Residual Stress Pattern Prediction in Spray Transfer Multipass Welding by Means of Numerical Simulation

One of the main problems of gas metal arc welding (GMAW) process is the generation of residual stresses (RS), which has a direct impact on the mechanical performance of welded components. Nevertheless, RS pattern prediction is complex and requires the simulation of the welding process. Consequently, most of the currently used dimensioning approaches do not consider RS, leading to design oversized structures. This fact is especially relevant in big structures since it generates high material, manufacturing and product transportation costs. Nowadays, there are different numerical methods to predict the RS generated in GMAW process, being Goldak’s method one of the most widely used model. However, the use of these methods during the design process is limited, as they require experimentally defining many parameters. Alternatively, in this chapter, a new methodology to define the heat source energy based on the spray welding physics is exposed. The experimental validation of the methodology conducted for a multipass butt weld case shows good agreement in both the temperature pattern (9.16% deviation) and the RS pattern (42 MPa deviation). Finally, the proposed methodology is extended to analyse the influence of the thickness and the number of passes in the RS pattern of thick T-joint welds

Procedure to predict residual stress pattern in spray transfer multipass welding

Gas metal arc welding (GMAW) is one of the most used joining method in the industry. However, one of the main problems of this process is the generation of residual stresses which have direct impact on the fatigue life of welded components. Nevertheless, residual stress pattern prediction is complex and requires the simulation of the welding process. Currently, there are different numerical methods to predict the residual stresses generated in GMAW process, being Goldak’s method one of the most widely used model. However, the main limitation of these methods is that they require defining many parameters experimentally and, consequently, this method is not valid during design process. Alternatively, in this work, it is developed a procedure where the heat source is defined based on the welding physics for spray transfer welding. The developed procedure has been validated for a spray transfer multipass butt weld case. Results have shown good correspondence with an average deviation of 9.16 % in thermal field and 42 MPa in the final residual stress field. Thus, the developed procedure has been validated as a cost-effective alternative method to estimate residual stress pattern in spray transfer multipass welding. Furthermore, the developed method does not require any welding experimental characterization once the efficiency of the used welding machine is defined. The proposed method can be used as a valid tool to optimize the welding process in order to minimize the residual stress field and, consequently, improve the fatigue life

Automation of Simulation Based Design Validation and Reporting of a Valve Family

Valves are mechanical devices for controlling fluid-flow in pipes of different diameter and service pressures used in several industry sectors. Most demanding industry sectors add custom design requirements and require product validation reports many times even before placing valve purchase orders of varying quantities. Therefore, customer and valve developer requirements must be made compatible, design reliably completed and a design validation report created, all as soon as possible. In order to respond to these market constraints, complete valve design process from product planning to product design and validation delivery must be optimized. This paper reports a 96% time reduction in Simulation Based Design validation and reporting tasks obtained by applying Design Automation in a company that develops valves for this market. Additionally, the architecture and most remarkable features of the Simulation Based Design validation and reporting automation are described

Trastorno por déficit de atención e hiperactividad (TDAH). Pautas para el profesorado.

El presente trabajo tiene como objetivo profundizar en el trastorno por déficit de atención e hiperactividad (TDAH). Este trastorno se caracteriza por tener una alta prevalencia en la edad escolar y se manifiesta en dos categorías principales: inatención e hiperactividad-impulsividad. Partiendo de una revisión teórica sobre los principales elementos que lo definen, se analizan los impactos educativos que conlleva y las estrategias docentes a tener en cuenta para su mejora. En el capítulo I, se expone una aproximación al trastorno teniendo en cuenta los dos sistemas internacionales de clasificación más utilizados en la actualidad, el CIE-10 y el DSM-V. Se aborda su prevalencia, la comorbilidad con otros trastornos y el tipo de intervención que guía su tratamiento. En un segundo capítulo, se estudia el impacto en el rendimiento académico, en las relaciones sociales y en el autoconcepto de los alumnos con TDAH. Para terminar, se proponen algunas de las técnicas o estrategias cognitivo-conductuales que el profesorado puede utilizar para paliar los efectos negativos del trastorno. El tratamiento multimodal, que incluye de manera simultánea intervención psicoeducativa y farmacológica se presenta como el de mayor efectividad. En esta línea, se facilitan pautas para que el profesorado pueda trabajar desde el aula con el fin de dar respuesta a las necesidades educativas que manifiestan los alumnos con TDAH

Double-tailed lipid modification as a promising candidate for oligonucleotide delivery in mammalian cells

Background The potential use of nucleic acids as therapeutic drugs has triggered the quest for oligonucleotide conjugates with enhanced cellular permeability. To this end, the biophysical aspects of previously reported potential lipid oligodeoxyribonucleotide conjugates were studied including its membrane-binding properties and cellular uptake. Methods These conjugates were fully characterized by MALDI-TOF mass spectrometry and HPLC chromatography. Their ability to insert into lipid model membrane systems was evaluated by Langmuir balance and confocal microscopy followed by the study of the internalization of a lipid oligodeoxyribonucleotide conjugate bearing a double-tail lipid modification (C28) into different cell lines by confocal microscopy and flow cytometry. This compound was also compared with other lipid containing conjugates and with the classical lipoplex formulation using Transfectin as transfection reagent. Results This double-tail lipid modification showed better incorporation into both lipid model membranes and cell systems. Indeed, this lipid conjugation was capable of inserting the oligodeoxyribonucleotide into both liquid-disordered and liquid-ordered domains of model lipid bilayer systems and produced an enhancement of oligodeoxyribonucleotide uptake in cells, even better than the effect caused by lipoplexes. In addition, in β2 integrin (CR3) expressing cells this receptor was directly involved in the enhanced internalization of this compound. Conclusions All these features confirm that the dual lipid modification (C28) is an excellent modification for enhancing nucleic acid delivery without altering their binding properties. General significance Compared to the commercial lipoplex approach, oligodeoxyribonucleotide conjugation with C28 dual lipid modification seems to be promising to improve oligonucleotide delivery in mammalian cells.This work was supported with funds from the Spanish Ministry of Economy [Grant BFU2007-62062], the Basque Government [GIV06-42], the Spanish Ministry of Education [Grant CTQ2010-20541], the Generalitat de Catalunya [2009/SGR/208], the Instituto de Salud Carlos III [CB06_01_0019] and Fundación Biofísica Bizkaia. CIBER-BBN is an iniciative funded by the VI National R&D&I Plan 2008-2011, Iniciativa Ingenio 2010, Consolider Program, CIBER Actions and financed by the Instituto de Salud Carlos III with assistance from the European Regional Development. B.U-U. was supported by Universidad de País Vasco-UPV/EHU pre-doctoral fellowship and Fundación Biofísica Bizkaia. J.V.B. was a postdoctoral scientist supported by Universidad de País Vasco-UPV/EHU postdoctoral fellowship. The authors acknowledge the Servicio General de Microscopía Analítica y de Alta Resolución en Biomedicina at the University of Basque Country for assistance with confocal microscopy, Prof. A. Gómez-Muñoz for flow cytometry facilities and Eneritz Bilbao for excellent technical assistance.Peer reviewe

A numerical analysis of multiaxial fatigue in a butt weld specimen considering residual stresses

Residual Stress (RS) pattern changes considerably depending on the width of the plates and the welding parameters, having effect on the fatigue strength. Most of the standards do not consider them and in some works, yield stress is taken as residual stressvalue. It results in a very conservative estimation of fatigue life. Authors developed recently a numerical model to predict more properly the value of RS pattern depending on the plate thickness. In a welded joint, considering the RS and alternating axial loads, the evolution of the stresses is multiaxial, becoming necessary its study. Therefore, the aim of this work is to analyse different fatigue indicator parameters (Smith-Watson-Topper, Fatemi-Socie, and Critical Plane implementation of the Basquin equation) in order to predict the fatigue behaviour of butt-weld components. For that purpose, the numerical model to predict the RS pattern in welded joint developed by this research group is used

Histological Examination in Obtaining a Diagnosis in Patients with Lymphadenopathy in Lima, Peru.

The differential diagnosis for lymphadenopathy is wide and clinical presentations overlap, making obtaining an accurate diagnosis challenging. We sought to characterize the clinical and radiological characteristics, histological findings, and diagnoses for a cohort of patients with lymphadenopathy of unknown etiology. 121 Peruvian adults with lymphadenopathy underwent lymph node biopsy for microbiological and histopathological evaluation. Mean patient age was 41 years (Interquartile Range 26-52), 56% were males, and 39% were HIV positive. Patients reported fever (31%), weight loss (23%), and headache (22%); HIV infection was associated with fever (P < 0.05) and gastrointestinal symptoms (P < 0.05). Abnormalities were reported in 40% of chest X-rays (N = 101). Physicians suspected TB in 92 patients (76%), lymphoma in 19 patients (16%), and other malignancy in seven patients (5.8%). Histological diagnoses (N = 117) included tuberculosis (34%), hyperplasia (27%), lymphoma (13%), and nonlymphoma malignancy (14%). Hyperplasia was more common (P < 0.001) and lymphoma less common (P = 0.005) among HIV-positive than HIV-negative patients. There was a trend toward reduced frequency of caseous necrosis in samples from HIV-positive than HIV-negative TB patients (67 versus 93%, P = 0.055). The spectrum of diagnoses was broad, and clinical and radiological features correlated poorly with diagnosis. On the basis of clinical features, physicians over-diagnosed TB, and under-diagnosed malignancy. Although this may not be inappropriate in resource-limited settings where TB is the most frequent easily treatable cause of lymphadenopathy, diagnostic delays can be detrimental to patients with malignancy. It is important that patients with lymphadenopathy undergo a full diagnostic work-up including sampling for histological evaluation to obtain an accurate diagnosis

Distribution and demographic parameters of the Peregrine falcon Falco peregrinus L., 1756 in Gipuzkoa

Gathering information on the distribution and population size is crucial in order to develop precise conservation actions, especially in threatened species or those of special concern. The aim of the present article is to update the population status and the breeding parameters of the Peregrine falcon Falco peregrinus L., 1756 in Gipuzkoa. We also used data obtained from previous studies in order to estimate population trends in the region (2000-2017). In 2017, 35 territories were detected. During the period from 1990 to 2000, the mean breeding population size increased 79.4%, but from 2000 to 2017, the increase was just 3.2%. However, the latter increase was not statistically significant. Therefore, it can be concluded that the population has remained stable for the last two decades. The Peregrine falcon is well distributed in Gipuzkoa, except for the central-eastern part of the region. The nests were found on inland cliffs (48.6%), marine cliffs (25.7%), quarries (22.9%) and buildings (2.9%). The breeding parameters in 2017 (productivity: 1.72 ± 1.36 offspring/breeding pair, n = 35; flight rate: 2.50 ± 0.83 offspring/nest, n = 24; breeding success, 92%) did not differ significantly from previous years within the region. In conclusion, the peregrine falcon population in Gipuzkoa has remained constant during the last two decades (from 2000 to 2010, and up to 2017), with one of the highest breeding densities in Spain. Breeding parameters are also high and, overall, the conservation status of the population is apparently good in Gipuzkoa

Impact of Reversion of Mycobacterium tuberculosis Immunoreactivity Tests on the Estimated Annual Risk of Infection

A key metric in tuberculosis epidemiology is the annual risk of infection (ARI), which is usually derived from tuberculin skin test (TST) and interferon-gamma release assay (IGRA) prevalence surveys in children. Deriving the ARI assumes that immunoreactivity is persistent over time; however, reversion of immunoreactivity has long been documented. Here we use a deterministic, compartmental model of Mycobacterium tuberculosis (Mtb) infection to explore the impact of reversion on ARI estimation using age-specific reversion probabilities for TST and IGRA. Using empirical data of TST reversion (22.2%/year for 0-19yo), the true ARI is 2-5 times higher than estimated from immunoreactivity studies in 8-12 year-olds. Applying empirical reversion probabilities for IGRA (9.9%/year for 12-18yo) showed a 1.5-2-fold underestimation. ARIs are increasingly underestimated in older populations, due to the cumulative impact of reversion on population reactivity over time. Declines in annual risk did not largely affect the results. Ignoring reversion leads to a stark underestimation of the true ARI in populations and our interpretation of Mtb transmission intensity. Future surveys should adjust for reversion probabilities and its cumulative effect with increasing age to provide a more accurate reflection of the burden and dynamics of Mtb infection