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41.
The plastic deformation kinetics of 99.4% MgO (d
o = 5.3 m) was investigated at 1500°–1600°C in uniaxial tension. It was determined that the stress exponent n 1 and the activation energy Q = 204 kJ/mole. Neither the present results on MgO, nor data in the literature on MgO and other oxide ceramics, can be fully explained by the models usually proposed for the plastic deformation of fine-grained oxide ceramics. The present results are however in good agreement with the model for grain boundary diffusion plastic flow recently developed by Kim, Estrin and Bush. 相似文献
42.
Quality-aware images. 总被引:4,自引:0,他引:4
Zhou Wang Guixing Wu Hamid Rahim Sheikh Eero P Simoncelli En-Hui Yang Alan Conrad Bovik 《IEEE transactions on image processing》2006,15(6):1680-1689
We propose the concept of quality-aware image, in which certain extracted features of the original (high-quality) image are embedded into the image data as invisible hidden messages. When a distorted version of such an image is received, users can decode the hidden messages and use them to provide an objective measure of the quality of the distorted image. To demonstrate the idea, we build a practical quality-aware image encoding, decoding and quality analysis system, which employs: 1) a novel reduced-reference image quality assessment algorithm based on a statistical model of natural images and 2) a previously developed quantization watermarking-based data hiding technique in the wavelet transform domain. 相似文献
43.
PURPOSE: Endosonographic image and surgical therapy of a retrorectal bowel duplication are described. METHODS, RESULTS, AND CONCLUSIONS: Compared with standard investigations, the most accurate information about a retrorectal mass in a 35-year-old woman could be obtained by means of endorectal ultrasound. Guided by endorectal ultrasound, the mass was excised using a transanal-transrectal approach, and Kraske's operation could be avoided. Additionally, histopathologic analysis of this rare disease is presented. 相似文献
44.
Marijuana use was assessed in 186 people seeking treatment for cocaine dependence. Comparisons were made between clients who did and did not report using marijuana and between marijuana users who did and did not meet diagnostic criteria for marijuana dependence. The relationship between marijuana use and treatment outcome was also explored. A high rate of current marijuana use (59%) was observed at intake, and the majority of the marijuana users (74%) used marijuana at some point during treatment. Marijuana use at intake was associated with increased psychosocial impairment and substance-use severity. However, no significant adverse relations were observed between marijuana use at intake or during treatment and treatment outcome. Such functional independence may have important implications for addressing marijuana use during treatment for cocaine dependence. These findings should be interpreted with caution pending replication in prospective studies and with other treatment approaches. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
45.
Kai Grjotheim Conrad Krohn Roger Naeumann Knut Tørklep 《Metallurgical and Materials Transactions B》1970,1(11):3133-3141
The convection pattern in the bath electrolyte and the cathode metal of 150 kamp prebaked anode aluminum reduction cells has been studied by means of radioactive tracers. The initial distribution of the tracers—24Na for the bath and198Au for the metal phase-indicates a fast circulating movement with vortices at the ends in both phases. Circulation rates up to 100 cm per sec were observed, and an average value seemed to be 10 cm per sec. The implications of the convection on the mechanism of the secondary reactions, the dissolution of alumina in the bath electrolyte and the distribution of carbon particles in the cell are discussed. 相似文献
46.
S. P. Agrawal G. A. Sargent H. Conrad 《Metallurgical and Materials Transactions B》1974,5(11):2415-2422
Hexagonal dislocation networks which occurred in as-annealed commercial Ti-A 50 rod and following partial extrusion under
hydrostatic pressure at room temperature were studied using transmission electron microscopy. For the as-annealed condition
networks were observed on the prism, basal and {2•1•1x} planes, while for the extrusion networks were only observed on the
basal plane. The various stages in the development of the networks are presented and mechanisms by which they form are proposed.
The self energies of the dislocation hexagons constituting the various networks are calculated using the equations proposed
by de Wit and Ruff. They increase in the order: a) networks on the basal plane in the as-annealed condition, b) networks on
the prism plane in the asannealed condition and c) networks on the basal plane in the partially extruded condition.
This paper is based on Doctoral Thesis presented in October 1973 by S. P. AGRAWAL to the Department of Metallurgical Engineering
and Materials Science at the University of Kentucky. 相似文献
47.
48.
Conrad KJ Wright BD McKnight P McFall M Fontana A Rosenheck R 《Journal of applied measurement》2004,5(1):15-30
This study examined whether Rasch analysis could provide more information than true score theory (TST) in determining the usefulness of reverse-scored items in the Mississippi Scale for Posttraumatic Stress Disorder (M-PTSD). Subjects were 803 individuals in inpatient PTSD units at 10 VA sites. TST indicated that the M-PTSD performed well and could be improved slightly by deleting one item. Factor analysis using raw scores indicated that the reverse-scored items formed the second factor and had poor relationships with normally scored items. However, since item-total correlations supported their usefulness, they were kept. The subsequent Rasch analysis indicated that five of the seven worst fitting items were reverse-scored items. We concluded that using reversed items with disturbed patients can cause confusion that reduces reliability. Deleting them improved validity without loss of reliability. The study supports the use of Rasch analysis over TST in health research since it indicated ways to reduce respondent burden while maintaining reliability and improving validity. 相似文献
49.
James CD Spence AJ Dowell-Mesfin NM Hussain RJ Smith KL Craighead HG Isaacson MS Shain W Turner JN 《IEEE transactions on bio-medical engineering》2004,51(9):1640-1648
Neuronal cell networks have been reconstructed on planar microelectrode arrays (MEAs) from dissociated hippocampal pyramidal neurons. Microcontact printing (microCP) and a photoresist-liftoff method were used to selectively localize poly-L-lysine (PLL) on the surface of MEAs. Haptotaxis led to the organization of the neurons into networks localized adjacent to microelectrodes. Various grids of PLL with 2-25-microm-wide lines spaced by 50-200 microm with 15-25-microm nodes at intersection points were used to guide cell body attachment and neurite outgrowth. Bursting activity with spike amplitude attenuation was observed, and multichannel recordings detected instances of coincident firing activity. Finally, we present here an extracellular recording from a approximately 2 microm bundle of guided neurites. 相似文献
50.