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Numerical analysis of a vibro-impact system with ideal and non-ideal excitation

Journal of Physics: conference Series 2021年第1期1730卷

作者： Dzanko Hajradinovic Miodrag Zukovic Ivana Kovacic Department of Mechanics Faculty of Mechanical Engineering University of Sarajevo Vilsonovo setaliste 9 Sarajevo Bosnia and Herzegovina Centre for Vibro-Acoustic Systems and Signal Processing Faculty of Technical Sciences University of Novi Sad Novi Sad Serbia

This study is concerned with modelling and analyses of a vibro-impact system consisting of a crank-slider mechanism and one oscillator attached to it, where the system can be exposed to ideal or non-ideal excitation. The impact occurs during the motion of the oscillator when it hits a base, and the excitation of the driving source is affected by this behaviour. The aim is to determine the interaction between a driving torque and the motion of the oscillator. To achieve this aim in a methodologically sound manner, both vibro-impact systems with ideal and non-ideal excitation are analysed. For these system differential equations are formed and the impact model is provided in the paper. The impact causes a strong nonlinearity in the system. The mathematical model of the vibro-impact system with ideal excitation is presented as a second order differential equation where the vibro-impact system with non-ideal excitation is given as a coupled system of nonlinear second order differential equations. Numerical simulations are carried out for the two systems and the results obtained are shown in terms of frequency response diagrams as well as in terms of time-displacement diagrams. The results found for different systems are compared mutually, and the differences between them are pointed out. Impact solutions for different regions of the excitation frequency are shown. For a specific value of the excitation frequency in the frequency response diagram where multiple solutions are found, basin of attractor diagrams are formed. Average value of the excitation frequency is used for the vibro-impact system with non-ideal excitation.

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modelling of photovoltaic cells in variable conditions of temperature and intensity of solar insolation as a method of mapping the operation of the installation in real conditions

Modelling of photovoltaic cells in variable conditions of te...

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2018 International Interdisciplinary PhD Workshop, IIPhDW 2018

作者： Zielińska, Anna Skowron, Mikolaj Bień, Andrzej AGH University of Science and Technology Cracow Poland

ISBN: (纸本)9781538661437

In engineering it is a common practice to apply a mathematical model of a given system in order to describe the behaviour of the system. The main aim of this study is to create a mathematical model of a photovoltaic installation as well as to verify whether such model enables one to assess the effectiveness, operating specification and voltage characteristics of the mentioned installation without the need for creating a real-world working installation. The mathematical models have been prepared for a single photovoltaic cell as well as a series circuit of a couple of cells connected using both a bypass diode. The study has been carried out using Matlab Simulink software in various levels of exposure to Sun rays, various temperatures as well as during a simulation of a partial eclipse of the photovoltaic installation. In order to depict the operation of the mathematical model, a graphic interpretation of the results has been created. The graphic presentation of the data has enabled one to show how temperature and sun-light intensity (changing atmospheric conditions) can influence the voltage characteristics of the photovoltaic modules. It also shows the dependence between power and voltage. The study shows that the mathematical model can be used for exploring anomalies as well as for diagnostics. It also enables one to interpret the results described through an implemented algorithm in a way that would mirror real operating conditions. © 2018 IEEE.

关键词： MATLAB

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Four-Bar Mechanism Substitution for Balance Board Experiments: A Parametric Study

Four-Bar Mechanism Substitution for Balance Board Experiment...

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14th International conference on Dynamical Systems - Theory and Applications (DSTA) - Recent Developments in mathematical modelling of Dynamical Systems

作者： Zelei, Ambrus Molnar, Csenge A. Insperger, Tamas MTA BME Res Grp Dynam Machines & Vehicles Muegyet Rkp 3-5 H-1111 Budapest Hungary MTA BME Lendulet Human Balancing Res Grp Muegyet Rkp 3-5 H-1111 Budapest Hungary Budapest Univ Technol & Econ Dept Appl Mech Budapest Hungary

ISBN: (纸本)9783319966014

Our research aims the study of balancing on a rolling balance board with respect to dynamic properties such as stability and stabilizability. The goal is to identify the parameter regions where human subjects are able to keep themselves stable in the upright position for at least 60 s. The radius of the balance board and the height of the foot platform are adjusted for each individual test, which is a time demanding process. We give a preliminary design of a substituting four-bar mechanism in order to speed up the balance board experiments and to extend the limits of the parameter study. The mechanism is tunable quickly in order to imitate the motion of the balance board with different radii and platform heights;whilst the agreement of the kinematic behaviour is almost perfect for tilt angles within the region of +/- 30 degrees. The dynamic behaviour of the mechanism and the balance board are compared based on theoretically derived stability diagrams associated with the underlyingmechanical models. The balancing process ismodelled by a proportional-derivative delayed feedback controller in order to account with the reaction time delay of the subject. We show that the stable parameter regions of the balance board and the mechanism are in good agreement, therefore the mechanism can be used as a substituting device for balance board.

关键词： human balancing Rolling balance board Four-bar mechanism Time-delay systems Parameter optimization

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Grid Tied Solid Oxide Fuel Cell Power Generation System for Peak Load Management

Grid Tied Solid Oxide Fuel Cell Power Generation System for ...

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International conference on Electronics, Communication and Computing Technologies (ICECCT)

作者： Sooraj Suresh Kumar C.M. Nirmal Mukundan P. Jayaprakash M.V. Manoj Kumar Government College of Engineering Kannur Kerala India Government College of Engineering Kannur India

Solid Oxide Fuel Cell (SOFC) based Transportation system have been reported as the future of human society. The SOFC based systems are pollution free and it converts fuel to electrical energy at high efficiency. The use of these fuel cell electric vehicle as stationary power production unit has added to the future prospects of such systems. This will help in creating a network of decentralized small scale power production units in the grid. Such power production units can be used effectively to meet the peak power demands in the *** paper proposes a grid tied Solid Oxide Fuel Cell (SOFC) system. The mathematical modelling of fuel cell given literature has been analysed and a Solid Oxide Fuel Cell (SOFC) model has been simulated. The SOFC has been further connected to a boost converter and an inverter to create a grid connected power generation system. Synchronous reference frame (SRF) theory has been used to syncronise the output of the proposed system to the grid. The proposed system has also been simulated using MATLAB with its Simpower system Blockset. The performance of the proposed system is found to be satisfactory.

关键词： Fuel cells Power generation Fuels mathematical model Hydrogen Inverters Load modeling

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Objective-Subjective Sound Quality Correlation Performance Comparison of Genetic Algorithm Based Regression Models and Neural Network Based Approach

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Journal of Physics: conference Series 2021年第1期2041卷

作者： Reza Jamali Gianmarco Battista Milena Martarelli Paolo Chiariotti Deepti Shriram Kunte Claudio Colangeli Paolo Castellini Department of Industrial Engineering and Mathematical Sciences Universita Politecnica delle Marche Via Brecce Bianche 60100 Ancona Italy Department of Mechanical Engineering Politecnico di Milano 20156 Milan Italy Siemens Industry Software NV Interleuvenlaan 68 3001 Leuven Belgium

Every product is growingly being evaluated in terms of acoustic characteristics. The most accurate way to rate sound quality is by performing jury tests; however, jury tests require a lot of time and human resources. To overcome this problem, jury tests results can be correlated to objective sound quality metrics owing to the fact that objective metrics could be easily obtained from sound data. In this study, advanced techniques for feature identification are explored to correlate objective metrics to subjective perception retrieved from jury tests. The data set referes to the interior noise of a regional propeller aircraft. Artificial Neural Network and two regression models (i.e. linear and quadratic regression models) have been chosen to predict subjective metrics according to the objective data. To obtain the optimized model parameters for the regression models, a Genetic Algorithm has been used as optimization strategy. In each modelling, 85 percent of sound sample data have been utilized to perform the model and remaining 15 percent have been reserved for testing the models. The results showed that the Artificial Neural Network can provide better prediction.

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Study on behaviour of compression members based on concept of biomimics 3

Study on behaviour of compression members based on concept o...

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3rd International conference on Recent Advances in Material Chemistry, ICRAMC 2019

作者： Sindhu Nachiar, S. Satyanarayanan, K.S. Lakshmipathy, M. Sai Pavithra, S. Department of Civil Engineering SRMIST Kattankulathur Kanchipuram Dt Tamil Nadu India

Biomimicry is the process of imitating nature to solve complex human problems. The concept of biomimicry can be used in different fields like material production, engineering, architecture etc. This paper is focused on structural design concept inspired by human skeleton. Structurally, human body is a stable vertical slender element of frameworks using bones. The key idea is taken by considering the femur bone as adaptation model for columns. In this paper, the behaviour of human bone is studied using F.E.A (finite element analysis). The human bone is efficient in resisting compressive force. The modelling of real proximal human bone is done using MIMICS and is analyzed in ANSYS under compressive force. Five different shapes (Round, Square, Stepped, Tapered, Mimicked) of compression member similar to bone is modelled and analysed. The mimicked model is found to be the best fit model for further study. Fifteen different shapes of models were derived by varying the diameter to half and double along the length. The stress pattern of real bone and the models (Compression member) were compared and studied. Many models have been derived out of which a particular configuration after iteration has given an optimal stress level. A particular model with M40 grade of concrete is found suitable as optimised based on shape and stress pattern. © 2018 Elsevier Ltd.

关键词： Stress analysis

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A REVIEW of modelling APPROACHES on TIDAL ANALYSIS and PREDICTION 6

A REVIEW of MODELLING APPROACHES on TIDAL ANALYSIS and PREDI...

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6th International conference on Geomatics and Geospatial Technology, GGT 2019

作者： Abubakar, A.G. Mahmud, M.R. Tang, K.K.W. Hussaini, A. Md Yusuf, N.H. Faculty of Built Environment and Surveying Universiti Teknologi Malaysia Bahru Johor81310 Malaysia Department of Surveying and Geo-Informatics College of Environmental Studies Waziri Umaru Federal Polytechnic Birnin Kebbi Kebbi State Nigeria Department of Geography Aminu Saleh College of Education Azare Bauchi Bauchi Nigeria

Tide height depends on both long-term astronomical effects that are principally affected by the moon and sun and short-term meteorological effects caused by severe weather conditions which are very important tasks for human activities, safe marine navigation in shallow areas, oceans and coastal engineering work. Conventional tidal forecasting techniques are based on harmonic analysis, which is a superposition of many sinusoidal constituents with three parameters amplitudes, Phase and frequencies using the least squares method to determine the harmonic parameters. However, harmonic analysis required a large number of parameters and long-term tidal measured for precise tidal level predictions. Furthermore, what seems to stand out by the other researchers on traditional harmonic methods, was its limitation when short data are involved and rely on based on the analysis of astronomical components and they can be insufficient when the influence of non-astronomical components such as the weather, is important. Therefore, conventional harmonic analysis alone does not adequately predict the coastal water level variation, in order to deal with these situations and provide predictions with the desired accuracy, with respect to the length of the available tidal record, an alternative approach has been developed by various tidalist. In this study the state - of - art for tidal analysis and prediction techniques that have proven to be successful in a variety of circumstances have been reviewed in a systematic and consistent way for holistic understanding with a view to provide a reference for future work, showing their main mathematical concepts, model capabilities for tidal analysis and prediction with their limitations. © 2019 A. G. Abubakar et al.

关键词： Harmonic analysis

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A generalized NURBS based dynamic metabolic flux analysis framework: Deciphering intracellular pathway activation from extracellular measurements 10

A generalized NURBS based dynamic metabolic flux analysis fr...

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10th International conference on Simulation and modelling in the Food and Bio-Industry, FOODSIM 2018

作者： Nimmegeers, Philippe Akkermans, Simen Gijsen, Wouter Telen, Dries Van Impe, Jan BioTeC+ and OPTEC Department of Chemical Engineering KU Leuven CPMF2 Flemish Cluster Predictive Microbiology in Foods Gebroeders de Smetstraat 1 GentB-9000 Belgium

ISBN: (纸本)9789492859013

Current macroscopic population balance models are not sufficient to obtain a profound understanding in the complex behaviour of microbial responses in food. Including metabolic network information in mathematical models leads to an improved mechanistic insight in microbial processes. The main difficulty in including such information is the high number of fluxes and metabolites and the number of ordinary differential equations that has to be added to the model equations. To reduce the number of mass balance differential equations, pseudo steady state is assumed and the intracellular mass balances are replaced by an underdetermined system of algebraic equations. Dynamic metabolic flux analysis estimates intracellular time-dependent flux distributions from available measurements, by parameter-izing the fluxes as a function of time. In this article, a novel DMFA technique based on a non-uniform rational B-splines (NURBS) parameterization of the free fluxes (NDMFA) is presented. This NDMFA technique can be seen as a generalization of previously introduced state of the art DMFA techniques. © 2018 EUROSIS-ETI.

关键词： Parameter estimation

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Static characteristics of a simple rotor-bearing system: modelling and experiment

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IOP conference Series: Materials Science and engineering 2020年第1期895卷

作者： Phuoc Vinh Dang Le Dinh Minh Nhat Nhu Thanh Vo Thanh Nghi Ngo Hoai Nam Le Huu Nhan Nguyen Department of Mechanical Engineering The University of Danang–Danang University of Science and Technology School of Material Science - Japan Advanced Institute of Science and Technology

The dynamics of rotating machinery have been extensively investigated during the past century. To date, longer rotating shafts, higher rotating velocity, higher fluid pressure, and generally high performances are required. For this purpose, a deep understanding and a more accurate modelling of the rotating machinery dynamical behaviour is needed, especially in terms of the resultant vibrations and stability issues. In this paper, a mathematical model was developed for a simple rigid rotor-bearing system using finite element method. Several natural frequencies and corresponding mode shapes of the systems were presented. In order to validate the model, some experimental tests were performed using a small test rig. The response of the system in the frequency domain and the direct orbit of the shaft were plotted as well.

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modelling and Control of Paraplegic Subjects Walking Using Functional Electrical Stimulation

Modelling and Control of Paraplegic Subjects Walking Using F...

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International conference on Cognitive Infocommunications (CogInfoCom)

作者： Razieh Darshi Ali Reza Khayatian Maryam Dehghani Reza Boostani School of Electrical and Computer Engineering Shiraz University Shiraz Iran

ISBN: (数字)9781728147932

ISBN: (纸本)9781728147949

Walking stabilization of paraplegic patients by designing a controller in order to apply functional electrical stimulation (FES) to their muscles is still a challenging issue. In this paper, to analyze the paraplegic walking, at the first step, a model for human locomotion is presented and then, PID controllers are designed in order to determine the activation patterns using FES to contract muscles of a patient that can walk like healthy persons. In this manner, a known walking musculoskeletal model is implemented, which comprises angles of feet, shanks, thighs and trunk. The model is a seven degree-of freedom (DOF) rigid linkage in the sagittal plane. The model is specified by user-specific parameters consisting of lengths, masses and inertia. Reference trajectory for simulation are recorded from healthy subjects during walking. Here, by the use of muscle inverse model and seven independent PID controllers, controlling signals in the form of FES are calculated and applied to the corresponding muscles of the model such that they can contract and produce required torques for human walking, and therefore the angles of joints (feet, shanks, thighs and trunk) can finely trace the trajectory patterns of healthy subjects.

关键词： Muscles Legged locomotion Torque mathematical model Iron Computational modeling Knee

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