Engineering

Publication Search Results

Now showing 1 - 7 of 7
  • (1998) Bradley, Peter; Rozenfeld, Anatoly; Lee, Kevin; Jamieson, Dana; Heiser, Gernot; Satoh, S
    Journal Article
    The first results obtained using a SOI device for microdosimetry applications are presented. Microbeam and broadbeam spectroscopy methods are used for determining minority carrier lifetime and radiation damage constants. A spectroscopy model is presented which includes the majority of effects that impact spectral resolution. Charge collection statistics were found to substantially affect spectral resolution. Lateral diffusion effects significantly complicate charge collection

  • (1998) Heiser, Gernot; Elphinstone, Kevin; Vochteloo, J; Russell, Stephen; Liedtke, Jochen
    Journal Article
    Single-address-space operating systems (SASOS) are an attractive model for making the best use of the wide address space provided by the latest generations of microprocessors. SASOS remove the address space boundaries which make data sharing between processes difficult and expensive in traditional operating systems. They offer the potential of significant performance advantages for applications where sharing is important, such as object-oriented databases or persistent programming systems. We have built the Mungi system to demonstrate that a SASOS can offer these performance advantages without resorting to special hardware. Mungi is a very `pure` SASOS, featuring an unintrusive protection model based on sparse capabilities, a fast protected procedure call mechanism, and uses shared memory as the exclusive inter-process communication mechanism, as well as for I/O. The simplicity of our model makes it easy to implement it efficiently on conventional architectures. Our implementation of Mungi for the MIPS R4600 64-bit microprocessor is presented, which is based on our port of the L4 microkernel. Mungi is shown to outperform, in some instances by more than an order of magnitude, two UNIX operating systems, Irix and Linux, in several important operations, such as task creation and inter-process communications, and on the OO1 object-oriented database benchmark. As well, we describe how our approach to key issues in SASOS design provides better performance than other systems, such as Opal. Our experience shows that the SASOS concept is viable, and that a well-designed microkernel is an excellent base on which to build high-performance operating systems.

  • (1998) Gu, Genda; Han, Shaowei; Lin, Zheng; Zhao, Yong; Russell, Graeme
    Journal Article

  • (1998) Choi, C; Kim, Hann; Standard, Owen; Kim, Min; Zhao, Yong; Sorrell, Charles
    Journal Article
    YBa2Cu3O7-y with high grain alignment has been successfully fabricated by a modified powder melting process at a temperature of ~930oC which is near the eutectic point of the starting materials Y2BaCuO5, BaCuO2, and CuO. In terms of the levitation force and YBa2Cu3O7-y grain alignment, the best result was shown in a sample having a Y2BaCuO5:BaCuO2:CuO molecular ratio of 1:3:5. In the present work, the Cu-surplus eutectic liquid was completely absorbed by use of a Y2BaCuO5 substrate, by which the final composition was driven to stoichiometric YBa2Cu3O7-y. The results were comparable to those obtained by the conventional melt-texture-growth process. A new invariant point apparently occurred at ~930-940oC owing to an interfacial reaction between YBa2Cu3O7-y matrix and Y2BaCuO5 substrate.

  • (1998) Ramadan, Ziad; Mulholland, Mary; Hibbert, D. Brynn; Preston, P; Compton, Paul; Haddad, Paul
    Journal Article

  • (1998) Haralambous, Y; Plaice, John
    Journal Article

  • (1998) Ankiewicz, A; Wang, Zheng; Peng, Gang-Ding
    Journal Article
    In this analysis, we show that, using a Bragg grating in transmission mode, an optical filter based on an asymmetric twin-core fibre can operate with excellent narrow bandpass characteristics (e.g., pass bandwidths less than 1 nm) for optical wavelength division multiplexing systems. The grating in this scheme operates outside the band-gap. This ensures that the grating functions are in ‘transmission mode', i.e., that most of the light is transmitted through the device. More importantly, the grating introduces a periodic modulation in propagation constant which produces resonantly enhanced dispersion in coupling, and this leads to a significant reduction in pass bandwidth.