Publications


The impact of occupancy patterns, occupant-controlled ventilation and shading on indoor overheating risk in domestic environments

BUILDING AND ENVIRONMENT 78 (2014) 183-198

A Mavrogianni, M Davies, J Taylor, Z Chalabi, P Biddulph, E Oikonomou, P Das, B Jones


The relative importance of input weather data for indoor overheating risk assessment in dwellings

BUILDING AND ENVIRONMENT 76 (2014) 81-91

J Taylor, M Davies, A Mavrogianni, Z Chalabi, P Biddulph, E Oikonomou, P Das, B Jones


Effect on plasma rotation of lower hybrid (LH) waves in Alcator C-Mod

AIP Conference Proceedings 1580 (2014) 398-401

JP Lee, M Barnes, RR Parker, JE Rice, FI Parra, PT Bonoli, ML Reinke

The injection of LH waves for current drive into a tokamak changes the ion toroidal rotation. In Alcator C-Mod, the direction of the steady state rotation change due to LH waves depends on the plasma current and the density. The change in rotation can be estimated by balancing the external torque of lower hybrid waves with the turbulent radial transport of the momentum. For high plasma current, the turbulent pinch and diffusion of the injected counter-current momentum are sufficient to explain the rotation change. However, for low plasma current, the change in the the intrinsic momentum transport (residual stress) for a non-rotating state is required to explain the co-current rotation change. Accordingly, we investigate the intrinsic momentum transport for the non-rotating state when diamagnetic flow and ExB flow cancel each other. The change in the intrinsic momentum transport due to lower hybrid waves is significant when the plasma current is low, which may explain the rotation reversal for low plasma current. The effect of changed q (safety factor) profile by lower hybrid on the intrinsic momentum transport is estimated by gyrokinetics. © 2014 AIP Publishing LLC.


Observation of a new high- β and high-density state of a magnetospheric plasma in RT-1

Physics of Plasmas 21 (2014)

H Saitoh, Y Yano, Z Yoshida, M Nishiura, J Morikawa, Y Kawazura, T Nogami, M Yamasaki

A new high-β and high-density state is reported for a plasma confined in a laboratory magnetosphere. In order to expand the parameter regime of an electron cyclotron resonance heating experiment, the 8.2 GHz microwave power of the Ring Trap 1 device has been upgraded with the installation of a new waveguide system. The rated input power launched from a klystron was increased from 25 to 50 kW, which enabled the more stable formation of a hot-electron high-β plasma. The diamagnetic signal (the averaged value of four magnetic loops signals) of a plasma reached 5.2 mWb. According to a two-dimensional Grad-Shafranov analysis, the corresponding local β value is close to 100%. © 2014 AIP Publishing LLC.


A current driven electromagnetic mode in sheared and toroidal configurations (vol 56, 035011, 2014)

PLASMA PHYSICS AND CONTROLLED FUSION 56 (2014) ARTN 129501

I Pusztai, PJ Catto, FI Parra, M Barnes


THE RELATION BETWEEN GAS DENSITY AND VELOCITY POWER SPECTRA IN GALAXY CLUSTERS: QUALITATIVE TREATMENT AND COSMOLOGICAL SIMULATIONS

ASTROPHYSICAL JOURNAL LETTERS 788 (2014) ARTN L13

I Zhuravleva, EM Churazov, AA Schekochihin, ET Lau, D Nagai, M Gaspari, SW Allen, K Nelson, IJ Parrish


The effect of bars on the M.-σ<inf>e</inf> relation: Offset, scatter and residuals correlations

Monthly Notices of the Royal Astronomical Society 441 (2014) 1243-1259

M Hartmann, VP Debattista, DR Cole, M Valluri, LM Widrow, J Shen

We analyse a set of collisionless disc galaxy simulations to study the consequences of bar formation and evolution on the M.-σe relation of supermassive black holes (SMBHs). The redistribution of angular momentum driven by bars leads to a mass increase within the central region, raising the velocity dispersion of the bulge, se, on average bỹ12 per cent and as much as ̃20 per cent. If a disc galaxy with an SMBH satisfying the M.-σe relation forms a bar, and the SMBH does not grow in the process, then the increase in se moves the galaxy off the M.-σe relation.We explore various effects that can affect this result including contamination from the disc and anisotropy. The displacement from theM.-σe relation for individual model barred galaxies correlates with both the bulge-to-total stellar mass ratio, M(B)/M(B + D), and the 2D anisotropy, βf(B + D), both measured within the effective radius of the bulge. Overall, this process leads to an M.-σe for barred galaxies offset from that of unbarred galaxies, as well as an increase in its scatter. We assemble samples of observed unbarred and barred galaxies with classical bulges and find tentative hints of an offset between the two consistent with the predicted. Including all barred galaxies, rather than just those with a classical bulge, leads to a significantly larger offset, which is mostly driven by the significantly larger offset of pseudo bulges. © 2014 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.


YOUNG STARS IN AN OLD BULGE: A NATURAL OUTCOME OF INTERNAL EVOLUTION IN THE MILKY WAY

The Astrophysical Journal 787 (2014) L19-L19

M Ness, VP Debattista, T Bensby, S Feltzing, R Roškar, DR Cole, JA Johnson, K Freeman


Models of magnetic field evolution and effective viscosity in weakly collisional extragalactic plasmas

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 440 (2014) 3226-3242

F Mogavero, AA Schekochihin


Equivalence of two independent calculations of the higher order guiding center Lagrangian

PHYSICS OF PLASMAS 21 (2014) ARTN 104506

FI Parra, I Calvo, JW Burby, J Squire, H Qin


Using probabilistic sampling-based sensitivity analyses for indoor air quality modelling

BUILDING AND ENVIRONMENT 78 (2014) 171-182

P Das, C Shrubsole, B Jones, I Hamilton, Z Chalabi, M Davies, A Mavrogianni, J Taylor


Turbulent amplification of magnetic fields in laboratory laser-produced shock waves

NATURE PHYSICS 10 (2014) 520-524

J Meinecke, HW Doyle, F Miniati, AR Bell, R Bingham, R Crowston, RP Drake, M Fatenejad, M Koenig, Y Kuramitsu, CC Kuranz, DQ Lamb, D Lee, MJ MacDonald, CD Murphy, H-S Park, A Pelka, A Ravasio, Y Sakawa, AA Schekochihin, A Scopatz, P Tzeferacos, WC Wan, NC Woolsey, R Yurchak, B Reville, G Gregori


Firehose and Mirror Instabilities in a Collisionless Shearing Plasma

PHYSICAL REVIEW LETTERS 112 (2014) ARTN 205003

MW Kunz, AA Schekochihin, JM Stone


Why stellar feedback promotes disc formation in simulated galaxies

Monthly Notices of the Royal Astronomical Society 443 (2014) 2092-2111

H Übler, T Naab, L Oser, M Aumer, LV Sales, SDM White

We study how feedback influences baryon infall on to galaxies using cosmological, zoom-in simulations of haloes with present mass Mvir = 6.9 × 1011 to 1.7 × 1012M⊙. Starting at z = 4 from identical initial conditions, implementations of weak and strong stellar feedback produce bulge- and disc-dominated galaxies, respectively. Strong feedback favours disc formation: (1) because conversion of gas into stars is suppressed at early times, as required by abundance matching arguments, resulting in flat star formation histories and higher gas fractions; (2) because 50 per cent of the stars form in situ from recycled disc gas with angular momentum only weakly related to that of the z = 0 dark halo; (3) because late-time gas accretion is typically an order of magnitude stronger and has higher specific angular momentum, with recycled gas dominating over primordial infall; (4) because 25-30 per cent of the total accreted gas is ejected entirely before z ̃ 1, removing primarily low angular momentum material which enriches the nearby intergalactic medium. Most recycled gas roughly conserves its angular momentum, but material ejected for long times and to large radii can gain significant angular momentum before re-accretion. These processes lower galaxy formation efficiency in addition to promoting disc formation. © 2014 The Authors.Published by Oxford University Press on behalf of the Royal Astronomical Society.


The diverse formation histories of simulated disc galaxies

Monthly Notices of the Royal Astronomical Society 441 (2014) 3679-3695

M Aumer, SDM White, T Naab

We analyse the formation histories of 19 galaxies from cosmological smoothed particle hydrodynamics zoom-in resimulations. We construct mock three-colour images and show that the models reproduce observed trends in the evolution of galaxy colours and morphologies. However, only a small fraction of galaxies contains bars. Many galaxies go through phases of central mass growth by in situ star formation driven by gas-rich mergers or misaligned gas infall. These events lead to accretion of low angular momentum gas to the centres and leave imprints on the distributions of z = 0 stellar circularities, radii and metallicities as functions of age. Observations of the evolution of structural properties of samples of disc galaxies at z = 2.5-0.0 infer continuous mass assembly at all radii. Our simulations can only explain this if there is a significant contribution from mergers or misaligned infall, as expected in a Λ cold dark matter universe. Quiescent merger histories lead to high kinematic disc fractions and inside-out growth, but show little central growth after the last 'destructive' merger at z > 1.5. For sufficiently strong feedback, as assumed in our models, a moderate amount of merging does not seem to be a problem for the z = 0 disc galaxy population, but may rather be a requirement. The average profiles of simulated disc galaxies agree with observations at z≥1.5. At z≤1, there is too much growth in size and too little growth in centralmass, possibly due to the underabundance of bars. The discrepancies may partly be caused by differences between the star formation histories of the simulations and those assumed for observations. © 2014 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.


Suppression of local heat flux in a turbulent magnetized intracluster medium

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 440 (2014) 1153-1164

SV Komarov, EM Churazov, AA Schekochihin, JA ZuHone


Three-dimensional extinction mapping using Gaussian random fields

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 445 (2014) 256-269

SE Sale, J Magorrian


Inboard and outboard radial electric field wells in the H- and I-mode pedestal of Alcator C-Mod and poloidal variations of impurity temperature

NUCLEAR FUSION 54 (2014) ARTN 083017

C Theiler, RM Churchill, B Lipschultz, M Landreman, DR Ernst, JW Hughes, PJ Catto, FI Parra, IH Hutchinson, ML Reinke, AE Hubbard, ES Marmar, JT Terry, JR Walk, AC-M Team


Reduction of core turbulence in I-mode plasmas in Alcator C-Mod

NUCLEAR FUSION 54 (2014) ARTN 083019

AE White, M Barnes, A Dominguez, M Greenwald, NT Howard, AE Hubbard, JW Hughes, DR Mikkelsen, FI Parra, ML Reinke, C Sung, J Walk, DG Whyte


The RAVE survey: the Galactic escape speed and the mass of the Milky Way

ASTRONOMY & ASTROPHYSICS 562 (2014) ARTN A91

T Piffl, C Scannapieco, J Binney, M Steinmetz, R-D Scholz, MEK Williams, RS de Jong, G Kordopatis, G Matijevic, O Bienayme, J Bland-Hawthorn, C Boeche, K Freeman, B Gibson, G Gilmore, EK Grebel, A Helmi, U Munari, JF Navarro, Q Parker, WA Reid, G Seabroke, F Watson, RFG Wyse, T Zwitter

Pages