Effect ofin Situ cooling on superconductivity of artificially layered BSCCO films with 2223 structure

Thin BSCCO films with the 2223 structure were deposited onto MgO substrate kept at 665°C by applying a sequential sputtering method using metallic Bi and Sr-Ca-Cu-O targets. The resultant films were then cooled under various oxygen partial pressures and cooling rates. It was found that the oxygen partial pressure and substrate temperature during cooling affect significantly the development of superconductivity of the as-deposited films. When the films were cooled stepwise under a critical oxygen partial pressure around 0.3 torr, the as-deposited films showed either superconductivity or nonsuperconductivity behavior. HRTEM images of the films showed no essential difference in the modulated structure, suggesting that the excess oxygen in the Bi-O double layers is the same and not the cause of the different superconducting behavior in the as-deposited films.     

ESCA study on the mechanism of adherence of metal to silica glass

Indium oxide films formed on the surface of silica glass samples by selective oxidation have been shown to greatly improve the adherence of gold-indium alloy to the silica glass. In order to clarify the role that the oxide films play in the reaction, thin indium films have been evaporated onto silica glass and heated at temperatures of between 973 and 1473 K, both in air and in hydrogen gas. Electron spectroscopy for chemical analysis (ESCA) measurements have then been made to investigate the chemical environments around oxygen and indium atoms at the reacting interface between the oxide and glass. Measured 01s and In3d _5/2 spectra reveal the formation of non-bridging oxygen atoms at the interface, in addition to the original bridging oxygen atoms in silica glass. Introduction of the non-bridging oxygen atoms and indium ions into the silica glass is concluded to be an essential factor in promoting good adherence between the gold alloy and silica glass.     

Proposal of Asynchronous Time Division Multiple Access Radio Highway Using Chirp Multiplexing Transform

Asynchronous TDMA bus-link systems using chirp multiplexing transform(CMT) are proposed for radio highway networks to provide the flexibleconstruction of fiber-optic radio access networks and thepossibility of the universal use of these networks among future diverseradio services. The CMT equipped at the radio base station performs twofunctions. One is the conversion of FDM multiple radio services intosignals with a TDMA format and the other is the time compression ofthe generated signal in order to allow asynchronous access. As aresult, the proposed systems can realize the unified transmission ofmultiple radio services and the switching of them in the optical stage(photonic routing) in the networks according to the type of radioservice. The realization of such photonic routing of the radio servicewould greatly benefit the goal of a seamless and universalnetwork available to different types of radio service. Therelationship between the pulse-loss probability performance and thecall-blocking probability performance is theoretically analyzed. Theeffect on the performance of traffic partiality in the coveredarea and the way the performance can be improved are theoreticallyinvestigated. Finally, one of the ways to determine the network sizecovered by a bus link and the number of connected radio base stationsis introduced.     

Microstructural changes of Al/amorphous SiC layered films subjected to heating

Layered specimens composed of aluminium and a-SiC films were prepared at room temperature by r.f. magnetron sputtering. a-SiC/Al/a-SiC triple-layered films were heated in the trans mission electron microscope (TEM), and thein-situ microstructural changes were observed continuously. In order to estimate the interfacial reaction process kinematically, electrical resistance measurements were conducted on Al/a-SiC double-layered films heated isothermally at 573, 598 and 623 K. Thein-situ TEM observations showed that no pronounced interfacial reactions occurred up to about 600 K, that silicon precipitates were formed and grew around 673 K, and that Al₄C₃ compounds were produced during heating at temperatures above about 753 K. The electrical resistance of Al/a-SiC double-layered film heated isothermally increased gradually with heating time, and this increase was closely related to the volume fraction of silicon precipitates in the aluminium film. From the kinematical analyses of the results of electrical resistance measurements, an activation energy of the interfacial reaction process of aluminium with a-SiC films in the temperature range 573 to 623 K was found to be about 2.6 eV, being close to the bond energy of Si-C.     

Marangoni convection driven by thermocapillary and solutocapillary forces in the Fe-O alloy pool during the solidification or remelting process

Marangoni convection during the solidification or remelting process was investigated in a small pool of a liquid Fe-O alloy, by experiments and numerical simulations. Most of the studies of such a system, with a low Prandtl number but a high Schmidt number, have taken into account thermocapillary convection but have left the solutocapillary effect out of consideration. However, our experimental and numerical approaches revealed that solutocapillary convection also plays an important role in the generation of peculiar flow patterns with a single roll cell or two roll cells. The Marangoni convection observed was classified into at least four categories based on the thermocapillary and solutocapillary forces.     

Direct Patterning of Silver Circuit Using Surface- modification and UV Irradiation on Polyimide Resin

A simplified method is proposed for the formation of a silver circuit pattern on a polyimide resin substrate through modification of the resin surface followed by adsorption of silver(l) ion and UV photoreduction to form patterns. The amide bond and carboxyl group, as a cation exchange group, were formed on the polyimide resin surface by a potassium hydroxide treatment. UV irradiation of the adsorbed silver(I) ion results in the formation of a silver thin film. Silver circuit patterns are easily formed on the modified polyimide resin substrates without using a plating resist by use of a metal-on-quart: mask     

Toward integrated product and process life cycle planning—An environmental perspective

Life cycle engineering (LCE) is a key concept for promoting environmentally sustainable practices among manufacturing firms. A major hurdle in the implementation of LCE is the lack of a systematic and strategic method to design or plan an entire product life cycle. To address this issue, this keynote provides a framework for life cycle development and proposes the concept of life cycle planning. This paper aims to provide explicit and systematic methodologies for life cycle planning by reviewing this research area. Practical cases that employ life cycle planning are also illustrated. Finally, some research directions are suggested.