Update - Sep 2013

I have recently moved to the University of Kent, UK as a Lecturer (Assistant Professor) in Ubiquitous computing, at the School of Engineering and Digital Arts.
I am looking for good research students to work on people-centric and mobile sensing, internet of things, and wireless sensor networks. If you are interested, please feel free to contact me.

Please, check my page there for recent updates: http://ce208.staff.eda.kent.ac.uk

Publications

There are about citations in this body of work according to Google Scholar.
Citation counts for individual papers are provided where greater than 5 (counts are dynamicaly updated through Google Scholar).

2014

  1. Tracking serendipitous interactions: How individual cultures shape the office
    C. Brown, C. Efstratiou, I. Leontiadis, D. Quercia, C. Mascolo
    In Proceedings of the ACM Conference on Computer Supported Cooperative Work and Social Computing (CSCW 2014). Baltimore, Maryland, USA. February 2014.
    @inproceedings{bro14a,
    title={Tracking serendipitous interactions: How individual cultures shape the office},
    author={C. Brown and C. Efstratiou and I. Leontiadis and D. Quercia and C. Mascolo},
    booktitle={Proceedings of the ACM Conference on Computer Supported Cooperative Work and Social Computing (CSCW 2014)},
    year=2014,
    location={Baltimore, Maryland, USA},
    month={February}
    }

2013

  1. ParkSense: A Smartphone Based Sensing System For On-Street Parking
    S. Nawaz, C. Efstratiou, C. Mascolo
    In Proceedings of the 19th ACM International Conference on Mobile Computing and Networking (MOBICOM 2013). Miami, FL. USA. September 2013.
    Abstract
    Studies of automotive traffic have shown that on average 30% of traffic in congested urban areas is due to cruising drivers looking for parking. While we have witnessed a push towards sensing technologies to monitor real-time parking availability, instrumenting on-street parking throughout a city is a considerable investment. In this paper, we present ParkSense, a smartphone based sensing system that detects if a driver has vacated a parking spot. ParkSense leverages the ubiquitous Wi-Fi beacons in urban areas for sensing unparking events. It utilizes a robust Wi-Fi signature matching approach to detect driver’s return to the parked vehicle. Moreover, it uses a novel approach based on the rate of change of Wi-Fi beacons to sense if the user has started driving. We show that the rate of change of the observed beacons is highly correlated with actual user speed and is a good indicator of whether a user is in a vehi- cle. Through empirical evaluation, we demonstrate that our approach has a significantly smaller energy footprint than traditional location sensors like GPS and Wi-Fi based posi- tioning while still maintaining sufficient accuracy.
    @inproceedings{naw13a,
    title={ParkSense: A Smartphone Based Sensing System For On-Street Parking},
    author={S. Nawaz and C. Efstratiou and C. Mascolo},
    booktitle={Proceedings of the 19th ACM International Conference on Mobile Computing and Networking (MOBICOM 2013)},
    year=2013,
    location={Miami, FL, USA},
    month={September}
    }
  2. METIS: Exploring mobile phone sensing offloading for efficiently supporting social sensing applications
    Mark Weiser's Best Paper Award
    K. Rachuri, C. Efstratiou, I. Leontiadis, C. Mascolo, P. Rentfrow
    In Proceedings of the IEEE International Conference on Pervasive Computing and Communications (PERCOM 2013). San Diego, California, March 2013.
    Abstract
    Mobile phones play a pivotal role in supporting ubiquitous and unobtrusive sensing of human activities. However, maintaining a highly accurate record of a user’s behavior throughout the day imposes significant energy demands on the phone's battery. In this paper, we present the design, implementation, and evaluation of METIS: an adaptive mobile sensing platform that efficiently supports social sensing applications. The platform implements a novel sensor task distribution scheme that dynamically decides whether to perform sensing on the phone or in the infrastructure, considering the energy consumption, accuracy, and mobility patterns of the user. By comparing the sensing distribution scheme with sensing performed solely on the phone or exclusively on the fixed remote sensors, we show, through benchmarks using real traces, that the opportunistic sensing distribution achieves over 60% and 40% energy savings, respectively. This is confirmed through a real world deployment in an office environment for over a month: we developed a social application over our frameworks, that is able to infer the collaborations and meetings of the users. In this setting the system preserves over 35% more battery life over pure phone sensing.
    @inproceedings{rac13a,
    title={METIS: Exploring mobile phone sensing offloading for efficiently supporting social sensing applications},
    author={K. Rachuri and C. Efstratiou and I. Leontiadis and C. Mascolo and P. Rentfrow},
    booktitle={Proceedings of the IEEE International Conference on Pervasive Computing and Communications (PERCOM 2013)},
    year=2013,
    month={March}
    }

2012

  1. Social Sensing in the Field: Challenges in Detecting Social Interactions in Construction Sites
    S. Nawaz, C. Efstratiou, C. Mascolo, K. Soga
    In Proceedings of the 1st ACM Workshop on Mobile Systems for Computational Social Science (in conjunction with MOBISYS'12). Lake District, UK. June 2012.
    Abstract
    Construction industry is a sector that is renowned for the slow uptake of new technologies. This is usually due to the conservative nature of this sector that relies heavily on tried and tested and successful old business practices. However, there is an eagerness in this industry to adopt Building Information Modelling (BIM) technologies to capture and record accurate information about a building project. But vast amounts of information and knowledge about the construction process is typically hidden within informal social interactions that take place in the work environment. In this paper we present a vision where smartphones and tablet devices carried by construction workers are used to capture the interaction and communication between workers in the field. Informal chats about decisions taken in the field, impromptu formation of teams, identification of key persons for certain tasks, and tracking the flow of information across the project community, are some pieces of information that could be captured by employing social sensing in the field. This information can not only be used during the construction to improve the site processes but it can also be exploited by the end user during maintenance of the building. We highlight the challenges that need to be overcome for this mobile and social sensing system to become a reality.
    @inproceedings{naw12a,
    title={Social Sensing in the Field: Challenges in Detecting Social Interactions in Construction Sites},
    author={S. Nawaz and C. Efstratiou and C. Mascolo and K. Soga},
    booktitle={Proceedings of the 1st ACM Workshop on Mobile Systems for Computational Social Science (in conjunction with MOBISYS'12)},
    location={Lake Distrikt, UK},
    month={June},
    year=2012
    }
  2. Collecting Big Datasets of Human Activity One Checkin at a Time
    T. Hossmann, C. Efstratiou, C. Mascolo
    In Proceedings of the 4th ACM International Workshop on Hot Topics in Planet-Scale Measurement (HOTPLANET'12 in conjunction with MOBISYS'12). Lake District, UK. June 2012.
    Abstract
    A variety of cutting edge applications for mobile phones exploit the availability of phone sensors to accurately infer the user activity and location to o er more e ective services. To validate and evaluate these new applications, appropriate and extensive datasets are needed: in particular, large sets of traces of sensor data (accelerometer, GPS, microphone, etc.), labelled with corresponding user activities. So far, such traces have only been collected in short-lived, small-scale setups. The primary reason for this is the diculty in establishing accurate ground truth information outside the laboratory. Here, we present our vision of a system for large-scale sensor data capturing, leveraging all sensors of todays smart phones, with the aim of generating a large dataset that is augmented with appropriate ground-truth information. The primary challenges that we address consider the energy cost on the mobile device and the incentives for users to keep running the system on their device for longer. We argue for leveraging the concept of the checkin – as successfully introduced in online social networks (e.g. Foursquare) – for collecting activity and context related datasets. With a checkin, a user deliberately provides a small piece of data about their behaviour while enabling the system to adjust sensing and data collection around important activities. In this work we present up2, a mobile app letting users check in to their current activity (e.g., "waiting for the bus", "riding a bicycle", "having dinner"). After a checkin, we use the phone's sensors (GPS, accelerometer, microphone, etc.) to gather data about the user's activity and surrounding. This makes up2 a valuable tool for research in sensor based activity detection.
    @inproceedings{the12a,
    title={Collecting Big Datasets of Human Activity One Checkin at a Time},
    author={T. Hossmann and C. Efstratiou and C. Mascolo},
    booktitle={Proceedings of the 4th ACM International Workshop on Hot Topics in Planet-Scale Measurement (HOTPLANET'12 in conjunction with MOBISYS'12)},
    location={Lake Distrikt, UK},
    month={June},
    year=2012
    }
  3. Sense and Sensibility in a Pervasive World
    C. Efstratiou, I. Leontiadis, M. Picone, K. Rachuri, C. Mascolo, J. Crowcroft
    In Proceedings of 10th International Conference on Pervasive Computing (PERVASIVE 2012). Newcastle, UK. June 2012.
    Abstract
    The increasing popularity of location based social services such as Facebook Places, Foursquare and Google Latitude, solicits a new trend in fusing social networking with real world sensing. The availability of a wide range of sensing technologies in our everyday environment presents an opportunity to further enrich social networking systems with fine-grained real-world sensing. However, the introduction of passive sensing into a social networking application disrupts the traditional, user-initiated input to social services, raising both privacy and acceptability concerns. In this work we present an empirical study of the introduction of a sensor-driven social sharing application within the working environment of a research institution. Our study is based on a real deployment of a system that involves location tracking, conversation monitoring, and interaction with physical objects. By utilizing surveys, interviews and experience sampling techniques, we report on our findings regarding privacy and user experience issues, and significant factors that can affect acceptability of such services by the users. Our results suggest that such systems deliver significant value in the form of self reflection and comparison with others, while privacy concerns are raised primarily by the limited control over the way individuals are projected to their peers.
    @inproceedings{efs12a,
    title={Sense and Sensibility in a Pervasive World},
    author={C. Efstratiou and I. Leontiadis and M. Picone and K. Rachuri and C. Mascolo and J. Crowcroft},
    booktitle={Proceedings of 10th International Conference on Pervasive Computing (PERVASIVE 2012)},
    location={Newcastle, UK},
    month={June},
    year=2012
    }
  4. Reflections on Long-Term Experiments with Public Displays
    A. Friday, N. Davies, C. Efstratiou
    IEEE Computer, vol 45, no 5. May, 2012.
    Abstract
    A reflection on the authors' experiences with public display research – systems built and lessons learned – explores content creation and control, programmable infrastructures, and applications, to offer unique insights for those considering research or practical deployments using this technology.
    @article{dav12a,
    title={Reflections on Long-Term Experiments with Public Displays},
    author={A. Friday and N. Davies and C. Efstratiou},
    journal={IEEE Computer},
    vol=45,
    number=5,
    pages={34--41},
    month={May},
    year=2012
  5. Don't kill my ads! Balancing Privacy in an Ad-Supported Mobile Application Market
    I. Leontiadis, C. Efstratiou, M. Picone, C. Mascolo
    In Proceedings of 13th International Workshop on Mobile Computing Systems and Applications (HOTMOBILE 2012), San Diego, California, February, 2012.
    Abstract
    Application markets have revolutionized the software download model of mobile phones: third-party application developers offer software on the market that users can effortlessly install on their phones. This great step forward, however, also imposes some threats to user privacy: applications often ask for permissions that reveal private information such as the user’s location, contacts and messages. While some mechanisms to prevent leaks of user privacy to applications have been proposed by the research community, these solutions fail to consider that application markets are primarily driven by advertisements that rely on accurately profiling the user. In this paper we take into account that there are two parties with conflicting interests: the user, interested in maintaining their privacy and the developer who would like to maximize their advertisement revenue through user profiling. We have conducted an extensive analysis of more than 250,000 applications in the Android market. Our results indicate that the current privacy protection mechanisms are not effective as developers and advert companies are not deterred. Therefore, we designed and implemented a market-aware privacy protection framework that aims to achieve an equilibrium between the developer’s revenue and the user’s privacy. The proposed framework is based on the establishment of a feedback control loop that adjusts the level of privacy protection on mobile phones, in response to advertisement generated revenue.
    @inproceedings{leo12b,
    title={Don't kill my ads! Balancing Privacy in an Ad-Supported Mobile Application Market},
    author={I. Leontiadis and C. Efstratiou and M. Picone and C. Mascolo},
    booktitle={Proceedings of 13th International Workshop on Mobile Computing Systems and Applications (HOTMOBILE 2012)},
    location={San Diego, CA},
    month={February},
    year=2012
    }
  6. SenShare: Transforming sensor networks into multi-application sensing infrastructures
    I. Leontiadis, C. Efstratiou, C. Mascolo, J. Crowcroft
    In Proceedings of European Conference on Wireless Sensor Networks (EWSN 2012), Trento, Italy, February, 2012.
    Abstract
    Sensor networks are typically purpose-built, designed to sup- port a single running application. As the demand for applications that can harness the capabilities of a sensor-rich environment increases, and the availability of sensing infrastructure put in place to monitor various quantities soars, there are clear bene ts in a model where infrastructure can be shared amongst multiple applications. This model however intro- duces many challenges, mainly related to the management of the commu- nication of the same application running on di erent network nodes, and the isolation of applications within the network. In this work we present SenShare, a platform that attempts to address the technical challenges in transforming sensor networks into open access infrastructures capa- ble of supporting multiple co-running applications. SenShare provides a clear decoupling between the infrastructure and the running application, building on the concept of overlay networks. Each application operates in an isolated environment consisting of an in-node hardware abstraction layer, and a dedicated overlay sensor network. We further report on the deployment of SenShare within our building, which presently supports the operation of multiple sensing applications, including oce occupancy monitoring and environmental monitoring.
    @inproceedings{leo12a,
    title={SenShare: Transforming sensor networks into multi-application sensing infrastructures},
    author={I. Leontiadis and C. Efstratiou and C. Mascolo and J. Crowcroft},
    booktitle={Proceedings of European Conference on Wireless Sensor Networks (EWSN 2012)},
    location={Trento, Italy},
    month={February},
    year=2012
    }
  7. Connected, computed, collective: Smart Mobilities
    M. Buscher, P. Coulton, C. Efstratiou, H. Gellersen, D. Hemment
    Book chapter in M. Grieco and J. Urry (eds) Mobilities: new perspectives on transport and society. Ashgate. 2012.
    @InCollection{bus12a,
    author = {M. Buscher and P. Coulton and C. Efstratiou and H. Gellersen and D. Hemment},
    title = {Connected, computed, collective: Smart Mobilities},
    booktitle = {Mobilities: new perspectives on transport and society},
    pages = {135--158},
    publisher = {Ashgate},
    year = 2012,
    editor = {M. Grieco and J. Urry}
    }
    Abstract
    The ‘smart’ in ‘Smart Transport’ usually refers to technologies, not people. From cars designed to be ‘stackable’, through signs that monitor parking spaces, to ‘automatic cruise control’ systems that ‘intelligently’ control distances through vehicle-to-vehicle and vehicle-to-infrastructure communication: technologies are key to smart transport. And it is true, people – armoured with status symbol cars and stuck in traffic – often do not behave intelligently, raging at other drivers and pedestrians, taking risks that endanger themselves and others. However, underestimating human intelligence could be a damaging oversight and missed opportunity for transport designers. In this chapter we examine several related aspects of human sense-making practices on the move and explore how these could be productively integrated with smart transport. Starting with a comparison of a ‘view from above’ and a ‘view from on the ground’, key aspects of the social logics of our mobile societies become visible. Then, new technologies are already an integral part of the social organisation of mobilities – with some socio-technical innovations that form a kind of parallel universe to the intelligent transport solutions envisaged by engineers and traffic planners. We discuss such ‘alternate smart mobilities’ through some utopian visions of ‘collective intelligence’ (Levy 1997) and its more mundane manifestations, including micro-coordination and an emergent digital economy of mobilities, based on crowdsourcing, community sensing, and data mashups. These ‘bottom-up’ innovations could come together productively with the pervasive ‘qualculation’ (Thrift 2004) that underpins traffic shaping and other engineering and design efforts around ‘intelligent transport systems’ (ITS) (COM 2008). Moreover, such a convergence of social and technological innovation could counteract the threat of ‘Orwellian’ surveillance that is part of a potentially Faustian bargain for more efficiency, convenience, sustainability and security in transport (Dennis and Urry 2009). We conclude with suggestions for mixed mobile research methods that can inform innovation.

2011

  1. Reflections on the Long-term Use of an Experimental Digital Signage System
    S. Clinch, N. Davies, A. Friday, C. Efstratiou
    In Proceedings of 13th ACM International Conference on Ubiquitous Computing (UBICOMP 2011), Beijing, China, September, 2011.
    Abstract
    In this paper we reflect on our long-term experiences of developing, deploying and supporting an experimental digital signage system. Existing public display systems almost always feature a single point of control that is responsible for scheduling content for presentation on the network and provide sophisticated mechanisms for controlling play-out timing and relative ordering. Our experiences suggest that such complex feature-sets are unnecessary in many cases and may be counter productive in signage systems. We describe an alternative, simpler paradigm for encouraging widespread use of signage systems based on shared ‘content channels’ between content providers and display owners. Our system has been in continuous use for approximately 3 years. We reflect and draw lessons from how our user community has adopted and used the resulting public display network. We believe that these reflections will be of benefit to future developers of ubiquitous display networks.
    @inproceedings{cli11a,
    title={Reflections on the Long-term Use of an Experimental Digital Signage System},
    author={S. Clinch and N. Davies and A. Friday and C. Efstratiou},
    booktitle={Proceedings of 13th ACM International Conference on Ubiquitous Computing (UBICOMP 2011)},
    location={Beijing, China},
    month={September},
    year=2011
    }
  2. Enabling Opportunistic Resources Sharing on Mobile Operating Systems: Benefits and Challenges
    N. Valina Rodriguez, C. Efstratiou, G. Xie, J. Crowcroft
    ACM S3 Workshop 2011 (in conjunction with MOBICOM 2011), Las Vegas, September, 2011
    @inproceedings{rod11a,
    title={Enabling Opportunistic Resources Sharing on Mobile Operating Systems: Benefits and Challenges},
    author={N. Valina Rodriguez and C. Efstratiou and G. Xie, J. Crowcroft},
    booktitle={ACM S3 Workshop 2011 (in conjunction with MOBICOM 2011)},
    location={Las Vegas},
    month={September},
    year=2011
    }
    Abstract
    The intense use of hardware resources by mobile applications has a significant impact on the battery life of mobile devices. In this paper we introduce a novel approach for the efficient use of mobile phone resources, by considering the coordinated sharing of resources offered by multiple co-located devices. Taking into account the social behaviour of users, there are frequent situations where similar resources are available by co-located mobile phones. In this work we discuss the feasibility of sharing such resources in an opportunistic way, the possible benefits and the research challenges that need to be addressed in order to implement a reliable and robust solution.

2010

  1. A Shared Sensor Network Infrastructure
    C. Efstratiou, I. Leontiadis, C. Mascolo, J. Crowcroft
    Demo Abstract in Proceedings of the 8th ACM Conference on Embedded Networked Sensor Systems (SENSYS 2010), Zurich, Switzerland, November 2010.
    Abstract
    An increasing number of sensor networks have been deployed to monitor a variety of conditions and situations. At the same time, more and more applications are starting to rely on the data from sensor networks to provide users with (near) real-time information and conditions. We argue that while ripe networking and duty cycling protocols for these networks exist, approaches to sensor network sharing and management are still immature. For example, the common approach to sensor network deployments is that one network serves a single application and often a single end-user. This approach can lead to inefficient use of resources and limits the potential for the implementation of new applications exploiting existing infrastructures. In this demonstration we present our initial efforts to the design of a sensor network architecture that supports sharing of network resources across multiple applications. The key characteristic of our approach is the virtualisation of hardware components on each sensor node, and the controlled access to these resources by multiple applications running on each node. Furthermore, our virtualisation runtime supports a range of hardware platforms (Imote2, smart-phones, laptops), offering a uniform application development API.
    @inproceedings{efs10a,
    title = {A Shared Sensor Network Infrastructure},
    author = {C. Efstratiou and I. Leontiadis and C. Mascolo and J. Crowcroft},
    booktitle = {Proceedings of the 8th ACM Conference on Embedded Networked Sensor Systems (SenSys 2010)},
    location = {Zurich, Switzerland},
    month = {November},
    year = {2010}
    }
  2. Challenges in Supporting Federation of Sensor Networks
    C. Efstratiou
    Position paper in NSF/FIRE Workshop on Federating Computing Resources, Princeton, NJ, May 11-12, 2010
    Abstract
    Wireless sensor networks are more and more seen as a solution to large-scale tracking and monitoring applications. However, existing networks are designed to serve a single application and deliver information to one authority; typically the owner of the network. This approach is clearly inefficient considering the high cost of deploying a sensor network. Supporting federation of sensor networks can allow the development of new applications that can access recourses offered by multiple existing sensor networks. This paper discusses the challenges in designing a platform for federated sensor networks.
    @misc{efs10a,
    title={Challenges in Supporting Federation of Sensor Networks},
    author={C. Efstratiou},
    howpublished={Position paper in NSF/FIRE Workshop on Federating Computing Resources, Princeton, NJ},
    month={May},
    year=2010
    }

2009

  1. Intelligent mobility systems: Some socio-technical challenges and opportunities.
    M. Buscher, P. Coulton, C. Efstratiou, H. Gellersen, D. Hemment, R. Mehmood and D. Sangiorgi.
    In Proceedings of EuropeComm 2009, London, August, 2009.
    Abstract
    Analysis of socio-technical challenges and opportunities around contemporary mobilities suggests new interpretations and visions for intelligent transport systems. Multiple forms of intelligence are required (but not easily compatible), transport is too narrow a term, and innovation results in new sociotechnical systems. An exploration of cumulative, collective and collaborative aspects of mobility systems, allows us to sketch challenges and opportunities in relation to practices of collaboration, communication and coordination, literacies for creativity, comfort and control, citizenship and (lack of) a sense of crisis, concluding with a discussion of methodological implications. Keywords: intelligent mobility systems, socio-technical, collaboration
    @inproceedings{bus09a,
    author = {M. Buscher and P. Coulton and C. Efstratiou and H. Gellersen and D. Hemment and R. Mehmood and D. Sangiorgi},
    title = {Intelligent mobility systems: Some socio-technical challenges and opportunities},
    booktitle = {Proceedings of EuropeComm 2009},
    location = {London},
    month = {August},
    year = {2009},
    abstract = {Analysis of socio-technical challenges and opportunities around contemporary mobilities suggests new interpretations and visions for intelligent transport systems. Multiple forms of intelligence are required (but not easily compatible), transport is too narrow a term, and innovation results in new sociotechnical systems. An exploration of cumulative, collective and collaborative aspects of mobility systems, allows us to sketch challenges and opportunities in relation to practices of collaboration, communication and coordination, literacies for creativity, comfort and control, citizenship and (lack of) a sense of crisis, concluding with a discussion of methodological implications.},
    file = {http://www.cl.cam.ac.uk/~ce291/papers/Buscher-et-al-EuropeComm-final.pdf}
    }

2008

  1. Constructing Ambient Intelligence
    Editors H. Gerhäuser, J. Hupp, C. Efstratiou and J. Heppner
    Proceeding of AmI 2008 Workshops, Nuremberg, Germany, 2008
    • Abstract
    • BibTex
    • PDF
    • Citations
    @proceedings{ger08a,
    booktitle = {Constructing Ambient Intelligence},
    series = {Communications in Computer and Information Science},
    editor = {Gerhäuser, Heinz and Hupp, Jürgen and Efstratiou, Christos and Heppner, Janina},
    publisher = {Springer Berlin Heidelberg},
    isbn = {978-3-642-10607-1},
    location={Darmstadt, Germany},
    month={November},
    year={2008}
    }
  2. Smart Design for Human Performance in the Office of the Future – Requirements towards Services and Technical Advises for Tomorrow's Office Work
    J. Kriegel, F. Jehle, C. Efstratiou, L. Zaad, J. Heppner and J. Hupp
    In Proceedings of Workshop in Constructing Ambient Intelligence, in conjunction with AmI 2008, Nuremberg, Germany, 2008
    Abstract
    The office of the future is a synonym of today’s needs and expectations towards prospective solutions and services which can support human performance in the future office work. The development of such future services is on one hand affected by the technical possibilities and on the other by the demands of changing and global work environment. The process of generating successful services can be initiated by creative methods. The 635 method is a creative brain writing technique, which follows the problem solving circle to create new uncommon ideas in a group of expert or user participants. The workshop on smart design for human performance in the office of the future used the 635 method to identify requirements towards services and technical advises for tomorrows office work. The outcome of the written brainstorming is a list of different criteria and examples which describe the several dimensions of needs and demands towards the office of the future.
    @incollection{kri08a,
    author = {J. Kriegel and F. Jehle and C. Efstratiou and L. Zaad and J. Heppner and J. Hupp},
    title = {Smart Design for Human Performance in the Office of the Future – Requirements towards Services and Technical Advises for Tomorrows Office Work},
    booktitle = {Constructing Ambient Intelligence},
    series = {Communications in Computer and Information Science},
    editor = {Gerhäuser, Heinz and Hupp, Jürgen and Efstratiou, Christos and Heppner, Janina},
    publisher = {Springer Berlin Heidelberg},
    isbn = {978-3-642-10607-1},
    keyword = {Computer Science},
    pages = {1-5},
    volume = {32},
    abstract = {The office of the future is a synonym of today’s needs and expectations towards prospective solutions and services which can support human performance in the future office work. The development of such future services is on one hand affected by the technical possibilities and on the other by the demands of changing and global work environment. The process of generating successful services can be initiated by creative methods. The 635 method is a creative brain writing technique, which follows the problem solving circle to create new uncommon ideas in a group of expert or user participants. The workshop on smart design for human performance in the office of the future used the 635 method to identify requirements towards services and technical advises for tomorrows office work. The outcome of the written brainstorming is a list of different criteria and examples which describe the several dimensions of needs and demands towards the office of the future.},
    year = {2009}
    }
  3. Exploring the Design of Pay-Per-Use Objects in the Construction Domain
    Best paper award
    D. Fitton, G. Kortuem, V. Sundramoorthy, J. Brown, C. Efstratiou, J. Finney and N. Davies.
    In Proceedings of EuroSSC 2008: Third European Conference on Smart Sensing and Context, Zurich, Switzerland, pp. 192–219, October, 2008. Springer.
    Abstract
    Equipment used in the construction domain is often hired in order to reduce cost and maintenance overhead. The cost of hire is dependent on the time period involved and does not take into account the actual use equipment has received. This paper presents our initial investigation into how physical objects augmented with sensing and communication technologies can measure use in order to enable new pay-per-use payment models for equipment hire. We also explore user interaction with pay-per-use objects via mobile devices. The user interactions that take place within our prototype scenario range from simple information access to transactions involving multiple users. This paper presents the design, implementation and evaluation of a prototype pay-per-use system motivated by a real world equipment hire scenario. We also provide insights into the various challenges introduced by supporting a pay-per-use model, including data storage and data security in addition to user interaction issues.
    @inproceedings{fit08a,
    author = {D. Fitton and G. Kortuem and V. Sundramoorthy and J. Brown and C. Efstratiou and J. Finney and N. Davies},
    title = {Exploring the Design of Pay-Per-Use Objects in the Construction Domain},
    booktitle = {Proceedings of EuroSSC 2008: Third European Conference on Smart Sensing and Context},
    location = {Zurich, Switzerland},
    month = {October},
    year = {2008},
    pages = {192--219},
    publisher = {Springer},
    abstract = {Equipment used in the construction domain is often hired in order to reduce cost and maintenance overhead. The cost of hire is dependent on the time period involved and does not take into account the actual use equipment has received. This paper presents our initial investigation into how physical objects augmented with sensing and communication technologies can measure use in order to enable new pay-per-use payment models for equipment hire. We also explore user interaction with pay-per-use objects via mobile devices. The user interactions that take place within our prototype scenario range from simple information access to transactions involving multiple users. This paper presents the design, implementation and evaluation of a prototype pay-per-use system motivated by a real world equipment hire scenario. We also provide insights into the various challenges introduced by supporting a pay-per-use model, including data storage and data security in addition to user interaction issues.},
    file={http://www.cl.cam.ac.uk/~ce291/papers/dan-EuroSSC.pdf},
    info = {Best paper award}
    }

2007

  1. Network Interrupts: Supporting Delay Sensitive Applications in Low Power Wireless Control Networks.
    J. Brown, J. Finney, C. Efstratiou, B. Green, N. Davies, M. Lowton and G. Kortuem.
    In Proceedings of CHANTS 2007: ACM MOBICOM 2007 Workshop on Challenged Networks, Montreal, Canada, pp. 51–58, September, 2007. ACM Press.
    Abstract
    The importance in maintaining energy efficient communications in low power networks such as sensor and actuator networks is well understood. However, in recent years, a growing number of delay sensitive and interactive applications have been discovered for such networks, that are no longer purely limited to the data gathering model of sensor networks. Providing support application requiring low latency interaction in such environments without negatively affecting energy efficiency remains a challenging problem. This paper outlines the importance of this emerging class of application, discusses problems involved in supporting them in energy challenged environments, proposes a combined hardware and software mechanism based on heterogeneous wireless networking which works toward solving this problem, and goes on to evaluate this mechanism through experimental analysis. The paper concludes with a discussion of the applicability of the mechanism to typical application scenarios.
    @inproceedings{jam07a,
    author = {J. Brown and J. Finney and C. Efstratiou and B. Green and N. Davies and M. Lowton and G. Kortuem},
    title = {Network Interrupts: Supporting Delay Sensitive Applications in Low Power Wireless Control Networks},
    booktitle = {Proceedings of CHANTS 2007: ACM MOBICOM 2007 Workshop on Challenged Networks},
    location = {Montreal, Canada},
    month = {September},
    year = {2007},
    pages = {51--58},
    publisher = {ACM Press},
    address = {New York, USA},
    file = {http://www.cl.cam.ac.uk/~ce291/papers/p51-brown.pdf},
    abstract = {The importance in maintaining energy efficient communications in low power networks such as sensor and actuator networks is well understood. However, in recent years, a growing number of delay sensitive and interactive applications have been discovered for such networks, that are no longer purely limited to the data gathering model of sensor networks. Providing support application requiring low latency interaction in such environments without negatively affecting energy efficiency remains a challenging problem. This paper outlines the importance of this emerging class of application, discusses problems involved in supporting them in energy challenged environments, proposes a combined hardware and software mechanism based on heterogeneous wireless networking which works toward solving this problem, and goes on to evaluate this mechanism through experimental analysis. The paper concludes with a discussion of the applicability of the mechanism to typical application scenarios.}
    }
  2. Sensor Networks or Smart Artifacts? An Exploration of Organizational Issues of An Industrial Health and Safety Monitoring System.
    G. Kortuem, D. Alford, L. Ball, J. Busby, N. Davies, C. Efstratiou, J. Finney, M. Iszatt-White and K. Kinder.
    In Proceedings of UBICOMP 2007, Innsbruck, Austria, pp. 465–482, September, 2007. Springer.
    Abstract
    Industrial health and safety is an important yet largely unexplored application area of ubiquitous computing. In this paper we investigate the relationship between technology and organization in the context of a concrete industrial health and safety system. The system is designed to reduce the number of incidents of "vibration white finger" (VWF) at construction sites and uses wireless sensor nodes for monitoring workers' exposure to vibrations and testing of compliance with legal health and safety regulations. In particular we investigate the impact of this ubiquitous technology on the relationship between management and operatives, the formulation of health and safety rules and the risk perception and risk behavior of operatives. In addition, we contrast sensor-network inspired and smart artifact inspired compliance systems, and make the case that these technology models have a strong influence on the linkage between technology and organization.
    @inproceedings{kor07a,
    author = {G. Kortuem and D. Alford and L. Ball and J. Busby and N. Davies and C. Efstratiou and J. Finney and M. Iszatt-White and K. Kinder},
    title = {Sensor Networks or Smart Artifacts? An Exploration of Organizational Issues of An Industrial Health and Safety Monitoring System},
    booktitle = {Proceedings of Ubicomp 2007},
    location = {Innsbruck, Austria},
    month = {September},
    year = {2007},
    publisher = {Springer},
    pages = {465--482},
    address = {Berlin},
    file = {http://www.cl.cam.ac.uk/~ce291/papers/Ubicomp-2007.pdf},
    abstract = {Industrial health and safety is an important yet largely unexplored application area of ubiquitous computing. In this paper we investigate the relationship between technology and organization in the context of a concrete industrial health and safety system. The system is designed to reduce the number of incidents of "vibration white finger" (VWF) at construction sites and uses wireless sensor nodes for monitoring workers' exposure to vibrations and testing of compliance with legal health and safety regulations. In particular we investigate the impact of this ubiquitous technology on the relationship between management and operatives, the formulation of health and safety rules and the risk perception and risk behavior of operatives. In addition, we contrast sensor-network inspired and smart artifact inspired compliance systems, and make the case that these technology models have a strong influence on the linkage between technology and organization.}
    }
  3. Experiences of Designing and Deploying Intellignent Sensor Nodes to Monitor Hand-Arm Vibrations in the Field.
    C. Efstratiou, N. Davies, G. Kortuem, J. Finney, R. Hooper and M. Lowton.
    In Proceedings of ACM MOBISYS 2007, San Juan, Puerto Rico, pp. 127–138, June, 2007. ACM Press.
    Abstract
    The NEMO project is exploring the use of mobile sensor nodes to augment physical work artefacts in order to ensure compliance with health and safety regulations. In this paper we present our experiences of designing and deploying the NEMO Hand Arm Vibration (HAV) monitoring system. Long term exposure to hand arm vibration can lead to serious health conditions and the NEMO HAV monitoring system offers an integrated architecture for capturing HAV exposure data in the field, providing feedback about exposure levels both in the field and as input to a back-end database. Our design allows health and safety regulations specified at the enterprise level to be embedded within the wireless sensor nodes allowing them to operate without any infrastructural support. The system has been the subject of a two week field trial that took place with the collaboration of a British construction and maintenance company. During the field trial, the NEMO HAV system was deployed to a road maintenance patching gang and data was collected on HAV exposure caused by hydraulic drills. The paper reports on the results of the field trial and the lessons learned through the real deployment of the system.
    @inproceedings{efs07b,
    author = {C. Efstratiou and N. Davies and G. Kortuem and J. Finney and R. Hooper and M. Lowton},
    title = {Experiences of Designing and Deploying Intellignent Sensor Nodes to Monitor Hand-Arm Vibrations in the Field},
    booktitle = {Proceedings of ACM MobiSys 2007},
    location = {San Juan, Puerto Rico},
    month = {June},
    year = {2007},
    pages = {127--138},
    publisher = {ACM Press},
    address = {New York, USA},
    file = {http://www.cl.cam.ac.uk/~ce291/papers/sys5742-efstratiou.pdf},
    abstract = { The NEMO project is exploring the use of mobile sensor nodes to augment physical work artefacts in order to ensure compliance with health and safety regulations. In this paper we present our experiences of designing and deploying the NEMO Hand Arm Vibration (HAV) monitoring system. Long term exposure to hand arm vibration can lead to serious health conditions and the NEMO HAV monitoring system offers an integrated architecture for capturing HAV exposure data in the field, providing feedback about exposure levels both in the field and as input to a back-end database. Our design allows health and safety regulations specified at the enterprise level to be embedded within the wireless sensor nodes allowing them to operate without any infrastructural support. The system has been the subject of a two week field trial that took place with the collaboration of a British construction and maintenance company. During the field trial, the NEMO HAV system was deployed to a road maintenance patching gang and data was collected on HAV exposure caused by hydraulic drills. The paper reports on the results of the field trial and the lessons learned through the real deployment of the system.}
    }
  4. Monitoring Hand-Arm Vibrations in Construction Sites.
    C. Efstratiou, N. Davies, G. Kortuem, J. Finney, R. Hooper and M. Lowton.
    In Demo Abstracts, ACM MOBISYS 2007, San Juan, Puerto Rico, June, 2007.
    • Abstract
    • BibTex
    • PDF
    • Citations
    @misc{efs07a,
    author = {C. Efstratiou and N. Davies and G. Kortuem and J. Finney and R. Hooper and M. Lowton},
    title = {Monitoring Hand-Arm Vibrations in Construction Sites},
    howpublished = {In Demo Abstracts, ACM MobiSys 2007},
    location = {San Juan, Puerto Rico},
    month = {June},
    year = {2007}
    }
  5. Sensing Danger - Challenges in Supporting Health and Safety Compliance in the Field.
    N. Davies, C. Efstratiou, J. Finney, R. Hooper, G. Kortuem and M. Lowton.
    In Proceedings of the 8th IEEE Workshop on Mobile Computing Systems and Applications (HOTMOBILE 2007), Tucson, Arizona, February, 2007.
    Abstract
    Many workers operate in environments that are inherently hazardous and that are subject to strict health and safety rules and regulations. We envisage a world in which physical work artefacts such as tools are augmented with intelligent mobile nodes that are able to observe the working activities taking place, evaluate compliance with health and safety regulations and assist or actively enforce compliance with these regulations. This vision creates a new field of work in the area of health and safety aware intelligent mobile sensor networks. In this paper we describe a number of new challenges faced when developing mobile systems for compliance with health and safety regulations.
    @inproceedings{dav07a,
    author = {N. Davies and C. Efstratiou and J. Finney and R. Hooper and G. Kortuem and M. Lowton},
    title = {Sensing Danger - Challenges in Supporting Health and Safety Compliance in the Field},
    booktitle = {Proceedings of the 8th IEEE Workshop on Mobile Computing Systems and Applications (HotMobile 2007)},
    location = {Tucson, Arizona},
    month = {February},
    year = {2007},
    file = {http://www.cl.cam.ac.uk/~ce291/papers/davies-SensingDanger.pdf},
    abstract = {Many workers operate in environments that are inherently hazardous and that are subject to strict health and safety rules and regulations. We envisage a world in which physical work artefacts such as tools are augmented with intelligent mobile nodes that are able to observe the working activities taking place, evaluate compliance with health and safety regulations and assist or actively enforce compliance with these regulations. This vision creates a new field of work in the area of health and safety aware intelligent mobile sensor networks. In this paper we describe a number of new challenges faced when developing mobile systems for compliance with health and safety regulations.},
    }

2006 and earlier

  1. Health and Safety Compliance in the Field.
    N. Davies, C. Efstratiou, J. Finney, R. Hooper, G. Kortuem, M. Lowton and M. Strohbach.
    In Demo Abstracts, ACM MOBISYS 2006, Uppsala, Sweden, June, 2006. ACM Press.
    @misc{dav06a,
    author = {N. Davies and C. Efstratiou and J. Finney and R. Hooper and G. Kortuem and M. Lowton and M. Strohbach},
    title = {Health and Safety Compliance in the Field},
    howpublished = {In Demo Abstracts, ACM MobiSys 2006},
    location = {Uppsala, Sweden},
    month = {June},
    year = {2006},
    publisher = {ACM Press},
    file = {http://www.cl.cam.ac.uk/~ce291/papers/MobiSys06Demo.pdf}
    }
  2. A Platform Supporting Coordinated Adaptation in Mobile Systems.
    C. Efstratiou, A. Friday, N. Davies and K. Cheverst.
    In Proceedings of the 4th IEEE Workshop on Mobile Computing Systems and Applications (WMCSA / HOTMOBILE 2002), Callicoon, New York, pp. 128–137, June, 2002. IEEE Computer Society.
    Abstract
    Mobile environments are highly dynamic, characterised by frequent and sudden changes in resource availability. As a consequence, adaptive mobile applications need to be capable of adapting their behaviour to ensure they continue to offer the best possible level of service to the user. Our experience of developing such applications has led us to believe that existing mobile middleware platforms fail to consider adaptive applications on a host as an ensemble of entities competing for the same resources; instead, focusing on the requirements of each application in isolation. A new approach is required which offers the mechanisms to support coordination of the adaptive behaviour of multiple applications in order to achieve a common goal. In this paper, we present a platform designed to meet this objective. Our platform is based on the notion of the definition of system-wide flexible adaptation policies written using a form of Kowalsky's event calculus, that may be adapted according to user needs. Moreover, we also believe that by using our approach it will soon be possible to identify and resolve conflicts caused by the need to adapt to multiple contextual triggers.
    @inproceedings{efs02b,
    author = {C. Efstratiou and A. Friday and N. Davies and K. Cheverst},
    title = {A Platform Supporting Coordinated Adaptation in Mobile Systems},
    booktitle = {Proceedings of the 4th {IEEE} Workshop on Mobile Computing Systems and Applications ({WMCSA}'02)},
    location = {Callicoon, New York},
    pages = {128--137},
    month = {June},
    year = {2002},
    publisher = {{IEEE Computer Society}},
    address = {Los Alamitos, CA, USA},
    abstract = {Mobile environments are highly dynamic, characterised by frequent and sudden changes in resource availability. As a consequence, adaptive mobile applications need to be capable of adapting their behaviour to ensure they continue to offer the best possible level of service to the user. Our experience of developing such applications has led us to believe that existing mobile middleware platforms fail to consider adaptive applications on a host as an ensemble of entities competing for the same resources; instead, focusing on the requirements of each application in isolation. A new approach is required which offers the mechanisms to support coordination of the adaptive behaviour of multiple applications in order to achieve a common goal. In this paper, we present a platform designed to meet this objective. Our platform is based on the notion of the definition of system-wide flexible adaptation policies written using a form of Kowalsky's event calculus, that may be adapted according to user needs. Moreover, we also believe that by using our approach it will soon be possible to identify and resolve conflicts caused by the need to adapt to multiple contextual triggers.},
    file = {http://www.cl.cam.ac.uk/~ce291/papers/efstratiou-wmcsa2002.pdf}
    }
  3. Utilising the Event Calculus for Policy Driven Adaptation in Mobile Systems.
    C. Efstratiou, A. Friday, N. Davies and K. Cheverst.
    In Proceedings of the 3rd International Workshop on Policies for Distributed Systems and Networks (POLICY 2002), Monterey, California, pp. 13–24, June, 2002. IEEE Computer Society.
    Abstract
    Adaptation is an important requirement for mobile applications due to the varying levels of resource availability that characterises mobile environments. However without proper control, multiple applications can each adapt independently in response to a range of different adaptive stimuli, causing conflicts or suboptimal performance. In this paper we present a policy driven approach for mobile adaptive systems that can overcome the aforementioned problems. Our system is based on a policy language derived from the Event Calculus logic programming formalism. Important characteristics of our policy language are the support for explicit expressions of time dependencies and the simple and user friendly syntax.
    @inproceedings{efs02a,
    author = {C. Efstratiou and A. Friday and N. Davies and K. Cheverst},
    title = {Utilising the Event Calculus for Policy Driven Adaptation in Mobile Systems},
    booktitle = {Proceedings of the 3rd International Workshop on Policies for Distributed Systems and Networks ({POLICY} 2002)},
    location = {Monterey, California},
    pages = {13--24},
    month = {June},
    year = {2002},
    publisher = {IEEE Computer Society},
    address = {Washington, DC, USA},
    abstract = {Adaptation is an important requirement for mobile applications due to the varying levels of resource availability that characterises mobile environments. However without proper control, multiple applications can each adapt independently in response to a range of different adaptive stimuli, causing conflicts or suboptimal performance. In this paper we present a policy driven approach for mobile adaptive systems that can overcome the aforementioned problems. Our system is based on a policy language derived from the Event Calculus logic programming formalism. Important characteristics of our policy language are the support for explicit expressions of time dependencies and the simple and user friendly syntax.},
    file = {http://www.cl.cam.ac.uk/~ce291/papers/efstratiou-policy2002.pdf}
    }
  4. The Rational for Infrastructure Support for Adaptive and Context-Aware Applications: A Position Paper.
    N. Davies, K. Cheverst, C. Efstratiou and A. Friday.
    In Proceedings of NSF Workshop on Infrastructure for Mobile and Wireless Systems, Scottsdale, Arizona, pp. 146–152, October, 2001. Springer.
    Abstract
    Research has demonstrated that mobile and wireless applications benefit from a knowledge of their operating environment. Examples of contextaware or adaptive applications have been constructed and evaluated with the results being widely disseminated within the research community. However, the field is still sufficiently new that there are currently no standards for describing, disseminating or managing the necessary contextual information. Moreover, there are no standards (or even accepted best practices) for coordinating adaptation across multiple applications and systems. In this position paper we argue that the lack of standards in this area will inhibit the widespread deployment of many of the compelling context-aware mobile applications currently being designed.
    @inproceedings{dav01a,
    author = {N. Davies and K. Cheverst and C. Efstratiou and A. Friday},
    title = {The Rational for Infrastructure Support for Adaptive and Context-Aware Applications: A Position Paper },
    booktitle = {Proceedings of NSF Workshop on Infrastructure for Mobile and Wireless Systems},
    location = {Scottsdale, Arizona},
    publisher = {Springer},
    pages = {146--152},
    month = {October},
    year = {2001},
    abstract = {Research has demonstrated that mobile and wireless applications benefit from a knowledge of their operating environment. Examples of contextaware or adaptive applications have been constructed and evaluated with the results being widely disseminated within the research community. However, the field is still sufficiently new that there are currently no standards for describing, disseminating or managing the necessary contextual information. Moreover, there are no standards (or even accepted best practices) for coordinating adaptation across multiple applications and systems. In this position paper we argue that the lack of standards in this area will inhibit the widespread deployment of many of the compelling context-aware mobile applications currently being designed.},
    file = {http://www.cl.cam.ac.uk/~ce291/papers/RationalInfra.pdf}
    }
  5. 'Feature' Interactions outside a Telecom Domain.
    L. Blair, G. Blair, J. Pang and C. Efstratiou.
    In Proceedings of Workshop on Feature Interactions in Composed Systems, ECOOP2001, Budapest, pp. 233–248, June, 2001. Kluwer, B.V.
    Abstract
    Feature interactions in the original sense of the term (i.e. within a telecommunications domain), have now been the subject of significant research activity for over ten years. This paper considers several different sources of interactions in other domains, arising during the course of our research at Lancaster. These interactions are taken from a variety of areas within the field of Distributed Systems, and stand to benefit greatly from the application of techniques developed in the feature interaction community. Furthermore, we believe they represent a potentially important generalisation for feature interaction research.
    @inproceedings{bla01a,
    author = {L. Blair and G. Blair and J. Pang and C. Efstratiou},
    title = {`{F}eature' Interactions outside a Telecom Domain},
    booktitle = {Proceedings of Workshop on Feature Interactions in Composed Systems, {ECOOP2001}},
    location = {Budapest},
    month = {June},
    pages = {233--248},
    publisher = {Kluwer, B.V.},
    address = {Deventer, The Netherlands},
    year = {2001},
    abstract = {Feature interactions in the original sense of the term (i.e. within a telecommunications domain), have now been the subject of significant research activity for over ten years. This paper considers several different sources of interactions in other domains, arising during the course of our research at Lancaster. These interactions are taken from a variety of areas within the field of Distributed Systems, and stand to benefit greatly from the application of techniques developed in the feature interaction community. Furthermore, we believe they represent a potentially important generalisation for feature interaction research. },
    file = {http://www.cl.cam.ac.uk/~ce291/papers/FICS01.pdf}
    }
  6. Using Context as a Crystal Ball: Rewards and Pitfalls.
    K. Cheverst, N. Davies, K. Mitchell and C. Efstratiou.
    Personal Technologies Journal, vol 5(1), pp. 8–11, February, 2001. Springer.
    Abstract
    Context-awareness can be used to simplify a user's understanding of, and interaction with, interactive systems. In effect, through adaptation, context-aware systems can migrate complexity away from the user and into the system (or agent). However, the incorporation of context-awareness raises a number of issues. For example, users are required to trust the behaviour of the system's intelligence and this requires the system to have predictable behaviour and the ability to successfully and consistently preempt the user's goal. Unfortunately, the agent may incorrectly preempt the user's goal, owing to either flawed intelligence or to incorrect or out-of-date contextual information. In such circumstances the user is likely to feel frustration because the system will either appear overly prescriptive or, worse still, present incorrect results. This paper considers these issues, a number of which are described in anecdotal form, based on our experiences in developing and evaluating the context-aware GUIDE system.
    @article{che01a,
    author = {K. Cheverst and N. Davies and K. Mitchell and C. Efstratiou},
    title = {Using Context as a Crystal Ball: Rewards and Pitfalls},
    journal = {Personal Technologies Journal},
    volume = {5},
    number = {1},
    month = {February},
    pages = {8--11},
    publisher = {Springer},
    year = {2001},
    abstract = {Context-awareness can be used to simplify a user's understanding of, and interaction with, interactive systems. In effect, through adaptation, context-aware systems can migrate complexity away from the user and into the system (or agent). However, the incorporation of context-awareness raises a number of issues. For example, users are required to trust the behaviour of the system's intelligence and this requires the system to have predictable behaviour and the ability to successfully and consistently preempt the user's goal. Unfortunately, the agent may incorrectly preempt the user's goal, owing to either flawed intelligence or to incorrect or out-of-date contextual information. In such circumstances the user is likely to feel frustration because the system will either appear overly prescriptive or, worse still, present incorrect results. This paper considers these issues, a number of which are described in anecdotal form, based on our experiences in developing and evaluating the context-aware GUIDE system.},
    file = {http://www.cl.cam.ac.uk/~ce291/papers/crystal.pdf}
    }
  7. An Architecture for the Effective Support of Adaptive Context-Aware Applications.
    C. Efstratiou, K. Cheverst, N. Davies and A. Friday.
    In Proceedings of Mobile Data Management (MDM'01), Hong Kong, pp. 15–26, January, 2001. Springer.
    Abstract
    Mobile applications are required to operate in environments characterised by change. More specifically, the availability of resources and services may change significantly during a typical period of system operation. As a consequence, adaptive mobile applications need to be capable of adapting to these changes to ensure they offer the best possible level of service to the user. Our experiences of developing and evaluating adaptive context-aware applications in mobile environments has led us to believe that existing architectures fail to provide the necessary support for such applications. In this paper, we discuss the shortcomings of existing approaches and present work on our own architecture that has been designed to meet the key requirements of context-aware adaptive applications.
    @inproceedings{efs01a,
    author = {C. Efstratiou and K. Cheverst and N. Davies and A. Friday},
    title = {An Architecture for the Effective Support of Adaptive Context-Aware Applications},
    booktitle = {Proceedings of Mobile Data Management ({MDM}'01)},
    location = {Hong Kong},
    month = {January},
    year = {2001},
    pages = {15--26},
    publisher = {Springer},
    address = {Berlin},
    abstract = {Mobile applications are required to operate in environments characterised by change. More specifically, the availability of resources and services may change significantly during a typical period of system operation. As a consequence, adaptive mobile applications need to be capable of adapting to these changes to ensure they offer the best possible level of service to the user. Our experiences of developing and evaluating adaptive context-aware applications in mobile environments has led us to believe that existing architectures fail to provide the necessary support for such applications. In this paper, we discuss the shortcomings of existing approaches and present work on our own architecture that has been designed to meet the key requirements of context-aware adaptive applications. },
    file = {http://www.cl.cam.ac.uk/~ce291/papers/mdm2001.pdf}
    }
  8. Architectural Ideas for the Support of Adaptive Context-Aware Applications.
    K. Cheverst, C. Efstratiou, N. Davies and A. Friday.
    In Proceedings of Workshop on Infrastructure for Smart Devices - How to Make Ubiquity an Actuality, HUC'00, Bristol, September, 2000.
    @inproceedings{che00a,
    author = {K. Cheverst and C. Efstratiou and N. Davies and A. Friday},
    title = {Architectural Ideas for the Support of Adaptive Context-Aware Applications},
    booktitle = {Proceedings of Workshop on Infrastructure for Smart Devices - How to Make Ubiquity an Actuality, HUC'00},
    location = {Bristol},
    month = {September},
    year = {2000},
    file = {http://www.cl.cam.ac.uk/~ce291/papers/ArchIdeas.pdf}
    }
  9. Architectural Requirements for the Effective Support of Adaptive Mobile Applications.
    C. Efstratiou, K. Cheverst, N. Davies and A. Friday.
    Work in progress paper in Middleware2000, USA:New York, April, 2000.
    Abstract
    Mobile applications are required to operate in environments that change. Specifically, the availability of resources and services may change significantly during typical system operation. As a consequence, mobile applications need to be capable of adapting to these changes to ensure they offer the best possible level of service to the user. Our experiences of developing adaptive applications have led us to believe that existing middleware fails to provide the necessary support for such applications. Moreover, we believe that current research in this area is also failing to address the core requirements of adaptive mobile systems. In this paper we present a set of requirements for future mobile middleware which have been derived by considering the shortcomings of existing approaches and the needs of application developers. Key among these requirements is the need to support coordinated action between application and system components and the resolution of conflicts caused by the need to adapt to multiple contextual triggers. The paper concludes with the presentation of an architectural framework within which middleware researchers can deploy solutions to the problems identified.
    @inproceedings{efs00a,
    author = {C. Efstratiou and K. Cheverst and N. Davies and A. Friday},
    title = {Architectural Requirements for the Effective Support of Adaptive Mobile Applications},
    booktitle = {Work in progress paper in {M}iddleware2000},
    location = {{USA}:{N}ew {Y}ork},
    month = {April},
    year = {2000},
    abstract = {Mobile applications are required to operate in environments that change. Specifically, the availability of resources and services may change significantly during typical system operation. As a consequence, mobile applications need to be capable of adapting to these changes to ensure they offer the best possible level of service to the user. Our experiences of developing adaptive applications have led us to believe that existing middleware fails to provide the necessary support for such applications. Moreover, we believe that current research in this area is also failing to address the core requirements of adaptive mobile systems. In this paper we present a set of requirements for future mobile middleware which have been derived by considering the shortcomings of existing approaches and the needs of application developers. Key among these requirements is the need to support coordinated action between application and system components and the resolution of conflicts caused by the need to adapt to multiple contextual triggers. The paper concludes with the presentation of an architectural framework within which middleware researchers can deploy solutions to the problems identified.},
    file = {http://www.cl.cam.ac.uk/~ce291/papers/Middleware2000.pdf}
    }
  10. Reflection: A Solution For Highly Adaptive Mobile Systems.
    C. Efstratiou and K. Cheverst.
    Position paper at the Reflective Middleware Workshop in conjunction with Middleware 2000, New York, April, 2000.
    @misc{efs00b,
    author = {C. Efstratiou and K. Cheverst},
    title = {Reflection: A Solution For Highly Adaptive Mobile Systems},
    howpublished = {Position paper at the Reflective Middleware Workshop in conjunction with Middleware 2000},
    location = {New York},
    year = {2000},
    month = {April},
    file = {http://www.cl.cam.ac.uk/~ce291/papers/reflection.pdf}
    }
  11. Developing a context-aware electronic tourist guide: some issues and experiences.
    K. Cheverst, N. Davies, K. Mitchell, A. Friday and C. Efstratiou.
    In Proceedings of the 2000 Conference on Human Factors in Computing Systems (CHI-00), edt. Thea Turner and Gerd Szwillus and Mary Czerwinski and Paterno Fabio, New York, pp. 17–24, April, 2000. ACM Press.
    Abstract
    In this paper, we describe our experiences of developing and evaluating GUIDE, an intelligent electronic tourist guide. The GUIDE system has been built to overcome many of the limitations of the traditional information and navigation tools available to city visitors. For example, group-based tours are inherently inflexible with fixed starting times and fixed durations and (like most guidebooks) are constrained by the need to satisfy the interests of the majority rather than the specific interests of individuals. Following a period of requirements capture, involving experts in the field of tourism, we developed and installed a system for use by visitors to Lancaster. The system combines mobile computing technologies with a wireless infrastructure to present city visitors with information tailored to both their personal and environmental contexts. In this paper we present an evaluation of GUIDE, focusing on the quality of the visitor's experience when using the system.
    @inproceedings{che00b,
    author = {K. Cheverst and N. Davies and K. Mitchell and A. Friday and C. Efstratiou},
    title = {Developing a context-aware electronic tourist guide: some issues and experiences},
    booktitle = {Proceedings of the 2000 Conference on Human Factors in Computing Systems ({CHI}-00)},
    publisher = {ACM Press},
    editor = {Thea Turner and Gerd Szwillus and Mary Czerwinski and Patern{\`o} Fabio},
    location = {New York},
    pages = {17--24},
    month = {April},
    year = {2000},
    abstract = {In this paper, we describe our experiences of developing and evaluating GUIDE, an intelligent electronic tourist guide. The GUIDE system has been built to overcome many of the limitations of the traditional information and navigation tools available to city visitors. For example, group-based tours are inherently inflexible with fixed starting times and fixed durations and (like most guidebooks) are constrained by the need to satisfy the interests of the majority rather than the specific interests of individuals. Following a period of requirements capture, involving experts in the field of tourism, we developed and installed a system for use by visitors to Lancaster. The system combines mobile computing technologies with a wireless infrastructure to present city visitors with information tailored to both their personal and environmental contexts. In this paper we present an evaluation of GUIDE, focusing on the quality of the visitor's experience when using the system.},
    file = {http://www.cl.cam.ac.uk/~ce291/papers/CHI.pdf},
    }
  12. A Layered Architecture for Computer-based simulation supporting skills learning: an X-ray imaging paradigm.
    L. Costaridou, G. Panayiotakis, C. Efstratiou, C. Papnikolaou and N. Palikarakis.
    Medical Informatics Journal, vol 22(2), pp. 165–177, 1997.
    Abstract
    Simulation is characterized by strong learning potential, providing the basis for a new category of systems, the simulation-based learning systems. To strengthen the learning potential of these systems, models are needed not only of the actual system being imitated, but also of the operational expertise required to carry out manipulations of the simulated system, inherently linked to learning. In this paper, an architecture is reported aimed at supporting the organization of multimodal simulation resources to induce skills learning. This architecture is based on distinct layers, allowing independent representation of learning and simulation components. Its applicability has been demonstrated by means of a paradigm, including simulation of X-ray imaging procedure, as well as authoring of learning scenarios pertaining to such procedures.
    @article{cos97a,
    author = {L. Costaridou and G. Panayiotakis and C. Efstratiou and C. Papnikolaou and N. Palikarakis},
    title = {A Layered Architecture for Computer-based simulation supporting skills learning: an X-ray imaging paradigm},
    journal = {Medical Informatics Journal},
    volume = {22},
    number = {2},
    pages = {165--177},
    year = {1997},
    abstract = {Simulation is characterized by strong learning potential, providing the basis for a new category of systems, the simulation-based learning systems. To strengthen the learning potential of these systems, models are needed not only of the actual system being imitated, but also of the operational expertise required to carry out manipulations of the simulated system, inherently linked to learning. In this paper, an architecture is reported aimed at supporting the organization of multimodal simulation resources to induce skills learning. This architecture is based on distinct layers, allowing independent representation of learning and simulation components. Its applicability has been demonstrated by means of a paradigm, including simulation of X-ray imaging procedure, as well as authoring of learning scenarios pertaining to such procedures.}
    }
  13. PRONET Services for Distance Learning in Mammographic Image Processing.
    L. Costaridou, G. Panayiotakis, C. Efstratiou, P. Sakellaropoulos, D. Cavouras, C. Kalogeropoulos, K. Varakis, L. Giannakou and J. Dimopoulos.
    In Proceedings of the XIII International Congress of the European Federation for Medical Informatics (MIE'97), Greece, pp. 165–177, 1997. Amsterdam : IOS Press.
    Abstract
    The potential of telematics services is investigated with respect to learning needs of medical physicists and biomedical engineers. Telematics services are integrated into a system, the PRONET, which evolves around multimedia computer based courses and distance tutoring support. In addition, information database access and special interest group support are offered. System architecture is based on a component integration approach. The services are delivered in three modes: LAN, ISDN and Internet. Mammographic image processing is selected as an example content area.
    @inproceedings{cos97b,
    title = {PRONET Services for Distance Learning in Mammographic Image Processing},
    author = {L. Costaridou and G. Panayiotakis and C. Efstratiou and P. Sakellaropoulos and D. Cavouras and C. Kalogeropoulos and K. Varakis and L. Giannakou and J. Dimopoulos},
    booktitle = {Proceedings of the XIII International Congress of the European Federation for Medical Informatics (MIE'97)},
    location = {Greece},
    publisher = {Amsterdam : IOS Press},
    pages = {165--177},
    year = {1997},
    abstract = {The potential of telematics services is investigated with respect to learning needs of medical physicists and biomedical engineers. Telematics services are integrated into a system, the PRONET, which evolves around multimedia computer based courses and distance tutoring support. In addition, information database access and special interest group support are offered. System architecture is based on a component integration approach. The services are delivered in three modes: LAN, ISDN and Internet. Mammographic image processing is selected as an example content area.}
    }
  14. Modelling X-Ray Imaging Procedures: A Tool for Generating Learning Tasks.
    L. Costaridou, C. Papnikolaou, C. Efstratiou, K. Hatzis, N. Palikarakis and G. Panayiotakis.
    In Proceedings of the XII International Congress of the European Federation for Medical Informatics (MIE'96), Denmark, pp. 1047–1051, 1996. Amsterdam : IOS Press.
    @inproceedings{cos97b,
    author = {L. Costaridou and C. Papnikolaou and C. Efstratiou and K. Hatzis and N. Palikarakis and G. Panayiotakis},
    title = {Modelling X-Ray Imaging Procedures: A Tool for Generating Learning Tasks},
    booktitle = {Proceedings of the XII International Congress of the European Federation for Medical Informatics (MIE'96)},
    location = {Denmark},
    publisher = {Amsterdam : IOS Press},
    year = {1996},
    pages = {1047--1051}
    }

Thesis

  1. Coordinated Adaptation for Adaptive Context-aware Applications.
    C. Efstratiou.
    Ph.D. Thesis, Lancaster University, Computing Department, 2004.
    Abstract
    The ability to adapt to change is critical to both mobile and context-aware applications. This thesis argues that providing sufficient support for adaptive context-aware applications requires support for coordinated adaptation. Specifically, the main argument of this thesis is that coordinated adaptation requires applications to delegate adaptation control to an entity that can receive state information from multiple applications and trigger adaptation in multiple applications. Furthermore, coordination requires support for reconfiguration of the adaptive behaviour and user involvement. Failure to support coordinated adaptation is shown to lead to poor system and application performance and insufficient support for user requirements. An investigation of the existing state-of-the-art in the areas of adaptive and contextaware systems and an analysis of the limitations of existing systems leads to the establishment of a set of design requirements for the support of coordinated adaptation. Specifically, adaptation control should be decoupled from the mechanisms implementing the adaptive behaviour of the applications, applications should externalise both state information and the adaptive mechanisms they support and the adaptation control mechanism should allow modifications without the need for re-implementation of either the application or the support platform. This thesis presents the design of a platform derived from the aforementioned requirements. This platform utilises a policy based mechanism for controlling adaptation. Based on the particular requirements of adaptive context-aware applications a new policy language is defined derived from Kowalsky's Event Calculus logic programming formalism. This policy language allows the specification of policy rules where conditions are defined through the expression of temporal relationships between events and entities that represent duration (i.e. fluents). A prototype implementation of this design allowed the evaluation of the features offered by this platform. This evaluation reveals that the platform can support coordinated adaptation with acceptable performance cost.
    @phdthesis{efs04a,
    author = {C. Efstratiou},
    title = {Coordinated Adaptation for Adaptive Context-aware Applications},
    type = {Ph.D. Thesis},
    school = {Lancaster University, Computing Department},
    year = {2004},
    abstract = {The ability to adapt to change is critical to both mobile and context-aware applications. This thesis argues that providing sufficient support for adaptive context-aware applications requires support for coordinated adaptation. Specifically, the main argument of this thesis is that coordinated adaptation requires applications to delegate adaptation control to an entity that can receive state information from multiple applications and trigger adaptation in multiple applications. Furthermore, coordination requires support for reconfiguration of the adaptive behaviour and user involvement. Failure to support coordinated adaptation is shown to lead to poor system and application performance and insufficient support for user requirements. An investigation of the existing state-of-the-art in the areas of adaptive and contextaware systems and an analysis of the limitations of existing systems leads to the establishment of a set of design requirements for the support of coordinated adaptation. Specifically, adaptation control should be decoupled from the mechanisms implementing the adaptive behaviour of the applications, applications should externalise both state information and the adaptive mechanisms they support and the adaptation control mechanism should allow modifications without the need for re-implementation of either the application or the support platform. This thesis presents the design of a platform derived from the aforementioned requirements. This platform utilises a policy based mechanism for controlling adaptation. Based on the particular requirements of adaptive context-aware applications a new policy language is defined derived from Kowalsky's Event Calculus logic programming formalism. This policy language allows the specification of policy rules where conditions are defined through the expression of temporal relationships between events and entities that represent duration (i.e. fluents). A prototype implementation of this design allowed the evaluation of the features offered by this platform. This evaluation reveals that the platform can support coordinated adaptation with acceptable performance cost.},
    file = {http://www.cl.cam.ac.uk/~ce291/papers/efstratiou-phd.pdf}
    }
  2. A tool for video and audio synchronisation over the Internet.
    C. Efstratiou.
    M.Sc. Thesis, Lancaster University, Computing Department, 1998.
    • Abstract
    • BibTex
    • PDF
    • Citations
    @mscthesis{efs98a,
    author = {C. Efstratiou},
    title = {A tool for video and audio synchronisation over the Internet},
    type = {M.Sc. Thesis},
    school = {Lancaster University, Computing Department},
    year = {1998}
    }

Patents

  1. System and method for effectively providing user information from a user device.
    P.G. Raverdy, N. Davies, O. Storz and C. Efstratiou.
    US Patent 7493368, Sony Corporation, February, 2009.
    @misc{rav09a,
    author = {P.G. Raverdy and N. Davies and O. Storz and C. Efstratiou},
    title = {System and method for effectively providing user information from a user device},
    howpublished = {{US} Patent 7493368},
    month = {February},
    year = {2009}
    }
  2. System and method for selectively providing information to a user device.
    P.G. Raverdy, N. Davies, O. Storz and C. Efstratiou.
    US Patent 6957217, Sony Corporation, October, 2005.
    @misc{rav05a,
    author = {P.G. Raverdy and N. Davies and O. Storz and C. Efstratiou},
    title = {System and method for selectively providing information to a user device},
    howpublished = {{US} Patent 6957217, {S}ony Corporation},
    month = {October},
    year = {2005}
    }
  3. System and method to support gaming in an electronic network.
    P.G. Raverdy, N. Davies, O. Storz and C. Efstratiou.
    US Patent 6884162, Sony Corporation, April, 2005.
    @misc{rav05b,
    author = {P.G. Raverdy and N. Davies and O. Storz and C. Efstratiou},
    title = {System and method to support gaming in an electronic network},
    howpublished = {{US} Patent 6884162, {S}ony Corporation},
    month = {April},
    year = {2005}
    }
  4. System and method for streaming video information to a user device
    P.G. Raverdy, N. Davies, O. Storz and C. Efstratiou.
    US Patent Application 20020069419, Sony Corporation, July, 2001.
    @misc{rav01a,
    author = {P.G. Raverdy and N. Davies and O. Storz and C. Efstratiou},
    title = {System and method for streaming video information to a user device},
    howpublished = {{US} Patent Application 20020069419, {S}ony Corporation},
    month = {July},
    year = {2001}
    }