Fluctuating loops and glassy dynamics of a pinned line in two dimensions

We represent the slow, glassy equilibrium dynamics of a line in a two-dimensional random potential landscape as driven by an array of asymptotically independent two-state systems, or loops, fluctuating on all length scales. The assumption of independence enables a fairly complete analytic description. We obtain good agreement with Monte Carlo simulations when the free energy barriers separating the two sides of a loop of size L are drawn from a distribution whose width and mean scale as L^(1/3), in agreement with recent results for scaling of such barriers.Comment: 11 pages, 4 Postscript figure

Analysis of the effectiveness of industrial R and D

The criteria used by private industry in evaluating and selecting proposed research and development projects for implementation, and also in determining which R and D facilities are to be acquired were investigated. Conceptual and practical issues inherent in any quantitative analysis of the contribution of R and D to economic growth were identified in order to assist NASA in developing approaches for analzying the economic implication of its own R and D efforts

Texas minerals : trends in production

UT Librarie

Models of planetary rings

The Voyager occultations provide several uniform and high quality data sets for Saturn, Uranus, and Neptune. These data are intercompared, and theoretical models for the particle sizes and the particle transport are developed. The major topics covered include: ring size distribution, torques and resonances, and satellite wakes

Use of ERTS-1 data in identification, classification, and mapping of salt-affected soils in California

There are no author-identified significant results in this report

Southern Sky Redshift Survey: Clustering of Local Galaxies

We use the two-point correlation function to calculate the clustering properties of the recently completed SSRS2 survey. The redshift space correlation function for the magnitude-limited SSRS2 is given by xi(s)=(s/5.85 h-1 Mpc)^{-1.60} for separations between 2 < s < 11 h-1 Mpc, while our best estimate for the real space correlation function is xi(r) = (r/5.36 h-1 Mpc)^{-1.86}. Both are comparable to previous measurements using surveys of optical galaxies over much larger and independent volumes. By comparing the correlation function calculated in redshift and real space we find that the redshift distortion on intermediate scales is small. This result implies that the observed redshift-space distribution of galaxies is close to that in real space, and that beta = Omega^{0.6}/b < 1, where Omega is the cosmological density parameter and b is the linear biasing factor for optical galaxies. We also use the SSRS2 to study the dependence of xi on the internal properties of galaxies. We confirm earlier results that luminous galaxies (L>L*) are more clustered than sub-L* galaxies and that the luminosity segregation is scale-independent. We find that early types are more clustered than late types, but that in the absence of rich clusters, the relative bias between early and late types in real space, is not as strong as previously estimated. Furthermore, both morphologies present a luminosity-dependent bias, with the early types showing a slightly stronger dependence on luminosity. We also find that red galaxies are significantly more clustered than blue ones, with a mean relative bias stronger than that seen for morphology. Finally, we find that the relative bias between optical and iras galaxies in real space is b_o/b_I $\sim$ 1.4.Comment: 43 pages, uses AASTeX 4.0 macros. Includes 8 tables and 16 Postscript figures, updated reference

The efficiency of HFMI treatment and TIG remelting for extending the fatigue life of existing welded structures

Different post‐weld treatment methods have been developed to enhance the fatigue strength of welded steel structures and extend the service lives of their components. High‐frequency mechanical impact (HFMI) treatment and tungsten inert gas (TIG) remelting are two methods that have attracted considerable interest in recent decades. This paper presents the results of a study of fatigue life extension for pre‐fatigued welded steel details which can be achieved using HFMI treatment and TIG remelting. More than 250 fatigue test results were collected – including different details such as butt welds, longitudinal attachments, transverse attachments and cover plate attachments. HFMI treatment was found to extend the life considerably when the specimens treated were free from cracks or when existing cracks were &lt; 2.25 mm deep. TIG remelting could extend fatigue lives even with cracks &gt; 4 mm deep. In comparison to TIG remelting, HFMI treatment results in a longer fatigue life extension for pre‐fatigued details, provided existing cracks are &lt; 2.25 mm deep. Regarding TIG remelting, the depth of possible remaining cracks was found to be a substantial parameter when assessing the degree of life extension