Social and Behavioral Sciences Commons^™

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 …

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.

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.

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.

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 …

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.

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.

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

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 …

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 …

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 …

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

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.

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

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 increases, and …

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 …

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.

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 …

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 …

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.

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.

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 the …

Simulated Annealing: Searching For An Optimal Temperature Schedule, Harry Cohn, Mark James Fielding

Faculty of Engineering and Information Sciences - Papers: Part A

A sizable part of the theoretical literature on simulated annealing deals with a property called convergence, which asserts that the simulated annealing chain is in the set of global minimum states of the objective function with probability tending to 1. However, in practice, the convergent algorithms are considered too slow, whereas a number of nonconvergent ones are usually preferred. We attempt a detailed analysis of various temperature schedules. Examples will be given of when it is both practically and theoretically justified to use boiling, fixed temperature, or even fast cooling schedules which have a small probability of reaching global minima. …

Magnetic Circuit Of A Synchronous Reluctance Motor, P P. Ciufo, D. Platt, B S. P Perera

Faculty of Engineering and Information Sciences - Papers: Part A

This paper presents a model of the magnetic circuit for an axially laminated synchronous reluctance motor. The basis of the modelling technique is the determination of a value for an equivalent ``q-channel'' reluctance. This reluctance contains all the effects of paths available to q-axis flux through the rotor body. Expressions for the distribution of airgap and other motor fluxes have been developed from basic analyses involving mmf and continuity of flux. The foundations of all of these expressions are the physical parameters of the motor. The equations developed have been applied to a 370 W motor and the results from …

Quantitative Landslide Hazard Assessment In An Urban Area, Phillip N. Flentje, Robin N. Chowdhury

Faculty of Engineering and Information Sciences - Papers: Part A

Before decisions can be made concerning the management of sloping areas subject to landsliding, systematic approaches for hazard and risk assessment must be developed. This paper is limited to a discussion of hazard assessment and describes quantitative approaches which have been developed for existing landslides. Consideration of areas of potential landsliding is outside the scope of the paper. The approach described here is based on (a) monitoring of subsurface shear movement at instrumented sites and (b) the percentage exceedance time of cumulative rainfalls considering different selected periods of antecedent rainfall. This approach is used in conjunction with a simpler approach, …

Landslide Risk Assessment - Development Of A Hazard Consequence Approach, Chit Ko Ko, Phillip N. Flentje, Robin N. Chowdhury

Faculty of Engineering and Information Sciences - Papers: Part A

Several Landslide Hazard and Risk Assessment methods have been developed and used in the State of New South Wales (NSW), Australia. The Rail Services Australia Geotechnical Services and the Roads and Traffic Authority of NSW have each developed Risk Assessment procedures suitable to their own specific needs. A generic risk management methodology is presented in the Australian Standard/New Zealand Standard (AS/NZS) 4360:1995. An approach similar to the (AS/NZS) 4360:1995 Risk Management Standard has been applied by a NSW State Emergency Services geotechnical team (which included one of the writers) to 191 problem sites in the Wollongong Area, following a major …

Network Reconfiguration For Load Balancing In Distribution Networks, Kashem M. Muttaqi, Velappa Ganapathy, G G. Jasmon

Faculty of Engineering and Information Sciences - Papers: Part A

Network reconfiguration of a power distribution system is an operation to alter the topological structure of distribution feeders by changing opedclosed status of sectionalising and tie switches. By transferring loads from the heavily loaded feeders to the lightly loaded ones, network reconfiguration can balance feeder loads and alleviate overload conditions of a network. The branch load-balancing index and the overall system load-balancing index are used to determine the loading conditions of the system and maximum system loading capacity. The index value has to be minimum in the optimal configuration of load balancing. For optimal load balancing condition the branch load-balancing …

Instrumentation For Slope Stability - Experience From An Urban Area, P N. Flentje, R N. Chowdhury

Faculty of Engineering and Information Sciences - Papers: Part A

This paper describes the monitoring of several existing landslides in an urban area near Wollongong in the state of New South Wales, Australia. A brief overview of topography and geology is given and reference is made to the types of slope movement, processes and causal factors. Often the slope movements are extremely slow and imperceptible to the eye, and catastrophic failures are quite infrequent. However, cumulative movements at these slower rates do, over time, cause considerable distress to structures and disrupt residential areas and transport routes. Inclinometers and piezometers have been installed at a number of locations and monitoring of …

Consideration Of Probability Assessments Relevant To Hazard And Risk For Landslides, R N. Chowdhury, P N. Flentje

Faculty of Engineering and Information Sciences - Papers: Part A

Probability of occurrence is the most important component of landslide hazard and risk and this paper outlines different approaches for its assessment. The reasons for the popularity of qualitative approaches are first outlined. Quantitative approaches can be best applied if the important influencing factors and issues are fully understood. Formal probabilistic approaches are often based on geotechnical models or on a combination of hydrological and geotechnical models. The paper also highlights the situations for which the performance function must be formulated in terms of lateral displacements rather than the conventional safety factor. Reference is then made to a procedure, based …

Aspects Of Recent Landslide Research At The University Of Wollongong, Robin N. Chowdhury, Phillip N. Flentje, Chit Ko Ko

Faculty of Engineering and Information Sciences - Papers: Part A

This paper introduces the issues which are of critical importance to landslide hazard and risk assessment and management. These include understanding of probability and consequence, the separation of the role of site-dependent factors from that of influencing/triggering natural events and the factors influencing target levels of risk. The research completed at the University of Wollongong is then outlined. This includes the development of an observational approach based on monitoring of subsurface movements at individual sites and appropriate use of rainfall data in terms of the concept of annual rainfall percentage exceedance time (ARPET). Attention is then focused on current research …