Drilled by the jet? XMM-Newton discovers a Compton-thick AGN in the GPS galaxy Mkn668

We report the XMM-Newton discovery of the first Compton-thick obscured AGN in a Broad Line Radio Galaxy, the Gigahertz Peaked-Spectrum source Mkn668 (OQ+208). The remarkably flat 2-10 keV X-ray spectrum (observed photon index, \Gamma ~ 0.7), alongside with a prominent iron K-alpha fluorescent emission line, is a clear signature of a Compton-reflection dominated spectrum. Mkn688 represents a remarkable example of discrepancy between X-ray spectral properties and optical classification, as its optical spectrum is characterized by broad and asymmetric Balmer lines. The obscuring matter is constrained to be located within the radio hotspots, in turn separated by about 10 pc. If the jets are piercing their way through a Compton-thick medium pervading the nuclear environment, one could be largely underestimating the radio activity dynamical age determined from the observed hotspot recession velocity. The soft X-ray spectrum is dominated by a much steeper component, which may be due to nuclear continuum electron scattering, or inverse Compton of the - remarkably large - far infrared emission. Soft X-rays are suppressed by a further Compton-thin (N_H ~ 10^21/cm/cm) absorbing system, that we identify with matter responsible for free-free absorption of the radio lobes.Comment: 11 pages, 7 figures, To appear in Astronomy & Astrophysic

A multisensing setup for the intelligent tire monitoring

The present paper offers the chance to experimentally measure, for the first time, the internal tire strain by optical fiber sensors during the tire rolling in real operating conditions. The phenomena that take place during the tire rolling are in fact far from being completely understood. Despite several models available in the technical literature, there is not a correspondently large set of experimental observations. The paper includes the detailed description of the new multi-sensing technology for an ongoing vehicle measurement, which the research group has developed in the context of the project OPTYRE. The experimental apparatus is mainly based on the use of optical fibers with embedded Fiber Bragg Gratings sensors for the acquisition of the circumferential tire strain. Other sensors are also installed on the tire, such as a phonic wheel, a uniaxial accelerometer, and a dynamic temperature sensor. The acquired information is used as input variables in dedicated algorithms that allow the identification of key parameters, such as the dynamic contact patch, instantaneous dissipation and instantaneous grip. The OPTYRE project brings a contribution into the field of experimental grip monitoring of wheeled vehicles, with implications both on passive and active safety characteristics of cars and motorbikes

Sensitivity of GNSS-R spaceborne observations to soil moisture and vegetation

Global navigation satellite systems-reflectometry (GNSS-R) is an emerging remote sensing technique that makes use of navigation signals as signals of opportunity in a multistatic radar configuration, with as many transmitters as navigation satellites are in view. GNSS-R sensitivity to soil moisture has already been proven from ground-based and airborne experiments, but studies using space-borne data are still preliminary due to the limited amount of data, collocation, footprint heterogeneity, etc. This study presents a sensitivity study of TechDemoSat-1 GNSS-R data to soil moisture over different types of surfaces (i.e., vegetation covers) and for a wide range of soil moisture and normalized difference vegetation index (NDVI) values. Despite the scattering in the data, which can be largely attributed to the delay-Doppler maps peak variance, the temporal and spatial (footprint size) collocation mismatch with the SMOS soil moisture, and MODIS NDVI vegetation data, and land use data, experimental results for low NDVI values show a large sensitivity to soil moisture and a relatively good Pearson correlation coefficient. As the vegetation cover increases (NDVI increases) the reflectivity, the sensitivity to soil moisture and the Pearson correlation coefficient decreases, but it is still significant.Postprint (author's final draft

Range-only underwater target localization : error characterization

Locating a target from range measurements using only one mobile transducer has been increased over the last years. This method allows us to reduce the high costs of deployment and maintenance of traditional fixed systems on the seafloor such as Long Baseline. The range-only single-beacon is one of the new architectures developed using the new capabilities of modern acoustic underwater modems, which can be time synchronization, time stamp, and range measurements. This document presents a method to estimate the sources of error in this type of architecture so as to obtain a mathematical model which allows us to develop simulations and study the best localization algorithms. Different simulations and real field tests have been carried out in order to verify a good performance of the model proposed.Postprint (published version