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:102995 2007-08-23T00:00:00Z Yuan, B. og Gallagher, M. R. http://espace.library.uq.edu.au/view/UQ:231410 2011-03-07T11:45:17Z Groza, T og Handschuh, S http://espace.library.uq.edu.au/view/UQ:197347 2010-03-02T00:00:00Z Harlow, T.J. og Gogarten, J. P. og Ragan, M. .A. http://espace.library.uq.edu.au/view/UQ:111604 2007-09-19T00:00:00Z Harlow, Timothy J. og Gogarten, J. Peter og Ragan, Mark A. http://espace.library.uq.edu.au/view/UQ:110863 A hybrid evaluation method using both the spectral- and the spatial-domain techniques is proposed for the evaluation of the Summer-feld-type integrals resulting from the full-wave analysis of microstrip structures. This method combines the advantages of the spectral-domain for the evaluation of near fields and the spatial-domain method for the evaluation of far-fields. This method is simple and needs no additional formulations. It also provides an easy alternative method to handle the inefficiency of calculation with the singularity of the Green's function. Numerical results are used to demonstrate the simplicity and the accuracy of this method. 2007-09-19T00:00:00Z Hui, H. T. og Yung, E. K. N. og Sheng, X. Q. og Chan, C. H. http://espace.library.uq.edu.au/view/UQ:263846 2011-12-20T13:03:51Z Liu, Feng og Zhu, Jianfeng og Xia, Ling og Crozier, Stuart http://espace.library.uq.edu.au/view/UQ:36284 This paper describes a hybrid numerical method of an inverse approach to the design of compact magnetic resonance imaging magnets. The problem is formulated as a field synthesis and the desired current density on the surface of a cylinder is first calculated by solving a Fredholm equation of the first, kind. Nonlinear optimization methods are then invoked to fit practical magnet coils to the desired current density. The field calculations are performed using a semi-analytical method. The emphasis of this work is on the optimal design of short MRI magnets. Details of the hybrid numerical model are presented, and the model is used to investigate compact, symmetric MRI magnets as well as asymmetric magnets. The results highlight that the method can be used to obtain a compact MRI magnet structure and a very homogeneous magnetic field over the central imaging volume in clinical systems of approximately 1 m in length, significantly shorter than current designs. Viable asymmetric magnet designs, in which the edge of the homogeneous region is very close to one end of the magnet system are also presented. Unshielded designs are the focus of this work. This method is flexible and may be applied to magnets of other geometries. (C) 2000 American Association of Physicists in Medicine. [S0094-2405(00)00303-5]. 2007-08-13T00:00:00Z Zhao, Huawei og Crozier, Stuart og Doddrell, David M. http://espace.library.uq.edu.au/view/UQ:286919 Noninvasive electrocardiographic imaging, such as the reconstruction of myocardial transmembrane potentials (TMPs) distribution, can provide more detailed and complicated electrophysiological information than the body surface potentials (BSPs). However, the noninvasive reconstruction of the TMPs from BSPs is a typical inverse problem. In this study, this inverse ECG problem is treated as a regression problem with multi-inputs (BSPs) and multioutputs (TMPs), which will be solved by the Maximum Margin Clustering- (MMC-) Support Vector Regression (SVR) method. First, the MMC approach is adopted to cluster the training samples (a series of time instant BSPs), and the individual SVR model for each cluster is then constructed. For each testing sample, we find its matched cluster and then use the corresponding SVR model to reconstruct the TMPs. Using testing samples, it is found that the reconstructed TMPs results with the MMC-SVR method are more accurate than those of the single SVR method. In addition to the improved accuracy in solving the inverse ECG problem, the MMC-SVR method divides the training samples into clusters of small sample sizes, which can enhance the computation efficiency of training the SVR model. 2012-12-09T00:14:28Z Jiang, Mingfeng og Liu, Feng og Wang, Yaming og Shou, Guofa og Huang, Wenqing og Zhang, Huaxiong http://espace.library.uq.edu.au/view/UQ:23864 The reconstruction of power industries has brought fundamental changes to both power system operation and planning. This paper presents a new planning method using multi-objective optimization (MOOP) technique, as well as human knowledge, to expand the transmission network in open access schemes. The method starts with a candidate pool of feasible expansion plans. Consequent selection of the best candidates is carried out through a MOOP approach, of which multiple objectives are tackled simultaneously, aiming at integrating the market operation and planning as one unified process in context of deregulated system. Human knowledge has been applied in both stages to ensure the selection with practical engineering and management concerns. The expansion plan from MOOP is assessed by reliability criteria before it is finalized. The proposed method has been tested with the IEEE 14-bus system and relevant analyses and discussions have been presented. 2007-07-05T00:00:00Z Xu, Zhao og Dong, Zhao Yang og Wong, Kit Po http://espace.library.uq.edu.au/view/UQ:176636 Existing prediction methods in moving objects databases cannot forecast locations accurately if the query time is far away from the current time. Even for near future prediction, most techniques assume the trajectory of an object's movements can be represented by some mathematical formulas of motion functions based on its recent movements. However, an object's movements are more complicated than what the mathematical formulas can represent. Prediction based on an object's trajectory patterns is a powerful way and has been investigated by several work. But their main interest is how to discover the patterns. In this paper, we present a novel prediction approach, namely The Hybrid Prediction Model, which estimates an object's future locations based on its pattern information as well as existing motion functions using the object's recent movements. Specifically, an object's trajectory patterns which have ad-hoc forms for prediction are discovered and then indexed by a novel access method for efficient query processing. In addition, two query processing techniques that can provide accurate results for both near and distant time predictive queries are presented. Our extensive experiments demonstrate that proposed techniques are more accurate and efficient than existing forecasting schemes. 2009-04-17T11:02:38Z Jeung, Hoyoung og Liu, Qing og Shen, Heng Tao og Zhou, Xiaofang http://espace.library.uq.edu.au/view/UQ:13275 Market-based transmission expansion planning gives information to investors on where is the most cost efficient place to invest and brings benefits to those who invest in this grid. However, both market issue and power system adequacy problems are system planers’ concern. In this paper, a hybrid probabilistic criterion of Expected Economical Loss (EEL) is proposed as an index to evaluate the systems’ overall expected economical losses during system operation in a competitive market. It stands on both investors’ and planner’s point of view and will further improves the traditional reliability cost. By applying EEL, it is possible for system planners to obtain a clear idea regarding the transmission network’s bottleneck and the amount of losses arises from this weak point. Sequentially, it enables planners to assess the worth of providing reliable services. Also, the EEL will contain valuable information for moneymen to undertake their investment. This index could truly reflect the random behaviors of power systems and uncertainties from electricity market. The performance of the EEL index is enhanced by applying Normalized Coefficient of Probability (NCP), so it can be utilized in large real power systems. A numerical example is carried out on IEEE Reliability Test System (RTS), which will show how the EEL can predict the current system bottleneck under future operational conditions and how to use EEL as one of planning objectives to determine future optimal plans. A well-known simulation method, Monte Carlo simulation, is employed to achieve the probabilistic characteristic of electricity market and Genetic Algorithms (GAs) is used as a multi-objective optimization tool. 2007-03-30T00:00:00Z Lu, M. og Dong, Z. Y. og Saha, T. K. http://espace.library.uq.edu.au/view/UQ:104247 2007-08-23T00:00:00Z Lu, M. og Dong, Z Y og Saha, T K http://espace.library.uq.edu.au/view/UQ:137349 We demonstrate a hybrid reconfigurable cluster-on-chip architecture with a cross-platform Message Passing Interface (MPI), a cross-platform parallel image processing library and a sample application. We describe the system, network architecture, MPI library and the parallel image processing library implementations. We validate the performance, scalability and suitability of MPI as a software interface to enable cross-platform application parallelism on reconfigurable hybrid cluster-on-chip systems and desktop cluster systems. The presented results are promising, showing the suitability, scalability and performance of parallelisation of image processing algorithms with a cross-platform MPI implementation. 2008-05-02T00:00:00Z Syed, Irfan og Williams, John A. og Bergmann, Neil W. http://espace.library.uq.edu.au/view/UQ:282372 With the fast growing of Web 2.0, social networking sites such as Facebook, Twitter and LinkedIn are becoming increasingly popular. Link prediction is an important task being heavily discussed recently in the area of social networks analysis, which is to identify the future existence of links among entities in the social networks so that user experiences can be improved. In this paper, we propose a hybrid time-series link prediction model framework called DynamicNet for large social networks. Compared to existing works, our framework not only takes timing as consideration by using time-series link prediction model but also combines the strengths of topological pattern and probabilistic relational model (PRM) approaches. We evaluated our framework on three known corpora, and the favorable results indicated that our proposed approach is feasible. 2012-09-24T11:44:22Z Zhu, Jia og Xie, Qing og Chin, Eun Jung http://espace.library.uq.edu.au/view/UQ:284990 2012-11-15T11:22:35Z Barnes, Nick og Baumgartner, Peter og Caetano, Tiberio og Durrant-Whyte, Hugh og Klein, Gerwin og Sanderson, Penelope og Sattar, Abdul og Stuckey, Peter og Thiebaux, Sylvie og Van Hentenryck, Pascal og Walsh, Toby http://espace.library.uq.edu.au/view/UQ:100830 2007-08-23T00:00:00Z Palmer, J. E. og Martorella, M. og Longstaff, I.D. http://espace.library.uq.edu.au/view/UQ:147252 2008-06-06T13:19:36Z Kabacik, P. og Sachse, K. og Sawicki, A. og Jaworski, G. og Bialkowski, M. E. http://espace.library.uq.edu.au/view/UQ:99105 2007-08-24T00:00:00Z Mojarrabi, B. og Homer, J. P. og Kubik, K. K. T. og Hahn, M. og Rizos, C. http://espace.library.uq.edu.au/view/UQ:61718 The paper discusses the bistatic radar parameters for the case when the transmitter is a satellite emitting communication signals. The model utilises signals from an Iridium-like low earth orbiting satellite system. The maximum detection range, when thermal noise-limited, is discussed at the theoretical level and these results are compared with experimentation. Satellite-radar signal levels and the power of ground reflections are evaluated. 2007-08-14T00:00:00Z Cherniakov, M. og Nezlin, D. og Kubik, K. http://espace.library.uq.edu.au/view/UQ:8572 Background: A quantitative understanding of airway sizes and proportions and a reference point for comparisons are important to a bronchoscopist. The aims of this study were to measure large airway areas, and define proportions and predictors of airway size in children. Methods: A validated videobronchoscope technique was used to measure in-vivo airway cross-sectional areas (cricoid, right (RMS) and left (LMS) main stem and major lobar bronchi) of 125 children. Airway proportions were calculated as ratios of airways to cricoid areas and to endotracheal tube (ETT) areas. Mann Whitney U, T-tests, and one-way ANOVA were used for comparisons and standard univariate and backwards, stepwise multivariate regression analyses were used to define airway size predictors. Results: Airways size increased progressively with increasing age but proportions remained constant. The LMS was 21% smaller than the RMS. Gender differences in airways' size were not significant in any age group or airway site. Cricoid area related best to body length (BL): cricoid area (mm2) = 26.782 + 0.254*BL (cm) while the RMS and LMS area related best to weight: RMS area (mm2) = 23.938 + 0.394*Wt (kg) and LMS area (mm2) = 20.055 + 0.263*Wt (kg) respectively. Airways to cricoid ratios were larger than airway to ETT ratios (p=0.0001). Conclusions: The cricoid and large airways progressively increase in size but maintain constant proportional relationships to the cricoid across childhood. The cricoid area correlates with body length while the RMS and LMS are best predicted by weight. These data provide for quantitative comparisons of airway lesions. 2006-03-06T00:00:00Z Masters, Ian B. og Ware, Robert S. og Zimmerman, Paul V. og Lovell, Brian og Wootton, Richard og Francis, Paul V. og Chang, Anne B. http://espace.library.uq.edu.au/view/UQ:60075 This paper is concerned with the design of a Ku-band active transmit-array module of transistor amplifiers excited by either a pyramidal horn or a patch array Optimal distances between the active transmit array and the signal-launching:receiving device, which is either a passive corporate-fed array or a horn, are determined to maximise the power gain at a design frequency: Having established these conditions, the complete structure is investigated in terms of operational bandwidth and near-field and far-field distributions measured at the output side of the transmit array, The experimental results show that the use of a corporate-fed array as an illuminating/receiving device gives higher gain and significantly larger operational bandwidth, An explanation for this behavior is sought. 2007-08-14T00:00:00Z Bialkowski, Marek E. og Song, Hyok J. http://espace.library.uq.edu.au/view/UQ:9621 In this paper we present a labelled proof method for computing nonmonotonic consequence relations in a conditional logic setting. The method is based on the usual possible world semantics for conditional logic. The label formalism KEM, introduced to account for the semantics of normal modal logics, is easily adapted to the semantics of conditional logic by simply indexing labels with formulas. The inference rules are provided by the propositional system KE+ - a tableau-like analytic proof system devised to be used both as a refutation and a direct method of proof - enlarged with suitable elimination rules for the conditional connective. The resulting algorithmic framework is able to compute cumulative consequence relations in so far as they can be expressed as conditional implications. 2005-04-07T00:00:00Z Artosi, Alberto og Governatori, Guido og Rotolo, Antonino http://espace.library.uq.edu.au/view/UQ:236747 Hybrid Wireless Mesh Networks (WMN) can be quickly deployed at disasters sites to provide high-capacity wireless communications. As with other WMN networks, a routing protocol is required to find a path between non-neighboring source and destination nodes. The routing metric used by the routing protocol can have a significant impact on the performance of the network. Most of the existing routing metrics for multiradio, multihop WMNs are calculated using external information (such as link quality statistics and channel information). In a network with highly mobile nodes, such as an Hybrid WMN, the required frequent exchange of this information can be very expensive, resulting in degraded performance. In this paper, we present the ALARM routing metric, which is computed using the number of packets queued per wireless interface. This computed value offers an accurate representation of the traffic load, link quality, interference and noise levels. As only this one value need be exchanged to compute ALARM, the overhead associated with the metric is less than existing approaches. With the help of extensive simulations, we show that ALARM outperforms well-know routing metrics like ETT and WCETT under varying mobility and traffic load conditions in HybridWMNs. Validation of these simulation results is obtained from a small-scale testbed deployment. † 2011-03-16T00:00:00Z Pirzada, Asad Amir og Wishart, Ryan og Portmann, Marius og Indulska, Jadwiga http://espace.library.uq.edu.au/view/UQ:103080 2007-08-23T00:00:00Z Zhou, S. og Hogan, M. og Ardon, S. og Portmann, M. og Hu, T og Wongrujira, K og Seneviratne, A. http://espace.library.uq.edu.au/view/UQ:103186 2007-08-23T00:00:00Z Zhang, Y. og Xu, G og Zhou, X. http://espace.library.uq.edu.au/view/UQ:175655 This paper considers the use of multiple transmit antennas to deliver independent data streams to multiple users. In particular, we examine a multi-user technique known as vector perturbation. We provide a new lattice-theoretic approach to analyze its performance in the presence of Rayleigh fading. Vector perturbation is based on performing a channel inversion, with the additional step of perturbing the data signal prior to linear preceding to significantly reduce the required transmit power. To analyze such systems it is necessary to calculate the resulting average energy of the sphere-encoded signal vector, as this determines the signal-to-noise ratio (SNR) at the output of the demodulator. Previous results presented in the literature were partially analytic, requiring further numerical evaluation. Here, we derive a concise approximation to the output SNR. We also provide tight upper and lower bounds on the bit error rate for the reception of QAM symbols using the required modulo demodulator, as a function of the average energy of the sphere- encoded signal vector. 2009-04-14T00:00:00Z Ryan, D. J. og Collings, I. B. og Clarkson, I. V. L. og Heath, R. W. http://espace.library.uq.edu.au/view/UQ:9875 We propose a circuit sizing model that takes layout parasitics into account. The circuit and layout parameters are stored in a parameterized layout description format, GBLD. The layout parasitics are stored as closed form expressions. Layout optimization tools can modify the layout and recalculate parasitics on the fly. If the results of sensitivity analysis are passed to those tools, optimization for performance can be achieved with relatively few iterations involving time consuming circuit simulations. 2005-02-21T00:00:00Z Tseng, I-Lun og Postula, Adam http://espace.library.uq.edu.au/view/UQ:99238 In this paper, a novel approach is developed to evaluate the overall performance of a local area network as well as to monitor some possible intrusion detections. The data is obtained via system utility 'ping' and huge data is analyzed via statistical methods. Finally, an overall performance index is defined and simulation experiments in three months proved the effectiveness of the proposed performance index. A software package is developed based on these ideas. 2007-08-24T00:00:00Z Zhang, Y. og Liu, W. og Dong, Z. Y. http://espace.library.uq.edu.au/view/UQ:7708 One of Semantic Web strengths is the ability to address incomplete knowledge. However, at present, it cannot handle incomplete knowledge directly. Also, it cannot handle non-monotonic reasoning. In this paper, we extend ALE Defeasible Description Logic with existential quantifier, i.e., ALE Defeasible Description Logic. Also, we modify some parts of the logic, resulting in an increasing efficiency in its reasoning. 2006-12-04T00:00:00Z Pothipruk, P. og Governatori, G http://espace.library.uq.edu.au/view/UQ:10633 An algebraic curve is defined as the zero set of a multivariate polynomial. We consider the problem of fitting an algebraic curve to a set of vectors given an additional set of vectors labelled as interior or exterior to the curve. The problem of fitting a linear curve in this way is shown to lend itself to a support vector representation, allowing non-linear curves and high dimensional surfaces to be estimated using kernel functions. The approach is attractive due to the stability of solutions obtained, the range of functional forms made ossible (including polynomials), and the potential for applying well understood regularisation operators from the theory of Support Vector Machines. 2004-03-19T00:00:00Z Walder, Christian og Lovell, Brian C. og Kootsookos, Peter J. http://espace.library.uq.edu.au/view/UQ:7961 Back and von Wright have developed algebraic laws for reasoning about loops in the refinement calculus. We extend their work to reasoning about probabilistic loops in the probabilistic refinement calculus. We apply our algebraic reasoning to derive transformation rules for probabilistic action systems and probabilistic while-loops. In particular we focus on developing data refinement rules for these two constructs. Our extension is interesting since some well known transformation rules that are applicable to standard programs are not applicable to probabilistic ones: we identify some of these important differences and we develop alternative rules where possible. In particular, our probabilistic action system and while-loop data refinement rules are new: they differ from the non-probabilistic rules. 2006-09-05T00:00:00Z Meinicke, Larissa og Hayes, Ian J. http://espace.library.uq.edu.au/view/UQ:176450 Back and von Wright have developed algebraic laws for reasoning about loops in a total correctness framework using the refinement calculus. We extend their work to reasoning about probabilistic loops in the probabilistic refinement calculus. We apply our algebraic reasoning to derive transformation rules for probabilistic action systems and probabilistic while-loops. In particular we focus on developing data refinement rules for these two constructs. Our extension is interesting since some well known transformation rules that are applicable to standard programs are not applicable to probabilistic ones: we identify some of these important differences and we develop alternative rules where possible. 2009-04-16T18:30:13Z Meinicke, Larissa og Hayes, Ian J. http://espace.library.uq.edu.au/view/UQ:279377 Currently, the coordination of dispersed energy resources, like domestic micro-CHP systems, Photovoltaic systems or the charging of electric vehicles is widely discussed. A major issue that has to be addressed in this context is the possibility of an overload of the public power system. In order to guarantee overload prevention, a robust mechanism is needed for making the coordination system aware of the system's loadability limits and to provide them with information for corrective measures if necessary. In this paper the authors present a reference algorithm allowing for an on-line constraint violation detection and mitigation under hard real-time constraints by predetermining the overall set of allowable grid usage patterns a-priori. 2012-08-28T13:51:04Z Krause, Olav og Lehnhoff, Sebastian http://espace.library.uq.edu.au/view/UQ:259072 The emergence of monitoring applications has precipitated the need for Data Stream Management Systems (DSMSs), which constantly monitor incoming data feeds (through registered continuous queries), in order to detect events of interest. In this article, we examine the problem of how to schedule multiple Continuous Queries (CQs) in a DSMS to optimize different Quality of Service (QoS) metrics. We show that, unlike traditional online systems, scheduling policies in DSMSs that optimize for average response time will be different from policies that optimize for average slowdown, which is a more appropriate metric to use in the presence of a heterogeneous workload. Towards this, we propose policies to optimize for the average-case performance for both metrics. Additionally, we propose a hybrid scheduling policy that strikes a fine balance between performance and fairness, by looking at both the average- and worst-case performance, for both metrics. We also show how our policies can be adaptive enough to handle the inherent dynamic nature of monitoring applications. Furthermore, we discuss how our policies can be efficiently implemented and extended to exploit sharing in optimized multi-query plans and multi-stream CQs. Finally, we experimentally show using real data that our policies consistently outperform currently used ones. 2011-10-23T03:15:22Z Sharaf, Mohamed A. og Chrysanthis, Panos K. og Labrinidis, Alexandros og Pruhs, Kirk http://espace.library.uq.edu.au/view/UQ:136359 Infrastructure mesh networks offer a high-capacity wireless backhaul network through which clients, such as PDAs, can connect to one another or with external networks. To use the mesh network, a client must route its outbound traffic via one of the mesh routers in the infrastructure mesh. As the clients are mobile, they may move out of range of the mesh router they were using and need to associate with another. Client handoff mechanisms enable this change in mesh routers to occur in a manner that limits disruption to any transport or application layer sessions the client may be running. In this paper we present an extremely light-weight handoff approach for clients that relies on gratuitous ARP messages broadcast at regular intervals from mesh routers within the infrastructure mesh. An evaluation of our approach using a 5 node testbed has shown that client handoffs can be conducted quickly, and with minimal loss of packets for both TCP and UDP traffic. 2008-04-24T00:00:00Z Wishart, R. og Pirzada, A. A. og Portmann, M. http://espace.library.uq.edu.au/view/UQ:100747 Online multimedia data needs to be encrypted for access control. To be capable of working on mobile devices such as pocket PC and mobile phones, lightweight video encryption algorithms should be proposed. The two major problems in these algorithms are that they are either not fast enough or unable to work on highly compressed data stream. In this paper, we proposed a new lightweight encryption algorithm based on Huffman error diffusion. It is a selective algorithm working on compressed data. By carefully choosing the most significant parts (MSP), high performance is achieved with proper security. Experimental results has proved the algorithm to be fast. secure: and compression-compatible. 2007-08-23T00:00:00Z Liu, Zeng og Li, Xue og Dong, Zhaoyang http://espace.library.uq.edu.au/view/UQ:176590 2009-04-17T10:03:51Z Wishart, Ryan og Pirzada, Asad Amir og Portmann, Marius og Indulska, Jadwiga http://espace.library.uq.edu.au/view/UQ:139714 The beam shaping of a linearly polarized radial-line slot-array (LP RLSA) antenna is demonstrated with the production of a prototype with a broadened main beam pointed in an arbitrary direction. The method of synthesis is presented, which utilizes a simple but accurate radiation model for the RLSA antenna to predict radiation characteristics. Experimental results for a Ku-band LP RLSA antenna manufactured using the described techniques show good agreement with the theoretically predicted performance. (C) 2000 John Wiley & Sons, Inc. 2008-06-10T00:00:00Z Bialkowski, M. E. og Davis, P. W. http://espace.library.uq.edu.au/view/UQ:194348 2010-01-31T00:07:38Z McKilliam, R. G. og Clarkson, I. V. L. og Smith, W. D. og Quinn, B. G. http://espace.library.uq.edu.au/view/UQ:174999 The lattice An is an important lattice because of its covering properties in low dimensions. Two algorithms exist in the literature that compute the nearest point in the lattice An in O(n log n) arithmetic operations. In this paper we describe a new algorithm that requires only O(n) operations. The new algorithm makes use of an approximate sorting procedure called a bucket sort. This is the fastest known nearest point algorithm for this lattice. 2009-04-09T00:00:00Z McKilliam, R. og Clarkson, I.V.L. og Smtih, W. D. og Quinn, B. G. http://espace.library.uq.edu.au/view/UQ:96950 2007-08-24T00:00:00Z Willadsen, K. og Wiles, J. H. http://espace.library.uq.edu.au/view/UQ:139793 2008-06-10T00:00:00Z Wang, Y. og Wang, Z. og Bialkowski, M. E. http://espace.library.uq.edu.au/view/UQ:23748 We explore of the feasibility of the computationally oriented institutional agency framework proposed by Governatori and Rotolo testing it against an industrial strength scenario. In particular we show how to encode in defeasible logic the dispute resolution policy described in Article 67 of FIDIC. 2007-06-17T00:00:00Z Wang, Miao og Governatori, Guido http://espace.library.uq.edu.au/view/UQ:229635 2011-02-20T00:04:52Z Reddy, Vikas og Sanderson, Conrad og Lovell, Brian C. http://espace.library.uq.edu.au/view/UQ:70445 This paper presents a new low-complexity multicarrier modulation (MCM) technique based on lattices which achieves a peak-to-average power ratio (PAR) as low as three. The scheme can be viewed as a drop in replacement for the discrete multitone (DMT) modulation of an asymmetric digital subscriber line modem. We show that the lattice-MCM retains many of the attractive features of sinusoidal-MCM, and does so with lower implementation complexity, O(N), compared with DMT, which requires O(N log N) operations. We also present techniques for narrowband interference rejection and power profiling. Simulation studies confirm that performance of the lattice-MCM is superior, even compared with recent techniques for PAR reduction in DMT. 2007-08-15T00:00:00Z Collings, I. B. og Clarkson, I. V. L. http://espace.library.uq.edu.au/view/UQ:101682 We present the design rationale and basic workings of a low-cost, easy-to-use power system simulator developed to support investigations into human interface design for a hydropower plant. The power system simulator is based on three important components: models of power system components, a data repository, and human interface elements. Dynamic Data Exchange (DDE) allows simulator components to communicate with each other within the simulator. To construct the modules of the simulator we have combined the advantages of commercial software such as Matlab/Simulink, ActiveX Control, Visual Basic and Excel and integrated them in the simulator. An important advantage of our approach is that further components of the simulator now can be developed independently. An initial assessment of the simulator indicates it is fit for intended purpose. 2007-08-23T20:20:10Z Memisevic, R. og Sanderson, P. M. og Choudhury, S. og Wong, W. http://espace.library.uq.edu.au/view/UQ:295900 In this paper we present the design and implementation of a low power neural amplifier which has two programmable gains in two programmable bandwidths. The bandwidths are programmable between 0.7-300Hz, suitable for measuring local field potentials and 1.95-5.4kHz, suitable for measuring action potentials. The amplifier achieves a maximum gain of 79dB in the higher bandwidth. A chip has been designed and implemented using a 0.5μm technology with 8 neural amplifiers. On average the neural amplifier consumes less than 14μW at 3.3V. 2013-04-04T16:24:24Z Thanigaivelan, Balavelan og Wiles, Janet og Hamilton, Tara Julia http://espace.library.uq.edu.au/view/UQ:71292 The design of dual-band 2.45/5.2 GHz antenna for an acces point of a Wireless Local Area Network (LAN) is presented. The proposed antenna is formed by a Radial Line Slot Array (RLSA) operating at 2.4 GHz and a Microstrip patch working at 5.2 GHz, both featuring circular polarization. The design of this antenna system is accomplished using commercially available Finite Element software. High Frequency Structure Simulator (HFSS) of Ansoft and an in-house developed iteration procedure. The performance of the designed antenna is assessed in terms of return loss (RL), radiation pattern and polarization purity in the two frequency bands. 2007-08-15T00:00:00Z Bialkowski, K. og Zagriatski, S. og Postula, A. J. og Bialkowski, M. E. http://espace.library.uq.edu.au/view/UQ:279391 The paper develops two new approaches based on alternative analytical expressions to determine the optimum sizes and power factors of distributed generation (DG) units at various locations for minimizing power losses and a methodology to identify the best location. These approaches can be easily adapted to accommodate different types of renewable DG units (i.e., biomass, wind and photovoltaic) for minimizing energy losses by considering the time-varying demand with all possible operating conditions of DG units. The results obtained on a 69-bus distribution system demonstrate that the proposed methods based on one load level can be adequate to determine the location, size and power factor of DG unit for minimizing energy losses. 2012-08-29T09:03:41Z Hung, Duong Quoc og Mithulananthan, Nadarajah http://espace.library.uq.edu.au/view/UQ:111937 An alternative expression is derived for the evaluation of the electric field in the source region. This expression caters for a finite size, instead of an infinitesimally small, principal volume and does not contain the source dyadic term. This expression provides a fast and accurate evaluation of the electric field inside an arbitrary shape finite size principal volume. Numerical calculations on using the new expression are provided. 2007-09-19T00:00:00Z Hui, HT