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51.
On Polynomial Functions over Finite Commutative Rings 总被引:1,自引:0,他引:1
Jian Jun JIANG Guo Hua PENG Qi SUN Qi Fan ZHANG 《数学学报(英文版)》2006,22(4):1047-1050
Let R be an arbitrary finite commutative local ring. In this paper, we obtain a necessary and sufficient condition for a function over R to be a polynomial function. Before this paper, necessary and sufficient conditions for a function to be a polynomial function over some special finite commutative local rings were obtained. 相似文献
52.
A Bayesian approach is used to analyze the seismic events with magnitudes at least 4.7 on Taiwan. Following the idea proposed
by Ogata (1988,Journal of the American Statistical Association,83, 9–27), an epidemic model for the process of occurrence times given the observed magnitude values is considered, incorporated
with gamma prior distributions for the parameters in the model, while the hyper-parameters of the prior are essentially determined
by the seismic data in an earlier period. Bayesian inference is made on the conditional intensity function via Markov chain
Monte Carlo method. The results yield acceptable accuracies in predicting large earthquake events within short time periods. 相似文献
53.
We give an account of the appearance and first developments of the statistical model of atoms proposed by Thomas and Fermi, focusing on the main results achieved by Fermi and his group in Rome. Particular attention is addressed to the unknown contribution to this subject by Majorana, anticipating some important results reached later by leading physicists. 相似文献
54.
We show that there is a threshold in energy for the onset of chaos in cosmology for the Universe described as a dynamical system derived from the Einstein equations of General Relativity (GR). In the case of the mixmaster model (homogeneous and anisotropic cosmology with a Bianchi IX metric), the chaos occurs precisely at the prescribed necessary value H
vac=0 of the GR for the energy of the Universe while the system is found to be regular for H<0 and chaotic for H>0 with respect to its pure vacuum part. In the case of generalized scalar tensor theories within the Bianchi IX model, we show using the ADM formalism and a conformal transformation that the energy of the dynamical system as compared to vacuum lies below the zero energy threshold. The system is thus not exhibiting chaos and the conclusion still holds in the presence of ordinary matter as well. The suppression of chaos occurs in a similar way for stiff matter alone. 相似文献
55.
Fan Chung 《Annals of Combinatorics》2005,9(1):1-19
We consider Laplacians for directed graphs and examine their eigenvalues. We introduce a notion of a circulation in a directed graph and its connection with the Rayleigh quotient. We then define a Cheeger constant and establish the Cheeger inequality for directed graphs. These relations can be used to deal with various problems that often arise in the study of non-reversible Markov chains including bounding the rate of convergence and deriving comparison theorems.Received September 8, 2004 相似文献
56.
Shui Cao ZHENG Huo Nan LIN Di He HU 《数学学报(英文版)》2005,21(5):1137-1148
In this paper, we investigate the Hausdorff measure for level sets of N-parameter Rd-valued stable processes, and develop a means of seeking the exact Hausdorff measure function for level sets of N-parameter Rd-valued stable processes. We show that the exact Hausdorff measure function of level sets of N-parameter Rd-valued symmetric stable processes of index α is Ф(r) = r^N-d/α (log log l/r)d/α when Nα 〉 d. In addition, we obtain a sharp lower bound for the Hausdorff measure of level sets of general (N, d, α) strictly stable processes. 相似文献
57.
Tunable microlens arrays using polymer network liquid crystal 总被引:1,自引:0,他引:1
A tunable-focus microlens array based on polymer network liquid crystal (PNLC) is demonstrated. The PNLC was prepared using an ultraviolet (UV) light exposure through a patterned photomask. The photocurable monomer in each of the UV exposed spot forms an inhomogeneous centro-symmetrical polymer network which acts as a lens when a homogeneous electric field is applied to the cell. The focal length of the microlens arrays is tunable with the applied voltage. 相似文献
58.
59.
Summary Vezetéknév 相似文献
60.
Through arylsulfonyl activation of thiourea, efficient synthesis of oligomeric guanidines can be achieved in either solution or solid-phase. Incorporation of TFA-sensitive arylsulfonyl groups, such as Pbf, during the synthesis greatly simplifies deprotection procedures for obtaining the final oligomeric guanidine products. 相似文献