9,098 research outputs found
A constitutive model with damage for high temperature superalloys
A unified constitutive model is searched for that is applicable for high temperature superalloys used in modern gas turbines. Two unified inelastic state variable constitutive models were evaluated for use with the damage parameter proposed by Kachanov. The first is a model (Bodner, Partom) in which hardening is modeled through the use of a single state variable that is similar to drag stress. The other (Ramaswamy) employs both a drag stress and back stress. The extension was successful for predicting the tensile, creep, fatigue, torsional and nonproportional response of Rene' 80 at several temperatures. In both formulations, a cumulative damage parameter is introduced to model the changes in material properties due to the formation of microcracks and microvoids that ultimately produce a macroscopic crack. A back stress/drag stress/damage model was evaluated for Rene' 95 at 1200 F and is shown to predict the tensile, creep, and cyclic loading responses reasonably well
Reggae to Rachmaninoff: How and Why People Participate in Arts and Culture
Provides the results of a telephone survey conducted to help inform those whose aim is to broaden and diversify cultural participation, and promote the role of arts and culture in strengthening American communities
On-line analysis capabilities developed to support the AFW wind-tunnel tests
A variety of on-line analysis tools were developed to support two active flexible wing (AFW) wind-tunnel tests. These tools were developed to verify control law execution, to satisfy analysis requirements of the control law designers, to provide measures of system stability in a real-time environment, and to provide project managers with a quantitative measure of controller performance. Descriptions and purposes of the developed capabilities are presented along with examples. Procedures for saving and transferring data for near real-time analysis, and descriptions of the corresponding data interface programs are also presented. The on-line analysis tools worked well before, during, and after the wind tunnel test and proved to be a vital and important part of the entire test effort
A Kame Field of Iowan Age in the Vicinity of Grand Mound and De Witt, Clinton County, Iowa
Numerous low mounds of irregular shape in the v1cm1ty of Grand Mound and De Witt, Iowa, are glacial features coming under the category of kames. Twenty-two kames have been identified within an oblong area about two or three miles wide and 12 miles long, lying immediately south of the Chicago, Northwestern railroad and U. S. Highway 30 (see Figure l). The area extends eastward from about two miles east of the town of Calamus, passing south of the town of Grand Mound and continuing two miles southeast of the city of De Witt. Parts of the kame field lie in Olive, Orange and De Witt townships, Clinton county
Multiple-function multi-input/multi-output digital control and on-line analysis
The design and capabilities of two digital controller systems for aeroelastic wind-tunnel models are described. The first allowed control of flutter while performing roll maneuvers with wing load control as well as coordinating the acquisition, storage, and transfer of data for on-line analysis. This system, which employs several digital signal multi-processor (DSP) boards programmed in high-level software languages, is housed in a SUN Workstation environment. A second DCS provides a measure of wind-tunnel safety by functioning as a trip system during testing in the case of high model dynamic response or in case the first DCS fails. The second DCS uses National Instruments LabVIEW Software and Hardware within a Macintosh environment
A Detailed Comparison of Multi-Dimensional Boltzmann Neutrino Transport Methods in Core-Collapse Supernovae
The mechanism driving core-collapse supernovae is sensitive to the interplay
between matter and neutrino radiation. However, neutrino radiation transport is
very difficult to simulate, and several radiation transport methods of varying
levels of approximation are available. We carefully compare for the first time
in multiple spatial dimensions the discrete ordinates (DO) code of Nagakura,
Yamada, and Sumiyoshi and the Monte Carlo (MC) code Sedonu, under the
assumptions of a static fluid background, flat spacetime, elastic scattering,
and full special relativity. We find remarkably good agreement in all spectral,
angular, and fluid interaction quantities, lending confidence to both methods.
The DO method excels in determining the heating and cooling rates in the
optically thick region. The MC method predicts sharper angular features due to
the effectively infinite angular resolution, but struggles to drive down noise
in quantities where subtractive cancellation is prevalent, such as the net gain
in the protoneutron star and off-diagonal components of the Eddington tensor.
We also find that errors in the angular moments of the distribution functions
induced by neglecting velocity dependence are sub-dominant to those from
limited momentum-space resolution. We briefly compare directly computed second
angular moments to those predicted by popular algebraic two-moment closures,
and find that the errors from the approximate closures are comparable to the
difference between the DO and MC methods. Included in this work is an improved
Sedonu code, which now implements a fully special relativistic,
time-independent version of the grid-agnostic Monte Carlo random walk
approximation.Comment: Accepted to ApJS. 24 pages, 19 figures. Key simulation results and
codes are available at https://stellarcollapse.org/MCvsD
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