Investigation of Northrop F-5A wing buffet intensity in transonic flight

A flight test and data processing program utilizing a Northrop F-5A aircraft instrumented to acquire buffet pressures and response data during transonic maneuvers is discussed. The data are presented in real-time format followed by spectral and statistical analyses. Also covered is a comparison of the aircraft response data with computed responses based on the measured buffet pressures

Evaluation of three analytical methods for structures under random acoustic excitation

Evaluation of three methods for determining response analysis of plate and shell structures under random acoustic excitatio

Analytical and experimental determination of localized structure to be used in laboratory vibration testing of shell structure-mounted components, Saturn V Progress report, May - Nov. 1966

Procedure for designing localized shell and finite difference computer program applications to Saturn V vibration testing projec

Assessment of wind-induced fatigue crack initiation life at guyed mast earplate joints considering welding residual stresses

A new method for assessing the degree of the cumulative fatigue crack initiation damage of the welds of earplate joints of a guyed mast,which connect the mast with the cable,is proposed.Based on the multi-scale wind-induced stress analysis of the earplate joint,and considering the welding residual stresses at the earplate joints,the critical plane approach is used for the calculation of the cumulative strain fatigue damage due to combined actions of the welding residual stresses and wind load.The multi-axis fatigue accumulative damages of the welds of earplate joints in different wind orientations and at different wind average velocities are then evaluated on basis of Mason-coffin formula and Miner fatigue accumulative damage rule.The crack germination life is also calculated from the total damage

Vertically coupled double quantum rings at zero magnetic field

Within local-spin-density functional theory, we have investigated the `dissociation' of few-electron circular vertical semiconductor double quantum ring artificial molecules at zero magnetic field as a function of inter-ring distance. In a first step, the molecules are constituted by two identical quantum rings. When the rings are quantum mechanically strongly coupled, the electronic states are substantially delocalized, and the addition energy spectra of the artificial molecule resemble those of a single quantum ring in the few-electron limit. When the rings are quantum mechanically weakly coupled, the electronic states in the molecule are substantially localized in one ring or the other, although the rings can be electrostatically coupled. The effect of a slight mismatch introduced in the molecules from nominally identical quantum wells, or from changes in the inner radius of the constituent rings, induces localization by offsetting the energy levels in the quantum rings. This plays a crucial role in the appearance of the addition spectra as a function of coupling strength particularly in the weak coupling limit.Comment: 18 pages, 8 figures, submitted to Physical Review

Proximate analysis of Lentinus squarrosulus (Mont.) Singer and Psathyrella atroumbonata Pegler

Lentinus squarrosulus and Psathyrella atroumbonata, two mushroom species commonly found growing on dead leaves and logs, were collected from the Zaria environ and taken to the laboratory for further studies. Each of the mushroom species was separated into its stipe and pileus and used for proximate analysis. There was a highly significant difference (p<0.01) in the proximate composition of the two species. P. atroumbonata had significantly higher crude protein, crude fibre and moisture content than L. squarrosulus while the reverse was the case for ash, dry matter, crude fat and soluble carbohydrates. In addition, there was a highly significant difference (p<0.01) in the proximate composition of the different mushroom parts. The pilei contained significantly higher amounts of crude protein, crude fibre, ash, and dry matter than the stipes while the converse was the case for moisture, crude fat and soluble carbohydrates. There was also a highly significant difference (p<0.01) in the interaction of species by parts.Keywords: Lentinus squarrosulus, Psathyrella atroumbonata, proximate analysi

Critical frequency for vortex nucleation in Bose-Fermi mixtures in optical lattices

We investigate within mean-field theory the influence of a one-dimensional optical lattice and of trapped degenerate fermions on the critical rotational frequency for vortex line creation in a Bose-Einstein condensate. We consider laser intensities of the lattice such that quantum coherence across the condensate is ensured. We find a sizable decrease of the thermodynamic critical frequency for vortex nucleation with increasing applied laser strength and suggest suitable parameters for experimental observation. Since 87Rb-40K mixtures may undergo collapse, we analyze the related question of how the optical lattice affects the mechanical stability of the system.Comment: 5 pages, 4 figures, revtex