Bookmark
Next issue
№4
Publication date:
16 December 2019
Articles of journal № 4 at 2019 year.
Order result by: Public date | Title | Authors |
1. Fuzzy set approach for IT project task management [№4 за 2019 год]
Authors: A.R. Diyazitdinova, N.I. Limanova
Visitors: 2745
Resource distribution and allocation problems are complex multi-criteria tasks. Therefore, the problem of development of effec-tive and universal technologies of work assignment among performers turns out to be challenging in software project manage-ment. One of the possible solutions to increase the relevance of project management decision-making in software development companies might be fuzzy logic. It allows processing semi-structured and inaccurate information using a natural language. The paper proposes a model of fuzzy production system to manage IT project tasks that allows operating natural language categories to improve the efficiency of decision making under uncertainty and cost cutout in the extreme. The authors consider software product development features; develop a typical logic of IT project tasks management process; prove fuzzy logic tech-nology application reasons are for project management. Implementation of fuzzy logic mathematical tools technique allows a project manager to operate variables represented in quality categories without transferring to mean values that enables decision-making quality increase. The paper considers a problem of task (ticket) development performance evaluation. There are derived six input linguistic variables and one output. There are developed term sets and membership functions for each of them. The built expert rule base includes 81 production rules. A model of fuzzy logic production system model for tasks management has been implemented us-ing Fuzzy Logic Toolbox for MatLab. The Mamdani algorithm has been used for fuzzy inference. The provided results of the model functioning would be useful for IT project managers.
2. Algorithmic and software implementation of a cognitive agent based on G. Polya’s methodology [№4 за 2019 год]
Authors: S.S. Kurbatov, Fominykh I.B., A.B. Vorobev
Visitors: 3364
The paper describes an original approach to creating an integrated problem solving system (cognitive agent). The system in-volves a tight integration of linguistic processing stages, an ontological representation, a heuristically oriented solution and visu-alization. The system concept is based on the Polya’s methodology interpreted in algorithmic and software implementation. The system is implemented in a mock-up version and tested in the subject area “school geometry”. The linguistic component uses the problem canonical description obtaining method through paraphrasing and mapping it into a semantic structure. An automated solution search is based on implementing the rules that reflect the axioms of the respective subject areas. The heuristics presented in the ontology define the rules. The heuristics are designed as semantic network structures, which allows organizing a rule multiple-aspect search and selection justification as a natural language comment. Conceptual (cognitive) visualization provides the solution visual representation by interpreting a text file with information to display graphical objects, as well as comments on the solution process. Comments include natural language descriptions of rules (axioms, theorems), heuristic and empirical justifications for their choice and links to visualized objects. The paper defines experiments that demonstrate visualization possibilities of task drawings and ontology fragments, natural language phrases, mathematical and formal logic formulas. The ontology is implemented in the DBMS Progress. Visualization programs are implemented in JavaScript using JSXGraph and MathJax. The implementation provides a step-by-step solution view in different directions with dynamic changing in drawing and related comments. The authors have interpreted experimental results and planned the study to develop the described approach.
3. The unified representation of LTL and CTL logics formulas by recursive equation systems [№4 за 2019 год]
Authors: Korablin Yu.P., Shipov A.A.
Visitors: 1780
Nowadays, to solve the formal verification problem using the Model Checking method, the following logics are often used: the linear-time temporal logic (LTL), the computation tree logic (CTL) and CTL* that combines the capabilities of both other logics. However, each of these logics has its own disadvantages, limitations and expressiveness problems due to their syntactic and se-mantic features. Therefore, there is no universal temporal logic at the moment. The authors are convinced that special representations, which are based on systems of recursive equations in regard to tem-poral logics, can extend their expressiveness, as well as unify their syntax. Thus, they allow building their common and uniform notation. The paper proposes and considers a special RTL notation that is based on systems of recursive equations and the accus-tomed LTL and CTL semantic definitions. The notation is intended to solve the problem of unification of expressiveness of both logics, which in turn expands the expressiveness each one of them. The unification of their syntactic structures will give an opportunity to develop a uniform approach for the Model Checking problem. The authors provide a detailed definition of the RTL notation; give corresponding axioms and theorems. The paper also rep-resents a number of examples and statements that clearly demonstrate the RTL expressiveness capabilities. The purpose of the paper is to demonstrate key features and capabilities of the RTL notation, which are the basis for the au-thors' further research on solving the problem of system models verification.
4. CAD integration for logic synthesis using global optimization [№4 за 2019 год]
Authors: P.N. Bibilo, V.I. Romanov
Visitors: 3454
The paper proposes a technology for designing digital devices. This technology allows logical modeling of VHDL descriptions of combina-tional logic, forming the corresponding systems of Boolean functions, their logical optimizing and synthesizing logic circuits in various tech-nological libraries of logic elements. The software integration within this technology is based using scripts and BAT files that are supported by modern CAD systems. The source VHDL descriptions can set algorithmic and functional descriptions. They are truth tables of completely or noncompletely specified Boolean function systems, systems of partial Boolean functions, systems of disjunctive normal forms, descriptions of multilevel log-ical equations. In addition, structural descriptions of logic circuits synthesized in various target technological libraries might also be used as source VHDL descriptions. In this case, they are redesigned into another basis of logical elements. The transition from VHDL descriptions to systems of Boolean functions is based on logical simulation for all possible sets of input varia-bles. Logical optimization includes using of powerful programs of joint and separate minimization of Boolean function systems in the class of disjunctive normal forms, as well as programs of minimization of multilevel BDD representations (BDD – Binary Decision Diagram) of Boolean function systems based on Shannon’s expansion. A user only needs to specify a VHDL source description, a logical optimization method and a target library of logic elements used in the LeonardoSpectrum synthesizer. The required BAT file is generated automatically. The file provides synthesis using global logic optimization. The user can assess the solution found by comparing with another one that the LeonardoSpectrum synthesizer obtained from the original de-scription without prior optimization.
5. Using the Bayes' theorem within software quality evaluation according to ISO/IEC 9126 standard [№4 за 2019 год]
Authors: D.P. Burakov , G.I. Kozhomberdieva
Visitors: 1218
The paper discusses a way to use the approach based on well-known Bayes rule to evaluate software quality according to quali-ty model and evaluation process described in the ISO/IEC 9126 standard. In addition, it briefly describes software quality mod-els and evaluation process that are proposed by the abovementioned standard, as well as by the improved ISO/IEC 25010:2011 standard. The authors define the field of using the proposed approach during the evaluation process. The software quality evaluation is presented as a probability distribution on a set of hypotheses that software quality has reached one of the predefined quality levels proposed by the model. The Bayes' formula is used to build a posteriori probability distribution based on revised and refined during quality evaluation a priori probability distribution that is defined before evalua-tion. The source data for calculating probabilities is the results of measurement of heterogeneous quality metrics for arbitrary set of quality attributes that are specified in the software quality model. The proposed approach allows using both directly measured metrics and the metrics estimated by experts. In fact, the ap-proach gives reasonable software quality evaluation even if there are incomplete, inaccurate and inconsistent quality metrics.
6. Flexibility of using input and output parameters of standard and non-standard functions in MatLab [№4 за 2019 год]
Author: O.G. Revinskaya
Visitors: 1064
Based on a review of recent papers, the paper reveals the contradiction between the understanding of the breadth and flexibility of using input and output parameters of standard functions and the feeling of rigid predetermination when describing and using similar parameters of non-standard MatLab functions. This contradiction is resolved by a detailed analysis of the capabilities provided by MatLab (including its latest versions), so that the function parameters (when it is called) are interpreted as mandatory or optional, positioned or unpositioned, typed or untyped, etc. This variety of properties of input and output parameters provides flexibility in the application of standard MatLab functions. It is shown that by default MatLab controls only formal excess of the number of parameters used when calling a function (standard, non-standard) over the number of corresponding parameters specified in its description. For the parameters of a non-standard function to have certain properties, it is necessary to organize a function body program code in a special way: to check how many parameters are specified when the function is actually called, what type of information enters the function and exits through parameters; to analyze which optional parameters are set and which are not, etc. Such organization of the function body has been remaining very laborious for a long time. Therefore, the latest versions of MatLab have standard functions that auto-mate some of the performed operations. Thus, the article systematizes a set of measures that allow the parameters of a non-standard function to have the same breadth and flexibility of use as the parameters of standard MatLab functions. Based on personal experience in applied programming and teaching MatLab, the author shows simple examples that illus-trate in detail how to write non-standard functions with parameters that have the appropriate properties.
7. On the application of greedy algorithms in some problems of discrete mathematics [№4 за 2019 год]
Author: V.A. Boykov
Visitors: 883
The algorithms that are based on the idea of local optimality seem natural and tempting when solving optimization problems. However, the optimization problems discussed in the paper are multistage. In this case, the obtaining an optimal solution in a multistage problem by greedy algorithms is not guaranteed generally. This fact is demonstrated by the examples of solving a transport problem, the problem of the shortest distance between cities on a given road network, and the traveling salesman prob-lem. The research objects are greedy algorithms applied to solving the same problems described in this paper. The paper gives an example of a paradoxical solution of a small dimension transportation problem. When solving the prob-lem, one of greedy algorithms constructs a product transportation plan. However, this plan is not optimal and has a paradoxical property. Namely, no transportation by the route that is the cheapest in the optimal plan. The optimal solution of the considered problem is given by mathematical package Mathcad. The fact that the greedy algorithm does not show the optimal path is shown on the example of the shortest distance problem. Three counterexamples on Euclidean graphs show that it is impossible to obtain an optimal route even when calculating options several steps ahead. The third example of applying the greedy algorithm to solve the traveling salesman problem is the nearest city method. The method describes the sequential construction of the Hamiltonian cycle. The above version of the algorithm is secured from ob-taining non-connected graphs during a solution process. Further, the length of the Hamiltonian cycle is used as an upper bound when implementing the simplest version of the branch and bound method. The program made in Mathcad checks the optimality of the obtained solution. In the considered examples, the solutions obtained by greedy algorithms are used as an initial approximation for further op-timization of the target function.
8. Development of the concept of data migration between relational and non-relational database systems [№4 за 2019 год]
Authors: Yu.A. Koroleva, V.O. Maslova, V.K. Kozlov
Visitors: 994
The article investigates relational and non-relational approaches to constructing, storing, and extracting data. Nowadays all information and analytical systems use databases. These systems require the ability to process, read, write specific data sets that need to be organized, structured and stored. Finding a suitable database and database management system is one of the most common problem for many companies, as this choice will determine performance, reliability, security, design features and other work features. Usually several data mod-els can be used in one information system of a company. For example, companies use a relational database for the tasks that re-quire using full data consistency and transaction control, whereas analytical, aggregated or meta-data can be kept in a NoSQL database. This separation is often necessary for the most effective functioning of the final product. Combining these systems is the main problem. The research discovered the most popular database management systems for both approaches of developing databases. Their advantages and disadvantages are analyzed. As the first phase of data preparation for transparent migration between two systems, the authors propose the transformation scheme from relational data to non-relational data. This scheme is based on the databases internal organization and their peculiar properties.
9. Energy consumption management in data storage process when choosing the size of a data physical block [№4 за 2019 год]
Authors: T.M. Tatarnikova, E.D. Poymanova
Visitors: 965
The papers considers the function hierarchy of data storage at a physical level. At the first level, there are functions to maintain a steady state of minimum data storage units. The number of stable states of data storage minimum unit affects the number of stored data bits. It is shown that minimum data storage units differ depending on the file type and the medium type. There is an expression that allows estimating the minimum energy required to convert a minimum storage unit. At the second level, there are functions to combine the minimum units of data storage into physical data blocks. The paper shows the structure of a physical unit. There is an example of changing a physical block size. It demonstrates the possibility of adjusting a physical block size depending on the stored information type and requirements for the storage system. When a phys-ical block increases, the metadata stored in a medium decreases, and thus the efficiency of using the media capacity increases. At the third level, there are functions to unite the physical blocks into logical data blocks. The logical block size depends on the capabilities of the installed file system and is set when formatting. At the file level, there is addressing of data bits, physical and logical blocks, thereby the data bits are logically combined into a file. The paper presents the results that demonstrate a sig-nificant reduction in energy consumption with a data block size increase and a metadata volume decrease compared to energy consumption when maintaining the original file.
10. Problems of an information survey as the main stage of development of automated control systems [№4 за 2019 год]
Authors: O.V. Sayapin, Tikhanychev O.V., S.V. Chiskidov , M.O. Sayapin
Visitors: 1537
The paper considers the problems of organizing an information survey, as the initial stage of creating an automated control sys-tem. This stage is most important in the development of automated control systems. It should provide a description of the analy-sis of an information and functional content of existing management processes in the form of a functioning model of the organ-izational and technical system under consideration. Such description should contain a system of detailed structured descriptions of all functional subsystems, processes, functions and tasks of officials of the automated system, as well as a description of a composition, content, circulation and requirements for processing documents in each automated process. The developed func-tional model provides the initial level of formalized descriptions of the considered processes, which presents and correlates with time all tasks and related documents. It should be a basis of forming a management process information model containing the combined, harmonized and standardized presentation of data required for all categories of officers of the organizational and technical system. According to domain analysis, the initial stage of creating a system (research and development rationale) is for setting the basic parameters of its further development. Existing approaches to the informational survey, which are focused on paper-and-pencil technologies, do not provide the proper quality of the formation of an automated system information model and a relia-ble basis for further work. At the same time, there is a fairly wide range of tools and methods to ensure the development of management automation tools, including tools for creating functional and information models. The paper proposes ways to solve the problem of the information survey of an automation object by consistently constructing a functional and information model of an organizational and technical system using the capabilities of modern information technologies. The paper proposes to finalize regulatory documents on the development of automated control systems for the implementa-tion of the proposed principles. In particular, taking into account another important factor in the process of management auto-mation – the mutual influence of the control system structure and automation tools introduced into it. As the practical experi-ence shows that these measures can significantly improve the efficiency of automated systems development.
| 1 | 2 | 3 | Next → ►