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Faculty of Informatics - Papers (Archive)

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Articles 901 - 930 of 2013

Full-Text Articles in Physical Sciences and Mathematics

Modelling The Lama Coaxial Helicopter, L. Chen, Phillip J. Mckerrow Jan 2007

Modelling The Lama Coaxial Helicopter, L. Chen, Phillip J. Mckerrow

Faculty of Informatics - Papers (Archive)

Control of a helicopter is complex, and includes cross coupling of forces and balancing of forces. While sophisticated and advanced controllers can achieve stable control, good mechanical design can reduce the problems and hence make tuning the control loops easier. In this paper, we argue that a coaxial-rotor design solves a number of problems that make control of a four-rotor helicopter difficult. First, we examine several coaxial helicopters and discuss the concepts behind coaxial propulsion. Then we develop a dynamic model of the Lama coaxial helicopter. Finally, we compare this model to a model of the Dragonflyer four-rotor helicopter to …

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Automatic Annotation Of Digital Images Using Colour Structure And Edge Direction, Wenbin Shao, G. Naghdy, Son Lam Phung Jan 2007

Automatic Annotation Of Digital Images Using Colour Structure And Edge Direction, Wenbin Shao, G. Naghdy, Son Lam Phung

Faculty of Informatics - Papers (Archive)

The focus of this paper is on automatic annotation for semantic image retrieval. This work is aimed at identifying visual descriptors that are most relevant, effective and suitable for semantic annotation tasks. We propose an image annotation system based on support vector machines and a combination of descriptors that includes a gradient direction histogram and several MPEG-7 visual descriptors. The system is tested on a large database of 7200 cityscape and landscape images. The results indicate that when descriptors are used individually, the proposed gradient direction histogram performs best. However, when descriptors are combined, the accuracy is improved. The presented …

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Automatic Image Annotation For Semantic Image Retrieval, Wenbin Shao, G. Naghdy, Son Lam Phung Jan 2007

Automatic Image Annotation For Semantic Image Retrieval, Wenbin Shao, G. Naghdy, Son Lam Phung

Faculty of Informatics - Papers (Archive)

This paper addresses the challenge of automatic annotation of images for semantic image retrieval. In this research, we aim to identify visual features that are suitable for semantic annotation tasks. We propose an image classification system that combines MPEG-7 visual descriptors and support vector machines. The system is applied to annotate cityscape and landscape images. For this task, our analysis shows that the colour structure and edge histogram descriptors perform best, compared to a wide range of MPEG-7 visual descriptors. On a dataset of 7200 landscape and cityscape images representing real-life varied quality and resolution, the MPEG-7 colour structure descriptor …

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Sydney - Brisbane Land Transport, Philip G. Laird Jan 2007

Sydney - Brisbane Land Transport, Philip G. Laird

Faculty of Informatics - Papers (Archive)

This paper shall commence with reference to the draft AusLink Sydney - Brisbane corridor strategy. Section 2 will outline the upgrading of the Pacific Highway, Section 3 will examine the existing Sydney - Brisbane railway whilst Section 4 will outline some 2009 - 2014 corridor upgrade options with particular attention to external costs and energy use as opposed to intercity supply chain costs. The conclusions are given in Section 5. The current population of the coastal regions of the Sydney - Brisbane corridor exceeds 8 million. As shown by Table I, the population is expected to be approaching 11 million …

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Towards Collaborative Service Level Agreement Negotiation, Qiang He, Jun Yan, Yun Yang, Ryszard Kowalczyk, Hai Jin Jan 2007

Towards Collaborative Service Level Agreement Negotiation, Qiang He, Jun Yan, Yun Yang, Ryszard Kowalczyk, Hai Jin

Faculty of Informatics - Papers (Archive)

A critical issue in the Service Level Agreement management for service composition is to control the relationship between the composite service and the component services in the negotiation. However, existing approaches are inefficient. This paper presents a novel agent-based collaborative approach to address this problem. We introduce a negotiation protocol, under which the agents on the service providers’ side collaborate by exchanging information with each other to gain global knowledge of the negotiation. The collaboration can facilitate the progress of the negotiation. We also discuss the corresponding impact on the decision making strategies.

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Newtonian Flow With Nonlinear Navier Boundary Condition, James M. Hill, Miccal T. Matthews Jan 2007

Newtonian Flow With Nonlinear Navier Boundary Condition, James M. Hill, Miccal T. Matthews

Faculty of Informatics - Papers (Archive)

The generalized nonlinear Navier boundary condition advocated by Thompson and Troian in the journal Nature, and motivated from molecular dynamical simulations, is applied to the conventional continuum mechanical description of fluid flow for three simple pressure-driven flows through a pipe, a channel and an annulus, with a view to examining possible non-uniqueness arising from the nonlinear nature of the boundary condition. For the pipe and the channel it is shown that the results with the nonlinear Navier boundary condition may be obtained from a pseudo linear Navier boundary condition but with a modified slip length. For the annulus, two sets …

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Practical Compact E-Cash, Man Ho Au, Willy Susilo, Yi Mu Jan 2007

Practical Compact E-Cash, Man Ho Au, Willy Susilo, Yi Mu

Faculty of Informatics - Papers (Archive)

Compact e-cash schemes allow a user to withdraw a wallet containing k coins in a single operation, each of which the user can spend unlinkably. One big open problem for compact e-cash is to allow multiple denominations of coins to be spent efficiently without executing the spend protocol a number of times. In this paper, we give a (partial) solution to this open problem by introducing two additional protocols, namely, compact spending and batch spending. Compact spending allows spending all the k coins in one operation while batch spending allows spending any number of coins in the wallet in a …

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A Comparative Study Of The Direct Boundary Element Method And The Dual Reciprocity Boundary Element Method In Solving The Helmholtz Equation, Song-Ping Zhu, Yinglong Zhang Jan 2007

A Comparative Study Of The Direct Boundary Element Method And The Dual Reciprocity Boundary Element Method In Solving The Helmholtz Equation, Song-Ping Zhu, Yinglong Zhang

Faculty of Informatics - Papers (Archive)

In this paper, we compare the direct boundary element method (BEM) and the dual reciprocity boundary element method (DRBEM) for solving the direct interior Helmholtz problem, in terms of their numerical accuracy and efficiency, as well as their applicability and reliability in the frequency domain. For BEM formulation, there are two possible choices for fundamental solutions, which can lead to quite different conclusions in terms of their reliability in the frequency domain. For DRBEM formulation, it is shown that although the DBREM can correctly predict eigenfrequencies even for higher modes, it fails to yield a reasonably accurate numerical solution for …

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Saidi Minimization Of A Remote Distribution Feeder, Kai Zou, Wickramaarachchi W. Keerthipala, Sarath Perera Jan 2007

Saidi Minimization Of A Remote Distribution Feeder, Kai Zou, Wickramaarachchi W. Keerthipala, Sarath Perera

Faculty of Informatics - Papers (Archive)

Distribution system reliability assessment is an important part of distribution system operation and planning. This paper presents some approaches taken to minimize the SAIDI (System Average Interruption Duration Index) for a remote distribution feeder in an 11kV distribution system. Resulting from unavailability of alternative backup supplies from the other adjacent feeders, distributed generators (DG) can be used as backup supplies in this case. Coordinating distribution automation (DA) system with DGs, the restoration area can be made larger and the outage time can be shorter, consequently, the distribution system reliability can be improved significantly. In this paper, factors affecting SAIDI are …

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A Numerical Model For Multiphase Flow Based On The Gmpps Formulation, Part I Kinematics, Song-Ping Zhu, Frank Bierbrauer Jan 2007

A Numerical Model For Multiphase Flow Based On The Gmpps Formulation, Part I Kinematics, Song-Ping Zhu, Frank Bierbrauer

Faculty of Informatics - Papers (Archive)

The CFD modeling of two dimensional multiphase ows is a useful tool in industry, although accurate modeling itself remains a difficult task. One of the difficulties is to track the complicated topological deformations of the interfaces between di erent phases. This paper describes a marker-particle method designed to track fluid interfaces for fluid ows of at least three phases. The interface-tracking scheme presented in this paper is the first part of a series of papers presenting our complete model based on a one-field Godunov marker-particle projection scheme (GMPPS). In this part, we shall focus on the presentation of the interface-tracking …

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Application Of Semistructured Data Model To The Implementation Of Semantic Content-Based Video Retrieval System, Lilac A. E. Al-Safadi, Janusz R. Getta Jan 2007

Application Of Semistructured Data Model To The Implementation Of Semantic Content-Based Video Retrieval System, Lilac A. E. Al-Safadi, Janusz R. Getta

Faculty of Informatics - Papers (Archive)

Semantic indexing of a video document is a process that performs the identification of elementary and complex semantic units in the indexed document in order to create a semantic index defined as a mapping of semantic units into the sequences of video frames. Semantic content-based video retrieval system is a software system that uses a semantic index built over a collection of video documents to retrieve the sequences of video frames that satisfy the given conditions. This work introduces a new multilevel view of data for the semantic content-based video retrieval systems. At the topmost level, we define an abstract …

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Emotional States Control For On-Line Game Avatars, Ce Zhan, Wanqing Li, Farzad Safaei, Philip Ogunbona Jan 2007

Emotional States Control For On-Line Game Avatars, Ce Zhan, Wanqing Li, Farzad Safaei, Philip Ogunbona

Faculty of Informatics - Papers (Archive)

Although detailed animation has already been achieved in a number of Multi-player On-line Games (MOGs), players have to use text commands to control emotional states of avatars. Some systems have been proposed to implement a real-time automatic system facial expression recognition of players. Such systems can then be used to control avatars emotional states by driving the MOG's "animation engine" instead of text commands. Some of the challenges of such systems is the ability to detect and recognize facial components from low spatial resolution face images. In this paper a system based on an improved face detection method of Viola …

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Nursing Information Systems: Applying Usability Testing To Assess The Training Needs For Nursing Students, Yiyu Qiu, Ping Yu Jan 2007

Nursing Information Systems: Applying Usability Testing To Assess The Training Needs For Nursing Students, Yiyu Qiu, Ping Yu

Faculty of Informatics - Papers (Archive)

Objective: In order to ensure the successful implementation of a nursing information system (NIS), nurses and nursing students must be adequately trained. In order to do this effectively, it is essential to understand their training needs. This study focuses on the training needs of nursing students in particular through the identification of the usage problems they encounter. Usability testing, which involves observing users' interaction with an NIS, overcomes the deficiencies of traditional approaches of training needs analysis such as interview and survey. The study applied usability test to assess training needs of nursing students to learn to use a specific …

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Development Of A Specialist Medical Vocabulary For Radiation Oncology, Andrew Alexis Miller, Ping Yu Jan 2007

Development Of A Specialist Medical Vocabulary For Radiation Oncology, Andrew Alexis Miller, Ping Yu

Faculty of Informatics - Papers (Archive)

Controlled medical terminologies that have been developed to describe terms utilized in the field of Radiation Oncology, include SNOMED-CT and DICOM-RT. However, a literature review has failed to provide evidence that the coverage and the level of granularity of these nomenclatures have satisfied the needs of radiation oncologists. Indeed most investigations conclude that the coverage is generally unsatisfactory. Fur-thermore, there is no evidence that an objective specification of the specialist medical terms used in Radiation Oncology has been developed. We report the development of a Specialist Medical Vocabu-lary for Radiation Oncology using an objective and systematic method of discovery of …

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New Method Vulnerability Assessment Of Power System, Ahmed M. Haidar, Azah Mohamed, Aini Hussain Jan 2007

New Method Vulnerability Assessment Of Power System, Ahmed M. Haidar, Azah Mohamed, Aini Hussain

Faculty of Informatics - Papers (Archive)

Vulnerability assessment in power systems is to determine a power system`s ability to continue to provide service in case of an unforeseen catastrophic contingency. It combines information on the level of system security as well as information on a wide range of scenarios, events and contingencies. To assess the level of system strength or weakness relative to the occurrence of an undesired event, a quantitative measure based on vulnerability index is often considered. In this study, a new vulnerability assessment method is proposed based on total power system loss which considers power generation loss due to generation outage, power line …

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An Example Of A Hierarchical System Model Using Seam And Its Formalization In Alloy, Alain Wegmann, Lam-Son Le, Jose Diego De La Cruz, Irina Rychkova, Gil Regev Jan 2007

An Example Of A Hierarchical System Model Using Seam And Its Formalization In Alloy, Alain Wegmann, Lam-Son Le, Jose Diego De La Cruz, Irina Rychkova, Gil Regev

Faculty of Informatics - Papers (Archive)

SEAM is an enterprise architecture method based on RM-ODP part 2. In this paper, we present an example of a SEAM hierarchical model where the behavioral part is formalized in Alloy. We introduce four kinds of actions and their relationships to properties that specify object state. We show that the Alloy formalization enables us to check that the SEAM model conforms to the required aspects of the universe of discourse.

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From Business To It With Seam: The J2ee Pet Store Example, Irina Rychkova, Gil Regev, Lam-Son Le, Alain Wegmann Jan 2007

From Business To It With Seam: The J2ee Pet Store Example, Irina Rychkova, Gil Regev, Lam-Son Le, Alain Wegmann

Faculty of Informatics - Papers (Archive)

Business and IT alignment demands clear traceability between the applications to be developed and the business requirements. SEAM is a systemic visual approach for modeling systems, including information systems and organizations. This paper illustrates how we represent the business role of an IT application and its platform-specific realization in SEAM. We use the Java Pet Store sample application as an example.

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Classifying Still Faces With Ultrasonic Sensing, Phillip J. Mckerrow, K. K. Yoong Jan 2007

Classifying Still Faces With Ultrasonic Sensing, Phillip J. Mckerrow, K. K. Yoong

Faculty of Informatics - Papers (Archive)

The echo of a chirp of ultrasonic energy from an object contains information about the geometry of that object: relative depth of surfaces and approximate area of those surfaces. A human face has complex geometry that produces a distinctive echo. In this paper, we report initial research into whether there is sufficient information in the echo to recognize a still face. Potential features for classification are identified using a facial model. The classification results for 10 faces encourage future research with a larger number of faces and with moving faces.

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A Simple Orthogonal Space-Time-Polarization Block Code, Beata J. Wysocki, Tadeusz A. Wysocki, Jennifer R. Seberry, Sarah S. Adams, Hamid Sharif Jan 2007

A Simple Orthogonal Space-Time-Polarization Block Code, Beata J. Wysocki, Tadeusz A. Wysocki, Jennifer R. Seberry, Sarah S. Adams, Hamid Sharif

Faculty of Informatics - Papers (Archive)

This letter proposes a simple but highly efficient technique to jointly utilize space, time, and polarization diversities. The technique is based on extending orthogonal space-time block codes into the quaternion domain and utilizing a description of the dual-polarized signal by means of quaternions, which are a generalization of complex numbers. In the given example, the achievable performance gain for two transmit and one receive antennas is approximately 6 dB at a bit error rate of 10-4 when compared with the Alamouti code.

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A Simple Spatial Model For Self-Heating Compost Piles, Harvinder Sidhu, Mark Nelson, Xiao Dong Chen Jan 2007

A Simple Spatial Model For Self-Heating Compost Piles, Harvinder Sidhu, Mark Nelson, Xiao Dong Chen

Faculty of Informatics - Papers (Archive)

We model the increase in temperature in compost piles due to micro-organisms undergoing exothermic reactions. The model incorporates two types of heat release: one due to biological activity; and the other due to the oxidation of cellulosic materials. In this study we also include the consumption of oxygen. We investigate the bifurcation behaviour and compare the results obtained from models that include and exclude oxygen consumption in both one- and two-dimensional geometries.

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Encapsulation Of C60 Fullerenes Into Single-Walled Carbon Nanotubes: Fundamental Mechanical Principles And Conventional Applied Mathematical Modeling, Duangkamon Baowan, Ngamta Thamwattana, James M. Hill Jan 2007

Encapsulation Of C60 Fullerenes Into Single-Walled Carbon Nanotubes: Fundamental Mechanical Principles And Conventional Applied Mathematical Modeling, Duangkamon Baowan, Ngamta Thamwattana, James M. Hill

Faculty of Informatics - Papers (Archive)

A well-known self-assembled hybrid carbon nanostructure is a nanopeapod which may be regarded as the prototype nanocarrier for drug delivery. While the investigation of the packing of C60 molecules inside a carbon nanotube is usually achieved through either experimentation or large scale computation, this paper adopts elementary mechanical principles and classical applied mathematical modeling techniques to formulate explicit analytical criteria and ideal model behavior for such encapsulation. In particular, we employ the Lennard-Jones potential and the continuum approximation to determine three encapsulation mechanisms for a C60 fullerene entering a tube: (i) through the tube open end (head-on), (ii) around the …

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Mechanics Of Spheroidal Fullerenes And Carbon Nanotubes For Drug And Gene Delivery, Barry Cox, Ngamta Thamwattana, James M. Hill Jan 2007

Mechanics Of Spheroidal Fullerenes And Carbon Nanotubes For Drug And Gene Delivery, Barry Cox, Ngamta Thamwattana, James M. Hill

Faculty of Informatics - Papers (Archive)

There is considerable interest in the mechanics of carbon nanostructures, such as carbon nanotubes and fullerenes , and the manner of their interactions at the intennolecular level. Medical applications i.n clud e the use of carbon .nanotub e. for tar etcd drug a nd gen e delivery, for which issues relating to ll1c acceptan ce and containmen t of dru g or genes are n ot prop ­ erly understood . A sph eroid is an ellipsoid with rwo equal axes and the general spheroidal shape inclu des a wide vadcty of possible m olecu lar onfigurations su ch a …

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Multi-Variable Relationships In A Batch Annealing Process, David J. Scott, Ken Russell, Judi Scheffer Jan 2007

Multi-Variable Relationships In A Batch Annealing Process, David J. Scott, Ken Russell, Judi Scheffer

Faculty of Informatics - Papers (Archive)

Empirical models are developed to predict the mechanical properties of four groups of cold-rolled annealed steels, based on upstream processing variables in the hot-rolling process, annealing conditions, the chemical composition of the steel and product details. Various linear models are considered but the simplest approach of using a multiple linear regression model is considered the most satisfactory. This analytical tool will allow better understanding of the steel making process and the ability to vary input parameters to improve the product. In particular the number of coils which fail mechanical testing may be able to be reduced, with a subsequent fall …

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Design Principles For Low Latency Anonymous Network Systems Secure Against Timing Attacks, Rungrat Wiangsripanawan, Willy Susilo, Reihaneh Safavi-Naini Jan 2007

Design Principles For Low Latency Anonymous Network Systems Secure Against Timing Attacks, Rungrat Wiangsripanawan, Willy Susilo, Reihaneh Safavi-Naini

Faculty of Informatics - Papers (Archive)

Low latency anonymous network systems, such as Tor, were considered secure against timing attacks when the threat model does not include a global ad- versary. In this threat model the adversary can only see part of the links in the system. In a recent paper entitled Low-cost traffic analysis of Tor, it was shown that a variant of timing attack that does not require a global adversary can be applied to Tor. More impor- tantly, authors claimed that their attack would work on any low latency anonymous network systems. The implication of the attack is that all low latency …

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Mitigating Phishing By A New Id-Based Chameleon Hash Without Key Exposure, Qiong Ren, Yi Mu, Willy Susilo Jan 2007

Mitigating Phishing By A New Id-Based Chameleon Hash Without Key Exposure, Qiong Ren, Yi Mu, Willy Susilo

Faculty of Informatics - Papers (Archive)

Chameleon signatures were introduced by Krawczyk and Rabin to provide a non-transferable signature scheme. However, the nontransferability property requires the willingness of the recipient in consequentially exposing a secret key and therefore invalidating all signatures issued to the same recipient’s public key. This notion has been extended by Chen et al. to allow a “key-exposure ” freeness scheme. However, it was concluded that to achieve this key-exposure freeness, one would require a technique called “identity customization”. Therefore, the notion of identity-based chameleon hash function becomes redundant since the identity is always needed in the construction of chameleon hash functions themselves. …

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A New Image Feature For Fast Detection Of People In Images, Son Lam Phung, Abdesselam Bouzerdoum Jan 2007

A New Image Feature For Fast Detection Of People In Images, Son Lam Phung, Abdesselam Bouzerdoum

Faculty of Informatics - Papers (Archive)

In this paper, we present a new method of detecting visual objects in digital images and video. The novelty of the proposed method is that it differentiates objects from non-objects using image edge characteristics. Our approach is based on a fast object detection method recently developed by Viola and Jones. While Viola and Jones use Harr-like features, we propose a new image feature called edge density that can be computed more efficiently. When applied to the problem of detecting people and pedestrians in images, the new feature shows very good discriminative capability compared to Harr-like features.

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Simplicity Of C*-Algebras Associated To Higher-Rank Graphs, David Robertson, Aidan Sims Jan 2007

Simplicity Of C*-Algebras Associated To Higher-Rank Graphs, David Robertson, Aidan Sims

Faculty of Informatics - Papers (Archive)

We prove that if ᴧ is a row-fiuit e k-graph with no sources, then the associated C*-algebra is simple if and only if ᴧ is cofinal and satisfies Kumjian and Pask's aperiodicity condition, known as Condition (A). We prove that the aperiodicity condition is equivalent to a suitably modifi ed version of Robertson and Steger's original nonperiodicity condition (H3), which in particular involves only finite paths. We also characterise both cofinality and aperiodicity of ᴧ in terms of ideals in C* (ᴧ).

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An Ontology-Based Knowledge Network To Reuse Inter-Organizational Knowledge, Nelson K. Y. Leung, Sim Kim Lau, Joshua P. Fan Jan 2007

An Ontology-Based Knowledge Network To Reuse Inter-Organizational Knowledge, Nelson K. Y. Leung, Sim Kim Lau, Joshua P. Fan

Faculty of Informatics - Papers (Archive)

Researchers have developed various types of Knowledge Management approaches that only focus on managing organizational knowledge. However, these designs are inadequate because employees are often needed to access knowledge from other knowledge sources in order to complete their works. Therefore, a new interorganizational Knowledge Management practice is required to enhance the sharing of knowledge across organizational boundaries in their business networks. In this paper, we investigate the application of ontology mediation that provides mechanisms of reconciling inter-organizational knowledge. An ontology-based Interorganizational knowledge Network that incorporates ontology mediation is developed so that heterogeneity of knowledge semantic in the ontologies could be …

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Modelling And Comparative Performance Analysis Of A Time Reversed Uwb System, Keni Popovski, Beata J. Wysocki, Tadeusz A. Wysocki Jan 2007

Modelling And Comparative Performance Analysis Of A Time Reversed Uwb System, Keni Popovski, Beata J. Wysocki, Tadeusz A. Wysocki

Faculty of Informatics - Papers (Archive)

The effects of multipath propagation lead to a significant decrease in system performance in most of the proposed ultra-wideband communication systems. A time-reversed system utilises the multipath channel impulse response to decrease receiver complexity, through a prefiltering at the transmitter. This paper discusses the modelling and comparative performance of a UWB system utilising time-reversed communications. System equations are presented, together with a semianalytical formulation on the level of intersymbol interference and multiuser interference. The standardised IEEE 802.15.3a channel model is applied, and the estimated error performance is compared through simulation with the performance of both time-hopped time-reversed and RAKE-based UWB …

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A New Approach To Bsofdm - Parallel Concatenated Spreading Matrices Ofdm, Ibrahim S. Raad, X. Huang Jan 2007

A New Approach To Bsofdm - Parallel Concatenated Spreading Matrices Ofdm, Ibrahim S. Raad, X. Huang

Faculty of Informatics - Papers (Archive)

This paper proposes a new approach to block spread OFDM called parallel concatenated spreading matrices OFDM (PCSM-OFDM). While BSOFDM improved the overall BER performance on OFDM in frequency selective channels, this new approach further improves the BER of BSOFDM by a 3 dB gain. This is achieved through increasing the diversity of the transmitted samples by concatenating two spreading matrices in parallel to BSOFDM.

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