178 research outputs found
The out of plane behaviour of masonry infilled frames
The great interest about out of plane behavior of masonry infill walls has recently increased since it is a key point in the seismic modelling of framed structures. Their contribute to the whole seismic resistance of a framed building cannot be skipped. After a review of the literature on the subject, this paper presents a trilinear constitutive model for the out of plane behavior of masonry infills based on the tensile strength of the constituents. Comparisons with literature model are provided and the identification of the model is based on experimental tests
LCC analysis for glued laminated timber components exposed in external
The aim of the experimentation is to characterize the performances of glued laminated timber components exposed to atmospheric agents, in the light of the concept of Life Cycle Cost, particularly emphasized in the Italian new legislation on public works.
In fact, it could be seen that the design of the construction details and the initial characteristics of glue laminated timber components, require a particular attention to avoid errors that may undermine the possibility to perform the structural functions for which, above all, this material it is dedicated.
The experimentation consisted of a series of tests aimed to identify the performance of glued laminated timber beams taken in site, after a work executed some years ago on a theatre built in Roman era, and to compare them with similarly manufactured new elements. The tests performed were thermography, ultrasound, Wood-Pecker penetrometer, mechanical characterization.
The results will be used to begin setting limits and conditions for outdoor use of glue
laminated timber, and assume a reliable life cycle, and consequently identify the most
appropriate maintenance strategy for the LCC
The CLT Panels in Structural Restoration: Characteristics and Technical Regulations
Wood can represent a valid and important alternative to the most commonly
used structural materials for the restoration of masonry buildings, with a view to efficient, effective and "conscious" renovation. Today, the modern technologies allows to overcome the structural limits of solid wood due to its own anisotropy. The use of composite wood elements makes possible to obtain excellent mechanical performances that consent to evaluate aspects such as the use of low environmental impact retrofit strategies. The aim of this work is the analysis of mechanical parameters related to CLT (cross laminated timber) panels in order to determine their possible use in the structural restoration of masonry buildings. The CLT panels consist of solid wood planks superimposed so that each layer has the fibres rotated ninety degrees with respect to the adjacent layer. The layers (always in odd number and at least three) can be connected by discrete joints, pins and nails, or glued together. This onfiguration enables to product large structural elements with considerable thickness. Two different experimental test campaigns were carried out on samples of panels with three and five glued layers. The purpose of experimentation activities was to evaluate the bending deformation of the wooden elements and shear strength of the bonding sections. All the tests were processed according to the provisions contained in the UNI standards. The test results were then compared with different theoretical calculation models to determine the one that best represents the tested material. The tests outcomes have shown that some characteristics of the material, such as the remarkable ductility, open different scenarios of use for the CLT panels in the field of structural restoration of masonry buildings
The effective dissipation in Nb/AlOx/Nb Josephson tunnel junctions by return current measurements
Measurements of temperature dependence of the return current in high quality Nb/AlOx/Nb Josephson junctions are presented. From the experimental data, we obtain the effective resistance, i.e., the effective dissipation, for the retrapping process, according to the generalized resistively shunted junction model proposed by Chen, Fisher, and Leggett. We present a careful analysis, based on a comparison between the measured temperature dependencies of both the return and the quasiparticle tunneling current. We find that the junction subgap conductance, which includes the quasiparticle and the quasiparticle-pair interference terms, is responsible for the return process. The measurements have been performed on various samples, in a wide range of critical current densities from 50 to 2250 A/cm2, covering different damping regimes and spanning over the high and low temperature limits. Junctions with low critical current density show ideal dissipation which makes the return current scale with temperature according to the BCS exponential behavior without flattening out effects. This result may be relevant for the possible use of Nb/AlOx/Nb junctions in macroscopic quantum coherence experiments, which strongly require a very low dissipation
Single-photon Resolved Cross-Kerr Interaction for Autonomous Stabilization of Photon-number States
Quantum states can be stabilized in the presence of intrinsic and
environmental losses by either applying active feedback conditioned on an
ancillary system or through reservoir engineering. Reservoir engineering
maintains a desired quantum state through a combination of drives and designed
entropy evacuation. We propose and implement a quantum reservoir engineering
protocol that stabilizes Fock states in a microwave cavity. This protocol is
realized with a circuit quantum electrodynamics platform where a Josephson
junction provides direct, nonlinear coupling between two superconducting
waveguide cavities. The nonlinear coupling results in a single photon resolved
cross-Kerr effect between the two cavities enabling a photon number dependent
coupling to a lossy environment. The quantum state of the microwave cavity is
discussed in terms of a net polarization and is analyzed by a measurement of
its steady state Wigner function.Comment: 8 pages, 6 figure
Photon Shot Noise Dephasing in the Strong-Dispersive Limit of Circuit QED
We study the photon shot noise dephasing of a superconducting transmon qubit
in the strong-dispersive limit, due to the coupling of the qubit to its readout
cavity. As each random arrival or departure of a photon is expected to
completely dephase the qubit, we can control the rate at which the qubit
experiences dephasing events by varying \textit{in situ} the cavity mode
population and decay rate. This allows us to verify a pure dephasing mechanism
that matches theoretical predictions, and in fact explains the increased
dephasing seen in recent transmon experiments as a function of cryostat
temperature. We investigate photon dynamics in this limit and observe large
increases in coherence times as the cavity is decoupled from the environment.
Our experiments suggest that the intrinsic coherence of small Josephson
junctions, when corrected with a single Hahn echo, is greater than several
hundred microseconds.Comment: 5 pages, 4 figures; includes Supporting Online Material of 6 pages
with 5 figure
Measurements of Quasiparticle Tunneling Dynamics in a Bandgap-Engineered Transmon Qubit
We have engineered the bandgap profile of transmon qubits by combining
oxygen-doped Al for tunnel junction electrodes and clean Al as quasiparticle
traps to investigate energy relaxation due to quasiparticle tunneling. The
relaxation time of the qubits is shown to be insensitive to this bandgap
engineering. Operating at relatively low makes the transmon
transition frequency distinctly dependent on the charge parity, allowing us to
detect the quasiparticles tunneling across the qubit junction. Quasiparticle
kinetics have been studied by monitoring the frequency switching due to
even/odd parity change in real time. It shows the switching time is faster than
10 s, indicating quasiparticle-induced relaxation has to be reduced to
achieve much longer than 100 s.Comment: 11 pages, 8 figure
The CLT Panels in Structural Restoration: Characteristics and Technical Regulations
Wood can represent a valid and important alternative to the most commonly used structural materials for the restoration of masonry buildings, with a view to efficient, effective and "conscious" renovation. Today, the modern technologies allows to overcome the structural limits of solid wood due to its own anisotropy. The use of composite wood elements makes possible to obtain excellent mechanical performances that consent to evaluate aspects such as the use of low environmental impact retrofit strategies. The aim of this work is the analysis of mechanical parameters related to CLT (cross laminated timber) panels in order to determine their possible use in the structural restoration of masonry buildings. The CLT panels consist of solid wood planks superimposed so that
each layer has the fibres rotated ninety degrees with respect to the adjacent layer. The layers (always in odd number and at least three) can be connected by discrete joints, pins and nails, or glued together. This configuration enables to product large structural elements with considerable thickness. Two different experimental test campaigns were carried out on samples of panels with three and five glued layers. The purpose of
experimentation activities was to evaluate the bending deformation of the wooden
elements and shear strength of the bonding sections. All the tests were processed according
to the provisions contained in the UNI standards. The test results were then compared
with different theoretical calculation models to determine the one that best represents the
tested material.
The tests outcomes have shown that some characteristics of the material, such as
the remarkable ductility, open different scenarios of use for the CLT panels in the
field of structural restoration of masonry buildings
Superconducting tunable flux qubit with direct readout scheme
We describe a simple and efficient scheme for the readout of a tunable flux
qubit, and present preliminary experimental tests for the preparation,
manipulation and final readout of the qubit state, performed in incoherent
regime at liquid Helium temperature. The tunable flux qubit is realized by a
double SQUID with an extra Josephson junction inserted in the large
superconducting loop, and the readout is performed by applying a current ramp
to the junction and recording the value for which there is a voltage response,
depending on the qubit state. This preliminary work indicates the feasibility
and efficiency of the scheme.Comment: 10 pages, 5 figure
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