An Integrated Circuit Compatible Compact Package for Thermal Gas Flowmeters

An original packaging method suitable for integrated thermal mass flow sensors is presented. The method consists in the application of a plastic transparent adapter to the chip surface. The adapter is sealed to the chip surface by means of a thermal procedure. By this approach it is possible to selectively convey the fluid flow to reduced chip areas, avoiding contact with the pads. Fabrication and testing of a very compact flow sensor is described.Comment: Submitted on behalf of EDA Publishing Association (http://irevues.inist.fr/EDA-Publishing

Freezing of Nonlinear Bloch Oscillations in the Generalized Discrete Nonlinear Schrodinger Equation

The dynamics in a nonlinear Schrodinger chain in an homogeneous electric field is studied. We show that discrete translational invariant integrability-breaking terms can freeze the Bloch nonlinear oscillations and introduce new faster frequencies in their dynamics. These phenomena are studied by direct numerical integration and through an adiabatic approximation. The adiabatic approximation allows a description in terms of an effective potential that greatly clarifies the phenomenon.Comment: LaTeX, 7 pages, 6 figures. Improved version to appear in Phys. Rev.

Numerical investigation on the seismic performance of a RC framed building equipped with a novel Prestressed LEad Damper with Straight Shaft

This study aims at assessing the use of a novel damper, which is called the Prestressed LEad Damper with Straight Shaft (or PSLED), for the seismic rehabilitation of RC framed buildings. This device provides high energy dissipation by the friction activated between a lead core and a shaft and achieves a high specific output force by preloading the lead during the assembly. In order to show the effectiveness of the PS-LED device for the retrofit of existing buildings, a RC structure designed according to past codes that ignored seismic actions is retrofitted with the PS-LED system considering two different damage targets: (i) in the first case, the structure is retrofitted in order to behave elastically under the design earthquake; (ii) in the second case, a partially dissipative behavior of the structure is conceived, with activation of plastic hinges, and limited and reparable damage. In order to assess the suitability of the design procedure, non-linear static analyses are performed on the upgraded building, showing a satisfactory agreement between the seismic performance and the design target. Non-linear dynamic analyses are further carried out considering a suite of bidirectional artificial ground motions with response spectra matching on average the target spectrum according to the Italian Building Code for the life-safety limit state. Finally, a comparison is performed between the performances of the building retrofitted with the PS-LED device and the building retrofitted with a conventional steel hysteretic damper (SHD), demonstrating that the PS-LED, thanks to its superior damping capacity, limits the increase in internal forces that usually affects frames equipped with SHDs, reducing the need of local strengthening of the columns and foundations and consequently the total cost of the seismic rehabilitation

The thermodynamics of creating correlations: Limitations and optimal protocols

We establish a rigorous connection between fundamental resource theories at the quantum scale. Correlations and entanglement constitute indispensable resources for numerous quantum information tasks. However, their establishment comes at the cost of energy, the resource of thermodynamics, and is limited by the initial entropy. Here, the optimal conversion of energy into correlations is investigated. Assuming the presence of a thermal bath, we establish general bounds for arbitrary systems and construct a protocol saturating them. The amount of correlations, quantified by the mutual information, can increase at most linearly with the available energy, and we determine where the linear regime breaks down. We further consider the generation of genuine quantum correlations, focusing on the fundamental constituents of our universe: fermions and bosons. For fermionic modes, we find the optimal entangling protocol. For bosonic modes, we show that while Gaussian operations can be outperformed in creating entanglement, their performance is optimal for high energies.Comment: 12 pages, 6 figure

A discrete Schrodinger spectral problem and associated evolution equations

A recently proposed discrete version of the Schrodinger spectral problem is considered. The whole hierarchy of differential-difference nonlinear evolution equations associated to this spectral problem is derived. It is shown that a discrete version of the KdV, sine-Gordon and Liouville equations are included and that the so called `inverse' class in the hierarchy is local. The whole class of related Darboux and Backlund transformations is also exhibited.Comment: 14 pages, LaTeX2

Design and experimental assessment of a novel damper with high endurance to seismic loads

The study presents the design and the experimental characterization of a new energy dissipation device aimed at providing improved resistance to repeated seismic loads. Differently from conventional steel hysteretic dampers, which dissipate energy by yielding of a mild steel core and are noted to suffer low-cycle fatigue, the new damper provides energy dissipation by the friction that is activated between a moving shaft and a lead core prestressed within a tube. The prestress level is controlled during the assembling process, allowing to adjust the axial strength of the damper. Thanks to the ability of lead to restore its properties by static recrystallization taking place immediately after deformation, repeated cycles of loading do not produce damages that may accrue and eventually lead to failure of the device. Moreover, prestressing of the lead core allows to achieve high specific strength (i.e., high force to volume ratio), thereby providing low dimensions which help to reduce the architectural invasiveness. Prototypes of the damper were subjected to the test procedure established in the European standard EN 15129 for Displacement Dependent Devices, fulfilling the relevant requirements. The damper provides a robust and stable response over repeated cycles, characterized by essentially rectangular hysteresis loops with an equivalent viscous damping ratio ξeff of about 55%. Moreover, it shows low sensitivity of mechanical properties on the loading rate and the ability to withstand multiple cycles of motion at the design earthquake displacement without deterioration of performance, demonstrating maintenance-free operation in presence of repeated ground shakes. Its ability to survive several strong motions without being damaged, and its high damping capability coupled to a compact design and low manufacturing cost, are the distinctive features that make it suitable for social housing

3D numerical characterization of a dissipative connection system for retrofit of prefabricated existing RC sheds

Prefabricated industrial sheds featured a high seismic vulnerability during the 2012 Emilia earthquake (Italy). The buildings typically exhibited a rigid collapse mechanism that was a consequence of the loss of support between columns, beams and roof elements. The study presents a numerical characterization of a novel dissipative connection system (DCS) designed to improve the seismic performance of industrial sheds. The device, which is placed on the top of the columns, exploits the movement of a rigid body on a sloped surface to provide horizontal stiffness and control the lateral displacement of the beam. A 3D finite element model of the prototype is formulated in Abaqus and used to switch the backbone curve from the scaled model to the full-scale device. A parametric study is conducted to evaluate the influence of the slope of the contact surface and the coefficient of friction on the output force of the system. In the second part of the study, non-linear dynamic analyses are performed on a finite element model of a portal frame implementing, at beam-column joints, either the DCS or a pure friction connection. The results highlight the effectiveness of the DCS in controlling beam-to-column displacements, reducing shear forces on the top of columns, and limiting residual displacements that can accrue during ground motion sequence

ASSESSMENT OF THE SHEAR PROPERTIES OF HDRBS UNDER DIFFERENT COMPRESSION LEVELS

Despite it is well known that the shear properties of High Damping Rubber Bearings (HDRBs) are affected by the instantaneous compression load developed during the seismic ground motion, only permissible variations of their design properties with frequency, temperature and ageing are prescribed in the standards while the influence of the compression level is usually disregarded. Within this framework, this research addresses this drawback through both experimental and numerical investigations. In the first part of the study, small scale laminated isolators are tested on a custom biaxial machine in order to assess the secant modulus, and damping factor of the elastomeric compound under different compression levels. In the second part, the same phenomenon is investigated through cyclic shear tests on full scale HDRBs under three different levels of axial load. In the last part, a 3D finite element model of the isolator is eventually formulated in Abaqus FEM software. The mechanical response of the elastomer is simulated by means of a hyperelastic strain energy function combined with a relaxation function. The experimental results highlight the substantial influence of the axial load on the damping capacity of the elastomer, while the shear modulus is less affected. The numerical analyses demonstrate that the vertical – horizontal coupled response of HDRBs can be accurately predicted, within the proposed formulation, with constitutive parameters estimated from simple uniaxial tests

Scattering of Plane Waves in Self-Dual Yang-Mills Theory

We consider the classical self-dual Yang-Mills equation in 3+1-dimensional Minkowski space. We have found an exact solution, which describes scattering of $n$ plane waves. In order to write the solution in a compact form, it is convenient to introduce a scattering operator $\hat{T}$. It acts in the direct product of three linear spaces: 1) universal enveloping of $su(N)$ Lie algebra, 2) $n$-dimensional vector space and 3) space of functions defined on the unit interval.Comment: 16 pages, LaTeX fil