Bond graph simulation of error propagation in position estimation of a hydraulic cylinder using low cost accelerometers

The indirect calculation from acceleration of transversal displacement of the piston inside the body of a double effect linear hydraulic cylinder during its operating cycle is assessed. Currently an extensive effort exists in the improvement of the mechanical and electronic design of the highly sophisticated MEMS accelerometers. Nevertheless, the predictable presence of measurement errors in the current commercial accelerometers is the main origin of velocity and displacement measurement deviations during integration of the acceleration. A bond graph numerical simulation model of the electromechanical system has been developed in order to forecast the effect of several measurement errors in the use of low cost two axes accelerometers. The level of influence is assessed using quality indicators and visual signal evaluation, for both simulations and experimental results. The obtained displacements results are highly influenced by the diverse dynamic characteristics of each measuring axis. The small measuring errors of a simulated extremely high performance sensor generate only moderate effects in longitudinal displacement but deep deviations in the reconstruction of piston transversal movements. The bias error has been identified as the source of the higher deviations of displacement results; although, its consequences can be easily corrected.Peer ReviewedPostprint (published version

Experimental study of 3D movement in cushioning of hydraulic cylinder

A double acting cylinder operation has been fully monitored in its key functional parameters, focused on characterization of end-of-stroke cushioning and starting phases. Being the cylinder performance reliant in the piston constructive geometry, the number and location of piston circumferential grooves is a significant parameter affecting the internal cushioning system performance. An eddy current displacement sensor assembled in the piston allows assessment of piston radial displacement inside the cylinder tube, which is directly related with the studied operating phases. Due to such 3D displacements, the piston becomes as an active and self-adjusting element along the functional cycle of the cylinder. Mechanical joints orientation and operating pressure are also relevant parameters affecting piston radial displacement and, thus, the cushioning and starting performance. Computational Fluid Dynamics (CFD) results confirm the observed functional role of the perimeter grooves; the flow and pressure distributions, where develops a significant radial force, are also in accordance with the registered radial displacement.Peer ReviewedPostprint (published version

Airway Complications after Lung Transplantation—A Contemporary Series of 400 Bronchial Anastomoses from a Single Center

(1) Objective: To determine whether recent advances in lung transplantation (LT) have reduced the incidence and changed the risk factors for airway complications (AC). (2) Methods: Retrospective analysis of patients receiving a lung transplant between January 2007 and January 2019. An AC was defined as a bronchoscopic abnormality in the airway, either requiring or not requiring an endoscopic or surgical intervention. Both univariable and multivariable analyses were performed to identify risk factors for AC. (3) Results: 285 lung transplants (170 single and 115 bilateral lung transplants) were analysed, comprising 400 anastomoses at risk. A total of 50 anastomoses resulted in AC (12%). There were 14 anastomotic and 11 non-anastomotic stenoses, 4 dehiscences, and 3 malacias. Independent predictors for AC were: gender male (OR: 4.18; p = 0.002), cardiac comorbidities (OR: 2.74; p = 0.009), prolonged postoperative mechanical ventilation (OR: 2.5; p = 0.02), PaO2/FiO2 < 300 mmHg at 24 h post-LT (OR: 2.48; p = 0.01), graft infection (OR: 2.16; p = 0.05), and post-LT isolation of Aspergillus spp. (OR: 2.63; p = 0.03). (4) Conclusions: In spite of advances in lung transplantation practice, the risk factors, incidence, and lethality of AC after LT remains unchanged. Graft dysfunction, an infected environment, and the need of prolonged mechanical ventilation remain an Achilles heel for AC

Experimental study of 3D movement in cushioning of hydraulic cylinder

A double acting cylinder operation has been fully monitored in its key functional parameters, focused on characterization of end-of-stroke cushioning and starting phases. Being the cylinder performance reliant in the piston constructive geometry, the number and location of piston circumferential grooves is a significant parameter affecting the internal cushioning system performance. An eddy current displacement sensor assembled in the piston allows assessment of piston radial displacement inside the cylinder tube, which is directly related with the studied operating phases. Due to such 3D displacements, the piston becomes as an active and self-adjusting element along the functional cycle of the cylinder. Mechanical joints orientation and operating pressure are also relevant parameters affecting piston radial displacement and, thus, the cushioning and starting performance. Computational Fluid Dynamics (CFD) results confirm the observed functional role of the perimeter grooves; the flow and pressure distributions, where develops a significant radial force, are also in accordance with the registered radial displacement.Peer Reviewe

Bond graph simulation of error propagation in position estimation of a hydraulic cylinder using low cost accelerometers

The indirect calculation from acceleration of transversal displacement of the piston inside the body of a double effect linear hydraulic cylinder during its operating cycle is assessed. Currently an extensive effort exists in the improvement of the mechanical and electronic design of the highly sophisticated MEMS accelerometers. Nevertheless, the predictable presence of measurement errors in the current commercial accelerometers is the main origin of velocity and displacement measurement deviations during integration of the acceleration. A bond graph numerical simulation model of the electromechanical system has been developed in order to forecast the effect of several measurement errors in the use of low cost two axes accelerometers. The level of influence is assessed using quality indicators and visual signal evaluation, for both simulations and experimental results. The obtained displacements results are highly influenced by the diverse dynamic characteristics of each measuring axis. The small measuring errors of a simulated extremely high performance sensor generate only moderate effects in longitudinal displacement but deep deviations in the reconstruction of piston transversal movements. The bias error has been identified as the source of the higher deviations of displacement results; although, its consequences can be easily corrected.Peer Reviewe

Simulation of hydraulic cylinder cushioning

The internal cushioning systems of hydraulic linear actuators avoid mechanical shocks at the end of their stroke. The design where the piston with perimeter grooves regulates the flow by standing in front of the outlet port has been investigated. First, a bond graph dynamic model has been developed, including the flow throughout the internal cushion design, characterized in detail by computational fluid-dynamic simulation. Following this, the radial movement of the piston and the fluid-dynamic coefficients, experimentally validated, are integrated into the dynamic model. The registered radial movement is in coherence with the significant drag force estimated in the CFD simulation, generated by the flow through the grooves, where the laminar flow regime predominates. Ultimately, the model aims to predict the behavior of the cushioning during the movement of the arm of an excavator. The analytical model developed predicts the performance of the cushioning system, in coherence with empirical results. There is an optimal behavior, highly influenced by the mechanical stress conditions of the system, subject to a compromise between an increasing section of the grooves and an optimization of the radial gap.Peer ReviewedPostprint (published version

Lung transplantation for cystic fibrosis: differential characteristics and outcomes between children and adults.

The survival benefit of lung transplantation (LTx) for cystic fibrosis (CF) patients is well demonstrated. We aim to compare children and adult CF recipients to assess whether there are differences in survival and clinical outcomes, and to identify risk factors for mortality. A retrospective analysis of 442 consecutive LTx performed at our institution in a 20-year period was conducted. CF patients were distributed into two groups: children (age The study group included 120 consecutive CF patients: 50 children (13 ± 3 years) and 70 adults (25 ± 6 years) undergoing 111 bilateral, 4 lobar, 4 combined and 1 unilateral LTx. Comparative analysis (children versus adults): survival (overall; 5, 10 and 15 years) 57, 45, 35% vs 67, 55, 43% (P = 0.32); survival (1-year survivors; 5, 10 and 15 years): 75, 64, 46% vs 90, 75, 59% (P = 0.09); 30-day mortality: 14 vs 16% (P = 0.27); urgent LTx: 32 vs 17% (P = 0.04); use of cardiopulmonary bypass (CPB): 56 vs 28% (P = 0.002); intensive care unit stay: 20 ± 19 vs 10 ± 9 days (P = 0.006); AR episodes (n): 1.4 ± 0.7 vs 1.2 ± 0.8 (P = 0.004). Incidence of PGD and freedom from CLAD did not differ between groups. Predictors of mortality were: use of CPB (HR 3.12; 95% CI 1.33-7.35; P Paediatric CF patients usually present with poorer pre-transplant status, require CPB more frequently and have a higher incidence of post-LTx diabetes and infections. This might explain the trend towards a better long-term survival observed in adult CF patients

Factors Influencing Duration of Breastfeeding: Insights from a Prospective Study of Maternal Health Literacy and Obstetric Practices

Numerous factors concerning early breastfeeding abandonment have been described, including health literacy (HL). This study’s objective was to analyze factors related to early breastfeeding abandonment (n = 224, 81.5%) to the sixth month postpartum (n = 117, 42.5%). A Cox regression analysis revealed that inadequate HL levels, lack of mobilization during labour, and induced labour were significantly associated with early breastfeeding cessation (p = 0.022, p = 0.019, and p = 0.010, respectively). The results highlight that women with adequate HL had a 32% lower risk of early breastfeeding abandonment. In comparison, mobilization during labour and induction of labour were linked to a 32.4% reduction and a 53.8% increase in this risk, respectively. These findings emphasize the importance of considering obstetric and HL factors when addressing the breastfeeding duration, indicating opportunities for educational and perinatal care interventions

Spanish Lung Cancer Group SCAT trial: surgical audit to lymph node assessment based on IASLC recommendations

Background: The Spanish Customized Adjuvant Therapy (SCAT) trial assessed the role of individualized adjuvant therapy in clinical N0 incidental pN1 and/or N2 non-small cell lung cancer (NSCLC) completely resected. We assessed surgical topics with an in-depth analysis of quality of lymphadenectomy based on International Association for the Study of Lung Cancer (IASLC) recommendations.Methods: Patients with information about lymphadenectomy available were included (N=451). Prospectively collected data about tumor, type of resection, and postoperative morbidity and quality of lymph node dissection (LND) were retrospectively evaluated. Role of lymph node assessment on survival was analyzed using Kaplan-Meier curves, using regression models to identify prognostic factors.Results: In 33.7%, 17.7% and 49.9% of cases, regions 7, 10 and 11 respectively were not assessed. In 21.1% of patients, less than three lymph node regions were biopsied, while in 19.6% of patients less than six lymph nodes were assessed. In 53,4% of patients only one N1 region was evaluated. From patients with positive N2, 8.9% had no N1 regions biopsied. Twenty-nine percent of patients with at least one N2 lymph node resected shown the highest region involved. Thirty-day postoperative mortality was unknown. Five-year overall survival (OS) was 61.7% (95% CI: 55.4-67.4%), 51.5% (95% CI: 39.2-62.4%) and 42.3% (95% CI: 32.1-52.2%) for patients with N1, N2 and N1+N2 disease, respectively (