Dissertations / Theses on the topic 'Angular rate'
To see the other types of publications on this topic, follow the link: Angular rate.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Angular rate.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Watson, Vincent C. "Angular rate estimation by multiplicative Kalman filtering techniques." Thesis, Monterey, Calif. : Naval Postgraduate School, 2003. http://handle.dtic.mil/100.2/ADA420668.
Full textAbstract:
Thesis (M.S. in Astronautical Engineering)--Naval Postgraduate School, December 2003."December 2003". Thesis advisor(s): Cristi, Roberto ; Agrawal, Brij. Includes bibliographical references (p. 53). Also available online.
2
John, James Daniel, and james d. john@gmail com. "An Adaptively Controlled MEMS Triaxial Angular Rate Sensor." RMIT University. Electrical and Computer Engineering, 2006. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20070112.162019.
Full textAbstract:
Prohibitive cost and large size of conventional angular rate sensors have limited their use to large scale aeronautical applications. However, the emergence of MEMS technology in the last two decades has enabled angular rate sensors to be fabricated that are orders of magnitude smaller in size and in cost. The reduction in size and cost has subsequently encouraged new applications to emerge, but the accuracy and resolution of MEMS angular rate sensors will have to be greatly improved before they can be successfully utilised for such high end applications as inertial navigation. MEMS angular rate sensors consist of a vibratory structure with two main resonant modes and high Q factors. By means of an external excitation, the device is driven into a constant amplitude sinusoidal vibration in the first mode, normally at resonance. When the device is subject to an angular rate input, Coriolis acceleration causes a transfer of energy between the two modes and results in a sinusoidal motion in the second mode, whose amplitude is a measure of the input angular rate. Ideally the only coupling between the two modes is the Coriolis acceleration, however fabrication imperfections always result in some cross stiffness and cross damping effects between the two modes. Much of the previous research work has focussed on improving the physical structure through advanced fabrication techniques and structural design; however attention has been directed in recent years to the use of control strategies to compensate for these structural imperfections. The performance of the MEMS angular rate sensors is also hindered by the effects of time varying parameter values as well as noise sources such as thermal-mechanical noise and sensing circuitry noise. In this thesis, MEMS angular rate sensing literature is first reviewed to show the evolu- tion of MEMS angular rate sensing from the basic principles of open-loop operation to the use of complex control strategies designed to compensate for any fabrication imperfections and time-varying effects. Building on existing knowledge, a novel adaptively controlled MEMS triaxial angular rate sensor that uses a single vibrating mass is then presented. Ability to sense all three components of the angular rate vector with a single vibrating mass has advantages such as less energy usage, smaller wafer footprint, avoidance of any mechanical interference between multiple resonating masses and removal of the need for precise alignment of three separate devices. The adaptive controller makes real-time estimates of the triaxial angular rates as well as the device cross stiffness and cross damping terms. These estimates are then used to com- pensate for their effects on the vibrating mass, resulting in the mass being controlled to follow a predefined reference model trajectory. The estimates are updated using the error between the reference model trajectory and the mass's real trajectory. The reference model trajectory is designed to provide excitation to the system that is sufficiently rich to enable all parameter estimates to converge to their true values. Avenues for controller simplification and optimisation are investigated through system simulations. The triaxial controller is analysed for stability, averaged convergence rate and resolution. The convergence rate analysis is further utilised to determine the ideal adaptation gains for the system that minimises the unwanted oscillatory behaviour of the parameter estimates. A physical structure for the triaxial device along with the sensing and actuation means is synthesised. The device is realisable using MEMS fabrication techniques due to its planar nature and the use of conventional MEMS sensing and actuation elements. Independent actuation and sensing is achieved using a novel checkerboard electrode arrangement. The physical structure is refined using a design automation process which utilises finite element analysis (FEA) and design optimisation tools that adjust the design variables until suitable design requirements are met. Finally, processing steps are outlined for the fabrication of the device using a modified, commercially available polysilicon MEMS process.
3
Osborn, Christopher Scott 1979. "Gyroscope angular rate processing across asynchronous clock domains." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/87278.
Full textAbstract:
Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2002.Includes bibliographical references (p. 85-86).
by Christopher Scott Osborn.
M.Eng.
4
Patil, Nishad. "Design And Analysis Of MEMS Angular Rate Sensors." Thesis, Indian Institute of Science, 2006. http://etd.iisc.ac.in/handle/2005/439.
Full textAbstract:
Design and analysis of polysilicon and single crystal silicon gyroscopes have been carried out. Variations in suspension design have been explored. Designs that utilize in-plane and out-of-plane sensing are studied.
Damping plays an important role in determining the sense response. Reduction in damping directly affects sensor performance. The various damping mechanisms that are prevalent in gyroscopes are studied. Perforations on the proof mass are observed to significantly reduce the damping in the device when operated in air. The effects of perforation geometry and density have been analyzed. The analysis results show that there is a two orders of magnitude reduction in damping of thick gyroscope structures with optimized perforation design.
Equivalent circuit lumped parameter models have been developed to analyze gyroscope performance. The simulation results of these models have been compared with results obtained from SABER, a MEMS specific system level design tool from Coventorware. The lumped parameter models are observed to produce faster simulation results with an accuracy comparable to that of Coventorware
Three gyroscopes specific to the PolyMUMPS fabrication process have been designed and their performance analyzed. Two of the designs sense motion out-of-plane and the other senses motion in-plane. Results of the simulation show that for a given damping, the gyro design with in-plane modes gives a resolution of 4º/s. The out-of-plane gyroscopes have two variations in suspension. The hammock suspension resolves a rate of 25º/s in a 200 Hz bandwidth while the design with folded beam suspension resolves a rate of 2º/s in a 12 Hz bandwidth. A single crystal silicon in-plane gyroscope has been designed with vertical electrodes to sense Coriolis motion. This design gives an order of magnitude higher
Capacitance change for a given rotation in comparison to conventional comb-finger design.
The effects of process induced residual stress on the characteristic frequencies of the polysilicon gyroscopes are also studied. The in-plane gyroscope is found to be robust to stress variations. Analysis results indicate that the tuning fork gyroscope with the hammock suspension is the most susceptible to compressive residual stress, with a significant drop in sensitivity at high stress values.
5
Patil, Nishad. "Design And Analysis Of MEMS Angular Rate Sensors." Thesis, Indian Institute of Science, 2006. http://hdl.handle.net/2005/291.
Full textAbstract:
Design and analysis of polysilicon and single crystal silicon gyroscopes have been carried out. Variations in suspension design have been explored. Designs that utilize in-plane and out-of-plane sensing are studied.
Damping plays an important role in determining the sense response. Reduction in damping directly affects sensor performance. The various damping mechanisms that are prevalent in gyroscopes are studied.
Perforations on the proof mass are observed to significantly reduce the damping in the device when operated in air. The effects of perforation geometry and density have been analyzed. The analysis results show that there is a two orders of magnitude reduction in damping of thick gyroscope structures with optimized perforation design.
Equivalent circuit lumped parameter models have been developed to analyze gyroscope performance. The simulation results of these models have been compared with results obtained from SABER, a MEMS specific system level design tool from Coventor-ware. The lumped parameter models are observed to produce faster simulation results with an accuracy comparable to that of Coventorware
Three gyroscopes specific to the PolyMUMPS fabrication process have been designed and their performance analyzed. Two of the designs sense motion out-of-plane and the other senses motion in-plane. Results of the simulation show that for a given damping, the gyro design with in-plane modes gives a resolution of 4◦/s. The out-of-plane gyroscopes have two variations in suspension. The hammock suspension resolves a rate of 25◦/s in a 200 Hz bandwidth while the design with folded beam suspension resolves a rate of 2◦/s in a 12 Hz bandwidth. A single crystal silicon in-plane gyroscope has been designed with vertical electrodes to sense Coriolis motion. This design gives an order of magnitude higher
capacitance change for a given rotation in comparison to conventional comb-finger design.
The effects of process induced residual stress on the characteristic frequencies of the polysilicon gyroscopes are also studied. The in-plane gyroscope is found to be robust to stress variations. Analysis results indicate that the tuning fork gyroscope with the hammock suspension is the most susceptible to compressive residual stress, with a significant drop in sensitivity at high stress values.
6
Patil, Nishad. "Design And Analysis Of MEMS Angular Rate Sensors." Thesis, Indian Institute of Science, 2006. https://etd.iisc.ac.in/handle/2005/291.
Full textAbstract:
Design and analysis of polysilicon and single crystal silicon gyroscopes have been carried out. Variations in suspension design have been explored. Designs that utilize in-plane and out-of-plane sensing are studied.
Damping plays an important role in determining the sense response. Reduction in damping directly affects sensor performance. The various damping mechanisms that are prevalent in gyroscopes are studied.
Perforations on the proof mass are observed to significantly reduce the damping in the device when operated in air. The effects of perforation geometry and density have been analyzed. The analysis results show that there is a two orders of magnitude reduction in damping of thick gyroscope structures with optimized perforation design.
Equivalent circuit lumped parameter models have been developed to analyze gyroscope performance. The simulation results of these models have been compared with results obtained from SABER, a MEMS specific system level design tool from Coventor-ware. The lumped parameter models are observed to produce faster simulation results with an accuracy comparable to that of Coventorware
Three gyroscopes specific to the PolyMUMPS fabrication process have been designed and their performance analyzed. Two of the designs sense motion out-of-plane and the other senses motion in-plane. Results of the simulation show that for a given damping, the gyro design with in-plane modes gives a resolution of 4◦/s. The out-of-plane gyroscopes have two variations in suspension. The hammock suspension resolves a rate of 25◦/s in a 200 Hz bandwidth while the design with folded beam suspension resolves a rate of 2◦/s in a 12 Hz bandwidth. A single crystal silicon in-plane gyroscope has been designed with vertical electrodes to sense Coriolis motion. This design gives an order of magnitude higher
capacitance change for a given rotation in comparison to conventional comb-finger design.
The effects of process induced residual stress on the characteristic frequencies of the polysilicon gyroscopes are also studied. The in-plane gyroscope is found to be robust to stress variations. Analysis results indicate that the tuning fork gyroscope with the hammock suspension is the most susceptible to compressive residual stress, with a significant drop in sensitivity at high stress values.
7
Palermo, William J. "Angular rate estimation for multi-body spacecraft attitude control." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2001. http://handle.dtic.mil/100.2/ADA392077.
Full textAbstract:
Thesis (M.S. in Astronautical Engineering and Aeronautical and Astronautical Engineer) Naval Postgraduate School, June 2001.Thesis advisor(s): Agrawal, Brij N. "June 2001." Includes bibliographical references (p. 109-110). Also available in print.
8
Wilson, Michael J. "Nonlinear projectile attitude estimation with magnetometers and angular rate sensors." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 37 p, 2006. http://proquest.umi.com/pqdweb?did=1163250861&sid=2&Fmt=2&clientId=8331&RQT=309&VName=PQD.
Full text
9
Nikpour, Behrouz. "A micromachined silicon vibrating-beam angular rate sensor : a design and implementation study." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0005/NQ40318.pdf.
Full text
10
Ghoussayni, Salim. "Application of angular rate gyroscopes as sensors in electrical orthoses for foot drop correction." Thesis, University of Surrey, 2004. http://epubs.surrey.ac.uk/673/.
Full text
11
Saliaris, Ioannis R. "Real-Time data acquisition and processing of the Magnetic, Angular Rate and Gravity (MARG) sensor /." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2004. http://library.nps.navy.mil/uhtbin/hyperion/04Jun%5FSaliaris.pdf.
Full textAbstract:
Thesis (M.S. in Electrical Engineering and M.S. in Systems Engineering)--Naval Postgraduate School, June 2004.Thesis advisor(s): Xiaoping Yun. Includes bibliographical references (p. 59-60). Also available online.
12
Mulders, Gijs D., Ilaria Pascucci, Carlo F. Manara, Leonardo Testi, Gregory J. Herczeg, Thomas Henning, Subhanjoy Mohanty, and Giuseppe Lodato. "Constraints from Dust Mass and Mass Accretion Rate Measurements on Angular Momentum Transport in Protoplanetary Disks." IOP PUBLISHING LTD, 2017. http://hdl.handle.net/10150/626047.
Full textAbstract:
In this paper, we investigate the relation between disk mass and mass accretion rate to constrain the mechanism of angular momentum transport in protoplanetary disks. We find a correlation between dust disk mass and mass accretion rate in Chamaeleon I with a slope that is close to linear, similar to the one recently identified in Lupus. We investigate the effect of stellar mass and find that the intrinsic scatter around the best-fit M-dust-M star and M-acc-M star relations is uncorrelated. We simulate synthetic observations of an ensemble of evolving disks using a Monte Carlo approach and find that disks with a constant alpha viscosity can fit the observed relations between dust mass, mass accretion rate, and stellar mass but overpredict the strength of the correlation between disk mass and mass accretion rate when using standard initial conditions. We find two possible solutions. In the first one, the observed scatter in M-dust and M-acc is not primordial, but arises from additional physical processes or uncertainties in estimating the disk gas mass. Most likely grain growth and radial drift affect the observable dust mass, while variability on large timescales affects the mass accretion rates. In the second scenario, the observed scatter is primordial, but disks have not evolved substantially at the age of Lupus and Chamaeleon I owing to a low viscosity or a large initial disk radius. More accurate estimates of the disk mass and gas disk sizes in a large sample of protoplanetary disks, through either direct observations of the gas or spatially resolved multiwavelength observations of the dust with ALMA, are needed to discriminate between both scenarios or to constrain alternative angular momentum transport mechanisms such as MHD disk winds.
13
Moser, David. "Application of angular rate gyroscopes for the analysis of swing phase control in transfemoral amputee gait." Thesis, University of Surrey, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.493049.
Full textAbstract:
Microprocessor controlled knee prostheses require expertise and programming skill to setup the swing phase damping performance for different walking speeds. There is a lack of suitable sensing and analysis means to quantify control performance and assist the setup process thereby hindering the development of self-optimizing prostheses. In this project the application of miniature gyroscopes was explored as a means to quantify the swing phase control of transfemoral (TF) amputees. The stride-to-stride repeatability of locomotion and the timing and coordination of knee segment motions were investigated as potential indicators of prosthetic swing control performance.
14
Maurer, Michael [Verfasser], and Yiannos [Akademischer Betreuer] Manoli. "System dimensioning, digital postprocessing, and nonideality control for electromechanical Delta-Sigma-Modulator based Angular Rate Detection." Freiburg : Universität, 2018. http://d-nb.info/1167159624/34.
Full text
15
Marinho, Diego de Freitas. "Calibração de um sistema de determinação de atitude com múltiplos sensores MARG (Magnetic, Angular Rate and Gravity)." Universidade Estadual de Londrina. Centro de Tecnologia e Urbanismo. Programa de Pós-Graduação em Engenharia Elétrica, 2017. http://www.bibliotecadigital.uel.br/document/?code=vtls000215309.
Full textAbstract:
O principal instrumento utilizado neste trabalho foi a Experiência MEMS (e- MEMS), que consiste de quatro conjunto de sensores organizados em uma estrutura tetraédrica, onde cada conjunto é composto por um acelerômetro de três eixos, um magnetômetro de três eixos, um girômetro de um eixo e um sensor de temperatura (o conjunto de acelerômetros, magnetômetros e girômetros será denominado de sensores MARG). Devido a distribuição dos conjuntos de sensores em uma estrutura tetraédrica, podem ser definidos cinco sistemas de coordenadas, quatro deles nos conjuntos de sensores e um na base da e-MEMS. Por causa dos erros inerentes aos sensores MEMS, as medidas dos sensores precisam ser corrigidas através de técnicas de calibração. Os métodos de calibração utilizados foram: mínimos quadrados com entradas controladas (LMS EC) e o da mínima variância sem entradas controladas (MV SEC). Matrizes de transformação serão utilizadas para transformar as medidas dos sensores do sistema de coordenadas dos conjuntos de sensores para o sistema de coordenadas da base. A atitude da e- MEMS foi determinada por meio de dois métodos: TRIAD e filtro de Kalman. Os algoritmos de calibração dos sensores e os algoritmos de determinação e estimação de atitude foram desenvolvidos na ferramenta matemática MATLAB/Simulink. Para realizar os ensaios de calibração e de atitude utilizou-se os seguintes sistemas: uma plataforma de rotação tridimensional; um sistema de determinação de atitude (AHRS) da empresa Advanced Navigation e a e-MEMS. Os resultados adquiridos da e-MEMS obtiveram pequenos erros quando comparados com os dados do AHRS, assim os métodos de calibração dos sensores e os algoritmos de determinação de atitude foram validados.The main instrument used in this work was the MEMS Experiment (e-MEMS), which consists of four set of sensors arranged in a tetrahedral structure, where each set consists of one three-axis accelerometer, one three-axis magnetometer, one-axis gyrometer, and a temperature sensor (the set of accelerometers, magnetometers and gyrometers will be called the MARG sensors). Due to the distribution of the sensor sets in a tetrahedral structure, _ve coordinate systems are de_ned, four of them in the sensor sets and one in the base of the e-MEMS. Because of the errors inherent in MEMS sensors, sensor measurements need to be corrected through calibration techniques. The calibration methods used were: Least squares with controlled inputs (LMS EC) and the least variance without controlled inputs (MV SEC). Transform matrices will be used to transform the sensor measurements from the sensor set coordinate system to the base coordinate system. The e-MEMS attitude was determined by two methods: TRIAD and Kalman _lter. The algorithms of calibration of the sensors and the algorithms of attitude determination and estimation were developed in mathematical tool MATLAB / Simulink. To perform the calibration and attitude tests the following systems were used: a three-dimensional rotation platform; an Attitude Determination System (AHRS) from the company Advanced Navigation and the e-MEMS. The results obtained from e-MEMS presented small errors when compared with data from AHRS, so the methods of calibration of the sensors and attitude determination algorithms were validated.
16
Sha, Zhanxin. "Kinetic and Kinematic Properties of D-I Male Sprinters." Digital Commons @ East Tennessee State University, 2014. https://dc.etsu.edu/etd/2468.
Full textAbstract:
The purpose of the study was to explore and determine kinetic and kinematic variables that related to D-I male sprinters maximal running velocity performance. The current study was separated into 3 individual chapters: 1.) Kinematic analysis magnitude of acceleration for braking and propulsion phases during foot contact phase at maximal speed sprinting; 2.) Using kinetic isometric mid-thigh pull variables to predict D-I male sprinters’ 60m performance; 3.) Relationship of whole and lower body angular momentum cancellation during terminal swing phase to sprint performance.
Methods: for sprint measurement all the athletes were participated 2 trials of 100% effort running through 60 meters. The sprint time was measured by an electronic timing gate system. The electronic timing gate system was placed at every 10 meter intervals from the start line for 60 m. Six cameras were placed between 50 m and 60 m for kinematic data collection and analysis. Volume captured by the cameras is 7.5 m long, 1.2 m wide, and 1.95 m high. Reflective markers were attached on the body landmarks based on Vicon Nexus full body plugin model. The strength assessments were performed in a customized power rack, and kinetic values were collected via a dual force plate setup (2 separate 91 cm x 45.5 cm force plates, Roughdeck HP, Rice Lake, WI). The position for each isometric pull was established before each trial using goniometry, with each bar height corresponding to a 125±5º knee angle and a near-vertical trunk position.
Results: current study partially support previous assumption that fast sprinters can minimize braking phase during foot contact phase when they are running maximal velocity. However, those minimizing effects did not impact maximal running velocity performance. Second, the study showed that fast sprinters can produce greater force during a short period of time than slower sprinters. Moreover, a certain trend of statistical significance was observed from the third study that angular momentum cancellation between lower bodies at frontal plane may be related to maximal running velocity performance.
Discussion: the current study confirmed that fast sprinters can produce greater force in a short period time. However, the current study did not show statistical significance of angular momenta cancellation and sprint performance. Only a level of trend was observed. Thus, further study should examine sprinters with different training background, especially elite level sprinters is definitely needed.
17
Huculak, Robert D. "Evaluating spatial orientation and position of an ATD head using accelerometers and angular rate sensors in dynamic impact testing." Thesis, Wichita State University, 2011. http://hdl.handle.net/10057/5045.
Full textAbstract:
Using three linear accelerometers and three angular rate sensors arranged to measure
local acceleration in the X, Y, and Z directions and angular velocity about those axes, it is
possible to calculate spatial orientation and position in a global coordinate system. The intent of
this thesis is to use this calculation to provide the head trajectory of an Anthropomorphic Test
Device (ATD) to supplement or replace photometric analysis. This thesis examines the various
parameters of the calculations of the spatial orientation and position to determine the most
accurate and efficient method. Using the local angular velocity as an input, this method
determines spatial orientation as a function of a unit quaternion by numerically solving a system
of ordinary differential equation.
The parameters of the numerical integration examined are the numerical integration
methods, time step, and order of rotation. These functions are examined through simulation data
generated by various MADYMO models. The MADYMO three-dimensional multi-body
simulations output the linear accelerations and angular velocity of selected bodies in simulations
similar to the data provided from accelerometers and angular rate sensors during dynamic impact
testing. Simulation data is useful in the examination and validation of the different parameters
used in the method due to the lack of noise and gravitational effects incurred during physical
dynamic impact testing.
The method is evaluated for dynamic impact testing through a comparison between the
calculated spatial orientation and position using the algorithm and photometric analysis as well
as physical limitations in the test setup, i.e. rigid bulkhead. The method is demonstrated to be
successfully implemented into the NIAR Crash Dynamics Laboratory at Wichita State
University.Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Mechanical Engineering.
18
Aditya, Pradyumna. "Leaky Wave Antenna." Wright State University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=wright1473414587856344.
Full text
19
Magnis, Lionel. "Estimation de vitesse de rotation par mesures de direction." Thesis, Paris, ENMP, 2015. http://www.theses.fr/2015ENMP0039/document.
Full textAbstract:
Cette thèse étudie l’estimation de vitesse de rotation d’un corps rigide à partir de mesures de directions (par exemple champ magnétique, direction du soleil) embarquées. L’objectif est de remplacer les gyromètres qui sont chers comparés aux autres capteurs inertiels et sujets à des saturations et à des dysfonctionnements. Dans une première partie de la thèse, on traite les cas spécifiques d’une rotation à axe fixe ou légèrement variable. Dans une seconde partie, on traite le cas d’une rotation quelconque par un observateur asymptotique non-linéaire. On construit l’observateur à partir de mesures de deux vecteurs de référence non colinéaires, ou bien d’un seul vecteur. La connaissance des coordonnées inertielles des vecteurs de référence n’est pas nécessaire. On étend ensuite l’observateur pour estimer en plus le couple et les paramètres d’inertie. Les équations d’Euler jouent un rôle central dans les travaux présentés ici. Il apparaît que, du moins pour les illustrations considérées, les gyromètres peuvent être remplacés par un algorithme d’estimation basé sur des capteurs de direction qui sont bien moins chers et plus robustesThis thesis addresses the general question of estimating the angular rate of a rigid body from on-board direction sensors (e.g. magnetometers, Sun sensors). The objective is to replace rate gyros which are very expensive compared to direction sensors, prone to saturation during high rate rotations and subject to failure. In a first part of the thesis, we address the specific cases of single-axis and slightly perturbed axis rotations.In a second part, we address the general case by an asymptotic non-linear observer. We build the observer from two non-collinear vector measurements or from a single vector measurements. The knowledge of the inertial coordinates of the reference vectors is not necessary. We then extend the observer to further estimate unknown torques and inertia parameters. The Euler’s equations play a central role in all the works developed in this thesis. It appears that, at least for the illustrative cases considered, rate gyros could be replaced with an estimation algorithm employing direction sensors which are much cheaper,more rugged and more resilient sensors
20
Alper, Said Emre. "Mems Gyroscopes For Tactical-grade Inertial Measurement Applications." Phd thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12606483/index.pdf.
Full textAbstract:
This thesis reports the development of high-performance symmetric and decoupled micromachined gyroscopes for tactical-grade inertial measurement applications. The symmetric structure allows easy matching of the resonance frequencies of the drive and sense modes of the gyroscopes for achieving high angular rate sensitivitywhile the decoupled drive and sense modes minimizes mechanical cross-coupling for low-noise and stable operation. Three different and new symmetric and decoupled gyroscope structures with unique features are presented. These structures are fabricated in four different micromachining processes: nickel electroforming (NE), dissolved-wafer silicon micromachining (DWSM), silicon-on-insulator (SOI) micromachining, and silicon-on-glass (SOG) micromachining. The fabricated gyroscopes have capacitive gaps from 1.5µ
m to 5.5µ
m and structural layer thicknesses from 12µ
m to 100µ
m, yielding aspect ratios up to 20 depending on the fabrication process. The size of fabricated gyroscope chips varies from 1x1mm2 up to 4.2x4.6mm2. Fabricated gyroscopes are hybrid-connected to a designed capacitive interface circuit, fabricated in a standard 0.6µ
m CMOS process. They have resonance frequencies as small as 2kHz and as large as 40kHz
sense-mode resonance frequencies can be electrostatically tuned to the drive-mode frequency by DC voltages less than 16V. The quality factors reach to 500 at atmospheric pressure and exceed 10,000 for the silicon gyroscopes at vacuum. The parasitic capacitance of the gyroscopes on glass substrates is measured to be as small as 120fF. The gyroscope and interface assemblies are then combined with electronic control and feedback circuits constructed with off-the-shelf IC components to perform angular rate measurements. Measured angular rate sensitivities are in the range from 12µ
V/(deg/sec) to 180µ
V/(deg/sec), at atmospheric pressure. The SOI gyroscope demonstrates the best performance at atmospheric pressure, with noise equivalent rate (NER) of 0.025(deg/sec)/Hz1/2, whereas the remaining gyroscopes has an NER better than 0.1(deg/sec)/Hz1/2, limited by either the small sensor size or by small quality factors. Gyroscopes have scale-factor nonlinearities better than 1.1% with the best value of 0.06%, and their bias drifts are dominated by the phase errors in the demodulation electronics and are over 1deg/sec. The characterization of the SOI and SOG gyroscopes at below 50mTorr vacuum ambient yield angular rate sensitivities as high as 1.6mV/(deg/sec) and 0.9mV/(deg/sec), respectively. The NER values of these gyroscopes at vacuum are smaller than 50(deg/hr)/Hz1/2 and 36(deg/hr)/Hz1/2, respectively, being close to the tactical-grade application limits. Gyroscope structures are expected to provide a performance better than 10 deg/hr in a practical measurement bandwidth such as 50Hz, provided that capacitive gaps are minimized while preserving the aspect ratio, and the demodulation electronics are improved.
21
Pinto, Stephanie Santana. "Comparação das respostas cardiorrespiratórias, neuromusculares e cinemáticas de um exercício de hidroginástica executado em diferentes cadências com e sem equipamento." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2009. http://hdl.handle.net/10183/17694.
Full textAbstract:
O objetivo do presente estudo foi comparar as respostas cardiorrespiratórias, neuromusculares e cinemáticas durante o exercício de corrida estacionária com a flexão e extensão de cotovelo em diferentes cadências com e sem equipamento. A amostra desse estudo foi composta por 15 mulheres jovens que realizaram o exercício nas situações sem equipamento (SEM), com equipamento flutuante em ambos os membros (FLU-MSs/MIs) e com equipamento resistivo em ambos os membros (RES-MSs/MIs), nas cadências de 80 bpm, 100 bpm e no máximo esforço. Para as cadências submáximas o exercício foi realizado durante 4 min em cada situação e no máximo esforço o mesmo foi realizado durante 15 s. Utilizou-se ANOVA de 2 e 3 fatores, com post-hoc de Bonferroni (p < 0,05) (SPSS vs 15.0). Os resultados da frequência cardíaca e do consumo de oxigênio mostraram haver diferenças significativas entre as situações FLUMSs/ MIs e RES-MSs/MIs em comparação a SEM, com valores significativamente maiores para as situações de exercício com equipamento. Além disso, houve diferença entre as cadências de 80 e 100 bpm, com valores maiores e significativos para a cadência de 100 bpm. Para as variáveis de amplitude de movimento houve diferenças entre as cadências, com valores maiores de amplitude de movimento do quadril e joelho, conforme o incremento da cadência. Todavia, para a amplitude de movimento do cotovelo com o incremento da cadência houve uma diminuição da amplitude de movimento. Em relação a velocidade angular média de movimento do cotovelo, quadril e joelho houve diferenças significativas entre as cadências, com valores maiores para o máximo esforço. A velocidade angular média do quadril foi menor nas situações FLUMSs/ MIs e RES-MSs/MIs em comparação a SEM. Para as variáveis neuromusculares, não houve diferenças entre as situações, com exceção do percentual da contração isométrica voluntária máxima (%CVM) do tríceps braquial, que foi maior na situação FLU-MSs/MIs. Entre as diferentes cadências submáximas não houve diferenças para todos os músculos analisados, todavia entre essas e o máximo esforço houve diferenças, com maiores %CVM para o máximo esforço. O %CVM do bíceps femoral foi o único que demonstrou diferenças entre todas as cadências testadas nesse estudo. Entre as fases de movimento não houve diferença, com exceção do %CVM do reto femoral, o qual foi maior na fase de extensão. Em suma, o exercício de corrida estacionária com a flexão e extensão de cotovelo apresentou maiores respostas cardiorrespiratórias com o uso de equipamento (flutuante e resistivo) e também com o aumento da cadência de execução. Todavia, as respostas neuromusculares não diferiram entre as cadências submáximas, mas essas foram significativamente maiores no máximo esforço.The purpose of the present study was to compare the cardiorespiratory, neuromuscular and kinematic responses during the stationary running with the elbow flexion/extension in different cadences with and without equipment. The sample was consisted of fifteen young women that performed the exercise without equipment (NO-E), with floating equipment in upper and lower limbs (FLO-LLs/ULs) and with resistive equipment in upper and lower limbs (RES-LLs/ULs) at three cadences (80 bpm, 100 bpm and maximal effort). For submaximal cadences the exercise was performed during 4 min and during 15 s at maximal effort in each situation. The results were analyzed using repeated measures ANOVA (factors: cadence, situation, phase of movement) with the Bonferroni correction for post-hoc comparisons (p < 0,05) (SPSS vs 15.0). The heart rate and oxygen uptake showed significant differences between FLO-LLs/ULs and RES-LLs/ULs compared with NO-E and higher values of these variables was found in the situations with equipment. In addition, the results for cardirespiratory responses demonstrated significant difference between submaximal cadences (80 and 100 bpm) with higher values of heart rate and oxygen uptake at 100 bpm. For the range of motion significant differences between cadences was showed with higher values of this variable for hip and knee according to the increment of the cadence. However, the range of motion for elbow decreased with the increment of the cadence. The angular velocity for elbow, hip and knee presented significant differences between cadences with higher values at maximal effort. Besides, the angular velocity for hip was minor in the situations FLU-LLs/Uls and RES-LLs/ULs compared with NO-E. For neuromucular responses no significant differences were showed between situations, except the percentage of maximal voluntary contraction (%MVC) for triceps brachii that was major in FLO-LLs/ULs. Between the different submaximal cadences no significant differences was found for all muscles analyzed, however, between these submaximal cadences and maximal effort were found significant differences with higher values of the %MVC at maximal effort. The unique %MVC that demonstrated significant differences between all cadences analyzed in this study was for biceps femoris. Between the phases of movement (flexion and extension) no significant difference was showed for all muscles investigated, except for the %MVC for rectus femoris that was higher in extension phase. In conclusion, the stationary running with the elbow flexion/extension presented higher cardiorespiratory responses with equipment (floating and resistive) and also with the enhance at the cadence of execution. Nevertheless, neuromuscular responses showed no significant difference between submaximal cadences, but these responses were significantly higher at maximal effort.
22
Cookson, Jeremy L. "A method for testing the dynamic accuracy of Microelectro-Mechanical Systems (MEMS) Magnetic, Angular Rate, and Gravity (MARG) sensors for Inertial Navigation Systems (INS) and human motion tracking applications." Thesis, Monterey, California : Naval Postgraduate School, 2010. http://edocs.nps.edu/npspubs/scholarly/theses/2010/Jun/10Jun%5FCookson.pdf.
Full textAbstract:
Thesis (M.S. in Electrical Engineering)--Naval Postgraduate School, June 2010.Thesis Advisor(s): Yun, Xiaoping ; Second Reader: Romano, Marcello. "June 2010." Description based on title screen as viewed on July 14, 2010. Author(s) subject terms: micro-electro-mechanical systems, MEMS, magnetic, angular rate, gravity sensor, MARG sensors, inertial navigation system, INS, inertial test, MicroStrain, 3DM-GX1, 3DMGX3, CompactRIO, MATLAB GUI, dynamic accuracy test. Includes bibliographical references (p. 187-189). Also available in print.
23
Alberton, Cristine Lima. "Respostas cardiorrespiratórias e neuromusculares da corrida estacionária em diferentes cadências nos meios aquático e terrestre." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2007. http://hdl.handle.net/10183/11315.
Full textAbstract:
O objetivo do presente estudo foi analisar as respostas cardiorrespiratórias, cinemáticas e neuromusculares de mulheres jovens realizando o exercício de corrida estacionária em diferentes cadências nos meios aquático e terrestre. Doze mulheres jovens, experientes na prática de hidroginástica, foram amostras voluntárias do estudo. Cada uma participou de duas sessões experimentais: 1) coleta dos dados de caracterização da amostra e realização de um teste de esforço máximo; 2) coleta das variáveis cardiorrespiratórias (freqüência cardíaca (FC), consumo de oxigênio (VO2), percentual da FC máxima (%FCmáx) e percentual do VO2 máximo (%VO2máx)), cinemáticas (velocidade angular média (VAMQ) e de pico do quadril (VAPQ)) e neuromusculares (amplitude do sinal eletromiográfico (EMG) dos músculos vasto lateral (VL), bíceps femoral (BF), reto femoral (RF) e semitendinoso (ST)). Para a coleta de tais variáveis, dois protocolos de testes foram realizados, um no meio terrestre e outro no meio aquático, com um intervalo de duas horas entre eles. Para cada um dos meios, o exercício de corrida estacionária foi realizado durante 4 min em 3 cadências submáximas (60, 80 e 100 bpm) e durante 15 s no máximo esforço, com um intervalo de 5 min entre cada situação. Utilizamos análise de variância com bloqueamento, considerando o efeito do sujeito como mais uma fonte de variação para a análise estatística, com os dados processados nos programas SPSS versão 13.0 e R-project. Como resultados, as variáveis VAMQ e VAPQ foram significativamente mais elevadas quando o exercício foi executado no meio terrestre, e maiores quanto maior a cadência de execução, sugerindo um padrão cinemático distinto entre os meios. Da mesma forma, as respostas cardiorrespiratórias foram maiores para o exercício no meio terrestre e aumentaram significativamente com o aumento da cadência de execução. Já as respostas neuromusculares não apresentaram um comportamento semelhante, visto que o sinal EMG dos músculos VL, BF, RF e ST não aumentou significativamente com o incremento da cadência de execução, exceto das cadências submáximas para o máximo esforço. Na comparação entre os meios, o meio terrestre apresentou respostas significativamente maiores para o sinal EMG de todos os músculos nas cadências submáximas, exceto para o músculo ST que apresentou respostas semelhantes. Entretanto, no máximo esforço todos os grupos musculares analisados apresentaram respostas similares entre os meios. Em suma, a realização do exercício de corrida estacionária no meio aquático em cadências de execução submáximas apresenta respostas cardiorrespiratórias e neuromusculares menores do que o mesmo executado no meio terrestre, para as cadências fixas do presente estudo. Todavia, em intensidades máximas, a amplitude do sinal EMG pode apresentar padrões de ativação muscular semelhante entre os meios.The aim of the present study was to analyze the cardiorespiratory, kinematic and neuromuscular response of young women performing stationary running exercise at different cadences in aquatic and terrestrial environments. The study sample consisted of twelve young women, experienced in hydrogymnastics. Each one took part in two experimental sessions: 1) collection of sample characterization data and the performance of a maximum effort test; 2) collection of the cardiorespiratory (heart rate, (HR), oxygen uptake (VO2), percentage of maximum HR (%HRmax) and percentage of maximum VO2 (%VO2max)), kinematic (mean hip angular velocity (MHAV) and peak hip angular velocity (PHAV)), and neuromusuclar variables (electromyographic signal amplitude (EMG) of the vastus lateralis (VL), biceps femoris (BF), rectus femoris (RF) and semitendinosus (ST) muscles). In order to collect these variables, two test protocols were carried out, one land-based and the other water-based, with a two-hour interval between them. The stationary running exercise was performed in each of these environments during 4 min at 3 submaximal cadences (60, 80, and 100 bpm) and during 15 s at maximum effort, with a 5 min-interval between each situation. We used blocked variance analysis, in which the effect of the subject was considered an additional source of variation for the statistical analysis. The data was processed using the SPSS (version 13.0) and R-project programs. The findings showed that the MHAV and PHAV were significantly higher when the exercise was performed on land, and higher the greater the cadence of execution, suggesting distinct kinematic patterns for the two environments. Similarly, the cardiorespiratory responses were higher with the land-based exercise and increased significantly with increased cadence. The neuromuscular responses, however, showed no such behavior, with the EMG signal from the VL, BF, RF and ST muscles showing no significant increase with greater cadence of execution, except from the sub-maximum cadences to the maximum effort. When comparing the environments, the terrestrial environment presented significantly greater EMG signal responses from all the muscles at the sub-maximum cadences, except for the ST muscle which presented similar responses in both environments. However, at the maximum effort, all the analyzed muscle groups showed similar responses in both environments. In summary, at the cadences used in the present study, the performance of the stationary running exercise in an aquatic environment at a sub-maximum cadences presents lower cardiorespiratory and neuromuscular responses than the same exercise performed on land. Yet, at maximum intensities, the amplitude of the EMG signal may present similar muscular activation patterns in the two environments.
24
Gugel, Denis. "Ordnungsreduktion in der Mikrosystemtechnik." Doctoral thesis, Universitätsbibliothek Chemnitz, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-201001091.
Full textAbstract:
Die vorliegende Arbeit befasst sich mit der Methode der modalen Superposition als Ordnungsreduktionsverfahren in der Mikrosystemtechnik. Typische Anwendungsgebiete sind Inertialsensoren und dabei im Besonderen Drehratensensoren, für die die Simulation von zeitabhängigen Phänomenen von entscheidender Bedeutung ist.
Im Rahmen der Weiterentwicklung der Ordnungsreduktion nach der Methode der modalen Superposition ist es gelungen für typische lineare Kräfte eine auf analytischen Gleichungen basierende Beschreibung im reduzierten Raum zu finden. Für die Beschreibung von nichtlinearen Kräften ist im Rahmen dieser Arbeit ein Verfahren entwickelt worden, das es erlaubt, bestehende Modelle im Finite-Elemente-Raum in der modalen
Beschreibung zu nutzen.
In dieser Arbeit werden die theoretischen Grundlagen zur Berücksichtigung von Einflüssen der Aufbau- und Verbindungstechnik in ordnungsreduzierten Modellen dargestellt. Neben der Einkopplung äußerer Kräfte und der Veränderung der mechanischen Randbedingungen wird auch der Einfluss der Aufbau- und Verbindungstechnik auf die elektrostatischen Eigenschaften untersucht.
Die Parametrisierung des Verfahrens der modalen Superposition über Fit- und Interpolationsverfahren erlaubt es, parametrisierte ordnungsreduzierte Modelle für die zeitabhängige Systemsimulation zu generieren. Damit wird die Durchführung von Designoptimierung und die Berücksichtigung von Fertigungs- und Prozessschwankungen in ordnungsreduzierten Modellen auf Systemebene möglich.
25
Sahin, Emre. "High Performance Readout And Control Electronics For Mems Gyroscopes." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/2/12610386/index.pdf.
Full textAbstract:
This thesis reports the development of various high performance readout and control electronics for implementing angular rate sensing systems using MEMS gyroscopes developed at METU. First, three systems with open loop sensing mechanisms are implemented, where each system has a different drive-mode automatic gain controlled (AGC) self-oscillation loop approach, including (i) square wave driving signal with DC off-set named as OLS_SquD, (ii) sinusoidal driving signal with DC off-set named as OLS_SineD, and iii) off-resonance driving signal named as OLS_OffD. A forth system is also constructed with a closed loop sensing mechanism where the drive mode automatic gain controlled (AGC) self-oscillation loop approach with square wave driving signal with DC off-set named as CLS_SquD. Sense and drive mode electronics employ transimpedance and transresistance amplifiers as readout electronics, respectively. Each of the systems is implemented with commercial discrete components on a dedicated PCB. Then, the angular rate sensing systems are tested with SOG (Silicon-on-Glass) gyroscopes that are adjusted to have two different mechanical bandwidths, more specially 100 Hz and 30 Hz. Test results of all of these cases verify the high performance of the systems.
For the 100 Hz bandwidth, the OLS_SquD system shows a bias instability of 4.67 ˚
/hr, an angle random walk (ARW) 0.080 &
#730
/&
#8730
hr, and a scale factor of 22.6 mV/(&
#730
/sec). For the 30 Hz bandwidth, the OLS_SquD system shows a bias instability of 5.12 &
#730
/hr, an ARW better than 0.017 &
#730
/&
#8730
hr, and a scale factor of 49.8 mV/(&
#730
/sec). For the 100 Hz bandwidth, the OLS_SineD system shows a bias instability of 6.92 &
#730
/hr, an ARW of 0.049 &
#730
/&
#8730
hr, and a scale factor of 17.97 mV/(&
#730
/sec). For the 30 Hz bandwidth, the OLS_SineD system shows a bias instability of 4.51 &
#730
/hr, an ARW of 0.030 &
#730
/&
#8730
hr, and a scale factor of 43.24 mV/(&
#730
/sec). For the 100 Hz bandwidth, the OLS_OffD system shows a bias instability of 8.43 &
#730
/hr, an ARW of 0.086 &
#730
/&
#8730
hr, and a scale factor of 20.97 mV/(&
#730
/sec). For the 30 Hz bandwidth, the OLS_OffD system shows a bias instability of 5.72 &
#730
/hr, an ARW of 0.046 &
#730
/&
#8730
hr, and a scale factor of 47.26 mV/(&
#730
/sec). For the 100 Hz bandwidth, the CLS_SquD system shows a bias instability of 6.32 &
#730
/hr, an ARW of 0.055 &
#730
/&
#8730
hr, and a scale factor of 1.79 mV/(&
#730
/sec). For the 30 Hz bandwidth, the CLS_SquD system shows a bias instability of 5.42 &
#730
/hr, an ARW of 0.057 &
#730
/&
#8730
hr, and a scale factor of 1.98 mV/(&
#730
/sec). For the 100 Hz bandwidth, the R2 nonlinearities of the measured scale factors of all systems are between 0.0001% and 0.0003% in the ±
100 &
#730
/sec measurement range, while for the 30 Hz bandwidth the R2 nonlinearities are between 0.0002% and 0.0062% in the ±
80&
#730
/sec measurement range. These performance results are the best results obtained at METU, satisfying the tactical-grade performances, and the measured bias instabilities and ARWs are comparable to the best results in the literature for a silicon micromachined vibratory gyroscope.
26
Cheng, Jiqi. "A Study of Wave Propagation and Limited-Diffraction Beams for Medical Imaging." University of Toledo / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1133820434.
Full text
27
Kok, Wing Hang (Ronald). "Development of a wireless MEMS inertial system for health monitoring of structures." Link to electronic thesis, 2004. http://www.wpi.edu/Pubs/ETD/Available/etd-11244-122741/.
Full textAbstract:
Thesis (M.S.)--Worcester Polytechnic Institute.Keywords: angular rate; cantilever; wireless; RF; microcontroller; tilt and rotation; health monitoring; inertial sensors; MEMS. Includes bibliographical references (p. 139-145).
28
Gugel, Denis. "Ordnungsreduktion in der Mikrosystemtechnik." Doctoral thesis, Der Andere Verlag, Tönning, 2008. https://monarch.qucosa.de/id/qucosa%3A19359.
Full textAbstract:
Die vorliegende Arbeit befasst sich mit der Methode der modalen Superposition als Ordnungsreduktionsverfahren in der Mikrosystemtechnik. Typische Anwendungsgebiete sind Inertialsensoren und dabei im Besonderen Drehratensensoren, für die die Simulation von zeitabhängigen Phänomenen von entscheidender Bedeutung ist.
Im Rahmen der Weiterentwicklung der Ordnungsreduktion nach der Methode der modalen Superposition ist es gelungen für typische lineare Kräfte eine auf analytischen Gleichungen basierende Beschreibung im reduzierten Raum zu finden. Für die Beschreibung von nichtlinearen Kräften ist im Rahmen dieser Arbeit ein Verfahren entwickelt worden, das es erlaubt, bestehende Modelle im Finite-Elemente-Raum in der modalen
Beschreibung zu nutzen.
In dieser Arbeit werden die theoretischen Grundlagen zur Berücksichtigung von Einflüssen der Aufbau- und Verbindungstechnik in ordnungsreduzierten Modellen dargestellt. Neben der Einkopplung äußerer Kräfte und der Veränderung der mechanischen Randbedingungen wird auch der Einfluss der Aufbau- und Verbindungstechnik auf die elektrostatischen Eigenschaften untersucht.
Die Parametrisierung des Verfahrens der modalen Superposition über Fit- und Interpolationsverfahren erlaubt es, parametrisierte ordnungsreduzierte Modelle für die zeitabhängige Systemsimulation zu generieren. Damit wird die Durchführung von Designoptimierung und die Berücksichtigung von Fertigungs- und Prozessschwankungen in ordnungsreduzierten Modellen auf Systemebene möglich.
29
Henry, Kevin Claude. "Soft Surface Roll Mechanics Parameters for Light Vehicle Rollover Accident Reconstruction." BYU ScholarsArchive, 2007. https://scholarsarchive.byu.edu/etd/1436.
Full textAbstract:
Light vehicle rollover accidents on soft surfaces can be modeled assuming constant drag with linear motion equations and other engineering principles. The concept of using segment average results to evaluate roll mechanics parameters throughout a roll sequence, and specifically, segment duration to evaluate vehicle trajectory between ground impacts is developed. The trajectory model is presented, explained and compared to values obtained by analyzing digital video of rollover crash tests. Detailed film analysis procedures are developed to obtain data from rollover crash tests that are not otherwise documented. Elevation of the center of gravity of vehicles is obtained where instrumentation does not explicitly yield this data. Instantaneous center of gravity elevation data throughout a roll sequence provides the opportunity to calculate descend distances as a vehicle travels from one ground contact to another. This data is used to quantify severity of ground impacts as a vehicle interact with the ground throughout a roll sequence. Segment average analysis is a reasonable method for determining general roll mechanics parameters. Because of the chaotic nature of rollover accidents, the range of effective drag factors for a given roll surface may be quite large. Choosing an average of typical drag factors is a reasonable approach for a first-order approximation although certain parameters may be predicted less accurately than if actual values were known. The trajectory results demonstrate the influence of drag factor descent height calculations. Typical constant drag factors tend to overestimate descent height early in a roll sequence and underestimate descent height later in the sequence. The trajectory model is a useful tool to aid in understanding rollover mechanics although a rolling vehicle may be in contact with the ground for a significant fraction of a roll segment. The model should not be used at locations in roll sequences where there are extremes in translational center of gravity decelerations. These extremes include the segments immediately following overturn where there are large angular accelerations and large differences between the tangential velocity of the vehicle perimeter and the translational velocity of the center of gravity, as well as segments that include vehicle impacts with irregular topography.
30
Reece, William R. "Exploiting angular correlations in the rare decay Bd -K*0 u+u - at LHCb." Thesis, Imperial College London, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.520835.
Full text
31
Spagnol, Marco. "Maintenance of electrical machines: Instantaneous Angular Speed analysis." Doctoral thesis, Università degli studi di Trieste, 2015. http://hdl.handle.net/10077/11102.
Full textAbstract:
2013/2014This research is focused on the condition monitoring of electrical machines and its long term purpose is to monitor electrical and mechanical faults at the same time, in non-stationary conditions (variable load and speed), with a single piece of hardware. The Instantaneous Angular Speed (IAS) measurement of an electrical machine is proposed and analysed in order to detect the fault development inside it. Chapter 1 introduces some basic principles about the maintenance of an electrical machine. Machine unscheduled downtimes are frequently caused by bearing faults, and rotor/stator faults. Monitoring systems are needed when the machine is very important for the plant (cost, safety). In this chapter, the electrical machine’s behaviour is also examined. Induction electrical machines have been chosen for this research. A review of the excitation frequencies is reported in the chapter. In the last section, characteristic fault frequencies (from mechanical and electrical sources) are collected. Chapter 2 presents the IAS measurement and its signal processing. The IAS is the measurement of the shaft rotating speed in order to visualize what’s happening during a single or in multiple turns. There are many measurement methods which are based either analogical to digital conversion or which use counters. Analogical to digital methods use a standard data acquisition board. Counter methods have to use specific hardware that is more expensive, but with less data to store. In this research, the counter method is used, combined with the Elapsed Time (ET) counting technique. Chapter 3 describes the encoder system. Its output signal is acquired with an oscilloscope and with the counter board. The signal’s differences are highlighted. In this chapter, the measurement’s source of errors are listed: the encoder’s geometrical error, the counter’s quantization error, the clock stability and the general electrical noise. Chapter 4 collects all the experimental tests done during the PhD research. Three experimental test rigs are shown and two measurements at Nidec ASI S.p.A. are reported. Note that the experimental test rigs were designed and built at the Università degli Studi di Trieste during the three years of the PhD. Experimental Test Rig 1 (ETR1) is used to understand the electrical motor’s behaviour with varying speed, the difference between the IAS and the speed acquired with the Torsional Laser Vibrometer, the difference between the IAS and the acceleration signal measured with an accelerometer located on the motor’s stator, the effect of the unbalance in the IAS measurement. Experimental Test Rig 2 (ETR2) allows to examine the load effect on the IAS measurement, the magneto-motive force harmonics, the slip and the rotor effects. Experimental Test Rig 3 (ETR3) is designed in order to detect the Inner Race Bearing Fault (Ball Pass Frequency Inner - BPFI) with varying load. The acceleration, the voltage and the current are compared with the Instantaneous Angular Speed. The motor is also tested with an unbalanced power supply. The two measurements at Nidec ASI S.p.A show how the IAS measurement could be implemented in an industrial machine larger than the one tested in the laboratory. This research presents the pros and cons of the IAS measurement, highlighting the capability of detecting BPFI bearing fault, feeling the load variations owing to the brake system (a synchronous generator), measuring the Fundamental Train Frequency of an healthy bearing, detecting unbalance in the rotor and other special features. The author would like to thank the Fondo Sociale Europeo, the Regione Friuli Venezia Giulia and Nidec ASI S.p.A (an electrical motor company) for the sponsorship and the collaboration during the three PhD years covered by the SHARM project ”Manutenzione Preventiva Integrata”.
Questo studio è focalizzato al monitoraggio dello stato di salute delle macchine elettriche con l'obbiettivo finale di monitorare danni meccanici ed elettrici, in condizioni non stazionarie (carico e velocità variabili), con un singolo sistema hardware. Viene quindi proposta ed analizzata la misura della Velocità Angolare Istantanea (Instantaneous Angular Speed - IAS) di una macchina elettrica allo scopo di prevedere l'insorgere di guasti al suo interno. Il Capitolo 1 introduce i principi base relativi alla manutenzione di macchine elettriche. Di frequente, le fermate non programmate sono conseguenti a danni su cuscinetti e su rotore/statore. I sistemi di monitoraggio sono indispensabili quando la macchina è molto importante nel contesto dell'impianto, considerazione esaminata sia dal punto di vista del costo che della sicurezza. In questo capitolo, viene analizzato anche il funzionamento della macchina elettrica. Dopo un'attenta valutazione, per lo sviluppo di questa ricerca sono state selezionate le macchine ad induzione asincrone. Nel capitolo è riportata anche un'analisi bibliografica sulle frequenze caratteristiche delle forzanti elettromagnetiche presenti. Nell'ultima sezione vengono elencate le frequenze tipiche dei danni rilevabili in misure di tipo vibrazionale ed elettrico. Il Capitolo 2 presenta la misura IAS. Questa rappresenta la misurazione della velocità di rotazione dell'albero e viene analizzata con accuratezza, individuando la relazione tra velocità di rotazione e le caratteristiche dell'encoder; inoltre vengono descritti i vari processamenti del segnale. Tale sistema permette di visualizzare ciò che sta accadendo alla macchina durante il suo funzionamento, in una o più rotazioni. Esistono metodi di misura basati o sulla conversione analogico-digitale o che prevedono l’impiego di contatori. I primi si servono di una scheda di acquisizione dati standard, mentre i secondi richiedono l'utilizzo di un hardware specifico, che alle volte può risultare più costoso, ma permette di acquisire i dati occupando una quantità inferiore di memoria. In questa tesi si è scelto di utilizzare un contatore per eseguire la misura IAS, sfruttando il conteggio Elapsed Time (ET). Il Capitolo 3 descrive l'encoder. Il segnale in uscita dal dispositivo viene acquisito con una scheda contatore e con un oscilloscopio in modo da confrontare ed analizzare le differenze presenti. In questo capitolo vengono elencate le tipologie di errore presenti nel sistema encoder: l'errore geometrico, l'errore di quantizzazione, l'errore dovuto alla stabilità del clock interno e l'errore dovuto a fonti esterni di rumore elettrico. Il Capitolo 4 raccoglie tutti i test sperimentali condotti durante il dottorato. Sono stati progettati e costruiti tre setup allo scopo di evidenziare particolari aspetti e problematiche; sono riportate anche due misure eseguite presso la sala prove dell'azienda Nidec ASI S.p.A. Il setup Experimental Test Rig 1 (ETR1) è stato utilizzato per conseguire le seguenti finalità: capire il funzionamento del motore elettrico con velocità variabile, analizzare la differenza della velocità acquisita con un torsiometro laser ed una scheda contatore, confrontare una misura vibrazionale (accelerometro posizionato sullo statore del motore) e la misura IAS, analizzare l'effetto dello sbilanciamento sulla misura IAS. Il setup Experimental Test Rig 2 (ETR2) permette di esaminare l'effetto del carico sulla misura IAS, le armoniche della forza elettromotrice, l'effetto dello slip e del rotore. Il setup Experimental Test Rig 3 (ETR3) è progettato in modo da evidenziare un difetto sulla guida interna di un cuscinetto, considerando anche un carico variabile. L'accelerazione, il voltaggio e la corrente sono confrontate con la Velocità Angolare Istantanea. Il motore viene testato anche applicando una tensione di alimentazione sbilanciata. Le due misure rilevate in Nidec ASI S.p.A dimostrano che la misura IAS può essere implementata in macchine industriali di grandi dimensioni e non solo nei setup di laboratorio. Questa ricerca espone gli aspetti positivi e negativi della misura IAS, evidenziando le capacità di individuare un danno sulla guida interna di un cuscinetto, captare le variazioni di carico prodotte dal freno (un generatore sincrono), misurare la Fundamental Train Frequency di un cuscinetto in buona salute, individuare uno sbilanciamento ed altre funzionalità. L'autore vuole ringraziare il Fondo Sociale Europeo, la Regione Friuli Venezia Giulia e l'azienda Nidec ASI S.p.A (produttore di macchine elettriche di medio-grandi dimensioni) per la sponsorizzazione e la collaborazione durante i tre anni di dottorato previsti dal progetto SHARM ”Manutenzione Preventiva Integrata”.
XXVII Ciclo
1983
32
Diallo, Abdoulaye Foula. "F-spin study of rare earth nuclei using F-spin multiplets and angular momentum projected intrinsic states." Diss., The University of Arizona, 1993. http://hdl.handle.net/10150/186290.
Full textAbstract:
The proton-neutron Interacting-Boson Model contains both symmetric and mixed-symmetry proton-neutron boson configurations. These states of different proton-neutron symmetry can be classified in terms of an SU(2) symmetry, called F-spin. This dissertation deals with some new applications of F-spin. Even-even nuclei drawn from the proton and neutron shells 50 < Z < 82 and 82 < N < 126, respectively, are systematically classified in F-spin multiplets and their binding energies are fit with a six-parameter mass-formula. Using particle-hole symmetry conjugation, the energies of the low-lying levels of the neutron-rich nuclei are estimated and their mass excesses determined with the mass-formula. The masses of these nuclei are of interest in astrophysical processes. A novel asymptotic realization of the angular-momentum projected intrinsic-state in the generalized IBM is presented. This approach which uses the Laplace method of asymptotic expansion, is shown to be an improvement over the Gaussian method espoused by Kuyucak and Morrison. The method, herein called the 1/Λ-expansion, is used to derive analytical expressions for different quantities in the framework of the generalized IBM. Particular attention is paid to the M1 summed strength, the mean-excitation energy of the mixed symmetry 1⁺ scissor mode, and the gyromagnetic ratios of the ground-band members, for which formulas are derived. A no-free-parameter calculation is performed for the summed M1 strength and the centroid energy of ⁽¹⁴⁶⁻¹⁵⁸⁾Sm isotopes. The g factors of deformed and transitional nuclei in the rare-earth mass region are also computed. The data in all cases are found to be well reproduced, in general. A weak L dependence is predicted for the g factors, and there appears to be no need to include two-body terms in the T(M1) operator for determining the M1 strength.
33
Петренко, Олексій Володимирович. "Удосконалення методів підвищення точності вібраційного гіроскопа з металевим циліндричним резонатором." Thesis, КПІ ім. Ігоря Сікорського, 2020. https://ela.kpi.ua/handle/123456789/36992.
Full textAbstract:
Робота виконана на кафедрі аерокосмічних систем управління Національного авіаційного університету Міністерства освіти і науки України та у Публічному акціонерному товаристві «Науково-виробниче об’єднання «Київський завод автоматики».Дисертаційна робота присвячена науковому обґрунтуванню та розробці алгоритмів компенсації внутрішніх похибок та зовнішніх збурень у Коріолісовому вібраційному гіроскопі, а також удосконаленню його складових частин (резонатора, чутливого елементу). Автором розроблено методику та обладнання для робочого місця безелектродного вимірювання динамічних параметрів металевого резонатора після його виготовлення, розроблено конструкцію приладдя для приклеювання п’єзоелектродів до резонатора нової конструкції, методику та обладнання робочого місця для балансування мас. Розроблено та відпрацьовано на експериментальному зразку КВГ методики температурної корекції фаз сигналів квадратури та кутової швидкості, багатопараметричної корекції дрейфу нуля і масштабного коефіцієнту, що призводить до збільшення точності виміру кутової швидкості в умовах дії температурних градієнтів.
In the thesis the following new scientific results are obtained: 1. For the first time, a multi-parameter method of CVG scale factor correction is developed and implemented, which can be used during the CVG operation in the rate and in the differential modes. Ukraine patent have been obtained for this method. 2. Scientifically grounded analysis of a new design of a cylindrical resonator with holes on the walls of a cylinder having higher vibration resistance was first developed and carried out. 3. The multiparameter bias correction algorithm has been developed and implemented, which has advantages over the existing ones by accuracy. 4. For the first time experimental researches were carried out on a manufactured experimental sample of CVG with developed metal cylindrical resonator made of elenvar elloy, which showed high accuracy scale factor and bias drift correction under the action of temperature gradient, as well as high shockvibration resistance of the sample. The practical significance of thesis results are: − comparison of two designs of metallic cylindrical resonators with holes on the bottom and on the wall of the cylinder and by calculations and computer simulation the advantages of the second design over the first one in the part of shock resistance have been substantiated; − аn analysis of the different geometries of the holes has been made. Their influence on the resonant oscillation frequencies of a cylindrical resonator is revealed. Recommendations for the geometry of the resonator and its elements have been developed; − improved design of the base on which the newly designed resonator with holes on the wall of the cylinder is installed; − the choice of electrodes used for oscillation excitation and measurement of the signals is experimentally substantiated; − the technique and equipment for workplace electrodeless measurement of metallic resonator dynamic parameters after its manufacture have been developed; − the influence of frequency mismatch, wave angle and positioning errors of the electrodes on the CVG bias and scale coefficient have been evaluated; − a new accessory design has been developed to attach the electrodes to the new resonator design; − the technique and equipment of the workplace for balancing the mass of the resonator on the fourth harmonic of the unbalance to reduce its frequency mismatch have been developed. The technique was tested in the manufactured ample of CVG; − the technique of measuring the angles of non-orthogonality of the sensitive axis to its mounting surface has been developed and implemented in the experimental sample of CVG; − the use of CVG to improve the accuracy of armament stabilization was analyzed; − improved CVG standing wave control algorithm block diagram, which provides a fast start of the gyroscope when it is turned on at any temperature in the range of operating temperatures; − the techniques for temperature correction of quadrature and angular rate phases, multiparameter correction of CVG bias and scale factor have been developed and tested on experimental sample of CVG, which leads to an increase in the accuracy of measuring angular rate under temperature gradients; − the experimental results showed that the CVG with a metallic resonator is resistant to multiple shocks with amplitude 100 g and its bias is slightly dependent on the shock amplitude and does not exceed 5×10−3 deg/s. The bias sensitivity to vibration perturbations is 2.5×10−3 deg/s/g.
Диссертация посвящена научному обоснованию и разработке алгоритмов компенсации внутренних погрешностей и внешних возмущений в Кориолисового вибрационном гироскопе, а также совершенствованию его составных частей (резонатора, чувствительного элемента). Автором разработана методика и оборудование для рабочего места безэлектродного измерения динамических параметров металлического резонатора после его изготовления, разработана конструкция приспособления для приклеивания пьезоэлектродов к резонатору новой конструкции, методику и оборудование рабочего места для балансировки масс резонатора. Разработано и отработано на экспериментальном образце КВГ методики температурной коррекции фаз сигналов квадратуры и угловой скорости, многопараметрической коррекции дрейфа нуля и масштабного коэффициента, что приводит к увеличению точности измерения угловой скорости в условиях действия температурных градиентов.
34
BRUNDU, DAVIDE. "Radiation hardness of the upgraded LHCb muon detector electronics and prospects for a full angular analysis in multi-body rare charm decays." Doctoral thesis, Università degli Studi di Cagliari, 2020. http://hdl.handle.net/11584/284134.
Full textAbstract:
In this dissertation the results of the studies on the new readout electronics for the muon system
of the LHCb experiment, and the perspectives for carrying out a full angular analysis in the
rare decays D0 -> pi+ pi- mu+ mu- and D0 -> K+ K- mu+ mu- will be described.
The LHCb experiment studies the heavy hadron physics, containing charm or bottom quarks,
in particular searching for new Charge-Parity (CP ) symmetry violation sources, searching for
rare decays and studying their properties. LHCb produced leading results in these fields so
far. In order to obtain more precise measurements or be able to study new observables, many
analyses need a considerable increase in statistics, thus the experiment is now being upgraded
to run with an higher instantaneous luminosity of proton-proton collisions. For this reason the
readout electronics has been completely replaced by a new optimised version. Several tests
have been performed on the new readout electronics that will be here discussed, and that have
allowed a comprehensive radiation hardness characterization of the UMC 130 nm technology,
used to develop the main electronics device of the muon system readout electronics, the nSYNC
chip.
On the other hand, in the last two years of data taking, 2017 and 2018, an excellent
performance of the LHCb experiment has been obtained and the significant increase in statistics
allowed access to new observables, especially in the field of rare decays. In particular, it has been
possible to increase the statistics of rare four-body charm decays, like D0 -> pi+ pi- mu+ mu- and
D0 -> K+ K- mu+ mu- , of which LHCb already carried out the branching fractions measurement,
as well as of angular and CP asymmetries. Since interesting results and flavour anomalies
have already been obtained from angular analyses of rare B decays, it is important to study
the possibility of these analyses in the complementary sector of rare charm decays. In this
work the perspectives for performing a full angular analysis with D0 -> pi+ pi- mu+ mu- and
D0 -> K+ K- mu+ mu- decays will be discussed. An angular analysis will allow to carry out several
Standard Model tests in the field of rare D decays, allowing also to measure theoretically clean
observables for probing effects of physics beyond Standard Model, that can occur at high energy
scale.
35
Coquereau, Samuel. "Study of the B⁰→K*⁰μ⁺μ⁻ decay with the LHCb experiment : angular analysis and measurement of the ratio RK*." Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066366.
Full textAbstract:
Les désintégrations de quark b rares interviennent principalement via des courant neutres changeant la saveur, (Flavor Changing Neutral Current, FCNC en anglais). Le modèle Standard n'autorise les courants qu'au niveau des boucles. Ces processus FCNC sont sujets à une suppression de GIM conduisant à des processus rares. Par conséquent les désintégration b→s sont de très bon outils pour la recherche de phénomène de Nouvelle Physique au delà du Modèle Standard. Cette thèse présente l'analyse angulaire de la désintégration B⁰→K*⁰μ⁺μ⁻ avec l'ensemble des données collecté par l'expérience lhcb durant le run I du lhc. La complète série des observable angulaires a été mesuré via un ajustement d'une fonction de vraisemblance, grâce à une sélection amélioré et les 3 fb⁻¹ de donné collecté en 2011 et 2012 par lhcb. Par ailleurs, l'analyse du rapport R_{K*} est également présenté et les résultats sont attendu pour la fin de l'année 2015Rare beauty decays proceed mostly through the b→s Flavor Changing Neutral Current, which is possible only at loop level in the Standard Model. These FCNC processes are subject to GIM suppression leading to a rare decay. Therefore the b→s processes are good tools to look for New Physics phenomenon beyond the Standard Model. New Physics particle could become detectable by causing deviation from the Standard Model predictions for observables such as angular observables, branching ratio or CP asymmetries. This thesis present the angular analysis of the B⁰→K*⁰μ⁺μ⁻ decay with the whole dataset collected by lhcb during the first run of the lhc. The full set of the angular observables has been measured through a maximum likelihood fit, thanks to an improved selection and the 3 fb⁻¹ of data collected in 2011 and 2012 by lhcb. In addition, the analysis on the measurement of the ratio R_{K*} has also been presented and the results are expected by the end of 2015
36
JUNQUEIRA, ASTROGILDO de C. "Estudo de interacoes hiperfinas em oxidos perovskitas do tipo La(MT)Osub(3) (MT=metais de transicao Fe, Cr, Mn e Co)." reponame:Repositório Institucional do IPEN, 2004. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11242.
Full textAbstract:
Made available in DSpace on 2014-10-09T12:49:51Z (GMT). No. of bitstreams: 0Made available in DSpace on 2014-10-09T14:03:04Z (GMT). No. of bitstreams: 1 09826.pdf: 5905522 bytes, checksum: b0354cc2f21014da9657b88019b2b992 (MD5)
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
FAPESP:99/07068-0
37
CAVALCANTE, FABIO H. de M. "Estudo de interacoes hiperfinas em oxidos RCoOsub(3) (R=Gd e Tb) e filmes finos de HfOsub(2) por meio da tecnica de espectroscopia de correlacao angular gama-gama perturbada." reponame:Repositório Institucional do IPEN, 2009. http://repositorio.ipen.br:8080/xmlui/handle/123456789/9422.
Full textAbstract:
Made available in DSpace on 2014-10-09T12:26:40Z (GMT). No. of bitstreams: 0Made available in DSpace on 2014-10-09T14:06:23Z (GMT). No. of bitstreams: 0
Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
38
Desse, Fabrice. "Analyse angulaire de désintégrations B⁰ →K*⁰e⁺e⁻ avec le détecteur LHCb et upgrade de l'électronique des calorimètres." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASS126.
Full textAbstract:
Les courants neutres changeant la saveur de type b -> s gamma ne sont autorisés qu’au niveau des boucles dans le Modèle Standard (MS). Ils sont donc potentiellement sensibles à des effets de Nouvelle Physique (NP) intervenant dans les boucles quantiques qui pourraient se manifester via la modification de certaines observables angulaires. Dans le MS, le photon est principalement émis avec une polarisation gauche. Cependant, plusieurs théories de NP autorisent une importante contribution des courants droits. L’analyse angulaire des désintégrations B0->K*e+e- à très bas q2 (la masse invariante de la paire de dielectron au carré) permet d’étudier la structure de l’hélicité des transitions b -> s gamma grâce à la contribution dominante du photon virtuel couplé à la paire de dielectron à très bas q2. Cette thèse présente l’analyse angulaire de désintégrations B0->K*e+e- utilisant l’ensemble des collisions proton-proton enregistrées par l’expérience LHCb durant les Run 1 et 2 entre 2011 et 2018, représentant une luminosité intégrée de 9.1 fb^−1 aux énergies dans le centre de masse allant de 7 à 13 TeV. Les asymétries transverses dans la région de q2 [0.0001, 0.25] GeV^2 /c^4 sont mesurées à hauteur de AT(2) = 0.106 ± 0.103 + 0.016 −0.017 , ATIm = 0.015 ± 0.102 ± 0.012, ATRe = −0.064 ± 0.077 ± 0.015 et FL = 0.044 ± 0.026 ± 0.014. 077 ± 0.015et F L = 0.044 ± 0.026 ± 0.014. Ces mesures représentent actuellement la plus importante contrainte mondiale sur la polarisation droite du photon dans les transitions b->s gamma.Le détecteur LHCb subit une importante mise à jour en 2019/2020 afin de faire fonctionner l’expérience à une luminosité instantanée de 2 × 10^33 cm−2s−1. L’électronique des calorimètres doit notamment être mise à niveau avec de nouvelles Cartes Front-End (CFE) adaptées à une lecture à 40 MHz. Cette thèse présente également l’upgrade du module Low Level Trigger de la CFE qui est notamment responsable de l’identification des cluster d’énergie transverse maximale pour chaque évènementFlavor changing neutral current processes of the type b -> s gamma are forbidden at tree level in the Standard Model (SM). They are thus sensitive to potential New Physics (NP) effects occurring via loop processes which may manifest themselves through the modification of angular observables. In the SM, the photon is predominantly left handed. However several NP theories allow large right-handed currents. The angular analysis of B0 ->K*e+e- decays at very low q2 (the dielectron pair invariant mass squared) allows to study the helicity structure of b -> s gamma transitions thanks to the dominant contribution from the virtual photon coupling to the dielectron pair at very low q2. This thesis presents the angular analysis of B0 ->K*e+e- decays using the full Run 1 and Run 2 proton-proton collision datasets collected between 2011 and 2018 at the LHCb experiment, corresponding to an integrated luminosity of 9.1 fb^-1 at centre-of-mass energies ranging from 7 to 13 TeV. The transverse asymmetries in the q2 range [0.0001, 0.25] GeV^2/c^4 are measured as AT(2) = 0.106 ± 0.103 + 0.016−0.017 , ATIm = 0.015 ± 0.102 ± 0.012, ATRe = −0.064 ± 0.077 ± 0.015 and FL = 0.044 ± 0.026 ± 0.014. These measurements provide the current world’s best constraint on right handed contributions to the photon polarization in b -> s gamma transitions.The LHCb detector is undertaking a major upgrade in 2019/2020 to be able to run the experiment at an instantaneous luminosity of 2 × 10^33cm−2s−1 . In particular, the electronics of the calorimeters has to be upgraded with new Front-End boards (FEB) to cope with the 40 MHz readout. This thesis also presents the upgrade of the Low Level Trigger module of the FEB, which is in particular responsible for identifying the maximum transverse energy cluster of each event
39
恵子, 名取, and Keiko Natori. "微細複合組織金属の変形機構および塑性加工性に関する研究." Thesis, https://doors.doshisha.ac.jp/opac/opac_link/bibid/BB12867122/?lang=0, 2014. https://doors.doshisha.ac.jp/opac/opac_link/bibid/BB12867122/?lang=0.
Full textAbstract:
ヘテロ構造組織を有する鉄・非鉄金属の組織形態に注目して,微視的構造やその挙動が巨視的現象(変形特性,成形性)として発現するメカニズムを解明することを目的とした.鉄系金属ではDual Phase型高張力鋼のスプリングバック現象のひずみ速度依存性,非鉄系金属では半凝固鋳造法と強ひずみ加工を組み合わせた亜共晶アルミニウム合金の衝撃後方押出し成形性に注目した.これらの検討によりいずれの試料においても,結晶粒界よりもスケールの大きいヘテロ構造に由来した変形機構が支配的であることが明らかになった.博士(工学)
Doctor of Philosophy in Engineering
同志社大学
Doshisha University
40
Patwari, Neal. "Measured and Modeled Time and Angle Dispersion Characteristics of the 1.8 GHz Peer-to-Peer Radio Channel." Thesis, Virginia Tech, 1999. http://hdl.handle.net/10919/32201.
Full textAbstract:
In an extensive outdoor propagation study, low antenna heights of
1.7 m are used at both the transmitter and the receiver to measure
over 3500 wideband power-delay profiles (PDPs) of the channel for
a peer-to-peer communications system. Rural and urban areas are
studied in 22 different transmitter-receiver links. The results
are used to characterize the narrowband path loss, mean delay,
root-mean-square (RMS) delay spread, and timing jitter of the
peer-to-peer wideband channel. Small-scale fading characteristics are
measured in detail by measuring and analyzing 160 PDPs within each
local area. This thesis shows the measurement setup for the
calculation of fading rate variance and angular spread and reports
the first known attempt to calculate angular spread from track
power measurements. New analysis presented in this thesis shows
the effect of measurement error in the calculation of angular
spread. The expected characteristics of angular spread are
derived using two different angle-of-arrival (AOA) models from the
literature. Measurement results show initial validation of
Durgin's angular spread theory. A new measurement-based algorithm
for simulating wideband fading processes is developed and
implemented. This simulation technique shows promise in the
simulation of high-bit rate peer-to-peer radio communication
systems.Master of Science
41
CORREA, EDUARDO DE L. "Produção, caracterização e aplicação de nanopartículas de Gd2O3 e Er2O3 como radiossensibilizadores em feixes de Radioterapia." reponame:Repositório Institucional do IPEN, 2017. http://repositorio.ipen.br:8080/xmlui/handle/123456789/27968.
Full textAbstract:
Submitted by Marco Antonio Oliveira da Silva (maosilva@ipen.br) on 2017-11-08T16:29:11Z
No. of bitstreams: 0Made available in DSpace on 2017-11-08T16:29:11Z (GMT). No. of bitstreams: 0
Nesse trabalho foram produzidas nanopartículas (NPs) de Gd2O3 e Er2O3 para aplicação como radiossensibilizadores em feixes de radioterapia. Elas foram sintetizadas no Laboratório de Interações Hiperfinas do IPEN pelo método da decomposição térmica e caracterizadas utilizando difração de raios-X, para verificar a estrutura cristalina, microscopia eletrônica de transmissão, para obter informações sobre forma, tamanho e distribuição de tamanho, análise por ativação neutrônica, por meio da qual foi possível determinar a pureza das amostras e calcular a concentração de gadolínio e érbio. Medições de magnetização e de espectroscopia de correlação angular γ-γ perturbada (PAC) foram realizadas a fim de estudar o comportamento magnético e a interação quadrupolar das partículas, respectivamente. Os resultados da caracterização mostram a formação de uma estrutura cristalina do tipo bixbyite, com aproximadamente 5 nm de diâmetro e estreita distribuição de tamanho, para as amostras pós-síntese. A determinação da massa de terra-rara em cada amostra foi importante para realizar a normalização nas medições de susceptibilidade magnética, tornando possível a visualização de um grande aumento na magnetização abaixo de 30 K, nas amostras pós-síntese, o que não é observado em partículas maiores, além de um aumento no momento magnético efetivo das NPs em relação aos respectivos bulks e uma mudança na temperatura de ordenamento antiferromagnético para o Er2O3. Os resultados da espectroscopia PAC evidenciam possíveis efeitos de superfície. A falta de uma frequência bem definida nas amostras de 5 nm indicam que a quantidade de 111In(111Cd) na superfície da partícula é maior do que no interior da mesma, fazendo com que a interação hiperfina do núcleo de prova com o host não seja evidente. Já a união da técnica de difração de raios-X com a espectroscopia PAC foi fundamental para o entendimento do dano causado às partículas pela irradiação com 60Co. Quanto às medições de radiossensibilização a dosimetria Fricke gel foi fundamental para a verificação de um fator de aumento de dose (DEF) de até 1,67 e 1,09 para NPs de Gd2O3 irradiadas com 60Co e 6MV, respectivamente. Nas mesmas condições, para as amostras de Er2O3, foram encontrados valores de DEF de até 1,37 e 1,06. Isso comprova os efeitos radiossensibilizadores dessas NPs. Os resultados alcançados nesse trabalho não apenas fornecem dados importantes para o estudo de NPs de terra-rara na área de física da matéria condensada como também uma base sólida para a aplicação desses elementos como radiossensibilizadores em feixes de radioterapia, possibilitando a utilização da imagem por ressonância magnética para localizar e obter a concentração dessas NPs dentro do paciente, aumentando assim a eficiência do tratamento do câncer.
Tese (Doutorado em Tecnologia Nuclear)
IPEN/T
Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP
42
Huang, Yi-Kai, and 黃奕凱. "Initial Attitude Acquisition of Sunsynchronous Satellites Using Angular Rate Feedback." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/56233928414348288324.
Full textAbstract:
碩士淡江大學
航空太空工程學系碩士班
101
This thesis initital acquisition of sun-synchronous satellites using angular rate feedback in the separation stage control.Because the satellite and vehicles in the separation stage, the satellite will produce angular velocity caused by rolling, making the satellite can not determine the Sun, the Earth or other celestial body position, and at this stage there are restrictions on the energy, you can not use too complex control relatively energy-intensive method or sensors. Therefore, in this thesis, choose a more direct way to control the angular velocity, thus using the angular rate feedback control, the study found that this control method can effectively reduce the angular velocity, the angular velocity of the satellite in any direction and attitude can be maintained stable, sun-synchronous orbit as used, so long as they can stabilized satellite, you can take advantage of the characteristics of a sun-synchronous orbit point to find the sun. In the study method, the first to use Matlab / Simulink establish satellite dynamic model and simulate the initial orbit of the satellite, the angular rate feedback control as a controller to the model and complete the simulation model. Use NSPO''s data with the simulation results are compared to determine the reliability of this method.
43
Vivek, Chandran K. P. "Development Of Gyroless Attitude And Angular Rate Estimation For Satellites." Thesis, 2009. https://etd.iisc.ac.in/handle/2005/1121.
Full textAbstract:
Studies aimed at the development of indigenous low cost star tracker and gyroless attitude and angular rate estimation is presented in the thesis. This study is required for the realization of low cost micro satellites. A target specification of determining the attitude with accuracy (3σ) of 0.05 degrees and attitude rate with accuracy (3σ) in the range of 50rad/sec at a rate of 10 samples/second in all the axes is set as a goal for the study. Different sensor arrays available in the market are evaluated on the basis of their noise characteristics, resolution of the analog-to-digital converter (ADC) present and ability to work in low light conditions, for possible use in the hardware realization of star tracker. STAR1000 APS CMOS array, manufactured by Cypress Semiconductors, qualified these performance criteria, is used for the simulation study. An algorithm is presented for scanning the sensor array, detection of star image and retrieving the information concerning the photoelectron counts corresponding to a star image. The exact designation of the center of the star image becomes crucial as it has direct implications on the accuracy of the estimated attitude. Various algorithms concerning the centroid estimation of a defocused star image on the sensor array to subpixel accuracy are studied and Gaussian Weighed Center of Gravity algorithm is adapted with some modifications and an accuracy of 0.039 pixels is obtained in both horizontal and vertical direction of the array. A one-to-one relationship is established between the stars obtained in the field-of-view (FOV) of the star tracker with the stars present in the star catalog resident in the star tracker through star identification algorithm. A star identification algorithm which relies on the interstar angles and brightness of the stars is developed in this thesis. The interstar angles of the stars visible in the FOV of the star sensor is recorded, compared with the inter-star angles made by the stars selected in the catalog, based on initial brightness match with stars formed on image plane. After identification at the initial epoch, consequent instants can drive information from the previous matches so as to decrease the computational complexity and storage requirement for the subsequent instants. The memory constraints and computational overhead on the processor and the dynamic range of the image detector used in the star tracker are the limiting factors. The stars thus identified with the stars in the catalog are used for the estimation of attitude. A point solution to the attitude estimation problem is computed using a least square based algorithm called ESOQ-2. The algorithm for centroiding of star images and ESOQ-2 for finding the point solution satellite attitude is coded and tested on Da Vinci based emulator. This exercise shows that it is possible to implement above algorithm for real time operations. Estimation of attitude at a given epoch using algorithms like ESOQ-2 does not minimize the noise and error covariance as the attitude estimated at each instant of time depends only on the measurement taken at that particular instant. So a Kalman Filter (KF) based estimation using Integrated Rate Parameter (IRP) formulation called SIAVE algorithm, is adapted, with some modifications, for the estimation of incremental angle and attitude rates from vector observations of stars. From the point solution of attitude estimation problem of the satellite, the incremental angle and angular rate at successive time steps are predicted using a linear KF and refined with the measurements from the stand alone star tracker, taken at discrete time steps, using the SIAVE algorithm. The sensor noise is modeled from the characteristics of STAR1000 sensor array used in the algorithm in order to make the simulations more realistic in nature. The optimality of Kalman filter is based on the assumption that the state and measurement noises are white gaussian random processes and the state dynamics of the plant is completely known. However, for most real systems, modeling uncertainties are present. So a robust state estimator based on H∞ norm minimization is devised. The H∞ filter, based on game theory approach is used to minimize the worst case variance of noise signals with the only assumption on the noise signals that they are energy bounded. The aim is to find the feasibility of using H∞ filter for the estimation of incremental angle and attitude rate of the satellite. The studies shows that H∞ filter with proper tuning can serve as potential estimation scheme for the attitude and angular rate estimation of the satellite. It is found that both Kalman filter and H∞ are able to meet the specified accuracy desired from low cost accurate star sensor.
44
Vivek, Chandran K. P. "Development Of Gyroless Attitude And Angular Rate Estimation For Satellites." Thesis, 2009. http://hdl.handle.net/2005/1121.
Full textAbstract:
Studies aimed at the development of indigenous low cost star tracker and gyroless attitude and angular rate estimation is presented in the thesis. This study is required for the realization of low cost micro satellites. A target specification of determining the attitude with accuracy (3σ) of 0.05 degrees and attitude rate with accuracy (3σ) in the range of 50rad/sec at a rate of 10 samples/second in all the axes is set as a goal for the study. Different sensor arrays available in the market are evaluated on the basis of their noise characteristics, resolution of the analog-to-digital converter (ADC) present and ability to work in low light conditions, for possible use in the hardware realization of star tracker. STAR1000 APS CMOS array, manufactured by Cypress Semiconductors, qualified these performance criteria, is used for the simulation study. An algorithm is presented for scanning the sensor array, detection of star image and retrieving the information concerning the photoelectron counts corresponding to a star image. The exact designation of the center of the star image becomes crucial as it has direct implications on the accuracy of the estimated attitude. Various algorithms concerning the centroid estimation of a defocused star image on the sensor array to subpixel accuracy are studied and Gaussian Weighed Center of Gravity algorithm is adapted with some modifications and an accuracy of 0.039 pixels is obtained in both horizontal and vertical direction of the array. A one-to-one relationship is established between the stars obtained in the field-of-view (FOV) of the star tracker with the stars present in the star catalog resident in the star tracker through star identification algorithm. A star identification algorithm which relies on the interstar angles and brightness of the stars is developed in this thesis. The interstar angles of the stars visible in the FOV of the star sensor is recorded, compared with the inter-star angles made by the stars selected in the catalog, based on initial brightness match with stars formed on image plane. After identification at the initial epoch, consequent instants can drive information from the previous matches so as to decrease the computational complexity and storage requirement for the subsequent instants. The memory constraints and computational overhead on the processor and the dynamic range of the image detector used in the star tracker are the limiting factors. The stars thus identified with the stars in the catalog are used for the estimation of attitude. A point solution to the attitude estimation problem is computed using a least square based algorithm called ESOQ-2. The algorithm for centroiding of star images and ESOQ-2 for finding the point solution satellite attitude is coded and tested on Da Vinci based emulator. This exercise shows that it is possible to implement above algorithm for real time operations. Estimation of attitude at a given epoch using algorithms like ESOQ-2 does not minimize the noise and error covariance as the attitude estimated at each instant of time depends only on the measurement taken at that particular instant. So a Kalman Filter (KF) based estimation using Integrated Rate Parameter (IRP) formulation called SIAVE algorithm, is adapted, with some modifications, for the estimation of incremental angle and attitude rates from vector observations of stars. From the point solution of attitude estimation problem of the satellite, the incremental angle and angular rate at successive time steps are predicted using a linear KF and refined with the measurements from the stand alone star tracker, taken at discrete time steps, using the SIAVE algorithm. The sensor noise is modeled from the characteristics of STAR1000 sensor array used in the algorithm in order to make the simulations more realistic in nature. The optimality of Kalman filter is based on the assumption that the state and measurement noises are white gaussian random processes and the state dynamics of the plant is completely known. However, for most real systems, modeling uncertainties are present. So a robust state estimator based on H∞ norm minimization is devised. The H∞ filter, based on game theory approach is used to minimize the worst case variance of noise signals with the only assumption on the noise signals that they are energy bounded. The aim is to find the feasibility of using H∞ filter for the estimation of incremental angle and attitude rate of the satellite. The studies shows that H∞ filter with proper tuning can serve as potential estimation scheme for the attitude and angular rate estimation of the satellite. It is found that both Kalman filter and H∞ are able to meet the specified accuracy desired from low cost accurate star sensor.
45
Burnie, Marc. "MODAL ANALYSIS OF MEMS GYROSCOPIC SENSORS." Thesis, 2010. http://hdl.handle.net/1974/5701.
Full textAbstract:
Microgyroscopes find popular applications in modern life, such as, vehicle navigation, inertial positioning, human body motion monitoring, etc. In this study, three unique MEMS gyroscopic sensors were investigated using experimental methods and finite element analysis (FEA) modelling, particularly their modal behaviour. The analytical, simulated and experimental results were compared and the discrepancy between resonant frequencies of the significant mode shapes was discussed.
Three microfabricated gyroscopes were investigated: a thermally-actuated in-plane gyroscope, an electrostatically-actuated in-plane gyroscope and an electrostatically-actuated out-of-plane gyroscope. Numerical finite element modal analysis for these three gyroscopes was conducted using COMSOL Multiphysics. The experimental testing was conducted using a microsystem analyzer (MSA-400 PolyTec) with an integrated laser vibrometer.
The simulation models predicted that the frequencies for driving and sensing modes were 4.948kHz and 5.459kHz for a thermally-actuated gyroscope, which agreed well with experimentally determined results of 5.98kHz and 6.0kHz respectively. The power requirements of a thermally-actuated gyroscope were 363.39mW to elicit a maximum peak-to-peak displacement of 4.2μm during dynamic operation. Similarly, the simulated frequencies for the driving and sensing modes were 1.170kHz and 1.644kHz for an electrostatically-actuated in-plane gyroscope, which corresponded to experimentally determined resonant frequencies 1.6kHz and 1.9kHz.
Simulation for the electrostatically-actuated out-of-plane gyroscope was conducted and the frequencies for the driving and sensing modes were found to be 2.159kHz and 3.298kHz. Due to some fabrication defects, the experimental testing for this microgyroscope was not successful. Some recommendations to improve the design were provided for the future work.Thesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2010-06-02 22:00:52.994
46
Chuang, Ming-Chieh, and 莊明傑. "Formation and Properties of High Strain Rate Superplastic Zn-22 wt.% Al Alloy by Equal Channel Angular Extrusion." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/93747148766580559790.
Full textAbstract:
碩士大同大學
材料工程學系(所)
92
In this study thermomechanical processings were applied to a Zn-22 wt.% Al alloy to produce fine equiaxed grain structure for the high strain rate superplasticity studies. The microstructure, hardness and superplastic properties of Zn-22 wt.% Al alloy was studied by using differential scanning calorimetry (DSC), scanning electron microscopy (SEM), microhardness measurements and tensile tester. The results showed that the microduplex Zn-22 wt.% Al alloy specimens exhibited low temperature high strain rate (LTHS) and high temperature high strain rate (HTHS) superplasticity when they were solution treated, quenched and properly thermomechanical processed through low temperature aging and equal channel angular extrusion (ECAE). A “work softening” phenomenon has been observed in the ECAE processing of the Zn-Al alloy at the extrusion temperatures investigated from -10℃ to 50℃. A boundary related DRV model based on the absorption of dislocation pile-up by grain boundary is proposed to explain the “work softening” behavior. The ECAE not only work softened the Zn-Al alloy but also converted the low angle boundaries of precipitates to high angle boundaries in the process of repeatedly DRV, which eventually leads to the high strain rate superplasticity in the ECAEed Zn-Al alloy. According to the microstructure examinations on deformed tensile specimens and the analysis of the superplasticity data, the mechanisms governing the HTLS and HTHS superplasticity were proven to be GBS and boundary related DRV, respectively. For the LTHS superplasticity occurred in the Zn-Al alloy, the governing mechanism is the boundary related DRV.
47
Pal, Madhumita. "Accurate and Efficient Algorithms for Star Sensor Based Micro-Satellite Attitude and Attitude Rate Estimation." Thesis, 2013. http://etd.iisc.ac.in/handle/2005/3428.
Full textAbstract:
This dissertation addresses novel techniques in determining gyroless micro-satellite attitude and attitude rate. The main objective of this thesis is to explore the possibility of using commercially available low cost micro-light star sensor as a stand-alone sensor for micro-satellite attitude as well as attitude rate determination. The objective is achieved by developing accurate and computationally efficient algorithms for the realization of onboard operation of a low fidelity star sensor. All the algorithms developed here are tested with the measurement noise presented in the catalog of the sensor array STAR-1000.
A novel accurate second order sliding mode observer (SOSMO) is designed for discrete time uncertain linear multi-output system. Our design procedure is effective for both matched and unmatched bounded uncertain ties and/or disturbances. The bound on uncertainties and/or disturbances is assumed to be unknown. This problem is addressed in this work using the second order multiple sliding modes approach. Second order sliding manifold and corresponding sliding condition for discrete time system is defined similar on the lines of continuous counterpart. Our design is not restricted to a particular class of uncertain (matched) discrete time system. Moreover, it can handle multiple outputs unlike single out-put systems. The observer design is achieved by driving the state observation error and its first order finite difference to the vicinity of the equilibrium point (0,0) in a finite steps and maintaining them in the neighborhood thereafter. The estimation synthesis is based on Quasi Sliding Mode (QSM) design.
The problem of designing sliding mode observer for a linear system subjected to unknown inputs requires observer matching condition. This condition is needed to ensure that the state estimation error is a asymptotically stable and is independent of the unknown input during the sliding motion. In the absence of a matching condition, asymptotic stability of the reduced order error dynamics on the sliding surface is not guaranteed. However, unknown bounded inputs guarantee bounded error on state estimation. The QSM design guarantees an ultimate error bound by incorporating Boundary Layer (BL) in its design procedure.
The observer achieves one order of magnitude improvement in estimation accuracy than the conventional sliding mode observer (SMO) design for an unknown input. The observer estimation errors, satisfying the given stability conditions, converge to an ultimate finite bound (with in the specified BL) of O(T2), where T Is the sampling period. A relation between sliding mode gain and boundary layer is established for the existence of second order discrete sliding motion. The robustness of the proposed observer with respect to measurement noise is also analyzed. The design algorithm is very simple to apply and is implemented for two examples with different classes of disturbances (matched and unmatched) to show the effectiveness of the design. Simulation results show the robustness with respect to the measurement noise for SOSMO.
Second order sliding mode observer gain can be calculated off-line and the same gain can work for large band of disturbance as long as the disturbance acting on the continuous time system is bounded and smooth. The SOSMO is simpler to implement on board compared to the other traditional nonlinear filters like Pseudo-Linear-Kalman-filter(PLKF); Extended Kalman Filter(EKF). Moreover, SMO possesses an automatic adaptation property same as optimal state estimator(like Kalman filter) with respect to the intensity of the measurement noise. The SMO rejects the noisy measurements automatically, in response to the increased noise intensity. The dynamic performance of the observer on the sliding surface can be altered and no knowledge of noise statistics is required. It is shown that the SOSMO performs more accurately than the PLKF in application to micro-satellite angular rate estimation since PLKF is not an optimal filter.
A new method for estimation of satellite angular rates through derivative approach is proposed. The method is based on optic flow of star image patterns formed on a star sensor. The satellite angular rates are derived directly from the 2D-coordinates of star images. Our algorithm is computationally efficient and requires less memory allocation compared to the existing vector derivative approaches, where there is also no need for star identification. The angular rates are computed using least square solution method, based on the measurement equation obtained by optic flow of star images. These estimates are then fed into discrete time second order sliding mode observer (SOSMO). The performance of angular rate estimation by SOSMO is compared with the discrete time First order SMO and PLKF. The SOSMO gives the best estimates as compared to the other two schemes in estimating micro-satellite angular rates in all three axes. The improvement in accuracy is one order of magnitude (around1.7984 x 10−5 rad/ sec,8.9987 x 10−6 rad/ sec and1.4222 x 10−5 rad/ sec in three body axes respectively) in terms of standard deviation in steady state estimation error.
A new method and algorithm is presented to determine star camera parameters along with satellite attitude with high precision even if these parameters change during long on-orbit operation. Star camera parameters and attitude need to be determined independent of each other as they both can change. An efficient, closed form solution method is developed to estimate star camera parameters (like focal length, principal point offset), lens distortions (like radial distortion) and attitude. The method is based on a two step procedure. In the first step, all parameters (except lens distortion) are estimated using a distortion free camera model. In the second step, lens distortion coefficient is estimated by linear least squares (LS) method. Here the derived camera parameters in first step are used in the camera model that incorporates distortion. However, this method requires identification of observed stars with the catalogue stars. But, on-orbit star identification is difficult as it utilizes the values of camera calibrating parameters that can change in orbit(detector and optical element alignment get change in orbit due to solar pressure or sudden temperature change) from the ground calibrated value. This difficulty is overcome by employing a camera self-calibration technique which only requires four observed stars in three consecutive image frames. Star camera parameters along with lens (radial and decentering) distortion coefficients are determined by camera self calibration technique. Finally Kalman filter is used to refine the estimated data obtained from the LS based method to improve the level of accuracy.
We consider the true values of camera parameters as (u0,v0) = (512.75,511.25) pixel, f = 50.5mm; The ground calibrated values of those parameters are (u0,v0) =( 512,512) pixel, f = 50mm; Worst case radial distortion coefficient affecting the star camera lens is considered to be k1 =5 x 10−3 .Our proposed method of attitude determination achieves accuracy of the order of magnitude around 6.2288 x 10−5 rad,3.3712 x 10−5 radand5.8205 x
10−5 rad in attitude angles φ,θ and ψ. Attitude estimation by existing methods in the literature diverges from the true value since they utilize the ground calibrated values of camera parameters instead of true values.
To summarize, we developed a formal theory of discrete time Second Order Sliding Mode Observer for uncertain multi-output system. Our methods achieve the desired accuracy while estimating satellite attitude and attitude rate using low fidelity star sensor data. Our methods require lower on-board processing requirement and less memory allocation; thus are suitable for micro-satellite applications. Thus, the objective of using low fidelity star sensor as stand-alone sensor in micro-satellite application is achieved.
48
Pal, Madhumita. "Accurate and Efficient Algorithms for Star Sensor Based Micro-Satellite Attitude and Attitude Rate Estimation." Thesis, 2013. http://etd.iisc.ernet.in/2005/3428.
Full textAbstract:
This dissertation addresses novel techniques in determining gyroless micro-satellite attitude and attitude rate. The main objective of this thesis is to explore the possibility of using commercially available low cost micro-light star sensor as a stand-alone sensor for micro-satellite attitude as well as attitude rate determination. The objective is achieved by developing accurate and computationally efficient algorithms for the realization of onboard operation of a low fidelity star sensor. All the algorithms developed here are tested with the measurement noise presented in the catalog of the sensor array STAR-1000.
A novel accurate second order sliding mode observer (SOSMO) is designed for discrete time uncertain linear multi-output system. Our design procedure is effective for both matched and unmatched bounded uncertain ties and/or disturbances. The bound on uncertainties and/or disturbances is assumed to be unknown. This problem is addressed in this work using the second order multiple sliding modes approach. Second order sliding manifold and corresponding sliding condition for discrete time system is defined similar on the lines of continuous counterpart. Our design is not restricted to a particular class of uncertain (matched) discrete time system. Moreover, it can handle multiple outputs unlike single out-put systems. The observer design is achieved by driving the state observation error and its first order finite difference to the vicinity of the equilibrium point (0,0) in a finite steps and maintaining them in the neighborhood thereafter. The estimation synthesis is based on Quasi Sliding Mode (QSM) design.
The problem of designing sliding mode observer for a linear system subjected to unknown inputs requires observer matching condition. This condition is needed to ensure that the state estimation error is a asymptotically stable and is independent of the unknown input during the sliding motion. In the absence of a matching condition, asymptotic stability of the reduced order error dynamics on the sliding surface is not guaranteed. However, unknown bounded inputs guarantee bounded error on state estimation. The QSM design guarantees an ultimate error bound by incorporating Boundary Layer (BL) in its design procedure.
The observer achieves one order of magnitude improvement in estimation accuracy than the conventional sliding mode observer (SMO) design for an unknown input. The observer estimation errors, satisfying the given stability conditions, converge to an ultimate finite bound (with in the specified BL) of O(T2), where T Is the sampling period. A relation between sliding mode gain and boundary layer is established for the existence of second order discrete sliding motion. The robustness of the proposed observer with respect to measurement noise is also analyzed. The design algorithm is very simple to apply and is implemented for two examples with different classes of disturbances (matched and unmatched) to show the effectiveness of the design. Simulation results show the robustness with respect to the measurement noise for SOSMO.
Second order sliding mode observer gain can be calculated off-line and the same gain can work for large band of disturbance as long as the disturbance acting on the continuous time system is bounded and smooth. The SOSMO is simpler to implement on board compared to the other traditional nonlinear filters like Pseudo-Linear-Kalman-filter(PLKF); Extended Kalman Filter(EKF). Moreover, SMO possesses an automatic adaptation property same as optimal state estimator(like Kalman filter) with respect to the intensity of the measurement noise. The SMO rejects the noisy measurements automatically, in response to the increased noise intensity. The dynamic performance of the observer on the sliding surface can be altered and no knowledge of noise statistics is required. It is shown that the SOSMO performs more accurately than the PLKF in application to micro-satellite angular rate estimation since PLKF is not an optimal filter.
A new method for estimation of satellite angular rates through derivative approach is proposed. The method is based on optic flow of star image patterns formed on a star sensor. The satellite angular rates are derived directly from the 2D-coordinates of star images. Our algorithm is computationally efficient and requires less memory allocation compared to the existing vector derivative approaches, where there is also no need for star identification. The angular rates are computed using least square solution method, based on the measurement equation obtained by optic flow of star images. These estimates are then fed into discrete time second order sliding mode observer (SOSMO). The performance of angular rate estimation by SOSMO is compared with the discrete time First order SMO and PLKF. The SOSMO gives the best estimates as compared to the other two schemes in estimating micro-satellite angular rates in all three axes. The improvement in accuracy is one order of magnitude (around1.7984 x 10−5 rad/ sec,8.9987 x 10−6 rad/ sec and1.4222 x 10−5 rad/ sec in three body axes respectively) in terms of standard deviation in steady state estimation error.
A new method and algorithm is presented to determine star camera parameters along with satellite attitude with high precision even if these parameters change during long on-orbit operation. Star camera parameters and attitude need to be determined independent of each other as they both can change. An efficient, closed form solution method is developed to estimate star camera parameters (like focal length, principal point offset), lens distortions (like radial distortion) and attitude. The method is based on a two step procedure. In the first step, all parameters (except lens distortion) are estimated using a distortion free camera model. In the second step, lens distortion coefficient is estimated by linear least squares (LS) method. Here the derived camera parameters in first step are used in the camera model that incorporates distortion. However, this method requires identification of observed stars with the catalogue stars. But, on-orbit star identification is difficult as it utilizes the values of camera calibrating parameters that can change in orbit(detector and optical element alignment get change in orbit due to solar pressure or sudden temperature change) from the ground calibrated value. This difficulty is overcome by employing a camera self-calibration technique which only requires four observed stars in three consecutive image frames. Star camera parameters along with lens (radial and decentering) distortion coefficients are determined by camera self calibration technique. Finally Kalman filter is used to refine the estimated data obtained from the LS based method to improve the level of accuracy.
We consider the true values of camera parameters as (u0,v0) = (512.75,511.25) pixel, f = 50.5mm; The ground calibrated values of those parameters are (u0,v0) =( 512,512) pixel, f = 50mm; Worst case radial distortion coefficient affecting the star camera lens is considered to be k1 =5 x 10−3 .Our proposed method of attitude determination achieves accuracy of the order of magnitude around 6.2288 x 10−5 rad,3.3712 x 10−5 radand5.8205 x
10−5 rad in attitude angles φ,θ and ψ. Attitude estimation by existing methods in the literature diverges from the true value since they utilize the ground calibrated values of camera parameters instead of true values.
To summarize, we developed a formal theory of discrete time Second Order Sliding Mode Observer for uncertain multi-output system. Our methods achieve the desired accuracy while estimating satellite attitude and attitude rate using low fidelity star sensor data. Our methods require lower on-board processing requirement and less memory allocation; thus are suitable for micro-satellite applications. Thus, the objective of using low fidelity star sensor as stand-alone sensor in micro-satellite application is achieved.
49
Sob, Peter Baonhe. "Modelling stain rate sensitive nanomaterials' mechanical properties: the effects of varying definitions." Thesis, 2016. http://hdl.handle.net/10352/332.
Full textAbstract:
M. Tech. (Mechanical Engineering, Faculty of Engineering and Technology): Vaal University of TechnologyPresently there exist a lot of controversies about the mechanical properties of nanomaterials. Several convincing reasons and justifications have been put forward for the controversies. Some of the reasons are varying processing routes, varying ways of defining equations, varying grain sizes, varying internal constituent structures, varying techniques of imposing strain on the specimen etc. It is therefore necessary for scientists, engineers and technologists to come up with a clearer way of defining and dealing with nanomaterials’ mechanical properties. The parameters of the internal constituent structures of nanomaterials are random in nature with random spatial patterns. So they can best be studied using random processes, specifically as stochastic processes. In this dissertation the tools of stochastic processes have been used as they offer a better approach to understand and analyse random processes. This research adopts the approach of ascertaining the correct mathematical models to be used for experimentation and modelling. After a thorough literature survey it was observed that size and temperature are two important parameters that must be considered in selecting the relevant mathematical definitions for nanomaterials’ mechanical properties. Temperature has a vital role to play during grain refinement since all severe plastic deformation involves thermomechanical processes. The second task performed in this research is to develop the mathematical formulations based on the experimental observation of 2-D grains and 3-D grains deformed by Accumulative Roll-Bonding and Equal Channel Angular Pressing. The experimental observations revealed that grains deformed by Accumulative Roll-Bonding and Equal Channel Angular Pressing are elongated when observed from the rolling direction, and transverse direction, and equiaxed when observed from the normal direction. In this dissertation, the different experimental observations for the grain size variants during grain refinement were established for 2-D and 3-D grains. This led to the development of a stochastic model of grain-elongation for 2-D and 3-D grains. The third task was experimentations and validation of proposed models. Accumulative Roll-Bonding, Equal Channel Angular Pressing and mechanical testing (tensile test) experiments were performed. The effect of size on elongation and material properties were studied to validate the developed models since size has a major effect on material’s properties. The fourth task was obtaining results and discussion of theoretical developed models and experimental results. The following facts were experimentally observed and also revealed by the models. Different approaches of measuring grain size reveal different strains that cannot be directly obtained from plots of the corresponding grain sizes. Grain elongation evolved as small values for larger grains, but became larger for smaller grains. Material properties increased with elongation reaching a maximum and started decreasing as is evident in the Hall-Petch to the Reverse Hall-Petch Relationship. This was alluded to the fact that extreme plastic straining led to distorted structures where grain boundaries and curvatures were in “non-equilibrium” states. Overall, this dissertation contributed new knowledge to the body of knowledge of nanomaterials’ mechanical properties in a number of ways. The major contributions to the body of knowledge by his study can be summarized as follows: (1) The study has contributed in developing a model of elongation for 2-D grain and 3-D grains. It has been generally reported by researchers that materials deformed by Accumulative Roll-Bonding and Equal Channel Angular Pressing are generally elongated but none of these researchers have developed a model of elongation. Elongation revealed more information about “size” during grain refinement. (2) The Transmission Electron Microscopy revealed the grain shape in three directions. The rolling direction or sliding direction, the normal direction and the transverse direction. Most developed models ignored the different approaches of measuring nanomaterials’ mechanical properties. Most existing models dealt only with the equivalent radius measurement during grain refinement. In this dissertation, the different approaches of measuring nanomaterials’ mechanical properties have been considered in the developed models. From this dissertation an accurate correlation can be made from microscopy results and theoretical results. (3) This research has shown that most of the published results on nanomaterials’ mechanical properties may be correct although controversies exist when comparing the different results. This research has also shown that researchers might have considered different approaches to measure nanomaterials’ mechanical properties. The reason for different results is due to different approaches of measuring nanomaterials’ mechanical properties as revealed in this research. Since different approaches of measuring nanomaterials’ mechanical properties led to different obtained results, this justify that most published results of nanomaterials’ mechanical properties may be correct. This dissertation revealed more properties of nanomaterials that are ignored by the models that considered only the equivalent length. (4) This research has contributed to the understanding of nanomaterials controversies when comparing results from different researchers.
50
Campbell, David Riley Mark A. "Angular momentum induced shape changes in the rare-earth nuclei ¹⁵², ¹⁵³Gd and ¹⁵⁹, ¹⁶⁰Yb." 2004. http://etd.lib.fsu.edu/theses/available/etd-06292004-181848.
Full textAbstract:
Thesis (Ph. D.)--Florida State University, 2004.Advisor: Dr. Mark A Riley, Florida State University, College of Arts and Sciences, Dept. of Physics. Title and description from dissertation home page (viewed Sept. 21, 2004). Includes bibliographical references.