Pressure investigation of NASA leading edge vortex flaps on a 60 deg Delta wing

Pressure distributions on a 60 deg Delta Wing with NASA designed leading edge vortex flaps (LEVF) were found in order to provide more pressure data for LEVF and to help verify NASA computer codes used in designing these flaps. These flaps were intended to be optimized designs based on these computer codes. However, the pressure distributions show that the flaps wre not optimum for the size and deflection specified. A second drag-producing vortex forming over the wing indicated that the flap was too large for the specified deflection. Also, it became apparent that flap thickness has a possible effect on the reattachment location of the vortex. Research is continuing to determine proper flap size and deflection relationships that provide well-behaved flowfields and acceptable hinge-moment characteristics

An experimental study of pressures on 60 deg Delta wings with leading edge vortex flaps

An experimental study was conducted in the Virginia Tech Stability Wind Tunnel to determine surface pressures over a 60 deg sweep delta wing with three vortex flap designs. Extensive pressure data was collected to provide a base data set for comparison with computational design codes and to allow a better understanding of the flow over vortex flaps. The results indicated that vortex flaps can be designed which will contain the leading edge vortex with no spillage onto the wing upper surface. However, the tests also showed that flaps designed without accounting for flap thickness will not be optimum and the result can be oversized flaps, early flap vortex reattachment and a second separation and vortex at the wing/flap hinge line

AMR Parsing is Far from Solved:GrAPES, the Granular AMR Parsing Evaluation Suite

We present the Granular AMR Parsing Evaluation Suite (GrAPES), a challenge set for Abstract Meaning Representation (AMR) parsing with accompanying evaluation metrics. AMR parsers now obtain high scores on the standard AMR evaluation metric Smatch, close to or even above reported inter-annotator agreement. But that does not mean that AMR parsing is solved; in fact, human evaluation in previous work indicates that current parsers still quite frequently make errors on node labels or graph structure that substantially distort sentence meaning. Here, we provide an evaluation suite that tests AMR parsers on a range of phenomena of practical, technical, and linguistic interest. Our 36 categories range from seen and unseen labels, to structural generalization, to coreference. GrAPES reveals in depth the abilities and shortcomings of current AMR parsers.</p

Recent advances in petri nets and concurrency

CEUR Workshop Proceeding

Temporary Trans-gastric Stent Deployment Over a 20 French Gastrostomy for Single-Stage Endoscopic Retrograde Cholangiopancreatography After Gastric Bypass

Introduction: Treatment of pancreato-biliary disorders after gastric bypass is challenging due to altered anatomy. Several techniques have been proposed to overcome this condition; however, none has emerged as the gold standard treatment. Furthermore, a decision-making algorithm evaluating when and why apply one technique over another is still lacking. Objectives: To describe a novel trans-gastric approach to allow endoscopic retrograde cholangiopancreatography (ERCP) in Roux-en-Y gastric bypass (RYGB) anatomy soon after prior laparoscopic cholecystectomy (LC) and to propose a decision-making algorithm for selection of the most suitable technique according a tailored approach. Setting: Private hospital. Methods: Between January and March 2020, patients with Roux-en-Y gastric bypass anatomy referred to our tertiary center to undergo ERCP after recent laparoscopic cholecystectomy were retrospectively evaluated. A 20 french (Fr) gastrostomy was performed during cholecystectomy. A single-stage ERCP was carried out by means of temporary trans-gastric stent deployment over a 20 Fr gastrostomy. Results: A total of 5 patients (mean age 41; mean body mass index 48.3) were enrolled. ERCP was performed after an average of 2 days from surgery. Technical and clinical success was achieved in 100%. No adverse events occurred. Spontaneous closure of the gastrostomy after its bedside removal was observed in all cases. Conclusions: Our approach allows to perform a single-stage ERCP in RYGB patients, early after LC, with no need of any other re-interventions. Any surgeon facing unexpected biliary disorders, during LC, can easily perform a 20 Fr gastrostomy thus allowing the patient to undergo early ERCP without any delay

Aortic injuries following stents in bariatric surgery: our experience

Background: Due to the large number of laparoscopic sleeve gastrectomy (LSG) performed over the last decade, the management of the leak following LSG has been increasingly reported. The role of covered Self Expandable Metal Stents (cSEMS) for the treatment of the leak is still controversial because of the poor tolerance and high risk of complications. Objectives: The aim of the present study was to analyze the foregut wall perforation and aorta injuries, a very rare but potentially fatal complication, related to the treatment of the leak following LSG using cSEMS. Setting: Private hospital, France. Methods: An audit was conducted in 2 French tertiary bariatric endoscopic centers focusing on aortic injuries after cSEMS use for leak. We examined and classified the initial procedure, leak characteristics, primary endoscopic treatment, and outcome of endoscopic complication for each eligible case. Results: A total of 5 patients were identified with foregut wall perforation and aorta injuries. All stents were deployed for staple line leak following LSG. The recorded mortality in case of esophageal-aortic injuries related to cSEMS use was 80%. Conclusion: cSEMS are potentially effective tools for the management of foregut leaks in bariatric surgery. The biggest challenges with this approach are stent migration and poor quality of life. Caution is required due to the risk of fatal complications such as foregut wall perforation and aortic injury

DEVELOPMENT OF OFF-DESIGN TURBOCHARGER MODELLING COMBINED WITH 1-D ENGINE MODEL

The present work aims to carry out an off-design turbocharger modellingpowered by exhaust gases from a Wärtsilä 20V34SG engine. First of all, 1-D engine model was already developed in GT-Power software whileconsidering a thermodynamic turbocharger modelling with constantisentropic efficiencies. Secondly, by using the results from 1-D enginemodel, the off-design turbocharger modelling is calibrated separately inEES software, taking into account compressible assumption, trianglevelocities and geometric dimensions. The case study is derived from a R&Dproject (ANEEL PD-06483-0318/2018) that targets to cool and dehumidifythe intake air at compressor’s upstream through a cooling coil, therebyallowing engine’s operation at reduced knocking conditions. The brakemean effective pressure (BMEP) is varied in the range of 20 to 23.45 bar,corresponding to brake power from 8.7 to 10.2 MW, respectively. With theoff-design turbocharger modelling it is possible to analyze its operationalbehavior under higher BMEP, hence, allowing to predict some importantparameters. The results showed that the turbocharger is operating within themanufacturer’s limit for BMEP of 23.45 bar, presenting total-to-staticisentropic efficiencies of 0.81 and 0.784 for compressor and turbine,respectively, rotational speed around 28135 RPM, pressure ratio atcompressor of 4.567 and maintaining control on waste-gate valve

THE EFFECT OF THE THERMODYNAMIC MODELS ON THE THERMOECONOMIC RESULTS FOR COST ALLOCATION IN A GAS TURBINE COGENERATION SYSTEM

The thermoeconomics combines economics and thermodynamics to provide information not available from conventional energy and economic analysis. For thermoeconomics modeling one of the keys points is the thermodynamic model that should be adopted. Different thermodynamic models can be used in the modeling of a gas turbine system depending on the accuracy required. A detailed study of the performance of gas turbine would take into account many features. These would include the combustion process, the change of composition of working fluid during combustion, the effects of irreversibilities associated with friction and with pressure and temperature gradients and heat transfer between the gases and walls. Owing to these and others complexities, the accurate modeling of gas turbine normally involves computer simulation. To conduct elementary thermodynamic analyses, considerable simplifications are required. Thus, there are simplified models that lead to different results in thermoeconomics. At this point, three questions arise: How different can the results be? Are these simplifications reasonable? Is it worth using such a complex model? In order to answer these questions, this paper compares three thermodynamic models in a gas turbine cogeneration system from thermoeconomic point of view: cold air-standard model, CGAM model and complete combustion with excess air