Typically, hermetic feedthroughs for implantable devices, such as pacemakers, use a alumina ceramic insulator brazed to a platinum wire pin. This combination of material has a long history in implantable devices and has been approved by the FDA for implantable hermetic feedthroughs. The growing demand for increased input/output (I/O) hermetic feedthroughs for implantable neural stimulator applications could be addressed by developing a new, cofired platinum/alumina multilayer ceramic technology in a configuration that supports 300 plus I/Os, which is not commercially available. Seven platinum powders with different particle sizes were used to develop different conductive cofire inks to control the densification mismatch between platinum and alumina. Firing profile (ramp rate, burn- out and holding times) and firing atmosphere and concentrations (hydrogen (wet/dry), air, neutral, vacuum) were also optimized. Platinum and alumina exhibit the alloy formation reaction in a reduced atmosphere. Formation of any compound can increase the bonding of the metal/ceramic interface, resulting in enhanced hermeticity. The feedthrough fabricated in a reduced atmosphere demonstrated significantly superior performance than that of other atmospheres. A composite structure of tungsten/platinum ratios graded thru the via structure (pure W, 50/50 W/Pt, 80/20 Pt/W and pure Pt) exhibited the best performance in comparison to the performance of other materials used for ink metallization. Studies on the high temperature reaction of platinum and alumina, previously unreported, showed that, at low temperatures in reduced atmosphere, Pt3Al or Pt8Al21 with a tetragonal structure would be formed. Cubic Pt3Al is formed upon heating the sample to temperatures above 1350 °C. This cubic structure is the equilibrium state of Pt-Al alloy at high temperatures. The alumina dissolves into the platinum ink and is redeposited as a surface coating. This was observed on both cofired samples and pure platinum thin films coated on a 99.6 Wt% alumina and fired at 1550 °C. Different mechanisms are proposed to describe this behavior based on the size of the platinum particle.

Detta examensarbete är utfört hos Swisslog under våren 2013. De hade problem med den manuella styrningen av deras pallstaplingskran för höglager, som upplevdes ryckig och svår att kontrollera vid låga hastigheter. Huvudsyftet var att undersöka varför detta fenomen uppstod och hur det kunde lösas med både hård- och mjukvarumässiga metoder. Utöver detta undersöktes hur produktionskostnaden, för delarna av kranen som rör den manuella styrningen, kunde reduceras. Det upplevda fenomenet är känt som biodynamic feedthrough. Det innebär att konstruktionens acceleration matas genom operatörens kropp och skapar en återkoppling till styrdonet, i detta fall en joystick. Operatörens hand ger en oavsiktlig störsignal som gör systemet instabilt som i sin tur skapar en oscillation som ökar i amplitud och är svår eller omöjlig att stoppa. Den föreslagna lösningen är att digitalt lågpassfiltrera styrsignalen från joysticken. Det dämpar de skarpaste spikarna i signalen och förhindrar systemet att ta in de snabba handrörelser som kranens acceleration har skapat. / This bachelor thesis was written at Swisslog, who had a problem with the manual control of their high-bay pallet stacker crane. The ride was perceived rough and hard to control at lower speeds.    The main purpose was to examine the source of the phenomenon and how to solve the problem with both software and hardware. It was also requested to investigate ways to lower production costs of the parts of the crane related to the manual control.   The experienced phenomenon is known as biodynamic feedthrough. It refers to the acceleration of the structure affects the body of the operator causing a feedback loop to the input, in this case a joystick. The hand of the operator causes an involuntary control input and making the system unstable and causing an oscillation increasing in amplitude over time. This may be hard or impossible to stop.   The proposed solution is a low-pass filter applied at the output of the joystick. This attenuates the sharpest spikes from the joystick control signal and prevents the system from receiving the fast hand movements caused by the acceleration of the crane.

Biodynamic feedthrough occurs in many types of operator controlled machines where the operator is a passenger and the motion of the controlled machine excites motion of the human operator, creating unwanted feedback. It is a significant cause for control performance degradation in backhoes. In this research, the problem of biodynamic feedthrough is investigated in a backhoe control system. For simplification, the system is limited to a single degree of freedom. Several controller based approaches are investigated to reduce cab vibration, while maintaining cylinder tracking performance. These controllers are tested in hardware, with and without the human operator and associated biodynamic feedthrough. The effect of this cab vibration reduction on biodynamic feedthrough is tested in a small set of human subject tests. The results indicate that some vibration reduction and improvement in the operator's control performance can be achieved by adding cab vibration compensation.

This thesis presents a design methodology for continuous wave (CW) synthetic aperture radar (SAR) systems. The focus is on design considerations specific to small, low-power systems suitable for operation on small aircraft and unmanned aerial vehicles (UAVs). Well-known results which have been derived in other works, such as the radar equation, are explained in the context of low-power, CW systems. Additionally, design issues unique to CW SAR are addressed and the results generalized. A method for controlling feedthrough between antennas is developed, and the resulting limitations on swath width are discussed. Methods are developed which allow an engineer to design a CW SAR system to obtain a given swath width, resolution, and data rate, and necessary tradeoffs are discussed. Using the proposed methodology, designs for two specific SAR systems are developed. Example sections outline the design of two small SAR systems called microASAR and microBSAR. These sections present a real-world application of the methodology and offer explanations of the rationale behind many of the design choices. Straightforward methods for testing different aspects of a completed SAR system are developed and presented. These procedures are carried out using microASAR hardware, and the results are used to validate the design methodology.

名古屋大学年代測定総合研究センターシンポジウム報告

Cette thèse porte sur l'estimation simultanée du coefficient de diffusion et du terme source régissant le modèle de transport de la température dans les plasmas chauds. Ce phénomène physique est décrit par une équation différentielle partielle (EDP) linéaire, parabolique du second-ordre et non-homogène, où le coefficient de diffusion est distribué et le coefficient de réaction est constant. Ce travail peut se présenter en deux parties. Dans la première, le problème d'estimation est traité en dimension finie ("Early lumping approach"). Dans la deuxième partie, le problème d'estimation est traité dans le cadre initial de la dimension infinie ("Late lumping approach"). Pour l'estimation en dimension finie, une fois le modèle établi, la formulation de Galerkin et la méthode d'approximation par projection sont choisies pour convertir l'EDP de transport en un système d'état linéaire, temps-variant et à entrées inconnues. Sur le modèle réduit, deux techniques dédiées à l'estimation des entrées inconnues sont choisies pour résoudre le problème. En dimension infinie, l'estimation en-ligne adaptative est adoptée pour apporter des éléments de réponse aux contraintes et limitations dues à la réduction du modèle. Des résultats de simulations sur des données réelles et simulées sont présentées dans ce mémoire. / This work deals with the diffusion and source term estimation in a heat transport model for tokamaks plasma . This phenomenon is described by a second-order linear parabolic partial differential equation (PDE) with distributed diffusion parameter and input. Both "Early lumping" and "Late lumping" approaches are considered in this thesis. First, once the heat model is chosen, the Galerkin formulation and the parameter projection method are combined to convert the PDE to a set of ordinary differential equations (ODEs). Then, two estimation methods able to give optimal estimates of the inputs are applied on the reduced model to identify simultaneously the source term and the diffusion coefficient. In the infinite dimensional method, the adaptive estimation technique is chosen in order to reconstruct "freely" the unknown parameters without the constraints due to the model reduction method. Simulation results on both simulated and real data are provided to attest the performance of the proposed methodologies.