A Multi-domain Approach to the Stabilization of Electrodynamic Levitation Systems

2020 ◽  
Vol 142 (6) ◽  
Author(s):  
Renato Galluzzi ◽  
Salvatore Circosta ◽  
Nicola Amati ◽  
Andrea Tonoli ◽  
Angelo Bonfitto ◽  
...  
Keyword(s):  
State Of The Art ◽  
Point Of View ◽  
Lumped Parameter Model ◽  
Extensive Literature ◽  
Lumped Parameter ◽  
Levitation System ◽  
The Stability ◽  
Linearized Model ◽  
Proper Interpretation ◽  
System Paradigm

Abstract The Hyperloop transportation system paradigm has gained increasing attention in the last years due to its potential advantages in technology, territory, and infrastructure. From an engineering point of view, it would lead to fast, safe, efficient transportation of passengers and cargo. The stability of the electrodynamic levitation system represents a key enabling aspect of Hyperloop. In this context, the state of the art presents numerous attempts to stabilize these systems without definitive guidelines on how to attain proper, stable behavior. Furthermore, research has provided extensive literature in the context of electrodynamic bearings, which requires proper interpretation and generalization into the translational domain. In this paper, we address the stabilization of levitation systems by reproducing the strong interaction between the electrodynamic phenomenon and the mechanical domain. A novel lumped-parameter model with a multiple-branch circuit is proposed and tuned through finite-element simulations to replicate the electrodynamic behavior. The multi-domain equations are linearized and the unstable nature of the levitation system is identified and discussed. Then, a suitable method to add damping and optimize stability is studied. Finally, the linearized model is compared with the nonlinear representation to validate the followed approach.

Modeling of Vapor Compression Cycles for Multivariable Feedback Control of HVAC Systems

1997 ◽  
Vol 119 (2) ◽  
pp. 183-191 ◽  
Author(s):  
Xiang-Dong He ◽  
Sheng Liu ◽  
Haruhiko H. Asada
Keyword(s):  
Feedback Control ◽  
Phase Interface ◽  
Heat Pumps ◽  
Lumped Parameter Model ◽  
Vapor Compression ◽  
Two Phase ◽  
Lumped Parameter ◽  
Fan Speed ◽  
Linearized Model ◽  
Multivariable Feedback

This paper presents a new lumped-parameter model for describing the dynamics of vapor compression cycles. In particular, the dynamics associated with the two heat exchangers, i.e., the evaporator and the condenser, are modeled based on a moving-interface approach by which the position of the two-phase/single-phase interface inside the one-dimensional heat exchanger can be properly predicted. This interface information has never been included in previous lumped-parameter models developed for control design purpose, although it is essential in predicting the refrigerant superheat or subcool value. This model relates critical performance outputs, such as evaporating pressure, condensing pressure, and the refrigerant superheat, to actuating inputs including compressor speed, fan speed, and expansion valve opening. The dominating dynamic characteristics of the cycle around an operating point is studied based on the linearized model. From the resultant transfer function matrix, an interaction measure based on the Relative Gain Array reveals strong cross-couplings between various input-output pairs, and therefore indicates the inadequacy of independent SISO control techniques. In view of regulating multiple performance outputs in modern heat pumps and air-conditioning systems, this model is highly useful for design of multivariable feedback control.

scholarly journals Stability of Fractional Order Systems

2013 ◽  
Vol 2013 ◽  
pp. 1-14 ◽  
Author(s):  
Margarita Rivero ◽  
Sergei V. Rogosin ◽  
José A. Tenreiro Machado ◽  
Juan J. Trujillo
Keyword(s):  
Fractional Calculus ◽  
Fractional Order ◽  
State Of The Art ◽  
Point Of View ◽  
Fractional Order Systems ◽  
Short Period ◽  
Systems And Control ◽  
Different Types ◽  
The Stability ◽  
And Control

The theory and applications of fractional calculus (FC) had a considerable progress during the last years. Dynamical systems and control are one of the most active areas, and several authors focused on the stability of fractional order systems. Nevertheless, due to the multitude of efforts in a short period of time, contributions are scattered along the literature, and it becomes difficult for researchers to have a complete and systematic picture of the present day knowledge. This paper is an attempt to overcome this situation by reviewing the state of the art and putting this topic in a systematic form. While the problem is formulated with rigour, from the mathematical point of view, the exposition intends to be easy to read by the applied researchers. Different types of systems are considered, namely, linear/nonlinear, positive, with delay, distributed, and continuous/discrete. Several possible routes of future progress that emerge are also tackled.

scholarly journals Characterization of Giant Magnetostrictive Materials Using Three Complex Material Parameters by Particle Swarm Optimization

Micromachines ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 1416
Author(s):  
Yukai Chen ◽  
Xin Yang ◽  
Mingzhi Yang ◽  
Yanfei Wei ◽  
Haobin Zheng
Keyword(s):  
Classical Method ◽  
Lumped Parameter Model ◽  
Complex Material ◽  
Material Parameters ◽  
Magnetostrictive Materials ◽  
Lumped Parameter ◽  
Giant Magnetostrictive Materials ◽  
Power Transducer ◽  
And Performance ◽  
The Stability

Complex material parameters that can represent the losses of giant magnetostrictive materials (GMMs) are the key parameters for high-power transducer design and performance analysis. Since the GMMs work under pre-stress conditions and their performance is highly sensitive to pre-stress, the complex parameters of a GMM are preferably characterized in a specific pre-stress condition. In this study, an optimized characterization method for GMMs is proposed using three complex material parameters. Firstly, a lumped parameter model is improved for a longitudinal transducer by incorporating three material losses. Then, the structural damping and contact damping are experimentally measured and applied to confine the parametric variance ranges. Using the improved lumped parameter model, the real parts of the three key material parameters are characterized by fitting the experimental impedance data while the imaginary parts are separately extracted by the phase data. The global sensitivity analysis that accounts for the interaction effects of the multiple parameter variances shows that the proposed method outperforms the classical method as the sensitivities of all the six key parameters to both impedance and phase fitness functions are all high, which implies that the extracted material complex parameters are credible. In addition, the stability and credibility of the proposed parameter characterization is further corroborated by the results of ten random characterizations.

Dynamic Response of a Cam-Actuated Mechanism With Pneumatic Coupling

1977 ◽  
Vol 99 (3) ◽  
pp. 598-603 ◽  
Author(s):  
F. Y. Chen
Keyword(s):  
Dynamic Response ◽  
Dynamic Characteristics ◽  
Lumped Parameter Model ◽  
System Equation ◽  
Variation Of Parameters ◽  
Lumped Parameter ◽  
Cam Follower ◽  
The Stability

The dynamic characteristics of a cam-actuated system whose follower mass is coupled with a nonlinear pneumatic mechanism of hysteretic type are investigated using a lumped-parameter model. The dynamic response of the cam follower is obtained from the solution of the formulated system equation by the Krylov-Bogoliubov method of variation of parameters. The stability of the system is also investigated.

Mode-Coupled Regenerative Machine Tool Vibrations

2003 ◽  
Author(s):  
Tama´s Kalma´r-Nagy ◽  
Francis C. Moon
Keyword(s):  
Machine Tool ◽  
Cutting Tool ◽  
Chip Thickness ◽  
The Other ◽  
Lumped Parameter Model ◽  
Regenerative Effect ◽  
Lumped Parameter ◽  
Tool Vibrations ◽  
The Stability ◽  
Effect Time

In this paper a new 3 degree-of-freedom lumped-parameter model for machine tool vibrations is developed and analyzed. One mode is shown to be stable and decoupled from the other two, and thus the stability of the system can be determined by analyzing the remaining two modes. It is shown that this mode-coupled nonconservative cutting tool model including the regenerative effect (time delay) can produce an instability criteria that admits low-level or zero chip thickness chatter.

EFFECT OF SURFACE LAYER ON ELECTROMECHANICAL STABILITY OF TWEEZERS AND CANTILEVERS FABRICATED FROM CONDUCTIVE CYLINDRICAL NANOWIRES

2016 ◽  
Vol 23 (02) ◽  
pp. 1550101 ◽  
Author(s):  
MARYAM KEIVANI ◽  
ALI KOOCHI ◽  
HAMID M. SEDIGHI ◽  
MOHAMADREZA ABADYAN ◽  
AMIN FARROKHABADI ◽  
...  
Keyword(s):  
Surface Layer ◽  
Homotopy Perturbation Method ◽  
Differential Quadrature Method ◽  
Surface Elasticity ◽  
Lumped Parameter Model ◽  
Governing Equations ◽  
Lumped Parameter ◽  
The Stability ◽  
The Impact ◽  
Effect Of Surface

Herein, the impact of surface layer on the stability of nanoscale tweezers and cantilevers fabricated from nanowires with cylindrical cross section is studied. A modified continuum based on the Gurtin–Murdoch surface elasticity is applied for incorporating the presence of surface layer. Considering the cylindrical geometry of the nanowire, the presence of the Coulomb attraction and dispersion forces are incorporated in the derived formulations. Three different approaches, i.e. numerical differential quadrature method (DQM), an approximated homotopy perturbation method (HPM) and developing lumped parameter model (LPM) have been employed to solve the governing equations. The impact of surface layer on the instability of the system is demonstrated.

User-Adaptable Comfort Control for HVAC Systems

1994 ◽  
Vol 116 (3) ◽  
pp. 474-486 ◽  
Author(s):  
Clifford C. Federspiel ◽  
Haruhiko Asada
Keyword(s):  
Thermal Sensation ◽  
Human Subjects ◽  
A Priori ◽  
Hvac Systems ◽  
Lumped Parameter Model ◽  
New Approach ◽  
Tuning Parameters ◽  
Lumped Parameter ◽  
Priori Information ◽  
The Stability

This paper describes a new approach to the control of heating, ventilating, and air-conditioning (HVAC) systems. The fundamental concept of the new approach is that the controller learns to predict the actual thermal sensation of the specific occupant by tuning parameters of a model of the occupant’s thermal sensation. The parameters are adjusted with respect to thermal sensation ratings acquired from the specific occupant and measurements of physical variables that affect thermal sensation so that with time the model accurately reflects the thermal sensation of the specific occupant. From a lumped-parameter model of a singleroom enclosure, it is shown that the stability of the nominal system can be maintained by utilizing a priori information about the parameters of the thermal sensation model. The method is implemented on a ductless, split-system heat pump. Experiments using human subjects verify the feasibility of the method.

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