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Selected Works

2010

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Articles 121 - 127 of 127

Full-Text Articles in Mechanical Engineering

Dynamic Reversibility Of Hydrodynamic Focusing For Recycling Sheath Fluid, Nicole N. Hashemi, Peter B. Howell Jr., Jeffrey S. Erickson, Joel P. Golden, Francis S. Ligler Jan 2010

Dynamic Reversibility Of Hydrodynamic Focusing For Recycling Sheath Fluid, Nicole N. Hashemi, Peter B. Howell Jr., Jeffrey S. Erickson, Joel P. Golden, Francis S. Ligler

Nastaran Hashemi

The phenomenon of "unmixing" has been demonstrated in microfluidic mixers, but here we manipulate laminar flow streams back to their original positions in order to extend the operational utility of an analytical device where no mixing is desired. Using grooves in the channel wall, we passively focus a sample stream with two sheath streams to center it in a microchannel for optical analysis. Even though the sample stream is completely surrounded by sheath fluid, reversing the orientation of the grooves in the channel walls returns the sample stream to its original position with respect to the sheath streams. We demonstrate …

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Oscillatory And Monotonic Modes Of Long-Wave Marangoni Convection In A Thin Film, Sergey Shklyaev, Mikhail Khenner, Alexei Alabuzhev Jan 2010

Oscillatory And Monotonic Modes Of Long-Wave Marangoni Convection In A Thin Film, Sergey Shklyaev, Mikhail Khenner, Alexei Alabuzhev

Mikhail Khenner

We study long-wave Marangoni convection in a layer heated from below. Using the scaling k=OBi, where k is the wave number and Bi is the Biot number, we derive a set of amplitude equations. Analysis of this set shows presence of monotonic and oscillatory modes of instability. Oscillatory mode has not been previously found for such direction of heating. Studies of weakly nonlinear dynamics demonstrate that stable steady and oscillatory patterns can be found near the stability threshold.

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100nm Thick Aluminum Nitride Based Piezoelectric Nano Switches Exhibiting 1mv Threshold Voltage Via Body-Biasing, Nipun Sinha, Zhijun Guo, Valeriy Felmetsger, Gianluca Piazza Dec 2009

100nm Thick Aluminum Nitride Based Piezoelectric Nano Switches Exhibiting 1mv Threshold Voltage Via Body-Biasing, Nipun Sinha, Zhijun Guo, Valeriy Felmetsger, Gianluca Piazza

Nipun Sinha

This paper reports on the first demonstration of aluminum nitride (AlN) piezoelectric logic switches that were fabricated with ultra-thin (100nm) AlN films and exhibit a 1 mV threshold voltage via the body-biasing scheme. The application of a relatively low (< 6 V) fixed potential to the body terminal of a 4-terminal switch has resulted in a repeatable threshold voltage of 1 mV. The nano-switch has been cycled to > 109 cycles and, although the contact resistance was found to be high (~ 1 MΩ), the nano-films have functioned throughout to show high piezoelectric nano-film reliability.

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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 …

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Demonstration Of Low Voltage And Functionally Complete Logic Operations Using Body-Biased Complementary And Ultra-Thin Aln Piezoelectric Mechanical Switches, Nipun Sinha, Timothy S. Jones, Zhijun Guo, Gianluca Piazza Dec 2009

Demonstration Of Low Voltage And Functionally Complete Logic Operations Using Body-Biased Complementary And Ultra-Thin Aln Piezoelectric Mechanical Switches, Nipun Sinha, Timothy S. Jones, Zhijun Guo, Gianluca Piazza

Nipun Sinha

This paper reports, for the first time, on the demonstration of low voltage and functionally complete logic elements (NAND and NOR) implemented by using body-biased complementary and ultra-thin (250 nm thick) Aluminum Nitride (AlN) based piezoelectric mechanical switches. This work presents, firstly, the importance of scaling AlN films for the demonstration of ultra-thin AlN switches and, secondly, the implementation of a new actuation scheme based on body biasing to lower the switch threshold voltage. Four of these ultra-thin switches were connected together to synthesize functionally complete MEMS logic gates (NAND and NOR) with a ± 2V swing and a body-bias …

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Pricing Residential Water To Account For Scarcity In Cyprus, Theodoros Zachariadis Dec 2009

Pricing Residential Water To Account For Scarcity In Cyprus, Theodoros Zachariadis

Theodoros Zachariadis

No abstract provided.

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Preliminary Numerical Analysis Of Valve Fatigue In A Checkball Pump For Driveline Applicatio, Yang Yang Dec 2009

Preliminary Numerical Analysis Of Valve Fatigue In A Checkball Pump For Driveline Applicatio, Yang Yang

Yang Yang

Recent studies have shown that hydraulic hybrid drivelines can significantly improve fuel savings for medium weight vehicles on stop-start drivecycles. In a series hydraulic hybrid (SHH) architecture, the conventional mechanical driveline is replaced with a hydraulic driveline that decouples vehicle speed from engine speed. In an effort to increase the design space, this paper explores the use of a fixed displacement check-ball piston pump in an SHH driveline. This paper identifies the potential life-limiting components of a fixed-displacement checkball piston pump and examines the likelihood of surface fatigue in the check valves themselves. Numerical analysis in ABAQUS software suggests that …

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