POWER SHELL ELEMENTS: DYNAMIC MATHEMATICAL MODELS, POWER SYSTEMS (OVERVIEW) Continuation

2021 ◽  
pp. 36-43
Author(s):  
Pavel P. Chernus ◽  
A. K. Arbiev ◽  
Petr P. Chernus ◽  
P. A. Loshitskiy ◽  
V. T. Sharovatov
Keyword(s):  
Power Systems ◽  
Mathematical Models ◽  
Gas Flow ◽  
Transfer Functions ◽  
Theory And Practice ◽  
Design Stage ◽  
Shell Elements ◽  
Advantages And Disadvantages ◽  
Working Medium ◽  
Compressed Gas

This article is a review devoted to the theory and practice of the application of power shell elements (PSE) in pneumatic drives (PD). She makes acquaint the reader with the main provisions of the theory of PD, performed on the PSE. The review briefly presents materials on the development of dynamic mathematical models (DMM) of power units (PU) of shell PDs (SPD), based on the use of static characteristics of SPD, an assessment of the advantages and disadvantages of PU based on traditional pneumatic cylinders (PC) and PSE is given. The main attention in the review is paid to the solution of the problem of creating PU on PSE with the required quality indicators at the design stage, when it is necessary to take into account the properties of compressed gas. For this, an original methodology for the development of nonlinear DMMs for various typical variants of the midrange is proposed, the basis of which is a number of provisions of the theory of gas dynamics. Without invoking this theory, it is impossible to take into account the properties of compressed gas (compressibility of the working medium, dependence on temperature and gas flow rate in the shell, the nature of the gas expansion processes), and, therefore, to reliably describe the state of unsteady gas processes inside the shell and develop a DMM of the PU, to a sufficient taking into account the mentioned properties. Since the topic of this review is intended mainly for engineers who develop SPD (theoreticians and practitioners), the review also contains materials on the linearization of the found nonlinear DMMs. As a result of linearization, nonlinear DMMs are transformed into transfer functions for displacement of the output coordinate and effort. The correctness of the linearization carried out is confirmed by the results of experiments. The review briefly discusses several options for pneumatic supply systems for SPD. Here, of particular interest for a specialist is the material on imparting invariance properties to SPDs to air intake from the atmosphere and discharge of exhaust air into the atmosphere, which significantly expands the scope of SPDs and reduce their cost.

POWER SHELL ELEMENTS: DYNAMIC MATHEMATICAL MODELS, POWER SYSTEMS (OVERVIEW)

2021 ◽  
pp. 31-39
Author(s):  
Pavel P. Chernus ◽  
A. K. Arbiev ◽  
Petr P. Chernus ◽  
P. A. Loshitskiy ◽  
V. T. Sharovatov
Keyword(s):  
Power Systems ◽  
Mathematical Models ◽  
Gas Flow ◽  
Transfer Functions ◽  
Theory And Practice ◽  
Design Stage ◽  
Shell Elements ◽  
Advantages And Disadvantages ◽  
Working Medium ◽  
Compressed Gas

This article is a review devoted to the theory and practice of the application of power shell elements (PSE) in pneumatic drives (PD). She makes acquaint the reader with the main provisions of the theory of PD, performed on the PSE. The review briefly presents materials on the development of dynamic mathematical models (DMM) of power units (PU) of shell PDs (SPD), based on the use of static characteristics of SPD, an assessment of the advantages and disadvantages of PU based on traditional pneumatic cylinders (PC) and PSE is given. The main attention in the review is paid to the solution of the problem of creating PU on PSE with the required quality indicators at the design stage, when it is necessary to take into account the properties of compressed gas. For this, an original methodology for the development of nonlinear DMMs for various typical variants of the midrange is proposed, the basis of which is a number of provisions of the theory of gas dynamics. Without invoking this theory, it is impossible to ta into account the properties of compressed gas (compressibility of the working medium, dependence on temperature and gas flow rate in the shell, the nature of the gas expansion processes), and, therefore, to reliably describe the state of unsteady gas processes inside the shell and develop a DMM of the PU, to a sufficient taking into account the mentioned properties. Since the topic of this review is intended mainly for engineers who develop SPD (theoreticians and practitioners), the review also contains materials on the linearization of the found nonlinear DMMs. As a result of linearization, nonlinear DMMs are transformed into transfer functions for displacement of the output coordinate and effort. The correctness of the linearization carried out is confirmed by the results of experiments. The review briefly discusses several options for pneumatic supply systems for SPD. Here, of particular interest for a specialist is the material on imparting invariance properties to SPDs to air intake from the atmosphere nd discharge of exhaust air into the atmosphere, which significantly expands the scope of SPDs and reduce their cost.

A Discussion on recent advances in heavy electrical plant - A review of the development of the vacuum interrupter

1973 ◽  
Vol 275 (1248) ◽  
pp. 121-129 ◽  
Keyword(s):  
Power Systems ◽  
Future Development ◽  
Reasonable Agreement ◽  
Theory And Practice ◽  
High Current ◽  
Physical Processes ◽  
Vacuum Interrupter ◽  
Advantages And Disadvantages ◽  
Recent Advances ◽  
Properties Of Materials

The basic physical processes occurring in vacuum arcs are described, and it is shown that reasonable agreement exists between theory and practice as to the interrupting ability to be expected of vacuum interrupters. Designs of interrupters and contacts for both low and high current applications are reviewed, together with the properties of materials required. The advantages and disadvantages of this method of circuit interruption in power systems are discussed, together with the present applications of these interrupters. Finally, an attempt is made to predict the pattern of future development of interrupters and of their applications.

Classification of Vortex Jet Devices for Gas Flow Control in Pneumo-Hydraulic Systems

2020 ◽  
pp. 43-58
Author(s):  
A.Y. Uss ◽  
A.V. Chernyshev
Keyword(s):  
Flow Control ◽  
Gas Flow ◽  
Vortex Flow ◽  
Hydraulic Systems ◽  
Advantages And Disadvantages ◽  
Working Medium ◽  
Functional Features ◽  
Technical Solutions ◽  
First Time

This article presents a review and analysis of the literature on the development and study of vortex jet devices that are used as control valves employing the principle of the vortex flow of the working medium. The article discusses vortex valves without mechanically moving parts, as well as semi-mechanical vortex valves. The principle of operation of a vortex jet device is described and, for the first time, a classification of vortex jet devices by a number of structural and functional features is carried out. The analysis of technical solutions identifies the advantages and disadvantages of vortex jet devices. Recommendations are given for selecting a structure diagram of a vortex jet device.

Review of classification studies for machine learning in the development of intelligent management decision support systems

2020 ◽  
Vol 89 ◽  
pp. 20-29
Author(s):  
Sh. K. Kadiev ◽  
◽  
R. Sh. Khabibulin ◽  
P. P. Godlevskiy ◽  
V. L. Semikov ◽  
...  
Keyword(s):  
Machine Learning ◽  
Decision Support ◽  
Mathematical Models ◽  
Decision Support Systems ◽  
Support Systems ◽  
Management Decision ◽  
Classification Methods ◽  
Advantages And Disadvantages ◽  
Intelligent Management ◽  
Management Decision Support

Introduction. An overview of research in the field of classification as a method of machine learning is given. Articles containing mathematical models and algorithms for classification were selected. The use of classification in intelligent management decision support systems in various subject areas is also relevant. Goal and objectives. The purpose of the study is to analyze papers on the classification as a machine learning method. To achieve the objective, it is necessary to solve the following tasks: 1) to identify the most used classification methods in machine learning; 2) to highlight the advantages and disadvantages of each of the selected methods; 3) to analyze the possibility of using classification methods in intelligent systems to support management decisions to solve issues of forecasting, prevention and elimination of emergencies. Methods. To obtain the results, general scientific and special methods of scientific knowledge were used - analysis, synthesis, generalization, as well as the classification method. Results and discussion thereof. According to the results of the analysis, studies with a mathematical formulation and the availability of software developments were identified. The issues of classification in the implementation of machine learning in the development of intelligent decision support systems are considered. Conclusion. The analysis revealed that enough algorithms were used to perform the classification while sorting the acquired knowledge within the subject area. The implementation of an accurate classification is one of the fundamental problems in the development of management decision support systems, including for fire and emergency prevention and response. Timely and effective decision by officials of operational shifts for the disaster management is also relevant. Key words: decision support, analysis, classification, machine learning, algorithm, mathematical models.

scholarly journals A Novel Methodology for Adaptive Coordination of Multiple Controllers in Electrical Grids

Mathematics ◽  
2021 ◽  
Vol 9 (13) ◽  
pp. 1474
Author(s):  
Ruben Tapia-Olvera ◽  
Francisco Beltran-Carbajal ◽  
Antonio Valderrabano-Gonzalez ◽  
Omar Aguilar-Mejia
Keyword(s):  
Power Systems ◽  
Power System ◽  
Electric Power ◽  
Large Scale ◽  
Short Circuit ◽  
Dynamic Performance ◽  
Low Frequency ◽  
Electric Power System ◽  
Design Stage ◽  
Positive Interaction

This proposal is aimed to overcome the problem that arises when diverse regulation devices and controlling strategies are involved in electric power systems regulation design. When new devices are included in electric power system after the topology and regulation goals were defined, a new design stage is generally needed to obtain the desired outputs. Moreover, if the initial design is based on a linearized model around an equilibrium point, the new conditions might degrade the whole performance of the system. Our proposal demonstrates that the power system performance can be guaranteed with one design stage when an adequate adaptive scheme is updating some critic controllers’ gains. For large-scale power systems, this feature is illustrated with the use of time domain simulations, showing the dynamic behavior of the significant variables. The transient response is enhanced in terms of maximum overshoot and settling time. This is demonstrated using the deviation between the behavior of some important variables with StatCom, but without or with PSS. A B-Spline neural networks algorithm is used to define the best controllers’ gains to efficiently attenuate low frequency oscillations when a short circuit event is presented. This strategy avoids the parameters and power system model dependency; only a dataset of typical variable measurements is required to achieve the expected behavior. The inclusion of PSS and StatCom with positive interaction, enhances the dynamic performance of the system while illustrating the ability of the strategy in adding different controllers in only one design stage.

scholarly journals A Review of Techniques for RSS-Based Radiometric Partial Discharge Localization

Sensors ◽  
2021 ◽  
Vol 21 (3) ◽  
pp. 909
Author(s):  
David W. Upton ◽  
Keyur K. Mistry ◽  
Peter J. Mather ◽  
Zaharias D. Zaharis ◽  
Robert C. Atkinson ◽  
...  
Keyword(s):  
Power Systems ◽  
High Voltage ◽  
Partial Discharge ◽  
Specific Area ◽  
Electrical Insulation ◽  
Acoustic Detection ◽  
Advantages And Disadvantages ◽  
Initial Stage ◽  
Catastrophic Failures ◽  
Radiometric Detection

The lifespan assessment and maintenance planning of high-voltage power systems requires condition monitoring of all the operational equipment in a specific area. Electrical insulation of electrical apparatuses is prone to failure due to high electrical stresses, and thus it is a critical aspect that needs to be monitored. The ageing process of the electrical insulation in high voltage equipment may accelerate due to the occurrence of partial discharge (PD) that may in turn lead to catastrophic failures if the related defects are left untreated at an initial stage. Therefore, there is a requirement to monitor the PD levels so that an unexpected breakdown of high-voltage equipment is avoided. There are several ways of detecting PD, such as acoustic detection, optical detection, chemical detection, and radiometric detection. This paper focuses on reviewing techniques based on radiometric detection of PD, and more specifically, using received signal strength (RSS) for the localization of faults. This paper explores the advantages and disadvantages of radiometric techniques and presents an overview of a radiometric PD detection technique that uses a transistor reset integrator (TRI)-based wireless sensor network (WSN).

Vibration Control in Industrial Plant: A Methodological Approach

1987 ◽  
Vol 109 (4) ◽  
pp. 335-342
Author(s):  
D. Miconi
Keyword(s):  
Mathematical Models ◽  
Vibration Control ◽  
Methodological Approach ◽  
Graphic Representation ◽  
Industrial Plant ◽  
Design Stage ◽  
Machine Foundation ◽  
Damping Characteristics ◽  
Effective Instrument

The present paper is a report on the construction of nomograms to ascertain the domain of elastic-inertial-damping characteristics required in vibrating machine-foundation systems, in order to ensure that ergonomic and other technical constraints are complied with. Nomograms, which are the graphic representation of mathematical models in nondimensional form, prove to be an effective instrument for orientation in the design stage.

Integrating molecular and morphological approaches for characterizing parasite cryptic species: implications for parasitology

Parasitology ◽  
2011 ◽  
Vol 138 (13) ◽  
pp. 1688-1709 ◽  
Author(s):  
STEVEN A. NADLER ◽  
GERARDO PÉREZ-PONCE DE LEÓN
Keyword(s):  
Cryptic Species ◽  
Applied Research ◽  
Molecular Data ◽  
Theory And Practice ◽  
Parasitic Diseases ◽  
Advantages And Disadvantages ◽  
Research Programmes ◽  
Parasite Biodiversity ◽  
Operational Practices ◽  
Methodological Considerations

SUMMARYHerein we review theoretical and methodological considerations important for finding and delimiting cryptic species of parasites (species that are difficult to recognize using traditional systematic methods). Applications of molecular data in empirical investigations of cryptic species are discussed from an historical perspective, and we evaluate advantages and disadvantages of approaches that have been used to date. Developments concerning the theory and practice of species delimitation are emphasized because theory is critical to interpretation of data. The advantages and disadvantages of different molecular methodologies, including the number and kind of loci, are discussed relative to tree-based approaches for detecting and delimiting cryptic species. We conclude by discussing some implications that cryptic species have for research programmes in parasitology, emphasizing that careful attention to the theory and operational practices involved in finding, delimiting, and describing new species (including cryptic species) is essential, not only for fully characterizing parasite biodiversity and broader aspects of comparative biology such as systematics, evolution, ecology and biogeography, but to applied research efforts that strive to improve development and understanding of epidemiology, diagnostics, control and potential eradication of parasitic diseases.

scholarly journals Multi-Objective Optimization of Autonomous Microgrids with Reliability Consideration

Energies ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4466
Author(s):  
Maël Riou ◽  
Florian Dupriez-Robin ◽  
Dominique Grondin ◽  
Christophe Le Loup ◽  
Michel Benne ◽  
...  
Keyword(s):  
Power Systems ◽  
Rural Areas ◽  
Energy System ◽  
Design Stage ◽  
Multi Objective Optimization ◽  
Renewable Energy Resources ◽  
Nsga Ii ◽  
Renewable Integration ◽  
Multi Objective ◽  
Trade Offs

Microgrids operating on renewable energy resources have potential for powering rural areas located far from existing grid infrastructures. These small power systems typically host a hybrid energy system of diverse architecture and size. An effective integration of renewable energies resources requires careful design. Sizing methodologies often lack the consideration for reliability and this aspect is limited to power adequacy. There exists an inherent trade-off between renewable integration, cost, and reliability. To bridge this gap, a sizing methodology has been developed to perform multi-objective optimization, considering the three design objectives mentioned above. This method is based on the non-dominated sorting genetic algorithm (NSGA-II) that returns the set of optimal solutions under all objectives. This method aims to identify the trade-offs between renewable integration, reliability, and cost allowing to choose the adequate architecture and sizing accordingly. As a case study, we consider an autonomous microgrid, currently being installed in a rural area in Mali. The results show that increasing system reliability can be done at the least cost if carried out in the initial design stage.

BLOOD FLOW SIMULATION USING SPH METHOD IN LS-DYNA, ANALYSIS OF ADVANTAGES AND DISADVANTAGES

2021 ◽  
Author(s):  
Marko Topalovic ◽  
◽  
Aleksandar Nikolic ◽  
Miroslav Zivkovic
Keyword(s):  
Blood Flow ◽  
Flow Simulation ◽  
Fem Analysis ◽  
Sph Method ◽  
Shell Elements ◽  
Advantages And Disadvantages ◽  
Fluid Analysis ◽  
Eulerian Formulation ◽  
Mesh Free ◽  
Modelling Methodology

The purpose of this research was to investigate the possibility of blood flow modelling in LS-DYNA using its SPH solver and SPH-FEM coupling. SPH and FEM methods are both based on the continuum mechanics, and SPH uses Lagrangian material framework, while FEM can use both Lagrangian for solid, and Eulerian formulation for fluid analysis. SPH implementation is mesh-free giving it the capability to model very large deformations without mesh distortions. However, this comes at a high computational price, so the number of SPH particles needs to be significantly lower in comparison to the number of FEM elements in the Eulerian analysis of the same fluid domain. In the case of combined SPH-FEM analysis, the blood vessel wall is modelled with FEM shell elements, while the blood inside is modelled with SPH particles. The contact between the two is done using nodes to surface algorithm, while if we use the SPH only, there is no need for the specific contact definition. The Lagrangian framework of the SPH method means that we need to generate particles at one end, and to destroy them on the other, in order to generate a continuous fluid flow. To do this we used activation and deactivation planes, which is a solution implemented in the commercial LS-Dyna SPH solver. In the results section of the paper, the velocity field of blood obtained by implementation of described modelling methodology is shown. SPH-FEM coupling offers greater possibilities to study the effects of wall deformations, tracking of movement of solid particle inclusion, or mixing two different fluids, but it requires elaborate contact definition, and prolonged analysis time in comparison to the FEM CFD analysis.

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