Generic composite flywheel designs

Fiber reinforced composites belong to a new class of materials and allow great flexibility in flywheel design. The most efficient flywheel may no longer have the classic Stodola taper and indeed, may not even be round. Some of the flywheel designs that have been developed in the past are discussed. Although choice of material, mounts and service requirements often dictate the final design choice for a particular application, the composite flywheels in this paper are classified within a geometric framework, a simple stress analysis of a circular disk is carried out

A representative sample of Be Stars I: Sample Selection, Spectral Classification and Rotational Velocities

We present a sample of 58 Be stars containing objects of spectral types O9 to B8.5 and luminosity classes III to V. We have obtained 3670 - 5070 Angstrom spectra of the sample which are used to derive spectral types and rotational velocities. We discuss the distribution of spectral types and rotational velocities obtained and conclude that there are no significant selection effects in our sample.Comment: 10 Pages, 9 Figures, Accepted for publication in A&A

Condition monitoring and prognostic indicators for network reliability

Large-scale investment in transmission and distribution networks are planned over the next 10-15 years to meet future demand and changes in power generation. However, it is important that existing assets continue to operate reliably and their health maintained. A research project is considering the increased use of simulation models that could provide accurate prognostics, targeting maintenance and reduce in service failures. Such models could be further refined with parameters obtained from on-line measurements at the asset. It is also important to consider the future development of the research agenda for condition monitoring of power networks and with colleagues from National Grid, PPA Energy and the Universities of Manchester and Strathclyde, the research team are preparing a Position Paper on this subject

Novel Rubidium Poly-Nitrogen Materials at High Pressure

First-principles crystal structure search is performed to predict novel rubidium poly-nitrogen materials at high pressure by varying the stoichiometry, i. e. relative quantities of the constituent rubidium and nitrogen atoms. Three compounds of high nitrogen content, RbN_{5}, RbN_{2}, and Rb_{4}N_{6}, are discovered. Rubidium pentazolate (RbN5) becomes thermodynamically stable at pressures above \unit[30]{GPa}. The charge transfer from Rb to N atoms enables aromaticity in cyclo-N_{^{_{5}}}^{-} while increasing the ionic bonding in the crystal. Rubidium pentazolate can be synthesized by compressing rubidium azide (RbN3) and nitrogen (N2) precursors above \unit[9.42]{GPa}, and its experimental discovery is aided by calculating the Raman spectrum and identifying the features attributed to N_{^{_{5}}}^{-} modes. The two other interesting compounds, RbN2 containing infinitely-long single-bonded nitrogen chains, and Rb_{4}N_{6} consisting of single-bonded N_{6} hexazine rings, become thermodynamically stable at pressures exceeding \unit[60]{GPa}. In addition to the compounds with high nitrogen content, Rb_{3}N_{3}, a new compound with 1:1 RbN stoichiometry containing bent N_{3} azides is found to exist at high pressures

Transferable neural networks for enhanced sampling of protein dynamics

Variational auto-encoder frameworks have demonstrated success in reducing complex nonlinear dynamics in molecular simulation to a single non-linear embedding. In this work, we illustrate how this non-linear latent embedding can be used as a collective variable for enhanced sampling, and present a simple modification that allows us to rapidly perform sampling in multiple related systems. We first demonstrate our method is able to describe the effects of force field changes in capped alanine dipeptide after learning a model using AMBER99. We further provide a simple extension to variational dynamics encoders that allows the model to be trained in a more efficient manner on larger systems by encoding the outputs of a linear transformation using time-structure based independent component analysis (tICA). Using this technique, we show how such a model trained for one protein, the WW domain, can efficiently be transferred to perform enhanced sampling on a related mutant protein, the GTT mutation. This method shows promise for its ability to rapidly sample related systems using a single transferable collective variable and is generally applicable to sets of related simulations, enabling us to probe the effects of variation in increasingly large systems of biophysical interest.Comment: 20 pages, 10 figure

Calculating the inherent visual structure of a landscape (inherent viewshed) using high-throughput computing

This paper describes a method of calculating the inherent visibility at all locations in a landscape (‘total viewshed’) by making use of redundant computer cycles. This approach uses a simplified viewshed program that is suitable for use within a distributed environment, in this case managed by the Condor system. Distributing the calculation in this way reduced the calculation time of our example from an estimated 34 days to slightly over 25 hours using a cluster of 43 workstations. Finally, we discuss the example ‘total viewshed’ raster for the Avebury region, and briefly highlight some of its implications

Water ice clouds in a martian global climate model using data assimilation

The water cycle is one of the key seasonal cycles on Mars, and the radiative effects of water ice clouds have recently been shown to alter the thermal structure of the atmosphere. Current Mars General Circulation Models (MGCMs) are capable of representing the formation and evolution of water ice clouds, though there are still many unanswered questions regarding their effect on the water cycle, the local atmosphere and the global circulation. We discuss the properties of clouds in the LMD/UK MGCM and compare them with observations, focusing on the differences between the water ice clouds in a standalone model and those in a model which has been modified by assimilation of thermal and aerosol opacity spacecraft data