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Data supporting: High-order hybrid DG-FV framework for compressible multi-fluid problems on unstructured meshes
No full textThis dataset contains binary output in Tecplot format for the test problems analysed in the "High-order hybrid DG-FV framework for compressible multi-fluid problems on unstructured meshes" JCP paper. Test cases included are: - Gas-water isolated material interface advection - 2D and 3D helium bubble interaction with shock wave - 2D shock driven air bubble collapse in water - 2D and 3D shock driven air bubble array collapse in water - 2D underwater explosionMulti-Physics Modellin
Shaping the structure and properties of HyTemp using polyethylene glycol diglycidyl ether cross-linkers
Get PDFNovel elastomers are made by reaction of hydroxyl-terminated polyacrylic ester (HyTemp) with polyethylene glycol (PEG, number of ethylene glycol units 1, 3, 6, 9) based cross-linkers. The influence of the cross-linker length, the HyTemp/cross-linker (w/w) ratio and the cross-linking accelerator trifluoromethanesulfonate scandium salt (ScTFMS) on the structure and the properties of the materials are studied. The cross-linker length has not influence on the glass transition (Tg) of the products because of the presence of the flexible PEG units that cancels out the cross-linking effect associated to a shift to higher Tg. A two-domain structure is seen by the presence of a dual Tg in samples cured with ScTFMS. Mathematical analysis of the modulated differential scanning calorimetry curves offers for the first time the possibility to identify/confirm structural differences in complex three-dimensional polymeric structures. Scanning electron microscopy and swelling experiments in ethyl acetate respectively reveal an increase in the pore size (1.13 to 5.48 nm) and in the absorption ability of the elastomers cured with different types and quantities of PEG cross-linker. The new elastomeric materials are exhibiting a rubbery state over a wide temperature range and absorptivity for the potential recovery of pollutants in soil and/or water.This research was funded by Cranfield University via a MSc projectJournal of Polymer Scienc
Practice effects of a breathing technique on pilots’ cognitive and stress associated heart rate variability during flight operations
Get PDFCommercial pilots endure multiple stressors in their daily and occupational lives which are detrimental to psychological well-being and cognitive functioning. The Quick coherence technique (QCT) is an effective intervention tool to improve stress resilience and psychophysiological balance based on a five-minute paced breathing exercise with heart rate variability (HRV) biofeedback. The current research reports on the application of QCT training within an international airline to improve commercial pilots’ psychological health and support cognitive functions. Forty-four commercial pilots volunteered in a one-month training programme to practise self-regulated QCT in day-to-day life and flight operations. Pilots’ stress index, HRV time-domain and frequency-domain parameters were collected to examine the influence of QCT practice on the stress resilience process. The results demonstrated that the QCT improved psychophysiological indicators associated with stress resilience and cognitive functions, in both day-to-day life and flight operation settings. HRV fluctuations, as measured through changes in RMSSD and LF/HF, revealed that the resilience processes were primarily controlled by the sympathetic nervous system activities that are important in promoting pilots’ energy mobilization and cognitive functions, thus QCT has huge potential in facilitating flight performance and aviation safety. These findings provide scientific evidence for implementing QCT as an effective mental support programme and controlled rest strategy to improve pilots’ psychological health, stress management, and operational performance.The corresponding author of this research was supported by the Higher Education Innovation Fund (HEIF 2021-2022).Stres
Response to various water regimes of the physiological aspects, nutritional water productivity, and phytochemical composition of bush tea (Athrixia phylicoides DC.) grown under a protected environment
Get PDFThe influence of water regimes on plants is crucial for integrating bush tea (Athrixia phylicoides DC.) into strategies in Sub-Saharan Africa to tackle food and nutritional insecurity by considering physiological aspects, nutritional yield, nutritional water productivity, and metabolite composition. The objective of the study was to determine the physiological aspects, including leaf gas exchange and chlorophyll fluorescence, nutritional yield, nutritional water productivity, and metabolite composition of bush tea under varying water regimes. The tunnel experiment was laid out in a randomized complete block design (RCBD) with treatments consisting of three water regimes: 100% of crop water requirement (ETa), 30% of ETa, and a control (no irrigation), all replicated three times. The morphological aspects were recorded on a weekly basis. However, yield, nutrient content, nutritional water productivity (NWP), and phytochemical composition were determined at harvest. The phytochemical analysis by liquid chromatography mass spectrometry (LC-MS), coupled with visualization of the detected chemical spaces through molecular networking, indicated Athrixia phylicoides DC. to be rich in various bioactive compound derivatives, including methyl chlorogenate, flavonoids, tartaric acid, caffeoylquinic acid, and glutinane. The results showed that 30% ETa enhanced plant growth, nutrient content, and nutritional water productivity compared to other water treatments. Nevertheless, 100% ETa yielded more (95.62 kg ha−1) than 30% ETa (60.61 kg ha−1) and control (12.12 kg ha−1). The accumulation of chlorogenic acids was higher under 30% ETa compared to 100% ETa and control. Therefore, this study is the first to determine the accumulation of various bioactive compounds in bush tea leaf extracts under varying water regimes. This confirms that in areas with low water availability, bush tea is well adapted for production without limiting nutrients.Horticultura
Estimating tactical surface metering management’s effect on aircraft fuel savings at airport
Get PDFWe estimated the effect of surface metering technology deployed at Charlotte Douglas International Airport (CLT) by the National Aeronautics and Space Administration (NASA) and the Federal Aviation Administration (FAA) on fuel and CO2 savings. We employed a difference-in-differences strategy, covariate-balancing methods, and a fixed-effects model. Furthermore, we used a doubly robust strategy that combines matching with parametric regression using datasets constructed by data-driven approaches, which minimizes discretion in selecting comparison units. Our estimates from the daily panel of US carriers from November 2015 to November 2019 suggested that about 39.156 kg (95% confidence interval (CI) 64.017–13.436) of fuel and 120.599 kg (CI 197.174 kg–41.382 kg) of CO2 could be saved per flight even when the single-engine taxiing rate was as high as 75% during the entire deployment phase. At the same time, our results suggested a concerning pattern: taxi-out time savings generated by the technology diminished over time.Research in Transportation Economic
Dynamic strategic marketing planning: the paradox of concurrently reconfiguring and implementing strategic marketing planning
Get PDFTraditional marketing planning may not be as effective in today’s challenging environments for achieving the dual imperative of meeting objectives and continuously improving market fit. Therefore, we introduce the concept of dynamic strategic marketing planning (DSMP) as a higher-order capability that requires the concurrent orchestration of marketing planning, senior management-led strategic implementation, and change as operationalized through the reconfiguration of processes and resources. With responses from 313 CEOs, we demonstrate that DSMP does overcome the innovativeness rigidities found in ordinary marketing planning capabilities. While DSMP is associated with higher levels of innovativeness, it also achieves higher levels of financial performance over ordinary marketing planning capabilities. Our findings seek to transform marketing planning practice by requiring that its implementation receives the attention of senior managers and combines reconfiguration processes that promote the renewal of plans and capabilities
A hybrid computer vision and machine learning approach for robust vortex core detection in fluid mechanics applications
Get PDFVortex core detection remains an unsolved problem in the field of experimental and computational fluid dynamics. Available methods such as the Q, delta and swirling-strength criterion are based on a decomposed velocity gradient tensor but detect spurious vortices (false positives and false negatives), making these methods less robust. To overcome this, we propose a new hybrid machine learning approach in which we used a convolutional neural network to detect vortex regions within surface streamline plots and an additional deep neural network to detect vortex cores within identified vortex regions. Furthermore, we propose an automatic labelling approach based on K-means clustering to pre-process our input images. We show results for two classical test cases in fluid mechanics; the Taylor-Green vortex problem and two rotating blades. We show that our hybrid approach is up to 2.6 times faster than a pure deep neural network-based approach and furthermore show that our automatic K-means clustering labelling approach is within 0.45% mean square error of the more labour-intensive, manual labelling approach. At the same time, using a sufficient number of samples, we show that we are able to reduce false positives and negatives entirely and thus show that our hybrid machine learning approach is a viable alternative to currently used vortex detection tools in fluid mechanics applications.Journal of Computing and Information Science in Engineerin
Investor emotions and market bubbles
No full textAsset pricing bubbles are highly emotional market episodes. Despite this, investor emotions are not part of traditional bubble models. We measure the powerful affects influencing investor decisions during speculative market bubbles directly employing textual analysis of media narratives and domain-specific emotion keyword dictionaries and show how understanding investor emotional dynamics helps explain market behavior. Specifically, we focus on the two Chinese stock market bubbles of 2005–2008 and 2014–2016; there is no evidence of investor learning from experience. Despite Chinese media being censored we show it still has strong explanatory power although the independent English language media can provide an additional perspective. Deeper emotions dominate more superficial feelings in information content.Review of Quantitative Finance and Accountin
Combinatorial sputtering and degradation behaviour of photoluminescence Europium Titanium Oxide thin films
No full textRao, Jeff - Associate SupervisorThe most common type of solar cell is the crystalline silicon (c-Si) cell, which has a
low cost of production and a high efficiency of energy conversion and is widely used
in various applications that require solar power. Inefficiencies associated with PV
devices mainly stem from energy conversation mismatches between solar radiation
and the PV spectral response. Photoluminescent (PL) thin films possess the capability
to absorb and re-emit specific photons, thereby minimising energy losses within the
PV system. In this thesis, PL thin films have been fabricated using the physical vapour
deposition (PVD) method, synthesised Europium oxide and Titanium oxide coating. A
range of Europium Titanium Oxide (ETO) luminescence thin films, with concentrations
varying from 0 at% to 100 at% in Eu/(Eu+Ti), were fabricated using combinatorial
sputtering. The samples underwent heat treatment annealing at 450˚C and 600˚C,
resulting in changes to the phase, structure, and optical properties. The effect of
composition and annealing temperature on the characterisations of the ETO thin film
samples were comprehensively studied using SEM, EDX, XRD, UV–Vis
spectrophotometer, Raman spectrometer, fluorescence spectrometer, and solar
simulator. Transmittance and bandgap variations are observed and influenced by
annealing temperature and europium ratios. The bandgap energy variation is identified
as a crucial factor affecting photon absorption and the luminescent properties of the
films. Fluorescence spectroscopy was used to examine the photoluminescence
properties of the thin films. Excitation peaks at 394 nm ( 7F0'→5L6') and 464 nm (7F0→
5D2) are identified as the most intense in excitation spectra, while in emission spectra
the strongest emission intensity peak at 613 nm (5D0→7F2) exhibits a higher branching
ratio in fluorescence spectra. Furthermore, an investigation into the optical and
fluorescence properties of luminescence thin films comprising Eu(dbm)3 and
CuInS2/ZnS in conjunction with PMMA and PVA matrices has been conducted. The
characteristics of these films were analysed both before and after degradation testing,
with a comparative assessment made against ETO thin films. In addition, an intriguing
correlation between bandgap values and power conversion efficiency is established.
Films with narrower bandgaps demonstrate reduced power conversion efficiency due
to increased photon absorption, scattering and escape from the substrate edge. These
findings contribute valuable insights into tailoring the properties of luminescence thin
films for potential applications, particularly in the realm of optoelectronic devices.PhD in Manufacturin
Insights from electrical resistivity tomography on the hydrogeological interaction between sand dams and the weathered basement aquifer
Get PDFData supporting this study are openly available in the Cranfield University repository (CORD) at https://dspace.lib.cranfield.ac.uk/handle/1826/20712.Sand dams, composed of recent alluvial aquifers behind concrete dam walls, are a water management technique in drylands. However, their level of hydraulic connectivity with their surrounding weathered basement aquifer is debated. This study aims to constrain this hydrogeological uncertainty in order to better understand their ability to meet water needs and improve dryland water security. The study is the first to use 2D geophysics (Electrical Resistivity Tomography) to provide evidence of seepage from sand dams at three mature and three newly built sites. A generally greater hydraulic connectivity was found between sand dams and their surrounding aquifer than has been assumed in some previous studies, with sites providing at least some local recharge rather than existing as isolated storage structures. This improved understanding is beneficial for both site selection and the performance of sand dams and can help ensure that maximum benefits are derived from the construction of a sand dam depending on its intended purpose.Engineering and Physical Sciences Research CouncilThis work was funded by Engineering and Physical Sciences Research Council (Grant No: EP/S022066/1).Journal of Applied Geophysic