1,953 research outputs found
Kombinierte Methode zur Bestimmung der Flussdichteverteilung am Beispiel Solugas
Turmkraftwerke weisen einen hohen Wirkungsgrad und groĂe Kostensenkungs-potenziale auf. Zur Bestimmung der Wirkungsgrade und Eintrittsleistung und zur Optimierung des Betriebs dient die Messung der solaren Flussdichteverteilung in der Ebene der Eintrittsapertur des Receivers. Flussdichtemesssysteme nutzen hĂ€ufig einen diffus reflektierenden Schwenkbalken, der sich vor dem Receiver vorbeibewegt, wĂ€hrend eine CCD-Kamera die Helligkeitsverteilung der am Balken reflektierten solaren Strahlung aufnimmt. AnschlieĂend wird das Bild mit Radio-meterwerten kalibriert. An kommerziellen Turmkraftwerken höherer Leistung und entsprechend gröĂerer Apertur sind mechanische Schwenkbalken sehr groĂ und daher nur bedingt geeignet. Aus diesem Grund werden Messmethoden untersucht, die ohne Schwenkbalken auskommen [1].
Eine Methode kombiniert eine Raytracing-Simulation mit einer vereinfachten Messung im Bereich des Strahlungsschutzes. Die Messung dient dabei zur Validierung der Simulationen. Aus dem Simulationsergebnis lassen sich dann alle wichtigen GröĂen zur Charakterisierung des Kraftwerkes ableiten.
Dieses Poster prÀsentiert die Anwendung dieser Methode an dem Demonstrationskraftwerk SOLUGAS, einem Cavityrohrreceiver mit Mikrogasturbine [2]
The Nature of Blue Cores in Spheroids: a Possible Connection with AGN and Star Formation
We investigate the physical nature of blue cores in early-type galaxies
through the first multi-wavelength analysis of a serendipitously discovered
field blue-nucleated spheroid in the background of the deep ACS/WFC griz
multicolor observations of the cluster Abell 1689. The resolved g-r, r-i and
i-z color maps reveal a prominent blue core identifying this galaxy as a
``typical'' case study, exhibiting variations of 0.5-1.0 mag in color between
the center and the outer regions, opposite to the expectations of reddened
metallicity induced gradients in passively evolved ellipticals. From a
Magellan-Clay spectrum we secure the galaxy redshift at . We find a
strong X-ray source coincident with the spheroid galaxy. Spectral features and
a high X-ray luminosity indicate the presence of an AGN in the galaxy. However,
a comparison of the X-ray luminosity to a sample derived from the Chandra Deep
Field South displays Lx to be comparable to Type I/QSO galaxies while the
optical flux is consistent with a normal star-forming galaxy. We conclude that
the galaxy's non-thermal component dominates at high-energy wavelengths while
we associate the spheroid blue light with the stellar spectrum of normal
star-forming galaxies. We argue about a probable association between the
presence of blue cores in spheroids and AGN activity.Comment: Accepted for publication in the Astrophysical Journal. 6 pages, 3
figures. Full resolution images available at
http://acs.pha.jhu.edu/~felipe/e-print
CLASH: Weak-Lensing Shear-and-Magnification Analysis of 20 Galaxy Clusters
We present a joint shear-and-magnification weak-lensing analysis of a sample
of 16 X-ray-regular and 4 high-magnification galaxy clusters at 0.19<z<0.69
selected from the Cluster Lensing And Supernova survey with Hubble (CLASH). Our
analysis uses wide-field multi-color imaging, taken primarily with Suprime-Cam
on the Subaru Telescope. From a stacked shear-only analysis of the
X-ray-selected subsample, we detect the ensemble-averaged lensing signal with a
total signal-to-noise ratio of ~25 in the radial range of 200 to 3500kpc/h. The
stacked tangential-shear signal is well described by a family of standard
density profiles predicted for dark-matter-dominated halos in gravitational
equilibrium, namely the Navarro-Frenk-White (NFW), truncated variants of NFW,
and Einasto models. For the NFW model, we measure a mean concentration of
at . We show this is in excellent agreement with Lambda
cold-dark-matter (LCDM) predictions when the CLASH X-ray selection function and
projection effects are taken into account. The best-fit Einasto shape parameter
is , which is consistent with the
NFW-equivalent Einasto parameter of . We reconstruct projected mass
density profiles of all CLASH clusters from a joint likelihood analysis of
shear-and-magnification data, and measure cluster masses at several
characteristic radii. We also derive an ensemble-averaged total projected mass
profile of the X-ray-selected subsample by stacking their individual mass
profiles. The stacked total mass profile, constrained by the
shear+magnification data, is shown to be consistent with our shear-based
halo-model predictions including the effects of surrounding large-scale
structure as a two-halo term, establishing further consistency in the context
of the LCDM model.Comment: Accepted by ApJ on 11 August 2014. Textual changes to improve clarity
(e.g., Sec.3.2.2 "Number-count Depletion", Sec.4.3 "Shape Measurement",
Sec.4.4 "Background Galaxy Selection"). Results and conclusions remain
unchanged. For the public release of Subaru data, see
http://archive.stsci.edu/prepds/clash
CLASH: Extreme Emission Line Galaxies and Their Implication on Selection of High-Redshift Galaxies
We utilize the CLASH (Cluster Lensing And Supernova survey with Hubble)
observations of 25 clusters to search for extreme emission-line galaxies
(EELGs). The selections are carried out in two central bands: F105W (Y105) and
F125W (J125), as the flux of the central bands could be enhanced by the
presence of [O III] 4959, 5007 at redshift of about 0.93-1.14 and 1.57-1.79,
respectively. The multi-band observations help to constrain the equivalent
widths of emission lines. Thanks to cluster lensing, we are able to identify 52
candidates down to an intrinsic limiting magnitude of 28.5 and to a rest-frame
[O III] 4959,5007 equivalent width of about 3737 angstrom. Our samples include
a number of EELGs at lower luminosities that are missed in other surveys, and
the extremely high equivalent width can be only found in such faint galaxies.
These EELGs can mimic the dropout feature similar to that of high redshift
galaxies and contaminate the color-color selection of high redshift galaxies
when the S/N ratio is limited or the band coverage is incomplete. We predict
that the fraction of EELGs in the future high redshift galaxy selections cannot
be neglected.Comment: 17 pages, 9 figures, 2 tables, Accepted for publication in AP
Lincp21-RNA as Predictive Response Marker for Preoperative Chemoradiotherapy in Rectal Cancer
Preoperative chemoradiotherapy (CRT) is a standard treatment for locally advanced rectal cancer (RC) patients, but its use in non-responders can be associated with increased toxicities and resection delay. LincRNA-p21 is a long non-coding RNA involved in the p53 pathway and angiogenesis regulation. We aimed to study whether lincRNA-p21 expression levels can act as a predictive biomarker for neoadjuvant CRT response. We analyzed RNAs from pretreatment biopsies from 70 RC patients treated with preoperative CRT. Pathological response was classified according to the tumor regression grade (TRG) Dworak classification. LincRNA-p21 expression was determined by RTqPCR. The results showed that lincRNA-p21 was upregulated in stage III tumors (p = 0.007) and in tumors with the worst response regarding TRG (p = 0.027) and downstaging (p = 0.016). ROC curve analysis showed that lincRNA-p21 expression had the capacity to distinguish a complete response from others (AUC:0.696; p = 0.014). LincRNA-p21 was shown as an independent marker of preoperative CRT response (p = 0.047) and for time to relapse (TTR) (p = 0.048). In conclusion, lincRNA-p21 is a marker of advanced disease, worse response to neoadjuvant CRT, and shorter TTR in locally advanced RC patients. The study of lincRNA-p21 may be of value in the individualization of pre-operative CRT in RC
Strong Lensing Analysis of A1689 from Deep Advanced Camera Images
We analyse deep multi-colour Advanced Camera images of the largest known
gravitational lens, A1689. Radial and tangential arcs delineate the critical
curves in unprecedented detail and many small counter-images are found near the
center of mass. We construct a flexible light deflection field to predict the
appearance and positions of counter-images. The model is refined as new
counter-images are identified and incorporated to improve the model, yielding a
total of 106 images of 30 multiply lensed background galaxies, spanning a wide
redshift range, 1.0z5.5. The resulting mass map is more circular in
projection than the clumpy distribution of cluster galaxies and the light is
more concentrated than the mass within . The projected mass profile
flattens steadily towards the center with a shallow mean slope of
, over the observed range,
r, matching well an NFW profile, but with a relatively high
concentration, . A softened isothermal profile
(\arcs) is not conclusively excluded, illustrating that
lensing constrains only projected quantities. Regarding cosmology, we clearly
detect the purely geometric increase of bend-angles with redshift. The
dependence on the cosmological parameters is weak due to the proximity of
A1689, , constraining the locus, .
This consistency with standard cosmology provides independent support for our
model, because the redshift information is not required to derive an accurate
mass map. Similarly, the relative fluxes of the multiple images are reproduced
well by our best fitting lens model.Comment: Accepted by ApJ. For high quality figures see
http://wise-obs.tau.ac.il/~kerens/A168
From Research to Industry: Development of a High-Resolution Measurement System for Mirrored Heliostats in Series Production
A new measurement system able to measure the shape accuracy of complete mirrored heliostat modules in series production was developed. The applied deflectometry measurement method is based on the reflection of regular
patterns in the mirror surface and their distortions due to mirror surface deviations. The measurement systemâs key
features are its high spatial resolution, its low global measurement uncertainty of less than 0.2 mrad and its total measurement and evaluation time of few minutes. The measurement process is contact-free and completely automatic, which allows a 100% optical quality control of the production of the heliostat modules for a typical solar tower power plant. The system is validated by measuring a flat reference surface and by comparison to manual photogrammetry measurements. This makes the new measurement system, called QDec-M-Helio, a valuable tool for final geometric quality control of heliostats in series production, especially for new generation heliostats which obtain its final curvature during a bonding process between mirror and support structure from a precise jig
Exoskeleton Technology in Rehabilitation: Towards an EMG-Based Orthosis System for Upper Limb Neuromotor Rehabilitation
The rehabilitation of patients should not only be limited to the first phases during intense hospital care but also support and therapy should be guaranteed in later stages, especially during daily life activities if the patientâs state requires this. However, aid should only be given to the patient if needed and as much as it is required. To allow this, automatic self-initiated movement support and patient-cooperative control strategies have to be developed and integrated into assistive systems. In this work, we first give an overview of different kinds of neuromuscular diseases, review different forms of therapy, and explain possible fields of rehabilitation and benefits of robotic aided rehabilitation. Next, the mechanical design and control scheme of an upper limb orthosis for rehabilitation are presented. Two control models for the orthosis are explained which compute the triggering function and the level of assistance provided by the device. As input to the model fused sensor data from the orthosis and physiology data in terms of electromyography (EMG) signals are used
Discovery of Two Distant Type Ia Supernovae in the Hubble Deep Field North with the Advanced Camera for Surveys
We present observations of the first two supernovae discovered with the
recently installed Advanced Camera for Surveys (ACS) on the Hubble Space
Telescope. The supernovae were found in Wide Field Camera images of the Hubble
Deep Field North taken with the F775W, F850LP, and G800L optical elements as
part of the ACS guaranteed time observation program. Spectra extracted from the
ACS G800L grism exposures confirm that the objects are Type Ia supernovae (SNe
Ia) at redshifts z=0.47 and z=0.95. Follow-up HST observations have been
conducted with ACS in F775W and F850LP and with NICMOS in the near-infrared
F110W bandpass, yielding a total of 9 flux measurements in the 3 bandpasses
over a period of 50 days in the observed frame. We discuss many of the
important issues in doing accurate photometry with the ACS. We analyze the
multi-band light curves using two different fitting methods to calibrate the
supernovae luminosities and place them on the SNe Ia Hubble diagram. The
resulting distances are consistent with the redshift-distance relation of the
accelerating universe model, although evolving intergalactic grey dust remains
as a less likely possibility. The relative ease with which these SNe Ia were
found, confirmed, and monitored demonstrates the potential ACS holds for
revolutionizing the field of high-redshift SNe Ia, and therefore of testing the
accelerating universe cosmology and constraining the "epoch of deceleration".Comment: 11 pages, 8 embedded figures. Accepted for publication in Ap
CLASH-X: A Comparison of Lensing and X-ray Techniques for Measuring the Mass Profiles of Galaxy Clusters
We present profiles of temperature (Tx), gas mass, and hydrostatic mass
estimated from new and archival X-ray observations of CLASH clusters. We
compare measurements derived from XMM and Chandra observations with one another
and compare both to gravitational lensing mass profiles derived with CLASH HST
and ground-based lensing data. Radial profiles of Chandra and XMM electron
density and enclosed gas mass are nearly identical, indicating that differences
in hydrostatic masses inferred from X-ray observations arise from differences
in Tx measurements. Encouragingly, cluster Txs are consistent with one another
at ~100-200 kpc radii but XMM Tx systematically decline relative to Chandra Tx
at larger radii. The angular dependence of the discrepancy suggests additional
investigation on systematics such as the XMM point spread function correction,
vignetting and off-axis responses. We present the CLASH-X mass-profile
comparisons in the form of cosmology-independent and redshift-independent
circular-velocity profiles. Ratios of Chandra HSE mass profiles to CLASH
lensing profiles show no obvious radial dependence in the 0.3-0.8 Mpc range.
However, the mean mass biases inferred from the WL and SaWLens data are
different. e.g., the weighted-mean value at 0.5 Mpc is = 0.12 for the WL
comparison and = -0.11 for the SaWLens comparison. The ratios of XMM HSE
mass profiles to CLASH lensing profiles show a pronounced radial dependence in
the 0.3-1.0 Mpc range, with a weighted mean mass bias of value rising to
~0.3 at ~1 Mpc for the WL comparison and of 0.25 for SaWLens comparison.
The enclosed gas mass profiles from both Chandra and XMM rise to a value 1/8
times the total-mass profiles inferred from lensing at 0.5 Mpc and remain
constant outside of that radius, suggesting that [8xMgas] profiles may be an
excellent proxy for total-mass profiles at >0.5 Mpc in massive galaxy clusters.Comment: Accepted to ApJ; 24 pages; scheduled to appear in the Oct 10, 2014
issue. This version corrects the typographical error in the superscripts for
Equation (2) to include the square of (r/r_core). The correct version of this
equation was used in the analysi
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