A One-Field Monolithic Fictitious Domain Method for Fluid-Structure Interactions

In this article, we present a one- eld monolithic fictitious domain (FD) method for simulation of general fluid-structure interactions (FSI). "One-fi eld" means only one velocity field is solved in the whole domain, based upon the use of an appropriate L2 projection. "Monolithic" means the fluid and solid equations are solved synchronously (rather than sequentially). We argue that the proposed method has the same generality and robustness as FD methods with distributed Lagrange multiplier (DLM) but is signi ficantly more computationally e fficient (because of one-fi eld) whilst being very straightforward to implement. The method is described in detail, followed by the presentation of multiple computational examples in order to validate it across a wide range of fluid and solid parameters and interactions

MeshingNet: A New Mesh Generation Method based on Deep Learning

We introduce a novel approach to automatic unstructured mesh generation using machine learning to predict an optimal finite element mesh for a previously unseen problem. The framework that we have developed is based around training an artificial neural network (ANN) to guide standard mesh generation software, based upon a prediction of the required local mesh density throughout the domain. We describe the training regime that is proposed, based upon the use of a posteriori error estimation, and discuss the topologies of the ANNs that we have considered. We then illustrate performance using two standard test problems, a single elliptic partial differential equation (PDE) and a system of PDEs associated with linear elasticity. We demonstrate the effective generation of high quality meshes for arbitrary polygonal geometries and a range of material parameters, using a variety of user-selected error norms

Researching informal workplace learning in the context of remote working in the post COVID-19 world

Work practices and learning are entangled processes that operate differently in each workplace. Central factors producing this diversity are the informal, social and affective cultures facilitated and supported in each workplace. Recent research findings further suggest that these informal modes of workplace practice are critical for how people in these organisations learn, and for their capacity to innovate and adapt to changes in their business environment. Lockdowns implemented because of the COVID-19 pandemic, during which many organisations and individuals have had to embrace remote working using digital devices, software and broadband, have significantly reduced opportunities for these important informal and social dimensions of workplace practice. Given the likelihood that diverse forms and degrees of remote working will become part of the post-pandemic ‘new normal’, we discuss in this paper approaches to researching the extent to which, and in what forms, the benefits of informal interactions can be enabled and replicated in situations of partially or wholly remote working. The paper contributes to the literature on workplace learning by critically discussing the effects of the pandemic, and especially remote working, on the modern workplace, and discussing possible future directions for research

Growth of Epitaxial Oxide Thin Films on Graphene

The transfer process of graphene onto the surface of oxide substrates is well known. However, for many devices, we require high quality oxide thin films on the surface of graphene. This step is not understood. It is not clear why the oxide should adopt the epitaxy of the underlying oxide layer when it is deposited on graphene where there is no lattice match. To date there has been no explanation or suggestion of mechanisms which clarify this step. Here we show a mechanism, supported by first principles simulation and structural characterisation results, for the growth of oxide thin films on graphene. We describe the growth of epitaxial SrTiO3 (STO) thin films on a graphene and show that local defects in the graphene layer (e.g. grain boundaries) act as bridgepillar spots that enable the epitaxial growth of STO thin films on the surface of the graphene layer. This study, and in particular the suggestion of a mechanism for epitaxial growth of oxides on graphene, offers new directions to exploit the development of oxide/graphene multilayer structures and devices

Characterization of cortex and white matter injury in a mild hypoxic-ischemic neonatal rat mode by diffusion tensor MR imaging

Animal Studies: Diffusion & Perfusion - Poster presentationWe evaluated hypoxic-ischemic (HI) induced cortex and white matter (WM) damage in a mild HI neonatal rat model at 24h post HI by diffusion tensor MR imaging (DTI) and correlated the DTI indices with histological evaluations. Results showed that significantly decreased FA and ¦Ë// reflected HI induced astrogliosis in the injured cortex, whereas significantly decreased FA with increased ¦Ë¡Í indicated dysmyelination in the WM. Our results demonstrated that early mild HI induced cortex and WM damage could be reflected by DTI indices and these may be potentially useful biomarkers to non-invasively monitor mild HI induced neonatal brain damage.published_or_final_versionThe 17th Scientific Meeting & Exhibition of the International Society of Magnetic Resonance in Medicine (ISMRM), Honolulu, HI., 18-24 April 2009. In Proceedings of ISMRM 17th Scientific Meeting & Exhibition, 2009, p. 359

An Algorithmic Framework for Labeling Network Maps

Drawing network maps automatically comprises two challenging steps, namely laying out the map and placing non-overlapping labels. In this paper we tackle the problem of labeling an already existing network map considering the application of metro maps. We present a flexible and versatile labeling model. Despite its simplicity, we prove that it is NP-complete to label a single line of the network. For a restricted variant of that model, we then introduce an efficient algorithm that optimally labels a single line with respect to a given weighting function. Based on that algorithm, we present a general and sophisticated workflow for multiple metro lines, which is experimentally evaluated on real-world metro maps.Comment: Full version of COCOON 2015 pape

Effects of long pulse width and high pulsing frequency on surface superhydrophobicity of polytetrafluoroethylene in quasi-direct-current plasma immersion ion implantation

Long pulse, high frequency quasi-direct-current (dc) oxygen plasma immersion ion implantation (PIII) is utilized to create a superhydrophobic polytetrafluoroethylene (PTFE) surface with a water contact angle of over 150°. This technique allows the use of a high duty cycle without deleterious effects such as extensive sample heating encountered in conventional PIII. Scanning electron microscopy images review submicrometer-nanometer structures on the PTFE surface after long pulse, high frequency PIII indicative of ion implantation. On the other hand, plasma modification is the dominant effect in short pulse, low frequency PIII. Quasi-dc PIII is demonstrated to offer adjustable synergistic plasma and ion beam effects. © 2009 American Institute of Physics.published_or_final_versio

Performance Evaluation of Two 25 kW Residential Wood Pellet Boiler Heating Systems

A significant increase in the use of wood pellets for residential space heating has occurred over the past decade. The performance of two modern residential wood pellet boilers (designated PB and WPB) were evaluated including boiler thermal efficiency, thermal energy storage (TES) tank discharge efficiency, and system efficiency. A correlation applicable to both systems between the boiler thermal efficiency (ηth, in %) and the boiler output load (χ, in %) was found in the form of ηth = 52.69 ln χ – 137.7 with R2 = 0.79 (for 25 < χ < 75). This equation provides an easy, accurate estimation of the boiler thermal efficiency in field operations. The boiler thermal efficiency decreased with time and this decline was determined using a Mann-Kendall trend analysis with Sen’s slope. This decrease was primarily the result of fouling in the heat exchanger and thus, this analysis identifies the need for manual cleaning of the heat exchanger tubes to restore maximal system performance. The evaluation of the TES tank performance found that the TES tank discharge efficiency was correlated with a dimensionless function of tank inlet Reynolds number (Red) and temperature differences in the tank and inlet and outlet pipes. Overall system efficiency showed a seasonal average of 62.8%, 62.0%, and 75.8% for three heating seasons of the PB system. These results provide a comprehensive performance evaluation of these wood pellet boiler heating systems in the field over an extended period of operation