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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.
51

Automated experience-based learning for plug and produce assembly systems

Scrimieri, Daniele, Antzoulatos, N., Castro, E., Ratchev, S.M. 04 March 2020 (has links)
Yes / This paper presents a self-learning technique for adapting modular automated assembly systems. The technique consists of automatically analysing sensor data and acquiring experience on the changes made on an assembly system to cope with new production requirements or to recover from disruptions. Experience is generalised into operational knowledge that is used to aid engineers in future adaptations by guiding them throughout the process. At each step, applicable changes are presented and ranked based on: (1) similarity between the current context and those in the experience base; (2) estimate of the impact on system performance. The experience model and the self-learning technique reflect the modular structure of the assembly machine and are particularly suitable for plug and produce systems, which are designed to offer high levels of self-organisation and adaptability. Adaptations can be performed and evaluated at different levels: from the smallest pluggable unit to the whole assembly system. Knowledge on individual modules can be reused when modules are plugged into other systems. An experimental evaluation has been conducted on an industrial case study and the results show that, with experience-based learning, adaptations of plug and produce systems can be performed in a shorter time. / European Union [grant number 314762].
52

On Hydroelastic Plug Valve Vibration

D'Netto, William Mark 10 1900 (has links)
<p> The research reported in this thesis concentrated on experimentally investigating and theoretically modelling self-excited valve vibrations. In particular the jet-flow inertia mechanism has been studied. Experimentally, this has been achieved by allowing water to discharge from a constant head tank into a pipeline through a simple plug valve. The plug valve was restrained so that axial vibrations of the plug valve could occur. Using this equipment the conditions for which the valve was stable and unstable was obtained. Further experimental investigation using a Laser Doppler Anemometer allowed for recording of instantaneous fluid discharge during the valve limit cycles. In addition the records of the instantaneous pressure difference and valve opening allowed for instantaneous discharge coefficient calculations. Although no trends in these instantaneous discharge coefficients were apparent, these particular experiments allowed for improved modelling of the valve vibration. </p> <p> Dimensionless nonlinear differential equations were derived to describe general flow control devices. A stability analysis of these differential equations showed that at large fluid inertias that the instability that arises is one of divergence, hence a quasistatic stability analysis is valid. Numerical integration of the differential equations of motion was used to predict limit cycles as well as valve stability. </p> <p> The divergence formula derived for large fluid inertia was found to coincide with the corresponding experimental results. Other predictions were found to generally agree with experimental results. Discrepancies which did arise were attributed to waterhammer. Hence the theory derived was concluded to be fundamentally correct. Recommendations for further research include inclusion of waterhammer in the model and investigation of local flow effects. </p> / Thesis / Master of Engineering (ME)
53

Designing and Implementing a Human-Machine Interface in Safe Plug and Produce Systems

Vijayan, Nivin January 2023 (has links)
This thesis introduces a Human-Machine Interface (HMI) developed to enhance safety and efficiency in Configurable Multiagent Systems (CMAS) operating in Plug-and-Produce robot cells. The HMI addresses challenges related to flexible CMAS configurations, specifically addressing collision detection difficulties. Through runtime Configuration and coding of CMAS, the HMI identifies safer robot paths to prevent collisions during real-world CMAS operations. The experimental phase involves a virtual environment, demonstrating the HMI's effectiveness in collision prevention during CMAS operations. This research represents a notable advancement in collision-free motion planning for flexible CMAS configurations, offering a valuable tool for operators to operate CMAS in dynamic production settings, fostering safer and more efficient robotic automation across industries
54

Thermal Decomposition and Growth of Short Alkylated Naphthalenes

YANG, JUN 04 April 2007 (has links)
No description available.
55

930 sqft of Architecture

Clark, David B. 15 October 2010 (has links)
There is no primacy to Architecture. For centuries architects have posited formulaic approaches to creating spatial environments. Bold maxims for design have defined entire periods and styles of architecture, and each subsequent postulation attempts to disprove the former by challenging its theories against imperfect realizations. Yet nearly all have the same fault; they prioritize characteristics of architecture, attempting to design according to absolutisms of thought and process. I believe this to be a dangerous mode of operation, as absolutisms can be extremely complex and difficult to grasp conceptually, let alone to manifest into realities. Reducing architecture to processes of selection, generalization, singularities, and priorities is just clever ways of dealing with complexity in an attempt to make the intangible tangible. This "reduction" and "simplification" can only hold value as a tool for the study and analysis of architecture, not its practice and execution. Although architecture is universally conditional, it has been assigned universal qualities over time in theory and practice. I believe time requires that those qualities be subject to change and reinterpretation so that architecture may maintain proper relevance, barring one constant: all qualities must exist by virtue of the others and cannot be seen independently; one quality is no more than an aspect of the others. To better explore this notion, three criteria (qualities, generators) have been identified as a measure for critical analysis of three architectural research projects. They are built from a history of pre-defined criterion, named and redefined in an attempt to elevate a personal study and practice of architecture at a period in time. These projects have a high degree of personal influence and involvement, and so this becomes in a way a self-analysis in the study and practice of architecture. The intention of this compendium is to gain insight towards a personal definition of architecture through an analysis of architectural theory and precedence in comparison to work that is reflective of personal architectonics. In time, I hope it will have continued to develop. / Master of Architecture
56

Simulation of the plug-assisted thermoforming of polypropylene using a large strain thermally coupled constitutive model

O'Connor, C.P.J., Martin, P.J., Sweeney, John, Menary, G., Caton-Rose, Philip D., Spencer, Paul 13 February 2013 (has links)
No / Thermoforming is widely employed in industry for the manufacture of lightweight, thin-walled products from pre-extruded plastic sheet and its largest application is in packaging. Over many years attempts have been made to simulate the process and thereby exploit modern computational tools for process optimisation. However, progress in this area has been greatly hampered by insufficient knowledge of the response of polymer materials under thermoforming conditions and an inability to measure this and other processing phenomena accurately. In recent years some address has been made to these problems through advances in measurement technologies, and in particular, the development of high speed, high strain, biaxial testing machines that are designed to replicate the conditions in thermoforming processes. In this work the development of an advanced finite element-based thermoforming process simulation is presented. At its heart is a sophisticated large strain thermally coupled (LSTC) material model for polypropylene, which has been developed after several years of research and is founded directly on biaxial test results at elevated temperatures. This material model has been demonstrated to provide an excellent fit to the biaxial data and to offer a very stable computational platform for the process simulation.The performance of the working simulation was validated through comparison with matching experimental test results, and this enabled investigation of the sensitivity of the process output (in the form of part wall thickness distribution) to changes in a range of other processing parameters. This work confirmed that the process is most sensitive to the parameters controlling plug/sheet contact friction. Heat transfer parameters were also shown to be significant and the requirement for the model to be fully thermo-mechanically coupled has been clearly established.
57

Úrovňové množiny mnohorozměrné hustoty a jejich odhady / Level Sets of Multivariate Density Functions and their Estimates

Kubetta, Adam January 2011 (has links)
A level set of a function is defined as the region, where the function gets over the specified level. A level set of the probability density function can be considered an alternative to the traditional confidence region because on certain conditions the level set covers the region with minimal volume over all regions with a given confidence level. The benefits of using level sets arise in situations where, for example, the given random variables are multimodal or the given random vectors have strongly correlated components. This thesis describes estimates of the level set by means of a so called plug-in method, which first estimates density from the data set and then specifies the level set from the estimated density. In addition, explicit direct methods are also studied, such as algorithms based on support vectors or dyadic decision trees. Special attention is paid to the nonparametric probability density estimates, which form an essential tool for plug-in estimates. Namely, the second chapter describes histograms, averaged shifted histograms, kernel density estimates and its generalization. A new technique transforming kernel supports is proposed to avoid the so called boundary effect in multidimensional data domains. Ultimately, all methods are implemented in Mathematica and compared on financial data sets.
58

Sistema eletrônico para aquisição, processamento e armazenamento de sinais biológicos baseado na norma IEEE 1451.4. / Electronic system for data aquisition, processing and biological signal storage according to standard IEEE 1451.4.

Santos, José Carlos dos 10 April 2006 (has links)
O objetivo deste trabalho foi o desenvolvimento de um sistema de aquisição, processamento e armazenamento de sinais adquiridos de um arranjo de sensores embasado na norma IEE 1451.4 , resultando num sistema de sensores plug&play. O sistema de aquisição de sinais proposto permitirá monitorar diversos tipos de sensores para as mais variadas aplicações nos campos da área biomédica, automação industrial, monitoramento ambiental dentre outras. O sistema de aquisição proposto é constituído por um módulo chamado de STIM (\"Smart Transducer Interface Module\") cujo elemento principal é um microcontrolador com arquitetura RISC de propósito geral, [Johnson 2001]. O módulo STIM é conectado a um computador via interface serial (RS232) para transmitir dados dos sensores e receber comandos de controle. Os sensores analógicos aqui utilizados foram adequados ao sistema utilizando-se da técnica chamada MMI (Mixed Mode Interface) em conformidade com a norma IEEE 1451.4, transformando os sensores em um sistema plug&play. O módulo STIM é monitorado por um software residente no computador PC permitindo que os dados adquiridos dos sensores sejam visualizados e gravados em arquivo para posterior estudo. A obtenção de um sistema de sensores plug&play foi desenvolvida utilizando a estrutura TEDS (Transducer Electronic Data Sheet) gravada em uma memória serial não volátil. O TEDS possui informações e especificações técnicas do transdutor de acordo com um modelo (template) conforme a norma IEEE 1451.4, tal que, quando um sensor é conectado, o sistema exibe na tela do computador informações tais como, o canal conectado, o tipo de sensor, o modelo, número de série, nome do fabricante e a data de fabricação. Neste trabalho foram implementados três módulos MMI utilizando três sensores analógicos, temperatura, pressão e pH. Estes três módulos MMI possibilitaram realizar medidas comparativas que fundamentam o funcionamento do sistema. / The purpose of this work was the development of an acquisition, processing and storage system of a signal from an arrangement of sensors based on IEEE 1451.4 standard, resulting in a plug&play sensors system. The acquisition signal system proposed will permit to monitoring several kinds of sensors for a variety application in the fields of biomedical, industrial automation and environment and many others. The system proposed is formed by a module, called STIM (Smart Transducer Interface Module) that the main element is a general purpose microcontroller with RISC architecture, [Johnson 2001]. The STIM module is connected with a PC computer by serial interface (RS232) to transmit the data from sensors and to receive the control commands. The analog sensors here utilized was adapted to the system utilizing a technique called MMI (Mixed Mode Interface) attending the IEEE 1451.4 standard, transforming the sensors in a plug&play system. The STIM module is assisted by a PC via resident software that will permit the acquired data viewing and recording in file for further study. The plug&play sensors system was developed utilize the TEDS structure (Transducer Electronic Data Sheet) recorded in a non volatile serial memory. The TEDS has specifications and technical information from the transducer according a model (template) in conformity of IEEE 1451.4 standard , as well, when a sensor is connected , the system shows information on the PC screen, as the connected channel , the kind of the sensor , the model , serial number, producer name and produced date. In this work three MMI modules were implemented utilizing three analog sensors; temperature, pressure and pH. These three MMI modules let\'s realize comparative measurements that grounds the system operation.
59

Sistema eletrônico para aquisição, processamento e armazenamento de sinais biológicos baseado na norma IEEE 1451.4. / Electronic system for data aquisition, processing and biological signal storage according to standard IEEE 1451.4.

José Carlos dos Santos 10 April 2006 (has links)
O objetivo deste trabalho foi o desenvolvimento de um sistema de aquisição, processamento e armazenamento de sinais adquiridos de um arranjo de sensores embasado na norma IEE 1451.4 , resultando num sistema de sensores plug&play. O sistema de aquisição de sinais proposto permitirá monitorar diversos tipos de sensores para as mais variadas aplicações nos campos da área biomédica, automação industrial, monitoramento ambiental dentre outras. O sistema de aquisição proposto é constituído por um módulo chamado de STIM (\"Smart Transducer Interface Module\") cujo elemento principal é um microcontrolador com arquitetura RISC de propósito geral, [Johnson 2001]. O módulo STIM é conectado a um computador via interface serial (RS232) para transmitir dados dos sensores e receber comandos de controle. Os sensores analógicos aqui utilizados foram adequados ao sistema utilizando-se da técnica chamada MMI (Mixed Mode Interface) em conformidade com a norma IEEE 1451.4, transformando os sensores em um sistema plug&play. O módulo STIM é monitorado por um software residente no computador PC permitindo que os dados adquiridos dos sensores sejam visualizados e gravados em arquivo para posterior estudo. A obtenção de um sistema de sensores plug&play foi desenvolvida utilizando a estrutura TEDS (Transducer Electronic Data Sheet) gravada em uma memória serial não volátil. O TEDS possui informações e especificações técnicas do transdutor de acordo com um modelo (template) conforme a norma IEEE 1451.4, tal que, quando um sensor é conectado, o sistema exibe na tela do computador informações tais como, o canal conectado, o tipo de sensor, o modelo, número de série, nome do fabricante e a data de fabricação. Neste trabalho foram implementados três módulos MMI utilizando três sensores analógicos, temperatura, pressão e pH. Estes três módulos MMI possibilitaram realizar medidas comparativas que fundamentam o funcionamento do sistema. / The purpose of this work was the development of an acquisition, processing and storage system of a signal from an arrangement of sensors based on IEEE 1451.4 standard, resulting in a plug&play sensors system. The acquisition signal system proposed will permit to monitoring several kinds of sensors for a variety application in the fields of biomedical, industrial automation and environment and many others. The system proposed is formed by a module, called STIM (Smart Transducer Interface Module) that the main element is a general purpose microcontroller with RISC architecture, [Johnson 2001]. The STIM module is connected with a PC computer by serial interface (RS232) to transmit the data from sensors and to receive the control commands. The analog sensors here utilized was adapted to the system utilizing a technique called MMI (Mixed Mode Interface) attending the IEEE 1451.4 standard, transforming the sensors in a plug&play system. The STIM module is assisted by a PC via resident software that will permit the acquired data viewing and recording in file for further study. The plug&play sensors system was developed utilize the TEDS structure (Transducer Electronic Data Sheet) recorded in a non volatile serial memory. The TEDS has specifications and technical information from the transducer according a model (template) in conformity of IEEE 1451.4 standard , as well, when a sensor is connected , the system shows information on the PC screen, as the connected channel , the kind of the sensor , the model , serial number, producer name and produced date. In this work three MMI modules were implemented utilizing three analog sensors; temperature, pressure and pH. These three MMI modules let\'s realize comparative measurements that grounds the system operation.
60

A Bioengineered Neonate Lung Model to Study Exogenous Pulmonary Surfactant Delivery in Airways

Combs, Hannah 25 October 2022 (has links)
No description available.

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