http://espace.library.uq.edu.au/ The University of Queensland en Fez http://blogs.law.harvard.edu/tech/rss http://espace.library.uq.edu.au/view/UQ:103178 2007-08-23T21:24:35Z Chan, M. og Postula, A. J. og Ding, Y og Jozwiak, L. http://espace.library.uq.edu.au/view/UQ:81308 Bang-bang phase detector based PLLs are simple to design, suffer no systematic phase error, and can run at the highest speed a process can make a working flip-flop. For these reasons designers are employing them in the design of very high speed Clock Data Recovery (CDR) architectures. The major drawback of this class of PLL is the inherent jitter due to quantized phase and frequency corrections. Reducing loop gain can proportionally improve jitter performance, but also reduces locking time and pull-in range. This paper presents a novel PLL design that dynamically scales its gain in order to achieve fast lock times while improving fitter performance in lock. Under certain circumstances the design also demonstrates improved capture range. This paper also analyses the behaviour of a bang-bang type PLL when far from lock, and demonstrates that the pull-in range is proportional to the square root of the PLL loop gain. 2007-08-15T09:39:49Z Chan, Michael J. og Postula, Adam og Ding, Yong og Jozwiak, Lech http://espace.library.uq.edu.au/view/UQ:60068 This paper reports on the design and development of a dividing/phasing network for a compact switched-beam array antenna for Land-vehicle mobile satellite communications, The device is formed by a switched radial divider/combiner and 1-bit phase shifters and generates a sufficient number of beams for the proper satellite tracking. 2007-08-14T16:14:41Z Karmakar, Nemai C. og Bialkowski, Marek E. http://espace.library.uq.edu.au/view/UQ:150376 2008-06-06T16:28:05Z Bialkowski, M. E. og Karmakar, N. http://espace.library.uq.edu.au/view/UQ:175156 This study presents a biconjugate gradient method (BiCG) that can significantly improve the performance of the quasi-static finite-difference scheme, which has been widely used to model field induction phenomena in voxel phantoms. The proposed BiCG method offers remarkable computational advantages in terms of convergence performance and memory consumption over the conventional iterative, successive over-relaxation algorithm. The wide application capability and computational performance of the BiCG method is demonstrated by modelling the exposures of MRI healthcare workers to fields produced by pulsed field gradients, which is presently an important topic of research in light of the Physical Agents Directive 2004/40/EC 2009-04-12T12:09:56Z Wang, H og Liu, F. og Trakic, A. og Crozier, S. http://espace.library.uq.edu.au/view/UQ:102983 2007-08-23T21:17:01Z D'Souza, M. J. og Postula, A. J. og Bergmann, N. W. og Ros, M. http://espace.library.uq.edu.au/view/UQ:103076 2007-08-23T21:20:51Z D'Souza, M. J. og Ros, M. og Postula, A. J. og Bergmann, N. W. http://espace.library.uq.edu.au/view/UQ:135512 2008-04-16T17:59:27Z Liu, Q. og Xue, Y. og Dong, Z.Y. og Ledwich, G. og Yuan, Y. http://espace.library.uq.edu.au/view/UQ:102582 Sharing data among organizations often leads to mutual benefit. Recent technology in data mining has enabled efficient extraction of knowledge from large databases. This, however, increases risks of disclosing the sensitive knowledge when the database is released to other parties. To address this privacy issue, one may sanitize the original database so that the sensitive knowledge is hidden. The challenge is to minimize the side effect on the quality of the sanitized database so that nonsensitive knowledge can still be mined. In this paper, we study such a problem in the context of hiding sensitive frequent itemsets by judiciously modifying the transactions in the database. To preserve the non-sensitive frequent itemsets, we propose a border-based approach to efficiently evaluate the impact of any modification to the database during the hiding process. The quality of database can be well maintained by greedily selecting the modifications with minimal side effect. Experiments results are also reported to show the effectiveness of the proposed approach. 2007-08-23T21:01:41Z Sun, Xingzhi og Yu, Philip S. http://espace.library.uq.edu.au/view/UQ:60439 2007-08-14T16:33:39Z Bialkowski, M. E. og Song, H.J. og Kabacik, P. http://espace.library.uq.edu.au/view/UQ:97106 A number of integrations of the state-based specification language Object-Z and the process algebra CSP have been proposed in recent years. In developing such integrations, a number of semantic decisions have to be made. In particular, what happens when an operation's precondition is not satisfied? Is the operation blocked, i.e., prevented from occurring, or can it occur with an undefined result? Also, are outputs from operations angelic, satisfying the environment's constraints on them, or are they demonic and not influenced by the environment at all? In this paper we discuss the differences between the models, and show that by adopting a blocking model of preconditions together with an angelic model of outputs one can specify systems at higher levels of abstraction. 2007-08-24T01:02:40Z Smith, G. P. og Derrick, J. http://espace.library.uq.edu.au/view/UQ:11097 The design process of building multidatabase systems is not developed enough for the problems of complex systems to be solved in a period of time feasable for any but the largest of companies. Based in part on business re-engineering principles, the methodology of design and analysis presented in this paper allows partial integration of information systems to be governed by the expected functionality. 2004-02-05T00:00:00Z Muhlberger, Ralf M. og Orlowska, Maria E. http://espace.library.uq.edu.au/view/UQ:10710 In this paper we study the academic performance of the large cohort of international students enrolled in the Bachelor of Engineering (Electrical) program at the University of Queensland. The need for this study arises from the extremely rapid internationalisation of the Electrical Engineering program over the past five years and the possible consequences of this growth on graduate quality. We conclude that the international students perform as well as, if not better than, domestic students. Thus international student quality does not appear to represent a major limiting factor when examining limits to program growth. 2004-02-25T00:00:00Z Lovell, Brian C. http://espace.library.uq.edu.au/view/UQ:10754 A major stream of Artificial Life (ALife) research aims to build synthetic life forms, operating in virtual worlds, implemented as computer programs. A clear long-term target for this research is the evolution of digital life-forms with a complexity of structure and behaviour analogous to biological life-forms, potentially exhibiting intelligence and self-awareness. The creation of intelligent, self-aware digital life-forms has clear ethical implications, but there is no current research into how these ethical issues might be addressed. This paper argues that such ethical research is needed. Furthermore, it describes our future research plans to build a solid philosophical foundation for the consideration of these ethical issues. 2004-02-12T00:00:00Z Thiel, Inari og Bergmann, Neil W. og Grey, William http://espace.library.uq.edu.au/view/UQ:100724 2007-08-23T19:41:56Z Miller, T. og Strooper, P. A. http://espace.library.uq.edu.au/view/UQ:96325 2007-08-24T00:26:03Z Long, B. og Strooper, P. A. http://espace.library.uq.edu.au/view/UQ:10583 This paper describes a case study in the testing of distributed systems. The software under test is a middleware system developed in Java. The full test lifecycle is examined including unit testing, integration testing, and system testing. Where possible, traditional tools and techniques are used to carry out the testing. One aspect where this is not possible is the testing of the low-level concurrency, which is often overlooked when testing commercial distributed systems, since the middleware or application server is already developed by a third-party and is assumed to operate correctly. This paper examines testing the middleware system itself, and therefore, a method for testing the concurrency properties of the system is used. The testing revealed a number of faults and design weaknesses, and showed that, with some adaptation, traditional tools and techniques go a long way in the testing of distributed applications. 2004-04-07T00:00:00Z Long, Brad og Strooper, Paul http://espace.library.uq.edu.au/view/UQ:10722 The new technology of reconfigurable System-on-Chip is shown to be a good match to the requirements of real-time embedded systems. In particular, the judicious use of specialised data processing peripherals can reduce the CPU load significantly and greatly ease the task of guaranteeing that real-time deadlines are met in complex multi-processing real-time systems. A catalog of other possible uses for the reconfigurable logic resources on such a chip which can assist in improving real-time system performance is also presented. 2004-02-20T00:00:00Z Bergmann, Neil og Waldeck, Peter og Williams, John http://espace.library.uq.edu.au/view/UQ:137493 2008-05-06T10:04:51Z Pedersen, C. og Diederich, J. http://espace.library.uq.edu.au/view/UQ:137497 2008-05-06T10:14:19Z Pedersen, C. og Diederich, J. http://espace.library.uq.edu.au/view/UQ:100823 2007-08-23T19:45:57Z Clode, S. og Kootsookos, P. J. og Rottensteiner, F. http://espace.library.uq.edu.au/view/UQ:78195 2007-08-15T07:34:32Z Clode, S. og Kootsookos, P. J. og Rottensteiner, F. http://espace.library.uq.edu.au/view/UQ:10313 Building detection from airborne laser scanner (ALS) data is a well-studied problem. Most existing building detection techniques rely on the generation of a digital terrain model (DTM) and a digital surface model (DSM) from last-pulse laser scanner data. The two are compared to form a normalised DSM (nDSM), from which the buildings are detected by use of a simple height threshold. Detection rates using a normalised DSM are very good, however, the accuracy of the building delineation is a function of ALS point spacing and system accuracy. To compete with the accuracies of photogrammetric and terrestrial measurement systems, the typical point spacing of 0.5m to 1.3m would need to be increased ten fold before the systems could be compared. Modern laser scanners can deliver either first- or last-pulse data collected in the same flight. If it exists, the difference between the first-pulse height and last-pulse height indicates that there is a height step somewhere in the laser spot. In a typical urban environment, these steps correspond to trees, power lines and building boundaries or edges. In this paper, first- and last-pulse laser scanner data is combined to improve the accuracy of the building outline delineation. Inclusion of the first-pulse data allows some ALS points to be identified as lying precisely on the building edge (outline) whilst interpolated edge points are used to supplement identified edge points. The identified edge points are assigned to building edges which are subsequently calculated from the points. The paper shows results from a real test site and examines the data acquisition process in order to maximise the benefit of using this method for building extent determination. 2004-08-20T00:00:00Z Clode, Simon P. og Kootsookos, Peter J. og Rottensteiner, Franz http://espace.library.uq.edu.au/view/UQ:8409 Scanning capacitance microscopy (SCM) is a dopant profile extraction tool with nanometre spatial resolution. While it is based on the high-frequency MOS capacitor theory, there are crucial second-order effects which make the extraction of dopant profile from SCM data a challenging task. Due to small size of the SCM probe, the trapped charges in the interface traps at the oxide-silicon dioxide interface surrounding the probe significantly affect the measured SCM data through the fringing electric field created by the trapped charges. In this paper, we present numerical simulation results to investigate the nature of SCM dC/dV data in the presence of interface traps. The simulation takes into consideration the traps response to the ac signal used to measure dC/dV as well as the fringing field of the trapped charge surrounding the probe tip. In the study, we present an error estimation of experimental SCM dopant concentration extraction when the interface traps and fringing field are ignored. The trap distribution in a typical SCM sample is also investigated. 2006-05-09T00:00:00Z Hong, Yang David og Yeow, YewTong og Chim, Wai Kin og Yan, Jian og Wong, Kin Mun http://espace.library.uq.edu.au/view/UQ:99385 2007-08-24T10:30:06Z Chang, M. M. og Wyeth, G. F. http://espace.library.uq.edu.au/view/UQ:66032 A switch-mode assisted linear amplifier (SMALA) combining a linear (Class B) and a switch-mode (Class D) amplifier is presented. The usual single hysteretic controlled half-bridge current dumping stage is replaced by two parallel buck converter stages, in a parallel voltage controlled topology. These operate independently: one buck converter sources current to assist the upper Class B output device, and a complementary converter sinks current to assist the lower device. This topology lends itself to a novel control approach of a dead-band at low power levels where neither class D amplifier assists, allowing the class B amplifier to supply the load without interference, ensuring high fidelity. A 20 W implementation demonstrates 85% efficiency, with distortion below 0.08% measured across the full audio bandwidth at 15 W. The class D amplifier begins assisting at 2 W, and below this value, the distortion was below 0.03%. Complete circuitry is given, showing the simplicity of the additional class D amplifier and its corresponding control circuitry. 2007-08-15T01:49:58Z Walker, G. R. http://espace.library.uq.edu.au/view/UQ:100368 2007-08-23T19:26:32Z Singer, B. og Walker, G. R. http://espace.library.uq.edu.au/view/UQ:98819 2007-08-24T02:11:44Z Long, B. J. og Strooper, P. A. http://espace.library.uq.edu.au/view/UQ:143852 We give an alternative proof of the fact that a planar function cannot exist on groups of even order. The argument involved leads us to define a class of functions which we call semi-planar. Through the introduction of an incidence structure we construct semi-biplanes using semi-planar functions. The method involved represents a new approach to constructing semi-biplanes and provides infinite classes of semi-biplanes unlike any known to the authors. For a particular class of semi-planar functions, we provide a method to construct association schemes with two associate classes. Such an association scheme is equivalent to a strongly regular graph. (C) 1999 Elsevier Science B.V. All rights reserved. 2008-06-10T14:40:09Z Coulter, R. S. og Henderson, M. http://espace.library.uq.edu.au/view/UQ:99333 2007-08-24T10:21:44Z McKinnon, D. N. R. og Jones, B. D. og Lovell, B. C. http://espace.library.uq.edu.au/view/UQ:10957 This paper presents a novel theoretical approach to calculating the apparent contour of a smooth surface. The problem is formulated as a dual space intersection of algebraic tangent cones, which we will consider to be the members of degree d hypersurfaces. The well known theoretical foundation for multi-view geometry is extended in light of this to solve the problems of triangulation and forming multi-view matching constraints for degree d apparent contours. 2004-02-06T00:00:00Z McKinnon, David og Jones, Barry og Lovell, Brian C. http://espace.library.uq.edu.au/view/UQ:77101 Power systems are large scale nonlinear systems with high complexity. Various optimization techniques and expert systems have been used in power system planning. However, there are always some factors that cannot be quantified, modeled, or even expressed by expert systems. Moreover, such planning problems are often large scale optimization problems. Although computational algorithms that are capable of handling large dimensional problems can be used, the computational costs are still very high. To solve these problems, in this paper, investigation is made to explore the efficiency and effectiveness of combining mathematic algorithms with human intelligence. It had been discovered that humans can join the decision making progresses by cognitive feedback. Based on cognitive feedback and genetic algorithm, a new algorithm called cognitive genetic algorithm is presented. This algorithm can clarify and extract human's cognition. As an important application of this cognitive genetic algorithm, a practical decision method for power distribution system planning is proposed. By using this decision method, the optimal results that satisfy human expertise can be obtained and the limitations of human experts can be minimized in the mean time. 2007-08-15T06:53:37Z Duan, Gang og Yu, Yixin og Dong, Zhao Yang http://espace.library.uq.edu.au/view/UQ:103320 2007-08-23T21:30:20Z Viller, S. A. og Brereton, M. F. og Redhead, F. S. og Axup, J. http://espace.library.uq.edu.au/view/UQ:137754 2008-05-07T11:51:36Z McComb, T. og Wildman, L. http://espace.library.uq.edu.au/view/UQ:161764 The understanding of Semantic Web documents is built upon ontologies that define concepts and relationships of data. Hence, the correctness of ontologies is vital. Ontology reasoners such as RACER and FaCT have been developed to reason ontologies with a high degree of automation. However, complex ontology-related properties may not be expressible within the current web ontology languages, consequently they may not be checkable by RACER and FaCT. We propose to use the software engineering techniques and tools, i.e., Z/EVES and Alloy Analyzer, to complement the ontology tools for checking Semantic Web documents. In this approach, Z/EVES is first applied to remove trivial syntax and type errors of the ontologies. Next, RACER is used to identify any ontological inconsistencies, whose origins can be traced by Alloy Analyzer. Finally Z/EVES is used again to express complex ontology-related properties and reveal errors beyond the modeling capabilities of the current web ontology languages. We have successfully applied this approach to checking a set of military plan ontologies 2009-01-27T11:41:37Z Dong, J S og Lee, C H og Lee, H B og Li, Y-F http://espace.library.uq.edu.au/view/UQ:136900 2008-04-30T16:37:49Z Abbosh, A. og Bialkowski, M.E. http://espace.library.uq.edu.au/view/UQ:8198 We present a non-monotonic logic tailored for specifying compact autonomous agent systems. The language is a consistent instantiation of a logic based argumentation system extended with Brooks' subsumption concept and varying degree of belief. Particularly, we present a practical implementation of the language by developing a meta-encoding method that translates logical specifications into compact general logic programs. The language allows n-ary predicate literals with the usual first-order term definitions. We show that the space complexity of the resulting general logic program is linear to the size of the original theory. 2006-06-30T00:00:00Z Song, I. og Governatori, G. http://espace.library.uq.edu.au/view/UQ:35005 Magnetic resonance microscopy (MRM) depends on the use of high field, superconducting magnet systems for its operation. The magnets that are conventionally used are those that were initially designed for chemical structural analysis work. A novel, compact magnet designed specifically for MRM is presented here, and while preserving high field, high homogeneity conditions, has a length less than one-third that of conventional systems. This enables much better access to samples, an important consideration in many MRM experiments. As the homogeneity of a magnet is strongly dependent on its length, novel geometries and optimization techniques are required to meet the requirements of MRM in a compact system. An important outcome of the stochastic optimization performed in this work, is that the use used of a thin superconducting solenoid surrounded by counterwound disk windings provides a mechanism for drastic length reductions over conventional magnet designs. (C) 1998 American Institute of Physics. 2007-08-13T10:33:10Z Crozier, S og Doddrell, DM http://espace.library.uq.edu.au/view/UQ:144516 This paper presents the design and development of a compact switched-beam array antenna for operation with the Australian mobile satellite communications system. Mobilesat(TM). The antenna is formed by eight aperture-coupled microstrip patch elements that are positioned on the side of a truncated comb Two elements, facing the satellite, are activated using an eight-way two-ports-on radial switch. The output ports of the radial switch incorporate 1-bit phase shifters A total of 24 beams are produced using this beam-forming system. lit order to reduce the manufacturing cost, inexpensive substrates and low-cost UHF p-i-n diodes are employed Further reduction in cast is achieved by eliminating coaxial connectors between the beam-forming network and the antenna elements. Experimental results are presented for the individual antenna elements, the beam-forming network, and the entire switched-beam array. (C) 1999 John Wiley & Sons, Inc. 2008-06-10T15:12:25Z Karmakar, N. C. og Bialkowski, M. E. http://espace.library.uq.edu.au/view/UQ:129602 A three-way power divider with ultra wideband behavior is presented. It has a compact size with an overall dimension of 20 mm * 30 mm. The proposed divider utilizes broadside coupling via multilayer microstrip/slot transitions of elliptical shape. The simulated and measured results show that the proposed device has 4.77 +/- 1dB insertion loss, better than 17 dB return loss, and better than 15 dB isolation across the frequency band 3.1 to 10.6 GHz. 2008-02-18T14:36:24Z Abbosh, A.M. http://espace.library.uq.edu.au/view/UQ:104274 2007-08-23T22:13:08Z Shou, G F og Feng, M og Xia, og Wei, Q. og Liu, F og Crozier, S http://espace.library.uq.edu.au/view/UQ:97593 2007-08-24T01:23:26Z Geard, N. L. og Wiles, J. H. og Hallinan, J. S. og Tonkes, B. og Skellett, B. http://espace.library.uq.edu.au/view/UQ:103085 2007-08-23T21:21:10Z Emoto, T. og Akutagawa, M. og Abeyratne, U. R. og Nagashino, H. og Kinouchi, Y. http://espace.library.uq.edu.au/view/UQ:9622 Recently there has been increased interest in logic programming-based default reasoning approaches which are not using negation-as-failure in their object language. Instead, default reasoning is modelled by rules and a priority relation among them. Historically the first logic in this class was Defeasible Logic. In this paper we will study its relationship to other approaches which also rely on the idea of using logic rules and priorities. In particular we will study sceptical LPwNF, courteous logic programs, and priority logic. 2005-04-07T00:00:00Z Antoniou, Grigoris og Maher, Michael J. og Billington, David og Governatori, Guido http://espace.library.uq.edu.au/view/UQ:7838 To enable the resource discovery of audiovisual documents over the WWW, it will be necessary to define content description standards or metadata standards for complex, multi-layered, time-dependent information-rich audiovisual data streams. In particular, this is the primary goal of the emerging MPEG-7 standard, the "Multimedia Content Description Interface" [1], under development by the MPEG group. In the past, a lot of effort has gone into generating descriptors and description schemes for video indexing but comparatively little research has been done on schemas capable of defining the structure, content and semantics of video documents and enabling validation and higher levels of automated content checking. This paper compares the capabilities of the RDF Schema, Extensible Markup Language (XML) Document Type Definitions (DTD's), Document Content Description (DCD), Schema for Object-Oriented XML (SOX) and Document Definition Markup Language (DDML), for supporting and validating hierarchical video descriptions based on Dublin Core, MPEG-7 and a specific hierarchical structure. Finally this paper proposes a hybrid schema based on features from each of these schemas which will satisfy the MPEG-7 Description Definition Language (DDL) requirements. 2006-10-05T00:00:00Z Hunter, Jane og Armstrong, Liz http://espace.library.uq.edu.au/view/UQ:136214 2008-04-24T09:47:33Z Maetschke, S. og Gallagher, M. og Boden, M. http://espace.library.uq.edu.au/view/UQ:8600 The small signal modulation characteristics of a vertical-cavity, surface-emitting laser (VCSEL) are determined using three different measurements: relative intensity noise, frequency response, and high resolution optical spectra. The resonant and damping frequencies were measured, and related rate equation parameters were extracted; excellent agreement was found both between experiment and theory, and amongst the different measurement techniques. The results and procedures are compared, and the findings are presented below. 2006-02-21T00:00:00Z O'Brien, Christopher J. og Majewski, M. L. og Rakic, A. D. http://espace.library.uq.edu.au/view/UQ:7766 Some approaches to the use of linguistic-preference models based on fuzzy relations in the context of multiple factor project assessment are considered. Projects are characterized in terms of linguistic expressions of 'performance' with respect to factors or impacts and the 'importance' of those factors and impacts. Some variations of methods by Wilhelm and Parsaei (1991) and Eldukair and Ayyub (1992) are considered with some possible analogous methods. A simple illustrative, hypothetical example is developed to compare methods in the context of a proposed bridge river crossing in the city of Brisbane, Queensland, Australia, assessed against six factors: (1) cost, (2) lifespan, (3) usage, (4) aesthetics, (5) construction time, and (6) environmental impact. 2006-11-22T00:00:00Z Smith, Phillip http://espace.library.uq.edu.au/view/UQ:175820 In MRI engineering, regularization techniques can be effectively used to solve ill-posed problems in electromagnetics, such as the inverse design of phased array RF coils. In this work, a comparison on various regularization methods which are employed to numerically reconstruct a divergence-free cylindrical surface of current distribution is investigated. It is found that a coil current pattern is very sensitive to the modes of the basis function describing the current densities on the coil surface; and iterative regularization techniques generally produce better B1 field profiles compared with direct approaches. 2009-04-15T11:34:14Z Li, Y. og Wang, H. og Liu, F. og Li, B.K. og Shou, G. og Weber, E. og Crozier, S. http://espace.library.uq.edu.au/view/UQ:100364 2007-08-23T19:26:24Z Robinson, R. R. og Indulska, J.