Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 2003. / Thesis supervisor: Neil E. Todreas. Includes bibliographical references (p. 117-121). Also available online.

Thesis (Ph. D.)--University of Oregon, 2000. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 374-384). Also available for download via the World Wide Web; free to University of Oregon users.

Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references (leaves 158-168). Available also in a digital version from Dissertation Abstracts.

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.

Static measures such as density and entropy, which are intimately connected to structure, have featured prominently in modern thinking about the dynamics of the liquid state. In this dissertation, we explore the connections between self-diffusivity, density, available space, and excess entropy in two non-trivial problems in liquid state theory, confined and supercooled liquids. We present exact simulation data for the relationship between self-diffusivity and excess entropy for a wide range of simple of simple fluids (i.e. hard-sphere, Lennard-Jones and square-well) confined to pores with a variety of different sizes and fluid-wall interations. Our main finding is that, at a given temperature, self-diffusivity of the confined fluids collapses onto the bulk behavior when plotted versus excess entropy. In other words, the only information required to "predict" the implications of confinement for the single-particle dynamics is the bulk fluid behavior at a given temperature and the excess entropy of the confined fluid. This should prove practically useful given that the bulk behavior is well known for these fluid systems, and the excess entropy of the confined fluids can be readily estimated from classical density functional theory. We also show that the self-diffusivity of the confined fluids approximately collapses onto the data for the corresponding bulk fluid when plotted versus the average packing fraction (which is based on total, rather than center accessible volume). For continuous interaction potentials such as Lennard-Jones, calculation of effective packing fraction requires knowledge of both the number density of the fluid and a temperature-dependent Boltzmann diameter associated with the repulsive part of the interparticle interactions. We suggest a way to calculate this effective diameter, which to a very good approximation, collapse the temperature- and density-dependent data for the self-diffusivity of the bulk Lennard-Jones fluid onto hard-sphere fluid data plotted versus the fluid's effective packing fraction. Finally, we found that the self-diffusivities of several model systems in their supercooled state also scale exponentially not only with the excess entropy, but also with the two-body contribution to the excess entropy obtained from the pair correlation function of the fluid. The latter observation is particularly interesting because it provides direct evidence of a quantitative link between the dynamics and the average structural order of supercooled liquids. Whether such a connection could indeed be discovered is part of a long-standing question in the study of liquids. / text

Η αναλογία μεταξύ των νόμων της μηχανικής της μελανής οπής και των νόμων της θερμοδυναμικής οδήγησε τους Bekenstein και Hawking να υποστηρίξουν ότι οι μελανές οπές θα πρέπει να θεωρηθούν ως πραγματικά θερμοδυναμικά συστήματα, τα οποία χαρακτηρίζονται από εντροπία και θερμοκρασία. Πιο συγκεκριμένα, ο Bekenstein υποστήριξε ότι η εντροπία μίας μελανής οπής ισούται με S=(k_BAc^3)/(4G\hbar), όπου A είναι το εμβαδό της επιφάνειας του ορίζοντά της, ενώ ο Hawking ότι η θερμοκρασία μιας μελανής οπής είναι T=(\hbar\grk)/(2\pi ck_B), όπου κ είναι η επιφανειακή της βαρύτητα. Η αντιστοιχία μεταξύ των νόμων της μηχανικής της μελανής οπής και αυτών της θερμοδυναμικής υποδηλώνει την ύπαρξη μιας βαθύτερης σχέσης μεταξύ της θερμοδυναμικής και της βαρύτητας. Η προοπτική αυτή παρακίνησε τη διατύπωση αρκετών ιδεών που υποστηρίζουν ότι συνολικά η βαρύτητα μπορεί να ερμηνευθεί ως ένα θερμοδυναμικό φαινόμενο. Η πρωτότυπη ιδέα ανήκει στον Jacobson, ο οποίος αντέστρεψε τη λογική και έδειξε ότι η εξίσωση του Einstein μπορεί να θεωρηθεί ως μία καταστατική εξίσωση. Αργότερα, σε μία σειρά δημοσιεύσεων, ο Padmanabhan έδειξε ότι σε ορισμένες περιπτώσεις οι εξισώσεις της βαρύτητας μπορούν να ερμηνευθούν με όρους της θερμοδυναμικής ή ακόμη και να εξαχθούν από τη θερμοδυναμική του χωροχρόνου. Πιο πρόσφατα, ο Verlinde υπόστηριξε ότι η βαρύτητα είναι μία εντροπική δύναμη. Τα παραπάνω επιχειρήματα αποτελούν συνιστώσες της ευρύτερης απόψης που διατυπώθηκε αρχικά από τον Sakharov και υποστηρίζει ότι η βαρύτητα δεν είναι μία θεμελιώδη δύναμη, αλλά αντίθετα μία αναδυόμενη (emergent) δύναμη, η οποία προκύπτει ως το όριο κάποιας υποκείμενης μικροσκοπικής άγνωστης προς το παρόν θεωρίας, υπό την ίδια έννοια που η υδροδυναμική ή η θεωρία της ελαστικότητας αναδύονται από τη μοριακή φυσική. Στην παρούσα εργασία μελετάμε τα επιχειρήματα των Jacobson, Padmanabhan και Verlinde που υποστηρίζουν την ερμηνεία της βαρύτητας ως μια θερμοδυναμική θεωρία. / The analogy between the laws of black hole mechanics and the laws of thermodynamics led Bekenstein and Hawking to argue that black holes should be considered as real thermodynamic systems that are characterised by entropy and temperature. In particular, Bekenstein argued that the entropy of a black hole is S = (k_BAc^3)=(4G\hbar), where A is the area of its horizon. In addition, Hawking showed that the temperature of a black hole is T = (\hbar κ)=(2πck_B), where κ is its surface gravity. Black hole thermodynamics shows a deeper connection between thermodynamics and gravity. This perspective motivated several ideas that suggest an interpretation of gravity as a thermodynamic phenomenon. The original idea is due to Jacobson. He first inverted the reasoning and showed that the Einstein's equation can be viewed as an equation of state. Later, Padmanabhan showed that the gravitational equations can be interpreted in terms of thermodynamics. He also showed that one can derive the gravitational equations from the thermodynamics of spacetime. More recently, Verlinde argued that gravity is an entropic force. The above arguments are components of the broader view, first formulated by Sakharov, that gravity is not a fundamental force, but an emergent one. It arises in the limit of some underlying--- yet unknown--- microscopic theory, in the same sense that hydrodynamics or elasticity emerge from molecular physics. In this thesis, we examine the arguments of Jacobson, Padmanabhan and Verlinde that suggest an interpretation of gravity as a thermodynamic theory.

No description available.

Thermodynamic properties are essential for the design of chemical processes, and they are most useful in the form of an equation of state (EOS). The motivating force of this work is the need for accurate prediction of the phase behavior and thermophysical properties of natural gas for practical engineering applications. This thesis presents a new cubic EOS for pure argon. In this work, a theoretically based EOS represents the PVT behavior of pure fluids. The new equation has its basis in the improved Most General Cubic Equation of State theory and forecasts the behavior of pure molecules over a broad range of fluid densities at both high and low pressures in both single and multiphase regions. With the new EOS, it is possible to make accurate estimations for saturated densities and vapor pressures. The density dependence of the equation results from fitting isotherms of test substances while reproducing the critical point, and enforcing the critical point criteria. The EOS includes analytical functions to fit the calculated temperature dependence of the new EOS parameters.

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No description available.