Event-Triggered Observers and Observer-Based Controllers for a Class of Nonlinear Systems

In this paper, we investigate the stabilization of a nonlinear plant subject to network constraints, under the assumption of partial knowledge of the plant state. The event triggered paradigm is used for the observation and the control of the system. Necessary conditions, making use of the ISS property, are given to guarantee the existence of a triggering mechanism, leading to asymptotic convergence of the observer and system states. The proposed triggering mechanism is illustrated in the stabilization of a robot with a flexible link robot.Comment: Proceedings of the 2015 American Control Conference - ACC 201

Soft-gluon resummation effects on parton distributions

We gauge the impact of soft-gluon resummation on quark distributions by performing a simple fit of Deep Inelastic Scattering structure function data using next-to-leading order (NLO) and next-to-leading-logarithmic (NLL)-resummed coefficient functions. We make use of NuTeV charged-current data, as well as New Muon Collaboration (NMC) and Bologna-CERN-Dubna-Munich-Saclay (BCDMS) neutral-current results, which probe large values of x. Our results suggest that the inclusion of resummation effects in global fits of parton distributions is both feasible and desirable, in order to achieve at large x the accuracy goals of the LHC physics program.Comment: 19 pages, 10 figures. Few changes after referee report, one figure and references added, published versio

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

NONLINEAR NON-LOCAL BOUNDARY-VALUE PROBLEMS AND PERTURBED HAMMERSTEIN INTEGRAL EQUATIONS

AbstractMotivated by some non-local boundary-value problems (BVPs) that arise in heat-flow problems, we establish new results for the existence of non-zero solutions of integral equations of the form$$u(t)=\gamma(t)\alpha[u]+\int_{G}k(t,s)f(s,u(s))\,\mathrm{d}s,$$where $G$ is a compact set in $\mathbb{R}^{n}$. Here $\alpha[u]$ is a positive functional and $f$ is positive, while $k$ and $\gamma$ may change sign, so positive solutions need not exist. We prove the existence of multiple non-zero solutions of the BVPs under suitable conditions. We show that solutions of the BVPs lose positivity as a parameter decreases. For a certain parameter range not all solutions can be positive, but for one of the boundary conditions we consider we show that there are positive solutions for certain types of nonlinearity. We also prove a uniqueness result

Microwave intermodulation distortion of MgB2 thin films

The two tone intermodulation arising in MgB2 thin films deposited in-situ by planar magnetron sputtering on sapphire substrates is studied. Samples are characterised using an open-ended dielectric puck resonator operating at 8.8 GHz. The experimental results show that the third order products increase with the two-tone input power with a slope ranging between 1.5 and 2.3. The behaviour can be understood introducing a mechanism of vortex penetration in grain boundaries as the most plausible source of non linearities in these films. This assumption is confirmed by the analysis of the field dependence of the surface resistance, that show a linear behaviour at all temperatures under test.Comment: 13 pages, 3 figures; to be published in Appl. Phys. Let

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

Improvement of the esca index for the evaluation of ecological quality of coralligenous habitat under the european framework directives

The ESCA (Ecological Status of Coralligenous Assemblages) index was recently developed to evaluate the ecological quality of coralligenous habitat. The study aims to improve the first index proposal through testing response to different sources of anthropogenic pressures and optimizing the sampling effort. ESCA was calculated on 14 sites and tested against a gradient of human pressures. Moreover, the main scales of spatial variability of assemblages were evaluated and values of index obtained with different sampling designs were compared. Results showed that studied sites resulted in high, good or moderate ecological status, according to an increasing gradient of the anthropization level. Values of ESCA index obtained with different methods have been compared and photographic method provides EQR values lower than destructive method. Spatial variability of assemblages was higher at large and small scales than at intermediate ones. Two locations for each study site and 20 replicated samples for each location may be consider the best sampling combination providing reliable values of ESCA index for the evaluation of ecological quality of coralligenous assemblages