Physical Sciences and Mathematics Commons^™

Decision Aided Joint Compensation Of Clipping Noise And Nonlinearity For Mimo-Ofdm Systems, Shouyi Yang, Jiangtao Xi, Xiaomin Mu

Faculty of Informatics - Papers (Archive)

In this paper, we propose a new iterative approach to compensate the nonlinearity and clipping noise in multi-input multi-output orthogonal frequency division multiplexing (MlMO-OFDM) system with nonlinear channel. The proposed approach consists of two stages. Firstly a decision aided method is proposed to eliminate the nonlinearity introduced by high power transmit amplifier (HPA). Then this improved decision observations are employed to achieve the clipping noise compensation. The effectiveness of the proposed approach has been verified by computer simulations.

An Adaptive Scalable Multiuser-Ofdm System For Multimedia Transmission Over Fading Channels, Ahmed Muthana M. Nadhim, Jianhua He, Jiangtao Xi, Zongkai Yang

Faculty of Informatics - Papers (Archive)

In this paper, an adaptive scalable multiuser-OFDM system was proposed for multimedia transmission over fading channels. The proposed adaptive algorithm can adapt according to the channel status information of each user's channel status. This algorithm dynamically changes according to the user's channel changes; this can keep fixed QoS at the physical layer. Another predefined QoS for different sessions and services to be provided for different users. This QoS can be guaranteed by multimedia scalability. Scalability can adapt to the service requirements, in terms of transmission data rate and bandwidth. As a result, a robust multimedia transmission scheme is achieved by …

Signal Processing Methods Implemented In A Novel Fbg Sensing System For Vibration/Dynamic Strain Measurement, Xingyuan Xu, Enbang Li, Jiangtao Xi, Joe F. Chicharo

Faculty of Informatics - Papers (Archive)

We have demonstrated a novel Fiber Bragg Grating sensing system based on a Fabry-Perot tunable filter for measuring dynamic processes. This system is very suitable for multipoint vibration or dynamic strain detection. However, in some conditions, the response time of Fabry-Perot tunable filter will influence the sensitivity of the sensor that the sensitivity is not kept constant. Therefore, post-processing for the measured vibration signal is necessary to solve this problem. In this paper, the demodulation technique of this system is briefly described and two signal processing methods are introduced to deal with the measured signal to obtain stable measurement of …

Multi-Frequency And Multiple Phase-Shift Sinusoidal Fringe Projection For 3d Profilometry, Enbang Li, X. Peng, Jiangtao Xi, Joe F. Chicharo, Jianquan Yao, D.W. Zhang

Faculty of Informatics - Papers (Archive)

In this paper, we report on a laser fringe projection set-up, which can generate fringe patterns with multiple frequencies and phase shifts. Stationary fringe patterns with sinusoidal intensity distributions are produced by the interference of two laser beams, which are frequency modulated by a pair of acousto-optic modulators (AOMs). The AOMs are driven by two RF signals with the same frequency but a phase delay between them. By changing the RF frequency and the phase delay, the fringe spatial frequency and phase shift can be electronically controlled, which allows high-speed switching from one frequency or phase to another thus makes …

A Comparative Analysis Of The Use Of The Web For Destination Marketing By Regional Tourism Organisations In Chile And The Asia Pacific, Lois Burgess, Joan Cooper, Narciso Cerpa, Jason P. Sargent

Faculty of Informatics - Papers (Archive)

With reports of travel purchases and reservations being one of the fastest growing segments of the Internet community (eMarketer, 2002), it is no surprise that the number of tourism operators on the Web has increased considerably over the past few years. In recent years, Australia and Chile have developed strong social and economic ties. With the introduction of direct air links between Australia and Chile in July 2002, the number of Australian business people and tourists visiting Chile and neighbouring countries increased significantly. This isn’t surprising considering approximately 35,000 Chileans live in Australia (DFAT, 2005). This paper presents the results …

A Generalized Algorithm For The Generation Of Correlated Rayleigh Fading Envelopes In Wireless Channels, Le Chung Tran, Tadeusz A. Wysocki, Alfred Mertins, Jennifer R. Seberry

Faculty of Informatics - Papers (Archive)

Although generation of correlated Rayleigh fading envelopes has been intensively considered in the literature, all conventional methods have their own shortcomings, which seriously impede their applicability. In this paper, a very general, straightforward algorithm for the generation of an arbitrary number of Rayleigh envelopes with any desired, equal or unequal power, in wireless channels either with or without Doppler frequency shifts, is proposed. The proposed algorithm can be applied to the case of spatial correlation, such as with multiple antennas in Multiple Input Multiple Output (MIMO) systems, or spectral correlation between the random processes like in Orthogonal Frequency Division …

A Data-Fitting Approach For Displacements And Vibration Measurement Using Self-Mixing Interferometers, Yi Zhang, Jiangtao Xi, Joe F. Chicharo, Yanguang Yu

Faculty of Informatics - Papers (Archive)

This paper presents a signal processing approach for vibration measurement using self-mixing interferometer (SMI). Compared to existing approaches, the proposed approach is able to achieve an accuracy of λ/40 which significantly exceeds the accuracy limit associated with conventional simple SMI systems λ/4.

Web Globalization: A Methodology For Developing Usable Websites For The Global Market, Ghassan Al Qaimari

Faculty of Informatics - Papers (Archive)

In today’s global economy, with the appearance of the Internet and the fast evolution of technology, the frontiers of local markets have been fading and blending with global markets. These markets with no boundaries have lead many companies, organizations, educational institutions, and digital libraries to develop their own websites, and to find ways to make them usable and accessible and their products saleable to customers outside their traditional markets. Going global can help corporations lower the cost of entry to international trade, increase sales, create global demands, and establish a reliable, professional and international image online.

This means that website …

Distributing Network Game Servers For Improved Geographical Scalability, Paul A. Boustead, Farzad Safaei, Jeremy Brun

Faculty of Informatics - Papers (Archive)

World-wide multiplayer games present several scalability challenges for large-scale deployment. In recent years, significant research has been devoted to scaling in terms of number of players so that the same virtual world can accommodate larger number of simultaneous avatars. A possible solution is to use grid computing techniques for distribution of processing over a cluster or a distributed set of servers. Scalability with respect to geographical distribution of players is another challenge. Large geographical distances between players introduces propagation delays which are impossible to avoid. Without proper design, responsiveness of the application to user inputs is degraded even when there …

A Theoretical Justification For Partnerships In Community Technology Centre Projects, William Tibben

Faculty of Informatics - Papers (Archive)

In many Community Technology Centre projects, partnerships are emerging as a fundamentally important aspect to achieving sustainability. While generally considered a less formal approach than direct funding from rich benefactors such as Government or philanthropic organisations, the paper argues that partnerships offer an effective and theoretically justifiable framework to achieving sustainability. Drawing on information based perspectives the paper proposes a theoretical justification for the use of partnerships in community informatics projects that is able to incorporate individuals and groups in the analysis.

A Study On The Charge-Discharge Mechanism Of Co3o4 As An Anode For The Li Ion Secondary Battery, Yong-Mook Kang, Min-Sang Song, Jin-Ho Kim, Hyun-Seok Kim, Min-Sik Park, Jai-Young Lee, Hua-Kun Liu, S X. Dou

Australian Institute for Innovative Materials - Papers

Co₃O₄ has shown acceptable electrochemical properties as the anode material of Li secondary batteries. In detail, its capacity reached about 700 mAh/g, twice as high as graphite, and 93.4% of initial capacity was retained after 100 cycles. EIS (electrochemical impedance spectroscopy) analyses revealed that after the 1st cycle, the insertion or extraction of Li ions in Co₃O₄ can occur homogeneously and reversibly (randless-like behavior, homogeneous mixture: Co + Li₂O (in the state of Li insertion), Co₃O₄ (in the state of Li extraction)). In fact, the coulombic efficiency of Co …

Radiocarbon In Corals From The Cocos (Keeling) Islands And Implications For Indian Ocean Circulation, Q Hua, Colin D. Woodroffe, Scott Smithers, M Barbetti, David Fink

Faculty of Science - Papers (Archive)

Annual bands of a Porites coral from the Cocos (Keeling) Islands, eastern Indian Ocean, were analysed by radiocarbon for 1955–1985 AD. A rapid oceanic response of the site to bomb 14C is found, with a maximum D14C value of 132% in 1975. This value is considerably higher than those for the northwestern Indian Ocean, suggesting that surface waters reaching Cocos are not derived from the Arabian Sea. Instead, D14C values for Cocos and those for Watamu (Kenya) agree well over most of the study interval, suggesting that the South Equatorial Current carries 14C-elevated water rather than 14C-depleted water westward across …

A Secure Multicast Architecture And Protocol For Mospf, Junqi Zhang, Yi Mu, Vijay Varadharajan

Faculty of Informatics - Papers (Archive)

Multicast Open Shortest Path First (MOSPF) is an en hancement to unicast routing protocol OSPF. It has been widely used in many multicast applications for years. How ever, its security is still a major concern in some applica tions. Much work has been done on data protection, but only a few works have been done on member access con trol mechanisms. In this paper, we present a new secure multicast architecture and protocol for MOSPF from the perspective of member access control. Our new model in cludes a variant of previous access control mechanism and a novel distributed encryption scheme. …

Macrochannels And Their Significance For Flood-Risk Minimisation, West Dapto, New South Wales, E. L. Roper, Ivars Reinfelds, Gerald C. Nanson

Faculty of Science - Papers (Archive)

A prominent characteristic of streams draining catchments in West Dapto, New South Wales, are well developed macrochannels that have formed within alluvial terraces in mid-catchment zones. A detailed hydraulic modelling study using HEC-RAS, HEC-GeoRAS and Arcview GIS indicates that these macrochannels are scaled to accommodate high magnitude floods. They offer a significant degree of natural protection from flood events up to and in excess of 100 years recurrence interval, essentially by operating as 'bankfull' channels during such events. Macrochannel landforms can be clearly distinguished and mapped on fine-scale digital elevation models (DEMs) and other GIS data sources such as rectified …

Rotational Effects In The Band Oscillator Strengths And Predissociation Linewidths For The Lowest 1pi U X 1sigma + G Transitions Of N2, V. E. Haverd, B.R. Lewis, S.T. Gibson, G. Stark

Faculty of Science - Papers (Archive)

A coupled-channel Schrödinger equation (CSE) model of photodissociation, which includes the effects of all interactions between the , , and and the and states, is employed to study the effects of rotation on the lowest- band oscillator strengths and predissociationlinewidths. Significant rotational dependences are found which are in excellent agreement with recent experimental results, where comparisons are possible. New extreme-ultraviolet (EUV)photoabsorption spectra of the key transition of are also presented and analyzed, revealing apredissociationlinewidth peaking near . This behavior can be reproduced only if the triplet structure of the state is included explicitly in the CSE-model calculations, with a spin-orbit …

Comparisons Between Sciamachy And Ground-Based Ftir Data For Total Columns Of Co, Ch4, Co2 And N2o, B Dils, M De Maziere, T Blumenstock, M Buchwitz, R De Beek, Nicholas B. Jones, David W. Griffith, P Demoulin, A G Frankenberg, H Duchatelet, Hans Fast

Faculty of Science - Papers (Archive)

Total column amounts of CO, CH4, CO2 and N2O retrieved from SCIAMACHY nadir observations in its near-infrared channels have been compared to data from a ground-based quasi-global network of Fourier-transform infrared (FTIR) spectrometers. The SCIAMACHY data considered 5 here have been produced by three different retrieval algorithms, WFM-DOAS (version 0.4, 0.41 for CH4), IMAP-DOAS (version 0.9) and IMLM (version 5.5) and cover the January to December 2003 time period. Comparisons have been made for individual data, as well as for monthly averages. To maximize the number of reliable coincidences that satisfy the temporal and spatial collocation criteria, the 10 SCIAMACHY …

An Automated Gis Method For Modeling Relative Wave Exposure Within Complex Reef-Island Systems: A Case Study Of The Great Barrier Reef, Marjetta L. Puotinen

Faculty of Science - Papers (Archive)

Patterns of wave energy play a significant role in shaping the long-term structure of coral reef communities worldwide. For example, sections of reefs have been shown to vary greatly in morphology (dominant size class, growth form) as coral colonies adapt in response to local-scale differences in the wave heights typically experienced. These differences result in zonation (crest, lagoon, and slope), producing characteristic growth forms and species assemblages that vary in their vulnerability to damage from waves (Done 1993). Those communities experiencing the greatest typical wave energy align themselves parallel to the water flow, adopt stream-lined forms and are usually smaller …

Illuminating Southeast Asian Prehistory : New Archaeological And Paleoanthropological Frontiers For Luminescence Dating, Richard G. Roberts, Michael J. Morwood, Kira E. Westaway

Faculty of Science - Papers (Archive)

Since the explorations of Alfred Russel Wallace and Eugène Dubois in the nineteenth century, Southeast Asia has been one of the world's focal points for studies of biogeography and biodiversity, human evolution and dispersal, environmental change, and the spread of culture, farming, and language. Yet despite its prominence, reliable chronologies are not available for many of the critical archaeological, evolutionary, and environmental turning points that have taken place in the region during the last 1.5 million years. In this paper, we discuss some of these chronological problems and describe how luminescence dating may help overcome them. "Luminescence dating" is a …

Evidence For Altitude-Dependent Photolysis-Induced 18o Isotopic Fractionation In Stratospheric Ozone, Vanessa E. Haverd, Geoffrey C. Toon, David W. Griffith

Faculty of Science - Papers (Archive)

We present vertical profiles of ¹⁸O fractionations in ozone, measured by balloon-borne infrared remote sensing between 15 and 40 km. The magnitudes of the ¹⁶O¹⁶O¹⁸O (⁶⁶⁸O₃) and ¹⁶O¹⁸O¹⁶O (⁶⁸⁶O₃) fractionations are 13.5 +/- 2.7% and 7.7 +/- 2.2%, averaged over the 20-35 km altitude range, in good agreement with previous atmospheric measurements by mass spectrometry and both infrared and far infrared remote sensing spectroscopy. We use our fractionation profiles, together with known fractionation effects of the ozone formation reaction, to deduce …