Incubation of penguin eggs

The preservation of rare and endangered species of birds requires finding efficient, and above all successful, methods of breeding them in captivity. One strategy adopted is to remove eggs from the mother, making her lay more eggs, and then incubating the removed eggs artificially. Artificial incubation machines must attempt to replicate the conditions of natural incubation as closely as possible. Aside from careful control of temperature and humidity within the artificial incubator, an important factor to reproduce is that eggs must be turned about their long axis from time to time. Hatching will not occur in an egg that is not subjected to some form of occasional rotation. The reason why eggs are turned and the way in which they should be turned are still not well understood. The Study Group attempted to gain some insight into why eggs have to be turned from a fluid dynamic perspective. A simple egg-turning model for an egg at the first stages of incubation was constructed, based on lubrication theory

Design of microfluidic networks

Microfluidics is a relatively new and fast growing research area in fluid mechanics. The devices in question are thin wafers containing etched or printed interconnecting channels through which fluids are pumped, which can mix and/or react at various nodes to produce an output product. Microfluidic devices have applications in many manufacturing and chemical detection processes. For example, they can be used to manufacture monodisperse droplets with very well defined properties for pharmaceutical applications; or form the basis for miniaturised ‘lab-on-a-chip’ sensor arrays for detecting biological substances or toxins

Roses are unselfish: a greenhouse growth model to predict harvest rates.

We consider the question of how rose production in a greenhouse can be optimised. Based on realistic assumptions, a rose growth model is derived that can be used to predict the rose harvest. The model is made up of two constituent parts: (i) a local model that calculates the photosynthetic rate per area of leaf and (ii) a global model of the greenhouse that transforms the photosynthesis of the leaves into an increase in mass of the rose crop. The growth rate of the rose stems depends not only on the time-dependent ambient conditions within the greenhouse, which include temperature, relative humidity, CO$_2$ concentration and light intensity, but also on the location and age distribution of the leaves and the form of the underlying rose bush supporting the crop

Analysis of the uncertainty in microbubble characterization

There is increasing interest in the use of microbubble contrast agents for quantitative imaging applications such as perfusion and blood pressure measurement. The response of a microbubble to ultrasound excitation is, however, extremely sensitive to its size, the properties of its coating and the characteristics of the sound field and surrounding environment. Hence the results of microbubble characterization experiments can be significantly affected by experimental uncertainties, and this can limit their utility in predictive modelling. The aim of this study was to attempt to quantify these uncertainties and their influence upon measured microbubble characteristics. Estimates for the parameters characterizing the microbubble coating were obtained by fitting model data to numerical simulations of microbubble dynamics. The effect of uncertainty in different experimental parameters was gauged by modifying the relevant input values to the fitting process. The results indicate that even the minimum expected uncertainty in, for example, measurements of microbubble radius using conventional optical microscopy, leads to variations in the estimated coating parameters of ~20%. This should be taken into account in designing microbubble characterization experiments and in the use of data obtained from them

Cut-On Cut-Off Transition in Flow Ducts: Comparing Multiple-Scales and Finite-Element Solutions

The phenomenon of cut-on cut-off transition of acoustic modes in ducts with mean flow is examined using an analytical multiple-scales solution, and compared to solutions obtained from a numerical finite-element method. The analytical solution, derived for an arbitrary duct with irrotational mean flow, remains valid to leading-order throughout the duct. In other words, it is a composite solution, encompassing both the inner boundary-layer solution in the neighbourhood of the transition point and the outer slowly varying modal solution far upstream and downstream. Several test cases are defined and presented within a geometry representative of a high-bypass turbofan engine. The cases span a wide realistic range of frequencies and circumferential mode numbers both with and without mean flow, including one numerically-challenging investigation of cut-off cut-on transition of a mode. The agreement is in most cases remarkably good. Slight differences in position of the pressure pattern can be observed for cases with mean flow, which seem due to the slight variations in mean flow fields obtained from both methods. When cut-on cut-off transition occurs for high Helmholtz number and high radial mode number a certain amount of modal scattering is observed. An attempt is made to explain this by incorporating the presence of neighbouring modes in the asymptotic scaling arguments for the turning point region. The composite solution should enable designers to continue to use multiple-scales theory to examine flow pressure and noise transmission inside an engine duct, whilst now being able to include directly the contributions of modes undergoing transition without encountering singular behaviour

Estimating 'lost heart beats' rather than reductions in heart rate during the intubation of critically-ill children.

PURPOSE: Reductions in heart rate occur frequently in children during critical care intubation and are currently considered the gold standard for haemodynamic instability. Our objective was to estimate loss of heart beats during intubation and compare this to reduction in heart rate alone whilst testing the impact of atropine pre-medication. METHODS: Data were extracted from a prospective 2-year cohort study of intubation ECGs from critically ill children in PICU/Paediatric Transport. A three step algorithm was established to exclude variation in pre-intubation heart rate (using a 95%CI limit derived from pre-intubation heart rate variation of the children included), measure the heart rate over time and finally the estimate the numbers of lost beats. RESULTS: 333 intubations in children were eligible for inclusion of which 245 were available for analysis (74%). Intubations where the fall in heart rate was less than 50 bpm were accompanied almost exclusively by less than 25 lost beats (n = 175, median 0 [0-1]). When there was a reduction of >50 bpm there was a poor correlation with numbers of lost beats (n = 70, median 42 [15-83]). During intubation the median number of lost beats was 8 [1]-[32] when atropine was not used compared to 0 [0-0] when atropine was used (p50 bpm the heart rate was poorly predictive of lost beats. A study looking at the relationship between lost beats and cardiac output needs to be performed. Atropine reduces both fall in heart rate and loss of beats. Similar area-under-the-curve methodology may be useful for estimating risk when biological parameters deviate outside normal range

Raw data for A combined 3D in vitro - in silico approach to modelling bubble dynamics in decompression sickness

These are the Prism files which contain the raw data for the experimental bubble growth for variation in dive parameters and the experimental and simulated data for the oscillatory pressure profile

Deliverable D2.14

This report forms, in two parts, deliverable D2.14 of the TurboNoiseCFD project. It describes the recommended innovative "triple plane pressure" in-duct matching strategy (TPP) at inlet and bypass duct side, and it describes in detail the newly developed and favourably tested CAA code for the propagation and radiation problem at the exhaust side. Due to the presence of the jet, this solution is also innovativ