390 research outputs found
Introducing a new method for efficient visualization of complex shape 3D ultrasonic phased-array C-scans
Automated robotic inspection systems allow the collection of large data volumes, compared to existing inspection systems. To maximize the throughput associated with the nondestructive evaluation phase, it is crucial that the reconstructed inspection data sets are generated and examined rapidly without a loss of detail. Data analysis often becomes the bottleneck of automated inspections. Therefore, new data visualization tools, suitable to screen the NDT information obtained through robotic systems, are urgently required. This paper presents a new approach, for the generation of three-dimensional ultrasonic C-scans of large and complex parts, suitable for application to high data throughput ultrasonic phased array inspection. This approach produces 3D C-scan presented as colored tessellated surfaces and the approach works efficiently on challenging geometry, with concave and convex regions. Qualitative and quantitative results show that the approach runs up to 500 times faster than other C-scan visualization techniques
Adapting robot paths for automated NDT of complex structures using ultrasonic alignment
Automated inspection systems using industrial robots have been available for several years. The IntACom robot inspection system was developed at TWI Wales and utilizes phased array ultrasonic probes to inspect complex geometries, in particular aerospace composite components. To increase inspection speed and accuracy, off-line path planning is employed to define a series of robotic movements following the surface of a component. To minimize influences of refraction at the component interface and effects of anisotropy, the ultrasonic probe must be kept perpendicular to the surface throughout the inspection. Deviations between the actual component and computer model used for path-planning result in suboptimal alignment and a subsequent reduction in the quality of the ultrasonic echo signal. In this work we demonstrate methods for using the ultrasonic echo signals to adapt a robotic path to achieve a minimal variation in the reflected surface echo. The component surface is imaged using phased array probes to calculate a sparse 3D point cloud with estimated normal directions. This is done through a preliminary alignment path covering approximately 25% of the total surface to minimize the impact on overall inspection time. The data is then compared to the expected geometry and deviations are minimized using least-squares optimization. Compared to manual alignment techniques, this method shows a reduction in surface amplitude variation of up to 32%, indicating that the robot is following the surface of the component more accurately
Assessing the accuracy of industrial robots through metrology for the enhancement of automated non-destructive testing
This work presents the study of the accuracy of an industrial robot KR5 arc HW, used to perform quality inspections of components with complex shapes. Metrology techniques such as laser tracking and large volume photogrammetry were deployed to quantify both pose and dynamic path accuracies of the robot in accordance with ISO 9283:1998. The overall positioning pose inaccuracy of the robot is found to be almost 1 mm and path inaccuracy at 100% of the robot rated velocity is 4.5 mm. The maximum pose orientation inaccuracy is found to be 14 degrees and the maximum path orientation inaccuracy is 5 degrees. Despite of the significant maximum inaccuracies, uncertainty of a robotic scanning application is estimated to be 0.5mm. Local positional errors manifest pronounced dependence on the position of the robot end effector in the working envelope. The uncertainties of the measurements are discussed and deemed to be caused by the tool center point calibration, the reference coordinate system transformation and the low accuracy of the photogrammetry system
Design and Rationale of a Scandinavian Multicenter Randomized Study Evaluating if Once-Daily Tacrolimus Versus Twice-Daily Cyclosporine Reduces the 3-year Incidence of Chronic Lung Allograft Dysfunction After Lung Transplantation (ScanCLAD Study)
Background A low level of evidence exists regarding the choice of calcineurin inhibitor (CNI) for immunosuppression after lung transplantation (LTx). Therefore, we designed a randomized clinical trial according to good clinical practice rules to compare tacrolimus with cyclosporine after LTx. Methods The ScanCLAD study is an investigator-initiated, pragmatic, controlled, randomized, open-label, multicenter study evaluating if an immunosuppressive protocol based on anti-thymocyte globulin (ATG) induction, once-daily tacrolimus dose, mycophenolate mofetil, and corticosteroid reduces the incidence of chronic lung allograft dysfunction (CLAD) after LTx, compared to a cyclosporine-based protocol with all other immunosuppressive and prophylactic drugs being identical between groups. All patients will be followed for 3 years to determine the main endpoint of CLAD. The study is designed for superiority, and power calculations show that 242 patients are needed. Also, the study is designed with more than 10 substudies addressing other important and unresolved issues in LTx. In addition, the ScanCLAD study enabled the synchronization of the treatment and follow-up protocols of the lung transplantation programs of all five Scandinavian lung transplantation centers. Planned Outcomes Recruitment started in 2016. At the end of April 2019, 227 patients were randomized. We anticipate the last patient to be randomized in autumn 2019, and thus the last patient visits will be in 2022. The ScanCLAD study is enrolling and investigates which CNI is to be preferred from a CLAD perspective after LTx. Trial Registry Number ScanCLAD trial registered at ClinicalTrials.gov before patient enrollment (NCT02936505). EUDRACT number 2015-004137-27.Peer reviewe
Urgent lung allocation system in the Scandiatransplant countries
BACKGROUND: Throughout the world, the scarcity of donor organs makes optimal allocation systems necessary. In the Scandiatransplant countries, organs for lung transplantation are allocated nationally. To ensure shorter wait time for critically ill patients, the Scandiatransplant urgent lung allocation system (ScULAS) was introduced in 2009, giving supranational priority to patients considered urgent. There were no pre-defined criteria for listing a patient as urgent, but each center was granted only 3 urgent calls per year. This study aims to explore the characteristics and outcome of patients listed as urgent, assess changes associated with the implementation of ScULAS, and describe how the system was utilized by the member centers. METHODS: All patients listed for lung transplantation at the 5 Scandiatransplant centers 5 years before and after implementation of ScULAS were included. RESULTS: After implementation, 8.3% of all listed patients received urgent status, of whom 81% were transplanted within 4 weeks. Patients listed as urgent were younger, more commonly had suppurative lung disease, and were more often on life support compared with patients without urgent status. For patients listed as urgent, post-transplant graft survival was inferior at 30 and 90 days. Although there were no pre-defined criteria for urgent listing, the system was not utilized at its maximum. CONCLUSIONS: ScULAS rapidly allocated organs to patients considered urgent. These patients were younger and more often had suppurative lung disease. Patients with urgent status had inferior short-term outcome, plausibly due to the higher proportion on life support before transplantation. (C) 2018 International Society for Heart and Lung Transplantation. All rights reserved.Peer reviewe
Heart failure in women with hypertensive disorders of pregnancy: Insights from the cardiovascular disease in Norway project
Hypertensive disorders of pregnancy (HDP) have been associated with heart failure (HF). It is unknown whether concurrent pregnancy complications (small-for-gestational-age or preterm delivery) or recurrent HDP modify HDP-associated HF risk. In this cohort study, we included Norwegian women with a first birth between 1980 and 2004. Follow-up occurred through 2009. Cox models examined gestational hypertension and preeclampsia in the first pregnancy as predictors of a composite of HF-related hospitalization or HF-related death, with assessment of effect modification by concurrent small-for-gestational-age or preterm delivery. Additional models were stratified by final parity (1 versus ≥2 births) and tested associations with recurrent HDP. Among 508 422 women, 565 experienced incident HF over a median 11.8 years of follow-up. After multivariable adjustment, gestational hypertension in the first birth was not significantly associated with HF (hazard ratio, 1.41 [95% CI, 0.84–2.35], P=0.19), whereas preeclampsia was associated with a hazard ratio of 2.00 (95% CI, 1.50–2.68, P<0.001). Among women with HDP, risks were not modified by concurrent small-for-gestational-age or preterm delivery (Pinteraction=0.42). Largest hazards of HF were observed in women whose only lifetime birth was complicated by preeclampsia and women with recurrent preeclampsia. HF risks were similar after excluding women with coronary artery disease. In summary, women with preeclampsia, especially those with one lifetime birth and those with recurrent preeclampsia, experienced increased HF risk compared to women without HDP. Further research is needed to clarify causal mechanisms.acceptedVersio
The challenges of transdisciplinary knowledge production: from unilocal to comparative research
This reflective paper surveys the lessons learnt and challenges faced by the Mistra Urban Futures (MUF) research centre and its research platforms in Sweden, the UK, South Africa and Kenya in developing and deploying different forms of transdisciplinary co-production of knowledge. Considerable experience with a distinctive portfolio of such methods has been gained and reflective evaluation is now under way. While it is important to understand the local context within which each method has evolved, we seek to explain the potential for adaptation in diverse contexts so that such knowledge co-production methods can be more widely utilized. Furthermore, the current phase of MUF’s work is undertaking innovative comparative transdisciplinary co-production research across its research platforms. Since the specific local projects differ, systematic thematic comparison requires great care and methodological rigour. Transdisciplinary co-production is inherently complex, time consuming and often unpredictable in terms of outcomes, and these challenges are intensified when it is undertaken comparatively
Early life exposures contributing to accelerated lung function decline in adulthood – a follow-up study of 11,000 adults from the general population
Background We aimed to assess whether exposure to risk factors in early life from conception to puberty continue to contribute to lung function decline later in life by using a pooled cohort comprising approx. 11,000 adults followed for more than 20 years and with up to three lung function measurements. Methods Participants (20–68 years) in the ECRHS and NFBC1966 cohort studies followed in the periods 1991–2013 and 1997–2013, respectively, were included. Mean annual decline in maximum forced expired volume in 1 s (FEV1) and forced vital capacity (FVC) were main outcomes. Associations between early life risk factors and change in lung function were estimated using mixed effects linear models adjusted for sex, age, FEV1, FVC and height at baseline, accounting for personal smoking. Findings Decline in lung function was accelerated in participants with mothers that smoked during pregnancy (FEV1 2.3 ml/year; 95% CI: 0.7, 3.8) (FVC 2.2 ml/year; 0.2, 4.2), with asthmatic mothers (FEV1 2.6 ml/year; 0.9, 4.4) (FEV1/FVC 0.04 per year; 0.04, 0.7) and asthmatic fathers (FVC 2.7 ml/year; 0.5, 5.0), and in women with early menarche (FVC 2.4 ml/year; 0.4, 4.4). Personal smoking of 10 pack-years contributed to a decline of 2.1 ml/year for FEV1 (1.8, 2.4) and 1.7 ml/year for FVC (1.3, 2.1). Severe respiratory infections in early childhood were associated with accelerated decline among ever-smokers. No effect-modification by personal smoking, asthma symptoms, sex or cohort was found. Interpretation Mothers’ smoking during pregnancy, parental asthma and early menarche may contribute to a decline of FEV1 and FVC later in life comparable to smoking 10 pack-years. Funding 10.13039/501100007601European Union's Horizon 2020; 10.13039/501100005416Research Council of Norway; 10.13039/501100002341Academy of Finland; University Hospital Oulu; 10.13039/501100008530European Regional Development Fund; 10.13039/501100004837Spanish Ministry of Science and Innovation; 10.13039/501100002809Generalitat de Catalunya
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