Physical Sciences and Mathematics Commons^™

Vulnerability Assessment Of A Large Sized Power System Considering A New Index Based On Power System Loss, Ahmed M. Haidar, Azah Mohamed, Aini Hussain

Faculty of Informatics - Papers (Archive)

The concept of power system vulnerability assessment combines information on the level of system security as well as information on a wide range of situations, events and contingencies with regards to which a system is vulnerable. This paper attempts to investigate and evaluate the effect of line outage, generation outage and amount of load disconnected on the power transmission network losses of a large size power system. These effects will be investigated and evaluated using new proposed method based on vulnerability index of power system loss. The objectives of this work is to evaluate and compare the efficiency of the …

Data Mining Of Misr Aerosol Product Using Spatial Statistics, Tao Shi, Noel A. Cressie

Faculty of Informatics - Papers (Archive)

In climate models, aerosol forcing is the major source of uncertainty in climate forcing, over the industrial period. To reduce this uncertainty, instruments on satellites have been put in place to collect global data. However, missing and noisy observations impose considerable difficulties for scientists researching global aerosol distribution, aerosol transportation, and comparisons between satellite observations and global-climate-model outputs. In this paper, we propose a Spatial Mixed Effects (SME) statistical model to predict the missing values, denoise the observed values, and quantify the spatial-prediction uncertainties. The computations associated with the SME model are linear scalable to the number of data points, …

Query Streaming For Multimedia Query By Content From Mobile Devices, Kevin Adistambha, S. J. Davis, Christian H. Ritz, I. Burnett

Faculty of Informatics - Papers (Archive)

Formulating and processing of multimedia queries using mobile devices presents many challenges. This is due to the limitations of the devices themselves and the cost of the bandwidth involved in transmitting multimedia data between servers and devices. In this paper we propose a novel approach: “query streaming” which uses Reverse Polish Notation to perform multimedia query-by-example on a mobile device and server. An important advantage of query streaming is the ability to perform a query within the previous result set. To solve the problem of limited resources, the concept of result set examination using Fragment Request Units and Fragment Update …

E-Government Evaluation: A User-Centric Perspective For Public Value Proposition, Akemi Takeoka Chatfield, Omar Alhujran

Faculty of Informatics - Papers (Archive)

Academic research and institutional reports present evidence of e-government project failures and stalled or cancelled initiatives. Prior research concludes that e-government evaluation is under developed and calls for improving egovernment evaluation practice. Stages of growth models have been used in IS research and more recently in e-government research. While egovernment stage models provide potentially useful tools for e-government evaluation, there are different e-government stage models that are sometimes contradictory in development stages and perspectives. Drawing on the concept of public value proposition, this research surveys existing egovernment stage models from a user-centric perspective and develops a user-centric, demandside model that …

Creating Mathematical Learning Resources - Combining Audio And Visual Components, Elahe Aminifar, Anne Porter, R. Caladine, Mark Nelson

Faculty of Informatics - Papers (Archive)

Students commencing science and engineering degrees at the Uni-versity of Wollongong are given mathematics skills tests in the first and fourth weeks of session. An evaluation of the results from these tests indicate that the majority of students' basic mathematical skills were insufficient to adequately support the prescribed first year math-ematics curriculum. To address this problem a pilot study was set up to develop video solutions. These solutions permit students to see the development of each solution in a step-by-step manner. An audio Contents C935 commentary on each worked solution assists learning by providing stu-dents with an explanation of the …

Modulation Solutions For Nematicon Propagation In Non-Local Liquid Crystals, Antonmaria Minzoni, Noel Smyth, Annette L. Worthy

Faculty of Informatics - Papers (Archive)

The propagation of solitary waves, so-called nematicons, in a nonlinear nematic liquid crystal is considered in the nonlocal regime. Approximate modulation equations governing the evolution of input beams into steady nematicons are derived by using suitable trial functions in a Lagrangian formulation of the equations for a nematic liquid crystal. The variational equations are then extended to include the effect of diffractive loss as the beam evolves. It is found that the nonlocal nature of the interaction between the light and the nematic has a significant effect on the form of this diffractive radiation. Furthermore, it is this shed radiation …

Stabilization Of Vortex Solitons In Nonlocal Nonlinear Media, Antonmaria Minzoni, Noel Smyth, Annette L. Worthy, Yuri Kivshar

Faculty of Informatics - Papers (Archive)

We study the evolution of vortex solitons in optical media with a nonlocal nonlinear response. We employ a modulation theory for the vortex parameters based on an averaged Lagrangian, and analyze the azimuthal evolution of both the vortex width and diffractive radiation. We describe analytically the physical mechanism for vortex stabilization due to the long-range nonlocal nonlinear response, the effect observed earlier in numerical simulations only.

Mathematical Modelling Of The Self-Heating Process In Compost Piles, Harvinder Sidhu, Mark Nelson, Thiansiri Luangwilai, Xiao Dong Chen

Faculty of Informatics - Papers (Archive)

We model the increase in temperature in compost piles or landfill sites due to micro-organisms undergoing exothermic reactions. The model incorporates the heat release due to biological activity within the pile and the heat release due to the oxidation of cellulosic materials. The heat release rate due to biological activity is modelled by a function which is a monotonic increasing function of temperature over a particular range and followed by a monotone decreasing function of temperature. This functionality represents the fact that micro-organisms die or become dormant at high temperatures. The heat release due to the oxidation reaction is modelled …

Analysis Of A Model For Ethanol Production Through Continuous Fermentation, Simon Watt, Harvinder Sidhu, Mark Nelson, Ajay Ray

Faculty of Informatics - Papers (Archive)

We investigate an experimentally verified model for the production of ethanol through continuous fermentation. Previous studies investigated this model using direct integration. Such integration is time consuming as parameter regions of interest can only be determined through laborious and repetitive calculations. Using techniques from nonlinear dynamical systems theory, in particular a combination of steady state analysis and path following methods, practical insights into operating strategies are found. We use the performance of the reaction scheme in one tank as a benchmark for comparing the performances of multiple tanks.

Development Of A Cross-Faculty Model For The Enhancement Of Academic Standards In Assessment Of Work-Integrated Learning Programs, Linda Corrin, Martin Smith

Faculty of Informatics - Papers (Archive)

The competetiveness of the graduate employment market has prompted universities to develop ways to enhance student employability. This has led to an increase in the adoption of work-integrated (WiL) programs across the university sector. As these programs become a more common element in university degrees, it is necessary for the academic standards of its related assessment to be examined.

At the University of Wollongong (UOW) a number of academic programs incorporate a WiL component, but the methods of presentation and assessment vary considerably. From more traditional internship programs to innovative new problem-based learning models, the breadth and variety of WiL …

Cryptanalysis Of Modification To Self-Certified Group-Oriented Cryptosystem Without A Combiner, Willy Susilo, Hiroaki Kikuchi

Faculty of Informatics - Papers (Archive)

In a (t, n) group-oriented cryptosystem collaboration of at least t participants is required to perform a designated cryptographic operation. This type of cryptographic operation is very important to support an ad-hoc type network, such as the one that is built using Bluetooth or ad-hoc wireless LAN, since the existence of a combiner is not required to decrypt an encrypted message. In the earlier paper, it was shown that a group-oriented encryption scheme, as proposed by Saeednia and Ghodosi, can be subjected to a conspiracy attack in which two participants collude to decrypt an encrypted message. Recently, it was shown …

An Integration Life Cycle For Semantic Web Services Composition, Muhammad Ahtisham Aslam, Jun Shen, Soren Auer, Michael Herrmann

Faculty of Informatics - Papers (Archive)

Business applications are more and more often developed on the basis of Web services. The aim is to provide platform independence and loose coupling between business applications to facilitate distributed and grid computing scenarios. However, most efforts to deploy and publish Web services are manual. Manual discovery, invocation and composition of Web services in a distributed computing environment significantly hamper the automatic process of enterprise application integration. Semantic enhancements in Web services aim at making the process of Web services discovery, invocation and composition dynamic by exposing the machine understandable description of Web service capabilities and Web service requests. In …

An Agent-Based Framework For Service Level Agreement Management, Qiang He, Jun Yan, Ryszard Kowalczyk, Hai Jin, Yun Yang

Faculty of Informatics - Papers (Archive)

In the Web services environment, service level agreements (SLA) refer to mutually agreed understandings and expectations of service provision between service consumers and providers. Although management of SLA is critical to wide adoption of Web services technologies in the real world, support for it is very limited nowadays. There lacks adequate frameworks and technologies supporting various SLA operations. This paper presents an agent-based framework which utilises the agents' ability of negotiation, interaction, and cooperation to facilitate autonomous and flexible SLA management. Based on this framework, mechanisms for autonomous SLA formation, recovery, and profiling are proposed and discussed.

Asymptotic Quasi-Likelihood Based On Kernel Smoothing For Nonlinear And Non-Gaussian State-Space Models, Raed Alzghool, Yan-Xia Lin

Faculty of Informatics - Papers (Archive)

This paper considers parameter estimation for nonlinear and non-Gaussian state-space models with correlation. We propose an asymptotic quasi-likelihood (AQL) approach which utilises a nonparametric kernel estimator of the conditional variance covariances matrix Σ_t to replace the true Σ_t in the standard quasi-likelihood. The kernel estimation avoids the risk of potential miss-specification of Σ_t and thus make the parameter estimator more robust. This has been further verified by empirical studies carried out in this paper.

On The Meaning Of Computer Models Of Robot-Environment Interaction, Ulrich Nehmzow, Phillip J. Mckerrow, Steve Billings

Faculty of Informatics - Papers (Archive)

The “meaning” of a computer model — a computer simulation — of some physical system is an ill-defined concept, and clearly it would strengthen any hypotheses based on such models if some formal model verification was possible. In this paper we present experiments on computer modelling of mobile robot operation, in which the interaction of a Scitos G5 mobile robot with a carefully chosen environment is modelled. The experimental setup chosen was such that we could determine from theoretical considerations what the model should be. The comparison between the actually obtained computer model and the theoretically correct solution demonstrates that …

Online Versus Traditional Grocery Shopping Stressors, Mark B. Freeman

Faculty of Informatics - Papers (Archive)

Research has shown that grocery shopping is the most stressful form of shopping and it is an activity that most individuals perform on a regular basis. Grocery shopping via the Internet has the potential to reduce a number stressors associated with grocery shopping. This research confirms that shopping over the Internet reduces these stressors but creates a new list of potential stressors for customers. This study concludes with solutions an online store can implement to reduce potential stressors for customers.

Small Area Estimation For Spatially Correlated Populations - A Comparison Of Direct And Indirect Model-Based Methods, Hukum Chandra, Nicola Salvati, Ray Chambers

Faculty of Informatics - Papers (Archive)

Linear mixed models underpin many small areas estimation (SAE) methods. In this paper with investigate SAE based on linear models with spatially correlated small area effects where the neighbourhood structure is described by a contiguity matrix. Such models allow efficient use of spatial auxiliary information in SAE.

Optimal Receiver For Space Time Spreading Across A Time Hopping Ppm Over Ultra Wideband Saleh-Valenzuela Mimo Channel, Peter James Vial, Beata J. Wysocki, Tadeusz A. Wysocki

Faculty of Informatics - Papers (Archive)

This paper outlines a technique which can use multiple transmit antennas to send more than one binary bit using the same number of transmit antennas over a single transmission. It uses Ultra Wideband orthogonal pulse position modulation to achieve this, with the receiver employing a Rake receiver and a Maximum Ratio Combiner optimal detector. This is done over a Space Time Spreading Time Hopping Ultra Wideband Pulse Position Modulation system assuming a rich multipath Saleh-Valenzuela MIMO channel model. Simulation results indicate that a significant gain can be achieved compared with other proposed schemes utilising multiple transmit antennas for Ultra Wide …

Community Domain Name Policy Development, Alison Norris, Mark B. Freeman

Faculty of Informatics - Papers (Archive)

In August 2006, auDA launched a new domain name space designed specifically for community groups to develop community websites for the benefit of the local community. This paper presents an overview of the scheme, and identifies the changes made to the governing policies since they were initially proposed. A comparison of the proposed and implemented policies is presented, and the potential effects of these changes on a ‘world first’ community website scheme are considered. The changes made by the administrators to the scheme were in the following areas: local focus; sale of geographic .com.au and .net.au domains; management and licensing; …

A Distributed Time-Fair Scheduling Algorithm For Multi-Rate Wlans, Kwan-Wu Chin

Faculty of Informatics - Papers (Archive)

The performance anomaly experienced by nodes in multi-rate wireless local area networks (WLANs) leads to low throughput and unfairness. To this end, we propose a distributed, token-based approach that allows applications to control nodes channel occupancy time via a single tuning knob. Our approach makes use of local information extensively and does not require any modifications to the IEEE 802.11 MAC nor require explicit signaling. Simulation results show our approach to be effective in ensuring fairness, and isolating high and low rate flows.

A Peirce-Style Calculus For Alc, Frithjof Dau, Peter Eklund

Faculty of Informatics - Papers (Archive)

Description logics (DLs) are a well-understood family of knowledge representation (KR) languages. The notation of DLs has the flavour of a variable-free first order predicate logic. In this paper, a diagrammatic representation of the DL ALC, based on Peirce’s existential graphs, is presented, and a set of transformation rules on these graphs is provided. It is proven that these rules form a sound and complete diagrammatic calculus for ALC.

A Diagrammatic Reasoning System For Alc, Frithjof Dau, Peter Eklund

Faculty of Informatics - Papers (Archive)

Description logics (DLs) are a well-known family of knowledge representation (KR) languages. The notation of DLs has the style of a variable-free first order predicate logic. In this paper a diagrammatic representation of the DL ALC– based on Peirce’s existential graphs – is presented and a set of transformation rules on these graphs provided. As the transformation rules modify the diagrammatic representation of ALC this produces a diagrammatic calculus. Some examples present in the paper illustrate the use and properties of this calculus.

Closed-Form Derivations Of Isi And Mui For Time-Reversed Ultra Wideband, Keni Popovski, Tadeusz A. Wysocki, Beata J. Wysocki

Faculty of Informatics - Papers (Archive)

Through transmitter pre-filtering, a time reversed UWB system is capable if harnessing a multipath channel to achieve temporal and spatial focusing. Unfortunately, large RMS channel delay spread leads to significant intersymbol and multiuser interference. This paper presents closed-form expressions for self and multi-user interference for a UWB system utilizing a time-reversed approach. The influence of user multiplexing codes is taken to account through incorporation of a ‘separation probability’, which characterizes a family of hopping sequences. The standardized IEEE 802.15.3a channel model is applied, and the derived performances are compared with that of a simulated time hopped time-reversed UWB system.

Fast Rsvp: A Cross Layer Resource Reservation Scheme For Mobile Ipv6 Networks, Yi Sun, Bin Feng, Yucheng Zhang, Gengfa Fang, Jinglin Shi, E. Dutkiewicz

Faculty of Informatics - Papers (Archive)

This paper proposes a new cross layer scheme (Fast (Fast RSVP) RSVP) to reserve resources in mobile IPv6 networks. networks. Through the cooperation of mobile IP and RSVP modules, The organ Fast RSVP includes a number of mechanisms such as ad- introduces re vanced resource reservation on neighbor tunnels, resource RSVP schem reservation on optimized routes, resource reservation for results; Secti handover sessions, path merge etc. Network simulation re- conclusions. sults show that our scheme, compared with other traditional ways to reserve resources in mobile environments, has the 2. Related following advantages: (1) it allows a mobile node to realize …

Toward Automatic Measurement Of The Linewidth-Enhancement Factor Using Optical Feedback Self-Mixing Interferometry With Weak Optical Feedback, Yanguang Yu, Jiangtao Xi, Joe F. Chicharo, Thierry Bosch

Faculty of Informatics - Papers (Archive)

This paper proposes an approach for automatically measuring the linewidth-enhancement factor (LEF) of semiconductor lasers using optical feedback self-mixing interferometry (OFSMI), which works in weak optical feedback regime and where the external target is subject to simple harmonic vibration with unknown vibration frequency and magnitude. According to well-known Lang–Kobayashi theory the waveform of the modulated optical output power from the OFSMI system is influenced by multiple parameters, including the LEF, the optical feedback level factor, and the parameters related to the movement of external target. In order to estimate LEF, other parameters must also be considered and, hence, a multiple …

Beyond Videoconference: Increased Functionality To Enhance Media-Rich Interactions In Teaching And Learning, Elahe Aminifar, R. Caladine, Anne Porter, Mark I. Nelson

Faculty of Informatics - Papers (Archive)

Modern technologies provide new approaches to tertiary education and will be an increasing component of the educational experience in the future. Their use poses a significant challenge to the design and delivery of teaching and learning as many teachers and students are unfamiliar with them in this context. Over the last decade there has been a very rapid expansion in the capability and usage of Information and Communication Technologies (ICTs) in teaching and learning. To use them effectively there is a need to understand how different ICTs can be applied to learning and teaching. Videoconference, Access Grid and Web Conference …

Blind Colour Isolation For Colour-Channel-Based Fringe Pattern Profilometry Using Digital Projection, Y. Hu, Jiangtao Xi, Joe F. Chicharo, Zongkai Yang

Faculty of Informatics - Papers (Archive)

We present an algorithm for estimating the color demixing matrix based on the color fringe patterns captured from the reference plane or the surface of the object. The advantage of this algorithm is that it is a blind approach to calculating the demixing matrix in the sense that no extra images are required for color calibration before performing profile measurement. Simulation and experimental results convince us that the proposed algorithm can significantly reduce the influence of the color cross talk and at the same time improve the measurement accuracy of the color-channel-based phase-shifting profilometry.

Optimizing Initial Ranging Region Allocation In Ieee 802.16 Ofdma Systems, Jihua Zhou, E. Dutkiewicz, Di Pang, Jinlong Hu, Jinglin Shi

Faculty of Informatics - Papers (Archive)

The IEEE 802.16 standard has been developed for metropolitan broadband wireless access systems. As part of the standard, the random access scheme is used for initial ranging. The ratio between the numbers of initial ranging slots and data slots in the uplink subframe decides the contention throughput, access delay and data throughput. However, no specific ratio is standardized in the protocol, so it is still necessary to determine the optimal number of initial ranging slots which is the decisive factor of the ratio. In this paper, we analyze the three parameters above, contention throughput, access delay and data throughput, each …

Energy Efficient Integrated Scheduling Of Unicast And Multicast Traffic In 802.16e Wmans, Lin Tian, Yubo Yang, Jinglin Shi, E. Dutkiewicz, Gengfa Fang

Faculty of Informatics - Papers (Archive)

In this paper we address a new problem that has not been addressed in the past: how to improve energy efficiency for both unicast and multicast services without violating QoS requirements of mobile stations in 802.16e wireless networks. We propose a scheduling set based integrated scheduling (SSBIS) algorithm to solve the problem. SSBIS partitions all the mobile stations into multicast Scheduling Sets and a unicast Scheduling Set on the principle of minimizing mobile stations' energy consumptions by making use of the multicast transmission scheme and it adopts different scheduling policies based on the attributes of the Scheduling Sets to improve …

Prediction Of Partners' Behaviors In Agent Negotiation Under Open And Dynamic Environments, Fenghui Ren, Minjie Zhang

Faculty of Informatics - Papers (Archive)

Prediction of partners' behaviors in negotiation has been an active research direction in recent years in the area of multi-agent and agent system. So by employing the prediction results, agents can modify their own negotiation strategies in order to achieve an agreement much quicker or to look after much higher benefits. Even though some of prediction strategies have been proposed by researchers, most of them are based on machine learning mechanisms which require a training process in advance. However, in most circumstances, the machine learning approaches might not work well for some kinds of agents whose behaviors are excluded in …