Characterisation of friction and lubrication regimes in premium tubular connections

A friction test rig has been developed to carry out repeated sliding friction tests for premium tubular connections. The test rig enables accurate measurement of friction in various contact regimes which are relevant to the threaded connections between tubular components. Higher load tests can simulate the contact in metal-to-metal seals under very high contact pressures by using perpendicular pin-on-pin tests. The contact in the thread loading flank under intermediate pressures can be simulated by using larger radius coupon-on-coupon tests. The measured coefficient of friction is well correlated with a lubrication parameter combining lubricant film thickness and initial surface roughness. © 2012 Elsevier Ltd. All rights reserved

Dynamic Network Mechanisms of Relational Integration

A prominent hypothesis states that specialized neural modules within the human lateral frontopolar cortices (LFPCs) support “relational integration” (RI), the solving of complex problems using inter-related rules. However, it has been proposed that LFPC activity during RI could reflect the recruitment of additional “domain-general” resources when processing more difficult problems in general as opposed to RI specifi- cally. Moreover, theoretical research with computational models has demonstrated that RI may be supported by dynamic processes that occur throughout distributed networks of brain regions as opposed to within a discrete computational module. Here, we present fMRI findings from a novel deductive reasoning paradigm that controls for general difficulty while manipulating RI demands. In accordance with the domain- general perspective, we observe an increase in frontoparietal activation during challenging problems in general as opposed to RI specifically. Nonetheless, when examining frontoparietal activity using analyses of phase synchrony and psychophysiological interactions, we observe increased network connectivity during RI alone. Moreover, dynamic causal modeling with Bayesian model selection identifies the LFPC as the effective connectivity source. Based on these results, we propose that during RI an increase in network connectivity and a decrease in network metastability allows rules that are coded throughout working memory systems to be dynamically bound. This change in connectivity state is top-down propagated via a hierarchical system of domain-general networks with the LFPC at the apex. In this manner, the functional network perspective reconciles key propositions of the globalist, modular, and computational accounts of RI within a single unified framework

On the interaction forces and responses of structural rings subjected to fragment impact Interim technical report, 1 Aug. 1969 - 31 Jul. 1970

FORTRAN 4 program for calculating dynamic Kirchhoff deformation of structural rings subjected to fragment impac

Cluster Populations in A115 and A2283

This paper presents four color narrow-band photometry of clusters A115 ($z=0.191$) and A2283 ($z=0.182$) in order to follow the star formation history of various galaxy types. Although located at similar redshifts, the two clusters display very different fractions of blue galaxies (i.e. the Butcher-Oemler effect, $f_B = 0.13$ for A115, $f_B = 0.30$ for A2283). A system of photometric classification is applied to the cluster members that divides the cluster population into four classes based on their recent levels of star formation. It is shown that the blue population of each cluster is primarily composed of normal starforming (SFR < 1 M_{\sun} yrs$^{-1}$) galaxies at the high luminosity end, but with an increasing contribution from a dwarf starburst population below $M_{5500}= -20$. This dwarf starburst population appears to be the same population of low mass galaxies identified in recent HST imaging (Koo et al 1997), possible progenitors to present-day cluster dwarf ellipticals, irregulars and BCD's. Deviations in the color-magnitude relationship for the red galaxies in each cluster suggest that a population of blue S0's is evolving into present-day S0 colors at this epoch. The radial distribution of the blue population supports the prediction of galaxy harassment mechanisms for tidally induced star formation operating on an infalling set of gas-rich galaxies.Comment: 28 pages including 2 tables and 9 figures, AASTeX v4.0. Accepted by Ap.J. Data, referee report and response are avaliable from http://zebu.uoregon.edu/~j

Global Dimension of Polynomial Rings in Partially Commuting Variables

For any free partially commutative monoid $M(E,I)$, we compute the global dimension of the category of $M(E,I)$-objects in an Abelian category with exact coproducts. As a corollary, we generalize Hilbert's Syzygy Theorem to polynomial rings in partially commuting variables.Comment: 11 pages, 2 figure

The IRAS 1-Jy Survey of Ultraluminous Infrared Galaxies: I. The sample and Luminosity Function

A complete flux-limited sample of 118 ultraluminous infrared galaxies (ULIGs) has been identified from the IRAS Faint Source Catalog (FSC). The selection criteria were a 60 micron flux density greater than 1 Jy in a region of the sky delta > -40 deg, |b| > 30 deg. All sources were subsequently reprocessed using coadded IRAS maps in order to obtain the best available flux estimates in all four IRAS wavelength bands. The maximum observed infrared luminosity is L_ir = 10^{12.90} L_{sun}, and the maximum redshift is z = 0.268. The luminosity function for ULIGs over the decade luminosity range L_ir = 10^{12} - 10^{13} L_{sun} can be approximated by a power law Phi (L) ~= L^{-2.35} Mpc^{-3} mag^{-1}. In the local Universe z < 0.1, the space density of ULIGs appears to be comparable to or slightly larger than that of optically selected QSOs at comparable bolometric luminosities. A maximum likelihood test suggests strong evolution for our sample; assuming density evolution proportional to (1+z)^{alpha} we find alpha = 7.6+/-3.2. Examination of the two-point correlation function shows a barely significant level of clustering, xi (r) = 1.6 +/- 1.2, on size scales r ~= 22 h^{-1} Mpc.Comment: 18 pages of text, 10 pages of figures 1 to 6, 6 pages of tables 1 to 3, ApJS accepte

Attentional biases for food stimuli in external eaters: Possible mechanism for stress-induced eating?

External eaters reportedly increase snack intake when stressed, which could be due to an attentional shift towards food stimuli. Attentional biases for food stimuli were tested in high and low external eaters in stress and control conditions, using a computerised Stroop. A significant interaction was observed between external eating group and condition for snack word bias. This suggested that low external eaters have a greater bias for snack words when unstressed and that stressed, high external eaters have a greater bias for snack words than stressed, low external eaters, which could contribute to stress-induced snack intake in high external eaters