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51.
Extreme Two‐Phase Cooling from Laser‐Etched Diamond and Conformal,Template‐Fabricated Microporous Copper 下载免费PDF全文
James W. Palko Hyoungsoon Lee Chi Zhang Tom J. Dusseault Tanmoy Maitra Yoonjin Won Damena D. Agonafer Jess Moss Farzad Houshmand Guoguang Rong Joshua D. Wilbur Derrick Rockosi Ihor Mykyta Dan Resler David Altman Mehdi Asheghi Juan G. Santiago Kenneth E. Goodson 《Advanced functional materials》2017,27(45)
This paper reports the first integration of laser‐etched polycrystalline diamond microchannels with template‐fabricated microporous copper for extreme convective boiling in a composite heat sink for power electronics and energy conversion. Diamond offers the highest thermal conductivity near room temperature, and enables aggressive heat spreading along triangular channel walls with 1:1 aspect ratio. Conformally coated porous copper with thickness 25 µm and 5 µm pore size optimizes fluid and heat transport for convective boiling within the diamond channels. Data reported here include 1280 W cm?2 of heat removal from 0.7 cm2 surface area with temperature rise beyond fluid saturation less than 21 K, corresponding to 6.3 × 105 W m?2 K?1. This heat sink has the potential to dissipate much larger localized heat loads with small temperature nonuniformity (5 kW cm?2 over 200 µm × 200 µm with <3 K temperature difference). A microfluidic manifold assures uniform distribution of liquid over the heat sink surface with negligible pumping power requirements (e.g., <1.4 × 10?4 of the thermal power dissipated). This breakthrough integration of functional materials and the resulting experimental data set a very high bar for microfluidic heat removal. 相似文献
52.
Microsystem Technologies - This article deals with the wave propagation problem of nanosize double-layered plates while subjected to a longitudinal magnetic field. To achieve more reliable answers,... 相似文献
53.
Farzad Aminravan Rehan Sadiq Mina Hoorfar Manuel J. Rodriguez Alex Francisque Homayoun Najjaran 《国际智能系统杂志》2011,26(8):731-758
This work investigates the problem of combining deficient evidence for the purpose of quality assessment. The main focus of the work is modeling vagueness, ambiguity, and local nonspecificity in information within a unified approach. We introduce an extended fuzzy Dempster–Shafer scheme based on the simultaneous use of fuzzy interval‐grade and interval‐valued belief degree (IGIB). The latter facilitates modeling of uncertainties in terms of local ignorance associated with expert knowledge, whereas the former allows for handling the lack of information on belief degree assignments. Also, generalized fuzzy sets can be readily transformed into the proposed fuzzy IGIB structure. The reasoning for quality assessment is performed by solving nonlinear optimization problems on fuzzy Dempster–Shafer paradigm for the fuzzy IGIB structure. The application of the proposed inference method is investigated by designing a reasoning scheme for water quality monitoring and validated through the experimental data available for different sampling points in a water distribution network. © 2011 Wiley Periodicals, Inc. 相似文献
54.
Farzad Nourmohammadzadeh Motlagh 《Applied Artificial Intelligence》2016,30(9):823-843
It seems very realistic to find different aspects in a problem solution like rule hiding. Based on this point of view, Availability, Sensitivity, and Conflict are defined as the novel measurements to detect specific transactions in each transactional database in an effective way. At this point, it will be helpful for decision makers to consider such aspects on their solutions to hide sensitive association rules (ARs). Accordingly, the authors put forward a fitness function of genetic algorithm adjusted to the proposed measurements for hiding sensitive rules of the original database. Experimental study shows that the MOSAR algorithm outperforms traditional approach (Decrease Support of Right Hand Side algorithm) in view of reducing ARs in conflict with sensitive ARs, as a side effect in sensitive rule hiding process. Furthermore, this approach is applicable to do its best in banking systems, where database is to be shared through the networks, to protect strategic information after a serious attack. 相似文献
55.
56.
We propose a multiscale approach to study the influence of carbon nanotubes’ agglomeration on the stability of hybrid nanocomposite plates. The hybrid nanocomposite consists of both macro- and nano-scale reinforcing fibers dispersed in a polymer matrix. The equivalent material properties are calculated by coupling the Eshelby-Mori-Tanaka model with the rule of mixture accounting for effects of CNTs inside the generated clusters. Furthermore, an energy based approach is implemented to obtain the governing equations of the problem utilizing a refined higher-order plate theorem. Subsequently, the derived equations are solved by Galerkin’s analytical method to predict the critical buckling load. The influence of various boundary conditions is studied as well. After validation, a set of numerical examples are presented to explain how each variant can affect the plate’s natural frequency. 相似文献
57.
Investigation of rare earth sealing of porous micro-arc oxidation coating formed on AZ91D magnesium alloy 总被引:1,自引:0,他引:1
Magnesium and its alloys have been used in many industries, but they are reactive and require protection against aggressive envi-ronments. In this study, oxide coatings were applied on AZ91D magnesium alloy using micro-arc oxidation (MAO) process. Then, in order to seal the pores of the MAO coatings, the samples were immersed in cerium bath for different times. The surface morphologies and composi-tions of the coatings were analyzed by scanning electron microscopy (SEM) and X-ray energy dispersive spectroscopy (EDS), respectively. The corrosion behavior of the coatings was investigated with electrochemical impedance spectroscopy (EIS) and potentiodynamic polariza-tion tests in 3.5 wt.% NaCl solution. The amount of the porosity of the coating was measured by electrochemical method. It was found that the sealing treatments by immersion in cerium bath successfully sealed the pores of the MAO coatings. The results of the corrosion tests showed that the MAO coating which was sealed in Ce bath for 10 min enhanced the corrosion resistance of the substrate significantly. Fur-thermore, this coating had the lowest amount of the porosity among the coatings.) 相似文献
58.
Javad Foroughi Bahram KimiaghalamShaban Reza Ghorbani Farzad SafaeiMehran Abolhasan 《Thin solid films》2012,520(24):7049-7053
Experiments were conducted to measure the electrical conductivity in three types of pristine and carbon nanotube-polypyrrole (CNT-PPy) composite yarns and its dependence on over a wide temperature range. The experimental results fit well with the analytical models developed. The effective energy separation between localized states of the pristine CNT yarn is larger than that for both the electrochemically and chemically prepared CNT-PPy yarns. It was found that all samples are in the critical regime in the insulator-metal transition, or close to the metallic regime at low temperature. The electrical conductivity results are in good agreement with a Three Dimensional Variable Range Hopping model at low temperatures, which provides a strong indication that electron hopping is the main means of current transfer in CNT yarns at T < 100 K. We found that the two shell model accurately describes the electronic properties of CNT and CNT-PPy composite yarns in the temperature range of 5-350 K. 相似文献
59.
In this paper a new algorithm for allocating energy and determining the optimum amount of network active power reserve capacity and the share of generating units and demand side contribution in providing reserve capacity requirements for day-ahead market is presented. In the proposed method, the optimum amount of reserve requirement is determined based on network security set by operator. In this regard, Expected Load Not Supplied (ELNS) is used to evaluate system security in each hour. The proposed method has been implemented over the IEEE 24-bus test system and the results are compared with a deterministic security approach, which considers certain and fixed amount of reserve capacity in each hour. This comparison is done from economic and technical points of view. The promising results show the effectiveness of the proposed model which is formulated as mixed integer linear programming (MILP) and solved by GAMS software. 相似文献
60.
Farzad Ebrahimi Mohammad Hassan Naei Abbas Rastgoo 《Journal of Mechanical Science and Technology》2009,23(8):2107-2124
A theoretical model for geometrically nonlinear vibration analysis of piezoelectrically actuated circular plates made of functionally
grade material (FGM) is presented based on Kirchhoff’s-Love hypothesis with von-Karman type geometrical large nonlinear deformations.
To determine the initial stress state and pre-vibration deformations of the smart plate a nonlinear static problem is solved
followed by adding an incremental dynamic state to the pre-vibration state. The derived governing equations of the structure
are solved by exact series expansion method combined with perturbation approach. The material properties of the FGM core plate
are assumed to be graded in the thickness direction according to the power-law distribution in terms of the volume fractions
of the constituents. Control of the FGM plate’s nonlinear deflections and natural frequencies using high control voltages
is studied and their nonlinear effects are evaluated. Numerical results for FG plates with various mixture of ceramic and
metal are presented in dimensionless forms. In a parametric study the emphasis is placed on investigating the effect of varying
the applied actuator voltage as well as gradient index of FGM plate on vibration characteristics of the smart structure.
This paper was recommended for publication in revised form by Associate Editor Eung-Soo Shin
Farzad Ebrahimi received his B.S. and M.S. degree in Mechanical Engineering from University of Tehran, Iran. He is currently working on his
Ph.D. thesis under the title of “Vibration analysis of smart functionally graded plates” at Smart Materials and Structures
Lab in Faculty of Mechanical Engineering of the University of Tehran. His research interests include vibration analysis of
plates and shells, smart materials and structures and functionally graded materials. 相似文献