Modelling of two-component turbulent mass and heat transfer in air-fed pressurised suits

This article has been accepted for publication in the Flow, Turbulence and Combustion journal.In this paper the modelling of an important industrial problem is addressed, which involves the two-component turbulent flow with heat transfer that takes place inside protective clothing. The geometry of the flow boundaries is reconstructed in a CAD system from photogrammetry scan data. The overall model is sufficiently realistic to allow, after validation, design improvements to be tested. Those presented here allow the reduction of hot spots over the worker’s body surface and increase thermal comfort.This project is funded by the Engineering and Physical Sciences Research Council and the UK Atomic Energy Authority

Heat and mass transfer in air-fed pressurised suits

Air-fed pressurised suits are used to protect workers against contamination and hazardous environments. The specic application here is the necessity for regular clean-up maintenance within the torus chamber of fusion reactors. The current design of suiting has been developed empirically. It is, therefore, very desirable to formulate a thermofluids model, which will be able to define optimum designs and operating parameters. Two factors indicate that the modelling should be as comprehensive as possible. Firstly, the overall thermofluids problem is three-dimensional and includes mass as well as heat transfer. The fluid field is complex, bounded on one side by the human body and on the other by what may be distensible, porous and multi-layer clothing. In this paper, we report firstly the modelling necessary for the additional mass and heat transport processes. This involves the use of Fick's and Fourier's laws and conjugate heat transfer. The results of an initial validation study are presented. Temperatures at the outlet of the suits were obtained experimentally and compared with those predicted by the overall CFD model. Realistic three-dimensional geometries were used for the suit and human body. Calculations were for turbulent flow with single- and two-component (species) models

The Avowal

https://digitalcommons.library.umaine.edu/mmb-ps/2979/thumbnail.jp

Sensitive Force Measurements With Optically Trapped Micro-Spheres in High Vacuum

This dissertation details our work on optically levitating and cooling microspheresin vacuum for use as force sensors. We have extensively modeled various optical trap congurations to determine stable trap geometries for m sized spheresin a dual-beam optical trap. Techniques have been developed for overcoming instabilities which occur when pumping trapped micro-spheres from low to high vacuum.We have also improved on methods for depositing micro-spheres in optical traps.We have shown that optically levitated micro-spheres are excellent force sensors.By eliminating the need to tether the spheres to a solid substrate, excellent environmental decoupling is achieved. In this work we present the realization of a N force sensitivity. The intended use for the technology developed is to extend the search for non-Newtonian gravity by several orders of magnitude at the micrometer length scale [1]. This technology is also suitable for investigating the Casimir eectin the unexplored regime where neither the Proximity Force Approximation or the Casimir-Polder limits are valid

Sun Shower : Caprice

https://digitalcommons.library.umaine.edu/mmb-ps/1907/thumbnail.jp

Stationary and non-stationary fluid flow of a Bose-Einstein condensate through a penetrable barrier

We experimentally study the fluid flow induced by a broad, penetrable barrier moving through an elongated dilute gaseous Bose-Einstein condensate. The barrier is created by a laser beam swept through the condensate, and the resulting dipole potential can be either attractive or repulsive. We examine both cases and find regimes of stable and unstable fluid flow: At slow speeds of the barrier, the fluid flow is stationary due to the superfluidity of the condensate. At intermediate speeds, we observe a non-stationary regime in which the condensate gets filled with dark solitons. At faster speeds, soliton formation completely ceases and a remarkable absence of excitation in the condensate is seen again.Comment: 4 pages, 4 figure

Bridging the chasm –a study of the realities of edtech use among trainee teachers

This paper evaluates the findings of a small scale research project into how trainee teachers can use technology for educational purposes. The paper is inspired by an apparent disconnect between the availability of educational technology (abbreviated from here to edtech) and the frequency and impact of its use. Furthermore, the paper aims to assess the extent to which trainee teachers are developing the skills and behaviours that are deemed necessary for the digital world. This paper’s focus is on the use of edtech with a cohort of trainee teachers. The first cohort is comprised of Secondary PGDE students, the second of PGCE trainee teachers specialising in Further Education and Training. A complementary element to the research reveals the disparities between individual trainees in their confidence towards using edtech and the barriers that are inhibiting the use of edtech. The work adheres to the principles of action research and was supported by two universities in the north of England. Through online questionnaires using Surveyhero.com, and focus groups, this paper raised some notable issues and areas for further stud

More than just a quiz - how Kahoot! can help trainee teachers understand the learning process

This paper evaluates the findings of a small-scale research project into how trainee teachers can use Kahoot! to help them reflect on the learning process. Kahoot! is an online collaborative learning platform - a game-based student response system (GSRS), which was launched in 2012. It is frequently used as a quiz by experienced and trainee teachers. These quizzes are frequently focused on recall and low order thinking. This paper aims to explore how teachers can design Kahoot! quizzes in a way that enables them to better understand the links between educational technologies and learning. A complementary element to the research assessed the effectiveness of Kahoot! as an example of using edtech to gather formative data and also develop their learners’ own questioning techniques. Through questionnaires, focus groups, individual interviews and Kahoot! surveys, this paper gained an insight into future areas that may be worthy of pursuit

My social autoethnography: How one teacher educator used digital communication to help tell his own stories

This paper inhabits the increasingly popular space of autoethnographic study. The piece is designed to critique and contextualise the process and usefulness of autoethnography as a way of making meaning. The study centres on how one highly experienced teacher and newly appointed teacher educator is using narrative writing to unpick and locate their skillset in a period of swift change and marked transition. One of the reasons for this choice is the freedom that autoethnography allows. Autoethnography is frequently dismissed as vague and self-indulgent as a method of social research. This paper will propose that autoethnography is a rigorous and powerful research method. It deploys some innovative methods of data collection, analysis and dissemination. The paper's discussion of the literature will naturally help interrogate debates around where autoethnography sits in the intellectual landscape related to qualitative research. The study found that using grounded theory as a research methodology helped arrive at potentially illuminating theories and self-knowledge. These were limited, however, by the underlying risk of indulgence, subjective autobiographical writing and participant bias. The paper also has potential value as a way of helping early career teachers explore critical incidents

An Energy-Minimization Finite-Element Approach for the Frank-Oseen Model of Nematic Liquid Crystals: Continuum and Discrete Analysis

This paper outlines an energy-minimization finite-element approach to the computational modeling of equilibrium configurations for nematic liquid crystals under free elastic effects. The method targets minimization of the system free energy based on the Frank-Oseen free-energy model. Solutions to the intermediate discretized free elastic linearizations are shown to exist generally and are unique under certain assumptions. This requires proving continuity, coercivity, and weak coercivity for the accompanying appropriate bilinear forms within a mixed finite-element framework. Error analysis demonstrates that the method constitutes a convergent scheme. Numerical experiments are performed for problems with a range of physical parameters as well as simple and patterned boundary conditions. The resulting algorithm accurately handles heterogeneous constant coefficients and effectively resolves configurations resulting from complicated boundary conditions relevant in ongoing research.Comment: 31 pages, 3 figures, 3 table