Application of eddy current inversion technique to the sizing of defects in Inconel welds with rough surfaces

This paper evaluates the applicability of eddy current inversion techniques to the sizing of defects in Inconel welds with rough surfaces. For this purpose, a plate Inconel weld specimen, which models the welding of a stub tube in a boiling water nuclear reactor is fabricated, and artificial notches machined into the specimen. Eddy current inspections using six different eddy current probes are conducted and efficiencies were evaluated for the six probes for weld inspection. It is revealed that if suitable probes are applied, an Inconel weld does not cause large noise levels during eddy current inspections even though the surface of the weld is rough. Finally, reconstruction of the notches is performed using eddy current signals measured using the uniform eddy current probe that showed the best results among the six probes in this study. A simplified configuration is proposed in order to consider the complicated configuration of the welded specimen in numerical simulations. While reconstructed profiles of the notches are slightly larger than the true profiles, quite good agreements are obtained in spite of the simple approximation of the configuration, which reveals that eddy current testing would be an efficient non-destructive testing method for the sizing of defects in Inconel welds.     

K?ln-Timi?oara Molecular Activity Combined Models toward Interspecies Toxicity Assessment

Aiming to provide a unified picture of computed activity – quantitative structure activity relationships, the so called Köln (ESIP-ElementSpecificInfluenceParameter) model for activity and Timisoara (Spectral-SAR) formulation of QSAR were pooled in order to assess the toxicity modeling and inter-toxicity correlation maps for aquatic organisms against paradigmatic organic compounds. The Köln ESIP model for estimation of a compound toxicity is based on the experimental measurement expressing the direct action of chemicals on the organism Hydractinia echinata so that the structural influence parameters are reflected by the metamorphosis degree itself. As such, the calculation of the structural parameters is absolutely necessary for correct evaluation and interpretation of the evolution of M(easured) and the C(computed) values. On the other hand, the Timişoara Spectral-SAR analysis offers correlation models and paths for H.e. species as well as for four other different organisms with which the toxicity may be inter-changed by means of the same mechanism of action induced by certain common chemicals.     

Synthesis of ABC miktoarm star block copolymers from a new heterotrifunctional initiator by combination of ATRP and ROP

We described the obtention of well-defined ABC star block copolymers through the use of a new heterotrifunctional initiator. That way, well-defined PCL-arm–PS-arm–PLLA star block copolymers have been synthesized from a heterotrifunctional initiator bearing two hydroxyl groups able to initiate ROP of CL and LLA (using Sn(Oct)₂ as coinitiator) and a bromide function able to initiate ATRP of styrene.     

Scale Selection for Compact Scale-Space Representation of Vector-Valued Images

This paper investigates the scale selection problem for nonlinear diffusion scale-spaces. This topic comprises the notions of localization scale selection and scale space discretization. For the former, we present a new approach. It aims at maximizing the image content’s presence by finding the scale that has a maximum correlation with the noise-free image. For the latter, we propose to adapt the optimal diffusion stopping time criterion of Mrázek and Navara in such a way that it may identify multiple scales of importance.     

Syntheses of pyrazole monomers

(1-Phenyl-5-methyl-pyrazolyl-4)-acetylene was prepared by treating 1-phenyl-4-acetyl-5-methyl-pyrazole with Vilsmeier complex. During the first stage of the reaction the β-(1-phenyl-5-methyl-pyrazolyl-4)-β-chloro-acroleine separated, and suffered in the presence of alkali a dechloroformylation to form the ethinylic compound. As the acroleine intermediate is an α,β-unsaturated aldehyde it can react with substituted hydrazines leading to substituted pyrazoline derivatives. The structures of the monomers were confirmed by means of IR and NMR spectral measurements. In the presence of PdCl₂ as catalyst, oligomers were obtained which have then been transformed into charge transfer-complexes. Variation of the ESR signal intensity was followed as a function of A/D ratio.     

Scalable general high voltage MOSFET model including quasi-saturation and self-heating effects

In this work, we present for the first time, a highly scalable general high voltage MOSFET model, which can be used for any high voltage MOSFET with extended drift region. This model includes physical effects like the quasi-saturation, impact-ionization and self-heating, and a new general model for drift resistance. The model is validated on the measured characteristics of two widely used high voltage devices in the industry i.e. LDMOS and VDMOS devices, and implemented on commercial circuit simulators like SABER (Synopsys), ELDO (Mentor Graphics), Spectre (Cadence) and UltraSim (Cadence). The accuracy of the model is better than 10% for DC I–V and g–V characteristics and shows good behavior for all capacitances which are unique for these devices showing peaks and shift of peaks with bias variation. The model also exhibits excellent scalability with transistor width, drift length, number of fingers and temperature.     

A Dedicated On-Board Dual-Energy Computer Tomograph

A dedicated on-board dual energy computer tomograph able to generate both tomographic and digital radiographic images of unconsolidated sediments cores with a diameter up to 12 cm and a height up to 1 m was built and tested on-board of the R/V Mare Nigrum. This instrument, designed to be used on-board of any oceanographic research vessel with minimum adaptations, can work very well on stationary laboratory too, provided that there is adequate protection against hard X-rays. The tomograph has a single 160 kV X-ray tube and two set of 240 in-line X-ray detectors separated by a copper attenuator (dual-energy arrangement) allowing one to obtain tomographic as well as digital radiographic images depicting the distribution of both density and effective atomic number of the objects. In tomographic and radiographic mode, the spatial resolution of reconstructed images of the linear attenuation coefficient is about 0.5 mm while in dual-energy mode, when reconstructed images depict the distribution of densities and effective atomic numbers that requires an additional smoothing filtering, the spatial resolution is about 1 mm.     

On the representative volume element of asphalt concrete at low temperature

The feasibility of characterizing asphalt mixtures’ rheological and failure properties at low temperatures by means of the Bending Beam Rheometer (BBR) is investigated in this paper. The main issue is the use of thin beams of asphalt mixture in experimental procedures that may not capture the true behavior of the material used to construct an asphalt pavement.For the rheological characterization, three-point bending creep tests are performed on beams of different sizes. The beams are also analyzed using digital image analysis to obtain volumetric fraction, average size distribution, and spatial correlation functions. Based on the experimental results and analyses, it is concluded that representative creep stiffness values of asphalt mixtures can be obtained from testing at least three replicates of the thin (BBR) mixture beams.Failure properties are investigated by performing strength tests using a modified Bending Beam Rheometer (BBR), capable of applying loads at different loading rates. Histogram testing of BBR mixture beams and of larger beams is performed and the failure distribution is analyzed based on the size effect theory for quasibrittle materials. Different Weibull moduli are obtained from the two specimens sizes, which indicates that BBR beams do not capture the representative volume element (RVE) of the material.     

Design and characterization of polypropylene matrix/glass fibers composite materials

In this article, polymer composites based on polypropylene (PP) matrix reinforced with short glass fibers type E (GF‐type E) were obtained. However, to ensure good interfacial adhesion and stress transfer across the interface, the influence of the chemical functionalization of the phases was analyzed. The better interfacial adhesion is assured by the use of maleic anhydride grafted PP and amino‐functionalized GF. The obtained composite materials were tested from the point of view of composition, morphology, and mechanical properties. It can conclude that the chemical functionalization of the two phases is beneficial from the point of view of compatibility of the phases and consequently higher mechanical properties are obtained. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42163.