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scientific edition of Bauman MSTU


Bauman Moscow State Technical University.   El № FS 77 - 48211.   ISSN 1994-0408

Informatics, Computer Science and Management

77-30569/274006 Frequency dictionaries time stability rating in texts identification
# 12, December 2011
Y.N. Pavlov, E.A. Tihomirova
 The article presents the time stability assessment results of F. Dostoevsky’s and M. Gorky’s vocabularies. The resulting statistical characteristics suggest that frequency dictionaries are unstable. That is why informativity of identifying the authors of the frequency dictionary is poor. The authors also show that a large percentage of words found by these authors are statistically indistinguishable. This fact, in the authors’ opinion, will help to improve authorship examination quality.
77-30569/292475 Object-oriented description of subject domain when modeling elimination of oil spills
# 11, November 2011
V.M. Chernen'kii, P.G. Ercev
Articel is devoted to the problem of environment description when eliminating oil spills. It was suggested to create an object-oriented description of subject domain in order to further research with simulation methods. To create the concept of object, the spatial decomposition was produced. After forming 2D mesh in the xy plane and the decomposition of z axes, it became possible to use the concept of cell, layer and section. A cell is characterized with a set of components within its limits; these components are organized as a tree. Components are characterized with parameters; basic operations such as decomposition, synthesis, transformation, internal conversion and operations of component movement are defined over these parameters. It was proposed to used an algorithmic model for the description of conversion processes.
77-30569/270497 Cost-criterion selection algorithm of parallel system database architecture
# 12, December 2011
Yu.A. Grigor'ev, V.L. Pluzhnikov
In the article the authors suggest expressions which make it possible to estimate the aggregate value of possessing database parallel systems (DPS). The authors developed an algorithm of DPS selection which allows for specific character of the comparison of DPS architectures and special feature of cost estimates. By means of sequential growth of the number of AMP-processors and SMP-units the algorithm orders the database parallel systems with SE, CE and SN architectures according to their cost increase. It is shown that in this sequence it is possible to isolate the subsequence in which DPS are ordered according to descending ordering of the mean time of responding to requests. As in the algorithm all DPS versions are consecutively analyzed, in the finite number of iterations optimal solution will be found
77-30569/296143 Estimation of SQL-query execution time
# 01, January 2012
Yu.A. Grigor'ev
Mathematical apparatus of analysis of SELECT-query execution time in distributed database, considering the mechanisms of complex query decomposition into sub-queries and connection of their results, the parameters of logic scheme and random characteristics of database filling. Proposed approach could be used at early stages of design for estimation of time characteristics of execution of different complex queries on different hardware platforms. In this manner, estimation was in form of Laplase-Stieltjes transformation, that allowed to estimate not only average values but also dispersions and other issues.
77-30569/292147 Algorithm of simulation process' generating
# 11, November 2011
V.M. Chernen'kii
Rules and algorithms of simulation process generating, based on the description of discrete system's functioning as a set of connected series-parallel processes, represented as algorithmic models are presented in this article. Fundamentals of algorithmic process model are briefly described. Rules providing correct generating of a class of simultaneous events (CSE) were introduced. Content and algorithms of basic components of generating algorithm such as a set of event subprograms, an algorithm of CSE selection, a program “Calendar”, a program which checks the conditions, a structure of controlling tables. Algorithms of two modeling program were included. They are scanning and linear types of program. Their performance was analyzed.
77-30569/292620 Algorithmic model of discrete process description of system functioning
# 12, December 2011
V.M. Chernen'kii
This article deals with algorithmic process model as a form of process description. It was suggested to specify the process description as a linear sequence of elementary operators; each operator compute only one point in state space of the system. The properties of every component of an algorithmic model were described; these components are elementary operator, track and initiator. The transformation of the track allowed introducing the concept of structure that led to the decreasing of description dimension. Different structure types were analyzed; the high adaptive specifying form of the structure was presented.  It was shown that proposed model covers a wide range of processes of discrete system functioning.
77-30569/294486 Algorithm of synthesis of suboptimal scheme of relational database
# 01, January 2012
Yu.A. Grigor'ev
This article deals with algorithm of synthesis of database scheme based on the given set of functional dependences. Bernshtein’s algorithm was described; it was shown that usage of (G* + J)+ = (G + J)+ condition caused calculation problems, because covering of FD F+ set could exponentially depend on the size of F. Algorithm, based on Ullman’s ideas, was proposed; it provided relatively simple implementation. Generated database scheme had the property of lossless connection, maintenance of functional dependences and each sub-scheme of this database was in the third normal form. Example of database scheme synthesis using the proposed algorithm was included in this article.
77-30569/291975 The forming of simulation process, based on algorithmic description of information system's functioning
# 11, November 2011
V.M. Chernen'kii
This article deals with the basic principles of simulation process' organizing, based on the description of discrete system's functioning as a set of connected series-parallel processes, represented as algorithmic models. Fundamentals of algorithmic description are summarized. Influence of the connection of processes and operators on the execution order of elementary operators in simulation process is analyzed. The concept of active temporary set was introduced, several of its properties were proved. Also author introduced the concept of action as the fact that an elementary operator has worked out. The actions were classified by their activity in time. The concept of class of simultaneous events at the forming of simulation process appeared to be very useful and important. Properties of class and rules of its creating were proved.
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