72 research outputs found
Thissavros Hydropower Plant Managing Geotechnical Problems in the Construction
The Thissavros hydropower and pumped storage project on the Nestos river in northern Greece involved construction of a 172 m high rockfill dam and an underground power house with 300 MW installed capacity. Bedrock at the site consists of gneiss with complex geological structure and complicated hydrogeological conditions. On the right abutment, the dam partially rests on a large landslide and the toe of another large landslide extends into the plunge pool from the left bank. Initial excavations activated the dormant slides. Unloading, buttressing and drainage successfully stabilized the landslides. Core material for the dam is a silty sand and required special precautions in design and construction. Starting with an extremely rapid reservoir filling the dam has performed highly satisfactorily. The power house had to be excavated in a relatively unfavorable geological orientation but application of structural discontinuity analysis avoided wedge failures
Application of Multiprotocol Medical Imaging Communications and an Extended DICOM WADO Service in a Teleradiology Architecture
Multiprotocol medical imaging communication through the Internet is more flexible than the tight DICOM transfers. This paper introduces a modular multiprotocol teleradiology architecture that integrates DICOM and common Internet services (based on web, FTP, and E-mail) into a unique operational domain. The extended WADO service (a web extension of DICOM) and the other proposed services allow access to all levels of the DICOM information hierarchy as opposed to solely Object level. A lightweight client site is considered adequate, because the server site of the architecture provides clients with service interfaces through the web as well as invulnerable space for temporary storage, called as User Domains, so that users fulfill their applications' tasks. The proposed teleradiology architecture is pilot implemented using mainly Java-based technologies and is evaluated by engineers in collaboration with doctors. The new architecture ensures flexibility in access, user mobility, and enhanced data security
Potential for measurement of the tensor electric and magnetic polarizabilities of the deuteron in storage-ring experiments with polarized beams
Measurement of the tensor electric and magnetic polarizabilities of the
deuteron is of great interest, especially in connection with the possibilities
of COSY and GSI. These polarizabilities can be measured in storage rings by the
frozen spin method providing a disappearance of g-2 precession. This method
will be used in the planned deuteron electric-dipole-moment experiment in
storage rings. The tensor electric polarizability of the deuteron significantly
influences the buildup of the vertical polarization in the above experiment.
The spin interactions depending on the electric dipole moment, the tensor
electric polarizability, and main systematical errors caused by field
misalignments have very different symmetries. For the considered experimental
conditions, the sensitivity to the deuteron EDM of cm
corresponds to measuring the both of tensor polarizabilities with an accuracy
of cm. This
conservative estimate can be improved by excluding the systematical error
caused by the field instability which is negligible for the measurement of the
tensor polarizabilities. To find the tensor magnetic polarizability, the
horizontal components of the polarization vector should be measured.Comment: 11 pages, the extended version of the paper prepared for the
Proceedings of 19th International Spin Physics Symposium (September 27 -
October 2, 2010, Julich, Germany
The 11-years solar cycle as the manifestation of the dark Universe
The solar luminosity in the visible changes at the 10-3 level, following an
11 years period. In X-rays, which should not be there, the amplitude varies
100000 times stronger, making their mysterious origin since the discovery in
1938 even more puzzling, and inspiring. We suggest that the multifaceted
mysterious solar cycle is due to some kind of dark matter streams hitting the
Sun. Planetary gravitational lensing enhances (occasionally) slow moving flows
of dark constituents towards the Sun, giving rise to the periodic behaviour.
Jupiter provides the driving oscillatory force, though its 11.8 years orbital
period appears slightly decreased, just as 11 years, if the lensing impact of
other planets is included. Then, the 11 years solar clock may help to decipher
(overlooked) signatures from the dark sector in laboratory experiments or
observations in space.Comment: 7 pages, 1 Figure, to appear in the proceedings of the 9th Patras
workshop, Mainz, German
Search for axions in streaming dark matter
A new search strategy for the detection of the elusive dark matter (DM) axion
is proposed. The idea is based on streaming DM axions, whose flux might get
temporally enormously enhanced due to gravitational lensing. This can happen if
the Sun or some planet (including the Moon) is found along the direction of a
DM stream propagating towards the Earth location. The experimental requirements
to the axion haloscope are a wide-band performance combined with a fast axion
rest mass scanning mode, which are feasible. Once both conditions have been
implemented in a haloscope, the axion search can continue parasitically almost
as before. Interestingly, some new DM axion detectors are operating wide-band
by default. In order not to miss the actually unpredictable timing of a
potential short duration signal, a network of co-ordinated axion antennae is
required, preferentially distributed world-wide. The reasoning presented here
for the axions applies to some degree also to any other DM candidates like the
WIMPs.Comment: 5 page
aKWISP: investigating short-distance interactions at sub-micron scales
The sub-micron range in the field of short distance interactions has yet to
be opened to experimental investigation, and may well hold the key to
understanding al least part of the dark matter puzzle. The aKWISP
(advanced-KWISP) project introduces the novel Double Membrane Interaction
Monitor (DMIM), a combined source-sensing device where interaction distances
can be as short as 100 nm or even 10 nm, much below the 1-10 micron distance
which is the lower limit encountered by current experimental efforts. aKWISP
builds on the technology and the results obtained with the KWISP
opto-mechanical force sensor now searching at CAST for the direct coupling to
matter of solar chameleons. It will reach the ultimate quantum-limited
sensitivity by exploiting an array of technologies, including operation at
milli-Kelvin temperatures. Recent suggestions point at short-distance
interactions studies as intriguing possibilities for the detection of axions
and of new physical phenomena
Atmospheric Temperature anomalies as manifestation of the dark Universe
We are investigating the possible origin of small-scale anomalies, like the
annual stratospheric temperature anomalies. Unexpectedly within known physics,
their observed planetary "dependency", does not match concurrent solar
activity, whose impact on the atmosphere is unequivocal; this points at an
additional energy source of exo-solar origin. A viable concept behind such
observations is based on possible gravitational focusing by the Sun and its
planets towards the Earth of low-speed invisible streaming matter; its influx
towards the Earth gets temporally enhanced. Only a somehow "strongly"
interacting invisible streaming matter with the small upper atmospheric
screening can be behind the observed temperature excursions. Ordinary dark
matter (DM) candidates like axions or WIMPs, cannot have any noticeable impact.
The associated energy deposition is . The atmosphere has been
uninterruptedly monitored for decades. Therefore, the upper atmosphere can
serve as a novel (low-threshold) detector for the dark Universe, with built-in
spatiotemporal resolution while the solar system gravity acts temporally as a
signal amplifier. Interestingly, the anomalous ionosphere shows a relationship
with the inner earth activity like earthquakes. Similarly investigating the
transient sudden stratospheric warmings within the same reasoning, the nature
of the assumed "invisible streams" could be deciphered.Comment: 8 pages, 7 figures, Published in the proceedings of the "15th
International Conference on Meteorology, Climatology and Atmospheric Physics
(COMECAP 2021)" see
https://www.conferre.gr/allevents/comecap2020/Proceedings_Final.pd
Search for chameleons with CAST
In this work we present a search for (solar) chameleons with the CERN Axion
Solar Telescope (CAST). This novel experimental technique, in the field of dark
energy research, exploits both the chameleon coupling to matter () and to photons () via the Primakoff effect. By reducing
the X-ray detection energy threshold used for axions from 1keV to 400eV
CAST became sensitive to the converted solar chameleon spectrum which peaks
around 600eV. Even though we have not observed any excess above background,
we can provide a 95% C.L. limit for the coupling strength of chameleons to
photons of for .Comment: 8 pages, 12 figure
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