Investigation of Thermoelastic Loss Mechanism in Shell Resonators

2014 ◽  
Author(s):  
Ali Darvishian ◽  
Behrouz Shiari ◽  
Jae Yoong Cho ◽  
Tal Nagourney ◽  
Khalil Najafi
Keyword(s):  
Fused Silica ◽  
Squeeze Film ◽  
Q Factor ◽  
Loss Mechanism ◽  
Conductive Coatings ◽  
Remarkable Effect ◽  
Resonator Design ◽  
Wide Range ◽  
Improved Performance ◽  
Q Factors

Maximizing quality (Q) factor is key to enhancing the performance of micro mechanical resonators, which are used in a wide range of applications such as gyroscopes, filters, and clocks. There are several energy loss mechanisms commonly associated with micro resonators including anchor loss through the substrate, squeeze film damping, thermoelastic dissipation (TED), and surface loss. This work focuses on the thermoelastic loss as one of the major energy dissipation mechanisms of micro shell resonators. In this article, the effects of material properties, thickness, conductive coating and operating temperature on the Q-factor of micro shell resonators are investigated. Numerical simulation shows shell resonators have higher Q-factors when they are operating at lower temperatures. Although, the magnitude of the simulated Q-factors of an uncoated bare resonator made from fused silica is more than 70 million and so it is too high to have a remarkable effect on the total Q-factor, our study shows that even a thin layer of some conductive coatings like gold on the surface of a bare shell reduces Q-factor significantly. The sensitivity of the coated shell resonator design to the TED phenomenon provides useful information for the development of new micro shell resonators with improved performance and Q-factors.

scholarly journals INVESTIGATION OF COUPLED EFFECTS OF TEMPERATURE AND RELATIVE HUMIDITY ON DYNAMIC PERFORMANCE OF MEMS CANTILEVER RESONATORS IN GAS RAREFACTION

2019 ◽  
Vol 57 (3) ◽  
pp. 366
Author(s):  
Nguyen Chi Cuong ◽  
Trinh Xuan Thang ◽  
Truong Van Phat ◽  
Vu Manh Giap ◽  
Ngo Vo Ke Thanh
Keyword(s):  
Relative Humidity ◽  
Dynamic Performance ◽  
Resonant Mode ◽  
Squeeze Film ◽  
Moist Air ◽  
Squeeze Film Damping ◽  
Wide Range ◽  
Accommodation Coefficients ◽  
Effects Of Temperature ◽  
Q Factors

The modified molecular gas lubrication (MMGL) equation with the effective viscosity of moist air is utilized to solve for the squeeze film damping (SFD) problem on the dynamic performance of MEMS cantilever resonators. Thus, the coupled effects of temperature and relative humidity are discussed on the Q-factors of MEMS cantilever resonators in a wide range of gas rarefaction (pressure, p and accommodation coefficients, ACs) and resonant mode of vibration. The results showed that the Q-factor of moist air decreases more significantly as temperature and relative humidity increase at higher gas rarefaction (lower p, and ACs) conditions.  

scholarly journals Experimental Study on Variation of Surface Roughness and Q Factors of Fused Silica Cylindrical Resonators with Different Grinding Speeds

Micromachines ◽  
2021 ◽  
Vol 12 (9) ◽  
pp. 1052
Author(s):  
Libin Zeng ◽  
Yunfeng Tao ◽  
Yao Pan ◽  
Jianping Liu ◽  
Kaiyong Yang ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Low Cost ◽  
Fused Silica ◽  
Q Factor ◽  
Cylindrical Resonator ◽  
Axisymmetric Shell ◽  
Measurement Results ◽  
Q Factors ◽  
Cylindrical Resonators ◽  
Quality Factor Q

For the axisymmetric shell resonator gyroscopes, the quality factor (Q factor) of the resonator is one of the core parameters limiting their performances. Surface loss is one of the dominating losses, which is related to the subsurface damage (SSD) that is influenced by the grinding parameters. This paper experimentally studies the surface roughness and Q factor variation of six resonators ground by three different grinding speeds. The results suggest that the removal of the SSD cannot improve the Q factor continuously, and the variation of surface roughness is not the dominant reason to affect the Q factor. The measurement results indicate that an appropriate increase in the grinding speed can significantly improve the surface quality and Q factor. This study also demonstrates that a 20 million Q factor for fused silica cylindrical resonators is achievable using appropriate manufacturing processes combined with post-processing etching, which offers possibilities for developing high-precision and low-cost cylindrical resonator gyroscopes.

WAVEGUIDE-COAXIAL RESONATOR WITH WIDE-RANGE FREQUENCY TUNING AND INCREASED Q-FACTOR

2016 ◽  
Vol 75 (10) ◽  
pp. 887-894 ◽  
Author(s):  
R. I. Bilous ◽  
A. P. Motornenko ◽  
I. G. Skuratovskiy ◽  
O. I. Khazov
Keyword(s):  
Frequency Tuning ◽  
Q Factor ◽  
Coaxial Resonator ◽  
Wide Range

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.

scholarly journals Carbon Nanotube Films for Energy Applications

Energies ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1890
Author(s):  
Monika Rdest ◽  
Dawid Janas
Keyword(s):  
Carbon Nanotube ◽  
Mechanical Energy ◽  
Research Community ◽  
Thermal Interface Materials ◽  
Thermal Interface ◽  
Conductive Coatings ◽  
Storage Devices ◽  
Energy Applications ◽  
Wide Range ◽  
Interface Materials

This perspective article describes the application opportunities of carbon nanotube (CNT) films for the energy sector. Up to date progress in this regard is illustrated with representative examples of a wide range of energy management and transformation studies employing CNT ensembles. Firstly, this paper features an overview of how such macroscopic networks from nanocarbon can be produced. Then, the capabilities for their application in specific energy-related scenarios are described. Among the highlighted cases are conductive coatings, charge storage devices, thermal interface materials, and actuators. The selected examples demonstrate how electrical, thermal, radiant, and mechanical energy can be converted from one form to another using such formulations based on CNTs. The article is concluded with a future outlook, which anticipates the next steps which the research community will take to bring these concepts closer to implementation.

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 Efficient and Innovative Polishing Processes for Smoothing Complex Surface Geometries and Internal Contours on Brittle-Hard Components

2020 ◽  
Vol 238 ◽  
pp. 03010
Author(s):  
Marcel Binder ◽  
Sebastian Henkel ◽  
Anne-Marie Schwager ◽  
Christoph Letsch ◽  
Jens Bliedtner ◽  
...  
Keyword(s):  
Current Trend ◽  
Glass Ceramics ◽  
Complex Surface ◽  
Fused Silica ◽  
Free Form ◽  
Resource Saving ◽  
Processing Technologies ◽  
Wide Range ◽  
Monolithic Components ◽  
Free Form Surfaces

The material fused silica, as well as other brittle-hard materials such as glass ceramics, have great potential for use in a wide range of applications due to their special material properties. The technical advantages of these materials require sophisticated processing technologies, including polishing steps, in order to be able to use these interesting materials advantageously. In addition, a current trend in modern optical manufacturing is the use of free-form surfaces and monolithic components that combine several optical and mechanical functions in one part. Novel or improved processes are needed in order to meet future requirements for resource-saving and effective production methods at the same time.

Viscous Oil-Water Flow in a Microchannel: Flow Patterns and Flow Development

2010 ◽  
Author(s):  
Hooman Foroughi ◽  
Masahiro Kawaji
Keyword(s):  
Water Flow ◽  
Silicone Oil ◽  
Flow Characteristics ◽  
Flow Patterns ◽  
Fused Silica ◽  
Water Mixture ◽  
Injection Point ◽  
Viscous Oil ◽  
Wide Range ◽  
Oil Water

The flow characteristics of a highly viscous oil and water mixture in a circular microchannel have been investigated. Water and silicone oil with a viscosity of 863 mPa.s were injected into a fused silica microchannel with a diameter of 250 μm. Before each experiment, the microchannel was initially saturated with either oil or water. In the initially oil-saturated case, different liquid-liquid flow patterns were observed and classified over a wide range of oil and water flow rates. As a special case, the flow of water at zero oil flow rate in a microchannel initially filled with silicone oil was also studied. When the microchannel was initially saturated with water, the oil formed a jet in water at the injection point but developed an instability at the oil-water interface downstream and eventually broke up into droplets.

Ultrafast Pulsed Laser Deposition of Chalcogenide Glass Films for Low-loss Optical Waveguides

2003 ◽  
Vol 780 ◽  
Author(s):  
B. Luther-Davies ◽  
V. Z. Kolev ◽  
M. J. Lederer ◽  
R. Yinlan ◽  
M. Samoc ◽  
...  
Keyword(s):  
Pulsed Laser Deposition ◽  
Repetition Rate ◽  
Pulsed Laser ◽  
Fused Silica ◽  
Laser Deposition ◽  
Process Conditions ◽  
High Optical Quality ◽  
Optical Films ◽  
Wide Range ◽  
Deposited Films

AbstractUltra-fast pulsed laser deposition using high-repetition-rate short-pulse lasers has been shown to provide high optical quality, super smooth thin films free of scattering centres. The optimized process conditions require short ps or sub-ps pulses with repetition rate in the range 1-100 MHz, depending on the target material. Ultra-fast pulsed laser deposition was used to successfully deposit atomically-smooth, 5micron thick As2S3 films. The as-deposited films were photosensitive at wavelengths close to the band edge (≈520 nm) and waveguides could be directly patterned into them by photo-darkening using an Argon ion or frequency doubled Nd:YAG laser. The linear and nonlinear optical properties of the films were measured as well as the photosensitivity of the material. The optical losses in photo-darkened waveguides were <0.2 dB/cm at wavelengths beyond 1200nm and <0.1 dB/cm in as-deposited films. The third order nonlinearity, n2,As2S3, was measured using both four-wave mixing and the z-scan technique and varied with wavelength from 100 to 200 times fused silica (n2,Silica ≈3×10-16 cm2/W) between 1500nm and 1100nm with low nonlinear absorption.Encouraged by the Ultrafast laser deposition results, we have built a new specialized modelocked picosecond laser system for deposition of optical films and for laser formation of nanoclusters. The newly developed “state of the art” powerful Nd:YVO laser can operate over a wide range of wavelengths, intensities, and repetition rates in MHz range. A brief description of the 50W laser installation is presented.

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