• Local maximizers of generalized convex vector-valued functions.

      Bagdasar, Ovidiu; Popovici, Nicolae; University of Derby; Babes-Bolyai University (Yokohama Publishers, 2017-12)
      Any local maximizer of an explicitly quasiconvex real-valued function is actually a global minimizer, if it belongs to the intrinsic core of the function's domain. In this paper we show that similar properties hold for componentwise explicitly quasiconvex vector-valued functions, with respect to the concepts of ideal, strong and weak optimality. We illustrate these results in the particular framework of linear fractional multicriteria optimization problems.
    • Local maximum points of explicitly quasiconvex functions

      Bagdasar, Ovidiu; Popovici, Nicolae; University of Derby (Springer, 2014-08-17)
      This work concerns generalized convex real-valued functions defined on a nonempty convex subset of a real topological linear space. Its aim is twofold: first, to show that any local maximum point of an explicitly quasiconvex function is a global minimum point whenever it belongs to the intrinsic core of the function’s domain and second, to characterize strictly convex normed spaces by applying this property for a particular class of convex functions.
    • A location aware fast PMIPv6 for low latency wireless sensor networks

      Kang, Byungseok; University of Derby (IEEE, 2019-06-28)
      Recently, mobile sensor networks (MSN) have been actively studied due to the emergence of mobile sensors such as Robomote and robotic sensor agents (RSAs). The research on existing mobile sensor networks mainly focuses on solving the coverage hole, which is a problem that occurs in the existing stationary sensor network (SSN). These studies have disadvantages in that they cannot make the most use of the mobile ability given to the moving sensors. In order to solve this problem, there is a proposal for sensing a wider area than a fixed sensor network by giving the moving sensor continuous mobility. However, the research is still in the early stage, and communication path to the sink node and data transmission problems. In this paper, we propose a location-aware fast PMIPv6 (LA-FPMIPv6) protocol that enables efficient routing and data transmission in a mobile sensor network environment composed of mobile sensors with continuous mobility. In the proposed protocol, the fixed sensor is arranged with the moving sensor so that the fixed sensor transmits the sensing data to the sink node instead of the moving sensor. For performance evaluation, the LA-FPMIPv6 is compared with existing methods through mathematical analysis and computer simulation. The results of the performance evaluation show that the LA-FPMIPv6 effectively reduces the handover latency, signaling cost, and buffering cost compared with the conventional methods.
    • Location based services analytics: Students as co-producers and partners in research

      Self, Richard; University of Derby (2015-08)
      A perennial question in teaching is that of inspiring students to become innova-tive in their thinking and work. This paper presents one approach to developing excellence in undergraduate analytics research into a leading-edge topic which has had few publications to-date. The resultant analytics has provided valuable in-sights into the accuracy profiles of Location Services in smart devices and identi-fied important consequences of the levels of accuracy that Assisted GPS (A-GPS) exhibits. Consolidation of the research of eight students by this author has resulted in approximately 3000 data points, from which it is possible to develop significant analytical insights which are of value to a wide range of potential us-ers. It has also resulted in a raised academic and research profile for the Universi-ty of Derby in the LBS field.
    • Long-time series aerosol optical depth retrieval from AVHRR data over land in North China and Central Europe

      Xue, Yong; He, Xingwei; de Leeuw, Gerrit; Mei, Linlu; Che, Yahui; Rippin, Wayne; Guang, Jie; Hu, Yincui; University of Chinese Academy of Sciences; University of Derby; et al. (Elsevier, 2017-07-06)
      An algorithm for the retrieval of the aerosol optical depth over land (ADL) using radiances at the top of the atmosphere (TOA) measured by the Advanced Very High Resolution Radiometer (AVHRR) is proposed. AVHRR is the only satellite sensor providing nearly continuous global coverage since June 1979, which could generate the longest aerosol climate data records currently available from operational satellites. In the implementation of the ADL algorithm, an analytical model is used which couples an atmospheric radiative transfer model and a land surface reflectance parameterization. The radiation field can be separated into three parts: direct radiance, single-scattered radiance, and multiple-scattered. Each of these parts is individually parameterized. To obtain the surface reflectance in an automatic retrieval procedure over land for AVHRR, the aerosol scattering effect at 3.75 μm was assumed to be negligible and relationships between the surface reflectances at 0.64 μm and 3.75 μm were evaluated for different surface types and the authors propose to use these to obtain the surface reflectance at the shorter wavelength. The 0.64 μm surface reflectance was then used in a radiative transfer model to compute AOD at that wavelength using six different aerosol types, where optimal estimation (OE) theory is applied to minimize the difference between modeled and measured radiances. The ADL algorithm is applied to re-calibrated Level 1B radiances from the AVHRRs on-board the TIROS-N and the Metop-B satellites to retrieve the AOD over North China and Central Europe. The results show that the AOD retrieved from these two instruments are in agreement with co-located AOD values from ground-based reference networks. Over North China, using AERONET sites, 58% of the ADL AOD values are within an expected error (EE) range of ±(0.05 + 20%) and 53% are within the EE range of ±(0.05 + 15%). For GAW-PFR (World Meteorological Organization, WMO, Global Atmosphere Watch, GAW) sites, part of the European ACTRIS (Aerosols, Clouds, and Trace gases Research InfraStructure) sites, 79% of the ADL AOD values are within the EE range of ±(0.05 + 20%) and 75% are within the EE range of ±(0.05 + 15%). Not surprisingly, the agreement is better over Europe with generally lower AOD values. An additional cross comparison of the AOD results with MODIS (MODerate-resolution Imaging Spectroradiometer) DeepBlue aerosol products shows that the spatial distributions of the two AOD datasets are similar, but with generally lower values for ADL and lower coverage. The temporal variation of the annual mean AOD over selected AERONET sites shows that ADL values are generally between 0.2 and 0.5 over North-Eastern China and trace the MODIS and AERONET data for the overlapping years quite well.
    • Longitudinal asymmetry and its effect on pseudorapidity distributions in Pb–Pb collisions at √sNN = 2.76 TeV

      ALICE Collaboration; Barnby, Lee; STFC Daresbury Laboratory (Elsevier, 2018-03-22)
      First results on the longitudinal asymmetry and its effect on the pseudorapidity distributions in Pb–Pb collisions at √sNN = 2.76 TeV at the Large Hadron Collider are obtained with the ALICE detector. The longitudinal asymmetry arises because of an unequal number of participating nucleons from the two colliding nuclei, and is estimated for each event by measuring the energy in the forward neutron-Zero-Degree-Calorimeters (ZNs). The effect of the longitudinal asymmetry is measured on the pseudorapidity distributions of charged particles in the regions |η|<0.9, 2.8 < η < 5.1 and -3.7 < η < 1.7 by taking the ratio of the pseudorapidity distributions from events corresponding to different regions of asymmetry. The coefficients of a polynomial fit to the ratio characterise the effect of the asymmetry. A Monte Carlo simulation using a Glauber model for the colliding nuclei is tuned to reproduce the spectrum in the ZNs and provides a relation between the measurable longitudinal asymmetry and the shift in the rapidity (y0) of the participant zone formed by the unequal number of participating nucleons. The dependence of the coefficient of the linear term in the polynomial expansion, c1, on the mean value of y0 is investigated.
    • LQR controller design for quad-rotor helicopters.

      E. Okyere; A. bousbaine; G. T. Poyi; A.K. Joseph; J.M. Andrade; University of Derby (The Institute of Engineering and Technology., 2018-06-22)
      This paper presents an analysis and performance of a LQR control algorithm for quadrotor helicopters. For a successful analysis, first the dynamic model has been developed for the quadcopter and then the controller was designed, tuned and tested. In tuning the LQR, much attention was given to the feedback gain matrix (K). The controller’s performance wasverified in terms of delay time, rise time, overshoot, settling time and tolerance limits. The overall performance of theLQR controller was analysed.
    • M2M-REP: Reputation system for machines in the internet of things.

      Azad, Muhammad Ajmal; Bag, Samiran; Hao, Feng; Salah, Khaled; Newcastle University; Khalifa University (2018-08-14)
      In the age of IoT (Internet of Things), Machine-to-Machine (M2M) communication has gained significant popularity over the last few years. M2M communication systems may have a large number of autonomous connected devices that provide services without human involvement. Interacting with compromised, infected and malicious machines can bring damaging consequences in the form of network outage, machine failure, data integrity, and financial loss. Hence, users first need to evaluate the trustworthiness of machines prior to interacting with them. This can be realized by using a reputation system, which evaluates the trustworthiness of machines by utilizing the feedback collected from the users of the machines. The design of a reliable reputation system for the distributed M2M communication network should preserve user privacy and have low computation and communication overheads. To address these challenges, we propose an M2M-REP System (Machine to Machine REPutation), a privacy-preserving reputation system for evaluating the trustworthiness of autonomous machines in the M2M network. The system computes global reputation scores of machines while maintaining privacy of the individual participant score by using secure multi-party computation techniques. The M2M-REP system ensures correctness, security and privacy properties under the malicious adversarial model, and allows public verifiability without relying on a centralized trusted system. We implement a prototype of our system and evaluate the system performance in terms of the computation and bandwidth overhead.
    • Machine-learning-based side-channel evaluation of elliptic-curve cryptographic FPGA processor.

      Mukhtar, Naila; Mehrabi, Mohamad; Kong, Yinan; Anjum, Ashiq; University of Derby; Macquarie University (MDPI, 2018-12-25)
      Security of embedded systems is the need of the hour. A mathematically secure algorithm runs on a cryptographic chip on these systems, but secret private data can be at risk due to side-channel leakage information. This research focuses on retrieving secret-key information, by performing machine-learning-based analysis on leaked power-consumption signals, from Field Programmable Gate Array (FPGA) implementation of the elliptic-curve algorithm captured from a Kintex-7 FPGA chip while the elliptic-curve cryptography (ECC) algorithm is running on it. This paper formalizes the methodology for preparing an input dataset for further analysis using machine-learning-based techniques to classify the secret-key bits. Research results reveal how pre-processing filters improve the classification accuracy in certain cases, and show how various signal properties can provide accurate secret classification with a smaller feature dataset. The results further show the parameter tuning and the amount of time required for building the machine-learning models
    • Man-In-The-Middle attacks in Vehicular Ad-Hoc Networks: Evaluating the impact of attackers’ strategies.

      Ahmad, Farhan; Adnane, Asma; Franqueira, Virginia N. L.; Kurugollu, Fatih; Liu, Lu; University of Derby; Loughborough University (MDPI, 2018-11-20)
      Vehicular Ad-Hoc Network (VANET), a vital component of Intelligent Transportation Systems (ITS) technology, relies on communication between dynamically connected vehicles and static Road Side Units (RSU) to offer various applications (e.g., collision avoidance alerts, steep-curve warnings and infotainment). VANET has a massive potential to improve traffic efficiency, and road safety by exchanging critical information between nodes (vehicles and RSU), thus reducing the likelihood of traffic accidents. However, this communication between nodes is subject to a variety of attacks, such as Man-In-The-Middle (MITM) attacks which represent a major risk in VANET. It happens when a malicious node intercepts or tampers with messages exchanged between legitimate nodes. In this paper, we studied the impact on network performance of different strategies which attackers can adopt to launch MITM attacks in VANET, such as fleet or random strategies. In particular, we focus on three goals of MITM attacks—message delayed, message dropped and message tampered. The simulation results indicate that these attacks have a severe influence on the legitimate nodes in VANET as the network experience high number of compromised messages, high end-to-end delays and preeminent packet losses.
    • Managing peer-to-peer networks with human tactics in social interactions

      Liu, Lu; Antonopoulos, Nikolaos; Mackin, Stephen (2007-11-14)
    • Mapping evolution of dynamic web ontologies

      Khattak, A.M.; Pervez, Z.; Khan, Wajahat Ali; Khan, A.M.; Latif, K.; Lee, S.Y.; Zayed University, United Arab Emirates; University of the West of Scotland; Kyung Hee University, Republic of Korea; Innopolis University, Russia; et al. (Elsevier BV, 2015-01-03)
      Information on the web and web services that are revised by stakeholders is growing incredibly. The presentation of this information has shifted from a representational model of web information with loosely clustered terminology to semi-formal terminology and even to formal ontology. Mediation (i.e., mapping) is required for systems and services to share information. Mappings are established between ontologies in order to resolve terminological and conceptual incompatibilities. Due to new discoveries in the field of information sharing, the body of knowledge has become more structured and refined. The domain ontologies that represent bodies of knowledge need to be able to accommodate new information. This allows for the ontology to evolve from one consistent state to another. Changes in resources cause existing mappings between ontologies to be unreliable and stale. This highlights the need for mapping evolution (regeneration) as it would eliminate the discrepancies from the existing mappings. In order to re-establish the mappings between dynamic ontologies, the existing systems require a complete mapping process to be restructured, and this process is time consuming. This paper proposes a mapping reconciliation approach between the updated ontologies that has been found to take less time to process compared to the time of existing systems when only the changed resources are considered and also eliminates the staleness of the existing mappings. The proposed approach employs the change history of ontology in order to store the ontology change information, which helps to drastically reduce the reconciliation time of the mappings between dynamic ontologies. A comprehensive evaluation of the performance of the proposed system on standard data sets has been conducted. The experimental results of the proposed system in comparison with six existing mapping systems are provided in this paper using 13 different data sets, which support our claims.
    • MARINE: Man-in-the-middle attack resistant trust model IN connEcted vehicles

      Ahmad, Farhan; Kurugollu, Fatih; Adnane, Asma; Hussain, Rasheed; Hussain, Fatima; University of Derby; Loughborough university; Innopolis University, Russia; API Delivery & Operations, Royal Bank of Canada, Toronto, Canada (IEEE, 2020-01-17)
      Vehicular Ad-hoc NETwork (VANET), a novel technology holds a paramount importance within the transportation domain due to its abilities to increase traffic efficiency and safety. Connected vehicles propagate sensitive information which must be shared with the neighbors in a secure environment. However, VANET may also include dishonest nodes such as Man-in-the-Middle (MiTM) attackers aiming to distribute and share malicious content with the vehicles, thus polluting the network with compromised information. In this regard, establishing trust among connected vehicles can increase security as every participating vehicle will generate and propagate authentic, accurate and trusted content within the network. In this paper, we propose a novel trust model, namely, Man-in-the-middle Attack Resistance trust model IN connEcted vehicles (MARINE), which identifies dishonest nodes performing MiTM attacks in an efficient way as well as revokes their credentials. Every node running MARINE system first establishes trust for the sender by performing multi-dimensional plausibility checks. Once the receiver verifies the trustworthiness of the sender, the received data is then evaluated both directly and indirectly. Extensive simulations are carried out to evaluate the performance and accuracy of MARINE rigorously across three MiTM attacker models and the bench-marked trust model. Simulation results show that for a network containing 35% MiTM attackers, MARINE outperforms the state of the art trust model by 15%, 18%, and 17% improvements in precision, recall and F-score, respectively.
    • Matching Services with Users in Opportunistic Network Environments

      Smith, Anthony; Berry, Stuart; Hill, Richard; University of Derby (2014-07)
      Opportunistic Networks are a specific type of wireless ad hoc network where there is an absence of a continuous end-to-end path. The proliferation of mobile devices with Wi-Fi capability creates opportunities to forward packets by utilizing nodes as they present themselves. Such a dynamic networking environment enables services to be advertised by propagating from device to device, in order that all users in an area receive them. However, excessive propagation of service advertisements consumes energy from mobile devices, whilst also degrading the users' experience if they receive adverts for services that are misaligned with their personal interests. In this article we propose an architecture for a protocol and an algorithm that facilitates the matching of relevant service adverts with interested recipients in an Opportunistic Networking environment, whilst serving to minimize energy consumption.
    • Mathematical model of a constructional coanda effect nozzle.

      Trancossi, Michele; Stewart, Jill; Subhash, M; Angeli, Diego; Sheffield Hallam University (Physics Society of Iran., 2016)
      This paper analyses the ACHEON Coanda effect nozzle for aircraft propulsion, based on the dynamic equilibrium of two jet streams. The ACHEON concept, and, in particular, the HOMER nozzle, which is its main component, are presented, together with the literature milestones from which the idea originally stems. A subsystem analysis inspired by the principles of Constructal Theory is presented for the current architecture. A mathematical model of a 2D case of the system is developed, focusing on the combined effect of the mixing of the two streams and the Coanda adhesion over a convex surface. A validation of the model is also reported, based on 2D CFD analyses, under the hypothesis of incompressible flow. Results highlight that, in spite of its relative simplicity, the model produces accurate results.
    • Mathematicians can also write, right?

      Larcombe, Peter J; University of Derby (The Institute of Mathematics and its Applications (IMA), 2019)
    • Mathematics as a mirror of painting.

      Larcombe, Peter J.; University of Derby (Institute of Mathematics and its applications, 2017-12)
    • Measurement of azimuthal correlations of D mesons with charged particles in pp collisions at √s=7 TeV and p–Pb collisions at √sNN=5.02 TeV

      Barnby, Lee; Evans, David; Graham, Katie; Jones, Peter; Jusko, Anton; Lietava, Roman; Krivda, Marian; Alexandre, Didier; Villalobos, Orlando; Zardoshti, Nima; et al. (2017-04-17)
    • Measurement of charged jet production cross sections and nuclear modification in p–Pb collisions at √sNN = 5.02 TeV

      Alexandre, Didier; Barnby, Lee; Bhasin, Anju; Bombara, Marek; Evans, David; Hanratty, Luke; Jones, Peter; Jusko, Anton; Krivda, Marian; Lee, Graham; et al. (2015-10-07)
    • Measurement of D-meson production versus multiplicity in p-Pb collisions at √sNN = 5.02 TeV

      ALICE Collaboration; Barnby, Lee; University of Birmingham (Springer Berlin Heidelberg, 2016-08-11)
      The measurement of prompt D-meson production as a function of multiplicity in p-Pb collisions at √sNN=5.02 TeV with the ALICE detector at the LHC is reported. D0, D+ and D*+ mesons are reconstructed via their hadronic decay channels in the centre-of-mass rapidity range −0.96 < ycms< 0.04 and transverse momentum interval 1