conventional uniformally spaced rotor configuration as well as the detuned nonuniform circumferentially spaced rotor to be determined. With Verdon's uniformly spaced Cascade B as a baseline, this analysis is then utilized to demonstrate the potential enhanced aeroelastic stability associated with this particular type of aerodynamic detuning.
Planform effects on the supersonic aerodynamics of multibody configurations
NASA Technical Reports Server (NTRS)
Mcmillin, Naomi; Wood, Richard M.
1987-01-01
An experimental and theoretical investigation of the effect of planform on the supersonic aerodynamics of low-fineness-ratio multibody configurations was conducted. Longitudinal and lateral-directional aerodynamic and flow visualization data were obtained on three multibody configurations. The data indicated that planform has a small effect on the zero lift drag of a multibody configuration. The longitudinal data obtained at lifting conditions showed a sensitivity to planform shape. Lateral-directional data obtained for all configurations did not uncover any unusual stability traits for this class of configuration. A comparison study was also made between the planform effects observed on single-body and multibody configurations. Results from this study indicate that the multibody concept appears to offer a mechanism for employing a low-sweep wing with no significant increase in zero-lift drag but still retaining high-performance characteristics at high-lift conditions. Evaluation of the linear-theory prediction methods revealed a general inability of the methods to predict the characteristics of low-fineness-ratio geometries.
Dynamic Stall in Pitching Airfoils: Aerodynamic Damping and Compressibility Effects
NASA Astrophysics Data System (ADS)
Corke, Thomas C.; Thomas, Flint O.
2015-01-01
Dynamic stall is an incredibly rich fluid dynamics problem that manifests itself on an airfoil during rapid, transient motion in which the angle of incidence surpasses the static stall limit. It is an important element of many manmade and natural flyers, including helicopters and supermaneuverable aircraft, and low-Reynolds number flapping-wing birds and insects. The fluid dynamic attributes that accompany dynamic stall include an eruption of vorticity that organizes into a well-defined dynamic stall vortex and massive excursions in aerodynamic loads that can couple with the airfoil structural dynamics. The dynamic stall process is highly sensitive to surface roughness that can influence turbulent transition and to local compressibility effects that occur at free-stream Mach numbers that are otherwise incompressible. Under some conditions, dynamic stall can result in negative aerodynamic damping that leads to limit-cycle growth of structural vibrations and rapid mechanical failure. The mechanisms leading to negative damping have been a principal interest of recent experiments and analysis. Computational fluid dynamic simulations and low-order models have not been good predictors so far. Large-eddy simulation could be a viable approach although it remains computationally intensive. The topic is technologically important owing to the desire to develop next-generation rotorcraft that employ adaptive rotor dynamic stall control.
Forced and Moment Measurements with Pressure-Sensitive Paint
NASA Technical Reports Server (NTRS)
Bell, James H.
1999-01-01
The potential of pressure-sensitive paint (PSP) to provide aerodynamic loads measurements has been a driving force behind the development of this measurement technique. To demonstrate the suitability of PSP for this purpose, it is necessary to show that PSP-derived pressures can be accurately integrated over the model surface. This cannot be done simply by demonstrating the accuracy of PSP as compared to pressure taps. PSP errors due to misregistration or temperature sensitivity may be high near model edges, where they will have a strong effect on moment measurements, but where pressure taps are rarely installed. A more suitable technique is to compare integrated PSP data over the entire model surface with balance and/or CFD results. This paper presents results from three experiments in which integrated PSP data is compared with balance and/or CFD data. This allows the usefulness of PSP for force and moment measurements, and by implication for loads measurements, to be assessed.
Sensitive glow discharge ion source for aerosol and gas analysis
Reilly, Peter T. A.
2007-08-14
A high sensitivity glow discharge ion source system for analyzing particles includes an aerodynamic lens having a plurality of constrictions for receiving an aerosol including at least one analyte particle in a carrier gas and focusing the analyte particles into a collimated particle beam. A separator separates the carrier gas from the analyte particle beam, wherein the analyte particle beam or vapors derived from the analyte particle beam are selectively transmitted out of from the separator. A glow discharge ionization source includes a discharge chamber having an entrance orifice for receiving the analyte particle beam or analyte vapors, and a target electrode and discharge electrode therein. An electric field applied between the target electrode and discharge electrode generates an analyte ion stream from the analyte vapors, which is directed out of the discharge chamber through an exit orifice, such as to a mass spectrometer. High analyte sensitivity is obtained by pumping the discharge chamber exclusively through the exit orifice and the entrance orifice.
Nonlinear problems in flight dynamics involving aerodynamic bifurcations
NASA Technical Reports Server (NTRS)
Tobak, M.; Chapman, G. T.
1985-01-01
Aerodynamic bifurcation is defined as the replacement of an unstable equilibrium flow by a new stable equilibrium flow at a critical value of a parameter. A mathematical model of the aerodynamic contribution to the aircraft's equations of motion is amended to accommodate aerodynamic bifurcations. Important bifurcations such as, the onset of large-scale vortex-shedding are defined. The amended mathematical model is capable of incorporating various forms of aerodynamic responses, including those associated with dynamic stall of airfoils.
In vivo measurement of aerodynamic weight support in freely flying birds
NASA Astrophysics Data System (ADS)
Lentink, David; Haselsteiner, Andreas; Ingersoll, Rivers
2014-11-01
Birds dynamically change the shape of their wing during the stroke to support their body weight aerodynamically. The wing is partially folded during the upstroke, which suggests that the upstroke of birds might not actively contribute to aerodynamic force production. This hypothesis is supported by the significant mass difference between the large pectoralis muscle that powers the down-stroke and the much smaller supracoracoideus that drives the upstroke. Previous works used indirect or incomplete techniques to measure the total force generated by bird wings ranging from muscle force, airflow, wing surface pressure, to detailed kinematics measurements coupled with bird mass-distribution models to derive net force through second derivatives. We have validated a new method that measures aerodynamic force in vivo time-resolved directly in freely flying birds which can resolve this question. The validation of the method, using independent force measurements on a quadcopter with pulsating thrust, show the aerodynamic force and impulse are measured within 2% accuracy and time-resolved. We demonstrate results for quad-copters and birds of similar weight and size. The method is scalable and can be applied to both engineered and natural flyers across taxa. The first author invented the method, the second and third authors validated the method and present results for quadcopters and birds.
Time Series Vegetation Aerodynamic Roughness Fields Estimated from MODIS Observations
NASA Technical Reports Server (NTRS)
Borak, Jordan S.; Jasinski, Michael F.; Crago, Richard D.
2005-01-01
Most land surface models used today require estimates of aerodynamic roughness length in order to characterize momentum transfer between the surface and atmosphere. The most common method of prescribing roughness is through the use of empirical look-up tables based solely on land cover class. Theoretical approaches that employ satellite-based estimates of canopy density present an attractive alternative to current look-up table approaches based on vegetation cover type that do not account for within-class variability and are oftentimes simplistic with respect to temporal variability. The current research applies Raupach s formulation of momentum aerodynamic roughness to MODIS data on a regional scale in order to estimate seasonally variable roughness and zero-plane displacement height fields using bulk land cover parameters estimated by [Jasinski, M.F., Borak, J., Crago, R., 2005. Bulk surface momentum parameters for satellite-derived vegetation fields. Agric. For. Meteorol. 133, 55-68]. Results indicate promising advances over look-up approaches with respect to characterization of vegetation roughness variability in land surface and atmospheric circulation models.
Index for aerodynamic data from the Bumblebee program
NASA Technical Reports Server (NTRS)
Cronvich, L. L.; Barnes, G. A.
1978-01-01
The Bumblebee program, was designed to provide a supersonic guided missile. The aerodynamics program included a fundamental research effort in supersonic aerodynamics as well as a design task in developing both test vehicles and prototypes of tactical missiles. An index of aerodynamic missile data developed in this program is presented.
14 CFR 25.445 - Auxiliary aerodynamic surfaces.
Code of Federal Regulations, 2010 CFR
2010-01-01
... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Auxiliary aerodynamic surfaces. 25.445... AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Structure Control Surface and System Loads § 25.445 Auxiliary aerodynamic surfaces. (a) When significant, the aerodynamic influence...