Vegetation phenology serves as a primary ecological indicator of climate change and has numerous ecosystem and climate impacts including nutrient cycling, energy budgets, and annual primary productivity. Phenology models, especially ones of autumnal processes like senescence, are typically based on correlations between environmental threshold triggers and transition dates and less is known about the specific mechanisms behind phenological events. Higher temporal resolution satellite data is needed to continue to identify the mechanisms at larger scales. It is unclear if a start of senescence (SOS) trigger is needed in mechanistic models and if decreased photosynthesis drives senescence. In this dissertation, I have two main themes: the first (Chapters 2 and 3) is to investigate the potential of the Geostationary Operational Environmental Satellite (GOES) to track changes to the phenology-sensitive Normalized Difference Vegetation Index (NDVI) and the second (Chapters 4 and 5) is to develop dynamic mechanistic models to predict senescence in cold-deciduous broadleaf forests. In Chapter 2, I created a novel statistical model to estimate daily NDVI with uncertainty from high temporal resolution (five - ten minutes) GOES-16 and -17 data. In Chapter 3, I used this data to track forest phenology by fitting double-logistic Bayesian models and comparing transition dates to those obtained from PhenoCams (digital cameras) and the Moderate Resolution Imaging Spectroradiometer (MODIS). Compared to MODIS, GOES was more correlated with PhenoCam at the start and middle of spring. In Chapter 4, I developed a dynamic Bayesian model based on the physiological process of chlorophyll cycling that assumes a constant chlorophyll breakdown rate and synthesis dependent on temperature and photoperiod to predict senescence without including a SOS trigger or degree-day memory. I fit the model to greenness time series from 24 PhenoCam sites and found that for 49% of the site-years the model could predict SOS using only pre-SOS data. Furthermore, the model could regularly predict greenness at other sites better than their climatologies. In Chapter 5, I investigated if including photosynthetic feedbacks could improve the chlorophyll synthesis model at the canopy and leaf-levels. Testing this against leaf-level measurements of photosynthetic capacity and changes in chlorophyll concentrations of Fagus grandifolia and Quercus rubra demonstrated that the model fit improved at the canopy level, but not at the leaf-level. This dissertation illustrates that GOES can track phenology and that senescence in cold-deciduous broadleaf forests might not be initiated with a threshold-based trigger.

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No / A series of eleven alpha-aminoacyl stabilised phosphorus ylides 9-19 have been prepared by condensation of N-alkoxycarbonyl protected amino acids with Ph3P=CHCO2Et using a carbodiimide peptide coupling reagent. Upon ash vacuum pyrolysis at 600 degreesC, these undergo extrusion of Ph3PO to give the corresponding, alpha,beta-acetylenic gamma-amino esters 21-29, 33 and 34 in moderate yield. In two cases the terminal alkynes 30 and 31 are also formed. The beta-aminoacyl ylide 20 from beta-alanine similarly gives the alpha,beta-acetylenic delta-amino ester 35 upon pyrolysis. Regioselective addition of HBr to the triple bond of one acetylenic ester 25 was observed giving a mixture of E and Z alpha-bromoacrylates 36. Hydrogenation of the N-Cbz acetylenic esters 21-23 and 33 results in N-deprotection and hydrogenation of the triple bond to afford the chiral GABA analogues 37-40 in 70 --> 95% ee as determined by F-19 NMR of their Mosher amides. Fully assigned C-13 NMR spectra of all the ylides and acetylenic ester derivatives are presented.

Information security is a complex issue, which is very critical for success of modern businesses. It can be implemented with the help of well-tested global standards and best practices. However, it has been studied that the human aspects of information security compliance pose significant challenge to its practitioners. There has been significant interest in the recent past on how human compliance to information security policy can be achieved in an organization. Various models have been proposed by these researchers. However, there are very few models that have tried to link human commitment attributes with information security governance of an organization. The research problem of this study was to identify the security controls and mechanisms to govern information security effectively. The proposed model was based on agency theory and comprises a relationship between human commitment variables (ethics, integrity and trust) with security governance variables (structural, relational and process) referred as systemic variables in the research. The resulting correlation is further related with governance objectives (goal congruence and reducing information asymmetry) to hypothesize an effective information security in an organization. The research model proposed was tested employing confirmatory factor analysis (CFA) and structural equation modeling (SEM). There were four models tested in this research. The first model (initial measurement model) comprised human variables linked with relational and the systemic variables linked with goal congruence and information asymmetry. This model could not get through the CFA tests. A modified model comprising human and systemic attributes related with goal congruence and information asymmetry, separately, was taken forward to SEM. This model returned low model fitment scores and hence two alternate models were tested. In the first alternative, the human attributes were related with goal congruence and systemic attributes were linked with information asymmetry. In the second alternative, the relationships of the first alternatives were retained and two alternate relationships were introduced - integrity was linked with information asymmetry and structural was linked with goal congruence. Both models are very close to good model fitment scores. However, the second alternative returned better results and hence, was chosen as the final outcome of the research. The model reflects that human attributes and systemic attributes are fairly independent in an effective information security framework, and drive goal congruence and information asymmetry, respectively. However, integrity is an important human commitment for ensuring information asymmetry and the right organizational structure and roles are important for ensuring goal congruence.

This paper addresses the influence of a mechanistic world view of East-West relations. The "classic" model of mechanism orders reality into a relationship akin to a simple clock or pump. In the model, discrete and unmodifiable parts, with no natural functional relationship to each other, are balanced and engineered into functional unity. This study shows how "environmental" conditions at the international level (ambiguity, complexity, and prolonged conflict) limit the ability of policy makers to define objective limits to containment, influencing them instead to follow the universal application of the "logic" of mechanism--that any imbalance must be checked by the container.

This thesis addresses problems in the area of mechanism design. In many settings in winch collective decisions are made, individuals' actual preferences are not publicly observable. As a result, individuals should be relied on to reveal this information. We are interested in an important application of mechanism design, which is the construction of desirable procedures for deciding upon resource allocation or task assignment. We make two main contributions. First, we propose a new mechanism for allocating a divisible commodity between a number of buyers efficiently and fairly. Buyers are assumed to behave as price-anticipators rather than as price-takers. The proposed mechanism is as parsimonious as possible, in the sense that it requires participants to report a one-dimensional message (scalar strategy) instead of an entire utility function, as required by Vickrey-Clarke-Groves (VCG) mechanisms. We show that this mechanism yields efficient allocations in Nash equilibria and moreover, that these equilibria are envy-free. Additionally, we present distinct results that this mechanism is the only simple scalar strategy mechanism that both implements efficient Nash equilibria and satisfies the no envy axiom of fairness. The mechanism's Nash equilibria are proven to satisfy the fairness properties of both Ranking and Voluntary Participation. Our second contribution is to develop optimal VCG mechanisms in order to assign identical economic "bads" (for example, costly tasks) to agents. An optimal VCG mechanism minimizes the largest ratio of budget imbalance to efficient surplus over all cost profiles. The optimal non-deficit VCG mechanism achieves asymptotic budget balance, yet the non-deficit requirement is incompatible with reasonable welfare bounds. If we omit the non-deficit requirement, individual rationality greatly changes the behavior of surplus loss and deficit loss. Allowing a slight deficit, the optimal individually rational VCG mechanism becomes asymptotically budget balanced. Such a phenomenon cannot be found in the case of assigning economic "goods."

The aim of this study is to present a design approach for compliant bistable four-link mechanisms. The design constraints are the two positions of the mechanism, the force required to snap between the positions and the fatigue life of the designed mechanism. The theory presented here will be applied to the door lock mechanism used in commercial dishwashers, which is originally designed as a rigid inverted slider crank mechanism snapping between two positions with the force applied by a spring. The mechanism is re-designed as a compliant bistable four-link mechanism and a prototype has been manufactured.

Les mécanismes d’assortiment, sont des marchés dont l’objet est de réaliser une allocation économique efficace mais qui opèrent sans échange monétaire. L’efficacité d’un mécanisme peut être évaluée de manière théorique, mais il est aussi important d’évaluer sa performance avec des agents réels pour tenir compte des biais comportementaux et leur rationalité limitée. La thèse résumée dans cette note s’inscrit dans cette démarche en fournissant des résultats empiriques qui permettront d’améliorer l’utilisation des mécanismes d’appariement sur le terrain. Le premier chapitre de la thèse vise à analyser l’expérience acquise par des agents ayant participé à un mécanisme d’acceptation différée qui peut être transmise à de nouveaux participants pour améliorer l’efficacité du mécanisme. Les résultats obtenus montrent que les sujets sont plus susceptibles de révéler leur préférence réelle dans leur proposition quand ils reçoivent des conseils de leurs pairs des sessions précédentes. Le deuxième chapitre de la thèse étudie l’effet de la taille du marché sur la performance de deux mécanismes d’appariement. Les résultats montrent que l’augmentation du marché de 4 à 40 joueurs accroit le taux des participants qui révèlent leur préférence réelle dans leur proposition au mécanisme d’acceptation différée, mais que ce taux diminue dans le mécanisme de Boston. Le passage à une taille de marché de 4000 joueurs n’a pas d’effet supplémentaire significatif. Le troisième chapitre de la thèse justifie l’évolution du système d’admission des Universités en Chine. Des études montrent que le mécanisme de Boston n’élimine pas l’envie justifiée, qu’il est manipulable, et qu’il n’est pas Pareto-efficace. Le mécanisme d’allocation simple élimine l’envie justifiée, et il est non-manipulable et Pareto-efficace. Ce résultat justifie la transition récente de l’algorithme de choix séquentiel à l’algorithme de choix parallèle dans les pratiques d’admission aux Universités chinoises. / This thesis consists of three essays examining empirical factors that are important for the success of the matching mechanism in the real world. The first chapter discusses whether highly experienced people can transmit what they have learned and encourage new participants to reveal their true preferences under the Deferred Acceptance mechanism. I address this issue in a laboratory experiment to check the effect of peer experience on individual behaviors and the performance of the DA mechanism. Results show that subjects are more likely to play truthfully when learning advice from their peers in previous sessions.The second chapter studies the performance of the Boston and the DA mechanism in a laboratory under different scale of the matching markets. Results show that increasing the market size from 4 to 40 students per match increases participant truth-telling under the DA but decrease it under the Boston mechanism, leading to a decrease in efficiency but no change in the large stability advantage of the DA over the Boston mechanism. However, further increase in the scale to 4,000 students per match has no effect.The third chapter justifies the evolution of the college admissions system in China from a mechanism design perspective. Studies show that the Boston mechanism does not eliminate justified envy, is not strategy-proof and is not Pareto-efficient. The Simple Serial Dictatorship mechanism eliminates justified envy, is strategy-proof and is Pareto-efficient, thus outperforming the Boston mechanism in all three criteria. This result provides justification for the mechanism transition in recent years in China’s college admissions practices.

<p>In many multiagent settings, a decision must be made based on the preferences of multiple agents, and agents may lie about their preferences if this is to their benefit. In mechanism design, the goal is to design procedures (mechanisms) for making the decision that work in spite of such strategic behavior, usually by making untruthful behavior suboptimal. In automated mechanism design, the idea is to computationally search through the space of feasible mechanisms, rather than to design them analytically by hand. Unfortunately, the most straightforward approach to automated mechanism design does not scale to large instances, because it requires searching over a very large space of possible functions. In this thesis, we adopt an approach to automated mechanism design that is computationally feasible. Instead of optimizing over all feasible mechanisms, we carefully choose a parameterized subfamily of mechanisms. Then we optimize over mechanisms within this family. Finally, we analyze whether and to what extent the resulting mechanism is suboptimal outside the subfamily. We apply (computationally feasible) automated mechanism design to three resource allocation mechanism design problems: mechanisms that redistribute revenue, mechanisms that involve no payments at all, and mechanisms that guard against false-name manipulation.</p> / Dissertation

abstract: Space systems such as communication satellites, earth observation satellites and telescope require accurate pointing to observe fixed targets over prolonged time. These systems typically use reaction wheels to slew the spacecraft and gimballing systems containing motors to achieve precise pointing. Motor based actuators have limited life as they contain moving parts that require lubrication in space. Alternate methods have utilized piezoelectric actuators. This paper presents Shape memory alloys (SMA) actuators for control of a deployable antenna placed on a satellite. The SMAs are operated as a series of distributed linear actuators. These distributed linear actuators are not prone to single point failures and although each individual actuator is imprecise due to hysteresis and temperature variation, the system as a whole achieves reliable results. The SMAs can be programmed to perform a series of periodic motion and operate as a mechanical guidance system that is not prone to damage from radiation or space weather. Efforts are focused on developing a system that can achieve 1 degree pointing accuracy at first, with an ultimate goal of achieving a few arc seconds accuracy. Bench top model of the actuator system has been developed and working towards testing the system under vacuum. A demonstration flight of the technology is planned aboard a CubeSat. / Dissertation/Thesis / Masters Thesis Mechanical Engineering 2016