Дисертації з теми "PIC method"
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Chen, Qiang. "Development of a full particle PIC method for simulating nonlinear wave-structure interaction." Thesis, University of Bath, 2017. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.760902.
Повний текст джерелаАнотація:
During the past few decades, Computational Fluid Dynamics (CFD) modelling hasbecome very popular in the coastal and offshore engineering community. Both Eulerianand Lagrangian methods have achieved great successes; typical examples are thegrid-based OpenFOAM® model and the meshless Smoothed Particle Hydrodynamics(SPH) method based model (e.g. SPHysics). While the former tends to be moreefficient and has advantages in enforcing incompressibility and boundary conditionsvia use of a grid, the latter is more suitable for handling large free-surface deformationsusing particles. In an attempt to combine the advantages of both methods, theParticle-In-Cell (PIC) method was devised through a combined use of particles andgrid. However, so far this hybrid method has not been very well exploited for use inthe coastal and offshore engineering field, where modelling complex wave-structureinteraction with computational efficiency still remains an important challenge. This thesis develops a novel "full particle" PIC based numerical model that solves theincompressible Newtonian Navier-Stokes equations for single-phase free-surface flowswith an emphasis on fluid-structure interaction. The use of the phrase "full particle"here indicates that all of the fluid properties, such as the mass and momentum,are assigned only to the particles, rather than being split between the particles andgrid as is the case in "classical" PIC. The novelty of the model lies in the fact thatthe particles are employed to solve the nonlinear advection term and track the fluidconguration (including the free surface), while the underlying grid is solely usedfor computational convenience for solving the non-advection terms. In addition, atailored Distributed Lagrange Multiplier method and a Cartesian cut cell based two-waystrong coupling algorithm are incorporated for fluid-structure interaction. Themodel is developed in both two and three spatial dimensions, and the 3D modelis parallelised using the Message Passing Interface (MPI) approach. The model isvalidated using benchmark tests in the coastal and offshore engineering field withsimulating nonlinear wave-structure interaction being the principal interest. It isshown that the present "full particle" PIC model is flexible, efficient (in terms ofCPU cost) and accurate when modelling complex free-surface flows and the violentinteraction of such flows with (surface-piercing) structures of arbitrary shape anddegree of freedom. With new innovations, the model has great potential to become ahigh quality numerical tool for use in coastal and offshore engineering applications.
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Yager, Kolton Jacob. "GPU High-Performance Framework for PIC-like Simulation Methods Using the Vulkan® Explicit API." DigitalCommons@CalPoly, 2021. https://digitalcommons.calpoly.edu/theses/2284.
Повний текст джерелаАнотація:
Within computational continuum mechanics there exists a large category of simulation methods which operate by tracking Lagrangian particles over an Eulerian background grid. These Lagrangian/Eulerian hybrid methods, descendants of the Particle-In-Cell method (PIC), have proven highly effective at simulating a broad range of materials and mechanics including fluids, solids, granular materials, and plasma. These methods remain an area of active research after several decades, and their applications can be found across scientific, engineering, and entertainment disciplines.
This thesis presents a GPU driven PIC-like simulation framework created using the Vulkan® API. Vulkan is a cross-platform and open-standard explicit API for graphics and GPU compute programming. Compared to its predecessors, Vulkan offers lower overhead, support for host parallelism, and finer grain control over both device resources and scheduling. This thesis harnesses those advantages to create a programmable GPU compute pipeline backed by a Vulkan adaptation of the SPgrid data-structure and multi-buffered particle arrays. The CPU host system works asynchronously with the GPU to maximize utilization of both the host and device. The framework is demonstrated to be capable of supporting Particle-in-Cell like simulation methods, making it viable for GPU acceleration of many Lagrangian particle on Eulerian grid hybrid methods. This novel framework is the first of its kind to be created using Vulkan® and to take advantage of GPU sparse memory features for grid sparsity.
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Hammel, Jeffrey Robert. "Development of an unstructured 3-D direct simulation Monte Carlo/particle-in-cell code and the simulation of microthruster flows." Link to electronic thesis, 2002. http://www.wpi.edu/Pubs/ETD/Available/etd-0510102-153614.
Повний текст джерела
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PEIRETTI, PARADISI BENEDETTA. "Study on Coulomb explosion induced by laser-matter interaction and application to ion acceleration." Doctoral thesis, Politecnico di Torino, 2019. http://hdl.handle.net/11583/2739923.
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Mirzai, Amin. "Feasibility Study of Hall Thruster's Wall Erosion Modelling Using Multiphysics Software." Thesis, Luleå tekniska universitet, Institutionen för system- och rymdteknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-315.
Повний текст джерелаАнотація:
The most common type of electric propulsion in space exploration is the Hall Effect Thruster (HET), mainly due to its high specific impulse and high thrust to power ratio. However, uncertainties about the thruster's lifetime prediction have prevented widespread integration of HETs. Among these limitations, wall erosion of acceleration channel is of greatest concern. The experimental methods of erosion are time consuming and costly, and they are often limited to one single configuration. Hence, developing a computational model not only decreases the costs but also shortens the design time of a HET. This thesis investigates the feasibility of a uid erosion modelling with a multi-physics software (COMSOL) to further decrease the time and the development cost. First of all, this thesis provides an overview of available plasma modelling techniques and the physics behind the erosion phenomenon. Moreover, the effective parameters and available modules in the multiphysics software as well as their theoretical background were studied and discussed in detail. The Electron Anomalous phenomenon and pressure instability are determined as the main limiting factors for such a model. A non-magnetized model is included to find an optimal value for pressure and to reduce the probability of pressure instability occurrence in magnetized model. To fulfill this task, several simulations for various pressure values (0.005 Torr, 0.05 Torr, and 0.5 Torr) were conducted. Next, the simulation of magnetized/full model has been carried out with addition of magnetic coils in non-magnetized model. To avoid the Electron Anomalous phenomenon, the Bohm diffusion approach was implemented. In addition, a full Particle-In-Cell (PIC) simulation of a typical HET (SPT-100) with the similar input parameters as in fluid model was conducted, and the results were compared and validated using experimental data. The PIC model was intended to be utilized to investigate the accuracy of erosion model in multiphysics software. The results of this thesis indicate that current application of erosion model in COMSOL is not possible whilst high accuracy of the erosion model based on PIC approach can be achieved. Finally, the application of semi-empirical method through direct input of magnetic field data can allow short time simulation of a HET in COMSOL to gain insight about the preliminary behaviour of plasma, however, the simulation of an erosion model requires either a built-in PIC algorithm in COMSOL or a PIC based code.
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Kärrfelt, Erik, and Felix Hardell. "Investigation of a Novel Pick-and-Place Method." Thesis, KTH, Skolan för industriell teknik och management (ITM), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-279481.
Повний текст джерелаАнотація:
Acoustic levitation is a versatile and promising tool for object manipulation that has been improved signicantly in recent years. This master's thesis explores the potential use of acoustic levitation in surface-mount technology. By coordinating several ultrasonic transducers an acoustic eld can be generated that can lift and manipulate small bodies without any physical contact. Earlier research in the area has demonstrated dierent arrangements for how the transducers can be placed. Two of these methods, each with 256 transducers, have been built and compared during this project. One arrangement can levitate bodies with higher density, while the other arrangement has provided a stronger lateral stability. An idea for future work is to combine the two arrangements to reach a solution that could potentially be used in surface-mount technology.Akustisk levitation ar en mångsidig och lovande teknik som utvecklats markant under de senaste åren. Detta examensarbete undersöker potentialen som akustisk levitation kan ha inom kretskortsmontering. Genom att koordinera ett flertal ultraljudshögtalare kan ett akustiskt fält genereras som gör det möjligt att på ett kontrollerat sätt lyfta och förflytta små komponenter utan någon fysisk kontakt. Tidigare forskning inom området har påvisat olika sätt att placera högtalarna på. Två av dessa, vardera med 256 högtalarelement, har under detta projekt byggts och jämforts. Den ena uppställningen har visat sig kunna hålla objekt med högre densitet svävande medan den andra har visat sig ge en bättre lateral stabilitet. Ett förslag för framtida arbete är att kombinera de två uppställningarna för att uppnå en lösning som eventuellt skulle fungera for kretskortsmontering.
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Nikkhah, Hamdam. "Enhancing the Performance of Si Photonics: Structure-Property Relations and Engineered Dispersion Relations." Thesis, Université d'Ottawa / University of Ottawa, 2018. http://hdl.handle.net/10393/37144.
Повний текст джерелаАнотація:
The widespread adoption of photonic circuits requires the economics of volume manufacturing offered by integration technology. A Complementary Metal-Oxide Semiconductor compatible silicon material platform is particularly attractive because it leverages the huge investment that has been made in silicon electronics and its high index contrast enables tight confinement of light which decreases component footprint and energy consumption. Nevertheless, there remain challenges to the development of photonic integrated circuits. Although the density of integration is advancing steady and the integration of the principal components – waveguides, optical sources and amplifiers, modulators, and photodetectors – have all been demonstrated, the integration density is low and the device library far from complete. The integration density is low primarily because of the difficulty of confining light in structures small compared to the wavelength which measured in micrometers. The device library is incomplete because of the immaturity of hybridisation on silicon of other materials required by active devices such as III-V semiconductor alloys and ferroelectric oxides and the difficulty of controlling the coupling of light between disparate material platforms. Metamaterials are nanocomposite materials which have optical properties not readily found in Nature that are defined as much by their geometry as their constituent materials. This offers the prospect of the engineering of materials to achieve integrated components with enhanced functionality. Metamaterials are a class of photonic crystals includes subwavelength grating waveguides, which have already provided breakthroughs in component performance yet require a simpler fabrication process compatible with current minimum feature size limitations.
The research reported in this PhD thesis advances our understanding of the structure-property relations of key planar light circuit components and the metamaterial engineering of these properties. The analysis and simulation of components featuring structures that are only just subwavelength is complicated and consumes large computer resources especially when a three dimensional analysis of components structured over a scale larger than the wavelength is desired. This obstructs the iterative design-simulate cycle. An abstraction is required that summarises the properties of the metamaterial pertinent to the larger scale while neglecting the microscopic detail. That abstraction is known as homogenisation. It is possible to extend homogenisation from the long-wavelength limit up to the Bragg resonance (band edge). It is found that a metamaterial waveguide is accurately modeled as a continuous medium waveguide provided proper account is taken of the emergent properties of the homogenised metamaterial. A homogenised subwavelength grating waveguide structure behaves as a strongly anisotropic and spatially dispersive material with a c-axis normal to the layers of a one dimensional multi-layer structure (Kronig-Penney) or along the axis of uniformity for a two dimensional photonic crystal in three dimensional structure. Issues with boundary effects in the near Bragg resonance subwavelength are avoided either by ensuring the averaging is over an extensive path parallel to boundary or the sharp boundary is removed by graded structures. A procedure is described that enables the local homogenised index of a graded structure to be determined. These finding are confirmed by simulations and experiments on test circuits composed of Mach-Zehnder interferometers and individual components composed of regular nanostructured waveguide segments with different lengths and widths; and graded adiabatic waveguide tapers. The test chip included Lüneburg micro-lenses, which have application to Fourier optics on a chip. The measured loss of each lens is 0.72 dB.
Photonic integrated circuits featuring a network of waveguides, modulators and couplers are important to applications in RF photonics, optical communications and quantum optics. Modal phase error is one of the significant limitations to the scaling of multimode interference coupler port dimension. Multimode interference couplers rely on the Talbot effect and offer the best in-class performance. Anisotropy helps reduce the Talbot length but temporal and spatial dispersion is necessary to control the modal phase error and wavelength dependence of the Talbot length. The Talbot effect in a Kronig-Penny metamaterial is analysed. It is shown that the metamaterial may be engineered to provide a close approximation to the parabolic dispersion relation required by the Talbot effect for perfect imaging. These findings are then applied to the multimode region and access waveguide tapers of a multi-slotted waveguide multimode interference coupler with slots either in the transverse direction or longitudinal direction. A novel polarisation beam splitter exploiting the anisotropy provided by a longitudinally slotted structure is demonstrated by simulation.
The thesis describes the design, verification by simulation and layout of a photonic integrated circuit containing metamaterial waveguide test structures. The test and measurement of the fabricated chip and the analysis of the data is described in detail. The experimental results show good agreement with the theory, with the expected errors due to fabrication process limitations. From the Scanning Electron Microscope images and the measurements, it is clear that at the boundary of the minimum feature size limit, the error increases but still the devices can function.
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Forest, Collado Josep. "New Methods for Triangulation-based Shape Acquisition using Laser Scanners." Doctoral thesis, Universitat de Girona, 2004. http://hdl.handle.net/10803/7730.
Повний текст джерелаАнотація:
Tradicionalment, la reproducció del mon real se'ns ha mostrat a traves d'imatges planes. Aquestes imatges se solien materialitzar mitjançant pintures sobre tela o be amb dibuixos. Avui, per sort, encara podem veure pintures fetes a ma, tot i que la majoria d'imatges s'adquireixen mitjançant càmeres, i es mostren directament a una audiència, com en el cinema, la televisió o exposicions de fotografies, o be son processades per un sistema computeritzat per tal d'obtenir un resultat en particular. Aquests processaments s'apliquen en camps com en el control de qualitat industrial o be en la recerca mes puntera en intel·ligència artificial. Aplicant algorismes de processament de nivell mitja es poden obtenir imatges 3D a partir d'imatges 2D, utilitzant tècniques ben conegudes anomenades Shape From X, on X es el mètode per obtenir la tercera dimensió, i varia en funció de la tècnica que s'utilitza a tal nalitat. Tot i que l'evolució cap a la càmera 3D va començar en els 90, cal que les tècniques per obtenir les formes tridimensionals siguin mes i mes acurades. Les aplicacions dels escàners 3D han augmentat considerablement en els darrers anys, especialment en camps com el lleure, diagnosi/cirurgia assistida, robòtica, etc. Una de les tècniques mes utilitzades per obtenir informació 3D d'una escena, es la triangulació, i mes concretament, la utilització d'escàners laser tridimensionals. Des de la seva aparició formal en publicacions científiques al 1971 [SS71], hi ha hagut contribucions per solucionar problemes inherents com ara la disminució d'oclusions, millora de la precisió, velocitat d'adquisició, descripció de la forma, etc. Tots i cadascun dels mètodes per obtenir punts 3D d'una escena te associat un procés de calibració, i aquest procés juga un paper decisiu en el rendiment d'un dispositiu d'adquisició tridimensional. La nalitat d'aquesta tesi es la d'abordar el problema de l'adquisició de forma 3D, des d'un punt de vista total, reportant un estat de l'art sobre escàners laser basats en triangulació, provant el funcionament i rendiment de diferents sistemes, i fent aportacions per millorar la precisió en la detecció del feix laser, especialment en condicions adverses, i solucionant el problema de la calibració a partir de mètodes geomètrics projectius.Traditionally, the reproduction of the real world has been shown to us by means of at images. These images used to be materialised by means of paint on canvas, drawings or the like. Today, we still see hand made pictures, by fortune, although most of the images are acquired by cameras and they are either directly shown to an audience, like in the cinema, television or photographs, or they are processed by a computer system in order to obtain a particular result, like in industrial quality assurance or bleeding edge artificial intelligence research. Applying mid-level processing algorithms, 3D images can be obtained from 2D ones, using well known techniques called Shape From X, where X is the method for obtaining the 3rd dimension. While the evolution to the 3D camera begun in the 90s, the techniques for obtaining the most accurate 3D shape need to be continuously improving. The application of 3D scanners has spread signi cantly in the recent years, specially in elds like entertainment, assisted diagnosis/ surgery, robotics, etc. One of the most used techniques to obtain 3D information from a scene is triangulation, and more concretely, triangulationbased laser scanners. Since their formal appearance in scienti c publications, in 1971 [SS71], there have been contributions for solving inherent problems like occlusion avoidance, accuracy improvement, acquisition speed, shape description, etc. All of the methods for obtaining 3D points of a scene is accompained with a calibration procedure, and this procedure plays a decisive role in the performance of the acquisition device. The goal of this thesis is to provide a holistic approach to the problem of shape acquisition, giving a wide survey of triangulation laser scanners, testing the performance of di erent systems, and to give contributions for both improving acquisition accuracy under adverse conditions and solving the calibration problem. In addition, the calibration approach is based on previous works that used projective geometry to this end.
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Sztulzaft, Patrick. "Green-expert : un solveur généralisé associé à un générateur de formulations pour la méthode des intégrales de frontières." Grenoble INPG, 1994. https://hal.archives-ouvertes.fr/tel-01331763.
Повний текст джерелаАнотація:
De nombreux secteurs de l'industrie et de la recherche utilisent la modélisation des phénomènes de la physique des milieux continus. Les équations aux dérivées partielles décrivant ces phénomènes sont résolues à l'aide de diverses méthodes numériques. Les modélisations utilisées sont de plus en plus pointues, tant au niveau physique qu'au niveau numérique. Les réponses logicielles à ces problèmes doivent donc être évolutives. Ce travail s'insère dans une dynamique de recherche dans le domaine de la modélisation des phénomènes complexes qui a débuté avec l'élaboration du programme Flux-Expert®, basé sur la Méthode des Eléments Finis. Afin d'élargir le champ des possibilités offertes par ce programme, nous avons choisi d'y associer la Méthodes des Intégrales de Frontières. Dans cette optique, après une présentation didactique de la Méthode des Intégrales de Frontières, nous proposons une décomposition générale de la résolution numérique d'un problème à l'aide de cette méthode. Nous décrivons ensuite le logiciel issu de cette analyse : Green-Expert. L'originalité de la démarche réside dans l'association d'un programme Générateur de Formulations et d'un programme Solveur généralisé. Ce Solveur est capable de résoudre tout problème décrit à l'aide d'une formulation issue du Générateur et d'une Géométrie discrétisée. La dernière partie de ce mémoire est consacré à la validation. Des exemples de couplage entre la Méthode des Intégrales de Frontières et la Méthode des Éléments Finis sont présentés. Enfin, des exemples de résolution 2D et 3D permettent de valider le Générateur et le Solveur de Green-ExpertInvestigations in many sectors of industry and research require the modelling of phenomena observed in the physics of continuous media. The partial differential equations describing these phenomena are solved using a wide range of numerical methods. The models used are increasingly sophisticated, from both a physical and numerical point of view. Software used to solve these problems must therefore be capable of evolving. This work is a continuation of research efforts devoted to the modelling of complex phenomena that began with the development of the Flux-Expert® program, based on the Finite Element Method. In order to extend the possibilities offered by this program, we decided to combine it with the Boundary Element Method. After reviewing the Boundary Element Method, we propose a general decomposition of the numerical solution of a problem using this method. We then describe the Green-Expert software developed on the basis of this analysis. The original aspect of the approach lies in the combination of a formulations generator and a general solver. This solver is capable of solving any problem described using a formulation coming from the Generator and a discrete geometry. The last part of this thesis is devoted to the validation phase. Examples of the combined use of the Boundary Elements and the Finite Element Methods are presented and examples of 2D and 3D resolution are used to validate the Green-Expert Solver and Generator
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Guessasm, Mohamed. "Contribution à la détermination des domaines de résistance de matériaux hétérogènes non périodiques." Université Joseph Fourier (Grenoble), 1999. http://www.theses.fr/1999GRE10010.
Повний текст джерелаАнотація:
Le travail realise a pour objet la determination des domaines de resistance macroscopiques de materiaux heterogenes non periodiques, dans le cadre de la theorie du calcul a la rupture. Afin de caracteriser le comportement non lineaire des materiaux aleatoirement heterogenes, le modele extremal heterogene (m. E. H. ) propose une formulation interessante dans le cas ou le comportement des materiaux constitutifs derive d'un potentiel. Un modele en contraintes, utilisant le cadre conceptuel du m. E. H. , est developpe. Ce modele concerne les materiaux dont le domaine de resistance est, soit convexe (dans ce cas il est identique au m. E. H. ), soit simplement etoile de centre l'origine des contraintes. Une application est realisee sur un materiau perfore aleatoirement. Le modele en contraintes adopte deux descriptions pour le materiau perfore. La premiere description est basee sur les fractions volumiques des materiaux constitutifs. La deuxieme description suppose que le materiau perfore aleatoirement est un agregat de plusieurs materiaux perfores periodiquement. Cette modelisation fournit une famille de domaines de resistance dependant d'un parametre d'heterogeneite r. Ce dernier est determine par calage des previsions numeriques aux resultats experimentaux pour une sollicitation donnee. Le domaine de resistance ainsi obtenu est valide par confrontation des previsions numeriques aux resultats experimentaux pour d'autres types de sollicitations. Parallelement a ce travail, des methodes de resolution sont developpees (a la fois simples et performantes) pour les problemes d'optimisation auxquels conduisent les approches en contraintes (du calcul a la rupture ou de l'homogeneisation). Sous des hypotheses relatives aux domaines de resistance, ces problemes d'optimisation, au depart sous conditions non lineaires, sont ramenes a des problemes d'infmax sans conditions avec une reduction significative du nombre de variables. Leur resolution est basee sur une methode de regularisation originale, effectuee sur une fonctionnelle independante de l'operateur max.
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Deblock, Yves. "Caractérisation ultrasonore haute fréquence des propriétés viscoélastiques de milieux liquides." Valenciennes, 1997. https://ged.uphf.fr/nuxeo/site/esupversions/d2e436b7-2cfd-4b8b-9ff8-9e725f939e0a.
Повний текст джерелаАнотація:
Les modules de compression et de rigidité constituent des paramètres macroscopiques, caractéristiques des matériaux homogènes, linéaires et isotropes. Nous proposons, dans ce travail, deux méthodes acoustiques, originales et complémentaires, applicables aux matériaux liquides, qui permettent leur détermination dans le domaine haute fréquence. La première méthode est basée sur le traitement de l'impédance électrique d'entrée d'un capteur à onde de cisaillement, place au contact du matériau liquide étudié. Ce traitement permet d'extraire le coefficient de réflexion a l'interface entre les matériaux solide et liquide, puis finalement, le module de rigidité. La seconde méthode utilise des capteurs onde de pression. Elle repose sur le traitement de la fonction de transfert en tension d'un système compose de deux capteurs et du matériau liquide dispose entre eux. La vitesse et l'absorption du matériau liquide sont extraites de ce traitement et reliées à une combinaison des deux modules. La connaissance du module de rigidité, issu de la méthode précédente, permet d'atteindre le module de compression. Les deux méthodes de mesure ont été validées, à l'aide d'un matériau liquide de référence. En guise d'exemple, elles ont été appliquées pour l'étude d'un matériau liquide particulier.
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Pal, Olivier. "Modélisation du comportement dynamique des ouvrages grâce à des éléments finis de haute précision." Université Joseph Fourier (Grenoble), 1998. http://www.theses.fr/1998GRE10189.
Повний текст джерелаАнотація:
Le theme dominant de ce travail de these, est l'analyse du comportement des ouvrages sous sollicitations dynamiques par la methode des elements finis. Sur le plan rheologique, on presente deux nouvelles lois de comportement basees sur le formalisme des lois incrimentales non lineaires du second ordre dont la specificite est de n'utiliser qu'un nombre reduit de parametres constitutifs. La reponse de ces lois est etudiee pour differents chemins de sollicitation. L'une de ces deux lois appelee loi duale, presente l'originalite d'etre ecrite sous une forme directe, bien adaptee aux analyses par elements finis. Sur le plan numerique on presente de facon detaillee les avantages et inconvenients lies a l'utilisation d'elements lagrangiens de haute precision. On propose notamment une technique d'optimisation permettant de diagonaliser la matrice de masse de ce type d'element ainsi qu'une formulation analytique de la pulsation maximale afin de definir pour un maillage donne le pas de temps critique correspondant. On aborde egalement la modelisation des milieux semi-infinis a partir de deux approches distinctes : la methode des frontieres absorbantes et les techniques de superposition. L'ensemble de ces developpements est accompagne de nombreuses validations largement detaillees.
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Youney, Justin. "A COMPARISON AND EVALUATIONOFCOMMON PID TUNING METHODS." Master's thesis, University of Central Florida, 2007. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2310.
Повний текст джерелаАнотація:
The motivation behind this thesis is to consolidate and evaluate the most common Proportional Integral Derivative (PID) controller tuning techniques used in industry. These are the tuning techniques used when the plant transfer function is not known. Many of these systems are poorly tuned because such consolidated information is not easily found in one single source such as this thesis. Once one of the tuning methods are applied almost always there will be further fine tuning needed to bring the system into the required design criteria. The purpose here is to find out which tuning technique will yield the lowest percent overshoot and the shortest settling time for all situations. This will give the engineer a good starting point; to minimally further adjust parameters to achieve the desired design criteria. There will also be discussion on the various algorithms used in industry. Four tuning methods will be evaluated based on their ability to control different style plants. The comparison criteria will be percent overshoot and settling time for an applied step input. The tuning methods chosen were the Ziegler-Nichols Open Loop method, the CHR method for 0% overshoot, the Ziegler-Nichols Closed Loop method, and the Rule of Thumb method. It is shown that for a second order plant with a lag and pure integration in its transfer function, the Open Loop method yielded the lowest results in terms of percent overshoot, yet the Closed Loop method had the shortest settling time. For systems of higher order than two it was shown that the CHR method gave the best performance however as the order increased the Closed Loop method gave a shorter settling time. For systems of higher order with varying lags in series the CHR method gave the best results. The Rule of thumb method usually gave similar results to that of the Closed Loop method; however for higher order systems the Rule of Thumb method gave less percent overshoot but with a longer settling time than the Closed Loop method. Since these tuning methods are used when the plant transfer function is not known, and none of the rules were found to give consistently the lowest percent overshoot, and settling time for all plants tested, there can not be a recommendation as to which method an engineer should choose to use. If the plant transfer function is known or can be reasonably modeled then the following recommendations can be followed. When tuning systems with pure integrations in their transfer function the Open Loop or Closed Loop method be used. When tuning systems of order higher than two the CHR or Closed Loop method should be used, however with high order systems with varying lags the CHR method should be used. It is the responsibility of the engineer to know how and when to implement each of the tuning rules properly.M.S.E.E.
School of Electrical Engineering and Computer Science
Engineering and Computer Science
Electrical Engineering MSEE
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Sun, Jiannhwa. "The NEO binary entropy coding method and system /." Diss., Digital Dissertations Database. Restricted to UC campuses, 2004. http://uclibs.org/PID/11984.
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Miao, Junzhe. "A homotopy method for the determination of intersection curve topology /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2003. http://uclibs.org/PID/11984.
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Bölke, Kristofer. "IRONARC; a New Method for Energy Efficient Production of Iron Using Plasma Generators." Thesis, KTH, Materialvetenskap, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-173357.
Повний текст джерелаАнотація:
The most widely used process to reduce iron ore and to produce pig iron is the blast furnace. The blast furnace is a large source of CO2 emissions since it is a coal based process and due to that the main energy source and reducing agent is coke, it is difficult to reduce these further. IRONARC is a new method used to produce pig iron by reducing iron ore and all the energy used for heating comes from electricity, which gives the opportunity to use renewable resources. The process uses plasma generators that inject gas at high temperature and velocity into a slag that consists of iron oxides. The iron oxides are reduced in two steps that appear by using gas as reduction agent in the first step and carbon in the second step. It exists in a smaller pilot plant scale and this project was the first step in the future upscaling of the IRONARC process. Computational Fluid Dynamics (CFD) modelling was used and the goal was to determine the penetration depth of the IRONARC pilot plant process by numerical simulation in the software ANSYS FLUENT. The penetration depth is of importance because to be able to scale up the process it is important to know the flow pattern and the structure of the flow in the process, which is dependent on how far into the slag the gas reaches. Two numerical models were made. First an air-water model that described the initial penetration of air injected into water. The air-water simulation was made with parameters and data from an experiment found in literature. This was done to build an accurate CFD model for the penetration depth in FLUENT and validate the model with the results of the penetration depth from the experiment. The air-water simulation gave good and promising results and yielded the same result regarding the penetration depth as the experiment. The model for the penetration depth was then used with the IRONARC geometry and parameters. After simulation the penetration depth of the IRONARC process was determined. For the future, the penetration depth of the pilot plant needs to be measured and compared with the simulated result for the penetration depth.
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Lopes, Daniel Deodato. "Preparation of gas-filled porous microparticles (GPPs) and microbubbles (MBs) by PGSS method." Master's thesis, Faculdade de Ciências e Tecnologia, 2012. http://hdl.handle.net/10362/9318.
Повний текст джерелаАнотація:
Dissertation to obtain the Master Degree in
BiotechnologyThe main goal of this Project was the development of microbubbles (MBs) and gas-filled porous particles (GPPs) by supercritical fluids (SCF) processes, namely particles from gas saturated solution (PGSS). MBs of perfluorcarbons (PFC) are currently used as contrast agents in ultrasound imaging and as ultrasound-guided drug delivery for targeted therapeutic applications. They are normally produced by processes that present some limitations. The SCF processes are an innovative technology for the production of these MB’s that has not yet been exploited and can overcome these limitations. Carriers are used to prevent rapid diffusion of the gas out of the particle. In the first part of this thesis, a preliminary selection of carrier materials was carried out, including lipids of different hydrophilic-lipophilic balance (HLB) and hydrophilic polymers. Their behavior in the presence of PFC and mixtures of PFC and sc-CO2 was qualitatively studied. A lipid of high HLB value, Gelucire 50/13, was selected to produce the GPPs by PGSS. Main parameters of the process, temperature and pressure, were studied in the range from 55ºC to 80ºC and from 8,5 MPa to 15,4 MPa. Besides, the carrier:PFC ratio and the molecular structure of the PFC were investigated. Particle morphology was analyzed by Scanning Electron Microscopy (SEM), and the presence of PFC was determined by Nuclear Magnetic Resonance (NMR). Small and non agglomerated particles were obtained at 80ºC and 8.5 MPa. Cyclic C4F8 was entrapped in lipid particles in higher amount than of linear C3F8. Nevertheless, the stability of particles obtained at the best operating conditions (80ºC and 8.5 MPa), was relatively short (below 3h) being the majority of the gas released in the first hour.
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Bergh, Ingrid. "Barn och Ungdomar med intellektuella funktionsnedsnedsättningars upplevelse av delaktighet." Thesis, Malmö högskola, Fakulteten för hälsa och samhälle (HS), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:mau:diva-25630.
Повний текст джерелаАнотація:
Vikten av barns och ungdomars delaktighet är centralt i samhällsinsatser och forskning, samtidigt som avsaknad av mätmetoder av upplevelsen lyfts fram.Syftet med denna c-uppsats har varit att genomföra en undersökning av intellektuellt funktionsnedsatta barns och ungdomars upplevelser av social delaktighet utifrån deras perspektiv, dvs. barnets perspektiv samt att undersöka om mätverktyget Pict-O-Stat är en adekvat metod att använda för att mäta upplevelsen av delaktighet. Delaktighetsbegreppets komplexitet belyses och det är med perspektivet ”Den sociala delaktigheten i vardagslivet” som frågeställningen undersöks. Metoderna har varit en kvantitativ enkätundersökning där Pict-O-Stat används som mätverktyg och Pict-O-Stathandledarnas upplevelse av hur funktionellt mätverktyget är, genomförs med ett hermeneutiskt förhållningssätt genom en studie med öppna frågor. Verksamheterna som undersökningen genomfördes i är korttidsvistelse, korttidstillsyn och bostad med särskild service för barn eller ungdomar enligt LSS. Barnen och ungdomarna tillhör LSS-personkrets 1, vilken omfattar personer med utvecklingsstörning, autism eller autismliknade tillstånd (inklusive Aspergers syndrom) och de var mellan 5-21 år. Materialet var begränsat, då få medgivande från föräldrar inkom. Sammanfattningsvis visade undersökningen att graden av upplevd delaktighet varierar samt att komplexiteten i begreppet gör det oklart vad delaktighet är. Resultatet belyser mätverktyget Pict-O-Stats möjligheter och begränsningar samt understryker behovet av framtida forskning inom området.Despite the importance of participation for children and young with intellectual disability in central social interventions and research, methods of quantifying and monitoring are underdeveloped. The purpose of this essay has been to conduct a study of intellectually disabled children´s and young people's experiences of social participation from their perspective, i.e. the child's perspective and to investigate whether the measuring tool Pict-O-Stat is a functional method to use to measure the experience of participation. The complexity of the concept of participation is analyzed in the perspective of “social participation in everyday life". The method utilized has been a quantitative survey where Pict-O-Stat is used as a measuring tool and Pict-O-Stat supervisors' perception of the functionality of the measurement tool is studied through a hermeneutic approach and a questionnaire with open questions. The activities that the survey was implemented in are short-term stay, short-term supervision and accommodation with special services for children or young people entitled to support by LSS, the Act on Support and Service to certain Impaired Persons. The children and young people participating belong to the LSS category 1, which includes persons with mental retardation, autism or pervasive developmental disorders (incl. Asperger’s syndrome) and they were between 5-21 years. The material was limited, because the consents from parents were less than expected. In summary, the survey showed that the degree of perceived participation varies and that the complexity of the concept made the meaning of participation unclear. The result emphasizes the possibilities and limitations of the method of Pict-O-Stat and underlines the need of future research within this field.
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Beilke, Michael C. "The Development of Nanomaterials and "Green" Methods for Separation Science." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1448475540.
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Lardy, Matthew Alan. "Computational combinatorial methods in virtual library design /." Diss., Digital Dissertations Database. Restricted to UC campuses, 2006. http://uclibs.org/PID/11984.
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Woods, James. "An exploration of evolutionary methods in macroeconomics /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2003. http://uclibs.org/PID/11984.
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Sallee, Philip Andrew. "Statistical methods for image and signal processing /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2004. http://uclibs.org/PID/11984.
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Dincay, Berkan. "GPS/Optical Encoder Based Navigation Methods for dsPIC Microcontroled Mobile Vehicle." Thesis, Halmstad University, Halmstad Embedded and Intelligent Systems Research (EIS), 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-4420.
Повний текст джерелаАнотація:
Optical encoders are being widely suggested for precise mobile navigation. Combining such sensor information with Global Positioning System (GPS) is a practical solution for reducing the accumulated errors from encoders and moving the navigational base into global coordinates with high accuracy.
This thesis presents integration methods of GPS and optical encoders for a mobile vehicle that is controlled by microcontroller. The system analyzed includes a commercial GPS receiver, dsPIC microcontroller and mobile vehicle with optical encoders. Extended kalman filtering (EKF), real time curve matching, GPS filtering methods are compared and contrasted which are used for integrating sensors data. Moreover, computer interface, encoder interface and motor control module of dsPIC microprocessor have been used and explained.
Navigation quality on low speeds highly depends greatly upon the processing of GPS data. Integration of sensor data is simulated for both EKF and real time curve matching technique and different behaviors are observed. Both methods have significantly improved the accuracy of the navigation. However, EKF has more advantages on solving the localization problem where it is also dealing with the uncertainties of the systems.
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Strickland, Walter R. "Liberation and Black theological method : a historical analysis." Thesis, University of Aberdeen, 2017. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=233773.
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Nelson, Kirk Edwin. "A Lagrangian method for investigating bacterial transport and attachment in the colloid filtration theory /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2004. http://uclibs.org/PID/11984.
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Zaïmi, Sami Alex. "Modélisation de l'écoulement des matières solides dans le haut fourneau : application de la méthode des éléments finis aux milieux granulaires non polaires et aux milieux de Cosserat, en comportement hypo-plastique." Châtenay-Malabry, Ecole centrale de Paris, 1998. http://www.theses.fr/1998ECAP0577.
Повний текст джерелаАнотація:
On utilise la méthode des éléments finis (a l'aide du code de calcul ABAQUS) afin de déterminer l'écoulement des matières solides dans le haut fourneau. Cet écoulement peut être assimilé à celui se produisant dans un silo à paroi divergente puis convergente, et a extraction périphérique. La loi de comportement utilisée appartient à la famille des lois dites hypo-plastiques, qui convient bien à la modélisation des écoulements granulaires. Cette loi est calibrée à l'aide d'essais triaxiaux sur des échantillons de coke et de minerai. Après de multiples remaillages, on atteint un régime permanent des vitesses et des contraintes. Les cartes obtenues montrent, entre autres, les régions en poussée et en butée, les régions en écoulement sablier et piston, et la forme de la zone stagnante appelée homme mort. La théorie de Cosserat a été appliquée, et a permis de simuler la formation de bandes de cisaillement en paroi (conditions aux limites rugueuses). Des observations expérimentales (appliquant la technique de l'analyse d'image) sur une maquette bidimensionnelle de haut fourneau sont venues étayer nos résultats sur le champ des vitesses.
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Ottosson, Joachim, and Niklas Renström. "aMAZEing robot : A method for automatic maze solving." Thesis, KTH, Skolan för industriell teknik och management (ITM), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-264491.
Повний текст джерелаАнотація:
The purpose of this report was to examine a method for automatic maze solving by developing a robot that can find a specific target within a maze. On this basis, a Arduino based robot was constructed. The steering mechanism was constructed in a way that supports differential steering which enables zero radius turns which is preferred in narrow spaces. The intersection detection as well as the method for defining which type of intersection occurring was based on three distance sensor mounted in front and on the left and right side of the robot. The target detection was based on a IR sensor. A feedback controller was applied on the left Ultrasonic sensor enabling the robot to keep a reference distance to the wall. The feedback system also enabled the robot to straighten up when taking to big or small turns. The robot was able to both detect and define what kind of intersection occurring as well as detect the specific target. The execution of the correct operation by detected intersection was calculated to 80% - 100% and the target was found 100% out of the test made. The definition of ”correct operation” in this report was when the robot detected a intersection, and executed the operation that was in accordance with the implemented algorithm. The rotational error, that is the quantity of degrees from the desired turn angle, occurring when the robot executed different operations was calculated to 3.5◦ - 9.5◦ . The robot started to oscillate due to angles grater than 19.5◦ when the left distance sensor was facing the wall which made the robot less able to follow a path and straighten up.Syftet med denna rapport var att undersöka en metod för automatiserad labyrintlösning genom att utveckla en robot som kan finna ett specifikt mål i en labyrint. På dessa grunder konstruerades en arduinobaserad robot. Styrmekanismen konstruerades på sådant sätt att differentialstyrning var möjlig vilket tillät svängar utan svängradie, vilket är att föredra vid trånga utrymmen. Vägkorsningsdetekteringen samt metoden för att bestämma vilken typ av vägkorsning som förekommer baserades på tre distansmätare. Dessa var monterade på robotens front samt på höger och vänster sida. Måldetekteringen var baserad på en IR sensor. Ett system medåterkoppling implementerades på den vänstra distansmätaren för att få roboten att hålla ett referensavstånd till väggen. Detta möjliggjorde även så att vägen kunde följas på ett optimalt sätt samt att roboten kunde rätas upp vid för stora eller för små tagna svängar. Roboten lyckades både detektera samt definiera vilken typ av vägkorsning som uppstod likväl som att detektera det specifika målet. Andelen utförda korrekta operationer vid detekterande av vägkorsning beräknades till 80% - 100% av fallen och målet detekterades 100% av gångerna vid det gjorda testerna. Definitionen av ”korrekt operaton ”i denna rapport var då roboten upptäckte en vägkorsning och utförde den operation som var i enlighet med den implementerade algoritmen. Rotationsfelet, det vill säga antalet grader från den önskade svängvinkeln, som uppstod vid de olika operationerna beräknades till 3.5◦ - 9.5◦ . Roboten började att oscillera vid vinklar större än 19.5◦ då den vänstra distansmätaren var vänd mot väggen vilket gjorde roboten mindre duglig att följa väggen samt att rätas upp.
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Vinberg, Karl, Jacob Holm, and Amer Basic. "Från periodisk inventering utan Pick By Voice till rullande inventering med Pick By Voice : En fallstudie på Företag X." Thesis, Linnéuniversitetet, Institutionen för ekonomistyrning och logistik (ELO), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-96750.
Повний текст джерелаАнотація:
Titel: Från periodisk inventering utan Pick By Voice till rullande inventering med Pick By Voice - En fallstudie på Företag X Bakgrund och problem: Företag X har valt att implementera plocktekniken Pick By Voice, samtidigt som företaget ser över möjligheten att implementera en rullande inventering i samband med detta. Frågor som uppstår är vad lagar och praxis säger för området samt hur en möjlig implementering av rullande inventering bör se ut. Syfte: Syftet med uppsatsen är att genom en kvalitativ studie undersöka behovet av en ny inventeringsmetod genom en förstudie och därefter utveckla en inventeringsprocess passande efter Företag X förutsättningar. Denna inventeringsprocess ska kunna användas i samspel med Pick By Voice. Vidare är också att uppmuntra andra företag inom likartad bransch att se över sin nuvarande inventeringsmetod och om de kan implementera en liknande förändring av rullande inventering med Pick By Voice. Metod: Denna studie är en kvalitativ fallstudie. Insamlingen av empiri har skett genom utförandet av semistrukturerade och ostrukturerade intervjuer med företag och revisionsbyråer. Slutsats: En nu 65 år gammal skattelag säger att företag måste inventera sina lager minst en gång om året. Som en otillräcklig beskrivning av hur detta ska göras, samtidigt som lagerhanteringssystemet får ny utveckling, har detta lagt större vikt vid nuvarande praxis. Detta är särskilt så när ett företag implementerar en rullande inventeringsmetod. Viktiga steg i implementeringsprocessen bekräftas vara avgörande för företag att uppfylla. Dels för att lyckas med implementeringen, men också för att säkerställa en tillfredsställande inventeringsprocess och undvika att både misstag i implementerings- och inventeringssprocessen uppstår. Att kombinera den rullande inventeringen med röstplocktekniken Pick By Voice anses även det vara betydande för att reducera ytterligare misstag som förekommer eller kan förekomma i inventeringsprocessen. Hur frekvent företag bör inventera grundar sig i; vilken typ av marknad företaget är verksamt på, andelen misstag som uppstår i inventeringsprocessen och om fler antal inventeringar kan bidra till fler besparingar för företaget.Title: From periodic inventory without Pick By Voice to continuous inventory with Pick By Voice - A case study at Company X Background and problem: Company X has chosen to implement the Pick By Voice picking technology, while at the same time considering the possibility of implementing a continuous inventory in connection with this. Questions that arise are what the laws and practices say for this area and what a possible implementation of continuous inventory should look like. Purpose: The purpose of this thesis is to investigate the need for a new inventory method through a pilot study and then develop an inventory process suitable for Company X conditions. This inventory process should be used in interaction with Pick By Voice. Furthermore, other companies in similar industries are also encouraged to review their current inventory method and whether they can implement a similar change of continuous inventory with Pick By Voice. Method: This study is a qualitative case study. The collection of empirical data has been carried out through the conduct of semi structured and unstructured interviews with companies and accounting firms. Conclusion: A now 65 years old tax law says that companies need to count their inventory at least once a year. As there is an insufficient description of how this should be done, while also warehouse management system get new development, this has placed greater emphasis on current practice. This so, especially when a company is implementing a continuous inventory method with Pick By Voice. Important steps in the implementation process have been confirmed to be crucial to fulfil by the company. Especially in order to achieve a successful implementation of the process, ensure that the process fulfil its required satisfaction level and to avoid occurrence of mistakes in the implementation process as well as in the inventory process. The combination of continuous inventory and Pick By Voice is considered to be significant in the reduction of further mistakes that occur or can occur in the inventory process. The determination of the inventory frequency is dependent on; type of market that the company operates in, number of occurring mistakes in the inventory process and if an increase in number of inventory occasions can contribute to an increase in the savings.
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Pilotto, Rafael 1989. "Modelagem e otimização de atuadores magnéticos no controle de vibrações." [s.n.], 2015. http://repositorio.unicamp.br/jspui/handle/REPOSIP/265844.
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Orientador: Katia Lucchesi Cavalca DediniDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica
Made available in DSpace on 2018-08-26T17:52:06Z (GMT). No. of bitstreams: 1 Pilotto_Rafael_M.pdf: 4691143 bytes, checksum: 8c6f267d72179ac9f88041489c3da8b5 (MD5) Previous issue date: 2015
Resumo: O uso de atuadores magnéticos para redução de vibrações visa substituir, em algumas ocasiões, os mancais magnéticos, uma vez que o atuador magnético envolve requisitos de projeto de menor complexidade em sua configuração. O presente trabalho consiste em avaliar como um atuador magnético se comporta ao controlar as vibrações em uma viga flexível de material metálico, bi-engastada, modelada computacionalmente, utilizando o método dos elementos finitos. O atuador magnético é inserido no modelo, utilizando a teoria de eletromagnetismo, assim como os componentes: amplificador de corrente, sensor de posição indutivo e um controlador PID (proporcional-integrador-derivativo). No modelo computacional, o atuador e o sensor de posição são posicionados em diferentes nós, com o propósito de estudar a eficácia do sistema atuador-controlador-sensor em função da sua posição ao longo da viga. Os parâmetros do controlador PID foram obtidos utilizando o método de otimização de Ziegler-Nichols, para as posições observadas do sistema atuador-sensor, e a técnica LPV (Linear Parameter Varying ¿ Variação Linear de Parâmetros) foi então aplicada para o desdobramento desses parâmetros como uma função do comprimento da viga. Para a validação experimental, foram utilizados dois dispositivos para a excitação externa da viga: um equipamento eletromecânico, denominado Shaker, que gerou ondas senoidais nas frequências naturais do sistema, com o propósito de verificar o comportamento do conjunto atuador/controlador em condições críticas, e um martelo de impacto, que excitou a viga através de um impulso único, o qual permitiu obter a dissipação de energia na viga em função do tempo decorrido até o amortecimento completo da resposta transiente. Assim, foram realizadas comparações entre os resultados obtidos a partir do modelo por elementos finitos e as análises realizadas sobre as medições na bancada experimental. Pode-se também observar o comportamento do atuador magnético, no que concerne ao controle de vibrações, em função de seu posicionamento ao longo da viga flexível
Abstract: The use of magnetic actuators for vibration reduction aims to substitute, in some occasions, the magnetic bearings, since the magnetic actuator involves less complex project requirements in its configuration. The present study consists of evaluating how a magnetic actuator behaves while controlling vibration in a flexible metallic beam, modeled using the finite elements method. The magnetic actuator is inserted into the model utilizing electromagnetic theory. Other components are added to the model through the theory of control of mechanical systems, such as: current amplifier, inductive position sensor and a PID controller (Proportional-Integral-Derivative). The actuator and the sensor are placed in different nodes in the computational model, in order to study the effectiveness of the actuator-controller-sensor system depending on its positioning in the beam. The parameters of the PID controller for the entire length of the beam were obtained using the Ziegler-Nichols optimization method for the locations of the beam where the actuator-sensor system was positioned and the LPV (Linear Parameter Varying) technique was applied to the unfolding of these parameters as a function of the beam length. For the experimental validation, two devices were used to act as an external excitation in the beam, an electromechanical equipment called Shaker, which generated sinusoidal waves in the natural frequencies of the system, in order to verify the behavior of the actuator/controller in critical conditions, and a modal hammer that excited the beam through a single impulse, which allowed the energy dissipation to be measured as a function of the time period until the complete damping of the transient response. Thus, the results obtained from the finite elements model were compared with the experimental analysis on the test rig. Moreover, the behavior of the magnetic actuator in vibration control is evaluated regarding its position alongside the flexible beam
Mestrado
Mecanica dos Sólidos e Projeto Mecanico
Mestre em Engenharia Mecânica
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Nagamune, Ryozo. "Robust Control with Complexity Constraint : A Nevanlinna-Pick Interpolation Approach." Doctoral thesis, KTH, Mathematics, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3394.
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Langham, James J. "Discovering drug candidates in virtual chemical libraries : a novel graph-based method for virtual screening /." Diss., Digital Dissertations Database. Restricted to UC campuses, 2006. http://uclibs.org/PID/11984.
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Asad, Ahmed, and Rikard Sallander. "Balansering och tidsoptimering av materialsatsning till F12-monteringen på Parker PMDE Trollhättan." Thesis, Högskolan Väst, Avdelningen för produktionssystem (PS), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:hv:diva-9440.
Повний текст джерелаАнотація:
I industriföretag används managementverktyg för att utveckla och effektivisera verksamheten så att ledtider och slöseri reduceras i samtliga processer. Parker PMDE Trollhättan tillverkar hydraulikmaskiner. Sedan 90-talet har Parker bedrivit verksamhetsutveckling enligt management principer i Lean Production. Ett nästa steg i Parkers ständiga förbättringsarbete var att undersöka möjligheter att utveckla en materialsatsningsavdelning så att en person kan förse monteringen med material tillräckligt snabbt utan att extra resurser behöver tillsättas. I dagsläget råder det obalans gentemot takttider i monteringen och det tar längre tid för satsningen att plocka ihop fyra satser än vad det tar för monteringen att förbruka dessa satser.Målet med examensarbetet var att ta fram förbättringsförslag där en person får förutsättningar att plocka ihop material till montering av fyra hydraulikmaskiner på mindre än 16 minuter. Delmålen var att göra en kartläggning av tider och arbetsmoment vid satsningen. Avgränsningarna i projektet var att inte undersöka processer utanför satsningen. Examensarbetet utformades efter DMAIC-metodiken, som är en projektmodell för faktabaserad problemlösning och tydlig struktur. Metoderna som användes vid insamling av data var observationer och analys av videoinspelat material som utfördes i programvaran AviX Method. Videoinspelningarna kategoriserades som olika aktiviteter i satsningsprocessen där gång, plock, scannertid, förmontering och övrig tid var de största kategorierna. Arbetsmoment identifierades som var tidskrävande och ej tillförde värde i processen. Mätningarna låg till grund för generering av lösningsförslagen.Baserat på ovanstående resultat och med hjälp av brainstorming genererades lösningsförslag tillsammans med produktionstekniker och materialhanterare. De lösningsförslag som uppfyllde målet med projektet att plocka en 4-sats under 16 minuter var pick by voice, pick by light, ringscanner och flytt av kilpress. Pick by voice anses vara lösningen som företaget bör införa eftersom den reducerar plocktid, scannertid och är ett flexibelt system. Ytterligare två lösningsförslag togs fram som inte uppfyllde målet men uppfattas som värda för företaget att utreda vidare utifrån Lean Production och ergonomiska skäl. De lösningsförslagen som inte uppfyllde målen bestod av en förändring av plockrundan och införande av en magnetlyft.In industries, the management tools of Lean Production are used to develop and streamline operations in a way to reduce waste and lead times in all processes. Parker PMDE in Trollhättan manufactures hydraulic machines. Since the 90´s, Parker has pursued business development under the management principles of Lean Production. One of the next steps in Parkers continuous improvement was to explore opportunities to develop a kitting department so that a worker could provide the assembly with the material quickly without surplus resources. In the current situation, there is an imbalance from the kitting station towards the tact times in the assembly station because it takes longer at the kitting station to pick materials for four hydraulic machines, than it takes for the assembly station to consume these kits of materials.The aim of the thesis was to develop suggestions for improvement where a worker could perform the kitting process in less than 16 minutes. The interim objectives were to do a survey of the times and activities within the kitting process. The boundaries of the project was not to examine processes outside the kitting station. The project was designed according to DMAIC methodology, which is a project model for fact-based problem solving and clear structure. The methods used in the data collection were observation and analysis of video footage applying the software called AviX Method. Video recordings were categorized as different activities in the kitting process such as transport, picking, scanner time, pre-assembly and uncategorized time. Activities that were time consuming and did not add value to the process were identified. These data measures were the basis for the solution proposals.Based on these results and using brainstorming, solution proposals were generated together with the engineers and material handlers. The solution proposals that met the objective of the project of picking a 4-set of materials in 16 minutes were: Pick by voice, Pick-by-light, Ring Scanner and Relocation of one pre-assembly operation. Pick by voice is considered to be the most appropriate solution for the company since it reduces picking times, scanning times and is a flexible system. Two more proposed solutions were developed that did not meet the objective of the project, but are considered worth investigating further based on Lean Production and ergonomic reasons. These proposed solutions consisted of changing the picking route and the installation of a magnetic lift.
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Hartmann, Daniel M. "Self-assembled pick and place methods for heterogeneous integration of micro and nano-scale structures /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2001. http://wwwlib.umi.com/cr/ucsd/fullcit?p3022234.
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Pollock, Jacob F. "New methods for making optimal use of real conservation data /." Diss., Digital Dissertations Database. Restricted to UC campuses, 2005. http://uclibs.org/PID/11984.
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Zhong, Xiaoyun. "Multivariate survival analysis methods for mapping genes for complex diseases /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2003. http://uclibs.org/PID/11984.
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Grishin, Denis. "Fast and efficient methods for multi-dimensional scattered data approximation /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2004. http://uclibs.org/PID/11984.
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Bartell, Scott Michael. "Statistical methods for non-steady state exposure inference using biomarkers /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2003. http://uclibs.org/PID/11984.
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Rieben, Robert N. "A novel high order time domain vector finite element method for the simulation of electromagnetic devices /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2004. http://uclibs.org/PID/11984.
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SPIESER, STEPHANE. "Analyse conformationnelle d'un oligosaccharide cyclique : modelisation de complexes." Université Joseph Fourier (Grenoble), 1997. http://www.theses.fr/1997GRE10036.
Повний текст джерелаАнотація:
Un nouvel oligosaccharide cyclique, le cyclotrikis-(16)- -d-glucopyranosyl-(14), d-glucopyranosyl, a ete etudie en solution par une double approche combinant la resonance magnetique nucleaire et la modelisation moleculaire. L'etude des sucres par mecanique moleculaire implique l'emploi d'un champ de forces specifique. Un ensemble de parametres adaptes aux saccharides et developpes par homans pour le coffret amber, a ete teste et valide a partir d'un modele de glucides, le 2-methoxytetrahydropyrane. Un nouvel outil informatique a ete developpe pour generer aleatoirement un grand nombre de structure cyclique. Une recherche conformationnelle de type monte carlo a ensuite ete realisee. Des parametres theoriques de rmn ont ainsi pu etre calcules. L'obtention, a partir d'experiences rmn de parametres experimentaux analogues, a permis de preciser les conformations presentes en solution. Celles-ci sont caracterisees par des structures a la fois asymetriques et symetriques, presentant une cavite de taille intermediaire a celle des cyclodextrines. A partir de conformations privilegiees de ce macrocycle, des simulations de complexes avec des cation alcalins et une molecule neutre, la thymine, ont ete realisees par modelisation moleculaire.
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Blaise, Philippe. "Dynamique moléculaire quantique : méthodes numériques et étude physique de la structure, de la thermodynamique, de la stabilité et de la fragmentation des agrégats métalliques de sodium." Université Joseph Fourier (Grenoble), 1998. http://www.theses.fr/1998GRE10110.
Повний текст джерелаАнотація:
Le but de cette these est l'etude des agregats metalliques de sodium par la simulation numerique. Nous avons developpe deux codes de calculs de dynamique moleculaire ab initio en fonctionnelle de densite. Le premier se fonde sur le modele semi-classique de thomas-fermi etendu. La resolution est en espace reel et utilise la methode car-parrinello. Son cout est en o(n), et nous avons mis au point un pseudopotentiel qui accelere le calcul. Au sacrifice des effets de couche, nous pouvons etudier un vaste ensemble d'agregats. Nous montrons alors qu'avec un minimum d'ajustements, les agregats de sodium suivent une energetique goutte liquide. Nous avons etudie les modes vibratoires de compression et de surface, ainsi que la repartition de la charge. Nous montrons que l'energie de surface des agregats est tres sensible a la temperature, et que leur point de fusion est plus bas que celui du solide. Nous avons extrait des barrieres de fission grace a une methode de contrainte. Le deuxieme code est base sur le modele quantique de kohn-sham. La resolution est en espace reel, et son cur est le couplage de l'algorithme du point fixe de broyden pour l'auto-coherence avec l'algorithme iteratif de lanczos-davidson pour le probleme propre. Cette methode possede un cout beaucoup plus eleve. Dans un premier temps, nous avons optimise les structures de plus basse energie des petits agregats et calcule leur energetique. L'accord avec des travaux anterieurs est excellent. Puis nous avons etudie la dynamique des agregats tres charges. Nous montrons que la fission peut etre extremement sensible aux conditions initiales. Nous avons mis en evidence pour la premiere fois, que les systemes de grande fissilite multifragmentaient avec l'emission preferentielle de monomeres sur des echelles de temps inferieures a la pico-seconde. Ces resultats ont pu etre obtenus grace au developpement d'une methode originale de maillage adaptatif dont la geometrie suit celle du systeme lors de la fragmentation.
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Amayo, Kenneth Osenewiwe. "Method development for identification and quantification of arsenolipids in seafood." Thesis, University of Aberdeen, 2013. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=201887.
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Park, Je-Hyoung. "East chip-level static and transient thermal analysis method for thermal management of VLSI ICs in packages /." Diss., Digital Dissertations Database. Restricted to UC campuses, 2009. http://uclibs.org/PID/11984.
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Medvedev, Dmitry. "Computation of electron transfer in proteins : method development and applications to cytochrome c oxidase and DNA photolyase /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2002. http://uclibs.org/PID/11984.
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Dogan, Nihan. "Investigation of an in-line, non-destructive ultrasonic method to study flow and rheology of complex fluids /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2003. http://uclibs.org/PID/11984.
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Swaminathan, Vidya. "A comparison of two methods of resolution : blow up and prolongation /." Diss., Digital Dissertations Database. Restricted to UC campuses, 2009. http://uclibs.org/PID/11984.
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Hong, Fangxin. "Statistical methods for analysis of microarray time course gene expression data /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2004. http://uclibs.org/PID/11984.
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Milburn, Tyler. "Analysis of Advanced Control Methods for Quadrotor Trajectory Tracking." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1532078119456277.
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Manzhur, Yuriy. "Untersuchung magnetischer Eigenschaften von Ni-Einkristalloberflächen, Ni-Dünnschichtoberflächen und Ni/Pd-Grenzflächen mit der PAC-Methode." [S.l.] : [s.n.], 2005. http://www.diss.fu-berlin.de/2006/198/index.html.
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Cardilla, Kim. "Personality vulnerabilities, coping, and depression : a multi-method daily diary study of college students' coping with daily hassles /." Diss., Digital Dissertations Database. Restricted to UC campuses, 2008. http://uclibs.org/PID/11984.
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Fioravanti, André. "H∞ analysis and control of time-delay systems by methods in frequency domain." Phd thesis, Université Paris Sud - Paris XI, 2011. http://tel.archives-ouvertes.fr/tel-00627352.
Повний текст джерелаАнотація:
This thesis addresses the H∞ analysis and control of continuous commensurate time-delay systems by frequential methods. First, the asymptotic behavior of the chains of poles are studied, and the conditions of stability for neutral systems with poles approaching the imaginary axis are given. The same analysis is done for fractional systems. In the sequel, a numerical method able to locate all the stability windows as well as the unstable root-locus for classical and fractional system is given. We conclude the analysis part by providing the stability crossing curves of a class of distributed delay system. Starting the synthesis part, we design PID controllers for unstable fractional systems using a small-gain theorem approach. Finally, using the Rekasius substitution, we construct a linear time invariant comparison system that allows us to get information about stability and H∞-norm for classical time-delay systems. Using this approach it is possible to design state and output feedback controllers, as well as linear filters for this class of systems.