Modeling and managing separation for noise abatement arrival procedures

Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2007.Includes bibliographical references.Aircraft noise is a significant concern to communities near airports, and therefore a constraint to the growth of aviation. Advanced noise abatement approach and arrival procedures have been shown in previous studies and in limited implementation to be a cost effective means of achieving near- and medium-term noise reductions. Additionally, these procedures can be employed to reduce fuel bum, emissions, and flight time. However, because of aircraft trajectory variations due to operational uncertainties, it is difficult for air traffic controllers to predict and maintain separation between aircraft. Thus, without proper decision support tools, controllers need to add arbitrarily large buffers, thereby reducing airport throughput. A design and operational framework is proposed to advance the implementation of noise abatement arrival procedures. Under this framework, a target spacing is given at an intermediate metering point to ensure with a certain (limited) probability that the remainder of the noise abatement arrival procedure may be completed without further controller intervention. Small probability exceptions are handled by alternative plans.(cont.) A design methodology is presented, along with the details of a unique Monte Carlo simulation-based Tool for the Analysis of Separation And Throughput (TASAT) that is used to determine the minimum possible target spacing between aircraft at the metering point. Hence, a smaller separation buffer can be used and traffic throughput can be maintained at a relatively high level. The Monte Carlo simulation-based design tool accounts for operational uncertainties such as differences in aircraft performance, Flight Management System logic, aircraft weight, pilot response, and winds. A mode-decomposition and autoregressive approach was developed to model the stochastic wind variations between flights. Aircraft trajectories from the Monte Carlo simulations (or from radar tracks if they are available) are used within the context of the design methodology to determine target spacing for given desired probability. The utility of the design framework, methodology, and tools was illustrated through simulation analysis and an Area Navigation (RNAV) Continuous Descent Arrival (CDA) flight test at Louisville International Airport.(cont.) The flight test results were consistent with the model prediction. The research demonstrated that with the developed tools, noise abatement arrival procedures can be implemented to achieve noise reductions and other economic and environmental benefits while maintaining a relatively high level of traffic throughput. Suggestions for the selection of target spacing and the location of the intermediate metering point were provided based on the analysis.by Liling Ren.Sc.D

A study on the mechanisms of teachers’ academic emotions and motivational beliefs on learning engagement in the context of online training

IntroductionIn the context of digital transformation of education, online training is one of the important ways for teachers to improve their professionalism and promote the quality of education. However, studies have shown that teachers’ online training suffers from insufficient learning engagement and other problems, so it is crucial to explore the factors influencing teachers’ learning engagement and their mechanisms of action in the context of online training.MethodsTaking 589 teachers who participated in online training as the research subjects, the study used the methods of survey research and statistical analysis to explore the influence mechanism of teachers’ academic emotions and motivational beliefs on online learning engagement based on the dual perspectives of control value theory and expectancy-value theory.ResultsThe study found that: (1) positive-high arousal academic emotions, training self-efficacy, and training task value significantly and positively predicted online learning engagement, respectively; (2) negative-high arousal and negative-low arousal academic emotions significantly and negatively predicted online learning engagement; (3) training self-efficacy and training task value mediated the relationship between positive-high arousal academic emotions, negative-high arousal academic emotions, negative-low arousal academic emotions and online learning engagement, respectively.DiscussionThe study concluded that by creating an immersive learning environment based on the educational meta universe, personalized and precise training based on big data and adaptive technologies, and establishing a multi-dimensional and three-dimensional online learning support service system, which can effectively improve teachers’ online learning engagement and enhance their online training quality and effectiveness

High pressure study on LaFeAsO with different Tc

We report studies on pressure dependence of superconducting transition temperature (Tc) of LaFeAsO, LaFeAs(O0.5F0.5) and LaFeAs(O0.89F0.11) samples. In-situ resistance measurements under high pressure showed that the Tc of these three compounds increases with pressure initially, reaches a maximum value and then decreases with further increasing pressure, although the Tc at ambient pressure are different. The onset Tc of LaFeAsO is ~50 K at 1.5 GPa, which is the highest record in La-based oxypnicited system. The significant change in Tc induced by pressure is attributed to the orbital degeneracy and the electron density of state at the Fermi level.Comment: 13 pages, 4 figure

Sequential Quality-Control Checkpoints Triage Misfolded Cystic Fibrosis Transmembrane Conductance Regulator

Cystic fibrosis arises from the misfolding and premature degradation of CFTR Delta F508, a Cl- ion channel with a single amino acid deletion. Yet, the quality-control machinery that selects CFTR Delta F508 for degradation and the mechanism for its misfolding are not well defined. We identified an ER membrane-associated ubiquitin ligase complex containing the E3 RMA1, the E2 Ubc6e, and Derlin-1 that cooperates with the cytosolic Hsc70/CHIP E3 complex to triage CFTR and CFTR Delta F508. Derlin-1 serves to retain CFTR in the ER membrane and interacts with RMA1 and Ubc6e to promote CFTR's proteasomal degradation. RMA1 is capable of recognizing folding defects in CFTR Delta F508 coincident with translation, whereas the CHIP E3 appears to act posttranslationally. A folding defect in CFTR Delta F508 detected by RMA1 involves the inability of CFTR's second membrane-spanning domain to productively interact with amino-terminal domains. Thus, the RMA1 and CHIP E3 ubiquitin ligases act sequentially in ER membrane and cytosol to monitor the folding status of CFTR and CFTR Delta F508

Autologous cord blood mononuclear cell infusion for the prevention of bronchopulmonary dysplasia in very preterm monozygotic twins: A study protocol for a randomized, placebo-controlled, double-blinded multicenter trial

BackgroundPreterm-associated complications remain the main cause of neonatal death. Survivors face the challenges of short- and long-term complications. Among all complications, bronchopulmonary dysplasia (BPD) remains the first important cause of neonatal mortality and morbidity. Current treatment does not address this main preterm complication. Cord blood is regarded as a convenient source of stem cells. The paracrine bioactive factors of stem cells contribute to tissue repair and immune modulation. Our clinical studies and those of others have shown that cord blood cell infusion is both safe and possibly effective in the prevention and treatment of BPD. The therapeutic use of cord blood has emerged as a promising therapy. However, the genetic heterogeneity between control and intervention groups may reduce the comparability especially among small sample trials. The purpose of this study protocol is to investigate the effects of autologous cord blood mononuclear cell (ACBMNC) infusion on the prevention of BPD in very preterm monozygotic twins of less than 32 gestation weeks.MethodsIn this prospective, randomized, placebo-controlled, double-blinded multicenter clinical trial, 60 pairs of monozygotic twin preterm neonates of less than 32 weeks admitted to the Neonatal Intensive Care Unit are randomly assigned to receive intravenous ACBMNC infusion (targeted at 5 × 107 cells/kg) or placebo (normal saline) within 24 h after birth in a 1:1 ratio. The primary outcome will be survival without BPD at 36 weeks of postmenstrual age. The secondary outcomes will include the mortality rate, BPD severity, other common preterm complication rates, respiratory support duration, length and cost of hospitalization, and long-term respiratory and neurodevelopmental outcomes during a 2-year follow-up. Furthermore, we will perform single-cell RNA sequencing for cord blood cells and blood cells 3–10 days after intervention and detect whether reactive oxygen species and inflammatory cytokines are present.ConclusionThis will be the first randomized, placebo-controlled, double-blinded trial to evaluate the efficacy of ACBMNC infusion to prevent BPD in monozygotic twin premature infants and investigate the underlying protective mechanisms. The results of this trial will provide valuable clinical evidence for translational application of cord blood cell therapy in very preterm infants.Trial registration: ClinicalTrials.gov, NCT05087498, registered 10/09/2021, https://register.clinicaltrials.gov/prs/app/action/SelectProtocol?sid=S000BAD7&selectaction=Edit&uid=U0002PLA&ts=2&cx=qvyylv

Atrial Fibrillation Follow-up Investigation to Recover Memory and Learning Trial (AFFIRMING): Rationale and Design of a Multi-center, Double-blind, Randomized Controlled Trial

Background: People with atrial fibrillation (AF) have elevated risk of developing cognitive impairment. At present, there is a dearth of randomized controlled trials investigating cognitive impairment management in patients with AF. The Atrial Fibrillation Follow-up Investigation to Recover Memory and learning (AFFIRMING) study is aimed at evaluating the potential for computerized cognitive training to improve cognitive function in patients with AF. Methods: The study is a multi-center, double-blind, randomized controlled study using a 1:1 parallel design. A total of 200 patients with AF and mild cognitive decline without dementia are planned to be recruited. The intervention group will use the adaptive training software with changes in difficulty, whereas the positive control group will use basic training software with minimal or no variation in difficulty level. At the end of 12 weeks, the participants will be unblinded, and the positive control group will stop training. The intervention group will be rerandomized 1:1 to stop training or continue training. All participants will be followed up until 24 weeks. The primary endpoint is the proportion of the improvement of the global cognitive function at week 12 compared with baseline, using the Basic Cognitive Ability Test (BCAT)

Reemerging superconductivity at 48 K across quantum criticality in iron chalcogenides

Pressure plays an essential role in the induction1 and control2,3 of superconductivity in iron-based superconductors. Substitution of a smaller rare-earth ion for the bigger one to simulate the pressure effects has surprisingly raised the superconducting transition temperature Tc to the record high 55 K in these materials4,5. However, Tc always goes down after passing through a maximum at some pressure and the superconductivity eventually tends to disappear at sufficiently high pressures1-3. Here we show that the superconductivity can reemerge with a much higher Tc after its destruction upon compression from the ambient-condition value of around 31 K in newly discovered iron chalcogenide superconductors. We find that in the second superconducting phase the maximum Tc is as high as 48.7 K for K0.8Fe1.70Se2 and 48 K for (Tl0.6Rb0.4)Fe1.67Se2, setting the new Tc record in chalcogenide superconductors. The presence of the second superconducting phase is proposed to be related to pressure-induced quantum criticality. Our findings point to the potential route to the further achievement of high-Tc superconductivity in iron-based and other superconductors.Comment: 20 pages and 7 figure

Flight demonstration of the separation analysis methodology for continuous descent arrival”, Seventh USA/Europe ATM R&D Seminar

Abstract The Tool for the Analysis of Separation And Throughput (TASAT) has been developed to predict the trajectories of different aircraft performing a given continuous descent arrival (CDA) and thereby determine the minimum spacing at a metering point such that there is a high probability of no separation violations during the remainder of the procedure. The resulting reduced need for controller intervention is expected to facilitate the implementation of CDA. This tool includes a fast-time Monte Carlo aircraft trajectory simulation environment and a theoretically rigorous separation analysis methodology based on probabilistic characteristics of aircraft trajectory variations. The tool was used to determine the target spacing between aircraft at the metering point for the Area Navigation based Continuous Descent Arrival flight test project conducted in September 2004 at Louisville International Airport. The flight test results indicated that the determined 15 nm target spacing yielded conditional probabilities of 69.6% for CDA to runway 35L, which is very close to the predicted value of 68.6%. The flight test also indicated an overall total probability of 81.7%, which is between the predicted overall total probabilities of 79.6% and 85.0% for the CDA to runway 35L and 17R respectively. The flight test demonstrated that with the tool developed, Continuous Descent Arrival can be efficiently implemented under moderate to moderately high traffic conditions to achieve environmental and economical benefits