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Articles 1 - 24 of 24

Full-Text Articles in Social and Behavioral Sciences

Integer-Modulated Filter Banks Providing Perfect Reconstruction, Alfred Mertins, Tanja Karp, Jorg Kliewer Jan 2000

Integer-Modulated Filter Banks Providing Perfect Reconstruction, Alfred Mertins, Tanja Karp, Jorg Kliewer

Faculty of Engineering and Information Sciences - Papers: Part A

In this paper, we extend the perfect reconstruction conditions known for cosine modulation to other, more general modulation schemes. The modified PR conditions provide additional degrees of freedom which can be utilized to design integer-modulated filter banks. Techniques for the design of prototypes and modulation sequences are presented.


The C*-Algebras Of Infinite Graphs, Neal J. Fowler, Marcelo Laca, Iain Raeburn Jan 2000

The C*-Algebras Of Infinite Graphs, Neal J. Fowler, Marcelo Laca, Iain Raeburn

Faculty of Engineering and Information Sciences - Papers: Part A

We associate C*-algebras to infinite directed graphs that are not necessarily locally finite. By realizing these algebras as Cuntz-Krieger algebras in the sense of Exel and Laca, we are able to give criteria for their uniqueness and simplicity, generalizing results of Kumjian, Pask, Raeburn, and Renault for locally finite directed graphs.


The Effect Of Different Rotation Patterns On The Revisions Of Trend Estimates, David G. Steel, Craig H. Mclaren Jan 2000

The Effect Of Different Rotation Patterns On The Revisions Of Trend Estimates, David G. Steel, Craig H. Mclaren

Faculty of Engineering and Information Sciences - Papers: Part A

The X11 and X11ARIMA procedures are widely used to produce seasonally adjusted and trend estimates from time series obtained from sample surveys. The surveys are often based on designs in which there is sample overlap between different periods. The degree of overlap is determined by the pattern of inclusion of selected units over time, i.e., the rotation pattern. An important issue in analysing the series is that trend estimates at the end of the series are revised as estimates for recent periods are added. This article considers the effects of different rotation patterns on the mean squared error of ...


Slope Instability, Hazard And Risk Associated With A Rainstorm Event - A Case Study, Phillip N. Flentje, Robin N. Chowdhury Jan 2000

Slope Instability, Hazard And Risk Associated With A Rainstorm Event - A Case Study, Phillip N. Flentje, Robin N. Chowdhury

Faculty of Engineering and Information Sciences - Papers: Part A

Over the last few decades there has been an increasing awareness of landslide hazard and risk in many coastal regions of Australia. Urban communities in hilly areas are, from time to time, adversely affected by rainfall-induced landsliding. However, acute awareness of hazard may be absent during periods between significant rainstorm events. In general, the serious consequences of landslides to property and life have been underestimated in Australia. It is now known that at least 80 deaths can be attributed to a number of landslides (Leiba, 1998). Some of these events have focussed the attention of the public, the most important ...


The Method Of Generalised Conditional Symmetries And Its Various Implementations, Joanna Goard Jan 2000

The Method Of Generalised Conditional Symmetries And Its Various Implementations, Joanna Goard

Faculty of Engineering and Information Sciences - Papers: Part A

We relate Kaptsov's method of B-determining equations for finding invariant solutions of PDEs to the nonclassical method and to the method of generalised conditional symmetries. An extension of Kaptsov's method is then used to find new solutions of degenerate diffusion equations.


Toward A Heuristic Optimum Design Of Rolling Schedules For Tandem Cold Rolling Mills, Dadong Wang, A Kiet Tieu, Friso Deboer, B Ma, W. Y. Daniel Yuen Jan 2000

Toward A Heuristic Optimum Design Of Rolling Schedules For Tandem Cold Rolling Mills, Dadong Wang, A Kiet Tieu, Friso Deboer, B Ma, W. Y. Daniel Yuen

Faculty of Engineering and Information Sciences - Papers: Part A

Scheduling for tandem cold mills refers to the determination of inter-stand gauges, tensions and speeds of a specified product. Optimal schedules should result in maximized throughput and minimized operating cost. This paper presents a genetic algorithm based optimization procedure for the scheduling of tandem cold rolling mills. The optimization procedure initiates searching from a logical staring point - an empirical rolling schedule - and ends with an optimum cost. Cost functions are constructed to heuristically direct the genetic algorithm's searching, based on the consideration of power distribution, tension, strip flatness and rolling constraints. Numerical experiments have shown that the proposed method ...


Induced C*-Algebras, Coactions And Equivariance In The Symmetric Imprimitivity Theorem, Siegfried Echterhoff, Iain Raeburn Jan 2000

Induced C*-Algebras, Coactions And Equivariance In The Symmetric Imprimitivity Theorem, Siegfried Echterhoff, Iain Raeburn

Faculty of Engineering and Information Sciences - Papers: Part A

The symmetric imprimitivity theorem provides a Morita equivalence between two crossed products of induced C*-algebras and includes as special cases many other important Morita equivalences such as Green's imprimitivity theorem. We show that the symmetric imprimitivity theorem is compatible with various inflated actions and coactions on the crossed products.


Developments In Blast Furnace Process Control At Port Kembla Based On Process Fundamentals, Robert Nightingale, Rian Dippenaar, Wei-Kao Lu Jan 2000

Developments In Blast Furnace Process Control At Port Kembla Based On Process Fundamentals, Robert Nightingale, Rian Dippenaar, Wei-Kao Lu

Faculty of Engineering and Information Sciences - Papers: Part A

This article is based on a presentation made in the "Geoffrey Belton Memorial Symposium," held in January 2000, in Sydney, Australia, under the joint sponsorship of ISS and TMS.


The Kth-Order Nonhomomorphicity Of S-Boxes, Yuliang Zheng, Xian-Mo Zhang Jan 2000

The Kth-Order Nonhomomorphicity Of S-Boxes, Yuliang Zheng, Xian-Mo Zhang

Faculty of Engineering and Information Sciences - Papers: Part A

Nonhomomorphicity is a new nonlinearity criterion of a mapping or S-box used in a private key encryption algorithm. An important advantage of nonhomomorphicity over other nonlinearity criteria is that the value of nonhomomorphicity is easy to estimate by the use of a fast statistical method. Due to the Law of Large Numbers, such a statistical method is highly reliable. Major contributions of this paper are (1) to explicitly express the nonhomomorphicity by other nonlinear characteristics, (2) to identify tight upper and lower bounds on nonhomomorphicity, and (3) to find the mean of nonhomomorphicity over all the S-boxes with the same ...


Influence Of In-Plane Displacement And Double-Aperture Orientation On Slope Fringe Formation In Double-Shearing-Aperture Speckle Interferometry, K F. Wang, A Kiet Tieu, Enbang Li Jan 2000

Influence Of In-Plane Displacement And Double-Aperture Orientation On Slope Fringe Formation In Double-Shearing-Aperture Speckle Interferometry, K F. Wang, A Kiet Tieu, Enbang Li

Faculty of Engineering and Information Sciences - Papers: Part A

The influence of the in-plane displacement and double-aperture orientation on the slope fringe formation in double-shearing-aperture speckle interferometry is discussed in detail. The research results show that the two in-plane displacement components, one parallel to and the other perpendicular to the shearing direction, have an influence on the slope fringe formation and that the double-aperture orientation also has an important influence on the slope fringe formation. A theoretical analysis and experimental results are presented. The experimental results are in good agreement with the theoretical analysis.


The C*-Algebras Of Row-Finite Graphs, Teresa Bates, David Pask, Iain Raeburn, Wojciech Szymanski Jan 2000

The C*-Algebras Of Row-Finite Graphs, Teresa Bates, David Pask, Iain Raeburn, Wojciech Szymanski

Faculty of Engineering and Information Sciences - Papers: Part A

We prove versions of the fundamental theorems about Cuntz-Krieger algebras for the C*-algebras of row-finite graphs: directed graphs in which each vertex emits at most finitely many edges. Special cases of these results have previously been obtained using various powerful machines; our main point is that direct methods yield sharper results more easily.


Fuelling Quasars With Hot Gas, Paul E J Nulsen, A C. Fabian Jan 2000

Fuelling Quasars With Hot Gas, Paul E J Nulsen, A C. Fabian

Faculty of Engineering and Information Sciences - Papers: Part A

We consider a model for quasar formation in which massive black holes are formed and fuelled largely by the accretion of hot gas during the process of galaxy formation. In standard hierarchical collapse models, objects about the size of normal galaxies and larger form a dense hot atmosphere when they collapse. We show that if such an atmosphere forms a nearly ‘maximal’ cooling flow, then a central black hole can accrete at close to its Eddington limit. This leads to exponential growth of a seed black hole, resulting in a quasar in some cases. In this model, the first quasars ...


A Physical Model For The Hard X-Ray Background, R J. Wilman, A C. Fabian, Paul E J Nulsen Jan 2000

A Physical Model For The Hard X-Ray Background, R J. Wilman, A C. Fabian, Paul E J Nulsen

Faculty of Engineering and Information Sciences - Papers: Part A

We combine a semi-analytic galaxy formation model with a prescription for the obscured growth of massive black holes, to reproduce the hard X-ray background (XRB), the local 2–10 keV active galactic nuclei (AGN) luminosity function and the source counts, including recent Chandra results. The model also complies with constraints on the AGN contribution to the far-infrared and submillimetre backgrounds.

The comoving density of luminous AGN [L(2-10keV) > 1044 erg s-1, in the unabsorbed rest-frame] in the model declines sharply since z=2, mimicking the observed evolution of the quasar population. The abundance of lower luminosity AGN simultaneously ...


Non-Gravitational Heating In The Hierarchical Formation Of X-Ray Clusters, K K S Wu, A C. Fabian, Paul E J Nulsen Jan 2000

Non-Gravitational Heating In The Hierarchical Formation Of X-Ray Clusters, K K S Wu, A C. Fabian, Paul E J Nulsen

Faculty of Engineering and Information Sciences - Papers: Part A

The strong deviation in the properties of X-ray clusters from simple scaling laws highlights the importance of non-gravitational heating and cooling processes in the evolution of protocluster gas. We investigate this from two directions: by finding the amount of ‘excess energy’ required in intracluster gas in order to reproduce the observed X-ray cluster properties, and by studying the excess energies obtained from supernovae in a semi-analytic model of galaxy formation. Using the insights obtained from the model, we then critically discuss possible ways of achieving the high excess specific energies required in clusters. These include heating by supernovae and active ...


Convergence Of Eigenvalues In State-Discretization Of Linear Stochastic Systems, Jose A. De Dona, Graham C. Goodwin, Richard H. Middleton, Iain Raeburn Jan 2000

Convergence Of Eigenvalues In State-Discretization Of Linear Stochastic Systems, Jose A. De Dona, Graham C. Goodwin, Richard H. Middleton, Iain Raeburn

Faculty of Engineering and Information Sciences - Papers: Part A

The transition operator that describes the time evolution of the state probability distribution for continuous-state linear systems is given by an integral operator. A state-discretization approach is proposed, which consists of a finite rank approximation of this integral operator. As a result of the state-discretization procedure, a Markov chain is obtained, in which case the transition operator is represented by a transition matrix. Spectral properties of the integral operator for the continuous-state case are presented. The relationships between the integral operator and the finite rank approximation are explored. In particular, the limiting properties of the eigenvalues of the transition matrices ...


Simulated Annealing With An Optimal Fixed Temperature, Mark James Fielding Jan 2000

Simulated Annealing With An Optimal Fixed Temperature, Mark James Fielding

Faculty of Engineering and Information Sciences - Papers: Part A

Contrary to conventional belief, it turns out that in some problem instances of moderate size, fixed temperature simulated annealing algorithms based on a heuristic formula for determining the optimal temperature can be superior to algorithms based on cooling. Such a heuristic formula, however, often seems elusive. In practical cases considered we include instances of traveling salesman, quadratic assignment, and graph partitioning problems, where we obtain results that compare favorably to the ones known in the literature.


The Berry-Esseen Bound For Studentized Statistics, Qiying Wang, Bing-Yi Jing, Lincheng Zhao Jan 2000

The Berry-Esseen Bound For Studentized Statistics, Qiying Wang, Bing-Yi Jing, Lincheng Zhao

Faculty of Engineering and Information Sciences - Papers: Part A

We derive Berry-Esseen bounds for a class of Studentized statistics. The results are applied to Studentized U-statistics, Studentized L-statistics and Studentized functions of the sample mean to give the Berry-Esseen bounds under conditions weaker than those obtained by alternative methods.


An Equivariant Brauer Semigroup And The Symmetric Imprimitivity Theorem, Astrid An Huef, Iain Raeburn, Dana Williams Jan 2000

An Equivariant Brauer Semigroup And The Symmetric Imprimitivity Theorem, Astrid An Huef, Iain Raeburn, Dana Williams

Faculty of Engineering and Information Sciences - Papers: Part A

No abstract provided.


Expedited Broda-Damas Bracket Abstraction, Martin W. Bunder Jan 2000

Expedited Broda-Damas Bracket Abstraction, Martin W. Bunder

Faculty of Engineering and Information Sciences - Papers: Part A

A bracket abstraction algorithm is a means of translating λ-terms into combinators. Broda and Damas, in [1], introduce a new, rather natural set of combinators and a new form of bracket abstraction which introduces at most one combinator for each λ-abstraction. This leads to particularly compact combinatory terms. A disadvantage of their abstraction process is that it includes the whole Schonfinkel [4] algorithm plus two mappings which convert the Schonfinkel abstract into the new abstract. This paper shows how the new abstraction can be done more directly, in fact, using only 2n - 1 algorithm steps if there are n occurrences ...


Specific Yield For A Two-Dimensional Flow, Peter Tritscher, W Wayne Read, Philip Broadbridge Jan 2000

Specific Yield For A Two-Dimensional Flow, Peter Tritscher, W Wayne Read, Philip Broadbridge

Faculty of Engineering and Information Sciences - Papers: Part A

We investigate the systematic secular spatial variation of specific yield. As a vehicle for this analysis we consider a canonical unconfined aquifer consisting of a porous zone whose cross section is a simple long rectangle. The hydraulic conductivity in the unsaturated zone is modeled by the quasi-linear approximation. We find that locally the specific yield may be strongly influenced by the water table depth and mildly dependent on the recharge rate if that rate is high. For the simple geometry considered, a lateral component of flow has been found to have an insignificant effect on the local specific yield and ...


Naturality And Induced Representations, Siegfried Echterhoff, S Kaliszewski, John Quigg, Iain Raeburn Jan 2000

Naturality And Induced Representations, Siegfried Echterhoff, S Kaliszewski, John Quigg, Iain Raeburn

Faculty of Engineering and Information Sciences - Papers: Part A

We show that induction of covariant representations for C*-dynamical systems is natural in the sense that it gives a natural transformation between certain crossed-product functors. This involves setting up suitable categories of C*-algebras and dynamical systems, and extending the usual constructions of crossed products to define the appropriate functors. From this point of view, Green's Imprimitivity Theorem identifies the functors for which induction is a natural equivalence. Various special cases of these results have previously been obtained on an ad hoc basis.


Network Reconfiguration For Enhancement Of Voltage Stability In Distribution Networks, Kashem M. Muttaqi, Velappa Ganapathy, G G. Jasmon Jan 2000

Network Reconfiguration For Enhancement Of Voltage Stability In Distribution Networks, Kashem M. Muttaqi, Velappa Ganapathy, G G. Jasmon

Faculty of Engineering and Information Sciences - Papers: Part A

Network reconfiguration is performed by altering the topological structure of distribution feeders. By reconfiguring the network, voltage stability can be maximised for a particular set of loads in distribution systems. A new algorithm is formulated for enhancement of voltage stability by network reconfiguration. Initially, a certain number of switching combinations is generated using the combination of tie and its two neighbouring switches, and the best combination of switches for maximising the voltage stability in the network among them is determined. Then the search is extended by considering the branches next to the open-branches of the best configuration one by one ...


A Geometric Approach For Three-Phase Load Balancing In Distribution Networks, Kashem M. Muttaqi, Velappa Ganapathy, G B. Jasmon Jan 2000

A Geometric Approach For Three-Phase Load Balancing In Distribution Networks, Kashem M. Muttaqi, Velappa Ganapathy, G B. Jasmon

Faculty of Engineering and Information Sciences - Papers: Part A

No abstract provided.


A Novel Method For Loss Minimization In Distribution Networks, Kashem M. Muttaqi, Velappa Ganapathy, G B. Jasmon, M Buhari Jan 2000

A Novel Method For Loss Minimization In Distribution Networks, Kashem M. Muttaqi, Velappa Ganapathy, G B. Jasmon, M Buhari

Faculty of Engineering and Information Sciences - Papers: Part A

Network reconfiguration for loss minimization is the determination of switching-options that minimizes the power losses for a particular set of loads on a distribution system. In this paper, a novel method is proposed by formulating an algorithm to reconfigure distribution networks for loss minimization. An efficient technique is used to determine the switching combinations, select the status of the switches, and find the best combination of switches for minimum loss. In the first stage of the proposed algorithm, a limited number of switching combinations is generated and the best switching combination is determined. In the second stage, an extensive search ...