Correlation method for computing sensitivity functions on a high-speed iterative analog computer
Digital correlation for computing sensitivity coefficients on iterative analog computer
Ogrady, E. P.↗
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Results for “sensitivity coefficients”
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Sensitivity of earth and lunar orbits to velocity changes at periapsis and apoapsis. Project Apollo
Maneuver sensitivity coefficients for earth and moon orbits
Pursell, B. M.↗
Signal flow graphs as an aid in network analysis
Signal flow graph, obtaining numeric and symbolic expressions for network function in terms of component parameters and sensitivity coefficients
Zobrist, G. W.↗
A new vector-matrix second order sensitivity equation with application to entry problem
Vector-matrix differential equation for second order sensitivity coefficients applied to trajectory optimization, modeling and compensation and guidance and control
Cefola, P. J.↗
Use of complex optimization for sensitivity determination in distributed lumped active networks
Complex optimization techniques applied to various sensitivity coefficient determination for distributed-lumped-active networks
Huelsman, L. P.↗
Time domain and frequency domain design techniques for model reference adaptive control systems
Some problems associated with the design of model-reference adaptive control systems are considered and solutions to these problems are advanced. The stability of the adapted system is a primary consideration in the development of both the time-domain and the frequency-domain design techniques. Consequentially, the use of Liapunov's direct method forms an integral part of the derivation of the design procedures. The application of sensitivity coefficients to the design of model-reference adaptive control systems is considered. An application of the design techniques is also presented.
Boland, J. S., III↗
System statistical reliability model and analysis
A digital computer code was developed to simulate the time-dependent behavior of the 5-kwe reactor thermoelectric system. The code was used to determine lifetime sensitivity coefficients for a number of system design parameters, such as thermoelectric module efficiency and degradation rate, radiator absorptivity and emissivity, fuel element barrier defect constant, beginning-of-life reactivity, etc. A probability distribution (mean and standard deviation) was estimated for each of these design parameters. Then, error analysis was used to obtain a probability distribution for the system lifetime (mean = 7.7 years, standard deviation = 1.1 years). From this, the probability that the system will achieve the design goal of 5 years lifetime is 0.993. This value represents an estimate of the degradation reliability of the system.
Lekach, V. S.↗
Nonlinear parameter identification: Ballistic range experience applicable to flight testing
The parameter identification scheme being used is a differential correction least squares procedure (Gauss-Newton method). The position, orientation, and derivatives of these quantities with respect to the parameters of interest (i.e., sensitivity coefficients) are determined by digital integration of the equations of motion and the parametric differential equations. The application of this technique to three vastly different sets of data is used to illustrate the versatility of the method and to indicate some of the problems that still remain.
Chapman, G.↗
Some statistical analysis techniques for the effect of systematic instrument errors on the results of measurements in a space experiment
Mathematical models of certain systematic telemetry signal errors arising during the passage of the signal through the recording and transmitting blocks of the physical instruments aboard the spacecraft are classified and constructed. Statistical analysis methods are used to determine the background function and relative sensitivity coefficients of the channels of a charged particle detector. Results are presented. A block diagram for a method taking into account the effect of distortions is given.
Kondakov, S. P.↗
Minimum trim drag design for interfering lifting surfaces using vortex-lattice methodology
A new method has been developed by which the mean camber surface can be determined for trimmed noncoplanar planforms with minimum vortex drag under subsonic conditions. The method uses a vortex lattice and overcomes previous difficulties with chord loading specification; it uses a Trefftz plane analysis to determine the optimum span loading for minimum drag, then solves for the mean camber surface of the wing which will provide the required loading. Pitching-moment or root-bending-moment constraints can be employed as well at the design lift coefficient. Sensitivity studies of vortex-lattice arrangement have been made with this method and are presented. Comparisons with other theories show generally good agreement. The versatility of the method is demonstrated by applying it to (1) isolated wings, (2) wing-canard configurations, (3) a tandem wing, and (4) a wing-winglet configuration.
Lamar, J. E.↗
Modular design attitude control system
Application of modular control techniques to the attitude control of a prototype flexible spacecraft and a prototype flexible space platform was further developed by determining numerical values for the physical parameters of a four body approximation of the MSFC/hybrid deployable truss incorporated in the space platform model, generating sensitivity coefficients for the model of the flexible spacecraft, evaluating the changes in the digital computer simulation of the flexible spacecraft resulting from the addition of another rigid body to the model and comparing attitude control effectiveness with actuators on more than one rigid body of the model with that for the case in which the actuators were restricted to one body.
Chichester, F. D.↗
Preliminary measurements of velocity, density and total temperature fluctuations in compressible subsonic flow
The heat transfer characteristics of a three-wire hot-wire probe operated with a constant temperature anemometer were investigated in the subsonic compressible flow regime. The sensitivity coefficients, with respect to velocity, density and total temperature, were measured and the results were used to calculate the velocity, density, and total temperature fluctuations in the test section of the Langley 0.3-m Transonic Cryogenic Tunnel (TCT). These results were extended to give estimates for fluctuations due to vorticity, sound, and entropy. In addition, attempts were made to determine the major source of disturbances in the 0.3-m TCT.
Stainback, P. C.↗
The use of hot-wire anemometry in transonic periodic flow
The unsteady wake profiles of an airfoil with an oscillating flap were measured in the NASA Ames 11 x 11-foot transonic wind tunnel. Laser Doppler Velocimetry (LDV) and holography techniques were used in limited region where optical accessability is available. X-hot-film wire was used to measure the wake profiles in the complete region to obtain magnitude and direction of the flow. A thorough calibration was carried out to determine the sensitivity coefficients of the hot-wire in three different tunnels at transonic speeds. A calculation procedure is established to resolve the hot-wire signals at transonic speeds and applied in the measurements of steady and periodic wake profiles. The effect of flow incidence on the hot-wire signals is evaluated and incorporated in the analyses. Typical hot-wire results are compared with the results of LDV, holography and pitot-static tube embedded with Kulite transducers.
Bodapati, S.↗
On determining important aspects of mathematical models: Application to problems in physics and chemistry
The use of parametric and functional gradient sensitivity analysis techniques is considered for models described by partial differential equations. By interchanging appropriate dependent and independent variables, questions of inverse sensitivity may be addressed to gain insight into the inversion of observational data for parameter and function identification in mathematical models. It may be argued that the presence of a subset of dominantly strong coupled dependent variables will result in the overall system sensitivity behavior collapsing into a simple set of scaling and self similarity relations amongst elements of the entire matrix of sensitivity coefficients. These general tools are generic in nature, but herein their application to problems arising in selected areas of physics and chemistry is presented.
Rabitz, Herschel↗
Application of a semianalytical technique for sensitivity analysis of unsteady aerodynamic computations
A semianalytical approach is developed for the sensitivity analysis of linear unsteady aerodynamic loads. The semianalytical approach is easier to implement than the analytical approach. It is also computationally less expensive than the finite difference approach when used with panel methods which require a large number of panels. The semianalytical approach is applied to an isolated airfoil in a two-dimensional flow and rotating propfan blades in three-dimensional flow. Sensitivity coefficients with respect to nonshape-dependent variables are shown for some cases.
Murthy, Durbha V.↗
Multiple boundary condition testing error analysis
Techniques for interpreting data from multiple-boundary-condition (MBC) ground tests of large space structures are developed analytically and demonstrated. The use of MBC testing to validate structures too large to stand alone on the ground is explained; the generalized least-squares mass and stiffness curve-fitting methods typically applied to MBC test data are reviewed; and a detailed error analysis is performed. Consideration is given to sensitivity coefficients, covariance-matrix theory, the correspondence between test and analysis modes, constraints and step sizes, convergence criteria, and factor-analysis theory. Numerical results for a simple beam problem are presented in tables and briefly characterized. The improved error-updating capabilities of MBC testing are confirmed, and it is concluded that reasonably accurate results can be obtained using a diagonal covariance matrix.
Glaser, R. J.↗
The mean ozone profile and its temperature sensitivity in the upper stratosphere and lower mesosphere - An analysis of LIMS observations
Multiple simultaneous LIMS (Limb Infrared Monitor of the Stratosphere) observations of both O3 and temperature T in the upper stratosphere and lower mesosphere are analyzed to derive O3-T correlations for comparisons with model calculations. The zonally averaged O3 profile is compared with results from a simplified photochemical model that assumes O3 to be in a photochemical steady state. The model profile is systematically lower than the observed profile. Key parameters are identified in which changes can systematically increase the O3 profile in both the stratosphere and the mesosphere. The LIMS-derived values for the sensitivity of O3 to changes in T are compared with equilibrium model calculations which include the T-driven opacity feedback effect on photodissociation rate constants. The theoretical O3 response to temperature perturbations is investigated. It is shown how the O3-T sensitivity coefficient is affected by zonal and vertical advection terms as well as by the photochemical coupling between O3 and T.
Froidevaux, Lucien↗
Perturbations to tropospheric oxidants, 1985-2035. I - Calculations of ozone and OH in chemically coherent regions
A one-dimensional model based on the sensitivity coefficients of Thompson (1990) is used to calculate regional changes in tropospheric O3 and OH due to specified global or regional changes in CH4 and CO emissions over the period 1985-2035. The methods applied are explained, and the results are presented in extensive tables and graphs and characterized in detail. A 10-15-percent increase in global tropospheric O3 and a 10-15-percent decrease in OH are predicted for both (1) global scenarios with continuing increases in CH4 and CO and (2) regional scenarios where emissions are limited in some regions but not in others; significant regional variation in O3 is predicted for (2). If depletion of O3 in the stratosphere and global warming are introduced into (1) or (2), however, they nearly cancel out the tropospheric O3 increases and OH decreases.
Thompson, Anne M.↗