Study of film formation in EHD contacts using a novel method based on electrical capacitance

The elastohydrodynamic lubrication regime (EHD) is found in many machine elements, such as rolling element bearings, gears, cam/tappet, where a combination of hydrodynamic effect, elastic deformation of the surfaces and an increase of the lubricant’s viscosity with pressure create a continuous lubricant film which is capable of supporting pressures of the order of tens of thousands of atmospheres. One of the most important features of these films is their thickness, as this determines whether the bounding surfaces are completely separated, thus avoiding premature wear and failure of the contact. Consequently for many years scientists were interested in finding methods for measuring the lubricant film thickness in elastohydrodynamic conditions. One of the most versatile and widely used techniques for measuring lubricant film thickness in EHD contacts is the optical interferometry method. Apart from numerous advantages, this method has the limitation in the fact that one of the contacting surfaces must be transparent, usually glass or sapphire, thus it does not replicate real conditions found in machine elements contacts. On the other hand, the other group of methods used for studying the behaviour of elastohydrodynamic films includes a variety of electrical methods. Historically, these appeared before the optical methods, but gradually lost importance with the success of the later. Most capacitive, resistive, inductance methods developed so far use specially designed sensors for monitoring the lubricant film thickness. In the case of electrical techniques, both elements of the contact are metallic, which means that these can be used for measuring film thickness in real machine elements. One of the main disadvantages of electrical methods though, is the difficulty with which the calibration of various electrical quantities, against lubricant film thickness is obtained. This thesis describes the work carried out by the author on the application of a capacitive method for studying lubrication of elastohydrodynamic contacts. The novelty of the method used consists in the calibration of the capacitance of the contact with optical interferometry. This project started from the premises that a thicker Chromium layer will supply the phase change needed to precisely measure the lubricant film thickness by eliminating the fragile silica layer, and it has been shown that an increase in Cr thickness results in a increase in reflection of the glass–Cr interface making the resulting images hard to process. Modifications to the existing experimental rig were carried out in order to apply/collect an electrical signal from both the disc and the ball. Signal collection from the disc was quite straightforward and a graphite brush paired with a copper nut was used, as this is the oldest method of collecting/applying and electrical signal from a rotating element. Collecting an electrical signal from the ball presented quite a challenge as the ball is submerged in oil. A number of brushes was designed, made and tested and the one that provided the most stable results chosen. For calibration purposes a base oil and two additives were chosen, the additives were chosen in such a way that the improvement made to the lubrication process to be very different from one additive to the other. The chosen additives were a Viscosity Index Improver [VII] and an Organic Friction Modifier [OFM]. The VII is used by many researchers in order to obtain multigrade lubricants using the same base oil by varying its percentage in the mix. The OFM is used to provide protection between the two contacting bodies when EHD film fails and EHD lubrication is replaced by mixed lubrication by forming a boundary layer on the contacting surfaces. Optical measurements were carried out on the base oil and the two resulting lubricants from the additive mixes using the Ultra Thin Film Interferometry [UTFI] method. The measurements were used as a benchmark against which the capacitive measurements were calibrated. Tests were conducted in a number of controlled conditions for speed, temperature, load and sliding conditions. Results showed that the highest influence on the lubrication process was given by the speed, an increase in speed results in an increase in optically measured film thickness and a decrease in electrically measured film thickness. Phenomenon explained by a large amount of lubricant pushed into the contact. Another parameter that influenced the results quite significantly was temperature, a rise in temperature supplies a decrease in optically measured film thickness and an increase in capacitive measured film thickness which was explained by lubricant viscosity dropping with a rise in temperature. Three different sliding conditions were employed and a small drop in optically measured film thickness followed by a small rise in electrically measured film thickness was recorded due to a local increase in contact temperature when sliding was employed. The capacitive method developed in this project is precise enough to accurately measure lubricant film thickness down to 100nm; a model for thicknesses lower that 100nm was proposed Results from the optical and capacitive methods were compared and a good correlation was found, indicating that the developed capacitive method can be used as a tool for measuring metal on metal contacts without further calibration.EThOS - Electronic Theses Online ServiceEPSRCGBUnited Kingdo

EUREC⁴A

The science guiding the EUREC⁴A campaign and its measurements is presented. EUREC⁴A comprised roughly 5 weeks of measurements in the downstream winter trades of the North Atlantic – eastward and southeastward of Barbados. Through its ability to characterize processes operating across a wide range of scales, EUREC⁴A marked a turning point in our ability to observationally study factors influencing clouds in the trades, how they will respond to warming, and their link to other components of the earth system, such as upper-ocean processes or the life cycle of particulate matter. This characterization was made possible by thousands (2500) of sondes distributed to measure circulations on meso- (200 km) and larger (500 km) scales, roughly 400 h of flight time by four heavily instrumented research aircraft; four global-class research vessels; an advanced ground-based cloud observatory; scores of autonomous observing platforms operating in the upper ocean (nearly 10 000 profiles), lower atmosphere (continuous profiling), and along the air–sea interface; a network of water stable isotopologue measurements; targeted tasking of satellite remote sensing; and modeling with a new generation of weather and climate models. In addition to providing an outline of the novel measurements and their composition into a unified and coordinated campaign, the six distinct scientific facets that EUREC⁴A explored – from North Brazil Current rings to turbulence-induced clustering of cloud droplets and its influence on warm-rain formation – are presented along with an overview of EUREC⁴A's outreach activities, environmental impact, and guidelines for scientific practice. Track data for all platforms are standardized and accessible at https://doi.org/10.25326/165 (Stevens, 2021), and a film documenting the campaign is provided as a video supplement

EUREC⁴A

The science guiding the EUREC⁴A campaign and its measurements is presented. EUREC⁴A comprised roughly 5 weeks of measurements in the downstream winter trades of the North Atlantic – eastward and southeastward of Barbados. Through its ability to characterize processes operating across a wide range of scales, EUREC⁴A marked a turning point in our ability to observationally study factors influencing clouds in the trades, how they will respond to warming, and their link to other components of the earth system, such as upper-ocean processes or the life cycle of particulate matter. This characterization was made possible by thousands (2500) of sondes distributed to measure circulations on meso- (200 km) and larger (500 km) scales, roughly 400 h of flight time by four heavily instrumented research aircraft; four global-class research vessels; an advanced ground-based cloud observatory; scores of autonomous observing platforms operating in the upper ocean (nearly 10 000 profiles), lower atmosphere (continuous profiling), and along the air–sea interface; a network of water stable isotopologue measurements; targeted tasking of satellite remote sensing; and modeling with a new generation of weather and climate models. In addition to providing an outline of the novel measurements and their composition into a unified and coordinated campaign, the six distinct scientific facets that EUREC⁴A explored – from North Brazil Current rings to turbulence-induced clustering of cloud droplets and its influence on warm-rain formation – are presented along with an overview of EUREC⁴A's outreach activities, environmental impact, and guidelines for scientific practice. Track data for all platforms are standardized and accessible at https://doi.org/10.25326/165 (Stevens, 2021), and a film documenting the campaign is provided as a video supplement

Revenue- versus spending-based consolidation plans: the role of follow up

The literature presents evidence that spending-based fiscal consolidations tend to have more benign macro-economic consequences than revenues-based consolidations. Several explanations have been put forward. By directly comparing ex-post data with consolidation plans, we offer a new explanation based on robust evidence of systematically-weaker follow-up of spending-based consolidation plans. Systematically over-optimistic growth forecasts can explain a substantial part of the differences in follow up. Next, using a newly developed dataset on consolidation announcements, we indeed confirm that follow-up in actual revenues is substantially better than in actual spending and that, consistent with a Keynesian setting, spending-based consolidations produce more benign macro-economic effects. An advantage of our dataset is that we control for confidence effects that can occur immediately after new fiscal information becomes available. Consistent with the ensuing course of the economy, confidence falls (is unchanged) upon announced revenue increases (spending reductions). Under a counterfactual in which the confidence channel is suppressed, announcements of revenue-based consolidations have a substantially less negative effect on the economy

The confidence effects of fiscal consolidations

We explore how fiscal consolidations affect private sector confidence, a possible channel for the fiscal transmission that has received particular attention recently as a result of governments embarking on austerity trajectories in the aftermath of the crisis. Panel regressions based on the action-based datasets of De Vries et al. (2011) and Alesina et al. (2014) show that consolidations, and in particular their unanticipated components affect confidence negatively. The effects are stronger for revenue-based measures and when institutional arrangements, such as fiscal rules, are weak. To obtain a more accurate picture of how consolidations affect confidence, we construct a monthly dataset of consolidation announcements based on the aforementioned datasets, so that we can study the confidence effects in real time using an event study. Consumer confidence falls around announcements of consolidation measures, an effect driven by revenue-based measures. Moreover, the effects are most relevant for European countries with weak institutional arrangements, as measured by the tightness of fiscal rules or budgetary transparency. The effects on producer confidence are generally similar, but weaker than for consumer confidence. Long-term interest rates, as a measure of confidence in the sovereign, tend to fall around spending-based consolidation announcements that take place in slump periods. Overall, if confidence is a concern and consolidation is unavoidable, spending-based measures seem preferable. Slump periods are not necessarily bad moments for such measures, while strengthening institutional arrangements may help in mitigating adverse confidence effects

Studio multicentrico per determinare l\u2019entit\ue0 della contaminazione batterica nei bagni degli ospedali rispetto al sistema di asciugatura delle mani: risultati del centro italiano

INTRODUZIONE L\u2019igiene delle mani \ue8 una delle componenti principali della prevenzione delle infezioni. In letteratura non esistono molti studi mirati a valutare quale sia il sistema di asciugatura delle mani che garantisca la minore diffusione di potenziali patogeni. Il presente studio multicentrico, coordinato dall\u2019Universit\ue0 di Leeds, ha confrontato la contaminazione ambientale batterica nei bagni degli ospedali sulla base del diverso sistema di asciugatura delle mani adottato: fazzoletti di carta (FC) o asciugatore a getto d\u2019aria (AGA). MATERIALI E METODI In ognuno dei tre ospedali partecipanti (Leeds, Parigi, Udine) sono stati selezionati due bagni simili in dimensioni e afflusso quotidiano. Per ogni periodo \ue8 stata resa disponibile agli utenti una sola metodica di asciugatura (FC o AGA): nel bagno 1 era disponibile la metodica FC nel 1\ub0 e 3\ub0 periodo, la metodica AGA nel 2\ub0 periodo; nel bagno 2 era disponibile la metodica AGA nel 1\ub0 e 3\ub0 periodo, la metodica FC nel 2\ub0 periodo. I 3 periodi di campionamento (luned\uec-venerd\uec, per 4 settimane) sono stati intervallati da 2 periodi di washout di 2 settimane, per un totale di 60 sessioni di campionamento. Quotidianamente sono stati prelevati da ogni bagno un campione di aria (tramite air sampler), 4 tamponi delle superfici maggiormente toccate (dispenser, maniglia, lavandino, pavimento) e un campione di polvere (tramite aspirapolvere). I campioni sono stati analizzati dalla SOC Microbiologia, che ha monitorato la presenza di S. aureus MRSA, E. coli, E. Coli ESBL, E. faecalis, E. faecium, C. difficile. RISULTATI Nel centro italiano \ue8 stata rilevata una carica batterica significativamente pi\uf9 elevata dal dispenser AGA rispetto al dispenser FC (mediana 100 vs 0 CFU, p<0,01), con frequenza di recupero 40/60, 66.6% vs 4/60, 6.6% (p<0,01). Per campioni di aria e tamponi di maniglia e lavandino la carica totale \ue8 stata simile, con un numero molto basso di batteri identificati, mentre \ue8 stata osservata una maggiore carica batterica dal pavimento dei bagni AGA e dalla polvere dei bagni FC (differenze non statisticamente significative). CONCLUSIONI I risultati italiani sono coerenti con i dati degli altri ospedali partecipanti e confermano che la contaminazione ambientale \ue8 generalmente pi\uf9 elevata nei bagni in cui sono utilizzati AGA rispetto a FC. In Italia, tuttavia, \ue8 stata isolata solo una gamma limitata di batteri; ci\uf2 potrebbe dipendere da possibili differenze nella pratica della pulizia dei bagni. I nostri risultati suggeriscono che le opzioni per l\u2019asciugatura delle mani hanno un diverso potenziale di contaminazione batterica ambientale

Protocol for Project Fizzyo, an analytic longitudinal observational cohort study of physiotherapy for children and young people with cystic fibrosis, with interrupted time-series design

Twitter @fizzyocfIntroduction: Daily physiotherapy is believed to mitigate the progression of cystic fibrosis (CF) lung disease. However, physiotherapy airway clearance techniques (ACTs) are burdensome and the evidence guiding practice remains weak. This paper describes the protocol for Project Fizzyo, which uses innovative technology and analysis methods to remotely capture longitudinal daily data from physiotherapy treatments to measure adherence and prospectively evaluate associations with clinical outcomes. Methods and analysis: A cohort of 145 children and young people with CF aged 6–16 years were recruited. Each participant will record their usual physiotherapy sessions daily for 16 months, using remote monitoring sensors: (1) a bespoke ACT sensor, inserted into their usual ACT device and (2) a Fitbit Alta HR activity tracker. Real-time breath pressure during ACTs, and heart rate and daily step counts (Fitbit) are synced using specific software applications. An interrupted time-series design will facilitate evaluation of ACT interventions (feedback and ACT-driven gaming). Baseline, mid and endpoint assessments of spirometry, exercise capacity and quality of life and longitudinal clinical record data will also be collected. This large dataset will be analysed in R using big data analytics approaches. Distinct ACT and physical activity adherence profiles will be identified, using cluster analysis to define groups of individuals based on measured characteristics and any relationships to clinical profiles assessed. Changes in adherence to physiotherapy over time or in relation to ACT interventions will be quantified and evaluated in relation to clinical outcomes. Ethics and dissemination: Ethical approval for this study (IRAS: 228625) was granted by the London-Brighton and Sussex NREC (18/LO/1038). Findings will be disseminated via peer-reviewed publications, at conferences and via CF clinical networks. The statistical code will be published in the Fizzyo GitHub repository and the dataset stored in the Great Ormond Street Hospital Digital Research Environment. Trial registration number: ISRCTN51624752; Pre-results.UCL Rosetrees Stoneygate prize (M712), a Cystic Fibrosis Trust Clinical Excellence and Innovation Award (CEA010), A UCL Partners award and the HEFCE Higher Education Innovation Fund (KEI2017-01-04). GD is supported by a Wellcome Institutional Strategic Support Fund award at UCL (204841/Z/16/Z), and formerly an NIHR Clinical Trials Fellowship. HD is funded by the CF Trust Youth Activity Unlimited SRC and an NIHR GOSH BRC internship. All work at UCL GOSICH is supported by the NIHR GOSH BRC