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Faculty of Informatics - Papers (Archive)

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Articles 1801 - 1830 of 2013

Full-Text Articles in Physical Sciences and Mathematics

New Wavelet Based Art Network For Texture Classification, Jiazhao Wang, Golshah Naghdy, Philip O. Ogunbona Jan 1996

New Wavelet Based Art Network For Texture Classification, Jiazhao Wang, Golshah Naghdy, Philip O. Ogunbona

Faculty of Informatics - Papers (Archive)

A new method for texture classification is proposed. It is composed of two processing stages, namely, a low level evolutionary feature extraction based on Gabor wavelets and a high level neural network based pattern recognition. This resembles the process involved in the human visual system. Gabor wavelets are exploited as the feature extractor. A neural network, Fuzzy Adaptive Resonance Theory (Fuzzy ART), acts as the high level decision making and recognition system. Some modifications to the Fuzzy ART make it capable of simulating the post-natal and evolutionary development of the human visual system. The proposed system has been evaluated using …

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Texture Analysis Using Gabor Wavelets, Golshah Naghdy, Jianli Wang, Philip Ogunbona Jan 1996

Texture Analysis Using Gabor Wavelets, Golshah Naghdy, Jianli Wang, Philip Ogunbona

Faculty of Informatics - Papers (Archive)

Receptive field profiles of simple cells in the visual cortex have been shown to resemble even- symmetric or odd-symmetric Gabor filters. Computational models employed in the analysis of textures have been motivated by two-dimensional Gabor functions arranged in a multi-channel architecture. More recently wavelets have emerged as a powerful tool for non-stationary signal analysis capable of encoding scale-space information efficiently. A multi-resolution implementation in the form of a dyadic decomposition of the signal of interest has been popularized by many researchers. In this paper, Gabor wavelet configured in a 'rosette' fashion is used as a multi-channel filter-bank feature extractor for …

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Differentiate And Make Waves, R. Nillsen Jan 1996

Differentiate And Make Waves, R. Nillsen

Faculty of Informatics - Papers (Archive)

In 1972 Gary Meisters and Wolfgang Schmidt showed that if the Fourier coefficient of a function is zero at the origin, then the function is a sum of three first order differences. They deduced from this that every translation invariant linear form on the space of square integrable functions on the circle group is automatically continuous. Their results were subsequently developed by the author for the case of n-dimensional Euclidean space (Lectures Notes in Mathematics, vol. 1586, Springer-Verlag,1994). The present paper gives an exposition of some of the ideas in this work, with the aim of minimising the technicalities. In …

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Global Telerobotics: Exploring Effective Internet Access To Robots, Simon Hartfiel, Susan Hartfiel, Leone Dunn Jan 1996

Global Telerobotics: Exploring Effective Internet Access To Robots, Simon Hartfiel, Susan Hartfiel, Leone Dunn

Faculty of Informatics - Papers (Archive)

This paper describes an Industrial Automation research project at the University of Wollongong, Australia. The project aims to develop a telerobotic planning and control architecture and human robot interface that can be used for intervention robots which require task level programming. In order to investigate global telerobotic principles, the workspace will be made accessible across the Internet via the World Wide Web. The paper describes the experimental setup and implementation of this project, focussing on a discussion of human robot interaction issues, such as interface design problems and the use of a World Wide Web browser for user interaction.

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Circulant Weighing Designs, K. T. Arasu, Jennifer Seberry Jan 1996

Circulant Weighing Designs, K. T. Arasu, Jennifer Seberry

Faculty of Informatics - Papers (Archive)

Algebraic techniques are employed to obtain necessary conditions for the existence of certain families of circulant weighing designs. As an application we rule out the existence of many circulant weighing designs. In particular, we show that there does not exist a circulant weighing matrix of order 43 for any weight. We also prove two conjectures of Yosef Strassler. © 1996 John Wiley & Sons, Inc.

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Selective Withdrawal From Stratified Streams, Chia-Shun Yih, Song-Ping Zhu Jan 1996

Selective Withdrawal From Stratified Streams, Chia-Shun Yih, Song-Ping Zhu

Faculty of Informatics - Papers (Archive)

Selective withdrawal from a stratified stream is considered. The average density of the withdrawn fluid and the flow pattern are found, within the limitations on the densimetric Froude number and the withdrawal rate specified in this paper, to depend on the strength and location of the sink, and very little on any slight variation in the velocity distribution far upstream and the densimetric Froude number. The upstream density distribution is assumed linear, but many other density distributions can be similarly treated.

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Latin Squares: Critical Sets And Their Lower Bounds, Diane Donovan, Joan Cooper, D. J. Nott, Jennifer Seberry Jan 1995

Latin Squares: Critical Sets And Their Lower Bounds, Diane Donovan, Joan Cooper, D. J. Nott, Jennifer Seberry

Faculty of Informatics - Papers (Archive)

In this paper we establish a number of new lower bounds on the size of a critical set in a latin square. In order to do this we first give two results which give critical sets for isotopic latin squares and conjugate latin squares. We then use these results to increase the known lower bound for specific classes of critical sets. Finally, we take a detailed look at a number of latin squares of small order. In some cases, we achieve an exact lower bound for the size of the minimal critical set.

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Nonlinearity And Propagation Characteristics Of Balanced Boolean Functions, Jennifer Seberry, Xian-Mo Zhang, Yuliang Zheng Jan 1995

Nonlinearity And Propagation Characteristics Of Balanced Boolean Functions, Jennifer Seberry, Xian-Mo Zhang, Yuliang Zheng

Faculty of Informatics - Papers (Archive)

Three important criteria for cryptographically strong Boolean functions are balance, nonlinearity, and the propogation criterion. The main contributions of this paper are to reveal a number of interesting properties of balance and nonlinearity, and to study systematic methods for contructing Boolean functions that satisfy some or all of the three criteria. We show that concatenating, splitting, modifying, and multiplying (in the sense of Kronecker) sequences can yield balanced Boolean functions with a very high nonlinearity. In particular, we show that balanced Boolean functions obtained by modifying and multiplying sequences achieve a nonlinearity higher than that attainable by any previously known …

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The Relationship Between Propagation Characteristic And Nonlinearity Of Cryptographic Functions, Jennifer Seberry, Xian-Mo Zhang, Yuliang Zheng Jan 1995

The Relationship Between Propagation Characteristic And Nonlinearity Of Cryptographic Functions, Jennifer Seberry, Xian-Mo Zhang, Yuliang Zheng

Faculty of Informatics - Papers (Archive)

The connections among the various nonlinearity criteria is currently an important topic in the area of designing and analyzing cryptographic function. In this paper we show a quantitative relationship between propagation characteristics and nonlinearity, two critical indicators of the cryptographic strength of a Boolean function. We also present a tight lower bound on the nonlinearity of a cryptographic function that has propagation characteristics.

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Applications Of Smartcards For Anonymous And Verifiable Databases, Thomas Hardjono, Jennifer Seberry Jan 1995

Applications Of Smartcards For Anonymous And Verifiable Databases, Thomas Hardjono, Jennifer Seberry

Faculty of Informatics - Papers (Archive)

In this paper we describe a practical solution towards anonymous and verifiable databases based on the use of smartcards and the recent Improved Leighton-Micali protocol for the distribution of keys. The scheme is addressed particularly to public data held in separate government databases with the aim of preventing unauthorized government institutions from gathering and merging private data concerning individuals from these separate containers. The solution can be realized through the recent Clipper Chip and smartcard technology, and its security relies on the strength of these technologies. The scheme is also extendible to mobile computing environments.

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The Weighing Matrices Of Order 4n And Weight 4n-2 And 2n-1, Marc Gysin, Jennifer Seberry Jan 1995

The Weighing Matrices Of Order 4n And Weight 4n-2 And 2n-1, Marc Gysin, Jennifer Seberry

Faculty of Informatics - Papers (Archive)

We give algorithms and constructions for mathematical and computer searches which allow us to establish the existence of W(4n, 4n - 2) and W (4n, 2n - 1) for many orders 4n less than 4000. We compare these results with the orders for which W(4n, 4n) and W(4n, 2n) are known. We use new algorithms based on the theory of cyclotomy to obtain new T-matrices of order 43 and JM-matrices which yield W(4n, 4n - 2) for n = 5,7,9,11,13,17,19,25,31,37,41,43,61,71,73,157.

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Relating Nonlinearity To Propagation Characteristics, Jennifer Seberry, Xian-Mo Zhang, Yuliang Zheng Jan 1995

Relating Nonlinearity To Propagation Characteristics, Jennifer Seberry, Xian-Mo Zhang, Yuliang Zheng

Faculty of Informatics - Papers (Archive)

The connections among the various nonlinearity criteria is currently an important topic in the area of designing and analyzing cryptographic functions. In this paper we show a quantitative relationship between propagation characteristics and nonlinearity, two critical indicators of the cryptographic strength of a Boolean function. We also present a tight lower bound on the nonlinearity of a cryptographic function that has propagation characteristics.

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Information Security In Mobile Databases, Thomas Hardjono, Jennifer Seberry Jan 1995

Information Security In Mobile Databases, Thomas Hardjono, Jennifer Seberry

Faculty of Informatics - Papers (Archive)

During the last decade the decrease in the size of computing machinery, coupled with the increase in their computing power have lend to the development of the concept of mobile computing. Effects of this new vision can be seen currently in the flourishing numbers of mobile telephones and portable computing units. In the current work we investigate some issues concerning the security of databases and database systems in the mobile computing environment. We present a scheme for end-to-end secure data transfer between one mobile computing element to another based on a recent protocol for key distribution. Secure data transfer is …

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Hybrid Predictive/Vq Lossless Image Coding, P O. Ogunbona, Jianli Wang, Golshah Naghdy Jan 1995

Hybrid Predictive/Vq Lossless Image Coding, P O. Ogunbona, Jianli Wang, Golshah Naghdy

Faculty of Informatics - Papers (Archive)

A multiplicative autoregressive model is used in a lossless predictive image coding scheme. The use of vector quantisation (VQ) for compression of the model coefficients leads to an improved compression ratio. Both image adaptive and universal codebooks are considered. A comparative analysis of the new coder is presented through simulation results.

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Industrial Computer Vision Using Undefined Feature Extraction, Phil Evans, John A. Fulcher, Philip Ogunbona Jan 1995

Industrial Computer Vision Using Undefined Feature Extraction, Phil Evans, John A. Fulcher, Philip Ogunbona

Faculty of Informatics - Papers (Archive)

This paper presents an application of computer The implementation and operation of the system is vision in a real-world uncontrolled environment found at BHP Steel Port Kembla. The task is visual identification of torpedo ladles at a Blast Furnace wlahdilceh. is achieved by reading numbers attached to each 3. IMPLEMENTATION Number recognition is achieved through use of feature extraction using a Multi-Layer Perceptron (MLP) Artificial Neural Network (ANN). The novelty in the method used in this application is that the features the MLP is being trained to extract are undefined before the MLP is initialised. The results of the MLP …

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New Feature-Based Image Adaptive Vector Quantisation Coder, Jamshid Shanbehzadeh, Philip O. Ogunbona Jan 1995

New Feature-Based Image Adaptive Vector Quantisation Coder, Jamshid Shanbehzadeh, Philip O. Ogunbona

Faculty of Informatics - Papers (Archive)

It is difficult to achieve a good low bit rate image compression performance with traditional block coding schemes such as transform coding and vector quantization, without regard for the human visual perception or signal dependency. These classical block coding schemes are based on minimizing the MSE at a certain rate. This procedure results in more bits being allocated to areas which may not be visually important and the resulting quantization noise manifests as a blocking artifact. Blocking artifacts are known to be psychologically more annoying than white noise when the human visual response is considered. While image adaptive vector quantization …

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Information Security Issues In Mobile Computing, Thomas Hardjono, Jennifer Seberry Jan 1995

Information Security Issues In Mobile Computing, Thomas Hardjono, Jennifer Seberry

Faculty of Informatics - Papers (Archive)

During the last decade the decrease in the size of computing machinery, coupled with the increase in their computing power has lend to the development of the concept of mobile computing. Effects of this new vision is currently evident in the flourishing numbers of mobile telephones and portable computing units. In this paper we investigate some issues concerning the security of mobile computing systems, within the framework of the categories of mobility, disconnection, data access modes and scale of operation (Imielinski & Badrinath, 1993). In contrast to previous works which concentrate on security in wireless communications, we focus on the …

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Relationship Among Nonlinearity Criteria, Jennifer Seberry, Xian-Mo Zhang, Yuliang Zheng Jan 1995

Relationship Among Nonlinearity Criteria, Jennifer Seberry, Xian-Mo Zhang, Yuliang Zheng

Faculty of Informatics - Papers (Archive)

An important question in designing cryptographic functions including substitution boxes (S-boxes) is the relationships among the various nonlinearity criteria each of which indicates the strength or weakness of a cryptographic function against a particular type of cryptanalytic attack. In this paper we reveal, for the first time, interesting connections among the strict avalanche characteristics, differential characteristics, linear structures and nonlinearity of quadratic (S-boxes). In addition, we show that our proof techniques allow us to treat in a unified fashion all quadratic permutations (namely, quadratic (S-boxes that form permutations), regardless of the underlying construction methods. This greatly simplifies the proofs for …

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New Normal Sequences Of Length 25, Marc Gysin, Jennifer Seberry Jan 1995

New Normal Sequences Of Length 25, Marc Gysin, Jennifer Seberry

Faculty of Informatics - Papers (Archive)

An introduction to binary sequences, combinatorial designs and how they are related to communication theory and computer security is given. An exhaustive search algorithm for normal sequences is presented. This is the first time that the lengths n = 24 and n = 25 have been searched through completely. No sequences of length 24 are found. It turns out that all the normal sequences of length 25 can be derived from Turyn sequences. This construction is subject to a new theorem that is given here.

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Structures Of Cryptographic Functions With Strong Avalanche Characteristics, Jennifer Seberry, Xian-Mo Zhang, Yuliang Zheng Jan 1995

Structures Of Cryptographic Functions With Strong Avalanche Characteristics, Jennifer Seberry, Xian-Mo Zhang, Yuliang Zheng

Faculty of Informatics - Papers (Archive)

This paper studies the properties and constructions of non linear functions, which are a core component of cryptographic primi- tives including data encryption algorithms and one-way hash function. A main contribution of this paper is to reveal the relationship between nonlinearity and propagation characteristic, two critical indicators of the cryptographic strength of a Boolean function. In particular, (we prove that (i) if f, a Boolean function on Vn, satisfies the propagation criterion with respect to all but a subset R of vectors in Vn, then the nonlinearity of f satisfies Nf ≥ 2 n-1 - …

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Small-Area Estimation: An Appraisal - Comment, Noel A. Cressie, Mark S. Kaiser Jan 1994

Small-Area Estimation: An Appraisal - Comment, Noel A. Cressie, Mark S. Kaiser

Faculty of Informatics - Papers (Archive)

Malay Ghosh and Jon Rao have presented us with a well written exposition of the topic of small area estimation. The past literature has been de-cidedly influenced by linear modeling, and we see that clearly in their paper. There has also been a tendency to judge the performance of the estimation methods by concentrating on a single, arbitrary small area. In our comment, we shall discuss what opportunities there might be to expand the class of statistical models for small area data and to consider multivariate aspects of small area estimation.

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Texture Analysis Using Partially Ordered Markov Models, Jennifer Davidson, Ashit Talukder, Noel A. Cressie Jan 1994

Texture Analysis Using Partially Ordered Markov Models, Jennifer Davidson, Ashit Talukder, Noel A. Cressie

Faculty of Informatics - Papers (Archive)

Texture is a phenomenon in image data that continues to receive wide-spread interest due to its broad range of applications. The paper focuses on but one of several ways to model textures, namely, the class of stochastic texture models. the authors introduce a new spatial stochastic model called partially ordered Markov models, or POMMs. They show how POMMs are a generalization of a class of models called Markov mesh models, or MMMs, that allow an explicit closed form of the joint probability, just as do MMMs. While POMMs are a type of Markov random field model (MRF), the general MRFs …

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Comments On "Generating And Counting Binary Bent Sequences", Claude Carlet, Jennifer Seberry, Xian-Mo Zhang Jan 1994

Comments On "Generating And Counting Binary Bent Sequences", Claude Carlet, Jennifer Seberry, Xian-Mo Zhang

Faculty of Informatics - Papers (Archive)

We prove that the conjecture on bent sequences stated in"Generating and counting bent sequences". IEEE Transactions on Information Theory, IT-36 No. 5, 1990 by C.M. Adams and S.E. Tavares is false.

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The Strong Kronecker Product, Warwick De Launey, Jennifer Seberry Jan 1994

The Strong Kronecker Product, Warwick De Launey, Jennifer Seberry

Faculty of Informatics - Papers (Archive)

The strong Kronecker product has proved a powerful new multiplication tool for orthogonal matrices. This paper obtains algebraic structure theorems and properties for this new product. The results are then applied to give new multiplication theorems for Hadamard matrices, complex Hadamard matrices and other related orthogonal matrices. We obtain complex Hadamard matrices of order 8abcd from complex Hadamard matrices of order 2a, 2b, 2c, and 2d, and complex Hadamard matrices of order 32abcdef from Hadamard matrices of orders 4a, 4b, 4c, 4d, 4e, and 4f We also obtain a pair of disjoint amicable OD(8hn; 2hn, 2hn)s from Hadamard matrices of …

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On The Existence Of Turyn Sequences Of Length Less Than 43, Genet M. Edmondson, Jennifer Seberry, Malcolm R. Anderson Jan 1994

On The Existence Of Turyn Sequences Of Length Less Than 43, Genet M. Edmondson, Jennifer Seberry, Malcolm R. Anderson

Faculty of Informatics - Papers (Archive)

Some theoretical results and computational algorithms are described which verify previous calculations, prove some theoretical nonexistence results, and totally enumerate all inequivalent Turyn sequences of length less than 43, that is, the longer sequence has length less than 43.

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A Few More Small Defining Sets For Sbibd(4t-1, 2t-1, T-1), Thomas Kunkle, Jennifer Seberry Jan 1994

A Few More Small Defining Sets For Sbibd(4t-1, 2t-1, T-1), Thomas Kunkle, Jennifer Seberry

Faculty of Informatics - Papers (Archive)

It has been conjectured by Dinesh Sarvate and Jennifer Seberry, that, when p is an odd prime or prime power congruent to 1 mod 4, a certain collection of p sets of p elements can be used to define uniquely an SBIBD(2p+ 1, p, 1/2(p-1)), and that, when p is a prime power congruent to 3 mod 4, then a certain collection of 1/2(p-1) sets can be used to define uniquely an SBIBD(p, 4(p - 1), 1/4(p - 3)). This would mean that, in certain cases, 2t - 1 rows are …

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Multiplication Of Sequences With Zero Autocorrelation, Christos Koukouvinos, Stratis Kounias, Jennifer Seberry, C. H. Yang, Joel Yang Jan 1994

Multiplication Of Sequences With Zero Autocorrelation, Christos Koukouvinos, Stratis Kounias, Jennifer Seberry, C. H. Yang, Joel Yang

Faculty of Informatics - Papers (Archive)

Near normal sequences of new lengths n = 4m + 1 = 49,53,57 are constructed. The relation between a special set of near normal sequences and Golay sequences is discussed. A reformulation of Yang's powerful theorems on T-sequences is also given. We give base sequences for lengths m + p, m + p, m, m for p = 1 and m є {19, ... ,30}. Some of these are new lengths, or new decompositions into four squares for n and constructed here for the first time.

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On Sequences With Zero Autocorrelation, Christos Koukouvinos, Stratis Kounias, Jennifer Seberry, C. H. Yang, Joel Yang Jan 1994

On Sequences With Zero Autocorrelation, Christos Koukouvinos, Stratis Kounias, Jennifer Seberry, C. H. Yang, Joel Yang

Faculty of Informatics - Papers (Archive)

Normal sequences of lengths n = 18, 19 are constructed. It is proved through an exhaustive search that normal sequences do not exist for n = 17,21,22,23. Marc Gysin has shown that normal sequences do not exist for n = 24. So the first unsettled case is n = 27. Base sequences of lengths 2n - 1, 2n - 1. n. n are constructed for all decompositions of 6n - 2 into four squares for n = 2.4.6 ..... 20 and some base sequences for n = 22.24 are also given. So T-sequences (T-matrices) of length 71 are constructed here …

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New Results With Near- Yang Sequences, Marc Gysin, Jennifer Seberry Jan 1994

New Results With Near- Yang Sequences, Marc Gysin, Jennifer Seberry

Faculty of Informatics - Papers (Archive)

We construct new TW -sequences, weighing matrices and orthogonal designs using near-Yang sequences. In particular we construct new OD(60(2m + 1) + 4t; 13(2m+ 1), 13(2m+ 1), 13(2m+ 1), 13(2m+ 1) and new W(60(2m+ 1) + 4t; 13s(2m+ 1))for all t ≥ O, m ≤ 30, s = 1,2,3,4.

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A Note On Small Defining Sets For Some Sbibd(4t-1, 2t-1, T-1), Dinesh Sarvate, Jennifer Seberry Jan 1994

A Note On Small Defining Sets For Some Sbibd(4t-1, 2t-1, T-1), Dinesh Sarvate, Jennifer Seberry

Faculty of Informatics - Papers (Archive)

We conjecture that p specified sets of p elements are enough to define an SBIBD(2p+ l,p,(p - 1)/2) when p ≡ 1(mod 4) is a prime or prime power. This means in these cases p rows are enough to uniquely define the Hadamard matrix of order 2p + 2. We show that the p specified sets can be used to first find the residual BIBD(p + 1,2p,p,(p + 1)/2,(p - 1)/2) for p prime or prime power. This can then be used to uniquely complete the SBIBD for p = 5,9,13 and 17. This is another case where a residual …

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