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101.
R. C. McPhedran D. R. McKenzie G. W. Milton 《Applied Physics A: Materials Science & Processing》1982,29(1):19-27
We describe clearly Milton's bounds on the scalar transport properties of composite materials in the case when no geometrical information is known about the composite, but when a set of measured values of a transport property is available. We consider how the measured values may be used when they are subject to known errors. In this case, a statistical analysis is employed. We illustrate the various conclusions which may result from this analysis by considering six cases involving both two-and three-dimensional composites. In four of the six cases, estimates of the volume fraction of the composite in agreement with the known value are obtained. In the fifth case, the analysis pointed out a possible error in the experimental data, while in the sixth it revealed a critical dependence of transport properties on composite geometry due to filamentary linking between particles. 相似文献
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The Forest Service investigated the concept of providing support to equipment working on steep slopes through use of a self-contained tether cable system. A vehicle's downhill component of weight is reduced to near zero by the cable's tension. The vehicle can then operate on steep slopes causing only slightly more damage to terrain than when working on flat areas. Mathematical equations for the ideal tension of the cable and for both the resulting side forces and equivalent slope when operating off the fall line were developed.The methods of sensing slope, vehicle design, the winch drive system, and the controls necessary to perform with a self-contained tether cable system are all presented. Also discussed are the acceptable tolerance of the cable tension and the effect of cable tension tolerance on equivalent slope. 相似文献
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McLeary JB McKenzie JM Tonge MP Sanderson RD Klumperman B 《Chemical communications (Cambridge, England)》2004,(17):1950-1951
Inhibition in Reversible Addition-Fragmentation chain Transfer (RAFT)-mediated polymerisations is currently a controversial issue; here we provide evidence that the slow "propagation" of the initiating and leaving group radicals during the early part (the period of consumption of the initial RAFT agent) of methyl acrylate RAFT-mediated polymerisation has characteristics similar to inhibition. 相似文献
107.
Burkhart DJ McKenzie AR Nelson JK Myers KI Zhao X Magnusson KR Natale NR 《Organic letters》2004,6(8):1285-1288
Utilizing our lateral metalation coupled with Jacobsen's catalytic asymmetric amino nitrile synthesis, we have demonstrated the ability to synthesize isoxazole-containing amino acid glutamate analogues in high yield and high enantiomeric excesses. Chiral centers alpha or beta at the C-5 position do not detract from diastereoselectivity of the Jacobsen-Strecker reaction. [reaction: see text] 相似文献
108.
Wilson HF Warschkow O Marks NA Schofield SR Curson NJ Smith PV Radny MW McKenzie DR Simmons MY 《Physical review letters》2004,93(22):226102
Density functional calculations are performed to identify features observed in STM experiments after phosphine (PH3) dosing of the Si(001) surface. On the basis of a comprehensive survey of possible structures, energetics, and simulated STM images, three prominent STM features are assigned to structures containing surface bound PH2, PH, and P, respectively. Collectively, the assigned features outline for the first time a detailed mechanism of PH3 dissociation and P incorporation on Si(001). 相似文献
109.
Density functional theory is used to probe the reaction of O(2) with the unsaturated transition-metal fragments [M(bipy)(2)](2+), M = Cr, Fe. In both cases, calculations indicate that the O(2) molecule is initially trapped as an eta(2)-bound superoxide ion, where the unpaired electron in the out-of-plane pi orbital of O(2) is weakly coupled to those on the trivalent metal ion. In the chromium case, a cis-dioxo Cr(VI) complex is found to be significantly more stable than the superoxo species. The two minima are, however, separated by a large barrier, along with a change in spin state. For the iron analogue, the relative energies of the two minima are reversed, the superoxo complex being the global minimum. The energetics of the O(2) activation processes are consistent with previously reported mass spectrometric experiments, where an adduct, [M(bipy)(2)(O(2))](2+), was detected only for chromium. 相似文献
110.