41,557 research outputs found
Visualization of steps and surface reconstructions in Helium Ion Microscopy with atomic precision
Helium Ion Microscopy is known for its surface sensitivity and high lateral
resolution. Here, we present results of a Helium Ion Microscopy based
investigation of a surface confined alloy of Ag on Pt(111). Based on a change
of the work function of 25\,meV across the atomically flat terraces we can
distinguish Pt rich from Pt poor areas and visualize the single atomic layer
high steps between the terraces. Furthermore, dechanneling contrast has been
utilized to measure the periodicity of the hcp/fcc pattern formed in the 2--3
layers thick Ag/Pt alloy film. A periodicity of 6.65\,nm along the
surface direction has been measured. In terms of
crystallography a hcp domain is obtained through a lateral displacement of a
part of the outermost layer by of a nearest neighbour spacing
along . This periodicity is measured with atomic
precision: coincidence between the Ag and the Pt lattices is observed for 23 Ag
atoms on 24 Pt atoms. The findings are perfectly in line with results obtained
with Low Energy Electron Microscopy and Phase Contrast Atomic Force Microscopy.Comment: 15 pages, 7 figure
Consumers’ Acceptance of a Bio-circular Automotive Economy: Explanatory Model and Influence Factors
Sustainability in the automotive sector and appropriate end-of-life (EOL) management options for car tyres are important and constitute global issues. There is currently an oversupply of EOL tyres and the potential of circular economy (CE) tyres and for bio-based (BB) tyres warrants further investigation. Likewise, BB and CE tyres might be an interesting approach to improve the overall sustainability of the tyre life cycle. Research on drivers for the acceptance of CE and BB tyres is currently missing. In 1989, a socio-economy model was created to understand the acceptance of various products. This model is still popular in many areas but does not address sustainability questions of the 21st century appropriately. This article aims to provide a better understanding of the factors which drive acceptance of sustainable tyres. It presents an acceptance model and related influence factors in three areas: variables related to the consumers, perceived product characteristics and stimulating moderator variables. The third aspect refers in particular to labels and certification influencing consumer views on existing product characteristics. This article ends by discussing how availability of such labels could be promoted through eco-labelling of tyres and related standardization, addressing the industry and policy makers to make the automotive sector more sustainable.BMBF, 033R236E, ReziProK - Verbundvorhaben: ConCirMy - Entwicklung eines stufen- und kreislaufübergreifend vernetzten Konfigurators zur Gewährleistung geschlossener Material- und Komponentenflüsse im Rahmen der zirkulären Ökonomie, Teilvorhaben 4: Sozioökonomische Analysen und GeschäftsmodelleDFG, 414044773, Open Access Publizieren 2019 - 2020 / Technische Universität Berli
The Dark Energy Survey Data Management System
The Dark Energy Survey collaboration will study cosmic acceleration with a
5000 deg2 griZY survey in the southern sky over 525 nights from 2011-2016. The
DES data management (DESDM) system will be used to process and archive these
data and the resulting science ready data products. The DESDM system consists
of an integrated archive, a processing framework, an ensemble of astronomy
codes and a data access framework. We are developing the DESDM system for
operation in the high performance computing (HPC) environments at NCSA and
Fermilab. Operating the DESDM system in an HPC environment offers both speed
and flexibility. We will employ it for our regular nightly processing needs,
and for more compute-intensive tasks such as large scale image coaddition
campaigns, extraction of weak lensing shear from the full survey dataset, and
massive seasonal reprocessing of the DES data. Data products will be available
to the Collaboration and later to the public through a virtual-observatory
compatible web portal. Our approach leverages investments in publicly available
HPC systems, greatly reducing hardware and maintenance costs to the project,
which must deploy and maintain only the storage, database platforms and
orchestration and web portal nodes that are specific to DESDM. In Fall 2007, we
tested the current DESDM system on both simulated and real survey data. We used
Teragrid to process 10 simulated DES nights (3TB of raw data), ingesting and
calibrating approximately 250 million objects into the DES Archive database. We
also used DESDM to process and calibrate over 50 nights of survey data acquired
with the Mosaic2 camera. Comparison to truth tables in the case of the
simulated data and internal crosschecks in the case of the real data indicate
that astrometric and photometric data quality is excellent.Comment: To be published in the proceedings of the SPIE conference on
Astronomical Instrumentation (held in Marseille in June 2008). This preprint
is made available with the permission of SPIE. Further information together
with preprint containing full quality images is available at
http://desweb.cosmology.uiuc.edu/wik
Managing community membership information in a small-world grid
As the Grid matures the problem of resource discovery across communities,
where resources now include computational services, is becoming more
critical. The number of resources available on a world-wide grid is set to grow
exponentially in much the same way as the number of static web pages on
the WWW. We observe that the world-wide resource discovery problem can
be modelled as a slowly evolving very-large sparse-matrix where individual
matrix elements represent nodes’ knowledge of one another. Blocks in the
matrix arise where nodes offer more than one service. Blocking effects also
arise in the identification of sub-communities in the Grid. The linear algebra
community has long been aware of suitable representations of large, sparse
matrices. However, matrices the size of the world-wide grid potentially number
in the billions, making dense solutions completely intractable. Distributed
nodes will not necessarily have the storage capacity to store the addresses of
any significant percentage of the available resources. We discuss ways of modelling
this problem in the regime of a slowly changing service base including
phenomena such as percolating networks and small-world network effects
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