scholarly journals Model-Based Optimization of an LLC-Resonant DC-DC Converter

Electronics ◽  
2019 ◽  
Vol 8 (7) ◽  
pp. 799
Author(s):  
Nikolay Hinov ◽  
Bogdan Gilev ◽  
Tsveti Hranov
Keyword(s):  
Transition Process ◽  
Automatic Regulation ◽  
Maximum Efficiency ◽  
Engineering Practice ◽  
Reliable Operation ◽  
Operating Modes ◽  
Model Based ◽  
Loss Maximum ◽  
Circuit Elements ◽  
Temperature Aging

The study presented in the paper is to guarantee the performance of the LLC DC-DC converter using model-based optimization. The primary scope of the study is to maintain the output parameters regardless of the variation of the values of the circuit elements. In engineering practice, it is known that any schematic element cannot be reproduced with an absolute accuracy of features. In addition, its main parameters change during operation due to changes in operating temperature, aging, operating modes and so on. Optimization procedures are a tool for finding the most appropriate values for circuit elements, with selected constraints, target functions and operating modes. In electronic converters, these are most often: minimal loss, maximum efficiency, the critical-aperiodic transition process, realization of certain dynamics, appropriate modes of operation and so on. The results obtained show that using the proposed approach produces more robustness to disturbances and tolerances, with improved dynamics and faster transient processes. On the other hand, the value of the circuit elements is smaller, and reliable operation of the protection and automatic regulation systems is achieved.

Conditions for the Effective Use of Air Curtain on Objects of Agricultural Production

2020 ◽  
Vol 67 (1) ◽  
pp. 54-59
Author(s):  
Aleksey V. Kuz’michev ◽  
Stanislav S. Trunov ◽  
Dmitriy A. Tikhomirov
Keyword(s):  
Agricultural Production ◽  
Theoretical Models ◽  
Research Purpose ◽  
Engineering Practice ◽  
Physical Factors ◽  
Air Curtain ◽  
Operating Modes ◽  
Air Jets ◽  
Urgent Task ◽  
Design Characteristics

Creating and maintaining a microclimate in animal housing is an energy-intensive technological process that consumes up to 70 percent of the thermal energy consumed on cattle farms. Improving heating and ventilation systems aimed at reducing energy consumption is an urgent task. (Research purpose) The research purpose is to analyze the theoretical models for calculating air curtains and evaluate the possibility of their use for agricultural production facilities and to identify promising directions in the design solutions for thermal air curtains aimed at rural consumers. (Materials and methods) The article considers the theoretical justification and calculation of air curtains. The authors studied the physical model of interaction of air jets in openings, which serves as the basis for mathematical calculation of air curtains in engineering practice. The article describes the features of using the models for calculating air curtains for agricultural objects and the energy parameters of the curtains depending on the design characteristics and external environmental factors. (Results and discussion) The effect of the air curtain on the energy characteristics of the room has been studied. It was found that it is necessary to determine the type of air curtain that is optimally suitable for protecting the gate opening, with or without heating the air curtain. Authors have found that the engineering methods of calculation are based on different experimental data, which leads to a discrepancy in the results of evaluating the effectiveness of the designed curtain, overestimating its energy intensity and power. The calculation of heat curtains, operating modes should be carried out taking into account the variable effects of external physical factors, the equipment should correspond to a specific room. (Conclusions) The use of air curtains reduces or eliminates the penetration of external cold air into the room through the openings of external gates, requires a smaller volume of air supplied by the curtain, compared to the mass of the incoming air flow.

Tracking Error Modeling of the Theodolite Based on GRNN Method

2011 ◽  
Vol 121-126 ◽  
pp. 4870-4874
Author(s):  
Miao Li ◽  
Hui Bin Gao
Keyword(s):  
Evaluation Method ◽  
Tracking Error ◽  
High Accuracy ◽  
Error Model ◽  
Error Modeling ◽  
General Regression Neural Network ◽  
Engineering Practice ◽  
Tracking Accuracy ◽  
Model Based ◽  
General Regression

To meet the requirement of high tracking accuracy as well as develop more reasonable evaluation method, in this paper, the General Regression Neural Network (GRNN) has been applied to build the tracking error model of the theodolite. First, we analyze the nonlinear factors in the theodolite. Second, we discuss the principle of GRNN, including its structure, the function as well as its priors. Third, we build the tracking error model based on GRNN and verify the model through the different parameters. The result indicated that the network model based on GRNN has high accuracy and good generalization ability. It could instead the real system to a certain extent. The research in this paper has important value to the engineering practice.

scholarly journals An Experimental Data-Driven Model of a Micro-Cogeneration Installation for Time-Domain Simulation and System Analysis

Energies ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2759 ◽  
Author(s):  
Wojciech Uchman ◽  
Janusz Kotowicz ◽  
Leszek Remiorz
Keyword(s):  
Time Domain ◽  
Electricity Generation ◽  
System Analysis ◽  
Data Driven ◽  
Maximum Efficiency ◽  
Time Domain Simulation ◽  
Term Operation ◽  
Operating Modes ◽  
Laboratory Setup ◽  
The Time Domain

In this article, an investigation of a free-piston Stirling engine-based micro-cogeneration (μCHP) unit is presented. This work is a step towards making the system calculations more reliable, based on a data-driven model, which enables the time-domain simulation of the μCHP behavior. A laboratory setup was developed that allowed for the measurement of a micro-cogeneration unit during long-term operation with a variable thermal load. The maximum efficiency of electricity generation was equal to 13.2% and the highest overall efficiency was equal to 95.7%. A model of the analyzed μCHP system was developed and validated. The simulation model was based on the device’s characteristics that were obtained from the measurements; it enables time-domain calculations, taking into account the different operating modes of the device. The validation of the system showed satisfactory compliance of the model with the measurements: for the period modeled of 24 h, the error in the heat generation fluctuated in the range 0.31–4.50%, the error in the electricity generation was in the range 2.48–4.70%, the error in the natural gas consumption was in the range 0.26–4.59%, and the engine’s runtime error was in the range 0.14–8.58%. The modelling process is easily applicable to other energy systems for detailed analysis.

scholarly journals Model-Based Testing Applied to Software Components of Satellite Simulators

2018 ◽  
Vol 2018 ◽  
pp. 1-14
Author(s):  
Paulo Diego Barbosa da Silva ◽  
Ana Maria Ambrosio ◽  
Emilia Villani
Keyword(s):  
Space Research ◽  
Test Case ◽  
Software Components ◽  
State Machines ◽  
Operating Modes ◽  
Model Based ◽  
Model Based Testing ◽  
Space Programs ◽  
Testing Approach ◽  
Correct Implementation

Operational simulators have a fundamental role in space programs. During a satellite operation, these simulators are essential for validating critical manoeuvres, testing new on-board software versions, and supporting the diagnosis of anomalies. With the purpose of reusing the operational simulators, the Brazilian National Institute for Space Research has proposed a new standard for the specification of the components that must be integrated in their in-house developed simulators. The new standard describes the behaviour of satellite subsystems using cause-effect tables that relate telecommands, electrical switches, equipment working states, energy consumption, telemetries, and operating modes of the subsystem. Using this new standard as input, this work proposes an approach that merges model-based testing and model checking to verify the correct implementation of new components in the satellite simulator. The verification approach consists of extracting state machines from the cause-effect tables and used it to automatically derive a test case suite. In order to validate the proposal, we applied it to three different satellite subsystems and assessed the results obtained from the test campaigns. In all the three cases, the proposed approach identified errors in the simulator components that were not initially detected by the traditional testing approach used at the Brazilian National Institute for Space Research.

Automatic Control of Operating Modes of Packed Apparatus for Selective Gas Emissions Cleaning

2020 ◽  
Vol 24 (2) ◽  
pp. 10-16 ◽  
Author(s):  
N.A. Merentsov ◽  
A.V. Persidsky ◽  
V.N. Lebedev ◽  
A.B. Golovanchikov
Keyword(s):  
Mass Transfer ◽  
Automatic Control ◽  
Mass Transfer Process ◽  
Automatic Regulation ◽  
Gas Emissions ◽  
Automatic Adjustment ◽  
Operating Modes ◽  
Mass Transfer Processes ◽  
Metal Chips ◽  
Main Operating

A modified system for automatic control of hydrodynamic operating modes of packed adsorption columns for the selective cleaning of gas emissions is described, which allows automatic adjustment of the operating modes of packed mass transfer apparatus. Presents the scheme and algorithm of developed system with the automatic adjustment (calibration) mode of main operating parameters. The main features and advantages of using elastically deformable blocks of packed material are given on the example of metal chips, i.e. waste of machine tools as a packed material that meet all requirements of the ongoing mass transfer processes and are amenable to automated regulation. The developed system of automatic regulation of parameters of packed units, but also to solve a very serious environmental problem of industrial waste recovery. A classification technique of studying the hydrodynamics of packed materials, capable of concluding the suitability of this sample of packing material for a specific mass transfer process, in particular the adsorption process for the selective cleaning of gas emissions.

scholarly journals THE CONTACT INTERACTION DYNAMICS OF THE WORKING TOOL OF THE MOLE PLOWSHARE WITH THE SOIL DURING FORMING PROSESS A CHANNEL FOR AN ANTI-FILTRATION SCREEN

2020 ◽  
pp. 81-89
Author(s):  
Olena Solona ◽  
Vladimir Kovbasa ◽  
Igor Kupchuk
Keyword(s):  
Rigid Body ◽  
Contact Interaction ◽  
Large Scale ◽  
Geometric Parameters ◽  
Theoretical Development ◽  
Maximum Efficiency ◽  
Industrial Complex ◽  
Engineering Structures ◽  
Operating Modes ◽  
Working Bodies

Today's realities of agriculture are increasingly prompting the need for the introduction of technologies for subsoil irrigation, as a possible tool to obtain maximum efficiency indicators of agricultural activities of agricultural enterprises. At the same time, the large-scale introduction of intra-soil irrigation technologies at the enterprises of the agro-industrial complex is significantly complicated due to the poor practical and theoretical development of its methods, as well as the lack of extensive experimental verification of this method of irrigation. The development of many processes in the construction of irrigation and engineering structures requires substantiation of the geometric parameters and operating modes of the working bodies that are used to implement these processes. One of the working bodies that is used to form the cavity along which communication is stretched is a mole plow, which, depending on the expected working conditions, may have a different geometric configuration and size. The results of investigations of the interaction of the mole ploughshare with the soil in cavity formation for laying the anti-filtration screen are describe in this article. The authors propose to consider the soil in the form of an elastic-viscous model. By solving the contact problem of the interaction of a rigid body with a deformed medium, the stress components in the soil on the contact surface with the ploughshare are determined, and soil compaction is determined. The components of forces that appear on the surface of the ploughshare because of its interaction with the soil are determined depending on its geometric parameters and the mechanical properties of the soil. This solution is a general approach for the analytical solution of the class of problems of the contact interaction of a rigid body with a deformable medium possessing the properties of elasticity and viscosity.

scholarly journals Refinement of the engineering practice of evaiuation of the wear rate of excavator impiement components

Dependability ◽  
2019 ◽  
Vol 19 (1) ◽  
pp. 18-23 ◽  
Author(s):  
I. V. Gadoiina ◽  
P. A. Pobegayio ◽  
D. Yu. Kritsky ◽  
L. Papić
Keyword(s):  
Abrasive Wear ◽  
Low Cost ◽  
Operating Conditions ◽  
Mining Machine ◽  
Engineering Practice ◽  
Mining Equipment ◽  
Operating Modes ◽  
Excavator Bucket ◽  
Dependability Evaluation ◽  
Scale Experiment

The existence of humankind on Earth largely depends on the energy at its disposal. It is mostly generated by processing minerals extracted from the Earth’s crust by open-cut mining. The quality and low cost of extraction are largely defined by the dependability of employed machines and mechanisms, plants and process engineering solutions. Various types of excavators are the backbone of a mining machine fleet. Their parts that principally interact with the environment (rock) are components of implements, i.e. primarily the buckets and components of bucket(s). It must be noted that in the process of interaction with the environment (rock) the excavator implements and their components are exposed to so-called abrasive wear. Since abrasive wear of implement components (most frequently excavator bucket teeth) causes their recurrent replacement, this inevitably affects the performance of the excavator as a whole and those process flows it is part of. Occasional interruptions of operation and repairs reduce the availability factor, the most important complex indicator of equipment dependability. Given the above, the aim of this paper is to refine the previously known formula proposed more than thirty years ago in VNIISDM (Reysh A.K.) for evaluation of the rate of abrasive wear of excavator bucket teeth. For the first time, with a sufficient accuracy we examined the multitude of operating modes of mining equipment, i.e. operation of excavators in various conditions, e.g. on different soils. Additionally, we extended Reysh’s approach from single-bucket machines to continuous operation multi-bucket ones. For that purpose, the authors used a method of data integration from known sources, method of full-scale experiment under the operating conditions of a specific excavator and method of mathematical simulation (a form of the Monte Carlo method). All of that allowed revising the values of the parameters in the Reysh formula. The refined formula that we obtained can now be used for the dependability evaluation of machines operating under varying conditions, as well as for the purpose of appointing the time of preventive inspections.

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