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307 results on '"Ohadi, Michael"'

51. The ICECool Fundamentals Effort on Evaporative Cooling of Microelectronics

Author

Bar-Cohen, Avram, primary, Asheghi, Mehdi, additional, Chainer, Timothy J., additional, Garimella, Suresh V., additional, Goodson, Kenneth, additional, Gorle, Catherine, additional, Mandel, Raphael, additional, Maurer, Joseph J., additional, Ohadi, Michael, additional, Palko, James W., additional, Parida, Pritish R., additional, Peles, Yoav, additional, Plawsky, Joel L., additional, Schultz, Mark D., additional, Weibel, Justin A., additional, and Joshi, Yogendra, additional

Published
2021
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60. Emerging Trends

Author

Dai, Jun, primary, Ohadi, Michael M., additional, Das, Diganta, additional, and Pecht, Michael G., additional

Published
2013
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69. In Memoriam: Professor Avram Bar-Cohen (1946–2020)

Author

Hodes, Marc, primary, Mahajan, Ravi, additional, Ruder, Zvi, additional, Simon, Terry, additional, Geisler, Karl, additional, Ohadi, Michael, additional, Maurer, Joseph, additional, Altman, David, additional, Wilson, Jim, additional, Ziskind, Gennady, additional, Spector, Mark, additional, Catton, Ivan, additional, Dhir, Vijay, additional, Fisher, Timothy, additional, Ayyaswamy, Portonovo, additional, and Mikic, Boravoje, additional

Published
2021
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70. Effect of electrode geometry on performance of an EHD thin-film evaporator

Author

Moghaddam, Saeed and Ohadi, Michael M.

Subjects
Electrodes -- Research, Microelectromechanical systems -- Research, Dielectric films -- Research, Thin films -- Research, Engineering and manufacturing industries, Science and technology
Abstract

This paper presents details of an optimization process of electrode geometry for an electrohydrodynamically (EHD) driven thin-film evaporator. The operation principle of the device is based on the action of the EHD force on the molecules of a dielectric liquid in a highly convergent electric field. The force starts at the end of a pair of electrodes, where the electric field changes from zero far from the electrodes to a finite value in between the electrodes. This force drives the liquid up into the spacing between the electrodes. The electrodes in this study were deposited thinly on a Si[O.sub.2]/Si wafer, so the liquid could be held within micrometers of thickness over the surface. Since the performance of the device in removing heat from the surface is a function of its pumping head and consequently its electrode geometry, the performances of different electrodes were evaluated by testing twelve sets of electrode pairs with different geometries. Then the optimum electrode design was incorporated into the design of a large size (32 x 32 [mm.sub.2]) EHD thin-film evaporator. The device was fabricated, and its pumping and heat transfer performances were tested. A pumping head equal to the full height of the electrodes and a heat transfer coefficient of 1.9 W/[cm.sup.2]*[degrees]C was achieved using HFE-7100 liquid. [1215] Index Terms--Electrohydrodynamic (EHD), electronic cooling, microfluidic MEMS, polarization, thin-film evaporator.

Published
2005

74. Design, fabrication, and testing of an electrohydrodynamic ion-drag micropump

Author

Darabi, Jeff, Rada, Mihai, Ohadi, Michael, and Lawler, John

Subjects
Ion pumps -- Design and construction, Electrodes -- Usage, Engineering and manufacturing industries, Science and technology
Abstract

This paper presents the design, fabrication, and testing of a novel electrohydrodynamic (EHD) ion-drag micropump. In order to maximize the electrical field gradients that are responsible for EHD pumping, we incorporated three-dimensional (3-D) triangular bumps of solder as part of the EHD electrodes. To form these bumps, Niobium was sputter-deposited onto a ceramic substrate, coated with photoresist, optically exposed and etched using a reactive ion etcher to define the electrode pattern. The substrate was then 'dipped' into a molten solder pool. Since the solder adheres only to the metallic film, bumps of solder form on the electrodes, giving the electrodes a significant 3-D character. The overall dimensions of the micropump are 19 mm x 32 mm x 1.05 mm. Four different designs were fabricated and tested. Static pressure tests were performed with a 3M Thermal Fluid (HFE-7100) as the working fluid and the optimum design was identified. The results with the thermal fluid were highly promising and indicated a pumping head of up to 700 Pa at an applied voltage of 300 V. The experimental results for the four different designs show that the presence of the 3-D bump structures significantly improves the pumping performance. Also, a much better pumping performance was obtained with the micropump in which the emitter had a saw-tooth shape. [816] Index Terms--Electrohydrodynamics (EHDs), ion-drag, micropump, three-dimensional (3-D) electrode.

Published
2002

84. Thermal Management of High-Power Density Electric Motors for Electrification of Aviation and Beyond

Author

Deisenroth, David C., Deisenroth, David C., Ohadi, Michael, Deisenroth, David C., Deisenroth, David C., and Ohadi, Michael

Abstract

Enhanced cooling, coupled with novel designs and packaging of semiconductors, has revolutionized communications, computing, lighting, and electric power conversion. It is time for a similar revolution that will unleash the potential of electrified propulsion technologies to drive improvements in fuel-to-propulsion efficiency, emission reduction, and increased power and torque densities for aviation and beyond. High efficiency and high specific power (kW/kg) electric motors are a key enabler for future electrification of aviation. To improve cooling of emerging synchronous machines, and to realize performance and cost metrics of next-generation electric motors, electromagnetic and thermomechanical co-design can be enabled by innovative design topologies, materials, and manufacturing techniques. This paper focuses on the most recent progress in thermal management of electric motors with particular focus on electric motors of significance to aviation propulsion.

Published
2019

93. RECENT DEVELOPMENTS IN HIGH TEMPERATURE HEAT EXCHANGERS: A REVIEW

Author

Zhang, Xiang, Zhang, Xiang, Keramati, Hadi, Arie, Martinus, Singer, Farah, Tiwari, Ratnesh, Shooshtari, Amir, Ohadi, Michael, Zhang, Xiang, Zhang, Xiang, Keramati, Hadi, Arie, Martinus, Singer, Farah, Tiwari, Ratnesh, Shooshtari, Amir, and Ohadi, Michael

Abstract

Heat exchangers are key components of most power conversion systems, a few industrial sectors can particularly benefit from high temperature heat exchangers. Examples include conventional aerospace applications, advanced nuclear power generation systems, and high efficiency stationary and mobile modular fossil fuel to shaft power/electricity conversion systems. This paper provides a review of high temperature heat exchangers in terms of build materials, general design, manufacturing techniques, and operating parameters for the selected applications. Challenges associated with conventional and advanced fabrication technologies of high temperature heat exchangers are discussed. Finally, the paper outlines future research needs of high temperature heat exchangers.

Published
2018

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