• Wasserstein GAN based Chest X-Ray Dataset Augmentation for Deep Learning Models: COVID-19 Detection Use-Case

      Hussain, B. Zahid; Andleeb, Ifrah; Ansari, Mohammad Samar; Joshi, Amit Mahesh; Kanwal, Nadia; Aligarh Muslim University; University of Chester; Malaviya National Institute of Technology Jaipur; Keele University (IEEE, 2022-09-08)
      The novel coronavirus infection (COVID-19) is still continuing to be a concern for the entire globe. Since early detection of COVID-19 is of particular importance, there have been multiple research efforts to supplement the current standard RT-PCR tests. Several deep learning models, with varying effectiveness, using Chest X-Ray images for such diagnosis have also been proposed. While some of the models are quite promising, there still remains a dearth of training data for such deep learning models. The present paper attempts to provide a viable solution to the problem of data deficiency in COVID-19 CXR images. We show that the use of a Wasserstein Generative Adversarial Network (WGAN) could lead to an effective and lightweight solution. It is demonstrated that the WGAN generated images are at par with the original images using inference tests on an already proposed COVID-19 detection model.
    • Watchdog Monitoring for Detecting and Handling of Control Flow Hijack on RISC-V-based Binaries

      Oyinloye, Toyosi; Speakman, Lee; Eze, Thaddeus; O'Mahony, Lucas; University of Chester; University of Salford (SAI Organization, 2022-08-31)
      Abstract—Control flow hijacking has been a major challenge in software security. Several means of protections have been developed but insecurities persist. This is because existing protections have sometimes been circumvented while some resilient protections do not cover all applications. Studies have revealed that a holistic way of tackling software insecurity could involve watchdog monitoring and detection via Control Flow Integrity (CFI). The CFI concept has shown a good measure of reliability to mitigate control flow hijacking. However, sophisticated attack techniques in the form of Return Oriented Programming (ROP) have persisted. A flexible protection is desirable, which not only covers as many architecture structures as possible but also mitigates known resilient attacks like ROP. The solution proffered here is a hybrid of CFI and watchdog timing via inter-process signaling (IP-CFI). It is a software-based protection that involves recompilation of the target program. The implementation here is on vulnerable RISC-V-based process but is flexible and could be adapted on other architectures. We present a proof of concept in IP-CFI which when applied to a vulnerable program, ROP is mitigated. The target program incurs a run-time overhead of 1.5%. The code is available.
    • Water quality and water-rock interaction in the Harz Mountains (Germany)

      Bozau, Elke; Staerk, Hans-Joachim; Strauch, Gerhard; Swanson, Claudia H.; Technische Universitaet Clausthal, University of Chester (European Federation of Geologists, 2015-11-01)
      The Harz Mountains, known for ancient silver and base metal mining, are an important drinking water supply region for northern Germany today. The water quality of the Harz Mountains is mainly influenced by atmospheric depositions, water-rock inter- actions and biological activities. Anthropogenic influences are minor. Springs, creeks, lakes and reservoirs have relatively low mineralisation. Measured as specific electrical conductivity, the mineralisation of the different water bodies ranges from about 15 to 650 µS/cm. Only deep springs and mine waters reach higher values. Despite dilution effects due to different rainwater amounts, water-rock interaction can be retraced by the chemical water composition, especially by trace metals and rare earth element concentrations. Examples of water-rock interaction are discussed for granite, greywacke and limestone.
    • Weak convergence of the L1 scheme for a stochastic subdiffusion problem driven by fractionally integrated additive noise

      Hu, Ye; Li, Changpin; Yan, Yubin; University of Chester; Lvliang University; Shanghai University
      The weak convergence of a fully discrete scheme for approximating a stochastic subdiffusion problem driven by fractionally integrated additive noise is studied. The Caputo fractional derivative is approximated by the L1 scheme and the Riemann-Liouville fractional integral is approximated with the first order convolution quadrature formula. The noise is discretized by using the Euler method and the spatial derivative is approximated with the linear finite element method. Based on the nonsmooth data error estimates of the corresponding deterministic problem, the weak convergence orders of the fully discrete schemes for approximating the stochastic subdiffusion problem driven by fractionally integrated additive noise are proved by using the Kolmogorov equation approach. Numerical experiments are given to show that the numerical results are consistent with the theoretical results.
    • Wheelchair-MR: A Mixed Reality Wheelchair Training Environment

      Day, Thomas W.; University of Chester (IEEE, 2017-09-20)
      In previous work we have demonstrated that Virtual Reality can be used to help train driving skills for users of a powered wheelchair. However, cybersickness was a particular problem. This work-in-progress paper presents a Mixed Reality alternative to our wheelchair training software, which overcomes this problem. The design and implementation of this application is discussed. Early results shows some promise and overcomes the cybersickness issue. More work is needed before a larger scale study can be undertaken.
    • Will Future Resource Demand Cause Significant and Unpredictable Dislocations for the UK Ministry of Defence?

      Antill, Peter; Powell-Turner, Julieanna; Cranfield University (Elsevier, 2015-06-24)
      This paper focuses on the drivers which may affect future trends in material availability for defence, in particular, the availability of rare earth elements (REE). These drivers include resource concentration, tighter regulatory policy and its enforcement, export policies, their use in economic statecraft, increases in domestic demand, promoting greater efficiency in resource use, efforts to mitigate resource depletion and more efficient resource extraction while reducing its associated environmental impact. It looks at the effect these factors might have on global systems and supply chains, the impact on material insecurity and how this may exacerbate the issue of their use in UK military equipment. It finds that these drivers are likely to have an increasing impact on material availability (if measures are not taken to mitigate them), which will have consequences for the provision of military capability by the UK.
    • X-ray Photoelectron Spectroscopy Analysis of Biochar

      Smith, Graham C.; University of Chester (CSIRO Publishing, 2017-03-01)
      The chapter describes the application of the XPS technique to the analysis of biochar.
    • The X-ray photoelectron spectroscopy of surface films formed during the ASTM D-130/ISO 2160 copper corrosion test

      Reid, David G.; Smith, Graham C.; University of Chester (Taylor & Francis, 2014-01)
      The surfaces of ISO 2160 copper strips tested in iso-octane with elemental sulfur, aliphatic, cyclic and aromatic thiols, diphenyl sulfide, and diphenyl disulfide individually or in combination were studied using XPS. Aliphatic thiols bonded through the sulfur, whereas elemental sulfur formed a cuprous sulfide layer. Aromatics bonded partially through the sulfur with the rings oriented horizontally due to π orbital interactions, accounting in part for their inhibitory effects in the test. The test rating was not directly related to the sulfur concentration in solution or on the surface, and certain combinations of species resulted in higher levels of sulfur at the surface than found individually.
    • XPS Analysis of the chemical degradation of PTB7 polymers for organic photovoltaics

      Kettle, Jeff; Ding, Ziqian; Smith, Graham C.; Horie, Masaki; Bangor University, National Tsing Hua University, Taiwan, University of Chester (Elsevier, 2016-10-14)
      The chemical degradation of the Poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl]] or ‘ PTB7’ has been studied using X-ray Photoelectron Spectroscopy (XPS). This material system appears to be intrinsically unstable especially when illuminated in air and XPS studies confirm the rapid photo-degradation is related to changes in chemical structure of the polymer. In particular, XPS spectra show an initial reduction in relative C-C intensity, suggests loss of the alkoxy side chains. This is followed by a dramatic increase in the level of oxygen-bonded species, especially C-O at ~286.5 eV and C(=O)O at 289.2 eV, indicative of COOH and OH group formation, and oxidation of S. The XPS results support the view that using processing additives reduces the chemical stability of the polymer and provides insight into strategies to improve molecular design to ensure higher chemical stability.