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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
351

Řešení technologie součásti "stopka" / Solution technology of part "stem-arbor"

Dudek, Milan January 2013 (has links)
This thesis is focused on proposal of new version of production proces of part stem-arbor, proposal of suitable edge tools, which should be used for new verion of production proces a their comparison based on their lifetime. The lifetime has been got from brought out sample production order. There is based on these results suitable edge tools and cutting conditions during machining according to new version of production proces. There is evaluated either quality control or figured out savings in production.
352

Conceptualization And Measurement Of Techno-Oraganizational Change Using Path Analysis : A Quasi Experiment For CNC Technology

Mathew, Mary 07 1900 (has links) (PDF)
No description available.
353

Modulo computacional, baseado em redes neurais, para a força de corte e para a rugosidade, em torneamento / Computacional module, based on neural networks for cutting force and roughness in turning

Almeida, Sergio Luis Rabelo de 14 June 2006 (has links)
Orientador: Olivio Novaski / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-07T14:11:27Z (GMT). No. of bitstreams: 1 Almeida_SergioLuisRabelode_D.pdf: 2212505 bytes, checksum: b547ce8e7c1a1faea1a6c7468054f32f (MD5) Previous issue date: 2006 / Resumo: Os softwares CAM existentes hoje no mercado permitem facilmente automatizar a geração de programas em linguagem CNC a partir de um modelo CAD. As trajetórias da ferramenta são calculadas respeitando-se a geometria final da peça. No entanto, estes programas, em geral, não disponibilizam recursos para corretamente estimar os parâmetros de usinagem (velocidade de corte, avanço, profundidade de usinagem), bem como sua influência em grandezas relevantes ao processo, como a força de corte e a rugosidade. Cria-se, assim, um descompasso com a realidade fisica do processo. Adicionalmente, tais programas não foram desenvolvidos com abordagem didática, possuindo pré-requisitos (interface CAD, domínio de idioma estrangeiro etc.) que dificultam ao estudante o fácil aprendizado de processos de usinagem a CNC. Este trabalho busca então abordar estes problemas vivenciados por escolas técnicas, desenvolvendo um módulo computacional, acoplado a um software CNC didático comercial para torneamento, que permita a predição de esforços de usinagem e rugosidade em tempo de programação CNC. Optou-se pela técnica da rede neural como núcleo, uma vez que permite aproximações bastante satisfatórias do processo de torneamento. Os resultados indicam que os modelos de rede neurais adotados (perceptron multi-camadas e função de base radial) aproximam de forma satisfatória o comportamento da força de corte e rugosidade, em função dos parâmetros de usinagem escolhidos (velocidade de corte, avanço e profundidade de corte) em uma série de casos de uso, utilizando-se o módulo computacional desenvolvido / Abstract: The majority of CAM software in the market allows the user to easily create the CNC program through CAD models. The tool paths are ca1culated in respect to the final piece geometry. However, these software do not permit, as part of their functionality, to estimate the cutting parameters (cutting speed, feed and depth of cut), as well as their influence in process variables such as cutting force and roughness. There is, in that sense, a gap between the geometrical and physical scenario of the machining process. Additionally, such software were not developed with didactical requirements, which makes difficult to the students the learning of the machining concepts using the CNC technology. The CAD and the foreign language interface are examples of such fact. This work targets to approach these remarks which are particularly common among the Technical Schools, developing a computational module, embedded in a commercial CNC didactic software, capable of predicting cutting forces (in roughing) and surface roughness (in finishing) at programming time. It was used a neural network technique as the base core, since it allows good estimative of turning process. The results indicate that the ANN topologies (Multilayer Perpectron and Radial Basis function) correlate satisfactorily with the experimental behavior of the cutting force and roughness regarding the input parameters chosen (cutting speed, feed and depth of cut) for different cases using the software prototype / Doutorado / Materiais e Processos de Fabricação / Doutor em Engenharia Mecânica
354

Desarrollo metodológico para la aplicación de técnicas de adquisición e impresión 3D en conservación y restauración de vidrio arqueológico, y caracterización de materiales relacionados con la fase de reconstrucción

Díaz Marín, María del Carmen 06 November 2017 (has links)
The introduction of 3D technology in the conservation of archaeological heritage has opened the gates for new researches. In the case of glass removed from the ground, their fragile state of conservation requires an extremely careful handle. That might cause its physical damage, so it should be minimized. This PhD thesis deals with the application of 3D technology in the different stages of the conservation and restoration of archeological glass objects. Alternative methods based on the substitution of the original object by its 3D model are offered instead of the traditional ones. The appearance of the glass will be required only at specific times in order to minimize its handle. The development of how to apply these techniques in a methodological way involves alternative procedures, those introduce new materials whose behavior we do not know. For this reason, a chapter has been produced to test them. In particular, we have studied the materials used in the reconstruction of missing areas which have been brought by the incorporation of 3D printed implants. In this way, it has been possible to determinate their rate of compatibility with archaeological glass conservation and restoration treatments. The proposed methodology has demonstrated that 3D technology is applicable in the field of conservation and restoration of archaeological glass. The initial problem of the 3D scanning of this material has been resolved. Furthermore, the handle rate of the objects during the reconstruction of the missing areas and in the creation of packaging has been reduced. The use of thermoplastic resins to build the gap filling has provided excellent results as the implants obtained show highly accuracy when reproducing the depth of objects decoration. Finally, concerned textures have been incorporated to virtual models by photogrammetry. Furthermore, a hypothetical recreation of the gap filling textures has been made too. These visualizations contribute to the complete reconstruction of the objects studied in 3D but without handling the originals in an excessive or unjustified way. As they are not specific from glass, the same process has been carried out on a different archaeological materials. In this way, the virtual reconstruction of an incomplete terracotta sculpture and the visualization of a paleontological skull had been made to support that. Textured models are brought through virtual and augmented reality showing the different stages of the reconstructive process to the potential audience, museum visitors and researchers. / La introducción de las tecnologías 3D en la conservación del patrimonio arqueológico ha permitido abrir nuevas vías de investigación. En el caso de los objetos de vidrio exhumados su frágil estado de conservación exige una manipulación extremadamente cuidadosa, que pone en riesgo su integridad física, por lo que ésta debe reducirse al máximo. La presente Tesis Doctoral muestra la aplicación de las tecnologías 3D en diferentes etapas de la conservación y restauración de objetos de vidrio arqueológico. Se ofrecen así métodos alternativos a los tradicionales basados en la sustitución del objeto original por su modelo 3D de forma que solo es necesaria su presencia en momentos puntuales para una mínima manipulación. Al desarrollar metodológicamente como aplicar estas técnicas se emplean procedimientos alternativos que introducen nuevos materiales cuyo comportamiento desconocemos. Por ello, se ha desarrollado un capítulo para la caracterización de estos nuevos materiales incorporados. En concreto, se han estudiado aquellos utilizados en la fase de reconstrucción del volumen perdido mediante la creación e incorporación de implantes impresos en 3D. De este modo, se ha podido determinar su grado de adecuación y compatibilidad en los tratamientos de conservación y restauración del vidrio arqueológico intervenido. La metodología propuesta ha demostrado que la tecnología 3D es aplicable en el campo de la conservación y restauración del vidrio arqueológico. Se ha resuelto la problemática inicial del escaneado en 3D de este material y se ha reducido la manipulación de los objetos durante las reconstrucciones volumétricas y en la creación de embalajes. La utilización de las resinas termoplásticas para elaborar los fragmentos faltantes ha proporcionado óptimos resultados obteniendo implantes de elevada precisión capaces de reproducir el detalle decorativo de estos objetos. Por último, en los modelos virtuales han sido incorporadas sus correspondientes texturas mediante fotogrametría llevando, también a cabo, la recreación hipotética de los faltantes de manera complementaria. Con ello se facilita la visualización y recuperación completa de los objetos estudiados en 3D sin manipular los originales de forma excesiva o no justificada. Estas visualizaciones no son específicas del vidrio y para dimensionar los resultados en su justa medida, este mismo proceso se ha llevado a cabo con material arqueológico de otra naturaleza permitiendo la reconstrucción virtual de una escultura incompleta de terracota y la visualización de un cráneo paleontológico. Se propone de esta manera como interaccionar, a través de la realidad aumentada, con los modelos texturizados y mostrar como acercar las diferentes fases del proceso reconstructivo a un público potencial, al visitante de exposiciones y a los estudiosos atraídos. / La introducció de les noves tecnologies 3D en la conservació del patrimoni arqueològic ha permès obrir noves vies d'investigació. En el cas dels objectes de vidre exhumats el seu fràgil estat de conservació exigeix una manipulació extremadament acurada, que posa en risc la seva integritat física, de manera que aquesta s'hauria de reduir al màxim. La present Tesi Doctoral mostra l'aplicació de les tecnologies 3D en diferents etapes de conservació i restauració d'objectes de vidre arqueològic. S¿ofereixen així mètodes alternatius als tradicionals basats en la substitució de l'objecte original pel seu model 3D de mena que només sigui necessària la seva presència en moments puntuals per una mínima manipulació. En desenvolupar metodològicament com aplicar aquestes tècniques s'empren procediments alternatius que introdueixen nous materials de comportament desconegut. Per tant, s¿ha desenvolupat un capítol per a la caracterització d'aquests nous materials incorporats. En concret, s'han estudiat aquells utilitzats en la fase de reconstrucció del volum perdut mitjançant la creació i incorporació d'implants impresos en 3D. D'aquesta manera, s'ha pogut determinar el seu grau d'adequació i compatibilitat en els tractaments de conservació i restauració del vidre arqueològic intervingut. La metodologia proposada ha demostrat que la tecnologia 3D és aplicable en el camp de la conservació i restauració del vidre arqueològic. S'ha resolt la problemàtica inicial de l'escanejat en 3D d'aquest material i s'ha reduït la manipulació dels objectes durant les reconstruccions volumètriques i en la creació d'embalatges. La utilització de les resines termoplàstiques per elaborar els fragments mancants ha proporcionat òptims resultats obtenint implants d'elevada precisió capaços de reproduir el detall decoratiu dels objectes. Finalment, en els models virtuals s'han incorporat les textures corresponents per mitjà de la fotogrametria, realitzant també, la recreació hipotètica dels mancants de manera complementària. Amb aquesta pràctica, s'ha facilitat la visualització i recuperació completa dels objectes estudiats en 3D sense manipular els originals de forma excessiva o no justificada. Aquestes visualitzacions no són específiques del vidre i per dimensionar els resultats en la seva justa mesura, aquest mateix procés s¿ha dut a terme amb material arqueològic d'una altra naturalesa, permetent la reconstrucció virtual d'una escultura incompleta de terracota i la visualització d'un crani paleontològic. Es proposa d'aquesta manera com interaccionar, a través de la realitat augmentada, amb els models amb textura i mostrar com acostar les diferents fases del procés constructiu a un públic potencial, al visitant d'exposicions i als estudiosos atrets. / Díaz Marín, MDC. (2017). Desarrollo metodológico para la aplicación de técnicas de adquisición e impresión 3D en conservación y restauración de vidrio arqueológico, y caracterización de materiales relacionados con la fase de reconstrucción [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/90472 / TESIS
355

Malá CNC frézka / Small CNC milling machine

Kalina, Vladimír January 2017 (has links)
The content of this diploma thesis is the design and construction of small vertical CNC milling machines. In the thesis are listed and machines that appear in today's production on the market. The components are designed for tools, for ball screw, linear guide. Parts are attached to the 3D models with vertical machine and drawings of the proposed machinery.
356

Malá CNC frézka / Small CNC milling machine

Kalina, Vladimír January 2018 (has links)
The content of this diploma thesis is the design and construction of small vertical CNC milling machines. In the thesis are listed and machines that appear in today's production on the market. The components are designed for tools, for ball screw, linear guide. Parts are attached to the 3D models with vertical machine and drawings of the proposed machinery.
357

Laserový řezací plotr ocelových plátů / Laser Plotter for Cutting Steel Plates

Dokulil, Marek January 2019 (has links)
This diploma thesis is divided into two main parts. The first section is dedicated to the history and development of the laser technology. The second part describes all individual types of laser technology which are used in the industry nowadays. The next section follows with the research of various laser devices which serve mainly as a cutting tool. This knowledge gathered in the previous part was used to create the next part including the own conception of the machine. The second half of this diploma thesis deals with a research of software available at the market today. Eventually, after summarizing the characteristics of each software, the new concept and implementation of own software are made. In the final section, there are mentioned the possible extension and available upgrades. The reader should be able to create his/her own conception of the laser device and software after reading and understanding this paper.
358

Laserový řezací plotr ocelových plátů / Laser Plotter for Cutting Steel Plates

Dokulil, Marek January 2018 (has links)
This diploma thesis is divided into two main parts. The first section is dedicated to the history and development of the laser technology. The second part describes all individual types of laser technology which are used in the industry nowadays. The next section follows with the research of various laser devices which serve mainly as a cutting tool. This knowledge gathered in the previous part was used to create the next part including the own conception of the machine. The second half of this diploma thesis deals with a research of software available at the market today. Eventually, after summarizing the characteristics of each software, the new concept and implementation of own software are made. In the final section, there are mentioned the possible extension and available upgrades. The reader should be able to create his/her own conception of the laser device and software after reading and understanding this paper.
359

THE INFLUENCE OF CELLULOSE NANOCRYSTALS ON PERFORMANCE AND TRANSPORT PROPERTIES OF CEMENTITIOUS MATERIALS AND GYPSUM

Anthony Paul Becerril (9669782) 16 December 2020 (has links)
<p>Concrete is in everyday life such as parking lots, buildings, bridges, and more. To keep concrete and its constituents together, binders such as cement are used. Cement’s production process is responsible for 8% of global carbon dioxide emissions as of 2018. With global warming being a severe global issue, the challenge of reducing cement carbon dioxide emissions can be greatly beneficial with even slight improvements. Various solutions to this challenge have developed over the years in the form of processing efficiency, material substitution, or material additives. Of the additives for cement and concrete that have been ventured, nanomaterials have had a strong development in recent years. Specifically, cellulose nanomaterials in the form of nanocrystals, nanofibrils, and more have demonstrated great improvement in cement’s performance resulting in a reduction in cement produced and reduction in emissions. This study expands on the knowledge of cellulose nanocrystals as an additive for cement using the formation factor methodology. Formation factor is a resistivity ratio of the specimen and pore solution that can be used in correlation to the diffusion of chloride ions through the use of the Nernst-Einstein equation. This study also investigates the effect that cellulose nanomaterials have on the mechanical properties and thermogravimetric analysis of gypsum, a material commonly used in cement production that delays the hardening of cement. </p>
360

Agentenbasierter Programmassistent zur Verwaltung von NC-Informationen in Produktionssystemen mit Kommunikationsnetzwerken

Dang, Thien Ngon 22 April 2008 (has links)
In den letzten Jahren hat sich die rapide Entwicklung der Elektrotechnik ebenso wie die der Softwaretechnologie auf die numerischen Steuerungen in den heutigen CNC-Maschinen groß ausgewirkt. Diese numerischen Steuerungen sind sowohl intelligenter und flexibler als auch mit größerer Internspeicherkapazität ausgerüstet. Dies führt zu einer Änderung der Art und Weise, wie DNC-Systeme zu etablieren sind, besonders solcher, die auf bisher verfügbaren, aber ungleichartigen DNC-Systemen basieren. In einem solch heterogenen DNC-System wird Datenspeicherungsfähigkeit stärker verteilt angeordnet, d.h., sie ist nicht nur in einem zentralen DNC-Server vorhanden, sondern auch in Terminals oder Steuerungen selbst angelagert. Diese Änderung des Archivierungsmittels benötigt neue DNC-Software, die die DNC-Grundfunktionen voll realisiert. Zudem sollte sie auch den neuen spezifischen Softwareanforderungen entsprechen und erlauben, neue Funktionen, z.B. Maschinendatenerfassung, Betriebsdatenerfassung usw., als Module hinzuzufügen. Derzeit wird die Agententechnologie bzw. ein MAS (Multiagentensystem) als ein aussichtsreicher Ansatz angesehen, um die Probleme der heutigen komplexen Softwaresysteme, wie ungleichartige Systemumgebungen und verteilte Strukturen, zu lösen. Die vorliegende Arbeit stellt die Idee zum Aufbau eines heterogenen DNC-Systems und die Konzipierung zur Gestaltung der agentenbasierten DNC-Software vor. Ausgehend von dem vorgestellten Lösungskonzept wird zudem der Programmassistent als erster Modul der agentenbasierten DNC-Software präsentiert. / In the network-based DNC systems and especially heterogeneous DNC systems data get more distributed due to the ability to store not only in the DNC Server but also in the CNC controller or CNC Terminal. This leads a challenge to the DNC software in the implementation of its basic functions. The agent-based DNC software with assistants (ADNC) is suggested to solve the above problem. Its tasks are to collect distributed NC information and transfer data safely as well as performing other extended functions, i.e. NC program generation, machine data collection, production data collection, control machines in system, etc. The present work presented the concept to develop the ADNC and its first prototype. This prototype was developed in a process using a framework of agent-based assistants, called AgentAP. It is applicable on distributed manufacturing data and had been implemented on the agent platform JADE. The module Program Assistant, one of these prototype modules, which is responsible for management, bidirectional transfer, and monitoring change of NC programs, is also discussed.

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