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41.
Winfried Wendelin Ilse Zmölnig Hans-Wolfgang Schramm 《Monatshefte für Chemie / Chemical Monthly》1980,111(5):1189-1202
Guanidine reacts with cyclohexanone, cycloheptanone, acetone and 3-pentanone, resp., in a molar ratio 2∶1 to give the 1,3,5-triazaspiro[5.5]undeca-and [5.6]dodeca-1,3-dien-2,4-diamines3 a and3 b resp. and the 6,6-dimethylresp. diethyl-1,6-dihydro-1,3,5-triazin-2,4-diamines3 d and3 e resp. On the contrary, action of guanidine on cyclopentanone yields not3 c, but the 1′,5′,7′-tetrahydrospiro[cyclopentane-1,4′-cyclopentapyrimidine]-2′(3′H)-imines2 c, 5 c and6 c resp., which are 1∶2- and 1∶3-condensates. Phenylacetone is transformed by guanidine (1∶2) to give 6-phenyl-2,4-pyrimidindiamine (8 f). The structure of the compounds cited is proved by NMR-, IR-, and (partially) mass spectra. The different courses of the formation of3 a, b, d, e, 2 c, 5 c and6 c resp. and8 f are also discussed. The structural formulae of some additional bases, which were synthesized from guanidine and cyclopentanone, 3-pentanone and phenylacetone resp. could not be established. 相似文献
42.
Winfried Kohnen 《The Ramanujan Journal》2018,45(2):491-495
We will give a new proof for the fact that the values of Dedekind sums are dense on the real line. 相似文献
43.
In this paper, we consider a queueing system in which there are two exponential servers, each having his own queue, and arriving
customers will join the shorter queue. Based on the results given in Flatto and McKean, we rewrite the formula for the probability
that there are exactlyk customers in each queue, wherek = 0, 1,…. This enables us to present an algorithm for computing these probabilities and then to find the joint distribution
of the queue lengths in the system. A program and numerical examples are given. 相似文献
44.
This author wants to express his thanks to the School of Information Engineering at Teesside Polytechnic, Middlesbrough, England, for its support and hospitality during a visiting appointment of 3 months in 1989, when this paper was written. 相似文献
45.
Winfried Teschner 《基于设计的结构力学与机械力学》2013,41(4):491-500
The application of optimal control theory to minimum weight design of continuous one-dimensional structural elements subject to eigenvalue constraints is discussed. If not only the value of an eigenvalue is prescribed but also its position in the sequence of the ordered eigenvalues—for example, the critical buckling load of a column—the corresponding optimal control problem is shown to include necessarily all eigenvalues. Considering the unspecified eigenvalues as free parameters, necessary conditions for minimum weight design are derived. These conditions are compared with those obtained by use of variational methods. Attention is focused on the special case of multimodal solutions. 相似文献
46.
We investigate optimal linear approximations (approximation numbers) in the context of periodic Sobolev spaces Hs(Td) of fractional smoothness s>0 for various equivalent norms including the classical one. The error is always measured in L2(Td). Particular emphasis is given to the dependence of all constants on the dimension d. We capture the exact decay rate in n and the exact decay order of the constants with respect to d, which is in fact polynomial. As a consequence we observe that none of our considered approximation problems suffers from the curse of dimensionality. Surprisingly, the square integrability of all weak derivatives up to order three (classical Sobolev norm) guarantees weak tractability of the associated multivariate approximation problem. 相似文献
47.
Winfried Kohnen 《Proceedings of the American Mathematical Society》2007,135(4):997-999
We shall show that the eigenvalues of a Hecke eigenform of integral weight and genus 2 not contained in the Maass space change signs infinitely often.
48.
We investigate traces of functions, belonging to a class of functions with dominating mixed smoothness in ℝ3, with respect to planes in oblique position. In comparison with the classical theory for isotropic spaces a few new phenomenona
occur. We shall present two different approaches. One is based on the use of the Fourier transform and restricted to p = 2. The other one is applicable in the general case of Besov-Lizorkin-Triebel spaces and based on atomic decompositions. 相似文献
49.
Dr. Winfried Recknagel 《Monatshefte für Mathematik》1985,100(4):293-298
An equivalent form of the classical circle problem is the unproved conjecture (3)
. In this note the corresponding conjecture with
k
(.) (the 1-periodic Bernoulli polynomials of orderk2) instead of 1(.) is settled in an affirmative way (even with =0). Moreover, a generalized sum (6) is estimated by means of an analogue to a classical result due tovan der Corput. 相似文献
50.
Winfried Sickel Frauke Sprengel 《Journal of Computational Analysis and Applications》1999,1(3):263-288
We investigate the order of convergence of periodic interpolation on sparse grids (blending interpolation) in the framework of tensor products of Nikol'skij–Besov spaces. To this end, we make use of the uniformity of the considered tensor norms and provide a unified approach to error estimates for the interpolation of univariate periodic functions from Nikol'skij–Besov spaces. 相似文献