School of Information Technology and Electrical Engineering Publications - UQ eSpace

A cognitive genetic algorithm for power distribution system planning

Duan, Gang og Yu, Yixin og Dong, Zhao Yang — 2007-08-15T00:00:00Z

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.

A Collaborative Digestion and Design Game for Community and Technology Exploration

2007-08-23T00:00:00Z

A collaborative scholarly annotation system for dynamic web documents - A literary case study

2010-07-18T00:09:55Z

This paper describes ongoing work within the Aus-e-Lit project at the University of Queensland to provide collaborative annotation tools for Australian Literary Scholars. It describes our implementation of an annotation framework to facilitate collaboration and sharing of annotations within research sub-communities. Using the annotation system, scholars can collaboratively select web resources and attach different types of annotations (comments, notes, queries, tags and metadata), which can be harvested to enrich the AustLit collection. We describe how rich semantic descriptions can be added to the constantly changing AustLit collection through a set of interoperable annotation tools based on the Open Annotations Collaboration (OAC) model. RDFa enables scholars to semantically annotate dynamic web pages and contribute typed metadata about the IFLA FRBR entities represented within the AustLit collection. We also describe how the OAC model can be used in combination with OAI-ORE to produce scholarly digital editions, and compare this approach with existing scholarly annotation approaches. © 2010 Springer-Verlag.

A combined approach for information flow analysis in fault tolerant hardware

McComb, T. og Wildman, L. — 2008-05-07T00:00:00Z

Fault tolerance in information security devices is difficult to establish due to the large number of possible interactions in the device (e. g. embedded code, boolean logic, electromagnetic interference, etc.) In previous work we examined information flow as a graph problem by composing orthogonal views of the device under analysis. In other work we used fault-tree analysis to reason about information flow as a systemic failure arising from certain configurations (or faults) in either the control logic or data flow 'backbone'. In this paper we combine these approaches by taking advantage of an alternative representation of fault trees as reliability block diagrams.

A combined approach to checking web ontologies

2009-01-27T00:00:00Z

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

A combined voxel and surface based method for topology correction of brain surfaces

2011-08-22T00:00:00Z

Brain surfaces provide a reliable representation for cortical mapping. The construction of correct surfaces from magnetic resonance images (MRI) segmentation is a challenging task, especially when genus zero surfaces are required for further processing such as parameterization, partial inflation and registration. The generation of such surfaces has been approached either by correcting a binary image as part of the segmentation pipeline or by modifying the mesh representing the surface. During this task, the preservation of the structure may be compromised because of the convoluted nature of the brain and noisy/imperfect segmentations. In this paper, we propose a combined, voxel and surfacebased, topology correction method which preserves the structure of the brain while yielding genus zero surfaces. The topology of the binary segmentation is first corrected using a set of topology preserving operators applied sequentially. This results in a white matter/gray matter binary set with correct sulci delineation, homotopic to a filled sphere. Using the corrected segmentation, a marching cubes mesh is then generated and the tunnels and handles resulting from the meshing are finally removed with an algorithm based on the detection of nonseparating loops. The approach was validated using 20 young individuals MRI from the OASIS database, acquired at two different time-points. Reproducibility and robustness were evaluated using global and local criteria such as surface area, curvature and point to point distance. Results demonstrated the method capability to produce genus zero meshes while preserving geometry, two fundamental properties for reliable and accurate cortical mapping and further clinical studies.

A compact and broadband NRI-TL metamaterial monopole antenna

Antoniades, Marco A. og Eleftheriades, George V. — 2011-12-02T00:00:00Z

A compact and broadband negative-refractive-index transmission-line (NRI-TL) metamaterial antenna is proposed, which consists of a conventional printed monopole loaded in a left-handed fashion. The metamaterial loading allows the antenna to be modeled as a short folded monopole around 5.5 GHz, and simultaneously acts as a a balun for the ground plane around 3.55 GHz, therefore enabling the ground plane to radiate at this frequency. Consequently, the metamaterial-loaded monopole antenna exhibits a very wide impedance bandwidth by virtue of the orthogonality between these two radiating modes. The NRITL metamaterial monopole antenna has a simulated -10 dB return-loss bandwidth of 3.84 GHz while maintaining a very high efficiency in the order of 90%, and achieves orthogonal pattern diversity in both the 3.3 - 3.8 GHz WiMax and 5.15 - 5.85 GHz WiFi bands.

A compact and directive UWB antenna for biomedical applications

Abbosh, A. og Bialkowski, M.E. — 2008-04-30T00:00:00Z

A compact and low-profile metamaterial ring antenna with vertical polarization

2011-12-02T00:00:00Z

A Compact Argumentation System for Agent System Specification

Song, I. og Governatori, G. — 2006-06-30T00:00:00Z

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.

A compact crossover using NRI-TL metamaterial lines

2012-11-14T18:42:23Z

A compact NRI-TL metamaterial branch-line crossover is presented that has an area of λ/36 × λ/12, and is a factor of 81 times smaller than its analogous transmission-line counterpart. Circuit simulations reveal that it exhibits a 34% −10 dB |S11| bandwidth, good isolation below −10 dB over a 22% bandwidth, and less than 0.5 dB insertion loss over a 15% bandwidth. Furthermore, the bandwidth of the device can be increased by incorporating additional branch-line sections into the structure.

A compact hepta-band antenna for portable and embedded devices

Boldaji, Ashkan og Bialkowski, Marek E. — 2012-05-14T21:23:10Z

The article presents the design of a compact hepta-band antenna for portable and embedded applications targeting the GSM-900/DCS/PCS/UMTS-2100 cellular and 2.4/5.2/5.5-GHz WLAN bands. A printed inverted-F antenna with a folded primary arm and a second radiating arm on the bottom surface of the substrate initially provides tri-band operation in the 900, 1700, and 2450-MHz bands. The shorting-arm is relocated below the primary arm for a reduction in occupied area. The addition of a long slot in the ground plane offers an additional operation around 2100 MHz, bridging the 1700- and 2450-MHz resonances and promoting significantly wide-band performance of more than 900 MHz in that band. A second ground slot allows the antenna to support two of the 5-GHz WLAN bands. Laboratory measurements confirm the performance of the final hepta-band antenna, with 6-dB return loss met from 880–1000, 1680–2590, and 5150–5710 MHz, and better than 10-dB return loss at the centers and edges of these bands.

A compact low-profile high-impedance surface for use as an antenna ground plane

2011-12-02T00:00:00Z

A compact and low-profile high-impedance surface is proposed which offers a significantly smaller footprint without affecting the usable reflection phase bandwidth of the structure. The unit cell of the proposed surface is similar to the traditional `mushroom' structure, but utilizes inter-digitated-capacitor and spiral-inductor lumped elements to reduce its size without sacrificing the in-phase reflection bandwidth. It is determined that the reflection-phase resonance and bandwidth is largely independent of the shunt inductive loading and depends primarily on the value of the series capacitive loading. Finally, an application of the structure as a high-impedance ground plane for a printed loop antenna is proposed.

A compact monopole antenna with a defected ground plane for multi-band applications

Antoniades, Marco A. og Eleftheriades, George V. — 2011-12-02T00:00:00Z

The primary interest of this work is to create a multi-band antenna that can be used for various wireless LAN standards (e.g. WiFi, WiMax), while occupying a small area. It will be shown that this can be achieved by etching an L-shaped slot in the ground plane of a UWB grounded monopole antenna. The resulting "defected ground plane" creates an additional two resonances in the input impedance of the antenna, whose locations can be adjusted according to the size and location of the slot. The design is completely uniplanar, it is very low profile, and it does not require the use of any vias or lumped-element components. It is therefore easy to fabricate using standard photolithographic procedures at a very reasonable cost, thus making it ideal for use in wireless LAN devices.

A compact multiband monopole antenna with a defected ground plane

Antoniades, M. A. og Eleftheriades, G. V. — 2011-12-02T00:00:00Z

A compact superconducting magnet for magnetic resonance microscopy

Crozier, S og Doddrell, DM — 2007-08-13T00:00:00Z

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.

A compact switched-beam array antenna for mobile satellite communications

Karmakar, N. C. og Bialkowski, M. E. — 2008-06-10T00:00:00Z

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.

A Compact Tri-Band Monopole Antenna With Single-Cell Metamaterial Loading

2011-12-02T00:00:00Z

A compact UWB three-way power divider

Abbosh, A.M. — 2008-02-18T00:00:00Z

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.

A comparative study of modulation scheme for three-phase voltage inverter

2010-09-21T00:00:00Z

A comparative study of modulation scheme for three-phase voltage source inverter

2011-03-08T00:00:00Z

A comparison of DCT and DWT block based watermarking on medical image quality

2011-09-10T00:00:00Z

Hiding watermark information in medical image data files is one method of enhancing security and protecting patient privacy. However the research area of medical image watermarking has not been particularly active, partly due to concerns that any distortion could affect the diagnostic value of the medical image. These concerns can be addressed by ensuring that any image changes are kept below visual perception thresholds. In this paper the effects of image watermarking and common image manipulations are measured using the Peak Signal-to-Noise Ratio (PSNR), Structural Similarity Measure (SSIM) and Steerable Visual Difference Predictor (SVDP) numerical metrics. Two methods of block based watermarking are compared: the Discrete Cosine Transform (DCT) and Discrete Wavelet Transform (DWT). To ensure a fair comparison a 128-pixel block size is used which allows an identical amount of information to be embedded for each method (3072 bits multiplied by embedding strength). The results suggest that although the two methods are similar, the DCT method is preferable if localization of changes is required. If localization is not required the DWT method is supported.

A comparison of different choices for the regularization parameter in inverse electrocardiography models

2007-08-23T00:00:00Z

Calculating the potentials on the heart’s epicardial surface from the body surface potentials constitutes one form of inverse problems in electrocardiography (ECG). Since these problems are ill-posed, one approach is to use zero-order Tikhonov regularization, where the squared norms of both the residual and the solution are minimized, with a relative weight determined by the regularization parameter. In this paper, we used three different methods to choose the regularization parameter in the inverse solutions of ECG. The three methods include the L-curve, the generalized cross validation (GCV) and the discrepancy principle (DP). Among them, the GCV method has received less attention in solutions to ECG inverse problems than the other methods. Since the DP approach needs knowledge of norm of noises, we used a model function to estimate the noise. The performance of various methods was compared using a concentric sphere model and a real geometry heart-torso model with a distribution of current dipoles placed inside the heart model as the source. Gaussian measurement noises were added to the body surface potentials. The results show that the three methods all produce good inverse solutions with little noise; but, as the noise increases, the DP approach produces better results than the L-curve and GCV methods, particularly in the real geometry model. Both the GCV and L-curve methods perform well in low to medium noise situations.

A comparison of multiple instance and group based learning

Brossi, Steven D. og Bradley, Andrew P. — 2013-04-03T14:23:52Z

In this paper we compare the performance of a number of multiple-instance learning (MIL) and group based (GB) classification algorithms on both a synthetic and real-world Pap smear dataset. We utilise the synthetic dataset to demonstrate that performance improves as both bag size and percent positives increase and that MIL outperforms GB algorithms when the percentage positives is less than 50%. However, as the positive bags become increasingly homogeneous, as is apparent on the real-world dataset, the two approaches become comparable. This result highlights that the performance of a MIL or GB algorithm will be maximised when the algorithm's MIL assumption matches the reality of the dataset. Therefore, on the Pap smear dataset, algorithms with a more generalised MIL assumption demonstrate the strongest performance.

A comparison of neural landscapes: NK, NKp and NKq

2007-08-24T00:00:00Z

A comparison of neural network and fast fourier transforn-based approach for the state analysis of brain

2007-08-23T00:00:00Z

A comparison of sceptical NAF-free logic programming approaches

2005-04-07T00:00:00Z

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.

A comparison of schemas for video metadata representation

Hunter, Jane og Armstrong, Liz — 2006-10-05T00:00:00Z

A comparison of sequence kernels for localization prediction of transmembrane proteins

2008-04-24T00:00:00Z

We applied support vector machines to the prediction of the subcellular localization of transmembrane proteins, and compared the performance of different sequence kernels on this task. More specifically we measured prediction accuracy, computation time, number of kernel evaluations and number of support vectors for the spectrum, the full spectrum, the wildcard, the mismatch, the local-alignment and the residue-coupling kernel. The local-alignment achieved the highest prediction accuracy, with a Matthews correlation coefficient of 0.51, closely followed by the mismatch kernel. However, the local-alignment kernel was also the most time consuming kernel and seven times slower than the mismatch kernel. The spectrum kernel was the fastest kernel but linked to the highest number of support vectors and kernel evaluations. The residue-coupling kernel showed the lowest number of support vectors and kernel evaluations. No correlation between the number of support vectors and prediction accuracy could be observed. A localization predictor (TMPLoc) has been made available at http://pprowler.itee.uq.edu.au/TMPLoc

A Comparison of Small Signal Modulation Parameter Extraction Techniques for Vertical-Cavity, Surface-Emitting Lasers

2006-02-21T00:00:00Z

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.

A Comparison of Some Fuzzy Relation-based Linguistic Preference Models for Multiple-Factor Project Assessment

Smith, Phillip — 2006-11-22T00:00:00Z

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.

A comparison of ultracapacitor, BESS and shunt capacitor on oscillation damping of power system with large-scale PV plants

Shah, Rakibuzzaman og Mithulananthan, N. — 2011-10-14T00:00:00Z

Intermittent and slow generator like PV is augmented with auxiliary device to meet the certain grid code requirements for interconnection. Ultracapacitor, battery energy storage system (BESS) or shunt capacitor at the PV terminal have recently been used as auxiliary devices for large-scale PV generator system to improve the system performance during transients. Although the studies on individual auxiliary devices are well documented, a comparative study of these devices impact on the damping of electromechanical (EM) mode and oscillatory instability problem has not been reported so far. This paper presents the damping performance of large-scale PV with auxiliary devices. The simulation studies have been done on multi-machine infinite bus (MMIB) system and two-area test system. For simulation studies different types of synchronous generators (e.g. hydro, thermal) are also taken into consideration.

A comparison study of different RF shields for an 8-element transceive small animal array at 9.4T

2011-12-20T00:00:00Z

In this study, three types of radio-frequency shields are studied and compared in the context of ultra-high field small-animal magnetic resonance imaging. It has been demonstrated that the coil penetration depth and mutual coupling between the coils depend heavily on the type of shield employed. The results were used to guide the design of a 9.4T 8-element transceive small animal array, which provides high overall coil penetration.

A comparison study of regularization techniques on the theoretical design of phased array RF coils in MRI

2009-04-15T00:00:00Z

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.

A complex systems approach to service discovery

Robinson, R. R. og Indulska, J. — 2007-08-23T00:00:00Z

A compliance management ontology: Developing shared understanding through models

2012-05-21T10:28:02Z

Managing regulatory compliance is increasingly challenging and costly for organizations world-wide. Due to the diversity of stakeholders in compliance management initiatives, any effort towards providing compliance management solutions demands a common understanding of compliance management concepts and practice. This paper reports on research undertaken to develop an ontology to create a shared conceptualization of the compliance management domain, namely CoMOn (Compliance Management Ontology). The ontology concepts are extracted from interviews and surveys of compliance management experts and practitioners, and refined through synthesis with leading academic literature related to compliance management. A semiotic framework was utilized to conduct a rigorous evaluation of CoMOn through a series of eight case studies spanning a number of industry sectors. The consensus achieved through the evaluation has positioned CoMOn as a comprehensive domain ontology for Compliance Management.

A compound object authoring and publishing tool for literary scholars based on the IFLA-FRBR

Gerber, A. og Hunter, J. — 2009-11-25T00:00:00Z

A compound object authoring and publishing tool for literary scholars based on the IFLA-FRBR Model

Gerber, Anna og Hunter, Jane — 2010-03-01T00:00:00Z

This paper presents LORE (Literature Object Re-use and Exchange), a light-weight tool which is designed to allow literature scholars and teachers to author, edit and publish compound information objects encapsulating related digital resources and bibliographic records. LORE enables users to easily create OAI-ORE-compliant compound objects, which build on the IFLA FRBR model, and also enables them to describe and publish them to an RDF repository as Named Graphs. Using the tool, literary scholars can create typed relationships between individual atomic objects using terms from a bibliographic ontology and can attach metadata to the compound object. This paper describes the implementation and user interface of the LORE tool, as developed within the context of an ongoing case study being conducted in collaboration with AustLit: The Australian Literature Resource, which focuses on compound objects for teaching and research within the Australian literature studies community.

A comprehensive comparison of FACTS devices for enhancing static voltage stability

2009-12-01T00:00:00Z

This paper presents a comparison of FACTS devices for static voltage stability study. Various performance measures including PV curves, voltage profiles, and power losses are compared under normal and contingency conditions. Placement and sizing techniques of series FACTS devices and UPFC are proposed for loading margin enhancement. The paper provides a guide for utilities to have an appropriate choice of FACTS device for enhancing loading margin and static voltage stability.

A comprehensive tool for congestion-based nodal price modelling

Nappu, M. B. og Saha, T. K. — 2010-04-20T00:00:00Z

A computational framework for institutional agency

Governatori, G og Rotolo, A — 2006-12-15T00:00:00Z

This paper provides a computational framework, based on Defeasible Logic, to capture some aspects of institutional agency. Our background is Kanger-Lindahl-P\"orn account of organised interaction, which describes this interaction within a multi-modal logical setting. This work focuses in particular on the notions of counts-as link and on those of attempt and of personal and direct action to realise states of affairs. We show how standard Defeasible Logic can be extended to represent these concepts: the resulting system preserves some basic properties commonly attributed to them. In addition, the framework enjoys nice computational properties, as it turns out that the extension of any theory can be computed in time linear to the size of the theory itself.

A Computationally Grounded Logic of Knowledge, Belief and Certainty

2005-05-23T00:00:00Z

This paper presents a logic of knowledge, belief and certainty, which allows us to explicitly express the knowledge, belief and certainty of an agent. A computationally grounded model, called interpreted KBC systems, is given for interpreting this logic. The relationships between knowledge, belief and certainty are explored. In particular, certainty entails belief; and to the agent what it is certain of appears to be the knowledge. To formalize those agents that are able to introspect their own belief and certainty, we identify a subclass of interpreted KBC systems, called introspective KBC systems. We provide sound and complete axiomatizations for the logics. We show that the validity problem for the interpreted KBC systems is PSPACE-complete, and the same problem for introspective KBC systems is co-NP complete, thus no harder than that of the propositional logic.

A computational system to optimise noise rejection in photoplethysmography signals during motion or poor perfusion states

Foo, J. Y. A. og Wilson, S. J. — 2007-09-19T00:00:00Z

Photoplethysmography (PPG) signals can be used in clinical assessment such as heart rate (HR) estimations and extraction of arterial flow waveforms. Motion artefact and/or poor peripheral perfusion can contaminate the PPG during monitoring. A computational system is presented here to minimise these two intrinsic weaknesses of the PPG signals. Specifically, accelerometers are used to detect the presence of motion artefacts and an adaptive filter is employed to minimise induced errors. Zero-phase digital filtering is engaged to reduce inaccuracy on the PPG signals when measured from a poorly perfused periphery. In this system, a decision matrix adopts the appropriate technique to improve the PPG signal-to-noise ratio dynamically. Statistical analyses show promising results (maximum error < 7.63%) when computed HR is compared to corresponding estimates from the electrocardiogram. Hence, the results here suggest that this dual-mode approach has potential for use in relevant clinical measurements.

A computer simulation study of imaging flexural inhomogeneities using plate-wave diffraction tomography

2009-04-08T00:00:00Z

This paper investigates the feasibility of plate-wave diffraction tomography for the reconstruction of flexural inhomogeneities in plates using the results of computer simulation studies. The numerical implementation of the fundamental reconstruction algorithm, which has recently been developed by Wang and Rose [C.H. Wang, L.R.F. Rose, Plate-wave diffraction tomography for structural health monitoring, Rev. Quant. Nondestr. Eval. 22 (2003) 1615–1622] is investigated addressing the essential effects of applying the discrete form of the Fourier diffraction theorem for solving the inverse problem as discussed by Kak and Slaney [A.C. Kak, M. Slaney, Principles of Computerized Tomographic Imaging, IEEE Press, New York, 1988] for the acoustic case, viz. diffraction limited sensitivity, influence of weak scatterer assumption, damage location and scatter field data processing in time and Fourier space as well as experimental limitations such as finite receiver length and limited views. The feasibility of the imaging technique is investigated for cylindrical inhomogeneities of various severities and relative position within the interrogation space and a normal incident interrogation configuration. The results show that plate-wave diffraction tomography enables the quantitative reconstruction of location, size and severity of plate damage with excellent sensitivity and offers the potential for detecting corrosion thinning, disbonds and delamination damage in structural integrity management applications.

A concept for hip prosthesis identification using ultra wideband radar

2007-08-23T00:00:00Z

Ultra wideband (UWB) radar has been extensively investigated both theoretically and practically for the identification buried artifacts. Ground probe radar (GPR) concentrates on the identification of lightly buried land mines, unexploded ordnance (UXO) and archeological targets. The same technology is proposed in a similar context for the rapid identification of in vivo implanted metallic prostheses. The technique is based on resonance based target identification and the paper investigates UWB scattering from a metallic hip prosthesis in free space as a first step in the identification process.

A concepts-first approach to object-oriented modelling

Sien, V.Y og Carrington, D. — 2008-04-22T00:00:00Z

A concurrency test tool for java monitors

Long, B. og Hoffman, D. og Strooper, P. A. — 2007-08-24T00:00:00Z

A constraint specification approach to building flexible workflows

Mangan, PJ og Sadiq, S — 2007-10-17T00:00:00Z

Process support systems, such as workflows, are being used in a variety of domains. However, most areas of application have focused on traditional production-style processes, which are characterised by predictability and repetitiveness. Application in non-traditional domains with highly flexible process is still largely unexplored. Such flexible processes are characterised by lack of ability to completely predefine and/or an explosive number of alternatives. Accordingly we define flexibility as the ability of the process to execute on the basis of a partially defined model where the full specification is made at runtime and may be unique to each instance. In this paper, we will present an approach to building workflow models for such processes. We will present our approach in the context of a non-traditional domain for workflow, deployment, which is, degree programs in tertiary institutes. The primary motivation behind our approach is to provide the ability to model flexible processes without introducing non-standard modelling constructs. This ensures that the correctness and verification of the language is preserved. We propose to build workflow schemas from a standard set of modelling constructs and given process constraints. We identify the fundamental requirements for constraint specification and classify them into selection, termination and build constraints. We will detail the specification of these constraints in a relational model. Finally, we will demonstrate the dynamic building of instance specific workflow models on the basis of these constraints.

A Contested Role for Perspective in Three-Dimensional Information Visualisation

Wyeld, T. G. — 2007-08-23T00:00:00Z

A context-based approach for detecting suspicious behaviours

2010-11-15T00:00:00Z