1,492 research outputs found
Thermal expansion within a chain of magnetic colloidal particles
We study the thermal expansion of chains formed by self-assembly of magnetic
colloidal particles in a magnetic field. Using video-microscopy, complete
positional data of all the particles of the chains is obtained. By changing the
ionic strength of the solution and the applied magnetic field, the interaction
potential can be tuned. We analyze the thermal expansion of the chain using a
simple model of a one dimensional anharmonic crystal of finite size.Comment: 5 pages and 3 figure
Antifreeze in the hot core of Orion - First detection of ethylene glycol in Orion-KL
Comparison of their chemical compositions shows, to first order, a good
agreement between the cometary and interstellar abundances. However, a complex
O-bearing organic molecule, ethylene glycol (CHOH), seems to depart
from this correlation because it was not easily detected in the interstellar
medium although it proved to be rather abundant with respect to other O-bearing
species in comet Hale-Bopp. Ethylene glycol thus appears, together with the
related molecules glycolaldehyde CHOHCHO and ethanol CHCHOH,
as a key species in the comparison of interstellar and cometary ices as well as
in any discussion on the formation of cometary matter. We focus here on the
analysis of ethylene glycol in the nearest and best studied hot core-like
region, Orion-KL. We use ALMA interferometric data because high spatial
resolution observations allow us to reduce the line confusion problem with
respect to single-dish observations since different molecules are expected to
exhibit different spatial distributions. Furthermore, a large spectral
bandwidth is needed because many individual transitions are required to
securely detect large organic molecules. Confusion and continuum subtraction
are major issues and have been handled with care. We have detected the aGg'
conformer of ethylene glycol in Orion-KL. The emission is compact and peaks
towards the Hot Core close to the main continuum peak, about 2" to the
south-west; this distribution is notably different from other O-bearing
species. Assuming optically thin lines and local thermodynamic equilibrium, we
derive a rotational temperature of 145 K and a column density of 4.6 10
cm. The limit on the column density of the gGg' conformer is five times
lower.Comment: 19 pages, 10 figures, A&A accepte
HCOOCH3 as a probe of temperature and structure of Orion-KL
We studied the O-bearing molecule HCOOCH3 to characterize the physical
conditions of the different molecular source components in Orion-KL. We
identify 28 methyl formate emission peaks throughout the 50" field of
observations. The two strongest peaks are in the Compact Ridge (MF1) and in the
SouthWest of the Hot Core (MF2). Spectral confusion is still prevailing as half
of the expected transitions are blended over the region. Assuming that the
transitions are thermalized, we derive the temperature at the five main
emission peaks. At the MF1 position we find a temperature of 80K in a 1.8"x0.8"
beam size and 120K on a larger scale (3.6" x2.2"), suggesting an external
source of heating, whereas the temperature is about 130K at the MF2 position on
both scales. Transitions of HCOOCH3 in vt=1 are detected as well and the good
agreement of the positions on the rotational diagrams between the vt=0 and the
vt=1 transitions suggests a similar temperature. The velocity of the gas is
between 7.5 and 8.0km/s depending on the positions and column density peaks
vary from 1.6x10^16 to 1.6x10^17cm^-2. A second velocity component is observed
around 9-10 km/s in a North-South structure stretching from the Compact Ridge
up to the BN object; this component is warmer at the MF1 peak. The two other
C2H4O2 isomers are not detected and the derived upper limit for the column
density is <3x10^14cm^-2 for glycolaldehyde and <2x10^15cm^-2 for acetic acid.
From the 223GHz continuum map, we identify several dust clumps with associated
gas masses in the range 0.8 to 5.8Msun. Assuming that the HCOOCH3 is spatially
distributed as the dust, we find relative abundances of HCOOCH3 in the range
<0.1x10^-8 to 5.2x10^-8. We suggest a relation between the methyl formate
distribution and shocks as traced by 2.12 mum H2 emission.Comment: Accepted for publication in A&
Crowdsourcing User-Contributed Solutions to Aerospace Product Development Issues through Micro-Blogging
Revenue and production output of the United Kingdom’s Aerospace Industry (AI) is growing year on year and the need to develop new products and innovative enhancements to existing ranges is creating a critical need for the increased utilisation and sharing of employee knowledge. The capture of employee knowledge within the UK’s AI is vital if it is to retain its pre-eminent position in the global marketplace. Crowdsourcing, as a collaborative problem solving activity, allows employees to capture explicit knowledge from colleagues and teams and also offers the potential to extract previously unknown tacit knowledge in a less formal virtual environment. By using micro-blogging as a mechanism, a conceptual framework is proposed to illustrate how companies operating in the AI may improve the capture of employee knowledge to address production-related problems through the use of crowdsourcing. Subsequently, the framework has been set against the background of the product development process proposed by Maylor in 1996 and illustrates how micro-blogging may be used to crowdsource ideas and solutions during product development. Initial validation of the proposed framework is reported, using a focus group of 10 key actors from the collaborating organisation, identifying the perceived advantages, disadvantages and concerns of the framework; results indicate that the activity of micro-blogging for crowdsourcing knowledge relating to product development issues would be most beneficial during product conceptualisation due to the requirement for successful innovation
A business process modelling approach to improve OEM and supplier collaboration
Nowadays, Small and Medium sized Enterprises (SMEs) are facing fast changes in technological advancement. These changes encourage them to be more innovative and to offer their Original Equipment Manufacturers (OEMs) quality products with ever shorter deadlines, which is not an easy task. This project (BENEFITS) aims to provide innovative solutions to keep the most exploitable SME’s skills within its local regions. This paper focuses on Business Process Modeling (BPM) and process interactions during the development phases of innovative products. Due to the specific needs and requirements in terms of Product Lifecycle Management (PLM)-based solutions for SMEs and OEMs, this work explores the relationship between them and their suppliers, based on ICT technologies and focuses on SMEs adoption of PLM. Such relationship needs the Business Process Modeling and Notation (BPMN) for representing all tasks that must be done for the collaborative process planning. Two existing information models (NIST and PPRO) serve as an information model to investigate the way of implementing design processes in the context of PLM
Full-Polarization Observations of OH Masers in Massive Star-Forming Regions: I. Data
We present full-polarization VLBA maps of the ground-state, main-line, 2 Pi
3/2, J = 3/2 OH masers in 18 Galactic massive star-forming regions. This is the
first large polarization survey of interstellar hydroxyl masers at VLBI
resolution. A total of 184 Zeeman pairs are identified, and the corresponding
magnetic field strengths are indicated. We also present spectra of the NH3
emission or absorption in these star-forming regions. Analysis of these data
will be presented in a companion paper.Comment: 111 pages, including 42 figures and 21 tables, to appear in ApJ
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