在近期的研究結果中, 相分離被發現發生在具非晶結構的Pd₄₁.₂₅Ni₄₁.₂₅P₁₇.₅合金，而該合金的構成元素之間的有負值的混合焓。通過高分辨率透射電子顯微鏡的直接成像的方法，他們為Pd-Ni-P非晶系統相分離的發生提供了證據。 / 在這篇論文所論述的研究工作中，我們運用類似的技術來研究Pḍ₄₀₊₀₅{U+2093}Nị₄₀₊₀₅{U+2093}P₂₀₋{U+2093}的合金系統從 x = 0到3.5的非晶相分離。 / 實驗結果顯示，任何在空氣中冷卻到578 K再在613K退火一小時的樣品 (乙類樣本)，非晶相分離都沒有發生。然而，在613K退火一小時而沒有經過578K和613K溫度範圍的Pḍ₄₀₊₀₅{U+2093}Nị₄₀₊₀₅{U+2093}P₂₀₋{U+2093}大塊非晶金屬(丙類樣本)，卻在部分成分範圍中發生相分離。在丙類樣本中，當x>1，相分離發生；而當x≤1，相分離沒有發生。通過量度高角環形暗場影像中顯示的兩個相的平均波長，我們可得出其統計結果，而該統計結果與槓桿規則吻合。從此可見，在過冷的Pd-Ni-P熔合合金中存在著亞穩液態混溶間隙。並且這種出現在有負值混合焓的系統的亞穩液態混溶間隙，可以以短程有序的模型來解釋。 / Recently, the phase separation was found in the system of amorphous Pd₄₁.₂₅Ni₄₁.₂₅P₁₇.₅ alloys which has negative heat of mixing among the constituent elements. In their work, the directly imaging method by technique of high resolution TEM provided the evidence of phase separation in amorphous Pd-Ni-P system. / In this work, by applying the similar technique of that previous studies, the alloy systems of Pḍ₄₀₊₀₅{U+2093}Nị₄₀₊₀₅{U+2093}P₂₀₋{U+2093} for x = 0 to 3.5were studied for amorphous phase separation. / The experimental result showed that for any sample which was allowed to cool down in air to 578 K before thermal annealing (B-type), there was no amorphous phase separation. But for the Pḍ₄₀₊₀₅{U+2093}Nị₄₀₊₀₅{U+2093}P₂₀₋{U+2093} BMG that was annealed at 613K for one hour without bypassing the temperature range between 578K and 613K (C-type), phase separation occurred with x>1 but absented when x≤1. The result of average wavelength measurement of the two phases in the HAADF images of the sample with phase separation obeyed the lever rule. This result suggested that in undercooled molten Pd-Ni-P alloys, there is a metastable liquid state miscibility gap. The formation of such miscibility gap in a system with negative heat of mixing can be explained by the model of unique short range orders. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Lau, Man Tat = 過冷鈀、鎳、磷熔化物中的亞穩液態互溶間隙 / 劉文達. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references. / Abstracts also in Chinese. / Lau, Man Tat = Guo leng ba, nie, lin rong hua wu zhong de ya wen ye tai hu rong jian xi / Liu Wenda. / Abstract --- p.i / Acknowledgement --- p.iv / List of Tables --- p.vii / List of Figures --- p.viii / Chapter Chapter 1 --- : Introduction --- p.1 / Chapter 1.1 --- Amorphous metal --- p.1 / Chapter 1.2 --- Phase Separation --- p.3 / Chapter 1.3 --- Nucleation --- p.6 / Chapter 1.4 --- Spinodal Decomposition --- p.10 / Chapter 1.5 --- Objective of the project --- p.16 / Figures --- p.18 / References --- p.26 / Chapter Chapter 2 --- : Experiment --- p.27 / Chapter 2.1 --- Preparation of sample --- p.27 / Chapter 2.2 --- Differential scanning calorimetry --- p.30 / Chapter 2.3 --- Preparation of TEM sample --- p.31 / Chapter 2.4 --- Microstructural analysis --- p.33 / Figures --- p.36 / References --- p.39 / Chapter Chapter 3 --- : A metastable liquid state miscibility gap in undercooled Pd-Ni-P melts --- p.40 / Chapter 3.1 --- Introduction --- p.40 / Chapter 3.2 --- Materials and experimental --- p.41 / Chapter 3.3 --- Results --- p.44 / Chapter 3.4 --- Discussions --- p.49 / Chapter 3.5 --- Conclusions --- p.52 / Table --- p.53 / Figures --- p.54 / References --- p.75

Thesis (Ph. D.)--Drexel University, 2005. / Includes abstract and vita. Includes bibliographical references (leaf 130).

Thesis (Ph. D.)--Drexel University, 2006. / Includes abstract and vita. Includes bibliographical references (leaves 157-163).

Thesis (Ph. D.)--Drexel University, 2007. / Includes abstract and vita. Includes bibliographical references (leaves 140-145).

Thesis (Ph.D)--Mathematics, Georgia Institute of Technology, 2009. / Committee Chair: Yi, Yingfei; Committee Member: Chow, Shui-Nee; Committee Member: Dieci, Luca; Committee Member: Verriest, Erik; Committee Member: Weiss, Howie. Part of the SMARTech Electronic Thesis and Dissertation Collection.

A thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy. Johannesburg / In this thesis we investigate the evolution of viscous FRW cosmological models for two different constitutive equations for the bulk viscous pressure a, namely (Abbreviation abstract) / Andrew Chakane 2018

A thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy. Johannesburg, / In this thesis we investigate the evolution of viscous FRW cosmological models for two different constitutive equations for the bulk viscous pressure a, namely: The truncated theory,,,,,,,,,,,,,,,, and the full (non-truncated] Israel-Stewart theory ...................We first review the relativistic theory of non-equilibrium thermodynamics developed by Eckart (1940) and the essentially equivalent formulation of the theory given by Landau and Lifshitz (1958). We give a, brief description of the relativistic second-order theories found by Israel and Stewart (1976) and subsequently developed by Pavon, Jou, and co-workers (1982, 1993). All this is done in order to develop the tools for the study of the evolution of FRW cosmological models in the context of causal thermodynamics. We find new exact and perturbative solutions of Einstein's field equations for the truncated Israel-Stewart theory of irreversible thermodynamics. We show that viscous effects speed up the expansion of the universe. We also consider a viscous fluid in the presence of a " non-interacting scalar field and show that inflationary solutions exist. The full theory of bulk viscosity is applied to dissipative FRW spacetimes. New causal viscous inflationary solutions are presented. These solutions extend the results obtained by Maartens (1995a) to cases where the coefficient of bulk viscosity e and the relaxation time r are independent. Power-law solutions for the scale factor are shown to exist. / Andrew Chakane 2018

Active nematic elastomers are a class of active materials that possess the elasticity of a rubber, and the orientational symmetry of a liquid crystal. Their constituent elements are typically elongated, cross-linked and active. The cross-linking of the elements leads to an elasticity that prevents the material to ow like a liquid. These elements are active in a sense that they continuously consume and dissipate energy, creating a state that is far-from-equilibrium. Active nematic elastomers may be a good physical model for biological systems such as the metaphase spindle, a complex biological machine that is made of an integrated assembly of microtubules and molecular motors. These motors not only cross-link the microtubules, but also actively slide them against each other, creating a highly dynamic, non-equilibrium state. The metaphase spindle, like other non-equilibrium structures in biology, has important functions to perform. During mitosis, the spindle is responsible for (1) capturing the sister chromatids, (2) bringing all the sister chromatids to the equator of the mother cell, and (3) segregating the daughter chromosome to the opposite poles of the cell. Thus, a fundamental challenge to biological physics is to understand the complex dynamics of the spindle, and similar systems, using the tools of non-equilibrium statistical mechanics. In this Thesis, we develop and explore a phenomenological model for an active nematic elastomer. We formulate the dynamics of this phenomenological model by incorporating the contribution of the active elements to the standard formulation of the hydrodynamic equations of a passive system. In a coarse-grained picture, the activity is taken into account as an extra active stress, proportional to the alignment tensor, added to the momentum equation of an otherwise passive nematic elastomer. Having obtained the equations of motion of an active nematic elastomer, we then investigate the response of the system to an external field by means of examining the structure and the stability of the modes. An active nematic elastomer has eight modes, in which six modes are propagating and two modes are massive. Out of the six propagating modes, two modes are in the longitudinal direction, linked to the density waves, and the other four modes are in the transverse direction, linked to the shear waves. The nature of these propagating modes transitions from dissipative and oscillatory, and vice versa, depending on the length scales. In particular, their stability is largely determined in the hydrodynamic limit, by a competition between the stabilizing effect of the elasticity and the destabilizing effect of the activity. In fact, the activity renormalizes the elastic coefficients down to even a negative value in some cases and thus, rendering the system linearly unstable. This is in contrast to the well-known instability of an active nematic liquid crystal, which is always linearly unstable. We then map out and discuss the stability phase diagram of the active nematic elastomer. Next, we compute and study various equal-time correlation functions of an active nematic elastomer, assuming that the noise spectra are thermal in origin. We find that they can be conveniently arranged into two terms. The first term has the exact mathematical structure of the equal-time correlation functions of a passive nematic elastomer, albeit with certain coefficients renormalized by activity. The second term, which is proportional to the activity, represents the non-equilibrium nature of an active nematic elastomer, and manifestly breaks the Fluctuation-Dissipation Theorem. We also find that (1) the displacement-displacement correlation function decays inversely with the square of the wave number for both the compressible and incompressible nematic elastomer, similar to that of a passive nematic elastomer, with elastic coefficients renormalized by the activity. (2) The density-density correlation function approaches a constant at the long wave-length limit, since the conservation of mass links the density to the rate of changes of the displacement in the longitudinal direction. (3) The director-displacement correlation function is purely imaginary, and thus the director is locked to the displacement with a (π/2) phase-shift. (3) The director-director correlation function approaches a constant value in the long-wavelength limit, instead of decaying inversely with the square of the wave number, like it would for a liquid crystal. This is because of the massive mode stems from the coupling energy, and it indicates that director in the large length scale is locked to a specific angle. These theoretical results are in qualitative agreement with the experimental measurements of the spindle. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2019. / FAU Electronic Theses and Dissertations Collection

Thesis (Ph. D.)--Hong Kong University of Science and Technology, 2003. / Includes bibliographical references (leaves 122-129). Also available in electronic version. Access restricted to campus users.

Thesis (Ph.D.)--Australian National University, 2005.