Engineering

Publication Search Results

Now showing 1 - 10 of 59
  • (2004) Engel, Frank; Heiser, Gernot; MUMFORD, PETER; Parkinson, Kevin; Rizos, Chris
    Conference Paper
    In this paper we present the concept of an FPGA-based GPS receiver architecture with the aim of providing a framework for investigating new receiver architectures for current and upcoming GNSS standards. This development system facilitates researchers to prove new receiver concepts using real signals, which nowadays can only be simulated using tools such as Matlab. One will be able to work with the satellites as soon as they are operational, rather than having to wait for the availability of commercial products. The system allows individual development of signal processing solutions for base-band processing. A soft-core processor implements higher layer services that provide data to the user.

  • (2008) Lundie, S; Kröger, T; Peters, G; Rowley, HV; Feitz, A
    Conference Paper
    In this article, Life Cycle Assessment (LCA) and Life Cycle Costing (LCC) quantify the performance of variable and fixed speed centrifugal chillers using two refrigerants (HCFC 123 or HFC 134A) in commercial air-conditioning systems. Electricity demand during operation causes the highest environmental and economic burdens for all options. Detailed energy simulation shows that chillers operate most of the time in partial load, therefore energy-optimised variable-speed systems are preferable. We demonstrate the significance of understanding each phase of the life cycle to optimise overall performance. A systems approach, if broadly applied, could reduce the barriers between stakeholders along supply chains.

  • (2008) Lundie, S; Peters, G; Rowley, HV; Schulz, M; Salem, J
    Conference Paper
    A life cycle assessment (LCA) was used to evaluate the influence of choosing refrigerants R22, R407C or R410A for domestic air conditioners. Other than the chemical characteristics of R22, the other key factor was the operating pressure. Due to high pressure operation, the R410A system experienced the highest leakage rate, energy consumption and global warming potential (GWP). Sensitivity analysis was used to examine the influence of leakage and to show that, compared with the unit’s lifespan, setpoint and efficiency, the climate in different Australian locations and the load profile have significant effects on the energy use and GWP.

  • (2006) Peters, Greg M.; Rowley, Hazel; Lundie, S; Flint, Megan
    Conference Paper
    Challenges like population growth and climate change are maintaining a high level of dynamism in the water industry, resulting in large capital investments and the consideration of alternatives to conventional water supplies. In this environment, LCA is appreciated as a useful planning tool, but it has not yet achieved its full potential due to the lack of a national sustainability framework and other factors. In this paper, examples of recent LCAs in the water industry are discussed. The practical justification and resourcing of LCAs are examined. In addition, two case studies are presented illustrating how LCA can assist the planning process and the degree to which hybridisation presents a methodological challenge to traditional process LCA. Finally, the implications of the new WSAA Sustainability Framework for the future of LCA practice are discussed.

  • (2006) Bandyopadhyay, Srikanta; Zeng, Qinghua; Berndt, Christopher C.; Rizkalla, Sami; Gowripalan, N.; Matisons, Janis
    Conference Paper
    The topics of ACUN-5 will cover all aspects of the science and technology of composite materials, from materials fabrication, processing, manufacture, structural and property characterisation, theoretical analysis, modelling and simulation, materials design to a variety of applications, such as aerospace, automotive, infrastructure, packaging, ship-building, and recreational products. ACUN-5 will bring together the latest research and developments of the complete range of composite materials, including biocomposites, medical-composites, functional and smart composites, gradient and layered composites, nanocomposites, structural composites and mimicking natural materials. The reinforcements will range from nano-, micro-, meso- to macro-scale in polymer, metal, ceramic and cementitious matrices.

  • (2007) Tabatabaei Balaei, Asghar; Motella, Beatrice; Dempster, Andrew
    Conference Paper
    Radio frequency interference affects the integrity, continuity and availability of the GPS system. These are the highly important parameters for critical applications like aviation. Interference also has an adverse impact on accuracy. Continuously operating reference stations (CORS) networks are employed to improve the accuracy of GPS position measurements used by surveyors. Interference can affect the normal operation of these stations. The goal of this work was to find if there is an interference source for GPS L1 in Sydney. It was shown that the third harmonic emission from a TV station lies within the L1 bandwidth. This source of interference is characterized in terms of frequency and power and the effect that it can have on the RF front-end of the receiver.

  • (2007) Glennon, Eamonn; Dempster, Andrew
    Conference Paper
    The cross correlation properties of the 1023 chip Gold (C/A) codes can cause difficulties in scenarios where both strong and weak GPS signals need to be processed. Such cases are increasingly likely given the new applications of GPS, with examples being the processing of GPS signals in E911 cellular phone applications and the use of bistatic GPS as a remote sensing tool. This coupled with the increasing use of software-defined radio (software correlation) for either cost-saving or flexibility enhancing reasons have resulted in a need to mitigate cross correlations within such systems. This paper provides details on two techniques developed by the authors for the mitigation of GPS cross correlations, both of which have been tested and implemented within a software correlator that has been written in the C programming language. Details on the software correlator are also provided as the table lookup requirements for the correlator are smaller than those previously reported. Test results indicating the effectiveness of the algorithms are presented, with a comparison between the two methods being performed., The datasets containing cross correlations were obtained by capturing the output of a GPS radio front end chip attached to a hardware GPS simulator.

  • (2007) Geng, Y; Cole, A.; Dempster, A; Rizos, C; Wang, J
    Conference Paper
    A navigation system based on a low-cost, low-grade MEMS inertial measurement unit (IMU) integrated with differential GPS has been developed for machine automation applications. Because the inertial sensors have no ability to measure Earth rotation, the attitude errors of pitch and heading cannot be obtained using only IMU measurements. To overcome this deficiency, two Kalman filters are used for robust estimation of navigation parameters and the errors of inertial sensors. An adaptive fading factor Kalman filter uses a GPS dynamic model to generate the velocities and accelerations which can be used to acquire approximate pitch and heading values. Another Kalman filter is used to integrate position, velocity and attitude from both the IMU and GPS so that position and attitude can be estimated directly - due to their individual observabilities. The drift error of the inertial sensors is also well compensated. The proposed algorithm has been implemented into post-processing integration software and has been tested in the field. The test results demonstrated that this robust MEMS/DGPS integrated system has the capability of providing continuous and reliable navigation for machine automation applications.

  • (2007) Dempster, A.G; Hewitson, S
    Conference Paper
    In the near future, there could be as many as four global navigation satellite systems (GNSS) and three regional navigation satellite systems (RNSS). This paper examines the visibility of these systems, identifying Australia as a good location to view all of them. The impacts on receiver design are also examined at sub-system level, revealing that a 'system of systems' receiver would be far more sophisticated than a basic GPS L1 receiver.

  • (2008) LI, M; WANG, F; Tabatabaei Balaei, Asghar; DEMPSTER, A.G; RIZOS, C
    Conference Paper