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621.
A bivariable polynomial of total degreen that has minimal uniform norm on a triangular region is given explictly.Communicated by Edward B. Saff. 相似文献
622.
623.
L. Silverman und M. S. Newman 《Fresenius' Journal of Analytical Chemistry》1942,124(5-6):227-228
Ohne Zusammenfassung 相似文献
624.
625.
626.
Brahms N Newman B Johnson C Greytak T Kleppner D Doyle J 《Physical review letters》2008,101(10):103002
We have trapped large numbers of copper (Cu) and silver (Ag) atoms using buffer-gas cooling. Up to 3 x 10{12} Cu atoms and 4 x 10{13} Ag atoms are trapped. Lifetimes are as long as 5 s, limited by collisions with the buffer gas. Ratios of elastic to inelastic collision rates with He are >or=10{6}, suggesting Cu and Ag are favorable for use in ultracold applications. The temperature dependence of the Ag-3He collision rate varies as T;{5.8+/-0.4}. We find that this temperature dependence is inconsistent with the behavior predicted for relaxation arising from the spin-rotation interaction, and conclude that the Ag-3He system displays anomalous collisional behavior in the multiple-partial wave regime. Gold (Au) was ablated into 3He buffer gas, however, atomic Au lifetimes were observed to be too short to permit trapping. 相似文献
627.
Cascading failures in large-scale electric power transmission systems are an important cause of blackouts. Analysis of North American blackout data has revealed power law (algebraic) tails in the blackout size probability distribution which suggests a dynamical origin. With this observation as motivation, we examine cascading failure in a simplified transmission system model as load power demand is increased. The model represents generators, loads, the transmission line network, and the operating limits on these components. Two types of critical points are identified and are characterized by transmission line flow limits and generator capability limits, respectively. Results are obtained for tree networks of a regular form and a more realistic 118-node network. It is found that operation near critical points can produce power law tails in the blackout size probability distribution similar to those observed. The complex nature of the solution space due to the interaction of the two critical points is examined.(c) 2002 American Institute of Physics. 相似文献
628.
Highly optimized tolerance is a model of optimization in engineered systems, which gives rise to power-law distributions of failure events in such systems. The archetypal example is the highly optimized forest fire model. Here we give an analytic solution for this model which explains the origin of the power laws. We also generalize the model to incorporate risk aversion, which results in truncation of the tails of the power law so that the probability of catastrophically large events is dramatically lowered, giving the system more robustness. 相似文献
629.
J. Carter A. A. Cowley H. Diesener R. W. Fearick S. V. Frtsch M. N. Harakeh J. J. Lawrie S. J. Mills P. von Neumann-Cosel R. T. Newman J. V. Pilcher A. Richter K. Schweda F. D. Smit G. F. Steyn S. Strauch D. M. Whittal 《Nuclear Physics A》1998,630(3-4)
The 40Ca(p,p′ α) reaction has been studied at an incident proton energy Ep = 99.5 MeV for proton laboratory scattering angles Θplab = 17°, 23° and 27°. Emission of α particles coincident with the scattered proton has been measured for an angular range Θα 0° − 180° relative to the recoil axis. A multipole decomposition for the α0-decay channel to the 36Ar ground state has been performed from the angular-correlation functions. The energy distribution of the dominating E2 strength deduced in the excitation energy range Ex = 11–21 MeV agrees reasonably well with the results from electron and α-induced α0-decay investigations. The exhaustion of the E2 energy-weighted sum rule in this channel up to an energy of 17 MeV is 16.1(4.0)%, in accord with the study of the (α, α′ α0) reaction. However, this value is twice what is found in the (e,e′ α0) experiment in the same energy region. Thus, the puzzling discrepancy in the E2 strengths derived from electromagnetic and hadronic probes remains unsolved. 相似文献
630.
A proof of the Ger?gorin disk theorem is given, in which the only analytic tool used is a contour integral. 相似文献