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Full-Text Articles in Social and Behavioral Sciences

An Adaptive Channel Tracking Method For Mimo- Ofdm Systems, Jun Tong, Yaohuan Gong, Shengxian Sun Jan 2004

An Adaptive Channel Tracking Method For Mimo- Ofdm Systems, Jun Tong, Yaohuan Gong, Shengxian Sun

Faculty of Engineering and Information Sciences - Papers: Part A

The tracking of the time-varying channel is crucial for MIMO-OFDM wireless communication systems. Aiming at doubly-selective fading MIMO channels, we present a novel pilot pattern and the corresponding adaptive channel tracking algorithm. Compared with the traditional pilot patterns, the new pattern has higher frequency efficiency and is more suitable for large transmit arrays. The computational complexity, frequency efficiency and BER performance of the system assisted by the proposed channel tracking scheme are analyzed. Simulation results demonstrate that the proposed scheme can track the timevarying channel effectively


A Note On Devaney's Definition Of Chaos, Joseph Tonien Jan 2004

A Note On Devaney's Definition Of Chaos, Joseph Tonien

Faculty of Engineering and Information Sciences - Papers: Part A

Devaney defines a function to be chaotic if it satisfies three conditions: transitivity, having dense set of periodic points and sensitive dependence on initial conditions. Banks et al prove that if the function is continuous then the third conditioin is implied from the first two and therefore is redundant. However, if the function is not assumed to be continuous, then it is not known if the third condition is redundant or not.

In this note, without assuming the function is continuous, we prove that the third condition is redundant if the underlying topological space is not precompact.


Linear Code Implies Publicf-Key Traitor Tracing With Revocation, Joseph Tonien, Rei Safavi-Naini Jan 2004

Linear Code Implies Publicf-Key Traitor Tracing With Revocation, Joseph Tonien, Rei Safavi-Naini

Faculty of Engineering and Information Sciences - Papers: Part A

In this paper, we show that the linear-coded Kurosawa–Desmedt scheme can be modified to allow revocation of users, that is to show a revocation scheme can be derived from a linear code.


Using Self-Regulated Learning To Manage The Discomfort Of Becoming Fluent With Information Technology, Victoria M. Neville, Sue Bennett Jan 2004

Using Self-Regulated Learning To Manage The Discomfort Of Becoming Fluent With Information Technology, Victoria M. Neville, Sue Bennett

Faculty of Engineering and Information Sciences - Papers: Part A

The technologically complex and changing world of the twenty first century requires teachers who are both knowledgeable and skilled in using information technology in their pedagogical practices. The changing nature of information technology means that teachers need to be flexible in how they use information technology in their teaching, adaptable to the changes in technological developments, problem solvers in unfamiliar circumstances, and continuing learners throughout their professional life. These ideas are encapsulated in the concept of fluency with information technology, or FITness (Committee on Information Technology Literacy, 1999). This research study, in progress, uses an interpretive, qualitative methodological approach to ...


Community Technology Centres: A Proposed Framework For Sustainability, William J. Tibben, Carole A. Alcock Jan 2004

Community Technology Centres: A Proposed Framework For Sustainability, William J. Tibben, Carole A. Alcock

Faculty of Engineering and Information Sciences - Papers: Part A

The effectiveness of Community Technology Centres (CTCs) in meeting many of the challenges presented by the digital divide invites a closer scrutiny of factors that contribute to their sustainability. The success of CTCs appears to be related to the way in which these initiatives are able to respond to the multifaceted nature of the digital divide problem. However, more systematic approaches are required to enable the identification of common factors that contribute to sustainability in different contexts. The paper responds to this challenge by initially reviewing recent contributions on the digital divide debate. From a more refined understanding of what ...


Energy Injection By Distributed Generation For Improvement In Feeder-Voltage Profile, Kashem M. Muttaqi, Gerard Ledwich Jan 2004

Energy Injection By Distributed Generation For Improvement In Feeder-Voltage Profile, Kashem M. Muttaqi, Gerard Ledwich

Faculty of Engineering and Information Sciences - Papers: Part A

No abstract provided.


Finite-Element Analysis To Determine Effect Of Monolimb Flexibility On Structural Strength And Interaction Between Residual Limb And Prosthetic Socket, Winson Lee, Ming Zhang, David A. Boone, Bill Contoyannis Jan 2004

Finite-Element Analysis To Determine Effect Of Monolimb Flexibility On Structural Strength And Interaction Between Residual Limb And Prosthetic Socket, Winson Lee, Ming Zhang, David A. Boone, Bill Contoyannis

Faculty of Engineering and Information Sciences - Papers: Part A

Monolimb refers to a kind of transtibial prostheses having the socket and shank molded into one piece of thermoplastic material. One of its characteristics is that the shank is made of a material that can deform during walking, which can simulate ankle joint motion to some extent. Changes in shank geometry can alter the stress distribution within the monolimb and at the residual limb-socket interface and, respectively, affect the deformability and structural integrity of the prosthesis and comfort perceived by amputees. This paper describes the development of a finite-element model for the study of the structural behavior of monolimbs with ...


Finite Element Modeling Of Contact Interface Between Trans-Tibial Residual Limb And Prosthetic Socket, Winson Lee, Ming Zhang, Xiaohong Jia, Jason Cheung Jan 2004

Finite Element Modeling Of Contact Interface Between Trans-Tibial Residual Limb And Prosthetic Socket, Winson Lee, Ming Zhang, Xiaohong Jia, Jason Cheung

Faculty of Engineering and Information Sciences - Papers: Part A

Finite element method has been identified as a useful tool to understand the load transfer mechanics between a residual limb and its prosthetic socket. This paper proposed a new practical approach in modeling the contact interface with consideration of the friction/slip conditions and pre-stresses applied on the limb within a rectified socket. The residual limb and socket were modeled as two separate structures and their interactions were simulated using automated contact methods. Some regions of the limb penetrated into the socket because of socket modification. In the first step of the simulation, the penetrated limb surface was moved onto ...


Load Transfer Mechanics Between Trans-Tibial Prosthetic Socket And Residual Limb-Dynamic Effects, Xiaohong Jia, Ming Zhang, Winson Lee Jan 2004

Load Transfer Mechanics Between Trans-Tibial Prosthetic Socket And Residual Limb-Dynamic Effects, Xiaohong Jia, Ming Zhang, Winson Lee

Faculty of Engineering and Information Sciences - Papers: Part A

The effects of inertial loads on the interface stresses between trans-tibial residual limb and prosthetic socket were investigated. The motion of the limb and prosthesis was monitored using a Vicon motion analysis system and the ground reaction force was measured by a force platform. Equivalent loads at the knee joint during walking were calculated in two cases with and without consideration of the material inertia. A 3D nonlinear finite element (FE) model based on the actual geometry of residual limb, internal bones and socket liner was developed to study the mechanical interaction between socket and residual limb during walking. To ...


Maple+Grtensorii Libraries For Cosmology, Dumitru N. Vulcanov, Valentina-Mira Wheeler Jan 2004

Maple+Grtensorii Libraries For Cosmology, Dumitru N. Vulcanov, Valentina-Mira Wheeler

Faculty of Engineering and Information Sciences - Papers: Part A

The article mainly presents some results in using MAPLE platform for com- puter algebra (CA) and GrTensorII package in doing calculations for theoretical and numerical cosmology.


The Limiting Ideal Theory For Shear-Index Cohesionless Granular Materials, Grant Cox, James Hill Jan 2004

The Limiting Ideal Theory For Shear-Index Cohesionless Granular Materials, Grant Cox, James Hill

Faculty of Engineering and Information Sciences - Papers: Part A

To model cohesionless granular flow using continuum theory, the usual approach is to assume the cohesionless Coulomb-Mohr yield condition. However, this yield condition assumes that the angle of internal friction is constant, when according to experimental evidence for most powders the angle of internal friction is not constant along the yield locus, but decreases for decreasing normal stress component σ from a maximum value of π/2. For this reason, we consider here the more general yield function which applies for shear-index granular materials, where the angle of internal friction varies with σ. In this case, failure due to frictional ...


Bifurcation Phenomena For An Oxidation Reaction In A Continuously Stirred Tank Reactor. Ii Diabatic Operation, Mark Nelson, Harvinder Sidhu Jan 2004

Bifurcation Phenomena For An Oxidation Reaction In A Continuously Stirred Tank Reactor. Ii Diabatic Operation, Mark Nelson, Harvinder Sidhu

Faculty of Engineering and Information Sciences - Papers: Part A

We extend an investigation into the bifurcation phenomena exhibited by an oxidation reaction in an adiabatic reactor to the case of a diabatic reactor. The primary bifurcation parameter is the fuel fraction; the inflow pressure and inflow temperature are the secondary bifurcation parameters. The inclusion of heat loss in the model does not change the static steady-state bifurcation diagram; the organising centre is a pitchfork singularity for both the adiabatic and diabatic reactors. However, unlike the adiabatic reactor, Hopf bifurcations may occur in the diabatic reactor. We construct the degenerate Hopf bifurcation curve by determining the double-Hopf locus. When the ...


An Investigation Into The Effects Of Heat Transfer On The Motion Of A Spherical Bubble, P J Harris, H Al-Awadi, Wee King Soh Jan 2004

An Investigation Into The Effects Of Heat Transfer On The Motion Of A Spherical Bubble, P J Harris, H Al-Awadi, Wee King Soh

Faculty of Engineering and Information Sciences - Papers: Part A

This paper investigates the effect of heat transfer on the motion of a spherical bubble in the vicinity of a rigid boundary. The effects of heat transfer between the bubble and the surrounding fluid, and the resulting loss of energy from the bubble, can be incorporated into the simple spherical bubble model with the addition of a single extra ordinary differential equation. The numerical results show that for a bubble close to an infiniterigid boundary there are significant differences in both the radius and Kelvin impulse of the bubble when the heat transfer effects are included.


Classification Theorems For The C*-Algebras Of Graphs With Sinks, Iain Raeburn, Mark Tomforde, Dana Williams Jan 2004

Classification Theorems For The C*-Algebras Of Graphs With Sinks, Iain Raeburn, Mark Tomforde, Dana Williams

Faculty of Engineering and Information Sciences - Papers: Part A

We consider graphs E which have been obtained by adding one or more sinks to a fixed directed graph G. We classify the C*-algebra of E up to a very strong equivalence relation, which insists, loosely speaking, that C*(G) is kept fixed. The main invariants are vectors WE: G0 → which describe how the sinks are attached to G; more precisely, the invariants are the classes of the WE in the cokernel of the map A – I, where A is the adjacency matrix of the graph G.


Reliability Of Higher Seeding Rates Of Wheat For Increased Competitiveness With Weeds In Low Rainfall Environments, D Lemerle, R D. Cousens, G S. Gill, S J. Peltzer, M Moerkerk, C E. Murphy, D Collins, Brian R. Cullis Jan 2004

Reliability Of Higher Seeding Rates Of Wheat For Increased Competitiveness With Weeds In Low Rainfall Environments, D Lemerle, R D. Cousens, G S. Gill, S J. Peltzer, M Moerkerk, C E. Murphy, D Collins, Brian R. Cullis

Faculty of Engineering and Information Sciences - Papers: Part A

Increasing crop competitiveness using higher seeding rates is a possible technique for weed management in low input and organic farming systems or when herbicide resistance develops in weeds. A range of wheat seeding rates were sown and resulted in crop densities between 50–400 plants/m2 (current recommendations are 100–150 plants/m2) in the presence and absence of annual ryegrass (Lolium rigidum Gaud.) in three wheat cultivars at nine experiments in southern Australia. Wheat densities of at least 200 plants/m2 were required to suppress L. rigidum and to a lesser extent increase crop yield across ...


Summability For Nonunital Spectral Triples, Adam C. Rennie Jan 2004

Summability For Nonunital Spectral Triples, Adam C. Rennie

Faculty of Engineering and Information Sciences - Papers: Part A

This paper examines the issue of summability for spectral triples for the class of nonunital algebras. For the case of (p, -) summability, we prove that the Dixmier trace can be used to define a (semifinite) trace on the algebra of the spectral triple. We show this trace is well-behaved, and provide a criteria for measurability of an operator in terms of zeta functions. We also show that all our hypotheses are satisfied by spectral triples arising from eodesically complete Riemannian manifolds. In addition, we indicate how the Local Index Theorem of Connes-Moscovici extends to our nonunital setting.


Dynamic Properties And Liquefaction Behavior Of Granular Materials Using Discrete Element Method, S V. Dinesh, T G. Sitharam, J S Vinod Jan 2004

Dynamic Properties And Liquefaction Behavior Of Granular Materials Using Discrete Element Method, S V. Dinesh, T G. Sitharam, J S Vinod

Faculty of Engineering and Information Sciences - Papers: Part A

Dynamic properties of the soil such as shear modulus and damping ratio are important parameters in the prediction of the dynamic response of geotechnical engineering structures. Though these properties are dependent on several factors, strain amplitude and confining pressure have a major effect. Liquefaction is another important phenomenon associated with the undrained response of granular materials in loose state. In this paper, the results of the numerical simulation of cyclic triaxial shear tests on three-dimensional assembly consisting of 1000 sphere particles using Discrete Element Method (DEM) have been reported under undrained conditions. From the results, the shear modulus and damping ...


Placement And Penetration Of Distributed Generation Under Standard Market Design, Ashish Agalgaonkar, S V. Kulkarni, S A. Khaparde, S A. Soman Jan 2004

Placement And Penetration Of Distributed Generation Under Standard Market Design, Ashish Agalgaonkar, S V. Kulkarni, S A. Khaparde, S A. Soman

Faculty of Engineering and Information Sciences - Papers: Part A

Distributed Generation (DG) can help in reducing the cost of electricity to the costumer, relieve network congestion and provide environmentally friendly energy close to load centers. Its capacity is also scalable and it provides voltage support at distribution level. Hence, DG placement and penetration level is an important problem for both the utility and DG owner. The cost of electricity as a commodity depends upon market model. The restructured power markets are slowly maturing with standardizations like Standard Market Design (SMD). The key feature of SMD is the Locational Marginal Pricing (LMP) scheme. This paper examines placement and penetration level ...


Study On The Mechanism Of The Squeeze-Strengthen Effect In Magnetorheological Fluids, Xianzhou Zhang, X L. Gong, P Q. Zhang, Q M. Wang Jan 2004

Study On The Mechanism Of The Squeeze-Strengthen Effect In Magnetorheological Fluids, Xianzhou Zhang, X L. Gong, P Q. Zhang, Q M. Wang

Faculty of Engineering and Information Sciences - Papers: Part A

Current magnetorheological (MR)fluids have the limitation that their yield stresses are not strong enough to meet some industrial requirements. X. Tang, X. Zhang, and R. Tao [J. App. Phys87, 2634 (2000)] proposed a method to achieve high-efficiency MR fluids by study of squeeze-strengthen effect. But there is little report on its mechanism. This paper aims to investigate this effect through experimental and theoretical approaches. For this purpose, an apparatus is designed to experimentally study the mechanism of this squeeze-strengthen effect. Taking account of a modified magnetic dipole model and the friction effect, a semiempirical model is proposed to explain ...


Smoothing With Mixed Model Software, Long Ngo, M P. Wand Jan 2004

Smoothing With Mixed Model Software, Long Ngo, M P. Wand

Faculty of Engineering and Information Sciences - Papers: Part A

Smoothing methods that use basis functions with penalization can be formulated as fits in a mixed model framework. One of the major benefits is that software for mixed model analysis can be used for smoothing. We illustrate this for several smoothing models such as additive and varying coefficient models for both S-PLUS and SAS software. Code for each of the illustrations is available on the Internet.


Effect Of Aging And Deformation On The Microstructure And Properties Of Fe-Ni-Ti Maraging Steel, A Shekhter, H I. Aaronson, M K. Miller, S P. Ringer, E V. Pereloma Jan 2004

Effect Of Aging And Deformation On The Microstructure And Properties Of Fe-Ni-Ti Maraging Steel, A Shekhter, H I. Aaronson, M K. Miller, S P. Ringer, E V. Pereloma

Faculty of Engineering and Information Sciences - Papers: Part A

The age-hardening behavior of Fe−25.3Ni−1.7 Ti (wt pct) alloy both in undeformed specimens and in specimens cold deformed by 10 or 20 pct prior to aging was studied. The microstructural changes during aging were observed using transmission electron microscopy (TEM) and atom probe analysis and there were related to the mechanical properties as measured by microhardness and shear punch testing. An excellent combination of hardness, strength, and ductility was achieved after only 5 seconds aging at 550°C. We propose that this rapid strengthening is due to a dislocation friction effect arising from the formation of ...


Effect Of Microstructure On The Stability Of Retained Austenite In Transformation-Induced-Plasiticity Steels, I B. Timokhina, P D. Hodgson, E V. Pereloma Jan 2004

Effect Of Microstructure On The Stability Of Retained Austenite In Transformation-Induced-Plasiticity Steels, I B. Timokhina, P D. Hodgson, E V. Pereloma

Faculty of Engineering and Information Sciences - Papers: Part A

Two Fe-0.2C-1.55Mn-1.5Si (in wt pct) steels, with and without the addition of 0.039Nb (in wt pct), were studied using laboratory rolling-mill simulations of controlled thermomechanical processing. The microstructures of all samples were characterized by optical metallography, X-ray diffraction (XRD), and transmission electron microscopy (TEM). The microstructural behavior of phases under applied strain was studied using a heat-tinting technique. Despite the similarity in the microstructures of the two steels (equal amounts of polygonal ferrite, carbide-free bainite, and retained austenite), the mechanical properties were different. The mechanical properties of these transformation-induced-plasticity (TRIP) steels depended not only on the ...


Widmanstatten Ferrite Plate Formation In Low-Carbon Steels, Dominic Phelan, Rian Dippenaar Jan 2004

Widmanstatten Ferrite Plate Formation In Low-Carbon Steels, Dominic Phelan, Rian Dippenaar

Faculty of Engineering and Information Sciences - Papers: Part A

The mechanism by which Widmanstätten ferrite plates nucleate and grow in low-carbon steels has been studied. In-situ laser scanning confocal microscopy (LSCM) observations, optical microscopy, and electron backscattered diffraction (EBSD) techniques have been used to characterize the relationship between grain boundary allotriomorphs and Widmanstätten ferrite plates. The issue of where Widmanstätten ferrite plates nucleate is one of some debate, with theories including morphological instability and sympathetic nucleation. Evidence has been found that supports the theory of a sympathetic nucleation mechanism being responsible for the formation of Widmanstätten ferrite plates. The EBSD measurements have shown that low-angle misorientations of between 5 ...


Role Of Cr And P Additions In The Development Of Microstructure And Texture In Annealed Low Carbon Steels, E V. Pereloma, I B. Timokhina, A I. Nosenkov, J J. Jonas Jan 2004

Role Of Cr And P Additions In The Development Of Microstructure And Texture In Annealed Low Carbon Steels, E V. Pereloma, I B. Timokhina, A I. Nosenkov, J J. Jonas

Faculty of Engineering and Information Sciences - Papers: Part A

The recrystallisation behaviour of four warm rolled steels was investigated during annealing. The extra-low carbon (ELC) steel displayed the highest rate of recrystallisation, the steels with additions of chromium and phosphorus (LC(Cr)), (LC(Cr,P)) recrystallised at intermediate rates, while the interstitial-free (IF) steel exhibited the lowest rate. The additions of Cr and Cr/P increased the fraction of g-fibre in the annealing textures compared to that present in the ELC steel; this effect was particularly pronounced up to 50 % recrystallisation. After the completion of recrystallisation, the steel textures were characterized by a dominant g-fibre in the IF steel ...


Massive Increase In The Stiffness Of The Human Lens Nucleus With Age: The Basis For Presbyopia?, Karl Robert Heys, Sandra Leigh Cram, Roger J W Truscott Jan 2004

Massive Increase In The Stiffness Of The Human Lens Nucleus With Age: The Basis For Presbyopia?, Karl Robert Heys, Sandra Leigh Cram, Roger J W Truscott

Faculty of Engineering and Information Sciences - Papers: Part A

Purpose: To determine the stiffness of different regions of human lenses as a function of age, and to correlate the biophysical measurements in the lens center with nuclear water content.

Methods: A custom made probe fitted to a dynamic mechanical analyzer was employed to measure stiffness values at 1 mm increments across equatorial sections of individual human lenses. Thermogravimetric analysis was used to determine the percentage water content in the nuclei of human lenses.

Results: There was a pronounced increase in lens stiffness over the age range from 14 to 78. In the nucleus, stiffness values varied almost 1,000 ...


On A Heat Problem Involving The Perturbed Hardy-Sobolev Operator, Nirmalendu Chaudhuri, Kunnath Sandeep Jan 2004

On A Heat Problem Involving The Perturbed Hardy-Sobolev Operator, Nirmalendu Chaudhuri, Kunnath Sandeep

Faculty of Engineering and Information Sciences - Papers: Part A

No abstract provided.


Mansfield's Imprimitivity Theorem For Arbitrary Closed Subgroups, Astrid An Huef, Iain Raeburn Jan 2004

Mansfield's Imprimitivity Theorem For Arbitrary Closed Subgroups, Astrid An Huef, Iain Raeburn

Faculty of Engineering and Information Sciences - Papers: Part A

No abstract provided.


Cuntz-Krieger Algebras Of Infinite Graphs And Matrices, Iain Raeburn, Wojciech Szymanski Jan 2004

Cuntz-Krieger Algebras Of Infinite Graphs And Matrices, Iain Raeburn, Wojciech Szymanski

Faculty of Engineering and Information Sciences - Papers: Part A

We show that the Cuntz-Krieger algebras of infinite graphs and infinite {0,1}-matrices can be approximated by those of finite graphs. We then use these approximations to deduce the main uniqueness theorems for Cuntz-Krieger algebras and to compute their K-theory. Since the finite approximating graphs have sinks, we have to calculate the K-theory of Cuntz-Krieger algebras of graphs with sinks, and the direct methods we use to do this should be of independent interest.


Estimation Of Diffusion Coefficients, Lateral Shear Stress, And Velocity In Open Channels With Complex Geometry, Shu-Qing Yang, Jian-Xing Yu, Yuan-Zhan Wang Jan 2004

Estimation Of Diffusion Coefficients, Lateral Shear Stress, And Velocity In Open Channels With Complex Geometry, Shu-Qing Yang, Jian-Xing Yu, Yuan-Zhan Wang

Faculty of Engineering and Information Sciences - Papers: Part A

The lateral distributions of depth-averaged apparent shear stress, depth mean velocity, and diffusion coefficients are essential in certain quantitative analysis for sediment transport and environmental studies. An analytical method for the computation of these parameters is presented. A mathematical relationship between these parameters, based on the concept of surplus energy transport through a minimum relative distance developed by Yang and Lim [1997], is established, the depth-averaged apparent shear stress is determined from the boundary shear stress, depth mean velocity is obtained by considering the influence of nonuniform shear velocity and the free surface in 3-D channels, and the diffusion coefficients ...


A Systematic Study Of Radio-Induced X-Ray Cavities In Clusters, Groups, And Galaxies, L Birzan, D A. Rafferty, B R. Mcnamara, M W. Wise, Paul E. J Nulsen Jan 2004

A Systematic Study Of Radio-Induced X-Ray Cavities In Clusters, Groups, And Galaxies, L Birzan, D A. Rafferty, B R. Mcnamara, M W. Wise, Paul E. J Nulsen

Faculty of Engineering and Information Sciences - Papers: Part A

We present an analysis of 16 galaxy clusters, one group, and one galaxy drawn from the Chandra Data Archive. These systems possess prominent X-ray surface brightness depressions associated with cavities or bubbles that were created by interactions between powerful radio sources and the surrounding hot gas. The central galaxies in these systems harbor radio sources with luminosities ranging between ∼2 × 10 38 and 7 × 10 44 ergs s -1. The cavities have an average radius of ∼10 kpc, and they lie at an average projected distance of ∼20 kpc from the central galaxy. The minimum energy associated with the cavities ...