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Effect of low pressure plasma surface modification on filtration performance of chitosan nanofibrous respiratory filter
No full textLow pressure drop is highly desirable for respiratory filters. Surface activation plays an important role to enhance the filtration performance of respiratory filters. In this study, a three-layer composite respiratory filter was developed using a combination of polypropylene (PP) nonwoven layers and chitosan nanofibres (CSNF) with variable coating time (h) during the electrospinning process. To study the impact of surface activation on filtration performance, the outer surface of all the samples were modified using low-pressure plasma treatment. Filtration performance testing was conducted to determine the filtration efficiency (%), pressure drop (Pa), and quality factor (Q) results, before and after the surface treatment. The maximum values of filtration efficiency and quality factor achieved were 99.99% and 0.068, respectively. The lowest value of the pressure drop was 16.12 Pa. All the low-pressure plasma-treated samples showed higher filtration efficiency and quality factor compared to untreated samples due to a more effective capturing mechanism. However, pressure drop results indicated no significant difference. Furthermore, the decay of plasma treatment impact was analysed by using drop shape analysis method to measure the water contact angle on the surface of the samples. Results showed a gradual decrease in surface modification impact and the surface of the treated samples changed from hydrophilic to hydrophobic with the passage of time.</p
CAST: Learning both Geometric and Texture Style Transfers for Effective Caricature Generation
No full textGiven a photo of a subject, ability to generate a caricature image that captures distinct characteristics of the subject but with certain exaggeration of their prominent features is of fundamental importance to image processing and facial recognition. There are two main challenges in this task: shape exaggeration and style transfer. The former morphs and exaggerates key facial features of the subject, while the latter generates caricature images in a certain artistic style. In this paper, we propose a CAricature Style Transfer (CAST) framework for caricature generation. There are two modules in the proposed framework. The first is a geometric warping module. Different from the existing style transfer methods, we incorporate the Whitening and Coloring Transformation (WCT) in the geometric style transfer. The WCT is learned on photo and caricature landmarks or the caricature landmark space of a specific artist and is capable of transforming input photo landmarks to caricature landmarks. The second module is a texture style rendering module. We propose a new style transfer method by considering a semantic region-aligned style transfer via affinity constraint. Given a reference caricature image as the style reference, this module is capable of transferring styles between the same or similar semantic regions in caricatures and photos. Furthermore, it can transfer visual attributes of the reference caricatures (such as mouth shape and expressions) to the output caricatures. Experiments have shown desirable effects of the proposed method in transferring both the geometric and artistic texture styles of caricatures. Both qualitative and quantitative results show that the CAST framework is more effective compared than the state-of-the-art caricature generation methods
Impact of occupational pesticide exposure assessment method on rist estimates for prostate cancer, non-Hodgkin's lymphoma and Parkinson's disease - results of three meta-analyses
No full textObjective: Assessment of occupational pesticide exposure in epidemiological studies of chronic diseases is challenging. Biomonitoring of current pesticide levels might not correlate with past exposure relevant to disease etiology, and indirect methods often rely on workers’ imperfect recall of exposures, or job titles. We investigated how applied exposure assessment method (EAM) influenced risk estimates for some chronic diseases. Methods: In three meta-analyses the influence of EAM type on the summary risk ratio (sRR) of prostate cancer (25 articles), Non-Hodgkin’s lymphoma (NHL) (30 articles), and Parkinson’s disease (PD) (32 articles) was investigated. EAM types analysed were: group-level assessments (e.g. job titles), self-reported exposures, expert-level assessments (e.g. job-exposure matrices), and biomonitoring (e.g. blood, urine). Additionally, sRRs were estimated by study design, publication year period, and geographic location where the study was conducted.Results: EAM types were not associated with statistically significant different sRRs across any of the health outcomes. Heterogeneity in results varied from high in cancer studies to moderate and low in PD studies. Overall, case-control designs showed significantly higher sRR estimates than prospective cohort designs. Later NHL publications showed significantly higher sRR estimates than earlier. For prostate cancer, studies from North America showed significantly higher sRR estimates than studies from Europe. Conclusion: Exposure assessment method applied in studies of occupational pesticides appears not to have a significant effect on risk estimates for prostate cancer, NHL, and PD. In systematic reviews of chronic health effects of occupational exposure to pesticides, epidemiological study design, publication year, and geographic location, should primarily be considered. <br/
Finite element modelling of hot compression testing of titanium alloys
No full textThis paper presents experimental results and finite element analysis of hot upsetting of titanium alloys Ti64 and Ti407 using a dilatometer in loading mode. All samples showed barrelling, as a consequence of an inhomogeneous temperature distribution and friction. The FE analysis is a full thermomechanical model of the test calibrated using multiple thermocouples. At each nominal temperature and strain-rate, the true flow stress-strain response is inferred using the difference between the initially assumed constitutive response input to the FE analysis, 𝜎𝜎=𝑓𝑓(𝑇𝑇,𝜀𝜀˙,𝜀𝜀), and the predicted response of the model. The analysis applies new procedures for: (i) modelling the thermal gradient; (ii) finding the flow stress correction due to the inhomogeneity, using literature data as the input to the FE analysis; (iii) smoothing the constitutive data, fitting empirical 𝜎𝜎=𝑓𝑓(𝑇𝑇,𝜀𝜀˙) surfaces at multiple discrete strains. The extracted true constitutive data confirms the moderate strain-softening behaviour in Ti64 alloy, and the FE model predicts the distribution of local deformation conditions, for application in interpretation of microstructure and texture evolution. This highlights the difference between nominal and actual test conditions, showing that the discrepancy varies systematically with test conditions, with the central strain and strain-rate being magnified significantly, by factors of order 2–3
Structure restoration and coarsening of nanocrystalline cementite in cold drawn pearlitic wire induced by low temperature annealing
No full textInternal structure evolution of nano-scale cementite during annealing has exhibited a critical impact on mechanical performance for various heavily strained high-carbon steel materials. Through a combination of post-annealing and in-situ annealing transmission electron microscopy observations, structural evolution of heavily strained cementite during low-temperature annealing was investigated. During annealing, the morphology of cementite lamellae is stable when the temperature (Ta) is lower than 350 °C. Meanwhile, lattice structure restoration and coarsening of nanocrystalline cementite (θ- NC) occurred inside the lamellae. Starting from a nanocrystalline structure in the as-drawn state, the interiors of cementite lamellae were observed to transform into coarsened isometric shape θ-NC (140 °C < Ta < 210 °C) or elongated θ-NC (Ta < 350 °C). The coarsening activation energy of heavily strained cementite nanocrystalline in lamellae is estimated to be in a range of 37 ~ 50 kJ mol-1, while the coarsening behaviour is limited by the ferrite-cementite phase boundary
Flash Sintering, A Novel Technique for Nuclear Waste Management
No full textMixed uranium plutonium oxide (MOx) pellets are a potential candidate wasteform for plutonium disposition in a GDF. However, to manufacture MOx pellets suitable for disposal, homogenised powder feeds must be densified by a sintering process. This is an energy intensive and time-consuming process. Flash Sintering (FS) is an innovative technique in which an electric field is applied to the sample during the sintering process. It offers a more efficient and robust way to densify ceramic-containing nuclear material for disposal. The FS process requires significantly lower firing temperatures. It may therefore offer safety improvements when immobilising unique or problematic waste streams, due to the retention of volatile but long-lived minor actinides such as americium oxide. These would normally vaporise out of the MOx pellet during the high temperatures and long hold times in conventional sintering.We report the successful application of controlled current rate AC-FS flash sintering on both UO2 and CeO2 surrogate nuclear material for both fuel and waste applications, together with the microstructural evolution of pellets produced using both conventional (CeO2) and FS (CeO2 and UO2). These results demonstrate the possibility of forming different microstructures as a function of current density, in a fraction of conventional processing time. Future opportunities exist for expanding this work to the demonstration of FS on mixed CeO2 and UO2, as well as zirconia and neutron poison-doped materials for waste management applications.<br/
Measuring Risk of Re-identification in Microdata: State-of-the Art and New Directions
No full textWe review the influential research carried out by Chris Skinner in the area of statistical disclosure control, and in particular quantifying the risk of re-identification in sample microdata from a random survey drawn from a finite population. We use the sample microdata to infer population parameters when the population is unknown, and estimate the risk of re-identification based on the notion of population uniqueness using probabilistic modelling. We also introduce a new approach to measure the risk of re-identification for a subpopulation in a register that is not representative of the general population, for example a register of cancer patients. In addition, we can use the additional information from the register to measure the risk of re-identification for the sample microdata. This new approach was developed by the two authors and is published here for the first time. We demonstrate this approach in an application study based on UK census data where we can compare the estimated risk measures to the known truth. <br/
Understanding the Effects of Zn Injection and OLNC-Treatment on 316 Stainless Steel Oxide under Simulated BWR Conditions
No full textThis study investigates the mechanism of incorporation of metal cations (Zn and Co) into the 316 stainless steel (SS) oxide under hydrogenated water chemistry (HWC) and On-Line NobleChemTM (OLNC). Coupons of 316 SS were exposed to simulated boiling water reactor (BWR) conditions (pure water, H:O molar ratio ~8) at 288 °C and then analysed via surface characterisation techniques. Specifically, coupons were initially exposed under HWC conditions for 500 h, then subjected for 200 h to the OLNCtreatment, and then a final exposure under HWC conditions for 500 h, all with simultaneous monitoring of the electrochemical corrosion potential. These exposures were performed both with and without Zn and or Co injection. It was found that Zn decreased the oxide thickness of the inner oxide layer and decreased the size of the crystallites on the outer layer. Addition of 0.2 ppb of Co in the water chemistry containing 10 ppb Zn did not appear to influence the oxide morphology nor its composition. Hard X-ray XPS analysis showed that Zn did not completely suppress Co incorporation in the outer oxide layer which was still found in concentrations up to 0.6 at. % on the surface of the oxide under Zn addition conditions
High-order simulations of isothermal flows using the local anisotropic basis function method (LABFM)
No full textMesh-free methods have significant potential for simulations of flows in complex geometries, with the difficulties of domain discretisation greatly reduced. However, many mesh-free methods are limited to low order accuracy. In order to compete with conventional mesh-based methods, high order accuracy is essential. The Local Anisotropic Basis Function Method (LABFM) is a meshfree method introduced in King et al., J. Comput. Phys. 415:109549 (2020), which enables the construction of highly accurate difference operators on disordered node discretisations. Here, we introduce a number of developments to LABFM, in the areas of basis function construction, stencil optimisation, stabilisation, variable resolution, and high order boundary conditions. With these developments, direct numerical simulations of the Navier Stokes equations are possible at extremely high order (up to 10th order in characteristic node spacing internally). We numerically solve the isothermal compressible Navier Stokes equations for a range of geometries: periodic and channel flows, flows past a cylinder, and porous media. Excellent agreement is seen with analytical solutions, published numerical results (using a spectral element method), and experiments. The potential of the method for direct numerical simulations in complex geometries is demonstrated with simulations of subsonic and transonic flows through an inhomogeneous porous media at pore Reynolds numbers up to Rep = 968