VictorJuiz/thesis huggingface dataset:
Application of a phase-field model to ferroelectrics
Keywords: Ferroelectrics
Energy Harvesters
Phase-field model
Vortex patterns
Actuators

The current work uses a phase-field model to design nanoscale ferroelectric device concepts and to explore nanoscale ferroelectric behaviour. The results are expected to serve initial steps for nanoscale experimentation and to assist in the industrial application of ferroelectrics.
The use of ferroelectrics in nanoscale devices such as sensors or energy harvesters has increased in recent times. This has advanced research interests in nanoscale ferroelectric properties. In the current study, a phase-field model is used as a research tool to explore nanoscale behaviour of barium titanate. The model is first used to design and optimize nano-actuator concepts that generate actuation strains ~0.45%. This strain is four times as large as the strain offered by piezoceramic actuators in market. Next, the model is used to describe how scaling and surface conditions affect the formation of nanoscale polarization patterns, such as vortices. The results demonstrate the dominant effect of surface conditions and explain experimental observations of phase, tetragonality and polarization patterns in ferroelectric nanoparticles. The phase-field model is next extended to three dimensions and is used to test the stability of nanoscale periodic polarization patterns. The results describe the internal stress and electric fields developed in these patterns, and illustrate a mechanism of how complex polarization patterns can be formed under external strain or electric fields. Here, a conceptual design of an energy harvester is also explored.
The current work explores the application of a phase-field model as a design tool to develop nano-actuator and energy harvester concepts. The results on actuation/harvester cycle and the design parameter optimization would assist in developing device prototypes and eventually benefit in industrial fabrication. The phase-field model extended to three dimensions contributes to the study of domain patterns with out-of-plane polarizations and will assist in engineering a more realistic ferroelectric device. The results on the effects of scaling, surface energy and external loads on nanoscale polarization patterns, explains prior experimental observations of polarization patterns and provide useful insights on how to engineer domain configurations for nanoscale applications. Finally, the results motivate research towards developing prospective nanoscale applications from other smart materials, such as relaxors and ferromagnets.
Continuum modelling and numerical approaches for energy minimisation in diblock copolymers
Keywords: Phase field modelling
Energy minimisation
Gradient flows
Asymptotic analysis
Optimization
Finite element methods
Variational inequalties
Non-linear partial differential equations
High performance/parallel computing

We use a continuum phase field model to study pattern formation in Diblock Copolymers (DBCs), with an emphasis on terracing in thin films.
Phase separation in DBCs is an important process in nanotechnology that yields an array of highly regular structures on very fine length scales that are of enormous utility. Terraces are ubiquitous in thin film DBC melts. It was long believed that modelling these structures was an intractable problem, but recent attempts to do so using the Self Consistent (Mean) Field Theory (SCFT) were successful.
In this thesis, we use the simpler and more flexible Ohta-Kawasaki (non-local Cahn-Hilliard) Density Functional Theory (DFT) model, derived from the SCFT, with obstacle homogeneous, and long-range energy components. Our main result is that such models can be used to capture terraces in the simplified 2D scenarios we examine, and that these structures form as an inevitable consequence of a simple energy minimisation process.
We consider a 2-phase model for DBC micro-structure evolution, which we analyse rigorously and comprehensively. We study stationary and dynamic (gradient flow) variants of the problem, using the latter as the basis for an efficient but provably convergent numerical method for simulating DBC evolution. Our theoretical analysis and numerical method are based on a common Moreau-Yosida regularisation of the homogeneous energy component. We use the Semi-Smooth Newton (SSN) method to resolve the non-linearities in our numerical method. Comprehensive numerical experiments confirm our theoretical predictions, including a Method of Manufactured Solutions (MMS) test for the order of convergence. We propose a complete specification of the equally spaced global energy minimisers of the symmetric, 2-phase problem in 1D, and offer a practical algorithm for finding them. We explicitly characterise the Order-Disorder Transition (ODT) in parameter space.
We extend our 2-phase model and methods to a 3-phase situation involving a copolymer/homopolymer blend, in which the free surface of the copolymer can adjust to form terraces. We develop energy estimates for energy-minimising 1D morphologies in the sharp interface limit, which we then combine via a double-tangent construction to analyse low energy, 2D structures. We argue that thin films with terraces have a lower free energy than their flat counterparts. Time-dependent numerical simulations in 2D confirm these predictions and provide insight into the evolution of these structures. We replicate and extend recent SCFT results, by performing a numerical experiment in which a terrace forms from a flat initial state.
The model, tools and methods developed in this thesis should serve as a solid foundation for researching more complex, multi-step 3D terraces.
The making of labour precariousness in post-1949 China
Keywords: precarious workers
history
China

If Marxists are right, why did Mao’s China witness a prevalence of precarious labour? If mainstream modernization theorists are right, why has post-Mao China seen a growth of precarious workers? In the light of these paradoxes, this thesis asks: what are the mechanisms that generate labour precariousness in post-1949 China?
Drawing upon insights from Marxism, mainstream economics, Polanyianism, and the theory of primitive socialist accumulation, this thesis develops a theoretical framework to study the origins of labour precariousness in post-1949 China. Briefly, exploitation and exclusion are two major mechanisms that generate labour precariousness. Both the state and the market can exercise these mechanisms. Both mechanisms operate in spheres of production and social reproduction.
By applying this framework to the analyses of data mainly collected from archives and fieldwork, this thesis has the following findings. Under the exclusion-centred precarization regime in Mao’ era, to reconcile the contradiction between primitive accumulation and political legitimacy, the state built up a system of social exclusion. One’s location in this system determined one’s conditions of precariousness. The rigidity of this system was primarily mediated by the alternation between centralization and decentralization of industrialization, as well as by employment policies and labour movements. Under the exploitation-centred precarization regime in reform China, the previous social exclusion system has been curtailed and the extent of exploitation, in spheres of both production and social reproduction, defines one’s conditions of precariousness. The magnitude of exploitation has been modulated primarily by labour regulation, and by labour movements as well.
On top of these findings, this thesis also extends the extant literature by unveiling the continuities and discontinuities of labour precariousness practices and mechanisms in post-1949 China, and by contributing to two debates in this field. It shows that in the Chinese experience precarization is a process of proletarian unification and formalization is a limited remedy for labour precariousness.
Computational and experimental studies of exotic magnets and superconductors
Keywords: Superconductivity
Magnetism

The advent of metalworking during the bronze age marked a transition in humankind’s relationship with materials: instead of materials existing only as they were found in nature, one could now manipulate their physical properties to make them fit for purpose. With the discovery of quantum mechanics, the new opportunities to manipulate materials were manifold. The collective behaviour of electrons inside a solid is much more than the sum of its parts; as such, in some bulk materials, new quantum mechanical behaviour can emerge. We can use our knowledge of quantum mechanics to manipulate these quantum materials, and thus we find ourselves not in the bronze or the iron age, but in the quantum age.
This thesis is a series of four studies on a range of quantum materials.
I begin with emergent magnetic monopoles in spin ice. While there have been many bulk studies of monopoles, there is yet to be a microscopic measurement of small ensembles of these emergent quasiparticles. I use Monte Carlo methods to simulate the expected magnetic field fluctuations arising from small numbers of monopoles passing close to a probe near the surface of a spin ice, and show that the presence of monopole excitations produces unique features in the magnetic noise spectrum. I also propose several experiments which may be able to detect these features.
I then move onto CoTi2O5. Using muSR and neutron powder diffraction, as well as theoretical calculations, I find that this material undergoes a transition to an antiferromagnetic state, which is coupled to a spontaneous breaking of structural symmetry. This makes CoTi2O5 the lowest-known-symmetry crystal to undergo the spin Jahn-Teller effect. I then present a possible magnetostructural coupling regime.
The remaining studies examine the importance of topology in the successful understanding of quantum material systems. I use μSR to investigate both the ACa2Fe4As4F2 (A = K, Rb, or Cs) and LuxZr1-xB12 families of superconductors. It is possible to alter the topological character of the superconducting gap in these families, either by manipulating the chemical spacer layers in the crystal structure of ACa2Fe4As4F2 or by changing x in LuxZr1-xB12. Along with the gap topologies, both the penetration depths and critical temperatures of these compounds appear to be sensitive to these chemical manipulations. I investigate how these topological crossovers are linked to the other superconducting properties of these materials, and discuss the consequences for our wider understanding of superconductivity.
The language of kingship under Henry III: civilian, canonical, and dictaminal ideas in practice, c.1230-c.1252
Keywords: canon law
civil law
dictamen
kingship

This thesis is a study in how the political culture of the reign of Henry III was conditioned by its engagement with wider continental ideological and administrative developments. Within the shared legal and cultural space of ‘Europe’, a number of factors contributed to the development of a language of power both secular and spiritual, including the growth of universities, the study of Roman civil and canon law, the development of dictamen and the increasing prominence of the mobile curial administrative elite. I propose that these influences were of signal importance for the reign of Henry III in its own right, and also in the longer-term development of later medieval English political culture.
The chapters of the thesis evaluate these influences through three sections: prosopographical, textual and linguistic. Chapter 1 examines the personnel of royal government, exploring both the contributions to royal government made by foreign clerks, and the participation of other royal servants in European cultural networks. Chapter 2 turns to analysis of legal and dictaminal manuscripts, exploring the challenges in reconstructing medieval reading culture. In Chapter 3, the circulation of such manuscripts over the longer thirteenth century is evaluated to demonstrate their influence on royal government. In Chapter 4, the thesis turns to linguistic influence during the period of the personal rule, 1230-1250, exploring the impact of Romano-Canonical legal concepts on the discussion of royal power. Chapter 5 looks at the impact of the same concepts on discussion of the wider political community. The final chapter considers the influence of dictamen on the rhetoric of royal government. Bringing these strands together, the thesis shows that a cultivated and cosmopolitan elite, serving Henry III and knowledgeable in the learned laws and rhetoric, adapted that knowledge to their portrayal and implementation of royal government, with lasting significance for this reign and beyond.
The Phytomonas cell surface proteome: Insights into the evolution of the parasite-host interface in Trypanosomatids
Keywords: Proteomics
Trypanosomatid
Parasites
Plant Pathology

The trypanosomatids are a diverse group of obligate parasitic eukaryotes that have adapted to colonise multicellular and unicellular hosts that span the eukaryotic tree of life. The genetic resources that have enabled trypanosomatids to colonise such a diverse range of hosts are largely unknown. However, there is precedent that adaptation is in part facilitated through the evolution of families of cell surface proteins. The aim of this thesis was to broaden our knowledge of how trypanosomatids have adapted their cell surface to colonise different hosts through a combination of proteomic and bioinformatic approaches. The principal body of work is focussed on Phytomonas, a globally distributed genus of plant infective trypanosomatids that are transmitted by insects. As a sister group to Leishmania parasites of animals, this study of Phytomonas informs our understanding of how trypanosomatids have evolved from a monoxenous parasite of insects to adapt to both mammalian and plant hosts. To provide further resolution, a second species, Trypanosoma carassii (an extracellular parasite of cyprinid fish) was also analysed. T. carassii occupies an informative position in the phylogenetic tree of trypanosomatids as an outgroup to the salivarian and stercorarian Trypanosoma species. The results of the bioinformatic analysis presented in this thesis reveal that there is a conserved core of trypanosomatid cell surface proteins, the majority of which have no known function. Bioinformatic and proteomic results show that the cell surface of T. carassii is covered in one or more novel and unique families of GPI anchored proteins. The study of P. serpens indicates that while evolution to parasitise plants was facilitated though adaptation of the cell surface, there was no evidence for the innovation of large families of cell surface proteins as is observed in Trypanosoma and Leishmania species. Placed in an evolutionary context, the results presented in this thesis provide some insight into how these enigmatic parasites evolved from a single common ancestor to parasitise a broad host range from coconuts to crocodiles.
The normativity of obligations: trust, blame, and interpersonal agency
Keywords: Ethics
Moral
Obligation
Normativity

This dissertation defends Deontic Pragmatism -- the view that the normativity of obligations is grounded in reasons to engage in interpersonal agency. I defend an account of obligations as correctness standards grounded in specific kinds of reasons. On this view, all obligations are directed from one person to another because these reasons are facts about a specific bipolar relation between people. To be a moral person is, in part, to comply with one's obligations for such reasons, by caring about other people and how they rely on oneself. Such caring attitudes are constitutive of the kinds of relationships people have reasons to have with one another. Indeed, the trusting attitudes such relationships also constitutively involve presuppose that others hold such caring attitudes towards us. In turn, the blaming responses to which trust disposes us presuppose that people fail to respond to such reasons, by failing to hold such caring attitudes.
I argue that this nexus between obligations, trust, blame, and relationships is played out across the entire moral domain. I then defend an account of the reasons people have to hold such attitudes. On this view, reasons that ground correctness standards, including obligations, are shared by people in virtue of their engagement in activities. Specifically, it is correct for people to have moral relationships, because they have reasons to intend to engage in interpersonal activities that involve mutual dependence relations. And they have those reasons, I argue, whatever other activities they are engaged in. Since such dependence is presupposed by the attitude of reliance involved in trust, the reasons that ultimately ground our obligations are grounded in a relation that is itself presupposed by the attitude of trust.
Probing the risks of moral enhancement
Keywords: virtue theory
moral enhancement
moral psychology

Attempting to improve fundamental moral dispositions with technology is prone to unexpected consequences. These dispositions are complex, and fragile when faced with technological interventions. For instance, a drug increasing the disposition to co-operate between individuals can unexpectedly lead to group conflict because it can increase parochialism. Furthermore, these interventions might be detrimental to a person’s psychological unity over time and thus might undermine interests whose realisation is sensitive to the continuation of this unity over time. Likewise, they might be detrimental to interests sensitive to the continued chain of human generations. Notwithstanding these risks, there are strong reasons in favour of attempting to improve moral dispositions; it could significantly decrease a wide range of extreme risks that arise from our moral failings (for example, nuclear war from lack of global co-operation). Appealing to a form of virtue theory as a guiding framework is likely to avoid these risks and to address other concerns expressed in the literature. If we apply such a framework, technological interventions aimed at improving fundamental moral dispositions are extremely desirable.
Seismic design and evaluation of moment resisting frames using elastomeric dampers
Keywords: Real Time Substructure Test
seismic retrofit
Elastomeric dampers
passive diisipation devices
Generalized Maxwell Model

This study evaluates the characteristics of elastomeric dampers, and assesses their eectiveness in mitigating the eects of dynamic loading. As part of this evaluation a series of characterization tests were carried out in order to extract the main mechanical properties of the elastomer material in a range of strain amplitudes, loading frequencies, and ambient temperatures, since it has been proved that elastomeric materials depend on these parameters. It was found that strain amplitude was the most dominant factor not only regarding the values of their mechanical properties (shear storage modulus, and loss factor) but also with regard to the shape of the hysteresis loops. At the same time frequency was shown to have only a minor eect on their behaviour.
Based on the Generalised Maxwell Model, a new hysteretic model was developed and proposed in this thesis which is able to capture the behaviour of the material. As part of this model an equation was derived which describes the force-displacement relationship of the Generalised Maxwell Model for N Maxwell elements in time domain, and formed the basis for the proposed model.
The seismic performance of a 10 storey steel moment resisting frame was evaluated, and the eect of the dampers on the frame's performance was examined. The dampers were designed to provide an additional 10% damping to the Eurocode 8 compliant building. The structure was tested with and without dampers for two dierent levels of earthquake intensity. It was shown that the elastomeric dampers led to signicant decrease of displacements, accelerations, base shear forces, and permanent damage of the structure, even after ground motions scaled to the Maximum Considered Earthquake level.
Lastly, Real Time Substructure tests were performed in order to further validate the proposed hysteretic model. Both SDOF and MDOF systems equipped with elastomeric dampers were tested under scaled version of the ElCentro ground motion and the corresponding force-displacement relationship of the dampers was compared with the analytical model. The results showed that the proposed model is able to capture the dynamic performance of the dampers under realistic earthquake conditions.
‘What if a spirit or an angel has spoken?’ Narrative modelling of the treatment of dreams and visions in the Acts of the Apostles
Keywords: Religious Experience
Ambiguity
Authority
Narrative Criticism
Acts of the Apostles
Dreams and Visions

The reports of dreams and visions in the Book of Acts are widely accepted to portray moments of divine-human communication that demonstrate God’s continuing involvement in the life of His church. However, within the narrative there are inconsistencies between repeated reports of visionary experience (e.g. Acts 9, 22, 26), cases of prophecy being ignored (e.g. Acts 21:10-14), mixed responses to dream-visions (e.g. Acts 2, 10, 11, 15, 22), and nuances that suggest more is going on in the text than what would be required simply to show God’s hand at work.
This thesis will analyse the dream-vision reports within the Acts of the Apostles, assessing the extent to which they reflect wider first century attitudes towards dreaming, and their function within the narrative itself. It will be argued that at both of these levels of enquiry, the reports of dreams and visions demonstrate an awareness of the challenges that these phenomena pose for individuals and communities. This is reflected not only in the struggle to appropriately interpret dreams and visions, but also in the recognition of the potential risks posed by these phenomena. Indeed, it will be suggested that the inherent ambiguity and uncertainty that surrounds dreams and visions is something that is heightened rather than diminished within the upside-down world of the Acts of the Apostles. It will be argued that one finds a movement from the idealised representation of dreams and visions in the account of the first Christian Pentecost, to its more complex practical outworking. Through engagement with this story the reader/hearer is offered a means of understanding how dreams and vision might be treated, mutatis mutandis, within the context of their own community.