Performance Practice Bibliography 1990

A bibliography concerning works published in the field of historical performance practice in 1990

Mass Outflow from Red Giant Stars in M13, M15, and M92

Chromospheric model calculations of the Halpha line for selected red giant branch (RGB) and asymptotic giant branch (AGB) stars in the globular clusters M13, M15, and M92 are constructed to derive mass loss rates. The model spectra are compared to the observations obtained with the Hectochelle on the MMT telescope. These stars show strong Halpha emissions and blue-shifted Halpha cores signaling that mass outflow is present in all stars. Outflow velocities of 3-19 km/s, larger than indicated by Halpha profiles, are needed in the upper chromosphere to achieve good agreement between the model spectra and the observations. The resulting mass loss rates range from 0.6*10^{-9} to 5*10^{-9} Msun/yr, which are about an order of magnitude lower than predicted from "Reimers' law" or inferred from the infrared excess of similar stars. The mass loss rate increases slightly with luminosity and with decreasing effective temperature. Stars in the more metal-rich M13 have higher mass loss rates by a factor of ~2 than in the metal-poor clusters M15 and M92. A fit to the mass loss rates is given by: M [Msun/yr] = 0.092 * L^{0.16} * Teff^{-2.02} * A^{0.37} where A=10^[Fe/H]. Multiple observations of stars revealed one object in M15, K757, in which the mass outflow increased by a factor of 6 between two observations separated by 18 months. Other stars showed changes in mass loss rate by a factor of 1.5 or less.Comment: 28 pages, 10 figures, 3 tables, Accepted in Astronomical Journa

Improving the Systems Engineering Process with Multilevel Analysis of Interactions

The systems engineering V (SE-V) is an established process model to guide the development of complex engineering projects (INCOSE, 2011). The SE-V process involves decomposition and integration of system elements through a sequence of tasks that produce both a system design and its testing specifications, followed by successive levels of build, integration, and test activities. This paper presents a method to improve SE-V implementation by mapping multilevel data into design structure matrix (DSM) models. DSM is a representation methodology for identifying interactions either between components or tasks associated with a complex engineering project (Eppinger & Browning, 2012). Multilevel refers to SE-V data on complex interactions that are germane either at multiple levels of analysis, e.g. component versus subsystem conducted either within a single phase or across multiple time phases, e.g. early or late in the SE-V process. This method extends conventional DSM representation schema by incorporating multilevel test coverage data as vectors into the off diagonal cells. These vectors provide a richer description of potential interactions between product architecture and SE-V integration test tasks than conventional domain mapping matrices (DMMs). We illustrate this method with data from a complex engineering project in the offshore oil industry. Data analysis identifies potential for unanticipated outcomes based on incomplete coverage of SE-V interactions during integration tests. Additionally, assessment of multilevel features using maximum and minimum function queries isolates all the interfaces that are associated with either early or late revelations of integration risks based on the planned suite of SE-V integration tests

Discovery of long-period variable stars in the very-metal-poor globular cluster M15

We present a search for long-period variable (LPV) stars among giant branch stars in M15 which, at [Fe/H] ~ -2.3, is one of the most metal-poor Galactic globular clusters. We use multi-colour optical photometry from the 0.6-m Keele Thornton and 2-m Liverpool Telescopes. Variability of delta-V ~ 0.15 mag is detected in K757 and K825 over unusually-long timescales of nearly a year, making them the most metal-poor LPVs found in a Galactic globular cluster. K825 is placed on the long secondary period sequence, identified for metal-rich LPVs, though no primary period is detectable. We discuss this variability in the context of dust production and stellar evolution at low metallicity, using additional spectra from the 6.5-m Magellan (Las Campanas) telescope. A lack of dust production, despite the presence of gaseous mass loss raises questions about the production of dust and the intra-cluster medium of this cluster.Comment: 13 pages, 9 figures, accepted by MNRA

Performance Practice Bibliography 1990

A bibliography concerning works published in the field of historical performance practice in 1990

An image retrieval system based on the feature of color differences among the edges of objects

This paper focuses on color differences among the edges of objects in an image. The variations of colors among the objects in the image can depict the directions and simple geometric shapes of most objects in the image regardless of the influence from the shift variant of objects and scale variant in the image. Based on the feature of color differences among the edges of objects, this paper constructs an image retrieval system. Experimental results show that this system can effectively and quickly deliver the desired database images to the usersFacultad de Informátic

LATERAL VIBRATION ANALYSIS OF DRILLSTRING USING FINITE ELEMENT METHOD

This project investigates lateral vibration of a drillstring under the action of weight on bit and drillstring rotation. The dominant cause of drillstring and bottom hole assembly’s failures, shocks and severe damages to borehole wall is recognized to be the lateral vibration. Thus, lateral vibration is chosen to be the only factor of interest and focused in this project. Lateral vibration manifests itself from the increased speed of rotary drilling. This study presents a finite element model using ANSYS software to investigate the lateral vibration of drillstring in a vertical well. The analysis proceeds in two stages. Firstly, modal analysis is performed to determine the natural frequencies of the drillstring and the second stage is to carry out harmonic analysis to obtain the frequency response at a varying length of drill pipe. Simulation is first carried out by simulating benchmark problem before proceeding to deal with the actual case studies by carrying out parametric study (drillstring length, weight on bit, rotational speed). The results show that increase in weight on bit increases the natural frequencies and hence changing the location of maximum amplitude in the harmonic analysis

Hepatic cytochromes P450: structural degrons and barcodes, posttranslational modifications and cellular adapters in the ERAD-endgame.

The endoplasmic reticulum (ER)-anchored hepatic cytochromes P450 (P450s) are enzymes that metabolize endo- and xenobiotics i.e. drugs, carcinogens, toxins, natural and chemical products. These agents modulate liver P450 content through increased synthesis or reduction via inactivation and/or proteolytic degradation, resulting in clinically significant drug-drug interactions. P450 proteolytic degradation occurs via ER-associated degradation (ERAD) involving either of two distinct routes: Ubiquitin (Ub)-dependent 26S proteasomal degradation (ERAD/UPD) or autophagic lysosomal degradation (ERAD/ALD). CYP3A4, the major human liver/intestinal P450, and the fast-turnover CYP2E1 species are degraded via ERAD/UPD entailing multisite protein phosphorylation and subsequent ubiquitination by gp78 and CHIP E3 Ub-ligases. We are gaining insight into the nature of the structural determinants involved in CYP3A4 and CYP2E1 molecular recognition in ERAD/UPD [i.e. K48-linked polyUb chains and linear and/or "conformational" phosphodegrons consisting either of consecutive sequences on surface loops and/or disordered regions, or structurally-assembled surface clusters of negatively charged acidic (Asp/Glu) and phosphorylated (Ser/Thr) residues, within or vicinal to which, Lys-residues are targeted for ubiquitination]. Structural inspection of select human liver P450s reveals that such linear or conformational phosphodegrons may indeed be a common P450-ERAD/UPD feature. By contrast, although many P450s such as the slow-turnover CYP2E1 species and rat liver CYP2B1 and CYP2C11 are degraded via ERAD/ALD, little is known about the mechanism of their ALD-targeting. On the basis of our current knowledge of ALD-substrate targeting, we propose a tripartite conjunction of K63-linked Ub-chains, P450 structural "LIR" motifs and selective cellular "cargo receptors" as plausible P450-ALD determinants

The condensation phase transition in the regular kk-SAT model

Much of the recent work on random constraint satisfaction problems has been inspired by ingenious but non-rigorous approaches from physics. The physics predictions typically come in the form of distributional fixed point problems that are intended to mimic Belief Propagation, a message passing algorithm, applied to the random CSP. In this paper we propose a novel method for harnessing Belief Propagation directly to obtain a rigorous proof of such a prediction, namely the existence and location of a condensation phase transition in the random regular $k$-SAT model.Comment: Revised version based on arXiv:1504.03975, version