Passively regulated water electrolysis rocket engine Patent

Water electrolysis rocket engine with self- regulating stoichiometric fuel mixing regulato

Fluid flow meter with comparator reference means Patent

Photometric flow meter with comparator reference mean

Precision thrust gage Patent

Development of temperature compensated thrust measuring gage for measuring forces as function of time in environment with varying temperatur

Electromechanical flowmeter accurately monitors fluid flow

Electromechanical flowmeter remotely and accurately monitors the flow rate and total volume of a transparent liquid discharged from a dispensing system. A dual dispensing tube system provides a relative reference level which permits compensation for temperature variations

Optical bistability for two-level atoms in a standing-wave cavity

Observations of optical bistability are reported for a system composed of multiple atomic beams passing through a high-finesse optical cavity. Both the transmitted power and the intracavity fluorescent intensity have been recorded as functions of incident laser power for zero cavity and atomic detunings. A quantitative study has been made of the evolution of the steady-state switching intensities from well below the critical onset of bistability to well above this point. The results show reasonable agreement with a Gaussian-beam theory of optical bistability, but systematic departures are noted

Gamma-Ray Bursts via Pair Plasma Fireballs from Heated Neutron Stars

In this paper we model the emission from a relativistically expanding electron-positron pair plasma fireball originating near the surface of a heated neutron star. This pair fireball is deposited via the annihilation of neutrino pairs emanating from the surface of the hot neutron star. The heating of neutron stars may occur in close neutron star binary systems near their last stable orbit. We model the relativistic expansion and subsequent emission of the plasma and find 10^51 to 10^52 ergs in gamma-rays are produced with spectral and temporal properties consistent with observed gamma-ray bursts.Comment: 5 pages, 3 figures. Submitted to the Conference Proceedings of the 5th Huntsville Gamma-Ray Burst Symposiu

Volatile hydrocarbons inhibit methanogenic crude oil degradation

Methanogenic degradation of crude oil in subsurface sediments occurs slowly, but without the need for exogenous electron acceptors, is sustained for long periods and has enormous economic and environmental consequences. Here we show that volatile hydrocarbons are inhibitory to methanogenic oil biodegradation by comparing degradation of an artificially weathered crude oil with volatile hydrocarbons removed, with the same oil that was not weathered. Volatile hydrocarbons (nC5-nC10, methylcyclohexane, benzene, toluene, and xylenes) were quantified in the headspace of microcosms. Aliphatic (n-alkanes nC12-nC34) and aromatic hydrocarbons (4-methylbiphenyl, 3-methylbiphenyl, 2-methylnaphthalene, 1-methylnaphthalene) were quantified in the total hydrocarbon fraction extracted from the microcosms. 16S rRNA genes from key microorganisms known to play an important role in methanogenic alkane degradation (Smithella and Methanomicrobiales) were quantified by quantitative PCR. Methane production from degradation of weathered oil in microcosms was rapid (1.1 ± 0.1 μmol CH4/g sediment/day) with stoichiometric yields consistent with degradation of heavier n-alkanes (nC12-nC34). For non-weathered oil, degradation rates in microcosms were significantly lower (0.4 ± 0.3 μmol CH4/g sediment/day). This indicated that volatile hydrocarbons present in the non-weathered oil inhibit, but do not completely halt, methanogenic alkane biodegradation. These findings are significant with respect to rates of biodegradation of crude oils with abundant volatile hydrocarbons in anoxic, sulphate-depleted subsurface environments, such as contaminated marine sediments which have been entrained below the sulfate-reduction zone, as well as crude oil biodegradation in petroleum reservoirs and contaminated aquifers

Design and testing of a contra-rotating tidal current turbine

A contra-rotating marine current turbine has a number of attractive features: nearzero reactive torque on the support structure, near-zero swirl in the wake, and high relative inter-rotor rotational speeds. Modified blade element modelling theory has been used to design and predict the characteristics of such a turbine, and a model turbine and test rig have been constructed. Tests in a towing tank demonstrated the feasibility of the concept. Power coefficients were high for such a small model and in excellent agreement with predictions, confirming the accuracy of the computational modelling procedures. High-frequency blade loading data were obtained in the course of the experiments. These show the anticipated dynamic components for a contra-rotating machine. Flow visualization of the wake verified the lack of swirl behind the turbine. A larger machine is presently under construction for sea trials

Evolution from a molecular Rydberg gas to an ultracold plasma in a seeded supersonic expansion of NO

We report the spontaneous formation of a plasma from a gas of cold Rydberg molecules. Double-resonant laser excitation promotes nitric oxide, cooled to 1 K in a seeded supersonic molecular beam, to single Rydberg states extending as deep as 80 cm$^{-1}$ below the lowest ionization threshold. The density of excited molecules in the illuminated volume is as high as 1 x 10$^{13}$ cm$^{-3}$. This population evolves to produce prompt free electrons and a durable cold plasma of electrons and intact NO$^{+}$ ions.Comment: 4 pages (two column) 3 figures; smaller figure files, corrected typo