Две вычислительные реализации фильтрации по кажущимся скоростям массивов записей многоэлементного волнового акустического каротажа
Two realizations of direct and inverse Radon transform were considered for solving the problem of velocity filtering of acoustic logging data, represented as arrays in (t ‑ x)-area (time – linear spatial coordinate): 1) through (τ – p)-area (travel time – slowness ); 2) through (f – p)-area (frequency – slowness). Original MATLAB-functions are outlined, comparison of filtering results for arrays of multielement wave acoustic logging data are adduced.
Printed documents protection problem against leakage is still one of the relevant. Existing security tools allow us to protect electronic text documents, however are ineffective in protecting their printed versions. This research presents the marking approach for text electronic documents invariant to the print-and-scan transformation. During marker embedding source text line spacing values are changing to the specified values within perceptual invisibility. The watermark extraction is carried out from the images containing text and based on normal Radon transform and Gaussian mixture model. This marking approach is robust to various image transformations and distortions. The accuracy of embedded information extraction was more than 0.98 for 200 DPI images and line spacing value change about 490 micrometers.
A computer implementation of the method of dispersive semblance for multi-element wave acoustic logging is proposed. The correction matrix for dispersion is constructed in (f-p)-domain using sets of dispersion curves of the flexural wave or Stoneley wave. The matrix is applied in computing scheme of the conventional semblance method in (tau-p)-domain (the Matlab script is given in electronic appendix).
This paper presents an approach to a robust watermark extraction from images containing text. Data extraction based on developed approach to robust watermark embedding into text data, characterizing by conversion invariance of text data into an image format. The comparative analysis of existing approaches of steganographic data embedding into text data is carried out, their advantages and disadvantages are determined. The choice of groups to steganographic data embedding methods based on text formatting is justified. As an embedding algorithm is determined approach based on interline space shifting. The block diagram and the description of the developed algorithm of data embedding into text data are given. An experimental estimation of the embedding capacity and perceptual invisibility of the developed data embedding approach was carried out. An approach to extract embedded information from images containing a robust watermark, based on the existing limitations, has been developed. The Radon transform is chosen as the basic extraction procedure of embedded information, allowing to extract values of the interline spacing. An approach based on Gaussian mixture model separating to isolate the values of the bits was chosen. The limits of the retrieval of embedded data have been experimentally established, and the robustness of the developed embedding approach to the implementation of various transformations has been estimated. The following parameters of robustness developed approach are defined: rotation of an image containing embedded data at any angle; scaling an image with a scaling factor not exceeding 1.5; conversion to any bitmap format; the application of a median filter to an image with a convolution core limit of not more than 9, a Gaussian blur filter with a blurring limit not exceeding 8 and an average filter with a convolution kernel limit of not more than 5.
This volume presents new results in the study and optimization of information transmission models in telecommunication networks using different approaches, mainly based on theiries of queueing systems and queueing networks .
The paper provides a number of proposed draft operational guidelines for technology measurement and includes a number of tentative technology definitions to be used for statistical purposes, principles for identification and classification of potentially growing technology areas, suggestions on the survey strategies and indicators. These are the key components of an internationally harmonized framework for collecting and interpreting technology data that would need to be further developed through a broader consultation process. A summary of definitions of technology already available in OECD manuals and the stocktaking results are provided in the Annex section.