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Articles 31 - 60 of 131
Full-Text Articles in Physical Sciences and Mathematics
Space Time Spreading With Modified Walsh-Hadamard Sequences, Peter James Vial, Beata J. Wysocki, I. Raad, Tadeusz A. Wysocki
Space Time Spreading With Modified Walsh-Hadamard Sequences, Peter James Vial, Beata J. Wysocki, I. Raad, Tadeusz A. Wysocki
Faculty of Informatics - Papers (Archive)
Previous work has shown that the performance of a space time spreading (STS) system using Walsh codes with two transmit antennas at the base station (BS) is degraded in the presence of mutual interference from adjacent sectors in the same cell. We use modified Walsh-Hadamard sequences exhibiting improved cross-correlation performance, which potentially mitigates the effects of MAI (multiple access interference). The presented study also looks at variation of sets of different modified Walsh-Hadamard codes being used by the adjacent interferer, with a hundred randomly selected pairings being chosen, as well as the case where one set of alternate codes is …
Distributed, Collaborative Learning Environments Using Ad Hoc Networks, A. Fuller, Penelope Mcfarlane, D. F. Saffioti
Distributed, Collaborative Learning Environments Using Ad Hoc Networks, A. Fuller, Penelope Mcfarlane, D. F. Saffioti
Faculty of Informatics - Papers (Archive)
Computer assisted distributed or collaborative learning environments have been in existence for some time, however one impediment to more widespread use has been the need for a permanent wired network infrastructure. In this paper we discuss the development of a prototype tool that allows the formation of an ad hoc network at any time, and in any locale.
Living With Inconsistencies In A Multidatabase System, J. R. Getta
Living With Inconsistencies In A Multidatabase System, J. R. Getta
Faculty of Informatics - Papers (Archive)
Integration of autonomous sources of information is one of the most important problems in implementation of the global information systems. This paper considers multidatabase systems as one of the typical architectures of global information services and addresses a problem of storing and processing inconsistent information in such systems. A new data model proposed in the paper separates sure from inconsistent information and introduces a system of elementary operations on the containers with sure and inconsistent information. A review of the implementation aspects in an environment of a typical relational database management system concludes the paper.
A Supervised Self-Organizing Map For Structures, Markus Hagenbuchner, Ah Chung Tsoi
A Supervised Self-Organizing Map For Structures, Markus Hagenbuchner, Ah Chung Tsoi
Faculty of Informatics - Papers (Archive)
This work proposes an improvement of a supervised learning technique for self organizing maps. The ideas presented in This work differ from Kohonen's approach to supervision in that a.) a rejection term is used, and b.) rejection affects the training only locally. This approach produces superior results because it does not affect network weights globally, and hence, prevents the addition of noise to the learning process of remote neurons. We implemented the ideas into self-organizing maps for structured data (SOM-SD) which is a more general form of self-organizing maps capable of processing graphs. The capabilities of the proposed ideas are …
Integration Of Dft And Cosine-Modulated Filter Banks With Blind Separation Of Convolutively Mixed Non-Stationary Sources, I. Russell, Jiangtao Xi, Alfred Mertins, Joe F. Chicharo
Integration Of Dft And Cosine-Modulated Filter Banks With Blind Separation Of Convolutively Mixed Non-Stationary Sources, I. Russell, Jiangtao Xi, Alfred Mertins, Joe F. Chicharo
Faculty of Informatics - Papers (Archive)
In this paper, oversampled M channel FIR filter banks using both DFT modulation and cosine modulation designs are used in conjunction with a time domain blind source separation (BSS) algorithm I. Russell et al., (2003). This BSS algorithm has been shown to blindly separate the fullband versions of non-stationary convolutively mixed sources in the time domain. However further savings on convergence and computational complexity can be made by using subband decomposition on the mixed signals before implementation of the time domain BSS algorithm in each subband. An extended lapped transform (ELT) prototype is modulated using a cosine-modulated (CM) FIR filter …
A Vision System For Providing 3d Perception Of The Environment Via: Transcutaneous Electro-Neural Stimulation, S. Meers, Koren Ward
A Vision System For Providing 3d Perception Of The Environment Via: Transcutaneous Electro-Neural Stimulation, S. Meers, Koren Ward
Faculty of Informatics - Papers (Archive)
The development of effective user interfaces, appropriate sensors, and information processing techniques for enabling the blind to achieve additional perception of the environment is a relentless challenge confronting HCI and sensor researchers. To address this challenge we have developed a novel 3D vision system that can enable the 3D structure of the immediate environment to be perceived via head mounted stereo video cameras and electro-tactile data gloves without requiring any use of the eyes. The electro-neural vision system (ENVS) works by extracting a depth map from the camera images by measuring the disparity between the stereo images. This range data …
The Effect Of Imperfect Carrier Recovery On The Performance Of The Diversity Antenna Selection Technique In Wireless Channels Utilizing Dstm, Le Chung Tran, Tadeusz A. Wysocki, Alfred Mertins
The Effect Of Imperfect Carrier Recovery On The Performance Of The Diversity Antenna Selection Technique In Wireless Channels Utilizing Dstm, Le Chung Tran, Tadeusz A. Wysocki, Alfred Mertins
Faculty of Informatics - Papers (Archive)
This paper examines the effect of imperfect carrier phase/frequency recovery at the receiver on the bit error performance of our diversity antenna selection technique (AST) proposed for channels utilizing differential space-time modulation (DSTM). The tolerance of differential detection associated with the proposed AST to phase/frequency errors is then analyzed.
Australian Backyard Gardens And The Journey Of Migration, Lesley M. Head, Pat Muir, E. Hampel
Australian Backyard Gardens And The Journey Of Migration, Lesley M. Head, Pat Muir, E. Hampel
Faculty of Science - Papers (Archive)
Gardens have been an important site of environmental engagement in Australia since the British colonization. They are places where immigrant people and plants carry on traditions from their homelands, and work out an accommodation with new social and biophysical environments. We examine the backyard gardens of three contemporary migrant groups in suburban Australia, Macedonian, Vietnamese and British-born, and a fourth group of first generation Australians with both parents born overseas. There is strong emphasis on the production of vegetables in Macedonian backyards, and herbs and fruit in Vietnamese backyards. British backyards were more diverse, some focusing on non-native ornamental flowers …
Multi-Modulation Schemes To Increase The Rate Space-Time Block Codes In Rayleigh Fading Channels, Le Chung Tran, Tadeusz A. Wysocki, Alfred Mertins
Multi-Modulation Schemes To Increase The Rate Space-Time Block Codes In Rayleigh Fading Channels, Le Chung Tran, Tadeusz A. Wysocki, Alfred Mertins
Faculty of Informatics - Papers (Archive)
The paper examines multimodulation schemes (MMSs) to increase the rate of our two new complex orthogonal designs (CODs) proposed for eight transmit antennas, namely C/sub 1/ and C/sub 2/, corresponding to the Amicable Orthogonal Designs (AODs) (8;1,1,2,2;1,1,2,2) and (8;1,1,1,4;1,1,1,4), respectively. In addition, the optimal intersymbol power allocation in the proposed codes in single modulation as well as in MMSs in flat Rayleigh fading channels is considered. It turns out that, in some modulation schemes, equal power transmission per each symbol time slot is not only optimal from the technical point of view, but also optimal in terms of achieving the …
Chain-Based Extraction Of Line Segments To Describe Images, A. Chalechale, G. Naghdy, Prashan Premaratne, H. Moghaddasi
Chain-Based Extraction Of Line Segments To Describe Images, A. Chalechale, G. Naghdy, Prashan Premaratne, H. Moghaddasi
Faculty of Informatics - Papers (Archive)
This work presents a novel fast method for line segment extraction, based on a chain code representation of edge maps. It has a parallel nature and can be employed on parallel machines. In the first phase it breaks the macro chains into several micro chains after applying shifting, smoothing and differentiating. The micro chains are then approximated by straight line segments. In the second phase, based on the length and the error criteria, the line segments are grouped into much longer lines. The experimental results show a significant improvement in the number of line segments extracted while their accumulative length …
An Mpeg Tolerant Authentication System For Video Data, Takeyuki Uehara, R. Safavi-Naini, P. Ogunbona
An Mpeg Tolerant Authentication System For Video Data, Takeyuki Uehara, R. Safavi-Naini, P. Ogunbona
Faculty of Informatics - Papers (Archive)
We propose a secure video authentication algorithm that is tolerant to visual degradation due to MPEG lossy compression to a designed level. The authentication process generates a tag that is sent with video data and the level of protection can be adjusted so that longer tags are used for higher security, and that the protection is distributed such that higher security is provided for regions of interest in the image. The computation required for authentication and verification can be largely performed as part of MPEG compression and so generation and verification of the tag can be integrated into the compression …
Document Image Analysis And Verification Using Cursive Signature, A. Chalechale, G. Naghdy, Prashan Premaratne, Alfred Mertins
Document Image Analysis And Verification Using Cursive Signature, A. Chalechale, G. Naghdy, Prashan Premaratne, Alfred Mertins
Faculty of Informatics - Papers (Archive)
A new approach for document image analysis and verification is presented. The approach utilizes connected component analysis and geometric properties of labelled regions for region of interest extraction. Document images containing Persian/Arabic text combined with English text, headlines, ruling lines, trade mark and cursive signature are used as a test data. Persian/Arabic signature extraction is investigated as a case study. The proposed method uses special characteristics of such signatures for extraction and verification procedures. A set of efficient, invariant and compact features is extracted utilizing spatial partitioning of the signature region. Comparative results exhibit high extraction and verification rates.
Two Complex Orthogonal Space-Time Codes For Eight Transmit Antennas, Le Chung Tran, Jennifer Seberry, Yejing Wang, Beata J. Wysocki, T. A. Wysocki, Tianbing Xia, Ying Zhao
Two Complex Orthogonal Space-Time Codes For Eight Transmit Antennas, Le Chung Tran, Jennifer Seberry, Yejing Wang, Beata J. Wysocki, T. A. Wysocki, Tianbing Xia, Ying Zhao
Faculty of Informatics - Papers (Archive)
Two new constructions of complex orthogonal space-time block codes of order 8 based on the theory of amicable orthogonal designs are presented and their performance compared with that of the standard code of order 8. These new codes are suitable for multi-modulation schemes where the performance can be sacrificed for a higher throughput.
Orthogonal Designs Of Kharaghani Type: Ii, C. Koukouvinos, Jennifer Seberry
Orthogonal Designs Of Kharaghani Type: Ii, C. Koukouvinos, Jennifer Seberry
Faculty of Informatics - Papers (Archive)
H. Kharaghani, in "Arrays for orthogonal designs", J. Combin. Designs, 8 (2000), 166-173, showed how to use amicable sets of matrices to construct orthogonal designs in orders divisible by eight. We show how amicable orthogonal designs can be used to make amicable sets and so obtain infinite families of orthogonal designs in six variables in orders divisible by eight.
The Importance Of Conducting Geodemographic Market Analysis On Coastal Areas: A Pilot Study Using Kiama Council, Katina Michael
The Importance Of Conducting Geodemographic Market Analysis On Coastal Areas: A Pilot Study Using Kiama Council, Katina Michael
Faculty of Informatics - Papers (Archive)
In February of 2003 Kiama Council launched a preliminary survey to gather community attitudes on the future growth of Werri Beach and Gerringong, NSW (Nelson). The survey focused primarily on what actions Council should take to manage population growth within existing neighbourhoods. This paper aims to support the preliminary survey by proposing that a geodemographic market analysis be conducted to complement the findings of the study published in May 2003 (Wiggins). The use of a Geographic Information System (GIS) can add great value to the strategic decisionmaking process and it is the recommendation of this paper that GIS should become …
Further Results On Strongbox Secured Secret Sharing Schemes, G. Gamble, B. M. Maenhaut, Jennifer Seberry, A. Penfold Street
Further Results On Strongbox Secured Secret Sharing Schemes, G. Gamble, B. M. Maenhaut, Jennifer Seberry, A. Penfold Street
Faculty of Informatics - Papers (Archive)
We extend our earlier work on ways in which defining sets of combinatorial designs can be used to create secret sharing schemes. We give an algorithm for classifying defining sets of designs according to their security properties and summarise the results of this algorithm for many small designs. Finally, we discuss briefly how defining sets can be applied to variations of the basic secret sharing scheme.
Homogeneous Bent Functions Of Degree N In 2n Variables Do Not Exist For N > 3 , Tianbing Xia, Jennifer Seberry, J. Pieprzyk, C. Charnes
Homogeneous Bent Functions Of Degree N In 2n Variables Do Not Exist For N > 3 , Tianbing Xia, Jennifer Seberry, J. Pieprzyk, C. Charnes
Faculty of Informatics - Papers (Archive)
We prove that homogeneous bent functions f : GF(2)2n —> GF(2) of degree n do not exist for n > 3. Consequently homogeneous bent functions must have degree < n for n > 3.
Orthogonal Designs From Negacyclic Matrices, K. Finlayson, Jennifer Seberry
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
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
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
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 …
Complex Orthogonal Sequences From Amicable Hadamard Matrices, Le Chung Tran, Jennifer Seberry, Beata J. Wysocki, Tadeusz A. Wysocki, Tianbing Xia, Y. Zhao
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 …
Blind Source Separation Of Nonstationary Convolutively Mixed Signals In The Subband Domain, I. Russell, Jiangtao Xi, Alfred Mertins, Joe F. Chicharo
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 …
A Routing Strategy For Heterogeneous Mobile Ad Hoc Networks, Mehran Abolhasan, Justin Lipman, Joe F. Chicharo
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
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
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
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
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
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
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 …