Hybrid active force control for fixed based rotorcraft

Disturbances are considered major challenges faced in the deployment of rotorcraft unmanned aerial vehicle (UAV) systems. Among different types of rotorcraft systems, the twin-rotor helicopter and quadrotor models are considered the most versatile flying machines nowadays due to their range of applications in the civilian and military sectors. However, these systems are multivariate and highly non-linear, making them difficult to be accurately controlled. Their performance could be further compromised when they are operated in the presence of disturbances or uncertainties. This dissertation presents an innovative hybrid control scheme for rotorcraft systems to improve disturbance rejection capability while maintaining system stability, based on a technique called active force control (AFC) via simulation and experimental works. A detailed dynamic model of each aerial system was derived based on the Euler–Lagrange and Newton-Euler methods, taking into account various assumptions and conditions. As a result of the derived models, a proportional-integral-derivative (PID) controller was designed to achieve the required altitude and attitude motions. Due to the PID's inability to reject applied disturbances, the AFC strategy was incorporated with the designed PID controller, to be known as the PID-AFC scheme. To estimate control parameters automatically, a number of artificial intelligence algorithms were employed in this study, namely the iterative learning algorithm and fuzzy logic. Intelligent rules of these AI algorithms were designed and embedded into the AFC loop, identified as intelligent active force control (IAFC)-based methods. This involved, PID-iterative learning active force control (PID-ILAFC) and PID-fuzzy logic active force control (PID-FLAFC) schemes. To test the performance and robustness of these proposed hybrid control systems, several disturbance models were introduced, namely the sinusoidal wave, pulsating, and Dryden wind gust model disturbances. Integral square error was selected as the index performance to compare between the proposed control schemes. In this study, the effectiveness of the PID-ILAFC strategy in connection with the body jerk performance was investigated in the presence of applied disturbance. In terms of experimental work, hardware-in-the-loop (HIL) experimental tests were conducted for a fixed-base rotorcraft UAV system to investigate how effective are the proposed hybrid PID-ILAFC schemes in disturbance rejection. Simulated results, in time domains, reveal the efficacy of the proposed hybrid IAFC-based control methods in the cancellation of different applied disturbances, while preserving the stability of the rotorcraft system, as compared to the conventional PID controller. In most of the cases, the simulated results show a reduction of more than 55% in settling time. In terms of body jerk performance, it was improved by around 65%, for twin-rotor helicopter system, and by a 45%, for quadrotor system. To achieve the best possible performance, results recommend using the full output signal produced by the AFC strategy according to the sensitivity analysis. The HIL experimental tests results demonstrate that the PID-ILAFC method can improve the disturbance rejection capability when compared to other control systems and show good agreement with the simulated counterpart. However, the selection of the appropriate learning parameters and initial conditions is viewed as a crucial step toward this improved performance

Enhancing disturbance rejection capability and body jerk performance of a twin-rotor helicopter model using intelligent active force control

This paper presents a study on the effectiveness of utilizing an innovative control approach based on an intelligent active force control (IAFC) strategy to stabilize a twin-rotor helicopter model and improve its ability to effectively reject external disturbances via a simulation work. A detailed mathematical model of a two-degree-of-freedom (DOF) helicopter was derived using the Euler-Lagrange method taking into account the effects of coupling and disturbances. In this developed model, a Proportional–Integral–Derivative (PID) controller was designed and combined with the proposed IAFC strategy to yield an intelligent hybrid control architecture known as a PID-IAFC scheme that can improve system performance and reject various types of applied disturbances. The intelligent algorithms used in the schemes are based on iterative learning (IL) and fuzzy logic (FL). In this work, different types of external disturbances in the form of sinusoidal waves, pulsating, and random noise disturbances were applied to the helicopter system to verify the sensitivity and durability of the proposed control schemes and consequently, a comparative study was performed to analyze the system characteristics. Notably, the efficacy of the IAFC based control unit was investigated to improve the body jerk performance in the presence of external disturbances. The acquired results reveal the effectiveness and robustness of the IAFC based controller in stabilizing the dual-rotor helicopter, rejecting the applied disturbances, and improving the body jerk performance by at least 54% for pitching and 19% for yawing motions in the presence of the pulsating disturbance, and 60% and 54%, respectively, for the random noise disturbance

Evaluation of laparoscopic-assisted anorectoplasty for the management of intermediate and high anorectal malformations in boys: Mansoura experience

Introduction: Laparoscopic-assisted anorectoplasty (LAARP) has been gaining great popularity for management of imperforate anus. This study aims to evaluate the use of this technique for high and intermediate anorectal malformations in boys.Patients and methods: From December 2012 to December 2016, we performed LAARP on 20 boys, all of which were colostomized at birth. Findings regarding the patients’ age at operation, type of anomaly, associated morbidities, sacral ratios, operative time, intraoperative complications, hospital stay, immediate/long-term postoperative complications, and reoperations were noted. Postoperatively, we evaluated the patients using barium enema, an ascending and voiding cystourethrogram, pelvic MRI, and a functional continence evaluation questionnaire.Results: A total of 11 patients presented with rectourethral bulbar fistula (RBF), seven with rectourethral prostatic fistula (RPF), one with rectovesical fistula, and one with no fistula. Mean sacral ratio was 0.82 ± 0.19. Mean age at time of LAARP was 236 ± 77 days. Mean operative time was 152 ± 32 min. Our most common intraoperative complication was peritoneal contamination (20%). Incidence of rectal mucosal prolapse was 40%. Barium enema revealed a mean rectoanal angle of 107 ± 13°. Ascending and voiding cystourethrogram revealed a residual urethral diverticulum in seven cases, six of which had RBFs. Mean MRI placement score obtained was 0.76± 0.51 denoting excellent rectal position.Conclusion: Usage of LAARP to manage high and intermediate anorectal malformations in boys is feasible, allowing accurate rectal placement within the muscle complex and with good postoperative functional results. Residual urethral diverticulum occurred more frequently in patients with RBF. Incidence of mucosal prolapse is high after LAARP and should be avoided.Keywords: laparoscopic-assisted anorectoplasty, anorectal malformations, residual urethral diverticulum post LAAR

Practical real-time implementation of a disturbance rejection control scheme for a twin-rotor helicopter system using intelligent active force control

This paper centers around an experimental investigation into the effectiveness of an innovative hybrid control approach based on an intelligent active force control (IAFC) strategy to stabilize a twin-rotor helicopter model and improve its ability to reject external disturbances efficiently. The intelligent algorithm was based on an iterative learning (IL) method integrated into the main control loop to estimate control parameters automatically while on-line. A mechatronic test rig with the IAFC-based control algorithm was incorporated into a Quanser Aero twin-rotor model in a laboratory setting as a verification platform to evaluate the applicability and efficacy of the proposed control algorithm via a practical real-time implementation. The hybrid IAFC-based control design was rigorously examined to test its feasibility and durability in countering various forms of external disturbances while executing the trajectory tracking tasks. Notably, the efficiency of the IAFC-based control unit was mainly studied and compared with other control plans under different operating conditions for benchmarking. The experimental results show the ability of the controller based on the IAFC strategy to effectively improve the disturbance rejection capability compared to the other control schemes considered in the study. About 27% improvement of the system performance in terms of lowering the root mean square error (RMSE) was observed compared to the other control systems counterparts

A novel voice-coil actuated mini crawler for in-pipe application employing active force control with iterative learning algorithm

This study proposes the design and development of an in-pipe mini crawler (or robot) capable of performing its various tasks with the ability to reject undesired disturbances resulting from friction and viscosity, as it was modeled, simulated, and experimented using an iterative learning algorithm (ILA)-based active force control (AFC) strategy. The crawler motion was executed based on a rapid and successive push-pull action plus friction that causes the crawler to move in an earthworm-like manner using a linear voice-coil actuator (VCA). A novel self-adjusted mechanism was designed to ensure that the crawler remained concentric in the pipe as it slides along the inner surface of the pipe. A novel control strategy was also proposed consisting of the AFC-based controller cascaded with a proportional-integral-derivative (PID) controller to control the crawler movement and expel off the applied perturbations. An intelligent PD-type ILA was employed to automatically tune the AFC while online. For the validation part, a prototype was designed, developed, and later experimented with using the proposed technique for a given set of conditions. The system integration employed a hardware-in-the-loop (HIL) test configuration utilizing LabVIEW. Experimental results are in good agreement with the simulation counterpart, thereby indicating the practicality and feasibility of the control system in performing accurate and robust trajectory tracking. This shall serve as a good basis for designing more challenging tasks related to miniature crawling mechanism in-pipe applications

Burnout among surgeons before and during the SARS-CoV-2 pandemic: an international survey

Background: SARS-CoV-2 pandemic has had many significant impacts within the surgical realm, and surgeons have been obligated to reconsider almost every aspect of daily clinical practice. Methods: This is a cross-sectional study reported in compliance with the CHERRIES guidelines and conducted through an online platform from June 14th to July 15th, 2020. The primary outcome was the burden of burnout during the pandemic indicated by the validated Shirom-Melamed Burnout Measure. Results: Nine hundred fifty-four surgeons completed the survey. The median length of practice was 10 years; 78.2% included were male with a median age of 37 years old, 39.5% were consultants, 68.9% were general surgeons, and 55.7% were affiliated with an academic institution. Overall, there was a significant increase in the mean burnout score during the pandemic; longer years of practice and older age were significantly associated with less burnout. There were significant reductions in the median number of outpatient visits, operated cases, on-call hours, emergency visits, and research work, so, 48.2% of respondents felt that the training resources were insufficient. The majority (81.3%) of respondents reported that their hospitals were included in the management of COVID-19, 66.5% felt their roles had been minimized; 41% were asked to assist in non-surgical medical practices, and 37.6% of respondents were included in COVID-19 management. Conclusions: There was a significant burnout among trainees. Almost all aspects of clinical and research activities were affected with a significant reduction in the volume of research, outpatient clinic visits, surgical procedures, on-call hours, and emergency cases hindering the training. Trial registration: The study was registered on clicaltrials.gov "NCT04433286" on 16/06/2020

Impact of opioid-free analgesia on pain severity and patient satisfaction after discharge from surgery: multispecialty, prospective cohort study in 25 countries

Background: Balancing opioid stewardship and the need for adequate analgesia following discharge after surgery is challenging. This study aimed to compare the outcomes for patients discharged with opioid versus opioid-free analgesia after common surgical procedures.Methods: This international, multicentre, prospective cohort study collected data from patients undergoing common acute and elective general surgical, urological, gynaecological, and orthopaedic procedures. The primary outcomes were patient-reported time in severe pain measured on a numerical analogue scale from 0 to 100% and patient-reported satisfaction with pain relief during the first week following discharge. Data were collected by in-hospital chart review and patient telephone interview 1 week after discharge.Results: The study recruited 4273 patients from 144 centres in 25 countries; 1311 patients (30.7%) were prescribed opioid analgesia at discharge. Patients reported being in severe pain for 10 (i.q.r. 1-30)% of the first week after discharge and rated satisfaction with analgesia as 90 (i.q.r. 80-100) of 100. After adjustment for confounders, opioid analgesia on discharge was independently associated with increased pain severity (risk ratio 1.52, 95% c.i. 1.31 to 1.76; P < 0.001) and re-presentation to healthcare providers owing to side-effects of medication (OR 2.38, 95% c.i. 1.36 to 4.17; P = 0.004), but not with satisfaction with analgesia (beta coefficient 0.92, 95% c.i. -1.52 to 3.36; P = 0.468) compared with opioid-free analgesia. Although opioid prescribing varied greatly between high-income and low- and middle-income countries, patient-reported outcomes did not.Conclusion: Opioid analgesia prescription on surgical discharge is associated with a higher risk of re-presentation owing to side-effects of medication and increased patient-reported pain, but not with changes in patient-reported satisfaction. Opioid-free discharge analgesia should be adopted routinely

Mortality from gastrointestinal congenital anomalies at 264 hospitals in 74 low-income, middle-income, and high-income countries: a multicentre, international, prospective cohort study

Summary Background Congenital anomalies are the fifth leading cause of mortality in children younger than 5 years globally. Many gastrointestinal congenital anomalies are fatal without timely access to neonatal surgical care, but few studies have been done on these conditions in low-income and middle-income countries (LMICs). We compared outcomes of the seven most common gastrointestinal congenital anomalies in low-income, middle-income, and high-income countries globally, and identified factors associated with mortality. Methods We did a multicentre, international prospective cohort study of patients younger than 16 years, presenting to hospital for the first time with oesophageal atresia, congenital diaphragmatic hernia, intestinal atresia, gastroschisis, exomphalos, anorectal malformation, and Hirschsprung’s disease. Recruitment was of consecutive patients for a minimum of 1 month between October, 2018, and April, 2019. We collected data on patient demographics, clinical status, interventions, and outcomes using the REDCap platform. Patients were followed up for 30 days after primary intervention, or 30 days after admission if they did not receive an intervention. The primary outcome was all-cause, in-hospital mortality for all conditions combined and each condition individually, stratified by country income status. We did a complete case analysis. Findings We included 3849 patients with 3975 study conditions (560 with oesophageal atresia, 448 with congenital diaphragmatic hernia, 681 with intestinal atresia, 453 with gastroschisis, 325 with exomphalos, 991 with anorectal malformation, and 517 with Hirschsprung’s disease) from 264 hospitals (89 in high-income countries, 166 in middleincome countries, and nine in low-income countries) in 74 countries. Of the 3849 patients, 2231 (58·0%) were male. Median gestational age at birth was 38 weeks (IQR 36–39) and median bodyweight at presentation was 2·8 kg (2·3–3·3). Mortality among all patients was 37 (39·8%) of 93 in low-income countries, 583 (20·4%) of 2860 in middle-income countries, and 50 (5·6%) of 896 in high-income countries (p<0·0001 between all country income groups). Gastroschisis had the greatest difference in mortality between country income strata (nine [90·0%] of ten in lowincome countries, 97 [31·9%] of 304 in middle-income countries, and two [1·4%] of 139 in high-income countries; p≤0·0001 between all country income groups). Factors significantly associated with higher mortality for all patients combined included country income status (low-income vs high-income countries, risk ratio 2·78 [95% CI 1·88–4·11], p<0·0001; middle-income vs high-income countries, 2·11 [1·59–2·79], p<0·0001), sepsis at presentation (1·20 [1·04–1·40], p=0·016), higher American Society of Anesthesiologists (ASA) score at primary intervention (ASA 4–5 vs ASA 1–2, 1·82 [1·40–2·35], p<0·0001; ASA 3 vs ASA 1–2, 1·58, [1·30–1·92], p<0·0001]), surgical safety checklist not used (1·39 [1·02–1·90], p=0·035), and ventilation or parenteral nutrition unavailable when needed (ventilation 1·96, [1·41–2·71], p=0·0001; parenteral nutrition 1·35, [1·05–1·74], p=0·018). Administration of parenteral nutrition (0·61, [0·47–0·79], p=0·0002) and use of a peripherally inserted central catheter (0·65 [0·50–0·86], p=0·0024) or percutaneous central line (0·69 [0·48–1·00], p=0·049) were associated with lower mortality. Interpretation Unacceptable differences in mortality exist for gastrointestinal congenital anomalies between lowincome, middle-income, and high-income countries. Improving access to quality neonatal surgical care in LMICs will be vital to achieve Sustainable Development Goal 3.2 of ending preventable deaths in neonates and children younger than 5 years by 2030

نوبات غضب جوليانو

Traduzione dell'opera teatrale di Italo Svevo intitolata Le ire di Giuliano dall'italiano all'arab