Optimum absorber parameters for various combinations of response and excitation parameters

Bistable microsystems have drawn considerable interest from the MEMS/NEMS research community not only due to their broad applicability in commercial applications, such as switching, but also because of the rich dynamic behavior they commonly exhibit. While a number of prior investigations have studied the dynamics of bistable microsystems, comparatively few works have sought to characterize their transient behavior. The present effort seeks to address this through the modeling and analysis of an optically-actuated, bistable MEMS switch. The work begins with the development of a distributed-parameter representation for the system, which is subsequently reduced to a lumped-mass analog and analyzed through the use of numerical simulation. The influence of various system and excitation parameters, including the applied axial load and optical actuation profile, on the system’s transient response is then investigated. Ultimately, the methodologies and results presented herein should provide for a refined predictive design capability for optically-actuated, bistable MEMS devices.

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Enhancing the Performance of DFIG Wind Turbines Considering Excitation Parameters of the Insulated Gate Bipolar Transistors and a New PLL Scheme

Frontiers in Energy Research ◽

10.3389/fenrg.2020.620277 ◽

2021 ◽

Vol 8 ◽

Author(s):

Kenneth E. Okedu ◽

Hind F. A. Barghash

Keyword(s):

Power System ◽

Wind Turbine ◽

Control Strategy ◽

Computer Aided Design ◽

Transient State ◽

Power Converter ◽

Bipolar Transistors ◽

Insulated Gate Bipolar Transistors ◽

Wind Generator ◽

Excitation Parameters

The major aim for achieving the successful synchronization of a wind turbine system to the grid is to mitigate electrical and mechanical stresses on the wind generator. During transient state, the gearbox, shaft, and rotor of the wind generator could be damaged due to mechanical stress. The rotor and stator windings of the wind generator, including its insulation, could be affected. This paper undertakes an extensive analysis of the effects of the excitation parameters of the power converter Insulated Gate Bipolar Transistors (IGBTs), on the transient state performance of the Doubly Fed Induction Generator (DFIG), considering different scenarios. The optimal excitation parameters of IGBTs were used for further analysis of the wind generator, considering a new Phase-Locked-Loop (PLL) scheme. The PLL computes the phase displacement of the grid required to achieve orientation and synchronization control. Consequently, it helps in preventing power system distortion due to stator-grid interphase. This paper proposes a new approach that integrates PLL control strategy and a Series Dynamic Braking Resistor (SDBR) to augment the fault ride through capability of a variable speed wind turbine that is DFIG-based. The SDBR helps the post fault recovery of the wind generator. Simulations were run in Power System Computer Aided Design and Electromagnetic Transient state Including DC (PSCAD/EMTDC) to examine severe fault conditions, and to test the robustness of the controllers employed. The results show that the proposed hybrid control strategy aids the fast recovery of the DFIG wind generator variables during fault conditions.

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Modeling and Analysis of an Optically-Actuated, Bistable MEMS Device

Journal of Computational and Nonlinear Dynamics ◽

10.1115/1.4005080 ◽

2012 ◽

Vol 7 (2) ◽

Cited By ~ 5

Author(s):

Vijay Kumar ◽

Jeffrey F. Rhoads

Keyword(s):

Transient Behavior ◽

Distributed Parameter ◽

Mems Devices ◽

Lumped Mass ◽

Modeling And Analysis ◽

Mems Switch ◽

The Rich ◽

Predictive Design ◽

Commercial Applications ◽

Excitation Parameters

Bistable microsystems have drawn considerable interest from the MEMS/NEMS research community not only due to their broad applicability in commercial applications, such as switching, but also because of the rich dynamic behavior they commonly exhibit. While a number of prior investigations have studied the dynamics of bistable microsystems, comparatively few works have sought to characterize their transient behavior. The present effort seeks to address this through the modeling and analysis of an optically-actuated, bistable MEMS switch. This work begins with the development of a distributed-parameter representation for the system, which is subsequently reduced to a lumped-mass analog and analyzed through the use of numerical simulation. The influence of various system and excitation parameters, including the applied axial load and optical actuation profile, on the system’s transient response is then investigated. Ultimately, the methodologies and results presented herein should provide for a refined predictive design capability for optically-actuated, bistable MEMS devices.

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The Energy Compensation of the HRG Based on the Double-Frequency Parametric Excitation of the Discrete Electrode

Sensors ◽

10.3390/s20123549 ◽

2020 ◽

Vol 20 (12) ◽

pp. 3549

Author(s):

Wanliang Zhao ◽

Hao Yang ◽

Fucheng Liu ◽

Yan Su ◽

Lijun Song

Keyword(s):

Parametric Excitation ◽

Dynamical Equation ◽

Dynamic Performance ◽

Free Precession ◽

Double Frequency ◽

Energy Compensation ◽

Hemispherical Resonator ◽

The Stability ◽

Resonator Vibration ◽

Excitation Parameters

In this study, for energy compensation in the whole-angle control of Hemispherical Resonator Gyro (HRG), the dynamical equation of the resonator, which is excited by parametric excitation of the discrete electrode, is established, the stability conditions are analyzed, and the method of the double-frequency parametric excitation by the discrete electrode is derived. To obtain the optimal parametric excitation of the resonator, the total energy stability of the resonator is simulated for the evolution of the resonator vibration with different excitation parameters and the free precession of the standing wave by the parametric excitation. In addition, the whole-angle control of the HRG is designed, and the energy compensation of parametric excitation is proven by the experiments. The results of the experiments show that the energy compensation of the HRG in the whole-angle control can be realized using discrete electrodes with double-frequency parametric excitation, which significantly improves the dynamic performance of the whole-angle control compared to the force-to-rebalance.

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General Method for Analyzing Refractory-Metal Alloys Using the Vacuum-Cup Electrode

Applied Spectroscopy ◽

10.1366/000370266774386443 ◽

1966 ◽

Vol 20 (6) ◽

pp. 400-403 ◽

Cited By ~ 5

Author(s):

Elizabeth C. Leao ◽

E. W. Hobart ◽

D. E. Fornwalt

Keyword(s):

Sulfuric Acid ◽

Refractory Metal ◽

Metal Alloys ◽

Sample Weight ◽

Coefficients Of Variation ◽

Permit Application ◽

Refractory Metal Alloys ◽

Excitation Parameters ◽

Oxalic Acids ◽

General Method

The application of the vacuum-cup electrode to the spectrographs analysis of solutions of refractory-metal alloys is described. Both citric and oxalic acids in 5% sulfuric acid solution served as suitable completing agents. The absence of interelement effects is demonstrated. Alternate sets of excitation parameters and variation of sample weight and aliquot sizes permit application of the technique to a broad range of element concentrations. Typical coefficients of variation of results obtained by the method are between 3% and 4%.

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Concerning a relationship between long-range ring proton – methyl proton coupling constants and mobile bond order

Canadian Journal of Chemistry ◽

10.1139/v68-106 ◽

1968 ◽

Vol 46 (4) ◽

pp. 654-656 ◽

Cited By ~ 7

Author(s):

D. J. Blears ◽

S. S. Danyluk ◽

T. Schaefer

Keyword(s):

Linear Relationship ◽

Long Range ◽

Bond Order ◽

Coupling Constants ◽

Methyl Proton ◽

Methyl Group ◽

Potential Barriers ◽

Proton Coupling ◽

Induced Changes ◽

Excitation Parameters

Long-range proton – methyl proton coupling constants in propene, mesitylene, 9-methylphenanthrene, and acenaphthene appear to be linearly related to the square of the mobile bond order between the carbon atoms bonded to the methyl group and the proton. However, substituent-induced changes in the charge on and hybridization state of the carbon atoms, in excitation parameters and in potential barriers to rotation of the methyl group, may also affect the coupling. Such changes must be considered in the application of a possible linear relationship.

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The spiral structure of our Milky Way

Proceedings of the International Astronomical Union ◽

10.1017/s1743921313000665 ◽

2012 ◽

Vol 8 (S292) ◽

pp. 106-106

Author(s):

L. G. Hou ◽

J. L. Han

Keyword(s):

Milky Way ◽

Spiral Structure ◽

Hii Regions ◽

Giant Molecular Clouds ◽

Constant Weight ◽

Spiral Arms ◽

Flat Rotation Curve ◽

Methanol Masers ◽

The Masses ◽

Excitation Parameters

AbstractThe spiral structure of our Milky Way has not yet been well outlined. HII regions, giant molecular clouds (GMCs) and 6.7-GHz methanol masers are primary tracers for spiral arms. We collect and update the database of these tracers which has been used in Hou et al. (2009) for the spiral arms.The new database consists of ∼ 2000 HII regions, ∼ 1300 GMCs and ∼ 800 methanol masers (6.7 GHz). If the photometric or trigonometric distance for any tracer is available from the literature, we will adopt it. Otherwise, we have to use the kinematic distance. We modify the VLSR according to the newly determined solar motions (U0 = 10.27 km s−1, V0 = 15.32 km s−1 and W0 = 7.74 km s−1, Schönrich et al. 2010), then calculate the kinematic distances with a flat rotation curve (R0 = 8.3 kpc, θ0 = 239 km s−1, Brunthaler et al. 2011). Very important step is that we weight tracers according to the excitation parameters of HII regions or the masses of GMCs, and a constant weight for masers. All three kinds of tracers are used together to outline the spiral structure (Fig. 1). A contour and gray map is constructed after we made a Gaussian extension for the tracers with the amplitude of weighting parameter.

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Identification of Physical and Excitation Parameters of Under-Chassis Equipment for Railway Vehicles

Journal of Vibration and Acoustics ◽

10.1115/1.4046129 ◽

2020 ◽

Vol 142 (3) ◽

Author(s):

Jiangxue Chen ◽

Dao Gong ◽

Jinsong Zhou ◽

Wenjing Sun ◽

Yu Sun ◽

...

Keyword(s):

Parameter Identification ◽

Vehicle Body ◽

Single Frequency ◽

Physical Parameters ◽

Acceleration Response ◽

Vibration Acceleration ◽

Excitation Parameter ◽

Identification Error ◽

Identification Method ◽

Excitation Parameters

Abstract The accuracy of the physical parameters and excitation parameters of the under-chassis equipment has a significant impact on investigations of the coupled vibration of the vehicle body and the under-chassis equipment. In this study, an equipment vibration isolator test bench is used to develop a physical parameter identification method based on the free vibration acceleration response of the equipment and an excitation parameter identification method based on the forced vibration acceleration response. The equipment mass parameter and the center of the gravity position parameter can be obtained first through a static load test, and then, the inertia parameters can be obtained through a dynamic test. Identification of the excitation parameters of the equipment is based on the physical parameters and the acceleration response. The accuracy of the physical parameters directly affects the excitation parameter identification results. The larger the frequency ratio, the smaller the identification error will be, and the larger the damping ratio, the larger the identification error will be. The identification test results of single-frequency excitation and multifrequency excitation show that the proposed excitation parameter identification method has high accuracy.

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