Torsional vibration can be characterized as the cyclic variation of shaft speed, which can cause various failures in rotating machines, such as: gear-tooth breakage, blade-off due to blade fatigue in steam turbines, break-off of shafts, and overloading of components fitted onto the shaft. Commercially, there are only a few systems available that measure this type of vibration as compared to lateral vibration measurement systems. Most of these systems required modifications to the rotating machine, which in some cases are unacceptable. Therefore, it has become common practice to develop in-house torsional vibration measurement systems. A common measurement technique, called Time Interval Measurement (TIMS), calculates the instantaneous speed of the shaft from a frequency modulated carrier wave. Since torsional vibration is the cyclic variation of shaft speed, the shaft speed can be used to determine torsional vibration. Noise can be easily introduced into this type of system masking the torsional vibration; this was apparent in the measurement system developed by Kar, which was used as a baseline for the experiments conducted in this thesis. Various techniques were employed to reduce the effects of the noise in the measurement system, such as (1) created an algorithm, different than the one used by Kar, to calculate shaft speed, (2) increased the sampling rate of the data acquisition boards, (3) resampled the shaft speed into the order domain in order to remove harmonic noise, and (4) created an algorithm that corrects the shaft speed calculation to account for unequal spacing of encoder segments. These noise reducing techniques were compiled into a LabVIEW™ program in order to develop a robust measurement system. Each technique was tested individually on two test rigs constructed at the Turbomachinery Laboratory. Each technique proved to reduce the noise introduced into the system, but the geometric compensation algorithm proved to be the most effective in reducing the noise. This thesis proved that an in-house measurement system could be developed at a relatively low cost and with relative ease.

Torsional vibration can be characterized as the cyclic variation of shaft speed, which can cause various failures in rotating machines, such as: gear-tooth breakage, blade-off due to blade fatigue in steam turbines, break-off of shafts, and overloading of components fitted onto the shaft. Commercially, there are only a few systems available that measure this type of vibration as compared to lateral vibration measurement systems. Most of these systems required modifications to the rotating machine, which in some cases are unacceptable. Therefore, it has become common practice to develop in-house torsional vibration measurement systems. A common measurement technique, called Time Interval Measurement (TIMS), calculates the instantaneous speed of the shaft from a frequency modulated carrier wave. Since torsional vibration is the cyclic variation of shaft speed, the shaft speed can be used to determine torsional vibration. Noise can be easily introduced into this type of system masking the torsional vibration; this was apparent in the measurement system developed by Kar, which was used as a baseline for the experiments conducted in this thesis. Various techniques were employed to reduce the effects of the noise in the measurement system, such as (1) created an algorithm, different than the one used by Kar, to calculate shaft speed, (2) increased the sampling rate of the data acquisition boards, (3) resampled the shaft speed into the order domain in order to remove harmonic noise, and (4) created an algorithm that corrects the shaft speed calculation to account for unequal spacing of encoder segments. These noise reducing techniques were compiled into a LabVIEW™ program in order to develop a robust measurement system. Each technique was tested individually on two test rigs constructed at the Turbomachinery Laboratory. Each technique proved to reduce the noise introduced into the system, but the geometric compensation algorithm proved to be the most effective in reducing the noise. This thesis proved that an in-house measurement system could be developed at a relatively low cost and with relative ease.

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This study utilizes recent advances in the analysis of neodymium (Nd) and samarium (Sm) by thermal ionization mass spectrometry (TIMS) to constrain timescales of heating and fluid flow within the lithosphere. Garnet grows during metamorphism and can be linked to its pressure and temperature of growth, while carbonate mineralization ages can be linked to hydrothermal fluid flow. The ability to date these common minerals makes it possible to unravel the timing and duration of tectonometamorphic processes. Garnet from the Eoarchean Nuvvuagittuq Supracrustal Belt (NSB) in Québec, Canada yields an age of 2574.66 ± 0.72 Ma. This is the most precise Neoarchean age reported for this terrane and was achieved through a modified partial dissolution procedure designed to remove the effects of much older (up to 3.8 Ga) inherited mineral growth. An accurate age for the most recent metamorphic garnet in the NSB is critical, as the (controversial) Hadean Nd model age calculations for this terrane depend on the time at which the 147Sm/144Nd systematics were last altered. Carbonate mineralization ages are explored for a diverse group of thirty samples using a novel sequential acid extraction procedure. Through this procedure it is possible to constrain carbonate mineralization in a variety of geologic settings (metamorphic fluid flow, hydrothermal and ore-forming systems) to ± 20 Myr. Zoned and bulk garnet geochronology at ten sites within a unusually localized area (~5 km2) of high temperature granulite-facies metamorphism in Bristol, New Hampshire reveals multiple brief (<1 Myr) periods of garnet growth focused between 393 and 386 Ma, at peak temperatures of 730-850°C. Comparison with garnet growth ages and temperatures , in central Massachusetts (364 Ma at 950°C) and Connecticut (341 Ma at 1000°C) reveal a regional trend of pulsed high temperature garnet growth spanning ~60 Myr from north to south, the same time span bracketed by associated igneous rocks dated via zircon geochronology. Ultrahigh metamorphic temperatures were achieved during the Acadian Orogeny in New England in localized, short pulses, likely related to igneous heating and/or associated fluid flow above and beyond the regional heating due to tectonic overthickening.

abstract: Thermal interface materials (TIMs) are extensively used in thermal management applications especially in the microelectronics industry. With the advancement in microprocessors design and speed, the thermal management is becoming more complex. With these advancements in microelectronics, there have been parallel advancements in thermal interface materials. Given the vast number of available TIM types, selection of the material for each specific application is crucial. Most of the metrologies currently available on the market are designed to qualify TIMs between two perfectly flat surfaces, mimicking an ideal scenario. However, in realistic applications parallel surfaces may not be the case. In this study, a unique characterization method is proposed to address the need for TIMs characterization between non-parallel surfaces. Two different metrologies are custom-designed and built to measure the impact of tilt angle on the performance of TIMs. The first metrology, Angular TIM Tester, is based on the ASTM D5470 standard with flexibility to perform characterization of the sample under induced tilt angle of the rods. The second metrology, Bare Die Tilting Metrology, is designed to validate the performance of TIM under induced tilt angle between the bare die and the cooling solution in an "in-situ" package testing format. Several types of off-the-shelf thermal interface materials were tested and the results are outlined in the study. Data were collected using both metrologies for all selected materials. It was found that small tilt angles, up to 0.6°, have an impact on thermal resistance of all materials especially for in-situ testing. In addition, resistance change between 0° and the selected tilt angle was found to be in close agreement between the two metrologies for paste-based materials and phase-change material. However, a clear difference in the thermal performance of the tested materials was observed between the two metrologies for the gap filler materials. / Dissertation/Thesis / M.S. Mechanical Engineering 2011

Dans le domaine de la microélectronique de puissance, les progrès de miniaturisation ne cessent de s’accroître. En effet, le nombre de composants par unité de surface a suivie durant de nombreuses années la loi de Moore. Cette évolution implique une augmentation de la densité d’énergie à évacuer sous forme de chaleur, ce qui rend le contrôle de la température de fonctionnement difficile et a pour effet de diminuer la fiabilité des systèmes électroniques.C’est pourquoi, le management thermique des matériaux d’interface thermique est indispensable pour pérenniser le bon fonctionnement des dispositifs de puissance dans leur environnement. L’utilité de ces matériaux est d’améliorer l’évacuation de la chaleur des composants électroniques vers le milieu environnant via un dissipateur thermique (radiateur, fluide caloporteur). Pour tenter de répondre à ces besoins, ce sujet de thèse est basé sur l’utilisation de nanotubes de carbone verticalement alignés, associée à des polymères fonctionnels. Les études se sont portées sur l’ensembledes résistances de contact existantes au sein d’un matériau d’interface thermique, depuis les nanotubes decarbone / Polymère / jusqu’au substrat de cuivre.L’optimisation des interactions est portée sur l’étude de différents polymères ayant la capacité d’engendrer des liaisons covalentes avec les nanotubes de carbone et avec le substrat de cuivre. L’intérêt de ces liaisons covalentes est d’améliorer le transfert de la chaleur via les phonons. Enfin, l’augmentation de la conductivité thermique intrinsèque des polymères est envisagée.Concernant les résultats obtenus, il apparait une nette diminution de chacune des résistances de contact étudiées. Afin de mieux comprendre ces résultats, des études de ces interfaces in-situ ont été réalisées. / With progress in microelectronics, the miniaturization of devices is a current issue and the component density on a device follows Moore’s law. As a consequence the power density reaches levels that challenge device reliability. New heat dissipation strategies are needed to efficiently drain heat.Thermal interface materials (TIMs) are used to transfer heat across interfaces, for example between the device and its packaging. However, to meet microelectronics requirement, commercials TIMs still need to be highly thermally conductive.In order to achieve these requirements, this work is focused on the use of vertically aligned carbon nanotubes (VACNTs) and functional polymers. All thermal contact resistances existing in TIMs, from VACNTs / Polymer / to substrate are studied.Interaction optimizations are based on the study of different polymers which are specially designed to develop covalent bonding with the CNTs sidewalls and/or metallic surface. The interest of these covalent bondings is to improve the thermal transfer by phonons. Finally, the increase of the intrinsic thermal conductivity of the polymer is considered.Regarding the results, a decrease of all thermal contact resistances is shown. In order to have a better understanding of these results, the thermal interfaces obtained are analyzed in situ.

Des anomalies nucléosynthétiques ont été observées dans des météorites pour plusieurs éléments. L’ampleur de ces anomalies ainsi que leur répartition entre les objets du système solaire renseigne sur le degré d’hétérogénéité de la nébuleuse solaire. L’étude des phases porteuses de ces anomalies procure des informations sur les processus à l’origine de cette hétérogénéité. Les datations par radiochronomètres de courte période reposent sur la répartition hétérogène des éléments père et fils. L’utilisation de ces outils nécessite donc l’étude parallèle des variations nucléosynthétiques de ces éléments. / Nucleosynthetic anomalies have been observed in meteorites for many elements. The magnitude and repartition of these anomalies provide information about the degree of heterogeneity of the solar nebula. The study of the nucleosynthetic anomalies carriers could also give insight into the processes responsible for this heterogeneity. The presence or absence of small variations in nucleosynthetic processes is a key for the use of the short-lived radiochronometers. Small variations in the repartition of the parent or daughter isotope can lead to misinterpretations of relative ages.

The intended goal within the scope of this master´s thesis is to get acquainted with the product of EMONA INSTRUMENTS Company. There are two main concepts: the software version TutorTIMS – Advanced and the hardware version TIMS-301. Both concepts were bought into the laboratory, where the following subjects are being lectured: “Access and transport networks” and “Telecommunication network services”. Three laboratory exercises were prepared for both software version and hardware version. Both versions are modular and all designed exercises support independent and creative approach of students. All exercises also consist of standard parts, which are the description of the exercise and exemplary protocol solution. The first exercise is called “amplitude modulation” and is designed as an introductory exercise. Next are a couple of exercises which are designed to be performed on one workplace at the same time. The first of them is focused on practical verification of facts from amplitude shift keying, the second one focuses on link codes. This couple of exercises is the best choice, considering the hardware version of TIMS-301 and at the present time available modules in the lab. Software version is not limited in such way, but it was required to allow performing all of prepared exercises on both versions. Lastly there is a comparison between the software and hardware version and several options for hardware TIMS optimization.

Three related sedimentary successions located in Arizona, Utah, and California were deposited in basins on proto-North America during the early rifting of Rodinia (~780 Mya). Previous detrital zircon U-Pb maximum ages for the units are inexact, making it difficult to piece together what happened at this point in Earth history. We report better maximum age constraints on these units obtained by subjecting detrital zircons to high-precision CA-ID-TIMS analysis, which provide more exact 206 Pb/238U ages. These new data significantly improve the precision for the base of the ChUMP units, with an average age of 775. 63 ± 0.27 Ma acquired for the bottom of the Chuar Group, where earlier work put the age at 782 Ma. An average age of 775.44 ± 0.73 Ma for the bottom of the Pahrump Group is also younger than the previously reported 787 ± 11 Ma. Zircons of the Uinta Mountain Group provided ages of about 766.88 ± 2.31 Ma, which is on par with an earlier age of 766.4 ± 4.8 Ma. These high precision ages for the young detrital zircons in the ChUMP units improve links between the units and provide better context for geochemical, isotopic, and biological events that occurred during the initial rifting of Rodinia.