The relaxation of two-dimensional rolls in Rayleigh–Bénard convection

Large aspect ratio, two-dimensional, periodic convection layers containing a Boussinesq fluid of finite Prandtl number bounded by rigid or free horizontal surfaces are investigated numerically. The fluid equations are solved using both a standard pseudospectral and a Fourier integral method for the time evolution of finite initial perturbations, both random thermal perturbations and localized roll disturbances, into a final equilibrium state. The suggestion that a Fourier integral solution method is required to yield roll relaxation, the two-dimensional process increasing the convection wavelength to values larger than critical, is investigated. Roll relaxation is found for both free-slip and no-slip surfaces using either solution method as long as the initial state is chosen to be of the form of a localized roll disturbance. A wide variety of simulations are performed and roll relaxation is found to be independent of the periodic domain length, weakly dependent on the Rayleigh number and dependent upon the magnitude of the initial localized roll disturbances

Visualizing experience: using creative research methods with members of sexual and gender communities

This chapter argues that visual methods may be particularly appropriate for the study of non- heteronormative sexualities and genders, particularly the more marginal identities and practices which have tended to be pathologised in, and excluded from, past research. We focus here on three of these: bisexuality (attraction to more than one gender, or regardless of gender), trans (moving away from the gender which was assigned at birth), and polyamory (having multiple sexual and/or intimate relationships). Of course trans people may be heterosexual, or indeed of any sexuality, but have tended to be marginalised in many of the same ways as people from non-heterosexual sexualities, and are consequently included in this chapter for that reason. First we briefly overview the history of qualitative research on non-heterosexual sexualities and trans, arguing that qualitative methods, per se, do not prevent researchers from forming limiting understandings and problematic generalisations about such groups. Then we present an alternative to conventional interview/focus group discussion research involving the use of visual methods. We summarise key reasons why this may be particularly appropriate to the exploration of those in marginalised sexualities, genders and relationship forms, and then present three examples, based in our own research, of the ways in which such research provided data which confounded simple celebratory or critical conclusions about people in these communities. Finally, we summarise some methodological considerations which are of value to those considering the use of visual methods in their own research

Rayleigh-Benard Convection in Large-Aspect-Ratio Domains

The coarsening and wavenumber selection of striped states growing from random initial conditions are studied in a non-relaxational, spatially extended, and far-from-equilibrium system by performing large-scale numerical simulations of Rayleigh-B\'{e}nard convection in a large-aspect-ratio cylindrical domain with experimentally realistic boundaries. We find evidence that various measures of the coarsening dynamics scale in time with different power-law exponents, indicating that multiple length scales are required in describing the time dependent pattern evolution. The translational correlation length scales with time as $t^{0.12}$, the orientational correlation length scales as $t^{0.54}$, and the density of defects scale as $t^{-0.45}$. The final pattern evolves toward the wavenumber where isolated dislocations become motionless, suggesting a possible wavenumber selection mechanism for large-aspect-ratio convection.Comment: 5 pages, 6 figure

Infrastructure information management of bridges at local authorities in the UK

Behind the largest infrastructure construction projects currently underway is a system of managing information known as Building Information Modelling (BIM). This represents a collaborative approach to civil engineering and makes use of advances in computer technology to link seamlessly many information repositories together across organisational boundaries. Alongside the developments in BIM, the world of asset management has also seen a major leap forward with the release of ISO 5500x – the family of international standards for asset management. This is now being adopted by many industries – particularly those in the infrastructure sectors – to maximise the value which is returned from their assets. In addition, the Highways Maintenance Efficiency Programme has released a guidance for highway authorities wishing to improve their asset management systems. However, infrastructure managers in local authorities such as county councils are significantly less engaged in both of these developments than their counterparts in strategic infrastructure networks. This paper presents the findings of a study of the ‘information system landscape’ at local authorities from across England, UK. The study reveals a number of recurring information management challenges that are frequently present. The paper finally provides a number of recommendations with specific reference to information management and encourages councils to consider adopting the standards. EPSRC/Innovate U

Heat pipe dynamic behavior

The vapor flow in a heat pipe was mathematically modeled and the equations governing the transient behavior of the core were solved numerically. The modeled vapor flow is transient, axisymmetric (or two-dimensional) compressible viscous flow in a closed chamber. The two methods of solution are described. The more promising method failed (a mixed Galerkin finite difference method) whereas a more common finite difference method was successful. Preliminary results are presented showing that multi-dimensional flows need to be treated. A model of the liquid phase of a high temperature heat pipe was developed. The model is intended to be coupled to a vapor phase model for the complete solution of the heat pipe problem. The mathematical equations are formulated consistent with physical processes while allowing a computationally efficient solution. The model simulates time dependent characteristics of concern to the liquid phase including input phase change, output heat fluxes, liquid temperatures, container temperatures, liquid velocities, and liquid pressure. Preliminary results were obtained for two heat pipe startup cases. The heat pipe studied used lithium as the working fluid and an annular wick configuration. Recommendations for implementation based on the results obtained are presented. Experimental studies were initiated using a rectangular heat pipe. Both twin beam laser holography and laser Doppler anemometry were investigated. Preliminary experiments were completed and results are reported

Analysis of margin classification systems for assessing the risk of local recurrence after soft tissue sarcoma resection

Purpose: To compare the ability of margin classification systems to determine local recurrence (LR) risk after soft tissue sarcoma (STS) resection. Methods: Two thousand two hundred seventeen patients with nonmetastatic extremity and truncal STS treated with surgical resection and multidisciplinary consideration of perioperative radiotherapy were retrospectively reviewed. Margins were coded by residual tumor (R) classification (in which microscopic tumor at inked margin defines R1), the R+1mm classification (in which microscopic tumor within 1 mm of ink defines R1), and the Toronto Margin Context Classification (TMCC; in which positive margins are separated into planned close but positive at critical structures, positive after whoops re-excision, and inadvertent positive margins). Multivariate competing risk regression models were created. Results: By R classification, LR rates at 10-year follow-up were 8%, 21%, and 44% in R0, R1, and R2, respectively. R+1mm classification resulted in increased R1 margins (726 v 278, P < .001), but led to decreased LR for R1 margins without changing R0 LR; for R0, the 10-year LR rate was 8% (range, 7% to 10%); for R1, the 10-year LR rate was 12% (10% to 15%) . The TMCC also showed various LR rates among its tiers (P < .001). LR rates for positive margins on critical structures were not different from R0 at 10 years (11% v 8%, P = .18), whereas inadvertent positive margins had high LR (5-year, 28% [95% CI, 19% to 37%]; 10-year, 35% [95% CI, 25% to 46%]; P < .001). Conclusion: The R classification identified three distinct risk levels for LR in STS. An R+1mm classification reduced LR differences between R1 and R0, suggesting that a negative but < 1-mm margin may be adequate with multidisciplinary treatment. The TMCC provides additional stratification of positive margins that may aid in surgical planning and patient education