Improved techniques for thermomechanical testing in support of deformation modeling

The feasibility of generating precise thermomechanical deformation data to support constitutive model development was investigated. Here, the requirement is for experimental data that is free from anomalies caused by less than ideal equipment and procedures. A series of exploratory tests conducted on Hastelloy X showed that generally accepted techniques for strain controlled tests were lacking in at least three areas. Specifically, problems were encountered with specimen stability, thermal strain compensation, and temperature/mechanical strain phasing. The source of these difficulties was identified and improved thermomechanical testing techniques to correct them were developed. These goals were achieved by developing improved procedures for measuring and controlling thermal gradients and by designing a specimen specifically for thermomechanical testing. In addition, innovative control strategies were developed to correctly proportion and phase the thermal and mechanical components of strain. Subsequently, the improved techniques were used to generate deformation data for Hastelloy X over the temperature range, 200 to 1000 C

Homodyne detection as a near-optimum receiver for phase-shift keyed binary communication in the presence of phase diffusion

We address binary optical communication channels based on phase-shift keyed coherent signals in the presence of phase diffusion. We prove theoretically and demonstrate experimentally that a discrimination strategy based on homodyne detection is robust against this kind of noise for any value of the channel energy. Moreover, we find that homodyne receiver beats the performance of Kennedy receiver as the signal energy increases, and achieves the Helstrom bound in the limit of large noise

Thermomechanical deformation behavior of a dynamic strain aging alloy, Hastelloy X

An experimental study was performed to identify the effects of dynamic strain aging (solute drag) and metallurgical instabilities under thermomechanical loading conditions. The study involved a series of closely controlled thermomechanical deformation tests on the solid-solution-strenghened nickel-base superalloy, Hastelloy X. This alloy exhibits a strong isothermal strain aging peak at approximately 600 C, promoted by the effects of solute drag and precipitation hardening. Macroscopic thermomechanical hardening trends are correlated with microstructural characteristics through the use of transmission electron microscopy. These observations are compared and contrasted with isothermal conditions. Thermomechanical behavior unique to the isothermal database is identified and discussed. The microstructural characteristics were shown to be dominated by effects associated with the highest temperature of the thermomechanical cycle. Results indicate that the deformation behavior of Hastelloy X is thermomechanically path dependent. In addition, guidance is given pertaining to deformation modeling in the context of macroscopic unified theory. An internal state variable is formulated to qualitatively reflect the isotropic hardening trends identified in the TMD experiments

Integrated Light 2MASS IR Photometry of Galactic Globular Clusters

We have mosaiced 2MASS images to derive surface brightness profiles in JHK for 104 Galactic globular clusters. We fit these with King profiles, and show that the core radii are identical to within the errors for each of these IR colors, and are identical to the core radii at V in essentially all cases. We derive integrated light colors V-J, V-H, V-K_s, J-H and J-K_s for these globular clusters. Each color shows a reasonably tight relation between the dereddened colors and metallicity. Fits to these are given for each color. The IR--IR colors have very small errors due largely to the all-sky photometric calibration of the 2MASS survey, while the V-IR colors have substantially larger uncertainties. We find fairly good agreement with measurements of integrated light colors for a smaller sample of Galactic globular clusters by Aaronson, Malkan & Kleinmann from 1977. Our results provide a calibration for the integrated light of distant single burst old stellar populations from very low to Solar metallicities. A comparison of our dereddened measured colors with predictions from several models of the integrated light of single burst old populations shows good agreement in the low metallicity domain for V-K_s colors, but an offset at a fixed [Fe/H] of ~0.1 mag in J-K_s, which we ascribe to photometric system transformation issues. Some of the models fail to reproduce the behavior of the integrated light colors of the Galactic globular clusters near Solar metallicity.Comment: Accepted for publication in the A

The psychosocial impact of assistive device scale: Italian validation in a cohort of nonambulant people with neuromotor disorders

The importance of adaptive seating system on body structure and function is widely accepted, but its impact on psychosocial aspects needs more consideration by health professionals. This article describes the Italian validation of the Psychosocial Impact of Assistive Device Scale (IT-PIADS) for non-ambulant people with neuromotor disorders. Once agreement has been given by the original authors, the scale was translated and adapted to the Italian culture. The IT-PIADS was administered to different wheelchairs users with heterogeneous diagnosis. The internal consistency and test-retest reliability were examined. Its concurrent validity was evaluated with the Italian version of the WheelCon-M-SF. The IT-PIADS was administered to 87 subjects. Cronbach's α was 0.92 (p < 0.05), and the testretest reliability (ICC) for competence, adaptability and self-esteem subscales were 0.96, 0.90, 0.93 respectively. The Pearson correlation coefficient of the IT-PIADS with the WheelCon-M-I-SF scores showed significant data for competence and adaptability subscales. Psychosocial perception on assistive devices can be reliably measure. The IT-PIADS showed good psychometric properties and it is possible to confirm its validity for clinical and research purposes. Nevertheless, before using this measure with greater confidence, further psychometric properties tests of the IT-PIADS are recommended

A computer program for hydrostatic bearings including the effects of non-uniform film thickness and relative velocity for various methods of lubricant supply final technical report

Computer program for hydrostatic bearing - effects of nonuniform film thickness and lubricant suppl

Artifacts at 4.5 and 8.0 um in Short Wavelength Spectra from the Infrared Space Observatory

Spectra from the Short Wavelength Spectrometer (SWS) on ISO exhibit artifacts at 4.5 and 8 um. These artifacts appear in spectra from a recent data release, OLP 10.0, as spurious broad emission features in the spectra of stars earlier than ~F0, such as alpha CMa. Comparison of absolutely calibrated spectra of standard stars to corresponding spectra from the SWS reveals that these artifacts result from an underestimation of the strength of the CO and SiO molecular bands in the spectra of sources used as calibrators by the SWS. Although OLP 10.0 was intended to be the final data release, these findings have led to an additional release addressing this issue, OLP 10.1, which corrects the artifacts.Comment: 14 pages, AASTex, including 5 figures. Accepted by ApJ Letter

HUMAN INTERVENTIONS AND ALTERATIONS OF THE GEOMORPHOLOGICAL CHARACTERISTICS IN PARTS OF THE COASTAL AREA IN THE IONIAN COAST (IPIROS - GREECE)

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