Presidential Young Investigator Award

理论和实验研究将涉及与(1)接触阻力问题和(2)凝固前沿演化有关的复杂微观界面的传热现象。挑战的原因是在微观层面和平均层面之间没有尺度的分离，以及在存在微妙的微结构的情况下微观测量技术的失败。磁共振成像将用于凝固前沿附近的非侵入性显微、浓度和速度测量，目标是达到1微米的空间分辨率和速度到0.1 mm/S。对于接触电阻问题，将建立基于有限区域接触点随机分布的分析模型。在这个问题中，还将使用磁共振成像来识别界面上的适当几何参数。对于微型微电子元件的开发、航空航天和生物医学工业的先进材料以及对进一步了解二元合金在金属铸造中的凝固过程具有重要意义的传热学问题，都将通过核磁共振技术的独特应用来解决。这项技术将揭示以前在微米水平上无法获得的新信息。

Theoretical and experimental studies of heat transfer phenomena will be performed involving complicated microscopic interfaces related to (1) the contact resistance problem and (2) solidification front evolution. The challenge results from there being no separation of scale between the micro- level and the averaging level, and the failure of microscopic measurement techniques in the presence of delicate microstructures. Magnetic resonance imaging (MRI) will be used for non-invasive microscopy, concentration and velocity measurements close to the solidification front, with a goal of achieving one micrometer spatial resolution and velocities down to 0.1 mm/s. For the contact resistance problem, an analytical model based upon a random distribution of finite area contact spots will be developed. MRI will also be used in this problem to identify the appropriate geometric parameters at the interface. Heat transfer problems of significance to the development of miniaturized microelectronic components, to advanced materials for the aerospace and biomedical industries, and to the further understanding of the solidification of binary alloys in metal casting will all be tackled by a unique application of MRI technology. This technique will reveal new information previously unobtainable at the micrometer level.