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  • Journal article
    Riedinger A, Leal MP, Deka SR, George C, Franchini IR, Falqui A, Cingolani R, Pellegrino Tet al., 2011,

    "Nanohybrids" Based on pH-Responsive Hydrogels and Inorganic Nanoparticles for Drug Delivery and Sensor Applications

    , NANO LETTERS, Vol: 11, Pages: 3136-3141, ISSN: 1530-6984
  • Journal article
    Korobchevskaya K, George C, Diaspro A, Manna L, Cingolani R, Comin Aet al., 2011,

    Ultrafast carrier dynamics in gold/iron-oxide nanocrystal heterodimers

    , APPLIED PHYSICS LETTERS, Vol: 99, ISSN: 0003-6951
  • Journal article
    Angelopoulou M, Bouganis C-S, Cheung PYK, 2011,

    Blur Identification with Assumption Validation for Sensor-based Video Reconstruction and its Implementation on FPGA

    , IET Computers & Digital Techniques
  • Journal article
    Reikard G, Pinson P, Bidlot JR, 2011,

    Forecasting ocean wave energy: The ECMWF wave model and time series methods

    , Ocean Engineering, Vol: 38, Pages: 1089-1099, ISSN: 0029-8018

    Recently, the technology has been developed to make wave farms commercially viable. Since electricity is perishable, utilities will be interested in forecasting ocean wave energy. The horizons involved in short-term management of power grids range from as little as a few hours to as long as several days. In selecting a method, the forecaster has a choice between physics-based models and statistical techniques. A further idea is to combine both types of models. This paper analyzes the forecasting properties of a well-known physics-based model, the European Center for Medium-Range Weather Forecasts (ECMWF) Wave Model, and two statistical techniques, time-varying parameter regressions and neural networks. Thirteen data sets at locations in the Atlantic and Pacific Oceans and the Gulf of Mexico are tested. The quantities to be predicted are the significant wave height, the wave period, and the wave energy flux. In the initial tests, the ECMWF model and the statistical models are compared directly. The statistical models do better at short horizons, producing more accurate forecasts in the 15 h range. The ECMWF model is superior at longer horizons. The convergence point, at which the two methods achieve comparable degrees of accuracy, is in the area of 6 h. By implication, the physics-based model captures the underlying signals at lower frequencies, while the statistical models capture relationships over shorter intervals. Further tests are run in which the forecasts from the ECMWF model are used as inputs in regressions and neural networks. The combined models yield more accurate forecasts than either one individually. © 2011 Elsevier Ltd. All rights reserved.
  • Journal article
    Mai L, Yang F, Zhao Y, Xu X, Xu L, Hu B, Luo Y, Liu Het al., 2011,

    Molybdenum oxide nanowires: synthesis & properties

    , MATERIALS TODAY, Vol: 14, Pages: 346-353, ISSN: 1369-7021
  • Journal article
    Mai L-Q, Yang F, Zhao Y-L, Xu X, Xu L, Luo Y-Zet al., 2011,

    Hierarchical MnMoO<sub>4</sub>/CoMoO<sub>4</sub> heterostructured nanowires with enhanced supercapacitor performance

    , NATURE COMMUNICATIONS, Vol: 2, ISSN: 2041-1723
  • Journal article
    Griggs WM, Anderson BDO, Shorten RN, 2011,

    A test for determining systems with "mixed" small gain and passivity properties

    , SYSTEMS & CONTROL LETTERS, Vol: 60, Pages: 479-485, ISSN: 0167-6911
  • Journal article
    Villalon J, Calvo RA, 2011,

    Concept Maps as Cognitive Visualizations of Writing Assignments

    , EDUCATIONAL TECHNOLOGY & SOCIETY, Vol: 14, Pages: 16-27, ISSN: 1176-3647
  • Journal article
    O'Rourke ST, Calvo RA, McNamara DS, 2011,

    Visualizing Topic Flow in Students' Essays

    , EDUCATIONAL TECHNOLOGY & SOCIETY, Vol: 14, Pages: 4-15, ISSN: 1176-3647
  • Journal article
    Demirel P, Kesidou E, 2011,

    Stimulating different types of eco-innovation in the UK: Government policies and firm motivations

    , ECOLOGICAL ECONOMICS, Vol: 70, Pages: 1546-1557, ISSN: 0921-8009
  • Journal article
    Van Zalk N, Van Zalk M, Kerr M, Stattin Het al., 2011,

    Social Anxiety as a Basis for Friendship Selection and Socialization in Adolescents' Social Networks

    , JOURNAL OF PERSONALITY, Vol: 79, Pages: 499-526, ISSN: 0022-3506
  • Patent
    Cheung PYK, Sedcole NP, Wong JS, 2011,

    Method of Measuring Delay in An Integrated Circuit

    , US 0095768 A1

    A method of measuring signal delay in a integrated circuit comprising applying a common clock signal at a circuit input and output, applying a test signal at the circuit input, detecting a corresponding output signal at the circuit output and detecting whether the test signal and output signal occur in a common part of the clock signal.
  • Conference paper
    Li N, Mohamed MS, Cai J, Lin J, Balint D, Dean TAet al., 2011,

    Experimental and Numerical Studies on the Formability of Materials in Hot Stamping and Cold Die Quenching Processes

    , The 14th International ESAFORM Conference on Material Forming, Publisher: American Institute of Physics, Pages: 1555-1561, ISSN: 0094-243X

    Formability of steel and aluminium alloys in hot stamping and cold die quenching processes is studied in this research. Viscoplastic‐damage constitutive equations are developed and determined from experimental data for the prediction of viscoplastic flow and ductility of the materials. The determined unified constitutive equations are then implemented into the commercial Finite Element code Abaqus/Explicit via a user defined subroutine, VUMAT. An FE process simulation model and numerical procedures are established for the modeling of hot stamping processes for a spherical part with a central hole. Different failure modes (failure takes place either near the central hole or in the mid span of the part) are obtained. To validate the simulation results, a test programme is developed, a test die set has been designed and manufactured, and tests have been carried out for the materials with different forming rates. It has been found that very close agreements between experimental and numerical process simulation results are obtained for the ranges of temperatures and forming rates carried out.
  • Conference paper
    Porat T, Rief I, Puzis R, Elovici Yet al., 2011,

    LoOkie – It Feels Like Being There, proposing a social mobile application

    , CHI’ 2011 Conference Proceedings
  • Journal article
    Krahne R, Morello G, Figuerola A, George C, Deka S, Manna Let al., 2011,

    Physical properties of elongated inorganic nanoparticles

    , PHYSICS REPORTS-REVIEW SECTION OF PHYSICS LETTERS, Vol: 501, Pages: 75-221, ISSN: 0370-1573
  • Journal article
    Calvo RA, O'Rourke ST, Jones J, Yacef K, Reimann Pet al., 2011,

    Collaborative Writing Support Tools on the Cloud

    , IEEE TRANSACTIONS ON LEARNING TECHNOLOGIES, Vol: 4, Pages: 88-97, ISSN: 1939-1382
  • Journal article
    Deterding S, 2011,

    Hitting the Straw Man, Missing the Parade

    , CONSTRUCTIVIST FOUNDATIONS, Vol: 6, Pages: 278-281, ISSN: 1782-348X
  • Journal article
    Corless M, Shorten R, 2011,

    On a class of generalized eigenvalue problems and equivalent eigenvalue problems that arise in systems and control theory

    , AUTOMATICA, Vol: 47, Pages: 431-442, ISSN: 0005-1098
  • Journal article
    George C, Dorfs D, Bertoni G, Falqui A, Genovese A, Pellegrino T, Roig A, Quarta A, Comparelli R, Curri ML, Cingolani R, Manna Let al., 2011,

    A Cast-Mold Approach to Iron Oxide and Pt/Iron Oxide Nanocontainers and Nanoparticles with a Reactive Concave Surface

    , JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, Vol: 133, Pages: 2205-2217, ISSN: 0002-7863
  • Conference paper
    Porat T, Oron-Gilad T, Silbiger J, Rottem-Hovev Met al., 2011,

    Switch and Deliver: display layouts for MOMV (Multiple Operators Multiple Video feeds) environments

    , IEEE CogSIMA 2011 Conference Proceedings
  • Journal article
    Nanayakkara T, Halgamuge MN, Sridhar P, Madni AMet al., 2011,

    Intelligent sensing in dynamic environments using Markov decision process

    , Sensors, Vol: 11, Pages: 1229-1242, ISSN: 1424-8220

    In a network of low-powered wireless sensors, it is essential to capture as many environmental events as possible while still preserving the battery life of the sensor node. This paper focuses on a real-time learning algorithm to extend the lifetime of a sensor node to sense and transmit environmental events. A common method that is generally adopted in ad-hoc sensor networks is to periodically put the sensor nodes to sleep. The purpose of the learning algorithm is to couple the sensor’s sleeping behavior to the natural statistics of the environment hence that it can be in optimal harmony with changes in the environment, the sensors can sleep when steady environment and stay awake when turbulent environment. This paper presents theoretical and experimental validation of a reward based learning algorithm that can be implemented on an embedded sensor. The key contribution of the proposed approach is the design and implementation of a reward function that satisfies a trade-off between the above two mutually contradicting objectives, and a linear critic function to approximate the discounted sum of future rewards in order to perform policy learning.
  • Conference paper
    Ben K, Paavilainen J, Björk S, Rao V, Deterding Set al., 2011,

    Social game studies at CHI 2011

    , Pages: 17-20

    "Social games", defined as games played and distributed on Social Networks, have become a digital gaming phenomenon. The most popular games boast tens of millions of users each month, employing simple mechanics to reach a vast new audience that was apparently under-served by traditional digital games. Their enormous success raises important academic questions about game design, interface design, psychology and the social power of online networks. Social Game Studies at CHI 2011 is a one-day workshop at CHI 2011 that will bring together the CHI community with an inter-disciplinary mix of researchers and practitioners to share findings and explore the issues surrounding this emerging area of research into social games, and highlight the key questions, opportunities and challenges for future academic study.
  • Conference paper
    Deterding S, O'Hara K, Sicart M, Dixon D, Nacke Let al., 2011,

    Gamification: Using game design elements in non-gaming contexts

    , Pages: 2425-2428

    "Gamification" is an informal umbrella term for the use of video game elements in non-gaming systems to improve user experience (UX) and user engagement. The recent introduction of 'gamified' applications to large audiences promises new additions to the existing rich and diverse research on the heuristics, design patterns and dynamics of games and the positive UX they provide. However, what is lacking for a next step forward is the integration of this precise diversity of research endeavors. Therefore, this workshop brings together practitioners and researchers to develop a shared understanding of existing approaches and findings around the gamification of information systems, and identify key synergies, opportunities, and questions for future research.
  • Conference paper
    Porat T, Rief I, Puzis R, Elovici Yet al., 2011,

    LoOkie - It feels like being there

    , Pages: 1873-1878

    In this paper, we describe an interaction design process and the challenges encountered during the development of LoOkie, a social mobile application, which enables members to request and receive live videos or pictures of desired locations from people who are present at the scene. The paper describes, from a human-computer interaction perspective, the development of the application from the birth of the idea through the design process encountered up to the point of the launch of the application for Beta at the beginning of 2011.
  • Journal article
    Vincent CL, Pinson P, Giebela G, 2011,

    Wind fluctuations over the North Sea

    , International Journal of Climatology, Vol: 31, Pages: 1584-1595, ISSN: 0899-8418

    Climatological patterns in wind speed fluctuations with periods of 1 min to 10 h are analysed using data from a meteorological mast in the Danish North Sea. Fluctuations on these time scales are of particular relevance to the effective management of the power supply from large wind farms. The Hilbert-Huang transform (HHT) is shown to be an effective tool for analysing long time series of wind speed observations, as it describes the time-evolving spectral information in the time series. By binning and averaging the time-evolving spectrum, the average spectral behaviour of the wind speed under a certain class of conditions can be found. Here, the HHT is applied to create conditional spectra which demonstrate patterns in the occurrence of severe wind variability. It is shown that wind fluctuations over the North Sea are more severe for westerly flow than for easterly flow, and that severe fluctuations are often observed in the vicinity of precipitation. The most severe wind fluctuations occur in the autumn and winter seasons, and are slightly more common when the pressure tendency is rising. Further, it is found that the wind is more variable for atmospherically unstable conditions than for stable conditions. © 2010 Royal Meteorological Society.
  • Journal article
    Tastu J, Pinson P, Kotwa E, Madsen H, Nielsen HAet al., 2011,

    Spatio-temporal analysis and modeling of short-term wind power forecast errors

    , Wind Energy, Vol: 14, Pages: 43-60, ISSN: 1095-4244

    Forecasts of wind power production are increasingly being used in various management tasks. So far, such forecasts and related uncertainty information have usually been generated individually for a given site of interest (either a wind farm or a group of wind farms), without properly accounting for the spatio-temporal dependencies observed in the wind generation field. However, it is intuitively expected that, owing to the inertia of meteorological forecasting systems, a forecast error made at a given point in space and time will be related to forecast errors at other points in space in the following period. The existence of such underlying correlation patterns is demonstrated and analyzed in this paper, considering the case-study of western Denmark. The effects of prevailing wind speed and direction on autocorrelation and cross-correlation patterns are thoroughly described. For a flat terrain region of small size like western Denmark, significant correlation between the various zones is observed for time delays up to 5 h. Wind direction is shown to play a crucial role, while the effect of wind speed is more complex. Nonlinear models permitting capture of the interdependence structure of wind power forecast errors are proposed, and their ability to mimic this structure is discussed. The best performing model is shown to explain 54% of the variations of the forecast errors observed for the individual forecasts used today. Even though focus is on 1-h-ahead forecast errors and on western Denmark only, the methodology proposed may be similarly tested on the cases of further look-ahead times, larger areas, or more complex topographies. Such generalization may not be straightforward. While the results presented here comprise a first step only, the revealed error propagation principles may be seen as a basis for future related work. Copyright © 2010 John Wiley & Sons, Ltd.
  • Journal article
    Gallego C, Pinson P, Madsen H, Costa A, Cuerva Aet al., 2011,

    Influence of local wind speed and direction on wind power dynamics - Application to offshore very short-term forecasting

    , Applied Energy, Vol: 88, Pages: 4087-4096, ISSN: 0306-2619

    Wind power time series usually show complex dynamics mainly due to non-linearities related to the wind physics and the power transformation process in wind farms. This article provides an approach to the incorporation of observed local variables (wind speed and direction) to model some of these effects by means of statistical models. To this end, a benchmarking between two different families of varying-coefficient models (regime-switching and conditional parametric models) is carried out. The case of the offshore wind farm of Horns Rev in Denmark has been considered. The analysis is focused on one-step ahead forecasting and a time series resolution of 10. min. It has been found that the local wind direction contributes to model some features of the prevailing winds, such as the impact of the wind direction on the wind variability, whereas the non-linearities related to the power transformation process can be introduced by considering the local wind speed. In both cases, conditional parametric models showed a better performance than the one achieved by the regime-switching strategy. The results attained reinforce the idea that each explanatory variable allows the modelling of different underlying effects in the dynamics of wind power time series. © 2011 Elsevier Ltd.
  • Journal article
    Fan J, Myant CW, Underwood R, Cann PM, Hart Aet al., 2011,

    Inlet protein aggregation: a new mechanism for lubricating film formation with model synovial fluids

    , Proceedings of the Institution of Mechanical Engineers Part H - Journal of Engineering in Medicine, Vol: 225, Pages: 696-709, ISSN: 0954-4119

    This paper reports a fundamental study of lubricant film formation with model synovial fluid components (proteins) and bovine serum (BS). The objective was to investigate the role of proteins in the lubrication process. Film thickness was measured by optical interferometry in a ball-on-disc device (mean speed range of 2–60 mm/s). A commercial cobalt–chromium (CoCrMo) metal femoral head was used as the stationary component. The results for BS showed complex time-dependent behaviour, which was not representative of a simple fluid. After a few minutes sliding BS formed a thin adherent film of 10–20 nm, which was attributed to protein absorbance at the surface. This layer was augmented by a hydrodynamic film, which often increased at slow speeds. At the end of the test deposited surface layers of 20–50 nm were measured. Imaging of the contact showed that at slow speeds an apparent ‘phase boundary’ formed in the inlet just in front of the Hertzian zone. This was associated with the formation of a reservoir of high-viscosity material that periodically moved through the contact forming a much thicker film. The study shows that proteins play an important role in the film-forming process and current lubrication models do not capture these mechanisms.
  • Journal article
    Cope B, Cheung PYK, Luk W, Howes Let al., 2011,

    A systematic design space exploration approach to customising multi-processor architectures: Exemplified using graphics processors

    , Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), Vol: 6760 LNCS, Pages: 63-83, ISSN: 0302-9743

    A systematic approach to customising Homogeneous Multi-Processor (HoMP) architectures is described. The approach involves a novel design space exploration tool and a parameterisable system model. Post-fabrication customisation options for using reconfigurable logic with a HoMP are classified. The adoption of the approach in exploring pre- and post-fabrication customisation options to optimise an architecture's critical paths is then described. The approach and steps are demonstrated using the architecture of a graphics processor. We also analyse on-chip and off-chip memory access for systems with one or more processing elements (PEs), and study the impact of the number of threads per PE on the amount of off-chip memory access and the number of cycles for each output. It is shown that post-fabrication customisation of a graphics processor can provide up to four times performance improvement for negligible area cost. © 2011 Springer-Verlag Berlin Heidelberg.
  • Journal article
    Derntl M, Calvo RA, 2011,

    E-learning frameworks: Facilitating the implementation of educational design patterns

    , International Journal of Technology Enhanced Learning, Vol: 3, Pages: 284-296, ISSN: 1753-5255

    Educational design patterns hold the promise of facilitating the design of educational activities and environments. We have a number of completed initiatives and projects today, but none of them has had sustained impact on the practitioner community. In this paper, we argue that the use and usability of educational design patterns for technology-enhanced learning can be increased by complementing patterns with ready-to-use tools as part of an e-learning framework approach. We present two different approaches of conceiving such an e-learning framework: 1 an 'extension' approach that provides pattern-based, custom LMS components 2 a 'facade' approach that enables the pattern-based reuse of existing LMS components. To demonstrate the feasibility and benefits of e-learning frameworks we present implementations of both approaches. Copyright © 2011 Inderscience Enterprises Ltd.

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