articles
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№ 4(94)
31 august 2021 year
Rubric: Processes and systems modeling Authors: Kavchenkov V., Chernenkov I., Kavchenkova E. |
The actual problem of an adequate mathematical description of the world development global processes trends is studied on the example of the Earth population growth and the production (consumption) of the electric energy. Various models used to describe the past, present and future of the various processes in nature, technology and economics are considered. It is shown that these processes are well described by the equations obtained during solving differential models with exponentially growth rates decaying in time. These models take into account the currently accepted doctrine of sustainable development of the world system using energy saving technologies, preserving environmental safety and using renewable energy sources. The similarity of the studied global processes and the possibility of their description by one criterion equation are established. At the same time their dynamics is characterized by different speeds. The first period is characterized by a rapid growth. After the inflection point the growth rates slow down but the volumes increase significantly and a gradual saturation occurs. The influence of the model parameters on the character of the studied processes on the phase plane is estimated which significantly simplifies their analysis. It is shown that the process of the world population growth passed the inflection point in 1990 and is 29 years ahead of the world electricity production growth. But the growth rates of electricity production and its consumption per capita are significantly higher. Thus, new mathematical models are proposed to describe the dynamic series of the Earth population growth, world production and electric energy consumption per capita. The obtained mathematical models have been in good agreement with statistical data for 60 years since 1960 and have high values of the determination coefficient. The studied processes prediction for the long-term period up to 2050 was made with their help. The results of the prediction do not contradict the results of other authoritative studies using the global processes inertial development model. Continue... |
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№ 4(94)
31 august 2021 year
Rubric: Researching of processes and systems Authors: Blinov A., Borisov A., Konchina L., Kulikova M., Maslova K. |
A two-link model of exoskeleton with variable-length links for supporting the lower limbs of the human musculoskeletal system is proposed in the article. The researched model differs from the existing ones by the variable-length links, and by the angle calculation method. While in the existing models, the angles are calculated from the regular direction – from vertical, or from horizontal, – in the proposed research they are calculated between the links. As for practical exoskeleton implementation, the proposed method of angle calculation is appropriate to the actual working conditions of the electrical motors with the reduction gears installed in the hinges, which change the angles between the links. The construction of a variable-length exoskeleton link consists of two absolutely solid weighty sections located at both ends of the link and one weightless section between them in the center of the link. In the weightless section, there is a drive that creates a control longitudinal force, which realizes the increase or decrease in the length of the link in the required manner and provides the necessary maintenance of the length of the link when the person moves in the exoskeleton. The links are connected to each other using spherical hinges. Drives are installed in each hinge, creating control torques, which provide a relative rotational movement of the links. The jointly controlling longitudinal forces and moments realize the maintenance of the posture or the movement of the link in the required manner and, in relation to the exoskeleton, the repetition of the basic biomechanical properties of the human musculoskeletal system. The mathematical model in the form of the system of Lagrange differential equations of the second kind is obtained. The obtained mathematical model is examined for existence and uniqueness of the Cauchy solution. The kinematic trajectory of the link motion has been synthesized, which simulates the anthropomorphic movement of the supporting leg during the single-support phase of movement, and the control actions required for its implementation has been found. The significance of the results obtained in the process of modeling lies in the ability to create active exoskeletons, prostheses in medicine, anthropomorphic robots, and spacesuits that take into account the biomechanical features of the functioning of the human musculoskeletal system. Continue... |
| The modern system of industrial risk management at enterprises is based on the basic principles laid down in the standards of industrial safety and labor protection, and presupposes, basically, long-term precedent risk management - responding to their occurrence, analyzing the results, and taking measures to reduce risks. At the same time, with rare exceptions, the management of extremely rapidly developing risk situations, carried out in the course of their development, remains outside the brackets. For example, the failure of some machine tools, or their parts, can be predicted in advance by the parameters of their operation (the nature and level of noise, vibration, temperature parameters, etc.). Previously, the management of such risk situations was complicated by the lack or high cost of automated systems capable of responding with the required delays. The features of risk management of extremely rapidly developing risk situations are considered. A comparative analysis of modern message brokers suitable for building intelligent risk management systems in conditions of uncertainty has been carried out. The architecture of software tools for intelligent risk management in conditions of uncertainty based on the Apache Kafka message broker is proposed. A comparative analysis of the implementation of fuzzy data processing based on Kafka Streams within Apache Kafka and a separate application outside Apache Kafka is carried out, an estimate of the load generated by such software is obtained. Continue... | |
| The development of the digital economy in the modern world requires solving the issue of security of Industrial Internet of Things (IIoT) applications. A large number of distributed, network-based, IIoT devices managed by intelligent programs (software agents) require protection. A successful attack on any IIoT device will lead to hacking of the IIoT application and to large financial losses, as well as to the termination of the IIoT application, therefore, the research topic is relevant. The purpose of this article is to radically solve the security problem of the IIoT application by developing a blockchain architecture of the application. The authors were tasked with investigating all aspects of the blockchain system that ensure the security of IIoT application devices. The peculiarity of the blockchain system is that its participants are software agents that control the application devices. As a result of the research, the concept of the blockchain architecture of the IIoT application is proposed. He mechanisms of consensus of intelligent programs of IIoT devices as equal active participants of the blockchain network are investigated. The consensus mechanism and the cryptographic system of the distributed registry of the blockchain network increase the information security of the IIoT application. The synergistic effect of the blockchain system and intelligent systems of software agents of IIoT application devices significantly increases the efficiency of the solution. Intelligent systems of software agents and IIoT applications are effectively trained on the blockchain platform, and as a result, we get a decentralized supercomputer in the form of a blockchain system. Continue... | |
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№ 5(95)
31 october 2021 year
Rubric: Models and methods Authors: Kychkin A., Gorshkov O. V., Pavlov V., Selivanov V. |
The development of application software for cyber-physical systems of buildings involves the widespread use of Internet of Things (IoT) integration platforms. In practice, the flexible functionality of IoT platforms often leads to additional costs for software enhancement of existing and connection of new units, in particular digital twins. The paper proposes a technological solution for the implementation of a digital twin of the ventilation process in the IoT control loop of heating, ventilation and air conditioning (HVAC) systems for buildings and industrial facilities. The implementation and execution of the digital twin in the form of a dynamic simulation model in the object-oriented modelling language Modelica in the OpenModelica environment is considered. The IoT platform InfluxData, based on the TICK stack, is considered as an example of an integration environment. It is a horizontally-oriented IoT platform that contains the mechanism for collecting data from devices and the InfluxDB time-series database for storing metrics. To integrate simulation models on Modelica with InfluxDB, an OMPython server is proposed. In this case, the integration scripts are executed in the Python language, which as a result extends the traditional capabilities of the IoT platform significantly to the level of a digitally twinned control system. This HVAC control involves adapting control loops by taking into account the dynamics of the air distribution process over the ventilation network, evaluating and compensating for process inertia. The publication was prepared within the framework of the Academic Fund Program at the HSE University in 2020–2021 (grant № 21-04-039). Continue... |
| The issues of ensuring the financial stability of financial institutions, which is understood as the sufficiency of assets to meet obligations, are of paramount importance both for clients and the management of a financial institution, and for the country's economy as a whole. Most often, the inability to fulfill obligations is associated with a lack of funds, therefore it is important to monitor the dynamics of the monetary capital of organizations, to assess their financial risks, including in the conditions of investment. Purpose of the study: development of tools for assessing the risks of financial organizations. Statement of the problem: to develop a simulation model that allows one to study the dynamics of the capital of an organization, whose financial resources are formed due to heterogeneous flows of inflow and outflow of funds and investment, including in risky assets, in an inflationary environment. The paper proposes a modeling algorithm that allows to collect a descriptive statistics on the distribution of financial resources, to estimate the dynamics of the money capital of financial organizations and investigate the "sufficiency" of the company's funds to meet financial obligations basing on data of cash flows for various types of contracts and returns (growth rates) of assets, presented in the form of statistical data and/or characteristics of time series models. The description of the software tool is given. A computational experiment was based on data of the inflow and outflow of funds of a non-state pension Fund under the program of non-state pension provision. Descriptive statistics are given for the distributions of the size of organization's funds constructed as a result of modeling. The probability of organization’s downfall in dynamics and the risk of entering the zone of financial insecurity are assessed. The proposed tools have scientific novelty in the field of designing simulation models and decision support systems for analyzing the activities of financial organizations and determining effective directions for their development. Continue... |
