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Generation of Micro Mechanical Devices Using Stereo Lithography
A high resolution machining setup for creating three-dimensional precision components from a
UV-curable photo-resin has been developed. By using frequency-converted diode-pumped solid
state lasers, functional micro-mechanical devices are directly fabricated in a successive layer-bylayer fashion. Within this paper, the direct generation of micro assemblies having
moving components without further assembly of parts will be presented. The micro system
design is based on user-defined 3D-CAD data and will completively be built up within the
fabrication cycle. By using specially developed μSL materials with suitable properties for micromechanical parts, the development from Rapid Prototyping towards Rapid Production of small
series is intended.Mechanical Engineerin
Detection of X-rays from the jet-driving Symbiotic Star MWC 560
We report the detection of X-ray emission from the jet-driving symbiotic star
MWC 560. We observed MWC 560 with XMM-Newton for 36 ks. We fitted the spectra
from the EPIC pn, MOS1 and MOS2 instruments with XSPEC and examined the light
curves with the package XRONOS. The spectrum can be fitted with a highly
absorbed hard X-ray component from an optically-thin hot plasma, a Gaussian
emission line with an energy of 6.1 keV and a less absorbed soft thermal
component. The best fit is obtained with a model in which the hot component is
produced by optically thin thermal emission from an isobaric cooling flow with
a maximum temperature of 61 keV, which might be created inside an
optically-thin boundary layer on the surface of the accreting with dwarf. The
derived parameters of the hard component detected in MWC 560 are in good
agreement with similar objects as CH Cyg, SS7317, RT Cru and T CrB, which all
form a new sub-class of symbiotic stars emitting hard X-rays. Our previous
numerical simulations of the jet in MWC 560 showed that it should produce
detectable soft X-ray emission. We infer a temperature of 0.17 keV for the
observed soft component, i.e. less than expected from our models. The total
soft X-ray flux (i.e. at < 3 keV) is more than a factor 100 less than predicted
for the propagating jet soon after its birth (<0.3 yr), but consistent with the
value expected due its decrease with age. The ROSAT upper limit is also
consistent with such a decrease. We find aperiodic or quasi-periodic
variability on timescales of minutes and hours, but no periodic rapid
variability. All results are consistent with an accreting white dwarf powering
the X-ray emission and the existence of an optically-thin boundary layer around
it.Comment: 8 pages, 5 figure, accepted for publication in A &
Determination of Corresponding Temperature Distribution within CFRP during Laser Cutting
AbstractLaser cutting of carbon fiber reinforced plastics as a thermal process results in a thermal load on the material. Due to the high thermal conductivity of carbon fibers, residual heat is conducted along the fibers, away from the laser interaction zone. Common temperature measurement techniques, such as pyrometry and infrared thermography only allow for observation of the temperature development on the surface of the material. In order to achieve information about the temperature distribution within the material during the cutting process, thermochromes and thermocouples were implemented during the laminating process of CFRP. The cutting tests were performed with a single mode fiber laser emitting a continuous wave and at a wavelength of λ = 1080 nm
Hydrodynamical simulations of the jet in the symbiotic star MWC 560 III. Application to X-ray jets in symbiotic stars
In papers I and II in this series, we presented hydrodynamical simulations of
jet models with parameters representative of the symbiotic system MWC 560.
These were simulations of a pulsed, initially underdense jet in a high density
ambient medium. Since the pulsed emission of the jet creates internal shocks
and since the jet velocity is very high, the jet bow shock and the internal
shocks are heated to high temperatures and should therefore emit X-ray
radiation. In this paper, we investigate in detail the X-ray properties of the
jets in our models. We have focused our study on the total X-ray luminosity and
its temporal variability, the resulting spectra and the spatial distribution of
the emission. Temperature and density maps from our hydrodynamical simulations
with radiative cooling presented in the second paper are used together with
emissivities calculated with the atomic database ATOMDB. The jets in our models
show extended and variable X-ray emission which can be characterized as a sum
of hot and warm components with temperatures that are consistent with
observations of CH Cyg and R Aqr. The X-ray spectra of our model jets show
emission line features which correspond to observed features in the spectra of
CH Cyg. The innermost parts of our pulsed jets show iron line emission in the
6.4 - 6.7 keV range which may explain such emission from the central source in
R Aqr. We conclude that MWC 560 should be detectable with Chandra or
XMM-Newton, and such X-ray observations will provide crucial for understanding
jets in symbiotic stars.Comment: 10 pages, 12 figures, accepted for publication in ApJ, uses
emulateap
Deterministic single-photon source from a single ion
We realize a deterministic single-photon source from one and the same calcium
ion interacting with a high-finesse optical cavity. Photons are created in the
cavity with efficiency (88 +- 17)%, a tenfold improvement over previous
cavity-ion sources. Results of the second-order correlation function are
presented, demonstrating a high suppression of two-photon events limited only
by background counts. The cavity photon pulse shape is obtained, with good
agreement between experiment and simulation. Moreover, theoretical analysis of
the temporal evolution of the atomic populations provides relevant information
about the dynamics of the process and opens the way to future investigations of
a coherent atom-photon interface
Mid-IR period-magnitude relations for AGB stars
Asymptotic Giant Branch variables are found to obey period-luminosity
relations in the mid-IR similar to those seen at K_S (2.14 microns), even at 24
microns where emission from circumstellar dust is expected to be dominant.
Their loci in the M, logP diagrams are essentially the same for the LMC and for
NGC6522 in spite of different ages and metallicities. There is no systematic
trend of slope with wavelength. The offsets of the apparent magnitude vs. logP
relations imply a difference between the two fields of 3.8 in distance modulus.
The colours of the variables confirm that a principal period with log P > 1.75
is a necessary condition for detectable mass-loss. At the longest observed
wavelength, 24 microns, many semi-regular variables have dust shells comparable
in luminosity to those around Miras. There is a clear bifurcation in LMC
colour-magnitude diagrams involving 24 micron magnitudes.Comment: 5 pages, 4 figure
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