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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.
211

The Use of Case-Based Reasoning in a Human-Robot Dialog System

Eliasson, Karolina January 2006 (has links)
As long as there have been computers, one goal has been to be able to communicate with them using natural language. It has turned out to be very hard to implement a dialog system that performs as well as a human being in an unrestricted domain, hence most dialog systems today work in small, restricted domains where the permitted dialog is fully controlled by the system. In this thesis we present two dialog systems for communicating with an autonomous agent: The first system, the WITAS RDE, focuses on constructing a simple and failsafe dialog system including a graphical user interface with multimodality features, a dialog manager, a simulator, and development infrastructures that provides the services that are needed for the development, demonstration, and validation of the dialog system. The system has been tested during an actual flight connected to an unmanned aerial vehicle. The second system, CEDERIC, is a successor of the dialog manager in the WITAS RDE. It is equipped with a built-in machine learning algorithm to be able to learn new phrases and dialogs over time using past experiences, hence the dialog is not necessarily fully controlled by the system. It also includes a discourse model to be able to keep track of the dialog history and topics, to resolve references and maintain subdialogs. CEDERIC has been evaluated through simulation tests and user tests with good results. / <p>Report code: LiU{Tek{Lic{2006:29.</p>
212

Helicopter money / Helikopterpengar

Olsson, Julia, Nilsonne, Sophie January 2016 (has links)
This thesis has been conducted through a qualitative research method in order to explain the concept of helicopter money and how to implement it in Sweden in line with present law. Milton Frideman was the first to coin the concept of helicopter money. His theory was that a permanent increase of the monetary base via money transferring to households would increase the aggregate demand and consequently result in an increase of the inflation level. Further Ben Bernanke has developed this theory to not only include transferring money to households but to the government in order to enable an increase in public spending and increase of inflation. Helicopter money is a form of direct monetary financing, which is illegal in Sweden today. There are ways to implement it though by doing an implicit transfer to the government through purchases of treasury bonds that are held in infinity. Helicopter money therefore requires cooperation between the government and the Riksbank. In order for helicopter money to be a sufficient tool the money that are being transferred needs to be consumed. Helicopter money has the unique quality that it’s irredeemable. Which result in an asymmetric treatment of the money, which mean that households never have to repay these money and therefore the consumption propensity rises. Helicopter money also weakens the currency, which results in an increase of inflation. Transferring money to the households would probably increase the inflation level but it also entails risks. If we on the other hand transfer the money to the government we can be absolutely certain that inflation will rise. The best way to implement helicopter money in order to achieve a higher inflation and at the same time taking present law into account is therefore to make an implicit transfer to the government. A good communication and explanation of the intentions are of great importance in order to retain the trust of the government and institutions. / Denna uppsats har genom en kvalitativ undersökning redogjort för begreppet helikopterpengar samt vilka förutsättningar som krävs för att implementera det i Sverige med hänsyn till rådande lagstiftning. Helikopterpengar bygger på en teori av Milton Friedman och innebär en permanent ökning av penningmängden via en transferering till hushållen vilket resulterar i en ökad aggregerad efterfråga och stigande inflation. Begreppet har utvecklats av bland annat Ben Bernanke som menar på att en transferering av helikopterpengarna likväl kan ske till staten för att öka offentliga utgifter och på det sättet driva upp inflationen. Helikopterpengar är en typ av direkt monetär finansiering som är förbjuden i Sverige med dagens lagstiftning. Det går dock att praktiskt tillämpa helikopterpengar genom att göra en indirekt transferering till staten genom köp av statsobligationer som hålls för evigt. Helikopterpengar kräver alltså ett samarbete mellan staten och Riksbanken. För att helikopterpengar ska få önskad effekt bygger det på att pengarna konsumeras. Helikopterpengar innebär en asymmetrisk behandling av pengarna vilket gör att hushållen inte behöver betala tillbaka pengarna i framtiden och konsumtionsbenägenheten ökar. Helikopterpengar urholkar kronans värde vilket leder till en svagare valuta som i sin tur också bidrar till en ökad inflation. En transferering till hushållen skulle med stor sannolikhet ge effekt på inflationsnivån men medför även risker. Genomförs däremot en transferering till staten kommer inflationen med säkerhet att öka då staten kan se till att varje krona spenderas. Bästa sättet att implementera helikopterpengar för att få störst effekt med hänsyn till rådande lagstiftning är alltså att göra en indirekt transferering till staten. Det är även viktigt att kommunicera intentionerna på ett pedagogiskt sätt för att marknaden ska behålla förtroendet för pengar och institutionerna.
213

Typologies of Helicopter Parenting in American and Chinese Young-Adults’ Game and Social Media Addictive Behaviors

Hwang, Woosang, Jung, Eunjoo, Fu, Xiaoyu, Zhang, Yue, Ko, Kwangman, Lee, Sun A., Lee, Youn Mi, Lee, Soyoung, You, Hyun Kyung, Kang, Youngjin 01 January 2022 (has links)
Helicopter parenting has emerged as a prevalent phenomenon in families with adult children. Due to its developmentally inappropriate nature, helicopter parenting sometimes serves as a risk factor for children. In addition, culture and parents’ gender shape parenting and adult children’s outcomes. The purpose of the present study was to identify multidimensional constructs of helicopter parenting among college students and describe how latent classes of helicopter parenting of mothers and fathers are related to college students’ game and social media addictive behaviors in the United States and China. Using a three-step latent class approach, data from 1402 mother and young-adult child (MC) and 1225 father and young-adult child (FC) pairs in the United States and 527 MC and 426 FC pairs in China were analyzed. Four helicopter parenting latent classes (strong, strong but weak direct intervention, weak but strong academic management, and weak) were identified among MC and FC pairs in the United States, but three latent classes (strong, strong but weak direct intervention, and weak) were identified in China. In addition, college students whose parents were in the strong helicopter parenting class reported a higher level of game and social media addictive behaviors than those in weak and weak but strong academic management classes in the United States, but not in China. These findings indicate that helicopter parenting is multidimensional in nature in both American and Chinese families, but the impact of helicopter parenting on college students’ game and social media addictive behaviors differs between the two countries.
214

Tracheal Tube Misplacement after Emergency Intubation in Pediatric Trauma Patients: A Retrospective, Exploratory Study

Rost, Franziska, Donaubauer, Bernd, Kirsten, Holger, Schwarz, Thomas, Zimmermann, Peter, Siekmeyer, Manuela, Gräfe, Daniel, Ebel, Sebastian, Kleber, Christian, Lacher, Martin, Struck, Manuel Florian 02 June 2023 (has links)
Inadvertent tracheal tube misplacement and particularly endobronchial intubation are well-known complications of emergency endotracheal intubation (ETI) in pediatric trauma patients, which require repositioning of the tube to avoid impairment of gas exchange. The main aim of study was to identify the frequency of tube misplacement and associated factors of pediatric trauma patients who received ETI either by prehospital physician-staffed emergency medical service (EMS), or at emergency department (ED) admission to a single level-1 trauma center. Sixty-five patients (median age 14 years and median injury severity score 29) were included. Of these, 30 underwent helicopter EMS ETI, 29 ground EMS ETI, and 6 ED ETI. Seventeen cases (26%) of tracheal tube misplacement were recognized. After multivariable analysis, tracheal tube misplacement was independently negatively associated with body weight (OR 0.86; 95% CI, 0.76–0.99; p = 0.032) and helicopter EMS ETI (OR 0.20; 95% CI, 0.04–0.97; p = 0.036). Two of nineteen patients received tube thoracostomy due to endobronchial intubation. Mortality and length of stay were comparable in patients with misplaced tubes and correctly placed tubes. The results suggest that particularly small children require attention to avoid tracheal tube misplacement, which emphasizes the need for special training. Helicopter EMS physicians’ expertise might be beneficial in prehospital pediatric trauma patients requiring advanced airway management.
215

Process Improvement of Surface Preparation of Structuraly Bonded Helicopter Detail Parts / Process Improvement of Surface Preparation of Structurally Bonded Helicopter Detail Parts

Tafoya, Keirsten Breann 12 1900 (has links)
The objective of this study was to increase the bond strength at the surface interface of a thin stainless-steel panel for structural bonding on a helicopter. To achieve this objective, six activation methods for applying the coating to the panel in the surface preparation process are presented and explored. Adhesion and roughness tests were conducted to determine which method consistently initiates the etch and improves the bond at the surface. Based on the test results, three methods proved to be effective in initiating the etch. Of the three effective methods, only one method exhibited significantly improved bond strength at the surface interface as well as consistently initiated the etch in solution. The applicability of this method is discussed, and recommendations are presented for further study.
216

Constrained Control for Helicopter Shipboard Operations and Moored Ocean Current Turbine Flight Control

Ngo, Tri Dinh 30 June 2016 (has links)
This dissertation focuses on constrained control of two applications: helicopter and ocean current turbines (OCT). A major contribution in the helicopter application is a novel model predictive control (MPC) framework for helicopter shipboard operations in high demanding sea-based conditions. A complex helicopter-ship dynamics interface has been developed as a system of implicit nonlinear ordinary differential equations to capture essential characteristics of the nonlinear helicopter dynamics, the ship dynamics, and the ship airwake interactions. Various airwake models such as Control Equivalent Turbulence Inputs (CETI) model and Computation Fluid Dynamics (CFD) data of the airwake are incorporated in the interface to describe a realistic model of the shipborne helicopter. The feasibility of the MPC design is investigated using two case studies: automatic deck landing during the ship quiescent period in sea state 5, and lateral reposition toward the ship in different wind-over-deck conditions. To improve the overall MPC performance, an updating scheme for the internal model of the MPC is proposed using linearization around operating points. A mixed-integer MPC algorithm is also developed for helicopter precision landing on moving decks. The performance of this control structure is evaluated via numerical simulations of the automatic deck landing in adverse conditions such as landing on up-stroke, and down-stroke moving decks with high energy indices. Kino-dynamic motion planning for coordinated maneuvers to satisfy the helicopter-ship rendezvous conditions is implemented via mixed integer quadratic programming. In the OCT application, the major contribution is that a new idea is leveraged from helicopter blade control by introducing cyclic blade pitch control in OCT. A minimum energy, constrained control method, namely Output Variance Constrained (OVC) control is studied for OCT flight control in the presence of external disturbances. The minimum achievable output variance bounds are also computed and a parametric study of design parameters is conducted to evaluate their influence on the OVC performance. The performance of the OVC control method is evaluated both on the linear and nonlinear OCT models. Furthermore, control design for the OCT with sensor failures is also examined. Lastly, the MPC strategy is also investigated to improve the OCT flight control performance in simultaneous satisfaction of multiple constraints and to avoid blade stall. / Ph. D.
217

Upgrade of a LabVIEW based data acquisition system for wind tunnel test of a 1/10 scale OH-6A helicopter fuselage

Lines, Philipp A. 06 1900 (has links)
Approved for public release, distribution is unlimited / For over half a century the NPS Aerolabʼ Low Speed Wind Tunnel located in Halligan Hall of the Naval Postgraduate school has served to provide students and faculty with meaningful aerodynamic data for research and problem analysis. New data acquisition hardware was installed three years ago but never fully verified, and contained no integrated software program to collect data from the strain-gauge balance pedestal. Existing National Instruments based hardware for the NPS low-speed wind tunnel was reconfigured to obtain data from the strain-gauge pedestal. Additionally, a data acquisition software program was written in LabVIEW⠭ to accommodate the hardware. The Virtual Instruments (VI) program collects and plots accurate data from all four strain gauges in real-time, producing non-dimensional force and moment coefficients. A research study on the performance of an OH-6A helicopter fuselage was conducted. NPS Aerolabʼ wind tunnel tests consisted of drag, lift, and pitching moment measurements of the OH-6A along yaw and angle-of-attack sweeps. The results of the NPS wind tunnel data were compared against testing conducted on a full-scale OH-6A helicopter in NASA Ames' 40 ft. x 80ft. wind tunnel, along with the U.S. Army's Light Observation Helicopter (LOH) wind tunnel tests. Results of current testing substantiate the LabVIEW⠭ code. / Ensign, United States Navy
218

The nonlinear modelling and model predictive control of a miniature helicopter UAV

01 August 2012 (has links)
M.Ing. / Linear control system theory is well developed and has lead to a number of control system types with well-defined design methods that can be applied to any linear system. Unfortunately, no system in nature is truly linear. As a result, such non-linear systems must be represented by a linear model that is accurate over some region of the operating states of the system. The success of linear control theory in commercial applications is testament to the fact that some types of systems can be adequately represented by a linear model. However, systems with time-varying dynamics or non-linearities such as input or operating state saturation cannot always be adequately controlled by linear control systems. For that reason, non-linear control techniques must be investigated. This project aims to investigate Non-linear Model Predictive Control theory and practical implementation in the context of developing an autopilot for an Unmanned Aerial Vehicle based on a miniature helicopter. A non-linear model of the dynamics of an X-Cell Spectra G radio-controlled helicopter was developed based on the existing literature. A number of experiments were performed to determine the parameters of this model. Significant future work exists in designing additional ground experiments since certain parameters are difficult to measure safely in the laboratory. Additional work to improve the accuracy of the model at high airspeeds, as well as incorporating a more accurate yaw dynamics model, is also required. Following this, a Non-linear Model Predictive Control autopilot was simulated using MATLAB®. The simulation tested the effects of control system parameters such as control horizon and sampling period, as well as the sensor noise susceptibility and its ability to handle wind as a random disturbance. The results determined adequate control system parameters for level flight as well as landing the helicopter under ideal conditions. Simulations in which sensor noise and wind were added showed that the control system is significantly affected by sensor noise and that it cannot hover in the presence of wind. A real-time implementation was not achieved during this work; however, several directions for future research have been discussed.
219

Fracturation polyphasée et contrôles des gisements de nickel supergène de Nouvelle-Calédonie : Nouvelles méthodes d’exploration et modèles de gisements / Polyphase fracturing and control of supergene nickel deposits in New Caledonia : New exploration methods and deposit models

Iseppi, Marion 23 October 2018 (has links)
La connaissance minéralogique et géochimique des gisements de nickel latéritique est sans aucun doute plus approfondie que celle de leur structuration. En effet, le profil d’altération oblitère le réseau de fracture affectant la roche mère sous-jacente, pourtant indispensable pour l’évaluation de la ressource car elle contrôle l’essentiel de l’altération et donc la libération du nickel. La Nappe des Péridotites de Nouvelle-Calédonie constitue un objet exceptionnel d’étude de la fracturation au sein d’une ophiolite mantellique car le soulèvement majeur et les phases d’érosion subséquentes, qu’elle a subis du Miocène à l’Actuel, ont permis de mettre au jour la structure en trois dimensions. Cependant, la facilité d’accès à la ressource fait qu’à ce jour assez peu d’études structurales ont été conduites sur les gisements, ou le plus souvent, sont restées confidentielles. L’objectif de cette étude est de mieux comprendre l’influence de la structuration de l’ophiolite sur la genèse des gisements de nickel latéritique en Nouvelle-Calédonie. Cette étude multi-échelle a porté sur l’ensemble de la Nappe des Péridotite et se scinde en deux volets : 1) une étude structurale de terrain, et 2) l’interprétation de données d’électromagnétisme nouvellement acquises. Cette campagne de géophysique héliportée a été effectuée sur trois zones minières représentatives des différents types (morphologiques et génétiques) de gisements rencontrés en Nouvelle-Calédonie (les massifs de Koniambo et du Kopéto-Boulinda et au sud, la zone de Plaines des Lacs – Goro - Port-Boisé).L’analyse de la fracturation des péridotites est primordiale pour comprendre les chemins de migration des eaux météoriques et donc les variations d’épaisseur du profil d’altération. Une approche minéralogique et texturale est nécessaire afin de distinguer les différents épisodes de fracturation et de remplissage statiques ou cinématiques, et permet de proposer une chronologie relative. À la suite de cet inventaire, il est possible d’identifier ces objets sur les profils d’électromagnétisme. Cette analyse permet de visualiser la géométrie des structures jusqu’à une profondeur de 300 m et montre un lien direct entre les approfondissements du profil d’altération et la présence de certaines fractures. Ainsi, il apparait clairement que les eaux météoriques empruntent des chemins préférentiels fonction de la morphologie générale du massif elle-même issue des structures héritées.La géométrie des structures visualisées par la géophysique, combinée aux observations de terrain, permet de mieux appréhender la complexité du système. A l’issue de ce travail, il est possible de replacer chacun des types d’objets observés dans leur contexte géodynamique et ainsi de restituer l’histoire de l’ophiolite depuis l’accrétion océanique jusqu’à son émersion à l’Oligocène. Un modèle révisé de la genèse des gisements de nickel en Nouvelle-Calédonie est présenté et de nouveaux guides d’exploration sont proposés. L’électromagnétisme s’avère être une méthode particulièrement adaptée pour visualiser la géométrie globale du profil d’altération et constitue une aide substantielle à la prospection et la modélisation des gisements de nickel. / The mineralogical and geochemical understanding of lateritic nickel ore deposits is undoubtedly better constrained than their tectonic structure. Indeed, the fracture network of the underlying bedrock is typically concealed beneath a thick weathering profile. However, this fracture network strongly controls weathering and ultimately nickel release from peridotites, thus improving its knowledge appears critical in the evaluation of nickel resources. In New Caledonia, the Peridotite Nappe is a particularly outstanding case study because Early Miocene to Recent uplift and subsequent erosion allow the structure of a mantle ophiolite to be observed in three dimensions. However, due to the easy access to nickel resources, only a few structural studies have been undertaken, or remained confidential. The main objective of this study is to better constrain the role of the fracture network of the Peridotite Nappe in the genesis of New Caledonia’s lateritic nickel ore deposits.A multiple-scale study of the whole Peridotite Nappe has been performed following two main parts: i) field-based structural observations and analyses; and 2) interpretation of new acquired heliborne electromagnetic data. The latter focused on three mining areas (massifs of Koniambo and Kopéto-Boulinda; and, Plaine des Lacs – Goro - Port-Boisé), which are representative of the different types (morphologic and genetic) of nickel ore deposits encountered in New Caledonia.The study of the fracture network is essential in the understanding of the migration of meteoric waters and thus thickness variations of the weathering profile of peridotites. A mineralogical and textural approach has been undertaken to distinguish the various steps of fracture development on the basis of static or synkinematic infill events and eventually allowed a relative chronology to be proposed. Following this inventory, it has been possible to identify these objects on electromagnetism profiles. This analysis allows visualizing the geometry of controlling fractures at depth and reveals a direct link between deepening of the weathering profile and the fracture network. Ultimately, it clearly appears that meteoric waters use preferential pathways that in turn depend on the geomorphology of each massif, which originate from the inherited fracture network. The combination of geophysical data interpretation and field observations allow a better understanding of the complex nappe structure. Our results allow every described tectonic object to be replaced in its geodynamic setting and thus the full ophiolite history to be restored, from oceanic accretion to emersion in Oligocene. A refined model for the genesis of New Caledonia’s lateritic nickel ore deposits is proposed, as well as additional metallotects for exploration. Electromagnetism appears to be appropriate for describing the overall geometry of the weathering profile and can be useful in prospecting and modelling nickel ore deposits.
220

Controle robusto descentralizado de movimentos coordenados de robôs heterogêneos / Decentralized robust control of coordinated movements of heterogeneous robots

Inoue, Roberto Santos 12 January 2012 (has links)
Este trabalho trata da coordenação de robôs heterogêneos que consiste em um robô helicóptero e em múltiplos robôs móveis com rodas, de modo que estes sigam um líder. Para atingirmos este objetivo, neste trabalho desenvolve-se a estimação da atitude e posição de um robô utilizando filtros robustos. Os filros realizam a fusão dos sinais de uma unidade de medida inercial de baixo custo e de um receptor GPS (Global Positioning System) considerando um modelo de corpo rígido formulado em termos de quatérnios. Resultados experimentais são apresentados baseados em um estudo comparativo entre os filtros robustos e o filtro de Kalman. Desenvolve-se o controle de um robô móvel com rodas deslizantes e de um robô helicóptero. Para realizar o controle robusto utilzia-se um regulador robusto recursivo. Simulaçõoes do robô móvel com rodas deslizantes e do robô helicóptero são apresentadas utilizando os parâmetros de um robô móvel Pioneer 3AT e de um robô helicóptero RMAX. Desenvolve-se também um mini robô helicóptero e uma base de movimento para realização de testes de controle do mini robô helicóptero constiste de um mini helimodelo e de um piloto automático baseado em um microprocessador com conectividade Wi-Fi, uma unidade de medida inercial e uma placa de controle de servos motores. E por fim, desenvolve-se a coordenação de robôs heterogêneos de modo que estes sigam um líder. Para isto é utilziado um controlador descentralizado e cooperativo cuja finalidade é gerar trajetórias de referência para que os robôs heterogênos se movimentem em formação rígida. / This research deals with the coordination of the heterogeneous robots, consisting of a robotic helicopter and multiple uheeled mobile robots, to achieve this aim this work develops the estimation of attitude, heading and positions of a robot based on robust filters. The filters perform the fusion of the signals of a low-cost inertial measurement unit and a GPS (Global Positioning System) receiver considering a rigid body model formulated in terms of quaternions. Experimental results are presented based on a comparative study of the robust filters and Kalman filter. It develops a robust control scheme of a ski-steering mobile robot and a robotic helicopter. The robust control is performed through a the robust recursive regulator. Simulations of the skid-steering mobile robot and a robotic helicopter are presented using the parameters of a Pioneer 3AT and a robotic helicopter RMAX. It also develops a mini robotic helicopter and a motion base to perform control test of a mini robotic helicopter. The mini robotic helicopter consists of a mini helicopter TREX 450 XL and an autopilot based on a microprocessor with Wi-Fi, an inertial measurement unit a servo control board. To finish, it develops the coordination of the heterogeneous robots in order to perform a leader strategy based on the concept of rigid formation.

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