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91.
The gamma-2 phase (Sn8Hg) and a dental amalgam in phosphate buffer have been studied by means of potentiostatic and galvanostatic techniques, along with a rotating ring-disc electrode (RRDE). The analysis of results has shown that phosphate ions play an important role in the corrosion of amalgam. The anodic reaction leads to the formation of soluble species and a passivating film, which is probably composed of tin hydroxide and tin phosphate. 相似文献
92.
Retardation of the gasification reaction of carbon with oxygen by SO2 was observed. Rates of oxidation were determined by thermal gravimetric analysis (TGA) of a nuclear graphite in the temperature range of 550–700°C, and of a coconut charcoal in the temperature range of 400–505°C. The oxidant gases were dry air containing 0–6% SO2. Reduction of the rate by SO2 varied with burn-off. Differential thermal analysis (DTA) was also applied to detect the retardation effect of SO2. The technique of infrared internal reflection spectroscopy (IRS) was used to examine the surface species of reacted charcoal samples. Absorption bands were assigned to surface carbonyls, lactones, and a chemisorbed SO2 in the form of sulfate. Chemisorption of SO2 was attributed to cause the retardation of the oxidation reaction. 相似文献
93.
P. Paufler S. K. Filatov I. P. Shakhverdova R. S. Bubnova M. Reibold B. Müller A. A. Levin D. C. Meyer 《Glass Physics and Chemistry》2007,33(3):187-198
The nanohardness (H) and microhardness (H
M) of sodium borosilicate glasses with and without nanopores were studied. From nanoindentation measurements, along with the
hardness H, the Young’s modulus E was derived. While both H and H
M varied between ∼10 GPa and ∼7 GPa for the bulk glass, the values for nanoporous specimens were one order of magnitude lower
at about 0.5 GPa. The Young’s moduli were found to be ∼82 GPa and ∼5 GPa for bulk and porous glasses, respectively. Cracks
and pileups were observed, respectively, arising from microindents and nanoindents in the bulk glass, whereas none of them
could be detected in the nanoporous material. The molecular structures of both glasses studied by X-ray diffraction are similar.
The text was submitted by the authors in English. 相似文献
94.
Janine Glänzel Arnd Meyer Roman Unger Michael Bräunig Volker Wittstock Steffen Ihlenfeldt 《The International Journal of Advanced Manufacturing Technology》2017,88(5-8):1279-1288
A new interdisciplinary approach is discribed to identifying unknown parameters using an extended version of the known interval bisection method. This developed method is based on the use of finite elements for calibrating the simulation calculation. The resulting thermo-elastic deformations which occur in drilling processes with impaired cooling lubrication are to be used as correction values for tool positioning in the NC control. Based on the strong impact on workpiece temperature of machining, a simulation approach is presented for calculating the temperature fields and their thermo-elastic consequences. In addition, methods are presented to correct these effects. This paper particularly deals with the temperature fields of drilling operations. Special attention is paid to the technique employed for iterative numerical determination of the unknown heat flux η w and heat transfer coefficient \(\bar {\gamma }\) values. Finally, the data obtained from experiments are compared with those achieved by numerical simulation in order to verify the efficiency of simulation and determination of parameters. 相似文献
95.
On the mechanical performance of closed cell Al alloy foams 总被引:8,自引:0,他引:8
Y. Sugimura J. Meyer M.Y. He H. Bart-Smith J. Grenstedt A.G. Evans 《Acta Materialia》1997,45(12):5245-5259
The mechanical properties of three different commercially available closed cell Al alloys all made by foam casting are examined. The objective is to assess the roles of cell morphology and of imperfections in governing the basic properties: stiffness, yield strength and fracture resistance. This assessment provides goals for manufacturing strategies that enable attainment of good mechanical performance with affordable process technologies. A prevalent role of curves and wiggles in the cell walls on stiffness and strength (anticipated by models) is affirmed by the present measurements. Systematically larger stiffnesses and yield strengths found in tension than in compression are consistent with a prominent role exerted by such imperfections. Moreover, foam casting is apparently capable of cell morphologies that impart properties approaching the best achievable values for an isotropic closed cell solid, devoid of imperfections. There are associated implications for performance and affordability. Fracture measurements indicate crack growth occurring along the cell walls by a mechanism analogous to the plastic tearing of thin sheets. The crack growth resistances are in the range of 1 kJm−2. This mechanism infers a toughness that scales with the cell wall thickness and its yield strength. 相似文献
96.
Michael Wrle Hans-Joachim Muhr Holger Meyer zu Altenschildesche Reinhard Nesper 《Journal of Alloys and Compounds》1997,260(1-2):80-87
Ca15(CBN)6(C2)2O contains CBN4− anions as well as C2− units and isolated O2− anions. The compound is obtained by heating a stoichiometric mixture of CaO, C and BN with an excess of Ca in sealed niobium ampoules to 1270 K. It crystallizes in the space group Ia
d with a = 1656.84(9) pm. Preparation, crystal structure, NMR and IR-spectroscopic properties are discussed. 相似文献
97.
In this paper, we introduce a novel technique for pre‐filtering multi‐layer shadow maps. The occluders in the scene are stored as variable‐length lists of fragments for each texel. We show how this representation can be filtered by progressively merging these lists. In contrast to previous pre‐filtering techniques, our method better captures the distribution of depth values, resulting in a much higher shadow quality for overlapping occluders and occluders with different depths. The pre‐filtered maps are generated and evaluated directly on the GPU, and provide efficient queries for shadow tests with arbitrary filter sizes. Accurate soft shadows are rendered in real‐time even for complex scenes and difficult setups. Our results demonstrate that our pre‐filtered maps are general and particularly scalable. 相似文献
98.
Joachim Meyer Yuval Bitan David Shinar 《International journal of human-computer interaction》2013,29(3):273-290
Two experiments assessed the effect of displaying a boundary on duration estimates and preference ratings for dynamic displays that were shown while users waited for the system's response. Displays were either symbolic (changing numbers) or graphic (increasing rectangles) and could contain a boundary that indicated when the interval was expected to be over. Duration estimates were similar for symbolic and graphic displays and for displays with and without a boundary. However, when the displays were encountered successively, participants assessed the graphic displays as having shorter durations than the symbolic displays. Faster rates of change in both types of displays led to increased duration estimates. Although displaying a boundary did not affect duration estimates, participants preferred displays in which a boundary was shown and preferred the graphic displays over the symbolic displays. Hence, bounded graphic displays are recommended as “wait” displays for computerized applications. 相似文献
99.
An important problem in agent verification is a lack of proper understanding of the relation between agent programs on the
one hand and agent logics on the other. Understanding this relation would help to establish that an agent programming language
is both conceptually well-founded and well-behaved, as well as yield a way to reason about agent programs by means of agent
logics. As a step toward bridging this gap, we study several issues that need to be resolved in order to establish a precise
mathematical relation between a modal agent logic and an agent programming language specified by means of an operational semantics. In this paper, we present an agent programming theory that provides both an agent programming language as well as a corresponding agent verification logic to verify agent programs.
The theory is developed in stages to show, first, how a modal semantics can be grounded in a state-based semantics, and, second, how denotational semantics can be used to define the mathematical relation connecting the logic and agent programming language. Additionally, it is
shown how to integrate declarative goals and add precompiled plans to the programming theory. In particular, we discuss the
use of the concept of higher-order goals in our theory. Other issues such as a complete axiomatization and the complexity
of decision procedures for the verification logic are not the focus of this paper and remain for future investigation.
Part of this research was carried out while the first author was affiliated with the Nijmegen Institute for Cognition and
Information, Radboud University Nijmegen. 相似文献
100.
C. Amatore A. Jutand G. Meyer P. Bourhis F. Machetto J. -M. Mallet P. Sinaÿ C. Tabeur Y. -M. Zhang 《Journal of Applied Electrochemistry》1994,24(8):725-729
Summary
O-glycosides were synthesized by electrochemical oxidation of phenylS-glycosides in the presence of primary alcohols in acetonitrile. Similarly, a -linked disaccharide was obtained selectively by oxidation of phenylS-glycoside in the presence of a sugar alcohol. Electrosyntheses were performed under controlled potential or at constant current, in an undivided cell, on a large scale. 1 to 60 g of phenylS-glycosides in 0.5 to 1 dm3 of acetonitrile were converted with chemical yields in the range of 65–75%. 相似文献