9,487 research outputs found
Generation of long time creep data of refrac- tory alloys at elevated temperatures seventh quarterly report, 26 dec. 1964 - 26 mar. 1965
Ultrahigh vacuum creep data for tungsten, tungsten-25 per cent rhenium, TZM and TZC MOLYBDENUM alloys and AS-30 niobium allo
Generation of long time creep data of refractory alloys at elevated temperatures fifth quarterly report, 26 jun. - 26 sep. 1964
Creep testing data and machine reliability for high-temperature long-time tests on niobium, tungsten, and rhenium alloy
A Proposed Approach for Prioritizing Maintenance at NASA Centers
The National Aeronautics and Space Administration (NASA) manages a vast array of infrastructure assets across ten National Centers with a worth of at least 30 billion dollars. Eighty percent of this infrastructure is greater than 40 years old and is in degraded condition. Maintenance budgets are typically less than one percent of current replacement value (CRV), much less than the 2-4% recommended by the National Research Council. The maintenance backlog was 2.55 billion dollars in FY10 and growing. NASA s annual budgets have flattened and are at risk of being reduced, so the problem is becoming even more difficult. NASA Centers utilize various means to prioritize and accomplish maintenance within available budgets, though data is suspect and processes are variable. This paper offers a structured means to prioritize maintenance based on mission criticality and facility performance (ability of the facility to deliver on its purpose). Mission alignment is assessed using the current timeframe Mission Dependence Index and a measure of facility alignment with the 2011 NASA Strategic Plan for the long-term perspective. Facility performance is assessed by combining specific findings from a structured facility condition assessment and an assessment of actual functional output. These are then combined in a matrix to identify the facilities most critical to mission and able to deliver services. The purpose of this approach is to provide the best benefits for the available funding. Additionally, this rationale can also be applied to the prioritization of investment (recapitalization) projects so that the ultimate customers of this paper, the senior infrastructure managers at each NASA Center, are better able to strategically manage their capabilities
A Framework to Manage the Complex Organisation of Collaborating: Its Application to Autonomous Systems
In this paper we present an analysis of the complexities of large group
collaboration and its application to develop detailed requirements for
collaboration schema for Autonomous Systems (AS). These requirements flow from
our development of a framework for collaboration that provides a basis for
designing, supporting and managing complex collaborative systems that can be
applied and tested in various real world settings. We present the concepts of
"collaborative flow" and "working as one" as descriptive expressions of what
good collaborative teamwork can be in such scenarios. The paper considers the
application of the framework within different scenarios and discuses the
utility of the framework in modelling and supporting collaboration in complex
organisational structures
Cold Molecule Spectroscopy for Constraining the Evolution of the Fine Structure Constant
We report precise measurements of ground-state, -doublet microwave
transitions in the hydroxyl radical molecule (OH). Utilizing slow, cold
molecules produced by a Stark decelerator we have improved over the precision
of the previous best measurement by twenty-five-fold for the F' = 2 F = 2
transition, yielding (1 667 358 996 4) Hz, and by ten-fold for the F' = 1
F = 1 transition, yielding (1 665 401 803 12) Hz. Comparing these
laboratory frequencies to those from OH megamasers in interstellar space will
allow a sensitivity of 1 ppm for over
years.Comment: This version corrects minor typos in the Zeeman shift discussio
Development of high temperature oxidation resistant coatings for chromium-base alloys Final report
High temperature oxidation resistant coatings for chromium-base alloy
Nuclear Reaction Rates in a Plasma
The problem of determining the effects of the surrounding plasma on nuclear
reaction rates in stars is formulated ab initio, using the techniques of
quantum statistical mechanics. We derive a result that expresses the complete
effects of Coulomb barrier penetration and of the influence of the surrounding
plasma in terms of matrix elements of well defined operators. We find that
possible "dynamical screening" effects that have been discussed in the
literature are absent. The form of our results suggests that an approach that
relies on numerical calculations of the correlation functions in a classical
Coulomb gas, followed by construction of an effective two body potential and a
quantum barrier penetration calculation, will miss physics that is as important
as the physics that it includes.Comment: 66 pages, revtex, Errors Fixed, Explanation Adde
Prospects for the cavity-assisted laser cooling of molecules
Cooling of molecules via free-space dissipative scattering of photons is
thought not to be practicable due to the inherently large number of Raman loss
channels available to molecules and the prohibitive expense of building
multiple repumping laser systems. The use of an optical cavity to enhance
coherent Rayleigh scattering into a decaying cavity mode has been suggested as
a potential method to mitigate Raman loss, thereby enabling the laser cooling
of molecules to ultracold temperatures. We discuss the possibility of
cavity-assisted laser cooling particles without closed transitions, identify
conditions necessary to achieve efficient cooling, and suggest solutions given
experimental constraints. Specifically, it is shown that cooperativities much
greater than unity are required for cooling without loss, and that this could
be achieved via the superradiant scattering associated with intracavity
self-localization of the molecules. Particular emphasis is given to the polar
hydroxyl radical (OH), cold samples of which are readily obtained from Stark
deceleration.Comment: 18 pages, 10 figure
Social informatics of data norms
Big data has been widely promoted across disciplines and sectors for its potential to enhance lives and promote knowledge discovery. However, challenges arise at all stages of the data lifecycle due to the complexity of interactions between data and the contexts within which they are collected and managed, which has implications for interpretations of this data and eventual use of information and the creation of knowledge products from these data. Starting from the perspective of social informatics, this panel will discuss: the reciprocal relationships between data and context; specific challenges in distinct stages of data generation, data repository implementation, data curation, data use, and data reproducibility; and the implications of these challenges and their potential solutions for both social informatics research and society in general
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