Military helicopters: have the seeds of future accidents already been sown?

Military helicopters provide ideal conditions for the nucleation and propagation of failure damage. Very few modern machines are expected to perform under such diverse loading and environmental conditions. It is often assumed that failures are a direct consequence of these extreme operating conditions. This paper aims to demonstrate that the originating causes of failure can be introduced at any point in the life of a component, including the design, materials processing, manufacturing or during the service life of the component. Solutions to prevent recurrence of problems cannot be developed without identification of the root cause. Details of four investigations will be presented. Each case study will demonstrate a physical cause residing in an action/inaction occurring during one (or more) of the key life stages of a component, Design, Processing, Manufacture and Service

Impact of Credit on the Relative Well?Being of Women: Evidence from the Grameen Bank

summary This study examines the impact of credit on women's relative well?being in Grameen Bank's credit programmes. Using a bargaining model of the household, as extended by Amartya Sen, well?being has been defined in terms of three sets of capabilities: (i) autonomy, (ii) control over decision?making within the family, and (iii) relative access to household resources. It is hypothesised that the relative well?being of women and men depends on their respective bargaining power, which in turn depends on three factors: breakdown position, perceived contribution to the family and perceived self?interest. The hypothesis has been tested using a two?stage estimation method to avoid the potential problem of simultaneity bias that may be caused by the self?selection problem. Results indicate that involvement in credit has improved the relative well?being of women in some dimensions, but not in others. Some reasons are advanced for this partial success in improving women's well?being

Development of a low-maintenance measurement approach to continuously estimate methane emissions: a case study

The chemical breakdown of organic matter in landfills represents a significant source of methane gas (CH4). Current estimates suggest that landfills are responsible for between 3% and 19% of global anthropogenic emissions. The net CH4 emissions resulting from biogeochemical processes and their modulation by microbes in landfills are poorly constrained by imprecise knowledge of environmental constraints. The uncertainty in absolute CH4 emissions from landfills is therefore considerable. This study investigates a new method to estimate the temporal variability of CH4 emissions using meteorological and CH4 concentration measurements downwind of a landfill site in Suffolk, UK from July to September 2014, taking advantage of the statistics that such a measurement approach offers versus shorter-term, but more complex and instantaneously accurate, flux snapshots. Methane emissions were calculated from CH4 concentrations measured 700 m from the perimeter of the landfill with observed concentrations ranging from background to 46.4 ppm. Using an atmospheric dispersion model, we estimate a mean emission flux of 709 μg m−2 s−1 over this period, with a maximum value of 6.21 mg m−2 s−1, reflecting the wide natural variability in biogeochemical and other environmental controls on net site emission. The emissions calculated suggest that meteorological conditions have an influence on the magnitude of CH4 emissions. We also investigate the factors responsible for the large variability observed in the estimated CH4 emissions, and suggest that the largest component arises from uncertainty in the spatial distribution of CH4 emissions within the landfill area. The results determined using the low-maintenance approach discussed in this paper suggest that a network of cheaper, less precise CH4 sensors could be used to measure a continuous CH4 emission time series from a landfill site, something that is not practical using far-field approaches such as tracer release methods. Even though there are limitations to the approach described here, this easy, low-maintenance, low-cost method could be used by landfill operators to estimate time-averaged CH4 emissions and their impact downwind by simultaneously monitoring plume advection and CH4 concentrations

From building to city level dynamic digital Twin: A review from data management perspective

The development of the digital twin (DT) has been focused greatly after the concept was brought from the manufacturing and aerospace areas. In the architectural, engineering, construction and facility management (AEC/FM) sector, DTs are capable of integrating heterogeneous metadata and cutting-edge technologies like artificial intelligence and machine learning to create a dynamic digital environment for various purposes. Although building information modelling (BIM) appears to be a significant contributor to DTs, one of the major limitations for DT development is how to construct and provide a shared data environment for all stakeholders to collaborate throughout the life cycle. Furthermore, as the stakeholders' requirements range of DTs expands from a single building to multiple buildings and regional/city levels, the information and data management gaps (e.g., BIM and GIS data integration) are more challenging and critical. To address these gaps, this paper aims to 1) review the current data management for building and city level DTs from a technical perspective; 2) summarise their major data management issues from building to city levels based on the review; 3) introduce the concept of city-level Common Data Environment (CDE) that addresses the issues identified above, and discuss the possibilities of developing a CDE for a dynamic city-level DT

SEWAL: an open-source platform for next-generation sequence analysis and visualization

Next-generation DNA sequencing platforms provide exciting new possibilities for in vitro genetic analysis of functional nucleic acids. However, the size of the resulting data sets presents computational and analytical challenges. We present an open-source software package that employs a locality-sensitive hashing algorithm to enumerate all unique sequences in an entire Illumina sequencing run (∼108 sequences). The algorithm results in quasilinear time processing of entire Illumina lanes (∼107 sequences) on a desktop computer in minutes. To facilitate visual analysis of sequencing data, the software produces three-dimensional scatter plots similar in concept to Sewall Wright and John Maynard Smith’s adaptive or fitness landscape. The software also contains functions that are particularly useful for doped selections such as mutation frequency analysis, information content calculation, multivariate statistical functions (including principal component analysis), sequence distance metrics, sequence searches and sequence comparisons across multiple Illumina data sets. Source code, executable files and links to sample data sets are available at http://www.sourceforge.net/projects/sewal

Sequential quasi-Monte Carlo: Introduction for Non-Experts, Dimension Reduction, Application to Partly Observed Diffusion Processes

SMC (Sequential Monte Carlo) is a class of Monte Carlo algorithms for filtering and related sequential problems. Gerber and Chopin (2015) introduced SQMC (Sequential quasi-Monte Carlo), a QMC version of SMC. This paper has two objectives: (a) to introduce Sequential Monte Carlo to the QMC community, whose members are usually less familiar with state-space models and particle filtering; (b) to extend SQMC to the filtering of continuous-time state-space models, where the latent process is a diffusion. A recurring point in the paper will be the notion of dimension reduction, that is how to implement SQMC in such a way that it provides good performance despite the high dimension of the problem.Comment: To be published in the proceedings of MCMQMC 201

Increasing situation awareness in healthcare through real-time simulation

This is the final version. Available from Taylor & Francis via the DOI in this record. Research into real-time simulation applications outside of manufacturing environments has extended to sociotechnical systems such as healthcare over the past decade, where a number of published studies have demonstrated proof-of-concept models for near-future resource planning. Using real-time decision-support systems, people take decisions supported by the output of simulations. However real-time simulation frameworks abstract human intervention to an “external decision-maker,” with little regard to the complexities of underlying decision-making constructs, and how design and development decisions can impact the quality of decision-support. One such construct is situation awareness (SA), which is a precursor to decision-making. It is a dynamic state of knowledge about how a situation is unfolding; one approach to enhancing situation awareness is the provision of appropriate real-time information. We argue that design, development and implementation decisions should be focused at the interface between decision-making and decision-support. This integrative literature review proposes a SA framework integrating models of SA with a technical perspective for real-time simulation, to support an understanding of the cognitive needs of users alongside technical details during the development process. The implications for the usefulness and usability of real-time decision-support tools are discussed with application to Emergency Departments.Economic and Social Research CouncilEconomic and Social Research CouncilNational Institute for Health Researc

A novel method for the analysis of particle coating behaviour via contact spreading in a tumbling drum: Effect of coating liquid viscosity

Spray coating is a common method of distributing liquids over powders, especially in the pharmaceutical, detergent and food industries. During this process, liquid drops are deposited on the surface of particles. Liquid is then transferred between particles via particle collisions, in a process called liquid contact spreading. This contact spreading process facilitates inter-particle coating, in which wetting, de-wetting, mixing and drying are occurring simultaneously. This work presents the first experimental study of the mechanism of liquid contact spreading. In this work, a novel experimental method has been developed to investigate the mechanism of contact spreading, incorporating a newly developed image analysis technique, based on colourimetric measurements, to quantitatively determine coating behaviour via contact spreading. Here, experiments designed to isolate the contact spreading coating mechanism were performed in a tumbling drum using a model material system; alumina particles and dyed polyethylene glycol solutions of varying viscosities. The coating uniformity was quantified by the variation in inter-particle coating; the coefficient of variation (CoV). For all systems, the uniformity of the coating increased with time until the CoV decreased to an asymptotic value. The rate of the decrease in the CoV was successfully fitted using an exponential decay function. The viscosity of the coating solution had a significant effect on the rate of liquid transfer; the lower the viscosity the faster the contact spreading process. This effect is attributed to differences in the formation and stability of liquid bridges between the particles, influencing the extent of liquid transfer. The results also show that in most cases examined here, viscous forces play a main role in the contact spreading process, and the contribution of capillary forces are minimal. This understanding could assist the design and scale up for the wet coating processes