• Cascaded multimodal biometric recognition framework

      Albesher, Badr; Kurugollu, Fatih; Bouridane, Ahmed; Baig, Asim; Queen's University, Belfast (IET, 2013-08-15)
      A practically viable multi-biometric recognition system should not only be stable, robust and accurate but should also adhere to real-time processing speed and memory constraints. This study proposes a cascaded classifier-based framework for use in biometric recognition systems. The proposed framework utilises a set of weak classifiers to reduce the enrolled users’ dataset to a small list of candidate users. This list is then used by a strong classifier set as the final stage of the cascade to formulate the decision. At each stage, the candidate list is generated by a Mahalanobis distance-based match score quality measure. One of the key features of the authors framework is that each classifier in the ensemble can be designed to use a different modality thus providing the advantages of a truly multimodal biometric recognition system. In addition, it is one of the first truly multimodal cascaded classifier-based approaches for biometric recognition. The performance of the proposed system is evaluated both for single and multimodalities to demonstrate the effectiveness of the approach.
    • Case studies: Using heuristics.

      Lowndes, Val; Bagdasar, Ovidiu; Berry, Stuart; University of Derby (Springer, 2017-04-14)
      The aim of these case studies is to demonstrate how large and complex decision-making problems can be “solved” using heuristic methods.
    • A case study on sound level monitoring and management at large-scale music festivals

      Hill, Adam J.; Kok, Marcel; Mulder, Johannes; Burton, Jon; Kociper, Alex; Berrios, Anthony; University of Derby; Murdoch University; dBcontrol; Gand Concert Sound (Institute of Acoustics, 2019-11)
      Sound level management at live events has been made immeasurably easier over the past decade or so through use of commercially-available sound level monitoring software. This paper details a study conducted at a large-scale multi-day music festival in Chicago, USA. The focus was twofold: first to explore how the use of noise monitoring software affects the mix level from sound engineers and second on how crowd size, density and distribution affect the mix level. Additionally, sound levels at various points in the audience were monitored to indicate audience sound exposure over the duration of the festival. Results are presented in relation to those from previous studies with key findings pointing towards recommendations for best practice.
    • A case study on the impact list event sound level regulations have on sound engineering practice

      Hill, Adam J.; Burton, Jon; University of Derby (Institute of Acoustics, 2020-11)
      Sound level management at live events in becoming increasingly common at live events in the UK, Europe and beyond. An inspection of regulations across the globe reveals a lack of standardization for sound level limits and averaging times. This case study is formed around a dataset generated on a recent tour by a well-known British musical act. The same sound engineer mixed the band throughout the tour using sound level monitoring software throughout. As the show’s configuration, engineer, musicians and running order were generally consistent day-to-day, the direct inspection of the influence of sound level limit and averaging time, as well as venue capacity and type (indoors or outdoors), is possible. The results from this study highlight both good and bad sound management practice, with key stakeholders’ experience and hearing safety in mind.
    • CCLBR: Congestion control-based load balanced routing in unstructured P2P systems

      Shen, Xiang-Jun; Chang, Qing; Liu, Lu; Panneerselvam, John; Zha, Zheng-Jun; University of Derby (2016-06-01)
      Given the growing popularity of the peer-to-peer (P2P) network systems in the recent years, efficient query routing under highly dynamic environments is still lacking in several P2P network systems. In response to this challenge, this paper proposes a new churn-resilient system to find alternative routing paths for the purpose of balancing the query loads under higher network churns and heavy workloads, ultimately to improve the search efficiency. Two novel methods are devised to balance the network query loads among both inter- and intragroup level peers. First, a resource grouping and a rewiring method is proposed to spontaneously organize and cluster the peers having same resources together. This strategy facilitates the peers to evolve the network into a cluster-like topology and balances the query loads among the intergroup peers. Second, a collaborative Q-learning method is proposed to balance the query loads among the intragroup peers in order to intelligently avoid queries being forwarded to the congested peers in the network. Experiments conducted under dynamic network scenarios demonstrate that our proposed method achieves better search performances with a more balanced network load than the existing methods, and further exhibits higher robustness and adaptability under higher network churns and heavy network loads.
    • Centrality and pseudorapidity dependence of the charged-particle multiplicity density in Xe–Xe collisions at √sNN = 5.44 TeV

      Barnby, Lee; Collaboration, ALICE; STFC Daresbury Laboratory (2018-12-21)
      In this Letter, the ALICE Collaboration presents the first measurements of the charged-particle multiplicity density, dNch/dη, and total charged-particle multiplicity, Nchtot, in Xe–Xe collisions at a centre-of-mass energy per nucleon–nucleon pair of √sNN = 5.44 TeV. The measurements are performed as a function of collision centrality over a wide pseudorapidity range of −3.5<η<5. The values of dNch/dη at mid-rapidity and Nchtot for central collisions, normalised to the number of nucleons participating in the collision (Npart) as a function of √sNN follow the trends established in previous heavy-ion measurements. The same quantities are also found to increase as a function of Npart, and up to the 5% most central collisions the trends are the same as the ones observed in Pb–Pb at a similar energy. For more central collisions, the Xe–Xe scaled multiplicities exceed those in Pb–Pb for a similar Npart. The results are compared to phenomenological models and theoretical calculations based on different mechanisms for particle production in nuclear collisions. All considered models describe the data reasonably well within 15%.
    • Centrality dependence of charged jet production in p–Pb collisions at √sNN = 5.02 TeV

      Alexandre, Didier; Barnby, Lee; Evans, David; Graham, Katie; Jones, Peter; Jusko, Anton; Krivda, Marian; Lee, Graham; Lietava, Roman; Villalobos, Orlando; et al. (2016-05-17)
    • Centrality dependence of J/ψ and ψ(2S) production and nuclear modification in p-Pb collisions at √sNN = 8.16 TeV

      Acharya, S.; Adamová, D.; Adler, A.; Adolfsson, J.; Aggarwal, M. M.; Agha, S.; Aglieri Rinella, G.; Agnello, M.; Agrawal, N.; Ahammed, Z.; et al. (Springer Science and Business Media LLC, 2021-02-01)
      The inclusive production of the J/ψ and ψ(2S) charmonium states is studied as a function of centrality in p-Pb collisions at a centre-of-mass energy per nucleon pair √sNN = 8.16 TeV at the LHC. The measurement is performed in the dimuon decay channel with the ALICE apparatus in the centre-of-mass rapidity intervals −4.46 < ycms < −2.96 (Pb-going direction) and 2.03 < ycms < 3.53 (p-going direction), down to zero transverse momentum (pT). The J/ψ and ψ(2S) production cross sections are evaluated as a function of the collision centrality, estimated through the energy deposited in the zero degree calorimeter located in the Pb-going direction. The pT-differential J/ψ production cross section is measured at backward and forward rapidity for several centrality classes, together with the corresponding average ⟨pT⟩ and ⟨pT^2⟩ values. The nuclear effects affecting the production of both charmonium states are studied using the nuclear modification factor. In the p-going direction, a suppression of the production of both charmonium states is observed, which seems to increase from peripheral to central collisions. In the Pb-going direction, however, the centrality dependence is different for the two states: the nuclear modification factor of the J/ψ increases from below unity in peripheral collisions to above unity in central collisions, while for the ψ(2S) it stays below or consistent with unity for all centralities with no significant centrality dependence. The results are compared with measurements in p-Pb collisions at √sNN = 5.02 TeV and no significant dependence on the energy of the collision is observed. Finally, the results are compared with theoretical models implementing various nuclear matter effects.
    • Centrality dependence of pion freeze-out radii in Pb-Pb collisions at √sNN = 2.76  TeV

      Alexandre, Didier; Barnby, Lee; Bhasin, Anju; Bombara, Marek; Evans, David; Graham, Katie; Jones, Peter; Jusko, Anton; Krivda, Marian; Lee, Graham; et al. (2016-02-04)
    • Centrality dependence of the charged-particle multiplicity density at midrapidity in Pb-Pb collisions at √ s N N = 5.02  TeV.

      ALICE Collaboration; Barnby, Lee; University of Birmingham (APS Physics, 2016-06-03)
      The pseudorapidity density of charged particles, d N ch / d η , at midrapidity in Pb-Pb collisions has been measured at a center-of-mass energy per nucleon pair of √ s N N = 5.02     TeV . For the 5% most central collisions, we measure a value of 1943 ± 54 . The rise in d N ch / d η as a function of √ s N N is steeper than that observed in proton-proton collisions and follows the trend established by measurements at lower energy. The increase of d N ch / d η as a function of the average number of participant nucleons, ⟨ N part ⟩ , calculated in a Glauber model, is compared with the previous measurement at √ s N N = 2.76     TeV . A constant factor of about 1.2 describes the increase in d N ch / d η from √ s N N = 2.76 to 5.02 TeV for all centrality classes, within the measured range of 0%–80% centrality. The results are also compared to models based on different mechanisms for particle production in nuclear collisions.
    • Centrality dependence of the nuclear modification factor of charged pions, kaons, and protons in Pb-Pb collisions at √sNN = 2.76 TeV

      Alexandre, Didier; Barnby, Lee; Evans, David; Graham, Katie; Jones, Peter; Jusko, Anton; Krivda, Marian; Lee, Graham; Lietava, Roman; Zardoshti, Nima; et al. (2016-03-25)
    • Centrality dependence of ψ(2S) suppression in p-Pb collisions at √sNN = 5.02TeV

      Jones, Peter; Alexandre, Didier; Barnby, Lee; Evans, David; Graham, Katie; Jusko, Anton; Krivda, Marian; Lee, Graham; Lietava, Roman; Villalobos, Orlando; et al. (2016-06-08)
    • Centrality evolution of the charged-particle pseudorapidity density over a broad pseudorapidity range in Pb–Pb collisions at √sNN = 2.76 TeV.

      ALICE Collaboration; Barnby, Lee; University of Birmingham (Elsevier, 2016-01-26)
      The centrality dependence of the charged-particle pseudorapidity density measured with ALICE in Pb–Pb collisions at √sNN = 2.76 TeV over a broad pseudorapidity range is presented. This Letter extends the previous results reported by ALICE to more peripheral collisions. No strong change of the overall shape of charged-particle pseudorapidity density distributions with centrality is observed, and when normalised to the number of participating nucleons in the collisions, the evolution over pseudorapidity with centrality is likewise small. The broad pseudorapidity range (−3.5 < η < 5) allows precise estimates of the total number of produced charged particles which we find to range from 162 ± 22(syst.) to 17170 ± 770(syst.) in 80–90% and 0–5% central collisions, respectively. The total charged-particle multiplicity is seen to approximately scale with the number of participating nucleons in the collision. This suggests that hard contributions to the charged-particle multiplicity are limited. The results are compared to models which describe dNch/dη at mid-rapidity in the most central Pb–Pb collisions and it is found that these models do not capture all features of the distributions
    • Challenges of data provenance for cloud forensic investigations

      Katilu, Victoria M.; Franqueira, Virginia N. L.; Angelopoulou, Olga; University of Derby (IEEE Computer Society, 2015-08)
      Cloud computing has gained popularity due to its efficiency, robustness and cost effectiveness. Carrying out digital forensic investigations in the cloud is currently a relevant and open issue. The root of this issue is the fact that servers cannot be physically accessed, coupled with the dynamic and distributed nature of cloud computing with regards to data processing and storage. This renders traditional methods of evidence collection impractical. The use of provenance data in cloud forensics is critical as it provides forensic investigators with data history in terms of people, entities and activities involved in producing related data objects. Therefore, cloud forensics requires effective provenance collection mechanisms. This paper provides an overview of current provenance challenges in cloud computing and identifies limitations of current provenance collection mechanisms. Recommendations for additional research in digital provenance for cloud forensics are also presented.
    • Channel and timeslot co-scheduling with minimal channel switching for data aggregation in MWSNs.

      Yeoum, Sanggil; Kang, Byungseok; Lee, Jinkyu; Choo, Hyunseung; Sungkyunkwan University (MDPI, 2017-05-04)
      Collision-free transmission and efficient data transfer between nodes can be achieved through a set of channels in multichannel wireless sensor networks (MWSNs). While using multiple channels, we have to carefully consider channel interference, channel and time slot (resources) optimization, channel switching delay, and energy consumption. Since sensor nodes operate on low battery power, the energy consumed in channel switching becomes an important challenge. In this paper, we propose channel and time slot scheduling for minimal channel switching in MWSNs, while achieving efficient and collision-free transmission between nodes. The proposed scheme constructs a duty-cycled tree while reducing the amount of channel switching. As a next step, collision-free time slots are assigned to every node based on the minimal data collection delay. The experimental results demonstrate that the validity of our scheme reduces the amount of channel switching by 17.5%, reduces energy consumption for channel switching by 28%, and reduces the schedule length by 46%, as compared to the existing schemes.
    • Characterisation of large changes in wind power for the day-ahead market using a fuzzy logic approach

      Martínez-Arellano, Giovanna; Nolle, Lars; Cant, Richard; Lotfi, Ahmad; Windmill, Christopher; Nottingham Trent University (Springer Science and Business Media LLC, 2014-08-21)
      Wind power has become one of the renewable resources with a major growth in the electricity market. However, due to its inherent variability, forecasting techniques are necessary for the optimum scheduling of the electric grid, specially during ramp events. These large changes in wind power may not be captured by wind power point forecasts even with very high resolution numerical weather prediction models. In this paper, a fuzzy approach for wind power ramp characterisation is presented. The main benefit of this technique is that it avoids the binary definition of ramp event, allowing to identify changes in power output that can potentially turn into ramp events when the total percentage of change to be considered a ramp event is not met. To study the application of this technique, wind power forecasts were obtained and their corresponding error estimated using genetic programming and quantile regression forests. The error distributions were incorporated into the characterisation process, which according to the results, improve significantly the ramp capture. Results are presented using colour maps, which provide a useful way to interpret the characteristics of the ramp events.
    • Characterizations of generalized exponential trichotomies for linear discrete-time systems.

      Popa, Ioan-Lucian; Ceauşu, Traian; Bagdasar, Ovidiu; University of Derby (Elsevier, 2016-12-01)
      The generalized exponential trichotomy (g.e.t) concept is explored for linear time varying systems. Characterizations and relations with the notion of uniform exponential trichotomy (u.e.t) in the sense of Elaydi-Janglajew are also provided.
    • Charge-dependent flow and the search for the chiral magnetic wave in Pb-Pb collisions at √sNN = 2.76 TeV

      Alexandre, Didier; Barnby, Lee; Evans, David; Graham, Katie; Jones, Peter; Jusko, Anton; Krivda, Marian; Lee, Graham; Lietava, Roman; Villalobos, Orlando; et al. (2016-04-08)
    • Charged jet cross sections and properties in proton-proton collisions at √s = 7 TeV

      Alexandre, Didier; Barnby, Lee; Bhasin, Anju; Bhat, Inayat; Evans, David; Hanratty, Luke; Jones, Peter; Jusko, Anton; Krivda, Marian; Lietava, Roman; et al. (2015-06-22)
    • Charged-particle multiplicities in proton–proton collisions at √s = 0.9 to 8 TeV

      Alexandre, Didier; Barnby, Lee; Evans, David; Graham, Katie; Jones, Peter; Jusko, Anton; Krivda, Marian; Lee, Graham; Lietava, Roman; Villalobos, Orlando; et al. (2017-01-17)