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101.
102.
T. J. Heindel F. P. Incropera S. Ramadhyani 《International Journal of Heat and Fluid Flow》1995,16(6):511-518
Coupled conduction and natural convection transport within a discretely heated cavity have been investigated numerically. One vertical wall of the cavity is composed of discrete, isoflux heat sources mounted in a substrate of finite thermal conductivity. The opposite vertical wall and the horizontal walls are assumed to be isothermal and adiabatic, respectively. The governing steady-state partial differential equations for the fluid and solid region are solved simultaneously using a control volume formulation, coupled with an additive correction multigrid procedure that increases the convergence rate of the solution. The fluid Prandtl number and heater/fluid thermal conductivity ratio are fixed at 25 and 2350, respectively, corresponding to a dielectric fluid (FC-77) and heaters manufactured from silicon. With increasing modified Rayleigh number (104 < RaLz* < 109), the cavity flow becomes more boundary layer-like along the vertical walls, and multiple fluid cells develop in the central region. Thermal spreading in the substrate increases with decreasing modified Rayleigh number and with increasing values of the substrate/fluid thermal conductivity ratio (10−1 <- Rs ≤ 103). For large Rs, the discrete heat sources lose their thermal identity, and the streamlines and isotherms resemble those associated with a differentially heated cavity. Thermal spreading in the substrate also has a significant effect on circulation in the cavity and on maximum surface temperatures. 相似文献
103.
Electronic-speckle-pattern interferometry and moiré interferometry have been used to calculateK
1 andJ for compact tension specimens. Automated-fringe-pattern analysis enables the full-field of data to be used with the minimum
of operator intervention. Measurements are shown to be accurate to within 10 percent. TheJ-measurement procedure employed could form the basis of an automatic-fault detection system. 相似文献
104.
Dan N. Borza 《Experimental Mechanics》2002,42(4):432-438
Electronic holography is a well-established technique used in real-time, non-contact, whole-field displacement measurements.
When using the real-time, time-averaged method for vibration measurments, the quantitative interpretation of dense fringe
patterns is difficult because of speckle noise. Even when speckle-reducing procedures are used, such as multiple-frame averaging
or rotation of the illumination beam, the remaining speckles and decreasing visibility of higher-order Bessel fringes are
serious limitations. The primary objective of this paper is to present a new realtime, interferometric method for mechanical
vibration measurements and the associated quantitative interpretation. The fringe pattern obtained by this method is quasi-binary
and half as dense as in the time-averaged method. The method greatly improves the overall visibility (contrast, resolution)
of vibration fringe patterns without any sacrifice in the real-time capabilities. Quantitative fringe interpretation is straightforward
and based on binary fringe tracking. It allows quantitative measurements in situations where the time-averaged fringe processing
fails. 相似文献
105.
0Introduction Anelectronicpackageisgenerallyconstructedwithanactivesiliconchip,mountisland,gold wires,leadframesandsoldersasshowninFig.1(a).Toprotectfromtheenvironment,thesilicon chipisusuallyencapsulatedinresin.SincethesematerialshavedifferentCTE(coeffic… 相似文献
106.
随着铜互连以及low-k电介质在超大规模集成电路中地广泛使用,low-k电介质的机械完整性及其对互连可靠性变得更加重要。影响介电膜的机械完整性和互连可靠性的因素包括介电膜的工艺制程,芯片与封装材料的相互影响,以及环境温度和湿度的影响。本文研究集中于了解环境温度和湿度对塑封硅器件中介电薄膜的可靠性影响。采用快速温度和湿度实验条件,对塑封硅器件中介电薄膜受水分和温度损伤的敏感性进行了分析。运用商业有限元(FEA)分析软件,对水分在塑封材料和硅器件中的扩散过程进行了建模及仔细分析。并对硅器件周边密封圈的防水分扩散效力进行了研究。通过这一系列实验与分析,对塑封硅器件中介电薄膜的温湿效应有了完整地了解,并提出和建立了相关的物理模型和经验公式。运用这物理模型和经验公式可对在各种使用环境温度和湿度条件下,塑封硅器件中介电薄膜的可靠性进行评估及分析。 相似文献
107.
In this paper, the out-of-plane deformation of silicon surface of Direct Chip Attachment (DCA) assembly, under thermal loading,
was measured in real-time by Twyman/Green interferometry. The contour maps of the out-of-plane displacement fields of silicon
surface under thermal loading and cycling of various temperature were obtained. Experimental results show that the relation
between the out-of-plane displacement and temperature is nonlinear and varies with temperature cycling, due to nonlinear mechanical
behavior of the materials used in electronic packaging. A comparison of the out-of-plane displacement fields of silicon surface
measured by T/G interferometry in real-time and replicating technique of high temperature specimen grating of moire interferometry
was made. 相似文献
108.
Deformation measurement of conducting polythiophene thin films by an electronic speckle pattern interferometric method 总被引:1,自引:0,他引:1
The deformation measurement of electrosynthesized polythiophene (Pth) thin films is difficult because of the small thickness
and high flexibility of the specimen. An electronic speckle pattern interferometry (ESPI) method is used to measure the deformation
of Pth films of thicknesses in the range of 4–65 μm. Their stres-strain curve are obtained. It is found that the mechanical
properties of Pth films are sensitive to the specimen thickness. The tensile strength increases with decreasing thickness
of thin film from 10 μm. The influence of the electrochemical synthesis conditions on the mechanical properties of Pth films
is also discussed.
Project supported by the Basic-Research Foundation of Tsinghua University (JC2000057), and the Visiting Scholar Foundation
of Solid Mechanical Key Lab in Tongji University of the Ministry of Education of China. Received 10 September 2001; revision
received 9 November 2001. 相似文献
109.
随着材料科学的迅速发展,聚合物材料以不同的形态越来越广泛地应用于食品包装中。但是由于聚合物材料自身的特性及其改性加工,导致了很多低分子量化合物的形成,因而给食品安全性带来很大隐患,也危害着人们的身体健康。为了解决这一问题,在选用材料前,必须分析聚合物材料中低分子化合物的迁移情况,考虑迁移过程对包材使用的影响。实验中选用正庚烷、8%乙醇、50%乙醇和蒸馏水作为食品模拟液,用气相色谱测定聚苯乙烯提取物的迁移量,进而将实验数据分析比较。结果显示,迁移量随着温度的升高和时间的延长而不断增加,溶剂种类的影响为:正庚烷>50%乙醇>8%乙醇>蒸馏水。 相似文献
110.
Water‐soluble porphyrin‐porphyrin and porphyrin‐CdSe nanoparticle monolayer films were self‐assembled on different substrates. The influence of substrates, types of films, and heat treatment temperature on fluorescence of different kinds of porphyrin films was investigated. The SEM images showed the formation of monolayer films on porous alumina foil. The films assembled on porous alumina foil possessed higher fluorescence intensity and thermal stability. The result of conductance measurement indicated that the interaction of trimethylamidophenylporphyrin iodide (TAPPI) molecules with hydroxyl groups on porous alumina foil was weakened after CdSe nanoparticles assembled with TAPPI. 相似文献