1,539 research outputs found
Requirements for the workflow-based support of release management processes in the automotive sector
One of the challenges the automotive industry currently has to master is the complexity of the electrical/elctronic system of a car. One key factor for reaching short product development cycles and high quality in this area are well-defined, properly executed test and release processes. In this paper we show why workflow management technology is needed to support these processes and how this support should look like. We further confront these requirements with the features of contemporary workflow technology and discuss which extensions become necessary
Simulation System for the Wendelstein 7-X Safety Control System
The Wendelstein 7-X (W7-X) Safety Instrumented System (SIS) ensures personal
safety and investment protection. The development and implementation of the SIS
are based on the international safety standard for the process industry sector,
IEC 61511. The SIS exhibits a distributed and hierarchical organized
architecture consisting of a central Safety System (cSS) on the top and many
local Safety Systems (lSS) at the bottom. Each technical component or
diagnostic system potentially hazardous for the staff or for the device is
equipped with an lSS. The cSS is part of the central control system of W7-X.
Whereas the lSSs are responsible for the safety of each individual component,
the cSS ensures safety of the whole W7-X device. For every operation phase of
the W7-X experiment hard- and software updates for the SIS are mandatory. New
components with additional lSS functionality and additional safety signals have
to be integrated. Already established safety functions must be adapted and new
safety functions have to be integrated into the cSS. Finally, the safety
programs of the central and local safety systems have to be verified for every
development stage and validated against the safety requirement specification.
This contribution focuses on the application of a model based simulation system
for the whole SIS of W7-X. A brief introduction into the development process of
the SIS and its technical realization will be give followed by a description of
the design and implementation of the SIS simulation system using the framework
SIMIT (Siemens). Finally, first application experiences of this simulation
system for the preparation of the SIS for the upcoming operation phase OP 1.2b
of W7-X will be discussed
Creating Online Brand Value through Online Discussion Site
This paper discusses the implications of the new evolving Service-Dominant (S-D) logic in marketing on brand value creation. Furthermore, it introduces the concept of online brand value and examines whether online discussion sites constitute a means for firms to co-create, together with a firm\u27s customers, online brand value. Moreover, a conceptual framework of online discussion sites is proposed. Finally, the results of an exploratory empirical analysis of two discussion sites are presented. The findings provide initial support for the hypothesis that online discussion sites can be used to create online brand value. Moreover, the findings suggest that firm-generated discussion sites are better suited for online brand value co-creation activities than third-party generated discussion sites
Radiative corrections to the pressure and the one-loop polarization tensor of massless modes in SU(2) Yang-Mills thermodynamics
We compute the one-loop polarization tensor for the on-shell, massless
mode in a thermalized SU(2) Yang-Mills theory being in its deconfining phase.
Postulating that SU(2), we discuss
's effect on the low-momentum part of the black-body spectrum at
temperatures where K.
A table-top experiment is proposed to test the above postulate. As an
application, we point out a possible connection with the stability of dilute,
cold, and old innergalactic atomic hydrogen clouds. We also compute the
two-loop correction to the pressure arising from the instantaneous massless
mode in unitary-Coulomb gauge, which formerly was neglected, and present
improved estimates for subdominant corrections.Comment: 25 pages, 17 figs, v4: consequences of a modification of the
evolution equation for the effectice coupling implemented, no qualitative
change of the physic
Sulphur-bearing molecules in diffuse molecular clouds: new results from SOFIA/GREAT and the IRAM 30 m telescope
We have observed five sulphur-bearing molecules in foreground diffuse
molecular clouds lying along the sight-lines to five bright continuum sources.
We have used the GREAT instrument on SOFIA to observe the 1383 GHz transitions of SH towards the star-forming regions W31C,
G29.96-0.02, G34.3+0.1, W49N and W51, detecting foreground absorption towards
all five sources; and the EMIR receivers on the IRAM 30m telescope at Pico
Veleta to detect the HS 1(10)-1(01), CS J=2-1 and SO 3(2)-2(1) transitions.
In nine foreground absorption components detected towards these sources, the
inferred column densities of the four detected molecules showed relatively
constant ratios, with N(SH)/N(HS) in the range 1.1 - 3.0, N(CS)/N(HS)
in the range 0.32 - 0.61, and N(SO)/N(HS) in the range 0.08 - 0.30. The
observed SH/H ratios - in the range (0.5-2.6) - indicate
that SH (and other sulphur-bearing molecules) account for << 1% of the
gas-phase sulphur nuclei. The observed abundances of sulphur-bearing molecules,
however, greatly exceed those predicted by standard models of cold diffuse
molecular clouds, providing further evidence for the enhancement of endothermic
reaction rates by elevated temperatures or ion-neutral drift. We have
considered the observed abundance ratios in the context of shock and turbulent
dissipation region (TDR) models. Using the TDR model, we find that the
turbulent energy available at large scale in the diffuse ISM is sufficient to
explain the observed column densities of SH and CS. Standard shock and TDR
models, however, fail to reproduce the column densities of HS and SO by a
factor of about 10; more elaborate shock models - in which account is taken of
the velocity drift, relative to H, of SH molecules produced by the
dissociative recombination of HS - reduce this discrepancy to a factor
~ 3.Comment: 30 pages, accepted for publication in A&
RACE-OC Project: Rotation and variability in the open cluster M11 (NGC6705)
Rotation and magnetic activity are intimately linked in main-sequence stars
of G or later spectral types. The presence and level of magnetic activity
depend on stellar rotation, and rotation itself is strongly influenced by
strength and topology of the magnetic fields. Open clusters represent
especially useful targets to investigate the rotation/activity/age connection.
The open cluster M11 has been studied as a part of the RACE-OC project
(Rotation and ACtivity Evolution in Open Clusters), which is aimed at exploring
the evolution of rotation and magnetic activity in the late-type members of
open clusters with different ages. Photometric observations of the open cluster
M11 were carried out in June 2004 using LOAO 1m telescope. The rotation periods
of the cluster members are determined by Fourier analysis of photometric data
time series. We further investigated the relations between the surface
activity, characterized by the light curve amplitude, and rotation. We have
discovered a total of 75 periodic variables in the M11 FoV, of which 38 are
candidate cluster members. Specifically, among cluster members we discovered 6
early-type, 2 eclipsing binaries and 30 bona-fide single periodic late-type
variables. Considering the rotation periods of 16 G-type members of the almost
coeval 200-Myr M34 cluster, we could determine the rotation period distribution
from a more numerous sample of 46 single G stars at an age of about 200-230 Myr
and determine a median rotation period P=4.8d. A comparison with the younger
M35 cluster (~150 Myr) and with the older M37 cluster (~550 Myr) shows that G
stars rotate slower than younger M35 stars and faster than older M37 stars. The
measured variation of the median rotation period is consistent with the
scenario of rotational braking of main-sequence spotted stars as they age.Comment: Accepted by Astronomy and Astrophysics on Dec 15, 200
Reasons why unscreened patients with cervical cancer present with advanced stage disease
OBJECTIVE: Cervical cancer is the most common gynaecological cancer in South Africa, and the vast majority of women present with an advanced stage of the disease. This can be attributed to the absence of an implemented screening programme, resulting in patients becoming symptomatic prior to diagnosis. There are little data on the health-seeking behaviour of these women. The objective was to investigate the circumstances of patients who present with cervical cancer, as well as examine their presenting symptoms and behaviour following the onset of symptoms. DESIGN: Descriptive study. Data were collected from patients who were diagnosed with cervical cancer by means interviews and a questionnaire. SETTING AND SUBJECTS: Women diagnosed and managed with cervical cancer at the Gynaecological Oncology Unit, Kalafong Hospital, Pretoria. OUTCOMES MEASURED: Included demographic data, tumour characteristics, presenting symptoms, number of visits to and interventions performed at the primary healthcare contact. RESULTS: Eighty-five patients were recruited. Of these, 74% lived in rural areas, 81% had access to primary healthcare facilities and 83% lived close to a healthcare provider. Eight had early-stage disease. The most common presenting symptoms were vaginal bleeding, pain and vaginal discharge. After the onset of symptoms, 55% of patients visited their healthcare provider within four weeks. At the first visit, only 41% of patients had a gynaecological examination and only 15% were appropriately referred, compared to 23% at their second visit. Late presentation was significantly associated with no gynaecological examination (p-value < 0.01). CONCLUSION: The lack of a cervical cancer screening programme, suboptimal management of symptomatic patients and low levels of literacy and knowledge about cervical cancer and screening are compounding the plight of these patients.http://www.sajgo.co.za/index.php/sajgoam2013ay201
Integrability of the N=2 boundary sine-Gordon model
We construct a boundary Lagrangian for the N=2 supersymmetric sine-Gordon
model which preserves (B-type) supersymmetry and integrability to all orders in
the bulk coupling constant g. The supersymmetry constraint is expressed in
terms of matrix factorisations.Comment: LaTeX, 19 pages, no figures; v2: title changed, minor improvements,
refs added, to appear in J. Phys. A: Math. Ge
Fluctuations and the QCD phase diagram
In this contribution the role of quantum fluctuations for the QCD phase
diagram is discussed. This concerns in particular the importance of the matter
back-reaction to the gluonic sector. The impact of these fluctuations on the
location of the confinement/deconfinement and the chiral transition lines as
well as their interrelation are investigated. Consequences of our findings for
the size of a possible quarkyonic phase and location of a critical endpoint in
the phase diagram are drawn.Comment: 7 pages, 3 figures, to appear in Physics of Atomic Nucle
Limits of ultra-high-precision optical astrometry: Stellar surface structures
We investigate the astrometric effects of stellar surface structures as a
practical limitation to ultra-high-precision astrometry, e.g. in the context of
exoplanet searches, and to quantify the expected effects in different regions
of the HR-diagram. Stellar surface structures are likely to produce
fluctuations in the integrated flux and radial velocity of the star, as well as
a variation of the observed photocentre, i.e. astrometric jitter, and closure
phase. We use theoretical considerations supported by Monte Carlo simulations
to derive statistical relations between the corresponding astrometric,
photometric, and radial-velocity effects. For most stellar types the
astrometric jitter due to stellar surface structures is expected to be of order
10 micro-AU or greater. This is more than the astrometric displacement
typically caused by an Earth-size exoplanet in the habitable zone, which is
about 1-4 micro-AU for long-lived main-sequence stars. Only for stars with
extremely low photometric variability (<0.5 mmag) and low magnetic activity,
comparable to that of the Sun, will the astrometric jitter be of order 1
micro-AU, suffcient to allow the astrometric detection of an Earth-sized planet
in the habitable zone. While stellar surface structure may thus seriously
impair the astrometric detection of small exoplanets, it has in general
negligible impact on the detection of large (Jupiter-size) planets and on the
determination of stellar parallax and proper motion. From the starspot model we
also conclude that the commonly used spot filling factor is not the most
relevant parameter for quantifying the spottiness in terms of the resulting
astrometric, photometric and radial-velocity variations.Comment: 12 pages, 4 figures, submitted to A&
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