360° Snapshot Imaging with a Convex Array of Long-wave Infrared Cameras

Long-wave infrared imaging systems remain prohibitively expensive for many high-pixel-count applications, such as panoramic imaging. We present a computational imaging solution which allows for low-cost, 360° long-wave infrared panoramic imaging at video rate

Comparison of tensile strength and fracture toughness of co-bonded and cold-bonded carbon fiber laminate-aluminum adhesive joints

The purpose of this work is to compare the co-bonding vs. cold-bonding route on the adhesive joint performance of a CFRP (Carbon Fiber Reinforced Polymer) laminate–aluminum connection. In particular, the overlap shear, tensile strength and Mode I and Mode II fracture toughness will be evaluated. The adhesives for co-bonding and cold-bonding are, respectively, a thermosetting modified epoxy, unsupported structural film and a two-component epoxy adhesive, chosen as representative of applications in the high-performance/race car field. The emerging trend is that, in tensile e Mode I fracture tests, the failure path is predominantly in the composite. Mode II fracture tests instead resulted in a cohesive fracture, meaning that, under pure shear loading, the weakest link may not be the composite. The lap-shear tests are placed midway (cohesive failure for co-bonding and composite delamination for cold-bonding, respectively), probably due to the different peel stress values related to the different adhesive Young’s modulus. The exploitation of the full capacity of the adhesive joint, hence the possibility of highlighting better, different performances of co-bonding vs. cold-bonding, would require consistent improvement of the out-of-plane strength of the CFRP laminate and/or to someway redistribute the peel stress on the bondline

Spatially-resolved spectrophotometric analysis and modelling of the Superantennae

We have performed spatially-resolved spectroscopy of the double-nucleated Ultra-Luminous Infrared Galaxy IRAS 19254-7245, ``the Superantennae'', along the line connecting the two nuclei. These data are analysed with a spectral synthesis code, to derive the star formation and extinction properties of the galaxy. The star formation history (SFH) of the two nuclei is similarly characterized by two different main episodes: a recent burst, responsible of the observed emission lines, and an older one, occurred roughly 1 Gyr ago. We tentatively associate this bimodal SFH with a double encounter in the dynamical history of the merger. We have complemented our study with a detailed analysis of the broad band spectral energy distribution of the Superantennae, built from published photometry, providing the separate optical-to-mm SEDs of the two nuclei. Our analysis shows that: a) the southern nucleus is responsible for about 80% of the total infrared luminosity of the system, b) the L-band luminosity in the southern nucleus is dominated by the emission from an obscured AGN, providing about 40 to 50% of the bolometric flux between 8 and 1000 microns; c) the northern nucleus does not show evidence for AGN emission and appears to be in a post-starburst phase. As for the relative strengths of the AGN and starburst components, we find that, while they are comparable at FIR and sub-mm wavelengths, in the radio the Sy2 emission dominates by an order of magnitude the starburst.Comment: 18 pages. Accepted for publication on A&

Geometrical Calibration for the Panrover: a Stereo Omnidirectional System for Planetary Rover

Abstract. A novel panoramic stereo imaging system is proposed in this paper. The system is able to carry out a 360° stereoscopic vision, useful for rover autonomous-driving, and capture simultaneously a high-resolution stereo scene. The core of the concept is a novel "bifocal panoramic lens" (BPL) based on hyper hemispheric model (Pernechele et al. 2016). This BPL is able to record a panoramic field of view (FoV) and, simultaneously, an area (belonging to the panoramic FoV) with a given degree of magnification by using a unique image sensor. This strategy makes possible to avoid rotational mechanisms. Using two BPLs settled in a vertical baseline (system called PANROVER) allows the monitoring of the surrounding environment in stereoscopic (3D) mode and, simultaneously, capturing an high-resolution stereoscopic images to analyse scientific cases, making it a new paradigm in the planetary rovers framework.Differently from the majority of the Mars systems which are based on rotational mechanisms for the acquisition of the panoramic images (mosaicked on ground), the PANROVER does not contain any moving components and can rescue a hi-rate stereo images of the context panorama.Scope of this work is the geometric calibration of the panoramic acquisition system by the omnidirectional calibration methods (Scaramuzza et al. 2006) based on Zhang calibration grid. The procedures are applied in order to obtain well rectified synchronized stereo images to be available for 3D reconstruction. We applied a Zhang chess boards based approach even during STC/SIMBIO-SYS stereo camera calibration (Simioni et al. 2014, 2017). In this case the target of the calibration will be the stereo heads (the BPLs) of the PANROVER with the scope of extracting the intrinsic parameters of the optical systems. Differently by previous pipelines, using the same data bench the estimate of the extrinsic parameters is performed

Characterisation of an urban bridge portfolio and multi-risk prioritisation accounting for deterioration and seismic vulnerability

This contribution proposes a procedure to prioritise retrofit interventions on stocks of bridges according to their seismic vulnerability. The procedure also combines a previously presented approach to evaluate deterioration effects on bridges at a territorial scale. Thereby, the combi-nation of the two approaches provides a multi-risk classification method for bridge stocks. This method also allows refined prioritisation within each class, based on the proposed quantitative indices and on multicriteria decision-making methods. The method was applied to the bridge stock managed by the municipality of Padova, in North-East Italy. First, an extensive charac-terisation of the analysed stock is provided, according to typological, geometric, and structural parameters. Then, the application of the combined approach is presented, highlighting which bridge types resulted more vulnerable to either seismic actions or deterioration effects