Dataset associated with 'Magnetohydrodynamic simulations of mechanical stellar feedback in a sheet-like molecular cloud'

Paper abstract: We have used the AMR hydrodynamic code, MG, to perform 3D magnetohydrodynamic simulations with self-gravity of stellar feedback in a sheet-like molecular cloud formed through the action of the thermal instability. We simulate the interaction of the mechanical energy input from a 15 solar mass star and a 40 solar mass star into a 100 parsec-diameter 17000 solar mass cloud with a corrugated sheet morphology that in projection appears filamentary. The stellar winds are introduced using appropriate Geneva stellar evolution models. In the 15 solar mass star case, the wind forms a narrow bipolar cavity with minimal effect on the parent cloud. In the 40 solar mass star case, the more powerful stellar wind creates a large cylindrical cavity through the centre of the cloud. After 12.5 million years and 4.97 million years respectively, the massive stars explode as supernovae (SNe). In the 15 solar mass star case, the SN material and energy is primarily deposited into the molecular cloud surroundings over 100,000 years before the SN remnant escapes the cloud. In the 40 solar mass star case, a significant fraction of the SN material and energy rapidly escapes the molecular cloud along the wind cavity in a few tens of kiloyears. Both SN events compress the molecular cloud material around them to higher densities (so may trigger further star formation), and strengthen the magnetic field, typically by factors of 2-3 but up to a factor of 10. Our simulations are relevant to observations of bubbles in flattened ring-like molecular clouds and bipolar HII regions. Data repository: This repository contains the raw data accompanying each figure in this publication

Numerical simulation of CO2 dispersion from punctures and ruptures of buried high-pressure dense phase CO2 pipelines with experimental validation

Carbon capture and storage (CCS) presents an option for significantly reducing the amount of carbon dioxide (CO2) released into the atmosphere and mitigating the effects of climate change. Pipelines are considered to be the most likely method for transporting captured CO2 and their safe operation is of paramount importance as their contents are likely to be in the region of several thousand tonnes and CO2 poses a number of concerns upon release due to its unusual physical properties. To this end, National Grid initiated the COOLTRANS (CO2 Liquid Pipeline Transportation) research programme to consider the pipeline transportation of high-pressure dense phase CO2. Part of this work involved the development of a mathematical model for predicting the dispersion of pure CO2 following the venting, puncture, or rupture, of such a transportation pipeline during normal operational conditions. In this paper, we describe the use of a computational fluid dynamic (CFD) tool that can be used to numerically simulate the near-field sonic dispersion from such releases, above and below ground. The model is shown to qualitatively and quantitatively reproduce observed experimental results. Validated flows at the top of the crater formed by below ground releases presented here for a range of scenarios provide the basis for developing robust source conditions for use in CFD studies of far-field dispersion, and for use with pragmatic quantified risk assessment (QRA) models

High pressure CO2 CCS pipelines: Comparing dispersion models with multiple experimental datasets

Carbon capture and storage (CCS) presents the short-term option for significantly reducing the amount of carbon dioxide (CO2) released into the atmosphere from the combustion of fossil fuels, thereby mitigating the effects of climate change. Enabling CCS requires the development of capture, storage and transport methodologies. The safe transport of CO2 in CCS scenarios can be achieved through pipelines or by shipping. Either way, transport and temporary storage of pressurised liquid CO2 will be required and subject to quantitative risk assessment, which includes the consideration of the low-risk, low-probability puncture or rupture scenario of such a pipeline, ship or storage facility. In this work, we combine multiple experimental datasets all concerned with the atmospheric free release of pure and impure liquid CO2 from CCS-transport-chain-relevant high pressure reservoirs and perform the first multiple dataset comparison to numerical models for both pure and impure jets in dry ambient air with no water vapour. The results validate the numerical approach adopted and for the prediction of such releases, highlight the significance of the mixture fraction at the release point, over the mixture composition itself. A new method for impure CO2 dispersion modelling is introduced and limited preliminary comparisons of impure CO2 data and predictions are performed. No clear difference between pure and impure releases is found for the cases considered

Modelling ruptures of buried high pressure dense phase CO2 pipelines in carbon capture and storage applications - Part I. Validation

Carbon dioxide (CO2) capture and storage presents a short-term option for significantly reducing the amount of CO2 released into the atmosphere and mitigating the effects of climate change. To this end, National Grid initiated the COOLTRANS research programme to consider the pipeline transportation of high pressure dense phase CO2, including the development and application of a mathematical model for predicting the sonic near-field dispersion of pure CO2 following the venting or failure of such a pipeline. Here, the application of this model to the rupture of a buried pipeline is considered and compared to experimental data obtained through the COOLTRANS programme. The rupture experiment was performed on a 230 m length of 152 mm external diameter pipeline with 300 mm soil cover, equivalent to approximately 1/4 scale when compared to the proposed full-scale 600 mm (24-inch) diameter pipelines with 1.2 m soil cover on average proposed in the UK. The experiment was performed in a pre-formed crater based on experimentally formed craters in other experiments. The comparison demonstrates reasonable quantitative and qualitative agreement. Such validated dispersion flow, to be applied to full-scale rupture modelling in Part II, defines novel, robust, thermodynamically accurate multi-phase source conditions, that enable far-field computational fluid dynamics studies and feed into pragmatic quantified risk assessment models

New candidate planetary nebulae in the IPHAS survey : The case of planetary nebulae with ISM interaction

Copyright © Astronomical Society of Australia 2010We present the results of the search for candidate Planetary Nebulae interacting with the interstellar medium (PNISM) in the framework of the INT Photometric H Survey (IPHAS) and located in the right ascension range 1820 h. The detection capability of this new Northern survey, in terms of depth and imaging resolution, has allowed us to overcome the detection problem generally associated to the low surface brightness inherent to PNe-ISM. We discuss the detection of 21 IPHAS PNISM candidates. Thus, different stages of interaction were observed, implying various morphologies i.e. from the unaffected to totally disrupted shapes. The majority of the sources belong to the so-called WZO2 stage which main characteristic is a brightening of the nebula's shell in the direction of motion. The new findings are encouraging as they would be a first step into the reduction of the scarcity of observational data and they would provide new insights into the physical processes occurring in the rather evolved PNe.Peer reviewe

Validation of three rapid screening methods for detection of verotoxin-producing Escherichia coli in foods:interlaboratory study

An interlaboratory study was conducted for the validation of 3 methods for the detection of all verotoxin-producing Escherichia coli (VTEC) in foods. The methods were a multi-analyte 1-step lateral flow immunoassay (LFIA) for detection of E. coli O157 and verotoxin (VT); an enzyme-linked immunosorbent assay targeted against VT1, VT2, and VT2c (VT-ELISA); and a polymerase chain reaction (PCR) method for detection of VT genes (VT-PCR). Aliquots (25 g or 25 mL) of 4 food types (raw minced [ground] beef, unpasteurized milk, unpasteurized apple juice [cider], and salami) were individually inoculated with low numbers (<9 to 375 cells/25 g) of 6 test strains of E. coli (serogroups O26, O103, O111, O145, and O157) with differing VT-producing capabilities. Five replicates for each test strain and 5 uninoculated samples were prepared for each food type. Fourteen participating laboratories analyzed samples using the LFIA, 9 analyzed the samples by ELISA, and 9 by PCR. The LFIA for O157 and VT had a specificity (correct identification of negative samples) of 92 and 94%, respectively, and a sensitivity (correct identification of positive samples) of 94 and 55%, respectively. The VT-ELISA and VT-PCR had a specificity of 98 and 99%, respectively, and a sensitivity of 89 and 72%, respectively