Physical Sciences and Mathematics Commons^™

Orthogonal Designs From Negacyclic Matrices, K. Finlayson, Jennifer Seberry

Faculty of Informatics - Papers (Archive)

We study the use of negacyclic matrices to form orthogonal designs and hence Hadamard matrices. We give results for all possible tuple for order 12, all but 3 for order 20 and all but 3 for order 28.

Comparison Of The Performance Of A Time-Dependent Short-Interest Rate Model With Time-Dependent Models (2004) + Clarification (2008), J. M. Goard, N. Hansen

Faculty of Informatics - Papers (Archive)

The coefficients in the stochastic differential equation that the short interest rate follows are of vital importance in the subsequent modelling of bond prices and other interest rate products. Empirical tests have previously been performed by various authors who compare a variety of popular short-rate models. Most recently, Ahn and Gao compared their model with affine-drift models and showed that their model with a non-linear drift function outperforms the others. This paper compares the model developed by Goard, which is a time-dependent generalization of the Ahn–Gao model, with the Ahn–Gao model itself. It is found that the time-dependent model using …

Reliable Optimised Flooding In Ad Hoc Networks, Justin Lipman, P. Boustead, Joe F. Chicharo

Faculty of Informatics - Papers (Archive)

Information dissemination (flooding) forms an integral part of routing protocols, network management, service discovery and information collection (sensing). Given the broadcast nature of ad hoc network communications, information dissemination provides a challenging problem. Blind flooding in ad hoc networks results in the broadcast storm problem. To limit the broadcast storm problem, mechanisms for optimised flooding have been proposed. However, this optimisation reduces the inherent level of redundancy. the minimum spanning tree (MST) algorithm using local one hop topology in a distributed manner as the basis of a more reliable optimised flooding mechanism called, reliable minimum spanning tree (RMST) flood is …

Asterism Decoding For Layered Space-Time Systems, P. Conder, Tadeusz A. Wysocki

Faculty of Informatics - Papers (Archive)

The area of layered space-time (LST) systems has received enormous attention recently as they can provide a roughly linear increase in data rate by using multiple transmit and receive antennas. The optimal detection strategy for a LST receiver is to perform a maximum-likelihood (ML) search over all possible transmitted symbol combinations. The decoding scheme proposed in this paper, called Asterism decoding, looks for a more efficient way of finding the ML solution by first considering the case of multiple transmit antennas and a single receive antenna. The decoder is then extended to achieve ML like performance for any number of …

Blind Source Separation Of Nonstationary Convolutively Mixed Signals In The Subband Domain, I. Russell, Jiangtao Xi, Alfred Mertins, Joe F. Chicharo

Faculty of Informatics - Papers (Archive)

The paper proposes a new technique for blind source separation (BSS) in the subband domain using an extended lapped transform (ELT) decomposition for nonstationary, convolutively mixed signals. As identified by S. Araki et al. (see Proc. 4th Int. Symp. on Independent Component Analysis and Blind Signal Separation - ICA2003, p.499-504, 2003), the motivation for subband-based BSS is the drawback of frequency domain BSS when dealing with separating mixed speech signals over a few seconds resulting in few samples in individual frequency bins leading to poor separation performance. In the proposed approach, mixed signals are decomposed into subband components by an …

Complex Orthogonal Sequences From Amicable Hadamard Matrices, Le Chung Tran, Jennifer Seberry, Beata J. Wysocki, Tadeusz A. Wysocki, Tianbing Xia, Y. Zhao

Faculty of Informatics - Papers (Archive)

The paper deals with the novel technique of designing complex spreading sequences with only four phases (0.257/spl pi/, 0.75/spl pi/, 1.25/spl pi/, 1.75/spl pi/). The interesting feature of those new sequences is the fact that not only the complex sequences are orthogonal but the real parts and imaginary parts are independently orthogonal. This can be utilized for spreading of complex constellation signals where the independent spreading using bipolar sequences (real part for in-phase component and imaginary part for quadrature component) can be applied. The paper introduces the theoretical background, and some example constructions of the amicable Hadamard matrices and the …

A Routing Strategy For Heterogeneous Mobile Ad Hoc Networks, Mehran Abolhasan, Justin Lipman, Joe F. Chicharo

Faculty of Informatics - Papers (Archive)

This paper presents a new routing strategy for heterogeneous mobile ad hoc networks. We refer to this strategy as on-demand utility-based routing protocol (OUBRP). This protocol introduces a utility-based route discovery strategy, which aims to minimise the number of control packets disseminated into the network during route discovery by efficiently using available resources at each node. Furthermore, we propose a new strategy to eliminate uni-directional links during the route discovery phase. We refer to this strategy as uni-directional link elimination (ULE). We performed a simulation study to compare the performance of OUBRP with a number of different routing protocols proposed …

Edge Image Description Using Angular Radial Partitioning, A. Chalechale, Alfred Mertins, G. Naghdy

Faculty of Informatics - Papers (Archive)

The authors present a novel approach for image representation based on geometric distribution of edge pixels. Object segmentation is not needed, therefore the input image may consist of several complex objects. For an efficient description of an arbitrary edge image, the edge map is divided into M/spl times/N angular radial partitions and local features are extracted for these partitions. The entire image is then described as a set of spatially distributed invariant feature descriptors using the magnitude of the Fourier transform. The approach is scale- and rotation-invariant and tolerates small translations and erosions. The extracted features are characterised by their …

Asterism Decoding For Layered Space-Time Systems Using 8psk, P. Conder, Tadeusz A. Wysocki

Faculty of Informatics - Papers (Archive)

The area of layered space-time (LST) systems has received enormous attention recently as they can provide a roughly linear increase in data rate by using multiple transmit and receive antennas. The optimal detection strategy for a LST receiver is to perform a maximum-likelihood (ML) search over all possible transmitted symbol combinations has an exponential complexity when the constellation size of number of transmit antennas increases. While sub-optimal decoders, such as VBLAST, provide linear decoding only where the number of receive antennas is at least equal to the number of transmit antennas. The decoding scheme proposed in this paper, called Asterism …

Modelling The Draganflyer Four-Rotor Helicopter, Phillip J. Mckerrow

Faculty of Informatics - Papers (Archive)

The Draganflyer is a radio-controlled helicopter. It is powered by 4 rotors and is capable of motion in air in 6 degrees of freedom and of stable hovering. For flying it requires a high degree of skill, with the operator continually making small adjustments. In this paper, we do a theoretical analysis of the dynamics of the Draganflyer in order to develop a model of it from which we can develop a computer control system for stable hovering and indoor flight.

Arabic/Persian Cursive Signature Recognition And Verification Using Line Segment Distribution, A. Chalechale, G. Naghdy, Prashan Premaratne

Faculty of Informatics - Papers (Archive)

This work proposes a fast method for line segment extraction based on chain code differentiation. It is applied to cursive signature recognition of Arabic/Persian. The evaluation method is introduced to obtain a quantitative value for the recognition rate. The comparative results show the existing differences among the methods in recognition, building time and searching time criteria. The two methods used for comparison are invariant moments and CBLSE method.

Image Analysis Using Line Segments Extraction By Chain Code Differentiation, A. Chalechale, G. Naghdy, Prashan Premaratne

Faculty of Informatics - Papers (Archive)

This paper proposes a new fast method for line segment extraction from edge maps. It has a parallel nature and can be used on parallel machines easily. The method uses the chain codes in the edge map, namely macrochains, for line segment detection. In the first phase, it breaks the macrochains into several microchains by employing the extreme points of the first derivative of shifted-smoothed chain code function. Straight-line segments approximate the resulting microchains. In the second phase, the line segments are grouped together based on their proximity (collinearity and nearness) to make longer segments. The final set could be …

Telecommunications Network Management Laboratory, I. Raad, Peter James Vial

Faculty of Informatics - Papers (Archive)

This work discusses network management laboratory design and implementation at the University of Wollongong in the School of Electrical, Computer and Telecommunications Engineering in years of 2002 and 2003 for a final year specialisation subject called telecommunication network management for telecommunications engineering students. The design and implementation included that of a network management GUI incorporating the fundamental aspects and functionality of the simple network management protocol (SNMP). The operational code of the SNMP is based on freely available software (joesnmp). This paper outlines how joesnmp was used to develop a suitable network management GUI, which is used to develop laboratory …

Determinants Of The Adoption Of Customer-Oriented Mobile Commerce Initiatives, Léger Pierre-Majorique, Luc Cassivi, S. F. Wamba

Faculty of Informatics - Papers (Archive)

This paper investigates organizations implementing mobile commerce initiatives. Mobile commerce (m-commerce) is defined as the wireless B2B and B2C exchange of operational and financial data within a supply chain. Based on a survey conducted with 159 Canadian and Scandinavian executive managers, this paper tests several theoretical determinants of customer-oriented m-commerce initiatives. Results indicate that i) the adoption of electronic commerce is a strong determinant for the adoption of m-commerce initiatives, ii) software firms are more inclined to adopt m-commerce initiatives, iii) firm size does not influence the adoption of mobile commerce, and iv) contrary to expectations, firms focusing on B2C …

Generalized Orthogonal Designs, S. Georgiou, C. Koukouvinos, Jennifer Seberry

Faculty of Informatics - Papers (Archive)

Orthogonal designs and their special cases such as weighing matrices and Hadamard matrices have many applications in combinatorics, statistics, and coding theory as well as in signal processing. In this paper we generalize the definition of orthogonal designs, we give many constructions for these designs and we prove some multiplication theorems that, most of them, can also be applied in the special case of orthogonal designs. Some necessary conditions for the existence of generalized orthogonal designs are also given.

On Some Antenna Selection Techniques For Wireless Channels Utilizing Differential Space-Time Modulation, Le Chung Tran, Tadeusz A. Wysocki

Faculty of Informatics - Papers (Archive)

The paper deals with antenna selection techniques for wireless channels utilizing differential space-time modulation. We propose here the restricted N-out-of-M antenna selection technique providing relatively good bit error performance, while using only one feedback bit for transmit diversity purpose. In addition, we also present an improved N-out-of-(N+1) antenna selection technique, which shortens the time required for processing feedback information. These techniques remarkably improve performance of wireless channels using differential detection.

Sharp Results Concerning The Expression Of Functions As Sums Of Finite Differences, R. Nillsen, S. Okada

Faculty of Informatics - Papers (Archive)

A square integrable function on the real line can be written as a finite sum of differences of order s if and only if the Fourier transform of the function vanishes at the origin at a rate comparable with |x|^{-s}. This enables us to see that the space of all such functions becomes a Hilbert space D^s(R) and that this space is the range of the derivative of order s on the Sobolev space of order s. It was proved by the author (Journal of Functional Analysis 110 (1992), 73-95) that each function in D^s(R) is a sum of 2s+1 …

Iterated Belief Change, Aditya K. Ghose, P. O. Hadjinian, A. Sattar, J. You, R. Goebel

Faculty of Informatics - Papers (Archive)

Most existing formalizations treat belief change as a single step process, and ignore several problems that become important when a theory, or belief state, is revised over several steps. This paper identifies these problems, and argues for the need to retain all of the multiple possible outcomes of a belief change step, and for a framework in which the effects of a belief change step persist as long as is consistently possible. To demonstrate that such a formalization is indeed possible, we develop a framework which uses the language of PJ-default logic to represent a belief state, and which enables …

Flexible Spatial Models For Kriging And Cokriging Using Moving Averages And The Fast Fourier Transform (Fft), Jay M. Ver Hoef, Noel A. Cressie, Ronald P. Barry

Faculty of Informatics - Papers (Archive)

Models for spatial autocorrelation and cross-correlation depend on the distance and direction separating two locations, and are constrained so that for all possible sets of locations, the covariance matrices implied from the models remain nonnegative-definite. Based on spatial correlation, optimal linear predictors can be constructed that yield complete maps of spatial fields from incomplete and noisy spatial data. This methodology is called kriging if the data are of only one variable type, and it is called cokriging if it is of two or more variable types. Historically, to satisfy the nonnegative-definite condition, cokriging has used coregionalization models for cross-variograms, even …

Designing Applications For Mobile Phones: The Mobile Subject Assistant, Sam Jebeile

Faculty of Informatics - Papers (Archive)

The rapid adoption rate of mobile phones coupled with advancements in supporting technologies suggests mobile phones may now be a viable tool for classroom use. In this paper we introduce the Mobile Subject Assistant, a proposed mobile phone based course tool. The tool is intended to assist in the delivery of university level subjects with an emphasis on student participation, collaboration and group or project work. We discuss a number of issues related to the design of interfaces for mobile phone applications and briefly describe the design of the interface to the Mobile Subject Assistant.

Mirroring Does Not Equal Transparency: The Importance Of Culturally Aware Student Interfaces, Penelope Mcfarlane, A. Fuller

Faculty of Informatics - Papers (Archive)

The University of Wollongong, along with most other Australian universities, now has considerable investment in delivering courses to Asian markets. While there is some concern regarding the relevance of a Western-based subject delivery to an Asian culture, most transnational teachers do localize course materials to varying degrees. However, the web-based interfaces to the subject materials are rarely, if ever, similarly adapted to better suit the culture of the intended target audience.

In this paper we argue that failure to take into consideration student perceptions of the interface provided to the materials may adversely affect the usability of such systems. Any …

A Longitudinal Study Of The Use Of The Web By Regional Tourism Organisations In The Asia Pacific Region, Lois Burgess, Joan Cooper, Carole Alcock, Preeti Uppala

Faculty of Informatics - Papers (Archive)

The information-intensive nature of the tourism and travel industry suggests an important role for Web technology in the promotion and marketing of tourist destinations. With reports of travel purchases and reservations being one of the fastest growing segments of the Internet community (eMarketer, 2002), it is no surprise that the number of tourism operators on the Web has increased considerably over the past few years. This paper presents the results of a longitudinal study of the use of Web technologies by Regional Tourism Organisations (RTOs) in the Asia-Pacific tourism industry. The Websites of 195 RTOs in the Asia-Pacific Region were …

A Research Framework For The Adoption And Usage Of Executive Information Systems By Organisational Executives: An Exploratory Study, Emmanuel Matthew Ikart, George Ditsa

Faculty of Informatics - Papers (Archive)

To improve the performance of executives’ work, a number of organisations have implemented executive information systems (EIS). Although the use of EIS is important in executives’ work, majority of executives are unwilling to use EIS applications. By using social factors, habits and facilitation conditions variables from Triandis’ framework, this paper extends TAM to derive variables to address the problem of the low usage of EIS by executives. This paper reports on research in progress in Australia on the adoption and usage of EIS by executives. The preliminary results suggest that executives’ experience in EIS positively relates to their experience in …

Issues Affecting Power Engineering Undergraduate Education In Australia, D A. Robinson, Victor J. Gosbell

Faculty of Informatics - Papers (Archive)

Recent changes to the electric power industry through deregulation and restructuring have had a considerable effect on power engineering education internationally. A number of Australian universities have also noticed a decline in the number of students interested in power engineering subjects, leading to the fewer graduates with power engineering knowledge. With a reduction in graduates and a perception of an aging workforce a shortage of suitably qualified power engineers for industry may be imminent. This paper provides discussion on the current status of university power engineering education within Australia and includes results from a recent Australia-wide survey of the university …

Power Quality Data Analysis Using Unsupervised Data Mining, Ali Asheibi, David A. Stirling, Sarath Perera, D A. Robinson

Faculty of Informatics - Papers (Archive)

The rapid increase in the size of databases required to store power quality monitoring data has demanded new techniques for analysing and understanding the data. One suggested technique to assist in analysis is data mining. Data mining is a process that uses a variety of data analysis tools to identify hidden patterns and relationships within large samples of data. This paper presents several data mining tools and techniques that are applicable to power quality data analysis to enable efficient reporting of disturbance indices and identify network problems through pattern recognition. This paper also presents results of data mining techniques applied …

Flicker Transfer In Radial Power Systems, Sankika Tennakoon, Lakshal Perera, D A. Robinson, Sarath Perera

Faculty of Informatics - Papers (Archive)

Loads which exhibit continuous and rapid variations in their current can cause voltage fluctuations that are often referred to as flicker. One good example for such loads is arc furnaces which are usually fed by dedicated feeders from the high voltage busbars in transmission systems. The flicker generated from such loads will propagate to the upstream HV point of common coupling (PCC), and from there to the downstream through the transmission and sub transmission systems. This paper demonstrates how the generated flicker is propagated from the HV PCC to the downstream in radial networks exhibiting different levels of attenuation depending …

Assessing The Future Of Electrical Power Engineering: A Report On Electrical Power Engineering Manpower Requirements In Australia, Victor J. Gosbell, D A. Robinson

Faculty of Informatics - Papers (Archive)

In 2001 the Electric Energy Society of Australia (EESA) developed concerns based on anecdotal evidence that there was a looming shortage of electrical power engineers in Australia. Information from the electrical power industry and academic communities was obtained through two separate survey questionnaires, a discussion workshop, and a number of submissions. This information was collated and compiled into 'Assessing the Future of Electrical Power Engineering: a Report on Electrical Power Engineering Manpower Requirements in Australia'.

Dynamic Multimedia Adaptation And Updating Of Media Streams With Mpeg-21, L. Rong, I. Burnett

Faculty of Informatics - Papers (Archive)

The paper discusses media streaming using dynamic resource adaptation and update as a means of facilitating universal multimedia access (UMA): the concept of accessing multimedia content through a variety of possible schemes (Bormans, J. et al., IEEE Sig. Process. Magazine, 2003). As background, the paper summarizes the most common content negotiation approaches and addresses their facets and problems. MPEG-21, the multimedia framework and its relationship to UMA are then explained. Our primary focus is an end-to-end approach to content adaptation which takes advantage of MPEG-21 to facilitate the UMA concept in a media streaming environment. The concept is validated using …

Hierarchic Decomposition In Agent Oriented Conceptual Modelling, R. B. Brown, Aditya K. Ghose

Faculty of Informatics - Papers (Archive)

Software development processes requires a thorough understanding of stakeholder objectives and requirements. Product-centrism is an insufficient stance from which to achieve greater efficiencies and reduce reengineering. Stakeholder requirement elicitation is thus worthy of formalization. A suite of tools, notably the i* model, provides a framework for early-phase requirements capture. These tools currently are at best only semiautomated and essentially consist of a notational glossary and sets of mark-up symbols. Increasing formalization may lead to greater automation of the process in the future, but currently there is a degree of flexibility that presents pitfalls for the unwary practitioner. A notion of …

Co-Evolution Of Complementary Formal And Informal Requirements, Aneesh Krishna, Aditya K. Ghose, S. A. Vilkomir

Faculty of Informatics - Papers (Archive)

Agent-oriented Conceptual Modelling (AoCM, as exemplified by the i* notation by E. Yu (1995)), represents an interesting approach to modelling early phase requirements that is particularly effective in capturing organizational contexts, stake-holder intentions and rationale. There are significant benefits in using formal methods for the development of computer systems and improving their quality. We propose a methodology which permits the use of these two otherwise disparate approaches in a complementary and synergistic fashion for requirements engineering.