Mechanism of refractory wear in the reaction shaft of furnaces for melting of raw material in the suspended state

Conclusions The mechanism of failure of chrome-magnesite refractories under conditions of autogenous melting of sulfide ore was studied.On the basis of an analysis of the thermal operation of the lining taking into consideration the closeness of domestic refractories in thermophysical properties to Radex CN refractories, lining of the reaction shaft with domestic refractories was recommended.Translated from Ogneupory, No. 5, pp. 49–52, May, 1986.     

Technological parameters of corundum chamotte

Conclusions It has been established that to obtain densely sintered macrocrystalline corundum chamotte it is most expedient to obtain the briquet in the form of granules 20–25 mm in diameter from finely ground GK alumina (or special alumina brands of high purity) followed by annealing at 1900–1950°C.Translated from Ogneupory, No. 3, pp. 31–36, March, 1980.     

Using Ideas of Kolmogorov Complexity for Studying Biological Texts

Kolmogorov complexity furnishes many useful tools for studying different natural processes that can be expressed using sequences of symbols from a finite alphabet (texts), such as genetic texts, literary and music texts, animal communications, etc. Although Kolmogorov complexity is not algorithmically computable, in a certain sense it can be estimated by means of data compressors. Here we suggest a method of analysis of sequences based on ideas of Kolmogorov complexity and mathematical statistics, and apply this method to biological (ethological) ??texts.?? A distinction of the suggested method from other approaches to the analysis of sequential data by means of Kolmogorov complexity is that it belongs to the framework of mathematical statistics, more specifically, that of hypothesis testing. This makes it a promising candidate for being included in the toolbox of standard biological methods of analysis of different natural texts, from DNA sequences to animal behavioural patterns (ethological ??texts??). Two examples of analysis of ethological texts are considered in this paper. Theses examples show that the proposed method is a useful tool for distinguishing between stereotyped and flexible behaviours, which is important for behavioural and evolutionary studies.     

Synthesis of ZnO-based nanostructures for heterostructure photovoltaic cells

A model describing heterostructure solar cells based on zinc and copper oxides is developed. Seed layers of ZnO and CuO are synthesized by spray pyrolysis. To form a bulk heterojunction, ZnO nanorods are grown by hydrothermal synthesis. The morphological, electricaland optical properties of the fabricated structures are investigated.     

Coding combinatorial sources with costs

We consider coding infinite sequences of a finite alphabet. The source is defined as a set of sequences (combinatorial source). The problem is to minimize the worst asymptotic compression ratio between each sequence and its coding output among the sequences in the combinatorial source. Ryabko showed that the optimal value coincides with the Hausdorff dimension of the combinatorial source. This correspondence extends the previous work in that the input and output costs are expressed in terms of not lengths but generalized costs. The essential quantity turns out to be the Hausdorff dimension with respect to the measure associated with the input cost. We construct an asymptotically optimal coding procedure, and also show that no coding scheme can beat the lower bound.     

Sample Complexity for Computational Classification Problems

In a statistical setting of the classification (pattern recognition) problem the number of examples required to approximate an unknown labelling function is linear in the VC dimension of the target learning class. In this work we consider the question of whether such bounds exist if we restrict our attention to computable classification methods, assuming that the unknown labelling function is also computable. We find that in this case the number of examples required for a computable method to approximate the labelling function not only is not linear, but grows faster (in the VC dimension of the class) than any computable function. No time or space constraints are put on the predictors or target functions; the only resource we consider is the training examples. The task of classification is considered in conjunction with another learning problem - data compression. An impossibility result for the task of data compression allows us to estimate the sample complexity for pattern recognition.     

Simulation of the properties of a single-polarization microstructured optical fiber

For the first time, the properties of a single-polarization microstructured fiber exhibited over a broad spectral range have been numerically simulated. The simulation was performed via the multipole method adapted to asymmetric structures. A structure with the highest values of birefringence and dichroism known to date has been proposed and investigated.     

Information-Theoretic method for classification of texts

We consider a method for automatic (i.e., unmanned) text classification based on methods of universal source coding (or “data compression”). We show that under certain restrictions the proposed method is consistent, i.e., the classification error tends to zero with increasing text lengths. As an example of practical use of the method we consider the classification problem for scientific texts (research papers, books, etc.). The proposed method is experimentally shown to be highly efficient.     

Constructing perfect steganographic systems

We propose steganographic systems for the case when covertexts (containers) are generated by a finite-memory source with possibly unknown statistics. The probability distributions of covertexts with and without hidden information are the same; this means that the proposed stegosystems are perfectly secure, i.e. an observer cannot determine whether hidden information is being transmitted. The speed of transmission of hidden information can be made arbitrary close to the theoretical limit — the Shannon entropy of the source of covertexts. An interesting feature of the suggested stegosystems is that they do not require any (secret or public) key.At the same time, we outline some principled computational limitations on steganography. We show that there are such sources of covertexts, that any stegosystem that has linear (in the length of the covertext) speed of transmission of hidden text must have an exponential Kolmogorov complexity. This shows, in particular, that some assumptions on the sources of covertext are necessary.     

Experimental investigation of forecasting methods based on data compression algorithms

We suggest and experimentally investigate a method to construct forecasting algorithms based on data compression methods (or the so-called archivers). By the example of predicting currency exchange rates we show that the precision of thus obtained predictions is relatively high.Translated from Problemy Peredachi Informatsii, No. 1, 2005, pp. 74–78.Original Russian Text Copyright © 2005 by Ryabko, Monarev.Supported in part by the Russian Foundation for Basic Research, project no. 03-01-00495, and INTAS, Grant 00-738.