bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of risk concept for technical systems using digital twins
Authors: Лепихин Анатолий Михайлович , Махутов Николай Андреевич , Шокин Юрий Иванович , Юрченко Андрей Васильевич 
Published: August 2021

Рассмотрены основные методологические аспекты анализа рисков технических систем с использованием цифровых двойников. Сформулирована концепция рисканализа и предложена базовая модель для ее реализации. Рассмотрены информационные аспекты анализа неопределенностей модели риска. Показано, что технологии цифровых двойников позволяют эффективно сочетать результаты компьютерного моделирования с данными мониторинга реальных объектов, обеспечивая более глубокий анализ объектов, с учетом множества вариантов конструкции, технологий и условий эксплуатации
Development of technology and technical systems significantly increases in the volume of information. Traditional methods for designing, manufacturing and operating of technical systems do not allow processing such volumes of information. In this regard, the modern strategy for creating technical systems is based on the use of digital twins. Solving the problems of risk analysis and risk management for technical systems at all stages of the life cycle appears to be one of the promising areas for application of the digital twins technology. Despite of active research, using digital twins in risk analysis currently do not have appropriate methodological justifications and technical solutions in a number of key aspects. In particular, effective reductions of the order of risk models and quantifying uncertainty factors of various types have not been solved. The concept of the risk-informed decision making in product lifecycle management has not been implemented. In fact, there are very few publications on the risk analysis and risk management methodology using digital twins. The article discusses the main methodological aspects of risk analysis of technical systems using digital twins. The concept of risk analysis is formulated and a basic model for its implementation is proposed. The informational aspects of the analysis of uncertainties of the risk model are considered. It is shown that digital twin technologies allow effective combination of the results of computer modelling with the data monitoring of real objects, providing a deeper analysis of objects, taking into account a variety of design options, technologies and operating conditions.
Two-dimensional model of wave hydrodynamics with high accuracy dispersion relation
Authors: Хакимзянов Гаяз Салимович , Федотова Зинаида Ивановна , Дутых Денис 
Published: August 2021

Полностью нелинейная слабо дисперсионная модель волновой гидродинамики, учитывающая подвижность дна, модифицирована с целью повышения точности дисперсионного соотношения. Проведено сравнение с известными аналогичными моделями и выявлено различие в асимптотическом поведении их фазовых скоростей.
Application of nonlinear dispersion wave hydrodynamics (NLD-) models for solving practical problems constantly stimulates the search for ways to expand their field of applicability and achieve a more accurate reproduction of the characteristics of the simulated processes. A productive step in this direction turned out to be the method proposed by Madsen & Sørensen (1992), which made it possible to increase the approximation order of the dispersion relation of the Peregrine model while preserving the third order of derivatives included in the original equations and the second order of long-wave approximation. Later, other approaches were proposed to achieve this goal, which had a noticeable effect on expanding the field of applicability of NLD-models (for example, Nwogu (1993), Beji & Nadaoka (1996)). In the present work, we set a similar goal - to improve the properties of the dispersion relation of the model (and, therefore, the phase velocity), providing the Pade approximation (2,2) of the dispersion relation of the 3D model of potential flows. In contrast to earlier works on this subject, where weakly non-linear models were considered, we proceed from the fully nonlinear weakly dispersive two-dimensional Serre - Green - Naghdi (SGN-) model. The novelty of the proposed method consists in modifying the formula for the non-hydrostatic part of the pressure, while the accuracy of the long-wave approximation is preserved. It is shown that in some special cases the obtained fully nonlinear model is close to the known models (for example, after appropriate simplification it coincides with the model from Beji & Nadaoka (1996)). A dispersion analysis was performed one of the results of which was the conclusion that for sufficiently long waves the approximation order of the dispersion relation of the 3D model increases from the second to the fourth and an improvement was also achieved for more short waves. The proposed modification of the SGN-model is invariant with respect to the Galilean transformation; the law of conservation of mass and the law of balance of the total momentum are satisfied. However, the law of conservation of total energy is not satisfied. Apparently all NLD-models with improved dispersion characteristics possess this negative quality.
Numerical solution of the problem of the gas compression from rest to rest
Authors: Баутин Сергей Петрович , Николаев Юрий Владимирович 
Published: August 2021

Представлены результаты численного решения математической модели перевода под действием двух поршней одномерного слоя газа из одного состояния покоя (начальный момент) в покой с большим значением плотности (финальный момент). Один из поршней движется со стороны оси или центра симметрии в сторону второго неподвижного поршня. Приводятся конкретные значения масс газа и его плотностей в финальный момент, сжатие которых возможно безударным способом. Траектория сжимающего поршня получена в виде табличной зависимости. Алгоритм численного решения реализован на основе метода характеристик и использует свойство решения, что на сжимающем поршне в финальный момент сжатия возникает особенность. В особой точке решение описывается формулами центрированной волны Римана, а в ее окрестности - обобщением центрированной волны Римана.
There is a flat, cylindrical or spherical layer homogeneous polytropic gas. One-dimensional and isentropic flows described by solutions of a system of gas dynamics. Let the gas be homogeneous at the initial moment of time with the density 1, and the gas velocity equal to 0 (state 1). At the final point in time the gas is again homogeneous with density large then 0 and rests (state 2). Purpose: It is need to find the gas flows that occur when a one-dimensional gas layer is shock-free compressed from the state 1 to the state 2. Methodology. In [1] was prove the existence of a solution to the problem of compression from rest to rest. To do this, the task is reduced to three initial boundary value problems. For this task the existence and uniqueness theorems of the solution are proved. In the proof of the theorems in particular, it is found that the solution has a feature on the compression piston in the final moment of compression, which at the point itself is described by the centered formula Riemann waves, and in its vicinity a generalization of the centered Riemann wave. Thus in theorems received a positive answer to the question about the existence of a solution (it can be written out in the form of an infinite series) in some area. However, theorems was not give answer about size of the solution area: no specific mass and density values were specified gas that can be compressed in the appropriate shock-free manner. In [2], the problem was solved numerically for the case of shock-free compression one-dimensional gas layer when the compression piston moves from the outside towards the axis or center symmetries. Findings. In the current work, the problem is numerically solved for the case of compression by a moving piston from inside to external stationary wall. The solution is obtained using its known properties and the method of characteristics. When numerical constructing there were no intersections of characteristics of the same family, which allows us to assert that the absence of shock waves in compression-induced flows. For specific mass values and the gas density trajectory of the compression piston was obtained in the form of table dependencies.
The application of artificial intelligence and data compression techniques for forecasting of social, economic and demographic indicators of the Novosibirsk region
Authors: Чирихин Константин Сергеевич , Рябко Борис Яковлевич 
Published: August 2021

Рассмотрена задача прогнозирования временных рядов в ее одно- и многомерной постановках. Описан метод прогнозирования, в основе которого лежат алгоритмы сжатия данных и искусственного интеллекта. В качестве примера практического применения этого метода приведены вычисления для некоторых социальных, демографических и экономических показателей Новосибирской области. Наряду с широко используемыми на практике программами для сжатия данных, использованы реализации относительно менее известных моделей на основе формальных грамматик, а также метода, основанного на конечных автоматах. Для прогнозных значений построены доверительные интервалы.
This paper describes and experimentally investigates a time series forecasting method based on data compression and artificial intelligence techniques. Its basic idea is to combine various algorithms that can estimate the compressed size of a sequence of discrete values into a single method of forecasting. Generalizations of the method to continuous and multivariate cases are described. We use several popular data compression libraries (zlib, bzip2, ppmd), as well as applications of relatively lesser-known algorithms based on formal grammars (re-pair) along with our implementation of an algorithm based on finite automata with multiple heads. All these are employed to make forecasts for some social, economic and demographic indicators of the Novosibirsk region. The article elaborates both our methodology and the methods used for data preprocessing. Confidence intervals with a confidence level of 0.95 are plotted for all predicted values; the average relative errors calculated from the results of predicting the already fixed values are given. Cases in which multivariate forecasting turned out to be more accurate than univariate forecasting are: 1. Average annual population and natural population growth in the Novosibirsk region. Figure 1 shows their graphs along with multivariate predictions, while confidence intervals and mean relative errors are presented in tables 1, 2. 2. Life expectancy and number of deaths in the Novosibirsk region. Figure 2 shows their graphs along with multivariate predictions, confidence intervals and mean relative errors are presented in tables 3, 4. Table 5 gives univariate forecasts of some other indicators of the Novosibirsk region. We think that the results of computations show that the proposed method is capable of finding non-trivial patterns in the data and can be used in practice.
Towards verification of scientific and engineering programs. The CPPS project
Authors: Кондратьев Дмитрий Алексеевич , Промский Алексей Владимирович 
Published: August 2021

В настоящее время, когда теоретические основы верификации программ хорошо изучены, исследователи концентрируют свои усилия на предметно-ориентированных методах для различных классов программ. Инструменты, которые они выбирают, варьируются от проверки моделей для сетевых протоколов до исчислений указателей для фрагментов ядра операционной системы. Однако, похоже, что области научных и инженерных программ все еще уделяется недостаточно внимания. Мы хотели бы внести свой вклад в заполнение этого пробела с помощью разработки системы CPPS. Целью этого проекта является создание системы параллельного программирования для Sisal-программ. Дедуктивная верификация Sisal-программ является одной из важных подцелей. Так как язык Cloud-Sisal построен на основе циклических выражений, их аксиоматическая семантика является базой логики Хоара для языка Sisal. Циклические выражения языка Cloud-Sisal, выражения конструирования массивов и выражения замещения элементов массивов позволяют реализовать эффективно исполняемые программы вычислительной или инженерной математики. Таким образом, мы полагаем, что наша аксиоматическая семантика для этих типов выражений может представлять интересный результат. Природа таких программ позволяет достичь не только эффективного исполнения, но и упростить верификацию. Действительно, программы вычислительной математики часто основаны на итерациях над структурами данных. Символический метод верификации финитных итераций является в этой ситуации очень полезным, так как он элиминирует те проблемные инварианты цикла, которые всегда мешают формальной верификации. Все предыдущие исследования этого метода были теоретическими, CPPS представляет собой первую попытку использования его на практике.
Nowadays, when formal fundamentals of program verification are well studied, researchers concentrate their efforts on domain-specific methods for various classes of programs. However, it seems that the field of scientific and engineering applications still lacks attention. We would like to contribute to filling this gap through the development of the Cloud Parallel Programming System (CPPS). The goal of this project is to create a parallel programming system for Sisal programs. Deductive verification of Sisal programs is one the of important subgoals. Since the Cloud Sisal language is built on the basis of loop expressions, their axiomatic semantics is the basis of Hoare’s logic for the Sisal language. The Cloud Sisal loop expressions, array construction expressions and array element replacement expressions enable efficiently executable computational or engineering mathematics programs. Thus, we believe that our axiomatic semantics for these types of expressions may present an interesting result.
Information theory as a means of determining the main factors affecting the processors architecture
Authors: Ракитский Антон Андреевич , Рябко Борис Яковлевич 
Published: August 2021

В работе исследуется процесс разработки компьютеров за последние десятилетия с целью определения наиболее влияющих на него факторов. Описываются сами факторы, которые используются для предсказания направления будущих разработок. Для решения этой задачи применяется концепция Вычислительной Способности, которая позволяет оценить производительность компьютеров теоретически, опираясь исключительно на описание их архитектуры.
In this article we are investigating the computers development process in the past decades in order to identify the factors that influence it the most. We describe such factors and use them to predict the direction of further development. To solve these problems, we use the concept of the Computer Capacity, which allows us to estimate the performance of computers theoretically, relying only on the description of its architecture.
Modelling of a rotating detonation engine combustion chamber
Authors: Михальченко Елена Викторовна , Никитин Валерий Федорович , Стамов Любен Иванович , Филиппов Юрий Григорьевич 
Published: August 2021

Рассмотрено трехмерное численное моделирование камеры сгорания двигателя с непрерывной детонационной волной с помощью авторского программного пакета. Программное обеспечение использует для многокомпонентного химически реактивного газа математическую модель с опциональным подключением модели турбулентности. В основе модели химической кинетики лежит механизм элементарных реакций, в зависимости от механизма меняется число реакций. В программе, в том числе, реализован авторский кинетический механизм. Рассмотрены шесть кинетических механизмов: Мааса-Варнаца-Поупа, Хонга, Вильямса, Gri-Mech 3.0, Ли-Джоу-Казакова-Драера и авторский, проведено их сравнение. Код распараллелен с помощью технологий OpenMP и MPI. В результате работы программы получена оптимальная форма камеры сгорания с самоподдерживающейся детонационной волной на смеси водорода с кислородом.
Purpose. To create software for studying the features of the transition from ignition and deflagration to a detonation mode in a three-dimensional configuration, including the formation and propagation of a rotating detonation complex, which takes transient processes into account. Methodology. The software is based on a mathematical model for multi-component gas dynamics with chemical reactions and turbulent transport for diffusion, viscosity, and thermal conductivity. High-order calculation schemes are used. To solve a stiff subsystem of kinetic equations, a hybrid implicit-explicit Novikov method is used (a specific variant of a Rosenbrock method). Findings. Authors created a code which calculates physical processes within a multi-component gas dynamics paradigm. The code accounts for chemical processes and turbulence modelling. The shape of computation domain and the type of boundary conditions is user defined. These include boundary conditions at the wall, as well as inflow and outflow conditions for both subsonic, and supersonic modes. Initial conditions can be set up differently in different regions of the domain. The software consists of several modules: a mesh-building module, initial state creation, calculation of new time layers saving the intermediate and final results at control points with a possibility to resume interrupted calculations, and post-processing modules. Authors developed blocks of solutions for various elementary chemical kinetic mechanisms, one of considered mechanisms is build up by themselves, others are published previously. It was obtained that the details of the 3D transient problem solution significantly depend on the chosen mechanism. Оriginality/value. The software complex makes it possible to process numerical modelling of a detonation engine combustion chamber in a 3D configuration considering chemical reactions and turbulent transport. Different chemical kinetics mechanisms are utilizable, and thrust characteristics could be obtained.
Computer 2D modelling of a micro-grip fluid cooling system
Authors: Насибуллаев Ильдар Шамилевич , Даринцев Олег Владимирович 
Published: August 2021

Представлено компьютерное численное моделирование системы жидкостного охлаждения камеры микрозахвата. Построены математические модели течения жидкости, переноса тепла жидкостью, теплообмена между жидкостью и радиатором, теплообмена между радиатором и элементом Пельтье. Определено влияние геометрических и физических параметров камеры микрозахвата на эффективность системы охлаждения, а также найдена зависимость максимальной температуры, установившейся на радиаторе, от скорости течения охлаждающей жидкости и коэффициента теплопередачи между радиатором и жидкостью для стационарного течения. Проведено исследование влияния нестационарного течения жидкости на колебания температуры радиатора. На основе результатов численного моделирования предложены простые аналитические формулы, которые можно использовать в программном обеспечении системы управления микрозахватом
Numerical simulation of a micro-grip chamber fluid cooling system is presented. The mathematical models for mass and heat transfer in a fluid, heat exchange between the fluid and the radiator as well as the heat exchange between the radiator and the Peltier element are constructed in a variational form. The equations of hydrodynamics and heat equations were simulated by the finite element method in the FreeFem++ software. The influence of the geometric and physical parameters of the cooling system chamber on the efficiency of the device is determined. It is shown that as the heat transfer coefficient between the radiator and the fluid and the velocity of the coolant increases, the maximum steady-state temperature on the radiator nonlinearly decreases with saturation. When flow of coolant oscillates then the temperature on the radiator so does with the flow frequency. As the flow frequency increases, the amplitude of temperature fluctuations decreases. The increasing amplitude of flow oscillations leads to the amplification of the temperature amplitude. Using orthogonal central compositional method, the influence of the parameters (heat transfer coefficient, fluid velocity) on the efficiency of the cooling system is found, and the contribution of pairwise interaction is determined. Based on the results of numerical modelling, simple analytical formulas are proposed that can be used in the software module of the micro-grip cooling control system.
Two-dimensional model of wave hydrodynamics with high accuracy dispersion relation. II. Fourth, sixth and eighth orders
Authors: Хакимзянов Гаяз Салимович , Федотова Зинаида Ивановна , Дутых Денис 
Published: August 2021

Построена полностью нелинейная слабо дисперсионная модель волновой гидродинамики четвертого порядка длинноволновой аппроксимации. За скорость в модели взята усредненная по глубине горизонтальная составляющая скорости трехмерного течения. Учтена подвижность дна. Выполненная модификация модели обеспечивает шестой и восьмой порядки точности аппроксимации дисперсионного соотношения трехмерной модели потенциальных течений.
In the numerical simulation of medium-length surface waves in the framework of nonlinear dispersive (NLD) models, an increased accuracy of reproducing the characteristics of the simulated processes is required. A number of works (Kirby (2016), e.g.) describe approaches to improve the known NLD-models. In particular, NLD-models of the fourth order of the long-wave approximation have been proposed and, based on a comparison of numerical results with experimental data, their high accuracy has been demonstrated (Ataie-Ashtiani and Najafi-Jilani (2007); Zhou and Teng (2010)). In these new models, the horizontal component of the velocity vector of the threedimensional (FNPF-) model of potential flows at a certain surface located between the bottom and the free boundary was chosen as the velocity vector. The result was a very cumbersome form of equations. In addition, the laws of conservation of mass and momentum do not hold for these models. The main result of this work is the derivation of a two-parameter fully nonlinear weakly dispersive (mSGN4) model of the fourth order of the long-wave approximation, which is a generalization of the well-known Serre-Green-Naghdi (SGN) second order model. In the derivation, the velocity averaged over the thickness of the liquid layer was used. The assumption about the potentiality of the three-dimensional flow was used only at the stage of closing the model. The movement of the bottom is taken into account. For the derived model, the law of conservation of mass is satisfied, and the law of conservation of total momentum is satisfied in the case of a horizontal stationary bottom. The equations of the mSGN4-model are invariant under the Galilean transformation and are presented in a compact form similar to the equations of gas dynamics. The dispersion relation of the mSGN4-model has the fourth order of accuracy in the long wave region and satisfactorily approximates the dispersion relation of the FNPF-model in the short wave region. Moreover, with a special choice of the values of the model parameters, an increased accuracy of approximating the dispersion relation of the FNPF-model at long waves (sixth or eighth order) is achieved. Analysis of the deviations of the values of the phase velocity of the mSGN4 model from the values of the “reference” speed of the FNPF model in the entire wavelength range showed that the most preferable is the mSGN4 model with the parameter values corresponding to the Pad’e approximant (2,4).