2,353 research outputs found
Parameter Identification of Pressure Sensors by Static and Dynamic Measurements
Fast identification methods of pressure sensors are investigated. With regard
to a complete accurate sensor parameter identification two different
measurement methods are combined. The approach consists on one hand in
performing static measurements - an applied pressure results in a membrane
deformation measured interferometrically and the corresponding output voltage.
On the other hand optical measurements of the modal responses of the sensor
membranes are performed. This information is used in an inverse identification
algorithm to identify geometrical and material parameters based on a FE model.
The number of parameters to be identified is thereby generally limited only by
the number of measurable modal frequencies. A quantitative evaluation of the
identification results permits furthermore the classification of processing
errors like etching errors. Algorithms and identification results for membrane
thickness, intrinsic stress and output voltage will be discussed in this
contribution on the basis of the parameter identification of relative pressure
sensors.Comment: Submitted on behalf of EDA Publishing Association
(http://irevues.inist.fr/EDA-Publishing
A different glance to the site testing above Dome C
Due to the recent interest shown by astronomers towards the Antarctic Plateau
as a potential site for large astronomical facilities, we assisted in the last
years to a strengthening of site testing activities in this region,
particularly at Dome C. Most of the results collected so far concern
meteorologic parameters and optical turbulence measurements based on different
principles using different instruments. At present we have several elements
indicating that, above the first 20-30 meters, the quality of the optical
turbulence above Dome C is better than above whatever other site in the world.
The challenging question, crucial to know which kind of facilities to build on,
is to establish how much better the Dome C is than a mid-latitude site. In this
contribution we will provide some complementary elements and strategies of
analysis aiming to answer to this question. We will try to concentrate the
attention on critical points, i.e. open questions that still require
explanation/attention.Comment: 3 figures, EAS Publications Series, Volume 25, 2007, pp.5
Force-induced unfolding of a homopolymer on fractal lattice: exact results vs. mean field predictions
We study the force-induced unfolding of a homopolymer on the three
dimensional Sierpinski gasket. The polymer is subject to a contact energy
between nearest neighbour sites not consecutive along the chain and to a
stretching force. The hierarchical nature of the lattice we consider allows for
an exact treatment which yields the phase diagram and the critical behaviour.
We show that for this model mean field predictions are not correct, in
particular in the exact phase diagram there is {\em not} a low temperature
reentrance and we find that the force induced unfolding transition below the
theta temperature is second order.Comment: 15 pages, 5 eps figure
The role of climate change and human pressure on forest decline in the early Holocene on Qinghai-Tibetan Plateau â an ecohydrological modelling approach
Abstract HKT-ISTP 2013
B
Investigating Rare Events by Transition Interface Sampling
We briefly review simulation schemes for the investigation of rare
transitions and we resume the recently introduced Transition Interface
Sampling, a method in which the computation of rate constants is recast into
the computation of fluxes through interfaces dividing the reactant and product
state.Comment: 12 pages, 1 figure, contributed paper to the proceedings of NEXT
2003, Second Sardinian International Conference on News and Expectations in
Thermostatistics, 21-28 Sep 2003, Cagliari (Italy
Seamounts and oceanic igneous features in the NE Atlantic: a link between plate motions and mantle dynamics
A new regional compilation of seamount-like oceanic igneous features (SOIFs) in the NE Atlantic points to three distinct oceanic areas of abundant seamount clusters. Seamounts on oceanic crust dated 54â50 Ma are formed on smooth oceanic basement, which resulted from high spreading rates and magmatic productivity enhanced by higher than usual mantle plume activity. Late EoceneâEarly Miocene SOIF clusters are located close to newly formed tectonic features on rough oceanic crust in the Irminger, Iceland and Norway basins, reflecting an unstable tectonic regime prone to local readjustments of mid-ocean ridge and fracture zone segments accompanied by extra igneous activity. A SOIF population observed on Mid-MioceneâPresent rough oceanic basement in the Greenland and Lofoten basins, and on conjugate Kolbeinsey Ridge flanks, coincides with an increase in spreading rate and magmatic productivity. We suggest that both tectonic/kinematic and magmatic triggers produced Mid-MioceneâPresent SOIFs, but the Early Miocene westwards ridge relocation may have played a role in delaying SOIF formation south of the Jan Mayen Fracture Zone. We conclude that Iceland plume episodic activity combined with regional changes in relative plate motion led to local mid-ocean ridge readjustments, which enhanced the likelihood of seamount formation
Design considerations for table-top, laser-based VUV and X-ray free electron lasers
A recent breakthrough in laser-plasma accelerators, based upon ultrashort
high-intensity lasers, demonstrated the generation of quasi-monoenergetic
GeV-electrons. With future Petawatt lasers ultra-high beam currents of ~100 kA
in ~10 fs can be expected, allowing for drastic reduction in the undulator
length of free-electron-lasers (FELs). We present a discussion of the key
aspects of a table-top FEL design, including energy loss and chirps induced by
space-charge and wakefields. These effects become important for an optimized
table-top FEL operation. A first proof-of-principle VUV case is considered as
well as a table-top X-ray-FEL which may open a brilliant light source also for
new ways in clinical diagnostics.Comment: 6 pages, 4 figures; accepted for publication in Appl. Phys.
Wind speed vertical distribution at Mt. Graham
The characterization of the wind speed vertical distribution V(h) is
fundamental for an astronomical site for many different reasons: (1) the wind
speed shear contributes to trigger optical turbulence in the whole troposphere,
(2) a few of the astroclimatic parameters such as the wavefront coherence time
(tau_0) depends directly on V(h), (3) the equivalent velocity V_0, controlling
the frequency at which the adaptive optics systems have to run to work
properly, depends on the vertical distribution of the wind speed and optical
turbulence. Also, a too strong wind speed near the ground can introduce
vibrations in the telescope structures. The wind speed at a precise pressure
(200 hPa) has frequently been used to retrieve indications concerning the tau_0
and the frequency limits imposed to all instrumentation based on adaptive
optics systems, but more recently it has been proved that V_200 (wind speed at
200 hPa) alone is not sufficient to provide exhaustive elements concerning this
topic and that the vertical distribution of the wind speed is necessary. In
this paper a complete characterization of the vertical distribution of wind
speed strength is done above Mt.Graham (Arizona, US), site of the Large
Binocular Telescope. We provide a climatological study extended over 10 years
using the operational analyses from the European Centre for Medium-Range
Weather Forecasts (ECMWF), we prove that this is representative of the wind
speed vertical distribution at Mt. Graham with exception of the boundary layer
and we prove that a mesoscale model can provide reliable nightly estimates of
V(h) above this astronomical site from the ground up to the top of the
atmosphere (~ 20 km).Comment: 12 pages, 9 figures (whereof 3 colour), accepted by MNRAS May 27,
201
Lab::Measurement - A portable and extensible framework for controlling lab equipment and conducting measurements
Lab::Measurement is a framework for test and measurement automatization using
Perl 5. While primarily developed with applications in mesoscopic physics in
mind, it is widely adaptable. Internally, a layer model is implemented.
Communication protocols such as IEEE 488, USB Test & Measurement, or, e.g.,
VXI-11 are addressed by the connection layer. The wide range of supported
connection backends enables unique cross-platform portability. At the
instrument layer, objects correspond to equipment connected to the measurement
PC (e.g., voltage sources, magnet power supplies, multimeters, etc.). The
high-level sweep layer automates the creation of measurement loops, with
simultaneous plotting and data logging. An extensive unit testing framework is
used to verify functionality even without connected equipment. Lab::Measurement
is distributed as free and open source software.Comment: Published version (open access, CC BY 4.0). 7 pages; refers to
Lab::Measurement 3.660, see https://www.labmeasurement.de
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