712 research outputs found
Quantitative imaging of the complexity in liquid bubbles' evolution reveals the dynamics of film retraction
The dynamics and stability of thin liquid films have fascinated scientists
over many decades. Thin film flows are central to numerous areas of
engineering, geophysics, and biophysics and occur over a wide range of length,
velocity, and liquid properties scales. In spite of many significant
developments in this area, we still lack appropriate quantitative experimental
tools with the spatial and temporal resolution necessary for a comprehensive
study of film evolution. We propose tackling this problem with a holographic
technique that combines quantitative phase imaging with a custom setup designed
to form and manipulate bubbles. The results, gathered on a model aqueous
polymeric solution, provide an unparalleled insight into bubble dynamics
through the combination of full-field thickness estimation, three-dimensional
imaging, and fast acquisition time. The unprecedented level of detail offered
by the proposed methodology will promote a deeper understanding of the
underlying physics of thin film dynamics
Respiratory Aware Routing for Active Commuters
Cyclists travelling in urban areas are particularly at risk of harm from
particulate emissions due to their increased breathing rate and proximity to
vehicles. In this paper we combine human respiratory models with models of
particulate inhalation to estimate the pollution risk an individual is
experiencing in real time given the local pollution level and their heart rate
for the first time. Using this model as a baseline, we learn a policy that
simultaneously optimises the route for a large number of cyclists with diverse
origins and destinations, to minimise overall pollution risk and account for
the detrimental impacts of congestion. We learn this policy using reinforcement
learning techniques on simulated data in different environments with varying
distributions of cyclist fitness. These findings establish that individualised
routing is effective in reducing pollution risk while cycling, improving the
net benefits of active commuting
Leaf Community: Control of an AC microgrid
Microgrids can be considered the building block and the backbone of the new way of thinking the
electrical grid, the smart grid. Integration of control theory, information technology and electronic
power plays an important role in closing the gap with this new paradigm which is considered an
important step towards integration of renewable sources of energy, new economic opportunities and
an overall safer and more efficient electric distribution net.
This thesis has been developed in cooperation with the Loccioni group. The contribution of this
thesis are threefold: (i) a realistic model of their microgrid was implemented in a Matlab/Simulink
environment; (ii) a control system was designed to achieve stability of the whole system and to obtain
plug and play inverters, that can work without central controllers; (iii) the developed algorithms were
implemented in a PLC environment.
The solutions implemented within the thesis work are being currently implemented in the real
microgrid at Loccioni
Serum Potassium Disorders Predict Subsequent Kidney Injury: A Retrospective Observational Cohort Study of Hospitalized Patients
Introduction: Electrolyte disorders are common findings in kidney diseases and might represent a useful biomarker preceding kidney injury. Serum potassium [K+] imbalance is still poorly investigated for association with acute kidney injury (AKI), and most evidence came from intensive care units. The aim of our study was to comprehensively investigate this association in a large, unselected cohort of hospitalized patients. Methods: We performed a retrospective observational cohort study on the inpatient population admitted to Fondazione Policlinico Universitario A. Gemelli IRCCS between January 1, 2010 and December 31, 2014, with inclusion of adult patients with at least 2 [K+] and 3 serum creatinine measurements who did not develop AKI during an initial 10-day window. The outcome of interest was in-hospital AKI. The exposures of interest were [K+] fluctuations and hypo (HoK) and hyperkalemia (HerK). [K+] variability was evaluated using the coefficient of variation. Cox proportional hazards regression models were used to obtain hazard ratios and 95% confidence intervals of the association between the exposures of interest and development of AKI. Results: About 21,830 hospital admissions from 18,836 patients were included in our study. During a median follow-up of 5 (interquartile range [IQR] 7) days, AKI was observed in 555 hospital admissions (2.9%); median time for AKI development was 5 (IQR 7) days. Higher [K+] variability was independently associated with increased risk of AKI with a statistically significant linear trend across groups (p value = 0.012). A significantly higher incidence of AKI was documented in patients with HerK compared with normokalemia. No statistically significant difference was observed between HoK and HerK (p value = 0.92). Conclusion: [K+] abnormalities including fluctuations even within the normal range are associated with development of AKI
- …