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We have developed a probe to measure specific heat of Gd-doped PbMo(_6)S(_8), at low temperatures in high magnetic fields up to 12.5 T using a heat pulse method and an a.c. technique. Comparison between these heat capacity measurements and transport measurements provides critical complimentary information about fundamental thermodynamic properties and granularity m superconductors. We have used a tiny, robust, highly sensitive and broadly field independent Cemox thermometer (CX-1030), eliminating the use of bulky gas thermometry or capacitance thermometry. The diameter of the probe is 20 min which facilitates use in our 17 T high field magnet and in free-standing cryostats. Experiments include accurate measurement of temperature oscillations of 10(^-6)K. The measurements and analysis of the data were made fully computer controlled. Measurements on Cu and NbTi demonstrate we achieved an accuracy of ±0.2 K in temperature and a typical accuracy of -10% m the specific heat values quoted. Gd-doped Lead Chevrel phase material Pb(_1-x)Gd(_x)Mo(_6)S(_8) has been fabricated in a controlled environment using simple sintering methods and a Hot Isostatic Press (HIP) operating at pressures up to 2000 atmospheres. Cp has been measured and the properties of the materials including B(_c2)(T) have been determined. HIP processing improves the materials, increasing Tc ~ 15 K and B(_c2)(0) ~ 60 T. These values are amongst the best reported values for the Chevrel phase materials to date. I am personally responsible for taking all the data and its analysis. The modification of the probe were also undertaken by me. The fabrication of the samples was not my work

This thesis introduces the original idea that it is possible, and productive, to consider the ‘blending’ of (or deliberate creative combining of methods from) the fields of fine art practice and science practice, using selected empirical research methods to investigate constructions of self and self-identity that emerge between disciplines. In particular, the thesis investigates how the scientific aspects of modern computer games, for instance, can be seen to affect emotional responses from viewers and how those responses are, in turn, affected by the ‘blending’ of aesthetic concerns with consideration of alternative cognitive processes that induce relaxation to connect with participant-players’ self-identities. This process created a method to access cognitive processes, hitherto unexplored by computer-game developers. This research locates its arguments primarily in and between the disciplines, Art and Game Studies and supports the findings with examples taken from art practice and with theories of Psychology and Gaming. This thesis documents the creation of the author’s original hybrid ‘art- work-game’, known as ‘Star World’. It describes the process of ‘Star World’s’ creation, with analysis of the efficacy of this environment as a space where the mapping of narrative, and where perceptual and interactive ‘blendings’ of self and self-identity were employed and tested, with both qualitative and empirical studies of the experiences and perceptions of participant-players. The research focuses on how the distinctive abstract environment, ‘Star World’, affords and facilitates personal expression and interaction for computer-game players. It reveals specific cognitive processes undergone by participant-players; evidence that supports and validates the conjecture that participant-players use personal frames of reference when navigating, exploring and interpreting computer games. Teach-back protocols and their impact are shown to improve the interactivity and immersive potential of the environment. Overall, this thesis classifies ‘haute game’ rules that are formulated to identify virtual environments creating unique, alternative ‘blendings’ with participant-players and assembles a framework for developers to pursue, when producing original computer-game genres. It offers an innovative case study of value to future scholars of Game Studies, as well as to game developers, with cautionary examples provided to assist in dealing with situations where emotional states are accessed by game play. This thesis highlights the potential of interactive art and game design to produce beneficial outcomes for its participant-players, moreover, it demonstrates, with empirical evidence, the effect of the virtual environment on its participant-players.

The thesis presents models for short term planning (24 hours) of a hyro dominated hydrothermal power system. The purpose of the models is to minimizae the system operation costs to provide a forecasted load and keep enough spinning reserve. / This thesis presents models for short term planning (24 hours) of a hydro dominated hydrothermal power system. The purpose of the models is to minimize the system operation cost to provide a forecasted load and keep enough spinning reserve.   The thesis focuses on two issues in hydro power modelling. The first issue is the relationship between water discharged and power generated. This relationship is a non-linear and non-convex function. If the plant has several units, the efficiency of the plant will have local maximums, so called local best-efficiency points. The second issue is to take into account the cost of start-ups of hydro units in the planning.   The hydro model is mixed-integer. Discharg􀁐s are allowed at zero flow, the local best-efficiency points and on the continuous part between the local best-efficiency point with the highest flow and the point with maximum flow. This last continuous part is modelled as a linear function. In order to get data for the start-up cost a survey among the largest power producers in Sweden has been made, where three questions about start-ups of hydro power units has been asked: What causes the costs in the start-up?, How much does a start-up cost? and How do start-ups effect the short-term scheduling strategies of power producers in Sweden? The results show that a fair estimate of the start-up cost is about $3/MW nominal output. For the thermal plants a standard model with polynomial operation cost, start-up costs and ramp-rate constraints has been used. The model also includes the possibilities of purchasing and selling power to forecasted prices.   The planning problem is formulated as a mathematical programming problem. The solution technique uses Lagrange relaxation to decompose the problem into subproblems. There will be one subproblem for each hydro and thermal plant. In order to find good feasible solutions a heuristic technique to change the integer variables in the hydro system has been developed. The Lagrange multipliers are updated with the subgradient method.   The models are tested in three different load situations; a winter day (heavy load), an autumn day (medium load) and a summer day (light load). The result shows that the method gives near optimal schedules in reasonable computation time in cases with a normal part of the thermal units committed. The assumed start-up cost results in that hydro units almost never are started or stopped for one hour only. / <p>QC 20161206</p>

The purpose of the research study was to provide improved relaxation training with the use of an electromyography feedback device based on the design of Green et al. (1969). It was intended that this instrument would allow the training of deep muscle relaxation to the point of neuro-muscular silence, while remaining inexpensive enough to be applied in the clinical setting.

Call number: LD2668 .T4 1957 D57 / Master of Science

Thesis advisor: Michael J. Graf / This thesis is concerned with experimentally determining the magnetic and electronic states in a unique class of transition metal oxides known as the pyrochlore iridates, A₂Ir₂O₇ (A = Y or Rare earth). The extended nature of the 5d Ir orbitals in the iridates places these materials in a regime of intermediate electron correlation and large spin-orbit interaction such that this system may host several novel or topological states of matter which may be perturbed by incorporating different A-species. Additionally, the pyrochlore structure is geometrically frustrated and has been long been studied as a potential host of a number of exotic magnetic phenomenon. However, even after years of intense theoretical and experimental interest many fundamental questions still remain about the nature of the magnetic ground sates in this series which are of vital importance in understanding the roles of various interactions and potential of such novel phenomenon. The primary aim of this thesis is therefore to determine how magnetic order develops on the Ir sublattice in this series, particularly how it is perturbed through variation of the crystalline structure, magnetism of the A-site ions, and presence of mobile charges. This thesis is the first comprehensive experimental study of these effects which has utilized several complementary experimental probes of both bulk and local magnetism in a number of compounds. The techniques presented in this work include magnetotransport, bulk magnetization, elastic neutron scattering, and muon spin relaxation (µSR) measurements. All of the three compounds studied in this work (A = Y, Yb, and Nd) are shown to definitively exhibit long-range magnetic order on the Ir sublattice, which has previously only been inferred based on studies of other compounds. The compounds Y₂Ir₂O₇ and Yb₂Ir₂O₇ are correlated insulators at low temperature and are found to have identical configuration of the Ir moments, despite the presence of the large localized Yb³⁺. Numerical investigations presented here have provided the first conclusive evidence that this order is of the `all-in/all-out' type, consistent with recent resonant x-ray studies; additionally, we have shown that this order exists for all insulating compounds regardless of structural parameters or properties of the A-ion. On the other hand, Nd₂Ir₂O₇ is weakly metallic with Kondo-like behavior at low temperature, with long-range order only on the Ir site, in disagreement with previous results from neutron scattering. Measurements of the field dependent magnetization and Hall effect reveal a large anomalous Hall component, suggesting that the Nd<super>3+</super> may exhibit a spin-ice state with very short correlation length, while the Ir sublattice is likely in the `all-in/all-out' state. From this, it is determined that Nd₂Ir₂O₇ lies at an important cross-over point in the series in which correlation energy and conduction bandwidth yield chiral order with features akin to both the metallic unordered Pr₂Ir₂O₇ and those of the magnetically ordered insulators. These results are discussed with regard to recent theoretical models exploring the role of electron correlation, frustration and various exchange interactions in these materials. / Thesis (PhD) — Boston College, 2013. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Physics.