498 research outputs found
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
System and market failures: the unavailability of magnesium sulphate for the treatment of eclampsia and pre-eclampsia in Mozambique and Zimbabwe.
Low cost and effective drugs, such as magnesium sulphate, need to be included in initiatives to improve access to essential medicines in Afric
Visuelle Detektion unabhängig bewegter Objekte durch einen bewegten monokularen Beobachter
The development of a driver assistant system supporting drivers in complex intersection situations would be a major achievement for traffic safety, since many traffic accidents happen in such situations. While this is a highly complex task, which is still not accomplished, this thesis focused on one important and obligatory aspect of such systems: The visual detection of independently moving objects. Information about moving objects can, for example, be used in an attention guidance system, which is a central component of any complete intersection assistant system. The decision to base such a system on visual input had two reasons: (i) Humans gather their information to a large extent visually and (ii) cameras are inexpensive and already widely used in luxury and professional vehicles for specific applications. Mimicking the articulated human head and eyes, agile camera systems are desirable. To avoid heavy and sensitive stereo rigs, a small and lightweight monocular camera system mounted on a pan-tilt unit has been chosen as input device. In this thesis information about moving objects has been used to develop a prototype of an attention guidance system. It is based on the analysis of sequences from a single freely moving camera and on measurements from inertial sensors rigidly coupled with the camera system.Die Entwicklung eines Fahrerassistenzsystems, welches den Fahrer in komplexen Kreuzungssituationen unterstützt, wäre ein wichtiger Beitrag zur Verkehrssicherheit, da sehr viele Unfälle in solchen Situationen passieren. Dies ist eine hochgradig komplexe Aufgabe und daher liegt der Fokus dieser Arbeit auf einen wichtigen und notwendigen Aspekt solcher Systeme: Die visuelle Detektion unabhängig bewegter Objekte. Informationen über bewegte Objekte können z.B. für ein System zur Aufmerksamkeitssteuerung verwendet werden. Solch ein System ist ein integraler Bestandteil eines jeden kompletten Kreuzungsassistenzssystems. Zwei Gründe haben zu der Entscheidung geführt, das System auf visuellen Daten zu stützen: (i) Der Mensch sammelt seine Informationen zum Großteil visuell und (ii) Kameras sind zum Einen günstig und zum Anderen bereits jetzt in vielen Fahrzeugen verfügbar. Agile Kamerasysteme sind nötig um den beweglichen menschlichen Kopf zu imitieren. Die Wahl einer kleinen und leichten monokularen Kamera, die auf einer Schwenk-Neige-Einheit montiert ist, vermeidet die Verwendung von schweren und empfindlichen Stereokamerasystemen. Mit den Informationen über bewegte Objekte ist in dieser Arbeit der Prototyp eines Fahrerassistenzsystems Aufmerksamkeitssteuerung entwickelt worden. Das System basiert auf der Analyse von Bildsequenzen einer frei bewegten Kamera und auf Messungen von der mit der Kamera starr gekoppelten Inertialsensorik
EUVE J0425.6-5714: A Newly Discovered AM Herculis Star
We detected a new AM Her star serendipitously in a 25 day observation with
the EUVE satellite. A coherent period of 85.82 min is present in the EUVE Deep
Survey imager light curve of this source. A spectroscopic identification is
made with a 19th magnitude blue star that has H and He emission lines, and
broad cyclotron humps typical of a magnetic cataclysmic variable. A lower limit
to the polar magnetic field of 46 MG is estimated from the spacing of the
cyclotron harmonics. EUVE J0425.6-5714 is also detected in archival ROSAT HRI
observations spanning two months, and its stable and highly structured light
curve permits us to fit a coherent ephemeris linking the ROSAT and EUVE data
over a 1.3 yr gap. The derived period is 85.82107 +/- 0.00020 min, and the
ephemeris should be accurate to 0.1 cycles until the year 2005. A narrow but
partial X-ray eclipse suggests that this object belongs to the group of Am Her
stars whose viewing geometry is such that the accretion stream periodically
occults the soft X-ray emitting accretion spot on the surface of the white
dwarf. A non-detection of hard X-rays from ASCA observations that are
contemporaneous with the ROSAT HRI shows that the soft X-rays must dominate by
at least an order of magnitude, which is consistent with a known trend among AM
Her stars with large magnetic field. This object should not be confused with
the Seyfert galaxy 1H 0419-577 (= LB 1727), another X-ray/EUV source which lies
only 4' away, and was the principal target of these monitoring observations.Comment: 13 pages, 5 figures, to appear in PASP, Dec. 1998 issu
GALEX, Optical and IR Light Curves of MQ Dra: UV Excesses at Low Accretion Rates
Ultraviolet light curves constructed from NUV and FUV detectors on GALEX
reveal large amplitude variations during the orbital period of the Low
Accretion Rate Polar MQ Dra (SDSSJ1553+55). This unexpected variation from a UV
source is similar to that seen and discussed in the Polar EF Eri during its low
state of accretion, even though the accretion rate in MQ Dra is an order of
magnitude lower than even the low state of EF Eri. The similarity in phasing of
the UV and optical light curves in MQ Dra imply a similar location for the
source of light. We explore the possibilities of hot spots and cyclotron
emission with simple models fit to the UV, optical and IR light curves of MQ
Dra. To match the GALEX light curves with a single temperature circular hot
spot requires different sizes of spots for the NUV and FUV, while a cyclotron
model that can produce the optical harmonics with a magnetic field near 60 MG
requires multipoles with fields > 200 MG to match the UV fluxes.Comment: accepted for ApJ; 15 pages, 7 tables, 8 fig
New Low Accretion-Rate Magnetic Binary Systems and their Significance for the Evolution of Cataclysmic Variables
Discoveries of two new white dwarf plus M star binaries with striking optical
cyclotron emission features from the Sloan Digital Sky Survey (SDSS) brings to
six the total number of X-ray faint, magnetic accretion binaries that accrete
at rates < 10^{-13} Msun/yr, or <1% of the values normally encountered in
cataclysmic variables. This fact, coupled with donor stars that underfill their
Roche lobes and very cool white dwarfs, brand the binaries as post
common-envelope systems whose orbits have not yet decayed to the point of
Roche-lobe contact. They are pre-magnetic CVs, or pre-Polars. The systems
exhibit spin/orbit synchronism and apparently accrete by efficient capture of
the stellar wind from the secondary star, a process that has been dubbed a
``magnetic siphon''. Because of this, period evolution of the binaries will
occur solely by gravitational radiation, which is very slow for periods >3 hr.
Optical surveys for the cyclotron harmonics appear to be the only means of
discovery, so the space density of pre-Polars could rival that of Polars, and
the binaries provide an important channel of progenitors (in addition to the
asynchronous Intermediate Polars). Both physical and SDSS observational
selection effects are identified that may help to explain the clumping of all
six systems in a narrow range of magnetic field strength around 60 MG.Comment: 25 pages, 13 figures, Accepted to Ap
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Nuclear resonance tomography with a toroid cavity detector
A toroid cavity detection system for determining the spectral properties and distance from a fixed point for a sample using Nuclear Magnetic Resonance. The detection system consists of a toroid with a central conductor oriented along the main axis of the toroidal cylinder and perpendicular to a static uniform magnetic field oriented along the main axis of the toroid. An rf signal is inputted to the central conductor to produce a magnetic field perpendicular to the central axis of the toroid and whose field strength varies as the inverse of the radius of the toroid. The toroid cavity detection system can be used to encapsulate a sample, or the detection system can be perforated to allow a sample to flow into the detection device or to place the samples in specified sample tubes. The central conductor can also be coated to determine the spectral property of the coating and the coating thickness. The sample is then subjected to the respective magnetic fields and the responses measured to determine the desired properties
Induction of fibroblast senescence generates a non-fibrogenic myofibroblast phenotype that differentially impacts on cancer prognosis
Cancer-associated fibroblasts (CAF) remain a poorly characterized, heterogeneous cell population. Here we characterized two previously described tumor-promoting CAF sub-types, smooth muscle actin (SMA)-positive myofibroblasts and senescent fibroblasts, identifying a novel link between the two
The Cyclotron Fundamental Exposed in the High-Field Magnetic Variable V884 Her
High-quality phase-resolved optical spectropolarimetry is presented for the
magnetic cataclysmic variable V884 Her. The overall circular polarization
during active accretion states is low and only slightly variable in the range
5000-8000A. However, the polarization is highly structured with wavelength,
showing very broad polarization humps, narrow features that are associated with
weak absorption lines in the total spectral flux, and sharp reversals across
each major emission line. The polarization reversals arise from Zeeman
splitting in the funnel gas in a longitudinal magnetic field B~30kG. The set of
narrow, polarized absorption features matches the Zeeman pattern of hydrogen
for a nearly uniform magnetic field of B=150MG, indicating that the features
are "halo" absorption lines formed in a relatively cool reversing layer above
the shock. With this identification, the broad polarization humps centered near
7150A and below 4000A are assigned to cyclotron emission from the fundamental
and first harmonic (n=2), respectively. V884 Her is only the second AM Her
system known with a field exceeding 100MG, and the first case in which the
cyclotron fundamental has been directly observed from a magnetic white dwarf.Comment: 14 pages, 6 figures, LaTeX, to appear in The Astrophysical Journal,
Part
Imagery Rescripting Versus Extinction: Distinct and Combined Effects on Expectancy and Revaluation Learning
Anxiety disorders are effectively treated with exposure therapy, but relapse remains high. Fear may reinstate after reoccurrence of the negative event because the expectancy of the aversive outcome (unconditioned stimulus [US]) is adjusted but not its evaluation. Imagery rescripting (ImRs) is an intervention that is proposed to work through revaluation of the US. The aim of our preregistered study was to test the effects of ImRs and extinction on US expectancy and US revaluation. Day 1 (n = 106) consisted of acquisition with an aversive film clip as US. The manipulation (ImRs + extinction, extinction-only, or ImRs-only) took place on Day 2. Reinstatement of fear was tested on Day 3. Results showed expectancy learning in both extinction conditions but not in the ImRs-only condition and no enhanced revaluation learning in ImRs. The combination of ImRs and extinction slowed down extinction but did not protect against reinstatement, which pleads in favor of stand-alone interventions in clinical practice
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