Dissertations / Theses: 'Composite materials – Quality control'

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Huang, Da. "Approximate analytical solutions for vibration control of smart composite beams." Thesis, Peninsula Technikon, 1999. http://hdl.handle.net/20.500.11838/1262.

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Thesis (MTech (Mechanical Engineering))--Peninsula Technikon, Cape Town,1999 Smart structures technology featuring a network of sensors and actuators, real-time control capabilities, computational capabilities and host material will have tremendous impact upon the design, development and manufacture of the next generation of products in diverse industries. The idea of applying smart materials to mechanical and structural systems has been studied by researchers in various disciplines. Among the promising materials with adaptable properties such as piezoelectric polymers and ceramics, shape memory alloys, electrorheological fluids and optical fibers, piezoelectric materials can be used both as sensors and actuators because of their high direct and converse piezoelectric effects. The advantage of incorporating these special types of material into the structure is that the sensing and actuating mechanism becomes part of the structure by sensing and actuating strains directly. This advantage is especially apparent for structures that are deployed in aerospace and civil engineering. Active control systems that rely on piezoelectric materials are effective in controlling the vibrations of structural elements such as beams, plates and shells. The beam as a fundamental structural element is widely used in all construction. The purpose of the present project is to derive a set of approximate governing equations of smart composite beams. The approximate analytical solution for laminated beams with piezoelectric laminae and its control effect will be also presented. According to the review of the related literature, active vibration control analysis of smart beams subjected to an impulsive loading and a periodic excitation are simulated numerically and tested experimentally.

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Gaete-Martinez, Victor. "Optical Measurement of Strang Geometry and Orientation and Their Influence on Oriented Strand Composite Formation Quality." Fogler Library, University of Maine, 2009. http://www.library.umaine.edu/theses/theses.asp?highlight=1&Cmd=abstract&ID=FTY2009-004.

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Wang, Ya. "Simultaneous Energy Harvesting and Vibration Control via Piezoelectric Materials." Diss., Virginia Tech, 2012. http://hdl.handle.net/10919/26191.

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This work examines a novel concept and design of simultaneous energy harvesting and vibration control on the same host structure. The motivating application is a multifunctional composite sandwich wing spar for a small Unmanned Aerial Vehicle (UAV) with the goal of providing self-contained gust alleviation. The basic idea is that the wing itself is able to harvest energy from the ambient vibrations along with available sunlight during normal flight. If the wing experiences any strong wind gust, it will sense the increased vibration levels and provide vibration control to maintain its stability. This work holds promise for improving performance of small UAVs in wind gusts. The proposed multifunctional wing spar integrates a flexible solar cell array, flexible piezoelectric wafers, a thin film battery and an electronic module into a composite sandwich structure. The basic design factors are discussed for a beam-like multifunctional wing spar with load-bearing energy harvesting, strain sensing and self-controlling functions. Three-point bending tests are performed on the composite sandwich structure for bending strength analysis and bending stiffness prediction under a given safety factor. Additional design factors such as the configuration, location and actuation type of each piezoelectric transducer are investigated for optimal power generation. The equivalent electromechanical representations of a multifunctional wing spar is derived theoretically, simulated numerically and validated experimentally. Special attention is given to the development of a reduced energy control (REC) law, aiming to minimize the actuation energy and the dissipated heat. The REC law integrates a nonlinear switching algorithm with a positive strain feedback controller, and is represented by a positive feedback operation amplifier (op-amp) and a voltage buffer op-amp for each mode. Experimental results exhibit that the use of nonlinear REC law requires 67.3 % less power than a conventional nonlinear controller to have the same settling time under free vibrations. Nonlinearity in the electromechanical coupling coefficient of the piezoelectric transducer is also observed, arising from the piezoelectric hysteresis in the constitutive equations coupling the strain field and the electric field. If a constant and voltage-independent electromechanical coupling coefficient is assumed, this nonlinearity results in considerable discrepancies between experimental measurements and simulation results. The voltage-dependent coupling coefficient function is identified experimentally, and a real time adaptive control algorithm is developed to account for the nonlinear coupling behavior, allowing for more accurate numerical simulations. Experimental validations build upon recent advances in harvester, sensor and actuator technology that have resulted in thin, light-weight multilayered composite sandwich wing spars. These multifunctional wing spars are designed and validated to able to alleviate wind gust of small UAVs using the harvested energy. Experimental results are presented for cantilever wing spars with micro-fiber composite transducers controlled by reduced energy controllers with a focus on two vibration modes. A reduction of 11dB and 7dB is obtained for the first and the second mode using the harvested ambient energy. This work demonstrates the use of reduced energy control laws for solving gust alleviation problems in small UAVs, provides the experimental verification details, and focuses on applications to autonomous light-weight aerospace systems. Ph. D.

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Thompson, Eric J. "Design of a multi-piece removable mandrel mold tool to fabricate and control inner mold surface contour of a composite wing spar." Morgantown, W. Va. : [West Virginia University Libraries], 2010. http://hdl.handle.net/10450/11141.

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Thesis (M.S.)--West Virginia University, 2010. Title from document title page. Document formatted into pages; contains viii, 69 p. : col. ill. Includes abstract. Includes bibliographical references (p. 69).

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Nguyen, Van Ky Quan. "PIEZOELECTRIC ACTUATOR DESIGN OPTIMISATION FOR SHAPE CONTROL OF SMART COMPOSITE PLATE STRUCTURES." University of Sydney. Aerospace, Mechanical and Mechatronic, 2005. http://hdl.handle.net/2123/652.

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Shape control of a structure with distributed piezoelectric actuators can be achieved through optimally selecting the loci, shapes and sizes of the piezoelectric actuators and choosing the electric fields applied to the actuators. Shape control can be categorised as either static or dynamic shape control. Whether it is a transient or gradual change, static or dynamic shape control, both aim to determine the loci, sizes, and shapes of piezoelectric actuators, and the applied voltages such that a desired structural shape is achieved effectively. This thesis is primarily concerned with establishing a finite element formulation for the general smart laminated composite plate structure, which is capable to analyse static and dynamic deformation using non-rectangular elements. The mechanical deformation of the smart composite plate is modelled using a third order plate theory, while the electric field is simulated based on a layer-wise theory. The finite element formulation for static and dynamics analysis is verified by comparing with available numerical results. Selected experiments have also been conducted to measure structural deformation and the experimental results are used to correlate with those of the finite element formulation for static analysis. In addition, the Linear Least Square (LLS) method is employed to study the effect of different piezoelectric actuator patch pattern on the results of error function, which is the least square error between the calculated and desired structural shapes in static structural shape control. The second issue of this thesis deals with piezoelectric actuator design optimisation (PADO) for quasi-static shape control by finding the applied voltage and the configuration of piezoelectric actuator patch to minimise error function, whereas the piezoelectric actuator configuration is defined based on the optimisation technique of altering nodal coordinates (size/shape optimisation) or eliminating inefficient elements in a structural mesh (topology optimisation). Several shape control algorithms are developed to improve the structural shape control by reducing the error function. Further development of the GA-based voltage and piezoelectric actuator design optimisation method includes the constraint handling, where the error function can be optimised subjected to energy consumption or other way around. The numerical examples are presented in order to verify that the proposed algorithms are applicable to quasi-static shape control based on voltage and piezoelectric actuator design optimisation (PADO) in terms of minimising the error function. The third issue is to use the present finite element formulation for a modal shape control and for controlling resonant vibration of smart composite plate structures. The controlled resonant vibration formulation is developed. Modal analysis and LLS methods are also employed to optimise the applied voltage to piezoelectric actuators for achieving the modal shapes. The Newmark direct time integration method is used to study harmonic excitation of smart structures. Numerical results are presented to induce harmonic vibration of structure with controlled magnitude via adjusting the damping and to verify the controlled resonant vibration formulation.

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Billon, Astrid. "Méthode d'évaluation non-destructive de la qualité du collage des composites de renforcement pour le génie civil." Thesis, Paris Est, 2016. http://www.theses.fr/2016PESC1091/document.

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Dans le secteur du génie civil, le renforcement structural et la réparation des ouvrages en béton par collage de polymère renforcé de fibres de carbone (PRFC) sont des techniques désormais répandues. Les performances et la durabilité du système de renforcement sont intrinsèquement liées à la qualité du collage entre le matériau composite et le béton. Or, en pratique, les conditions environnementales et les contraintes liées au chantier ne permettent pas d’assurer l’intégrité de ce collage, dont les propriétés évoluent par ailleurs dans le temps en raison des phénomènes de vieillissement. La vérification in-situ par une méthode non-destructive de l’état du collage est donc une étape importante pour garantir les propriétés d'usage tout au long de la vie du renforcement.Une méthode d’évaluation non-destructive est développée dans le cadre de cette étude. Elle s’inspire de l’essai standard d’arrachement en traction directe bien connu sur le terrain. La méthode repose sur un essai mécanique qui caractérise le comportement en charge – déplacement de l’assemblage, et permet d’exprimer un critère d’évaluation appelé raideur d’assemblage qui dépend notamment du module d’Young de l’adhésif utilisé.La faisabilité en laboratoire de cette méthode est vérifiée sur un dispositif d’essai entièrement conçu pour les fins de l’étude. Un travail d’analyse et de dimensionnement basé sur une modélisation numérique par éléments finis permet de sélectionner des capteurs et une chaîne d’acquisition adaptés. Une formulation analytique partielle de la raideur d’assemblage est énoncée.Une campagne expérimentale sur des éprouvettes de béton renforcées par lamelles de PRFC avec trois adhésifs époxy différents est ensuite mise en œuvre. Les résultats sont interprétés en suivant une approche statistique qui prend en compte les variations de tous les paramètres d’influence. Les performances de détection de l’essai dans le cadre de notre application en laboratoire peuvent ainsi être exprimées.Des éléments contribuant à l’élaboration d’une méthodologie d’essai applicable in-situ sont enfin apportés, et les performances de l’essai sont rediscutées en vue de cette transposition sur le terrain Over the last 30 years, repairing and strengthening techniques of concrete structures using externally bonded carbon fiber reinforced polymer (CFRP) composites have gained much popularity and are now widespread. The effectiveness of the strengthening systems highly depends on the level of adhesion between the composite material and the concrete surface. Therefore, on-site evaluation of the bond quality is crucial to assess the performance and predict the durability of the reinforcement system.It is proposed to determine the bond properties of the adhesive layer within the reinforcement system by using a nondestructive test (NDT) method derived from the standard and well-known pull-off test. This method consists in analyzing the linear load vs displacement behavior of the adhesive joint, in order to determine an assembly stiffness which can be related to the Young’s modulus of the adhesive layer.In order to investigate the feasibility of the test method, a laboratory implementation is carried out on a mechanical device fully designed for the purpose of the present study. Suitable displacement sensors and an appropriate measurement chain are chosen based on a finite element modeling and a mechanical analysis of the test. A partial analytical form of the assembly stiffness is also expressed.The test method is then applied to concrete slabs reinforced with CFRP plates using three different epoxy adhesives. A statistical assessment of all identified parameters of influence sheds light on the results. In the end, the performances of the test performed in laboratory conditions are discussed.Finally, foundations for a relevant test methodology on real field conditions are laid, and the above-mentioned performances are reviewed

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Simington, Maureen Fresquez 1970. "Redefining manufacturing quality control in the electronics industry." Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/34709.

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Thesis (S.M.)--Massachusetts Institute of Technology, Sloan School of Management; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering; in conjunction with the Leaders for Manufacturing Program, Massachusetts Institute of Technology, 2000. Also available online at the MIT Theses Online homepage <http://thesis.mit.edu>. Includes bibliographical references (p. 103). The most time consuming and capital intensive portion in the assembly of power electronic devices is the test system. A comprehensive test system including functional and stress screening technologies can significantly increase assembly times and more than double the capital investment required in a new assembly line. The primary purpose of the test system is to screen components for early life failures and to verify proper assembly. Determination of key performance characteristics and the resultant test system are developed during the product design phase and are seldom revised after the product has been released to manufacturing. This thesis explores best practices in testing methods and develops new methods to analyze test system performance. Both efforts were conducted in an effort to optimize existing test regimes. Upon completion of the above analyses the existing test sequence was reduced by 50%. This was primarily due to a discovery in the Burn In test cycle which indicated that failures correlated strongly with the on/off cycles inherent in the test sequence. A new test cycle was proposed to accommodate this finding and test results verified the initial hypothesis. Additionally, the summary of best practices identified new forms of product testing including Highly Accelerated Stress Testing (HAST), moving additional product testing into the development phase consequently reducing testing requirements during assembly. by Maureen Fresquez Simington. S.M.

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Patsora, Iryna, Dmytro Tatarchuk, Henning Heuer, and Susanne Hillmann. "Study of a Particle Based Films Cure Process by High-Frequency Eddy Current Spectroscopy." Multidisciplinary Digital Publishing Institute, 2016. https://tud.qucosa.de/id/qucosa%3A30206.

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Particle-based films are today an important part of various designs and they are implemented in structures as conductive parts, i.e., conductive paste printing in the manufacture of Li-ion batteries, solar cells or resistive paste printing in IC. Recently, particle based films were also implemented in the 3D printing technique, and are particularly important for use in aircraft, wind power, and the automotive industry when incorporated onto the surface of composite structures for protection against damages caused by a lightning strike. A crucial issue for the lightning protection area is to realize films with high homogeneity of electrical resistance where an in-situ noninvasive method has to be elaborated for quality monitoring to avoid undesirable financial and time costs. In this work the drying process of particle based films was investigated by high-frequency eddy current (HFEC) spectroscopy in order to work out an automated in-situ quality monitoring method with a focus on the electrical resistance of the films. Different types of particle based films deposited on dielectric and carbon fiber reinforced plastic substrates were investigated in the present study and results show that the HFEC method offers a good opportunity to monitor the overall drying process of particle based films. Based on that, an algorithm was developed, allowing prediction of the final electrical resistance of the particle based films throughout the drying process, and was successfully implemented in a prototype system based on the EddyCus® HFEC device platform presented in this work. This prototype is the first solution for a portable system allowing HFEC measurement on huge and uneven surfaces.

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Patsora, Iryna, Dmytro Tatarchuk, Henning Heuer, and Susanne Hillmann. "Study of a Particle Based Films Cure Process by High-Frequency Eddy Current Spectroscopy." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-220609.

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Particle-based films are today an important part of various designs and they are implemented in structures as conductive parts, i.e., conductive paste printing in the manufacture of Li-ion batteries, solar cells or resistive paste printing in IC. Recently, particle based films were also implemented in the 3D printing technique, and are particularly important for use in aircraft, wind power, and the automotive industry when incorporated onto the surface of composite structures for protection against damages caused by a lightning strike. A crucial issue for the lightning protection area is to realize films with high homogeneity of electrical resistance where an in-situ noninvasive method has to be elaborated for quality monitoring to avoid undesirable financial and time costs. In this work the drying process of particle based films was investigated by high-frequency eddy current (HFEC) spectroscopy in order to work out an automated in-situ quality monitoring method with a focus on the electrical resistance of the films. Different types of particle based films deposited on dielectric and carbon fiber reinforced plastic substrates were investigated in the present study and results show that the HFEC method offers a good opportunity to monitor the overall drying process of particle based films. Based on that, an algorithm was developed, allowing prediction of the final electrical resistance of the particle based films throughout the drying process, and was successfully implemented in a prototype system based on the EddyCus® HFEC device platform presented in this work. This prototype is the first solution for a portable system allowing HFEC measurement on huge and uneven surfaces.

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Tremaine, Kellie Michelle. "MODAL ANALYSIS OF COMPOSITE STRUCTURES WITH DAMPING MATERIAL." DigitalCommons@CalPoly, 2012. https://digitalcommons.calpoly.edu/theses/823.

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The purpose of this study is to develop an analytical solution for modal analysis of actively damped orthotropic composite plates in bending and to verify it with experimental analysis. The analytical modal analysis solution for composite plate dynamics is derived using Euler theory. This analysis applies to structures with orthotropic lamina of uniform material properties at any lamination angle. The bending-extensional coupling can be neglected for plates that are symmetric or approximately symmetric, which allows an exact solution for natural frequency and mode shape to be obtained. An exact solution can be found for natural vibration and in general. The active control is modeled analytically by combining the Lagrange equation with the Ritz Assumed Mode method. This analysis produces a generalized coordinate vector that correlates the assumed mode to the particular amplitude of a particular case. The kinetic energy dissipated by the piezoelectric actuator from the system over one oscillation can be calculated from the generalized coordinate vector and the assumed mode. The equivalent damping ratio of the active control system is calculated as the ratio between the kinetic energy absorbed by the piezoelectric actuator from the system in one oscillation and the maximum strain energy of the system during that oscillation. A point mass on the plate, such as an accelerometer mass, can also be modeled as a single layer of uniform mass, that is an isotropic layer, by equating the potential energy of the point mass with the potential energy of the uniform mass layer. It is important to note that the mass of the isotropic layer is frequency dependent, and it has no effect on the plate stiffness. The analytical model is validated by comparison to experimental work. The samples studied were aluminum and composite plates of various lengths. The active control predictions were also validated using previous experimental work completed at California Polytechnic State University in San Luis Obispo. These cases included active control of an aluminum beam with a patch of piezoelectric material and an aluminum sailplane with a patch of piezoelectric material. Results indicate that while the analytical mode solutions are in good agreement with the experimental results, they are also systematically higher than the experimental results. The analytical active control solutions match previous work when the piezoelectric effects are linear. The main result of adding an active control system is approximately a 5-10% increase in modal frequencies and a 200-800% increase of damping ratio.

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Kuchan, Abigail. "The integration of active flow control devices into composite wing flaps." Thesis, Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/44758.

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Delaying stall is always an attractive option in the aerospace industry. The major benefit of delaying stall is increased lift during takeoff and landings as well as during high angle of attack situations. Devices, such as fluidic oscillators, can be integrated into wing flaps to help delay the occurrence of stall by adding energized air to the airflow on the upper surface of the wing flap. The energized air from the oscillator allows the airflow to remain attached to the upper surface of the wing flap. The fluidic oscillator being integrated in this thesis is an active flow control device (AFC). One common method for integrating any device into a wing flap is to remove a section of the flap and mechanically secure the device. A current trend in the aerospace industry is the increased use of fiber-reinforced composites to replace traditional metal components on aircraft. The traditional methods of device integration cause additional complications when applied to composite components as compared to metal components. This thesis proposes an alternative method for integration of the AFC devices, which occurs before the fabrication of wing flaps is completed and they are attached to the aircraft wing. Seven design concepts are created to reduce the complications from using current methods of integration on composite wing flaps. The concepts are based on four design requirements: aerodynamics, manufacturing, maintenance, and structure. Four of the design concepts created are external designs, which place the AFC on the exterior surface of the wing flap in two types of grooved channels. The other three designs place the AFC inside the wing flap skin and are categorized as internal designs. In order for the air exiting the AFC to reach the upper surface of the wing flap, slots are created in the wing flap skin for the internal designs. Within each of the seven design concepts two design variants are created based on foam or ribbed core types. Prototypes were created for all of the external design AFC devices and the side inserted AFC and retaining pieces. Wing flap prototypes were created for the rounded groove straight AFC design, the semi-circular groove with straight AFC, and the side inserted AFC designs. The wing flaps were created using the VARTM process with a vertical layup for the external designs. The rounded groove and semi-circular groove prototypes each went through three generations of prototypes until an acceptable wing flap was created. The side inserted design utilized the lessons learned through each generation of the external design prototypes eliminating the need for multiple generations. The lessons learned through the prototyping process helped refine the designs and determine the ease of manufacturing to be used in the design evaluation. The evaluation of the designs is based on the four design requirements stated above. The assessment of the designs uses two levels of evaluation matrices to determine the most fitting design concept. As a result of the evaluation, all four of the external designs and one of the internal designs are eliminated. The two remaining internal designs' foam core and ribbed variants are compared to establish the final design selection. The vertically inserted AFC foam core design is the most fitting design concept for the integration of an AFC device into a composite wing flap.

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Tong, Daqun. "Modeling and optimal shape control of a laminated composite thin plate with piezoelectric acturators surface embedded or bonded." Ohio : Ohio University, 1997. http://www.ohiolink.edu/etd/view.cgi?ohiou1184345824.

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Ghasemzadeh-Barvarz, Massoud. "Quality control of complex polymer materials using hyperspectral imaging associated with multivariate statistical analysis." Doctoral thesis, Université Laval, 2015. http://hdl.handle.net/20.500.11794/26025.

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Dans la première étape de ce travail, des composites formulés à partir d'anhydride maléique greffé polyéthylène (MAPE) et de différentes charges de fibres de chanvre (entre 0 et 60%) ont été produits et analysés par imagerie NIR. Trois méthodes chimiométriques ont été utilisées puis comparées pour la prédiction des propriétés mécaniques, cartographier la distribution des constituants et détecter les défauts physiques des matériaux: la calibration multivariée traditionnelle basée sur la régression PLS, la résolution multivariée de courbes (MCR) et l’analyse d’images et la régression sur les images multivariées (MIA/MIR). Dans la deuxième partie de ce projet, une série de films multicouches complexes (échantillons industriels) ont été étudiés par imagerie NIR combinée à l’analyse d’images multivariée. Le potentiel et l'efficacité de la méthode proposée pour détecter les défauts causés par la (les) couche(s) manquant(es) ont été étudiés pour des films non imprimés et imprimés. Dans la dernière partie, les composites hybrides polypropylène (PP) / fibre de verre / fibre de lin ont été étudiés. L'effet de la teneur en fibres (0 à 40% en volume) et de la composition sur les propriétés mécaniques ont été investigués, ainsi que l’effet de l’exposition à l’eau et la dégradation thermique et aux rayons UV (vieillissement accéléré des matériaux). Les images de microscopie électronique à balayage (MEB) des composites non vieillis ont été analysées en combinant des méthodes d’analyse de texture et des méthodes multivariées. Enfin, l'imagerie NIR a été mise en œuvre sur des composites non vieillis et vieillis afin de prédire leurs propriétés finales ainsi que pour modéliser les variations de composition chimique et celles dues au vieillissement accéléré. En résumé, les résultats montrent que la combinaison de l'imagerie hyperspectrale et des méthodes statistiques multivariées est un outil puissant pour le contrôle de la qualité des composites polymères complexes. De plus, la méthode proposée est rapide et non destructive, elle peut être mise en œuvre en ligne, pour le contrôle de la qualité des matériaux composites. D'autre part, il a été démontré que l'analyse de la texture des images peut être appliquée à la quantification de la dispersion et du degré d’homogénéité de la distribution des charges dans des matériaux composites. In the first step of this work, maleic anhydride grafted polyethylene (MAPE)/hemp fiber composites with different filler concentration between 0 to 60% were analyzed by NIR imaging. Three chemometrics methods including Partial Least Squares (PLS), Multivariate Curve Resolution (MCR) and Multivariate Image Analysis/Multivariate Image Regression (MIA/MIR) were implemented and compared for predicting mechanical properties as well as mapping chemical compositions and material physical variations. In the second part of this project, a series of complex multilayer films (industrial samples) were investigated using NIR hyperspectral imaging and Multivariate Image Analysis (MIA). The potential and effectiveness of the proposed method for detecting defects caused by missing layer(s) were studied for unprinted and printed films. In the final part, polypropylene (PP)/glass/flax hybrid composites were studied. The effect of composition (fiber content between 0 and 40 vol%), as well as water, thermal and UV aging on mechanical properties was investigated. Then, Scanning Electron Microscopy (SEM) images of unaged hybrid composites were analyzed using texture analysis and multivariate methods. Finally, NIR imaging was implemented on unaged and aged composites to predict their final properties as well as to capture chemical composition and aging variations. In summary, the results show that combining hyperspectral imaging and multivariate statistical methods is a powerful tool for quality control of complex polymer composites. Since the proposed method is rapid and nondestructive, one can implement it for on-line quality control of finished plastic products. On the other hand, texture analysis and multivariate methods can be applied for quantifying the mixing aspects of composites.

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Bres, Stéphane. "Contributions a la quantification des criteres de transparence et d'anisotropie par une approche globale : application au controle de qualite de materiaux composites." Lyon, INSA, 1994. http://www.theses.fr/1994ISAL0070.

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L'objectif de cette thèse est de dégager les éléments d'une méthodologie permettant de quantifier les critères globaux de transparence (d'un matériau) et d'anisotropie (d'un ensemble de formes); tout cela est réalisé, de façon automatique, dans le cadre des images à niveaux de gris. Pour appréhender de tels critères, la vision humaine est très performante car elle analyse, très naturellement et de façon simultanée une image à différents niveaux, allant d'une inspection locale des détails à une perception plus globale (ce qui fait sa supériorité dans les cas qui nous concernent). L'approche adoptée ici est donc volontairement globale, pour reproduire au mieux les processus de l'analyse humaine. Des applications pratiques de la quantification de ces critères globaux sont proposées, en particulier sur les matériaux composites pour lesquels on réalise ainsi une avancée en contrôle qualité. Le premier chapitre présente la discrimination de formes par une approche globale en n'utilisant que des paramètres intrinsèques à ces formes ou en normalisant celles-ci au préalable. Le deuxième chapitre présente une méthode originale de quantification de transparence, caractère encore peu étudié. Cette méthode est basée sur l'évaluation de la "lisibilité" d'une mire de test cachée par le matériau à qualifier par corrélation. Enfin, le troisième chapitre présente une étude de la caractéristique Anisotropie. Les aspects locaux et globaux de ce caractère sont abordés. Une nouvelle méthode, applicable sur des images à niveaux de gris et capable d'inspecter l'ensemble des directions de l'image, y est présentée. Elle permet de produire des résultats chiffrés d'anisotropie, très en accord avec les impressions de l’œil humain, ainsi que des roses d'orientations qui visualisent les directions privilégiées The aim of this thesis is to highlight basis toward a methodology able to quantity the global features of transparency (of a material) and anisotropy (of a set of patterns). This work is realised on grey levels images, in an automatic way. The human vision is very performant in catching such features because it analyses, very naturally and simultaneously, a picture at diff~rent levels, from a local inspection of details to a more global perception. This is why human vision beats computer used here is voluntarily global, to reproduce at best the human analysis processes. Practical applications of the quantification of these global features are proposed, especially on composite materials, where it yields a reliable improvement in control quality. The first chapter presents the patterns discrimination by a global approach, using either only intrinsic parameters of these patterns or a previous step of normalization. The second chapter presents a novel method of the quantification of transparency, which is of importance be cause this feature has not been extensively studied in the past. This method has been applied to composite materials study. The main point of this method is a correlation based on lisibility evaluation of a test pattern, supposedly hidden by the material to be qualified. At last, the third chapter presents a study of the anisotropy feature. The local and global aspects of this feature are considered. A new method is presented which can be applied on grey levels images and can inspect ali the image directions. It results in numerical information about anisotropy and roses of orientations which clearly show the principal directions. Our results show similarities when compared to human visual behaviour

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Cerilles, Jeffrey T. (Jeffrey Thomas). "Measurement and control of brake pedal feel quality in automobile manufacturing." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/34839.

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Thesis (M.B.A.)--Massachusetts Institute of Technology, Sloan School of Management; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering; in conjunction with the Leaders for Manufacturing Program at MIT, 2005. Includes bibliographical references (p. 56). Customer perception of brake pedal feel quality, as related to the perception of the brake pedal feeling soft or mushy, depends on both the customer's subjective judgment of quality and the actual build quality of the brake system. This project analyzed the different factors contributing to the soft brake condition using a fishbone diagram. A low cost tool to objectively measure brake pedal feel was developed and tested. Using this tool we found a negative linear correlation between residual air in the brake system and brake pedal feel. Even in the worst-case, a residual air level of 0.9 mL or greater is required before the brake pedal force drops 10%. The air evacuation step in the brake fluid filling process was investigated by the addition of a vacuum accumulator tank, and we found the air evacuation to depend on the brake system cross-sectional area (i.e. tube diameter) and not on the vacuum pressure. Organizational process issues were analyzed, and we found that greater cross-functional communication and collaboration are needed between manufacturing and external groups such as design and marketing. by Jeffrey T. Cerilles. S.M. M.B.A.

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Choi, Ki-Seok. "Service level guarantee in capacitated supply chains." Diss., Georgia Institute of Technology, 2003. http://hdl.handle.net/1853/25583.

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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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Bachman, William Hendricks. "Towards a GIS-based modal model of automobile exhaust emissions." Diss., Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/21762.

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Paul, Noel Michael. "Studies in dendritic secondary structural control." Connect to this title online, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1104365307.

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Thesis (Ph. D.)--Ohio State University, 2005. Title from first page of PDF file. Document formatted into pages; contains xix, 343 p.; also includes graphics (some col.) Includes bibliographical references (p. 325-343).

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Baliso, Unathi. "Partnering with suppliers for quality improvement." Thesis, Cape Peninsula University of Technology, 2010. http://hdl.handle.net/20.500.11838/1232.

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A dissertation submitted in fulfillment of the requirements for the degree Master Technology: Quality in the Faculty of Engineering at the Cape Penisula University of Technology Uneven surfaces on national roads that often lead to difficulty and even danger can be extremely hazardous when wet, due to mud and cracks, and also create dust pollution for motorists, pedestrians, residents and business. The continuing use of low quality raw materials in producing hot mix asphalt for national roads, leads to regular maintenance at a very high cost. The quality aggregates (stone that is used to produce asphalt), and the quality of bitumen are often inadequate for the correct composition of hot mix asphalt. The mst important factors affecting initial and long term performance of the highways is the inferior pavement structure and condition, due to poor aggregates (raw material)from suppliers. The performance of asphalt i s largely determined by the characteristics of its constituents, the asphalt binder and aggregates.

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Thurman-Newell, Jamie A. "Quantification of variation in biological input materials and its effect on manufacture and process control." Thesis, Loughborough University, 2017. https://dspace.lboro.ac.uk/2134/25346.

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Currently cellular therapies, such as hematopoietic stem cell transplantation (HSCT), are produced at a small scale on a case-by-case basis, usually in a clinical or near-clinical setting. Meeting the demand for future cellular therapies will require a robust and scalable manufacturing process that is either designed around or controls the variation associated with biological starting materials. Understanding variation requires both a measure of the allowable variation (that does not negatively affect patient outcome) and the achievable variation (with current technology). The prevalence of HSCT makes it an ideal case study to prepare for more complex biological manufacturing with more challenging regulatory classifications.

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Asselin, Daniel. "Influence des defauts sur les propriétés mécaniques du composite Duralcan F3S.20S /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 1993. http://theses.uqac.ca.

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Wilson, Nicola Dawn. "The application of near infrared spectroscopy to the characterisation and quality control of pharmaceutical materials of natural origin." Thesis, University College London (University of London), 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.274461.

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Wheeler, Jake T. "The effects of vendor and quality control variability in the procurement of raw materials in a bio-pharmaceutical company." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/68901.

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Thesis (M. Eng. in Logistics)--Massachusetts Institute of Technology, Engineering Systems Division, 2011. Cataloged from PDF version of thesis. Includes bibliographical references (p. 65-66). Pharmaceutical companies have traditionally placed little emphasis on supply chain efficiencies and operations costs. With the changing landscape of expiring intellectual property rights and increased market segmentation, the need for improved supplier relations and inventory management is becoming paramount. This thesis presents a study of a procurement system within a biopharmaceutical company. The many sources of variation in delivery lead times from both suppliers and internal departments coupled with variation in manufacturing demand, has resulted in excess raw-material inventory at the company. By using discrete-events-simulation software to model the system and its inputs, we generate insights that can help the materials management team maximize their efforts to improve the system performance. In this particular case, it was found that reducing supplier lead time variability was far more effective in reducing the need for inventory than reducing average lead times or even internal lead times from the Quality Control department. The pharmaceutical company involved in this study would be best served by focusing its efforts on working with suppliers to increase the consistency of delivery for their raw materials. This increased consistency will allow them to reduce total inventory costs by reducing the variability of the raw-material supplies. by Jake T. Wheeler. M.Eng.in Logistics

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Jiménez, Otero Cintia. "Control de qualitat en mètodes d'anàlisi qualitatius i la seva aplicació al control antidopatge." Doctoral thesis, Universitat Pompeu Fabra, 2007. http://hdl.handle.net/10803/7105.

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L'anàlisi qualitatiu ha estat sempre molt important en el control antidopatge i constitueix cada cop més una part molt significativa de l'activitat diària d'altres tipus de laboratoris. Tanmateix, no existeixen guies o documents específics per ajudar els laboratoris a implantar sistemes de qualitat quan es disposa d'aquest tipus de mètodes. L'objectiu general d'aquesta tesi ha estat el desenvolupament de les eines necessàries per assegurar la qualitat i fiabilitat dels resultats produïts per mètodes d'anàlisi qualitatius, treballant en tres aspectes fonamentals per a l'assegurament de la qualitat dels resultats als laboratoris d'anàlisi: la validació de mètodes, el control intern de la qualitat, i els exercicis d'intercomparació. S'ha elaborat un protocol de validació, s'ha implantat un sistema de control intern de la qualitat per a mètodes d'anàlisi qualitatius i, finalment, s'han elaborat protocols per a la preparació de mostres que seran utilitzades com a materials d'assaig en exercicis d'intercomparació o com a materials de referència, i per realitzar estudis d'homogeneïtat i d'estabilitat, que han estat aplicats a l'estudi de l'estabilitat de substàncies d'interès en control antidopatge. Qualitative analysis has been very important in antidoping control and its becoming a significant part of the daily activity of other type of laboratories. However, there is a lack of guidance or specific documents to help laboratories to implement quality assurance systems when using these type of methods. The aim of this thesis has been the development of the necessary tools to ensure the quality and reliability of results released by qualitative analytical methods, working in the three main aspects of quality assurance in the analytical laboratory: method validation, internal quality control and intercomparison exercises. A protocol for method validation has been proposed and an internal quality control system for qualitative methodologies has been established. Finally, protocols for the preparation of samples to be used in intercomparison exercises or as reference materials, including homogeneity and stability studies, have been prepared. These protocols have been applied to study the stability of substances with especial interest in antiodoping control.

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Kelly, Matt. "A COMPARATIVE ANALYSIS OF GREEN ROOF DESIGNS INCLUDING DEPTH OF MEDIA, DRAINAGE LAYER MATERIALS, AND POLLUTION CONTROL MEDIA." Master's thesis, University of Central Florida, 2008. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2304.

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Population growth has lead to an increase in development and impervious areas in urban settings. Post-development conditions cause several problems for stormwater management such as limited space for stormwater storage systems and the conveyance of pollution picked up by runoff to near by water bodies. Green Roofs with cisterns have been shown to attenuate the peak flow of storm events and reduce the pollution load leaving a site and entering nearby water bodies. The purpose of this research is to expand the available research data on green roofs with cisterns by investigating the water quality and hydrology effects of different green roof designs including depth of media, an additional pollution control layer beneath the growth media, and different drainage layer materials. Furthermore, a comparison study is performed on the cistern water quality, direct filtrate water quality, and control roof filtrate water quality. Results show that phosphorus concentrations are lower when using a pollution control layer beneath the growing media, and that evapotransporation and filtrate factor values from the 4-inch media and the 8-inch media are approximately equal for one year. However, hydrograph results show that the 8-inch media design has a lower peak flow and longer attenuation when compared to the 4-inch media design for a single storm event. Furthermore, the drainage layer material has no significant effect on the water quality or hydrology of the green roof discharge. The data also emphasizes the importance and effectiveness of the incorporation of a cistern into a green roof system. M.S.Env.E. Department of Civil and Environmental Engineering Engineering and Computer Science Environmental Engr MSEnvE

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Radwan, Badreddin. "Treatment of a Liquid Al-Si Alloy : Quality Control and Comparison of Two Melt Degassing Processes." Thesis, Tekniska Högskolan, Jönköping University, JTH, Material och tillverkning, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-48236.

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Products manufactured by aluminium casting have become very popular and already replaced many parts that were once produced by iron and steel casting. This trends upwards especially in the automotive industry as it has become extremely important to reduce vehicle weight due to environmental requirements and economical aspects. This popularity of aluminium alloys could be ascribed to their light weights and many other advantages including excellent castability, good corrosion resistance, good thermal and electrical conductivity, good machinability, low melting temperatures and minimal gas solubility with the exception of hydrogen. The most important alloy group among casting alloys is Aluminium Silicon (Al - Si). Al-Si alloys must undergo a specific melt treatment procedure prior to casting. This treatment consists of several steps including degassing of hydrogen, grain refinement and eutectic modification. The aim of this study is to make an assessment of the metal treatment process of an (Al-Si) casting alloy at Unnaryd Modell AB for the purpose of improving the melt conditions and thus the quality of the final product. A rotary degasser provided by Foseco is also tested instead of the traditional tablet degassing method to see if this technique would result in any significant improvement of the melt quality. The results show that Unnaryd modell AB follows a proper treatment routine. It shows moreover that the rotary degassing is superior to the tablet degassing in many aspects including the level of degassing achieved, time efficiency, environmental consideration and personnel security.

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Johnson, Phillip. "Design and automation of MEDUSA (Materials and Electronic Device Universal System Analyzer)." Thesis, This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-03242009-040444/.

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Wei, Wei. "Development of an Effective System Identification and Control Capability for Quad-copter UAVs." University of Cincinnati / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1427813832.

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Boozula, Aravind Reddy. "Use of Bio-Product/Phase Change Material Composite in the Building Envelope for Building Thermal Control and Energy Savings." Thesis, University of North Texas, 2018. https://digital.library.unt.edu/ark:/67531/metadc1248391/.

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This research investigates the bio-products/phase change material (PCM) composites for the building envelope application. Bio-products, such as wood and herb, are porous medium, which can be applied in the building envelope for thermal insulation purpose. PCM is infiltrated into the bio-product (porous medium) to form a composite material. The PCM can absorb/release large amount of latent heat of fusion from/to the building environment during the melting/solidification process. Hence, the PCM-based composite material in the building envelope can efficiently adjust the building interior temperature by utilizing the phase change process, which improves the thermal insulation, and therefore, reduces the load on the HVAC system. Paraffin wax was considered as the PCM in the current studies. The building energy savings were investigated by comparing the composite building envelope material with the conventional material in a unique Zero-Energy (ZØE) Research Lab building at University of North Texas (UNT) through building energy simulation programs (i.e., eQUEST and EnergyPlus). The exact climatic conditions of the local area (Denton, Texas) were used as the input values in the simulations. It was found that the EnergyPlus building simulation program was more suitable for the PCM based building envelope using the latent heat property. Therefore, based on the EnergyPlus simulations, when the conventional structure insulated panel (SIP) in the roof and wall structures were replaced by the herb panel or herb/PCM composite, it was found that around 16.0% of energy savings in heating load and 11.0% in cooling load were obtained by using PCM in the bio-product porous medium.

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Berglund, Lina, Filip Ivarsson, and Marcus Rostmark. "Crucial Parameters for Additive Manufacturing of Metals : A Study in Quality Improvement." Thesis, KTH, Skolan för industriell teknik och management (ITM), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-254785.

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Production by Additive Manufacturing creates opportunities to make customized products in small batches with less material than in traditional manufacturing. It is more sustainable and suitable for niche products, but entails new production demands to ensure quality. The goal of this study is to define the most crucial parameters when creating Additive Manufactured products in metal and suggest tools for quality improvement. This is done by analysing earlier studies and evaluating the standard production procedures for manufacturing by Selective Laser Melting. The results from this study stated that porosity and insufficiencies in shape are the most common factors leading to deviation in quality. To avoid it, the most crucial parameters to consider are; The laser freeform fabrication-system related parameters, hatch distance, laser power, layer thickness, fscanning pattern, scan speed and flowability of the powder. Concluded is also that crucial parameters within additive manufacturing are very dependent on the definition of quality for a certain product and can therefore vary. By continuous collection and analysis of data, the task of improving quality will be simplified. Produktion genom Additiv Tillverkning möjliggör tillverkande av skräddarsydda produkter i små batcher och med mindre material än vid traditionell tillverkning. Det är ett mer hållbart tillverkningssätt och mer passande för nischprodukter, men innebär nya produktionskrav för att säkerhetsställa bra kvalitet. Målet med denna studie är att definiera de viktigaste parametrarna vid Additiv Tillverkning av produkter i metall och föreslå verktyg för att förbättra dem. Detta genom analys av tidigare studier och utvärdering av klassiska produktionsrutiner för Selective Laser Melting. Resultaten från denna studie visar att porositet och formfel är de vanligaste faktorerna som leder till bristande kvalitet. För att undvika detta är de viktigaste parametrarna att ta i beaktande; parametrar kopplade till "laser freeform fabrication"-system, distans mellan laserstrålar, kraft på lasern, lagertjocklek, skanningsmönster, fart på skanningen och flytbarhet på pulvret. Slutsatsen pekar även på att avgörande parametrar inom Additiv Tillverkning beror på definitionen av kvalitet för en speciell produkt och kan därför variera. Genom kontinuerlig insamling och analys av data kommer förbättringen av kvalitet förenklas markant.

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VIANA, VLAMIR. "Caracterização de um dispositivo de ensaio para determinação da camada semirredutora e da filtração com equivalência de qualidade de acordo com a norma ABNT NBR IEC 606001-1-3." reponame:Repositório Institucional do IPEN, 2012. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10138.

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Made available in DSpace on 2014-10-09T12:35:12Z (GMT). No. of bitstreams: 0 Made available in DSpace on 2014-10-09T13:56:40Z (GMT). No. of bitstreams: 0 Dissertação (Mestrado) IPEN/D Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

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Restrepo, Edgar Salom. "Determination of AASHTO Bridge Design Parameters through Field Evaluation of the Rt. 601 Bridge: A Bridge Utilizing Strongwell 36 in. Fiber-Reinforced Polymer Double Web Beams as the Main Load Carrying Members." Thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/36182.

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The Route 601 Bridge in Sugar Grove, Virginia spans 39 ft over Dickey Creek. The Bridge is the first to use the Strongwell 36 in. fiber reinforced polymer (FRP) double web beam (DWB) in its superstructure. Replacement of the old bridge began in June 2001, and construction of the new bridge was completed in October 2001. The bridge was field tested in October 2001 and June 2002. This thesis details the field evaluation of the Rt. 601 Bridge. Using mid span deflection and strain data from the October 2001 and June 2002 field tests, the primary goal of this research was to determine the following AASHTO bridge design parameters: wheel load distribution factor g, dynamic load allowance IM, and maximum deflection. The wheel load distribution factor was determined to be S/5, a dynamic load allowance was determined to be 0.30, and the maximum deflection of the bridge was L/1500. Deflection results were lower than the AASHTO L/800 limit. This discrepancy is attributed to partial composite action of the deck-to-girder connections, bearing restraint at the supports, and contribution of guardrail stiffness. Secondary goals of this research were to quantify the effect of diaphragm removal on girder distribution factor, determine torsion and axial effects of the FRP girders, compare responses to multiple lane symmetrical loading to superimposed single lane response, and compare the field test results to a finite element and a finite difference model. It was found that diaphragm removal had a small effect on the wheel load distribution factor. Torsional and axial effects were small. The bridge response to multilane loading coincided with superimposed single lane truck passes, and curb-stiffening effects in a finite difference model improved the accuracy of modeling the Rt. 601 Bridge behavior. Master of Science

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Lam, Wai-lin, and 藍慧玲. "The impact of ISO 9000 and quality assurance in construction with particular reference to suppliers." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1997. http://hub.hku.hk/bib/B31251493.

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Sousa, Rosane Pontes de. "Anticariogenic in situ effect of different restorative dental materials." Universidade Federal do CearÃ, 2008. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=1358.

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Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico Tooth structure immediately adjacent to restorations is susceptible to secondary caries, which may be caused by imperfect adaptation of restorative materials and subsequent microorganism colonization. Therefore, in order to identify methods of preventing secondary caries and increasing clinical dental restoration durability, different restorative dental materials have been introduced and applied in dental clinics. Thus, this in situ study assessed the effects of different restorative materials on the microbiological composition of dental biofilm and evaluated their ability of protecting the adjacent enamel against acid attacks from bacterial activity. A double-blind, split-mouth design was performed in one phase of 14 days, during which, 20 volunteers wore intra-oral palatal devices with five human enamel slabs, which were extra-orally restored according to the manufacturerâs specifications, using one of the following materials: Filtek Z 250/Single Bond composite resin; Permite amalgam; Fuji II encapsulated resin-modified glass ionomer; Vitremer resin-modified glass ionomer and Ketac Molar conventional glass ionomer.. During the experimental period, all subjects used fluoride-containing dentifrice 3x/day and a 20% sucrose solution was dripped onto the slabs 8x/day in predetermined times. The biofilm formed on the slabs was analyzed to determine total and mutans streptococci as well as lactobacilli counts. Demineralization (delta S) was determined on enamel by cross-sectional microhardness at 20 and 70 -Âm from the restoration margin. In order to verify the differences among the treatments, Kruskal-Wallis and ANOVA followed by Minimum Squares test were applied for cariogenic microbiota and delta S, respectivly. No statistically significant differences were found in the cariogenic microbiota grown on the slabs. At 20-Âm distance, only Fuji II statistically differed from the other groups presenting the lowest demineralization. At 70-Âm, Fuji II significantly inhibited demineralization when compared to Permite, Filtek-Z-250 and Ketac Molar. Concluding, in the background of fluoride dentifrice and under the cariogenic exposure condition of this study, only the encapsulated resin-modified glass ionomer material provided additional protection against secondary caries. A estrutura dentÃria imediatamente adjacente a restauraÃÃes Ã suscetÃvel ao surgimento de cÃrie secundÃria, que pode ocorrer devido a imperfeiÃÃes na adaptaÃÃo de materiais restauradores e subseqÃente colonizaÃÃo por microrganismos. Logo, com o objetivo de identificar os mÃtodos de prevenÃÃo da cÃrie secundÃria e aumentar a longevidade das restauraÃÃes, diferentes materiais restauradores tÃm sido introduzidos e usados na clÃnica odontolÃgica. Desta forma, este estudo in situ avaliou os efeitos de diferentes materiais restauradores na composiÃÃo microbiolÃgica do biofilme dental bem como a habilidade destes materiais em proteger o esmalte adjacente dos ataques Ãcidos provenientes da atividade bacteriana. Foi empregado um delineamento duplo-cego, âsplit-mouthâ realizado em uma fase de 14 dias, durante a qual, 20 voluntÃrios utilizaram dispositivos intra-orais palatinos com cinco blocos de esmalte dental humano que foram restaurados extra-oralmente, de acordo com as recomendaÃÃes do fabricante com um dos seguintes materiais: Resina composta Filtek Z250/Single Bond (grupo controle), AmÃlgama Permite, IonÃmero de vidro modificado por resina encapsulado Fuji II, IonÃmero de vidro modificado por resina Vitremer e IonÃmero de vidro convencional Ketac Molar. Durante o perÃodo experimental, os voluntÃrios utilizaram dentifrÃcio fluoretado, 3 vezes ao dia e gotejaram sobre os blocos, uma soluÃÃo de sacarose a 20%, 8 vezes ao dia em horÃrios prÃ-determinados. No 14o dia, o biofilme formado sobre os blocos foi removido para determinar a contagem de estreptococos totais e estreptococos mutans, bem como lactobacilos. A desmineralizaÃÃo (delta S) ao redor da restauraÃÃo foi avaliada atravÃs da anÃlise de microdureza em corte longitudinal do esmalte a 20 e 70 Âm da margem da restauraÃÃo. Para detectar as diferenÃas entre os tratamentos, foram aplicados os testes Kruskal-Wallis e ANOVA seguida do teste dos quadrados mÃnimos para a microbiota cariogÃnica e delta S, respectivamente. NÃo foram encontradas diferenÃas estatisticamente significativas na microbiota cariogÃnica formada sobre os blocos. Na distÃncia 20 Âm, somente o Fuji II diferiu estatisticamente dos outros grupos apresentando a menor desmineralizaÃÃo. A 70 Âm, o Fuji II inibiu significativamente a desmineralizaÃÃo quando comparado ao Permite, Filtek-Z-250 e Ketac Molar. Conclui-se que na situaÃÃo de uso de dentÃfricio flouretado associada ao desafio cariogÃnico do presente estudo, somente, o ionÃmero de vidro modificado por resina encapsulado apresentou uma proteÃÃo adicional contra o desenvolvimento de cÃrie secundÃria

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PETRONI, ROBSON. "Validação dos métodos de análise por ativação do Laboratório de Análise por Ativação Neutrônica do IPEN - CNEN/SP visando à produção de materiais de referência certificados." reponame:Repositório Institucional do IPEN, 2015. http://repositorio.ipen.br:8080/xmlui/handle/123456789/23829.

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Submitted by Claudinei Pracidelli (cpracide@ipen.br) on 2015-07-23T11:19:49Z No. of bitstreams: 0 Made available in DSpace on 2015-07-23T11:19:49Z (GMT). No. of bitstreams: 0 Dissertação (Mestrado em Tecnologia Nuclear) IPEN/D Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

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Rarani, Manelisi. "Quality assurance in low-cost housing construction projects in the metropole." Thesis, Cape Peninsula University of Technology, 2013. http://hdl.handle.net/20.500.11838/2054.

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Thesis (MTech (Business Administration))--Cape Peninsula University of Technology, 2013. In 1994, the South African government introduced low-cost housing construction through Reconstruction and Development Programme. The programme was intended to improve the quality of lives of the country's citizens. Many communities across the country benefited from the programme. However, concerns regarding the quality of low-cost housing produced through this programme have been raised. The programme has produced low-cost housing with many structural defects such as gaping wall cracks, roof leaks, unstable roof, water penetration and seepage. To protect the beneficiaries of low-cost housing against the inferior workmanship, unsuitable material and inappropriate construction methods, building standards and regulations have been introduced. The low-cost housing inspectors have been given power to enforce and ensure that the building standards and regulations are followed and met by low-cost housing contractors. Regardless of the measures, the programme still produces low-cost housing built with many structural problems. Hence, the researcher has conducted a research to assess the effectiveness and adequateness that inspection process contributes to quality assurance in low-cost housing construction projects in the Metropole. The findings of the research provided an overall low-cost housing inspectors' experience in the construction industry, education, training, knowledge, roles and responsibilities and the perception of the low-cost housing inspectors on the current housing inspection. The primary conclusion of this research suggest that the low-cost housing inspectors lack training in housing inspection, are not aware of their roles and responsibilities and lack knowledge in building standards and regulations. This resulted to failure to enforce and ensure that the contractors comply with building standards and regulations during the low-cost housing construction projects in the Metropole. The primary recommendations are to establish a standard continuous training and education for low-cost housing inspectors. Provide courses and training to improve the level of knowledge of building standards and regulations by low-cost housing inspectors and review the roles and responsibilities of low-cost housing inspectors and establish awareness of them among the affected parties.

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Neely, William Douglas. "Evaluation of the In-Servic Performance of the Tom's Creek Bridge." Thesis, Virginia Tech, 2000. http://hdl.handle.net/10919/33249.

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The Tom's Creek Bridge is a small-scale demonstration project involving the use of fiber-reinforced polymer (FRP) composite girders as the main load carrying members. The project is intended to serve two purposes. First, by calculating bridge design parameters such as the dynamic load allowance, transverse wheel load distribution and deflections under service loading, the Tom's Creek Bridge will aid in modifying current AASHTO bridge design standards for use with FRP composite materials. Second, by evaluating the FRP girders after being exposed to service conditions, the project will begin to answer questions about the long-term performance of these advanced composite material beams when used in bridge design. This thesis details the In-Service analysis of the Tom's Creek Bridge. Five load tests, at six month intervals, were conducted on the bridge. Using mid-span strain and deflection data gathered from the FRP composite girders during these tests the above mentioned bridge design parameters have been determined. The Tom's Creek Bridge was determined to have a dynamic load allowance, IM, of 0.90, a transverse wheel load distribution factor, g, of 0.101 and a maximum deflection of L/488. Two bridge girders were removed from the Tom's Creek Bridge after fifteen months of service loading. These FRP composite girders were tested at the Structures and Materials Research Laboratory at Virginia Tech for stiffness and ultimate strength and compared to pre-service values for the same beams. This analysis indicates that after fifteen months of service, the FRP composite girders have not lost a significant amount of either stiffness or ultimate strength. Master of Science

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Alcantara, Michael Steinhorst. "Avaliação de biodigestor tubular na degradação anaeróbia de cama de frango de corte." Universidade Estadual do Oeste do Parana, 2012. http://tede.unioeste.br:8080/tede/handle/tede/399.

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Made available in DSpace on 2017-05-12T14:48:32Z (GMT). No. of bitstreams: 1 Michael.pdf: 1358064 bytes, checksum: 7b7dc640218999c74c7f3b747a92d228 (MD5) Previous issue date: 2012-02-20 In the twenty-first century, the broiler production has increased in the world and continues increasing due to the high consumption of this meat. The broiler litter is the largest amount of waste generated in poultry production. It is also characterized by its high concentration of organic matter. The broiler production integrated system defines a radius around it to settle down poultry farms in order to reduce costs. It has also increased the concentration of broiler litter in the producing regions and demanded waste treatment. So, the anaerobic digestion has come as an alternative treatment with high organic load removal. Thus, this trial aimed at evaluating the treatment capacity of broiler litter by anaerobic digestion into tubular biodigester with a semi-continuous flow. The applied treatments varied both the amount of added total volatile solids, from 2.93 to 3.72%, as well as the hydraulic retention time, from 11.60 to 28.40 days. The digesters were maintained at 27 ºC and considered stabilized when the removal efficiency of total solids, total volatile solids and chemical oxygen demand were according to the statistical quality control. Once stabilized, the 11 digesters of 0.6 m per 0.15 m (length per diameter) were evaluated for removal of solids and chemical oxygen demand with statistical quality control and design composite central rotational in a factorial design (22), at two levels (-1, 1), plus the axial points (-α, α) and the central point. The analysis of statistical quality control showed that the treatment with 3.32% added total volatile solids and 20 days of hydraulic retention time removed the highest amount of total solids (64.37%) and total volatile solids (72.38%), while the removal values of chemical oxygen demand were similar in all treatments, around 80%. Significant statistical models were registered with the central composite rotational design to remove total solids and for chemical oxygen demand. No século XXI, a produção de frangos de corte ganhou espaço no mercado e continua crescendo, devido ao alto consumo da carne. A cama de frango é o resíduo gerado em maior quantidade na produção de frangos e caracteriza-se pela elevada concentração de matéria orgânica. O sistema de produção de frango de corte das empresas integradoras delimita um raio ao seu redor para implantação de aviários, visando à redução de custos, além de ocasionar a concentração de cama de frango nas regiões produtoras e gerar a necessidade de tratar o resíduo. A digestão anaeróbia é uma alternativa de tratamento, com alta remoção de carga orgânica. Logo, o objetivo deste trabalho foi avaliar a capacidade de tratamento da digestão anaeróbia da cama de frango em biodigestor tubular de fluxo semicontínuo. Os tratamentos aplicados variaram tanto a quantidade de sólidos totais voláteis adicionados, de 2,93 a 3,72% como o tempo de detenção hidráulica, de 11,60 a 28,40 dias. Os biodigestores foram mantidos a 27 ºC e considerados estabilizados quando as eficiências de remoção de sólidos totais, sólidos totais voláteis e demanda química de oxigênio encontraram-se dentro do controle estatístico de qualidade. Depois de estabilizados, os onze biodigestores de 0,60 m por 0,15 m (comprimento x diâmetro) foram avaliados quanto à remoção de sólidos e à demanda química de oxigênio com o controle estatístico de qualidade. O delineamento composto central rotacional foi em esquema fatorial (22), em dois níveis (1, +1), mais os pontos axiais (-α, +α) e o ponto central. A análise do controle estatístico de qualidade mostrou que o tratamento com 3,32% de sólidos totais voláteis adicionados e 20 dias de tempo de detenção hidráulica foi o que mais se destacou na remoção de sólidos totais (64,37%) e sólidos totais voláteis (72,38%) e os valores de remoção de demanda química de oxigênio foram próximos em todos os tratamentos, em torno de 80%. Com o delineamento composto central rotacional, foram verificados modelos estatísticos significativos para a remoção de sólidos totais e demanda química de oxigênio.

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ALCARDE, LAIS F. "Estudo de radiomarcação com gálio-68 do inibidor de PSMA baseado em ureia - avaliação comparativa de método automatizado e não automatizado." reponame:Repositório Institucional do IPEN, 2016. http://repositorio.ipen.br:8080/xmlui/handle/123456789/26945.

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Submitted by Marco Antonio Oliveira da Silva (maosilva@ipen.br) on 2016-12-22T16:27:41Z No. of bitstreams: 0 Made available in DSpace on 2016-12-22T16:27:41Z (GMT). No. of bitstreams: 0 Os métodos para o diagnóstico clínico de câncer de próstata incluem o toque retal e a dosagem do antígeno prostático específico (PSA). Entretanto, o nível de PSA encontra-se elevado em cerca de 20 a 30% dos casos relacionados a patologias benignas, o que resulta em falsos positivos e leva os pacientes a realização de biópsias desnecessárias. O antígeno de membrana prostático específico (PSMA), ao contrário, é sobre expresso no câncer de próstata e encontrado em baixos níveis em órgãos saudáveis. Em razão disso, estimulou-se o desenvolvimento de pequenas moléculas inibidoras do receptor de PSMA, que carreguem agentes de imagem ao tumor e que não sejam prejudicadas pela microvasculatura deste. Estudos recentes sugerem que o quelante HBED-CC contribui intrinsicamente para a ligação do peptídeo inibidor de PSMA baseado em ureia (Glu-ureia-Lys) ao grupo farmacofórico. Este trabalho descreve os estudos de otimização das condições de radiomarcação do PSMA-HBED-CC com 68Ga, utilizando sistema automatizado (módulo de síntese) e método não automatizado, buscando estabelecer uma condição adequada de preparação deste novo radiofármaco, com ênfase no rendimento da marcação e na pureza radioquímica do produto. Também objetivou avaliar a estabilidade do peptídeo radiomarcado em condições de transporte e estudar a distribuição biológica do radiofármaco em camundongos sadios. O estudo dos parâmetros de radiomarcação possibilitou definir um método não automatizado que resultou em alta pureza radioquímica (> 95%), sem a necessidade de purificação do radiomarcado. Já o método de marcação automatizado foi adaptado para utilizar módulo de síntese e software já disponíveis no IPEN, e também resultou em rendimento de síntese elevado (≥ 90%) e superior aos descritos em literatura, com a vantagem associada de maior controle do processo produtivo em atendimento aos requisitos de Boas Práticas de Fabricação. O estudo dos parâmetros de radiomarcação permitiu a obtenção do PSMA-HBED-CC-68Ga com atividade específica superior à utilizada em estudos clínicos publicados (≥ 140,0 GBq/μmol), com estabilidade suficientemente longa, que permitirá o transporte às clínicas para aplicação na obtenção de imagens diagnósticas. Os perfis de biodistribuição e farmacocinético do peptídeo radiomarcado foram compatíveis com os encontrados na literatura. Conclui-se que o PSMA-HBED-CC-68Ga, é uma importante ferramenta de diagnóstico do câncer de próstata por imagem PET, pode ser produzido tanto por método automatizado ou não automatizado, com alta pureza radioquímica, alto rendimento de síntese e estabilidade do radiofármaco. Dissertação (Mestrado em Tecnologia Nuclear) IPEN/D Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP

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Wu, Lulu. "Virus retentive filter paper for processing of plasma-derived proteins." Licentiate thesis, Uppsala universitet, Nanoteknologi och funktionella material, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-419899.

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The studies in the present thesis explored the feasibility of using nanocellulose-based filters in virus removal filtration of plasma-derived proteins. In Paper I, two-step nanofiltration of commercially available human serum albumin (HSA) product, which was diluted to 10 g L-1 by phosphate buffer saline (PBS) and adjusted pH to 7.4, was performed to remove soluble protein aggregates and reduce filter fouling. The two-step filtration of HSA employed nanocellulose-based filters of varying thickness, i.e. 11 μm and 22 μm filters. The removal of HSA aggregates during filtration through 11 μm pre-filters dramatically improves the flow properties of the 22 μm filter, enabling high protein throughput and high virus clearance. A distribution of pore sizes between 50 nm and 80 nm, which is present in the 11 μm filter and is absent in the 22 μm filter, plays a crucial part in removing the HSA aggregates. With respect to virus filtration, 1 bar constant trans-membrane pressure filtration shows poor removal ability of ΦX174 bacteriophage (28 nm), i.e., log10 reduction value (LRV) ≤ 3.75, while that at 3 bar and 5 bar achieves LRV[MOU1] [LW2] > 5 model virus clearance and overall rapid filtration. Removal of protein aggregates during bioprocessing of HSA products is key to improving the filtration flux, which makes it possible to apply virus removal filtration for HSA to ensure its virus safety. In Paper II, nanofiltration of human plasma-derived intravenous immuno-globulin (IVIG) intermediate (11.26 g L-1, pH 4.9) was carried out to demonstrate high product recovery and high model virus clearance. Virus removal filtration of industrial-grade human IVIG was achieved using 33μm filters at both low (60 Lm-2) and high (288 Lm-2) volumetric load. No changes in IVIG structure were detected and high product recovery was recorded. High virus clearance (LRV ≥ 5-6) was achieved for the small-size model viruses (ΦX174 and MS2 bacteriophages) during the load volume of 60 Lm-2. Side-by-side comparisons with commercial virus removal filters suggest that the nanocellulose-based filter paper presents great potential for industrial bioprocessing of plasma-derived IVIG. In Paper III, process analytical technology (PAT) approach was employed to identify the critical filter parameters, e.g. thickness, basis weight, pore size, and flux, affecting model virus removal efficiency using filters produced by different hot presses. The quality parameters were analyzed with ANOVA and Shewhart charts. Compared with other studied parameters, the hydraulic flux appears as the most relevant final product quality attribute of the nanocellulose-based filter paper to reflect the virus removal efficiency. In particular, a 15% higher flux may be associated with a 0.5-1.0 log10 reduced virus clearance (p=0.007). The results are highlight the importance of continued systematic studies in quality assurance using statistical process control tools [MOU1]Define LRV [LW2]Defined in the line above

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Bur, Nicolas. "Développement d’algorithmes de réduction de modèles pour l’optimisation du procédé de placement de fibres robotisé." Thesis, Compiègne, 2015. http://www.theses.fr/2015COMP2186/document.

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La réalisation par des procédés robotisés de pièces composites à destination, notamment, de l’aéronautique vise à en augmenter la productivité. Cependant le Placement de Fibres Robotisé (PFR) est encore en phase de maturation et requiert de nombreux développements, en particulier dans le cas des composites à matrice thermoplastique ou à fibre sèche. Dans cette thèse, nous proposons différents outils qui permettent in fine de déterminer à l’avance la meilleure puissance de chauffe pour la mise en œuvre de ces composites. La difficulté réside dans le fait que cette puissance dépend de nombreux paramètres, non seulement au niveau de la matière utilisée (densité, chaleur spécifique. . .), mais encore au niveau du procédé lui-même (vitesse de déplacement, nombre et orientation des plis. . .). Nous avons construit un modèle réduit multi-paramétrique en utilisant la technique appelée Proper Generalised Decomposition (PGD). Les résultats ont été confrontés à ceux obtenus par des méthodes plus conventionnelles et aussi à des données expérimentales Realising composite parts mainly dedicated to aeronautics sector by robotised processes tends to increase productivity. However, Automated Tape Placement (ATP) is still in ripening stage and requires various developments, particularly in case of thermoplastic composites or dry fibres. In this manuscript, we propose different tools allowing to determine in advance the best heating power to drape composite fibres. Difficulty arises from dependence on many parameters, from material (density, specific heat) or from process itself (velocity, number and orientation of plies). Therefore we construct a multi-parametric reduced order model using the so called Proper Generalised Decomposition (PGD). Results have been faced to those obtained from more conventional methods but also to experimental data

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Ribeiro, Lorrane Pereira. "Modelagem estocástica de estruturas compósitas incorporando circuitos Shunt para o controle passivo de vibrações." Universidade Federal de Uberlândia, 2015. https://repositorio.ufu.br/handle/123456789/15008.

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Fundação de Amparo a Pesquisa do Estado de Minas Gerais Engineering composite structures containing piezoelectric elements coupled with the so-named shunt circuits, with the aim of passive vibration attenuation, are characterized by inherent uncertainties in their parameters, which can affect significantly performance of the passive shunt circuit. In this context, this work presents the stochastic finite element modeling of a composite structure containing piezoelectric element to be coupled with a shunt circuit, in such a way, that uncertain parameters such as the fiber s orientation, layer thicknesses and the resistance and inductance in the shunt circuit are assumed as uncertain variables and, their corresponding dispersion, is characterized in the stochastic response by propagating the uncertainties into the model. First, the deterministic electromechanical problem is modeled by combining the First-Order Shear Deformation Theory and the concept of Equivalent Single Layer, in order to approximate the mechanical displacement fields, with the so-called Layerwise Theory used to model the discrete electric fields within the composite element. In the sequence, the shunt circuits coupled to the piezoelectric element are introduced in the model. The deterministic finite element modeling procedure was performed taking into the parameterization process of the design variables of interest to be further assumed as random variables in a straightforward way. In the present stochastic finite element modeling procedure, the uncertain variables are modeled as Gaussian stochastic homogeneous fields and discretized according to the Karhunen-Loève expansion method, with the aim of generating the exact stochastic matrices. The obtained results, in terms of the envelopes of the frequency response functions for a composite beam incorporating piezoelectric material coupled with a shunt circuit, demonstrate the interest in considering the uncertainties in the preliminary design phase of the shunt circuits to control the undesired vibrations. Estruturas compósitas em engenharia contendo elementos piezelétricos acoplados a circuitos elétricos shunt, para fins de atenuação passiva dos níveis de vibração, apresentam incertezas inerentes em seus parâmetros de projeto, as quais, podem afetar significativamente a eficiência dos circuitos elétricos passivos. Neste contexto, este trabalho apresenta a modelagem por elementos finitos estocásticos de uma estrutura em material compósito laminado contendo elemento piezelétrico acoplado a circuitos elétricos shunt, de modo que, parâmetros incertos, como direções das fibras, espessuras das camadas e a resistência e indutância do circuito shunt, são assumidos como sendo variáveis aleatórias e, a dispersão destas variáveis, é caracterizada nas respostas estocásticas obtidas após a propagação das incertezas no modelo. Desta forma, realiza-se em um primeiro momento a modelagem do problema eletromecânico determinístico. Para tal, há combinação das teorias de Deformação Cisalhante de Primeira Ordem e da Camada Equivalente Única para aproximação dos campos de deslocamentos mecânicos, com a Teoria Layerwise, que utiliza o conceito de Camadas Equivalentes Discretas na consideração dos campos elétricos, os quais, são assumidos discretos ao longo da espessura da estrutura do laminado. Na sequência, faz-se a inclusão dos circuitos elétricos shunt no modelo eletromecânico. A modelagem determinística é realizada de forma parametrizada para que se possa realizar a introdução a posteriori das incertezas no modelo de forma mais eficiente. Utilizando-se do Método dos Elementos Finitos Estocásticos, os parâmetros fatorados das matrizes e os elementos do circuito são considerados como variáveis aleatórias e modelados como campos homogêneos estocásticos gaussianos. Estes campos são então discretizados de acordo com o método de expansão em série de Karhunen-Loève, onde são geradas as matrizes estocásticas exatas do sistema eletromecânico via modificação do processo de integração pelas funções de covariância. Os resultados obtidos, em termos dos envelopes das respostas em frequência para uma viga compósita contendo um elemento piezelétrico acoplado ao circuito shunt, evidenciam a importância de se considerar as incertezas durante as fases de concepção inicial e/ou pré-projeto de sistemas dinâmicos incorporando circuitos shunt para o controle passivo de vibrações. Mestre em Engenharia Mecânica

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Quevedo, Valéria Ramos Baltazar. "Estudo de composição para concreto extrudável para pré fabricados." Universidade Tecnológica Federal do Paraná, 2013. http://repositorio.utfpr.edu.br/jspui/handle/1/999.

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Capes Bem estabelecido e amplamente utilizado nas indústrias de polímeros e cerâmicas, o processo de extrusão vem sendo também explorado pela indústria de concreto. Embora a indústria de pré fabricados estruturais de concreto utilize superplastificantes, ainda não existem ensaios específicos para caracterizar o comportamento no estado fresco de concretos utilizados para extrusão. Foi observado que, mesmo em empresas de grande porte, a avaliação consiste no ensaio de abatimento em tronco de cone e na experiência intuitiva de um funcionário ao manipular o concreto com uma pá manual. No entanto o lançamento do concreto nos moldes é realizado por máquinas extrusoras que possuem maior força e constância na aplicação. Assim, a extrudabilidade do concreto é baseada no ensaio de “slump test” e na avaliação pessoal do operador, sendo confirmado num lote piloto no próprio processo industrial. Este trabalho teve como base o processo de fabricação de telhas extrudadas autoportantes. Visando simular algumas condições do processo de produção, foi realizada uma adaptação do ensaio da caixa-L, no qual foi inserido um vibrador de mangote no reservatório da caixa. O ensaio consistiu em avaliar o comportamento do concreto ao ser inserido no reservatório da caixa-L e logo após a abertura da comporta, com e sem vibração prévia do concreto no reservatório, para assim melhor definir um procedimento de ensaio. Para uma análise reológica foi proposta a realização de ensaio de squeeze-flow, realizado com argamassa e concreto da dosagem de concreto para extrusão. Foram utilizadas as mesmas configurações do ensaio utilizado para a argamassa: máquina de ensaio do tipo universal, célula de carga de 2000 N, prato superior e amostra, ambos com 10 cm de diâmetro, deformação livre, e com o diâmetro do punção igual ao diâmetro da amostra. Ensaios para adaptação da altura da amostra (5 cm) foram realizados de modo a evitar que ao invés de se deformar por cisalhamento ocorresse a compressão simples da brita. Foi realizada caracterização das matérias primas e testes de compactação, que determinaram a melhor proporção entre a areia fina natural, areia artificial e brita nas seguintes proporções: 25%: 25%: 50% e 0%: 50%: 50%, em massa. Para cada uma destas proporções, foram determinadas composições para o concreto com valores de “m” variando de 4,0, 4,5 e 5,0, que reduzem a quantidade de cimento em até 16%. Utilizou- se aditivo superplastificante de 3a geração à base de Policarboxilato. Para definir os teores de aditivo, foi realizado ensaio de slump test, referência na indústria para escolha de composição, definindo assim as 16 composições para estudo. A realização do ensaio possibilitou criar uma metodologia para verificar o comportamento do concreto sobre vibração, fornecendo informações tais como: aparência, coesão, tixotropia e o perfil do fluxo. Isso pode permitir realizar ajustes reais de trabalhabilidade do concreto com base nas características do processo de produção e perfil da peça extrudada. A análise reológica verificou que as condições de fluxo sofridas pela argamassa não são mantidas para o concreto, principalmente quanto à coesão e aderência. Outros fatores também foram observados, como a segregação, exsudação e comportamento ao longo do tempo. Os resultados mostram que ocorrem diferenças significativas, sendo que algumas características apresentadas na argamassa não se reproduzem no concreto. Ensaios de resistência mecânica à compressão mostraram que todas as composições atendem ao valor mínimo previsto em norma e quanto à trabalhabilidade observou-se que as composições somente com areia artificial apresentaram falta de coesão, perceptível no ensaio de slump test. Definiu-se o ensaio de caixa-L adaptado com vibração prévia como melhor procedimento de ensaio. Os resultados mostraram que mesmo composições com abatimento nulo, que seriam descartadas pela indústria, apresentaram trabalhabilidade e fluíram com vibração, sendo que os teores de aditivo influenciaram no perfil e no tempo do escoamento. A well established and widely used in the industries of ceramics and polymers, the extrusion process has been also explored by the concrete industry. Although the industry of prefabricated structural concrete using superplasticizers, there are still no specific tests to characterize the behavior in the fresh concrete used for extrusion. Although the industry prefabricated concrete structural use superplasticizers, there're not no specific tests to characterize the behavior of the fresh concrete used for extrusion. It was observed that, even in large companies, the evaluation consists of the slump test in truncated cone and the intuitive experience of an employee to handle the concrete with a shovel manual. However the concrete cast in molds is done by extruding machines that have greater strength and consistency in application. Thus extrudability of concrete is based on the testing of "slump test" and the personal evaluation of the operator, being confirmed in a pilot batch in industrial process itself. This work was based on the manufacturing process of extruded tiles freestanding. Aiming to simulate some of the conditions of the production process, there was an adaptation of the test box-L, which was inserted in the reservoir hose vibrator housing. The test consisted in assessing the behavior of the concrete to be inserted into the reservoir from the L-box and immediately after opening the gate, with and without prior vibration of concrete in the tank, so as to better define a test procedure. For a rheological analysis was proposed to carry out squeeze flow test conducted with concrete mortar and concrete strength for extrusion. We used the same settings as used for the test mortar testing machine universal type, load cell 2000 N, and sample top plate, both 10 cm in diameter, free deformation, and the punch diameter equal to the diameter sample. Assays for adjusting the height of the sample (5 cm) were made in order to avoid that instead of being deformed by the compressive shear occur in the gravel. Was performed characterization of raw materials and compression testing which determined the best ratio between the fine sand natural, artificial sand and gravel in the following proportions: 25%: 25%: 50% to 0%: 50%: 50% by mass. For each of these ratios were determined for concrete compositions with values of "m" ranging from 4.0, 4.5 and 5.0, which reduces the amount of cement up to 16%. We used superplasticizer 3rd generation based Polycarboxylate. To set the content of admixture slump test was performed test, the industry benchmark for the choice of composition, thereby setting the 16 estudo.Para compositions for each of these ratios were determined for concrete compositions with values of "m" varying from 4.0, 4.5 and 5.0, which reduces the amount of cement up to 16%. We used superplasticizer 3rd generation based Polycarboxylate. The main test possible to create a methodology to assess the behavior of concrete on vibration, providing information such as: appearance, cohesion, thixotropy and flow profile. This can make adjustments allow real concrete workability based on the characteristics of the production process and extruded profile part. The rheological analysis verified that the flow conditions experienced by the cement is not retained in the concrete, especially in regard to cohesion and adhesion. Other factors were also observed, such as segregation, exudation and behavior over time. The results show that significant differences occur, and some features disclosed in the mortar on the concrete not reproduced. Testing of mechanical strength showed that all compositions meet the minimum standards set out in and about the workability was observed that the compositions only with artificial sand showed a lack of cohesion noticeable slump test. Set up the test L-box pre adapted as best vibration test procedure. The results showed that even compositions with zero rebate which would be discarded by the industry had flowed workability and vibration, and the admixture levels and influence the time profile of the flow.

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Dissertations / Theses on the topic 'Composite materials – Quality control'

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