Intelligent environment recognition and prediction for NDT inspection through autonomous climbing robot

This paper presents a novel approach to environment mapping prediction with focus on autonomous climbing robot to NDT (Non-Destructive Technique) inspection. In industrial installations, the inspection of non-planar surfaces requires that NDT probes passe on whole surface, while the autonomous robot navigates over an unknown environment based only on its perception abilities. However, the path planning of inspection is not a trivial task specially when there is no precise information about environment. In this work, a special kind of climbing robot is used to inspect large metallic surfaces such as spherical pressure vessels used to store Liquified Petroleum Gas (LPG). The robot has adherence skills that allow it to safely navigate through the internal and external surface of the vessel. As a result, robot mobility suffers from hard magnetic adhesion constraints. A new approach is proposed to environment detailed prediction, including specific characteristic (like weld beads and plates) of inspected surface. The goal is the automatic extraction of some environment characteristics to predict the storage tank dimensions and robot localization, based on a group of 3D perception sources (laser rangefinder, light detection and ranging and depth camera) mounted over a rolling platform to improve its reach. The environment prediction is carried out after the robot visually detects two or more weld beads corners. A multi-measuring environment is firstly build by Fuzzy data fusion of the different perception measurements allowing to estimate plates and weld beads based on design and safety standards. Virtual and real experiments are carried out to illustrate proposed method performance.     

Mass spectrometric characterization of high-valent metal-oxo, -peroxo and -peroxy intermediates of relevance in oxidation processes

The coupling of mass spectrometry with ionization techniques like electrospray ionization (ESI) or matrix-assisted matrix-assisted laser desorption-ionization (MALDI) offers many advantages over other well-established spectroscopic techniques employed for the investigation of intermediates or short-lived species in condensed-phase. In this review we describe some of the applications of mass spectrometry, in particular of ESI-MS to the detection and characterization of high-valent metal-oxo, -peroxo and -peroxy derivatives, crucial intermediates in the oxyfunctionalization of organic substrates. In addition, by utilizing gas-phase ion-molecule reactions and MS/MS experiments, information on the intrinsic reactivity of the short-lived intermediates may be obtained. The combined use of ESI-MS in association with other spectroscopic techniques and theoretical calculations is discussed as well.     

Intrinsic flame retardancy of poly(lactic acid) bead foams

Linear economy models are no longer acceptable for the plastic industry and a change to a sustainable circular plastic economy must take place. In the field of thermoplastic foams, the biopolymer poly(lactic acid) (PLA) is a suitable alternative for fossil based foams like polystyrene. However, the production of PLA bead foams is still a challenge. In regards to circular plastic economy products, a reduction of the needed polymer additives is aspired to simplify the union of end-of-life plastic streams. Flame retardants (FR) are required in many applications and are often the largest proportion of additives. It turns out that the removal of FRs, for example the removal of the REACh registered FR hexabromocyclododecane for polystyrene foams, requires a great effort. This paper shows that PLA bead foams require no FR to achieve a class E classification for construction products. Therefore, nine PLA types are analyzed by differential scanning calorimetry, thermogravimetric analysis, gel permeation chromatography, and rheotens measurements. From five types, PLA bead foams could be produced with two different densities. In addition, PLA bead foams containing 1.5 wt% alkoxy amine FR were produced. The flammability of the PLA bead foams was investigated by LOI, DIN-4102-1-B2, and cone calorimeter tests.     

Rheological properties of neat epoxy exposed to in‐service aerospace contaminants

We present an experimental study on the rheological properties of a commonly used epoxy resin system (EPIKOTE‐862 resin and EPIKURE‐W curing agent), exposed to a variety of fluids typical of aerospace operations (jet fuel, hydraulic fluids, deicing, detergents, etc.), for a period of up to 6 months, at room temperature for most conditions, and with no concurrent mechanical loading or prior degradation. The specimens were subjected to stress and frequency sweeps with a shear rheometer, while a limited set received also a temperature sweep in a range consistent with aircraft operations. Results indicate that the treated resin samples are linear viscoelastic under these testing conditions. The resin has reasonable chemical resistance to most contaminants of this study, with the exception of two commonly used detergents: an aircraft surface cleaning compound, Penair C5572, and a nonionic detergent, Methyl Ethyl Ketone (MEK). The durability change of the first compound appears triggered by high temperatures only, while the second compound causes a very drastic stiffness loss under several conditions. This drop of performance occurs within a 3‐months period, with no apparent color change or fracture that could prompt visual inspection and repair. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3961–3971, 2013     

Modularity as a fish (Xenotoca eiseni) views it: Conjoining geometric and nongeometric information for spatial reorientation.

When disoriented in a closed rectangular tank, fish (Xenotoca eiseni) reoriented in accord with the large-scale shape of the environment, but they were also able to conjoin geometric information with nongeometric properties such as the color of a wall or the features provided by panels located at the comers of the tank. Fish encoded geometric information even when featural information sufficed to solve the spatial task. When tested after transformations that altered the original arrangement of the panels, fish were more affected by those transformations that modified the geometric relationship between the target and the shape of the environment. Finally, fish appeared unable to use nongeometric information provided by distant panels. These findings show that a reorientation mechanism based on geometry is widespread among vertebrates, though the joint use of geometric and nongeometric cues by fish suggest that the degree of information encapsulation of the mechanism varies considerably between species. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Functional properties of subunit interactions in human cytidine deaminase

An intersubunit interactions study related to the active sitehas been performed on the wild-type cytidine deaminase (CDA)and on the mutant enzyme F137W/W113F. F137 is the homologousto the Bacillus subtilis CDA F125 involved in the subunit interactions.In the presence of SDS, wild-type human CDA dissociates intoenzymatically inactive monomers without intermediate forms viaa non-cooperative transition. Extensive dialysis or dilutionof the inactivated monomers restores completely the activity.Circular dichroism measurements show that the secondary/tertiarystructure organization of each subunit is unaffected by theSDS concentration, while the mutation Phe/Trp causes weakeningin quaternary structure. The presence of the strong human CDAcompetitive inhibitor 5-fluorozebularine disfavours dissociationof the tetramer into subunits in the wild-type CDA, but notin mutant enzyme F137W/W113F. The absence of tyrosine fluorescenceand the much higher quantum yield of the double mutant proteinspectrum suggest the occurrence of an energy transfer effectbetween the protein subunits. This assumption is confirmed bythe crystallographic studies on B.subtilis in which it is shownthat three different subunits concur with the formation of eachof the four active sites and that F125, homologous to the humanCDA F137, is located at the interface between two differentsubunits contributing to the formation of active site. Received February 10, 2003; revised October 14, 2003;; accepted October 21, 2003     

Synthesis of conducting polysiloxane — polypyrrole graft copolymers

Summary Polysiloxane-polypyrrole graft copolymers have been synthesized by a series of chemical reactions and subsequent electropolymerization. First, the hydrosilation of 4-vinyl aniline by dimethyl-methylhydrosiloxane copolymer gave the corresponding aminophenyl functional polydimethylsiloxane (PDMS-NH₂). The side chain pyrrole functionalized polysiloxanes were then prepared by the reaction of PDMS-NH₂ with glycidylpyrrole. Finally, the synthesis of graft copolymers of polysiloxane and pyrrole has been achieved electrochemically by using two different electrolytes, p-toluene sulfonic acid (PTSA) and tetrabutylammonium tetrafluoroborate (TBAFB). Characterization of these graft copolymers were performed by a combination of techniques consisting of scanning electron microscopy (SEM), thermal gravimetry (TGA), differential scanning calorimetry (DSC) analyses and FT-IR studies. The conductivities were measured by four-probe technique. Received: 19 September 2001/ Revised version: 4 December 2001/ Accepted: 2 December 2001     

Biomimetic formation of crystalline bone-like apatite layers on spongy materials templated by bile salts aggregates

Since the trabecular bone exhibit sponge-like bicontinuity there is a growing interest in the synthesis of spongy-like sieves for the construction of bio-active implantable materials. Here, we propose a one step sol–gel method for the synthesis of bicontinuous pore silica materials using different bile salts aqueous mixtures as templates. The influences of the type and amount of bile salt on the synthesis processes are investigated and correlated with the final material morphology. As a final point, their structural properties are interrelated with their ability to induce a bone-like apatite layer in contact with simulated body fluid (SBF). We have confirmed that under specific template conditions, the synthesized material has an open bio-active macropore structure that is blanched in a 3D-disordered sponge-like network similar than those existed in trabecular bone.     

Detergent impurity effect on recycled HDPE: Properties after repetitive processing

High density polyethylene (rHDPE) is extruded 1 to 8 times, with and without detergent, to simulate the effects of impurities on the material and on the artificial ageing process. The mechanical properties, thermal stability, rheology, Fourier transform infrared spectroscopy (FTIR), and volatile organic compound (VOC) emissions are measured. According to the results, ageing of rHDPE increases tensile strength, reduces elongation, and enhances side chain branching of the material and thus causes rheological changes. The addition of detergent reduces changes in mechanical properties and rheological behavior but accelerates thermal degradation. VOC and FTIR measurements of the samples with detergent addition show generation of harmful 1,4‐dioxane. The amount of total emission, as well as emissions of important perfumes limonene and 1R‐α‐pinene, decreases during multiple extrusion cycles. Heating of the plastics is found to be a major factor in the VOC emission reduction. Impurities have a notable effect on the artificial ageing results. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43766.