Flight evaluation of advanced control systems and displays on a general aviation airplane

A flight-test program was conducted to determine the effect of advanced flight control systems and displays on the handling qualities of a light twin-engined airplane. A flight-director display and an attitude-command control system, used separately and in combination, transformed a vehicle with poor handling qualities during ILS approaches in turbulent air into a vehicle with good handling qualities. The attitude-command control system also improved the ride qualities of the airplane. A rate-command control system made only small improvements to the airplane's ILS handling qualities in turbulence. Both the rate- and the attitude-command control systems reduced stall warning in the test airplane, increasing the likelihood of inadvertent stalls. The final approach to the point of flare was improved by both the rate- and the attitude-command control systems. However, the small control wheel deflections necessary to flare were unnatural and tended to cause overcontrolling during flare. Airplane handling qualities are summarized for each control-system and display configuration

SYNTHESIS AND FABRICATION OF REFRACTORY URANIUM COMPOUNDS. Quarterly Report No. 5, August 1 through October 31, 1960

Additional quantities of UC, UN, and U/sub 3/Si/sup 2/ were prepared to be used in fabrication of test specimens for property determinations. A reduction in oxygen contamination of UN and U/sub 3/Si/sup 2/as achieved by improved techniques of synthesis.>s Preliminary values for thermal expansion, modulus of elasticity, and corrosion in boiling water were also obtained for these materials. (For preceding period see TID-6591.) (J.R.D.

SYNTHESIS AND FABRICATION OF REFRACTORY URANIUM COMPOUNDS. Monthly Progress Report No. 10 for September 1 through September 30. 1960

Several synthesis experiments were carried out to provide a stock of U/ sub 3/Si/sub 2/, powders for fabrication of test specimens. Initial thermal- expansion characteristics were determined on U/sub 3/Si/sub 2/ bars. High densities were obtained in the preparation of UN bodies. Thermal-expansion tests were made on bars of UN with a high-density silicon carbide tube dilatometer in a flowing argon atmosphere. (W.L.H.

SYNTHESIS AND FABRICATION OF REFRACTORY URANIUM COMPOUNDS. Monthly Progress Report No. 11, November 1-November 30, 1960

Batches of UC were synthesized for use in fabrication of specimens for physical property determinations. This synthesis was carried out with mixed loose powders in a graphite crucible. Two and one-half pound batches of UN were synthesized using a stainless steel boat and an Inconel muffle furnace. Three batches of U/sub 3/Si/sub 2/ were synthesized with particular emphasis on controlling the rate of the reaction by limiting the maximum temperature to 1500 deg C. In addition, determinations were made of modulus of rupture, shear modulus, and Poisson's ratio of sintered UC, UN, and U/sub 3/Si/sub 2/ specimens. (M.C.G.

Continuous Nucleation and Size Dependent Growth Kinetics of Indium Phosphide Nanocrystals

Aminophosphines derived from N,N′-disubstituted ethylenediamines (R–N(H)CH2CH2N(H)–R; R = ortho-tolyl, phenyl, benzyl, iso-propyl, and n-octyl) were used to adjust the kinetics of InP nanocrystal formation by more than 1 order of magnitude. Ultraviolet–visible absorption and 31P nuclear magnetic resonance measurements demonstrate that the rate of nanocrystal formation is limited by the precursor reactivity. At low temperature (180 °C), crystal nucleation is concurrent with growth throughout the reaction, rather than occurring in a burst at early times. The low temperature produces a narrow range of small sizes (d = 4.2–4.9 nm) regardless of the precursor used. Higher temperatures (up to 270 °C) promote growth to larger sizes (d ≤ 7.8 nm), shorten the nucleation period, and create conditions where the final size is controlled by the precursor conversion reactivity. The temperature dependence is proposed to arise from growth kinetics that slow as the nanocrystal size increases, a novel surface attachment limited size distribution-focusing mechanism. Such a mechanism supports a narrow size distribution without separating the nucleation and growth phases

Low Mach number modeling of Type I X-ray burst deflagrations

The Low Mach Number Approximation (LMNA) is applied to 2D hydrodynamical modeling of Type I X-ray bursts on a rectangular patch on the surface of a non-rotating neutron star. Because such phenomena involve decidedly subsonic flows, the timestep increase offered by the LMNA makes routine simulations of these deflagrations feasible in an environment where strong gravity produces significant stratification, while allowing for potentially significant lateral differences in temperature and density. The model is employed to simulate the heating, peak, and initial cooling stages in the deep envelope layers of a burst. During the deflagration, Benard-like cells naturally fill up a vertically expanding convective layer. The Mach number is always less than 0.15 throughout the simulation, thus justifying the low Mach number approximation. While the convective layer is superadiabatic on average, significant fluctuations in adiabaticity occur within it on subconvective timescales. Due to convective layer expansion, significant compositional mixing naturally occurs, but tracer particle penetration through the convective layer boundaries on convective timescales is temporary and spatially limited. Thus, mixing occurs on the relatively slow burst timescale through thermal expansion of the convective layer rather than from mass penetration of the convective layer boundary through particle convection. At the convective layer boundaries where mixing is less efficient, the actual temperature gradient more closely follows the Ledoux criteria.Comment: 40 pages, 13 figures, accepted by ApJ, high resolution version: http://www.astro.northwestern.edu/~lin/references/Lin_LMNA_ApJ_2006.pd

SYNTHESIS AND FABRICATION OF REFRACTORY URANIUM COMPOUNDS. Quarterly Report No. 4 for March 1 to April 30 and July 31, 1960

Additional work on the synthesis and fabrication of uranium nitride produced an improved product free of oxide contamination as indicated by x-ray analysis. Further work to increase the density of the sintered pellets is needed. A stock of several pounds of stoichiometric uranium monocarbide was prepared by carbon reduction of uranium dioxide. Pellets having bulk densities ranging from 93 to 96% theoretical were obtained by cold pressing and sfntering. Initial experiments on the fabrication of bars, 3 by 1/2 by 1/4 in., by cold pressing and sintering, resulted in sound but somewhat low-density bodies. A few experiments were conducted on the production of uranium monocarbide from ammonium diuranate. The results indicate that considerable addftional work may be necessary to consistently produce a stoichiometric product. The simultaneous synthesis ard hot pressing of uranium monocarbide was funther studied and pellets with balk densities as high as 96.6% theoretical (based on 100% UC) were produced. However, metallographic examination disclosed the presence of some free uranium metal in all pellets. The synthesis of 1-lb batches of U/sub 3/Si/sub 2/ of improved quality was successfully carried out by a nonquench method. Using the U/ sub 3/Si/sub 2/ so produced, sound pellets with bulk densities up to 98.5% theoretical were prepared by cold pressing and sintering. The sintering technique was also used to produce 3- by 1/2- by 1/4-in. bars for physical- property tests. (auth

Suitability of the predatory mites Iphiseiodes zuluagai and Euseius concordis in controlling Polyphagotarsonemus latus and Tetranychus bastosi on Jatropha curcas plants in Brazil

One of the most promising plant species for biofuel production in Brazil is the physic nut Jatropha curcas. Major phytosanitary problems include the attack of two pest mite species, the broad mite Polyphagotarsonemus latus and the spider mite Tetranychus bastosi. Owing to pesticide-related problems, there is an increasing demand for sustainable environmental-friendly control methods such as biological control. In this study we evaluated the suitability of the predatory mite species Iphiseiodes zuluagai and Euseius concordis in controlling P. latus and T. bastosi on J. curcas. The number of T. bastosi killed by I. zuluagai was lower than the number of P. latus consumed.Euseius concordis preyed upon both T. bastosi and P. latus but the number of prey killed was always lower in comparison with I. zuluagai. However, P. latus and T. bastosi are suitable for the development of I. zuluagai and E. concordis as oviposition of both predators did not differ in relation to prey species. The preference of I. zuluagai for leaves of plants infested by either P. latus or T. bastosi, combined with the higher values for predation obtained by this predatory mite when fed on P. latus, compared to those values obtained by E. concordis, suggests that I. zuluagai can be more efficient than E. concordis in reducing populations of P. latus and T. bastosi under field conditions. Furthermore, we report here on the first record of predatory mites associated with P. latus and T. bastosi on native J. curcas plants in Brazil. In conclusion, we emphasize the crucial importance of predatory mites as agents of natural biological control of mite pests on J. curcas in small farms