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Full-Text Articles in Mechanical Engineering

Ultra-Thin-Film Aln Contour-Mode Resonators For Sensing Applications, Matteo Rinaldi, Chiara Zuniga, Gianluca Piazza Sep 2010

Ultra-Thin-Film Aln Contour-Mode Resonators For Sensing Applications, Matteo Rinaldi, Chiara Zuniga, Gianluca Piazza

Matteo Rinaldi

This paper reports on the design and experimental verification of a new class of ultra-thin-film (250 nm) aluminum nitride (AlN) microelectromechanical system (MEMS) contour mode resonators (CMRs) suitable for the fabrication of ultra-sensitive gravimetric sensors. The device thickness was opportunely scaled in order to increase the mass sensitivity, while keeping a constant frequency of operation. In this first demonstration the resonance frequency of the device was set to 178 MHz and a mass sensitivity as high as 38.96 KHz⋅μm2/fg was attained. This device demonstrates the unique capability of the CMR-S technology to decouple resonance frequency from mass sensitivity.


Performance Comparison Of Control Methods For Tankless Water Heaters, David P. Yuill, Andrew H. Coward, Gregor P. Henze Aug 2010

Performance Comparison Of Control Methods For Tankless Water Heaters, David P. Yuill, Andrew H. Coward, Gregor P. Henze

David Yuill

Tankless water heaters (TWH) have several advantages and disadvantages when compared with storage water heaters. One disadvantage is that the outlet temperature of the water is difficult to control. To address this problem, the authors apply seven different control approaches and con- duct experiments to test the effectiveness of each approach. The experiments are carried out on a commercially available electric TWH, using a test method and apparatus developed by the authors. The seven approaches include various configurations of feedback or feed-forward con- trol, or both. One fairly simple approach devised in this project combines feedback and feed-forward control. This …


Hilbert-Huang Transform Transient Analysis Of Composite Panel Undergoing High-Velocity Impact, Seungkyu Lee Aug 2010

Hilbert-Huang Transform Transient Analysis Of Composite Panel Undergoing High-Velocity Impact, Seungkyu Lee

Seungkyu Lee

Fast Fourier transform (FFT) has been widely used to analyze distribution patterns of frequency components in dynamic response signals. Given a stationary dynamic response signal, a fixed frequency distribution pattern can be obtained efficiently using FFT. If the system of concern is not stationary, however, the frequency distribution pattern varies with time, and the variation in that pattern cannot be effectively determined via FFT. To overcome this weakness, time-frequency dual-domain signal analysis methods such as wavelet transform and Hilbert-Huang transform (HHT) have been introduced. HHT has been shown to be particularly effective in analysis of nonstationary signals obtained from non-linear …


Super-High-Frequency Two-Port Aln Contour-Mode Resonators For Rf Applications, Matteo Rinaldi, Chiara Zuniga, Chengjie Zuo, Gianluca Piazza Dec 2009

Super-High-Frequency Two-Port Aln Contour-Mode Resonators For Rf Applications, Matteo Rinaldi, Chiara Zuniga, Chengjie Zuo, Gianluca Piazza

Matteo Rinaldi

This paper reports on the design and experimental verification of a new class of thin-film (250 nm) super-high-frequency laterally-vibrating piezoelectric microelectromechanical (MEMS) resonators suitable for the fabrication of narrow-band MEMS filters operating at frequencies above 3 GHz. The device dimensions have been opportunely scaled both in the lateral and vertical dimensions to excite a contour-extensional mode of vibration in nanofeatures of an ultra-thin (250 nm) AlN film. In this first demonstration, 2-port resonators vibrating up to 4.5 GHz have been fabricated on the same die and attained electromechanical coupling, kt2, in excess of 1.5%. These devices are employed to synthesize …