Methods for systematic generation of Liapunov functions /part one/
Review of Liapunov stability theory as applied to stability analysis on nonlinear control systems - methods for generation of Liapunov functions
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SEARCH · Engineering Papers
Results for “nonlinear analysis”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Error analysis of inversion techniques Final report
Error analysis of nonlinear inversion techniques for deriving atmospheric temperature profiles from satellite radiometer data
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Aerodynamics of bodies of revolution in nonplanar motion.
Aerodynamics of bodies of revolution in nonplanar motion using nonlinear functional analysis of moments for motion about center of gravity
Peterson, V. L.↗
Aerodynamics of bodies of revolution in coning motion.
Aerodynamics of bodies of revolution in nonplanar motion using nonlinear functional analysis of moments for motion about center of gravity
Peterson, V. L.↗
Nonlinear flutter of curved plates.
Nonlinear Galerkin analysis of curved plate flutter, using shallow shell/von Karman equations and quasi-steady aerodynamic theory
Dowell, E. H.↗
Nonlinear flutter of curved plates, part 2
Numerical results for nonlinear flutter analysis of three dimensional curved plates
Dowell, E. H.↗
A kinetic model for the acid-catalyzed decomposition of Delrin
Kinetic model for acid catalyzed Delrin decomposition, testing for Delrin-citric acid system and predicting thermograms with nonlinear regression analysis
Cagliostro, D. E.↗
Damper design from a structural engineer's point of view
Nonlinear structural analysis of Mariner spacecraft solar panel, using damper test characteristics
Chen, J. C.↗
Stability analysis of systems with time delay
Computerized Pontryagin stability analysis of nonlinear multiple delay systems
Karmarkar, J. S.↗
Techniques for generation of control and guidance signals derived from optical fields, part 2
The development is reported of a high resolution technique for the detection and identification of landmarks from spacecraft optical fields. By making use of nonlinear regression analysis, a method is presented whereby a sequence of synthetic images produced by a digital computer can be automatically adjusted to provide a least squares approximation to a real image. The convergence of the method is demonstrated by means of a computer simulation for both elliptical and rectangular patterns. Statistical simulation studies with elliptical and rectangular patterns show that the computational techniques developed are able to at least match human pattern recognition capabilities, even in the presence of large amounts of noise. Unlike most pattern recognition techniques, this ability is unaffected by arbitrary pattern rotation, translation, and scale change. Further development of the basic approach may eventually allow a spacecraft or robot vehicle to be provided with an ability to very accurately determine its spatial relationship to arbitrary known objects within its optical field of view.
Hemami, H.↗
A sequence solution to the Fokker-Planck equation.
In this paper a new approach to nonlinear system analysis based on the Fokker-Planck equation is developed. The development begins as a modification of the parametrix method of partial differential equation theory and provides a sequence solution to the multidimensional time-varying Fokker-Planck equation. This sequence is simplified for the case where only a steady-state solution or a solution for the variance of a particular combination of states is desired. Equations are presented in a form suitable for obtaining numerical results using a digital computer.
Mayfield, W. W.↗
Nonlinear models for estimating GSFC travel requirements
A methodology is presented for estimating travel requirements for a particular period of time. Travel models were generated using nonlinear regression analysis techniques on a data base of FY-72 and FY-73 information from 79 GSFC projects. Although the subject matter relates to GSFX activities, the type of analysis used and the manner of selecting the relevant variables would be of interest to other NASA centers, government agencies, private corporations and, in general, any organization with a significant travel budget. Models were developed for each of six types of activity: flight projects (in-house and out-of-house), experiments on non-GSFC projects, international projects, ART/SRT, data analysis, advanced studies, tracking and data, and indirects.
Buffalano, C.↗
Importance of helicopter dynamics to the mathematical model of the helicopter
A mathematical model of the helicopter requires appropriate representation of the constituent elements of rotor dynamics. General-purpose programs that model a variety of configurations for a broad range of operating conditions result in varying and incompatible levels of sophistication. Analysis of specific dynamic problems facilitates the identification of configuration parameters which determine system behavior. For the present analysis, the nonlinear equations of a torsionally rigid hingeless rotor are linearized about an equilibrium condition to determine flap-lag stability characteristics in hover. A collocation method was used to obtain the coupled natural frequencies and modes. These modes allow exact treatment of the effect of elastic coupling which more than compensates for the destabilizing inertial coupling. The sensitivity of damping to the number of modes was found to be small, and reasonable accuracy was obtained the first flapwise and edgewise coupled modes. The range of destabilizing precone was found to be small.
White, W. F., Jr.↗
Control optimization, stabilization and computer algorithms for aircraft applications
Research related to reliable aircraft design is summarized. Topics discussed include systems reliability optimization, failure detection algorithms, analysis of nonlinear filters, design of compensators incorporating time delays, digital compensator design, estimation for systems with echoes, low-order compensator design, descent-phase controller for 4-D navigation, infinite dimensional mathematical programming problems and optimal control problems with constraints, robust compensator design, numerical methods for the Lyapunov equations, and perturbation methods in linear filtering and control.
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Variations in chemical composition of Apollo 15 mare basalts
Chemical analyses of 30 different Apollo 15 mare basalts were examined to evaluate the effects of closure on the pearson moment correlation coefficient. It is shown possible to describe the Apollo 15 mare basalts in terms of an opaque, an olivine/pyroxene, an anorthite, and a KREEP component, if significant correlations are identified using the expected correlations as null values. Using Q-mode cluster analysis and nonlinear mapping, it is possible to recognize three groups of the mare basalts, groups 1 and 2 belonging to the olivine normative basalt cluster and group 3 to the quartz normative cluster.
Butler, J. C.↗
Thermal-structural mission analyses of air-cooled gas turbine blades
Cyclic temperature and stress-strain states in cooled turbine blades were calculated for a simulated mission of an advanced technology aircraft engine. TACT1 (three dimensional heat transfer) and MARC (nonlinear structural analysis) computer programs were used to analyze impingement cooled airfoils, with and without leading-edge film cooling. Creep was the predominant damage mode, particularly around film cooling holes. Radially angled holes exhibited less creep than holes normal to surface. Beam-type analyses of all-impingement cooled airfoils gave fair agreement with MARC results for initial creep.
Kaufman, A.↗
Thermal-structural mission analyses of air-cooled gas turbine blades
Cyclic temperature and stress-strain states in cooled turbine blades were calculated for a simulated mission of an advanced technology aircraft engine. TACTl (three dimensional heat transfer) and MARC (nonlinear structural analysis) computer programs were used to analyze impingement cooled airfoils, with and without leading-edge film cooling. Creep was the predominant damage mode, particularly around film cooling holes. Radially angled holes exhibited less creep than holes normal to surface. Beam-type analyses of all-impingement cooled airfoils gave fair agreement with MARC results for initial creep.
Kaufman, A.↗
NASA/FAA general aviation crash dynamics program - An update
Work in progress in the NASA/FAA General Aviation Crash Dynamics Program for the development of technology for increased crash-worthiness and occupant survivability of general aviation aircraft is presented. Full-scale crash testing facilities and procedures are outlined, and a chronological summary of full-scale tests conducted and planned is presented. The Plastic and Large Deflection Analysis of Nonlinear Structures and Modified Seat Occupant Model for Light Aircraft computer programs which form part of the effort to predict nonlinear geometric and material behavior of sheet-stringer aircraft structures subjected to large deformations are described, and excellent agreement between simulations and experiments is noted. The development of structural concepts to attenuate the load transmitted to the passenger through the seats and subfloor structure is discussed, and an apparatus built to test emergency locator transmitters in a realistic environment is presented.
Hayduk, R. J.↗