Achieving aerospace standard porosity levels when welding thin and thick-section aluminium using fibre-delivered lasers : executive summary

Environmental and commercial pressures have forced the aerospace industry to look at alternatives to riveting for the manufacture of aluminium aircraft structures. This resulted, at the end of last century, in an extensive study by Airbus into the possiblities of using CO2 lasers, which led to the process being implemented for a (small) number of stringer-to-skin fuselage panels in the newer Airbus models. Since this initial commercial success, new laser sources have become available that are more suitable for the welding of aluminium than CO2 lasers, in the form of Nd: YAG and Yb-fibre lasers. Both produce a wavelength that is absorbed more efficiently by aluminium alloys than the CO2 laser wavelength, resulting in an improved keyhole stability, as demonstrated in the late nineties for Nd: YAG lasers. In addition, Yb-fibre lasers have become available at output powers higher than available for Nd: YAG lasers, allowing thicker sections of aluminium to be welded in a single pass. However, despite their claimed advantages, no efforts were made to demonstrate the potential of these lasers for (aluminium) aircraft manufacture. For this reason, the author initiated a series of studies in 2001, with the overall aim to develop procedures to laser weld both thin (3.2mm) and thicksection (12.7mm) aerospace aluminium alloys using these fibre-delivered lasers to a weld quality, in particular related to weld metal porosity, suitable for aerospace service. The focus in this research was on weld metal porosity, because this is a particular problem when laser welding aluminium, either in the form of fine (hydrogen) porosity or larger porosity associated with an unstable keyhole behaviour. The benchmark weld metal porosity for this study was obtained from the stringent weld quality classes defined in BS EN 13919-2 and AWS D17.1. The approach to this research was in three parts, with work in the first aimed at demonstrating that a 3kW Nd: YAG laser was capable of producing low-porosity welds in 3.2mm thickness 2024 aluminium alloy, and thus can be considered for replacing the CO2 laser currently used for the stringer-to-skin fuselage application. Prior to the final part of the research, in which a 7kW Yb-fibre laser was used to demonstrate that these benchmark porosity levels could also be achieved in thicker section (aerospace-grade) aluminium, a comparison study was carried out to quantify the difference in welding performance between the Nd: YAG and the Yb-fibre laser. At an output power of 4kW focused in a 0.4mm diameter spot, the Yb-fibre laser was capable of a 30% higher welding speeds in 4mm (5083) aluminium alloy, or a 20% increase in depth of penetration for welding speeds between 1 and 15m/min, compared with the Nd: YAG laser. This improvement in welding performance, together with an output power of 7W, produced full penetration in 12.7mm thickness (aerospace-grade) AI-Zn-Mg-Cu aluminium alloy using the Yb-fibre laser autogenously, or in a hybrid configuration with a MIG arc. Both the autogenous laser and hybrid laser-MIG process were capable of producing welds with a weld metal porosity in line with the BS EN 13919-2 and AWS D17.1 benchmark conditions, at welding speeds of 0.55 and 0.75m/min, respectively. At these production rates, the 248 metres of stringer incorporated in a typical aluminium wing structure can be welded in 7.5 and 5.5 hours, in case of autogenous laser and hybrid laser-MIG, respectively, compared with 37.6 hours currently needed for the riveting process

First case of spontaneous rupture of the left ureter in immediate post-partum

The rupture of the ureter during pregnancy is a rare complication and is most frequently observed in the right ureter. We report below the case of a rupture in the left ureter. A 36-year old woman gave birth vaginally to a 3010-g girl without operative vaginal delivery or episiotomy. The following day, the patient exhibited a sudden pain in the left side spreading to the left iliac fossa. An abdominopelvic CT scan was carried out and revealed a flow of contrast agent at the left ureteral lumbar level and a left urinoma. A ureteral stent was inserted on the left side under X-ray control. Six weeks after delivery the ureteral stent was removed. The Uro CT scan allowed us to confirm the total recovery of the left ureter. We have reported below the first case of left rupture treated in a conservative manner with positive and functional clinical progress

Patients' experiences of transitioning between different renal replacement therapy modalities : a qualitative study

BACKGROUND: Different kidney replacement therapy modalities are available to manage end-stage kidney disease, such as home-based dialysis, in-center hemodialysis, and kidney transplantation. Although transitioning between modalities is common, data on how patients experience these transitions are scarce. This study explores patients' perspectives of transitioning from a home-based to an in-center modality. METHODS: Patients transitioning from peritoneal dialysis to in-center hemodialysis were purposively selected. Semi-structured interviews were performed, digitally recorded, and transcribed verbatim. Data analysis, consistent with Charmaz' constructivist approach of grounded theory was performed. RESULTS: Fifteen patients (10 males; mean age 62 years) participated. The conditions of the transitioning process impacted the participants' experiences, resulting in divergent experiences and associated emotions. Some participants experienced a loss of control due to the therapy-related changes. Some felt tied down and having lost independence, whereas others stated they regained control as they felt relieved from responsibility. This paradox of control was related to the patient having or not having (1) experienced a fit of hemodialysis with their personal lifestyle, (2) a frame of reference, (3) higher care requirements, (4) insight into the underlying reasons for transitioning, and (5) trust in the healthcare providers. CONCLUSIONS: Care teams need to offer opportunities to elicit patients' knowledge and fears, dispel myths, forge connections with other patients, and visit the dialysis unit before transition to alleviate anxiety. Interventions that facilitate a sense of control should be grounded in the meaning that the disorder has for the person and how it impacts their sense of self

The Geoff Egan Memorial Lecture 2011. Artefacts, art and artifice: reconsidering iconographic sources for archaeological objects in early modern Europe

A first systematic analysis of historic domestic material culture depicted in contemporaneous Western painting and prints, c.1400-1800. Drawing on an extensive data set, the paper proposes to methodologies and hermeneutics for historical analysis and archaeological correspondence

Effect of metal micro-structuring on the mechanical behavior of polymer–metal laser T-joints

AbstractThe metal was locally structured by pulsed laser radiation producing microscopic patterns on its surface. In a second step the opposite side of the micro-structured metal was irradiated by a continuous wave (CW) fiber laser to achieve the mechanical interlock between the two materials. A tight relationship between the microstructure parameters and pull-out test performance was observed. The greatest strength was achieved when the distance between subsequent grooves was minimized. The T-joint mechanical performance did not reveal any significant dependence on the considered range of joining areas. The morphological and topographical features of the detached surfaces showed that the micro-structured grooves were completely filled during the laser conductive joining process. Different alignment angles of patterns produced different failure modes although there was no evidence of an additional mechanical interlock

Effect of the use of a video tutorial in addition to simulation in learning the maneuvers for shoulder dystocia

The development of video tutorials is flourishing and may make it possible to maintain knowledge learned during instruction with simulation. The aim of this study was to assess the effect of adding a video tutorial to a lecture and simulation for learning the maneuvers and protocol for the management of shoulder dystocia. Student midwives and medical students attended a lecture class including instruction about maneuvers and a presentation of an algorithm for the management of shoulder dystocia. They were randomized into two groups. The video group was reminded every two weeks to watch a short tutorial. The control group was reminded to consult the slide show. At the end of two months, they were evaluated by graders. The practice, theory, and global scores of the students in the video group were significantly higher than those of the students in the control group (14.8 vs. 10.4; 5.6 vs. 3.4; and 9.3 vs. 7.0, P<0.001). The scores for the video group improved at the second simulation session, compared with the first (14.8 vs. 9.9; 5.6 vs. 2.9; and 9.3 vs. 7, P<0.001). The addition of a video tutorial improved learning compared to a standard lecture and simulation session alone

Psychometric properties of the Dutch version of the London Measure of Unplanned Pregnancy in women with pregnancies ending in birth

OBJECTIVE: To evaluate the psychometric properties of the Dutch version of the London Measure of Unplanned Pregnancy in women with pregnancies ending in birth. METHODS: A two-phase psychometric evaluation design was set-up. Phase I comprised the translation from English into Dutch and pretesting with 6 women using cognitive interviews. In phase II, the reliability and validity of the Dutch version of the LMUP was assessed in 517 women giving birth recently. Reliability (internal consistency) was assessed using Cronbach's alpha, inter-item correlations, and corrected item-total correlations. Construct validity was assessed using principal components analysis and hypothesis testing. Exploratory Mokken scale analysis was carried out. RESULTS: 517 women aged 15-45 completed the Dutch version of the LMUP. Reliability testing showed acceptable internal consistency (alpha = 0.74, positive inter-item correlations between all items, all corrected item-total correlations >0.20). Validity testing confirmed the unidimensional structure of the scale and all hypotheses were confirmed. The overall Loevinger's H coefficient was 0.57, representing a 'strong' scale. CONCLUSION: The Dutch version of the LMUP is a reliable and valid measure that can be used in the Dutch-speaking population in Belgium to assess pregnancy planning. Future research is necessary to assess the stability of the Dutch version of the LMUP, and to evaluate its psychometric properties in women with abortions

Reconstruction microchirurgicale et prise en charge globale des patients porteurs de cancer ORL : l’importance d’une approche qualité et d’un circuit protocolisé [Microsurgical reconstruction and full management of patients with head and neck cancer: Importance of a quality approach and a circuit protocolisation]

Main of study: Management and surgical reconstruction of head and neck cancers remain a challenge. From the first consultation to surgery and radiotherapy, it is necessary to save time to ensure optimum treatment and better survival rates. Objectif: To establish a kind of quality approach to the management of patients with head and neck cancers. 54 patients who had microsurgical reconstruction after head and neck cancer were included in this study between 1997 and 2006. Results : Multiple data were considered: body mass index (BMI), ASA stage, age, existence of a pre-or postoperative radiotherapy, the surgeon's experience and the number of veins drainage. The success rate is superior when more than one draining vein is sutured to the flap for patients with a BMI > 20. Radiotherapy does not seem to affect the survival of the flap. Conclusion: According to current literature, the survival rate of these patients is better when the overall time care is less than 100 days. That period is possible with a perfect organization of the medical and paramedical team. Therefore, we propose to include these patients in a circuit protocolisation care, which saves time, to better inform patients and improve survival rates. Buts: la prise en charge et la reconstruction chirurgicale des cancers ORL restent un challenge. De la première consultation à la chirurgie et la radiothérapie, il est nécessaire de gagner du temps afin d’assurer une traitement optimum et un meilleur taux de survie. Objectif : établir une sorte d’approche qualité de la prise en charge des patients porteurs de cancers ORL. 54 patients qui ont bénéficié d’une reconstruction microchirurgicale suite à un cancer ORL ont été inclus dans cette étude entre 1997 et 2006. Résultats : plusieurs données ont été étudiées : l’index de masse corporelle (IMC), le stade ASA, l’âge, l’existence d’une radiothérapie pré ou post opératoire, l’expérience du chirurgien ainsi que le nombre de veines de drainage. Le taux de succès se révèle supérieur lorsque plus d’une veine de drainage est suturée au lambeau, pour des patients ayant un IMC > 20. La radiothérapie ne semble pas avoir de répercussion sur la survie du lambeau. Conclusion : conformément à la littérature actuelle, le taux de survie de ces patients est meilleur lorsque le temps global de prise en charge est inférieur à 100 jours. Ce délai court n’est possible qu’avec une parfaite organisation de l’équipe médicale et paramédicale. De ce fait, nous proposons d’inclure ces patients dans un circuit de prise en charge protocolisé, ce qui permet de gagner du temps, de mieux informer le patient et d’améliorer le taux de survie