articles
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The paper concentrating on random linear network coding in the presence of symbolic erasures
besides packets errors and erasures. New models of network are constructed based on two new models
of nodes with extended node alphabets. Alphabets of those nodes include special symbols to save
linear transformation with corresponding coordinate of packet, which occurs during linear combinations
on the following nodes on network. In the first model, extending alphabet contains only one special
symbol “*”, in the second model, every node has personal alphabet that not intersected with others.
Network coding methods based on Koetter-Kschischang-Silva network codes and channel errorcorrecting
codes are represented. Coding methods are based on idea of cascading use of channel and
network coders on network’s source. On sinks of network applies both as channel code decoder and
network code decoder with some modifications in reverse order. First coding method uses first model
of nodes and applied in case of number of symbols erasures does not exceed the error-correcting capability
of channel code. In the opposite case are applied second model and corresponding coding
method, which are representing probability decoder. An applicability opportunity of these methods to
unauthorized using of linear networks by illegal user is noticed.
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№ 1(73)
27 february 2018 year
Rubric: Software development technologies Authors: Myasnikov S., Namiot D. |
The paper examines the main aspects of testing the performance of software products. The article
gives a classification of testing methods. The main focus is on so-called load testing. Load testing is
conducted to determine the degree to which the system meets non-functional requirements, such as
the maximum number of simultaneous users, the response time of the information service, and so on.
To verify such requirements, as a rule, we need to emulate user activity, close to real. Load testing is
conducted to determine how quickly the computing system or part of it under a certain load, as well
as confirm other attributes of system quality, such as scalability, reliability and resource consumption.
The paper describes in detail the different types of stress tests, as well as a testing methodology for
each species. This list includesб for example, the detection of maximum performance, reliability and
fault tolerance tests, localization of performance problems. The article suggests also a set of indicators
for the classification of testing tools, on the basis of which a comparative analysis of existing tools
for conducting load testing is given.
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№ 1(73)
27 february 2018 year
Rubric: Software development technologies Authors: Alekseev Е., Boltacheva N., Demin P. |
The article is devoted to the use of new parallelism technologies, which appeared in modern Fortran
standards (Fortran-2003, Fortran-2008). The authors describe conveyor operations and subroutines.
Examples of speeding up programs on Fortran using conveyor operations are given. New technologies
of parallelism are considered for the first time: coarrays and auto-parallelization. On the example
of iterative algorithms for solving systems of linear algebraic equations, the analysis of the speed of
parallel programs is performed using all concurrency technologies supported by Fortran compilers.
A comparative analysis of the performance of free and proprietary compilers is carried out. The recommendations
on the use of various Fortran compilers for solving computational problems are presented.
The features of coding on modern Fortran are described with the use of various compilers.
Provided reasoned recommendations on the use of Fortran as a system of mathematical modeling.
Literature sources are presented, in which the graphical conclusion of research results in cross-platform
programs on Fortran is described.
The choice of Fortran as the language of teaching programming for students of mathematical, physical,
biological, chemical and technical specialties is justified.
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Multi-Agent approach is proposed for applications of real-time control and management of the microgrids.
The multi-agent system (MAS) structure and content design are presented. MAS functionality
is defined in order to optimize the real-time operation of a microgrid by optimally scheduling
its distributed generation and managing demand and supply. Economic and environmental factors, as
well as standardized electric power reliability indices are adopted as optimization criteria. Moreover,
the paper also presents a model for evaluation of economic, technological and ecological efficiency of
the interaction of elements of the proposed MAS based on an artificial neural network (ANN) model
implementation.
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The scale of features informativeness is formulated and presented. The efficiency of «wide» neural
network neurons based on the various variations of following criteria for checking the distribution law
of a random variable was evaluated: Smirnov-Kramer-von Mises, Anderson-Darling, Watson, Frotsini,
average geometric comparison functions for probability densities Kolmogorov-Smirnov, Cooper. A criterion
for the maximum area of intersection of the comparable probability density functions is proposed.
Variants for the modernization of functionals for the processing of features with a noticeable and high
correlation dependence are found, in particular, on the basis of the Smirnov-Kramer-von Mises criterion.
The analysis of the results of the work made it possible to determine the most suitable conditions
for the use of the functionals under consideration, depending on the features of the feature space. The
boundary conditions of the experiment correspond to the features of dynamic biometric patterns. First
of all, the research was aimed at solving the problems of recognizing secret biometric images, but the
results obtained can be used in any verification task, where there are dependent and independent signs
of average informativeness, as well as little informative and extremely little informative features with
a distribution of values close to normal.
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The purpose of writing this work is to develop a software tool for finding the optimal portfolio
of wholesale purchases of a trading enterprise. The software is developed on the basis of the created
mathematical models and functional model. The mathematical models takes into account the restrictions
on the volume of working capital spent on wholesale purchases of goods, restrictions on the volume
of goods in the warehouse of wholesale purchases, demand constraints and some others. The functional
model describes the structure of the system for determining the optimal portfolio of wholesale
purchases of a trading company and created on the basis of graphical notation IDEF0. The operation
principle of the algorithm is illustrated by a block diagram. The algorithm of the software is based on
the branch and bound method. The work of the software is demonstrated on a practical example of
searching for the optimal portfolio of wholesale purchases of ventilation equipment. A software tool
can be of interest to managers who are developing a wholesale purchase plan.
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