Dissertations / Theses on the topic 'Smart structure'
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1
Griffin, Steven F. "Acoustic replication in smart structure using active structural/acoustic control." Diss., Georgia Institute of Technology, 1995. http://hdl.handle.net/1853/13085.
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Iong, Kuoc-Vai. "Smart structure integrity monitoring using transient response." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/mq26332.pdf.
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Nwankwo, Cosmas Chidozie. "Smart offshore structure for reliability prediction process." Thesis, Cranfield University, 2013. http://dspace.lib.cranfield.ac.uk/handle/1826/9335.
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A review of the developments within the field of structural reliability theory shows that
some gaps still exist in the reliability prediction process and hence there is an urgent
desire for improvements such that the estimated structural reliability will be capable of
expressing a physical property of the given structure. The current reliability prediction
process involves the continuous estimation and use of reliability index as a way of
estimating the safety of any given structure. The reliability index β depends on the
Probability Density Function (PDF) distribution for the wave force and the corresponding
PDF of resistance from respective structural members of the given structure. The PDF
for the applied wave force will depend on the PDF of water depth, wave angular velocity
and wave direction hence the reliability index as currently practiced is a statistical way
of managing uncertainties based on a general probabilistic model.
This research on Smart Offshore Structure for Reliability Prediction has proposed the
design of a measurement based reliability prediction process as a way of closing the
gap on structural reliability prediction process. Structural deflection and damping are
some of the measurable properties of an offshore structure and this study aims at
suggesting the use of these measurable properties for improvements in structural
reliability prediction process. A design case study has shown that a typical offshore
structure can deflect to a range of only a few fractions of a millimetre. This implies that if
we have a way of monitoring this level of deflection, we could use the results from such
measurement for the detection of a structural member failure. This advocated concept is
based on the hypothesis that if the original dynamic characteristics of a structure is
known, that measurement based modified dynamic properties can be used to determine
the onset of failure or failure propagation of the given structure.
This technology could reveal the location and magnitude of internal cracks or corrosion
effects on any given structure which currently is outside the current probability based
approach. A simple economic analysis shows that the recommended process shows a
positive net present value and that some $74mln is the Value of Information for any life
extension technology that could reveal the possibility of extending the life of a given
10,000bopd production platform from 2025 to 2028.
4
Won, Chin Chung. "Active control of smart structure : theory and experiment." Diss., Georgia Institute of Technology, 1990. http://hdl.handle.net/1853/12374.
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Nale, Kumar S. "Multiplexed Control of Smart Structure using Piezoelectric Actuators." Cleveland State University / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=csu1231281641.
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Lellis, Leandro. "An organizational structure analysis for BC Hydro, Power Smart /." Burnaby B.C. : Simon Fraser University, 2006. http://ir.lib.sfu.ca/handle/1892/3523.
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Research Project (M.B.A.) - Simon Fraser University, 2006.Theses (Faculty of Business Administration) / Simon Fraser University. MBA-MOT Program. Senior supervisor : Dr. Sudheer Gupta. Also issued in digital format and available on the World Wide Web.
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Al-Baradi, Ateyyah. "Nanoscale structure and single molecule diffusion in smart polymeric systems." Thesis, University of Sheffield, 2012. http://etheses.whiterose.ac.uk/14559/.
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Soft nanotechnology requires the development and understanding of smart polymeric systems that respond to small changes in the surrounding environment. This thesis reports on the structure and dynamics in poly(methacn"lic acid) (PMAA) hydrogels and hyperbranched poly(N-isopropyl acrylamide) (HB-PNIPAM) in response to physical and chemical stimuli. Fluorescence correlation spectroscopy (FCS) has been utilized to study the diffusion of single dextran molecules labelled with fluorescein isothiocyanate within a PMAA hydrogel. Diffusion in pure water shows a temperature dependence described by Zimm dynamics, whereas the diffusion coefficient decreases with temperature in the hydrogel for which a model has been developed. Diffusion in PMAA hydrogel has revealed the mesh size dependence on temperature. The effect of pH and salt on the diffusion in PMAA hydrogel has also been considered. Introducing magnetic nanoparticles to hydrogels forms ferrogels the mesh of which is controlled by applied magnetic fields. The swelling, diffusion and release in PMAA ferro gel has been found to follow the same scaling theory developed in this work. Small angle neutron scattering (SANS) has revealed the structural behaviour of HB-PNIPAM as a function of temperature compared to its linear counterpart. These experiments have shown that water is a good solvent for HB-PNIPAM at low temperatures, while increasing the temperature leads to a gradual collapse of these polymers until they form spherical particles with sharp boundaries of the order of 24-40 nm in diameter, depending on the branching degree. This indicates that HB-PNIPAM shows no entanglements either as a function of temperature or branching degree. In contrast, linear PNIPAM showed a network-like behaviour above its collapsing temperature. Neutron spin echo experiments on HB-PNIPAM are described well by the Rouse model for unentangled chains and the self-diffusion of HB-PNIPAl\I by FCS follows Zimm behaviour, which is in agreement with SANS results. These studies have given a better understanding of the nanostructure and dynamics in the investigated polymeric systems, showing their usefulness as delivery systems for many biological and medical applications.
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Phoenix, Austin Allen. "High Precision Thermal Morphing of the Smart Anisogrid Structure for Space-Based Applications." Diss., Virginia Tech, 2016. http://hdl.handle.net/10919/78824.
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To meet the requirements for the next generation of space missions, a paradigm shift is required from current structures that are static, heavy and stiff, to innovative structures that are adaptive, lightweight, versatile, and intelligent. This work proposes the use of a novel morphing structure, the thermally actuated anisogrid morphing boom, to meet the design requirements by making the primary structure actively adapt to the on-orbit environment. The proposed concept achieves the morphing capability by applying local and global thermal gradients and using the resulting thermal strains to introduce a 6 Degree of Freedom (DOF) morphing control. To address the key technical challenges associated with implementing this concept, the work is broken into four sections. First, the capability to develop and reduce large dynamic models using the Data Based Loewner-SVD method is demonstrated. This reduction method provides the computationally efficient dynamic models required for evaluation of the concept and the assessment of a vast number of loading cases. Secondly, a sensitivity analysis based parameter ranking methodology is developed to define parameter importance. A five parameter model correlation effort is used to demonstrate the ability to simplify complex coupled problems. By reducing the parameters to only the most critical, the resulting morphing optimization computation and engineering time is greatly reduced. The third piece builds the foundation for the thermal morphing anisogrid structure by describing the concept, defining the modeling assumptions, evaluating the design space, and building the performance metrics. The final piece takes the parameter ranking methodology, developed in part two, and the modeling capability of part three, and performs a trust-region optimization to define optimal morphing geometric configuration. The resulting geometry, optimized for minimum morphing capability, is evaluated to determine the morphing workspace, the frequency response capability, and the minimum and maximum morphing capability in 6 DOF. This work has demonstrated the potential and provided the technical tools required to model and optimize this novel smart structural concept for a variety of applications.Ph. D.
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Kakani, Naveen Kumar. "Algorithms for Efficient Utilization of Wireless Bandwidth and to Provide Quality-of-Service in Wireless Networks." Thesis, University of North Texas, 2000. https://digital.library.unt.edu/ark:/67531/metadc2635/.
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This thesis presents algorithms to utilize the wireless bandwidth efficiently and at the same time meet the quality of service (QoS) requirements of the users. In the proposed algorithms we present an adaptive frame structure based upon the airlink frame loss probability and control the admission of call requests into the system based upon the load on the system and the QoS requirements of the incoming call requests. The performance of the proposed algorithms is studied by developing analytical formulations and simulation experiments. Finally we present an admission control algorithm which uses an adaptive delay computation algorithm to compute the queuing delay for each class of traffic and adapts the service rate and the reliability in the estimates based upon the deviation in the expected and obtained performance. We study the performance of the call admission control algorithm by simulation experiments. Simulation results for the adaptive frame structure algorithm show an improvement in the number of users in the system but there is a drop in the system throughput. In spite of the lower throughput the adaptive frame structure algorithm has fewer QoS delay violations. The adaptive call admission control algorithm adapts the call dropping probability of different classes of traffic and optimizes the system performance w.r.t the number of calls dropped and the reliability in meeting the QoS promised when the call is admitted into the system.
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Goulet-Langlois, Gabriel. "Exploring regularity and structure in travel behavior using Smart Card data." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/99546.
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Thesis: S.M. in Transportation, Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2015.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 161-166).
As the economic opportunities fostered by large cities become more diverse, the travel patterns of public transport users become more heterogeneous. From personalized customer information, to improved travel demand models, understanding these heterogeneous travel patterns is useful for a number of applications relevant to public transport agencies. This thesis explores how smart card data can be used to analyze and compare the structure of individual travel patterns observed over several weeks. Specifically, the way in which multiple journeys and activities are ordered and combined into repeated patterns, both by the same individual over time and across individuals is evaluated from the journey sequence of each user. The research is structured around three objectives. First, we introduce a representation of individual travel patterns and develop a measure of travel sequence regularity. The mobility of each individual is modeled as a stochastic process with memory, of which each new realization represents an activity or journey. Entropy rate, a measure of randomness in the stochastic process, is used to quantify repetition in the order of journeys and activities. This analysis reveals that the order of events is an important component of regularity not explicitly captured in previous literature. Second, we develop an approach to identify clusters of travel patterns with similar structure considered with respect to public transport usage and activity patterns. Finally, we present an exploratory evaluation of the associations between the identified clusters and socio-demographic characteristics by linking smart card data to an annual travel diary survey. These three objectives are considered in the context of a practical application using the transactions of a sample of approximately 100,000 users collected between February 10th and March 10th 2015 in London.
by Gabriel Goulet-Langlois.
S.M. in Transportation
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Amer, Motaz. "Power consumption optimization based on controlled demand for smart home structure." Thesis, Aix-Marseille, 2015. http://www.theses.fr/2015AIXM4354.
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Cette thèse propose un concept d'optimisation de la consommation d'énergie dans les maisons intelligentes basées sur la gestion de la demande qui repose sur l'utilisation de système d e gestion de l'énergie à la maison (HEMS) qui est en mesure de contrôler les appareils ménagers. L'avantage de ce concept est l'optimisation de la consommation d'énergie sans réduire les utilisateurs vivant confort. Un mécanisme adaptatif pour une croissance intelligente système de gestion de l'énergie de la maison qui a composé des algorithmes qui régissent l'utilisation des différents types de charges par ordre de priorité pré-sélectionné dans la maison intelligente est proposé. En outre, une méthode pourl'optimisation de la puissance générée à partir d'un hybride de systèmes d'énergie renouvelables (HRES) afin d'obtenir la demande de charge. particules technique d'optimisation essaim (PSO) est utilisé comme l'optimisation algorithme de recherche en raison de ses avantages par rapport à d'autres techniques pour réduire le coût moyen actualisé de l'énergie (LCE) avec une plage acceptable de la production en tenant compte des pertes entre la production et la demande. Le problème est défini et la fonction objective est introduite en tenant compte des valeurs de remise en forme de sensibilité dans le processus d’essaim de particules. La structure de l'algorithme a été construite en utilisant un logiciel MATLAB et Arduino 1.0.5 du logiciel.Ce travail atteint le but de réduire la charge de l'électricité et la coupure du rapport pic-moyenne (PAR)This thesis proposes a concept of power consumption optimization in smart homes based on demand side management that reposes on using Home Energy Management System (HEMS) that is able to control home appliances. The advantage of the concept is optimizing power consumption without reducing the users living comfort. An adaptive mechanism for smart home energy management system which composed of algorithms that govern the use of different types of loads in order of pre-selected priority in smart home is proposed. In addition a method for the optimization of the power generated from a Hybrid Renewable Energy Systems (HRES) in order to achieve the load demand. Particle Swarm Optimization Technique (PSO) is used as optimization searching algorithm due to its advantages over other techniques for reducing the Levelized Cost of Energy (LCE) with an acceptable range of the production taking into consideration the losses between production and demand sides. The problem is defined and the objective function is introduced taking into consideration fitness values sensitivity in particle swarm process. The algorithm structure was built using MATLAB software and Arduino 1.0.5 Software. This work achieves the purpose of reducing electricity expense and clipping the Peak-toAverage Ratio (PAR). The experimental setup for the smart meter implementing HEMS is built relying on the Arduino Mega 2560 board as a main controller and a web application of URL http://www.smarthome-em.com to interface with the proposed smart meter using the Arduino WIFI Shield
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Mereuta, Alina. "Smart web accessibility platform : dichromacy compensation and web page structure improvement." Thesis, Tours, 2014. http://www.theses.fr/2014TOUR4032/document.
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Dans ces travaux, nous nous concentrons sur l’amélioration de l’accessibilité web pourdes utilisateurs handicapés visuels à travers d’outils s’intègrant dans la plateforme SmartWeb Accessibility Platform (SWAP). Après une synthèse sur l’accessibilité, un panoramade SWAP est présenté. Notre première contribution concerne la compensation de la pertede contraste textuel dans les pages web pour les daltoniens tout en maintenant les intentionsde l’auteur retranscrites par les couleurs. Ce problème est modélisé sous la forme d’unproblème de minimisation d’une fonction numérique dépendante des couleurs initiales, desrelations entre les couleurs de la page et des couleurs modifiées. L’intérêt et l’efficacité detrois méthodes d’optimisation (mass-spring system, CMA-ES, API) ont été évaluées surdeux jeux de données (réel, artificiel). Notre deuxième contribution cherche à améliorer lastructure de pages web pour des utilisateurs de lecteurs d’écran afin de compenser la perted’information due à la linéarisation du contenu. Grâce à l’utilisation d’heuristiques et detechnique d’apprentissage, les zones caractéristiques de la page sont identifiées. La pageest complétée en utilisant des liens supplémentaires et les marqueurs ARIA afin de permettreune meilleure identification des zones par les lecteurs d’écran. Nos expérimentationsmontrent l’efficacité de notre propositionThis thesis works are focused on enhancing web accessibility for users with visual disabilities using tools integrated within the SmartWeb Accessibility Platform (SWAP). After a synthesis on accessibility, SWAP is presented. Our first contribution consists in reducing the contrast loss for textual information in web pages for dichromat users while maintaining the author’s intentions conveyed by colors. The contrast compensation problem is reduced at minimizing a fitness function which depends on the original colors and the relationships between them. The interest and efficiency of three methods (mass-spring system, CMA-ES, API) are assessed on two datasets (real and artificial). The second contribution focuses on enhancing web page structure for screen reader users in order to overcome the effect of contents’linearization. Using heuristics and machine learning techniques, the main zones of the page are identified. The page structure can be enhanced using ARIA statements and access links to improve zone identification by screen readers
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Huková, Martina. "Stavebně technologická příprava prodejny Smart Light v Bratislavě." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2019. http://www.nusl.cz/ntk/nusl-392005.
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The main subject of this diploma thesis is elaboration of construction and technological preparation for the main structure of the Smart Light shop in Bratislava. For main structure has been processed time schedule of the construction, single item budget, machine configuration design, drawing of building site, coordination situation of the building with connection to the infrastructure, safety and health protection during work on building site. Part of the thesis is processing study of main construction technological parts. Diploma thesis in technological prescript focuses on implementation of floor structure with cast epoxy walking surface. There has been elaborated testing and quality plan of this technological part. Additional chapter approximates built-in technology – cooling ceiling structure. For elaboration of this diploma thesis were used programs AutoCAD, CONTEC, BuildPowerS, Microsoft Excel, Microsoft Word.
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Sousa, Margarida Bucho Nunes de. "Smart macroporous structures for the purification of viral particles." Master's thesis, Faculdade de Ciências e Tecnologia, 2014. http://hdl.handle.net/10362/12179.
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Dissertação para obtenção do Grau de Mestre em
Engenharia Química e BioquímicaThe increasing application of viral particles in vaccination and gene-based therapies, has led to the development of alternative and improved purification processes. Traditional purification methods include chromatographic techniques, however the chromatographic matrices used present limitations specially when aimed at the purification of large molecules. This work presents the preparation of chitosan-based monoliths using clean processes and easy functionalization techniques intending to improve Adenovirus serotype 5 (Ad5) purification. Monoliths were prepared by blending chitosan (CHT) with glycidylmethacrylate (GMA) or poly(vinyl alcohol) (PVA), using two preparation techniques, freeze-drying and a scCO2 – assisted drying process, and were subsequently functionalized with Q ligands by three different methods. In addition, monoliths blended with magnetic nanoparticles were also prepared using the same strategies to confer them a controlled magnetic response. The monoliths produced were characterized in terms of ligand immobilization yield, and evaluated for Ad5 purification. Two types of monoliths showed potential: the CHT/PVA(50:50) prepared by freeze drying and functionalized by the alternative plasma technique (M2) and the CHT/PVA(50:50) 7% monolith prepared by scCO2 – assisted drying process and functionalized by the epoxyactivation technique (M1). The amount of ligand Q immobilized on the supports was monitored by titration assays, among which the CHT/PVA(50:50) 7% M2 prepared by scCO2 – assisted drying process exhibited the highest immobilization yield (91%). Among the results for Ad5 purification, the CHT/PVA(50:50)M2 and the CHT/PVA(50:50)7% M1 resulted in a 40% and 14% of the viral particles, respectively. Protein-binding assays were conducted using bovine serum albumin (BSA) and lysozyme, to evaluate the anionic-exchange capacity of the supports. The results make us believe in the potential of the produced monoliths to be applied in chromatographic techniques. However further improvements are necessary to enhance virus binding and recovery, to obtain an improved purification process.
project PTDC/EBB-BIO/118317/2010
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Chee, Clinton Yat Kuan. "STATIC SHAPE CONTROL OF LAMINATED COMPOSITE PLATE SMART STRUCTURE USING PIEZOELECTRIC ACTUATORS �." University of Sydney. Aeronautical Engineering, 2000. http://hdl.handle.net/2123/709.
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The application of static shape control was investigated in this thesis particularly for a composite plate configuration using piezoelectric actuators. A new electro-mechanically coupled mathematical model was developed for the analysis and is based on a third order displacement field coupled with a layerwise electric potential concept. This formulation, TODL, is then implemented into a finite element program. The mathematical model represents an improvement over existing formulations used to model intelligent structures using piezoelectric materials as actuators and sensors. The reason is TODL does not only account for the electro-mechanical coupling within the adaptive material, it also accounts for the full structural coupling in the entire structure due to the piezoelectric material being attached to the host structure. The other significant improvement of TODL is that it is applicable to structures which are relatively thick whereas existing models are based on thin beam / plate theories. Consequently, transverse shearing effects are automatically accounted for in TODL and unlike first order shear deformation theories, shear correction factors are not required. The second major section of this thesis uses the TODL formulation in static shape control. Shape control is defined here as the determination of shape control parameters, including actuation voltage and actuator orientation configuration, such that the structure that is activated using these parameters will conform as close as possible to the desired shape. Several shape control strategies and consequently algorithms were developed here. Initial investigations in shape control has revealed many interesting issues which have been used in later investigations to improve shape controllability and also led to the development of improved algorithms. For instance, the use of discrete actuator patches has led to greater shape controllability and the use of slopes and curvatures as additional control criteria have resulted in significant reduction in internal stresses. The significance of optimizing actuator orientation and its relation to piezoelectric anisotropy in improving shape controllability has also been presented. Thus the major facets of shape control has been brought together and the algorithms developed here represent a comprehensive strategy to perform static shape control.
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BATOR, CHRISTOFFER, and RICKARD SVENSSON. "Exoskeleton arm : How to construct a smart support structure for an arm." Thesis, KTH, Mekatronik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-190843.
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The purpose of this thesis was to find an optimal way to construct and control a product that could help those who suffer from muscle weakness or a muscle sickness. The device was made out of two major parts (upper arm and lower arm) which were connected through a motorized joint. The focus was on finding a satisfying construction that could handle the forces and with the help of sensors measure movement of the users arm relative to the construction and then control it using that information. The device needed to be fast and reliable and react to small movements to be as comfortable for the user as possible. The result was a construction controlled by measuring the forces from the user’s movement with the use of force sensors placed at the wrist. The construction managed to follow the users’ arm, fast and in a satisfactory way.Tanken med detta arbete var att hitta ett optimalt sätt att konstruera en produkt som skulle hjälpa de som lider av muskel -svaghet och -sjukdom. Produkten skulle bestå av två större delar (överarmen och underarmen) som var sammanlänkade med en motoriserad led. Fokusen låg på att hitta en tillfredställande konstruktion som kunde hantera krafterna och med hjälp av sensorer kunna mäta avståndet och rörelsen på användarens arm och förflytta konstruktionen utifrån det. Produkten behövde vara snabb, pålitlig och reagera på små rörelser för att vara så bekväm för användaren som möjligt. Resultatet blev en konstruktion som styrs genom att mäta tryckkraften, när användaren flyttar armen, med hjälp av trycksensorer som placeras vid handleden. Konstruktionen lyckades följa användarens arm, snabbt och på ett tillfredställande sätt.
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Kim, JungMi. "System Identification of Smart Structures Using a Nonlinear WARMA Model." Digital WPI, 2013. https://digitalcommons.wpi.edu/etd-theses/7.
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System identification (SI) for constructed structural systems has received a lot of attention with the continuous development of modern technologies. This thesis proposes a new nonlinear time series model for use in system identification (SI) of smart structures. The proposed model is implemented by the integration of a wavelet transform (WT) and nonlinear autoregressive moving average (NARMA) time series model. The approach demonstrates the efficient and accurate nonlinear SI of smart structures subjected to both ambient excitation and high impact load. To demonstrate the effectiveness of the wavelet-based NARMA modeling (WNARMA), smart structures equipped with magnetorheological (MR) dampers are investigated. The simulation results show that the computation of the WNARMA model is faster than that of the NARMA model without sacrificing the modeling accuracy. In addition, the WNARMA model is robust against noise in the data since it inherently has a denoising capacity.
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Lee, Seung Joon. "Nonlinear analysis of smart composite plate and shell structures." Diss., Texas A&M University, 2003. http://hdl.handle.net/1969.1/2218.
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Theoretical formulations, analytical solutions, and finite element solutions for laminated composite plate and shell structures with smart material laminae are presented in the study. A unified third-order shear deformation theory is formulated and used to study vibration/deflection suppression characteristics of plate and shell structures. The von K??rm??n type geometric nonlinearity is included in the formulation. Third-order shear deformation theory based on Donnell and Sanders nonlinear shell theories is chosen for the shell formulation. The smart material used in this study to achieve damping of transverse deflection is the Terfenol-D magnetostrictive material. A negative velocity feedback control is used to control the structural system with the constant control gain. The Navier solutions of laminated composite plates and shells of rectangular planeform are obtained for the simply supported boundary conditions using the linear theories. Displacement finite element models that account for the geometric nonlinearity and dynamic response are developed. The conforming element which has eight degrees of freedom per node is used to develop the finite element model. Newmark's time integration scheme is used to reduce the ordinary differential equations in time to algebraic equations. Newton-Raphson iteration scheme is used to solve the resulting nonlinear finite element equations. A number of parametric studies are carried out to understand the damping characteristics of laminated composites with embedded smart material layers.
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Chee, Clinton Yat Kuan. "STATIC SHAPE CONTROL OF LAMINATED COMPOSITE PLATE SMART STRUCTURE USING PIEZOELECTRIC ACTUATORS ©." Thesis, The University of Sydney, 2000. http://hdl.handle.net/2123/709.
Full textAbstract:
The application of static shape control was investigated in this thesis particularly for a composite plate configuration using piezoelectric actuators. A new electro-mechanically coupled mathematical model was developed for the analysis and is based on a third order displacement field coupled with a layerwise electric potential concept. This formulation, TODL, is then implemented into a finite element program. The mathematical model represents an improvement over existing formulations used to model intelligent structures using piezoelectric materials as actuators and sensors. The reason is TODL does not only account for the electro-mechanical coupling within the adaptive material, it also accounts for the full structural coupling in the entire structure due to the piezoelectric material being attached to the host structure. The other significant improvement of TODL is that it is applicable to structures which are relatively thick whereas existing models are based on thin beam / plate theories. Consequently, transverse shearing effects are automatically accounted for in TODL and unlike first order shear deformation theories, shear correction factors are not required. The second major section of this thesis uses the TODL formulation in static shape control. Shape control is defined here as the determination of shape control parameters, including actuation voltage and actuator orientation configuration, such that the structure that is activated using these parameters will conform as close as possible to the desired shape. Several shape control strategies and consequently algorithms were developed here. Initial investigations in shape control has revealed many interesting issues which have been used in later investigations to improve shape controllability and also led to the development of improved algorithms. For instance, the use of discrete actuator patches has led to greater shape controllability and the use of slopes and curvatures as additional control criteria have resulted in significant reduction in internal stresses. The significance of optimizing actuator orientation and its relation to piezoelectric anisotropy in improving shape controllability has also been presented. Thus the major facets of shape control has been brought together and the algorithms developed here represent a comprehensive strategy to perform static shape control.
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Bhatnagar, Mohit. "Multiplexing of interferometric fiber optic sensors for smart structure applications using spread spectrum techniques." Thesis, This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-12052009-020246/.
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Ciminello, Monica. "Semi-passive control strategy using piezo ceramic patches in non linear commutation architecture for structural-accoustice smart systems." Paris, CNAM, 2010. http://www.theses.fr/2010CNAM0668.
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De nombreuses recherches sont aujourd’hui consacrées à l’étude et au développement de stratégies de réduction du bruit et des vibrations. Dans le domaine de l’acoustique comme dans le domaine des vibrations, différentes approches peuvent être envisagées. Une tendance actuelle est d’appliquer des techniques actives qui sont reconnues pour être efficaces sur une large bade de fréquence, mais qui souffrent cependant d’une complexité de mise en oeuvre et d’une nécessité d’un apport d’énergie extérieur qui rendent ces systèmes peu robustes et potentiellement instables. Les techniques passives, qui utilisent par exemple des matériaux isolants, sont quand à elles très efficaces pour les hautes fréquences mais plus limitées en basse fréquence pour un problème de poids et d’encombrement, ce qui peut être un inconvénient dans certaines applications aéronautiques ou aérospatiales où la légèreté est un paramètre primordial. Afin de diminuer le bruit engendré par les vibrations des structures, il est possible d’adopter une approche différente basée sur l’utilisation de systèmes semi-passifs. Cette technique, qui sera utilisée dans ce travail, est réalisée grâce des éléments piézo-céramiques collés à la structure et connectés à un circuit électrique de type shunt résonant avec un interrupteur (switch shunt). L’interrupteur permet d’ouvrir et de fermer le circuit électrique à des moments bien précis de façon à maximiser l’atténuation des vibrations. Par rapport aux systèmes actifs, ce type d’approche est relativement simple à mettre en oeuvre, robuste et stable. De plus, par rapport aux techniques piézoélectriques purement passives, il n’est pas nécessaire de fournir de l’énergie extérieur au système ni d’accorder précisément les composants électrique pour garder une efficacité sur une bande de fréquence relativement large. L’objectif du travail est double. Il s’agit de développer un outil de calcul par éléments finis (basé sur les logiciels Matlab et Nastran) pour simuler la réponse dynamique de système couplés élasto-acoustiques amortis grâce à l’utilisation de pastilles piézoélectriques connectées à un circuit de type shunt avec interrupteur. De plus, des expérimentations sont réalisées de façon à tester un dispositif piézoélectrique original et valider certains développements numériques. Concernant l’expérimentation, une approche originale basée sur l’utilisation d’un tachymètre et de circuits intégrés CMOS (nécessitant une alimentation de 12 V) a été développée. Une adaptation est également proposée pour l’utilisation simultanée de plusieurs patches piézoélectriques. Une modélisation éléments finis d’une structure élastique couplée à une cavité acoustique est tout d’abord réalisée. Les matrices globales des parties fluide, structure et couplage fluidestructure sont extraites du code de calcul Nastran et sont réassemblées dans Matlab selon la formulation classique non symétrique en termes de déplacement de la structure et de pression dans le fluide. Ensuite, la matrice de couplage électro-mécanique est ajoutée pour prendre en compte les effets piézoélectriques. Enfin, le comportement du circuit résonnant avec interrupteur est modélisé et simulé. Etant donné les temps de commutation très courts, une approche temporelle directe (basée sur le shéma de Newmark) a été utilisée de façon à calculer la réponse transitoire du système coupléAmong the different strategies oriented to the noise and vibration control, due to their promising properties in terms of limited required power supply, broad band and no tuneable nature, semi-active switched shunt architectures have well done for themselves. The idea of using piezo transducers to convert mechanical into electrical energy and elaborating related signal within an external time variant electrical circuit, represents the inspiring principle of this type of control. A wide amount of efforts has been spent on the semi-active switched shunt control with specific interest in the “synchronised” one; theoretical, numerical, experimental investigations, proved in different ways pros and cons of applications generally confined to the vibration field, in the low frequency band. Also the idea of extending this control to acoustics has been taken into account: problems like the structure-borne sound have been dealt with, implementing switch logic onto piezo networks mounted on structural components. An interesting industrial application in the field of aeronautics and automotive in general, is the interior sound level reduction: in this case a distribution of piezoelectric transducers suitably collocated may lead to remarkable effects, without excessive power consumption. In the present work, a semi analytic approach aimed at estimating the effects on the reduction of pressure sound level by synchronised switched shunt logic, is described. The displacement field within a 1D longitudinal air column through a Fourier series ;expansion has been formalised by assigning a sinusoidal perturbation and fluid–structure interface condition on the left and right boundaries, respectively. At first, a validation procedure has been implemented: both the convergence of the series coefficients and the satisfaction of boundary and initial conditions have been verified. To simulate the no control operative condition, the solution has been computed for the entire time domain, keeping invariant all circuitry properties; then for the switch working modality, solution has been computed by splitting the entire time domain into partitions, each one delimited by the instants at which the circuit is switched on (i. E. , by maxima and minima of the displacement on the right boundary domain); for any partition, specific circuitry properties (e. G. Piezo voltage, electrical field…) have been selected. Based on displacement information, related sound pressure level has been compared for no controlled and controlled operative conditions, with and without signal amplification
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Bîlteanu, Liviu. "Atomic scale simulation of hydrogen related defects in hydrogen implanted silicon - Smart Cut™ technology." Paris 11, 2010. http://www.theses.fr/2010PA112293.
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Le sujet de cette thèse est lié à l'étape d'implantation de la technologie Smart Cut™. Cette technologie utilise l'hydrogène pour transférer des couches de silicium sur des substrats isolants. Le transfert se fait par une fracture induite par la formation des défauts bidimensionnels appelés dans la littérature des plaquettes (en anglais « platelets »). Plus précisément, nous avons étudié dans le cadre de cette thèse les défauts qui apparaissent dans l'état post implantation et leur évolution de l'endommagement d'implantation vers l'état qui contient des plaquettes. L'étude est organisée en deux parties : une première partie qui contient les résultats obtenus par simulation atomistique et une deuxième partie qui contient l'étude par spectroscopie infrarouge de l'évolution des concentrations des défauts suites à des recuits à différentes températures. Les simulations atomistiques ont été effectuées dans le cadre de la théorie de la fonctionnelle densité et ont permis de calculer des énergies de formation et de migration/recombinaisons. Les défauts étudiés sont les interstitiels d'hydrogène atomique et moléculaire, des lacunes et multi-lacunes hydrogénées et finalement des différents modèles de plaquettes. Ces énergies ont permis réaliser un schéma hiérarchique de stabilité des défauts. Ce schéma a été confronté avec des analyses infrarouge sur des échantillons de silicium implanté par hydrogène (à 37 keV) dans le régime dit de «sous-dose» qui ne permets habituellement la formation immédiate des plaquettes lors de l'étape de l'implantation. Ces analyses ont permis de discriminer des évolutions des concentrations de défauts déduites des comportements lors des recuits des pics correspondants aux défauts. La comparaison entre ces évolutions et le schéma énergétique a permis de valider un scénario d'évolution des défauts vers l'état plaquetteThe topic of this thesis is related to the implantation step of the Smart Cut™ technology. This technology uses hydrogen in order to transfer silicon layers on insulating substrates. The transfer is performed through a fracture induced by the formation of bidimensional defects well known in Iiterature as "platelets". More exactly, we have studied within this thesis work the defects appearing in the post implant state and the evolution of the implantation damage towards a state dominated by platelets. The study is organised into two parts: in the first part we present the results obtained by atomic scale simulations while the second part we present an infrared spectroscopy study of the evolution of defects concentrations after annealing at different temperatures. The atomic scale simulations have been performed within the density functional theory and they allowed us to compute the formation energies and the migration and recombination barriers. The defects included in our study are: the atomic and diatomic interstitials, the hydrogenated vacancies and multivacancies and the several platelets models. The obtained energies allowed us to build a stability hierarchy for these types of defects. This scheme has been confronted with some infrared analysis on hydrogen implanted silicon samples (37 keV) in a sub-dose regime which does not allow usually the formation of platelets during the implantation step. The analysis of the infrared data allowed the detailed description of the defects concentration based on the behaviour of peaks corresponding to the respective defects during annealing. The comparison between these evolutions and the energy scheme obtained previously allowed the validation of an evolution scenario of defects towards the platelet state
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Fannin, Christopher A. "Design of an Analog Adaptive Piezoelectric Sensoriactuator." Thesis, Virginia Tech, 1997. http://hdl.handle.net/10919/37020.
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In order for a piezoelectric transducer to be used as a
sensor and actuator simultaneously, a direct charge due to
the applied voltage must be removed from the total response
in order to allow observation of the mechanical response
alone. Earlier researchers proposed electronic
compensators to remove this term by creating a reference
signal which destructively interferes with the direct
piezoelectric charge output, leaving only the charge
related to the mechanical response signal. This research
presents alternative analog LMS adaptive filtering methods
which accomplish the same result. The main advantage of
the proposed analog compensation scheme is its ability to
more closely match the order of the adaptive filter to the
assumed dynamics of the piezostructure using an adaptive
first-order high-pass filter. Theoretical and experimental
results are provided along with a discussion of the
difficulties encountered in trying to achieve perfect
compensation of the feedthrough capacitive charge on a
piezoelectric wafer.Master of Science
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Bucciarelli, Stefano. "Un compilatore per un linguaggio per smart contract intrinsecamente tipato." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amslaurea.unibo.it/19573/.
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Backe, Carin. "Enhancing textile electrode performance : Regulating moisture management through textile structure." Thesis, Högskolan i Borås, Akademin för textil, teknik och ekonomi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-12389.
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The medical field has been a part of the smart textile area for quite some time. With time come technological advancement and the two fields converge on more and more areas. One such area is that of using textile electrodes, textrodes, for measuring bioelectrical activity, such as heart rate for ECG analysis. There are many components that make for a successful textile electrode and though many studies have been made in the subject there are several aspects that still are difficult. By using textile electrodes the problem with skin irritation from electrolyte gels, commonly used for conventional electrodes, is avoided, however dry textrodes create disturbances in the output signal (heart rate) while subjected to movement and internal dimensional changes. The addition of moisture to a textrode has shown to decrease these intermittent disturbances but the knowledge about fundamental textile structural influence in the matter has not been fully investigated. This study investigates a flat, a 2-thread fleece and an open structure, and their relation to moisture both as textile structures and as textrodes. This way the possibilities of utilising moisture to increase performance in a textrode purpose can be examined and to what extent the textile structure plays a part in that exploitation. The material composition of textile structures also affects their properties The introduction of assistive materials, polyester and viscose, into the Shieldex (conductive yarn) structures is done to test core moisture management properties such as surface tension, absorption and moisture content, and correlate them to electrical properties necessary for textrode function. In the end the gap between textile structure and end product in form of a textrode is closed as the impedance and microclimate of the textrodes are studied. This is mainly to tie together the fundamental textile structures with a complex textile construction. In conclusion the complexity is also confirmed as structural, materialistic and external influences has an impact on the results. The influence of moisture on lowered resistance and impedance in the structures is confirmed but the impact of textile structure can also be seen. The 2-thread fleece and open structures often has a more positive impact on results and therefore has the possibility of enhancing performance of a textrode for bioelectrical signal monitoring. With these results a more effective way of producing long-lasting, patient-friendly, textrodes can be derived and in the future lead to better care in the medical areas.
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Larson, John P. "Design of a Magnetostrictive-Hydraulic Actuator Considering Nonlinear System Dynamics and Fluid-Structure Coupling." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1402566309.
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Lefort, Antoine. "A smart grid ready building energy management system based on a hierarchical model predictive control." Thesis, Supélec, 2014. http://www.theses.fr/2014SUPL0010/document.
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L’intégration des énergies renouvelables produites par un bâtiment et les réseaux de fourniture, qui sont amenés à proposer des tarifications et des puissances disponibles variables au cours de la journée, entraînent une grande variabilité de la disponibilité de l’énergie. Mais les besoins des utilisateurs ne sont pas forcément en accord avec cette disponibilité. La gestion de l’énergie consiste alors à faire en sorte que les moments de consommation des installations coïncident avec les moments où celle-ci est disponible. Notre objectif a été de proposer une stratégie de commande prédictive, distribuée et hiérarchisée, pour gérer efficacement l’énergie de l’habitat. Les aspects prédictifs de notre approche permettent d’anticiper les besoins et les variations de la tarification énergétique. L’aspect distribué va permettre d’assurer la modularité de la structure de commande, pour pouvoir intégrer différents usages et différentes technologies de manière simple et sans faire exploser la combinatoire du problème d’optimisation résultantElectrical system is under a hard constraint: production and consumption must be equal. The production has to integrate non-controllable energy resources and to consider variability of local productions. While buildings are one of the most important energy consumers, the emergence of information and communication technologies (ICT) in the building integrates them in smart-grid as important consumer-actor players. Indeed, they have at their disposal various storage capacities: thermal storage, hot-water tank and also electrical battery. In our work we develop an hierarchical and distributed Building Energy Management Systems based on model predictive control in order to enable to shift, to reduce or even to store energy according to grid informations. The anticipation enables to plan the energy consumption in order to optimize the operating cost values, while the hierarchical architecture enables to treat the high resolution problem complexity and the distributed aspect enables to ensure the control modularity bringing adaptability to the controller
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Eden, Derek. "Forces and Pressures on Core-Loc Armour Units in Rubble Mound Breakwaters Measured via Instrumented “Smart-Units”." Thesis, Université d'Ottawa / University of Ottawa, 2019. http://hdl.handle.net/10393/39058.
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Today, more than forty percent of the world’s population lives within 100 kilometers of a coastal area, and population densities are only increasing. In recent years, extreme conditions have resulted in several failures of coastal protection structures around the world. During these failure events, the incurred cost of damages and loss of life has been nearly immeasurable.
Rubble mound breakwaters have been used for millennia, and are critical even today for the protection of coastal areas. In the last several decades, the popularity of using concrete armour units in place of natural rock has risen greatly. However, the quantitative interaction between wave hydrodynamics and the armour layer is still not clearly understood. Due to highly complex, turbulent flow patterns that occur in the armour layer, direct assessment of forces acting on individual units has not been practical. This has prevented the coastal engineering field from applying a force-balance design approach that is commonplace in other civil engineering disciplines. Instead, a wealth of experimental testing and past case studies have resulted in a wide array of empirical formulae and design techniques. These approaches are often very idealized and do not account for all parameters that have been shown to affect armour unit stability.
The current study aims to quantify the forces and pressures acting on units within an armour layer, using an experimental approach. This was achieved by developing an instrumented Core-Loc armour unit. This armour unit was outfitted with 6 pressure sensors, and the ability to be mounted on a force transducer. This unit was then put through a performance analysis and calibration procedure, before being extensively tested in a breakwater setting. Wide ranges of wave conditions were utilized, with the unit at three different locations along the breakwater slope. This was done to isolate both the effect of various sea state parameters, and the effect of unit location along a breakwater slope versus generated forces and pressures. In addition to the experimental study, an accompanying numerical study was performed in OpenFOAM. This had the intent of both developing general modeling rules of thumb for rubble mound breakwaters, and for replicating the experimental results.
The results showed that using relatively low-tech, low-cost, and widely available instrumentation was capable of performing in a coastal engineering setting. The performance of the unit showed great promise for “smart-units” to usher in a new paradigm of experimental testing for rubble mound breakwaters. From the results of the performance analysis and calibration procedure, it was evident that the unit could record forces and pressures to a high degree of accuracy. From the breakwater testing program, notable relationships between unit location, surf similarity, and wave steepness emerged. It appeared that the largest hydrodynamic interaction with units occurs slightly below the SWL. As well, both decreased surf similarity, and increased wave steepness resulted in higher hydrodynamic interaction for all locations. General rules of thumb for modeling armour units, as well as wave conditions in a breakwater setting were developed for the numerical study in OpenFOAM. Additionally, the calibrated numerical model was capable of reproducing the experimental results with reasonable accuracy.
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Amanda, Tannor Ophelia. "Hearing aid combined with virtual reality function." Thesis, Boston, USA, 2020. http://openarchive.nure.ua/handle/document/11840.
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In this paper the structure scheme of a smart hearing aid with augmented reality was proposed. This scheme consists of 6 blocks: sensor (microphone), ADC, microprocessor or microcontroller, battery, Bluetooth module, speaker. Such a device should not only improve hearing but also increase the psychological confidence of a person. The next stage of work is the development of an electrical circuit diagram of the device and the assembly of the prototype
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Poumeyrol, Thierry. "Étude du mécanisme de transfert dans le procédé Smart-Cut : application à l'élaboration d'une structure SOI (unibond)." Grenoble INPG, 1996. http://www.theses.fr/1996INPG0121.
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Le mecanisme de transfert dans le procede smart-cut a ete etudie. L'elaboration par le procede smart-cut d'une structure soi, nommee unibond, a ete apprehendee. Le procede smart-cut fait appel a l'implantation d'hydrogene et des traitements thermiques post-implantation. Au niveau microscopique, cette etude a mis en evidence les defauts responsables de la fracture dans le silicium. L'evolution de ces microcavites ou microfissures au cours du recuit de transfert a ete quantifiee. La coalescence de ces microcavites a ete explicitee par le mecanisme d'ostwald ripening. Au niveau macroscopique, les effets de l'application, par collage direct, d'une plaque de silicium sur la plaque implantee ont ete etudies. L'influence de la repartition d'hydrogene implante dans le silicium a ete apprehendee. Les energies d'activation du procede ont ete determinees. Le mecanisme de diffusion de l'hydrogene implante a ete mis en evidence. Enfin, le materiau soi-unibond a ete caracterise et presente un interet majeur pour l'industrie ulsi
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Vann, James Linwood. "Institutional Dimensions of the Government's "Smart Buyer" Problem: Pillars, Carriers, and Organizational Structure in Federal Acquisition Management." Diss., Virginia Tech, 2011. http://hdl.handle.net/10919/26410.
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This study applies a theoretical framework from institutional organization theory (Scott, 2001) to examine the problem of managing government contracting, conceptualized as the "smart buyer problem" by Kettl (1993). Kettl argued that, while embracing the market-based promises of contracting, governments have failed to develop the capacity to address even the most fundamental contracting questions, such as what to buy, who to buy from and what was bought? He suggests that the problem is partly attributable to bureaucratic barriers to information sharing in government agencies that prevent them from becoming learning organizations. This study explores the proposition that institutional characteristics within acquisition organizations may contribute to this problem. Governments do not behave as a single buyer with clearly defined buying objectives. Multiple organizations, each shaped by institutional factors, lay claim to processes relating to Kettl's smart buyer questions. As key organizational participants become aligned with their own regulative, normative, and socio-cognitive institutional "pillars," smart buying behavior may become confounded by institutional factors and constraining organizational structures. For this study, an organizational field consisting of the program office, contracting office, and budget office was selected as the level of analysis. A qualitative multi-approach methodology was developed to analyze data from public sources, including government policy documents, audit reports, and other published information related to five individual cases. Data from autoethnographic accounts, interviews, content analyses, and the case studies helped frame the institutional characteristics of these offices. The study confirmed that the three offices are key participants in acquisition programs, although their roles are not always formally recognized. Strong evidence was found that they each possess unique institutional characteristics. These differences could be creating conditions of divergence and misalignment with the acquisition objectives, raising the possibility of conflicting institutional demands, competing challenges for legitimacy, and institutional change. Policy initiatives to formally recognize the roles and responsibilities of these offices and the use of working-level oversight boards, project teams, and interagency contracting may help mitigate these institutional differences. The study points to the importance of recognizing participants' institutional characteristics when planning and managing an acquisition program.Ph. D.
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CAPOVILLA, GIORGIO. "Development of next generation multifunctional composite structures for CubeSats, pico- and nanosatellites." Doctoral thesis, Politecnico di Torino, 2022. http://hdl.handle.net/11583/2971315.
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Wennberg, Simon. "Optimal nätdesign : Utvärdering och jämförelse av nätstrukturer i Stockholms mellanspänningsnät." Thesis, Uppsala universitet, Elektricitetslära, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-321898.
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In today’s society the electric grid has become one of the most important infrastructures and industries as well as other infrastructures, and individuals rely on its functionality. The unavailability of electricity caused by outages is increasingly rare but when it occurs it can have serious consequences. An electric grid’s reliability is now a requirement, not only from customers but also from the regulatory authority.The electric grid in Stockholm is owned and operated by Ellevio AB. Over the past decade the reliability, measured in SAIDI (System Average Interruption Duration Index), in the area has deterioated, mainly due to failures of the medium voltage grid (11- kV, MV). The network structure on the MV- grid consists primarily of two parallel medium voltage cables each of which acts redundantly to its pair cable. The technique, called dual cable structure, works most optimally with substations with automatic switching, which automaticly switch over to the redundant cable when failure occurs. However substations without this automatic switching are widely used resulting in a longer interruption time. Another network structure is the ring or loop structure, which still has redundancy, but when failure occurs a load- break switch must close so that the grid can be fed from another direction. The substation in the loop structure can also be remotely controlled, making the load-break swith operable from the control center, resulting in a shorter interruption time.This thesis evaluates and compares different network structures consisting of dual cable with automatic switching and loop structure with remotely controlled substations, based on economy and reliability, on Stora Essingen. The two structures have been designed in the network information system program Trimble NIS and divided into two different environments; one developed and one undeveloped environment. The results show that the technical solutions in network structures of MV- grid do not necessarily mean major differences in economy nor reliability, rather the choice between few but long interruptions and many but short interruptions is central. Results show however that a combination of the dual cable structure with remotely controlled substations in the undeveloped environment is economically motivated while the reliability can be maintained at the same tame.
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Masilela, Mbonisi. "Supporting Data-Intensive Wireless Sensor Applications using Smart Data Fragmentation and Buffer Management." VCU Scholars Compass, 2007. http://scholarscompass.vcu.edu/etd/779.
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Recent advances in low power device technology have led to the development of smaller powerful sensors geared for use in Wireless Sensor Networks. Some of these sensors are capable of producing large data packets in a single reading. This becomes a challenging problem given the constraints imposed by current MAC and Transport Layer implementations since a single data packet can exceed the MTU of the protocol stack. Little has been done in the way of addressing this issue in Wireless Sensor Networks. This paper proposes a novel solution to this issue. Proposed is a Lightweight Data Transportation Protocol that uses smart data fragmentation and efficient pipelined transmission and buffer management schemes to solve this problem. The methodology outlined in this paper ensures that data is successfully transmitted from source to destination with minimal delay or packet loss.
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Di, Prima Matthew Allen. "Thermo-mechanical and micro-structural characterization of shape memory polymer foams." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/28178.
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Thesis (M. S.)--Materials Science and Engineering, Georgia Institute of Technology, 2009.Committee Chair: Gall, Ken; Committee Co-Chair: McDowell, David; Committee Member: Guldberg, Robert; Committee Member: Sanderson, Terry; Committee Member: Shofner, Meisha; Committee Member: Tannenbaum, Rina.
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Ferhat, Ipar. "Development and Application of Modern Optimal Controllers for a Membrane Structure Using Vector Second Order Form." Diss., Virginia Tech, 2015. http://hdl.handle.net/10919/53513.
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With increasing advancement in material science and computational power of current computers that allows us to analyze high dimensional systems, very light and large structures are being designed and built for aerospace applications. One example is a reflector of a space telescope that is made of membrane structures. These reflectors are light and foldable which makes the shipment easy and cheaper unlike traditional reflectors made of glass or other heavy materials. However, one of the disadvantages of membranes is that they are very sensitive to external changes, such as thermal load or maneuvering of the space telescope. These effects create vibrations that dramatically affect the performance of the reflector.
To overcome vibrations in membranes, in this work, piezoelectric actuators are used to develop distributed controllers for membranes. These actuators generate bending effects to suppress the vibration. The actuators attached to a membrane are relatively thick which makes the system heterogeneous; thus, an analytical solution cannot be obtained to solve the partial differential equation of the system. Therefore, the Finite Element Model is applied to obtain an approximate solution for the membrane actuator system.
Another difficulty that arises with very flexible large structures is the dimension of the discretized system. To obtain an accurate result, the system needs to be discretized using smaller segments which makes the dimension of the system very high. This issue will persist as long as the improving technology will allow increasingly complex and large systems to be designed and built. To deal with this difficulty, the analysis of the system and controller development to suppress the vibration are carried out using vector second order form as an alternative to vector first order form. In vector second order form, the number of equations that need to be solved are half of the number equations in vector first order form.
Analyzing the system for control characteristics such as stability, controllability and observability is a key step that needs to be carried out before developing a controller. This analysis determines what kind of system is being modeled and the appropriate approach for controller development. Therefore, accuracy of the system analysis is very crucial. The results of the system analysis using vector second order form and vector first order form show the computational advantages of using vector second order form.
Using similar concepts, LQR and LQG controllers, that are developed to suppress the vibration, are derived using vector second order form. To develop a controller using vector second order form, two different approaches are used. One is reducing the size of the Algebraic Riccati Equation to half by partitioning the solution matrix. The other approach is using the Hamiltonian method directly in vector second order form. Controllers are developed using both approaches and compared to each other. Some simple solutions for special cases are derived for vector second order form using the reduced Algebraic Riccati Equation. The advantages and drawbacks of both approaches are explained through examples.
System analysis and controller applications are carried out for a square membrane system with four actuators. Two different systems with different actuator locations are analyzed. One system has the actuators at the corners of the membrane, the other has the actuators away from the corners. The structural and control effect of actuator locations are demonstrated with mode shapes and simulations. The results of the controller applications and the comparison of the vector first order form with the vector second order form demonstrate the efficacy of the controllers.Ph. D.
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Franco, Vitor Ramos. "Monitoramento da integridade em estruturas aeronáuticas /." Ilha Solteira : [s.n.], 2009. http://hdl.handle.net/11449/94527.
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Resumo: Este trabalho apresenta o estudo e desenvolvimento de uma técnica de monitoramento da integridade estrutural, para identificação e caracterização de falhas estruturais através da metodologia das ondas de Lamb utilizando materiais piezelétricos como sensores e atuadores. Ondas de Lamb são uma forma de perturbação elástica que se propaga guiada entre duas superfícies paralelas livres. Ondas de Lamb são formadas quando o atuador excita a superfície da estrutura com um pulso depois de receber um sinal. Quando uma onda propaga na superfície de uma placa, ela chega em um PZT sensor por diferentes caminhos. Um caminho é quando a onda atinge o sensor diretamente, ou seja, sem obstáculos no caminho em que ela se propaga. Outro caminho possível é quando a onda chega ao sensor após se propagar sobre descontinuidades existentes na superfície da estrutura. Com as várias características dos sinais recebidos, e com o uso de certas técnicas de processamento de sinais, essas falhas podem ser identificadas, realizando-se a ação correta tentando evitar a total falha da estrutura. Nesse contexto, diferentes testes experimentais foram realizados em diferentes tipos de estruturas. Redes de sensores e atuadores piezelétricos foram acopladas na superfície dessas estruturas, a fim de se fazer a configuração das ondas de Lamb. Os PZTs atuadores excitaram a estrutura em altas faixas de frequência. Diferentes tipos de falhas estruturais foram simuladas, através do aumento de massa, alteração de rigidez e através de cortes na borda das estruturas. Quatro índices de falha foram utilizados para detectar a presença da falha na estrutura, são eles: Root- Means-Square Deviation (RMSD), Índice de Falha Métrica (IFM), Norma H2 e Correlation Coefficient Deviation Mean (CCDM). Estes índices foram computados através dos sinais de entrada e de saída no domínio da frequência... (Resumo completo, clicar acesso eletrônico abaixo)Abstract: This work presents the study and development of a Structural Health Monitoring technique for identification and characterization of structural damages based on Lamb waves methodology using piezoelectric materials as actuators and sensors. Lamb waves are a form of elastic perturbation that remains guided between two parallel free surfaces. Lamb waves are formed when the actuator excites the structure's surface with a pulse after receiving a signal. When the wave propagates on the structure, it comes in a PZT sensor from different paths. One path is when the wave reaches the sensor directly, i.e. without obstacles in the path in which it propagated. Another possible path is when the wave reaches the sensor after spreads on discontinuities in the structure's surface. Damages can be detected and located through several features of the received signals and with the use of certain techniques of signal processing. In this context, several experimental tests were performed on different kinds of structures. Piezoelectric actuators and sensors networks were attached on the surface of these structures in order to make the Lamb waves configuration. The PZTs actuators excited the structure in high frequency ranges. Different kinds of structural damages were simulated by increasing mass, reduction of stiffness and cuts through the edge of the structures. Four damage-sensitive indexes were used to detect the presence of the damage in the structure: Root-Means-Square Deviation (RMSD), Metric Damage Index (MDI), H2 Norm and Correlation Coefficient Deviation (CCDM). These indices were computed in the frequency domain. The results showed the viability of the Lamb waves methodology for Structural Health Monitoring system using smart materials as actuators and sensors
Orientador: Vicente Lopes Junior
Coorientador: Michael J. Brennan
Banca: Gilberto Pechoto de Melo
Banca: José Roberto de França Arruda
Mestre
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Narayanan, Pavanesh. "Sensor-less Control of Shape Memory Alloy Using Artificial Neural Network and Variable Structure Controller." University of Toledo / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1416501021.
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Kim, Rae-Young. "Improved renewable energy power system using a generalized control structure for two-stage power converters." Diss., Virginia Tech, 2009. http://hdl.handle.net/10919/28932.
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The dissertation presents a generalized control structure for two-stage power converters operated in a renewable energy power system for smart grid and micro grid systems. The generalized control structure is based on the two-loop average-mode-control technique, and created by reconstructing the conventional control structure and feedback configuration. It is broadly used for both dc-dc and dc-ac power conversion based on the two-stage converter architecture, while offering several functionalities required for renewable energy power systems. The generalized control structure improves the performance and reliability of renewable energy power systems with multiple functionalities required for consistent and reliable distributed power sources in the applications of the smart grid and micro grid system.
The dissertation also presents a new modeling approach based on a modification of the subsystem-integration approach. The approach provides continuous-time small-signal models for all of two-stage power converters in a unified way. As a result, a modeling procedure is significantly reduced by treating a two-stage power converter as a single-stage with current sinking or sourcing. The difficulty of linearization caused by time-varying state variables is avoided with the use of the quasi-steady state concept.
The generalized control structure and modeling approach are demonstrated using the two-stage dc-dc and dc-ac power conversion systems. A battery energy storage system with a thermoelectric source and a grid-connected power system with a photovoltaic source are examined. The large-signal averaged model and small-signal model are developed for the two demonstrated examples, respectively. Based on the modeling results, the control loops are designed by using frequency domain analysis. Various simulations and experimental tests are carried out to verify the compensator designs and to evaluate the generalized control structure performance.
From the simulation and experimental results, it is clearly seen that the generalized control structure improves the performance of a battery energy storage system due to the unified control concept. The unified control concept eliminates transient over-voltage or over-current, extra energy losses, power quality issues, and complicated decision processes for multiple-mode control. It is also seen that the generalized control structure improves the performance of a single-phase grid-connected system through increased voltage control loop bandwidth of the active ripple current reduction scheme. As a result of the increased loop bandwidth, the transient overshoot or undershoot of the dc-link voltage are significantly reduced during dynamic load changes.Ph. D.
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Lin, Brian E. "Stucture and thermomechanical behavior of nitipt shape memory alloy wires." Thesis, Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/28233.
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The objective of this work is to understand the structure-property relationships in a pseudoelastic composition of polycrystalline NiTiPt (Ti-42.7 at% Ni-7.5 at% Pt). Structural characterization of the alloy includes grain size determination and texture analysis while the thermo-mechanical properties are explored using tensile testing. Variation in heat treatment is used as a vehicle to modify microstructure. The results are compared to experiments on Ni-rich NiTi alloy wires (Ti-51.0 at% Ni), which are in commercial use in various biomedical applications. With regards to microstructure, both alloys exhibit a <111> fiber texture along the wire drawing axis, however the NiTiPt alloy's grain size is smaller than that of the Ni-rich NiTi wires, while the latter materials contain second phase precipitates. Given the nanometer scale grain size in NiTiPt and the dispersed, nanometer scale precipitate size in NiTi, the overall strength and ductility of the alloys are essentially identical when given appropriate heat treatments. Property differences include a much smaller stress hysteresis and smaller temperature dependence of the transformation stress for NiTiPt alloys compared to NiTi alloys. Potential benefits and implications for use in vascular stent applications are discussed.
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Sheng, Lizeng. "Finite Element Analysis and Genetic Algorithm Optimization Design for the Actuator Placement on a Large Adaptive Structure." Diss., Virginia Tech, 2004. http://hdl.handle.net/10919/30184.
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The dissertation focuses on one of the major research needs in the area of adaptive /intelligent/smart structures, the development and application of finite element analysis and genetic algorithms for optimal design of large-scale adaptive structures. We first review some basic concepts in finite element method and genetic algorithms, along with the research on smart structures. Then we propose a solution methodology for solving a critical problem in the design of a next generation of large-scale adaptive structures -- optimal placements of a large number of actuators to control thermal deformations. After briefly reviewing the three most frequently used general approaches to derive a finite element formulation, the dissertation presents techniques associated with general shell finite element analysis using flat triangular laminated composite elements. The element used here has three nodes and eighteen degrees of freedom and is obtained by combining a triangular membrane element and a triangular plate bending element. The element includes the coupling effect between membrane deformation and bending deformation. The membrane element is derived from the linear strain triangular element using Cook's transformation. The discrete Kirchhoff triangular (DKT) element is used as the plate bending element. For completeness, a complete derivation of the DKT is presented. Geometrically nonlinear finite element formulation is derived for the analysis of adaptive structures under the combined thermal and electrical loads. Next, we solve the optimization problems of placing a large number of piezoelectric actuators to control thermal distortions in a large mirror in the presence of four different thermal loads. We then extend this to a multi-objective optimization problem of determining only one set of piezoelectric actuator locations that can be used to control the deformation in the same mirror under the action of any one of the four thermal loads. A series of genetic algorithms, GA Version 1, 2 and 3, were developed to find the optimal locations of piezoelectric actuators from the order of 1021 ~ 1056 candidate placements. Introducing a variable population approach, we improve the flexibility of selection operation in genetic algorithms. Incorporating mutation and hill climbing into micro-genetic algorithms, we are able to develop a more efficient genetic algorithm. Through extensive numerical experiments, we find that the design search space for the optimal placements of a large number of actuators is highly multi-modal and that the most distinct nature of genetic algorithms is their robustness. They give results that are random but with only a slight variability. The genetic algorithms can be used to get adequate solution using a limited number of evaluations. To get the highest quality solution, multiple runs including different random seed generators are necessary. The investigation time can be significantly reduced using a very coarse grain parallel computing. Overall, the methodology of using finite element analysis and genetic algorithm optimization provides a robust solution approach for the challenging problem of optimal placements of a large number of actuators in the design of next generation of adaptive structures.Ph. D.
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Chavosh, Ardalan. "Handbook of Waste and Network of Re-use." Thesis, KTH, Stadsbyggnad, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-98819.
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The intelligent handling of waste is a pressing issue today. Up until the 19th century it had been however an integral part of societies especially when it comes to the waste generated by construction and demolition (Bahamon and Sanjines, 2010). After industrial revolution (1750-1850) which opened the gates of mass production and mass consumption followed and supported by two major forces of capitalism and the dramatic increase in world population, the generation of waste accelerated correspondingly and in a global scale. The mass extraction of natural resources on one hand (limited amount of natural resources), and the problems caused by waste landfilling and incineration such as pollution and diseases on the other hand, made us stop this linear extraction-to-waste trend and recognize recycling as a solution. Recycling chiefly addresses a sustainable approach to reduce the negative effects of waste and at the same time involves processing used materials (waste) into new products to prevent waste of potentially useful materials (Eco Cloud), however through recycling not only some energy has to be consumed to make this process run but also some portion of pollution would be generated as a side effect. What is more is that up until today recycling has been neither in many cases economically profitable nor has it been possible to recycle all the amount of waste. For instance In US- as the most consuming society on the planet Earth- only 34% of the municipal solid waste can be recycled and the rest ends up in either landfills or incinerators (EPA,2010). This project is to mainly focus on the definition of a rather comprehensive network (Network of Reuse) which sits right before recycling through which as much as possible of the total amount of waste could be directly absorbed back into the society (with minor changes in some cases) in different scales, the resultants of which would be claimed not to be only less energy consumption and less pollution caused through processing waste (as in recycling) but also avoiding a considerable amount of unrecycled materials from ending up in landfills and incineration. In fact the assumed network-which is simulated by the smart grid model- could be said to be a complementary section added to the existing trend today and is on no account against recycling. Like any other network, the network of reuse is based upon strategies, tools, and policies. The rhizomic growing structure of this network-that is in contrast to the tree structure of recycling- suggests a bottom up movement in handling waste and empowering people while the proposed time-line strategy is assumed to be moving from entertainment towards a coherent business network. In fact the project itself suggests the necessity of more bottom up structures to happen in our future planning. The entire project is highly founded upon research and could be applied in a variety of actual designs and concrete cases. Therefore, in this project no specific site is being addressed directly but the actual need for adding the supposed network is explored.
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Franco, Vitor Ramos [UNESP]. "Monitoramento da integridade em estruturas aeronáuticas." Universidade Estadual Paulista (UNESP), 2009. http://hdl.handle.net/11449/94527.
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franco_vr_me_ilha.pdf: 5148348 bytes, checksum: 722b347f89e5e9a0aa5c379afe0dadba (MD5)Financiadora de Estudos e Projetos (FINEP)
Este trabalho apresenta o estudo e desenvolvimento de uma técnica de monitoramento da integridade estrutural, para identificação e caracterização de falhas estruturais através da metodologia das ondas de Lamb utilizando materiais piezelétricos como sensores e atuadores. Ondas de Lamb são uma forma de perturbação elástica que se propaga guiada entre duas superfícies paralelas livres. Ondas de Lamb são formadas quando o atuador excita a superfície da estrutura com um pulso depois de receber um sinal. Quando uma onda propaga na superfície de uma placa, ela chega em um PZT sensor por diferentes caminhos. Um caminho é quando a onda atinge o sensor diretamente, ou seja, sem obstáculos no caminho em que ela se propaga. Outro caminho possível é quando a onda chega ao sensor após se propagar sobre descontinuidades existentes na superfície da estrutura. Com as várias características dos sinais recebidos, e com o uso de certas técnicas de processamento de sinais, essas falhas podem ser identificadas, realizando-se a ação correta tentando evitar a total falha da estrutura. Nesse contexto, diferentes testes experimentais foram realizados em diferentes tipos de estruturas. Redes de sensores e atuadores piezelétricos foram acopladas na superfície dessas estruturas, a fim de se fazer a configuração das ondas de Lamb. Os PZTs atuadores excitaram a estrutura em altas faixas de frequência. Diferentes tipos de falhas estruturais foram simuladas, através do aumento de massa, alteração de rigidez e através de cortes na borda das estruturas. Quatro índices de falha foram utilizados para detectar a presença da falha na estrutura, são eles: Root- Means-Square Deviation (RMSD), Índice de Falha Métrica (IFM), Norma H2 e Correlation Coefficient Deviation Mean (CCDM). Estes índices foram computados através dos sinais de entrada e de saída no domínio da frequência...
This work presents the study and development of a Structural Health Monitoring technique for identification and characterization of structural damages based on Lamb waves methodology using piezoelectric materials as actuators and sensors. Lamb waves are a form of elastic perturbation that remains guided between two parallel free surfaces. Lamb waves are formed when the actuator excites the structure’s surface with a pulse after receiving a signal. When the wave propagates on the structure, it comes in a PZT sensor from different paths. One path is when the wave reaches the sensor directly, i.e. without obstacles in the path in which it propagated. Another possible path is when the wave reaches the sensor after spreads on discontinuities in the structure’s surface. Damages can be detected and located through several features of the received signals and with the use of certain techniques of signal processing. In this context, several experimental tests were performed on different kinds of structures. Piezoelectric actuators and sensors networks were attached on the surface of these structures in order to make the Lamb waves configuration. The PZTs actuators excited the structure in high frequency ranges. Different kinds of structural damages were simulated by increasing mass, reduction of stiffness and cuts through the edge of the structures. Four damage-sensitive indexes were used to detect the presence of the damage in the structure: Root-Means-Square Deviation (RMSD), Metric Damage Index (MDI), H2 Norm and Correlation Coefficient Deviation (CCDM). These indices were computed in the frequency domain. The results showed the viability of the Lamb waves methodology for Structural Health Monitoring system using smart materials as actuators and sensors
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Wang, Zhuang. "Intrinsic Fabry-Perot Interferometric Fiber Sensor Based on Ultra-Short Bragg Gratings for Quasi-Distributed Strain and Temperature Measurements." Diss., Virginia Tech, 2006. http://hdl.handle.net/10919/30213.
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The health monitoring of smart structures in civil engineering is becoming more and more important as in-situ structural monitoring would greatly reduce structure life-cycle costs and improve reliability. The distributed strain and temperature sensing is highly desired in large structures where strain and temperature at over thousand points need to be measured simultaneously. It is difficult to carry out this task using conventional electrical strain sensors. Fiber optic sensors provide an excellent opportunity to fulfill this need due to their capability to multiplex many sensors along a single fiber cable. Numerous research studies have been conducted in past decades to increase the number of sensors to be multiplexed in a distributed sensor network.
This dissertation presents detailed research work on the analysis, design, fabrication, testing, and evaluation of an intrinsic Fabry-Perot fiber optic sensor for quasi-distributed strain and temperature measurements. The sensor is based on two ultra-short and broadband reflection fiber Bragg gratings. One distinct feature of this sensor is its ultra low optical insertion loss, which allows a significant increase in the sensor multiplexing capability. Using a simple integrated sensor interrogation unit and an optical spectrum based signal processing algorithm, many sensors can be interrogated along a single optical fiber with high accuracy, high resolution and large dynamic range. Based on the experimental results and theoretical analysis, it is expected that more than 500 sensors can be multiplexed with little crosstalk using a frequency-division multiplexing technology. With this research, it is possible to build an easy fabrication, robust, high sensitivity and quasi-distributed fiber optic sensor network that can be operated reliably even in harsh environments or extended structures.
This research was supported in part by U.S. National Science Foundation under grant CMS-0427951.Ph. D.
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Maillard, Julien. "Advanced Time Domain Sensing For Active Structural Acoustic Control." Diss., Virginia Tech, 1997. http://hdl.handle.net/10919/30335.
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Active control of sound radiation from vibrating structures has been an area of much research in the past decade. In Active Structural Acoustic Control (ASAC), the minimization of sound radiation is achieved by modifying the response of the structure through structural inputs rather than by exciting the acoustic medium (Active Noise Control, ANC). The ASAC technique often produces global far-field sound attenuation with relatively few actuators as compared to ANC. The structural control inputs of ASAC systems are usually constructed adaptively in the time domain based on a number of error signals to be minimized. One of the primary concerns in active control of sound is then to provide the controller with appropriate ``error'' information. Early investigations have implemented far-field microphones, thereby providing the controller with actual radiated pressure information. Most structure-borne sound control approaches now tend to eliminate the use of microphones by developing sensors that are integrated in the structure. This study presents a new sensing technique implementing such an approach. A structural acoustic sensor is developed for estimating radiation information from vibrating structures. This technique referred to as Discrete Structural Acoustic Sensing (DSAS) provides time domain estimates of the radiated sound pressure at prescribed locations in the far field over a broad frequency range. The structural acoustic sensor consists of a set of accelerometers mounted on the radiating structure and arrays of digital filters that process the measured acceleration signals in real time. The impulse response of each filter is constructed from the appropriate radiation Green's function for the source area associated with each accelerometer.
Validation of the sensing technique is performed on two different systems: a baffled rectangular plate and a baffled finite cylinder. For both systems, the sensor is first analyzed in terms of prediction accuracy by comparing estimated and actual sound pressure radiated in the far field. The analysis is carried out on a numerical model of the plate and cylinder as well as on the real structures through experimental testing. The sensor is then implemented in a broadband radiation control system. The plate and cylinder are excited by broadband disturbance inputs over a frequency range encompassing several of the first flexural resonances of the structure. Single-sided piezo-electric actuators provide the structural control inputs while the sensor estimates are used as error signals. The controller is based on the filtered-x version of the adaptive LMS algorithm. Results from both analytical and experimental investigations are again presented for the two systems. Additional control results based on error microphones allow a comparison of the two sensing approaches in terms of control performance.
The major outcome of this study is the ability of the structural acoustic sensor to effectively replace error microphones in broadband radiation control systems. In particular, both analytical and experimental results show the level of sound attenuation achieved when implementing Discrete Structural Acoustic Sensing rivaled that achieved with far-field error microphones. Finally, the approach presents a significant alternative over other existing structural sensing techniques as it requires very little system modeling.Ph. D.
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Stragier, Anne-Sophie. "Elaboration et caractérisation de structures Silicium-sur-Isolant réalisées par la technologie Smart Cut™ avec une couche fragile enterrée en silicium poreux." Thesis, Lyon, INSA, 2011. http://www.theses.fr/2011ISAL0108.
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Au vu des limitations rencontrées par la miniaturisation des circuits microélectroniques, l’augmentation de performances des systèmes repose largement aujourd’hui sur la fabrication d’empilements de couches minces complexes et innovants pour offrir davantage de compacité et de flexibilité. L’intérêt grandissant pour la réalisation de structures innovantes temporaires, i.e. permettant de réaliser des circuits sur les deux faces d’un même film, nous a mené à évaluer les potentialités d’une technologie combinant le transfert de films minces monocristallins, i.e. la technologie Smart Cut™, et un procédé de de porosification partielle du silicium afin de mettre au point une technologie de double report de film monocristallin. En ce sens, des substrats de silicium monocristallin ont été partiellement porosifiés par anodisation électrochimique. La mise en œuvre de traitements de substrats partiellement poreux a nécessité l’emploi de techniques de caractérisation variées pour dresser une fiche d’identité des couches minces poreuses après anodisation et évaluer l’évolution des propriétés de ces couches en fonction des différents traitements appliqués. Les propriétés chimiques, structurales et mécaniques des couches de Si poreux ont ainsi été étudiées via l’utilisation de différentes techniques de caractérisation (XPS-SIMS, AFM-MEB-XRD, nanoindentation, technique d’insertion de lame, etc.). Ces études ont permis d’appréhender et de décrire les mécanismes physiques mis au jeu au cours des différents traitements et de déterminer les caractéristiques {porosité, épaisseur} optimales des couches poreuses compatibles avec les séquences de la technologie proposée. La technologie Smart Cut™ a ainsi été appliquée à des substrats partiellement porosifiés menant à la fabrication réussie d’une structure temporaire de type Silicium-sur-Isolant avec une couche de silicium poreux enterrée. Ces structures temporaires ont été « démontées » dans un second temps par collage polymère ou collage direct et insertion de lame menant au second report de film mince monocristallin par rupture au sein de la couche porosifiée et donc fragile. Les structures fabriquées ont été caractérisées pour vérifier leur intégrité et leurs stabilités chimique et mécanique. Les propriétés cristallines du film mince de Si monocristallin, reporté en deux temps, ont été vérifiées confirmant ainsi la compatibilité des structures fabriquées avec des applications microélectroniques telles que les applications de type « Back-Side Imager » nécessitant une implémentation de composants sur les deux faces du film. Ainsi une technologie prometteuse et performante a pu être élaborée permettant le double report de films minces monocristallins et à fort potentiel pour des applications variées comme les imageurs visibles ou le photovoltaïqueAs scaling of microelectronic devices is confronted from now to fundamental limits, improving microelectronic systems performances is largely based nowadays on complex and innovative stack realization to offer more compaction and flexibility to structures. Growing interest in the fabrication of innovative temporary structures, allowing for example double sided layer processing, lead us to investigate the capability to combine one technology of thin single crystalline layer transfer, i.e. the Smart Cut™ technology, and partial porosification of silicon substrate in order to develop an original double layer transfer technology of thin single crystalline silicon film. To this purpose, single crystalline silicon substrates were first partially porosified by electrochemical anodization. Application of suitable treatments of porous silicon layer has required the use of several characterization methods to identify intrinsic porous silicon properties after anodization and to verify their evolution as function of different applied treatments. Chemical, structural and mechanical properties of porous silicon layers were studied by using different characterization techniques (XPS-SIMS, AFM-MEB-XRD, nanoindentation, razor blade insertion, etc.). Such studies allowed comprehending and describing physical mechanisms occurring during each applied technological steps and well determining appropriated {porosity, thickness} parameters of porous silicon layer with the developed technological process flow. The Smart Cut™ technology was successfully applied to partially porosified silicon substrates leading to the fabrication of temporary SOI-like structures with a weak embedded porous Si layer. Such structures were then “dismantled” thanks to a second polymer or direct bonding and razor blade insertion to produce a mechanical rupture through the fragile embedded porous silicon layer and to get the second thin silicon film transfer. Each fabricated structure was characterized step by step to check its integrity and its chemical and mechanical stabilities. Crystalline properties of the double transferred silicon layer were verified demonstrating the compatibility of such structures with microelectronic applications such as “Back-Side Imagers” needing double-sided layer processing. Eventually, a promising and efficient technology has been developed to allow the double transfer of thin single crystalline silicon layer which presents a high potential for various applications such as visible imagers or photovoltaic systems
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Yi, Duo. "Intégration de capteurs à fibre optique par projection thermique pour des applications de contrôle de structures intelligentes." Thesis, Belfort-Montbéliard, 2016. http://www.theses.fr/2016BELF0285/document.
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Ce mémoire présente la modélisation, la simulation, l’expérimentation et la conception d’une structure composite intelligente pour des mesures de haute température (jusqu’à 300 °C). Pour ce faire, une fibre à revêtement métallique, particulièrement résistante pour de tels niveaux thermiques, a été considérée et intégrée au sein d’un revêtement d'alumine. La structure composite intelligente se compose alors du substrat, du dépôt et d’un capteur à fibre optique à modulation d’intensité. Pour mener cette étude, une estimation des flux thermiques basée sur le thermogramme expérimental s’est révélée nécessaire afin d’alimenter un modèle numérique. Différents modèles ont ensuite été construits afin d’évaluer les niveaux de températures atteints en surface ainsi que les niveaux de contraintes au sein même du composite. La simulation a montré que le dépôt pouvait thermiquement être considéré comme une couche mince et que la diffusion de la chaleur au sein du dépôt et du substrat était rapide et pouvait être estimée à l'échelle de la milliseconde. La répartition des contraintes est comme on pouvait s'y attendre dépendante du flux incident mais aussi de la géométrie globale du composite. Les contraintes restent relativement uniformes lors de l'échauffement et durant leur propagation mais s’intensifient après le refroidissement. Il s'avère également que les contraintes résultantes ne sont pas symétriques dans la fibre et sont dépendantes de la position de la fibre par rapport au substrat. Après une phase de modélisation des niveaux thermiques et des contraintes susceptibles d’être atteints au sein du matériau, une phase expérimentale consistant à intégrer une fibre optique non fonctionnalisée dans un dépôt d’alumine a donc été réalisée. Les observations microscopiques en surface et en coupe ont été effectuées afin de vérifier l’intégrité de la fibre intégrée. L’adhérence mécanique des fibres a ensuite été mesurée ainsi que l’atténuation optique pendant le processus d’intégration et le comportement thermique de l’ensemble durant des cyclages thermiques. Enfin, un capteur à fibre optique à modulation d’intensité a été conçu par intégration dans un dépôt céramique réalisé par projection thermique. Un système de mesure de la température a donc été construit et les premiers essais de réponse thermique ainsi que le cyclage thermique du capteur de température ont été effectués et analysés. En concluision, cette étude démontre la faisabilité d’une structure composite intelligente par intégration d'un capteur à modulation d’intensité à fibre optique dans un dépôt céramique élaboré par projection thermique susceptible de pouvoir travailler jusqu’à des températures de 300 °CThis paper presents the modeling, simulation, experimentation and design of a smart composite structrure for high temperature measurements (up to 300 °C). In order to achieve this goal, a high temperature resistant metal coated optical fiber was considered and integrated into alumina coating. The smart composite structure consists of a substrate, a coating and an intensity modulated optical fiber temperature sensor. Firstly, an estimation of heat flux based on a experimental thermogram was firstly carried out in order to feed a numerical modeling. Then, different modelings were built to evaluate the surface temperature levels as well as the composite stress levels. The simulation showed that the composite (substrate and coating) could be considered as a thermally thin medium, the heat propagation within the composite was fast and could be estimated at a scale of millisecond. The stresses remained relatively uniform during the heating process but intensified during the cooling process. The modeling also showed that the stresses are not symmetrical in the fiber and depend on the position of the fiber relative to the substrate. After a modeling evaluation of the thermal levels as well as the stresses that may be achieved in the composite, an experimental step integrating a optical fiber into a thermal coating was carried out. Microscopic observation of surface and cross section were conducted in order to analyze the characteristics of the integrated fiber. The mechanical strength of the integrated fiber was then measured and the optical attenuation during the integration process as well as the thermal behavior of the integrated fiber during the thermal cycling were evaluated. Finally, an intensity modulated optical fiber temperature sensor was designed and integrated into ceramic coating by thermal spraying. A temperature measuring system was designed and the first tests of the thermal response as well as thermal cycling of temperature sensor were carried out. This study demonstrates the feasibility of designing a high temperature resistant smart composite structure by integrating an intensity modulated optical fiber temperature sensor in a ceramic coating elaborated by thermal spraying
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Sinn, Thomas. "Smart deployable space structures." Thesis, University of Strathclyde, 2016. http://digitool.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=28327.
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Nowadays, space structures are often designed to serve only a single objective during their mission life, examples range from solar sail for propulsion over shields for protection to antennas and reflectors for communication and observation. By enabling a structure to deploy and change its shape to adapt to different mission stages, the flexibility of the spacecraft can be greatly increased while significantly decreasing the mass and the volume of the system. Inspiration was taken from nature. Various plants have the ability to follow the sun with their flowers or leaves during the course of a day via a mechanism known as heliotropism. This mechanism is characterized by the introduction of pressure gradients between neighboring motor cells in the plant’s stem,enabling the stem to bend. By adapting this bio-inspired mechanism to mechanical systems, a new class of smart deployable structures can be created. The shape change of the full structure can be significant by adding up these local changes induced by the reoccurring cell elements. The structure developed as part of this thesis consists of an array of interconnected cells which are each able to alter their volume due to internal pressure change. By coordinated cell actuation in a specific pattern, the global structure can be deformed to obtain a desired shape. A multibody code was developed which constantly solves the equation of motion with inputs from internal actuation and external perturbation forces. During the inflation and actuation of the structure, the entities of the mass matrix and the stiffness matrix are changed due to changing properties of the cells within the array based on their state and displacement. This thesis will also give an overview of the system architecture for different missions and shows the feasibility and shape changing capabilities of the proposed design with multibody dynamic simulations. Furthermore, technology demonstrator experiments on stratospheric balloons and sounding rockets have been carried out to show the applicability and functionality of the developed concepts.
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Blanc, Arthur. "Control of Sound Radiation From Structures with Periodic Smart Skins." Thesis, Virginia Tech, 2001. http://hdl.handle.net/10919/35080.
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An innovative implementation of the skin concept for the reduction of the radiated sound power from a vibrating structure is proposed. The skin has a periodic structure and continuously covers a vibrating beam. Thus, this skin decouples the vibrating structure from the acoustic field by modifying the wavenumber spectrum of the radiating surface. First, structural acoustics and periodic structure theories are reviewed in order to predict how bending waves propagate along a periodic beam and how this beam radiates sound. These theories are then extended to the case of multi-layered structures in order to understand the behavior of a beam loaded with a periodic skin. In order to design the beam and skin structural periods, two different methods are used: Galois sequences and an optimization process using a real-valued genetic algorithm. Simulations are run for the case of periodic beams and beams coupled with periodic smart skins in both finite and infinite configurations. Results show that periodic beam can radiate less sound than equivalent uniform structures. Results also show the potential of periodic skin for application to the structural radiation problem for frequencies higher than approximately 100Hz with an approximately 10dB of radiated sound power attenuation.Master of Science
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Soriano, casero Robert. "Etude de la gravure du SiN contrôlée a l'échelle atomique par implantation d'O2 suivi de gravure ultra-sélective SiO2/SiN en plasma déporté NF3/NH3." Thesis, Université Grenoble Alpes (ComUE), 2019. http://www.theses.fr/2019GREAT003/document.
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Depuis le début de la microélectronique, l’industrie a développé sans arrêt des nouvelles technologies de gravure plasma pour diminuer la taille des dispositifs tout en réduisant le cout de fabrication et en augmentent les performances des circuits intégrés. Aujourd’hui, les transistors tel que le FDSOI 22nm ou FinFET 10 nm doivent être gravé avec une précision sub-nanométrique et sans endommager la sous-couche sur plus d’une couche atomique. Pour arriver à faire cela, de nouvelles technologie se développent, dont le Smart Etch. Cette technologie en deux étapes consiste à modifier la surface du matériau sous l’action d’un plasma, puis à retirer ce matériau modifié sélectivement par rapport au matériau non modifié. Le but de cette thèse est d’étudier la faisabilité de remplacer les plasmas de He et H2 utilisé dans le Smart Etch par des plasmas d’O2. L’intérêt est l’oxydation du matériau est une réelle modification chimique, permettant l’élimination sélective de ce dernier en RPS. Par ailleurs, contrairement aux plasma de He/H2, le plasma de O2 ne grave pas les parois du réacteur et rejette beaucoup moins d’impuretés dans le plasma. Dans un premier temps, nous avons étudié les mélanges gazeux NF3/H2 et NF3/NH3 utilisés dans l’étape de retrait RPS. Ces études ont été fait grâce à la spectroscopie d’absorption VUV et d’émission UV. Nous avons mis en évidence la création de HF dans les deux mélanges et nous avons mis en avant de manière indirecte la création de NH4F (cette espèce jouant un rôle clé dans la formation des sels) à partir de NH3 et HF. De plus nous avons observé la présence de F et H qui sont responsable de la gravure de SiO2 et SiN lorsque H2Since the beginning of microelectronics, the industry has continuously developed new plasma etching technologies to reduce the size of devices while reducing the cost of manufacturing and increase the performance of integrated circuits. Today, transistors such as 22nm FDSOI or 10nm FinFET must be engraved with sub-nanometric precision and without damaging the underlayment on more than one atomic layer. To achieve this, new technologies are developing, including the Smart Etch. This two-step technology involves modifying the surface of the material under the action of a plasma and then removing selectively the modified material from the unmodified material. The aim of this thesis is to study the feasibility of replacing the He and H2 plasmas used in the Smart Etch by O2 plasmas. The interest is the oxidation of the material, that it is a real chemical modification, allowing latter the selective elimination by RPS. Moreover, unlike He / H2 plasma, the O2 plasma does not damage the reactor walls and releases much less impurities into the plasma. Firstly, we studied the gaseous mixtures NF3 / H2 and NF3 / NH3 used in the step of RPS remove. Thouse studies were done through VUV absorption spectroscopy and UV emission. We have demonstrated the creation of HF in both mixtures and we have indirectly highlighted the creation of NH4F (this species plays a key role in the formation of salts) from NH3 and HF. In addition we observed the presence of F and H which are responsible for the etching of SiO2 and SiN when H2