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61.
Alloying zinc coatings with elements such as magnesium and titanium increases the corrosion resistance in industrial tests. Based on the fundamental mechanism of cathodic delamination, a simple concept how alloying zinc with specific elements might improve its resistance to cathodic delamination is presented in this paper. As an example, results concerning the delamination of a simple polymer from the zinc‐magnesium intermetallic MgZn2 are presented. From electrode potential measurements obtained with the Scanning Kelvin Probe it can be concluded that cathodic delamination from this alloy is completely inhibited. This behaviour is attributed to the electronic properties of the magnesium‐rich oxidic passive layer, that inhibits the oxygen reduction reaction at the metal oxide/polymer interface. 相似文献
62.
Michael H. Brill 《Color research and application》2002,27(6):421-424
A simple algorithm (amenable to spreadsheets) is described for plotting a luminance contour map of the color gamut of an additive‐primary display given the chromaticities of its primaries and screen white. Each contour of the plot represents (in either r,g or x,y coordinates) the polygon of intersection of the RGB cube with a plane of constant Y. Each vertex on a contour is an intersection of 1 of the 12 edges of the RGB cube with the constant‐Y plane. Feasibility of an edge as a vertex of the polygon is tested through comparison of the computed r,g coordinates with functions of the luminosity coefficients of the primaries. By ordering the RGB‐cube edges in a particular way prior to scanning them for feasibility, one is guaranteed to retrieve the vertices of any constant‐Y polygon in convex order. This fact facilitates plotting of the polygons. 相似文献
63.
Michael Bowling 《Artificial Intelligence》2002,136(2):215-250
Learning to act in a multiagent environment is a difficult problem since the normal definition of an optimal policy no longer applies. The optimal policy at any moment depends on the policies of the other agents. This creates a situation of learning a moving target. Previous learning algorithms have one of two shortcomings depending on their approach. They either converge to a policy that may not be optimal against the specific opponents' policies, or they may not converge at all. In this article we examine this learning problem in the framework of stochastic games. We look at a number of previous learning algorithms showing how they fail at one of the above criteria. We then contribute a new reinforcement learning technique using a variable learning rate to overcome these shortcomings. Specifically, we introduce the WoLF principle, “Win or Learn Fast”, for varying the learning rate. We examine this technique theoretically, proving convergence in self-play on a restricted class of iterated matrix games. We also present empirical results on a variety of more general stochastic games, in situations of self-play and otherwise, demonstrating the wide applicability of this method. 相似文献
64.
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67.
Impossible and ambiguous shading patterns 总被引:2,自引:1,他引:1
Michael J. Brooks Wojciech Chojnacki Ryszard Kozera 《International Journal of Computer Vision》1992,7(2):119-126
A smooth object depicted in a monochrome image will often exhibit brightness variation, or shading. A problem much studied in computer vision has been that of how object shape may be recovered from image shading. When the imaging conditions are such that an overhead point-source illuminates a smooth Lambertian surface, the problem may be formulated as that of finding a solution to an eikonal equation. This article will focus on the existence and uniqueness of such solutions, reporting recent results obtained. With regard to existence, shading patterns are exhibited for which there is no corresponding object shape. Specifically, a necessary and sufficient condition is presented for a circularly symmetric eikonal equation to admit exclusively unbounded solutions; additionally, a sufficient condition is given for an eikonal equation to have no solution whatsoever. In connection with uniqueness, we consider eikonal equations, defined over a disc, such that the Euclidean norm of the gradient of any solution is circularly symmetric, vanishes exactly at the disc center, and diverges to infinity as the circumference of the disc is approached. Contrary to earlier influential work, a class of such eikonal equations is shown to possess simultaneously circularly symmetric and noncircularly symmetric bounded smooth solutions. 相似文献
68.
69.
K''Andrea C. Bickerstaff Michael J. Schulte Earl E. Swartzlander 《The Journal of VLSI Signal Processing》1995,9(3):181-191
As developed by Wallace and Dadda, a method for high-speed, parallel multiplication is to generate a matrix of partial products
and then reduce the partial products to two numbers whose sum is equal to the final product. The resulting two numbers are
then summed using a fast carry-propagate adder. This paper presents Reduced Area multipliers, which employ a modified reduction
scheme that results in fewer components and less interconnect overhead than either Wallace or Dadda multipliers. This reduction
scheme is especially useful for pipelined multipliers, because it minimizes the number of latches required in the reduction
of the partial products. The reduction scheme can be applied to either unsigned (sign-magnitude) or two's complement numbers.
Equations are given for determining the number of components and a method is presented for estimating the interconnect overhead
for Wallace, Dadda, and Reduced Area multipliers. Area estimates indicate that for non-pipelined multipliers, the reduction
in area achieved with Reduced Area multipliers ranges from 3.7 to 6.6 percent relative to Dadda multipliers, and from 3.8
to 8.4 percent relative to Wallace multipliers. For fully pipelined multipliers, the reduction in area ranges from 15.1 to
33.6 percent relative to Dadda multipliers, and from 2.9 to 9.0 percent relative to Wallace multipliers. 相似文献
70.
Heat Transport to the Wall of Packed Tubes. Radial conduction of heat in packed tubes has a crucial influence on yield and selectivity of many heterogeneously catalyzed reactions. In spite of many years of intensive research in the field, there are still tremendous discrepancies between correlations of different origin. Even the standard model using two constant heat transport parameters, which was introduced in the fifties and has since become most widely accepted, has been controversially discussed and called into question. The unsatisfactory state of the art has been an incentive for several groups of researchers to take up this old topic once again. Three parallel experimental investigations on heat transport with air flowing in packed tubes of similar dimensions, electrically heated, steam-heated, or water-cooled, were completed in 1991. Comparative evaluation of the results of these three investigations, together with other data from the relevant literature, now provides the first clear answers to some of the questions so controversially discussed in the past. 相似文献