scholarly journals Performance of Quad Mass Gyroscope in the Angular Rate Mode

Micromachines ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 266
Author(s):  
Sina Askari ◽  
Mohammad Asadian ◽  
Andrei Shkel
Keyword(s):  
Angular Rate ◽  
Open Loop ◽  
Q Factor ◽  
Control Loops ◽  
Noise Characteristics ◽  
Trade Offs ◽  
Power Spectral ◽  
Mode Of Operation ◽  
Q Factors ◽  
Bias Instability

In this paper, the characterization and analysis of a silicon micromachined Quad Mass Gyroscope (QMG) in the rate mode of operation are presented. We report on trade-offs between full-scale, linearity, and noise characteristics of QMGs with different Q-factors. Allan Deviation (ADEV) and Power Spectral Density (PSD) analysis methods were used to evaluate the performance results. The devices in this study were instrumented for the rate mode of operation, with the Open-Loop (OL) and Force-to-Rebalance (FRB) configurations of the sense mode. For each method of instrumentation, we presented constraints on selection of control parameters with respect to the Q-factor of the devices. For the high Q-factor device of over 2 million, and uncompensated frequency asymmetry of 60 mHz, we demonstrated bias instability of 0.095∘/hr and Angle Random Walk (ARW) of 0.0107∘/hr in the OL mode of operation and bias instability of 0.065∘/hr and ARW of 0.0058∘/hr in the FRB mode of operation. We concluded that in a realistic MEMS gyroscope with imperfections (nearly matched, but non-zero frequency asymmetry), a higher Q-factor would increase the frequency stability of the drive axis resulting in an improved noise performance, but has challenges in implementation of digital control loops.

scholarly journals In-Band Pumped Thulium-Doped Tellurite Glass Microsphere Laser

2021 ◽  
Vol 11 (12) ◽  
pp. 5440
Author(s):  
Elena A. Anashkina ◽  
Vitaly V. Dorofeev ◽  
Alexey V. Andrianov
Keyword(s):  
Tellurite Glass ◽  
High Gain ◽  
Glass Microsphere ◽  
Ion Concentration ◽  
Laser Generation ◽  
Q Factor ◽  
Narrow Line ◽  
Simple Theoretical Model ◽  
Q Factors ◽  
Doped Glass

Microresonator-based lasers in the two-micron range are interesting for extensive applications. Tm3+ ions provide high gain; therefore, they are promising for laser generation in the two-micron range in various matrices. We developed a simple theoretical model to describe Tm-doped glass microlasers generating in the 1.9–2 μm range with in-band pump at 1.55 μm. Using this model, we calculated threshold pump powers, laser generation wavelengths and slope efficiencies for different parameters of Tm-doped tellurite glass microspheres such as diameters, Q-factors, and thulium ion concentration. In addition, we produced a 320-μm tellurite glass microsphere doped with thulium ions with a concentration of 5·1019 cm−3. We attained lasing at 1.9 μm experimentally in the produced sample with a Q-factor of 106 pumped by a C-band narrow line laser.

AC Loss Modeling in Ba0.5Sr0.5TiO3 Using Dielectric Relaxation

2004 ◽  
Vol 833 ◽  
Author(s):  
Nadia K. Pervez ◽  
Jiwei Lu ◽  
Susanne Stemmer ◽  
Robert A. York
Keyword(s):  
Dielectric Loss ◽  
Dielectric Relaxation ◽  
Power Law ◽  
Fractional Power ◽  
Ac Loss ◽  
Dielectric Susceptibility ◽  
Network Analyzer ◽  
Q Factor ◽  
Relaxation Model ◽  
Q Factors

ABSTRACTIn universal relaxation, a material's complex dielectric susceptibility follows a fractional power law f1-n where 0 < n < 1 over multiple decades of frequency. In a variety of materials, including Ba0.5Sr0.5Ti03, dielectric relaxation has been observed to follow this universal relaxation model with values of n close to 1. In this work we have shown that the universal relaxation model can be used to calculate dielectric loss even when n is very close to 1. Our calculated Q-factors agree with measured values at 1 MHz; this agreement suggests that this technique may be used for higher frequencies where network analyzer measurements and electrode parasitics complicate Q-factor determination.

scholarly journals The connection between the 15 GHz radio and gamma-ray emission in blazars

2014 ◽  
Vol 10 (S313) ◽  
pp. 17-20
Author(s):  
W. Max-Moerbeck ◽  
J. L. Richards ◽  
T. Hovatta ◽  
V. Pavlidou ◽  
T. J. Pearson ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Statistical Tests ◽  
High Energy ◽  
Light Curves ◽  
Owens Valley ◽  
Noise Characteristics ◽  
Power Spectral ◽  
Emission Models ◽  
Gamma Ray Emission ◽  
Many Sources

AbstractSince mid-2007 we have carried out a dedicated long-term monitoring programme at 15 GHz using the Owens Valley Radio Observatory 40 meter telescope (OVRO 40m). One of the main goals of this programme is to study the relation between the radio and gamma-ray emission in blazars and to use it as a tool to locate the site of high energy emission. Using this large sample of objects we are able to characterize the radio variability, and study the significance of correlations between the radio and gamma-ray bands. We find that the radio variability of many sources can be described using a simple power law power spectral density, and that when taking into account the red-noise characteristics of the light curves, cases with significant correlation are rare. We note that while significant correlations are found in few individual objects, radio variations are most often delayed with respect to the gamma-ray variations. This suggests that the gamma-ray emission originates upstream of the radio emission. Because strong flares in most known gamma-ray-loud blazars are infrequent, longer light curves are required to settle the issue of the strength of radio-gamma cross-correlations and establish confidently possible delays between the two. For this reason continuous multiwavelength monitoring over a longer time period is essential for statistical tests of jet emission models.

scholarly journals Grid-Forming Control Suitable for Large Power Transmission System Applications

2021 ◽  
Author(s):  
Taoufik QORIA ◽  
Xavier Guillaud
Keyword(s):  
Power Transmission ◽  
Stability Margin ◽  
Open Loop ◽  
System Stability ◽  
Test Cases ◽  
Large Power ◽  
Control Loops ◽  
Power Inverters ◽  
Practical Feasibility ◽  
Typical Solution

The inner cascaded structure-based grid-forming control is a typical solution used to impose an AC voltage magnitude across the output filters of the power inverters. Yet, because of the limited inverter’s bandwidth resulting from the low-switching frequencies in transmission systems, the interaction (i.e., coupling) between control loops is highly likely making the understanding of the system behavior complex and its simplification unaffordable and may also lead to instabilities. The novelty of this paper consists in proposing a simple open-loop direct voltage control to reduce the number of the inner control regulators, and thereby guaranteeing a decoupling between the inner and outer control layers as well as increasing the system stability margin. This statement is well supported with a small-signal analysis and progressive order model reduction of the system. The overall concept is validated in a 10-bus grid case while comparing the EMT and Phasor-based simulations. The practical feasibility of the control itself is experimentally proved with different test cases.

A Parametrically Amplified MEMS Gyroscope

2010 ◽  
Vol 2010 (DPC) ◽  
pp. 001322-001334
Author(s):  
Barry J. Gallacher ◽  
Z. X. Hu ◽  
J. S. Burdess ◽  
K. M. Harish
Keyword(s):  
Open Loop ◽  
Parametric Amplification ◽  
Vibration Modes ◽  
Q Factor ◽  
Amplitude Control ◽  
Mems Gyroscope ◽  
Primary Mode ◽  
Harmonic Forcing ◽  
Control Schemes ◽  
Order Of Magnitude

The applicability of parametric amplification of either the primary and secondary vibration modes of a MEMS gyroscope, shown in Fig.1 is investigated experimentally in this paper. All control schemes have been implemented digitally onto a SHARC DSP development board. Parametric gains in excess of 80, which correspond to multiplication of the Q-factor by a factor of 80, are demonstrated experimentally for open-loop operation of the primary mode and are shown in Fig. 2. For open-loop operation it is shown that amplitude limiting nonlinearities become important as the vibration amplitude increases (see Figs.3) and that parametric amplification in excess of 80 can be only be achieved by further reducing the harmonic forcing amplitude. In many applications it is desirable to have as high a Q-factor as possible. The rate gyroscope is one application were active control of the Q-factor is extremely pertinent. If applied to the primary mode then it permits reduced forcing levels and hence contamination from “feedthrough”. If applied to the sense mode then the Coriolis force is effectively amplified. Parametric amplification of the secondary mode of the gyroscope is a challenging problem but it has the potential to improve the performance of MEMS rate gyroscope but an order of magnitude. In operation as a rate gyroscope it is important to maintain the amplitude of the primary mode of vibration at a constant level. For the case of a parametrically amplified primary mode the amplitude control circuit automatically adjusts the parametric excitation parameters to ensure the required parametric gain is achieved whilst at the same time reducing the amplitude of the harmonic forcing. In closed loop parametric amplification of the primary mode by a factor 20 have been demonstrated. Experimental results obtained from the amplified primary mode are shown in Fig.4.

Multi-Frequency Atomic Force Microscopy Combining Amplitude- and Frequency-Modulation Techniques

2012 ◽  
Vol 1422 ◽  
Author(s):  
Santiago D. Solares ◽  
Gaurav Chawla
Keyword(s):  
Atomic Force Microscopy ◽  
Frequency Modulation ◽  
Complementary Information ◽  
Control Loops ◽  
Force Microscopy ◽  
Atomic Force ◽  
Mode Of Operation ◽  
Modulation Techniques ◽  
Different Response ◽  
Amplitude And Frequency Modulation

ABSTRACTMulti-frequency atomic force microscopy (AFM) offers additional response signals in comparison to traditional dynamic AFM. Furthermore, depending on the mode of operation used, the higher eigenmode responses are generally not directly influenced by the topographical acquisition control loops, such that they can explore a fuller range of tip-sample interactions. In this work we describe the implementation of multi-frequency imaging schemes that enable the acquisition of topographical, phase and frequency shift contrast in tapping-mode operation. This type of characterization can be especially useful for soft, highly dissipative samples, such as polymers, for which the various response channels can exhibit significantly different response, thus providing complementary information. We discuss typical results obtained as well as important challenges that need to be addressed in order to develop a fully quantitative technique.

Seismic noise characteristics in Chinese mainland

2020 ◽  
Author(s):  
Fang Wang ◽  
Weitao Wang ◽  
Jianfeng Long ◽  
Leiyu Mu
Keyword(s):  
Noise Level ◽  
Seismic Noise ◽  
Vertical Component ◽  
Chinese Mainland ◽  
Low Noise ◽  
Noise Characteristics ◽  
Power Spectral ◽  
Short Period ◽  
Power Spectral Densities ◽  
Noise Models

&lt;p&gt;Using the three-component continuous waveform recordings of 880 broadband seismic stations in China Seismic Network from January 2014 to December 2015, we calculated power spectral densities and probability density functions over the entire period for each station&amp;#65292;and&amp;#160; investigated the characteristics of seismic noise in Chinese mainland. The deep analysis on the vertical recordings&amp;#160; indicates that the spatial distribution of noise levels is characterized by obvious zoning for different period bands.&amp;#160; Densely populated areas have higher short-period noise level than sparsely populated ones, suggesting that short-period noise is related to the intensity distribution of human activities such as transportation and industry. Meanwhile&amp;#65292;the short-period noise level near the basin is higher than the mountainous areas&amp;#65292;which is probably caused by the amplification effect of the sedimentary layer. The microseism energy&amp;#160; gradually decreases from the southeastern coastal lines to the inland regions. Furthermore, horizontal-component noise level&amp;#160; showed a striking constrast with the vertical component at microseismic and long-period bands. In consideration of&amp;#160; the zoning chracteristics and the need of seismic observations, high and low noise models were&amp;#160; acquired for each network , which were proved to be a more effective tool to identify locally abnormal signals including earthquake, instrumental error and various distrubance compared with the global new high and low model.&amp;#160;&lt;/p&gt;

scholarly journals High Quality-Factor Dual-Band Fano Resonances Induced by Bound States in The Continuum Using A Planar Nanohole Slab

2021 ◽  
Author(s):  
Tian Sang ◽  
Qing Mi ◽  
Yao Pei ◽  
Chaoyu Yang ◽  
Shi Li ◽  
...  
Keyword(s):  
Bound States ◽  
Near Field ◽  
Dual Band ◽  
Q Factor ◽  
Fano Resonances ◽  
High Quality ◽  
Potential Applications ◽  
Q Factors ◽  
Symmetry Protected ◽  
The Continuum

Abstract In photonics, it is essential to achieve high quality (Q)-factor resonances to enhance light-mater interactions for improving performances of optical devices. Herein, we demonstrate that high Q-factor dual-band Fano resonances can be achieved by using a planar nanohole slab (PNS) based on the excitation of bound states in the continuum (BICs). By shrinking or expanding the tetramerized holes of the superlattice of the PNS, symmetry-protected BICs can be excited and the locations of Fano resonances as well as their Q-factors can be flexibly tuned. Physical mechanisms for the dual-band Fano resonances can be interpreted as the resonant couplings between the electric-toroidal dipoles or the magnetic-toroidal dipoles based on the far-field multiple decompositions and the near-field distributions of the superlattice. The dual-band Fano resonances of the PNS possess polarization independent feature, they can be survived even the geometric parameters of the PNS are significantly altered, making them more suitable for potential applications.

scholarly journals High Q Resonant Graphene Absorber with Lossless Phase Change Material Sb2S3

Nanomaterials ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 2820
Author(s):  
Qi Meng ◽  
Xingqiao Chen ◽  
Wei Xu ◽  
Zhihong Zhu ◽  
Shiqiao Qin ◽  
...  
Keyword(s):  
Phase Change ◽  
Phase Change Material ◽  
Near Infrared ◽  
Infrared Region ◽  
Q Factor ◽  
Thermal Emitters ◽  
Crystallization Fraction ◽  
Q Factors ◽  
Refractive Index Grating ◽  
Change Material

Graphene absorbers have attracted lots of interest in recent years. They provide huge potential for applications such as photodetectors, modulators, and thermal emitters. In this letter, we design a high-quality (Q) factor resonant graphene absorber based on the phase change material Sb2S3. In the proposed structure, a refractive index grating is formed at the subwavelength scale due to the periodical distributions of amorphous and crystalline states, and the structure is intrinsically flat. The numerical simulation shows that nearly 100% absorption can be achieved at the wavelength of 1550 nm, and the Q factor is more than hundreds due to the loss-less value of Sb2S3 in the near-infrared region. The absorption spectra can be engineered by changing the crystallization fraction of the Sb2S3 as well as by varying the duty cycle of the grating, which can be employed not only to switch the resonant wavelength but also to achieve resonances with higher Q factors. This provides a promising method for realizing integrated graphene optoelectronic devices with the desired functionalities.

scholarly journals Interactive Tuning Tool of Proportional-Integral Controllers for First Order Plus Time Delay Processes

Symmetry ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 569 ◽  
Author(s):  
Mario Ruz ◽  
Juan Garrido ◽  
Francisco Vazquez ◽  
Fernando Morilla
Keyword(s):  
Time Delay ◽  
Controller Design ◽  
Industrial Process ◽  
Implementation Process ◽  
Open Loop ◽  
Practical Case ◽  
Control Loops ◽  
Proportional Integral ◽  
First Order ◽  
Tuning Rules

Engineering education and, particularly, control engineering, has shown growth in research and development activities during last years. Currently, proportional–integral (PI) and proportional–integral–derivative (PID) controllers are the most commonly used in industrial process applications. Nonetheless, it is reported that many of them are badly tuned. From an educational perspective, it is crucial for the student to understand the importance of tuning a control loop correctly. This paper presents an interactive tool focused on the study of PI controllers. The tool provides a set of tuning rules for both open-loop stable and unstable first order plus time delay processes. The different tuning rules can be compared interactively by the user, allowing a critical analysis of basic concepts about stability, robustness, and performance in PI control loops. In addition to educational purposes, the tool has been developed, taking into account practical considerations, such as simulation with a controller discrete implementation, process input saturations, and windup effect. We evaluated students’ achievement in the final examination in the Automatic Control course of the Electronics Engineering degree. Students showed significant improvement in their understanding of PI controller design. A survey and a practical case study were performed to evaluate the effectiveness of the proposed tool.

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