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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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Development of acoustic lining for turbofan nacelle modification to minimize fan compressor noise radiation
Flightworthy nacelle development to minimize fan compressor noise radiation - Vol. 4
Automatic power supply circuit design for driving inductive loads and minimizing power consumption including solenoid example
Design and characteristics of supersonic inlet controls for minimizing inlet unstarts
Studying mechanism of flame spreading over surface of igniting polystyrene and polymethyl methacrylate for minimizing fire hazard in space capsules
Quasi-Newtonian minimization methods extended to infinite dimensional Hilbert space with applications to optimal control problems
Predicting characteristics of minimal total impulse solution of two-terminal, two-impulse orbital transfer problem by using bounding trajectories
Conjugate direction minimization procedure based on sequences and inferred second partial derivative matrix inverse
Minimization of unconstrained function of several variables by gradient dependent techniques, discussing applications to boundary value problems in optimal control
Minimization algorithms unified derivation, using Hessian matrix inverse
Sonic boom minimization including front and rear shocks, exemplified by SST aircraft
Minimal partial realizations of linear input/output map, discussing significance in regard to adaptive dynamics identification procedures
Recorder deficiencies are minimized by using two-channel system to prepare two tapes, each having noise, wow and flutter, and dropout characteristics of channel on which it was made. Processing tapes by computer and combining signals from two channels produce single tape free of dropouts caused by recording process.
A modified Newton-Raphson or quasilinearization minimization technique for determining stability derivatives from flight data was developed and compared with simple-equations, analog-matching, least-squares, and Shinbrot methods of analysis. For the data analyzed, the solutions computed by using the estimates obtained from the Newton-Raphson technique fit the data and determined coefficients adequately. A further modification to include a priori information was found to be useful. A model statistically similar to the flight data was analyzed using the same methods (excluding analog matching), and the Newton-Raphson technique was found to yield superior estimates. An approximate Cramer-Rao bound was compared with the error covariance matrix of the model and was found to provide information about the reliability of the individual estimates obtained. The technique was successfully applied to data obtained from a light airplane, a large supersonic airplane, and a lifting body vehicle. It was shown that the reliability of the estimates of a given coefficient obtained from these vehicles depends upon the data analyzed.
A mathematical expression was derived describing multipacting and corona effects in a coaxial cavity. Both mechanical and electrical design techniques were investigated to minimize the susceptibility of coaxial cavity to corona and multipacting-type breakdown. To assist in the design of a multicoupler free from corona and multipactor breakdown, a flow chart obtained from the derived mathematical expression is included.
The applicability of sonic boom minimization concepts in the design of large supersonic transport airplanes capable of a 2500-nautical-mile range at a cruise Mach number of 2.7 is considered. Aerodynamics, weight and balance, and mission performance as well as sonic boom factors, have been taken into account. The results indicate that shock-strength nominal values of somewhat less than 48 newtons/sq m during cruise are within the realm of possibility. Because many of the design features are in direct contradiction to presently accepted design practices, further study of qualified airplane design teams is required to ascertain sonic boom shock strength levels actually attainable for practical supersonic transports.
CONMIN is a FORTRAN program, in subroutine form, for the solution of linear or nonlinear constrained optimization problems. The basic optimization algorithm is the Method of Feasible Directions. The user must provide a main calling program and an external routine to evaluate the objective and constraint functions and to provide gradient information. If analytic gradients of the objective or constraint functions are not available, this information is calculated by finite difference. While the program is intended primarily for efficient solution of constrained problems, unconstrained function minimization problems may also be solved, and the conjugate direction method of Fletcher and Reeves is used for this purpose. This manual describes the use of CONMIN and defines all necessary parameters. Sufficient information is provided so that the program can be used without special knowledge of optimization techniques. Sample problems are included to help the user become familiar with CONMIN and to make the program operational.
An alternative method for deriving the generalized inverse of an arbitrary rectangular matrix with real or complex coefficients is described. The method applies a classical minimization procedure without iteration processes and is readily applicable in digital computer programming.