2,948 research outputs found
Observation of charge-density-wave excitations in manganites
In the optical conductivity of four different manganites with commensurate
charge order (CO), strong peaks appear in the meV range below the ordering
temperature T_{CO}. They are similar to those reported for one-dimensional
charge density waves (CDW) and are assigned to pinned phasons. The peaks and
their overtones allow one to obtain, for La{1-n/8}Ca{n/8}$MnO{3} with n = 5, 6,
the electron-phonon coupling, the effective mass of the CO system, and its
contribution to the dielectric constant. These results support a description of
the CO in La-Ca manganites in terms of moderately weak-coupling and of the CDW
theory.Comment: To be published on Phys. Rev. Let
Multidisciplinary study of the Tindari Fault (Sicily, Italy) separating ongoing contractional and extensional compartments along the active Africa–Eurasia convergent boundary
The Africa–Eurasia convergence in Sicily and southern Calabria is currently expressed by two different tectonic
and geodynamic domains: thewestern region, governed by a roughlyN–S compression generated by a continental
collision; the eastern one, controlled by a NW–SE extension related to the south-east-directed expansion of
the Calabro–Peloritan Arc. The different deformation pattern of these two domains is accommodated by a
right-lateral shear zone (Aeolian–Tindari–Letojanni fault system) which, from the Ionian Sea, north of Mt.
Etna, extends across the Peloritani chain to the Aeolian Islands.
In this work, we study the evidence of active tectonics characterizing this shear zone, through the analysis of
seismic and geodetic data acquired by the INGV networks in the last 15 years. The study is completed by
structural and morphological surveys carried out between Capo Tindari and the watershed of the chain.
The results allowed defining a clear structural picture depicting the tectonic interferences between the two
different geodynamic domains. The results indicate that, besides the regional ~N130°E horizontal extensional
stress field, another one, NE–SW-oriented, is active in the investigated area. Both tension axes are mutually
independent and have been active up to the present at different times. The coexistence of these different
active horizontal extensions is the result of complex interactions between several induced stresses: 1) the
regional extension (NW–SE) related to the slab rollback and back-arc extension; 2) the strong uplift of the
chain; 3) the accommodation between compressional and extensional tectonic regimes along the Aeolian–
Tindari–Letojanni faults, through a SSE–NNW right-lateral transtensional displacement. In these conditions,
the greater and recurring uplift activity is not able to induce a radial extensional dynamics, but, under the
“directing” action of the shear system, it can only act on the regional extension (NW–SE) and produce the
second system of extension (NE–SW)
PHYSICAL WORK AND THERMAL EMISSION
In this progress report, the ninth of the joint research CON1 - ENEA - FILPJ, after a thermodynamic approach-to the human body machine, the first application heat-exchange equation during a physical working period is carried out. The study is performed during "positive" and "negative work thermodynamical cycles, and the main result is analyzed and compared with experimental results
Reliability analysis of wireless sensor network for smart farming applications
Wireless Sensor Networks are subjected to some design constraints (e.g., processing capability, storage memory, energy consumption, fixed deployment, etc.) and to outdoor harsh conditions that deeply affect the network reliability. The aim of this work is to provide a deeper understanding about the way redundancy and node deployment affect the network reliability. In more detail, the paper analyzes the design and implementation of a wireless sensor network for low-power and low-cost applications and calculates its reliability considering the real environmental conditions and the real arrangement of the nodes deployed in the field. The reliability of the system has been evaluated by looking for both hardware failures and communication errors. A reliability prediction based on different handbooks has been carried out to estimate the failure rate of the nodes self-designed and self-developed to be used under harsh environments. Then, using the Fault Tree Analysis the real deployment of the nodes is taken into account considering the Wi-Fi coverage area and the possible communication link between nearby nodes. The findings show how different node arrangements provide significantly different reliability. The positioning is therefore essential in order to obtain maximum performance from a Wireless sensor network
Progress in crystal extraction and collimation
Recent IHEP Protvino experiments show efficiencies of crystal-assisted slow
extraction and collimation of 85.3+-2.8%, at the intensities of the channeled
beam on the order of 10^12 proton per spill of 2 s duration. The obtained
experimental data well follows the theory predictions. We compare the
measurements against theory and outline the theoretical potential for further
improvement in the efficiency of the technique. This success is important for
the efficient use of IHEP accelerator and for implementation of
crystal-assisted collimation at RHIC and slow extraction from AGS onto E952,
now in preparation. Future applications, spanning in the energy from order of 1
GeV (scraping in SNS, slow extraction from COSY and medical accelerators) to
order of 1 TeV and beyond (scraping in Tevatron, LHC, VLHC), can benefit from
these studies.Comment: 7pp. Presented at HEACC 2001 (Tsukuba, March 25-30
Crystal experiments on efficient beam extraction
Silicon crystal was channeling and extracting 70-GeV protons from the U-70
accelerator with efficiency of 85.3+-2.8% as measured for a beam of 10^12
protons directed towards crystals of 2 mm length in spills of 1-2 s duration.
The experimental data follow very well the prediction of Monte Carlo
simulations. This success is important to devise a more efficient use of the
U-70 accelerator in Protvino and provides a crucial support for implementation
of crystal-assisted collimation of gold ion beam in RHIC and slow extraction
from AGS onto E952, now in preparation at Brookhaven Nat'l Lab. Future
applications, spanning in the energy from sub-GeV (medical) to order of 1 GeV
(scraping in the SNS, extraction from COSY) to order of 1 TeV and beyond
(scraping in the Tevatron, LHC, VLHC), can benefit from these studies.Comment: 12pp. Presented at 19-th Intern. Conference on Atomic Collisions in
Solids (ICACS-19: Paris, July 29 - August 3, 2001
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