A Wide Range Frequency Coherent Modulation Control Based on Modal Coupling Effect in MEMS Resonators

2021 ◽  
Author(s):  
Kuo Lu ◽  
Xin Zhou ◽  
Qingsong Li ◽  
Kai Wu ◽  
Yongmeng Zhang ◽  
...  
Keyword(s):  
Coupling Effect ◽  
Mems Resonators ◽  
Wide Range ◽  
Modal Coupling ◽  
Modulation Control ◽  
Coherent Modulation

scholarly journals Modal Coupling Effect in a Novel Nonlinear Micromechanical Resonator

Micromachines ◽  
2020 ◽  
Vol 11 (5) ◽  
pp. 472
Author(s):  
Kuo Lu ◽  
Qingsong Li ◽  
Xin Zhou ◽  
Guoxiong Song ◽  
Kai Wu ◽  
...  
Keyword(s):  
Cavity Mode ◽  
Coupling Effect ◽  
Micromechanical Resonators ◽  
Mechanical Coupling ◽  
Wide Range ◽  
Modal Coupling ◽  
Dynamical Coupling ◽  
Electrostatic Coupling ◽  
Stiffness Softening ◽  
Hardening Condition

Capacitive micromechanical resonators share electrodes with the same bias voltage, resulting in the occurrence of electrostatic coupling between intrinsic modes. Unlike the traditional mechanical coupling, the electrostatic coupling is determined by the structural electric potential energy, and generally, it only occurs when the coupling modes operate in nonlinear regions. However, previous electrostatic coupling studies mainly focus on the stiffness softening region, with little attention on the opposite stiffness hardening condition. This paper presents a study on the electrostatic modal coupling effect in the stiffness hardening region. A novel capacitive micromechanical resonator with different modal nonlinearities is designed and fabricated. It is demonstrated that activating a cavity mode can shift the fundamental resonance of the manipulated mode by nearly 90 times its mechanical bandwidth. Moreover, the frequency shifting direction is found to be related to the manipulated mode’s nonlinearity, while the frequency hopscotch is determined by the cavity mode’s nonlinearity. The electrostatic coupling has been proven to be an efficient and tunable dynamical coupling with great potential for tuning the frequency in a wide range. The modal coupling theory displayed in this paper is suitable for most capacitive resonators and can be used to improve the resonator’s performance.

scholarly journals Controlling Resonator Nonlinearities and Modes through Geometry Optimization

Micromachines ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 1381
Author(s):  
Amal Z. Hajjaj ◽  
Nizar Jaber
Keyword(s):  
Axial Stress ◽  
Geometry Optimization ◽  
Beam Equation ◽  
Design Parameters ◽  
Dynamical Response ◽  
Successful Implementation ◽  
Shape Effect ◽  
Mems Resonators ◽  
Wide Range ◽  
The Galerkin Method

Controlling the nonlinearities of MEMS resonators is critical for their successful implementation in a wide range of sensing, signal conditioning, and filtering applications. Here, we utilize a passive technique based on geometry optimization to control the nonlinearities and the dynamical response of MEMS resonators. Also, we explored active technique i.e., tuning the axial stress of the resonator. To achieve this, we propose a new hybrid shape combining a straight and initially curved microbeam. The Galerkin method is employed to solve the beam equation and study the effect of the different design parameters on the ratios of the frequencies and the nonlinearities of the structure. We show by adequately selecting the parameters of the structure; we can realize systems with strong quadratic or cubic effective nonlinearities. Also, we investigate the resonator shape effect on symmetry breaking and study different linear coupling phenomena: crossing, veering, and mode hybridization. We demonstrate the possibility of tuning the frequencies of the different modes of vibrations to achieve commensurate ratios necessary for activating internal resonance. The proposed method is simple in principle, easy to fabricate, and offers a wide range of controllability on the sensor nonlinearities and response.

AN APPROXIMATION METHOD FOR COMPUTING THE DYNAMIC RESPONSES AND EQUIVALENT STATIC WIND LOADS OF LARGE-SPAN ROOF STRUCTURES

2010 ◽  
Vol 10 (05) ◽  
pp. 1141-1165 ◽  
Author(s):  
XUANYI ZHOU ◽  
MING GU
Keyword(s):  
Coupling Effect ◽  
Coupling Factor ◽  
Dynamic Responses ◽  
Wind Loads ◽  
Inertia Force ◽  
Large Span ◽  
Load Distributions ◽  
Modal Coupling ◽  
Vibration Responses ◽  
Equivalent Static Wind Loads

Due to their sensitivity to wind, the design of large-span roofs is generally governed by wind loads. For some flexible large-span roofs with low damping and concentrated modes, the effect of multi-mode coupling should be taken into account in computing the resonant buffeting response and equivalent static wind loads. Such an effect is considered by the modified SRSS method in this paper via the modal coupling factor. Based on the same SRSS method, the equivalent static wind loads combining the mean, background, and resonant components, are computed. Particularly, the background and resonant components are computed by the LRC method and the equivalent inertia force method considering the modal coupling effects by the modified SRSS method, respectively. The method is then applied to the computation of wind-induced vibration responses and equivalent static wind load distributions of a real large-span roof. The results show that the modal coupling effect on the resonant component can be identified by the present method with high accuracy.

Design of Decoupled Mechanical Shim Control System for a Generation III+ Pressurized Water Reactor Based on Feedforward Compensation and Multimodel Approach

2018 ◽  
Author(s):  
Pengfei Wang ◽  
Xinyu Wei ◽  
Fuyu Zhao
Keyword(s):  
Control System ◽  
Power Distribution ◽  
Coupling Effect ◽  
Control Performance ◽  
Pressurized Water Reactor ◽  
Pressurized Water ◽  
Decoupling Method ◽  
Control Rod ◽  
Wide Range ◽  
Decoupled Control

The advanced Mechanical Shim (MSHIM) core control strategy employs two separate and independent control rod banks, namely the MSHIM control banks (M-banks) and axial offset (AO) control bank (AO-bank), for automatic reactivity/temperature and axial power distribution control respectively. The M-banks and AO-bank are independently controlled by two closed-loop controllers called the coolant average temperature (Tavg) controller and AO controller. Since the movement of M-banks and AO-bank can both affect the Tavg and AO, the Tavg controller is coupled with the AO controller. In order to avoid the interference between the two controllers, the MSHIM control system adopts an interlock design between them to avoid the simultaneous movement of the M-banks and AO-bank and make sure the priority of the M-bank movement. This design can enhance the stability of the MSHIM control system. However, the control performance is degraded at the same time. In the present study, the feedforward compensation decoupling method and multimodel approach are used to eliminate the coupling effect between the two controllers in the MSHIM control system during a wide range of power maneuvers. A multiple feedforward compensation system is designed with integration of feedforward compensators for the Tavg and AO controllers at five power levels using the multimodel approach. By implementing it in the MSHIM control system, the interlock between the M-banks and AO-bank can be released to realize the independent and decoupled control between Tavg and AO. The effectiveness of the decoupled MSHIM control system is verified by comparing its control performance with that of the original MSHIM control system during typical load change transients of the AP1000 reactor. The obtained results show that superior and decoupled control of Tavg and AO can be achieved with the proposed decoupled MSHIM control system.

On an Axisymmetric Coupled Thermal Stress Problem in a Finite Circular Cylinder

1983 ◽  
Vol 50 (1) ◽  
pp. 116-122 ◽  
Author(s):  
Y. Takeuti ◽  
R. Ishida ◽  
Y. Tanigawa
Keyword(s):  
Thermal Stress ◽  
Circular Cylinder ◽  
Thermal Stresses ◽  
Coupling Effect ◽  
Three Dimensions ◽  
Thermomechanical Coupling ◽  
Coupling Term ◽  
Wide Range ◽  
A New Technique ◽  
Transient Thermal

This paper presents a general treatment of the transient thermal stresses of a finite circular cylinder with consideration of the thermomechanical coupling effect using a new technique. The method used is quite useful for the solution of a wide range of transient thermal stress problems in two or three dimensions. From numerical results, we can find that there is a clear effect on the thermal stress distribution when the coupling term is taken into account.

scholarly journals Monte Carlo and Experimental Magnetic Studies of Molecular Spintronics Devices

NANO ◽  
2015 ◽  
Vol 10 (04) ◽  
pp. 1550056 ◽  
Author(s):  
Pawan Tyagi ◽  
Christopher D'Angelo ◽  
Collin Baker
Keyword(s):  
Monte Carlo ◽  
Magnetic Properties ◽  
Coupling Effect ◽  
Experimental Studies ◽  
Magnetic Tunnel Junction ◽  
Magnetic Interactions ◽  
Magnetic Studies ◽  
Magnetic Molecules ◽  
Wide Range ◽  
Different Temperatures

Molecule-based spintronics devices (MSDs) are highly promising candidates for discovering advanced logic and memory computer units. An advanced MSD will require the placement of paramagnetic molecules between the two ferromagnetic (FM) electrodes. Due to extreme fabrication challenges, only a couple of experimental studies could be performed to understand the effect of magnetic molecules on the overall magnetic and transport properties of MSDs. To date, theoretical studies mainly focused on charge and spin transport aspects of MSDs; there is a dearth of knowledge about the effect of magnetic molecules on the magnetic properties of MSDs. This paper investigates the effect of magnetic molecules, with a net spin, on the magnetic properties of 2D MSDs via Monte Carlo (MC) simulations. Our MC simulations encompass a wide range of MSDs that can be realized by establishing different kinds of magnetic interactions between molecules and FM electrodes at different temperatures. The MC simulations show that ambient thermal energy strongly influenced the molecular coupling effect on the MSD. We studied the nature and strength of molecule couplings (FM and antiferromagnetic) with the two electrodes on the magnetization, specific heat and magnetic susceptibility of MSDs. For the case when the nature of molecule interaction was FM with one electrode and antiferromagnetic with another electrode the overall magnetization shifted toward zero. In this case, the effect of molecules was also a strong function of the nature and strength of direct coupling between FM electrodes. In the case when molecules make opposite magnetic couplings with the two FM electrodes, the MSD model used for MC studies resembled with the magnetic tunnel junction based MSD. The experimental magnetic studies on these devices are in agreement with our theoretical MC simulations results. Our MC simulations will enable the fundamental understanding and designing of a wide range of novel spintronics devices utilizing a variety of molecules, nanoclusters and quantum dots as the device elements.

Analytical and experimental studies on midstory isolated buildings with modal coupling effect

2012 ◽  
Vol 42 (2) ◽  
pp. 201-219 ◽  
Author(s):  
Shiang-Jung Wang ◽  
Jenn-Shin Hwang ◽  
Kuo-Chun Chang ◽  
Meng-Hui Lin ◽  
Bo-Han Lee
Keyword(s):  
Coupling Effect ◽  
Experimental Studies ◽  
Modal Coupling

scholarly journals Designing an uninterruptible power supply based on the high efficiency push–pull converter

2013 ◽  
Vol 16 (3) ◽  
pp. 29-40
Author(s):  
Phuong Minh Le ◽  
Dzung Quoc Phan ◽  
Huy Minh Nguyen ◽  
Phong Hoai Nguyen
Keyword(s):  
Power Supply ◽  
High Efficiency ◽  
Harmonic Distortion ◽  
Original System ◽  
Uninterruptible Power Supply ◽  
Switching Power ◽  
Wide Range ◽  
Uninterruptible Power ◽  
Modulation Control ◽  
High Level

This paper presents an implementation of the DC/DC push–pull converter for an uninterruptible power supply (UPS). Some classical DC/DC converters are presented and analyzed for pointing out their advantages and drawbacks. Besides, an original system based on a push-pull converter associated with a dynamic modulation control is chosen. The main advantage is the possibility to control the delivered electric power in a wide range from very low level to high level of voltage within the same basic architecture. It can reduce the switching power losses and increase the power conversion efficiency. This paper proposed a new control scheme of the DC/DC converter and DC/AC inverter. The suggested system consists of a high efficiency DC/DC converter and a singlephase DC/AC inverter has been simulated using Matlab/Simulink and designed basing on the DSP TMS320F28027. Both results show high performances of the DC link and AC load voltages, when load changes from zero to rated. The performance of the proposed system has been verified through a 1kW prototype of the system for a 50 Hz/220-230 VAC load sourcing by two series connected batteries of 12V. The proposed DC/DC converter achieves a high efficiency of 93.0%. The system including the DC/DC converter and DC/AC inverter achieves an efficiency of 91.2% and Total Harmonic Distortion (THD) of AC load voltage reached 1.9%.

A Monte Carlo Study of Molecular Spintronics Devices

2013 ◽  
Author(s):  
Pawan Tyagi ◽  
Christopher D’Angelo
Keyword(s):  
Monte Carlo ◽  
Magnetic Properties ◽  
Exchange Coupling ◽  
Coupling Effect ◽  
Experimental Studies ◽  
Magnetic Molecules ◽  
Molecular Spintronics ◽  
Ferromagnetic Electrodes ◽  
Wide Range ◽  
And Control

Molecular spintronics devices (MSDs) are capable of harnessing the controllable transport and magnetic properties of molecular device elements and are highly promising candidates for revolutionizing computer logic and memory. These advanced MSD can enable the next generation of instrumentation and control devices for the wide range of mechanical engineering systems. A MSD is typically produced by placing magnetic molecule(s) between the two ferromagnetic electrodes. Recent experimental studies show that some magnetic molecules produced unprecedented strong exchange couplings between the two ferromagnetic electrodes, leading to intriguing magnetic and transport properties in a MSD. Future development of MSDs will critically depend on obtaining an in-depth understanding of the molecule induced exchange coupling, and its impact on MSD’s switchability, functional temperature range, stability etc. However, the large size of MSD systems and unsuitable device designs are the two biggest hurdles in theoretical and experimental studies of magnetic attributes produced by molecules in a MSD. This research theoretically studies the MSD by performing Monte Carlo simulations (MCS). The effect of magnetic molecule induced exchange coupling was studied at different temperature and for different device sizes — represented by a 2D Ising model. Our MCS shows that thermal energy of the MSD strongly influenced the molecular coupling effect. We studied the effect of a wide range of molecule-metal electrode couplings on the fundamental properties of MSDs. If molecules induced exchange coupling increased beyond a threshold limit a MSD acquired dramatically new attributes. Our MCS exhibited that the transition points in MSD’s magnetic properties was the interplay of temperature and molecular coupling strength. These simulations will allow the understanding of fundamental device mechanisms behind the functioning of novel MSDs. Our MSD model represents a myriad of magnetic molecules and ferromagnets combinations promising for realizing experimental MSDs. These MCS will also assist in designing new class of MSDs with desired attributes for advanced computers and control systems.

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