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Том 40, № 4 (2016)
- Год: 2016
- Статей: 7
- URL: https://journals.rcsi.science/0278-6419/issue/view/10799
Article
On the convergence of the Dirichlet grid problem with a singularity for a singularly perturbed convection–diffusion equation
Аннотация
The Dirichlet problem for a singulary perturbed convection–diffusion equation in a rectangle when a discontinuity at the flow exit the first derivative of the boundary condition gives rise to an inner layer for the solution. On piecewise-uniform Shishkin grids that condense near regular and characteristic layers, the solution obtained using the classical five-point difference scheme with a directed difference is shown to converge with respect to the small parameter to solve the original problem in the grid norm L∞h almost with the first order. This theoretical result is confirmed via numerical analysis.
147-154
Influence of Gibbs phenomenon on the mutual coherence in sparse representations
Аннотация
The influence of ringing effect (which is based on the Gibbs phenomenon) on the mutual coherence in sparse representation approach is considered. It is shown that for random vectors, the ringing effect increases the average mutual coherence. Numerical results that demonstrate that the mutual coherence behaves identically for real images are given. It is also shown how the ringing effect affects the sparsity of representations (which is closely related to the mutual coherence).
155-160
161-164
Theoretical game analysis of position auctions according to the Vickrey–Clarke–Groves mechanism with two-stage ranking
Аннотация
Different types of position auctions are considered. A position auction is a mechanism for the allocation of advertising space in search engine results to a user-defined query. Advertisers make bids they are willing to pay the search engine for a click to their website. The search engine determines whose advertisements will get to the page and in what position, based on the bids of all the advertisers. Different types of such auctions are discussed using the example of the Yandex search engine based on the Vickrey–Clarke–Grovesmechanism. The main result is a formalization of the concept of an auction with two-stage ranking and its balance test.
165-170
Modeling futures price dynamics on the RTS and MICEX indices
Аннотация
Reasons for the substantial differences of historical and theoretical futures prices on RTS and MICEX indices are investigated. A model is proposed that considers the observed differences for the modeling of futures prices within the risk assessment of a portfolio of derivatives using the Monte Carlo method.
171-178
Machine learning methods for analyzing user behavior when accessing text data in information security problems
Аннотация
A new method for detecting user access to irrelevant documents based on estimating the document text membership in typical subject areas of the analyzed user is proposed. The typical subject areas are formed using subject area modeling implemented via orthonormal nonnegative matrix factorization. An experimental study with real corporate correspondence formed from an Enron data set demonstrates the high classification accuracy of the proposed method, compared to traditional approaches.
179-184
Investigating and predicting the perceptibility protect of channel mismatch in stereoscopic video
Аннотация
The degree of visual discomfort caused by watching stereoscopic scenes with channel mismatch is investigated and predicted. A scene with channel order mismatch is one in which the right and left views are swapped. A way of finding channelmismatch is used to analyze 105 3D films; the scenes found in this analysis are used for experimental study of the visual discomfort caused by channelmismatch. The experimental results are used to construct samplingwith a reference pattern. This sampling is used to learn different regression analysis algorithms, and the bestway of predicting visual discomfort caused by channel mismatch is chosen.
185-191