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Faculty of Informatics - Papers (Archive)

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Articles 1201 - 1230 of 2013

Full-Text Articles in Physical Sciences and Mathematics

A Cryptographic Solution For General Access Control, Y. Kong, Jennifer Seberry, J. R. Getta, Ping Yu Sep 2005

A Cryptographic Solution For General Access Control, Y. Kong, Jennifer Seberry, J. R. Getta, Ping Yu

Faculty of Informatics - Papers (Archive)

As one of the most popular information safeguarding mechanisms, access control is widely deployed in information systems. However, access control approach suffers from a tough problem, i.e. system administrators must be unconditionally trusted. Cryptographic substitutes have been developed to solve the above problem. In particular, hierarchical encryption, as an alternate solution of access control in a hierarchy, has been intensively studied. In this paper, we propose a cryptographic solution for general access control based on Chinese Remainder Theorem. Our solution has two categories: data based solution and key based solution. In contrast to the most recent hierarchical encryption system: Ray, …

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Executable Specifications For Agent Oriented Conceptual Modelling, Y. Guan, Aditya K. Ghose Sep 2005

Executable Specifications For Agent Oriented Conceptual Modelling, Y. Guan, Aditya K. Ghose

Faculty of Informatics - Papers (Archive)

Agent-oriented conceptual modelling (AoCM) notations such as i* have received considerable recent attention as a useful approach to early-phase requirements engineering. AoCM notations are useful in modeling organizational context and in offering high-level anthropomorphic abstractions as modeling constructs. AoCM notations such as i* help answer questions such as what goals exist, how key actors depend on each other and what alternatives must be considered. In this paper, we suggest an approach to executing i* models by translating these into set of interacting agents implemented in the 3APL language. In addition, we suggest a hybrid modeling, or co-evolution, approach in which …

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Generalized Williamson And Wallis-Whiteman Constructions For Improved Square Order-8 Co Stbcs, Le Chung Tran, Tadeusz A. Wysocki, Jennifer Seberry, A. Mertins, Sarah A. Spence Sep 2005

Generalized Williamson And Wallis-Whiteman Constructions For Improved Square Order-8 Co Stbcs, Le Chung Tran, Tadeusz A. Wysocki, Jennifer Seberry, A. Mertins, Sarah A. Spence

Faculty of Informatics - Papers (Archive)

Constructions of square, maximum rate Complex Orthogonal Space-Time Block Codes (CO STBCs) are well known, however codes constructed via the known methods include numerous zeros, which impede their practical implementation. By modifying the Williamson and Wallis-Whiteman arrays to apply to complex matrices, we propose two methods of construction of square, order-4n CO STBCs from square, order-n codes which satisfy certain properties. Applying the proposed methods, we construct square, maximum rate, order-8 CO STBCs with no zeros, such that the transmitted symbols equally disperse through transmit antennas. Those codes, referred to as the improved square CO STBCs, have the advantages that …

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Simultaneous Map Estimation Of Inhomogeneity And Segmentation Of Brain Tissues From Mr Images, Wanqing Li, C. Desilver, Y. Attikiouzel Sep 2005

Simultaneous Map Estimation Of Inhomogeneity And Segmentation Of Brain Tissues From Mr Images, Wanqing Li, C. Desilver, Y. Attikiouzel

Faculty of Informatics - Papers (Archive)

Intrascan and interscan intensity inhomogeneities have been identified as a common source of making many advanced segmentation techniques fail to produce satisfactory results in separating brains tissues from multi-spectral magnetic resonance (MR) images. A common solution is to correct the inhomogeneity before applying the segmentation techniques. This paper presents a method that is able to achieve simultaneous semi-supervised MAP (maximum a-posterior probability) estimation of the inhomogeneity field and segmentation of brain tissues, where the inhomogeneity is parameterized. Our method can incorporate any available incomplete training data and their contribution can be controlled in a flexible manner and therefore the segmentation …

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The Power And Influence In Some Youden Squares And Secret Sharing, L. Fitina, Ken Russell, Jennifer Seberry Sep 2005

The Power And Influence In Some Youden Squares And Secret Sharing, L. Fitina, Ken Russell, Jennifer Seberry

Faculty of Informatics - Papers (Archive)

We investigate subsets of critical sets of some Youden squares in the context of secret sharing schemes. A subset C of a Youden square is called a critical set, if C can be uniquely completed to a Youden square but any subset of C cannot does not have a unique completion to a Youden square. That part of a Youden square Y which is inaccessible to subsets of a critical set C of Y, called the strongbox of C, may be thought to contain secret information. We study the size of the secret. Seberry and Street have shown how strongboxes …

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Optical Signal Processing For Fiber Bragg Grating Based Wear Sensors, Enbang Li, Jiangtao Xi, Joe F. Chicharo Aug 2005

Optical Signal Processing For Fiber Bragg Grating Based Wear Sensors, Enbang Li, Jiangtao Xi, Joe F. Chicharo

Faculty of Informatics - Papers (Archive)

In this study, we propose a simplified signal processing scheme for fiber Bragg grating (FBG) based wear sensing. Instead of using a chirped FBG and detecting the bandwidth, we use uniform gratings as sensors and measure the optical power reflected by the sensing grating to determine the length of the sensor grating, hence detect the wear. We demonstrate by the experiments that the proposed method is feasible and practical. The advantage of the proposed method lies in the fact that structure of the wear sensing system is simplified and therefore the cost can be significantly reduced. The principle of the …

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A Half-Frequency Domain Approach For Convolutive Blind Source Separation Based On Kullback-Leibler Divergence, T. Mei, Fuliang Yin, Jiangtao Xi, Alfred Mertins, Joe F. Chicharo Aug 2005

A Half-Frequency Domain Approach For Convolutive Blind Source Separation Based On Kullback-Leibler Divergence, T. Mei, Fuliang Yin, Jiangtao Xi, Alfred Mertins, Joe F. Chicharo

Faculty of Informatics - Papers (Archive)

This paper studies the problem of blind separation of convolutive mixtures by means of Kullback-Leibler divergence in frequency domain. Unlike exiting approaches, an integrated objective function is defined in frequency-domain with time-domain parameters as the variables. The permutation problem is avoided through the frequency domain integration and time domain optimization. Simulation results show that the algorithm is valid and of high performance for the separation of real world recorded convolutive mixtures.

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Shift Estimation Method Based Fringe Pattern Profilometry And Performance Comparison, Y. Hu, Jiangtao Xi, Enbang Li, Joe F. Chicharo, Zongkai Yang Aug 2005

Shift Estimation Method Based Fringe Pattern Profilometry And Performance Comparison, Y. Hu, Jiangtao Xi, Enbang Li, Joe F. Chicharo, Zongkai Yang

Faculty of Informatics - Papers (Archive)

In this paper, we present and study two approaches to fringe pattern profilometry (FPP) technique. Based on generalized analysis model for fringe pattern profilometry (FPP), Inverse Function based Shift Estimation (IFSE) and Gradient-based Shift Estimation (GSE) are proposed to calculate the shift between the projected and deformed fringe patterns. Further, computer simulations are utilized to compare the performance between these two methods. Meanwhile, we also compare these two algorithms with Phase Shift profilometry (PSP). It can be seen that both of these two shift estimation algorithms can significantly improve the measurement accuracy when the fringe patterns are nonlinearly distorted.

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An Improved Dynamic Model For Optical Feedback Self-Mixing Interferometry-Based Measurement And Instrumentation, Jiangtao Xi, Yuanguang Yu, Enbang Li, Joe F. Chicharo Aug 2005

An Improved Dynamic Model For Optical Feedback Self-Mixing Interferometry-Based Measurement And Instrumentation, Jiangtao Xi, Yuanguang Yu, Enbang Li, Joe F. Chicharo

Faculty of Informatics - Papers (Archive)

This paper presents a new model that describes the behaviour of optical feedback self-mixing interferometry (OFSMI). Compared to the existing model, the proposed one does not suffer from the multiple value ambiguity problems. The proposed model is a dynamic one that gives a unique relationship between the external target moving law and the self-mixing signal (SMS) waveform (SMS) when other parameters are given. A computer simulation tool for OFSMI has been implemented to generate SMS waveforms and its effectiveness has been verified by experimental data.

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An Investigation Of Temporal Modeling In Blind Signal Separation, Daniel Smith, Jason Lukasiak, Ian Burnett Aug 2005

An Investigation Of Temporal Modeling In Blind Signal Separation, Daniel Smith, Jason Lukasiak, Ian Burnett

Faculty of Informatics - Papers (Archive)

This paper investigates the performance of blind signal separation (BSS) algorithms that exploit the temporal predictability of speech. Specifically, the investigation considers how the separation performance of two BSS algorithms will be affected when the length of the AR process (used in the algorithms to model speech) is varied. The investigation concludes that the length of the AR process (prediction order) has a significant impact on separation performance. In particular, the separation performance of both algorithms is degraded, if the AR model’s prediction order, over fits, or under fits, the temporal structure of the speech. It is revealed that a …

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Wireless Ad-Hoc Control Networks, Shengrong Bu, Fazel Naghdy Aug 2005

Wireless Ad-Hoc Control Networks, Shengrong Bu, Fazel Naghdy

Faculty of Informatics - Papers (Archive)

A new concept called wireless ad-hoc control networks (WACNets), designed for distributed and remote monitoring and control is suggested in this work. Such systems represent the next stage in the evolution of distributed control and monitoring. WACNet explores a framework for organic, evolutionary and scalable method of integrating a large number of nodes with sensing and/or actuation, local intelligence and control, data processing and communication capabilities. The concept is introduced and the design of the network is presented. As an essential element in the operation of WACNet, service discovery developed for WACNet will be described and progress made so far …

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Estimating The Parameters Of Semiconductor Lasers Based On Weak Optical Feedback Self-Mixing Interferometry, Jiangtao Xi, Yanguang Yu, Joe F. Chicharo, T. Bosch Aug 2005

Estimating The Parameters Of Semiconductor Lasers Based On Weak Optical Feedback Self-Mixing Interferometry, Jiangtao Xi, Yanguang Yu, Joe F. Chicharo, T. Bosch

Faculty of Informatics - Papers (Archive)

The paper presents a practical approach for measuring the linewidth enhancement factor /spl alpha/ of semiconductor lasers and the optical feedback level factor C in a semiconductor laser with an external cavity. The proposed approach is based on the analysis of the signals observed in an optical feedback self-mixing interferometric system. The parameters /spl alpha/ and C are estimated using a gradient-based optimization algorithm that achieves best data-to-theoretical model match. The effectiveness and accuracy of the method has been confirmed and tested by computer simulations and experiments, which show that the proposed approach is able to estimate /spl alpha/ and …

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A Coloured Petri Net Based Strategy For Multi-Agent Scheduling, Q. Bai, Minjie Zhang, H. Zhang Jul 2005

A Coloured Petri Net Based Strategy For Multi-Agent Scheduling, Q. Bai, Minjie Zhang, H. Zhang

Faculty of Informatics - Papers (Archive)

In the last decade, the focus of agent research has shifted from single agent systems to multi-agent systems (MASs). Dynamic agent coordination is one of the challenge problems of multi-agent research. One coordination problem is how to achieve agent scheduling under open dynamic environments. Petri Nets (PNs) and Coloured Petri Nets (CPNs) are system study tools that provide an appropriate mathematical formalism for the description, construction and analysis of distributed and concurrent systems. In this paper, we present a CPN based strategy to schedule and allocate new tasks to suitable agent(s) or agent combinations. In this strategy, through using CPNs …

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Universal Designated Multi Verifier Signature Schemes, Ching Yu Ng, Willy Susilo, Y. Mu Jul 2005

Universal Designated Multi Verifier Signature Schemes, Ching Yu Ng, Willy Susilo, Y. Mu

Faculty of Informatics - Papers (Archive)

The notion of Universal Designated-Verifier Signatures was put forth by Steinfeld et. al. in Asiacrypt 2003. This notion allows a signature holder to designate the signature to a desired designated-verifier. In this paper, we extend this notion to allow a signature holder to designate the signature to multi verifiers, and hence, we call our scheme as Universal Designated Multi Verifier Signatures. We provide security proofs for our schemes based on the random oracle model.

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Delegatable Access Control For Fine-Grained Xml, Jing Wu, Jennifer Seberry, Y. Mu, Chun Ruan Jul 2005

Delegatable Access Control For Fine-Grained Xml, Jing Wu, Jennifer Seberry, Y. Mu, Chun Ruan

Faculty of Informatics - Papers (Archive)

The access control mechanisms are critical to ensure security in XML (eXtensible Markup Language). Several such mechanisms have been used or proposed; however, the notion of delegation in XML has not been studied in the literature. In this paper, we propose an access control model encapsuling delegation authorization rules for XML documents that allow flexible data granularity and limited inference protection. Our access control policy specification is basically DTD-based. It can also be considered to be document-based.

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Humancentric Applications Of Rfid Implants: The Usability Contexts Of Control, Convenience And Care, Amelia Masters, Katina Michael Jul 2005

Humancentric Applications Of Rfid Implants: The Usability Contexts Of Control, Convenience And Care, Amelia Masters, Katina Michael

Faculty of Informatics - Papers (Archive)

Recent developments in the area of RFID have seen the technology expand from its role in industrial and animal tagging applications, to being implantable in humans. With a gap in literature identified between current technological development and future humancentric possibility, little has been previously known about the nature of contemporary humancentric applications. This paper utilizes usability context analyses, to provide a cohesive study on the current development state of humancentric applications, detached from the emotion and prediction which plagues this particular technology.

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Routing In Manets With Address Conflicts, Kwan-Wu Chin, Darryn Lowe, W. H. O. Lau Jul 2005

Routing In Manets With Address Conflicts, Kwan-Wu Chin, Darryn Lowe, W. H. O. Lau

Faculty of Informatics - Papers (Archive)

Mobile ad-hoc networks (MANETs) are dynamic and multi-hop in nature. As nodes continually join and leave the MANET, managing the problem of address conflicts is particularly challenging. In the past, researchers have gone to great lengths to ensure that nodes are assigned unique addresses and various protocols and policies have been designed to resolve address conflicts. In this paper, we argue that current solutions, originally designed for static wired networks, put unnecessary stress on the dynamic operation of a MANET. To solve, this problem, we present a MANET that can continue to operate even when there are conflicting addresses. Unlike …

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Orthogonal Designs With Quaternion Elements, K. Finlayson, Jennifer Seberry, Tadeusz A. Wysocki, Tianbing Xia Jul 2005

Orthogonal Designs With Quaternion Elements, K. Finlayson, Jennifer Seberry, Tadeusz A. Wysocki, Tianbing Xia

Faculty of Informatics - Papers (Archive)

We introduce orthogonal designs with quaternion elements and show their existence. In future work we explore these applications to signal processing.

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Introducing Location-Based Services Into Information Technology Curriculum: Reflections On Practice, Katina Michael, Holly Tootell Jul 2005

Introducing Location-Based Services Into Information Technology Curriculum: Reflections On Practice, Katina Michael, Holly Tootell

Faculty of Informatics - Papers (Archive)

This paper describes how location-based services (LBS) was introduced into the information technology curriculum at the University of Wollongong in 2004. The inquiry is based on two academic reflections on practice. The results indicate that students found the course experience both intellectually challenging and rewarding. Academics linked to the project found the topic aligned well to their research interests and stimulated new ideas for grant applications. And industry representatives found the experience advantageous, a vehicle for collaboration, and subsequently a way to give something back to their local community. In summary the dynamic exchange of knowledge between staff, students, and …

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The Pros And Cons Of Rfid In Supply Chain Management, Katina Michael, Luke Mccathie Jul 2005

The Pros And Cons Of Rfid In Supply Chain Management, Katina Michael, Luke Mccathie

Faculty of Informatics - Papers (Archive)

This paper presents the pros and cons of using radio-frequency identification (RFID) in supply chain management (SCM). While RFID has a greater number of benefits than its predecessor, the bar code, it currently comes at a price that many businesses still consider prohibitive. On the one hand, RFID is advantageous because it does not require line-of-sight scanning, it acts to reduce labor levels, enhances visibility, and improves inventory management. On the other hand, RFID is presently a costly solution, lacking standardization, it has a small number of suppliers developing end-to-end solutions, suffers from some adverse deployment issues, and is clouded …

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Using Spatial Cues For Meeting Speech Segmentation, E Cheng, J Lukasiak, Ian S. Burnett, David A. Stirling Jul 2005

Using Spatial Cues For Meeting Speech Segmentation, E Cheng, J Lukasiak, Ian S. Burnett, David A. Stirling

Faculty of Informatics - Papers (Archive)

This work investigates the validity and accuracy of using spatialcues with Time-Delay Estimation (TDE) as a method of segmenting multichannel recorded speech by speaker location. In environments such as meetings where speakers do not significantly alter position, segmentation by speaker location essentially leads to segmentation by speaker ‘ turn’. The proposed system calculates location information using TDEs and spatial cues extracted from multichannel meeting audio recordings. This location information is then input into a simple segmentation algorithm. Experiments have been performed on both theoretical and real meeting recordings with non-overlapping speakers, and theoretical recordings with overlapping speakers. Segmentation results reveal …

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Exchanging Xml Multimedia Containers Using A Binary Xml Protocol, S. J. Davis, I. Burnett Jul 2005

Exchanging Xml Multimedia Containers Using A Binary Xml Protocol, S. J. Davis, I. Burnett

Faculty of Informatics - Papers (Archive)

XML is becoming increasingly popular as the ubiquitous standard for metadata; consequently, it is being incorporated into many multimedia applications, such as those based on MPEG-7 and MPEG-21. However, XML is often verbose and transmitting the large filescan be wasteful in bandwidth and power-limited mobile applications. This paper introduces an XML access mechanism, RXEP, which combines XML compression with a fragment access protocol. RXEP ensures that essential information is exchanged efficiently while minimising superfluous XML content transmission. This makes XML containers an attractive technique for multimedia content delivery.

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Ontology-Based Resource Descriptions For Distributed Information Sources, Hui Yang, Minjie Zhang Jul 2005

Ontology-Based Resource Descriptions For Distributed Information Sources, Hui Yang, Minjie Zhang

Faculty of Informatics - Papers (Archive)

Content-based resource description is the key to find appropriate information sources that are most likely to contain the relevant documents for a given user query. However, semantic heterogeneity makes it difficult to acquire accurate and meaningful resource descriptions from distributed, heterogeneous information sources. To address this problem, we describe an ontology-based approach which uses domain-specific ontologies to extract content-related information from information sources, and to generate ontology-based resource descriptions. The preliminary experimental results demonstrate that our ontology-based approach could improve selection accuracy.

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Compression Transparent Low-Level Description Of Audio Signals, Jason Lukasiak, C. Mcelroy, E Cheng Jul 2005

Compression Transparent Low-Level Description Of Audio Signals, Jason Lukasiak, C. Mcelroy, E Cheng

Faculty of Informatics - Papers (Archive)

A new low level audio descriptor that represents the psycho acoustic noise floor shape of an audio frame is proposed. Results presented indicate that the proposed descriptor is far more resilient to compression noise than any of the MPEG-7 low level audio descriptors. In fact, across a wide range of files, on average the proposed scheme fails to uniquely identify only five frames in every ten thousand. In addition, the proposed descriptor maintains a high resilience to compression noise even when decimated to use only one quarter of the values per frame to represent the noise floor. This characteristic indicates …

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Mmse-Optimal Approximation Of Continuous-Phase Modulated Signal As Superposition Of Linearly Modulated Pulses, Xiaojing Huang, Y. Li Jul 2005

Mmse-Optimal Approximation Of Continuous-Phase Modulated Signal As Superposition Of Linearly Modulated Pulses, Xiaojing Huang, Y. Li

Faculty of Informatics - Papers (Archive)

The optimal linear modulation approximation of any M-ary continuous-phase modulated (CPM) signal under the minimum mean-square error (MMSE) criterion is presented in this paper. With the introduction of the MMSE signal component, an M-ary CPM signal is exactly represented as the superposition of a finite number of MMSE incremental pulses, resulting in the novel switched linear modulation CPM signal models. Then, the MMSE incremental pulse is further decomposed into a finite number of MMSE pulse-amplitude modulated (PAM) pulses, so that an M-ary CPM signal is alternatively expressed as the superposition of a finite number of MMSE PAM components, similar to …

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Teaching Content Creation With Programming, Phillip J. Mckerrow Jul 2005

Teaching Content Creation With Programming, Phillip J. Mckerrow

Faculty of Informatics - Papers (Archive)

Multimedia is an art form that uses computers as a means of personal expression. However, much multimedia content is unattractive, and many applications have poor user interfaces because many developers don't have training in both programming and content creation. To counteract this, we teach students QuickTime for Java, which provides a rich library for manipulating media. Our students reported an increased understanding of multimedia programming and developed creative skills.

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Bitstream Binding Language – Mapping Xml Multimedia Containers Into Streams, Joseph Thomas-Kerr, I. Burnett, Philip Ciufo Jul 2005

Bitstream Binding Language – Mapping Xml Multimedia Containers Into Streams, Joseph Thomas-Kerr, I. Burnett, Philip Ciufo

Faculty of Informatics - Papers (Archive)

Bitstream Binding Language (BBL) provides an abstraction layer between XML multimedia containers and the way their resources and metadata are published in a bitstream. It allows multiple bindings from a single source document to facilitate interoperability and applicability of the multimedia content to a wide range of terminals and users. BBL introduces a number of features not found in other XML fragmentation techniques – such as support for random-access – and provides a highly general framework for combining metadata with multimedia content in a transport format. This paper presents an overview of BBL and provides details of a Java implementation …

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Simple Cpm Receivers Based On A Switched Linear Modulation Model, Xiaojing Huang, Y. Li Jul 2005

Simple Cpm Receivers Based On A Switched Linear Modulation Model, Xiaojing Huang, Y. Li

Faculty of Informatics - Papers (Archive)

Based on a switched linear modulation model recently developed for continuous-phase modulated (CPM) signal representation and approximation, and incorporated with new phase state symbol definitions, three simple CPM receivers are proposed in this letter. Their performance simulation results and complexity comparison are given using a quaternary 2RC (raised cosine frequency pulse) CPM scheme.

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On The Growth Problem For Skew And Symmetric Conference Matrices, C. Kravvaritis, M. Mitrouli, Jennifer Seberry Jul 2005

On The Growth Problem For Skew And Symmetric Conference Matrices, C. Kravvaritis, M. Mitrouli, Jennifer Seberry

Faculty of Informatics - Papers (Archive)

C. Koukouvinos, M. Mitrouli and Jennifer Seberry, in "Growth in Gaussian elimination for weighing matrices, W (n, n — 1)", Linear Algebra and its Appl., 306 (2000), 189-202, conjectured that the growth factor for Gaussian elimination of any completely pivoted weighing matrix of order n and weight n— 1 is n— 1 and that the first and last few pivots are (1,2,2,3 or 4, ..., n–1 or (n–1)/2, , (n–1)/2, n–1) for n > 14. In the present paper we study the growth problem for skew and symmetric conference matrices. An algorithm for extending a k × k matrix with elements …

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Power Efficient Connected Topologies In Ad-Hoc Networks, G. Srivastava, Joe F. Chicharo, P. Boustead Jun 2005

Power Efficient Connected Topologies In Ad-Hoc Networks, G. Srivastava, Joe F. Chicharo, P. Boustead

Faculty of Informatics - Papers (Archive)

Power efficient topologies in an ad-hoc network can reduce battery usage and increase the lifetime of a network. Topology control algorithms including a local minimum spanning tree (LMST), distributed relative neighbourhood graph (DRNG) and K-Neigh graphs are computed by using the location or the distance information of the network nodes. Inaccurate distance or location information can lead to disconnected topology graphs. Furthermore, a distance based topology graph may not necessarily be connected due to wireless signal attenuation and propagation characteristics. In a realistic scenario, a small link distance may correspond to a large transmission power as the signal may need …

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