- Date:
- 2009-
- Themes:
- Low-Energy Sustainable Systems, Systems Design, Model-Based Verification, Formal Methods, Low-Energy Sustainable Systems, Low-Energy Sustainable Systems
The advent of low-cost, low-power multi-core systems provides the opportunity to exploit the parallelism offered by such systems. However, even if high-level programming models are provided to exploit this parallelism, it is important that the underlying memory-model supports parallel programming in an efficient way. It is also important that the memory model is rigorously defined to facilitate the proper verification of parallel applications.
The memory model defines behaviours of transactions between the memory and the processor. For a uniprocessor system, microarchitectures like out-of-order execution, speculative execution, forwarding and cache hierarchy could effectively increase the performance of systems. For a multiprocessor system with shared memory, such techniques may easily break the sequential consistency in a multi-thread programme and result in unexpected execution. Therefore, weak memory models introduce barrier (fence) instructions to keep the sequential consistency while maintain the optimized system performance by using those techniques. And the verification of the system becomes an important issue to ensure the system behaviours as expected. However, the verification of weak memory models is inefficient by using simulation-based approach. So the formal method-based verification approach is investigated.
Formal methods are mathematical based technique to model and verify software and hardware systems by using model checking and theorem proving [1]. Event-b is one of formal methods which are based on set theory for system-level modelling and analysis. In Event-b, a chain of refinements is used to represent the system at different abstraction levels. With the support of Rodin platform, the consistency of two levels of refinement could be verified by using automated mathematical proof [2]. This project aims to develop weak memory models formally within multiprocessor shared-memory systems in Event-b and to evaluate performance of systems with weak memory models.
References: [1] Neil Storey, Safety-Critical Computer Systems, Pearson Education Limited, Bath, UK,1996 [2] Event-B,http://www.event-b.org/
Primary investigators
- fl1e08
- jlc05r
Secondary investigator
Associated research group
- Electronics and Electrical Engineering
- Date:
- 2008-
- Themes:
- Low-Energy Sustainable Systems, Systems Design
With CMOS transistor size scaling leakage power consumption becomes an increasing problem for electronics system design. Mobile devices spend most of their time in idle mode. Idle circuit power consumption has high impact on the battery life of these devices, which will limit their applications. Low power design techniques such as power gating and supply voltage scaling were proposed to reduce leakage power. However these techniques introduce noises to a system and makes it more susceptible to errors. There are three important design parameters in an pervasive system: performance, power consumption and reliability. Higher performance enables more sophisticated applications, low power consumption prolongs the battery life and high reliability is a necessary requirement for critical tasks. The aim of this project is to provide low cost and effective circuit design techniques to improve the reliability of low power designs.
Primary investigator
- sy08r
Secondary investigators
- Professor David Flynn
- Bashir Al-Hashimi
- Dr. Harry Oldham
- Sachin Idgunji
Partner
- ARM
Associated research groups
- Pervasive Systems Centre
- Electronic Systems and Devices Group
- Electronics and Electrical Engineering
- Date:
- 2007-
- Themes:
- Healthcare, Wireless Sensing and Sensor Networks, Healthcare in ECS
- Funding:
- EPSRC
Recent advancements in wireless communication and wireless sensor network have opened up significant opportunity in futuristic healthcare and heath monitoring system development. Using sophisticated sensors and the wireless communication infrastructure monitoring a patient on a continuous basis will be feasible in the future. Typically such a system can be viewed as a layered structure consisting of 1) intelligent sensors layer, 2) network layer and 3) service layer. In the first layer a set of sensors (wearable or environmental) are deployed for collecting the vital signs of the patient under monitoring. These collected data are transmitted via the network layer to a central facility. WLAN/cellular/GSM/3G network could be used for serving this purpose. In the service layer the central facility processes these data to check for any abnormality of the received vital sign signals and accordingly the appropriate healthcare service is informed to take immediate action. Although very effective this structure faces the problem of transmission of huge amount of data over the network layer and effective management of the data at the central facility. The quality of transmitted medical data cannot be compromised by any means by using compression techniques since this may lead to false information about the condition of the patient under monitoring. Thus the main research effort has been dedicated to improve the quality and bandwidth in the network layer. Additionally maintenance of the data in the central facility needs intelligent database development.
We envisage that a way out is to add intelligent processing circuitry in the sensor layer itself which can monitor the patientââ¬â¢s vital signs on a continuous basis and only transmit the signal to the central facility when it finds a departure of the vital signââ¬â¢s pattern from the regular pattern. The raw medical data can be stored in a local computer using home wireless infrastructure. This approach reduces the burden on the network layer significantly. If required, the central facility can call for the raw data stored in the home computer over the network layer. However, processing the vital signs on a continuous basis is an extremely challenging problem in signal processing. Although there are several techniques developed for processing these data, they are very much computationally intensive and thus require significant amount of power. But in a wireless sensor network the biggest problem is the power and area. Thus these techniques are not likely to be suitable for embedding the associated circuitry within the sensor layer. To materialise our envisaged system, it is necessary to reduce the complexity of the required signal processing tasks (ââ¬Ålight-weight signal processingââ¬?) and associated architectural optimisation in such a way that each of the processing circuit consumes as small power as possible. In the extreme case we envisage that the circuits may work through energy harvesting.
Keeping this fact in mind we have initiated a research project for development of signal processing algorithms and associated ultra low-power architecture development for separating ââ¬Åaââ¬? vital sign signal from composite of similar kind of signals. This is a typical scenario when environmental sensors are used to monitor a patient who is visited by his/her relatives/friends. In this case the environmental sensor will receive a composite signal of several similar kinds of vital sign signals from which the circuit embedded in the sensor need to separate the only ââ¬Ånecessaryââ¬? signal corresponding to the person under monitoring. Since the person under monitoring can be mobile (within the room) it also needs to track the person on a continuous basis. The main challenge in this case is to find a clever algorithm of reduced complexity and associated ultra low-power architecture development.
We would like to continue this work in this area since this leads to joint algorithm-circuit optimisation which eventually enables us to develop ââ¬Årealââ¬? pervasive healthcare system satisfying the stringent criteria of ââ¬Åpervasivenessââ¬?.
Primary investigator
- aa07r
Secondary investigators
Associated research groups
- Pervasive Systems Centre
- Electronic Systems and Devices Group
- Electronics and Electrical Engineering
- Date:
- 2010-2010
- Themes:
- Digital Libraries, Web Science
- Funding:
- JISC
Open Impact is a project to help collect evidence about the impact of research that has been undertaken in UK universities and to provide it to a range of stakeholders (government, funders, press etc) through an independent third party agency (a learned society). The project focuses on a specific discipline (Computer Science) mediated through a particular society (the British Computer Society). In particular, this project will produce software that helps to make institutional repositories effective in collecting evidence of the impact of their institutionsââ¬â¢ research ââ¬â evidence that justifies the investment that government and research funders have made and that promotes the role of Universities in society.
Primary investigators
Partner
- British Computer Society
Associated research group
- Intelligence, Agents, Multimedia Group
- Date:
- 2010-2010
- Theme:
- Innovation in Science, Engineering and Technology Education
- Funding:
- JISC
Developments in ePortfolios enable greater power and flexibility in displaying achievements. Current initiatives side-step the problem of inter-institutional certification rather than dealing with it. Although proprietary solutions are starting to appear, they tend to be organisation- rather than user- centric.
This project seeks to address the issue of design for a suitable user-centric "eCertificate" system by working with representatives of the community to establish use case scenarios, to verify this design by building a demonstrator, and then by testing the demonstrator within the group. The demonstrator will be based on a code library which will be developed, and both will be placed in the public domain.
Primary investigator
Secondary investigators
- lcw07r
- tg2
- Gary Wills
- Lester Gilbert
- Andrew Gravell
Associated research groups
- Learning Societies Lab
- Electronic and Software Systems
- Date:
- 2009-
- Themes:
- Wireless Networking, Multimedia Source Compression, Pervasive Computing and Networks, Algorithms for Wireless Sensor Networks, Novel Sensors, Healthcare in ECS, Pervasive Healthcare and Telemedicine, Low-Energy Sustainable Systems
Body Area Wireless Sensor Networks (BAWSNs) have numerous applications. These typically involve the sensing of physiological data in a number of sensor nodes placed at various points on the body, the communication of this data to a central node and the use of intelligence algorithms to make decisions on the basis of the data. The sensor nodes are required to be small and light, preventing the use of bulky batteries. In order to maximise the length of time for which the sensor nodes can operate without requiring recharging, their energy consumption must be minimised. There are two main causes of sensor node energy consumption, namely the processing of data and the transmission of data. Clearly, reducing the amount of data that is processed and transmitted by a node can be reduce the energy consumption. However, there is typically a trade-off between the amount of data that is processed by a node and the amount of data that it transmits. For example, distributed intelligence and compression algorithms can be used to reduce the amount of data that is transmitted by a node, at the cost of increasing the amount of data processing performed. Furthermore, the contributions of sensing, communication and intelligence are inherently linked. For example, distributed intelligence algorithms require the communication of data between the sensor nodes that are involved in making decisions. Therefore this project aims to jointly consider the sensing, communication and intelligence of BAWSNs in order to strike attractive trade-offs between the processing and communication requirements of sensor nodes.
Primary investigator
- nw7g08
Secondary investigators
Associated research groups
- Pervasive Systems Centre
- Electronic Systems and Devices Group
- Electronics and Electrical Engineering
- Intelligence, Agents, Multimedia Group
- Date:
- 2008-
- Themes:
- Communication and Networking, Wireless Networking, Channel coding, Pervasive Healthcare and Telemedicine, Healthcare in ECS, Low-Energy Sustainable Systems
There is demand for Body Area Wireless Sensor Networks (BAWSNs) in which the sensor nodes are small and light, preventing the use of bulky batteries. In order to maximise the length of time that the sensor nodes can operate without being recharged, their energy consumption needs to be minimised. Since the energy consumed when transmitting has a significant contribution to the energy consumption of typical wireless sensor nodes, it is desirable to consider sophisticated error correction schemes, which allow reliable communications to be maintained when the transmission energy per data bit is reduced significantly. However, these error correction schemes are associated with some processing complexity, which consumes energy and erodes the transmission energy savings that are afforded. This project aims to analyse the processing energy consumption associated with sophisticated error correction schemes, allowing the optimal trade-off between processing energy and transmission energy to be found. In this way, the net energy consumption of wireless sensor nodes can be minimised.
Primary investigator
- ll08r
Secondary investigators
Associated research groups
- Pervasive Systems Centre
- Communications Research Group
- Electronic Systems and Devices Group
- Electronics and Electrical Engineering
Embedded systems based on system-on-chip (SoC) are making their way into more and more devices, from household appliances to hand-held devices, from satellite applications to automobiles, sensors, etc. Since many of these systems are battery powered, power consumption is a prime design issue to extend battery life. Also, to optimize system performance the design of efficient on-chip communication architecture is a crucial design requirement.
An emerging requirement of the current and the future SoCs is the ability to operate in the presence of soft errors caused by radiation. However, addressing the power minimization and reliability improvement simultaneously is difficult because lowering voltage to reduce power consumption has been reported to exponentially increase the number of transient faults or soft errors. Such power reduction also causes degradation of system performance as operating frequency is also reduced. Therefore, with increasing complexity of applications and short time-to-market requirements, the design of low power, efficient and reliable system is a truly challenging task.
The aim of this project is to develop efficient on-chip communication architectures for multiprocessor SoCs and to devise system-level design techniques, which are able to simultaneously meet both low power consumption and reliability requirements. The impact of soft errors on reliability is investigated at application-level rather than at architectural-level. Based on the investigation, novel power minimization technique has been developed meeting a specified acceptable-level reliability and real-time performance for a given soft error rate. Furthermore, the impact of application system tasks mapping on reliability has been studied. Underpinning this study, a novel design optimization technique has been developed to jointly minimize power consumption through voltage scaling and the number of soft errors experienced through application task mapping. The effectiveness of the proposed techniques is evaluated using different applications, including MPEG-2 video decoder and random task graphs.
Primary investigator
Secondary investigator
- ras06r
Associated research group
- Pervasive Systems Centre
- Date:
- 2009-2012
- Themes:
- Web Science, Knowledge Technologies, Decentralised Information Systems
- Funding:
- EPSRC (EP/G008493/1)
The EPSRC funded Advanced Knowledge Technologies Interdisciplinary Research Collaboration (AKT IRC) has been a significant success in terms of papers published, grants awarded, students trained, and international impact. The Review Panel rated the project as "outstanding" scoring 34 out of a maximum possible 35 on the seven review criteria used to assess the results of projects by the EPSRC. The purpose of this proposal is to take some of the most important results from AKT and organise a next stage of research. This in turn will serve as a precursor to a longer-term ambition; the establishment of Web Science as a discipline. This initiative we are undertaking with the Web's inventor Professor Sir Tim Berners-Lee and MIT.
The development of new Semantic Web technologies (many developed and researched in the AKT IRC) points to a new generation of Web capability that can explore and query, assemble and integrate content in a context-aware, focused fashion. The basic idea is that we move from a document centric view of the Web to one in which data and information are the principle objects of interest. This data may relate to people, scientific structures, financial transactions or any domain that can be represented on the Web.
With the emergence of a Web of data it is essential to address three key research problems; (1) how to build ontologies quickly that are capable of exploiting the potential of large-scale user participation, (2) how we query an unbounded web of linked data, (3) how to visualise, explore, browse and navigate this mass of data.
The proposal is to undertake fundamental research in the areas 1-3 identified above. This fundamental research is supported via two application domains; one in the area of public sector information, a second in the domain of transport. The application domains will provide the context in which to gather realistic requirements, understand the social aspects that determine the success or otherwise of the systems constructed, test the adequacy of solutions, and showcase the promise of the results obtained in pursuing the research objectives outlined.
Primary investigator
Secondary investigators
- timbl
- Nicholas Gibbins
- Wendy Hall
- monica schraefel
- gc3
- Ian Charles Millard
- ms8
- Temitope Omitola
- clk08r
- ip2g09
- yy1402
- Hugh Glaser
Associated research groups
- Intelligence, Agents, Multimedia Group
- Agents, Interaction and Complexity
- Web and Internet Science
- Date:
- 2009-2010
- Theme:
- Accessible Technologies
- Funding:
- (Computer Aid International)
The project aim is to produce an open source Windows based screen magnifier that will run from a USB pen drive and work in line with the NonVisual Desktop Access (NVDA) free and open source screen reader for use by visually impaired users.
Although magnification in various forms is available on Windows XP and Vista with complete screen magnification on Windows 7 it is felt that these systems do not offer a portable solution with links to an open source screen reader or such options as:
- Invert on screen colours for better contrast, providing users with multiple colour combinations to choose from for text, foreground and background.
- Font smoother
- Level of magnification: fractional magnification
- Full Screen Magnification
- Magnifying Lens
- Strip Magnifier
- Vertical and Horizontal Split Screens
- Ability of visualising the mouse pointer in the magnified area (and changing its colour/size)
- Ability to use the mouse in the magnified area
This project will build on the work of the LATEU funded Access Tools with the accessible USB pen drive menu and inclusion of other free and open source applications.
Primary investigators
Secondary investigators
- Sebastian Skuse
- jc1
- mc5
Associated research group
- Learning Societies Lab