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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
241

Spécification de lois de commande pour hélicoptères orientée Qualités de Vol / Designing helicopter control laws with Handling Qualities objectives

Antonioli, Jean-Charles 14 September 2015 (has links)
Cette thèse s'inscrit dans le domaine de l’étude des lois de commandes de vol pour hélicoptères. Les automaticiens doivent régler les gains de ces lois de manière à respecter au mieux les exigences de Qualités de Pilotage extraites de la norme ADS-33. La norme traduit ces exigences en termes de critères de Qualités de Vol. Ils évaluent la qualité de la stabilité, de l'agilité, et du suivi des consignes du pilote par la machine. Ils traduisent la pilotabilité de l'hélicoptère pour un pilote « moyen » de référence. A part une technique d’optimisation interactive développée à la NASA et l'US Army depuis 40 ans, il n’existe pas de méthode appropriée à ce problème. Les réglages sont effectués de manière empirique et itérative. L’ONERA propose une approche méthodologique structurée. L’objectif de la thèse consiste à développer cette méthodologie de manière à gérer deux contraintes supplémentaires par rapport aux capacités des méthodes de synthèse classiques en automatique : la capacité à prendre en compte la structure contrainte des lois de commande et les exigences spécifiques en terme de Qualités de Vol selon la norme ADS-33.Une technique d'amélioration des Qualités de Vol par analyse de sensibilités entre les gains et les critères est développée. Puis une méthodologie d’initialisation des gains est proposée, via la création et l’utilisation efficace de nouveaux abaques de Qualités de Vol pour modèles équivalents simplifiés. Afin d'améliorer l'efficacité de ce réglage initial, deux contraintes supplémentaires sont prises en compte (énergie et découplage). Enfin, un processus complet de réglage est proposé : initialisation, ajustement linéaire et ajustement non linéaire. / This study is in the field of designing helicopter control laws. Designers must tune the gains of these laws in order to meet as much as possible Handling Qualities requirements from ADS-33. This standard translates these requirements in terms of Flying Qualities requirements. Then, we can evaluate the quality of the stability, of the quickness, and of the ability of the machine to follow the inputs from the pilot. Apart from an interactive optimization technique developed at NASA and US Army over the last 40 years, no appropriate method exists to solve this problem. Then, empirical iterative tunings are led. ONERA addresses this issue through a structured methodological approach. The aim of the thesis is to develop this methodology, taking into account two additional constraints compared with the capabilities of usual synthesis methods used in automatics: the capability to deal with the constraints from the control law structures and with the Handling Qualities requirements from the ADS-33 standards. A technique is developed to improve the Flying Qualities using sensitivity studies between gains and criteria. Then, a methodology to initialize the gains is developed, through the creation and the efficient usage of new Flying Qualities-based charts for equivalent simplified models. In order to improve the efficiency of the initial tuning, two additional constraints are taken into account (uncoupling and energy). Thus, a complete full procedure of tuning is proposed: initialization, linear adjustment and non linear adjustment.
242

Passenger Flight Experience of Urban Air Mobility

Persson, Daniel January 2019 (has links)
The first part of a study of passenger flight experience of Urban Air Mobility was completed. This first part included the design of different Urban Air Mobility vehicle models, in which the passenger flight experience would be quantitatively measured. A first version of a simulator setup, in which the measurements were performed, was also developed. Three concept vehicle models, a single main rotor, a side-by-side rotor and a quadrotor, were designed in the conceptual design software NDARC. The vehicles were electrically propelled with battery technology based on future technology predictions and were designed for autonomous flight with one passenger. The emissions of the vehicles were analyzed and compared with an existing turboshaft helicopter. The interface between NDARC and the flight dynamics analysis and control system software FlightCODE, which was used to create control systems to the NDARC models,  was developed to fit the vehicle configurations considered. The simulator setup was created with a VR headset, the flight simulation software X-Plane, an external autopilot software and stress sensors. Trial runs with the simulator setup were performed and gave important data for the continued development. Planned upgrades of the simulation station were presented and the continuation of the study was discussed.
243

Pojezdové a zvedací zařízení / Travelling and lifting mechanism

Bernard, Vladislav January 2010 (has links)
The thesis deals the design and calculation of handling equipment designed for transport of Bell helicopter between the airport and hangar space. The first part contains an analysis of possible mechanisms applicable to the handling of the helicopter as well as an overview of the overall evaluation of some producers, engaged in the manufacture of this type of device. The second part presents the design, necessary calculations and drawing documentation. Handling equipment is designed for loading kapacity of 2000kg with a minimum 80 mm lift of helicopter to ensure safe transportation to the required distance.
244

Analýza a porovnání technicko-provozních parametrů klasických letadel a bezpilotních prostředků pro provádění leteckých prací / Analysis and comparison of technical-operational parameters of aircrafts and UAVs used for aerial works

Cihlář, Marek January 2012 (has links)
The main content of this master's is desing of analysis and comparison of technical-operational parameters of aircrafts and UAVs used for aerial works. This theme attend to basic factors that affect selection of aeronautical technics used for aeriál works, also ekonomics and technical calculation.
245

Florida Adult Trauma Scorecard Methodology and Scene Transportation Choice

Maher, Patricia 01 January 2019 (has links)
Prehospital management of patients who are traumatically injured within the state of Florida starts with the use of the Florida Adult Trauma Scorecard Methodology. The scorecard methodology may indicate that a patient is a Trauma Alert based on applied physiological and other judgment criteria. However, patients may be transported via Helicopter Emergency Medical Services (HEMS) without justified physiological needs. Rawls’ theory of justice posits that a fair and equal distribution of social resources is essential to public wellbeing. To evaluate this premise regarding prehospital trauma transports, archival 2015 data from the Florida Department of Health Trauma Registry was obtained. Using logistic regression, each trauma scorecard assessment criteria was individually and collectively evaluated regarding its predictive likelihood of a scene responder requesting HEMS versus ground ambulance transport. Controlling for trauma center locations, all five of the triage classifications illustrated a significant likelihood (p = 0.000) of HEMS transportation requests. Category 4 (EMS Judgment) predicted the highest likelihood of HEMS transport requests (b = 2.39, Wald X2(1) = 2026.88, OR = 10.9, p = .000, CI [9.83, 12.09]). Categories 4 (14.7%) and 6 (Local Criteria; [25.8%]) illustrated unexpectedly high percentages of emergency department discharge when Trauma Alert patients were HEMS transported. Over triage of patients to HEMS without meeting physiologic criteria provides less than an equal and fair distribution of public and private resources. State-level social change can be realized through HEMS transport criteria modifications applying more stringent application of physiologic patient condition scoring when determining the mode of prehospital scene response transport.
246

Effect of Education on Adult Sepsis Quality Metrics In Critical Care Transport

Schano, Gregory R. 21 June 2019 (has links)
No description available.
247

Is Helicopter Parenting Related to College Students’ Mental Health? A Typological and Cross-Cultural Approach

Hwang, Woosang, Jung, Eunjoo, Fu, Xiaoyu, Zhang, Yue, Ko, Kwangman, Lee, Sun-A, Lee, Soyoung, You, Hyun-Kyung, Kang, Youngjin 14 November 2022 (has links)
Abstract Objective The goal of this study is to uncover latent classes of maternal and paternal helicopter parenting among American and Chinese college students, and to examine whether latent classes of maternal and paternal helicopter parenting are related to college students’ mental health (depression and self-esteem). Background Previous studies have examined the association between helicopter parenting and college students’ well-being. However, less is known about how the multidimensional construct of helicopter parenting is related to college students’ mental health across Western and Eastern cultural contexts. Method We conducted three-step latent class analyses using nine helicopter parenting indicators for 1,386 mother–child and 1,214 father–child groups in the United States and 520 mother–child and 454 father–child groups in China. Next, we tested the association between the class membership of maternal and paternal helicopter parenting and college students’ mental health. Results We identified distinct helicopter parenting latent classes among four American and Chinese parent–child groups. We also found that American college students in the strong maternal helicopter parenting latent class reported poorer mental health than those in other latent classes. Conclusion Our findings indicate that the multidimensional construct of helicopter parenting can be interpreted differently by parents and college-aged children according to their social and cultural contexts. Implications The findings of this study suggest that it is necessary to strengthen understanding of the multidimensional construct of helicopter parenting for parents with college-aged children to enable them to develop more appropriate parenting practices as well as support their children's well-being.
248

Using Remote Cameras to Estimate the Abundance of Ungulates

Taylor, Jace C 01 December 2017 (has links)
Many wildlife populations globally are experiencing unprecedented declines, and without accurate and precise estimates of abundance, we will not be able to conserve these vulnerable species. Remote cameras have rapidly advanced as wildlife monitoring tools and may provide accurate and precise estimates of abundance that improve upon traditional methods. Using remote cameras to estimate abundance may be less expensive, less intrusive, less dangerous, and less time consuming than other methods. While it is apparent that remote cameras have a place in the future of wildlife monitoring, research, and management, many questions remain concerning the proper use of these tools. In an effort to answer some of these questions, we used remote cameras to study a population of Rocky Mountain bighorn sheep (Ovis canadensis) in Utah, USA from 2012 to 2014. In Chapter 1, we compared methods using remote cameras against 2 traditional methods of estimating abundance. In Chapter 2, we evaluated the relationship between deployment time of cameras and proportion of photos needed to be analyzed to obtain precise estimates of abundance. We found that methods using remote cameras compared favorably to traditional methods of estimating abundance, and provided a number of valuable advantages. In addition, we found that remote cameras can produce precise estimates of abundance in a relatively short sampling period. Finally, we identified the optimal sampling period to produce precise estimates of abundance for our study population. Our findings can help researchers better utilize the potential of remote cameras, making them a more suitable alternative to traditional wildlife monitoring.
249

Using Remote Cameras to Estimate the Abundance of Ungulates

Taylor, Jace C 01 December 2017 (has links)
Many wildlife populations globally are experiencing unprecedented declines, and without accurate and precise estimates of abundance, we will not be able to conserve these vulnerable species. Remote cameras have rapidly advanced as wildlife monitoring tools and may provide accurate and precise estimates of abundance that improve upon traditional methods. Using remote cameras to estimate abundance may be less expensive, less intrusive, less dangerous, and less time consuming than other methods. While it is apparent that remote cameras have a place in the future of wildlife monitoring, research, and management, many questions remain concerning the proper use of these tools. In an effort to answer some of these questions, we used remote cameras to study a population of Rocky Mountain bighorn sheep (Ovis canadensis) in Utah, USA from 2012 to 2014. In Chapter 1, we compared methods using remote cameras against 2 traditional methods of estimating abundance. In Chapter 2, we evaluated the relationship between deployment time of cameras and proportion of photos needed to be analyzed to obtain precise estimates of abundance. We found that methods using remote cameras compared favorably to traditional methods of estimating abundance, and provided a number of valuable advantages. In addition, we found that remote cameras can produce precise estimates of abundance in a relatively short sampling period. Finally, we identified the optimal sampling period to produce precise estimates of abundance for our study population. Our findings can help researchers better utilize the potential of remote cameras, making them a more suitable alternative to traditional wildlife monitoring.
250

Evaluation of fatigue crack growth software for use on cracks in complex geometries

Williams, Joshua Marc 02 May 2009 (has links)
Fatigue-crack growth data for the lower arm of the Apache helicopter’s scissor assembly is presented from an Army alternate source qualification test. The lower arm model is imported to finite element analysis software to obtain the stress state at a crack location. The stress state and geometry are used in seven fatigue-crack growth cases in NASGRO and AFGROW, with an additional four cases discussed briefly. The results from the fatigue-crack growth routines are compared to the fatigue-crack growth data from the Army’s test. One case reproduces the crack growth data prior to breakthrough. Some cases are shown to be more applicable to this configuration than others are. The process of performing fatigue life estimates is discussed. Suggestions are made on the viability of this approach and possible future avenues for development.

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