Fe2-homogenization of micromorphic elasto-plastic materials

In this work, a homogenization strategy for a micromorphic–type inelastic material is presented. In the spirit of FE2, a representative volume element is attached to each macroscopic quadrature point. Due to the inherent length scale of the micromorphic continuum, size effects for inelastic behavior are obtained on RVE–level. A focus is placed on the computation of the homogenized algorithmic tangent. It is determined via sensitivity analyses with respect to the boundary conditions imposed on the RVE. Following this procedure, costly single–scale computations with dense meshes can be replaced by a robust homogenization approach with optimal convergence rates

Use of Imaging Spectrometer Data and Multispectral Imagery for Improved Earthquake Response

Imaging and Applied Optics Technical Digest, 2012Multispectral imagery and imaging spectrometer data are used to develop prototype map products for improved earthquake response. A tiered approach keyed to post-event communications infrastructure is directed at providing critical information to emergency services personnel.This research is supported by the Science and Technology (S&T) Directorate, Department of Homeland Security (DHS). We gratefully acknowledge the participation of emergency responders and managers from the cities and counties of Monterey, Los Angeles, San Diego, and Riverside California. We also appreciate contributions during project definition stage and follow-ups by the California Emergency Management Agency (Cal EMA) and the Federal Emergency Management Agency (FEMA), the U.S. Geological Survey, and DHS. AVIRIS data were acquired by NASA/JPL. The LiDAR data were provided by the Association of Monterey Bay Area Governments, via a USGS grant through the American Reinvestment and Recovery Act of 2009. WV-2 data were provided by the National Geospatial Intelligence Agency (NGA) under the NextView imagery license agreement

‘Gobbling drops’: the jetting–dripping transition in flows of polymer solutions

This paper discusses the breakup of capillary jets of dilute polymer solutions and the dynamics associated with the transition from dripping to jetting. High-speed digital video imaging reveals a new scenario of transition and breakup via periodic growth and detachment of large terminal drops. The underlying mechanism is discussed and a basic theory for the mechanism of breakup is also presented. The dynamics of the terminal drop growth and trajectory prove to be governed primarily by mass and momentum balances involving capillary, gravity and inertial forces, whilst the drop detachment event is controlled by the kinetics of the thinning process in the viscoelastic ligaments that connect the drops. This thinning process of the ligaments that are subjected to a constant axial force is driven by surface tension and resisted by the viscoelasticity of the dissolved polymeric molecules. Analysis of this transition provides a new experimental method to probe the rheological properties of solutions when minute concentrations of macromolecules have been added.Schlumberger FoundationMIT Class of 1951 Fellowship Fun

The impact of a rural sanitation programme on safe disposal of child faeces: a cluster randomised trial in Odisha, India.

BACKGROUND: Unsafe disposal of child faeces is persistent and may lead to considerable impact on the health of young children. Research is limited on the impact of sanitation or hygiene interventions to improve child faeces disposal practices. METHODS: In the context of a randomised controlled trial to assess the health impact of a programme in Odisha, India, to promote rural sanitation under the Government of India's Total Sanitation Campaign, we explored whether the intervention affected the safe disposal of faeces of children under-5 years of age. RESULTS: At baseline, 1.1% of households practised 'safe' disposal of child faeces, either disposing it in a toilet or by burial. The intervention increased safe disposal of child faeces to 10.4% in intervention households, compared to 3.1% in the control households (RR 3.34; 95% CI 1.99-5.59). This increase in safe disposal is attributable to increases in latrine presence in the intervention communities; the intervention did not change safe disposal practices above and beyond the increase in latrine coverage. CONCLUSIONS: The very modest increase in safe disposal, while statistically significant, is not likely to have consequential health benefit. To achieve open defecation free communities, sanitation interventions will need to develop behaviour change approaches to explicitly target safe disposal behaviours

The impact of a school-based water supply and treatment, hygiene, and sanitation programme on pupil diarrhoea: a cluster-randomized trial.

The impact of improved water, sanitation, and hygiene (WASH) access on mitigating illness is well documented, although impact of school-based WASH on school-aged children has not been rigorously explored. We conducted a cluster-randomized trial in Nyanza Province, Kenya to assess the impact of a school-based WASH intervention on diarrhoeal disease in primary-school pupils. Two study populations were used: schools with a nearby dry season water source and those without. Pupils attending 'water-available' schools that received hygiene promotion and water treatment (HP&WT) and sanitation improvements showed no difference in period prevalence or duration of illness compared to pupils attending control schools. Those pupils in schools that received only the HP&WT showed similar results. Pupils in 'water-scarce' schools that received a water-supply improvement, HP&WT and sanitation showed a reduction in diarrhoea incidence and days of illness. Our study revealed mixed results on the impact of improvements to school WASH improvements on pupil diarrhoea

Capillary breakup of suspensions near pinch-off

We present new findings on how the presence of particles alters the pinch-off dynamics of a liquid bridge. For moderate concentrations, suspensions initially behave as a viscous liquid with dynamics determined by the bulk viscosity of the suspension. Close to breakup, however, the filament loses its homogeneous shape and localised accelerated breakup is observed. This paper focuses on quantifying these final thinning dynamics for different sized particles with radii between 3 μm and 20 μm in a Newtonian matrix with volume fractions ranging from 0.02 to 0.40. The dynamics of these capillary breakup experiments are very well described by a one-dimensional model that correlates changes in thinning dynamics with the particle distribution in the filament. For all samples, the accelerated dynamics are initiated by increasing particle-density fluctuations that generate locally diluted zones. The onset of these concentration fluctuations is described by a transition radius, which scales with the particle radius and volume fraction. The thinning rate continues to increase and reaches a maximum when the interstitial fluid is thinning between two particle clusters. Contrary to previous experimental studies, we observe that the final thinning dynamics are dominated by a deceleration, where the interstitial fluid appears not to be disturbed by the presence of the particles. By rescaling the experimental filament profiles, it is shown that the pinching dynamics return to the self-similar scaling of a viscous Newtonian liquid bridge in the final moments preceding breakup