To see the other types of publications on this topic, follow the link: Multi-material systems.
Dissertations / Theses on the topic 'Multi-material systems'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 43 dissertations / theses for your research on the topic 'Multi-material systems.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Cheung, Hoi-hoi, and 張凱凱. "A multi-material virtual prototyping system." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2004. http://hub.hku.hk/bib/B29727716.
Full text
2
Zhu, Wenkai, and 朱文凱. "Concurrent toolpath planning for multi-material layered manufacturing." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2009. http://hub.hku.hk/bib/B42841446.
Full text
3
Zhu, Wenkai. "Concurrent toolpath planning for multi-material layered manufacturing." Click to view the E-thesis via HKUTO, 2009. http://sunzi.lib.hku.hk/hkuto/record/B42841446.
Full text
4
PRADHANANGA, ROJEE. "MULTI-OBJECTIVE ANT COLONY SYSTEMS FOR OPTIMIZING HAZARDOUS MATERIAL TRANSPORTATION." 京都大学 (Kyoto University), 2010. http://hdl.handle.net/2433/126792.
Full text
5
Huynh, Thi Thu Thuy. "Capacity Constraints in Multi-Stage Production-Inventory Systems : Applying Material Requirments Planning Theory." Doctoral thesis, Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-7355.
Full textAbstract:
In this thesis, capacity-constrained aspects of multi-level, multi-stage productionplanning are investigated. The aim has been to extend Material Requirements Planning Theory (MRP Theory) to cover more general problems dealing with capacity constraints, in particular when non-zero lead times are present and the processes take place in continuous time. MRP Theory deals with multi-level production systems with multiple items taking place either within a discrete or continuous time framework. External demand is considered either deterministic or stochastic. Lead times are assumed to be given constants, and the Net Present Value Principle has been applied as the objective function. The Bill-of-Materials, capturing component as well as capacity requirements, in volume as well as in advanced timing due to lead times, has been described using a generalised input matrix involving Laplace transforms or z transforms. In order to be able to apply Dynamic Programming as a solution method, the system state has been defined and designed in terms of a matrix, in which historical values of cumulative production and cumulative demand are given state variables. A high power computer has been used to calculate solutions to numerical examples. Moreover, this thesis examines the fundamental equations of MRP Theory in order to analyse the possibility to obtain closed-form expressions for the time development of the system, when standard ordering rules of MRP are applied. In addition, capacity-constrained production planning problems and procedures in a paper mill have been surveyed and are presented in the form of a case study.
6
Huynh, Thi Thu Thuy. "Capacity constraints in multi-stage production-inventory systems applying material requirements planning theory /." Linköping : Department od Production Economics, Linköping Institute of Technology, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-7355.
Full text
7
Hill, Jeremy Lee. "Mechanical property determination for flexible material systems." Diss., Georgia Institute of Technology, 2016. http://hdl.handle.net/1853/54993.
Full textAbstract:
Inflatable Aerodynamic Decelerators (IADs) are a candidate technology NASA began investigating in the late 1960’s. Compared to supersonic parachutes, IADs represent a decelerator option capable of operating at higher Mach numbers and dynamic pressures. IADs have seen a resurgence in interest from the Entry, Descent, and Landing (EDL) community in recent years. The NASA Space Technology Roadmap (STR) highlights EDL systems, as well as, Materials, Structures, Mechanical Systems, and Manufacturing (MSMM) as key Technology Areas for development in the future; recognizing deployable decelerators, flexible material systems, and computational design of materials as essential disciplines for development. This investigation develops a multi-scale flexible material modeling approach that enables efficient high-fidelity IAD design and a critical understanding of the new materials required for robust and cost effective qualification methods. The approach combines understanding of the fabric architecture, analytical modeling, numerical simulations, and experimental data. This work identifies an efficient method that is as simple and as fast as possible for determining IAD material characteristics while not utilizing complicated or expensive research equipment. This investigation also recontextualizes an existing mesomechanical model through validation for structures pertaining to the analysis of IADs. In addition, corroboration and elaboration of this model is carried out by evaluating the effects of varying input parameters. Finally, the present investigation presents a novel method for numerically determining mechanical properties. A sub-scale section that captures the periodic pattern in the material (unit cell) is built. With the unit cell, various numerical tests are performed. The effective nonlinear mechanical stiffness matrix is obtained as a function of elemental strains through correlating the unit cell force-displacement results with a four node membrane element of the same size. Numerically determined properties are validated for relevant structures. Optical microscopy is used to capture the undeformed geometry of the individual yarns.
8
Pitakthapanaphong, Sasithon. "Deformation behaviour and failure predictions of multi-layered systems with a functionally graded material." Thesis, Imperial College London, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.246987.
Full text
9
Udeaja, Chika Emmanuel. "A decision support framework for construction material supply chain management using multi-agent systems." Thesis, London South Bank University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.271804.
Full text
10
Bradley, Ryan T. "A Framework for Sustainable Material Selection for Multi-Generational Components." UKnowledge, 2015. http://uknowledge.uky.edu/me_etds/61.
Full textAbstract:
The early stages of a product’s design are a critical time for decisions that impact the entire life-cycle cost. Product designers have mastered the first generation; however, they currently do not have the ability to know the impact of their decisions on the multi-generational view. This thesis aims at closing the gap between total life-cycle information and the traditional design process in order to harbor sustainable value creation among all stakeholders involved. A framework is presented that uses a combination of a life-cycle costing methodology and an evolutionary algorithm in order to achieve a sustainability assessment for a true multi-generational component. An illustration of the implementation of the framework shows the value to current engineering scenarios. A foundation is also laid for the overall future vision of this work to utilize proper databases and existing design tools to evaluate the overall sustainability and life-cycle cost of multi-generational components.
11
Lee, Moonsu. "Analytical models to evaluate system performance measures for vehicle based material-handling systems under various dispatching policies." Diss., Texas A&M University, 2005. http://txspace.tamu.edu/bitstream/handle/1969.1/2352/etd-tamu-2005A-INEN-Lee.pdf?sequence=1.
Full text
12
Inanloo, Bahareh. "A Multi-Criteria GIS-Based Route Selection Tool for Hazardous Material Transport: Consideration of Environmental Consequence, Traffic Congestions and Costs." FIU Digital Commons, 2015. http://digitalcommons.fiu.edu/etd/2262.
Full textAbstract:
Hazardous materials are substances that, if not regulated, can pose a threat to human populations and their environmental health, safety or property when transported in commerce. About 1.5 million tons of hazardous material shipments are transported by truck in the US annually, with a steady increase of approximately 5% per year.
The objective of this study was to develop a routing tool for hazardous material transport in order to facilitate reduced environmental impacts and less transportation difficulties, yet would also find paths that were still compelling for the shipping carriers as a matter of trucking cost. The study started with identification of inhalation hazard impact zones and explosion protective areas around the location of hypothetical hazardous material releases, considering different parameters (i.e., chemicals characteristics, release quantities, atmospheric condition, etc.). Results showed that depending on the quantity of release, chemical, and atmospheric stability (a function of wind speed, meteorology, sky cover, time and location of accidents, etc.) the consequence of these incidents can differ. The study was extended by selection of other evaluation criteria for further investigation because health risk as an evaluation criterion would not be the only concern in selection of routes. Transportation difficulties (i.e., road blockage and congestion) were incorporated as important factor due to their indirect impact/cost on the users of transportation networks. Trucking costs were also considered as one of the primary criteria in selection of hazardous material paths; otherwise the suggested routes would have not been convincing for the shipping companies. The last but not least criterion was proximity of public places to the routes.
The approach evolved from a simple framework to a complicated and efficient GIS-based tool able to investigate transportation networks of any given study area, and capable of generating best routing options for cargos. The suggested tool uses a multi-criteria-decision-making method, which considers the priorities of the decision makers in choosing the cargo routes.
Comparison of the routing options based on each criterion and also the overall suitableness of the path in regards to all the criteria (using a multi-criteria-decision-making method) showed that using similar tools as the one proposed by this study can provide decision makers insights in the area of hazardous material transport. This tool shows the probable consequences of considering each path in a very easily understandable way; in the formats of maps and tables, which makes the tradeoffs of costs and risks considerably simpler, as in some cases slightly compromising on trucking cost may drastically decrease the probable health risk and/or traffic difficulties. This will not only be rewarding to the community by making cities safer places to live, but also can be beneficial to shipping companies by allowing them to advertise as environmental friendly conveyors.
13
Baumann, Marion [Verfasser], and K. [Akademischer Betreuer] Furmans. "Discrete Time Analysis of Multi-Queue Systems with Multiple Departure Streams in Material Handling and Production under Different Service Rules / Marion Baumann ; Betreuer: K. Furmans." Karlsruhe : KIT Scientific Publishing, 2019. http://d-nb.info/1202111920/34.
Full text
14
Cheung, Hoi-hoi. "A versatile multi-material virtual prototyping system." Click to view the E-thesis via HKUTO, 2007. http://sunzi.lib.hku.hk/hkuto/record/B3931988X.
Full text
15
Cheung, Hoi-hoi, and 張凱凱. "A versatile multi-material virtual prototyping system." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B3931988X.
Full text
16
Carbonari, Ronny Calixto. "Projeto de multi-atuadores piezelétricos homogêneos e gradados utilizando o método de otimização topológica." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/3/3152/tde-04102016-093909/.
Full textAbstract:
Microdispositivos piezelétricos tem uma vasta aplicação em mecânica de precisão, como, por exemplo, manipulação de células, microcirurgias, equipamentos de nanotecnologia e principalmente em microeletromecanismos (MEMS). Os microdispositivos piezelétricos considerados nesta tese essencialmente consistem de uma estrutura multi-flexível atuada por duas ou mais piezocerâmicas, que geram deslocamentos e forças em direções e regiões pré-determinadas do domínio, ou seja, a estrutura multi-flexível atua como um transformador mecânico amplificando e alterando os deslocamentos gerados pelas piezocerâmicas nos movimentos de atuação. O desenvolvimento destes microdispositivos piezelétricos em sua grande maioria não utiliza ferramentas sistemáticas e genéricas. A complexidade dos movimentos de atuação torna o desenvolvimento dos microdispositivos piezelétricos complexo, principalmente devido ao surgimento de movimentos indesejados ou acoplados durante a sua atuação. Portanto, é necessário um método sistemático e eficiente como o método de otimização topológica (MOT), que incorpore na sua formulação as principais exigências de projeto dos microdispositivos, como apresentado nesse trabalho. O MOT implementado é baseado na abordagem CAMD (Distribuição Contínua da Distribuição de Material), onde as pseudo-densidades são interpoladas nos nós de cada elemento finito, resultando numa distribuição contínua de material no domínio. Um método adjunto foi implementado para o cálculo das sensibilidades. São consideradas três formulações. A primeira denominada de MAPs (Multi-Atuadores Piezelétricos) considera as regiões piezocerâmicas fixas, otimizando apenas a estrutura multi-flexível no domínio de projeto. Nesta formulação materiais não-piezelétricos (como, por exemplo, Alumínio) e vazio são distribuídos no domínio de projeto, mantendo as regiões piezocerâmicas fixas e homogêneas. Para validar os resultados obtidos com essa formulação foram fabricados protótipos de nanoposicionadores $XY$, que foram caracterizados experimentalmente utilizando técnicas de interferometria laser, considerando excitação quasi-estática. No entanto, essa primeira formulação impõe restrições no problema, limitando a optimalidade da solução obtida pela otimização topológica. Assim, surgiu a necessidade de desenvolver uma segunda formulação, que permite distribuir simultaneamente material não-piezelétrico, piezelétrico e vazio no domínio de projeto, denominada de LOMPs (Localização Ótima do Material Piezelétrico). A formulação dos LOMPs obtém simultaneamente a localização do material piezelétrico na estrutura flexível otimizada pela OT, e inclui também uma variável de projeto para determinar o ângulo ótimo entre as direções de polarização e do campo elétrico. Nesta formulação como as posições dos eletrodos não são conhecidas, ``a priori\'\', é utilizado como abordagem aplicar um campo elétrico constante para determinar a localização do material piezelétrico e conseqüentemente dos eletrodos. Finalmente, foi explorado o conceito de materiais com gradação funcional (MGFs) no projeto dos MAPs. Os MGFs apresentam uma distribuição contínua de materiais na sua microestrutura, não possuindo interface entre os materiais distribuídos, o que possibilita aumentar a vida útil do dispositivo piezelétrico. Assim, foi implementado uma terceira formulação denominada de MAPs MGFs, que permite obter a gradação ótima de materiais piezelétricos e não-piezelétricos no domínio piezocerâmico dos MAPs, conjuntamente com a topologia da estrutura multi-flexível. Essa formulação foi estendida para projetar atuadores bilaminares MGFs. Todas as formulações desenvolvidas utilizam uma função multi-objetivo, que permite controlar a rigidez e a flexibilidade minimizando o movimento acoplado, de cada movimento de atuação. Os exemplos numéricos são limitados a modelos bi-dimensionais, utilizando o estado plano de tensões e deformações mecânicas e elétricas, uma vez que a grande maioria das aplicações dos microdispositivos piezelétricos são bi-dimensionais.<br>Microtools offer significant promise in a wide range of applications such as cell manipulation, microsurgery, nanotechnology processes, and many other fields. The microtools considered in this doctoral thesis essentially consist of a multi-flexible structure actuated by two or more piezoceramic devices that when each piezoceramic is actuated, it generates an output displacement and force at a specified point of the domain and direction. The multi-flexible structure acts as a mechanical transformer by amplifying and changing the direction of the piezoceramic output displacements. Thus, the development of microtools requires the design of actuated flexible structures that can perform complex movements. The development of these microtools is still in the beginning and it can be strongly enhanced by using design tools. In addition, when multiple piezoceramic devices are involved, coupling effects in their movements become critical, especially the appearance of undesired movements, which makes the design task very complex. One way to avoid such undesirable effects is the use of a systematic design method, such as topology optimization, with appropriate formulation of the optimization problem. The topology optimization method implemented is based on the CAMD (Continuous Approximation of Material Distribution) approach where fictitious densities are interpolated at each finite element, providing a continuum material distribution in the domain. The corresponding sensitivity analysis is presented using the adjoint method. Three formulations are considered. The first formulation, called Piezoelectric Multi-Actuators (PMAs), keeps fixed piezoceramic positions in the design domain and only the flexible structure is designed by distributing some non-piezoelectric material (Aluminum, for example). $XY$ Piezoelectric Nanopositioner are manufactured and experimentally analyzed to validate the results of the topology optimization obtained using this formulation. Experimental analyses are conducted using laser interferometry to measure displacement, while considering a quasi-static excitation. However, this first formulation imposes a constraint to the position of piezoelectric material in the optimization problem limiting the optimality of the solution. Thus, the second formulation presented, called LOMPs, allows the simultaneous distribution of non-piezoelectric and piezoelectric material in the design domain, to achieve certain specified actuation movements. The optimization problem is posed as the simultaneous search for an optimal topology of a flexible structure as well as the optimal position of piezoceramics in the design domain and optimal rotation angle of piezoceramic material axes that maximize output displacements or output forces at a specified point of the domain and direction. When the distribution of a non-piezoelectric conductor material and a piezoceramic material is considered in the design domain, the electrode positions are not known ``a priori\'\'. To circumvent this problem, an electric field is applied as electrical excitation. Finally, the concept of functionally graded materials (FGM) is applied to PMAs design. FGMs are special materials that possess continuously graded properties without interfaces which can increase lifetime of piezoelectric devices. Thus, a third formulation is implemented to find the optimum gradation and polarization sign variation of piezoceramic FGMs, while simultaneously optimizing the multi-flexible structural configuration. This formulation is extended to design bimorph type FGM actuators. For all developed formulations, a multi-objective function is defined that controls the stiffness and flexibility, minimizing the coupling movement of each actuated movement. The present examples are limited to two-dimensional models because most part of the applications for such micro-tools are planar devices.
17
Zeng, Jiani. "Expand material presence to material experience with volumetric thinking : voxel based multi-material printing in designing objects." Thesis, Massachusetts Institute of Technology, 2020. https://hdl.handle.net/1721.1/129844.
Full textAbstract:
Thesis: S.M. in Engineering and Management, Massachusetts Institute of Technology, System Design and Management Program, February, 2020<br>Cataloged from student-submitted version of thesis.<br>Includes bibliographical references (pages 68-70).<br>Material serves as the first touchpoint between an object and a person. In current product development, material together with color and finishing is regarded as a separate entity from the form and function design. Every material needs to be paired with a series of optimal manufacturing processes for the desired effect. In many cases, this is handled with material design specialists. People perceive a material primarily by its surface: chromatic, tactile, and decorative identity it displays or the temperature and hardness when touching it. Typically, this material surface can be viewed as a two-dimensional entity that reveals limited-expression and information to be delivered via human intervention. In this thesis, we propose to get away from surface obsession in object and industrial design, by adding another dimension to the material interface. By embedding information into three-dimensional matter, we introduce volumetric material: a new material organization that responds directly to the user intervention or the environment. With multi-material 3D printing, we envision a future in product development where the design of surface detail, texture, reflexivity can finally be merged with the overall product composition from the beginning of the design process. With voxel printing capability, we designed and tested material interface with depth and explored volumetric behavior that is both visually and functionally meaningful to the user, and discussed the results.<br>by Jiani Zeng.<br>S.M. in Engineering and Management<br>S.M.inEngineeringandManagement Massachusetts Institute of Technology, System Design and Management Program
18
Rocha, André Dionísio Bettencourt da Silva. "An agent based architecture for material handling systems." Master's thesis, Faculdade de Ciências e Tecnologia, 2013. http://hdl.handle.net/10362/10504.
Full textAbstract:
Dissertação para obtenção do Grau de Mestre em
Engenharia Electrotécnica e de Computadores<br>In the recent past, market requirements and consequently the production lines changed too. With the customization of products and the growing number of products to produce, the dy-namism and flexibility of the lines are now requirements of extreme importance.
A traditional approach indicates great difficulty in satisfying those needs and as such has appeared some proposals in order to solve them. The proposed approaches are mostly related to scheduling and production planning.
The transportation system is not usually inserted in the control architecture and system reconfiguration, constantly being put aside in order to this issue.
This work proposes architecture to support self-organized transportation system, where it performs control functions and management. The architecture was developed for a system com-prising conveyors where the stations operate.
The proposed work is a multi-agent architecture that use Dijkstra’s algorithm to improve the routing of products and materials. The main features of architecture are load balancing pre-sent in conveyors and ability to plug and unplug stations in runtime.
The architecture was first tested in a virtual environment in order to check the behavior of the same and was subsequently tested in a real industrial cell in order to demonstrate its use in a real system.
19
Hung, Chang-Yu. "Material Cutting Plan Generation Using Multi-Expert and Evolutionary Approaches." Diss., Virginia Tech, 2000. http://hdl.handle.net/10919/28256.
Full textAbstract:
Firms specializing in the construction of large commercial buildings and factories must often design and build steel structural components as a part of each project. Such firms must purchase large steel plates, cut them into pieces and then weld the pieces into H-beams and other construction components. The details of the order and the production operation are specified in the "cutting plan." This dissertation focuses on solving this "cutting plan generation" problem with the goal of minimizing cost.
Two solution approaches are proposed in this dissertation: a multi-expert system and an evolutionary algorithm. The expert system extends the field by relying on the knowledge of multiple experts. Furthermore, unlike traditional rule-base expert systems, this expert system (XS) uses procedural rules to capture and represent experts' knowledge. The second solution method, called CPGEA, involves development of an evolutionary algorithm based on Falkenauer's grouping genetic algorithm.
A series of experiments is designed and performed to investigate the efficiency and effectiveness of the proposed approaches. Two types of data are used in the experiments. Historical data are real data provided by a construction company. Solutions developed manually and implemented are available. In addition, simulated data has been generated to more fully test the solution methods. Experiments are performed to optimize CPGEA parameters as well as to compare the approaches to each other, to known solutions and to theoretical bounds developed in this dissertation.
Both approaches show excellent results in solving historical cases with an average cost 1% above the lower bound of the optimal solution. However, as revealed by experiments with simulated problems, the performance decreases in cases where the optimal solution includes multiple identical plates. The performance of the XS is affected by this problem characteristic more than that of CPGEA. While CPGEA is more robust in effectively solving a range of problems, the XS requires substantially less processing time. Both approaches can be useful in different practical situations.<br>Ph. D.
20
Venkataraayan, Kavitha. "Multi-wavelength, multi-beam, photonic based sensor for object discrimination and positioning." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2012. https://ro.ecu.edu.au/theses/488.
Full textAbstract:
Over the last decade, substantial research efforts have been dedicated towards the development of advanced laser scanning systems for discrimination in perimeter security, defence, agriculture, transportation, surveying and geosciences. Military forces, in particular, have already started employing laser scanning technologies for projectile guidance, surveillance, satellite and missile tracking; and target discrimination and recognition. However, laser scanning is relatively a new security technology. It has previously been utilized for a wide variety of civil and military applications. Terrestrial laser scanning has found new use as an active optical sensor for indoors and outdoors perimeter security. A laser scanning technique with moving parts was tested in the British Home Office - Police Scientific Development Branch (PSDB) in 2004. It was found that laser scanning has the capability to detect humans in 30m range and vehicles in 80m range with low false alarm rates. However, laser scanning with moving parts is much more sensitive to vibrations than a multi-beam stationary optic approach. Mirror device scanners are slow, bulky and expensive and being inherently mechanical they wear out as a result of acceleration, cause deflection errors and require regular calibration.
Multi-wavelength laser scanning represent a potential evolution from object detection to object identification and classification, where detailed features of objects and materials are discriminated by measuring their reflectance characteristics at specific wavelengths and matching them with their spectral reflectance curves. With the recent advances in the development of high-speed sensors and high-speed data processors, the implementation of multi-wavelength laser scanners for object identification has now become feasible.
A two-wavelength photonic-based sensor for object discrimination has recently been reported, based on the use of an optical cavity for generating a laser spot array and maintaining adequate overlapping between tapped collimated laser beams of different wavelengths over a long optical path. While this approach is capable of discriminating between objects of different colours, its main drawback is the limited number of security-related objects that can be discriminated.
This thesis proposes and demonstrates the concept of a novel photonic based multi-wavelength sensor for object identification and position finding. The sensor employs a laser combination module for input wavelength signal multiplexing and beam overlapping, a custom-made curved optical cavity for multi-beam spot generation through internal beam reflection and transmission and a high-speed imager for scattered reflectance spectral measurements. Experimental results show that five different laser wavelengths, namely 473nm, 532nm, 635nm, 670nm and 785nm, are necessary for discriminating various intruding objects of interest through spectral reflectance and slope measurements. Various objects were selected to demonstrate the proof of concept.
We also demonstrate that the object position (coordinates) is determined using the triangulation method, which is based on the projection of laser spots along determined angles onto intruding objects and the measurement of their reflectance spectra using an image sensor. Experimental results demonstrate the ability of the multi-wavelength spectral reflectance sensor to simultaneously discriminate between different objects and predict their positions over a 6m range with an accuracy exceeding 92%.
A novel optical design is used to provide additional transverse laser beam scanning for the identification of camouflage materials. A camouflage material is chosen to illustrate the discrimination capability of the sensor, which has complex patterns within a single sample, and is successfully detected and discriminated from other objects over a 6m range by scanning the laser beam spots along the transverse direction.
By using more wavelengths at optimised points in the spectrum where different objects show different optical characteristics, better discrimination can be accomplished.
21
Chen, Da. "A Multi-Material Projection Stereolithography System for Manufacturing Programmable Negative Poissons Ratio Structures." Thesis, Virginia Tech, 2017. http://hdl.handle.net/10919/74961.
Full textAbstract:
Digital light Projection based Additive Manufacturing (AM) enables fabrication of complex three-dimensional (3D) geometries for applications ranging from rapid prototyping jet parts to scaffolds for cell cultures. Despite the ability in producing complex, three-dimensional architectures, the state of art DLP AM systems is limited to a single homogenous photo-polymer and it requires a large volume of resin bath to begin with. Extensible Multi-material Stereolithography (EMSL) is a novel high-resolution projection stereolithography system capable of manufacturing hybrid 3D objects. This system provides new capabilities, allowing more flexible design criteria through the incorporation of multiple feedstock materials throughout the structure. With EMSL manufacturing ability, multi-material programmable negative Poissons ratio honeycomb reentrant structures are realized.
Researchers have been studying auxetic structures over decades, the mechanical property control of auxetic structure mainly relies on geometry design in previous studies. Now with the help of EMSL system, other design variables associated with auxetic structures, such as material properties of local structural members, are added into design process. The additional variables are then proved to have significant effects on the material properties of the auxetic structures. The ability to accurately manufacture multi-material digital design will not only allow for novel mechanical and material researches in laboratory, but also extend the additive manufacturing technology to numerous future applications with characteristics such as multiple electrical, electromechanical and biological properties. The design and optimization of EMSL system realizes novel structures have not been producible, therefore it will stimulate new possibilities for future additive manufacturing development.<br>Master of Science
22
Rahman, Sazzadur. "Knowledge-based decision support system for multi criteria roofing material selection and cost modelling." Thesis, University of Ulster, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.523124.
Full text
23
Kim, Hee Sun. "Nonlinear multi-scale anisotropic material and structural models for prosthetic and native aortic heart valves." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/29671.
Full textAbstract:
Thesis (Ph.D)--Civil and Environmental Engineering, Georgia Institute of Technology, 2009.<br>Committee Chair: Haj-Ali, Rami; Committee Member: White, Donald; Committee Member: Will, Kenneth; Committee Member: Yavari, Arash; Committee Member: Yoganathan, Ajit. Part of the SMARTech Electronic Thesis and Dissertation Collection.
24
Balasubramaniam, Arjun, and Naga Lakshmana Naidu Navuluri. "Analysis and improvement of material handling in a highly customized multi-variant product-based production system." Thesis, Tekniska Högskolan, Högskolan i Jönköping, JTH, Produktionsutveckling, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-47399.
Full textAbstract:
Twenty first century manufacturing is characterized by customer specific products. Customers expect greater differentiation in the products that companies offer to them, thus changing the whole landscape of production. Greater the variety of products being offered to customers, greater is the complexity of shop floor operations. This complexity is translated to all the operations in the shop floor including material handling and inventory control. To overcome this situation, many manufacturers have turned to “Lean Manufacturing” to gain a competitive edge in the market by reducing costs and improving productivity in all operations throughout the shop floor. Therefore, this purpose of this thesis is to analyze the material handling of a highly customized multi-variant product-based production system. The thesis represents a case study that was done at a caravan manufacturing company in Tenhult, Sweden. During the study, data was gathered from field notes, observations and multiple semi-structured interviews. The findings were analyzed with respect to a theoretical background which was generated through an extensive literature review that was carried out throughout the research. Our analysis was based on a systems approach where the findings were categorized into three dimensions that affect material handling and inventory control. These dimensions are warehouse management systems, culture, and production management, which contribute to successful implementation of lean into the material handling operations and inventory control. In conclusion, the results show that efficient material handling and inventory control can only be achieved by finding a synergy between technology, people and organization. Our results also show that soft issues like organizational culture and employee culture need to be addressed along with technological issues because only when an alignment between people, technology and business objectives and values is achieved, lean implementation can be successful. Our results also show the need for better supplier customer collaboration to reduce inventory levels and material handling operation.
25
Srinivaas, Sujith. "Testing and Analysis of Innovative High-Speed Automotive Fastening System for Multi Materials." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1587397193415362.
Full text
26
Velasco, Fernández Raúl. "The pattern of socio-ecological systems. A focus on energy, human activity, value added and material products." Doctoral thesis, Universitat Autònoma de Barcelona, 2017. http://hdl.handle.net/10803/457589.
Full textAbstract:
Esta tesis trata del desarrollo de herramientas analíticas dentro de un innovador marco teórico con el objetivo de generar datos cuantitativos más útiles en relación al análisis de la sostenibilidad. En particular, el enfoque metodológico explorado quiere integrar la información cuantitativa referente a diferentes dimensiones de análisis (económico, demográfico, social, biofísico y ambiental), así como diferentes escalas (macro-regional, regional y nacional) y diferentes niveles (el total de la economía, sus sectores y subsectores).
Como se analiza en detalle en el capítulo 3, cada vez es más evidente que el análisis biofísico ha de ser más holístico. Asimismo, tiene que ser capaz de contextualizar y dar sentido a las evaluaciones cuantitativas concretas que produce. Los indicadores agregados que se refieren a toda la economía o los coeficientes técnicos específicos que describen procesos individuales, no son coherentes entre sí, y cuando se usan aisladamente no proporcionan información confiable sobre el funcionamiento de la economía.
El innovador marco teórico utilizado para esta investigación es el Análisis Integrado Multiescalar del Metabolismo Societal y Ecosistémico (MuSIASEM de sus siglas en inglés), el cual permite desarrollar un análisis cuantitativo relacional capaz de manejar múltiples escalas y dimensiones, tal como se requiere para abordar temas de sostenibilidad. El objetivo de este método (y el de mis exploraciones) ha sido la identificación de los factores más relevantes que deben considerarse para estudiar el comportamiento del patrón metabólico de las sociedades modernas.
Mi investigación se inicia con una aplicación básica de los métodos de MuSIASEM, comparando los cambios de las economías de China e India durante el período entre 1971 y 2010 (Capítulo 2). Adoptando un procedimiento ya establecido, este análisis se basa en datos referentes a la energía (medida en equivalente de energía bruta requerida), el valor añadido y la actividad humana en tres niveles de análisis: (i) la sociedad en conjunto; (ii) el sector del trabajo remunerado frente al de los hogares, y (iii) el conjunto de sectores económicos compuestos por la agricultura, la industria y los servicios. Este análisis sirvió para identificar relevantes factores que afectaron los patrones metabólicos de estos dos grandes países: su estructura demográfica, el nivel de capitalización de sus diferentes sectores o los distintos efectos que estas capitalizaciones generaron sobre el nivel de vida material en los hogares.
Posteriormente, se desarrolla un nuevo protocolo de análisis capaz de contabilizar diferentes tipos de energía según sus distintas cualidades. Esto fue requerido dada la insatisfactoria contabilidad de los indicadores biofísicos existentes (Capítulo 3). La contabilidad de "energía" ya no se realiza en Julios de energía bruta, sino utilizando diferentes categorías de "Julios" que se refieren a distintos vectores energéticos (electricidad, combustibles y calor de proceso).
Con el fin de aplicar el nuevo protocolo, se realiza un gran estudio de caso considerando el patrón metabólico de los países europeos (UE27 + Noruega). Asimismo, este análisis se lleva a cabo a través de diferentes escalas, llegando a distinguir hasta 13 subsectores dentro del sector de la Manufactura y la Construcción (Capítulo 4).
Finalmente, la última exploración de las potencialidades del enfoque está relacionada con un intento de incluir la contabilidad de flujos de materiales, empezando por el análisis de los productos producidos y el nivel de importaciones y exportaciones de un subsector del sector industrial (Capítulo 5). El análisis demuestra que este enfoque puede utilizarse eficazmente para: (i) identificar categorías relevantes de los procesos de producción que tienen lugar a niveles inferiores del de subsector, y (ii) caracterizar el nivel de apertura de los subsectores (el grado de externalización a otros sistemas socio-ecológicos). Este último análisis se realiza para 22 países de la UE.<br>This thesis is about the development of analytical tools within an innovative theoretical framework, with the goal of generating more useful quantitative data in relation to the analysis of sustainability. In particular, the methodological approach explored here wants to integrate quantitative information referring to different dimensions of analysis (economic, demographic, social, biophysical and environmental), different scales (macro-regional, regional and national) and different levels of analysis (whole economy, economic sectors and subsectors).
As discussed in detail in Chapter 3, it is becoming more and more evident that biophysical analysis has to become more holistic. It has to be capable of contextualizing and giving meaning to the individual quantitative assessments it produces. Aggregate indicators referring to the whole economy or to specific technical coefficients describing individual processes are not coherent with each other and when used in isolation do not provide reliable information about the performance of the economy.
The innovative theoretical framework I used for my exploration is the Multi-Scale Integrated Analysis of Societal and Ecosystem Metabolism (MuSIASEM), which allows developing a quantitative relational analysis capable of dealing with multiple scales and dimensions, as required for dealing with sustainability issues. The goal of the method (and of my explorations) has been the identification of the relevant factors that have to be considered in order to study the performance of the metabolic pattern of modern societies.
My research started – Chapter 2 - with a basic application of MuSIASEM’s methods to compare the changes in the performance of the economies of China and India in the period between 1971 and 2010. Adopting the established accounting procedure, this analysis was based on data referring to energy (measured in gross energy requirement), value added and human activity at three levels of analysis: (i) average society; (ii) paid work vs. households, and (iii) the set of economic sectors made up of agriculture, industry and services. This analysis identified relevant factors affecting the metabolic patterns of these two big countries: their demographic structure, the level of capitalization of their different sectors or the different effects that this capitalization generated on the material standard of living in the household sector.
Afterwards, I developed a new protocol of analysis able to keep the accounting of energy forms of different qualities separate. This was required by the unsatisfactory situation with existing biophysical indicators of performance (Chapter 3). The accounting of “energy” was no longer done in Joules of gross energy requirement, but using different categories of “Joules” referring to different energy carriers (electricity, fuels and process heat).
In order to apply the new protocol across different scales, it was applied to a large case study, by considering the metabolic pattern of European countries (EU27 + Norway). Moreover, this analysis was carried out across many levels, arriving to distinguish up to 13 subsectors inside the Manufacturing and Construction sector (Chapter 4).
Finally, the last exploration of the potentialities of the approach was related to an attempt to include material flow accounting, starting with the analysis of the products produced and the level of imports and exports of a subsector of the industrial sector (Chapter 5). The analysis shows that the approach can be effectively used to: (i) identify relevant categories of production processes taking place at lower levels than subsectors, and (ii) characterize the level of openness of the subsectors (the degree of externalization to other socio-ecological systems). This last analysis was carried out for EU22 countries.
27
Dal, Taylan. "A dynamic behavior modeler for future inclusion into a multi-tasking motion planning system for material handling in construction." Thesis, This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-08142009-040314/.
Full text
28
Sordelet, Tyler Christopher. "Design and optimization of a multi-particle accelerator beam transport and delivery system for material irradiation in nuclear and fusion science." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/76574.
Full textAbstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering, February 2012.<br>"December 2011." Cataloged from PDF version of thesis.<br>Includes bibliographical references (p. 129-131).<br>A beam delivery and transport system were designed for the use in MIT Materials Test Facility (M2TF). The purpose of this beam delivery system was to design a 36 MeV Proton Cyclotron for DPA accumulation and a 100 MeV Helium Cyclotron for irradiation failure and volumetric helium accumulation simulation. The purpose of the beam transport system was to incorporate the two cyclotrons into the beam transport system and transport their beams to the target chamber, the location of the target sample. The cyclotrons were designed using Opera-3D and Acfields. The beam transport system was designed using TRANSPORT. The shielding analysis for the entire facility was designed using SolidWorks and calculated with MCNP/X The design specification of M2TF with respect to beam energy, current density, and control were achieved based on these design tools and previously developed analytic methods. The design process for the cyclotrons resulted in a 4.3T lsochronous Proton Cyclotron and 3.9T Isochronous Helium Cyclotron. A beam transport system connected the cyclotrons to the target chamber with three doublet quadrupoles and one dipole bending magnet The shielding calculation proved the total effect dose rate in rem/year for the final design facility was safe for operational workers.<br>by Tyler Christopher Sordelet.<br>S.M.
29
Webster, Keith Gordon. "Investigation of Close Proximity Underwater Explosion Effects on a Ship-Like Structure Using the Multi-Material Arbitrary Lagrangian Eulerian Finite Element Method." Thesis, Virginia Tech, 2007. http://hdl.handle.net/10919/31077.
Full textAbstract:
This thesis investigates the characteristics of a close proximity underwater explosion and its effect on a ship-like structure. Finite element model tests are conducted to verify and validate the propagation of a pressure wave generated by an underwater explosion through a fluid medium, and the transmission of the pressure wave in the fluid to a structure using the Multi-Material Arbitrary Lagrangian/Eulerian method. A one dimensional case modeling the detonation of a spherical TNT charge underwater is investigated. Three dimensional cases modeling the detonation of an underwater spherical TNT charge, and US Navy Blast Test cases modeling a shape charge and a circular steel plate, and a shape charge and a Sandwich Plate System (SPS) are also investigated. This thesis provides evidence that existing tools and methodologies have some capability for predicting early-time/close proximity underwater explosion effects, but are insufficient for analyses beyond the arrival of the initial shock wave. This thesis shows that a true infinite boundary condition, a modified Gruneisen equation of state near the charge, and the ability to capture shock without a very small element size is needed in order to provide a sufficient means for predicting early-time/close proximity underwater explosion effects beyond the arrival of the initial shock wave.<br>Master of Science
30
Ali, Muzdalifa. "Using dynamic programming and unsupervised learning to optimize material flow in assembly line supermarket : A case study of Volvo Powertrain at Skövde." Thesis, Högskolan i Skövde, Institutionen för informationsteknologi, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-17597.
Full textAbstract:
Replenishment is an important process in automotive industries. It is the process by which parts required at assembly lines are stored and organized in assembly lines supermarket. Over many years replenishment have been done with the aim of positively impacting the varying demand frequency of articles in multi flows mixed-model assembly lines (MMALs) operating in just-in-time (JIT) fashion. However, a series of successive replenishment actions have negative impacts on the number of reallocation movements of parts within volume flows of supermarkets especially within a context of multi-flows supermarkets (MFSs). The cost of movements of parts within the supermarket has not been taken into consideration in previous replenishment methods. This is a significant problem since both un-optimized reallocation movements, and articles misplacement resolutions lead to production halts which cost assembly plants valuable time and money. Therefore, this research study proposes a replenishment method that optimizes flow of material within multi-flow assembly lines supermarkets and hence reduces the cost due to reallocation movement of multi-flow assembly lines supermarkets. The proposed method has been evaluated in the context of Volvo automobile engine assembly plant in Skövde. The proposed replenishment method has been evaluated by conducting an experiment using real-world data for the assembly plant in context. Performance metrics such as accuracy, F1-score, precision, sensitivity, and specificity were used to demonstrate the utility and validity of the proposed method. The evaluation results showed that the proposed method for optimizing material flow in supermarkets performed better than the existing method. In addition to utility, the proposed method provides contribution to knowledge by providing means for the industry to adopt replenishment method that takes into consideration the cost of reallocation movements of the parts within the supermarket.
31
Altunyurt, Nevin. "Integration and miniaturization of antennas for system-on-package applications." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/33903.
Full textAbstract:
Wireless communications have been an indispensable aspect of everyday life, and there is an increasing consumer demand for accessing several wireless communication technologies from a single, compact, mobile device. System-on-package (SOP) technology is an advanced packaging technology that has been proven to realize the convergence of multiple functions into miniaturized, high-performance systems to meet this demand. With the advancements in the SOP technology, the miniaturization of the front-end module has been achieved using embedded passives in multilayer packages. However, the integration of the antenna directly on the module package is still the barrier to achieve a fully-integrated, high-performance RF SOP system. The main reason for this missing link is that integrating the antenna on the package requires miniaturizing the antenna, which is a difficult task.
The focus of this dissertation is to design high-performance antennas along with developing techniques for miniaturization and system-on-package (SOP) integration of these antennas to achieve fully-integrated SOP systems using advanced multilayer organic substrates and thin-film magneto-dielectric materials. The targeted spectrum for the antenna designs are 2.4/5 GHz WLAN/WiMAX and 60 GHz WPAN bands. Several novel antenna designs and configurations to integrate the antenna on the package along with the module are discussed in this dissertation. The advanced polymers used in this research are Liquid Crystalline Polymer (LCP), RXP, and thin-film magneto-dielectrics.
32
Vuoluterä, Fredrik, and Oliver Carlén. "Analysis of material flow and simulation-based optimization of transportation system : The combination of simulation and Lean to evaluate and design a transportation system." Thesis, Högskolan i Skövde, Institutionen för ingenjörsvetenskap, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-15974.
Full textAbstract:
The thesis has been performed in cooperation with a Swedish manufacturing company. The manufacturing site of the company is currently implementing a new machine layout in one of its workshops. The new layout will increase the product flow to another workshop on the site. The goal of the thesis was to evaluate the current transportation system and suggest viable alternatives for the future product flow. By means of discrete event simulation these alternative solutions would be modelled and subsequently optimized to determine if their performance is satisfactory. An approximated investment cost of the solutions would also be estimated. By performing a literature review and creating a frame of reference, a set of relevant methodologies were selected to provide a foundation to the project. Following these methodologies, the current state of transportation was identified and mapped using Value Stream Mapping. Necessary data from the current flow was identified and collected from the company computer systems. This data was deemed partly inaccurate and further verification was needed. To this end, a combination of Genchi Genbutsu, assistance from onsite engineers and a time study was used to verify the unreliable data points. The data sets from the time study and the company data which was deemed valid were represented by statistical distributions to provide input for the simulation models. Two possible solutions were picked for evaluation, an automated guided vehicle system and a tow train system. With the help of onsite personnel, a Kaizen Event was performed in which new possible routing for the future flow was evaluated. A set of simulation models portraying the automated guided vehicle system and the tow train system were developed with the aid of simulation software. The results from these models showed a low utilization of both systems. A new set of models were developed, which included all the product flows between the workshops. The new flows were modelled as generic pallets with the arrival distribution based on historical production data. This set of models were then subject for optimization with regard to the work in process and lead time of the system. The results from the optimization indicates the possibility to reduce the overall work in process by reducing certain buffer sizes while still maintaining the required throughput. These solutions were not deemed to be ready for implementation due to the low utilization of the transportation systems. The authors instead recommend expanding the scope of the system and including other product flows to reach a high utilization.
33
Gyllenbreider, Emelie, and Stina Odencrants. "En miljö- och kostnadsjämförelse av insamlingssystem för källsortering närmare hushållen." Thesis, Linköpings universitet, Industriell miljöteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-138844.
Full textAbstract:
För att kunna uppnå de tuffare materialåtervinningsmålen som börjar gälla i Sverige år 2020 måste utsorteringen av bland annat plast-, papper- och metallförpackningar öka. Hushållsavfall beskrivs som en av de mest miljöpåverkande kategorin av avfall men samtidigt den kategori där det finns mest potential för förbättringar genom bättre hantering. Plockanalyser från 67 procent av Sveriges kommuner mellan åren 2013 och 2016 visar att ett svenskt villahushålls restavfall innehåller 34,5 procent förpackningar och returpapper som skulle kunna sorteras ut för materialåtervinning. Ett sätt att öka utsorteringen av producentansvarsmaterial från restavfallet och då kunna uppnå materialåtervinningsmålen är att kommuner erbjuder enklare samt ökad service i form av källsortering närmare hushållen. Tidigare studier har jämfört systemen optisk sortering och fyrfackskärl, som båda innebär källsortering närmare hushållen, med det vanligaste systemet i Sverige idag, tvåkärl, som inte innebär en ökad service genom kvalitativa metoder. Systemen har inte jämförts med kvantitativa metoder utifrån ekonomi eller miljö och inte heller med ett nytt koncept som heter Kvartersnära insamling. Den här rapporten har därför jämfört de fyra systemen utifrån aspekterna miljö och ekonomi med hjälp av verktygen livscykel- och livscykelkostnadsanalys som applicerades i ett område i Kristinehamns kommun för att på så sätt komma närmare verkligheten. Resultatet visar att systemet kvartersnära insamling har lägst miljöpåverkan i de undersökta miljöpåverkanskategorierna och därefter fyrfackskärl, optisk sortering och högst miljöpåverkan har systemet tvåkärl utifrån förutsättningarna och antagandena som har applicerats i studien. Livscykelanalysen visar att miljönyttan med materialåtervinningen överväger konsekvenserna av ökade transporter. Systemet med lägst livscykelkostnad är tvåkärl och sedan kvartersnära insamling, optisk sortering och dyrast livscykelkostnad har fyrfackskärl utifrån antaganden och de förutsättningar som använts i studien. En slutsats från rapporten är att det är viktigt att även undersöka andra aspekter förutom ekonomi och miljö vid val av insamlingssystem då resultatet till stor del beror på andra aspekter bland annat användarens uppfattning om systemet.<br>To achieve the stricter material recycling goals in Sweden in 2020 plastic-, metallic- and paper packages need to be better sorted from the household waste. Household waste might have the highest environmental impact compared with other sorts of waste but household waste has the highest potential to lower its impact. Waste pick-up analysis from 67 percent of Sweden's municipalities between 2013 and 2016 show that a Swedish household waste contains 34.5 percent packaging and recycled paper that could be sorted for recycling. The producers of that material have the responsibility to collect it but it does not work as well as planned because of different circumstances. One way to increase the recycling of the material from the household waste and then achieve the material recycling goals is that municipalities offer simpler and increased service in the form of source sorting closer to the households. Previous studies have compared the systems of optical sorting and multi compartment bin, which offer separation at sources closer to the households. Moreover, those systems have been compared with the most common system in Sweden today, two bins, which do not involve increased service. The systems have not been compared with quantitative methods based on economics or the environment, nor with a new concept called district collection. This report has compared the four systems. The aspects that have been compared are the environmental aspects and economical aspects by using the tools lifecycle assessment and lifecycle cost assessment. Moreover, the systems have been fictive studied in an area in the municipality of Kristinehamn, in order to get closer to reality. The results indicate that the collection system district collection had the lowest environmental impact followed by multi compartment bin and then optical sorting. Moreover, the system with two bins has the highest impact in the studied environmental impact categories according to the assumptions that have been applied in the study. The lifecycle assessment indicates that the benefits with material recycling is higher than the environmental impacts of increased transportation. The system with lowest lifecycle cost is the system with two bins and then the district collection. The system with highest lifecycle cost is the system optical sorting and the system with the second highest cost is multi compartment bin according to the assumptions that have been applied in the study. One conclusion from the study is that it is important to investigate more aspects than environmental impact and costs when to decide collection system. It is because the results depends on the other aspects as well like the users experience about the system.
34
Fenollosa, Artés Felip. "Contribució a l'estudi de la impressió 3D per a la fabricació de models per facilitar l'assaig d'operacions quirúrgiques de tumors." Doctoral thesis, Universitat Politècnica de Catalunya, 2019. http://hdl.handle.net/10803/667421.
Full textAbstract:
La present tesi doctoral s’ha centrat en el repte d’aconseguir, mitjançant Fabricació Additiva (FA), models per a assaig quirúrgic, sota la premissa que els equips per fer-los haurien de ser accessibles a l’àmbit hospitalari. L’objectiu és facilitar l’extensió de l’ús dels prototips com a eina de preparació d’operacions quirúrgiques, transformant la pràctica mèdica actual de la mateixa manera que en el seu moment ho van fer tecnologies com les que van facilitar l’ús de radiografies. El motiu d’utilitzar FA, en lloc de tecnologies més tradicionals, és la seva capacitat de materialitzar de forma directa les dades digitals obtingudes de l’anatomia del pacient mitjançant sistemes d’escanejat tridimensional, fent possible l’obtenció de models personalitzats. Els resultats es centren en la generació de nou coneixement sobre com aconseguir equipaments d’impressió 3D multimaterials accessibles que permetin l’obtenció de models mimètics respecte als teixits vius. Per facilitar aquesta buscada extensió de la tecnologia, s’ha focalitzat en les tecnologies de codi obert com la Fabricació per Filament Fos (FFF) i similars basades en líquids catalitzables. La recerca s’alinea dins l’activitat de desenvolupament de la FA al CIM UPC, i en aquest àmbit concret amb la col·laboració amb l’Hospital Sant Joan de Déu de Barcelona (HSJD). El primer bloc de la tesi inclou la descripció de l’estat de l’art, detallant les tecnologies existents i la seva aplicació a l’entorn mèdic. S’han establert per primer cop unes bases de caracterització dels teixits vius -sobretot tous- per donar suport a la selecció de materials que els puguin mimetitzar en un procés de FA, a efectes de millorar l’experiència d’assaig dels cirurgians. El caràcter rígid dels materials majoritàriament usats en impressió 3D els fa poc útils per simular tumors i altres referències anatòmiques. De forma successiva, es tracten paràmetres com la densitat, la viscoelasticitat, la caracterització dels materials tous a la indústria, l’estudi del mòdul elàstic de teixits tous i vasos, la duresa d’aquests, i requeriments com l’esterilització dels models. El segon bloc comença explorant la impressió 3D mitjançant FFF. Es classifiquen les variants del procés des del punt de vista de la multimaterialitat, essencial per fer models d’assaig quirúrgic, diferenciant entre solucions multibroquet i de barreja al capçal. S’ha inclòs l’estudi de materials (filaments i líquids) que serien més útils per mimetitzar teixits tous. Es constata com en els líquids, en comparació amb els filaments, la complexitat del treball en processos de FA és més elevada, i es determinen formes d’imprimir materials molt tous. Per acabar, s’exposen sis casos reals de col·laboració amb l’HJSD, una selecció d’aquells en els que el doctorand ha intervingut en els darrers anys. L’origen es troba en la dificultat de l’abordatge d’operacions de resecció de tumors infantils com el neuroblastoma, i a la iniciativa del Dr. Lucas Krauel. Finalment, el Bloc 3 té per objecte explorar nombrosos conceptes (fins a 8), activitat completada al llarg dels darrers cinc anys amb el suport dels mitjans del CIM UPC i de l’activitat associada a treballs finals d’estudis d’estudiants de la UPC, arribant-se a materialitzar equipaments experimentals per validar-los. La recerca ampla i sistemàtica al respecte fa que s’estigui més a prop de disposar d’una solució d’impressió 3D multimaterial de sobretaula. Es determina que la millor via de progrés és la de disposar d’una pluralitat de capçals independents a fi de capacitar la impressora 3D per integrar diversos conceptes estudiats, materialitzant-se una possible solució. Cloent la tesi, es planteja com seria un equipament d’impressió 3D per a models d’assaig quirúrgic, a fi de servir de base per a futurs desenvolupaments.<br>La presente tesis doctoral se ha centrado en el reto de conseguir, mediante Fabricación
Aditiva (FA), modelos para ensayo quirúrgico, bajo la premisa que los equipos para
obtenerlos tendrían que ser accesibles al ámbito hospitalario. El objetivo es facilitar la
extensión del uso de modelos como herramienta de preparación de operaciones
quirúrgicas, transformando la práctica médica actual de la misma manera que, en su
momento, lo hicieron tecnologías como las que facilitaron el uso de radiografías. El
motivo de utilizar FA, en lugar de tecnologías más tradicionales, es su capacidad de
materializar de forma directa los datos digitales obtenidos de la anatomía del paciente
mediante sistemas de escaneado tridimensional, haciendo posible la obtención de
modelos personalizados.
Los resultados se centran en la generación de nuevo conocimiento para conseguir
equipamientos de impresión 3D multimateriales accesibles que permitan la obtención de
modelos miméticos respecto a los tejidos vivos. Para facilitar la buscada extensión de la
tecnología, se ha focalizado en las tecnologías de código abierto como la Fabricación
por Hilo Fundido (FFF) y similares basadas en líquidos catalizables. Esta investigación
se alinea dentro de la actividad de desarrollo de la FA en el CIM UPC, y en este ámbito
concreto con la colaboración con el Hospital Sant Joan de Déu de Barcelona (HSJD).
El primer bloque de la tesis incluye la descripción del estado del arte, detallando las
tecnologías existentes y su aplicación al entorno médico. Se han establecido por primera
vez unas bases de caracterización de los tejidos vivos – principalmente blandos – para
dar apoyo a la selección de materiales que los puedan mimetizar en un proceso de FA, a
efectos de mejorar la experiencia de ensayo de los cirujanos. El carácter rígido de los
materiales mayoritariamente usados en impresión 3D los hace poco útiles para simular
tumores y otras referencias anatómicas. De forma sucesiva, se tratan parámetros como
la densidad, la viscoelasticidad, la caracterización de materiales blandos en la industria,
el estudio del módulo elástico de tejidos blandos y vasos, la dureza de los mismos, y
requerimientos como la esterilización de los modelos.
El segundo bloque empieza explorando la impresión 3D mediante FFF. Se clasifican las
variantes del proceso desde el punto de vista de la multimaterialidad, esencial para hacer
modelos de ensayo quirúrgico, diferenciando entre soluciones multiboquilla y de mezcla
en el cabezal. Se ha incluido el estudio de materiales (filamentos y líquidos) que serían
más útiles para mimetizar tejidos blandos. Se constata como en los líquidos, en
comparación con los filamentos, la complejidad del trabajo en procesos de FA es más
elevada, y se determinan formas de imprimir materiales muy blandos. Para acabar, se
exponen seis casos reales de colaboración con el HJSD, una selección de aquellos en los
que el doctorando ha intervenido en los últimos años. El origen se encuentra en la
dificultad del abordaje de operaciones de resección de tumores infantiles como el
neuroblastoma, y en la iniciativa del Dr. Lucas Krauel.
Finalmente, el Bloque 3 desarrolla numerosos conceptos (hasta 8), actividad completada a lo largo de los últimos cinco años con el apoyo de los medios del CIM UPC y de la actividad asociada a trabajos finales de estudios de estudiantes de la UPC, llegándose a materializar equipamientos experimentales para validarlos. La investigación amplia y sistemática al respecto hace que se esté más cerca de disponer de una solución de impresión 3D multimaterial de sobremesa. Se determina que la mejor vía de progreso es la de disponer de una pluralidad de cabezales independientes, a fin de capacitar la impresora 3D para integrar diversos conceptos estudiados, materializándose una posible solución.
Para cerrar la tesis, se plantea cómo sería un equipamiento de impresión 3D para
modelos de ensayo quirúrgico, a fin de servir de base para futuros desarrollos.
35
Huang, Chia-Hung, and 黃嘉宏. "Application of Multi-Agent Systems in the Multi-site Material Demand planning." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/74444536895515649317.
Full textAbstract:
碩士<br>中國文化大學<br>資訊管理研究所碩士在職專班<br>96<br>This study provided an application of material demand confirmation mechanism for a multi-sites factory. We used an agent support system combined with advanced planning and scheduling system to construct the material demand planning of a multi-sites factory.
In the plastic industry, through an agent mechanism, the use of the advanced planning and scheduling system to planning material demand of sales order for each plant and exchange the information among other plants and suppliers become a multi-sites factory of the material demand planning. According to the different scenario, this study verified the feasibility of the support and material planning system at a multi-sites factory.
This system of multi-sites material demand planning, help enterprises to raise support capacity of material for multi-site factory, to effective use of material for each plant, to reduce the enterprise overall inventory, to enhance the delivery of orders clear, to enhance the adaptability and flexibility of change in customer requirement, and create the competitive advantage for this factory.
36
Jiung, Shu-Jen, and 姜淑真. "A Study of Multi-Floor Facility Layout Based on Overhead Material Handling Systems." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/76619468702328130700.
Full textAbstract:
碩士<br>國立雲林科技大學<br>工業工程與管理研究所碩士班<br>91<br>This research focus on the specific layout problems under the situation of multiple floors and the overhand material handling system for each floor plane. The multi-floor facility layout problem is an extension of the single-floor problem. It requires the analysis of both inter flow and external floors. An independent material handling system may be required for transferring material between two different floor levels. The overhead material handling system assumes no moving tracks required on each floor plane, which makes the handling system more flexible in considering the input/output point for each department.
The proposed solution procedure can be described by the following three stages: The first stage is to assign appropriate departments for each floor level. The traditional layout problem is then applied in the second stage. The third stage is to search an input/output location for each department. Solution techniques using in those three stages involve the Threshold Accepting (TA) and the Genetic Algorithm(GA). According to the comparison result, the three-stage algorithm proposed in this research performs a better result than those in previous literatures. Finally, a numerical example is also included to illustrate how this methodology solve a typical multi-floor layout problem from scratch.
37
Chu, Baojin. "Pvdf-based copolymers, terpolymers and their multi-component material systems for capacitor applications." 2008. http://etda.libraries.psu.edu/theses/approved/WorldWideIndex/ETD-2558/index.html.
Full text
38
Lionel, Flandin. "Multiscale Relationships in Polymer-Based Heterogeneous Systems: Experiments and Simulations." Habilitation à diriger des recherches, 2006. http://tel.archives-ouvertes.fr/tel-00454578.
Full textAbstract:
I have worked on many projects, but there are several things that they all had in common. First, nearly all projects involved searching for the structural parameters that governed the macroscopic properties of the polymers and composite materials. A second common denominator is that even though my work was performed in an “academic context”, the goals were targeted toward industrial needs. Lastly, the methods and procedures were similar; they were all based on experimental results obtained for various scales of measurement (see Fig. 1). Hence, multi-scale modeling was very useful and beneficial for these projects. The models developed (mainly numerical and sometimes analytical) were initially derived from experimental evidence and then validated and improved with further experimentation. The refined models provided an efficient means of: (i) optimizing the composites according to specific needs, (ii) better understanding the hierarchical relations between the different scales, (iii) controlling the micro or meso structure and thereby the macroscopic properties. This study of the relations between structure and properties was performed on a wide variety of physical properties and materials. However, the electric and dielectric properties of composites constituted the major- ity of it and will be presented in this report. The remaining property investigations provided supplemental but valuable information. This work often requires altering various conventional experimental techniques or using well-known techniques for new purposes. I also developed, when needed, several unconventional but necessary measurement techniques. This report contains two major parts which are separated according to the nature of the fillers: Part I : Conducting fillers. In the first part, the main interest both for application and fundamental point of view, is related to the changes in properties in the vicinity of the sharp percolation transition. After a brief introduction to the percolation theory, this part will be subdivided in three chapters: Chapter 1. presents a numerical method that correlates the mesostructure to the macroscopic electrical properties both in two and three dimensions. Chapter 2. will show that an external variable (the mechanical stress) may largely alter the microstruc- ture of the percolating network within composites as revealed the macroscopic conductivity. The understanding of the mesoscale changes will be based on the chemical structure of the polymer matrix. Chapter 3. is devoted to the description of a unique case in term of percolation behavior, which made possible the control of the phase arrangement within the composite and thereby the control of the macroscopic resistivity. p. 2 Multiscale relationships in polymer–based heterogeneous systems. . . Part II : Insulating fillers. In the second part, the main interest is to obtain good electrical insulators, i.e. that can withstand large electric fields. This part thus starts with a brief introduction to the common failure mechanisms, associated with the dielectric breakdown and is also divided in three chapters: Chapter 4. is devoted to the description of a numerical simulation of the relationships between mesostructure and dielectric breakdown. Chapter 5. reveals the influence of the processing conditions of a composite utilized in the industry on the microstructure and the quantitative consequences on breakdown properties. Chapter 6. presents the aging of these composites under “real word” conditions which will further be compared to accelerated aging performed in controlled conditions, in the laboratory. A comparison of the two aging situations will furnish a quantitative understanding of the relative influence of the chemical and physical contributions to the aging process. This report will then be concluded with a description of the current and future projects.
39
Deng, Jin-Yu, and 鄧晉宇. "Research and Improvement of Multi-color Multi-Material Vat Polymerization 3D Printing System." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/7mqfp4.
Full textAbstract:
碩士<br>國立臺灣科技大學<br>機械工程系<br>106<br>The DLP systems is still in development, but most of the systems use DLP or laser as the light source. Most multi-material machines are top-illuminated and there are few down-lit multi-color multi-material 3D printing. This multi-color multi-material 3D printing system used a mobile device, with a rotating disc that can be assembled with several material slots.
This study is to improve the multi-color light-curing 3D printing system and is the same as the original system, which uses a portable device and a rotating disk. The improved machine has the function of printing multi-color and printing Multi-materials, and corrects problems that occurred on the original system. The improved positioning accuracy of the rotating disc can be increased by more than 50%. When printing large objects, it will not directly hit the resin tank; and the problem that the Mobile phone is dragged by the turntable will also be sloved, the Mobile phone platform will keep away before the turntable turns away. When the dial is positioned and then returned to the original position, the mobile phone will not be driven by the rotating disc during printing, which improves the success rate of printing.
40
Wang, Pei-Hao, and 王培濠. "A Study of Multi Soil Layering System Using Environment-Friendly Filter Material." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/4m6ep9.
Full textAbstract:
碩士<br>國立臺北科技大學<br>土木與防災研究所<br>102<br>Now, Taiwan starts running Natural Treatment System (NTS) to solve the current problems, for example, wetland and contact oxidation system, et al. However, this treatment is limited by poor hydraulic loading which gets clogging easily. Therefore, there is a new soil processing technique called Multi Soil Layering System (MSL) in Japan which provided larger load for hydraulic loading locates beneath the ground. This system efficiently improves the defect of NTS, and reduces the manual maintenance and disturbance.
MSL is mainly combined from Soil Mixing Block Layer (SML) and Permeability Layer (PL). In the case of MSL, it is use zeolite as permeable layer in Japan. The objective of this study was, however, to consider the character of localization materials and environmental protection.In this study used easily to abtain the recycling filter of material and in place of zeolite,after that it will also discuss the water cleaning experiment of MSL, and provide a reference to future engineer materials by applying filter material in the different hydraulic loadings.
From the result of experiment, the expanded clay, oyster shell and waste activated carbon systems under a 1000 L/m2/day loading rate effectively reduced the level of NH3-N and TP at percentages of more than 90%. It’s observed the processing capacity from the SS and COD, the expanded clay and the waste activated carbon system effectively reduced the level of SS at percentages of 83% and 93%, respectively. The expanded clay and the waste activated carbon system effectively reduced the level of COD at percentages of 87% and 78%, respectively. Moreover foam Lianshi and waste activated carbon systems HLR1000 ~ 3000 L/m2/day the removal performance and stability, about 90 to 95 percent of TP removal, it can increase the efficiency of phosphorus removal using a high HLR in lieu of zeolite as MSL permeable layer.
Oyster shell system in the HLR 500 ~ 800 L/m2/day SS and COD removal efficiency for better performance, but still inside the water purifying organic matter will affect the color. However, the effect of oyster shell system for the removal of nutrients, can indeed replace zeolite, and can greatly reduce the cost of assembling MSL system use in large-scale engineering.
41
Silvestre, Filipe André Antão. "Development of a multi-material 3D printing system with integrated post-production processes." Master's thesis, 2017. http://hdl.handle.net/10362/31874.
Full textAbstract:
This thesis main objective is to integrate 3D printing techniques with a post-processing method in a singular system. The idea is to use an existing 3D printer as the base structure, and then integrate an independent equipment for extrusion and spraying, as well as a laser system resulting in a multi-material 3D printing system with integrated post-production proce-dures. The first task consisted in the substitution and suitability of the entire electronics, followed by the ability to print a viscous material by extrusion and this was tested by defining a range of parameters for which it is possible to obtain the desired design of the 3D printed part. With the preliminary tests accomplished it was verified the need for some adjustments, for example, an inclusion of a heating plate on the printing surface. This equipment gives an extrusion/spray ability to the 3D printer, so that it can be used with different material and/or viscosities. The next step was finding a solution for the coupling of the “add-on” type laser to perform the post-processing as a sintering and / or crosslink source. After installation of all components came the operation test and finishing, such as introduction of laser radiation protection panels, com-pressed air inlets, extruder / spray control source, etc. The last part of this thesis was to assess the functionality of the full system and test the printing parameters: for the extrusion were: first layer height, rotation speed, print speed, den-sity, layer height, software’s nozzle diameter, leaning capacity, double wall support; for the spray: dispensing time, dispenser exit width, dispensing height; and for the laser: manual focus and power.
42
Chuang, Yueh-Lung, and 莊岳龍. "Finding the System Parameters of Multi-objective Optimization for Material Handling in an FMS." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/63081549954826285045.
Full textAbstract:
碩士<br>國立雲林科技大學<br>工業工程與管理研究所碩士班<br>95<br>The material handling system ( MHS ) is the most complex component of an advanced flexible manufacturing system ( FMS ). It utilizes various functions and resource to regulate the part movement from one work-center to another. The material handling action occupies most of the production action, therefore the practice and theory of MHS possess decisive influence in the production management and operating cost.
We apply simulation software to build up an flexible manufacturing system and adopt the response surface methodology ( RSM ). It can help us to realize the full potential design, schedule and control in AGV system. In this research, we consider two different objectives: Average throughput and Average AGV utility rate. System parameters of AGV amount, AGV speed, AGV dispatching rule, batch and machine dispatching rule were considered. We combine average throughput with average AGV utility rate to from a single desirability function to find optimal parameters of system.
43
Chang, Ai-Lin, and 張艾琳. "A Novel Integrated Framework for Multi-objective Vehicle Fleet Sizing of Automated Material Handling System." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/43168457703798143047.
Full textAbstract:
碩士<br>國立清華大學<br>工業工程與工程管理學系<br>101<br>Automated Material Handling System (AMHS) plays a key role in factory automation. Vehicle feet sizing is one of the critical issues when designing an effective AMHS. However, due to complexity of AMHS design and uncertainty involved in the production process, e.g., random processing time, vehicle feet sizing is a challenging problem, especially when there are multi-objectives, e.g., minimized cycle times and maximized throughputs are simultaneously desired. In this paper, we propose a novel framework which integrates simulation optimization techniques and Data Envelopment Analysis (DEA) to facilitate the identification of the optimal feet sizes of AMHS under multiple objectives. The trade-os between different objectives can also be demonstrated. A numerical study shows that the proposed framework can outperform the traditional approaches. In addition, an empirical study at the end verifies the effectiveness and the viability of the proposed framework in practical settings.