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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.
1

ADVANCED RANGE TELEMETRY DYNAMIC MEASUREMENT LISTS

Luten, Robert H., Diekmann, Vernon 10 1900 (has links)
International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada / A typical telemetry system for aircraft flight-testing transmits one or several data streams to the ground for real-time display and analysis, and also records the same stream onboard for later playback. During test operations, only a fraction of the available data is used at any given time for real-time display or analysis. More efficient use of the RF channel could be realized if only the data needed for the current test point is transmitted, rather than the entirety of the data. Intelligent selection of a subset of the data stream can provide large reductions in the required telemetry downlink bandwidth. As one of the Advanced Range Telemetry (ARTM) On-Board Data Management (OBDM) initiatives, a prototype on-board data selection subsystem is being developed and demonstrated. The demonstration utilizes COTS telemetry workstations to the maximum extent possible and includes “plug-in” data requestor, selection, and server components to implement the added DML functionality. A significant objective of the OBDM/DML project will be to validate RF channel models to help minimize the amount of flight-testing necessary to validate the DML concept. This paper will discuss the OBDM/DML architecture, integration of several custom components with the COTS portions of the ARTM “test bench”, and the current status of the OBDM/DML development and test program.
2

Piezoelectric active sensor and electric impedance approach for structural dynamic measurement

Sun, Fanping 29 August 2008 (has links)
The increasing use of piezoelectric material in the last decade has led to the new discovery that piezoelectric devices may be used not only as sensors or actuators individually, but also as a sensor and actuator at the same time. This bi-directional phenomenon greatly expands the utility of piezoelectric devices, especially in the area of smart material systems and structures, such as structural dynamic measurement analysis, structural damage detection, active structural vibration and acoustic control, etc. Presented in this thesis is a new electromechanical approach for structural dynamic analysis. It uses PZT patches bonded on structures as active piezoelectric sensors, and acquires the structural information by measuring the electric admittance of the sensors. Because of the electromechanical coupling, the electric admittance is mechanically modulated by the structural dynamics through the piezoelectric effect. The structural dynamic characteristics can then be extracted using a mathematical model governing the interaction of PZT actuators and structures. In this thesis, a multi-input, multi-output mathematical model is derived based on the one-dimensional constitutive law of the PZT and the mechanical impedance approach. The model yields explicit expressions of structural mechanical mobility in terms of the measured electric admittance. Applications of the approach in smart structures are presented in the area of mechanical frequency response function extraction, structural modal analysis, and structural health monitoring. As a general issue related to the application of PZT sensor-actuators in smart structures, the energy conversion efficiency of PZT actuators has also been experimentally investigated. / Master of Science
3

Contribution à l'analyse biomécanique de l'activité en kayak. Mise en place et validation d'une chaîne de mesure dynamométrique tridimensionnelle / Biomechanical contribution to kayak activity analysis. Implementation and validation of three-dimensional dynamics measurement

Munoz Nates, Franco Miller 19 December 2013 (has links)
Les méthodes modernes d'entraînement utilisent des appareillages spécifiques appelés ergomètres sur lesquels, en particulier, des programmes d'entraînement et d'évaluation sont proposés par les entraîneurs. De tels dispositifs favorisent la continuité d'un entraînement pendant les périodes peu favorables à une pratique sportive. De même, lorsque ces outils sont instrumentés, ils apportent à l'entraîneur des informations difficilement accessibles en situation réelle de pratique. Ce travail s'inscrit dans cette problématique scientifique dont l'objet est la conception d'un ergomètre pour la pratique du kayak en ligne. Les travaux réalisés ont conduit à la conception d'un ergomètre kayak capable de reproduire les conditions d'une pratique écologique aussi précisément que possible tant d'un point de vue de la gestuelle (cinématique) que des efforts générés (dynamique) d'une part, de proposer et de valider une instrumentation afin de recueillir l'ensemble des efforts d'interaction kayakiste/ergomètre, d'autre part. De plus, cette instrumentation doit être suffisamment exigeante en termes de poids et d'encombrement pour être installée dans un kayak K1 pour réaliser des mesures in situ. Les moyens mis en œuvre donnent accès aux variables biomécaniques permettant de quantifier les éléments de base de la technique de pagayage qui constituent l'ensemble des facteurs déterminants de la performance (force, endurance, technique, etc.). Scientifiques et entraineurs ont ainsi à leur disposition un outil pour une évaluation objective des performances du kayakiste. Ce travail a été réalisé dans le cadre d'une collaboration entre l'axe RoBioss, le CAIPS et la société SENSIX. / The modern training methods developed during the last 20 years involve specific equipments named ergometer. These devices allow semi-specific training sessions on a sheltered environment to develop strength during unfavorable periods of in situ practice. They are also more and more used by coaches to evaluate athlete’s skills and aptitudes. Ergometers provide numerical information that cannot be easily measured during in situ sessions. This work is a significant contribution of the following scientific problems; firstly the design of a flat-water kayak ergometer that reproduces accurately on-water conditions, both kinematics and forces generated (dynamic) during the throughout the whole kayaking cycle, secondly, to propose and validate an instrumentation to collect every dynamic interactions between the ergometer and kayaker (hands, seat, feet). In addition, this instrumentation must be design in terms of weight, size and watertightness to be installed in a kayak K1 for in situ measurements. This instrumentation quantifies the basic biomechanics parameters of the kayaking performance such as external forces, endurance, technique, etc. As a result, researchers and coaches will be able to evaluate kayakers’ performance using an unbiased device. This work was conducted as part of a scientific collaboration between the RoBioSS research team, CAIPS and SENSIX compagny.
4

Far-Field Noise From a Rotor in a Wind Tunnel

Unknown Date (has links)
This project is intended to demonstrate the current state of knowledge in the prediction of the tonal and broadband noise radiation from a Sevik rotor. The rotor measurements were made at the Virginia Tech Stability Wind Tunnel. Details of the rotor noise and flow measurements were presented by Wisda et al(2014) and Murray et al(2015) respectively. This study presents predictions based on an approach detailed by Glegg et al(2015) for the broadband noise generated by a rotor in an inhomogeneous flow, and compares them to measured noise radiated from the rotor at prescribed observer locations. Discrepancies between the measurements and predictions led to comprehensive study of the flow in the wind tunnel and the discovery of a vortex upstream of the rotor at low advance ratios. The study presents results of RANS simulations. The static pressure and velocity profile in the domain near the rotor's tip gap region were compared to measurements obtained from a pressure port array and a PIV visualization of the rotor in the wind tunnel. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2015. / FAU Electronic Theses and Dissertations Collection
5

Étude expérimentale des interactions aube-abradable à très grandes vitesses : influence du matériau et de sa microstructure / Experimental study of high speed blade-abradable interactions : influence of the material and its microstructure

Vincent, Julien 16 March 2015 (has links)
Le rendement des turboréacteurs peut être amélioré en minimisant le jeu aube-carter, réduisant ainsi les pertes aérodynamiques. Ces jeux réduits occasionnent des risques de contact entre les aubes en rotation à grande vitesse et le carter moteur. Des matériaux sacrificiels, appelés matériaux abradables, sont alors déposés sur le carter pour limiter les endommagements induits par ces contact. Ces interactions font intervenir un grand nombre de mécanismes d’endommagement bénéfiques ou néfastes au bon fonctionnement du joint abradable et à la fiabilité du moteur. L’objectif de cette thèse est alors de comprendre, prédire et quantifier les différents endommagements et les efforts d’interaction associés pour des matériaux abradables obtenus à l’aide de paramètres procédés différents. Un dynamomètre triaxial a été développé afin de reproduire l’interaction locale entre l’extrémité de l’aube et le matériau abradable à très grande vitesse (50 – 300 m/s) lors de phases transitoires. La mesure d’efforts d’interaction lors de contacts de très courte durée (300 µs – 1 ms) nécessite une bande passante importante. Une méthode de correction basée sur l’analyse modale expérimentale a été mise en œuvre afin d’étendre la bande passante naturelle du dynamomètre et d’atténuer les couplages entre les différentes voies de mesure. Les mécanismes d’endommagements des abradables ont été étudiés à partir d’analyses post-mortem et corrélés aux efforts et vitesse d’interactions / The turbofan efficiency can be improved by minimizing the blade-casing gap, thus reducing the aerodynamic loss. The reduced gap conduces to contact risk between the high-speed rotating blades and the engine case. Sacrificial materials, called abradable materials, are deposited on the casing to limit the damage caused by these contacts. These interactions involve a lot of damage mechanisms, which can be adverse or beneficial to the proper performance of the abradable seal and to the reliability of the engine. The aim of this thesis is to understand, predict and quantify the different damages and the interaction forces associated for abradable materials obtained with different process parameters. A triaxial dynamometer was developed to reproduce the local high-speed interactions (50 – 300 m/s) between the blade tip and the abradable material during transitional phases. The interaction forces measurement during short-lived contacts (300 µs – 1 ms) requires a large bandwidth. A correction method based on experimental modal analysis was implemented to extend the natural bandwidth of the device and attenuate the crosstalk between the different measurement channels. The damage mechanisms of abradable materials were studied by post-mortem analysis and correlated to the interaction forces and velocity
6

Měření odklonu kola během jízdy / Measurement of camber during driving

Vojtěšek, Aleš January 2015 (has links)
The subject of this master's thesis is design measurement and measure change wheel camber angle during driving. For this task were used parts from Corrsys-Datron and remaining elements needed to be manufactured. With complete system measurements were done and outputs data were displayed by Matlab and evaluated. Based on data evaluation is possible exactly determine relative position of the wheel to the road surface and to the body of vehicle.
7

Trakční pohony s asynchronním motorem / Traction Drives with Asynchronous Motors

Běloušek, Josef January 2013 (has links)
The first part of this work is devoted to the design of a traction asynchronous motor. The second part focuses on the developed method of the equivalent circuit parameters identification of the asynchronous motor in the form of -network. It is explained here that the equivalent circuit in the shape of a -network, alternatively of an inverse 'I-network, is exactly equivalent and fully-fledged to a T-network, although one of two stray inductances is formally missing. Furthermore, the relationships for the conversions of the T-network parameters to the -network parameters and back, and of the T-network to the inverse 'I-network and back are found. The third part deals with the calculation of the torque and the current characteristics of the asynchronous motor. A sensitive analysis of the torque characteristic is carried out on the individual parameters of the equivalent circuit of the asynchronous motor in the form of a -network and a method of the measurement by means of a flywheel is used for the torque characteristic measurement of the asynchronous motor. The fourth part focuses on the verification of the identified -network parameters in the Matlab-model of the traction drive.

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