scholarly journals Catalyst State Diagnosis of Three-Way Catalytic Converters Using Different Resonance Parameters—A Microwave Cavity Perturbation Study

Sensors ◽  
2019 ◽  
Vol 19 (16) ◽  
pp. 3559
Author(s):  
Carsten Steiner ◽  
Vladimir Malashchuk ◽  
David Kubinski ◽  
Gunter Hagen ◽  
Ralf Moos
Keyword(s):  
Resonant Frequency ◽  
Quality Factor ◽  
Signal Amplitude ◽  
Oxygen Storage ◽  
Microwave Cavity ◽  
Technical Application ◽  
Gasoline Vehicles ◽  
Relative Change ◽  
Rf Signal ◽  
First Time

Recently, radio frequency (RF) technology was introduced as a tool to determine the oxygen storage level of a three-way catalyst (TWC) for gasoline vehicles. Previous studies on the investigation of commercial catalysts mostly use only the resonant frequency to describe the correlation of oxygen storage level and RF signal. For the first time this study presents a comparison under defined laboratory conditions considering both, resonance frequency and also the quality factor as measurands. Furthermore, various advantages over the sole use of the resonant frequency in the technical application are discussed. Experiments with Ø4.66’’ catalysts and Ø1.66’’ catalyst cores with alternating (rich/lean) gas compositions showed that the relative change in signal amplitude due to a change in oxygen storage is about 100 times higher for the inverse quality factor compared to the resonant frequency. In addition, the quality factor reacts more sensitively to the onset of the oxygen-storage ability, and delivers precise information about the necessary temperature, which is not possible when evaluating the resonant frequency due to the low signal amplitude. As investigations on aged catalysts confirm, the quality factor also provides a new approach to determine operando the ageing state of a TWC.

Influence of Large Water Droplets Passing through Microwave Cavity on Steam Wetness Measurement

2013 ◽  
Vol 339 ◽  
pp. 495-502
Author(s):  
Jiang Bo Qian ◽  
Heng Fan Li ◽  
Zhong He Han
Keyword(s):  
Resonant Frequency ◽  
Quality Factor ◽  
Resonant Cavity ◽  
Great Influence ◽  
Microwave Cavity ◽  
Large Droplet ◽  
Ring Radius ◽  
Secondary Droplets ◽  
Large Water ◽  
Turbine Exhaust

The steam turbine exhaust contains large secondary droplets, and the droplets show an uneven distribution in space and time. It analyzes the change of resonant frequency and quality factor with different sizes and positions of droplets, and analyzes the influence on the steam wetness measurement. The results show that: when the size of resonant cavity is constant, the resonant frequency and quality factor are related to the size and location of water droplet. For the cylindrical cavity whose length is 40mm and radius is 30mm, when large droplet located in the ring (radius is 13.0mm) onxoyplane, it has great influence on wetness measurement, and the influence is greater with larger size of droplet.

scholarly journals Reactive Dual Magnetron Sputtering: A Fast Method for Preparing Stoichiometric Microcrystalline ZnWO4 Thin Films

Surfaces ◽  
2021 ◽  
Vol 4 (2) ◽  
pp. 106-114
Author(s):  
Yannick Hermans ◽  
Faraz Mehmood ◽  
Kerstin Lakus-Wollny ◽  
Jan P. Hofmann ◽  
Thomas Mayer ◽  
...  
Keyword(s):  
Thin Films ◽  
Magnetron Sputtering ◽  
Photoelectron Spectroscopy ◽  
Fast Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Glass Substrates ◽  
Post Annealing ◽  
Rf Signal ◽  
First Time

Thin films of ZnWO4, a promising photocatalytic and scintillator material, were deposited for the first time using a reactive dual magnetron sputtering procedure. A ZnO target was operated using an RF signal, and a W target was operated using a DC signal. The power on the ZnO target was changed so that it would match the sputtering rate of the W target operated at 25 W. The effects of the process parameters were characterized using optical spectroscopy, X-ray diffraction, and scanning electron microscopy, including energy dispersive X-ray spectroscopy as well as X-ray photoelectron spectroscopy. It was found that stoichiometric microcrystalline ZnWO4 thin films could be obtained, by operating the ZnO target during the sputtering procedure at a power of 55 W and by post-annealing the resulting thin films for at least 10 h at 600 °C. As FTO coated glass substrates were used, annealing led as well to the incorporation of Na, resulting in n+ doped ZnWO4 thin films.

A Frequency-Tunable Comb Resonator Using Spring Tension and Compression Effects

2004 ◽  
Author(s):  
Ki Bang Lee ◽  
Albert P. Pisano ◽  
Liwei Lin
Keyword(s):  
Resonant Frequency ◽  
Bias Voltage ◽  
Frequency Tuning ◽  
Electrostatic Force ◽  
Voltage Change ◽  
Tension And Compression ◽  
Frequency Tunable ◽  
Frequency Changes ◽  
Compression Effects ◽  
First Time

A 2μm-thick frequency-tunable microresoantor capable of either increasing or decreasing its resonant frequency by a combination of Joule heating and electrostatic force has been successfully demonstrated for the first time. For the heating voltage increase from 0 to 2V under fixed bias voltage of 40V, the resonant frequency changes from 22.2kHz to 16.2kHz, resulting in the 27% reduction in the resonant frequency. For the bias voltage change from 20V to 40V under the heating voltage of 0V, the resonant frequency increase from 19.0kHz to 23.6kHz, resulting in the 24.2% increase in the resonant frequency. As such, this surface-micromachined microactuator could assist complicated frequency tuning for applications of microsensors and microactuators.

Medium damping influences on the resonant frequency and quality factor of piezoelectric circular microdiaphragm sensors

2011 ◽  
Vol 21 (4) ◽  
pp. 045002 ◽  
Author(s):  
M Olfatnia ◽  
Z Shen ◽  
J M Miao ◽  
L S Ong ◽  
T Xu ◽  
...  
Keyword(s):  
Resonant Frequency ◽  
Quality Factor

A Microcontroller Approach to Measuring Transmissibility of MEMS Devices

2015 ◽  
Vol 2015 (DPC) ◽  
pp. 001564-001593
Author(s):  
Chong Li ◽  
Yixuan Wu ◽  
Haoyue Yang ◽  
Luke L. Jenkins ◽  
Robert N. Dean ◽  
...  
Keyword(s):  
Resonant Frequency ◽  
Quality Factor ◽  
Real Time ◽  
High Speed ◽  
Mechanical Quality Factor ◽  
Quantization Noise ◽  
Mems Devices ◽  
Input And Output ◽  
Mechanical Quality ◽  
Mems Device

The transmissibility reveals two very useful characteristics of a micro-electro-mechanical systems (MEMS) device, the resonant frequency and the mechanical quality factor. Real time knowledge on these two important factors can enhance application performance or avoid potential problems from environmental disturbances due to fabrication tolerances and the resulting operational differences in otherwise identical devices. Expensive laboratory equipment is typically used to measure the transmissibility. However, these test systems are not readily adaptable to field use. Therefore, it is important to be able to measure the transmissibility using a real time technique with a simplified test setup. This study proposes a technique that can compute the transmissibility in real time using a low cost microcontroller. This technique utilizes two laser vibrometers to detect the input and output motions of the proof mass in a MEMS device, which are fed to high speed 500 KHz analog to digital converters (ADC) in the microcontroller. A filtering step is performed to decrease noise. After the sampling and pre-filtering, a Fast Fourier Transform (FFT) is performed to convert the time-domain signals to frequency domain signals. The amplitude of the output signal at each frequency is divided by the amplitude of the corresponding input signal at each frequency to obtain the transmissibility. To overcome the difficulties resulting from measurement and quantization noise, a recursive calculating algorithm and a de-quantization filter are introduced. The recursive calculating process guarantees that the system updates the results continually, which results in a transmissibility plot covering the entire bandwidth. The de-quantization filter considers the validity of the data and performs the transmissibility division step accordingly. A cantilevered structure was chosen as the device-under-test to verify and evaluate this technique. The cantilevered device was attached to an electromechanical shaker system for vibratory stimulation. Two laser vibrometers were used to detect the input and output motion and this data was fed into a microcontroller. The microcontroller was STM32F407, which is 32-bit and 168 MHz controller. The tests demonstrated that this technique can measure the transmissibility and therefore the resonant frequency and mechanical quality factor accurately compared to a professional signal analyzer.

A MEMS PPA Based Active Vibration Isolator - STUDENT AWARD 3RD PLACE $500

2016 ◽  
Vol 2016 (DPC) ◽  
pp. 000853-000880
Author(s):  
Chong Li ◽  
C. Lavinia Elana ◽  
Robert N. Dean ◽  
George T. Flowers
Keyword(s):  
Resonant Frequency ◽  
Quality Factor ◽  
Proof Mass ◽  
Control Voltage ◽  
Stable Range ◽  
Vibration Isolator ◽  
Operating Range ◽  
Stable Operating ◽  
Mass Damper ◽  
Active Vibration

Several types of micro-devices are adversely affected by high frequency mechanical vibrations present in the operating environment. Examples include MEMS vibratory gyroscopes and resonators, and micro-optics. Various types of MEMS vibration isolators have been developed for use in the packaging of these vibration sensitive devices. Passive isolators consist of a spring-mass-damper MEMS device and usually have a very high mechanical quality factor, which makes them susceptible to ringing at the isolator's resonant frequency. Active isolators have been realized by using state sensing of the proof mass motion and feeding one or more of these states back through an actuator to adjust the frequency response of the isolator. For example, the technique known as skyhook damping uses velocity feedback to adjust, and typically increase, the damping of the isolator. Although these technique are doable, they require state sensing or state estimation, with feedback electronics to drive the actuator. A simpler MEMS active vibration isolator architecture employs only a parallel plate actuator (PPA) with the MEMS spring-mass-damper structure. The PPA driven with a DC voltage, in its stable operating range, displaces the proof mass, which results in a change in the effective system spring constant due to the electrostatic spring softening effect. This results in a change in the resonant frequency and the quality factor of the isolator. However, due to the nonlinearities inherent in this type of device, the stable operating range is reduced as the PPA voltage is increased. Furthermore, even when the isolator is stable in steady-state, a sufficiently large transient response can also drive it into the unstable regime, resulting in the electrodes snapping into contact. In this study, the PPA based active vibrator isolator is developed and its performance is evaluated. The characteristics of the transient instability are investigated and its stable range of operation is specified, for booth external disturbances and rapid application of the control voltage. This MEMS PPA based active vibration isolator can improve performance compared to passive isolators, while being much simpler than state feedback active isolators.

Performance Improvement of RF Inductors Using LTCC Technology

2011 ◽  
Vol 2011 (CICMT) ◽  
pp. 000054-000058 ◽  
Author(s):  
Goran Radosavljević ◽  
Andrea Marić ◽  
Walter Smetana ◽  
Ljiljana Živanov
Keyword(s):  
Experimental Data ◽  
Low Temperature ◽  
Design Optimization ◽  
Quality Factor ◽  
Performance Improvement ◽  
Air Gap ◽  
Frequency Range ◽  
Operating Frequency Range ◽  
Rf Inductors ◽  
First Time

This paper presents for the first time a parallel comparison of the performance of RF inductors realized on different substrate configurations. Presented inductors are meander type structures fabricated in Low Temperature Co-fired Ceramic (LTCC) technology. Also, chosen material is never before implemented for inductor fabrication. The performance improvement is achieved by design optimization of different substrate configurations that incorporate placement of an air-gap beneath the inductor and/or introduction of an additional shielding layer on the top. Designed structures are characterized on the basis of simulation and experimental data, achieving good correlation between obtained results. Presented results show over 30 % increase in quality factor and widening of the operating frequency range by over 55 %.

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