A transient thermoreflectance technique, using a 200-fs laser pulse, is demonstrated as a nondestructive method for measuring the thermal boundary resistance between a thin metallic film and dielectric substrate. Experimental results are presented for Au deposited on silicon and silicon dioxide substrates taken at room temperature and compared to a thermal model. The relevant thermal properties...

The accuracy of predictions of phonon thermal boundary conductance using traditional models such as the diffuse mismatch model (DMM) varies depending on the types of material comprising the interface. The DMM assumes that phonons, undergoing diffuse scattering events, are elastically scattered, which drives the energy conductance across the interface. It has been shown that at relatively high t...

Previous work reported from JPL has included characterization of eleetrode kinetics and alkali atom transport from electrodes including MO) W, WRhX, WPtX(Mn), in sodium AMTEC cells and vapor exposure cells; and Mo in potassium vapor exposure cells. [Williams, cl al., 1990a, 1991, 1992] These studies were generally performed in cells with small area electrodes (about 1 to 5 cm2), and device geom...

In this paper we present an algorithm for inverse optimization problems concerning electromagnetic casting of molten metals. We are interested in locating suitable inductors around the molten metal so that the equilibrium shape be as near as possible to a desired target shape. A Simultaneous Analysis and Design (SAND) mathematical programming formulation is stated for the inverse problem. The r...

Dual-energy X-ray computed tomography (DECT) is a powerful tool for non-destructive evaluation for security. In security applications where DECT is used for scanning checked luggage, many different materials may be scanned in various degrees of clutter and metal objects are common. Conventionally, fi ltered back-projection (FBP) is used for image formation and there is no unifi ed treatment of ...

Impurity elements, which have very low bulk concentrations in metals, often segregate to grain boundaries where their concentrations can be greatly enriched. As a results of this segregation, the grain boundaries are often weakened so that they become preferred paths for brittle fracture. This paper presents the results of fully quantum mechanical cluster calculations which have been applied to...

Introduction: Pallasites are stony-iron meteorites that consist of comparable volumes of olivine and Fe-Ni metal. It is widely believed that pallasites were formed at the interface of the metallic core and peridotitic mantle in differentiated asteroid(s) [1,2]. Fe-Ni metal in pallasites exhibits Widmanstätten structure indicative of slow cooling (~10 C/yr) [3,4]. These metallographic cooling ra...

The NASICON-type (Sodium Super Ionic Conductor) Na3Zr2Si2PO12 solid electrolyte is one of the most promising electrolytes for solid-state sodium metal batteries. When preparing ceramic using a traditional high-temperature reaction, high-densification temperature would result in volatilization certain elements and consequent generation impurity phase, worsening functional mechanical performance ...