• Virtual Reality Environment for the Cognitive Rehabilitation of Stroke Patients

      John, Nigel W.; Day, Thomas W.; Pop, Serban R.; Chatterjee, Kausik; Cottrell, Katy; Buchanan, Alastair; Roberts, Jonathan; University of Chester; Countess of Chester Hospital NHS Foundation Trust; Cadscan Ltd (IEEE, 2019-10-14)
      We present ongoing work to develop a virtual reality environment for the cognitive rehabilitation of patients as a part of their recovery from a stroke. A stroke causes damage to the brain and problem solving, memory and task sequencing are commonly affected. The brain can recover to some extent, however, and stroke patients have to relearn to carry out activities of daily learning. We have created an application called VIRTUE to enable such activities to be practiced using immersive virtual reality. Gamification techniques enhance the motivation of patients such as by making the level of difficulty of a task increase over time. The design and implementation of VIRTUE is presented together with the results of a small acceptability study.
    • Virtual reality training in cardiopulmonary resuscitation in schools

      Rees, Nigel; John, Nigel W.; Beever, Lee; Vaughan, Neil; Powell, C; Fletcher, A; Welsh Ambulance Services NHS Trust; Swansea University; University of Chester; University of Exeter; British Heart Foundation; London School of Hygiene & Tropical Medicine (Mark Allen Healthcare, 2021-09-11)
      UK average survival from Out of Hospital Cardiac Arrest (OHCA) survival is around 8.6%, which is significantly lower than other high performing countries with survival rates of over 20%. A cardiac arrest victim is 2–4 times more likely to survive OHCA with bystander CPR provision. Mandatory Teaching CPR to children in school is acknowledged to be the most effective way to reach the entire population and improving the bystander CPR rate and is endorsed by the World Health Organization (WHO) “Kids Save Lives” statement. Despite this, Wales is yet to follow other home nations by including CPR training as a mandatory within the school’s curriculum. In this paper, we explore the role of teaching CPR to schoolchildren and report on the development by Computer scientists at the University of Chester and the Welsh Ambulance Services NHS Trust (WAST) of VCPR, a virtual environment to help teach the procedure. VCPR was developed in three stages: identifying requirements and specifications; development of a prototype; and management—development of software, further funding and exploring opportunities for commercialisation. We describe the opportunities in Wales to skill up the whole population over time in CPR and present our Virtual reality (VR) technology is emerging as a powerful for teaching CPR in schools.
    • Visual-Inertial 2D Feature Tracking based on an Affine Photometric Model

      Aufderheide, Dominik; Edwards, Gerard; Krybus, Werner; South Westphalia University of Applied Sciences, University of Chester, South Westphalia University of Applied Sciences (Springer, 2015-04-08)
      The robust tracking of point features throughout an image sequence is one fundamental stage in many different computer vision algorithms (e.g. visual modelling, object tracking, etc.). In most cases, this tracking is realised by means of a feature detection step and then a subsequent re-identification of the same feature point, based on some variant of a template matching algorithm. Without any auxiliary knowledge about the movement of the camera, actual tracking techniques are only robust for relatively moderate frame-to-frame feature displacements. This paper presents a framework for a visual-inertial feature tracking scheme, where images and measurements of an inertial measurement unit (IMU) are fused in order to allow a wider range of camera movements. The inertial measurements are used to estimate the visual appearance of a feature’s local neighbourhood based on a affine photometric warping model.
    • Visualization beyond the Desktop--the Next Big Thing

      Roberts, Jonathan C.; Ritsos, Panagiotis D.; Badam, Sriram Karthik; Brodbeck, Dominique; Kennedy, Jessie; Elmqvist, Niklas; University of Chester (IEEE, 2014-08-15)
      Visualization researchers need to develop and adapt to today’s new devices and tomorrow’s technology. Today, people interact with visual depictions through a mouse. Tomorrow, they’ll be touching, swiping, grasping, feeling, hearing, smelling, and even tasting data.
    • Volatile Liquid Detection by Terahertz Technologies

      Baxter, Harry W.; Worrall, Adam A.; Pang, Jie; Chen, Riqing; Yang, Bin; University of Chester; Fujian Agriculture and Forestry University (Frontiers Media, 2021-04-08)
      The prospect of being able to move through security without the inconvenience of separating liquids from bags is an exciting one for passengers, and there are important operational benefits for airports as well. Here, two terahertz (THz) systems, 100 GHz sub-THz line scanner and attenuation total reflection-based THz time domain spectroscopy (TDS), have been used to demonstrate the capability of identifying different liquid samples. Liquid samples’ THz complex permittivities are measured and their differences have contributed to the variation of 100 GHz 2D images of volatile liquids with different volumes inside of cannister bottles. The acquired attenuation images at 100 GHz can easily be used to distinguish highly absorbed liquids (Water, Ethanol, Fuel Treatment Chemicals) and low loss liquids (Petrol, Diesel, Kerosene and Universal Bottle Cleaner). The results give a promising feasibility for mm-wave imager and THz spectroscopy to efficiently identify different volatile liquids.
    • Volatile organic compounds (VOCs) in photochemically aged air from the Eastern and Western Mediterranean

      Derstroff, Bettina; Hueser, Imke; Sander, Rolf; Bourtsoukidis, Efstratios; Crowley, John N.; Fischer, Horst; Gromov, Sergey; Harder, Hartwig; Kesselmeier, Juergen; Lelieveld, Jos; et al. (Copernicus Publications, 2017-08-09)
      During the summertime CYPHEX campaign (CYprus PHotochemical EXperiment 2014) in the Eastern Mediterranean, multiple volatile organic compounds (VOCs) were measured from a 650 m hilltop site in western Cyprus (34°57' N/32°23' E). Periodic shifts in the northerly Etesian winds resulted in the site being alternately impacted by photochemically processed emissions from Western (Spain, France, Italy) and Eastern (Turkey, Greece) Europe. In this study we examine the temporal variation of VOCs at the site. The sparse Mediterranean scrub vegetation generated diel cycles in the reactive biogenic hydrocarbon isoprene, from below detection limit at night to 100 pptv by day on average. In contrast, the oxygenated volatile organic compounds (OVOCs) methanol and acetone exhibited no diel cycle and were approximately an order of magnitude higher in mixing ratio (range: 1–8 ppbv) than the locally emitted isoprene (up to 320 pptv), total monoterpenes (up to 250 pptv) and aromatic compounds such as benzene and toluene (up to 100 pptv, spikes up to 400 pptv). Acetic acid was present at mixing ratios between 0.05 and 4 ppbv and followed a pronounced diel cycle in one specific period, which was related to local production and loss and local meteorological effects. During the rest of the campaign the impact of the free troposphere and long distance transport from source regions dominated over local processes and diel cycles were not observed. The Lagrangian model FLEXPART was used to determine transport patterns and photochemical processing times of air masses originating from Eastern and Western Europe. Eastern and Western European air masses showed distinct trace gas concentrations, with ca. 20 % higher ozone and ca. 30–50 % higher values for most of the OVOCs observed from the East. Using the FLEXPART calculated transport time, the contribution of photochemical processing, sea surface contact and dilution was estimated. Methanol, acetone and acetic acid all decreased with residence time in the marine boundary layer (MBL) with loss rates of 0.1 ± 0.01 ppbv/h, 0.06 ± 0.01 ppbv/h, 0.05 ± 0.01 ppbv/h from Eastern Europe and 0.06 ± 0.01 ppbv/h, 0.02 ± 0.004 ppbv/h and 0.03 ± 0.004 ppbv/h from Western Europe, respectively. The most soluble species, acetic acid, showed the lowest loss rates, indicating that solubility limited deposition to the ocean was not the only factor and that turbulent transport, plume dilution, microbial consumption within the surface of the ocean and especially entrainment from the free troposphere may also be important. Correlations between acetone, methanol and acetic acid were rather weak in western air masses (r2 = 0.52–0.62), but were stronger in air masses measured after the shorter transport time from the East (r2 = 0.53–0.81).
    • Volatile organic compounds (VOCs) in photochemically aged air from the Eastern and Western Mediterranean

      Derstroff, Bettina; Stoenner, Christof; Kluepfel, Thomas; Sauvage, Carina; Crowley, John N.; Phillips, Gavin J.; Parchatka, Uwe; Lelieveld, Jos; Williams, Jonathan; Max Planck Institute for Chemistry; University of Chester (Copernicus Publications, 2015-02-25)
      In summer 2014 a comprehensively instrumented measurement campaign (CYPHEX) was conducted in northwest Cyprus in order to investigate atmospheric oxidation chemistry in the Mediterranean region. The site was periodically influenced by the northerly Etesian winds advecting air from Eastern Europe (Turkey and Greece) and from westerly winds bringing more photochemically processed emissions from Western Europe (Spain and France). In this study the data from a Proton Transfer Reaction Time of Flight Mass Spectrometer (PTR-TOF-MS) are analyzed. Generally, oxidized volatile organic compounds (OVOCs) such as methanol and acetone were measured in high mixing ratios (max. 9.5 ppb, min. 1.3 ppb, average 3.2 ppb for methanol, max. 7.9 ppb, min. 1.3 ppb, average 2.4 ppb for acetone ) while precursors like propane showed low values (max. 500 ppt). This demonstrates that the air measured was oxidized to a high degree over the Mediterranean Sea. Low values of acetonitrile throughout the campaign indicated no significant influence of biomass burning on the data. Temporal variations in VOC mixing ratios and precursor/product ratios over the campaign can be explained by using the HYSPLIT backward trajectory model which delineated air masses originating from Eastern and Western Europe. Diel variations of reactive VOCs such as isoprene and terpenes were also observed at the site. A sharp increase in isoprene and monoterpenes at circa 9:00 local time indicated that the 600 m hilltop site was influenced by ascending boundary layer air at this time. In this study, particular emphasis is placed on acetic (ethanoic) acid measured by PTR- TOF-MS and calibrated by a permeation source. Acetic acid is an atmospheric oxidation product of multiple volatile organic compounds, emitted directly from vegetation, and found in abundance in the Mediterranean region (max. 2.7 ppb, min. 0.2 ppb, average 0.8 ppb). Acetic acid contributes to the acidity of precipitation in remote areas, can be incorporated into aerosols by adsorption on the surface and thereby alter the activity due to their high polarity. Correlations of acetic acid with peracetic acid, humidity and ozone have been investigated in order to better understand the sources influencing acetic acid at the site and to assess its potential as a marker for Criegee radical chemistry.
    • Volatile organic compounds (VOCs) in photochemically aged air from the eastern and western Mediterranean

      Derstroff, Bettina; Hueser, Imke; Bourtsoukidis, Efstratios; Crowley, John N.; Fischer, Horst; Gromov, Sergey; Harder, Hartwig; Janssen, Ruud; Kesselmeier, Juergen; Lelieveld, Jos; et al. (Copernicus Publications, 2017-08-09)
      During the summertime CYPHEX campaign (CYprus PHotochemical EXperiment 2014) in the eastern Mediterranean, multiple volatile organic compounds (VOCs) were measured from a 650 m hilltop site in western Cyprus (34° 57′ N/32° 23′ E). Periodic shifts in the northerly Etesian winds resulted in the site being alternately impacted by photochemically processed emissions from western (Spain, France, Italy) and eastern (Turkey, Greece) Europe. Furthermore, the site was situated within the residual layer/free troposphere during some nights which were characterized by high ozone and low relative humidity levels. In this study we examine the temporal variation of VOCs at the site. The sparse Mediterranean scrub vegetation generated diel cycles in the reactive biogenic hydrocarbon isoprene, from very low values at night to a diurnal median level of 80–100 pptv. In contrast, the oxygenated volatile organic compounds (OVOCs) methanol and acetone exhibited weak diel cycles and were approximately an order of magnitude higher in mixing ratio (ca. 2.5–3 ppbv median level by day, range: ca. 1–8 ppbv) than the locally emitted isoprene and aromatic compounds such as benzene and toluene. Acetic acid was present at mixing ratios between 0.05 and 4 ppbv with a median level of ca. 1.2 ppbv during the daytime. When data points directly affected by the residual layer/free troposphere were excluded, the acid followed a pronounced diel cycle, which was influenced by various local effects including photochemical production and loss, direct emission, dry deposition and scavenging from advecting air in fog banks. The Lagrangian model FLEXPART was used to determine transport patterns and photochemical processing times (between 12 h and several days) of air masses originating from eastern and western Europe. Ozone and many OVOC levels were  ∼  20 and  ∼  30–60 % higher, respectively, in air arriving from the east. Using the FLEXPART calculated transport time, the contribution of photochemical processing, sea surface contact and dilution was estimated. Methanol and acetone decreased with residence time in the marine boundary layer (MBL) with loss rate constants of 0.74 and 0.53 day−1 from eastern Europe and 0.70 and 0.34 day−1 from western Europe, respectively. Simulations using the EMAC model underestimate these loss rates. The missing sink in the calculation is most probably an oceanic uptake enhanced by microbial consumption of methanol and acetone, although the temporal and spatial variability in the source strength on the continents might play a role as well. Correlations between acetone and methanol were weaker in western air masses (r2  =  0.68), but were stronger in air masses measured after the shorter transport time from the east (r2  =  0.73).
    • Volterra integral equations and fractional calculus: Do neighbouring solutions intersect?

      Diethelm, Kai; Ford, Neville J.; Technische Universität Braunschweig ; University of Chester (Rocky Mountain Mathematics Consortium, 2012-04-04)
      This journal article considers the question of whether or not the solutions to two Volterra integral equations which have the same kernel but different forcing terms may intersect at some future time.
    • VRIA - A Framework for Immersive Analytics on the Web

      Butcher, Peter; John, Nigel W.; Ritsos, Panagiotis D.; University of Chester and Bangor University (ACM, 2019-05)
      We report on the design, implementation and evaluation of <VRIA>, a framework for building immersive analytics (IA) solutions inWeb-based Virtual Reality (VR), built upon WebVR, A-Frame, React and D3. The recent emergence of affordable VR interfaces have reignited the interest of researchers and developers in exploring new, immersive ways to visualize data. In particular, the use of open-standards web-based technologies for implementing VR in a browser facilitates the ubiquitous and platform-independent adoption of IA systems. Moreover, such technologies work in synergy with established visualization libraries, through the HTML document object model (DOM). We discuss high-level features of <VRIA> and present a preliminary user experience evaluation of one of our use-cases.
    • VRIA: A Web-based Framework for Creating Immersive Analytics Experiences

      Butcher, Peter; John, Nigel W; Ritsos, Panagiotis D.; University of Chester and Bangor University (IEEE, 2020-01-09)
      We present<VRIA>, a Web-based framework for creating Immersive Analytics (IA) experiences in Virtual Reality.<VRIA>is built upon WebVR, A-Frame, React and D3.js, and offers a visualization creation workflow which enables users, of different levels of expertise, to rapidly develop Immersive Analytics experiences for the Web. The use of these open-standards Web-based technologies allows us to implement VR experiences in a browser and offers strong synergies with popular visualization libraries, through the HTMLDocument Object Model (DOM). This makes<VRIA>ubiquitous and platform-independent. Moreover, by using WebVR’s progressive enhancement, the experiences<VRIA>creates are accessible on a plethora of devices. We elaborate on our motivation for focusing on open-standards Web technologies, present the<VRIA>creation workflow and detail the underlying mechanics of our framework. We also report on techniques and optimizations necessary for implementing Immersive Analytics experiences on the Web, discuss scalability implications of our framework, and present a series of use case applications to demonstrate the various features of <VRIA>. Finally, we discuss current limitations of our framework, the lessons learned from its development, and outline further extensions.
    • 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.
    • 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
      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.