Aeronautical Engineering: A continuing bibliography with indexes (supplement 165)

This bibliography lists 466 reports, articles and other documents introduced into the NASA scientific and technical information system in August 1983

Aeronautical Engineering: A continuing bibliography with indexes (supplement 177)

This bibliography lists 469 reports, articles and other documents introduced into the NASA scientific and technical information system in July 1984

Aeronautical Engineering: A Continuing Bibliography with indexes

This bibliography lists 426 reports, articles and other documents introduced into the NASA scientific and technical information system in August 1984. Reports are cited in the area of Aeronautical Engineering. The coverage includes documents on the engineering and theoretical aspects of design, construction, evaluation, testing operation and performance of aircraft (including aircraft engines) and associated components, equipment and systems

Optimal control of geometric partial differential equations

Optimal control problems for geometric (evolutionary) partial differential inclusions are considered. The focus is on problems which, in addition to the nonlinearity due to geometric evolution, contain optimization theoretic challenges because of non-smoothness. The latter might stem from energies containing non-smooth constituents such as obstacle-type potentials or terms modeling, e.g., pinning phenomena in microfluidics. Several techniques to remedy the resulting constraint degeneracy when deriving stationarity conditions are presented. A particular focus is on Yosida-type mollifications approximating the original degenerate problem by a sequence of nondegenerate nonconvex optimal control problems. This technique is also the starting point for the development of numerical solution schemes. In this context, also dual-weighted residual based error estimates are addressed to facilitate an adaptive mesh refinement. Concerning the underlying state model, sharp and diffuse interface formulations are discussed. While the former always allows for accurately tracing interfacial motion, the latter model may be dictated by the underlying physical phenomenon, where near the interface mixed phases may exist, but it may also be used as an approximate model for (sharp) interface motion. In view of the latter, (sharp interface) limits of diffuse interface models are addressed. For the sake of presentation, this exposition confines itself to phase field type diffuse interface models and, moreover, develops the optimal control of either of the two interface models along model applications. More precisely, electro-wetting on dielectric is used in the sharp interface context, and the control of multiphase fluids involving spinodal decomposition highlights the phase field technique. Mathematically, the former leads to a Hele-Shaw flow with geometric boundary conditions involving a complementarity system due to contact line pinning, and the latter gives rise to a Cahn-Hilliard Navier-Stokes model including a non-smooth obstacle type potential leading to a variational inequality constraint

Morphing Waveriders for Atmospheric Entry

The primary challenge for vehicles entering planetary atmospheres is surviving the intense heating and deceleration encountered during the entry process. Entry capsules use sacrificial ablative heat shields and sustain several g deceleration. The high lift produced by the Space Shuttle geometry resulted in lower rates of heating and deceleration. This enabled a fully reusable vehicle that was protected by heat shield tiles. Hypersonic waveriders are vehicles that conform to the shape of the shock wave created by the vehicle. This produces high compression-lift and low drag, but only around a design Mach number. Atmospheric entry can reach speeds from zero to as high as Mach 40. A morphing waverider is a vehicle that deflects its flexible bottom surface as a function of Mach number in order to preserve a desired shock wave shape. It was demonstrated in this work that doing so retains high aerodynamic lift and lift-to-drag ratio across a wide range of Mach number. Numerical simulations were conducted for case-study waveriders designed for Mach 6 and 8 for flight at their design conditions as well as with variations in angle-of-attack and Mach number. A single-species air model was used between Mach 1 and 12 with the RANS k-omega SST and LES-WALE turbulence models. A seven-species air model was used for Mach 15 at 60km altitude and Mach 20 at 75km. Analytical methods were used to construct a reduced-order model (ROM) for estimating waverider aerodynamic forces, moments, and heating. The ROM matched numerical simulation results within 5-10% for morphing waveriders with variations in angle-of-attack, but discrepancies exceeded 20% for large deviations of rigid vehicles from their design Mach numbers. Atmospheric entry trajectory simulations were conducted using reduced-order models for morphing waverider aerodynamics, the Mars Science Laboratory (MSL) capsule, and the Space Shuttle. Three morphing waveriders were compared to the Space Shuttle, which resulted in reduced heating and peak deceleration. One morphing waverider was compared to the MSL capsule, which demonstrated a reduction in the peak stagnation heat flux, a reduction in the peak and average deceleration, and a reduction in the peak area-averaged heating

Aeronautical engineering: A continuing bibliography with indexes (supplement 210)

This bibliography lists 409 reports, articles and other documents introduced into the NASA scientific and technical information system in January 1987

Aeronautical Engineering: A cumulative index to the 1984 issues of the continuing bibliography

This bibliography is a cumulative index to the abstracts contained in NASA SP-7037(171) through NASA SP-7037(182) of Aeronautical Engineering: A Continuing Bibliography. NASA SP-7037 and its supplements have been compiled through the cooperative efforts of the American Institute of Aeronautics and Astronautics (AIAA) and the National Aeronautics and Space Administration (NASA). This cumulative index includes subject, personal author, corporate source, foreign technology, contract, report number, and accession number indexes

A cumulative index to Aeronautical Engineering: A special bibliography, January 1976

This publication is a cumulative index to the abstracts contained in NASA SP-7037 (54) through NASA SP-7037 (65) of Aeronautical Engineering: A Special Bibliography. NASA SP-7037 and its supplements have been compiled through the cooperative efforts of the American Institute of Aeronautics and Astronautics (AIAA) and the National Aeronautics and Space Administration (NASA). This cumulative index includes subject, personal author, corporate source, contract, and report number indexes

Measuring the spatiotemporal electric field of ultrashort pulses with high spatial and spectral resolution

In this thesis a powerful and practical method for characterizing ultrashort pulses in space and time is described (called SEA TADPOLE). First we focus on measuring pulses that are spatially uniform but very complicated in time or frequency. We demonstrate and verify that SEA TADPOLE can measure temporal features as small as 30 femtoseconds over durations as long as 14 picoseconds. The spectral resolution of this device is carefully studied and we demonstrate that for certain pulses, we achieve spectral super resolution. We also develop and test an algorithm for measuring polarization shaped pulses with SEA TADPOLE. Our simple interferometer can even be used to measure the spatiotemporal electric field of ultrashort pulses at a focus. This is because SEA TADPOLE samples the field with an optical fiber which has a small core size. Therefore this fiber can be used to spatially sample the beam, so that the temporal electric field can be measured at every position to obtain E(x, y, z, t). The single mode fiber can be replaced with an NSOM (Near Field Scanning Optical Microscopy) fiber so that spatial resolution as low as 500nm (and possibly lower) can be achieved. Using this device we make the first direct measurements of the compete field of focusing ultrashort pulses. These measurement can be viewed as "snap shots" in flight of the focusing pulse. Also, for the first time, we have observed some of the interesting distortions that have been predicted for focusing ultrashort pulses such as the "forerunner" pulse, radially varying group delay dispersion, and the Bessel-like X-shaped pulse. We have also made the first direct measurements of the electric field of Bessel X-pulses and their propagation invariance is demonstrated. We also use SEA TADPOLE to study the "boundary wave pulses" which are due to diffraction.Ph.D.Committee Chair: Rick Trebino; Committee Member: Jennifer Curtis; Committee Member: John Buck; Committee Member: Mike Chapman; Committee Member: Stephen Ralp

Aeronautical engineering: A continuing bibliography with indexes (supplement 289)

This bibliography lists 792 reports, articles, and other documents introduced into the NASA scientific and technical information system in Mar. 1993. Subject coverage includes: design, construction and testing of aircraft and aircraft engines; aircraft components, equipment, and systems; ground support systems; and theoretical and applied aspects of aerodynamics and general fluid dynamics