A New Insight on Phased Array Ultrasound Inspection in MIG/MAG Welding

Weldment inspection is a critical process in the metal industry. It is first conducted visually, then manually and finally using instrumental techniques such as ultrasound. We made one hundred metal inert/active gas (MIG/MAG) weldments on plates of naval steel S275JR+N with no defects, and inducing pores, slag intrusion and cracks. With the objective of the three-dimensional reconstruction of the welding defects, phased array ultrasound inspections were carried out. Error-free weldment probes were used to provide the noise level. The results can be summarized as follows. (i) The top view obtained from the phased array provided no conclusive information about the welding defects. The values of the echo amplitudes were about 70 mV for pores and cracks, and greater than 150 mV for slag intrusion, all of which showed great variability. (ii) The sectional data did not lie at the same depths and they needed to be interpolated. (iii) The interpolated sectional views, or C-scans, allowed the computation of top views at any depth, as well as the three-dimensional reconstruction of the defects. (iv) The use of the simplest tool, consisting of the frequency histogram and its statistical moments, was sufficient to classify the defects. The mean echo amplitudes were 33 mV for pores, 72.16 mV for slag intrusion and 43.19 mV for cracks, with standard deviations of 8.84 mV, 24.64 mV and 12.39 mV, respectively. These findings represent the first step in the automatic classification of welding defects.This research was funded by CEI.MAR Cadiz, 2020-PR003

On the Prediction of Upwelling Events at the Colombian Caribbean Coasts from Modis-SST Imagery

The upwelling cores on the Caribbean Colombian coasts are mainly located at the Peninsula de la Guajira and Cabo de la Aguja. We used monthly averaged Moderate Resolution Imaging Spectroradiometer (MODIS) sea surface temperature as the only information to build up a prediction model for the upwelling events. This comprised two steps: (i) the reduction of the complexity by means of the Karhunen–Loève transform and (ii) a prediction model of time series. Two prediction models were considered: (a) a parametric autoregressive-moving average (ARMA) time series from the Box–Jenkins methodology and (b) a harmonic synthesis model. The harmonic synthesis also comprised of two steps: the maximum entropy spectral analysis and a least-squares harmonic analysis on the set of frequencies. The parametric ARMA time series model failed at the time of prediction with a very narrow range, and it was quite di cult to apply. The harmonic synthesis allowed prediction with a horizon of six months with a correlation of about 0.80. The results can be summarized using the time series of the weights of the di erent oscillation modes, their spatial structures with the nodal lines, and a high confidence model with a horizon of prediction of about four months

Advanced Comparison of Phased Array and X-rays in the Inspection of Metallic Welding

The most common nondestructive weld inspection technique is X-rays and, since a few years ago, the ultrasound-based phased array. Their comparison has been done from the top view of both, with the result that the phased array is much more efficient in discovering flaws. From the last studies of the authors, a welding flaw can be three-dimensionally reconstructed from the sectorial phased array information. The same methodology is applied to compare quantitatively X-rays and phased array on 15 metal inert/active (MIG/MAG) welding specimens covering pores, slag intrusion and cracks. The results can be summarized in the correlation of the top views and in the correlation profiles between the X-ray top-view and the reconstructed top-view at the depths from phased array in the weld. The maximum correlation is the depth when the flaw in the X-ray looks like that in the phased array records at some depth, leading to an effective quantitative comparison of X-rays and phased array

Determination of jet calibration and energy resolution in proton–proton collisions at √s = 8 TeV using the ATLAS detector

Artículo escrito por un elevado número de autores, solo se referencian el que aparece en primer lugar, el nombre del grupo de colaboración, si le hubiere, y los autores pertenecientes a la UAMThe jet energy scale, jet energy resolution, and their systematic uncertainties are measured for jets reconstructed with the ATLAS detector in 2012 using proton–proton data produced at a centre-of-mass energy of 8 TeV with an integrated luminosity of 20 fb−1. Jets are reconstructed from clusters of energy depositions in the ATLAS calorimeters using the anti-kt algorithm. A jet calibration scheme is applied in multiple steps, each addressing specific effects including mitigation of contributions from additional proton–proton collisions, loss of energy in dead material, calorimeter non-compensation, angular biases and other global jet effects. The final calibration step uses several in situ techniques and corrects for residual effects not captured by the initial calibration. These analyses measure both the jet energy scale and resolution by exploiting the transverse momentum balance in γ + jet, Z + jet, dijet, and multijet events. A statistical combination of these measurements is performed. In the central detector region, the derived calibration has a precision better than 1% for jets with transverse momentum 150 GeV < pT < 1500 GeV, and the relative energy resolution is (8.4 ± 0.6)% for pT = 100 GeV and (23 ± 2)% for pT = 20 GeV. The calibration scheme for jets with radius parameter R = 1.0, for which jets receive a dedicated calibration of the jet mass, is also discusse

Ticuna Ceramics Amidst the Expansion of Illicit Coca: Rendering New Relations

In Ticuna communities across Amazonia, ceramics are useful objects employed for cooking and storage. Their practical importance, however, does not describe the extent of their significance. In the following article, we consider Ticuna ceramics and ceramic-making practices as a means of studying the changes set in motion by the transformation of Ticuna ancestral lands in Peru’s lowland Amazonian region into zones of illicit coca cultivation. Drawing on mixed-methods ethnographic research, including participant observation, interviews, and a participatory film project focused on ceramic production, we evaluate contemporary practices of ceramic-making within three Peruvian Ticuna communities in the context of these transformations, and the national government’s subsequent responses to the coca situation. Ceramics are a starting point to explore a complex web of relations as Ticuna communities intersect with both drug-trafficking operations and agents of the Peruvian state

Search for squarks and gluinos in final states with hadronically decaying τ-leptons, jets, and missing transverse momentum using pp collisions at √s=13 TeV with the ATLAS detector

Artículo escrito por un elevado número de autores, solo se referencian el que aparece en primer lugar, el nombre del grupo de colaboración, si le hubiere, y los autores pertenecientes a la UA

Properties of g → bЪ at small opening angles in pp collisions with the ATLAS detector at √s=13 TeV

Artículo escrito por un elevado número de autores, solo se referencian el que aparece en primer lugar, el nombre del grupo de colaboración, si le hubiere, y los autores pertenecientes a la UA

Search for heavy charged long-lived particles in the ATLAS detector in 36.1 fb−1 of proton-proton collision data at √ s = 13 TeV

Artículo escrito por un elevado número de autores, solo se referencian el que aparece en primer lugar, el nombre del grupo de colaboración, si le hubiere, y los autores pertenecientes a la UA