Plasma Sprayed Dense MgO-Y2O3 Nanocomposite Coatings Using Sol-Gel Combustion Synthesized Powder

MgO-Y₂O₃ nanostructured composite powder (volume ratio of 50:50) was synthesized by a sol-gel combustion process which generated crystal sizes in the 10-20 nm range. The MgO-Y₂O₃ nanopowder was plasma sprayed using a conventional, DC arc plasma spray system. X-ray diffraction analysis shows that the as-sprayed MgO-Y₂O₃ coating is composed of cubic MgO and Y₂O₃ phases and has ~95% density. Microstructure characterization by SEM reveals that the as-sprayed coating has fine grain sizes of 100-300 nm as a result of rapid solidification. The hardness of the coating, 7.5 ± 0.6 GPa, is higher than that of coarse-grained, dense MgO, and Y₂O₃ ceramics. This approach demonstrates the potential of plasma spray processes for making thick, dense MgO-Y₂O₃ nanocomposite performs for applications as durable, infrared windows.     

Binocular fixation disparity in single word displays.

It has been claimed that the recognition of words displayed in isolation is affected by the precise location at which they are fixated. However, this putative role for fixation location has yet to be reconciled with the finding from reading research that binocular fixations are often misaligned and, therefore, more than 1 location in a word is often fixated simultaneously. The accuracy and alignment of binocular fixations during single word processing have not been assessed previously. To investigate this issue, words were presented for lexical decision at locations around a central fixation point. Eye-tracking data revealed that participants often fixated inaccurately and that fixations were frequently misaligned, but that this did not affect word recognition. The findings show that binocular fixation disparity is pervasive even in single word displays and a potential source of confound for research into effects of fixation location on word recognition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Social influences related to college students’ use of Macintosh computers on an all-PC campus

In the present qualitative research study, 35 Mac users were interviewed in a university campus that exclusively supports PC machines. We particularly explored the Mac-users’ social influences, saving technological and other influences for future reports. Results showed Mac users to possess significant connections with other Mac users on the university campus. The Mac users in our study indicated that positive, past exposure, including Apple’s advertising of Macs, had sharp influences on their decisions to become and remain Mac users.     

Calculating fragment impact velocity from penetration data

Depth of penetration experiments were conducted with fragment simulating projectiles launched into Celotex^® in order to develop an equation for the strike velocity as a function of the FSP mass and the depth of penetration into Celotex^® recovery media. A powder gun launched FSPs, designed in accordance with STANAG-2920 [NATO STANAG-2920 Ballistic Test Method for Personal Armour Materials and Combat Clothing, 2nd ed., 1999.] weighing between 0.13 g and 53.78 g at striking velocities between 198 m/s and 1524 m/s. A multiple linear regression analysis was used to determine an empirical relationship for the strike velocity to the impact parameters of depth of penetration, fragment mass, and mean presented area. Sabot launched natural fragments weighing between 2.8 g and 15.8 g at striking velocities between 532 m/s and 1084 m/s were used to validate the equation.     

Spiral-CT-based assessment of tracheal stenoses using 3-D-skeletonization

PURPOSE: Demonstration of a technique for three-dimensional (3-D) assessment of tracheal-stenoses, regarding site, length and degree, based on spiral computed tomography (S-CT). PATIENTS AND METHODS: S-CT scanning and automated segmentation of the laryngo-tracheal tract (LTT) was followed by the extraction of the LTT medial axis using a skeletonization algorithm. Orthogonal to the medial axis the LTT 3-D cross-sectional profile was computed and presented as line charts, where degree and length was obtained. Values for both parameters were compared between 36 patients and 18 normal controls separately. Accuracy and precision was derived from 17 phantom studies. RESULTS: Average degree and length of tracheal stenoses was found to be 60.5% and 4.32 cm in patients compared with minor caliber changes of 8.8% and 2.31 cm in normal controls (p < 0.0001). For the phantoms an excellent correlation between the true and computed 3-D cross-sectional profile was found (p < 0.005) and an accuracy for length and degree measurements of 2.14 mm and 2.53% respectively could be determined. The corresponding figures for the precision were found to be 0.92 mm and 2.56%. CONCLUSION: LTT 3-D cross-sectional profiles permit objective, accurate and precise assessment of LTT caliber changes. Minor LTT caliber changes can be observed even in normals and, in case of an otherwise normal S-CT study, can be regarded as artifacts.     

High temperature superconductivity applied to electric motors

The application of high temperature superconductors to electric motors is discussed. Both the advantages and limitations of using superconductors in motors are reviewed. A synchronous motor with a high-temperature superconductor field winding for pump and fan drive applications is described and some of its unique features are identified. A 10000-hp superconducting motor design and its advantages in terms of improved efficiency and reduced size are described. The performance requirements for the superconducting wire necessary for motor applications are considered, and the progress being made toward realizing these requirements is assessed