Signature of chaos in gravitational waves from a spinning particle

A spinning test particle around a Schwarzschild black hole shows a chaotic behavior, if its spin is larger than a critical value. We discuss whether or not some peculiar signature of chaos appears in the gravitational waves emitted from such a system. Calculating the emitted gravitational waves by use of the quadrupole formula, we find that the energy emission rate of gravitational waves for a chaotic orbit is about 10 times larger than that for a circular orbit, but the same enhancement is also obtained by a regular "elliptic" orbit. A chaotic motion is not always enhance the energy emission rate maximally. As for the energy spectra of the gravitational waves, we find some characteristic feature for a chaotic orbit. It may tell us how to find out a chaotic behavior of the system. Such a peculiar behavior, if it will be found, may also provide us some additional informations to determine parameters of a system such as a spin.Comment: 14 pages, LaTeX, to appear in Phys. Rev.

Nonlinear time-series analysis of Hyperion's lightcurves

Hyperion is a satellite of Saturn that was predicted to remain in a chaotic rotational state. This was confirmed to some extent by Voyager 2 and Cassini series of images and some ground-based photometric observations. The aim of this aticle is to explore conditions for potential observations to meet in order to estimate a maximal Lyapunov Exponent (mLE), which being positive is an indicator of chaos and allows to characterise it quantitatively. Lightcurves existing in literature as well as numerical simulations are examined using standard tools of theory of chaos. It is found that existing datasets are too short and undersampled to detect a positive mLE, although its presence is not rejected. Analysis of simulated lightcurves leads to an assertion that observations from one site should be performed over a year-long period to detect a positive mLE, if present, in a reliable way. Another approach would be to use 2---3 telescopes spread over the world to have observations distributed more uniformly. This may be achieved without disrupting other observational projects being conducted. The necessity of time-series to be stationary is highly stressed.Comment: 34 pages, 12 figures, 4 tables; v2 after referee report; matches the version accepted in Astrophysics and Space Scienc

Estimation of hydrologic properties of an unsaturated, fractured rock mass

In this document, two distinctly different approaches are used to develop continuum models to evaluate water movement in a fractured rock mass. Both models provide methods for estimating rock-mass hydrologic properties. Comparisons made over a range of different tuff properties show good qualitative and quantitative agreement between estimates of rock-mass hydrologic properties made by the two models. This document presents a general discussion of: (1) the hydrology of Yucca Mountain, and the conceptual hydrological model currently being used for the Yucca Mountain site, (2) the development of two models that may be used to estimate the hydrologic properties of a fractured, porous rock mass, and (3) a comparison of the hydrologic properties estimated by these two models. Although the models were developed in response to hydrologic characterization requirements at Yucca Mountain, they can be applied to water movement in any fractured rock mass that satisfies the given assumptions

Formation and characterization of highly-dispersed metal colloid catalysts

The objective of this research is to explore the feasibility of using small metal colloids, in microemulsions, as catalysts. The product of this work will be a new concept for tailoring highly dispersed materials to specific catalytic reactions. The knowledge gained from the proposed research will be broadly applicable to variety of reactions, including hydrogenation, synthesis gas conversion, and hydrogen conversion. To achieve this objective, a plan has been formulated to prepare and characterize catalyst particles in organic solvents and to explore the use of catalyst particles. In this paper, we will discuss the use of inverse micelles to solubilize significant quantities of metal compounds in hydrocarbon solvents and their reduction, decomposition, and sulfidation to give colloidal catalytic materials. We will also discuss in detail the characterization of these materials, present preliminary results for the catalytic hydropyrolysis of coals, and discuss the results of our evaluation of selected metal colloids in catalytic hydrogenation of pyrene. 9 refs., 3 tabs

Comparison Of Mass Fluxes Predicted By The Dusty-gas And A Modified Dusty-gas Model

The equations of the dusty-gas model (homoporous model) are modified through the use of correction factors which account for the effects the pore-size and tortuosity distributions have on the mass fluxes in heteroporous media. When the correction factors approach unity, the modified dusty-gas model approaches the behavior of the dusty-gas equations; this occurs when the pressure of the system is either very low or very high because, at either extreme, almost all pores in a porous medium are in a single transport regime, that is either Knudsen or molecular diffusion. A comparison of the mass fluxes predicted by the modified dusty-gas (heteroporous model) and the dusty-gas models for binary isobaric diffusion and simultaneous flow and diffusion, shows that the percentage deviation between NiMDG and NiDG. (i species A or B) may be, in some cases, significant (up to 75% for the porous media studied in this work); this indicates that the dusty-gas model (homoporous model) could fail in predicting accurately the mass fluxes in porous media with wide pore-size distributions. The percentage deviation in the mass fluxes becomes smaller as the pressure increases above certain values at which the deviation of the correction factors from unity is small. © 1982

Chemical Reactions With Mole Changes In Heteroporous Catalysts—Part II

In this short communication, the modified dusty-gas model1-3is used to describe the mass fluxes and to estimate the effectiveness factors in the transition regime of second order irreversible reactions with mole changes in heteroporous media. The results of this note show that the effectiveness factors predicted by the dusty-gas model are larger (up to about 30% for the systems examined) than those estimated by the modified dusty-gas model which accounts for the effects the pore-size and tortuosity distributions have on the mass fluxes in industrial heteroporous catalysts. © 1984, Taylor & Francis Group, LLC. All rights reserved

Crystalline silicotitanates--new ion exchanger for selective removal of cesium and strontium from radwastes

A new class of inorganic ion exchange material called crystalline silicotitanates (CST) has been developed for radioactive waste treatment in a collaborative effort between Sandia National Laboratories and Texas A&M University. The Sandia National Laboratories Laboratory Directed Research and Development program provided the initial funding for this effort and this report summarizes the rapid progress that was achieved. A wide range of compositions were synthesized, evaluated for cesium (Cs) removal efficiency, and a composition called TAM-5 was developed that exhibits high selectivity and affinity for Cs and strontium (Sr). Tests show it can remove parts per million concentrations of Cs{sup +} from highly alkaline, high-sodium, simulated radioactive waste solutions modeled after those at Hanford, Oak Ridge, and Savannah River. In experiments with solutions that simulate highly alkaline Hanford defense wastes, the crystalline silicotitanates exhibit distribution coefficients for Cs{sup +} of greater than 2,000 ml/g, and distribution coefficients greater than 10,000 ml/g for solutions adjusted to a pH between 1 and 10. In addition, the CSTs were found to exhibit distribution coefficients for Sr{sup +} greater than 100,000 ml/g and for plutonium of 2,000 ml/g from simulated Hanford waste. The CST crystal structure was determined and positions of individual atoms identified using x-ray and neutron diffraction. The structural information has permitted identification of the ion exchange sites and provided insights into the strong effect of pH on Cs ion exchange. Information on the synthesis, composition, and structure of CST is considered proprietary and is not discussed in this report

Chemical Reactions With Mole Changes In Heteroporous Catalysts—Part I

The modified dusty-gas model1.2 is used to describe the mass fluxes for zero and first order irreversible reactions with moles changes in heteroporous catalysts, and to estimate their effectiveness factors in the transition regime. It is shown that the effectiveness factors predicted by the dusty-gas model (homoporous model) are larger than those calculated by the modified dusty-gas model (heteroporous model), in some cases by about 30%. In the Knudsen and molecular regimes, the correction factors of the modified dusty-gas model approach unity and the two models predict the same values for the effectiveness factors. Since many industrial catalysts are heteroporous and operate in the transition region of transport, the transport equations and calculational procedures presented in this work are relevant to reactor design. © 1984, Taylor & Francis Group, LLC. All rights reserved