• Behavioural Digital Forensics Model: Embedding Behavioural Evidence Analysis into the Investigation of Digital Crimes

      Al Mutawa, Noora; Bryce, Joanne; Franqueira, Virginia N.L.; Marrington, Andrew; Read, Janet C.; University of Derby (Elsevier, 2019-03)
      The state-of-the-art and practice show an increased recognition, but limited adoption, of Behavioural Evidence Analysis (BEA) within the Digital Forensics (DF) investigation process. Yet, there is currently no BEA-driven process model and guidelines for DF investigators to follow in order to take advantage of such an approach. This paper proposes the Behavioural Digital Forensics Model to fill this gap. It takes a multidisciplinary approach which incorporates BEA into in-lab investigation of seized devices related to interpersonal cases (i.e., digital crimes involving human interactions between offender(s) and victim(s)). The model was designed based on the application of traditional BEA phases to 35 real cases, and evaluated using 5 real digital crime cases - all from Dubai Police archive. This paper, however, provides details of only one case from this evaluation pool. Compared to the outcome of these cases using a traditional DF investigation process, the new model showed a number of benefits. It allowed a more effective focusing of the investigation, and provided logical directions for identifying the location of further relevant evidence. It also enabled a better understanding and interpretation of victim/offender behaviours (e.g., probable offenders' motivations and modus operandi), which facilitated a more in depth understanding of the dynamics of the specific crime. Finally, in some cases, it enabled the identification of suspect's collaborators, something which was not identified via the traditional investigative process.
    • On some results concerning the polygonal polynomials.

      Andrica, Dorin; Bagdasar, Ovidiu; Babeș-Bolyai University; University of Derby (Technical University of Cluj-Napoca., 2019-02-13)
      In this paper we define the $n$th polygonal polynomial $P_n(z) = (z-1)(z^2-1)\cdots(z^n-1)$ and we investigate recurrence relations and exact integral formulae for the coefficients of $P_n(z)$ and for those of the Mahonian polynomials $Q_n(z)=(z+1)(z^2+z+1)\cdots(z^{n-1}+\cdots+z+1)$. We also explore numerical properties of these coefficients, unraveling new meanings for old sequences and generating novel entries to the Online Encyclopedia of Integer Sequences (OEIS). Some open questions are also formulated.
    • Blockchain-Based Distributed Marketplace.

      Kabi, Oliver R.; Franqueira, Virginia N. L.; University of Derby (Springer Nature, 2019-01-03)
      Developments in Blockchain technology have enabled the creation of smart contracts; i.e., self-executing code that is stored and executed on the Blockchain. This has led to the creation of distributed, decentralised applications, along with frameworks for developing and deploying them easily. This paper describes a proof-of-concept system that implements a distributed online marketplace using the Ethereum framework, where buyers and sellers can engage in e-commerce transactions without the need of a large central entity coordinating the process. The performance of the system was measured in terms of cost of use through the concept of ‘gas usage’. It was determined that such costs are significantly less than that of Amazon and eBay for high volume users. The findings generally support the ability to use Ethereum to create a distributed on-chain market, however, there are still areas that require further research and development.
    • On the notion of mathematical genius: rhetoric and reality.

      Larcombe, Peter J.; University of Derby (Palestine Polytechnic University, 2019)
      The existential hypothesis of mathematical ‘genius’ rests irrefutably with the affirmative. We can’t all be one of course—that sublime solopreneur in creativity—but we may still contribute to research as lesser mortals. This short essay attempts to explore what the notion means to both us and non-mathematicians.
    • On generalised multi-index non-linear recursion identities for terms of the Horadam sequence.

      Larcombe, Peter J.; Fennessey, Eric J.; University of Derby (Palestine Polytechnic University, 2019)
      We state and prove a non-linear recurrence identity for terms of the so called Horadamsequence,andthenofferitsgeneralisationwhichisavailablefromthesamemethodology. We illustrate how the overarching idea may be used to sequentially produce extended versions, each in turn with an extra level of non-linearity and term index complexity. These identities can all be captured in matrix determinant form.
    • New proofs of linear recurrence identities for terms of the Horadam sequence.

      Larcombe, Peter J.; Fennessey, Eric J.; University of Derby (Palestine Polytechnic University, 2019)
      We state, and prove using matrices, two (related) linear recurrence identities for termsofthesocalledHoradamsequence;eachresultexpressesthegeneraltermofthesequence as a linear combination of terms with particular initial values. First offered by A.F. Horadam himself in the 1960s, our approach to their formulation is quite different and, we believe, new.
    • On an arithmetic triangle of numbers arising from inverses of analytic functions.

      Bagdasaryan, Armen G.; Bagdasar, Ovidiu; American University of the Middle East; University of Derby (Elsevier, 2018-12-06)
      The Lagrange inversion formula is a fundamental tool in combinatorics. In this work, we investigate an inversion formula for analytic functions, which does not require taking limits. By applying this formula to certain functions we have found an interesting arithmetic triangle for which we give a recurrence formula. We then explore the links between these numbers, Pascal’s triangle, and Bernoulli’s numbers, for which we obtain a new explicit formula. Furthermore, we present power series and asymptotic expansions of some elementary and special functions, and some links to the Online Encyclopedia of Integer Sequences (OEIS).
    • Some remarks on 3-partitions of multisets.

      Andrica, Dorin; Bagdasar, Ovidiu; Babeş-Bolyai University; University of Derby (Elsevier, 2018-12-06)
      Partitions play an important role in numerous combinatorial optimization problems. Here we introduce the number of ordered 3-partitions of a multiset M having equal sums denoted by S(m1, ..., mn; α1, ..., αn), for which we find the generating function and give a useful integral formula. Some recurrence formulae are then established and new integer sequences are added to OEIS, which are related to the number of solutions for the 3-signum equation.
    • On some new arithmetic functions involving prime divisors and perfect powers.

      Bagdasar, Ovidiu; Tatt, Ralph-Joseph; University of Derby (Elsevier, 2018-12-06)
      Integer division and perfect powers play a central role in numerous mathematical results, especially in number theory. Classical examples involve perfect squares like in Pythagora’s theorem, or higher perfect powers as the conjectures of Fermat (solved in 1994 by A. Wiles [8]) or Catalan (solved in 2002 by P. Mih˘ailescu [4]). The purpose of this paper is two-fold. First, we present some new integer sequences a(n), counting the positive integers smaller than n, having a maximal prime factor. We introduce an arithmetic function counting the number of perfect powers i j obtained for 1 ≤ i, j ≤ n. Along with some properties of this function, we present the sequence A303748, which was recently added to the Online Encyclopedia of Integer Sequences (OEIS) [5]. Finally, we discuss some other novel integer sequences.
    • Analytical tools for blockchain: review, taxonomy and open challenges.

      Balaskas, Anastasios; Franqueira, Virginia N. L.; University of Derby (IEEE Computer Society, 2018-12-06)
      Bitcoin has introduced a new concept that could feasibly revolutionise the entire Internet as it exists, and positively impact on many types of industries including, but not limited to, banking, public sector and supply chain. This innovation is grounded on pseudo-anonymity and strives on its innovative decentralised architecture based on the blockchain technology. Blockchain is pushing forward a race of transaction-based applications with trust establishment without the need for a centralised authority, promoting accountability and transparency within the business process. However, a blockchain ledger (e.g., Bitcoin) tend to become very complex and specialised tools, collectively called “Blockchain Analytics”, are required to allow individuals, law enforcement agencies and service providers to search, explore and visualise it. Over the last years, several analytical tools have been developed with capabilities that allow, e.g., to map relationships, examine flow of transactions and filter crime instances as a way to enhance forensic investigations. This paper discusses the current state of blockchain analytical tools and presents a thematic taxonomy model based on their applications. It also examines open challenges for future development and research.
    • Application of Two-Constant Feedback Quasi-Orthogonal Space Time Block Coding in MIMO Communication Systems

      Elazreg, Abdulghani; Elsabae, Ramadan; Shrud, Mohamed; Kharaz, Ahmad; University of Derby; Loughborough University; College of Electronic Technology, Tripoli, Libya (IEEE, 2018-12-03)
    • Evaluation of the AVHRR DeepBlue aerosol optical depth dataset over mainland China.

      Che, Yahui; Xue, Yong; Guang, Jie; She, Lu; Guo, Jianping; University of Derby; Chinese Academy of Sciences; Chinese Academy of Meteorological Sciences; University of Chinese Academy of Sciences (Elsevier, 2018-12)
      Advanced Very High Resolution Radiometer (AVHRR) on-board NOAA series satellites have been used to observe the Earth’s surface and clouds for almost 40 years. Limited by bands and problematic instrument calibration, aerosol studies using AVHRR data have focused on retrieving data over the ocean. However, continuous developments have made it possible to retrieve aerosol over land as well. The newly developed AVHRR Deep Blue (DB) technique has been applied to process global aerosol datasets over both land and the ocean during 1989–1990, 1995–1999 and 2006–2011. This paper aims to evaluate, in detail, the performance of the AVHRR DB aerosol optical depth (AOD) dataset over mainland China by comparison with both ground-based data and satellite aerosol products. The ground-based validation results show that DB AOD is close to ground-based AOD when AOD is moderate during winter, while DB underestimates AOD when AOD increases over 1.0 during summer over vegetated surfaces. AVHRR DB underestimates dry, urban and transitional surfaces in Western China due to the high uncertainty in low retrievals over bright surfaces. Cross-comparison with the Moderate-resolution imaging spectrometer (MODIS) DB aerosol dataset shows that the disadvantages of the single longer visible channel are greatly increased over bright surfaces. Together with problematic instrument calibration, the differences between the two datasets over most of mainland China are significant. Meanwhile, the differences show strong seasonal variation characteristics.
    • 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.
    • Dynamic diffuse signal processing for sound reinforcement and reproduction.

      Moore, Jonathan B.; Hill, Adam J.; University of Derby (Audio Engineering Society, 2018-11-16)
      High inter-channel coherence between signals emitted from multiple loudspeakers can cause undesirable acoustic and psychoacoustic effects. Examples include position-dependent low-frequency magnitude response variation, where comb-filtering leads to the attenuation of certain frequencies dependent on path length differences between multiple coherent sources, lack of apparent source width in multi-channel reproduction and lack of externalization in headphone reproduction. This work examines a time-variant, real-time decorrelation algorithm for the reduction of coherence between sources as well as between direct sound and early reflections, with a focus on minimization of low-frequency magnitude response variation. The algorithm is applicable to a wide range of sound reinforcement and reproduction applications, including those requiring full-band decorrelation. Key variables which control the balance between decorrelation and processing artifacts such as transient smearing are described and evaluated using a MUSHRA test. Variable values which render the processing transparent whilst still providing decorrelation are discussed. Additionally, the benefit of transient preservation is investigated and is shown to increase transparency.
    • Towards wireless technology for safety critical systems.

      Johnston, A B; Schiffers, W; Kharaz, Ahmad H.; Rolls-Royce plc; University of Derby (IOP Science, 2018-11-13)
      Wireless technology provides an unprecedented level of design flexibility for new system designs and legacy system updates. However, there are several challenges which present themselves when adopting wireless technologies for use in safety systems. This paper elaborates on available design techniques which can resolve the implementation issues for a given application, to ensure data communication between nodes is safe (deterministic), secure, reliable and available.
    • Live sound loudspeaker array optimization for consistent directional coverage with diffuse radiation characteristics.

      Hill, Adam J.; Hawksford, Malcolm O. J.; University of Derby; University of Essex (Institute of Acoustics, 2018-11)
      A central aim of sound reinforcement systems is to deliver consistent tonality across a wide audience area. Loudspeaker arrays are commonly used to meet this goal, where the upper and lower frequency bounds that can be spatially controlled are dictated by inter-element spacing and array width, respectively. This work focuses on the calculation of frequency-dependent complex coefficients for each array element using a modified Fourier technique to achieve a frequency-independent radiation pattern across an array’s functional region. In order to ensure efficiency, temporally diffuse impulses are utilized within the optimization procedure to avoid clustering of radiated energy at the center of an array and to provide a diffuse radiated field while maintaining the desired directional characteristics. Example applications for subwoofer arrays are presented, although the technique is applicable to any frequency range across the audible spectrum.
    • Investigation into the relationship between standing audience density and absorption.

      Hammond, Ross; Hill, Adam J.; Mapp, Peter; University of Derby; Peter Mapp Associates (Institute of Acoustics, 2018-11)
      Predicting acoustics of occupied performance venues is problematic due to difficulties in the selection of accurate audience absorption coefficients. The absorption due to a small group of people measured in a reverberation chamber cannot be accurately transferred to larger audiences due to differences between area to edge ratio. Analysis of data from an FDTD acoustic model of a reverberation chamber with an audience modelled as columns distributed at different densities with various perimeter to area ratios, allows derived absorption coefficients to be transferable to larger audience sizes. For densely-packed audiences, diffraction results in low frequencies having linear correlation between audience size and total absorption. There is less increase in total absorption per person at higher frequencies. Comparable real-world measurements confirm these findings, allowing the verified absorption coefficients to be applied to an acoustic model of a performance venue to inspect audience effects on absorption for typical configurations.
    • Development of ambisonic microphone design tools – Part 1.

      Middlicott, Charlie; Wiggins, Bruce; University of Derby (Audio Engineering Society, 2018-10-20)
      In recent years an increase in the capture and production of ambisonic material has occurred as a result of companies such as YouTube and Facebook utilising ambisonics for spatial audio playback. There is now a greater need for affordable higher order microphone arrays. This work details the development of a set of tools which can be used to simulate and evaluate such microphone arrays, The ‘Ambisonic Array Design Tool’ for simulation and ‘Ambisonic Array Evaluation Tool’ for evaluation. The microphone capsules’ position and directivity can be changed, with the effects on the synthesised spherical harmonics frequency and polar responses observed within the GUI. These scripts written in MatLab have been packaged within a GUI and will be available online.
    • Development of ambisonic microphone design tools – Part 1.

      Middlicott, Charlie; Wiggins, Bruce; University of Derby (Audio Engineering Society, 2018-10-20)
      In recent years an increase in the capture and production of ambisonic material has occurred as a result of companies such as YouTube and Facebook utilising ambisonics for spatial audio playback. There is now a greater need for affordable higher order microphone arrays. This work details the development of a set of tools which can be used to simulate and evaluate such microphone arrays, The ‘Ambisonic Array Design Tool’ for simulation and ‘Ambisonic Array Evaluation Tool’ for evaluation. The microphone capsules’ position and directivity can be changed, with the effects on the synthesised spherical harmonics frequency and polar responses observed within the GUI. These scripts written in MatLab have been packaged within a GUI and will be available online.
    • A framework for orchestrating secure and dynamic access of IoT services in multi-cloud environments.

      Kazim, Muhammad; Liu, Lu; Zhu, Shao Ying; Zheng, Yongjun; University of Derby (IEEE, 2018-10-16)
      IoT devices have complex requirements but their limitations in terms of storage, network, computing, data analytics, scalability and big data management require it to be used it with a technology like cloud computing. IoT backend with cloud computing can present new ways to offer services that are massively scalable, can be dynamically configured, and delivered on demand with largescale infrastructure resources. However, a single cloud infrastructure might be unable to deal with the increasing demand of cloud services in which hundreds of users might be accessing cloud resources, leading to a big data problem and the need for efficient frameworks to handle a large number of user requests for IoT services. These challenges require new functional elements and provisioning schemes. To this end, we propose the usage of multi-clouds with IoT which can optimize the user requirements by allowing them to choose best IoT services from many services hosted in various cloud platforms and provide them with more infrastructure and platform resources to meet their requirements. This paper presents a novel framework for dynamic and secure IoT services access across multi-clouds using cloud on-demand model. To facilitate multi-cloud collaboration, novel protocols are designed and implemented on cloud platforms. The various stages involved in the framework for allowing users access to IoT services in multi-clouds are service matchmaking (i.e. to choose the best service matching user requirements), authentication (i.e. a lightweight mechanism to authenticate users at runtime before granting them service access), and SLA management (including SLA negotiation, enforcement and monitoring). SLA management offers benefits like negotiating required service parameters, enforcing mechanisms to ensure that service execution in the external cloud is according to the agreed SLAs and monitoring to verify that the cloud provider complies with those SLAs. The detailed system design to establish secure multi-cloud collaboration has been presented. Moreover, the designed protocols are empirically implemented on two different clouds including OpenStack and Amazon AWS. Experiments indicate that proposed system is scalable, authentication protocols result only in a limited overhead compared to standard authentication protocols, and any SLA violation by a cloud provider could be recorded and reported back to the user.