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Distribution by Scientific Domains

Engineering	50%

Selected Abstracts

Legibility evaluation using point-of-regard measurement

ELECTRICAL ENGINEERING IN JAPAN, Issue 4 2008
Daisuke Saito
Abstract Web site visibility has become important because of the rapid dissemination of the World Wide Web, and combinations of foreground and background colors are crucial in providing high visibility. In our previous studies, the visibilities of several web-safe color combinations were examined using a psychological method. In those studies, simple stimuli were used because of experimental restriction. In this paper, legibility of sentences on web sites was examined using a psychophysiological method, point-of-regard measurement, to obtain other practical data. Ten people with normal color sensations ranging from ages 21 to 29 were recruited. The number of characters per line in each page was arranged in the same number, and the four representative achromatic web-safe colors, that is, #000000, #666666, #999999, and #CCCCCC, were examined. The reading time per character and the gaze time per line were obtained from point-of-regard measurement, and the normalized with the reading time and the gaze time of the three colors were calculated and compared. It was found that the time of reading and gaze become long at the same ratio when the contrast decreases by point-of-regard measurement. Therefore, it was indicated that the legibility of color combinations could be estimated by point-of-regard measurement. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 162(4): 35,42, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20612 [source]

On morphometric properties of basins, scale effects and hydrological response

HYDROLOGICAL PROCESSES, Issue 1 2003
Roger Moussa
Abstract One of the important problems in hydrology is the quantitative description of river system structure and the identification of relationships between geomorphological properties and hydrological response. Digital elevation models (DEMs) generally are used to delineate the basin's limits and to extract the channel network considering pixels draining an area greater than a threshold area S. In this paper, new catchment shape descriptors, the geometric characteristics of an equivalent ellipse that has the same centre of gravity, the same principal inertia axes, the same area and the same ratio of minimal inertia moment to maximal inertia moment as the basin, are proposed. They are applied in order to compare and classify the structure of seven basins located in southern France. These descriptors were correlated to hydrological properties of the basins' responses such as the lag time and the maximum amplitude of a geomorphological unit hydrograph calculated at the basin outlet by routing an impulse function through the channel network using the diffusive wave model. Then, we analysed the effects of the threshold area S on the topological structure of the channel network and on the evolution of the source catchment's shape. Simple models based on empirical relationships between the threshold S and the morphometric properties were established and new catchment shape indexes, independent of the observation scale S, were defined. This methodology is useful for geomorphologists dealing with the shape of source basins and for hydrologists dealing with the problem of scale effects on basin topology and on relationships between the basin morphometric properties and the hydrological response. Copyright © 2002 John Wiley & Sons, Ltd. [source]

R&D COMPETITION AND ENDOGENOUS SPILLOVERS

THE MANCHESTER SCHOOL, Issue 1 2006
JIM Y. JIN
The paper examines firms' choices between innovation and imitation in duopoly. We show that in the unique equilibrium asymmetric firms choose the same level of expenditure on imitation and the same ratio of innovative cost reduction to output. We evaluate the marginal contribution of innovation and imitation expenditure by small and large firms to consumer surplus and welfare, and discuss the desirability of differentiated R&D subsidies on innovation and imitation in terms of R&D tax rebates. [source]

Thermal Decomposition of Energetic Materials 85: Cryogels of Nanoscale Hydrazinium Diperchlorate in Resorcinol-Formaldehyde

PROPELLANTS, EXPLOSIVES, PYROTECHNICS, Issue 2 2003
Bryce
Abstract The objective of this work was to try to desensitize an energetic material by using sol-gel processing and freeze drying to incorporate the energetic material into the fuel matrix on the nano (or at least submicron) particle size scale. Hydrazinium diperchlorate ([N2H6][ClO4]2 or HP2) and resorcinol-formaldehyde (RF) were chosen as the oxidizer and fuel, respectively. Solid loading up to 88% HP2 was achieved by using the sol gel-to-cryogel method. Various weight percentages of HP2 in RF were characterized by elemental analysis, scanning electron (SEM) and optical microscopy, T-jump/FTIR spectroscopy, DSC, and drop-weight impact. SEM indicated that 20,50,nm diameter HP2 plates aggregated into porous 400,800,nm size clusters. Below 80% HP2 the cryogels are less sensitive to impact than physical mixtures having the same ratios of HP2 and RF. The decomposition temperatures of the cryogels are higher than that of pure HP2, which is consistent with their lower impact sensitivity. The heat of decomposition as measured at a low heating rate increases with increasing percentage of HP2. The cryogels and physical mixtures release similar amounts of energy, but the cryogels exhibit mainly a single exotherm by DSC whereas the physical mixtures showed a two-step energy release. Flash pyrolysis revealed gaseous product ratios suggestive of more energy being released from the cryogels than the physical mixtures. Cryogels also burn faster by visual observation. [source]