1,950 research outputs found

    Steel Bridge Fabrication Errors Indexed Examples and Solutions: Combining Rules and Cases

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    This research focuses on the development of a knowledge-based system in the domain of steel bridge fabrication errors using both rule-based reasoning (RBR) and case-based reasoning (CBR). Fabrication error Indexed and Solutions (FIXS) was developed to combine the benefits of two previous research projects: 1) the rule-based Bridge Fabrication error solution eXpert system (BFX), and 2) its case-based counterpart (CB-BFX). Errors that occur during the fabrication of steel bridg~ members can have a costly effect on the performance of a bridge if not repaired properly. FIXS is an effort to provide guidance to the bridge engineer responsible for cost effective solutions in a time sensitive manner. FIXS is implemented in the programming language PROLOG and runs in the Windows environment as a stand-alone application. RBR facilities are provided by the expert system shell MESS (Modest Expert System Shell). Similarly, CBR functions are provided by the simple case-based reasoner shell SCBR (Simple Case Based Reasoning). The application has been designed for addition of new domain knowledge. The addition of new and updated knowledge allows the application to keep pace with changes in the steel bridge design industry and the methods of repairing errors

    Wafer-scale magnesium diboride thin films and devices with tunable high kinetic inductance

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    Progress in superconducting device and detector technologies over the past decade have realized practical applications in quantum computers, detectors for far-IR telescopes, and optical communications. Superconducting thin film materials, however, have remained largely unchanged, with aluminum still being the material of choice for superconducting qubits, and Nb compounds for higher frequency devices. MgB2\mathrm{MgB}_2, known for its highest Tc\mathrm{T}_c (39 K) among metallic superconductors, is a viable material for higher frequency superconducting devices moving towards THz frequencies. However, difficulty in synthesizing thin films have prevented implementation of MgB2\mathrm{MgB}_2 devices into the application base of superconducting electronics, despite promising preliminary results for a number of applications. We have developed smooth and uniform MgB2\mathrm{MgB}_2 films on 4-inch Si wafers by depositing uniform Mg-B co-sputtered film, capping the film in situ to create a closed environment, followed by an optimized post-annealing step. We further report mature device fabrication processes and demonstrate test structures to measure properties of the films. This includes resonators with internal Q factor over 104\mathrm{10}^4 at 4.5 K and tunable high kinetic inductance (5-50 pH/\square readily achieved in a 40 nm film), opening up the path for development of high frequency and high temperature MgB2\mathrm{MgB}_2 microdevices

    The enrichment of an alkaliphilic biofilm consortia capable of the anaerobic degradation of isosaccharinic acid from cellulosic materials incubated within an anthropogenic, hyperalkaline environment.

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    Anthropogenic hyper-alkaline sites provide an environment that is analogous to proposed cementitious geological disposal facilities (GDF) for radioactive waste. Under anoxic, alkaline conditions cellulosic wastes will hydrolyse to a range of cellulose degradation products (CDP) dominated by isosaccharinic acids (ISA). In order to investigate the potential for microbial activity in a cementitious GDF, cellulose samples were incubated in the alkaline (∼pH 12), anaerobic zone of a lime kiln waste site. Following retrieval, these samples had undergone partial alkaline hydrolysis and were colonised by a Clostridia dominated biofilm community, where hydrogenotrophic, alkaliphilic methanogens were also present. When these samples were used to establish an alkaline CDP fed microcosm, the community shifted away from Clostridia, methanogens became undetectable and a flocculate community dominated by Alishewanella sp. established. These flocs were composed of bacteria embedded in polysaccharides and protein stabilised by extracellular DNA. This community was able to degrade all forms of ISA with >60% of the carbon flow being channelled into extracellular polymeric substance (EPS) production. This study demonstrated that alkaliphilic microbial communities can degrade the CDP associated with some radioactive waste disposal concepts at pH 11. These communities divert significant amounts of degradable carbon to EPS formation, suggesting that EPS has a central role in the protection of these communities from hyper-alkaline conditions

    Secondary B-mode polarization from Faraday rotation in clusters and galaxies

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    We revisit the polarisation induced by Faraday rotation when Cosmic Microwave Background photons traverse magnetised plasma. We compute the secondary B-mode angular power spectrum from Faraday rotation due to magnetic fields in galaxies and galaxy clusters with masses ranging from 101110^{11} to 1016.5M10^{16.5} M_\odot. We investigate its dependence on the electron and the magnetic field profiles. Namely, we consider both the beta-profile of electron density as well as an electron density distribution based on the Navarro-Frenk-White dark matter profile. We model the magnetic field structure in galaxies and clusters motivated by recent observations. We further account for its redshift evolution and we examine the importance of its coherence length. We find that the B-mode polarisation from Faraday rotation depends on the normalisation parameter Clσ856C_l\propto \sigma_8^{5-6}. At 30 GHz for σ8=0.8\sigma_8=0.8, the B-modes from Faraday rotation range between 0.01μK20.01 {\mu \rm K}^2 and 4×103μK24 \times 10^{-3} {\mu \rm K}^2 at l=104l=10^4 in the case of a maximally coherent fields. For smaller coherence lengths, those amplitudes are smaller and they peak at higher multipoles.Comment: Accepted for publication in MNRA

    Molecularly Engineered Self-Assembling Membranes for Cell-Mediated Degradation

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    The use of peptide engineering to develop self-assembling membranes that are responsive to cellular enzyme activities is reported. The membranes are obtained by combining hyaluronan (HA) and a rationally designed peptide amphiphile (PA) containing a proteolytic domain (GPQGIWGQ octapeptide) sensitive to matrix metalloproteinase-1 (MMP-1). Insertion of an octapeptide in a typical PA structure does not disturb its self-assembly into fibrillar nanostructures neither the ability to form membranes with HA. In vitro enzymatic degradation with hyaluronidase and MMP-1 shows that membranes containing the MMP-1 substrate exhibit enhanced enzymatic degradation, compared with control membranes (absence of MMP-1 cleavable peptide or containing a MMP-1 insensitive sequence), being completely degraded after 7 days. Cell viability and proliferation is minimally affected by the enzymatically cleavable functionality of the membrane, but the presence of MMP-1 cleavable sequence does stimulate the secretion of MMP-1 by fibroblasts and interfere with matrix deposition, particularly the deposition of collagen. By showing cell-responsiveness to biochemical signals presented on self-assembling membranes, this study highlights the ability of modulating certain cellular activities through matrix engineering. This concept can be further explored to understand the cellular remodeling process and as a strategy to develop artificial matrices with more biomimetic degradation for tissue engineering applications.This work was funded by the European Regional Development Fund (ERDF) through the Operational Competitiveness Programme "COMPETE" (FCOMP-01-0124-FEDER-014758) and national funds through the Portuguese Foundation for Science and Technology (FCT) under the project PTDC/EBB-BIO/114523/2009. The authors also thank a start-up grant provided by the School of Engineering and Materials Science at QMUL. D.S.F. gratefully acknowledges FCT for the PhD scholarship (SFRH/BD/44977/2008)
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