Recent Submissions

  • NOTRINO: a NOvel hybrid TRust management scheme for INternet-Of-vehicles

    Ahmad, Farhan; Kurugollu, Fatih; Kerrache, Chaker Abdelaziz; Sezer, Sakir; Liu, Lu; Coventry University; University of Derby; Universit Amar Telidji Laghouat, 243326 Laghouat, Laghouat, Algeria; Queen's University Belfast; University of Leicester (IEEE, 2021-01-05)
    Internet-of-Vehicles (IoV) is a novel technology to ensure safe and secure transportation by enabling smart vehicles to communicate and share sensitive information with each other. However, the realization of IoV in real-life depends on several factors, including the assurance of security from attackers and propagation of authentic, accurate and trusted information within the network. Further, the dissemination of compromised information must be detected and vehicle disseminating such malicious messages must be revoked from the network. To this end, trust can be integrated within the network to detect the trustworthiness of the received information. However, most of the trust models in the literature relies on evaluating node or data at the application layer. In this study, we propose a novel hybrid trust management scheme, namely, NOTRINO, which evaluates trustworthiness on the received information in two steps. First step evaluates trust on the node itself at transport layer, while second step computes trustworthiness of the data at application layer. This mechanism enables the vehicles to efficiently model and evaluate the trustworthiness on the received information. The performance and accuracy of NOTRINO is rigorously evaluated under various realistic trust evaluation criteria (including precision, recall, F-measure and trust). Furthermore, the efficiency of NOTRINO is evaluated in presence of malicious nodes and its performance is benchmarked against three hybrid trust models. Extensive simulations indicate that NOTRINO achieve over 75% trust level as compared to benchmarked trust models where trust level falls below 60% for a network with 35% malicious nodes. Similarly, 92% precision and 87% recall are achieved simultaneously with NOTRINO for the same network, comparing to benchmark trust models where precision and recall falls below 87% and 85% respectively.
  • Machinability of INCONEL718 alloy with a porous microstructure produced by laser melting powder bed fusion at higher energy densities

    Wood, Paul; Díaz-Álvarez, Antonio; Díaz-Álvarez, José; Miguélez, María Henar; Rusinek, Alexis; Williams, Gavin; Bahi, Slim; Sienkiewicz, Judyta; Płatek, Paweł; Gunputh, Urvashi Fowdar; et al. (MDPI, 2020-12-15)
    Products produced by additive manufacturing (AM) seek to exploit net shape manufacturing by eliminating or minimizing post-process stages such as machining. However, many applications which include turbo machinery components with tight dimensional tolerances and a smooth surface finish will require at least a light machine finishing stage. This paper investigates the machinability of the additively fabricated INCONEL718 (IN718) alloy produced by laser melting powder bed fusion (LM-PBF) with different levels of spherical porosity in the microstructure. The literature suggests that the band width for laser energy density, which combines the various scan process parameters to obtain a low spherical type porosity in the LM-PBF IN718 alloy (~1%), has wide breadth. With the increasing laser energy density and above a threshold, there is a rapid increase in the spherical pore size. In this paper, three tube samples each with different levels of spherical porosity were fabricated by varying the laser energy density for LM-PBF of the IN718 alloy within the stable and higher energy density range and the porosity measured. A low laser energy density was avoided due to balling up, which promotes highly irregular lack of fusion defects and poor consolidation within the alloy microstructure. An orthogonal turning test instrumented, with a three-component dynamometer to measure the cutting forces, was performed on AM produced IN718 tube samples under light cut conditions to simulate a finish machining process. The orthogonal turning tests were also performed on a tube sample obtained from the wrought extruded stock. The machining process parameters, which were studied include varying the cutting speed at three levels, at a fixed feed and under dry cut conditions for a short duration to avoid the tool wear. The results obtained were discussed and a notable finding was the higher rate of built-up-edge formation on the tool tip from the AM samples with a higher porosity and especially at a higher cutting speed. The paper also discusses the mechanisms that underpin the findings.
  • A novel structure of a modular interleaved DC/DC converter for renewable street lighting systems

    Alargt, Farag S.; Ashur, Ahmed S.; Kharaz, Ahmad H.; The Centre for Solar Energy Research and Studies, Tripoli, Libya; The Department of Electrical and Electronic Engineering, University of Tripoli, Tripoli, Libya; University of Derby (IEEE, 2018-12-13)
    The conventional structure of the renewable street lighting systems required two converters. A buck converter used for battery charging during the day, and a boost converter used to supply power to the lighting system from the battery during night. Combining the two converters is desirable as both cost and size are reduced. In this paper, a novel structure of a modular interleaved DC/DC converter with PWM/PID control technique for renewable street lighting system is presented. During the day, the proposed converter works in a buck mode and is used to charge the battery. at night, the converter works in a boost mode to provide power to the lighting system. Analysis of the converter is carried out in order to achieve the required system stability and to improve its dynamic performance. The operating principle and boundary conditions are discussed too. All the advantages of interleaving technique, such as higher efficiency and reduced ripple for voltage/current, are also maintained. The simulation results are presented to show the performance of the proposed converter.
  • The number of partitions of a set and Superelliptic Diophantine equations

    Andrica, Dorin; Bagdasar, Ovidiu; Ţurcaş, George Cătălin; “Babeş-Bolyai” University, Cluj-Napoca, Romania; University of Derby; The Institute of Mathematics of the Romanian Academy “Simion Stoilow” Bucharest, Romania (Springer, 2020-11-22)
    In this chapter we start by presenting some key results concerning the number of ordered k-partitions of multisets with equal sums. For these we give generating functions, recurrences and numerical examples. The coefficients arising from these formulae are then linked to certain elliptic and superelliptic Diophantine equations, which are investigated using some methods from Algebraic Geometry and Number Theory, as well as specialized software tools and algorithms. In this process we are able to solve some recent open problems concerning the number of solutions for certain Diophantine equations and to formulate new conjectures.
  • WHAM - Webcam Head-tracked AMbisonics

    Dring, Mark; Wiggins, Bruce; University of Derby (Institute of Acoustics, 2020-11-19)
    This paper describes the development and implementation of a real-time head-tracked auralisation platform using Higher Order Ambisonics (HOA) decoded binaurally based on open-source and freely available web technologies without the need for specialist head-tracking hardware. An example implementation of this work can be found at https://brucewiggins.co.uk/WHAM/.
  • A repairing missing activities approach with succession relation for event logs

    Liu, Jie; Xu, Jiuyun; Zhang, Ruru; Reiff-Marganiec, Stephan; China University of Petroleum; The China Mobile (Suzhou) Software Technology Company, Suzhou, China; University of Derby (Springer, 2020-11-11)
    In the field of process mining, it is worth noting that process mining techniques assume that the resulting event logs can not only continuously record the occurrence of events but also contain all event data. However, like in IoT systems, data transmission may fail due to weak signal or resource competition, which causes the company’s information system to be unable to keep a complete event log. Based on a incomplete event log, the process model obtained by using existing process mining technologies is deviated from actual business process to a certain degree. In this paper, we propose a method for repairing missing activities based on succession relation of activities from event logs. We use an activity relation matrix to represent the event log and cluster it. The number of traces in the cluster is used as a measure of similarity calculation between incomplete traces and cluster results. Parallel activities in selecting pre-occurrence and post-occurrence activities of missing activities from incomplete traces are considered. Experimental results on real-life event logs show that our approach performs better than previous method in repairing missing activities.
  • The challenges of teaching design in the 21st century, the age of the fourth industrial revolution

    Sole, Martin; Barber, Patrick; Harmanto, Dani; University of Derby (The Design Society - Institution of Engineering Designers, 2020-09-12)
    There is an ever-growing demand from industry for qualified design engineers. Many of these design engineers are trained at universities and colleges. This paper will explore how to keep this training as up to date and relevant as possible. It will look at the modern techniques and methods used by world-leading industries during the 21st century. This century, known also as the Fourth Industrial Revolution, or the Information Technology Revolution. It will show how these techniques and methods can be applied in academia. A challenge is also highlighted, how to get students to design to industry standards but at the same time make it possible to assess their work to satisfy the needs of academia and awarding bodies. These modern techniques and methods will be applied to actual university students and an assessment made of the results. Use of group working will be explored and an algorithm developed to grade the completed group work. What do students need now to equip them to become competent designers, and what will they need soon?
  • Permeability characterization of braided fabrics made of hemp fibers

    Rubino, Felice; Corbin, Anne-Clémence; Ferreira, Manuela; Labbanieh, Ahmad Rashed; Sanguigno, Luigi; Soulat, Damien; Maligno, Angelo; University of Derby; University of Lille, Ensait, Gemtex, F-59000, Roubaix, France (AIP Publishing, 2019-07-02)
    Reinforcement permeability represents crucial parameters in the manufacturing of fiber reinforced composites by liquid composite molding processes (LCM) [1]. Evaluation of fabric permeability is usually challenging and it requires several flow experiments. Indeed, permeability usually presents different values due to the anisotropic nature of textiles and different values have to be evaluated to calculate the permeability tensor. In addition, different flow conditions could establish during the impregnation: macroscopic and microscopic flow through the inter- and intra-tow leading to unevenly wetted regions of the fabric. Finally, differently from synthetic fibers, natural fibers can absorb fluid, acting as a sink, drawing fluid from the main flow and causing swelling of the natural fibers. In this work unsaturated permeability of braided hemp fabrics are studied for different architectures. Two type of braided fabric were investigated: triaxial and biaxial braids. Three distinct values of braiding angle, namely 45°, 50° and 60° were adopted for the biaxial braid to assess the impact of the braiding angle on the reinforcement permeability. The relation between permeability, porosity and fabric architecture was obtained in the case of the Vacuum Assisted Resin Infusion process.
  • Intelligent price alert system for digital assets - cryptocurrencies

    Chhem, Sronglong; Anjum, Ashiq; Arshad, Bilal; University of Derby (ACM Press, 2019-12)
    Cryptocurrency market is very volatile, trading prices for some tokens can experience a sudden spike up or downturn in a matter of minutes. As a result, traders are facing difficulty following with all the trading price movements unless they are monitoring them manually. Hence, we propose a real-time alert system for monitoring those trading prices, sending notifications to users if any target prices match or an anomaly occurs. We adopt a streaming platform as the backbone of our system. It can handle thousands of messages per second with low latency rate at an average of 19 seconds on our testing environment. Long-Short-Term-Memory (LSTM) model is used as an anomaly detector. We compare the impact of five different data normalisation approaches with LSTM model on Bitcoin price dataset. The result shows that decimal scaling produces only Mean Absolute Percentage Error (MAPE) of 8.4 per cent prediction error rate on daily price data, which is the best performance achieved compared to other observed methods. However, with one-minute price dataset, our model produces higher prediction error making it impractical to distinguish between normal and anomaly points of price movement.
  • Impact of social distancing to mitigate the spread of COVID-19 in a virtual environment

    Marti-Mason, Diego; Kapinaj, Matej; Pinel-Martínez, Alejandro; Stella, Leonardo; University of Derby (The Association for Computing Machinery, 2020-11-01)
    A novel strand of Coronavirus has spread in the past months to the point of becoming a pandemic of massive proportions. In order to mitigate the spread of this disease, many different policies have been adopted, including a strict national lockdown in some countries or milder government policies: one common aspect is that they mostly rely around keeping distance between individuals. The aim of this work is to provide means of visualizing the impact of social distancing in an immersive environment by making use of the virtual reality technology. To this aim, we create a virtual environment which resembles a university setting (we based it on the University of Derby), and populate it with a number of AI agents. We assume that the minimum social distance is 2 meters. The main contribution of this work is twofold: the multi-disciplinary approach that results from visualizing the social distancing in an effort to mitigate the spread of the COVID-19, and the digital twin application in which the users can navigate the virtual environment whilst receiving visual feedback in the proximity of other agents. We named our application SoDAlVR, which stands for Social Distancing Algorithm in Virtual Reality.
  • Computational study of flow around 2D and 3D tandem bluff bodies

    Charles, Terrance; Yang, Zhiyin; Lu, Yiling; University of Derby (Shahid Chamran University of Ahvaz, 2020-11-21)
    Numerical simulations have been carried out to advance our current understanding of flow around two dimensional (2D) and three dimensional (3D) square shaped tandem bluff bodies at a Reynolds number of 22,000, especially to shed light on the sudden change of the downstream body’s drag coefficient. The Reynolds-Averaged Navier-Stokes (RANS) approach has been employed in the present study and the predicted drag coefficients compare reasonably well with available experimental data. Better understanding of flow fields has been achieved by analyzing streamlines, velocity vectors for both 2D and 3D cases in a horizontal plane and a vertical symmetric plane. The sudden jump in drag coefficient for the 2D case is well captured numerically, which is due to the flow over the upstream body impinging onto the front face of the downstream body at a critical gap size between those two bodies. For the 3D case the drag coefficient is predicted to increase gradually, consistent with the previous experimental finding. This is due to the fact that the vortical structures formed in the 3D case are very different, resulting in a reasonably smooth change of the flow field around the upstream body and hence leading to gradual, not sudden, increase in the drag coefficient of the downstream body.
  • Smart anomaly detection in sensor systems: A multi-perspective review

    Erhan, L.; Ndubuaku, M.; Di Mauro, M.; Song, W.; Chen, M.; Fortino, G.; Bagdasar, O.; Liotta, A.; University of Derby; University of Salerno, Italy; et al. (Elsevier, 2020-10-15)
    Anomaly detection is concerned with identifying data patterns that deviate remarkably from the expected behavior. This is an important research problem, due to its broad set of application domains, from data analysis to e-health, cybersecurity, predictive maintenance, fault prevention, and industrial automation. Herein, we review state-of-the-art methods that may be employed to detect anomalies in the specific area of sensor systems, which poses hard challenges in terms of information fusion, data volumes, data speed, and network/energy efficiency, to mention but the most pressing ones. In this context, anomaly detection is a particularly hard problem, given the need to find computing-energy-accuracy trade-offs in a constrained environment. We taxonomize methods ranging from conventional techniques (statistical methods, time-series analysis, signal processing, etc.) to data-driven techniques (supervised learning, reinforcement learning, deep learning, etc.). We also look at the impact that different architectural environments (Cloud, Fog, Edge) can have on the sensors ecosystem. The review points to the most promising intelligent-sensing methods, and pinpoints a set of interesting open issues and challenges.
  • The design and optimisation of surround sound decoders using heuristic methods

    Wiggins, Bruce; Berry, Stuart; Lowndes, Val; Paterson-Stephens, Iain; University of Derby (2003-04-09)
    Surround sound has, for a number of years, had the standard of an irregular five-speakers layout (as defined by the ITU), but this is most likely set to expand to 7,9 or more, speaker configurations. The Ambisonic system, pioneered by Micheal Gerzon in the late 1960s, is very well suited to situations where the end system speaker configuration is not fixed in terms of number or position. However, while designing Ambisonic decoders for a regular (e.g. hexagonal) layout is well documented, optimising the decoders for irregular layouts is not a simple task, when optimisation requires the solution of a set of non-linear simultaneous equations [1 – Gerzon & Barton]. This paper describes an alternative approach to the determination of these “optimised coefficients”. This approach, based on a Tabu Search methodology [2 – Berry & Lowndes], efficiently determined sets of alternative optimal settings which were better (in terms of the reviewed parameters) than the results obtained using the standard analytical methods.
  • Effective solder for improved thermo-mechanical reliability of solder joints in ball grid array (BGA) soldered on printed circuit board (PCB)

    Depiver, Joshua; Sabuj, Mallik; Amalu, Emeka H; University of Derby; Teeside University (Springer, 2020-11-05)
    Ball grid array (BGA) packages have increasing applications in mobile phones, disk drives, LC displays and automotive engine controllers. However, the thermo-mechanical reliability of the BGA solder joints challenges the device functionality amidst component and system miniaturisation as well as wider adoption of lead-free solders. This investigation determines the effective BGA solders for improved thermo-mechanical reliability of the devices. It utilised a conducted study on creep response of a lead-based eutectic Sn63Pb37 and four lead-free Tin-Silver-Copper (SnAgCu) [SAC305, SAC387, SAC396 and SAC405] solders subjected to thermal cycling loadings and isothermal ageing. The solders form the joints between the BGAs and printed circuit boards (PCBs). ANSYS R19.0 package is used to simulate isothermal ageing of some of the assemblies at -40℃, 25℃, 75℃ and 150℃ temperatures for 45 days and model the thermal cycling history of the other assemblies from 22℃ ambient temperature for six cycles. The response of the solders is simulated using Garofalo-Arrhenius creep model. Under thermal ageing, SAC396 solder joints demonstrate possession of least strain energy density, deformation and von-Mises stress in comparison to the other solders. Under thermal cycle loading conditions, SAC405 acquired the lowest amount of the damage parameters in comparison. Lead-free SAC405 and SAC387 joints accumulated the lowest and highest energy dissipation per cycle, respectively. It is concluded that SAC405 and SAC396 are the most effective solders for BGA in devices experiencing isothermal ageing and temperature cycling during operation, respectively. They are proposed as the suitable replacement of eutectic Sn63Pb37 solder for the various conditions.
  • Research and implementation of intelligent decision based on a priori knowledge and DQN algorithms in wargame environment

    Sun, Yuxiang; Yuan, Bo; Zhang, Tao; Tang, Bojian; Zheng, Wanwen; Zhou, Xianzhong; University of Derby; Nanjing University, China (MDPI AG, 2020-10-13)
    The reinforcement learning problem of complex action control in a multi-player wargame has been a hot research topic in recent years. In this paper, a game system based on turn-based confrontation is designed and implemented with state-of-the-art deep reinforcement learning models. Specifically, we first design a Q-learning algorithm to achieve intelligent decision-making, which is based on the DQN (Deep Q Network) to model complex game behaviors. Then, an a priori knowledge-based algorithm PK-DQN (Prior Knowledge-Deep Q Network) is introduced to improve the DQN algorithm, which accelerates the convergence speed and stability of the algorithm. The experiments demonstrate the correctness of the PK-DQN algorithm, it is validated, and its performance surpasses the conventional DQN algorithm. Furthermore, the PK-DQN algorithm shows effectiveness in defeating the high level of rule-based opponents, which provides promising results for the exploration of the field of smart chess and intelligent game deduction
  • Comparing and benchmarking fatigue behaviours of various sac solders under thermo-mechanical loading

    Depiver, Joshua Adeniyi; Mallik, Sabuj; Amalu, Emeka H; University of Derby (IEEE, 2020-10-23)
    While the fatigue behaviours (including fatigue life predictions) of lead-free solder joints have been extensively researched in the last 15 years, these are not adequately compared and benchmarked for different lead-free solders that are being used. As more and more fatigue properties of lead-free solders are becoming available, it is also critical to know how fatigue behaviours differ under different mathematical models. This paper addresses the challenges and presents a comparative study of fatigue behaviours of various mainstream lead-free Sn-Ag-Cu (SAC) solders and benchmarked those with lead-based eutectic solder. Creep-induced fatigue and fatigue life of lead-based eutectic Sn63Pb37 and four lead-free SAC solder alloys: SAC305, SAC387, SAC396 and SAC405 are analysed through simulation studies. The Anand model is used to simulate the inelastic deformation behaviour of the solder joints under accelerated thermal cycling (ATC). It unifies the creep and rate-independent plastic behaviour and it is used to predict the complex stress-strain relationship of solders under different temperatures and strain rates, which are required in the prediction of fatigue life using the fatigue life models such as Engelmaier, Coffin-Mason and Solomon as the basis of our comparison. The ATC was carried out using temperature range from −40°C to 150°C. The fatigue damage propagation is determined with finite element (FE) simulation, which allows virtual prototyping in the design process of electronics devices. The simulation was carried out on a BGA (36 balls, 6 × 6 matrix) mounted onto Cu padded substrate. Results are analysed for plastic strain, Von mises stress, strain energy density, and stress-strain hysteresis loop. The simulation results show that the fatigue behaviours of lead-based eutectic Sn63Pb37 solder is comparable to those of lead-free SAC solders. Among the four SAC solders, SAC387 consistently produced higher plastic strain, strain energy and stress than the other solders. The fatigue life’s estimation of the solder joint was investigated using Engelmaier, Coffin-Manson, and Solomon models. Results obtained show that SAC405 has the highest fatigue life (25.7, 21.1 and 19.2 years) followed by SAC396 (18.7, 20.3 and 17.9 years) and SAC305 (15.2, 13.6 and 16.2 years) solder alloys respectively. Predicting the fatigue life of these solder joints averts problems in electronics design for reliability and quality, which if not taken care of, may result in lost revenue. Predictive fatigue analysis can also considerably reduce premature failure, and modern analysis technique such as one used in this research is progressively helping to provide comprehensive product life expectancy data.
  • Additive manufacturing of graded structures in IN718

    Wood, Paul; Gunputh, Urvashi; University of Derby (2019-08)
    Workshop at LSU, USA 13th to 16th August 2019
  • Selective laser melting of a high precision turbomachinery application in IN718 alloy

    Wood, Paul; Gunputh, Urvashi; Williams, Gavin; Carter, Wayne; Boud, Fathi; Bahi, Slim; Rusinek, Alexis; Kowalewski, Zbigniew; Nowak, Zdzisław; Libura, Tomasz; et al. (2021)
    The paper describes the manufacture of an outlet guide vane (OGV) component, in IN718 alloy, used in jet engines by Selective Laser Melting (SLM). The OGV component is a static part in the last stage of the compressor and is characterised as a series of airfoils or vanes secured by two flanged rings. The part tolerances at the leading and trailing edge require a high dimensional precision of +/-0.072 m whilst the profile tolerances are slightly more generous. The current challenge to manufacture a prototype OGV in IN718 alloy from a wrought stock involves a lengthy machining process in a hard-to-machine alloy. The tooling access is greatly restricted between the curved vanes, and the process involves careful fixturing and process management to mitigate residual stress in the component arising from the removal of material.
  • Analysis of machining performance of Inconel 718 printed by PBF-LM (powder bed fusion laser melting)

    Diaz-Alvarez, A; Diaz-Alvarez, J; Wood, P; Gunputh, U; Rusinek, A; Miguelez, M; University of Derby (2021)
    Additive manufacturing based on powder bed fusion laser melting (PBF-LM) is receiving increased attention in nickel-base superalloys manufacturing, due to the difficulty of removal processes of superalloys. PBF-LM process involves the use of high-energy laser beam (continuous or pulsed) to melt a thin layer of metal powder under an inert or near-inert gas atmosphere. After rapid solidification, a new layer of powder is deposited and exposed again to the laser, repeating the process until the whole piece is obtained. The Inconel 718 alloy is one of the most widely used nickel-based alloys in jet engines and industrial steam turbines for components that operate at high temperature and require high resistance to fatigue and corrosion. Additive manufacturing processes commonly require further finishing operations in order to achieve dimensional and surface specifications of the workpiece. The present study focuses on the analysis of machining of Inconel 718 pieces manufactured through the PBF-LM process, when it is compared with the reference piece manufactured through conventional method. This paper investigates the cutting forces and the relationship to tool wear in machining Inconel 718 alloy obtained through the PBF-LM technique and conventional methods.
  • Selective laser melting of stainless steel 316L pressure fittings

    Wood, Paul; University of Derby (2019-04-19)
    Workshop presentation DYNAMAT, 17-19 April 2019, Nicosia, Cyprus.

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