2,750 research outputs found
Methane cracking over cobalt molybdenum carbides
The catalytic behaviour of Co3Mo3C, Co6Mo6C, Co3Mo3N and Co6Mo6N for methane cracking has been studied to determine the relationship between the methane cracking activity and the chemical composition. The characterisation of post-reaction samples showed a complex phase composition with the presence of Co3Mo3C, α-Co and β-Mo2C as catalytic phases and the deposition of different forms of carbon during reaction
Creative Citizenship – two journeys, one destination
This paper is a representation of a live, audio-visual keynote address given at the Creative Citizens Conference in London (September 2014), co-presented by Hargreaves (IH) and Hartley (JH). It seeks to combine (i) autobiographical narrative storytelling – two of them, in fact; with (ii) an attempt to build concepts, themes and strategies out of that narrative, and how the two stories did indeed arrive at ‘one destination’; and (iii) plentiful use of visual prompts, combined with part-scripted, part-improvised dialogic commentary. This approach was risky on the day; it is even harder to render into two dimensions, not least because a vital element, the audience, cannot be represented in that format. Nevertheless, we offer the ‘paper’ as a record of how two intersecting lives and careers were both drawn to the ‘Creative Citizens’ idea, not only as a research problem but also as a component of the speakers’ own practice – one as a high profile journalist turned academic; the other as an academic with interests in alternative models of journalism. We think that our bio-trajectories are relevant to the way that the research project led by Hargreaves has been tackled
A Dynamical Fossil in the Ursa Minor Dwarf Spheroidal Galaxy
The nearby Ursa Minor dwarf spheroidal (UMi dSph) is one of the most dark
matter dominated galaxies known, with a central mass to light ratio roughly
equal to 70. Somewhat anomalously, it appears to contain morphological
substructure in the form of a second peak in the stellar number density. It is
often argued that this substructure must be transient because it could not
survive for the > 10 Gyr age of the system, given the crossing time implied by
UMi's 8.8 km/s internal velocity dispersion. In this paper, however, we present
evidence that the substructure has a cold kinematical signature, and argue that
UMi's clumpiness could indeed be a primordial artefact. Using numerical
simulations, we demonstrate that substructure is incompatible with the cusped
dark matter haloes predicted by the prevailing Cold Dark Matter (CDM) paradigm,
but is consistent with an unbound stellar cluster sloshing back and forth
within the nearly harmonic potential of a cored dark matter halo. Thus CDM
appears to disagree with observation at the least massive, most dark matter
dominated end of the galaxy mass spectrum.Comment: Astrophysical Journal (Letters), in pres
Reconciling Gaussian plume and Computational Fluid Dynamics models of particulate dispersion
Computational Fluid Dynamics (CFD) is increasingly used to model particulate dispersion in situations where Gaussian Dispersion models are inappropriate or inaccurate. However, there is evidence which indicates that many CFD models under-predict lateral plume spread. This paper aims to address this by imple- menting a strategy which incorporates wind direction variability into CFD models using a formulation which is also used in the UK-ADMS plume spread module. In the present work, a series of CFD simulations are run at various wind angles. The outputs from these simulations are weighted using a Gaussian probability density function and combined to produce a plume. The standard k−ε model has been employed to solve the RANS equations of the flow field for stable, neutral and unstable atmospheric stabilities, coupled with the Lagrangian Particle tracking model to model dispersion. By comparing the CFD accretion profiles to UK-ADMS dry deposition results, it is observed that the proposed modelling methodology produces lateral spreading of the plume which is comparable to that obtained using UK-ADMS. However, the Lagrangian integral time scale constant, c L , which governs the influence turbulence has on the dispersion, must also be modified to bring absolute values of accretion rates in line with those observed in UK-ADMS
First Clear Signature of an Extended Dark Matter Halo in the Draco Dwarf Spheroidal
We present the first clear evidence for an extended dark matter halo in the
Draco dwarf spheroidal galaxy based on a sample of new radial velocities for
159 giant stars out to large projected radii. Using a two parameter family of
halo models spanning a range of density profiles and velocity anisotropies, we
are able to rule out (at about the 2.5 sigma confidence level) haloes in which
mass follows light. The data strongly favor models in which the dark matter is
significantly more extended than the visible dwarf. However, haloes with
harmonic cores larger than the light distribution are also excluded. When
combined with existing measurements of the proper motion of Draco, our data
strongly suggest that Draco has not been tidally truncated within ~1 kpc. We
also show that the rising velocity dispersion at large radii represents a
serious problem for modified gravity (MOND).Comment: to be published in ApJL; 5 pages, 4 figure
Validation of Computational Models of Auxiliary Ventilation Systems with Experimental Data
This paper reports the interim findings of a research program whose objective is to determine whether Computational Fluid Dynamic (CFD) models can be employed to accurately predict the airflow patterns within rapid development headings. In particular, the project aims to investigate the optimum set back distances for the ducts in order to adequately ventilate the face of the drivage. To validate the accuracy of the CFD model simulations measurements were obtained from a series of experiments performed on both scale models and within a full-scale surface gallery. The experimental scale-modeling program included making a series of pressure measurements across the face of the model for equivalent forcing duct setback distances of 5, 10 and 15 m (16, 33 and 50 ft). This pressure data was then plotted as contour plots and compared with the corresponding CFD predictions. A series of full-scale auxiliary ventilation trials were performed within a modified surface gallery. Three-dimensional velocity measurements were taken across a number of cross-sections using an ultrasonic anemometer. Velocity measurements were obtained for three forcing duct setback distances and for a typical force-exhaust overlap configuration
An Expansion Term In Hamilton's Equations
For any given spacetime the choice of time coordinate is undetermined. A
particular choice is the absolute time associated with a preferred vector
field. Using the absolute time Hamilton's equations are
+ (\delta H_{c})/(\delta \pi)=\dot{q}\Theta = V^{a}_{.;a}N\equiv exp(-\int\Theta d \ta)\pi^{N}\pi^N$. Briefly the possibility of a non-standard sympletic form
and the further possibility of there being a non-zero Finsler curvature
corresponding to this are looked at.Comment: 10 page
TE INTEGRATION OF WATER HYDRODYNAMICS MODELLING AND REMOTE SENSING DATA TO IMPROVE THE WATER CIRCULATION OF LAKE MANZALA, EGYPT
This paper presents the preliminary results of the application of the ocean model (FVCOM) to replicate the hydrodynamic flows experienced within Lake El-Manzala, Egypt. The construction of this model is used to characterize the ecosystem of this shallow brackish lake and assess a range of sustainable water management strategies. Lake El-Manzala is the largest of the Egyptian shallow coastal lakes on the fringe of the Mediterranean Sea. The lake currently supports 30% of the fresh water fish farm production of Egypt. In recent years the aquatic health of the lake has significantly deteriorated due to an increase in the contamination of the lake by polluted inflows and over intensive aquaculture. The focus of this study is to develop a model that may be employed to investigate the causes, effects and potential solutions to the pollutant loads imposed on the lake. The model has been used to study the hydrodynamic effect that a 40% reduction in the polluted drain water inflows to the lake due to a diversion of this water towards the Sinai for land development. This study concluded that in the western zone of the lake this action slightly changed the magnitude and direction of the water flows and an increase in the salinity levels. Several other lake management scenarios were proposed and the environmental effects on the lake water quality are under investigation. It is concluded that the hydrodynamic models developed may be used to study the cause and effects of other aquatic pollution problems and permit the investigation of potential engineering solutions to improve water quality management
A feasibility, randomised controlled trial of a complex breathlessness intervention in idiopathic pulmonary fibrosis (BREEZE-IPF): study protocol
Introduction Idiopathic pulmonary fibrosis (IPF) is a chronic and progressive lung disease that causes breathlessness and cough that worsen over time, limiting daily activities and negatively impacting quality of life. Although treatments are now available that slow the rate of lung function decline, trials of these treatments have failed to show improvement in symptoms or quality of life. There is an immediate unmet need for evidenced-based interventions that improve patients' symptom burden and make a difference to everyday living. This study aims to assess the feasibility of conducting a definitive randomised controlled trial of a holistic, complex breathlessness intervention in people with IPF.
Methods and analysis The trial is a two-centre, randomised controlled feasibility trial of a complex breathlessness intervention compared with usual care in patients with IPF. 50 participants will be recruited from secondary care IPF clinics and randomised 1:1 to either start the intervention within 1 week of randomisation (fast-track group) or to receive usual care for 8 weeks before receiving the intervention (wait-list group). Participants will remain in the study for a total of 16 weeks. Outcome measures will be feasibility outcomes, including recruitment, retention, acceptability and fidelity of the intervention. Clinical outcomes will be measured to inform outcome selection and sample size calculation for a definitive trial.
Ethics and dissemination Yorkshire and The Humber – Bradford Leeds Research Ethics Committee approved the study protocol (REC 18/YH/0147). Results of the main trial and all secondary end-points will be submitted for publication in a peer-reviewed journal
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