A statistical approach for electric taxiing requirements for regional turboprop aircraft

Abstract : Electric motorization of the landing gear appears to be one of the alternative solutions to reduce fuel burn, CO2 emissions, and noise during the taxi phase. Because turboprop aircraft operate on short routes, the taxi phase represents an important part of both flight time and fuel consumption. An Electric Taxiing System (ETS) sized to meet current operational practices could reduce the fuel consumption and remain near transparent to the pilots. This paper first presents a statistical approach to define the taxiing requirements for regional turboprop aircraft using 200 taxi phases of 77 aircraft. Requirements of 0.4 m/s2 maximum acceleration until 15 kts, 25 kts top speed, and 13,000 ft distance (including taxi-in and taxi-out) are determined in accordance with the analysis, operational practices, and pilots’ routines. For higher speed than 15 kts, the acceleration requirement is adjusted using the iso-power to limit the mass of the ETS. Then, an ETS with sufficient performance is sized to be integrated in the main landing gear of a regional turboprop aircraft (Dash 8-300). For a standard mission of 270 nautical miles, the expected fuel economy is 3.1 % for a payload loss of 2.2 % or 1.3 PAX due to the system weight

Sizing and performance estimation of the payload lifting with a circling single fixed-wing tethered aircraft

Abstract: Interest in transporting payload by air has grown significantly since the 1950s with the necessity of lifting heavy infrastructures such as power lines or reaching remote locations for mining exploitation. Nowadays, vertical take-off and landing (VTOL) aircraft fulfil some of these missions. Despite great improvements over the last two decades with the democratization of tiltrotor aircraft, these advances focus on improving the high-speed capabilities, not their hover efficiencies. Moreover, no rotorcraft can reach 60,000 ft to observe a suspicious balloon due to their limited ceiling, while a light fixed-wing aircraft can and even loiter around.Résumé de la communication présentée lors du congrès international tenu conjointement par Canadian Society for Mechanical Engineering (CSME) et Computational Fluid Dynamics Society of Canada (CFD Canada), à l’Université de Sherbrooke (Québec), du 28 au 31 mai 2023

Development of a thruster-based payload stabilization method for a single-airplane tethered lifting system

Abstract: Vertical lifting operations with aircraft are essential during emergencies, to access remote regions and for various construction operations, even though they are costly. Helicopters are typically used for these operations, but these aircraft are known for their high operating cost partly due to their mechanical complexity and fuel consumption. An alternative method for vertical load lifting includes airships. However, they lack the manoeuvrability required for most aerial operations, they require oversized hangars for storage, and use helium, a limited resource gas. An alternative approach to efficiently lift a payload consists on using high-efficiency airplanes flying along a circular path while being tethered to a centralized payload. The system aims to replace the highly loaded rotor disk of a rotorcraft by high-efficiency airplane wings. The payload has to remain at the centre of the trajectory for such a lifting method to work. The payload can maintain a steady position using either (1) a multi-airplane configuration to balance the lateral loads or using (2) a long tether and accept some payload motion, as demonstrated as early as 1942 for cargo delivery. In addition to a 5-fold reduction in power requirements for the same payload, this concept enables to reuse commercial airplanes with minimal mechanical modifications.In order to minimize the system complexity while providing a precise payload position, the current work focus on the development of a thruster-based Payload Control System (PCS) for a single circling airplane. Installed at the tip of the tether, the PCS first allows for a precise positioning of the payload to compensate the airplane trajectory deviation and the aerodynamic forces on the tether. Second, the PCS allows for a shorter tether, which diminishes the influence of aerodynamic forces on the system. Third, the PCS creates a rotating force around the payload to compensate the lateral force imbalance in the case of a single tether concept. As a result, the PCS is the missing key to enable efficient single-tethered airplane payload delivery and aerial work in remote regions.This presentation aims to present the latest developments in the PCS design, numerical simulations, and experimental results. The prototype is designed to control the lateral position and yaw of a 2 kg payload (including the PCS) under a UAV simulating the circular trajectory of an airplane. This PCS is equipped with a Pixhawk flight controller, real-time kinematics GPS and five thrusters.Résumé de la communication présentée lors du congrès international tenu conjointement par Canadian Society for Mechanical Engineering (CSME) et Computational Fluid Dynamics Society of Canada (CFD Canada), à l’Université de Sherbrooke (Québec), du 28 au 31 mai 2023

Overview of the challenges of alternative propulsion systems applied to business aircraft

Abstract: In order to reduce greenhouse gas emissions and reach the 2050 net-zero emissions target, the aviation sector is looking towards new propulsion architectures, such as electric, hybrid-electric, and hydrogen powertrains. The integration of these kinds of new powertrain technologies has a significant impact on aircraft performance. The loss of performance typically consists of a range reduction, a reduced payload capacity, a lower cruise speed than the baseline aircraft, etc. Cost in capabilities does not have the same impact depending on business or commercial aviation, as these are two radically different markets. The travel routes for a given airline are constant and well-known, and a loss of aircraft performance capability may therefore be acceptable, this is not the case for business aviation due to hard operational constraints. The operational constraints of business aircraft are reflected in a higher cruise speed than commercial aviation, a flight altitude above commercial traffic, a long-range capability, high volume and comfort of the cabin, the capability to takeoff and land at small regional airports, and so on. Since the operational flexibility of the aircraft is at the heart of the business aviation market and dependent on these performance indicators, these requirements are necessary to maintain the high level of competitiveness of the aircraft. The literature mainly focuses on the greenhouse gas emissions reduction of retrofitted aircraft without considerations for keeping the same level of performance as the baseline aircraft. As business aviation is expected to experience growth in deliveries over the next few years, the assessment of the impact of alternative propulsion systems on the performance of aircraft is crucial. Since all new propulsion technologies for the mitigation of aviation carbon footprint have drawbacks, the integration of these systems should result in an acceptable trade-off between the operational capabilities of the aircraft and CO2 emissions reduction. This paper presents the cost in performance and the key challenges of alternative propulsion system integration of business aircraft. The analysis focuses on three main architectures, the all-electric powertrain, hydrogen-powered aircraft, and parallel hybrid powertrain. The objective is to provide an overview of business aircraft requirements, the impact of alternative propulsion systems on such aircraft, and the key challenges to meet the operational constraints of the business aviation market.Résumé de la communication présentée lors du congrès international tenu conjointement par Canadian Society for Mechanical Engineering (CSME) et Computational Fluid Dynamics Society of Canada (CFD Canada), à l’Université de Sherbrooke (Québec), du 28 au 31 mai 2023

Analyse structurelle et validation expérimentale d'un Rim-Rotor Rotary Ramjet Engine (R4E)

Le Rim-Rotor Rotary Ramjet Engine (R4E) est un moteur très haute densité de puissance utilisant des statoréacteurs en rotation pour produire un couple à grande vitesse angulaire.Le design structurel d'une première génération de R4E est présenté dans ce mémoire ainsi qu'une validation expérimentale avec combustion haute température. Ces travaux s'imbriquent dans un programme de recherche où l'objectif ultime est de démontrer expérimentalement qu'il est possible de produire de la puissance positive de ce type de moteur. La structure principale du moteur est basée sur l'utilisation d'un Rim-Rotor, un anneau de Carbone-PEEK unidirectionnel, qui reprend partiellement le chargement des propulseurs en compression. Un moyeu en aluminium en une pièce inclut les propulseurs et supporte le système d'allumage inductif intégré à la structure. Ce dernier a été caractérisé indépendamment afin de connaître l'effet des paramètres tels la distance entre les électrodes sur la puissance et l'énergie des étincelles.Le concept final proposé pèse 76 g, ne contient que 5 pièces dans un assemblage unique et peut résister à une vitesse tangentielle de 330 m/s (120 krpm) au niveau des propulseurs lors d'une combustion d'hydrogène de 1 sec. Un autre concept présenté est conçu pour résister 560 m/s (200 krpm) pour des durées de combustion très courtes, sans échauffement significatif des composants. Un modèle structurel analytique est proposé et validé par un modèle numérique ainsi que des essais expérimentaux sans combustion réalisés jusqu'à 188 krpm sans rupture.Le prototype conçu pour la combustion est validé par rapport à ses paramètres de conception et une rupture des pales de turbine survient tel que prédit par le modèle couplé thermique-structurel numérique. Les recherches ont démontré que le concept d'un R4E est viable et qu'il a le potentiel d'atteindre une vitesse tangentielle de près de 1000 m/s en utilisant des matériaux disponibles aujourd'hui. Les dissimilitudes d'expansion thermique entre les composantes, la différence de rigidité entre les pièces de l'assemblage ainsi que le transfert de chaleur vers le Rim-Rotor ont été identifiés comme des considérations importantes pour les futurs concepts de R4E

Big Ramsey degrees and infinite languages

This paper investigates big Ramsey degrees of unrestricted relational structures in (possibly) infinite languages. While significant progress has been made in studying big Ramsey degrees, many classes of structures with finite small Ramsey degrees still lack an understanding of their big Ramsey degrees. We show that if there are only finitely many relations of every arity greater than one, then unrestricted relational structures have finite big Ramsey degrees, and give some evidence that this is tight. This is the first time that finiteness of big Ramsey degrees has been established for an infinite-language random structure. Our results represent an important step towards a better understanding of big Ramsey degrees for structures with relations of arity greater than two.Comment: 21 pages. An updated version strengthening the statement of the positive results and fixing a mistake in the earlier version of the negative result which now needs an extra assumptio

Assessing Wind Impact on Semi-Autonomous Drone Landings for In-Contact Power Line Inspection

In recent years, the use of inspection drones has become increasingly popular for high-voltage electric cable inspections due to their efficiency, cost-effectiveness, and ability to access hard-to-reach areas. However, safely landing drones on power lines, especially under windy conditions, remains a significant challenge. This study introduces a semi-autonomous control scheme for landing on an electrical line with the NADILE drone (an experimental drone based on original LineDrone key features for inspection of power lines) and assesses the operating envelope under various wind conditions. A Monte Carlo method is employed to analyze the success probability of landing given initial drone states. The performance of the system is evaluated for two landing strategies, variously controllers parameters and four level of wind intensities. The results show that a two-stage landing strategies offers higher probabilities of landing success and give insight regarding the best controller parameters and the maximum wind level for which the system is robust. Lastly, an experimental demonstration of the system landing autonomously on a power line is presented

SERCA2 Regulates Non-CF and CF Airway Epithelial Cell Response to Ozone

Calcium mobilization can regulate a wide range of essential functions of respiratory epithelium, including ion transport, ciliary beat frequency, and secretion of mucus, all of which are modified in cystic fibrosis (CF). SERCA2, an important controller of calcium signaling, is deficient in CF epithelium. We conducted this study to determine whether SERCA2 deficiency can modulate airway epithelial responses to environmental oxidants such as ozone. This could contribute to the pathogenesis of pulmonary exacerbations, which are important and frequent clinical events in CF. To address this, we used air-liquid interface (ALI) cultures of non-CF and CF cell lines, as well as differentiated cultures of cells derived from non-CF and CF patients. We found that ozone exposure caused enhanced membrane damage, mitochondrial dysfunction and apoptotic cell death in CF airway epithelial cell lines relative to non-CF. Ozone exposure caused increased proinflammatory cytokine production in CF airway epithelial cell lines. Elevated proinflammatory cytokine production also was observed in shRNA-mediated SERCA2 knockdown cells. Overexpression of SERCA2 reversed ozone-induced proinflammatory cytokine production. Ozone-induced proinflammatory cytokine production was NF-κB- dependent. In a stable NF-κB reporter cell line, SERCA2 inhibition and knockdown both upregulated cytomix-induced NF-κB activity, indicating importance of SERCA2 in modulating NF-κB activity. In this system, increased NF-κB activity was also accompanied by increased IL-8 production. Ozone also induced NF-κB activity and IL-8 release, an effect that was greater in SERCA2-silenced NF-κB-reporter cells. SERCA2 overexpression reversed cytomix-induced increased IL-8 release and total nuclear p65 in CFTR-deficient (16HBE-AS) cells. These studies suggest that SERCA2 is an important regulator of the proinflammatory response of airway epithelial cells and could be a potential therapeutic target

Targeted deletion of a 170-kb cluster of LINE-1 repeats and implications for regional control.

Approximately half the mammalian genome is composed of repetitive sequences, and accumulating evidence suggests that some may have an impact on genome function. Here, we characterized a large array class of repeats of long-interspersed elements (LINE-1). Although widely distributed in mammals, locations of such arrays are species specific. Using targeted deletion, we asked whether a 170-kb LINE-1 array located at a mouse imprinted domain might function as a modulator of local transcriptional control. The LINE-1 array is lamina associated in differentiated ES cells consistent with its AT-richness, and although imprinting occurs both proximally and distally to the array, active LINE-1 transcripts within the tract are biallelically expressed. Upon deletion of the array, no perturbation of imprinting was observed, and abnormal phenotypes were not detected in maternal or paternal heterozygous or homozygous mutant mice. The array does not shield nonimprinted genes in the vicinity from local imprinting control. Reduced neural expression of protein-coding genes observed upon paternal transmission of the deletion is likely due to the removal of a brain-specific enhancer embedded within the LINE array. Our findings suggest that presence of a 170-kb LINE-1 array reflects the tolerance of the site for repeat insertion rather than an important genomic function in normal development

A Review of Hot Deck Imputation for Survey Non-response

L'imputation hot deck est une méthode de gestion des données manquantes dans laquelle chaque valeur manquante est remplacée par une réponse observée à partir d'une unité“similaire.” Bien qu'elle soit largement utilisée en pratique, sa théorie n'est pas aussi développée que celle des autres méthodes d'imputation. Nous avons constaté qu'il n'existe aucun consensus quant à la meilleure faon d'appliquer les hot deck et obtenir des inférences à partir de la série de données complète. Ici, nous passons en revue les différentes formes de hot deck et les recherches existantes sur ses propriétés statistiques. Nous décrivons les applications du hot deck actuellement utilisées, y compris le hot deck du Bureau US du recensement pour la Current Population Survey (CPS). Nous proposons aussi des exemples nombreux de variations du hot deck à la troisième National Health and Nutrition Examination Survey (NHANES III). Certains domaines possibles de recherches futures sont mises en évidence.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/78729/1/j.1751-5823.2010.00103.x.pd