Polymer-based composites reinforced with nanocarbonaceous materials can be tailored for functional applications. Poly(vinylidene fluoride) (PVDF) reinforced with carbon nanotubes (CNT) or graphene with different filler contents have been developed as potential piezoresistive materials. The mechanical properties of the nanocomposites depend on the PVDF matrix, filler type, and filler content. PVDF 6010 is a relatively more ductile material, whereas PVDF-HFP (hexafluropropylene) shows larger maximum strain near 300% strain for composites with CNT, 10 times higher than the pristine polymer. This behavior is similar for all composites reinforced with CNT. On the other hand, reduced graphene oxide (rGO)/PVDF composites decrease the maximum strain compared to neat PVDF. It is shown that the use of different PVDF copolymers does not influence the electrical properties of the composites. On the other hand, CNT as filler leads to composites with percolation threshold around 0.5 wt.%, whereas rGO nanocomposites show percolation threshold at ≈ 2 wt.%. Both nanocomposites present excellent linearity between applied pressure and resistance variation, with pressure sensibility (PS) decreasing with applied pressure, from PS ≈ 1.1 to 0.2 MPa−1. A proof of concept demonstration is presented, showing the suitability of the materials for industrial pressure sensing applications.

An easy way to achieve higher depth of field in a camera-laser configuration is to tilt the image sensor respect to the lens plane, such that the image plane, laser plane and the lens plane intersect in a unique line (Scheimpflug condition [1]). If something has to be measured with this kind of cameras, a proper camera calibration must be done. The usual calibration methods are not valid in this case because they are based on the pin-hole camera model, this model being valid only for normal cameras, i.e. cameras that have the image plane and the lens plane parallel. Thus, a new camera model and its respective calibration must be developed, which includes the Scheimplug angle in the intrinsic camera parameters. In this article, the new camera model and its calibration are defined. Experimental results indicate that using this calibration cameras under Scheimpflug condition can be accurately calibrated.

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It is believed that the acoustic emissions (AE) signal contains potentially valuable information for monitoring precision cutting processes, as well as to be employed as a control feedback signal. However, AE stress waves produced in the cutting zone are distorted by the transmission path and the measurement systems. In this article, a bicepstrum based blind system identification technique is proposed as a valid tool for estimating both, transmission path and sensor impulse response. Assumptions under which application of bicepstrum is valid are discussed and diamond turning experiments are presented, which demonstrate the feasibility of employing bicepstrum for AE blind identification. r