scholarly journals Dynamics of a coupled mechanical system containing a spherical pendulum and a fractional damper

Meccanica ◽  
2020 ◽  
Vol 55 (12) ◽  
pp. 2541-2553 ◽  
Author(s):  
Jan Freundlich ◽  
Danuta Sado
Keyword(s):  
Fractional Derivative ◽  
Spherical Pendulum ◽  
System Parameters ◽  
External Resonance ◽  
Time Histories ◽  
Linear Spring ◽  
Three Degree Of Freedom ◽  
The Impact ◽  
Resonance Bifurcation ◽  
Fractional Type

AbstractThe presented work deals with nonlinear dynamics of a three degree of freedom system with a spherical pendulum and a damper of the fractional type. Vibrations in the vicinity of the internal and external resonance are considered. The system consists of a block suspended from a linear spring and a fractional damper, and a spherical pendulum suspended from the block. The viscoelastic properties of the damper are described using the Caputo fractional derivative. The fractional derivative of an order of $$0 < \alpha \le 1$$ 0 < α ≤ 1 is assumed. The impact of a fractional order derivative on the system with a spherical pendulum is studied. Time histories, the internal and external resonance, bifurcation diagrams, Poincaré maps and the Lyapunov exponents have been calculated for various orders of a fractional derivative. Chaotic motion has been found for some system parameters.

scholarly journals Impact of the Generation System Parameters on the Frequency Response of the Power System: A UK Grid Case Study

Electricity ◽  
2021 ◽  
Vol 2 (2) ◽  
pp. 143-157
Author(s):  
Jovi Atkinson ◽  
Ibrahim M. Albayati
Keyword(s):  
Power System ◽  
Frequency Response ◽  
Power Grid ◽  
Sudden Increase ◽  
Generation System ◽  
System Parameters ◽  
Primary Frequency ◽  
Primary Frequency Response ◽  
The Impact ◽  
System Inertia

The operation and the development of power system networks introduce new types of stability problems. The effect of the power generation and consumption on the frequency of the power system can be described as a demand/generation imbalance resulting from a sudden increase/decrease in the demand and/or generation. This paper investigates the impact of a loss of generation on the transient behaviour of the power grid frequency. A simplified power system model is proposed to examine the impact of change of the main generation system parameters (system inertia, governor droop setting, load damping constant, and the high-pressure steam turbine power fraction), on the primary frequency response in responding to the disturbance of a 1.32 GW generation loss on the UK power grid. Various rates of primary frequency responses are simulated via adjusting system parameters of the synchronous generators to enable the controlled generators providing a fast-reliable primary frequency response within 10 s after a loss of generation. It is concluded that a generation system inertia and a governor droop setting are the most dominant parameters that effect the system frequency response after a loss of generation. Therefore, for different levels of generation loss, the recovery rate will be dependent on the changes of the governor droop setting values. The proposed model offers a fundamental basis for a further investigation to be carried on how a power system will react during a secondary frequency response.

Global Analysis of the Double Impact Oscillator Dynamics

1999 ◽  
Author(s):  
František Peterka
Keyword(s):  
Global Analysis ◽  
Impact Oscillator ◽  
System Parameters ◽  
Impact Oscillators ◽  
Real Value ◽  
Simulation Results ◽  
The Impact ◽  
Impact Motion ◽  
Double Impact ◽  
Phase Motion

Abstract The double impact oscillator represents two symmetrically arranged single impact oscillators. It is the model of a forming machine, which does not spread the impact impulses into its neighbourhood. The anti-phase impact motion of this system has the identical dynamics as the single system. The in-phase motion and the influence of asymmetries of the system parameters are studied using numerical simulations. Theoretical and simulation results are verified experimentally and the real value of the restitution coefficient is determined by this method.

scholarly journals Exploiting Thermochronology to Quantify Exhumation Histories and Patterns of Uplift Along the Margins of Tibet

2021 ◽  
Vol 9 ◽  
Author(s):  
Kevin P. Furlong ◽  
Eric Kirby
Keyword(s):  
Thermal History ◽  
Data Sets ◽  
The Tibetan Plateau ◽  
Tectonic History ◽  
Time Histories ◽  
Major Fault ◽  
History Of ◽  
Cooling Behavior ◽  
Exhumation Rates ◽  
The Impact

The utilization of thermal-chronological data to constrain mountain building processes exploits the links among rock uplift, exhumation, and cooling during orogenesis. Conceptually, periods of rapid uplift and associated denudation will lead to cooling of rocks as they approach Earth’s surface. The linkage between uplift and exhumation can be complex, but in practice exhumation is often assumed to directly track uplift. The reconstruction of temperature-time histories via thermochronologic systems provides a proxy method to relate the cooling of rock as it is exhumed toward the surface to orogenesis. For the rapid exhumation rates that can occur in active orogenic systems the thermal history will be complex as a result of heat advection, rates of propagation of thermal perturbations, and other processes that affect the cooling behavior. These effects become amplified as exhumation rates increase, and in regions experiencing exhumation rates greater than ∼0.2–0.3 mm/yr (0.2–0.3 km/Ma) simple assumptions of cooling through a constant geotherm will bias the subsequent interpretation. Here we explore, through a suite of generalized models, the impact of exhumation rate and duration on the resulting thermal history and apparent age results. We then apply lessons from these simple exhumation systems to data sets from the high-relief ranges along the eastern margin of the Tibetan Plateau to determine exhumation histories constrained by those data. The resulting exhumation histories provide constraints on the onset of Cenozoic exhumation, the subsequent pace of exhumation, and on the tectonic history of one of the major fault systems in the central Longmen Shan.

scholarly journals Finite Element Analysis-Aided Performance Improvement of Circular Coil Assemblies Applied in Electric Vehicle Inductive Chargers

2021 ◽  
Author(s):  
Guodong Zhu ◽  
Dawei Gao
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Electric Vehicle ◽  
Performance Improvement ◽  
Magnetic Circuit ◽  
Element Analysis ◽  
System Parameters ◽  
Leakage Magnetic Field ◽  
Fea Simulation ◽  
The Impact

Energy efficiency and leakage magnetic field (LMF) are two important issues in inductive chargers. In this work, the maximum achievable coil efficiency and the corresponding LMF strength are formulated as functions of system parameters, and figure of merits (FOM) are proposed for assessing the efficiency and LMF performance of the coil assemblies. The target application is electric vehicle inductive chargers where the LMF is suppressed via passive shielding. The impact of the coil assembly’s geometric parameters on both FOMs is examined through a combination of finite element analysis (FEA) simulation and magnetic circuit analysis, and measures to improve the FOMs are studied Optimization of an exemplary coil assembly within given dimensional limits is conducted and the performance improvement is verified by FEA simulation results. <br>

PaaS Optimization of Apache Applications Using System Parameter Tuning of Big Data Platforms in Distributed Computing

2020 ◽  
Vol 11 (4) ◽  
pp. 23-38
Author(s):  
Tanuja Pattanshetti ◽  
Vahida Attar
Keyword(s):  
Parameter Tuning ◽  
Service Level ◽  
System Parameters ◽  
Second Stage ◽  
Huge Data ◽  
Optimal Value ◽  
System Output ◽  
Software Quality Metrics ◽  
The Impact ◽  
Individual Input

Widely used data processing platforms use distributed systems to process huge data efficiently. The aim of this article is to optimize the platform services by tuning only the relevant, tunable, system parameters and to identify the relation between the software quality metrics. The system parameters of data platforms based on the service level agreements can be defined and customized. In the first stage, the most significant parameters are identified and shortlisted using various feature selection approaches. In the second stage, the iterative runs of applications are executed for tuning these shortlisted parameters to identify the optimal value and to understand the impact of individual input parameters on the system output parameter. The empirical results imply significant improvement in performance and with which it is possible to render the proposed work optimizing the services offered by these data platforms.

A Systematic Comparison and Multi-Objective Optimization of Humid Power Cycles—Part I: Thermodynamics

2009 ◽  
Vol 131 (4) ◽  
Author(s):  
R. M. Kavanagh ◽  
G. T. Parks
Keyword(s):  
Power Systems ◽  
Gas Turbine ◽  
Search Algorithm ◽  
Working Fluid ◽  
Specific Work ◽  
Humid Air ◽  
System Parameters ◽  
Multi Objective ◽  
Air Turbine ◽  
The Impact

The steam injected gas turbine (STIG), humid air turbine (HAT), and TOP Humid Air Turbine (TOPHAT) cycles lie at the center of the debate on which humid power cycle will deliver optimal performance when applied to an aeroderivative gas turbine and, indeed, when such cycles will be implemented. Of these humid cycles, it has been claimed that the TOPHAT cycle has the highest efficiency and specific work, followed closely by the HAT, and then the STIG cycle. In this study, the systems have been simulated using consistent thermodynamic and economic models for the components and working fluid properties, allowing a consistent and nonbiased appraisal of these systems. Part I of these two papers focuses purely on the thermodynamic performance and the impact of the system parameters on the performance; Part II will study the economic performance. The three humid power systems and up to ten system parameters are optimized using a multi-objective Tabu Search algorithm, developed in the Cambridge Engineering Design Centre.

Comparative Study of Evolutionary Algorithms for Parameter Identification of an Impact Oscillator

2014 ◽  
Author(s):  
Amit Banerjee ◽  
Issam Abu Mahfouz
Keyword(s):  
Evolutionary Algorithms ◽  
Differential Evolution ◽  
Parameter Identification ◽  
Optimization Techniques ◽  
System Response ◽  
Impact Oscillator ◽  
Swarm Optimization ◽  
System Parameters ◽  
Highly Nonlinear ◽  
The Impact

The use of non-classical evolutionary optimization techniques such as genetic algorithms, differential evolution, swarm optimization and genetic programming to solve the inverse problem of parameter identification of dynamical systems leading to chaotic states has been gaining popularity in recent years. In this paper, three popular evolutionary algorithms — differential evolution, particle swarm optimization and the firefly algorithm are used for parameter identification of a clearance-coupled-impact oscillator system. The behavior of impacting systems is highly nonlinear exhibiting a myriad of harmonic, low order and high order sub-harmonic resonances, as well as chaotic vibrations. The time-history simulations of the single-degree-of-freedom impact oscillator were obtained by the Neumark-β numerical integration algorithm. The results are illustrated by bifurcation graphs, state space portraits and Poincare’ maps which gives valuable insights on the dynamics of the impact system. The parameter identification problem relates to finding one set of system parameters given a chaotic or periodic system response as a set of Poincaré points and a different but known set of system parameters. The three evolutionary algorithms are compared over a set of parameter identification problems. The algorithms are compared based on solution quality to evaluate the efficacy of using one algorithm over another.

scholarly journals Autonomous Energy Matching Control in an LLC Induction Heating Generator

Energies ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1860
Author(s):  
Jerzy Zgraja ◽  
Grzegorz Lisowski ◽  
Jacek Kucharski
Keyword(s):  
Induction Heating ◽  
Active Role ◽  
Load Resistance ◽  
Heating Process ◽  
Strong Impact ◽  
Functional Dependencies ◽  
Resonance System ◽  
System Parameters ◽  
Equivalent Load ◽  
The Impact

Induction heating is one of the most effective methods of energy conversion from the electrical to thermal form, used in diverse industrial processes. In this paper the resonance generators for induction heating are considered for which the equivalent load resistance has a strong impact on the ability of the system to use optimally the potentially available power. The equivalent load resistance varies, depending on the type of induction heating system (IHS) and during the heating process itself. This paper presents an induction heat generator in which an L-LC resonance system (called the LLC system) plays an active role in energy matching. The LLC resonance system is analyzed from the point of view of both the functional dependencies describing the influence of frequency on the load resistance transformation, and the impact of the LLC setup on the sensitivity of the generator to changes in the charge resistance caused by heating. The procedure for initial selection of the resonance system parameters is presented. We also consider the possibility of automatic correction by the generator of the LLC system parameters, in order to limit the effect of changes in the IHS parameters on the degree of source–load energy matching. We describe cascade power control algorithms based on the use of Field Programmable Gate Array (FPGA) systems, which enable the optimal control of energy matching. Our study is based on theoretical considerations, numerical simulations, and experimental verification using a 30 kW model.

Analysis of two colliding fractionally damped spherical shells in modelling blunt human head impacts

Open Physics ◽  
2013 ◽  
Vol 11 (6) ◽  
Author(s):  
Yury Rossikhin ◽  
Marina Shitikova
Keyword(s):  
Fractional Derivative ◽  
Human Head ◽  
Contact Spot ◽  
Spherical Shells ◽  
Spherical Object ◽  
Frontal Impacts ◽  
Age Related ◽  
Laplace Transform Technique ◽  
The Laplace Transform ◽  
The Impact

AbstractThe collision of two elastic or viscoelastic spherical shells is investigated as a model for the dynamic response of a human head impacted by another head or by some spherical object. Determination of the impact force that is actually being transmitted to bone will require the model for the shock interaction of the impactor and human head. This model is indended to be used in simulating crash scenarios in frontal impacts, and provide an effective tool to estimate the severity of effect on the human head and to estimate brain injury risks. The model developed here suggests that after the moment of impact quasi-longitudinal and quasi-transverse shock waves are generated, which then propagate along the spherical shells. The solution behind the wave fronts is constructed with the help of the theory of discontinuities. It is assumed that the viscoelastic features of the shells are exhibited only in the contact domain, while the remaining parts retain their elastic properties. In this case, the contact spot is assumed to be a plane disk with constant radius, and the viscoelastic features of the shells are described by the fractional derivative standard linear solid model. In the case under consideration, the governing differential equations are solved analytically by the Laplace transform technique. It is shown that the fractional parameter of the fractional derivative model plays very important role, since its variation allows one to take into account the age-related changes in the mechanical properties of bone.

Effects of nonconstant coupling through nonlinear magnetics in electromagnetic vibration energy harvesters

2012 ◽  
Vol 23 (13) ◽  
pp. 1533-1541 ◽  
Author(s):  
Clemens Cepnik ◽  
Eric M Yeatman ◽  
Ulrike Wallrabe
Keyword(s):  
Magnetic Field ◽  
Energy Harvesting ◽  
Magnetic Fields ◽  
Vibration Amplitude ◽  
Homogeneous Magnetic Field ◽  
Vibration Energy ◽  
System Parameters ◽  
Energy Harvesters ◽  
Electromagnetic Vibration ◽  
The Impact

This article discusses how a nonhomogeneous magnetic field with a nonconstant flux gradient affects the behavior of electromagnetic vibration energy harvesters. Based on simulations, the authors show that this nonlinearity enables to increase the output power and bandwidth but not to effectively limit the oscillator vibration amplitude. The impact, however, depends on various system parameters, especially the mechanical damping. Comparing the results to an energy-harvesting prototype, one can conclude that, in practice, the linear model based on a homogeneous magnetic field provides a good estimate. The authors finally give suggestions about magnetic fields that are beneficial for energy harvesting.

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