School of Information Technology and Electrical Engineering Publications - UQ eSpace
http://espace.library.uq.edu.au/
The University of QueenslandenFez http://blogs.law.harvard.edu/tech/rssA general-purpose tunable landscape generator
http://espace.library.uq.edu.au/view/UQ:79344
The research literature on metalieuristic and evolutionary computation has proposed a large number of algorithms for the solution of challenging real-world optimization problems. It is often not possible to study theoretically the performance of these algorithms unless significant assumptions are made on either the algorithm itself or the problems to which it is applied, or both. As a consequence, metalieuristics are typically evaluated empirically using a set of test problems. Unfortunately, relatively little attention has been given to the development of methodologies and tools for the large-scale empirical evaluation and/or comparison of metaheuristics. In this paper, we propose a landscape (test-problem) generator that can be used to generate optimization problem instances for continuous, bound-constrained optimization problems. The landscape generator is parameterized by a small number of parameters, and the values of these parameters have a direct and intuitive interpretation in terms of the geometric features of the landscapes that they produce. An experimental space is defined over algorithms and problems, via a tuple of parameters for any specified algorithm and problem class (here determined by the landscape generator). An experiment is then clearly specified as a point in this space, in a way that is analogous to other areas of experimental algorithmics, and more generally in experimental design. Experimental results are presented, demonstrating the use of the landscape generator. In particular, we analyze some simple, continuous estimation of distribution algorithms, and gain new insights into the behavior of these algorithms using the landscape generator.2007-08-15T08:17:40Z
Gallagher, Marcus; Yuan, Bo A general technique for proving lock-freedom
http://espace.library.uq.edu.au/view/UQ:181762
Lock-freedom is a property of concurrent programs which states that, from any state of the program, eventually some process will complete its operation. Lock-freedom is a weaker property than the usual expectation that eventually all processes will complete their operations. By weakening their completion guarantees, lock-free programs increase the potential for parallelism, and hence make more efficient use of multiprocessor architectures than lock-based algorithms. However, lock-free algorithms, and reasoning about them, are considerably more complex. In this paper we present a technique for proving that a program is lock-free. The technique is designed to be as general as possible and is guided by heuristics that simplify the proofs. We demonstrate our theory by proving lock-freedom of two non-trivial examples from the literature. The proofs have been machine-checked by the PVS theorem prover, and we have developed proof strategies to minimise user interaction.2009-09-03T08:47:45Z
Colvin, Robert; Dongol, Brijesh A generative bias towards average complexity in artificial cell lineages
http://espace.library.uq.edu.au/view/UQ:129119
The evolution of life on earth has been characterized by generalized long-term increases in phenotypic complexity. Although natural selection is a plausible cause for these trends, one alternative hypothesis generative bias-has been proposed repeatedly based on theoretical considerations. Here, we introduce a computational model of a developmental system and use it to test the hypothesis that long-term increasing trends in phenotypic complexity are caused by a generative bias towards greater complexity. We use our model to generate random organisms with different levels of phenotypic complexity and analyse the distributions of mutational effects on complexity. We show that highly complex organisms are easy to generate but there are trade-offs between different measures of complexity. We also find that only the simplest possible phenotypes show a generative bias towards higher complexity, whereas phenotypes with high complexity display a generative bias towards lower complexity. These results suggest that generative biases alone are not sufficient to explain long-term evolutionary increases in phenotypic complexity. Rather, our finding of a generative bias towards average complexity argues for a critical role of selective biases in driving increases in phenotypic complexity and in maintaining high complexity once it has evolved.2008-02-18T17:29:05Z
Lohaus, R.; Geard, N.L.; Wiles, J.; Azevedo, R.B.R. A gene regulatory network for cell differentiation in caenorhabditis elegans
http://espace.library.uq.edu.au/view/UQ:98581
2007-08-24T02:02:24Z
Geard, N. L.; Wiles, J. H. A Generic Schema-Driven Metadata Editor for the eResearch Community
http://espace.library.uq.edu.au/view/UQ:162252
2009-01-30T10:06:30Z
Crawley, Stephen C.; Chernich, Ronald A.; Hunter, Jane A genetic algorithm based method for deregulated electricity market dispatch
http://espace.library.uq.edu.au/view/UQ:104240
In a deregulated electricity market, optimizing dispatch capacity and transmission capacity are among the core concerns of market operators. Many market operators have capitalized on linear programming (LP) based methods to perform market dispatch operation in order to explore the computational efficiency of LP. In this paper, the search capability of genetic algorithms (GAs) is utilized to solve the market dispatch problem. The GA model is able to solve pool based capacity dispatch, while optimizing the interconnector transmission capacity. Case studies and corresponding analyses are performed to demonstrate the efficiency of the GA model.2007-08-23T22:11:50Z
Wong, Kinn Onn; Dong, Zhao Yang; Saha, T. K. A genetic algorithm/method of moments approach to the optimization of an RF coil for MRI applications - Theoretical considerations - Abstract
http://espace.library.uq.edu.au/view/UQ:65560
A Combined Genetic Algorithm and Method of Moments design methods is presented for the design of unusual near-field antennas for use in Magnetic Resonance Imaging systems. The method is successfully applied to the design of an asymmetric coil structure for use at 190MHz and demonstrates excellent radiofrequency field homogeneity.2007-08-15T01:32:42Z
Yau, D.; Crozier, S. Agent-based distributed software verification
http://espace.library.uq.edu.au/view/UQ:102650
Despite decades of research, the takeup of formal methods for developing provably correct software in industry remains slow. One reason for this is the high cost of proof construction, an activity that, due to the complexity of the required proofs, is typically carried out using interactive theorem provers. In this paper we propose an agent-oriented architecture for interactive theorem proving with the aim of reducing the user interactions (and thus the cost) of constructing software verification proofs. We describe a prototype implementation of our architecture and discuss its application to a small, but non-trivial case study.2007-08-23T21:04:15Z
Hunter, Chris; Robinson, Peter J.; Strooper, Paul A. Agentenbasierte Verteilnetzautomatisierung
http://espace.library.uq.edu.au/view/UQ:299069
2013-05-01T16:05:28Z
Lehnhoff, Sebastian; Krause, Olav Agents adapt to majority behaviours
http://espace.library.uq.edu.au/view/UQ:138883
Agents within a group can have different perceptions of their working environment and autonomously fulfil their goals. However, they can be aware of beliefs and goals of the group as well as other members so that they can adjust their behaviours accordingly. To model these agents, we explicitly include knowledge commonly shared by the group and that obtained from other agents. By avoiding actions which violate ``mental attitudes'' shared by the majority of the group, agents demonstrate their social commitment to the group. Defeasible logic is chosen as our representation formalism for its computational efficiency, and for its ability to handle incomplete and conflicting information. Hence, our agents can enjoy the low computational cost while performing ``reasoning about others''. Finally, we present the implementation of our multi-agent system.2008-05-24T14:21:37Z
Pham, D.H.; Governatori, G; Raboczi, S Agents as multi-threaded logical objects
http://espace.library.uq.edu.au/view/UQ:62242
In this paper we describe a distributed object oriented logic programming language in which an object is a collection of threads deductively accessing and updating a shared logic program. The key features of the language, such as static and dynamic object methods and multiple inheritance, are illustrated through a series of small examples. We show how we can implement object servers, allowing remote spawning of objects, which we can use as staging posts for mobile agents. We give as an example an information gathering mobile agent that can be queried about the information it has so far gathered whilst it is gathering new information. Finally we define a class of co-operative reasoning agents that can do resource bounded inference for full first order predicate logic, handling multiple queries and information updates concurrently. We believe that the combination of the concurrent OO and the LP programming paradigms produces a powerful tool for quickly implementing rational multi-agent applications on the internet.2007-08-14T17:44:27Z
Clark, K.; Robinson, P. J. A Gentzen System for Reasoning with Contrary-To-Duty Obligations: A Preliminary Study
http://espace.library.uq.edu.au/view/UQ:9872
In this paper we present a Gentzen system for reasoning with contrary-to-duty obligations. The intuition behind the system is that a contrary-to-duty is a special kind of normative exception. The logical machinery to formalize this idea is taken from substructural logics and it is based on the definition of a new non-classical connective capturing the notion of reparational obligation. Then the system is tested against well-known contrary-to-duty paradoxes2005-02-21T00:00:00Z
Governatori, Guido; Rotolo, Antonino A geometrical method for calculating the unreachable workspace of the 3-DOF Gantry-Tau parallel manipulator
http://espace.library.uq.edu.au/view/UQ:188723
2009-12-01T14:24:27Z
Tyapin, Ilya; Hovland, Geir; Brogardh, Torgny Age-related factors that confound peripheral pulse timing characteristics in Caucasian children
http://espace.library.uq.edu.au/view/UQ:76007
Characteristics obtained from peripheral pulses can be used to assess the status of cardiovascular system of subjects. However, nonintrusive techniques are preferred when prolonged monitoring is required for their comfort. Pulse transit time ( PTT) measurement has showed its potentials to monitor timing changes in peripheral pulse in cardiovascular and respiratory studies. In children, the common peripheries used for these studies are fingers or toes. Presently, there is no known study conducted on children to investigate the possible physiologic parameters that can confound PTT measure at these sites. In this study, PTT values from both peripheral sites were recorded from 55 healthy Caucasian children ( 39 male) with mean age of 8.4 +/- 2.3 years ( range 5 - 12 years). Peripheries' path length, heart rate, systolic blood pressure, diastolic blood pressure ( DBP) and mean arterial pressure ( MAP) were measured to investigate their contributions to PTT measurement. The results reveal that PTT is significantly related to all parameters ( P< 0.05), except for DBP and MAP. Age is observed to be the dominant factor that affects PTT at both peripheries in a child. Regression equations for PTT were derived for measuring from a finger and toe, ( 6.09 age + 189.2) ms and ( 6.70 age + 243.0) ms, respectively.2007-08-15T06:11:43Z
Foo, J. Y. A.; Wilson, S. J.; Williams, G.; Harris, M. A.; Cooper, D. Agile artifacts - documenting, tracking and reporting: trust the source Luke!
http://espace.library.uq.edu.au/view/UQ:315561
2013-11-26T18:24:14Z
Thomas, Dave Aging Rate of Grade 3 Presspaper Insulation used in Power Transformers
http://espace.library.uq.edu.au/view/UQ:343423
2014-10-25T11:22:07Z
Lelekakis, Nick; Wijaya, Jaury; Martin, Daniel; Saha, Tapan; Susa, Dejan; Krause, Christoph A GIS model to predict urban population and housing in the southeast Queensland region with visualization
http://espace.library.uq.edu.au/view/UQ:98439
2007-08-24T01:56:50Z
Bell, M. J.; Stimson, R. J.; Shyy, T.; Belward, J. A.; Kastanis, L. E. A Global Sensitivity Tool for Cardiac Cell Modeling: Application to Ionic Current Balance and Hypertrophic Signaling
http://espace.library.uq.edu.au/view/UQ:312792
2013-10-22T15:26:22Z
Sher, Anna A.; Cooling, Michael T.; Bethwaite, Blair; Tan, Jefferson; Peachey, Tom; Enticott, Colin; Garic, Slavisa; Gavaghan, David J.; Noble, Denis; Abramson, David; Crampin, Edmund J. A global vision system for a robot soccer team
http://espace.library.uq.edu.au/view/UQ:100553
This paper describes the real time global vision system for the robot soccer team the RoboRoos. It has a highly optimised pipeline that includes thresholding, segmenting, colour normalising, object recognition and perspective and lens correction. It has a fast ‘paint’ colour calibration system that can calibrate in any face of the YUV or HSI cube. It also autonomously selects both an appropriate camera gain and colour gains robot regions across the field to achieve colour uniformity. Camera geometry calibration is performed automatically from selection of keypoints on the field. The system acheives a position accuracy of better than 15mm over a 4m × 5.5m field, and orientation accuracy to within 1°. It processes 614 × 480 pixels at 60Hz on a 2.0GHz Pentium 4 microprocessor.2007-08-23T19:34:10Z
Ball, D. M.; Wyeth, G. F.; Nuske, S. A gram-based string paradigm for efficient video subsequence search
http://espace.library.uq.edu.au/view/UQ:298597
The unprecedented increase in the generation and dissemination of video data has created an urgent demand for the large-scale video content management system to quickly retrieve videos of users' interests. Traditionally, video sequence data are managed by high-dimensional indexing structures, most of which suffer from the well-known “curse of dimensionality” and lack of support of subsequence retrieval. Inspired by the high efficiency of string indexing methods, in this paper, we present a string paradigm called VideoGram for large-scale video sequence indexing to achieve fast similarity search. In VideoGram, the feature space is modeled as a set of visual words. Each database video sequence is mapped into a string. A gram-based indexing structure is then built to tackle the effect of the “curse of dimensionality” and support video subsequence matching. Given a high-dimensional query video sequence, retrieval is performed by transforming the query into a string and then searching the matched strings from the index structure. By doing so, expensive high-dimensional similarity computations can be completely avoided. An efficient sequence search algorithm with upper bound pruning power is also presented. We conduct an extensive performance study on real-life video collections to validate the novelties of our proposal.2013-04-28T00:21:39Z
Huang, Zi; Liu, Jiajun; Cui, Bin; Du, Xiaoyong A graphical specification of model transformations with triple graph grammars
http://espace.library.uq.edu.au/view/UQ:102675
Models and model transformations are the core concepts of OMG's MDA (TM) approach. Within this approach, most models are derived from the MOF and have a graph-based nature. In contrast, most of the current model transformations are specified textually. To enable a graphical specification of model transformation rules, this paper proposes to use triple graph grammars as declarative specification formalism. These triple graph grammars can be specified within the FUJABA tool and we argue that these rules can be more easily specified and they become more understandable and maintainable. To show the practicability of our approach, we present how to generate Tefkat rules from triple graph grammar rules, which helps to integrate triple graph grammars with a state of a art model transformation tool and shows the expressiveness of the concept.2007-08-23T21:05:08Z
Grunske, L.; Geiger, L.; Lawley, M. Agreement contexts in formal concept analysis
http://espace.library.uq.edu.au/view/UQ:100459
2007-08-23T19:30:03Z
Cole, R. J.; Becker, P. A grid compatible methodology for reactive power compensation in renewable based distribution system
http://espace.library.uq.edu.au/view/UQ:255222
The penetration level of renewable based distributed generation (DG) has increased rapidly in recent years. Grid standards demand small DG units to operate with constant power factor control mode and large DG units with voltage control mode. As a result, small DG units are exposed to the problem of slow voltage recovery due to contingencies like fault. This paper proposes a new sensitivity index based methodology for placement of shunt reactive power compensators to support voltage at load bus and generator bus under steady state and transient conditions. Two different test systems with diverse network and load configurations have been used to test and verify the proposed methodology.2011-10-12T15:12:21Z
Aziz, T.; Mhaskar, U. P.; Saha, T. K.; Mithulananthan, N. A grid computing based approach for probablisitic load flow analysis
http://espace.library.uq.edu.au/view/UQ:104503
2007-08-23T22:25:29Z
Ali, M; Dong, Z Y; Li, X; Zhang, P. A Grid-Enabled Architecture for Geospatial Data Sharing
http://espace.library.uq.edu.au/view/UQ:172837
This paper explores combining OGC and grid technologies for geospatial data sharing. OGC and grid technologies have different focuses: OGC technologies focus more on interface specifications and encodings for the access to geospatial data sources, while grid technologies focus more on the collaboration and sharing of resources. By combining both, we hope to leverage each other's strengths. In the paper, we first introduce our grid-enabled architecture which is based on both OGC and grid technologies, then we discuss how grid-enabled OGC Web services can be integrated with non-grid-enabled ones, and finally, we report our initial implementation of a case study2009-03-31T12:15:23Z
Shu, Yanfeng; Zhang, Jack Fan; Zhou, Xiaofang A hamming distance based VLIW/EPIC code compression technique
http://espace.library.uq.edu.au/view/UQ:100617
2007-08-23T19:36:56Z
Ros, M. B.; Sutton, P. R. A handover protocol and network architecture for wireless extensions of ATM networks
http://espace.library.uq.edu.au/view/UQ:95726
2007-08-23T23:54:19Z
Indulska, J.; Zhu, W. A handover protocol for wireless ATM
http://espace.library.uq.edu.au/view/UQ:149962
2008-06-06T15:59:59Z
Indulska, J.; MacFarlane, S.; Zhu, W. A hardware scheduler based on task queues for FPGA-based embedded real-time systems
http://espace.library.uq.edu.au/view/UQ:357205
A hardware scheduler is developed to improve real-time performance of soft-core processor based computing systems. A hardware scheduler typically accelerates system performance at the cost of increased hardware resources, inflexibility and integration difficulty. However, the reprogrammability of FPGA-based systems removes the problems of inflexibility and integration difficulty. This paper introduces a new task-queue architecture to better support practical task controls and maintain good resource scaling. The scheduler can be configured to support various algorithms such as time sliced priority scheduling, Earliest Deadline First and Least Slack Time. The hardware scheduler reduces scheduling overhead by more than 1,000 clock cycles and raises the system utilization bound by a maximum 19.2 percent. Scheduling jitter is reduced from hundreds of clock cycles in software to just two or three cycles for most operations. The additional resource cost is no more than 17 percent of a typical softcore system for a small scale embedded application.2015-05-03T01:16:26Z
Tang, Yi; Bergmann, Neil W. A helicopter named Dolly: Behavioural cloning for autonomous helicopter control
http://espace.library.uq.edu.au/view/UQ:99325
This paper considers the pros and cons of using behavioural cloning for the development of low-level helicopter automation modules. Over the course of this project several Behavioural cloning approaches have been investigated. The results of the most effective Behavioural cloning approach are then compared to PID modules designed for the same aircraft. The comparison takes into consideration development time, reliability, and control performance. It has been found that Behavioural cloning techniques employing local approximators and a wide state-space coverage during training can produce stabilising control modules in less time than tuning PID controllers. However, performance and reliabity deficits have been found to exist with the Behavioural Cloning, attributable largely to the time variant nature of the dynamics due to the operating environment, and the pilot actions being poor for teaching. The final conclusion drawn here is that tuning PID modules remains superior to behavioural cloning for low-level helicopter automation.2007-08-24T10:18:13Z
Buskey, G. D.; Roberts, J.; Wyeth, G. F. A heuristic data reduction approach for associative classification rule hiding
http://espace.library.uq.edu.au/view/UQ:176499
When data are to be shared between business partners, there could be some sensitive patterns which should not be disclosed to the other parties. On the other hand, the “quality” of the data must also be preserved. This creates an interesting question: how can we maintain the shared data that are guaranteed to have the quality, and the certain types of sensitive patterns be removed or “hidden”? In this paper, we address such the problem of sensitive classification rule hiding by using data reduction approach, i.e. removing the whole selected tuples in the given dataset. We focus on a specific type of classification rules, i.e. associative classification rules. In our context, a sensitive rule is hidden when its support falls below a minimal support threshold. Meanwhile, the impact on the data quality of the dataset is represented in term of a number of false-dropped rules, and a number of ghost rules. We present a few observations on the data quality with regard to the data reduction processes. From the observations, we can represent the impact by each reduction precisely without any re-applying the classification algorithm. Subsequently, we propose a heuristic algorithm to hide the sensitive rules based on the observations. Experimental results are presented to show the effectiveness and the efficiency of the proposed algorithm.2009-04-16T22:58:14Z
Natwichai, J.; Sun, X.; Xue, Li A hierarchical conflict resolution method for multi-agent path planning
http://espace.library.uq.edu.au/view/UQ:199118
2010-03-14T00:07:33Z
Chen, Kuang-Yuan; Lindsay, Peter A.; Robinson, Peter J.; Abbass, Hussein A. A high definition, finite difference time domain method
http://espace.library.uq.edu.au/view/UQ:64800
A high definition, finite difference time domain (HD-FDTD) method is presented in this paper. This new method allows the FDTD method to be efficiently applied over a very large frequency range including low frequencies, which are problematic for conventional FDTD methods. In the method, no alterations to the properties of either the source or the transmission media are required. The method is essentially frequency independent and has been verified against analytical solutions within the frequency range 50 Hz-1 GHz. As an example of the lower frequency range, the method has been applied to the problem of induced eddy currents in the human body resulting from the pulsed magnetic field gradients of an MRI system. The new method only requires approximately 0.3% of the source period to obtain an accurate solution. (C) 2003 Elsevier Science Inc. All rights reserved.2007-08-14T19:24:28Z
Zhao, Huawei W.; Crozier, Stuart; Liu, Feng A High-Level Programming Language for Modelling the Earth
http://espace.library.uq.edu.au/view/UQ:8866
Computational models based on the solution of partial differential equations (PDEs) play a key role in Earth systems simulations. The software implementing these models depends on the discretisation method, data structures and the computer architecture. For this reason, it is difficult for scientists to implement new models without strong software engineering skills. In this paper, we present a computational modeling language (escript) based on the object-oriented scripting language (Python). This language, is designed to implement PDE-based models with a high degree of abstraction from the underlying discretization techniques and their implementation. The main components of escript are the Data class objects which handle data with a spatial distribution and the linearPDE class which define linear PDEs to be solved in each step of a time integration or non-linear iteration scheme. As an example we will discuss the solution of the Lame equation and the implementation of a quasi-static model for crustal fault systems.2005-12-09T00:00:00Z
Gross, Lutz; Smillie, Jonathan; Davies, Matt A High Performance FDTD Scheme for MRI Applications
http://espace.library.uq.edu.au/view/UQ:104375
2007-08-23T22:20:05Z
Wang, Hua; Trakic, Adnan; Liu, Feng; Bialkowski, Marek E.; Crozier, Stuart A high resolution smart camera with GigE Vision extension for surveillance applications
http://espace.library.uq.edu.au/view/UQ:177223
2009-04-22T17:54:58Z
Norouznezhad, E.; Bigdeli, A.; Postula, A.; Lovell, B. C. A homogeneous superconducting magnet design using a hybrid optimization algorithm
http://espace.library.uq.edu.au/view/UQ:319630
This paper employs a hybrid optimization algorithm with a combination of linear programming (LP) and nonlinear programming (NLP) to design the highly homogeneous superconducting magnets for magnetic resonance imaging (MRI). The whole work is divided into two stages. The first LP stage provides a global optimal current map with several non-zero current clusters, and the mathematical model for the LP was updated by taking into account the maximum axial and radial magnetic field strength limitations. In the second NLP stage, the non-zero current clusters were discretized into practical solenoids. The superconducting conductor consumption was set as the objective function both in the LP and NLP stages to minimize the construction cost. In addition, the peak-peak homogeneity over the volume of imaging (VOI), the scope of 5 Gauss fringe field, and maximum magnetic field strength within superconducting coils were set as constraints. The detailed design process for a dedicated 3.0 T animal MRI scanner was presented. The homogeneous magnet produces a magnetic field quality of 6.0 ppm peak-peak homogeneity over a 16 cm by 18 cm elliptical VOI, and the 5 Gauss fringe field was limited within a 1.5 m by 2.0 m elliptical region.2013-12-17T00:27:27Z
Ni, Zhipeng; Wang, Qiuliang; Liu, Feng; Yan, Luguang A Hopfield neural network based task mapping method
http://espace.library.uq.edu.au/view/UQ:144116
With a prior knowledge of a program, static mapping aims to identify an optimal clustering strategy that can produce the best performance. In this paper we present a static method that uses Hopfield neural network to cluster the tasks of a parallel program for a given system. This method takes into account both load balancing and communication minimization. The method has been tested on a distributed shared memory system against other three clustering methods. Four programs, SOR, N-body, Gaussian Elimination and VQ, are used in the test. The result shows that our method is superior to the other three. (C) 1999 Elsevier Science B.V. All rights reserved.2008-06-10T14:53:10Z
Zhu, W.; Liang, T. Y.; Shieh, C. K. A hybrid approach to parameter tuning in genetic algorithms
http://espace.library.uq.edu.au/view/UQ:102995
2007-08-23T21:17:28Z
Yuan, B.; Gallagher, M. R. A hybrid approach towards information expansion based on shallow and deep metadata
http://espace.library.uq.edu.au/view/UQ:231410
2011-03-07T11:45:17Z
Groza, T; Handschuh, S A hybrid clustering approach to genome-scale recognition of protein families
http://espace.library.uq.edu.au/view/UQ:197347
2010-03-02T11:44:04Z
Harlow, T.J.; Gogarten, J. P.; Ragan, M. .A. A hybrid clustering approach to recognition of protein families in 114 microbial genomes
http://espace.library.uq.edu.au/view/UQ:111604
2007-09-19T19:00:25Z
Harlow, Timothy J.; Gogarten, J. Peter; Ragan, Mark A. A hybrid evaluation method for the full-wave analysis of microstrip structures
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.2007-09-19T17:33:48Z
Hui, H. T.; Yung, E. K. N.; Sheng, X. Q.; Chan, C. H. A hybrid field-harmonics approach for passive shimming design in MRI
http://espace.library.uq.edu.au/view/UQ:263846
2011-12-20T13:03:51Z
Liu, Feng; Zhu, Jianfeng; Xia, Ling; Crozier, Stuart A Hybrid Inductive and Active Filtering Method for Damping Harmonic Resonance in Distribution Network with Nonlinear Loads
http://espace.library.uq.edu.au/view/UQ:364791
2015-07-16T14:53:07Z
Li, Yong; Liu, Fang; Saha, Tapan K.; Krause, Olav; Cao, Yijia A hybrid, inverse approach to the design of magnetic resonance imaging magnets
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].2007-08-13T11:39:57Z
Zhao, Huawei; Crozier, Stuart; Doddrell, David M. A hybrid mock circulation loop for a total artificial heart
http://espace.library.uq.edu.au/view/UQ:340900
Rotary blood pumps are emerging as a viable technology for total artificial hearts, and the development of physiological control algorithms is accelerated with new evaluation environments. In this article, we present a novel hybrid mock circulation loop (HMCL) designed specifically for evaluation of rotary total artificial hearts (rTAH). The rTAH is operated in the physical domain while all vasculature elements are embedded in the numerical domain, thus combining the strengths of both approaches: fast and easy exchange of the vasculature model together with improved controllability of the pump. Parameters, such as vascular resistance, compliance, and blood volume, can be varied dynamically in silico during operation. A hydraulic–numeric interface creates a real-time feedback loop between the physical and numerical domains. The HMCL uses computer-controlled resistance valves as actuators, thereby reducing the size and number of hydraulic elements. Experimental results demonstrate a stable interaction over a wide operational range and a high degree of flexibility. Therefore, we demonstrate that the newly created design environment can play an integral part in the hydraulic design, control development, and durability testing of rTAHs.2014-10-01T15:10:34Z
Nestler, Frank; Bradley, Andrew P.; Wilson, Stephen J.; Timms, Daniel L.; Frazier, Howard; Cohn, William E. A hybrid model of maximum margin clustering method and support vector regression for noninvasive electrocardiographic imaging
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; Liu, Feng; Wang, Yaming; Shou, Guofa; Huang, Wenqing; Zhang, Huaxiong A hybrid planning method for transmission networks in a deregulated environment
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.2007-07-05T14:00:38Z
Xu, Zhao; Dong, Zhao Yang; Wong, Kit Po A hybrid prediction model for moving objects
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; Liu, Qing; Shen, Heng Tao; Zhou, Xiaofang