Latest NICTA Publications

Performance and scalability evaluation of the Castalia Wireless Sensor Network simulator

Mon, 15 Mar 2010 00:00:00 +0000

Authors: Dimosthenis Pediaditakis, Yuri Tselishchev, Athanassios Boulis

Abstract: Castalia is an open-source simulator for wireless sensor networks and body area networks which is widely used in the academic and research community. This paper presents a basic evaluation study of Castalia, reporting computation time and memory usage for a variety of scenarios/benchmarks. Moreover, key parameters, such as network size, simulation time, fraction of mobile nodes are varied to reveal Castalia’s scalability potential. We discuss our results and explain counterintuitive findings in performance. The results and their explanation can be used by Castalia users as a guide to determine the limits they can push their simulations, as well as to make parameter choices that trade-off accuracy for performance. They also provide an indication of Castalia’s performance capabilities to potential users.

3rd International ICST Conference on Simulation Tools and Techniques (SIMUTools2010)-March 2010

Refinement in the formal verification of seL4

Sat, 13 Mar 2010 00:00:00 +0000

Authors: Gerwin Klein, Thomas Sewell, Simon Winwood

Abstract: We present an overview of the different refinement frameworks used in theL4.verified project to formally prove the functional correctnes ofthe seL4 microkernel. The verification is conducted in theinteractive theorem prover Isabelle/HOL and proceeds in two large refinementsteps: one proof between two monadic, functional specificationsin HOL and one proof between such a monadic specification and a C program.To connect these proofs into one overall theorem, we map both refinementstatements into a common overall framework.

Design and Verification of Microprocessor Systems for High-Assurance Applications-March 2010

An Inclusion Theorem for Defeasible Logic

Fri, 12 Mar 2010 00:00:00 +0000

Authors: David Billington, Grigoris Antoniou, Guido Governatori, Michael Maher

Abstract: Defeasible reasoning is a computationally simple nonmonotonic reasoning approach that has attracted significant theoretical and practical attention. It comprises a family of logics that capture different intuitions, among them ambiguity propagation versus ambiguity blocking, and the adoption or rejection of team defeat. This paper provides a compact presentation of the defeasible logic variants, and derives an Inclusion Theorem which shows that different notions of provability in defeasible logic form a chain of levels of proof, while they al exhibit a basic coherence property.

ACM Transactions on Computational Logic

Towards an Architectural Viewpoint for Systems of Software Intensive Systems

Fri, 12 Mar 2010 00:00:00 +0000

Authors: John Brondum, Liming Zhu

Abstract: An important part of architectural knowledge is the capture of the environment and external system relationships through contextual viewpoints[35]. However, the semantic definitions of software relationships[29][23][26] do not adequately capture inter-system level relationships[6], and offers no guidance on implicit or indirect relationships[35]. Yet the architect is tasked with the very responsibility of defining external relationships[11] leaving him/her either unaware of critical relationships or, to’roll their own’ based on aggregations of code-level call/use structures. This leads to critical gaps in the architectural documentation and communication problems within Systems of Software intensive Systems (S3) environments - if undetected can cause serious problems for development projects[3]. S3 environments may also restrict the sharing of architectural knowledge due to either legal or contractual constraints, or contain an overwhelming amount of documentation due to size and number of involved systems - either scenario further adds to the challenge of identifying and describing therelationships. This paper presents a novel and light-weight S3 Architectural Viewpoint consisting of 1) an extensible taxonomy of system level relationships, 2) with a systematic, repeatable technique to detect both immediate and linked system level relationships. The goal is an architectural approach for the sharing and analysis of architectural knowledge relating to software system relationships in an S3 or ecosystem environment. The research is on-going and developed through the mining of existing software ecosystems and industry S3 architectures. Validation will be performed through casestudies from industry collaborations.

SHARK at ICSE 2010-May 2010

Software Architecture for Systems of Software Intensive Systems (S3): The Concepts and Detection of Inter-System Relationships

Fri, 12 Mar 2010 00:00:00 +0000

Authors: John Brondum

Abstract: Key to software architecture is the description of relationshipsbetween software components [10] supported by commonlyunderstood semantic definitions [9][8]. However, thedefinitions do not adequately capture the inter-system levelsoftware relationships. This leaves software architects eitherunaware of critical relationships or, to’roll their own’ based on aggregations of code-level call/use structures. This leads to critical gaps in the architectural description and communication problems within distributed development environments - as poorly understood relationships can inadvertently propagate changes and break systeminteroperability [2]. The solution requires a description of new system level relationships and a new systematic, repeatable technique to detect both immediate and linked system level relationships. The solution will be developed through the mining of existing software ecosystemsand industry systems of softwareintensive systems (S3) architectures. Validation will be performedthrough case studies from industry collaborations.

Doctoral Symposium at ACM/IEEE 32nd International Conference on Sofware Engineering (ICSE 2010)-May 2010

OMF: A Control and Management Framework for Networking Testbeds

Fri, 12 Mar 2010 00:00:00 +0000

Authors: Thierry Rakotoarivelo, Max Ott, Guillaume Jourjon, Ivan Seskar

Abstract: Networking testbeds are playing an increasingly important role in the development of new communication technologies. Testbeds are traditionally built for a particular project or to study a specific technology. An alternative approach is to federate existing testbeds to a) cater for experimenter needs which cannot be fulfilled by a single testbed, and b) provide a wider variety of environmental settings at different scales. These heterogenous settings allow the study of new approaches in environments similar to what one finds in the real world. This paper presents OMF, a control, measurement, and management framework for testbeds. It describes through some examples the versatility of OMF's current architecture and gives directions for federation of testbeds through OMF. In addition, this paper introduces a comprehensive experiment description language that allows an experimenter to describe resource requirements and their configurations, as well as experiment orchestration. Researchers would thus be able to reproduce their experiment on the same testbed or in a different environment with little changes. Along with the efficient support for large scale experiments, the use of testbeds and support for repeatable experiments will allow the networking field to build a culture of cross verification and therefore strengthen its scientific approach.----- This work was first accepted for publication and presented at the SOSP Workshop on Real Overlays and Distributed Systems (ROADS '09). It was then selected with other papers from SOSP Workshops to be re-published in the December 2009 issue of ACM Operating Systems Review journal (http://www.sigops.org/osr.html).

ACM Operating Systems Review (OSR)-December 2009

How Do Agents Comply with Norms?

Thu, 11 Mar 2010 00:00:00 +0000

Authors: Guido Governatori, Antonino Rotolo

Abstract: The import of the notion of institution in the design of MASsrequires to develop formal and efficient methods for modeling theinteraction between agents' behaviour and normative systems. Thispaper discusses how to check whether agents' behaviour complieswith the rules regulating them. The key point of our approach isthat compliance is a relationship between two sets ofspecifications: the specifications for executing a process and thespecifications regulating it. We propose a formalism fordescribing both the semantics of normative specifications and thesemantics of compliance checking procedures.

2nd Workshop on Logics for Intelligent Agents and Multi-Agent Systems (WLIAMAS 2009)-15 September 2009

Probability representation and statistical models in phylogenetic trees.

Tue, 09 Mar 2010 00:00:00 +0000

Authors: J.F. Weng, I. Mareels, D. Thomas

Evolution- The Experience-February 2009

Repetition-Based Compression of Large DNA Datasets.

Tue, 09 Mar 2010 00:00:00 +0000

Authors: S. Kuruppu, B. Beresford-Smith, T. Conway, J. Zobel

ausbiotech2009-December 2009

Reference-Free Validation of Short Read Data

Tue, 09 Mar 2010 00:00:00 +0000

Authors: J. Schroder, J. Bailey, T. Conway, J. Zobel

NICTA-March 2010

Relative Lempel-Ziv Parsing for Storing and Accessing Similar Genomes.

Tue, 09 Mar 2010 00:00:00 +0000

Authors: S. Kuruppu, S. Puglisi, J. Zobel

Abstract: This report is a description of the relative LZ-based compression algorithm RLZ that compresses a set of similar sequences against a selected reference sequence in a space efficient manner while providing fast access to the sequence collection.

NICTA-December 2009

Exploring Classification Techniques in Speech based Cognitive Load Monitoring

Mon, 08 Mar 2010 00:00:00 +0000

Authors: Bo Yin, Natalie Ruiz, Fang Chen, Eliathamby Ambikairajah

Abstract: The ability to monitor cognitive load level in real time is extremely useful for preventing fatal operating errors or improving the efficiency of task execution. In top of the success of our previously proposed speech based cognitive load monitoring system, we explored alternative classification techniques in this paper, including simple linear kernel Support Vector Machine (SVM), hybrid SVM-GMM which accepts the likelihood scores from GMM as inputs for SVM, and a fusion approach which integrates GMM, SVM and SVM-GMM systems together. All systems are evaluated on the data collected from two different tasks– a reading comprehension and a Stroop test based task. SVM-GMM based system achieves the highest performance on both tasks and improves the accuracy of three cognitive load levels classification from 71.1% to 75.6% and 77.5% to 88.2%, respectively.

InterSpeech-September 2008

Introducing FM based Feature to Hierarchical Language Identification

Mon, 08 Mar 2010 00:00:00 +0000

Authors: Bo Yin, Tharmarajah Thiruvaran, Eliathamby Ambikairajah, Fang Chen

Abstract: Although relatively neglected in auditory analysis, phase information plays an important role in human auditory intelligibility. This paper investigates a Frequency Modulation (FM) based feature and its contribution to a Language Identification (LID) system, using Hierarchical LID framework. FM components represent the phase information of a given signal in an AM-FM model. In this paper, we extract a FM-based feature using a technique which produces consistent and continuous FM components, and build a LID system on this feature with GMM based modeling. The performance is improved by combining this system with existing MFCC, Prosody based systems and a PRLM system. Comparing to the baseline system without integrating a FM-based system, the proposed Hierarchical LID system shows improvements. Additionally, the proposed system outperforms the GMM fusion-based system integrating the same four primary systems, showing that Hierarchical LID framework is more effective in integrating additional features.

InterSpeech-September 2008

Developing a Smart Camera for Road Traffic Surveillance

Mon, 08 Mar 2010 00:00:00 +0000

Authors: Bei Na Wei, Yu Shi, Getian Ye, Jie Xu

Abstract: This paper discussesin details a hardware implementation of a real-time object tracking algorithm based Harris keypoint detection technique. VHDL design using an FPGA development platform is the development environment. Preliminary results have shown promising real-time performance and tracking accuracy. The targeted application is a smart camera for road traffic flow analysis.

International Workshop on Multimedia Signal Processing-October 2008

Think before you talk: An empirical study of Relationship between Speech pauses and Cognitive load

Mon, 08 Mar 2010 00:00:00 +0000

Authors: M. Asif Khawaja, Natalie Ruiz, Fang Chen

Abstract: Measuring a user’s level of cognitive load while they are interacting with the system could offer another dimension to the development of adaptable user interfaces. High levels of cognitive load affect performance and efficiency. However, current methods of measuring cognitive load are physically intrusive and interrupt the task flow. Certain speech features have been shown to change under high levels of load and are good candidates for cognitive load indices for usability evaluation and automatic adaptation of an interface or work environment. A speech-based dual-task user study is presented in which we explore the behaviour of speech pause features in natural speech. The experiment yielded new results confirming that speech pauses are useful indicators of high load versus low load speech. We report an increase in the percentage of time spent pausing from low load to high load tasks. We interpret these results within the framework of Baddeley’s modal model of working memory and detail how such a measure could be utilized in the cognitive load measurement.

OzCHI 2008-December 2008

An Efficient Unification-based Multimodal Language Processor for Multimodal Input Fusion

Mon, 08 Mar 2010 00:00:00 +0000

Authors: Fang Chen, Yong Sun

Abstract: Multimodal User Interaction technology aims at building natural and intuitive interfaces allowing a user to interact with computer in a way similar to human-to-human communication, for example, through speech and gestures. As a critical component in a multimodal user interface, Multimodal Input Fusion explores ways to effectively derive the combined semantic interpretation of user inputs through multiple modalities. Based on state of art review on multimodal input fusion approaches, this chapter presents a novel approach to multimodal input fusion based on speech and gesture; or speech and eye tracking. It can also be applied for other input modalities and extended to more than 2 modalities. It is the first time that a powerful combinational categorical grammar is adopted in multimodal input fusion. The effectiveness of the approach has been validated through user experiments, which indicated a low polynomial computational complexity while parsing versatile multimodal input patterns. It is very useful for mobile context. Future trends in multimodal input fusion will be discussed at the end of this chapter.

Handbook of Research on Multimodal Human Computer Interaction and Pervasive Services: Evolutionary Techniques for Improving Accessibility-May 2009

VOICED/UNVOICED PATTERN-BASED DURATION MODELING FOR LANGUAGE IDENTIFICATION

Mon, 08 Mar 2010 00:00:00 +0000

Authors: Bo Yin, Eliathamby Ambikairajah, Fang Chen

Abstract: As a major prosodic feature, duration-based features have been explored in related areas but the existing approaches require manually annotated corpus to train the segmentation models, which may be cost and time-consuming. In this paper, a novel duration modeling approach is proposed, in which the segmentation is implemented by using articulatory feature like voicing status. A pair of connected unvoiced and voiced segments is considered as the unit, and the duration of each segment is normalized for each utterance and then quantized into 20 discrete ranges. The ranges of units are later considered as symbol sequences and are modeled by n-gram model, to capture the temporal pattern, which is hypothesized to be different in different languages. The experiments based on the NIST LRE 2005 tasks show a relative 19.7% EER improvement by introducing the proposed duration modeling-based system into a fusion system containing two GMM-UBM based acoustic systems using MFCC and pitch+intensity features.

ICASSP-April 2009

Language-dependent Contribution Measuring and Weighting for Combining Likelihood Scores in Language Identification Systems

Mon, 08 Mar 2010 00:00:00 +0000

Authors: Bo Yin, Eliathamby Ambikairajah, Fang Chen

Abstract: Developing a fusion-based system is one of the key research issues in modern Language Identification (LID) systems. In this paper we investigate existing fusion techniques for LID systems and propose an alternative solution.By directly utilizing language-dependent contribution information, a novel Language-Dependent Weighting approach is introduced and implemented. We investigate various contribution measures, including LID performances, likelihood ratios, and Kullback-Leibler divergence. These measures are conducted from either development datasets or class models. The advantage of using language-dependent weighting over language-independent weighting is illustrated using a Language-Dependent Contribution Map. Both the OGI and CallFriend databases show a very similar contribution pattern which is related to language characteristics. Experiments on the NIST LRE 2003 task and OGI database demonstrate that the proposed fusion technique outperforms other recent fusion techniques when the amount of available development data is limited. In particular, the system based on Kullback-Leibler divergence achieved the best performance while eliminating the need for development data

Journal of Signal Processing Systems

Skipping Spare Information in Multimodal Inputs during Multimodal Input Fusion

Mon, 08 Mar 2010 00:00:00 +0000

Authors: Yong Sun, Yu Shi, Fang Chen, Vera Chung

Abstract: In a multimodal interface, a user can use multiple modalities, such as speech, gesture, and eye gaze etc., to communicate with a system. As a critical component in a multimodal interface, multimodal input fusion explores the ways to effectively interpret the combined semantic interpretation of user’s multimodal inputs. Although multimodal inputs may contain spare information, few multimodal input fusion approaches have tackled this issue. This paper proposes a novel multimodal input fusion approach to flexibly skip spare information in multimodal inputs and derive semantic interpretation ofthem. The experiment confirms that the proposed approach makes human-computer interaction more natural and smooth.

IUI 2009-2 2009

Building a Practical Multimodal Interface with a Multimodal Fusion Module

Mon, 08 Mar 2010 00:00:00 +0000

Authors: Yong Sun, Yu Shi, Fang Chen, Vera Chung

Abstract: See uploaded file

HCII 2009-7 2009