No description available.

No description available.

Multilayers provide an ideal tool to study thermodynamics of heterogeneous systems far from equilibrium. In this study, synthesis, characterization, thermal stability and phase equilibrium of multilayers are investigated based on Au-Pt system. Au-50%Pt multilayers were first formed by repeated rolling and folding. The microstructure was investigated by x-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). These methods revealed that the process reduced layer thicknesses to below 30nm. However, delaminating and non-uniform spacings were also observed in some regions. To get well- welded and regular multilayers, the experiment was redesigned. The improved approach, involving repeated cutting, stacking, annealing and cold rolling, has yielded uniform multilayers with interlamellar spacings as low as 6nm. XRD demonstrated the formation of a homogeneous solid solution during cold rolling at room temperature. TEM suggested that the multilayers were discontinuously homogenized via steady state motion of boundaries. The reason for the solid solution formation is that the stored interface energy is higher than the energy barrier for solid solution formation. The solid solution is unstable. It decomposes into Au and Pt after heating to 500°C at 50°C/min by differential scanning calorimetry (DSC). The phase diagram is strongly modified in the nanometer range when we take into account of interface energy. The grain size dependent phase diagram model of Au-Pt system shows that the melting points of Au and Pt can be lowered more than 300K if the average grain size is reduced to 10nm. The melting temperature of Au/Pt multilayers has been studied with theoretical and experimental approaches. High speed laser heating was used to minimize any modification of the multilayer structure prior to melting. The qualitative experimental results are shown to be in agreement with expectations. / Thesis / Master of Applied Science (MASc)

Yes / In order to improve the frequency-dependent dielectric properties of the immiscible polymeric blends which were melt-compounded by composing poly (vinylidene fluoride) (PVDF) and low density polyethylene (LDPE), the layer multiplication and the solid phase orientation technologies were respectively adopted as two effective strategies to optimize the dispersion state and the orientation of internal microstructure, aiming at reducing physical porosity and improving the barrier performance as well as crystal phase of the polymer extrudates. Results comparison showed the dielectric properties were greatly dependent on the crystal type and the physical porosity density which were also emphasized as the interfacial effect in the previous work [ref. 29: Lin X et al, J Appl Polym Sci 2015; 132(36), 42507]. It was found that the multilayer-structure manipulation could substantially improve the dispersion state between the two immiscible components, enhance the mechanical performance and reduce the internal defects and increase the dielectric constant while keeping the dielectric loss stable. By uniaxial stretching the sample sheets at a rubber state temperature of ca. 10-20˚C below the melting point, crystal transformation was induced by increasing molecular chains orientation degree which was also contributed to the enhancement of the dielectric properties. These techniques implied the potential as a promising way for inducing functional structures of polymeric blends.

A transducer consisting of multiple layers of ionic polymer material is developed for applications in sensing, actuation, and control. The transducer consists of two to four individual layers each approximately 200 microns thick. The transducers are connected in parallel to minimize the electric field requirements for actuation. The tradeoff in deflection and force can be controlled by controlling the mechanical constraint at the interface. Packaging the transducer in an outer coating produces a hard constraint between layers and reduces the deflection with a force that increases linearly with the number of layers. This configuration also increases the bandwidth of the transducer. Removing the outer packaging produces an actuator that maintains the deflection of a single layer but has an increased force output. This is obtained by allowing the layers to slide relative to one another during bending. A Finite Element Analysis (FEA) method capable of modeling the structure of the multilayer transducers is developped. It is used to model the interfacial friction in multilayer transducers. Experiments on transducers with one to three layers are performed and the results are compared to Newbury's equivalent circuit model, which was modified to accommodate the multilayer polymers. The modification was performed on four different boundary conditions, two electrical the series and the parallel connection, and two mechanical the zero interfacial friction and the zero slip on the interface. Results demonstrate that the largest obstacle to obtaining good performance is water transport between the individual layers. Water crossover produces a near short circuit electrical condition and produces feedthrough between actuation layers and sensing layers. Electrical feedthrough due to water crossover eliminates the ability to produce a transducer that has combined sensing and actuation properties. Eliminating water crossover through good insulation enables the development of a small (5 mm x 30 mm) transducer that has sensing and actuation bandwidth on the order of 100 Hz. Due to the mechanical similarities of ionic transducers to biological muscles and their large flapping displacement capabilities we are studying the possibility of their use in flapping Micro Air Vehicle (MAV) application, as engines, controllers and sensors. The FEA modeling technique capable is used to design two ionic polymers actuated flapping wings. / Master of Science

No / Simply melt blended polypropylene/carbon nanotubes composites (PP/CNTs) usually present mechanical deterioration. In this work, multilayered sheet of PP/CNTs with improved tensile property was obtained by solid-phase orientation and hot compression. The initially blended PP/CNTs were highly orientated by employing a constrained slit die and hot compressed under a certain temperature and pressure by stacking eight layers together. The effects of compression temperature and pressure on the tensile property and AC conductivity of the multilayered sheets were examined to explore the evolution of hierarchical crystallization morphology and CNT networks. The multilayered sheet which was hot compressed at 184°C and 5 MPa demonstrated an optimum tensile strength of ∼132.5 MPa and an elongation at break ∼52.7%, respectively, raised by almost 3-fold compared with those initially blended PP/CNTs. By increasing compression temperature and decreasing pressure, the AC conductivity showed an increase of 2 to 4 orders of magnitude. / China Scholarship Council. Grant Number: 201806465028.

O presente trabalho teve como objetivo apresentar uma metodologia que permita encontrar o posicionamento e rastrear as diferentes localizações de um suíno em uma baia, utilizando o valor do Receiver Signal Strenght Indicator (RSSI), entre o dispositivo móvel (suíno) e três dispositivos fixos, e uma Rede Neural Artificial do tipo Perceptron Multicamadas (PMC), responsável por interpretar os sinais RSSI e transformá-los em valores conhecidos, como em um plano cartesiano, com coordenadas no eixo X e eixo Y. A região de teste foi dividida em 289 pontos, sendo 286 utilizados para coleta de dados e para o treinamento da rede PMC. Para cada ponto, foram armazenados a sua posição dentro da baia e o valor RSSI entre o dispositivo móvel e os três dispositivos fixos. O processo foi repetido para 8 pontos escolhidos aleatoriamente dentro do espaço de teste e inseridos como entradas na rede PMC. Após treinamentos e operações realizadas com diversas arquiteturas foi possível concluir que àquela dotada de 10 neurônios na camada intermediária consistiu na melhor alternativa, cujos resultados de monitoramento e rastreamento das posições do dispositivo móvel foram encontradas com valores aceitáveis de exatidão. / This paper aims to present a methodology to find the positioning and tracking of the different locations of a pig in a stall, using the value of the Receiver Signal Strength Indicator (RSSI), between the mobile device (pig) and three devices fixed, and an Artificial Neural Network Multilayer Perceptron (MLP), responsible for interpreting the RSSI signals and turning them into known values, such as on a Cartesian plane, with coordinates on X axis and Y axis. The test region was divided into 289 points, with 286 points used for data collection and training of PMC network, and for each point, it was stored its position inside the stall and its RSSI value between the mobile devices and the three fixed. The process was repeated for 8 points chosen randomly within the space of test and entered as inputs into the PMC network. After training and operations with various architectures it was concluded that the architecture with 10 neurons in the hidden layer was the best alternative, whose the results of monitoring and tracking the positions of mobile device were found with acceptable accuracy.

O presente trabalho teve como objetivo apresentar uma metodologia que permita encontrar o posicionamento e rastrear as diferentes localizações de um suíno em uma baia, utilizando o valor do Receiver Signal Strenght Indicator (RSSI), entre o dispositivo móvel (suíno) e três dispositivos fixos, e uma Rede Neural Artificial do tipo Perceptron Multicamadas (PMC), responsável por interpretar os sinais RSSI e transformá-los em valores conhecidos, como em um plano cartesiano, com coordenadas no eixo X e eixo Y. A região de teste foi dividida em 289 pontos, sendo 286 utilizados para coleta de dados e para o treinamento da rede PMC. Para cada ponto, foram armazenados a sua posição dentro da baia e o valor RSSI entre o dispositivo móvel e os três dispositivos fixos. O processo foi repetido para 8 pontos escolhidos aleatoriamente dentro do espaço de teste e inseridos como entradas na rede PMC. Após treinamentos e operações realizadas com diversas arquiteturas foi possível concluir que àquela dotada de 10 neurônios na camada intermediária consistiu na melhor alternativa, cujos resultados de monitoramento e rastreamento das posições do dispositivo móvel foram encontradas com valores aceitáveis de exatidão. / This paper aims to present a methodology to find the positioning and tracking of the different locations of a pig in a stall, using the value of the Receiver Signal Strength Indicator (RSSI), between the mobile device (pig) and three devices fixed, and an Artificial Neural Network Multilayer Perceptron (MLP), responsible for interpreting the RSSI signals and turning them into known values, such as on a Cartesian plane, with coordinates on X axis and Y axis. The test region was divided into 289 points, with 286 points used for data collection and training of PMC network, and for each point, it was stored its position inside the stall and its RSSI value between the mobile devices and the three fixed. The process was repeated for 8 points chosen randomly within the space of test and entered as inputs into the PMC network. After training and operations with various architectures it was concluded that the architecture with 10 neurons in the hidden layer was the best alternative, whose the results of monitoring and tracking the positions of mobile device were found with acceptable accuracy.

No description available.

Trend towards downsizing the product size and at the same time to bring more functionality in electronic products, demands electrically interconnecting several miniaturized electronic components with high counts of I\Os (Input/Out put) on smaller and smaller size printed wiring boards [PWB]. These miniature components occupy lower foot print area but require higher routing interconnection densities. However, the conventional multilayer board technologies exhibit limitations when there is need to connect very high I\O components such as ball grid arrays, which require blind and buried interconnections within the multilayer mono-block. This limitation has given raise to newer methods of multi layer construction. Build–up multilayer PWB is now the technology of choice for enhanced routing capability including blind and buried interlayer connections. Build up methods are based on making very small vias within dielectric layers followed by metalisation. Typically blind and buried vias are very small, and hence called “micro vias” connecting the layers selectively within the multilayer mono-block. Buried vias make the interconnection between the consecutive layers, and blind vias connect the surface layers to any one of the interior layers in the build up multilayer board. If the blind vias are filled with a dielectric, the entire top and bottom surface area becomes available for high -density component mounting. The crux in build up board technologies is the method of creating micro-holes; a micro hole is a hole, which is less than 150 micro meter in diameter. Efforts are made to replace existing metalising techniques with “paste filling” methodologies, which would result in “SOLID CONDUCTING VIAS” CALLED AS “MICRO -INTERCONNECTS” The work reported in this thesis aims at demonstrating one such innovative ‘solid conducting via’ formation without using any of the known micro-hole formation techniques. Based on the results obtained some useful conclusions have been drawn which will perhaps go a long way in the name of “PRINTED PILLAR TECHNOLOGY” a novel methodology for building multilayer suitable for very high I\O components such as “ball grid arrays.”