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(2001)Journal ArticleBiosolids are the reusable organic materials removed from sewage during treatment. Different options for biosolids handling in Sydney, Australia, are compared using life-cycle assessment. Two key comparisons are made: of system scenarios (scenario one - local dewatering and lime-amendment; scenario two - a centralized drying system) and of technologies (thermal drying versus lime-amendment). The environmental issues addressed are energy consumption, global warming potential (GWP) and human toxicity potential (HTP). Scenario two would consume 24% more energy than scenario one. This is due to the additional electricity for pumping and particularly the petrochemical methane that supplements biogas in the dryer. A centralized system using the same technologies as scenario one has approximately the same impacts. The GWP and HTP of the different scenarios do not differ significantly. The assessment of technology choices showed significant differences. The ample supply of endogenous biogas at North Head Sewage Treatment Plant (STP) for the drying option for allows reductions, relative to the lime amendment option, of 68% in energy consumption, 45% in GWP and 23% in HTP. Technology choices have more significant influence on the environmental profile of biosolids processing than the choice of system configurations. Controlling variables for environmental improvement are the selection of biogas fuel, avoidance of coal-sourced electrical energy, minimization of trucking distances and raising the solids content of biosolids products.
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(2012)Journal ArticleWater supply is a key consideration in sustainable urban planning. Recycling may increase the expense and energy consumption of supply systems, raising optimisation questions. Ideally, detailed quantitative sustainability assessments are undertaken during the planning stage in order to inform the decision-making process. In reality, however, the significant time and cost associated with undertaking such detailed environmental and economic assessments is often cited as a barrier to wider implementation of these key decision-support tools, particularly for decisions made at the local or regional government level. In an attempt to counter this barrier of complexity, four water service providers in Melbourne (Australia) funded the development of a publicly available streamlined Environmental Sustainability Assessment Tool (ESAT). The tool is aimed at a wide range of decision-makers to assist them in broadening the type and number of water servicing options that can be considered for greenfield or backlog developments. ESAT consists of a simple user interface and draws upon life cycle inventory data to allow for rapid estimation of the environmental and economic performance of different water servicing scenarios. Scenario options can then be further prioritised by means of an interactive multicriteria analysis. The intent of this paper is to identify the key issues to be considered in a streamlined sustainability assessment tool for the urban water industry and to demonstrate the feasibility of generating accurate life cycle assessments (LCAs) and life cycle costings (LCCs) using such a tool. We use a real-life case study consisting of three separate scenarios for a planned urban development to show that this kind of tool can emulate LCA and LCC outcomes obtained by more detailed studies. We hope this kind of approach will support ‘sustainability thinking’ early on in the decision-making process, thereby encouraging more sustainable water and sewerage infrastructure solutions.
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(2008)Journal ArticleIn the global positioning system (GPS), code division multiple access (CDMA) signals are used. Because of the known spectral characteristics of the CDMA signal, continuous wave (CW) interference has a predictable effect on the different pseudo random noise (PRN) spreading codes (unique to each satellite) depending on the Doppler frequency of the signal. The Doppler frequency for each signal is also predictable once the receiver position is known. As different satellite signals have different Doppler frequencies, the effect on the signal quality is also different. In this paper first the effect is studied analytically. The concept of an `exclusion zone` is defined and analyzed for each satellite. This exclusion zone, where that satellite should not be used due to interference degradation, is shown to be predictable for each satellite as a function of time. Using this prediction, the CW interference effect on the positioning quality of the receiver can be mitigated by ignoring the affected satellites within exclusion zones when performing position evaluation. The threshold beyond which a satellite should be excluded is then derived by studying the mutual effects of the geometry and the signal quality of that satellite on the positioning quality. Receiver autonomous integrity monitoring (RAIM) uses redundancy in measurements to perform an internal consistency check to see if all of the measurements are satisfactory. In this paper this technique is also used to mitigate the effect of CW interference on the positioning accuracy. Finally it is shown that the prediction of the exclusion zone for each satellite outperforms the RAIM algorithm in mitigation the effect of the interference when 5 satellites are visible. © 2007 Springer-Verlag.
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(2007)Journal ArticleTo provide the proper positioning signal, global navigation satellite systems (GNSSs), need very accurate satellite on-board time references. For GPS, GLONAS and GALILEO, such time references are spaceborn atomic clocks. The augmentation/positioning system QZSS (Quasi-Zenith Satellite System) would need the same kind of accuracy. However, due to the high QZSS satellite visibility, a completely new kind of time reference method, where no on-board atomic references are needed, could be adopted. If an opportune ground location is chosen, QZSS satellites are fully visible for the whole orbital period. Therefore, a main time reference (atomic clock), located on the ground, could be kept synchronized to a inexpensive and compact time reference (VCXO) on board each QZSS satellite. In the following article, a new practical implementation of such a remote synchronization method is proposed and some of its problematic are discussed.
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(2008)Journal ArticleA real-time GPS/INS integrated system based on a field programmable gate array (FPGA) platform has recently been developed at the Satellite Navigation and Positioning Laboratory, School of Surveying & Spatial Information Systems, University of New South Wales. Compared with an application-specific integrated circuit (ASIC) approach, the FPGA approach can shorten the research and development cycle. Its reprogrammable hardware provides a system design methodology of lower risk and maximum flexibility, being able to integrate a wide range of GPS and INS sensor packages. Tests demonstrate the feasibility of this type of system on an FPGA platform. Functionality of the system has been tested including; the stability and accuracy of the time synchronisation mechanism, the performance of the hardware and software architecture, the workability and accuracy of the algorithm, and finally, the capability of the integrated system to bridge GPS outages.
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(2005)Journal ArticleSyren, a location-based, multi-speaker augmented audio reality installation was presented as a shipboard exhibit at the 12th International Symposium on Electronic Art in August 2004. It was conceived as a continuous 3-day spatial audio experience that augments the landscape through the Baltic archipelago with location-based audio media, spatialised through a 12- channel speaker array. As the ship tracks between Helsinki, Mariehamn, Stockholm and Tallinn, listeners on the upper deck hear sounds that are perceived to originate from geographic features. Our custom GIS is derived from electronic nautical charting information that includes coastlines, buoys and beacons. A handheld GPS provides both position and direction data that was used by a software system to drive parameters of the spatial audio presentation. The sound production for the artwork was created using the custom application that enabled the artist to place sound media in relation to a real-world map. An important component to this software was the ability to audition the audio experience without ever taking the journey.
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(2008)Journal ArticleComb filters can be designed by replacing single delays in digital filters by multiple delays. These filters are `periodic` in the sense that their frequency response repeats itself at fixed intervals. They are thus well suited to a signal such as GPS L1 which has a spectrum made up of lines separated by the code repetition frequency of 1 kHz. In this paper we examine how periodic filters can be used in a conventional GPS L1 receiver. We find that comb filters assist with acquisition of weak signals, and can improve code-tracking performance. © 2007 Springer-Verlag.