Thesis (Ph. D.)--University of Wisconsin--Madison, 1968. / Typescript. Vita. Includes bibliographical references.

No description available.

by Chan Man-ng. / Thesis (M.Ph.)--Chinese University of Hong Kong. / Bibliography: l. 108.

Since the discovery of high superconducting transition temperature in layered copper oxides, many researchers have searched for similar behavior in other layered metal oxides, such as cobalt and nickel. The sodium cobalt oxyhydrate is the first cobalt-oxide layered superconductor. We present the studies of low-temperature specific heat C(T, H) in NaxCoO2¡EyH2O (x ~ 0.35, y ~ 1.3). At H = 0, a very sharp anomaly was observed at T ~ 4.7 K indicating the existence of bulk superconductivity. There exists an £\T2 term in C(T, H=0) in the superconducting state manifesting the line nodal superconducting order parameter. The feature at the superconducting transition is rather sharp, becoming broad and strongly suppressed in an applied magnetic field. The transition temperature also changed in an applied magnetic field. Thus an abrupt change of slope in H vs. Tc curve was observed. Possible scenarios such as the multiple phase transitions in the mixed state are discussed.

Water is a continuous source of fascination to scientist because of its many counterintuitive low-temperature properties. Although the stable from of water at low temperature is crystalline, liquid water can also exist below the melting point. Many people study the interesting phenomenon of water at low temperature and it is found that two critical points may even coexist in a single component liquid [1]. The other properties of water, like melting point, viscosity, compressibility, self-diffusion constant have also been studied below low temperature [2-4]. Now, we want to take the advantage of the equipment we have in our laboratory to measure the temperature dependence of Cp of water confined in different scale of nano-pores. This is also the beginning for people to study the thermodynamic properties of water confined in nano-pores. In addition, I have learned a lot, such as to understand LabView graphical programming language, the skill to measure AC specific heat, DSC specific heat, and to set up TGA. It will be helpful for me in the future, I think.

Conventional superconductor could be explained by BCS theory (for Tc<35K), but the BCS theory is not valid for all superconductors with theincrease of critical temperature (Tc) in the continuous discovery of new superconductors. Later on, other theories, such as d-wave, line nodes, the point nodes, the s +g wave, the two gap model, have been proposed. After successfully applying the two-gap model on MgB2, we try to measure the magnetic field dependence of low-temperature specific heat on 2H-NbSe2. Subsequently, analysis is focused on checking whether the two-gap model could also be applied to NbSe2 . Based on this model, the corresponding two gap values are obtained. The nonlinear field dependence of electronic specific heat coefficient is also observed. Moreover, the positive curvature in Hc2(T) is similar to that in the other two-gap superconductor MgB2. Thus, the two-gap model appears to describe the superconducting gap function of 2H-NbSe2 better than s-wave and line nodes models.

Low temperature specific heat (LTSH) is a powerful tool to investigate the physical properties of bulk samples. For superconductivity, LTSH can probe the pairing state in superconductors and provides additional information under magnetic fields. In this thesis, I present comprehensive specific-heat studies of superconductivity in YNi2B2C, NbSe2, and CeRu2. (1) Single crystalline YNi2B2C was found to be superconducting at the superconducting transition temperature Tc ~ 13.77 K. The superconducting specific heat Ce(T) can be described by either the point-node or the two-gap model. (2) Single crystalline NbSe2 has a two-dimensional crystalline structure showing the Tc ~ 6.7 K and the anisotropy in the critical fields, Hc2¡æ/Hc2// ~3. We investigated the Ce(T) and the electronic specific heat £^(H) by the two-gap model. Obtained fitting parameters, such as gap values and the relative ratio of two gaps in both analyses (Ce(T) and £^(H)), are comparable meaning that the superconductivity of NbSe2 can be described by the two-gap scenario. (3) Finally, we studied the DC magnetic susceptibility and the specific heat of polycrystalline CeRu2 in different magnetic fields. In the bulk CeRu2, the amount of the possible impurity phase or nano-clusters was reduced after annealing. Based on the analysis results of zero-field and in-field specific heat, CeRu2 is a BCS-like superconductor with an anisotropic gap.

Thesis (Ph. D.)--University of Nebraska, 1934.

Thesis--John Hopkins Univ. / Vita. Bibliography: leaves 45-46.

[pt] Neste trabalho foi utilizado o método dos volumes de controle para solução das equações de balanço de massa, momentum e energia, relativas ao escoamento de ar através de um canal. Este é formado por duas paredes verticais, planas, paralelas e adiabáticas. A dissipação de calor, através de um elemento retangular isotérmico adjacente a uma das paredes, provoca a convecção natural. O pioneirismo está na utilização da condição de contorno de pressão para a solução de uma equação, que corrige s velocidades neste mesmo contorno, permitindo utilizar as equações de momentum em forma elíptica. É investigado o comportamento do número de Nusselt médio do canal para Rayleigh variando do Ra igual 153 a Ra igual 1223, com o elemento posicionado no início, no meio e no fim do canal, variando-se as aberturas do mesmo. Verifica-se também o comportamento do Nusselt local ao redor do elemento, assim como o campo de velocidade. Foi verificada a existência de uma distancia ótima entre as paredes do canal, para cada valor do número de Rayleigh. Conclui-se, portanto, que a geometria do elemento tem um efeito importante no processo de transferência de calor, não devendo ser desprezada. / [en] The control volume method was used to solve numerically the equations related to mass, momentum and energy balance. Air flows trough a channel formed by two vertical, flat, parallel and adiabatic walls. The natural convection was caused by a retangular Isothermal element attached to one of the walls. The innovation of this work lies in the utilization of the momentum equations in its elliptical form. It was achieved using the pressure boundary condition to solve an equation that corrects the boundary velocity. The variation of the medium Nusselt number was insvestigated from Ra equal 153 to Ra equal 1223, attaching the element in three diferent positions: at the beginning, in the middle, at the end of the channel and varyin the distance between the walls. The local Nusselt number and the velocity Field around the element were also studied. An optimum distance between the walls for each Rayleign number was that the geometry, of the element has a decisive effect on the heat transfer process, and so it must not be neglected.