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11.
Summary Teaching of Computer Based Analytical Chemistry (COBAC) is considered with emphasis on a regular course in the education of chemists. A proposal for conducting a COBAC course is made and discussed from the point of view of introducing basic principles in lectures and of putting the presented methods into practice in parallel tutorial computer sessions. 相似文献
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It is shown that, for solid caps D of heat balls in ? d + 1 with center z 0 = (0, 0), there exist Borel measurable functions w on D such that inf w(D) > 0 and ∫ v(z)w(z) dz ≤ v(z 0), for every supertemperature v on a neighborhood of D?. This disproves a conjecture by N. Suzuki and N.A. Watson. On the other hand, it turns out that there is no such volume mean density, if the bounded domain D in ? d × (?∞, 0) is only slightly wider at z 0 than a heat ball. 相似文献
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This paper characterizes the subsets E of which have the following property: there exists a harmonic function u on such that as for each x inE. This problem has its roots in classical work of Lusin and Privalov, and the answer has been known for some time in the case
where n=1. However, the characterization turns out to be more delicate in higher dimensions.
Received: 19 March 2000 / Published online: 1 February 2002 相似文献
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Summary For purposes of trace element analysis of organic materials a combined analytical procedure is tested. It consists of a pressure decomposition by nitric acid at 220° C in quartz vessels. The measurements are performed in the diluted digests by inductively coupled plasma/mass spectrometry. Analytical figures of merit are given.Dedicated to Prof. Dr. Karl Winsauer on the occasion of his 60th birthday. 相似文献
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Let X be a Green domain in Rd, d?2, x∈X, and let Mx(P(X)) denote the compact convex set of all representing measures for x. Recently it has been proven that the set of harmonic measures , U open in X, x∈U, which is contained in the set of extreme points of Mx(P(X)), is dense in Mx(P(X)). In this paper, it is shown that Mx(P(X)) is not a simplex (and hence not a Poulsen simplex). This is achieved by constructing open neighborhoods U0, U1, U2, U3 of x such that the harmonic measures are pairwise different and . In fact, these measures form a square with respect to a natural L2-structure. Since the construction is mainly based on having certain symmetries, it can be carried out just as well for Riesz potentials, the Heisenberg group (or any stratified Lie algebra), and the heat equation (or more general parabolic situations). 相似文献
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We consider self-avoiding walks on the backbone of percolation clusters in space dimensions d=2,3,4. Applying numerical simulations, we show that the whole multifractal spectrum of singularities emerges in exploring the peculiarities of the model. We obtain estimates for the set of critical exponents that govern scaling laws of higher moments of the distribution of percolation cluster sites visited by self-avoiding walks, in a good correspondence with an appropriately summed field-theoretical epsilon=6-d expansion [H.-K. Janssen and O. Stenull, Phys. Rev. E 75, 020801(R) (2007)10.1103/PhysRevE.75.020801]. 相似文献
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The two-dimensional J-J' dimerized quantum Heisenberg model is studied on the square lattice by means of (stochastic series expansion) quantum Monte Carlo simulations as a function of the coupling ratio alpha=J'/J. The critical point of the order-disorder quantum phase transition in the J-J' model is determined as alpha_c=2.5196(2) by finite-size scaling for up to approximately 10 000 quantum spins. By comparing six dimerized models we show, contrary to the current belief, that the critical exponents of the J-J' model are not in agreement with the three-dimensional classical Heisenberg universality class. This lends support to the notion of nontrivial critical excitations at the quantum critical point. 相似文献