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Artykuły w czasopismach na temat "Matter phases classification"
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Schakel, A. M. J., i F. A. Bais. "A symmetry classification of superfluid3He phases". Journal of Physics: Condensed Matter 1, nr 9 (6.03.1989): 1743–52. http://dx.doi.org/10.1088/0953-8984/1/9/017.
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Thiang, Guo Chuan. "On the K-Theoretic Classification of Topological Phases of Matter". Annales Henri Poincaré 17, nr 4 (28.05.2015): 757–94. http://dx.doi.org/10.1007/s00023-015-0418-9.
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Elben, Andreas, Jinlong Yu, Guanyu Zhu, Mohammad Hafezi, Frank Pollmann, Peter Zoller i Benoît Vermersch. "Many-body topological invariants from randomized measurements in synthetic quantum matter". Science Advances 6, nr 15 (kwiecień 2020): eaaz3666. http://dx.doi.org/10.1126/sciadv.aaz3666.
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Many-body topological invariants, as quantized highly nonlocal correlators of the many-body wave function, are at the heart of the theoretical description of many-body topological quantum phases, including symmetry-protected and symmetry-enriched topological phases. Here, we propose and analyze a universal toolbox of measurement protocols to reveal many-body topological invariants of phases with global symmetries, which can be implemented in state-of-the-art experiments with synthetic quantum systems, such as Rydberg atoms, trapped ions, and superconducting circuits. The protocol is based on extracting the many-body topological invariants from statistical correlations of randomized measurements, implemented with local random unitary operations followed by site-resolved projective measurements. We illustrate the technique and its application in the context of the complete classification of bosonic symmetry-protected topological phases in one dimension, considering in particular the extended Su-Schrieffer-Heeger spin model, as realized with Rydberg tweezer arrays.
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Hernandes, V. F., M. S. Marques i José Rafael Bordin. "Phase classification using neural networks: application to supercooled, polymorphic core-softened mixtures". Journal of Physics: Condensed Matter 34, nr 2 (28.10.2021): 024002. http://dx.doi.org/10.1088/1361-648x/ac2f0f.
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Abstract Characterization of phases of soft matter systems is a challenge faced in many physical chemical problems. For polymorphic fluids it is an even greater challenge. Specifically, glass forming fluids, as water, can have, besides solid polymorphism, more than one liquid and glassy phases, and even a liquid–liquid critical point. In this sense, we apply a neural network algorithm to analyze the phase behavior of a mixture of core-softened fluids that interact through the continuous-shouldered well (CSW) potential, which have liquid polymorphism and liquid–liquid critical points, similar to water. We also apply the neural network to mixtures of CSW fluids and core-softened alcohols models. We combine and expand methods based on bond-orientational order parameters to study mixtures, applied to mixtures of hardcore fluids and to supercooled water, to include longer range coordination shells. With this, the trained neural network was able to properly predict the crystalline solid phases, the fluid phases and the amorphous phase for the pure CSW and CSW-alcohols mixtures with high efficiency. More than this, information about the phase populations, obtained from the network approach, can help verify if the phase transition is continuous or discontinuous, and also to interpret how the metastable amorphous region spreads along the stable high density fluid phase. These findings help to understand the behavior of supercooled polymorphic fluids and extend the comprehension of how amphiphilic solutes affect the phases behavior.
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FARAGGI, ALON E. "TOWARD CLASSIFICATION OF THE REALISTIC FREE-FERMIONIC SUPERSTRING MODELS". International Journal of Modern Physics A 14, nr 11 (30.04.1999): 1663–702. http://dx.doi.org/10.1142/s0217751x99000841.
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The realistic free-fermionic models have had remarkable success in providing plausible explanations for various properties of the Standard Model, which include the natural appearance of three generations, the explanation of the heavy top quark mass and the qualitative structure of the fermion mass spectrum in general, the stability of the proton, and more. These intriguing achievements make evident the need to understand the general space of these models. While the number of possibilities is large, general patterns can be extracted. In this paper I present a detailed discussion on the construction of the realistic free-fermionic models with the aim of providing some insight into the basic structures and building blocks that enter the construction. The role of free phases in the determination of the phenomenology of the models is discussed in detail. I discuss the connection between the free phases and mirror symmetry in (2,2) models and the corresponding symmetries in the case of (2,0) models. The importance of the free phases in determining the effective low energy phenomenology is illustrated in several examples. The classification of the models in terms of boundary condition selection rules, real world-sheet fermion pairings, exotic matter states and the hidden sector is discussed.
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Benalcazar, Wladimir A., B. Andrei Bernevig i Taylor L. Hughes. "Quantized electric multipole insulators". Science 357, nr 6346 (6.07.2017): 61–66. http://dx.doi.org/10.1126/science.aah6442.
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The Berry phase provides a modern formulation of electric polarization in crystals. We extend this concept to higher electric multipole moments and determine the necessary conditions and minimal models for which the quadrupole and octupole moments are topologically quantized electromagnetic observables. Such systems exhibit gapped boundaries that are themselves lower-dimensional topological phases. Furthermore, they host topologically protected corner states carrying fractional charge, exhibiting fractionalization at the boundary of the boundary. To characterize these insulating phases of matter, we introduce a paradigm in which “nested” Wilson loops give rise to topological invariants that have been overlooked. We propose three realistic experimental implementations of this topological behavior that can be immediately tested. Our work opens a venue for the expansion of the classification of topological phases of matter.
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Chan, Amos, i Thorsten B. Wahl. "Classification of symmetry-protected topological many-body localized phases in one dimension". Journal of Physics: Condensed Matter 32, nr 30 (1.05.2020): 305601. http://dx.doi.org/10.1088/1361-648x/ab7f01.
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Wunderlich, B. "A classification of molecules, phases, and transitions as recognized by thermal analysis". Thermochimica Acta 340-341 (grudzień 1999): 37–52. http://dx.doi.org/10.1016/s0040-6031(99)00252-x.
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Salcedo-Gallo, J. S., C. C. Galindo-González i E. Restrepo-Parra. "Deep learning approach for image classification of magnetic phases in chiral magnets". Journal of Magnetism and Magnetic Materials 501 (maj 2020): 166482. http://dx.doi.org/10.1016/j.jmmm.2020.166482.
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Cedzich, C., T. Geib, F. A. Grünbaum, L. Velázquez, A. H. Werner i R. F. Werner. "Quantum Walks: Schur Functions Meet Symmetry Protected Topological Phases". Communications in Mathematical Physics 389, nr 1 (29.12.2021): 31–74. http://dx.doi.org/10.1007/s00220-021-04284-8.
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AbstractThis paper uncovers and exploits a link between a central object in harmonic analysis, the so-called Schur functions, and the very hot topic of symmetry protected topological phases of quantum matter. This connection is found in the setting of quantum walks, i.e. quantum analogs of classical random walks. We prove that topological indices classifying symmetry protected topological phases of quantum walks are encoded by matrix Schur functions built out of the walk. This main result of the paper reduces the calculation of these topological indices to a linear algebra problem: calculating symmetry indices of finite-dimensional unitaries obtained by evaluating such matrix Schur functions at the symmetry protected points $$\pm 1$$ ± 1 . The Schur representation fully covers the complete set of symmetry indices for 1D quantum walks with a group of symmetries realizing any of the symmetry types of the tenfold way. The main advantage of the Schur approach is its validity in the absence of translation invariance, which allows us to go beyond standard Fourier methods, leading to the complete classification of non-translation invariant phases for typical examples.
Rozprawy doktorskie na temat "Matter phases classification"
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Riesch, Christian. "Non-equilibrium dynamics in ordered modulated phases". Doctoral thesis, Universitätsbibliothek Chemnitz, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-172821.
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In der vorliegenden Arbeit wird die Dynamik geordneter modulierter Phasen außerhalb des thermischen Gleichgewichts untersucht. Der Schwerpunkt liegt auf einem zweidimensionalen, streifenbildenden System, genannt Modell B mit Coulomb-Wechselwirkung, welches aus einem geordneten Anfangszustand unter dem Einfluß eines Rauschterms relaxiert. Aus den mittels numerischer Simulationen gewonnenen Daten wird die lokale Orientierung der Streifen extrahiert und deren raum-zeitliche Korrelationsfunktionen berechnet. Wir beobachten eine langsame Dynamik und Alterungseffekte in der Zwei-Zeit-Autokorrelationsfunktion, welche einer Skalenform folgt, die aus kritischen Systemen bekannt ist. Dies geht einher mit dem Wachstum einer räumlichen Korrelationslänge senkrecht zu den Streifen. Zu sehr späten Zeiten klingt die zugehörige räumliche Korrelationsfunktion mit einem Potenzgesetz ab. Weiterhin wird der Einfluß der Systemgröße und verschiedener Seitenverhältnisse auf die Dynamik des Orientierungsfeldes studiert, wobei ein Wachstumsprozeß parallel zur Ausrichtung der Streifen identifiziert wird. Es zeigt sich, daß dieser Prozeß für die Nichtgleichgewichtsdynamik entscheidend ist. Zwei weitere Modelle für modulierte Phasen werden in ähnlicher Weise untersucht. Die Swift-Hohenberg-Gleichung in der Variante mit erhaltenem sowie nicht erhaltenem Ordnungsparameter zeigt ebenfalls Alterungseffekte in der Dynamik der Streifenorientierung. In einem System, welches zweidimensionale hexagonale Muster bildet, werden Alterungseffekte in der Autokorrelationsfunktion der Verschiebung beobachtet. Jedoch sättigt die zugehörige räumliche Korrelationslänge bei einem endlichen Wert, was auf eine Unterbrechung der Alterung hindeutet.
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Schmiedt, Jacob. "Interplay of magnetic, orthorhombic, and superconducting phase transitions in iron-based superconductors". Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-154434.
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The physics of iron pnictides has been the subject of intense research for half a decade since the discovery of superconductivity in doped LaFeAsO in 2008. By now there exists a large number of different materials that are summarized under the term "pnictides'' with significant differences in their crystal structure, electronic properties, and their phase diagrams. This thesis is concerned with the investigation of the various phase transitions that are observed in the underdoped compounds of the pnictide subgroups RFeAsO, where R is a rare-earth element, and AFe_2As_2, where A is an alkaline-earth element. These compounds display two closely bound transitions from a tetragonal to an orthorhombic phase and from a paramagnetic to an antiferromagnetic metal. Both symmetry-broken phases are suppressed by doping or pressure and close to their disappearance superconductivity sets in. The superconducting state is stabilized until some optimal doping or pressure is reached and gets suppressed thereafter. The central goal of this thesis is to improve our understanding of the interplay between these three phases and to describe the various phase transitions. We start from an itinerant picture that explains the magnetism as a result of an excitonic instability and show how the other phases can be included into this picture. This approach is based on the the observation that the compounds we are interested in have a Fermi surface with multiple nested electron and hole pockets and that they have small to intermediate interaction strengths.
The thesis starts with a study of the doping dependence of the antiferromagnetic phase transition in four different five-orbital models. We use the random-phase approximation to determine the transition temperature, the dominant ordering vector, and the contribution of the different orbitals to the ordering. This allows us to identify the more realistic models, which give results that are in good agreement with experimental observations. In addition to the frequently made assumption of orbital-independent interaction potentials we study the effect of a reduction of the interaction strengths that involve the d_{xy} orbital. We find that this tunes the system between two different nesting instabilities. A reduction of the interactions that involve the d_{xy} orbital also enhances the tendency towards incommensurate (IC) order. For a weak reduction this tendency is compensated by the presence of the orthorhombic phase. However, for a reduction of 30%, as it is suggested by constrained random-phase-approximation calculations, we always find large doping ranges, where a state with IC order has the highest transition temperature.
We continue the investigation of the magnetic phase transition by studying the competition of different possible types of antiferromagnetic order that arises from the presence of two degenerate nesting instabilities with the ordering vectors (pi,0) and (0,pi). We derive a Ginzburg-Landau free energy from a microscopic two-band model and find that the presence of the experimentally observed stripe phase strongly depends on the number and size of the hole pockets in the system and on the doping. We show that within the picture of a purely magnetically driven nematic phase transition, which breaks the C_4 symmetry and induces the orthorhombic distortion, the nematic phase displays exactly the same dependence on the model parameters as the magnetic stripe phase. We propose that in addition to the purely magnetically driven nematic instability there is a ferro-orbital instability in the system that stabilizes the nematic transition and, thus, explains the experimentally observed robustness of the orthorhombic transition. We argue that including a ferro-orbital instability into the picture may also be necessary to reproduce the transition from simultaneous first-order transitions into an orthorhombic antiferromagnetic state to two separate second-order transitions, which is observed as a function of doping.
Finally, a study of the superconducting phase transition inside the antiferromagnetic phase that is observed in some pnictide compounds is presented. We present an approach to calculate the fluctuation-mediated pairing interaction in the spin-density-wave phase of a multiband system, which is based on the random-phase approximation. This approach is applied to a minimal two-band model for the pnictides to study the effect of the various symmetry-allowed bare on-site interactions on the gap symmetry and structure. We find a competition between various even- and odd-parity states and over a limited parameter range a p_x-wave state is the dominant instability. The largest part of the parameter space is dominated by even parity states but the gap structure sensitively depends on the bare interactions. We propose that the experimentally observed transition from a nodeless to a nodal gap can be due to changes in the on-site interaction potentials.
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Wang, Zitao. "Topological Phases of Matter: Exactly Solvable Models and Classification". Thesis, 2019. https://thesis.library.caltech.edu/11488/14/Wang_Zitao_2019.pdf.
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In this thesis, we study gapped topological phases of matter in systems with strong inter-particle interaction. They are challenging to analyze theoretically, because interaction not only gives rise to a plethora of phases that are otherwise absent, but also renders methods used to analyze non-interacting systems inadequate. By now, people have had a relatively systematic understanding of topological orders in two spatial dimensions. However, less is known about the higher dimensional cases. In Chapter 2, we will explore three dimensional long-range entangled topological orders in the framework of Walker-Wang models, which are a class of exactly solvable models for three-dimensional topological phases that are not known previously to be able to capture these phases. We find that they can represent a class of twisted discrete gauge theories, which were discovered using a different formalism. Meanwhile, a systematic theory of bosonic symmetry protected topological (SPT) phases in all spatial dimensions have been developed based on group cohomology. A generalization of the theory to group supercohomology has been proposed to classify and characterize fermionic SPT phases in all dimensions. However, it can only handle cases where the symmetry group of the system is a product of discrete unitary symmetries. Furthermore, the classification is known to be incomplete for certain symmetries. In Chapter 3, we will construct an exactly solvable model for the two-dimensional time-reversal-invariant topological superconductors, which could be valuable as a first attempt to a systematic understanding of strongly interacting fermionic SPT phases with anti-unitary symmetries in terms of exactly solvable models. In Chapter 4, we will propose an alternative classification of fermionic SPT phases using the spin cobordism theory, which hopefully can capture all the phases missing in the supercohomology classification. We test this proposal in the case of fermionic SPT phases with Z2 symmetry, where Z2 is either time-reversal or an internal symmetry. We find that cobordism classification correctly describes all known fermionic SPT phases in space dimensions less than or equal to 3.
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Roy, Sthitadhi. "Nonequilibrium and semiclassical dynamics in topological phases of quantum matter". 2017. https://monarch.qucosa.de/id/qucosa%3A32068.
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The discovery of topological phases of quantum matter has brought about a new paradigm in the understanding of rich and exotic phases which fall outside the conventional classification of phases using Landau’s theory of broken symmetries. The thesis addresses various aspects of nonequilibrium and semiclassical dynamics in systems hosting such topological phases. While the study of nonequilibrium closed quantum systems is an exciting field in itself, it has gained a lot of importance in the context topological systems. Much of this has been fuelled by the immense progress in the experimental realisation of such topological systems with ultracold atoms in optical lattices. As measurements of real-time responses are natural in such experiments, they have served as ideal platforms to study the nonequilibrium responses of topological systems.
The studies presented in this thesis can be brought under the umbrella of two broad questions, first, how non-equilibrium dynamics can be used to characterize topological phases or locate topological critical points, and second, what new topological phases can be realized out of equilibrium.
Generally, non-trivial topology of a system manifests itself via quantised responses at the edges of a system or via appropriate non-local string order parameters which are rather difficult to measure in experiments. Local measurements in the bulk are more conducive to experiments. We address this question by showing that within a non-equilibrium setup obtained via a quantum quench, local bulk observables can show sharp signatures of topological quantum criticality via a non-analyticity in parameter space at the critical point. Although via non-local basis transformations, topological phase transitions can often be mapped onto conventional phase transitions, a remarkable aspect of this result is that within the non-equilibrium setup, the local bulk observables can locate the critical point in the natural basis where the phase transition is topological and not described by a local order parameter.
The next question that the thesis explores is how nonequilibrium and semiclassical dynamics, more precisely wavepacket dynamics, can be used to probe topological phases with an emphasis on Chern insulators in two dimensions. Chern insulators are essentially similar to quantum Hall systems except that they show quantised Hall responses in the absence of external magnetic fields due to intrinsically broken time-reversal symmetry. The Hall conductance in these systems is related to an integer-valued topological invariant characterising the energy bands, known as the Chern number, which is the net flux of Berry curvature through the entire two-dimensional Brillouin zone. The Berry curvature modifies the semiclassical equations of motion describing the dynamics of a wavepacket. Hence, the real-time motion of a wavepacket is used to map out the Berry curvature and thence the topology of the band. Complementary to these bulk responses, spatially local quenches in Chern insulators are also shown as probes for the presence or absence of chiral edge modes.
The idea of semiclassical equations of motion can be extended to the case of a three-dimensional Weyl semimetal. Weyl semimetals are a new class of gapless topological systems in three dimensions, elementary fermionic excitations of which are described by the Weyl equation. Since in cold atom experiments, magnetic fields are realized synthetically via phases in complex hoppings, exploring the Hofstadter limit is a natural scenario. When the magnetic field penetrating a two-dimensional system becomes so large that the associated magnetic length becomes comparable to the lattice spacing, the energy spectrum of the system is described by fractal known as the Hofstadter butterfly. We introduce the Weyl butterfly, a set of fractals which describes the spectrum of a Weyl semimetal subjected to a magnetic field, and we characterize the fractal set of Weyl nodes in the spectrum using wavepacket dynamics to reveal their chirality and location. Moreover, we show that the chiral anomaly -- a hallmark of the topological Weyl semimetal -- does not remain proportional to the magnetic field at large fields, but rather inherits a fractal structure of linear regimes as a function of external field.
Finally, the thesis addresses the question of novel nonequilibrium topological phases of matter. In the context of phase structures of nonequilibrium systems, periodically driven, also known as Floquet systems, has received a lot of attention. Moreover, the role of disorder has been shown to be rather crucial as generically such Floquet systems heat up to featureless infinite temperature states. Also, in the context of topological systems like Chern insulators, disorder is expected to play an interesting role given that it is important in localising the bulk cyclotron orbits in an integer quantum Hall system. With this motivation, the phase diagram of the disordered Chern insulator with a Floquet drive is explored in the thesis. In the model considered there are indeed topological Floquet edge modes which are exclusive to Floquet systems, for instance, the edge modes in gaps of the quasienergy spectrum around ±pi. There are also disorder-induced topological transitions between different Floquet topological phases, due to a mechanism shown to be of levitation-annihilation type.
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You, Minyoung. "Topological Phases of Matter: Classification, Stacking Law, and Relation to Topological Quantum Field Theory". Thesis, 2020. https://thesis.library.caltech.edu/13859/1/Caltech_Thesis_Minyoung_You.pdf.
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We study aspects of gapped phases of matter, focusing on their classification, including the group law under stacking, and their relation to topological quantum field theories (TQFT). In one spatial dimension, it is well-known that Matrix Product States (MPS) efficiently approximate ground states of gapped systems; by showing that these states arise naturally in 1 + 1-dimensional lattice TQFT, which in turn are closely related to continuum TQFT, we provide a concrete connection between ground states of lattice systems and TQFT in 1 + 1 dimensions. We generalize this to systems with symmetries and fermions, and obtain a classification and group law for the stacking of 1 + 1-dimensional symmetry-protected topological phases. Further, we study the effect of turning on/off interactions for the classification: the phase classification of a given symmetry class of Hamiltonians can be different depending on whether we allow interactions or not, and in low dimensions we provide some concrete formulas relating the phases under the non-interacting classification and those under the interacting classification. Lastly, we study the phases of the 2 + 1-dimensional topological superconductor, and show that for all 16 phases braiding statistics of vortices, which determine the underlying TQFT, can be obtained by stacking layers of the basic p + ip superconductor.
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Gupta, Gaurav Kumar. "Interplay of Interaction and Topology From Topological Band Theory to Topological Field Theory". Thesis, 2018. https://etd.iisc.ac.in/handle/2005/4892.
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Classification of phases of matter has long been a central point of interest in the research community in condensed matter physics. Over the past several decades mainly two kinds of classification schemes have emerged, namely, one related to spontaneous symmetry breaking and the other to symmetry invariant topological classification. Although the latter one is fairly new, a lot of progress has been made over the past couple of decades, but still these two classification schemes are generally treated separately. In this thesis, I discuss systems where both the classification schemes need to be invoked due to the interplay of interaction and topology and their effect on each other.
In the first piece of work, I present the theory of a new type of topological quantum order which is driven by the spin-orbit density wave order parameter and distinguished by Z2 topological invariant. The resulting quantum order parameters break translational symmetry but preserve time-reversal symmetry. Consequently, the system is inherently associated with a Z2 topological invariant along each density wave propagation direction which makes it a weak topological insulator in two dimensions, with an even number of spin-polarized boundary states.
In the second work, I discuss the effect of the parent topological ground state on the local order. In particular, I focus on a well-studied (experimentally) material TlCuCl3 and show that it has unique unexplored topological properties which arise when a time-reversal breaking antiferromagnetic order parameter sets into the system and how they can explain the uncanny properties of this material such as unconventional paramagnon lifetime, finite Higgs mass across the phase transition, among other.
In the last work, I discuss our attempt to confirm the presence of bosonic integer and fractional quantum hall effect in an interacting lattice model. The model consists of bosons spread over the honeycomb lattice with the nearest neighbour and next nearest correlated hopping with flux per hexagon. I provide evidence for the presence of integer as well as fractional quantum Hall states and also a superfluid state, for different fillings and tuning parameters. I have used mean-field theory and path integral methods as the theoretical tools to study the above problems. Furthermore, I have also used numerical methods such as Density Functional Theory (DFT, as implemented in VASP) and exact diagonalization (using Lanczos algorithm) where appropriate. As I have shown in the thesis, a large number of interesting results emerge from these studies, leading to a better understanding of the problems and uncovering some interesting underlying physics.
Overall, this thesis brings forth some notable and interesting possibilities in understanding the physics of topological state of mater. An idea that stands out is that effect of topological phase onto the symmetry breaking phase and vice-versa. This will have an important impact on the future studies in the related area and to find a unified theory of phase transitions which incorporate both symmetry breaking and topological transition together along with more sophisticated like inclusion of Gaussian fluctuations on the top of the mean-field.
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Alaimo, Francesco. "Phase Field Crystal Modeling of Active Matter". 2018. https://tud.qucosa.de/id/qucosa%3A32687.
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Active matter describes systems that convert energy from their environment into directed motion. Therefore, these systems are in intrinsic nonequilibrium, unlike their passive counterparts. From a theoretical point of view, such active systems have been modeled by agent-based models, as well as hydrodynamic approaches, which allowed for the investigation of a wide range of observed collective phenomena characterizing active matter. In this thesis we develop a microscopic field-theoretical approach to describe generic properties of active systems. This description combines the phase field crystal model with a polar order parameter and a self-propulsion term. First, we validate this approach by reproducing results obtained with corresponding agent-based models, such as binary collisions, collective migration and vortex formation. We also perform a direct comparison between our model and a microscopic phase field description of active matter. Next, we use this continuum approach to simulate some larger active systems and to analyze the coarsening process in active crystals, as well as the mechanisms leading to mobile clusters. We show the generality of our approach by extending it to binary mixtures of interacting active and passive particles. Also in this case, we first validate the model by reproducing known results, such as enhanced crystallization via active doping and the suppression of collective migration in an active bath in the presence of fixed obstacles. Interestingly, for the regime of mobile passive particles in an active bath a laning state is found, which is characterized by an alignment of the active particles that is globally nematic, but polar within each lane. This state represents a theoretical prediction feasible to be validated experimentally. Finally, we explore the field of topological active matter. We develop an agent-based model to describe self-propelled particles on curved surfaces and study the complex spatiotemporal patterns that emerge.Aktive Materie beschreibt Systeme, die Energie aus ihrer Umgebung in gerichtete bewegung umwandeln. Im Gegensatz zur passiven Materie befinden sich diese Systeme nie im physikalischen Gleichgewicht und offenbaren dadurch interessante physikalische Phänomene. Vom theoretischen Standpunkt her wurde aktive Materie bereits simuliert, typischerweise durch agenten-basierte Modelle oder hydrodynamische Ansätze, die es ermöglichen eine Vielzahl der auftretenden kollektiven Bewegungsprinzipien zu untersuchen. In dieser Doktorarbeit entwickeln wir einen mikroskopischen Kontinuumsansatz um die generischen Eigenschaften von aktiven Systemen zu untersuchen. Unsere Beschreibung kombiniert das Phasenfeld-Kristall Modell mit einem polaren Ordnungsparameter und einem Antriebsterm. Zuerst validieren wir den Ansatz durch Reproduktion bekannter Ergebnisse agenten-basierter Modelle, wie binäre Kollisionen, kollektive Bewegung und Wirbelformationen. Des Weiteren führen wir einen direkten Vergleich zwischen unserem Modell und einer mikroskopischen Phasenfeldbeschreibung aktiver Materie durch. Danach nutzen wir den kontinuierlichen Ansatz um große aktive Systeme zu simulieren und analysieren den Vergröberungsprozess in aktiven Kristallen und Mechanismen der mobilen Aggregatbildung. Wir illustrieren die Allgemeingültigkeit unseres Simulationsansatzes durch die Erweiterung auf binäre Systeme, in denen sowohl aktive als auch passive Partikel enthalten sind. Auch in diesem Fall validieren wir das Modell durch Vergleiche mit bekannten Resultaten, wie zum Beispiel die verstärkte Kristallisation durch aktives Doping oder die Unterdrückung kollektiver Bewegung durch die Einführung von Hindernissen in einem aktiven Bad. Interessanterweise finden wir bei der Präsenz mobiler passiver Partikel in einem aktiven Bad einen Fahrspur-Zustand, in welchem die aktiven Partikel nematische Fahrspuren bilden und sich nur jeweils innerhalb einer Fahrspur nematisch polar anordnen. Dieser bisher unbekannte Zustand stellt eine theoretische Vorhersage dar, die experimentell geprüft werden kann. Schließlich begeben wir uns auf das Gebiet der topologischen aktiven Materie. Wir entwickeln ein agenten-basiertes Modell um selbst-angetriebene Partikel auf gekrümmten Oberflächen zu beschreiben und untersuchen die dabei auftretenden zeitlich und räumlich komplexen Muster.%, die dabei auftreten.
Książki na temat "Matter phases classification"
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Keil, Geert, Lara Keuck i Rico Hauswald, red. Vagueness in Psychiatry. Oxford University Press, 2016. http://dx.doi.org/10.1093/med/9780198722373.001.0001.
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Blurred boundaries between the normal and the pathological are a recurrent theme in almost every publication concerned with the classification of mental disorders. However, systematic approaches that take into account the philosophical discussions about vagueness are rare. This is the first volume to systematically draw various lines of philosophical and psychiatric inquiry together–including the debates about categorial versus dimensional approaches in current psychiatric classification systems, the principles of psychiatric classification, the problem of prodromal phases and subthreshold disorders, and the problem of overdiagnosis in psychiatry–and to explore the connections of these debates to philosophical discussions about vagueness. The book consists of an introduction (Part I) followed by three parts. Part II encompasses historical and recent philosophical positions regarding the nature of demarcation problems in nosology. Here the authors discuss the pros and cons of gradualist approaches to health and disease and the relevance of philosophical discussions of vagueness to these debates. Part III narrows the focus to psychiatric nosology. The authors approach the vagueness of psychiatric classification by drawing on contentious medical categories, such as PTSD or schizophrenia, and on the dilemmas of day-to-day diagnostic and therapeutic practice. Against this background, the chapters critically evaluate how current revisions of the ICD classifications and DSM manuals conceptualize mental disorders and how they are applied in various contexts. Part IV is concerned with social, moral, and legal implications that arise when being mentally ill is a matter of degree. Not surprisingly, the law is ill-equipped to deal with these challenges due to its binary logic. Still, the authors show that there are more and less reasonable ways of dealing with blurred boundaries and of arriving at warranted decisions in hard cases.
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Janssen, Ted, Gervais Chapuis i Marc de Boissieu. Description and symmetry of aperiodic crystals. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198824442.003.0002.
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This chapter first introduces the mathematical concept of aperiodic and quasiperiodic functions, which will form the theoretical basis of the superspace description of the new recently discovered forms of matter. They are divided in three groups, namely modulated phases, composites, and quasicrystals. It is shown how the atomic structures and their symmetry can be characterized and described by the new concept. The classification of superspace groups is introduced along with some examples. For quasicrystals, the notion of approximants is also introduced for a better understanding of their structures. Finally, alternatives for the descriptions of the new materials are presented along with scaling symmetries. Magnetic systems and time-reversal symmetry are also introduced.
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Compston, Alastair. Multiple sclerosis and other demyelinating diseases. Oxford University Press, 2011. http://dx.doi.org/10.1093/med/9780198569381.003.0871.
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The oligodendrocyte–myelin unit subserves saltatory conduction of the nerve impulse in the healthy central nervous system. At one time, many disease processes were thought exclusively to target the structure and function of myelin. Therefore, they were designated ‘demyelinating diseases’. But recent analyses, based mainly on pathological and imaging studies, (re)emphasize that axons are also directly involved in these disorders during both the acute and chronic phases. Another ambiguity is the extent to which these are inflammatory conditions. Here, distinctions should be made between inflammation, as a generic process, and autoimmunity in which rather a specific set of aetiological and mechanistic conditions pertain. And there are differences between disorders that are driven primarily by immune processes and those in which inflammation occurs in response to pre-existing tissue damage.With these provisos, the pathological processes of demyelination and associated axonal dysfunction often account for episodic neurological symptoms and signs referable to white matter tracts of the brain, optic nerves, or spinal cord when these occur in young people. This is the clinical context in which the possibility of ‘demyelinating disease’ is usually considered by physicians and, increasingly, the informed patient. Neurologists will, with appropriate cautions, also be prepared to diagnose demyelinating disease in older patients presenting with progressive symptoms implicating these same pathways even when there is no suggestive past history. Both in its typical and atypical forms multiple sclerosis remains by far the commonest demyelinating disease. But acute disseminated encephalomyelitis, the leucodystrophies, and central pontine myelinolysis also need to be considered in particular circumstances; and multiple sclerosis itself has a differential diagnosis in which the relapsing-remitting course is mimicked by conditions not associated with direct injury to the axon–glial unit. Since our understanding of the cause, pathogenesis and features of demyelinating disease remains incomplete, classification combines aspects of the aetiology, clinical features, pathology, and laboratory components. Whether the designation ‘multiple sclerosis’ encapsulates one or more conditions is now much debated. We anticipate that a major part of future studies in demyelinating disease will be further to resolve this question of disease heterogeneity leading to a new taxonomy based on mechanisms rather than clinical empiricism. But, for now, the variable ages of onset, unpredictable clinical course, protean clinical manifestations, and non-specific laboratory investigations continue to make demyelinating disease one of the more challenging diagnostic areas in clinical neurology.
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Giacovazzo, Carmelo. Phasing in Crystallography. Oxford University Press, 2013. http://dx.doi.org/10.1093/oso/9780199686995.001.0001.
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Modern crystallographic methods originate from the synergy of two main research streams, the small-molecule and the macro-molecular streams. The first stream was able to definitively solve the phase problem for molecules up to 200 atoms in the asymmetric unit. The achievements obtained by the macromolecular stream are also impressive. A huge number of protein structures have been deposited in the Protein Data Bank. The solution of them is no longer reserved to an elite group of scientists, but may be attained in a large number of laboratories around the world, even by young scientists. New probabilistic approaches have been tailored to deal with larger structures, errors in the experimental data, and modest data resolution. Traditional phasing techniques like ab initio, molecular replacement, isomorphous replacement, and anomalous dispersion techniques have been revisited. The new approaches have been implemented in robust phasing programs, which have been organized in automatic pipelines usable even by non-experts. Protein structures, which 50 years ago could take months or even years to solve, can now be solved in a matter of hours, partly also due to technological advances in computer science. This book describes all modern crystallographic phasing methods, and introduces a new rational classification of them. A didactic approach is used, with the techniques described simply and logically in the main text, and further mathematical details confined to the Appendices for motivated readers. Numerous figures and applicative details illustrate the text.
Części książek na temat "Matter phases classification"
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"Phase States of Matter, Their Classification". W Thermodynamics and Equations of State for Matter, 7–47. WORLD SCIENTIFIC, 2016. http://dx.doi.org/10.1142/9789814749206_0002.
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Adriana, REYES-NAVA, SANCHEZ-FLORES Diego, LÓPEZ-GONZÁLEZ Erika i ANTONIO-VELAZQUEZ Juan Alberto. "Classification of mature corn cobs using Convolutional Neural Networks". W Handbook Science of Technology and Innovation, 16–31. ECORFAN, 2022. http://dx.doi.org/10.35429/h.2022.3.16.31.
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The aim of this study is to analyze an algorithm capable of classifying mature corn cobs for the detection of diseases, including Aspergillus, Gibberella and Fusarium fungi, in addition to the common charcoal that these elements may have. The process was carried out through a Convolutional Neural Network associated to a classification algorithm, based on deep learning techniques using MobileNet. This work is divided into two phases, the first one is to determine the performance of the algorithm for a small sample of images and videos analysis and the second one is the extension of the data corpus for the automatic analysis of new samples. It is necessary to mention that this work focuses on the development of the first phase, in which the identification and classification of the cob has had promising results.
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West-Eberhard, Mary Jane. "Heterochrony". W Developmental Plasticity and Evolution. Oxford University Press, 2003. http://dx.doi.org/10.1093/oso/9780195122343.003.0019.
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Heterochrony is evolutionary change in the timing of expression of a phenotype trait, that transfers expression of the trait from one life stage or behavioral or physiological phase to another—”the shifting of characters from one part of an ontogeny to another” (Valentine, 1977b, p. 260) or simply “the displacement of characters in time” (Gould, 1977, p. 225). A clear fossil example occurs in monograptids, where there is a temporal shift in the onset of a modified morphology, a life-history modification that is recorded in the structure of the body (figure 13.1). Heterochrony can occur at any level of organization, including the molecular level, where evolutionary changes in the timing of gene expression have been demonstrated, for example, in echinoids and a fibronectin gene of amphibians (Collazo, 1994). Some recent authors (e.g., McKinney and McNamara, 1991; Reilly et al., 1997) define heterochrony as any change in the timing of regulatory events. Most novel traits qualify as heterochrony by this regulatory-timing definition, since virtually all evolutionary change involves change in the timing of developmental events. This regulatorytiming definition of heterochrony leads to a classification of evolutionary change termed panheterochrony by McKinney and McNamara (1991)—a classification of evolutionary transitions that lumps all evolutionary change under the heading of heterochrony. “Because all developmental events occur along a time line, any significant change is likely to result in a heterochrony at some level” (Raff, 1992, p. 211). As expressed by Barbara McClintock in a staff meeting at Cold Spring Harbor Laboratories, “If I could control the time of gene action, I could cause a fertilized snail egg to develop into an elephant. Their biochemistries are not all that different; it's simply a matter of timing”. I will adhere to a classification that divides the effects of regulatory change into their different kinds of effects on phenotypes, in keeping with the general emphasis on phenotypes in this book.
Streszczenia konferencji na temat "Matter phases classification"
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Thiang, Guo Chuan. "On the K-theoretic classification of topological phases of matter". W Frontiers of Fundamental Physics 14. Trieste, Italy: Sissa Medialab, 2016. http://dx.doi.org/10.22323/1.224.0149.
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Badawi, W. K., Z. M. Osman, M. A. Sharkas i M. Tamazin. "A classification technique for condensed matter phases using a combination of PCA and SVM". W 2017 Progress In Electromagnetics Research Symposium - Spring (PIERS). IEEE, 2017. http://dx.doi.org/10.1109/piers.2017.8261759.
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Canina, Marita, Carmen Bruno i Eva Monestier. "An operational framework of methods for designing ethical and sustainable future digital scenarios". W 13th International Conference on Applied Human Factors and Ergonomics (AHFE 2022). AHFE International, 2022. http://dx.doi.org/10.54941/ahfe1001507.
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The rapid pace of technological innovations is changing almost every aspect of people’s lives. Indeed, digital technologies are reshaping behaviors and human interactions as well as having great impacts on the environmental, political and economic level (Schwab, 2016). In this scenario, it becomes paramount for people to be able to adapt to this increasingly digital environment to reach the so-called Digital Maturity (MIT Sloan Management Review, 2017) and to recognize and unlock the huge potentialities of emerging technologies to foster sustainable development (WEF & PwC, 2020).Such topics are being addressed and tackled by the Digital Creativity for developing Digital Maturity Future Skills (DC4DM) European Project [1], a three-year project funded by the Erasmus + Program and whose outcome will be the spread of an educational model to train students to become Digital Maturity Enablers, new professional figures up-skilled to drive the change and to creatively envision future possibilities. Digital Maturity Enablers, indeed, have to possess a set of Digital Creative Abilities (DCAs) which encompass all those competencies, attitudes and mindsets that allow them to unleash their full creative potential. The empowerment and practice of such DCAs are enabled by the DC4DM educational model, a creativity-driven design model to free learners’ creativity and ease the achievement of a Digital Maturity (Bruno & Canina, 2021).Some DCAs can be trained simultaneously and are thus grouped in the so-called Drivers, clusters of DCAs that allow learners to gain awareness on paramount topics applied to digital technologies, namely digital ethics and sustainability, collaboration, technology foresight, data collection and complexity. Within this context, the aim of the paper is to introduce an operational framework built as part of the methodology used to identify the most important methods and tools to enhance the DCAs related to ethics, sustainability and futures thinking. Indeed, an ad hoc methodology was implemented in order to provide a systematic overview of the existing resources that could be useful to develop the competencies to design responsibly and sustainably with digital technologies and to envision futures possibilities. The effort has been channeled into mapping and clustering methods, tools, techniques and formats i.e. every type of resource that could help students acquire the creative abilities included in the cross model area called “Digital Responsibility and Sustainability”. As a matter of fact, the initial draft of the DC4DM model, the starting point to conceive the methodology, consisted of three phases, namely Pre-Process, Process and Post-Process, and a cross model area which included all the ethics, sustainability and futures thinking-related abilities essential when dealing with digital technologies. In order to filter and systematize the selected resources, these three dimensions have been considered as macro-categories and some criteria identified to steer the classification process. Based on their objectives, all the resources have been mapped on the DC4DM model, sorted between the Pre-Process and Process phase and finally collected in a digital booklet. So far the booklet has been used internally by the DC4DM consortium which is actually willing to make it an open online repository accessible to anyone interested in improving specific abilities. [1] https://www.dc4dm.eu/
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Maia, Pedro, i Raul Pinto. "Original-Copy: ideation for a lampshade inspired by nature". W 14th International Conference on Applied Human Factors and Ergonomics (AHFE 2023). AHFE International, 2023. http://dx.doi.org/10.54941/ahfe1003545.
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The following article looks at nature as a cultural pre-set narrative (or set of narratives) and reflects on how it can influence the design process to achieve a concrete result - a product. It describes an ongoing process that intersects intangible (behaviours) and tangible (matter) expressions of nature with the concept of Original-Copy, as the conceptual framework to develop and materialize a lampshade.The inclusion of behaviour patterns presents poetic and imaginative properties to trigger the conceptual phase of a project, while biomatter was chosen to physically materialize the ideas. In this context, the Original-Copy concept works as the archetype on which a new product can be based.The aforementioned approach has been applied and developed through a workshop, which intends to join the three concepts referred to above: behaviours, matter and original-copy.Firstly, a taxonomy of animals´ seduction rituals and courtship behaviours has been developed, which includes various criteria of classification, such as duration, triggers, interaction, or intensity. This taxonomy works as the catalyst of the workshop, to promote imagination and disruption in the design process.In this challenge, the shape of the object is predetermined by an original form (an archetype), in this case, the renowned Constanza lampshade, produced by the Italian brand Luceplan. The poetic dimension is induced by the attempt of translating the patterns of animal mating rituals described in the taxonomy into the characteristics of the biomaterial. The final objective was for the participants to express themselves through the physical dimension (texture, opacity, smell, touch, taste, bias) of created materials, inspired by animal behaviours, and use it to create the reinterpretation of the pre-existing form of the Constanza lampshade.After explaining the workshop methodology, the article presents the main ideas generated. Selected behaviours and the way of their application, composition of the created biomaterials used to materialize the ideas, as well as the final outcomes are described.An important part of the article is the report on the failed attempts of creating the materials and constructing the lampshades, their causes and the impact on the whole process.In the future, further evaluation and development of the proposed approach are anticipated, through the described workshops in different social and geographic contexts. It is awaited the possible creation of collections of other design classics lampshades, based on distinct triggers, for example on endogenous resources, emphasizing different ways how nature can influence design.
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Ali, Abdulbaset, Harnoor Singh, Daniel Kelly, Donald Hender, Alan Clarke, Mohammad Mahdi Ghiasi, Ronald Haynes i Lesley James. "Automatic Classification of PDC Cutter Damage Using a Single Deep Learning Neural Network Model". W SPE/IADC International Drilling Conference and Exhibition. SPE, 2023. http://dx.doi.org/10.2118/212503-ms.
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Abstract There is considerable value in automatically quantifying cutter damage from drill bit pictures. Current approaches do not classify cutter damage by type, i.e., broken, chipped, lost, etc. We, therefore, present a computer vision model using deep learning neural networks to automate multi-type damage detection in Polycrystalline Diamond Compact (PDC) drill bit cutters. The automated bit damage detection approach presented in this paper is based on training a computer vision model on different cutter damage types aimed at detecting and classifying damaged cutters directly. Prior approaches detected cutters first and then classified the damage type for the detected cutters. The You Only Look Once version 5 (YOLOv5) algorithm was selected based on the findings of an earlier published study. Different models of YOLOv5 were trained with different architecture sizes with various optimizers using two-dimensional (2D) drill bit images provided by the SPE Drilling Uncertainty Prediction technical section (DUPTS) and labeled by the authors with training from industry subject matter experts. To achieve the modeling goal, the images were first annotated and labeled to create training, validation, and testing sub-datasets. Then, by changing brightness and color, the images allocated for the training phase were augmented to generate more samples for the model development. The categories defined for labeling the DUPTS dataset were bond failure, broken cutter, chipped cutter, lost cutter, worn cutter, green cutter, green gauge, core out, junk damage, ring out, and top view. These categories can be updated once the IADC upgrade committee finishes upgrading IADC dull bit grading cones. Trained models were validated using the validation dataset of 2D images. It showed that the large YOLOv5 with stochastic gradient descent (SGD) optimizer achieved the highest metrics with a short training cycle compared to the Adam optimizer. In addition, the model was tested using an unseen data set collected from the local office of a drill bit supplier. Testing results illustrated a high level of performance. However, it was observed that inconsistency and quality of rig site drill bit photos reduce model accuracy. Therefore, it is suggested that companies produce large sets of quality images for developing better models. This study successfully demonstrates the integration of computer vision and machine learning for drill bit grading by categorizing/classifying damaged cutters by type directly in one stage rather than detecting the cutters first and then classifying them in a second stage. To guarantee the deployed model's robustness and consistency the model deployment has been tested in different environments that include cloud platform, container on a local machine, and cloud platform as a service (PaaS) with an online web app. In addition, the model can detect ring out and cored damages from the top view drill bit images, and to the best of the authors’ knowledge, this has not been addressed by any study before. The novelty of the developed deep learning computer vision algorithm is the ability to detect different cutter damage types in a fast and efficient process compared to the current lengthy manual damage evaluation practice. Furthermore, the trained model can detect damages that frequently take place in more than one blade of the bit such as ring outs and coring. In addition, a user-friendly interface was developed that generates results in pdf and CSV file formats for further data analysis, visualization, and documentation. Also, all the technologies used in the development of the model are open source and we made our web app implementation open access.