Study of indicial aerodynamic forces of multistage space vehicle systems. Volume 1 - Application of theory to basic geometries and to the Saturn 5 Final report, 28 Jun. 1967 - 27 Sep. 1968

Potential theory for determining aerodynamic forces of axisymmetric vehicles and Saturn

Fundamental investigation of stress corrosion cracking

Two principle areas studied were stress corrosion crack growth rates of a titanium alloy in liquid environments containing halide ions and pitting corrosion of titanium in bromide solutions. Two initial assumptions were made, that the rate of propagation was controlled by a macroscopic solution parameter and that this parameter was viscosity. A series of solutions were prepared using lithium chloride as the solute and water, methanol, glycerin, formic acid, acetone, dimethyl sulphoxide, etc. As solvents, these solutions were prepared with a 5:1 solvent-solute ratio. Viscosity was varied by changing the temperature and it was found: (1) In all solvents the velocity of cracking was proportional to the reciprocal of the viscosity. (2) Each solvent gave a separate relationship, (3) The temperature dependence and numerical values for the apparent activation energy of cracking and viscosity were the same

Stress corrosion cracking of titanium alloys: Studies of cracks in thin specimens; SCC of Ti-6Al-4V in chloride, iodide and fluoride solutions; stress corrosion cracking in molten salts; electrochemistry of freshly generated titanium surfaces

Electrochemistry of freshly generated titanium surfaces and stress corrosion cracking in aqueous solutions and in molten salt

Impacts of Grazing on Watersheds: A State of Knowledge.

36 pgLivestock grazing affects watershed hydrologic properties by removing protective plant cover and by trampling. Reductions in the vegetation cover may: (a) increase the impact of raindrops, (b) decrease soil organic matter and soil aggregates, (c) increase surface crusts, (d) decrease infiltration rates, and/or increase erosion. Resultant impacts may include increased overland flow, reduced soil water content, and increased erosion. Bacteria and/or nutrients as potential pollutants from livestock grazing do not appear to be a problem on areas not included on riparian zones. Existing studies show no hydrologic advantage to grazing a watershed lightly rather than moderately. Some studies show no difference in soil loss, infiltration capacity, or soil bulk density between light. moderate, or ungrazed pastures. Little information supports claims for specialized grazing systems. To evaluate hydrologic impacts adequately, additional studies, both intensive and extensive, should be conducted

Quasistationary binary inspiral. I. Einstein equations for the two Killing vector spacetime

The geometry of two infinitely long lines of mass moving in a fixed circular orbit is considered as a toy model for the inspiral of a binary system of compact objects due to gravitational radiation. The two Killing fields in the toy model are used, according to a formalism introduced by Geroch, to describe the geometry entirely in terms of a set of tensor fields on the two-manifold of Killing vector orbits. Geroch's derivation of the Einstein equations in this formalism is streamlined and generalized. The explicit Einstein equations for the toy model spacetime are derived in terms of the degrees of freedom which remain after a particular choice of gauge.Comment: 37 pages, REVTeX, one PostScript Figure included with epsfig; minor formatting changes and copyright notice added for journal publicatio

Periodic Solutions of the Einstein Equations for Binary Systems

This revision includes clarified exposition and simplified analysis. Solutions of the Einstein equations which are periodic and have standing gravitational waves are valuable approximations to more physically realistic solutions with outgoing waves. A variational principle is found which has the power to provide an accurate estimate of the relationship between the mass and angular momentum of the system, the masses and angular momenta of the components, the rotational frequency of the frame of reference in which the system is periodic, the frequency of the periodicity of the system, and the amplitude and phase of each multipole component of gravitational radiation. Examination of the boundary terms of the variational principle leads to definitions of the effective mass and effective angular momentum of a periodic geometry which capture the concepts of mass and angular momentum of the source alone with no contribution from the gravitational radiation. These effective quantities are surface integrals in the weak-field zone which are independent of the surface over which they are evaluated, through second order in the deviations of the metric from flat space.Comment: 18 pages, RevTeX 3.0, UF-RAP-93-1

Toxicity and bioaccumulation of TNT in marine fish in sediment exposures

The bioaccumulation potential and toxicity of 2, 4, 6-trinitrotoluene (TNT) spiked to sediment was evaluated in juvenile sheeps head minnows (JSHM, Cyprinodon variegatus) and adult freckled blennies (FB, Hypsoblennius ionthas). The JSHM were exposed for 4 days in the presence or absence of a mesh separating fish from sediment. FB were exposed to sediment for 7 days. During the 24-day storage period(4 °C), extensive transformation of spiked TNT occurred and concentrations are expressed as the sum of TNT, aminodinitrotoluenes and diaminonitrotoluenes (Sum TNT), on a dry weight basis. Sum TNT in the overlying water, not exchanged during exposure, increased gradually. Survival was high( ≥ 90%) for JSHM exposed to 7 mgkg-1 and FB exposed to up to 260 mgkg-1. All SHM died after 24-h exposure to 340 mgkg-1. Isolation from sediment did not significantly affect water concentrations or decrease bioaccumulation. Uptake from contact to sediment was likely negligible and bioaccumulation was from the overlying water. The feeding rate of FB exposed to 1700 μmol kg-1 sediment suspended in water for 24-h was significantly reduced by 50%