My Lucky Star

https://digitalcommons.library.umaine.edu/mmb-vp/3675/thumbnail.jp

Altitude Performance and Operational Characteristics of YJ71-A-7 Turbojet Engine

Altitude performance of a YJ71-A-7 turbojet engine, with afterburner inoperative, was determined in the NACA Lewis altitude wind tunnel over a wide range of flight conditions. Engine speed and exhaust-nozzle area were controlled independently during this investigation. The variation of corrected values of air flow, net thrust, and fuel flow with corrected engine speed was not defined by a single curve with changes in altitude at given flight Mach number. Changes in altitude had very little effect on minimum specific fuel consumption at altitudes up to 45,000 feet. There is one exhaust-nozzle schedule that is nearly optimum for all flight conditions. Performance calculated from pumping characteristics agreed with experimental values and can therefore be used to extend engine performance data

Performance of a turbojet engine with adjustable first-stage turbine stator and variable-area exhaust nozzle

The performance of a turbojet engine with a two-stage turbine, an adjustable first-stage turbine stator, and a variable-area exhaust nozzle was investigated at selected constant engine speeds and two simulated flight conditions. For the particular component characteristics of the engine investigated, little improvement in thrust levels of interest by use of an adjustable rather than an optimum fixed first-stage turbine stator

Design considerations for a Space Station radiation shield for protection from both man-made and natural sources

This study was conducted to analyze scenarios involving the use of nuclear-power vehicles in the vicinity of a manned Space Station (SS) in low-earth-orbit (LEO) to quantify their radiological impact to the station crew. In limiting the radiant dose to crew members, mission planners may (1) shut the reactor down prior to reentry, (2) position the vehicle at a prescribed parking distance, and (3) deploy radiation shield about the shutdown reactor. The current report focuses on the third option in which point-kernel gamma-ray shielding calculations were performed for a variety of shield configurations for both nuclear electric propulsion (NEP) and nuclear thermal rocket (NTR) vehicles. For a returning NTR vehicle, calculations indicate that a 14.9 MT shield would be needed to limit the integrated crew exposure to no more than 0.05 Sv over a period of six months (25 percent of the allowable exposure to man-made radiation sources). During periods of low vehicular activity in LEO, the shield may be redeployed about the SS habitation module in order to decrease crew exposures to trapped proton radiations by approximately a factor of 10. The corresponding shield mass required for deployment at a returning NEP vehicle is 2.21 MT. Additional scenarios examined include the radioactivation of various metals as might be found in tools used in EVA activities

Encapsulated Molecules in Carbon Nanotubes: Structure and Properties

We encapsulate a number of fullerenes inside single-walled carbon nanotubes (SWNTs) including La2@C80 and ErxSc3-xN@C80(x=0-3). The structural properties of these nanoscopic hybrid materials are described using high resolution transmission electron microscopy and electron diffraction. It is found that the encapsulated fullerenes selfassemble into long, one-dimensional chains. The thermal stability of these supramolecular assemblies are studied and large variations are found. The behavior is nominally consistent with the mass of the encapsulated metallofullerenes

Supercritical Fluid (SCF) Treatment: Its Effect on Bending Strength and Stiffness of Ponderosa Pine Sapwood

Adverse effects on mechanical properties from using a supercritical fluid (SCF) to increase preservative penetration of refractory woods were evaluated by treating small ponderosa pine sapwood specimens with supercritical carbon dioxide at 64 combinations of temperatures (35 to 80 C), pressure (1,000 to 4,000 psig), and time (0.5 to 2 h). Thereafter, the treated and identical untreated specimens were equilibrated to constant moisture content and tested for bending strength and stiffness. The SCF-treated and untreated specimens were not significantly different in modulus of rupture (MOR) or modulus of elasticity (MOE). Temperature, pressure, and time had no significant effect on MOR; there were interacting effects of these variables on MOE, although these interactions had no meaningful patterns

Supercritical Fluid (SCF) Treatment: Its Effect on Bending Strength and Stiffness of Ponderosa Pine Sapwood

Adverse effects on mechanical properties from using a supercritical fluid (SCF) to increase preservative penetration of refractory woods were evaluated by treating small ponderosa pine sapwood specimens with supercritical carbon dioxide at 64 combinations of temperatures (35 to 80 C), pressure (1,000 to 4,000 psig), and time (0.5 to 2 h). Thereafter, the treated and identical untreated specimens were equilibrated to constant moisture content and tested for bending strength and stiffness. The SCF-treated and untreated specimens were not significantly different in modulus of rupture (MOR) or modulus of elasticity (MOE). Temperature, pressure, and time had no significant effect on MOR; there were interacting effects of these variables on MOE, although these interactions had no meaningful patterns

Synthesis and Characterization of [Ir_2(TMB)_4H_2][B(C_6H_5)_4]_2·CH_3C_6H_5

The ^3(dσ *pσ) excited state of Ir_2(TMB)_4^(2+) (TMB = 2,5-diisocyano-2,5-dimethylhexane) reacts with hydrogen atom donors to give Ir_2(TMB)_4H_2^(2+) (Ir_2H_2). This d^7-d^7 dihydride has been isolated as a tetraphenylborate salt: v(Ir-H) 1940 cm^(-1), v(Ir-Ir) 136 cm^(-1). [Ir_2(TMB)_4H_2] [B(C_6H_5) _4]_2·CH_3C_6H_5, Ir_2C_(95)H_(114)N_8B_2, crystallizes in the monoclipic system, space group P2_1/c (No. 14), with a = 10.54 (2) Å, b = 31.02 (4) Å, and c = 27.05 (4) Å, β = 91.57 (3)°, V = 8841 (3) Å^3, and Z = 4. The Ir-Ir separation is 2.920 (2) Å, approximately 0.3 Å shorter than Ir-Ir in the d^8 dimer (lr_2) but ~0.1 Å longer than in the diiodide, Ir_2(TMB)_4I_2^(2+). The reaction of Ir_2H_2 with styrene gives Ir_2 and ethylbenzene