18,593 research outputs found

    Do changes in organisational status affect financial performance?

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    School of Managemen

    Dickens, Edward Said and Australia

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    An Expert System for Managing an Activated Sludge Wastewater Treatment Plant

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    A diagnostic expert system for an activated sludge wastewater treatment plant has been designed to link with a relational database management system for obtaining operational parameter values that are used by the program to diagnose operational problems that may occur in the process. The problems that are dealt with by the system are bulking sludge, floating sludge, defloculation, ashing, solids washout, foaming problems, high soluble effluent BOD and problems in the aeration system. The link between the expert system and the database is accomplished via programming that is initiated by the expert system program. The operator of the system is not required to perform any action in order for the appropriate retrievals of operational parameter values to occur. The system is designed such that parameter values are retrieved from the database if such a database exists and contains appropriate values and, if no such database exists or if the appropriate values are not present, the operator is queried for the parameter values. Since many wastewater treatment plants maintain database management systems for operational parameter values, such an expert system has advantages over stand alone systems. However, an override of the database query is possible, making the system useful for experimental queries and for training

    Fibre lasers: the new wave in material processing

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    In the last few years, fibre lasers have established themselves as the preferred laser source in many applications. The combination of small size, maintenance-free operation, thermal and electrical efficiency combined with outstanding (diffraction-limited) beam quality have made the fibre laser an attractive alternative to more established technologies. In fact, in some processes the fiber laser is the enabling technology. Unique among high power lasers, the fiber laser is monolithic, the light being entirely confined to the fiber core. This gives immunity to thermal distortion of the beam, almost instant startup, very high stability and protection from the environment. Maintenance is minimal, since no realignment or cleaning of components is necessary

    Photocatalytic degradation of an organophosphorus compound by porous Au- and WO3- modified TiO2

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    Organophosphorus (OP) compounds are highly toxic substances that are often used as chemical warfare agents and pesticides. OP pesticides are the most widely used class of pesticide in the world, and due to their ubiquity, the contamination of agricultural runoff by OP pesticides has become a problem of global concern. One of the more attractive solutions that has been proposed is the use of photocatalytic degradation to decontaminate affected water supplies. In the present work, the visible-light photocatalytic activity of a series of porous Au-WO3-TiO2 photocatalysts with variable concentrations of Au (0, 1, 3, and 5 weight percent) synthesized using mesoporous SiO2 as a template was evaluated in the aqueous degradation reaction of an OP agent, dimethyl methylphosphonate (DMMP). The Au and WO3 were added to the catalysts using sonochemical deposition and incipient wetness impregnation, respectively. The photocatalytic activity of the ternary Au-WO3-TiO2 series was compared to that of a WO3-free series of Au-TiO2 catalysts with comparable Au loadings. The catalysts were characterized by scanning electron microscopy (SEM), powder x-ray diffractometry (PXRD), and N2-physisorption. The SEM and N2-physisorption analyses indicated the Au-TiO2 and Au-WO3-TiO2 particles had high surface areas of 135 m2 g-1 and 100 m2 g-1, respectively, with particle diameters of 1-3 ÎŒm. No crystalline WO3 was detected on the WO3-containing species, indicating the formation of a monolayer of WO3 on the surface of the TiO2. The sonochemically deposited gold nanoparticles (NPs) were found to be 3-10 nm in diameter. The photocatalytic degradation of DMMP was monitored by quantitative GCMS analysis. The independent addition of Au NPs or WO3 to the surface of the TiO2 did not significantly affect the total degradation of DMMP after 30 hours of irradiation relative to unmodified TiO2, however the presence of both Au and WO3 on the surface of the TiO2 significantly increased the total degradation of DMMP after 30 hours, reaching the detection limit for the 1 and 3 weight percent catalysts. It was found that the photocatalytic activity of the Au-WO3-TiO2 catalysts was not significantly influenced by the weight percent Au for the concentrations studied

    Quantitative Verification: Formal Guarantees for Timeliness, Reliability and Performance

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    Computerised systems appear in almost all aspects of our daily lives, often in safety-critical scenarios such as embedded control systems in cars and aircraft or medical devices such as pacemakers and sensors. We are thus increasingly reliant on these systems working correctly, despite often operating in unpredictable or unreliable environments. Designers of such devices need ways to guarantee that they will operate in a reliable and efficient manner. Quantitative verification is a technique for analysing quantitative aspects of a system's design, such as timeliness, reliability or performance. It applies formal methods, based on a rigorous analysis of a mathematical model of the system, to automatically prove certain precisely specified properties, e.g. ``the airbag will always deploy within 20 milliseconds after a crash'' or ``the probability of both sensors failing simultaneously is less than 0.001''. The ability to formally guarantee quantitative properties of this kind is beneficial across a wide range of application domains. For example, in safety-critical systems, it may be essential to establish credible bounds on the probability with which certain failures or combinations of failures can occur. In embedded control systems, it is often important to comply with strict constraints on timing or resources. More generally, being able to derive guarantees on precisely specified levels of performance or efficiency is a valuable tool in the design of, for example, wireless networking protocols, robotic systems or power management algorithms, to name but a few. This report gives a short introduction to quantitative verification, focusing in particular on a widely used technique called model checking, and its generalisation to the analysis of quantitative aspects of a system such as timing, probabilistic behaviour or resource usage. The intended audience is industrial designers and developers of systems such as those highlighted above who could benefit from the application of quantitative verification,but lack expertise in formal verification or modelling

    Theory of tunneling spectroscopy in UPd2Al3

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    There is still significant debate about the symmetry of the order parameter in the heavy-fermion superconductor UPd2_{2}Al3_{3}, with proposals for cos(k3), cos(2k3), sin(k3),and exp(i\phi) sin(k3). Here we analyze the tunneling spectroscopy of this compound and demonstrate that the experimental results by Jourdan et al are inconsistent with the last two order parameters, which are expected to show zero-bias conductance peaks. We propose a definitive tunneling experiment to distinguish between the first two order parameters.Comment: 6 pages, 8 figure