IA Scholar Query: Topology Preserving Algorithms for Implicit Surfaces Simplifying and Sewing.
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Internet Archive Scholar query results feedeninfo@archive.orgThu, 29 Sep 2022 00:00:00 GMTfatcat-scholarhttps://scholar.archive.org/help1440Notes on invariant measures for loop groups
https://scholar.archive.org/work/xwbwpdllrjcrlhm5il2pwudyla
Let K denote a simply connected compact Lie group and let G denote its complexification. It is known that there exists an LK-biinvariant probability measure on a natural completion of the complex loop group LG. It is believed that there exist deformations which are positive line bundle valued and reproduce the unitary structure for (projective) positive energy representations of LK. These are notes which supplement lectures I have given on these measures, explaining a number of conjectures concerning how these measures are characterized, how they are computed, and how they are potentially useful for formulating quantum sigma models.Doug Pickrellwork_xwbwpdllrjcrlhm5il2pwudylaThu, 29 Sep 2022 00:00:00 GMTPeter Bergmann on Observables in Hamiltonian General Relativity: A Historical-Critical Investigation
https://scholar.archive.org/work/nxpiwdfsn5bdhjn2zoqygsroqu
The problem of observables and their supposed lack of change has been significant in Hamiltonian quantum gravity since the 1950s. This paper considers the unrecognized variety of ideas about observables in the thought of Peter Bergmann, who invented observables. Whereas initially he required a constrained Hamiltonian formalism to be mathematically equivalent to the Lagrangian, in 1953 Bergmann and Schiller introduced a novel postulate, motivated by facilitating quantum gravity: observables were _invariant_ under transformations generated by _each individual_ first-class constraint. While modern works rely on Bergmann's authority and sometimes speak of "Bergmann observables," he had much to say about observables, plausible but not all consistent or remembered. At times he required observables to be locally defined (not changeless and global); at times he wanted them independent of the Hamiltonian formalism (not essentially involving separate first-class constraints). But typically he took observables to have vanishing Poisson bracket with each first-class constraint, purportedly justified by electrodynamics. He expected observables to be analogous to the transverse true degrees of freedom of electromagnetism. Hence there is no coherent concept of observables which he reliably endorsed. A revised definition of observables that satisfies the requirement that equivalent theories should have equivalent observables using the Rosenfeld-Anderson-Bergmann-Castellani gauge generator G, a tuned sum of first-class constraints that changes the canonical action ∫ dt(pq̇-H) by a boundary term. Bootstrapping from theory formulations with no first-class constraints, the "external" coordinate symmetry of GR calls for covariance (4-dimensional Lie derivative), not invariance (0 Poisson bracket), under G (not each first-class constraint).J. Brian Pittswork_nxpiwdfsn5bdhjn2zoqygsroquThu, 11 Aug 2022 00:00:00 GMTA tectonic-rules-based mantle reference frame since 1 billion years ago – implications for supercontinent cycles and plate–mantle system evolution
https://scholar.archive.org/work/veeugyh5nrbxfkird2i2lbhb5q
Abstract. Understanding the long-term evolution of Earth's plate–mantle system is reliant on absolute plate motion models in a mantle reference frame, but such models are both difficult to construct and controversial. We present a tectonic-rules-based optimization approach to construct a plate motion model in a mantle reference frame covering the last billion years and use it as a constraint for mantle flow models. Our plate motion model results in net lithospheric rotation consistently below 0.25∘ Myr−1, in agreement with mantle flow models, while trench motions are confined to a relatively narrow range of −2 to +2 cm yr−1 since 320 Ma, during Pangea stability and dispersal. In contrast, the period from 600 to 320 Ma, nicknamed the "zippy tricentenary" here, displays twice the trench motion scatter compared to more recent times, reflecting a predominance of short and highly mobile subduction zones. Our model supports an orthoversion evolution from Rodinia to Pangea with Pangea offset approximately 90∘ eastwards relative to Rodinia – this is the opposite sense of motion compared to a previous orthoversion hypothesis based on paleomagnetic data. In our coupled plate–mantle model a broad network of basal mantle ridges forms between 1000 and 600 Ma, reflecting widely distributed subduction zones. Between 600 and 500 Ma a short-lived degree-2 basal mantle structure forms in response to a band of subduction zones confined to low latitudes, generating extensive antipodal lower mantle upwellings centred at the poles. Subsequently, the northern basal structure migrates southward and evolves into a Pacific-centred upwelling, while the southern structure is dissected by subducting slabs, disintegrating into a network of ridges between 500 and 400 Ma. From 400 to 200 Ma, a stable Pacific-centred degree-1 convective planform emerges. It lacks an antipodal counterpart due to the closure of the Iapetus and Rheic oceans between Laurussia and Gondwana as well as due to coeval subduction between Baltica and Laurentia and around Siberia, populating the mantle with slabs until 320 Ma when Pangea is assembled. A basal degree-2 structure forms subsequent to Pangea breakup, after the influence of previously subducted slabs in the African hemisphere on the lowermost mantle structure has faded away. This succession of mantle states is distinct from previously proposed mantle convection models. We show that the history of plume-related volcanism is consistent with deep plumes associated with evolving basal mantle structures. This Solid Earth Evolution Model for the last 1000 million years (SEEM1000) forms the foundation for a multitude of spatio-temporal data analysis approaches.R. Dietmar Müller, Nicolas Flament, John Cannon, Michael G. Tetley, Simon E. Williams, Xianzhi Cao, Ömer F. Bodur, Sabin Zahirovic, Andrew Merdithwork_veeugyh5nrbxfkird2i2lbhb5qThu, 07 Jul 2022 00:00:00 GMTZMK Zeitschrift für Medien- und Kulturforschung. Schalten und Walten
https://scholar.archive.org/work/hykxofh3ovcs7kzpbykz7exkou
ZMK 11 | 2020 into space. If complex semiconductor circuits can finally take over thought processes such as arithmetic or even speech, then they are still bodies of thought. So Schalten on its turn brings with it Walten like its own shadow, and, of course, media theory is interested in this remaining ontological shadow of digitization and of mediatization in general. But there is even more than the necessary pertinence of Walten even under digital conditions. Walten is not only the unavoidable substrate of Schalten, it can also emerge from it. One striking example can be seen in what Raymond Williams called the flow. The flux of images on TV is, due to the switchability of the screen picture, continuously and constantly interrupted in a most abrupt way by switching over to other images, most heterogenuous image types, TV genres, broadcast formats. They interfere with each other in a way to only leave caleidoscopic meaningless fragments, tiny bits and pieces of what used to be for instance, news, advertising, wheater forecasts, sports, shows, episodes, fictions, live transmissions, announcements, wrap ups, and so forth. There is no coherence of whatsoever quality, especially if it comes to semantics, to meaning or to any form of Gestalt. The term of coherence (or of interruption) loses any significance. Switching operates, as Hartmut Winkler once put it, an operation directed against any kind of context and hence of text. But, Williams observes, a strange kind of rhythm, or of surfing on the surface of the fragmented sequence of distinctions and of switching operations that comes into being. Based on highly frequent interruptions, a flow of plasticity and viscosity arises, a state of experience or even existence, a mode of being, which integrates viewers, images, switchable pictures, sounds, and the world beyond. Flow is a bodily and hence physical, material phenomenon, not just a structure or a sequence of otherwise disembodied distinctions. It hence brings physis back into the game. Flow emerges from switching, Schalten, but it rules in the sense of Walten. What can be found in the switchable picture may also emerge elsewhere. The Maltese Cross in the movie camera (and projector) could also be adressed here, or, even more general, language. In what André Martinet called la double articulation du langage, the articulation or segmentation of what has already been articulated or fragmented, the coherent dominion of sense emerges as both an artifact, and hence on the side of switching, and an unavoidably and unquestionably ruling condition of existence. Signals, discernable and switchable entities, as they emerge from ruling noise may on their turn, if sequenced, generate a kind of second order flow-like noise and as such turn into given conditions of existence. The cloud, or looped CCTV Systems, or the pervasion of the habitat with computers, and hence switches, may be regarded in a comparable way as modes of turning Schalten into Walten. In this sense, with the topic of Schalten und Walten, the last issue of the ZMK endeavors to investigate the entry or implementation of the mathematical, switch-(:Unkn) Unknown, Mediarep.Org, Lorenz Engell, Bernhard Siegertwork_hykxofh3ovcs7kzpbykz7exkouWed, 29 Jun 2022 00:00:00 GMTProceedings of the 2009 WSU International Research Conference
https://scholar.archive.org/work/wgd3xf3hyfc2hcidomfzjbyumi
Overview The papers featuring in this Book of Conference Proceedings: Advancing Knowledge for Empowerment through Innovations in Research, are part of the 130 oral and poster presentations made at the 2009 Walter Sisulu University (WSU) Research Conference. Manuscripts were subjected to single-blind peer reviews, from which the 31 published in this Book of Conference Proceedings were accepted. The reviewers of the manuscripts are scholars of reputable academic standing drawn from tertiary and research institutions in South Africa and abroad. The published articles are reflective of contemporary topical issues of research, spanning from Biomedical and Health Sciences, Mathematical and Physical Sciences, Education; and Business, Management Sciences and Law. In Biomedical and Health Sciences, some of the articles discussed subjects such as Severe Acute Respiratory Syndrome (SARS), HIV/AIDS, herbal diarrhoea remedies, lipid peroxidation, health informatics; and cysticercosis and taeniasis. Quantum cryptography, electric and magnetic diapole moments, reproductive biology, pest management, traditional medicinal plants, epibionts, and biological technologies are some of the issues elaborated on in the Mathematical and Physical Sciences section. In Business, Management Sciences and Law, the Chickerings Theory of Development and Indigenous African Law are discussed. Some of the papers in Education considered ethical theories, deconstructive criticism, integrated quality management system, curriculum reform, research and knowledge management, musical analyses, rural poverty and conflict resolution. With an anticipated wide readership, Advancing Knowledge for Empowerment through Innovations in Research is a book reflective of a Developmental University's research efforts such as WSU. Prof GE Ekosse Chairperson: Scientific Organizing Committee 2009 WSU Research Conference PROCEEDINGS East London, South Africa 25th – 27th August 2009 ADVANCING KNOWLEDGE FOR EMPOWERMENT THROUGH INNOVATIONS IN RESEARCHAdelin Kantorework_wgd3xf3hyfc2hcidomfzjbyumiFri, 13 May 2022 00:00:00 GMTFIRST INTERNATIONAL CONFERENCE ON ARTIFICIAL INTELLIGENCE AND DATA SCIENCE (ICAIDS-2022)
https://scholar.archive.org/work/l2cydaphindbxd3aqhpzsr7gvy
SRM IST Ramapuram Campus stands tall for its successful, developed holistic system where the formal education has been intricately woven with moral, spiritual and social education. The dynamism of the young talent blooming in our garden is being tapped; the skills and the potentialities of its students and faculty members are being mined out and chiseled. I would like to congratulate the staff, the students of the Department of Computer Applications (BCA) and all the others directly and indirectly associated in organizing the First International Conference on Artificial Intelligence and Data Science (ICAIDS-2022) in association with Object Automation Software Solutions Pvt ltd, IBM, OpenPower, Onstitute and X-Scale Solutions on 4th and 5th March 2022.Dr. Agusthiyar . Rwork_l2cydaphindbxd3aqhpzsr7gvyFri, 04 Mar 2022 00:00:00 GMTGeometric recursion
https://scholar.archive.org/work/gowip6k5ubgfndn5ndzx6nxlz4
We propose a general theory for constructing functorial assignments Σ⟼Ω_Σ∈ E(Σ) for a large class of functors E from a certain category of bordered surfaces to a suitable target category of topological vector spaces. The construction proceeds by successive excisions of homotopy classes of embedded pairs of pants, and thus by induction on the Euler characteristic. We provide sufficient conditions to guarantee the infinite sums appearing in this construction converge. In particular, we can generate mapping class group invariant vectors Ω_Σ∈ E(Σ). The initial data for the recursion encode the cases when Σ is a pair of pants or a torus with one boundary, as well as the "recursion kernels" used for glueing. We give this construction the name of Geometric Recursion. As a first application, we demonstrate that our formalism produce a large class of measurable functions on the moduli space of bordered Riemann surfaces. Under certain conditions, the functions produced by the geometric recursion can be integrated with respect to the Weil–Petersson measure on moduli spaces with fixed boundary lengths, and we show that the integrals satisfy a topological recursion generalizing the one of Eynard and Orantin. We establish a generalization of Mirzakhani–McShane identities, namely that multiplicative statistics of hyperbolic lengths of multicurves can be computed by the geometric recursion. As a corollary, we show that the systole function can be obtained from the geometric recursion. The theory has however a wider scope than functions on Teichmüller space, which will be explored in subsequent papers; one expects that many functorial objects in low-dimensional geometry could be constructed by variants of this geometric recursion.Jørgen Ellegaard Andersen, Gaëtan Borot, Nicolas Orantinwork_gowip6k5ubgfndn5ndzx6nxlz4Fri, 25 Feb 2022 00:00:00 GMTCLO3D-Based 3D Virtual Fitting Technology of Down Jacket and Simulation Research on Dynamic Effect of Cloth
https://scholar.archive.org/work/lajzi3bomrhwxihnq4j7h7a3em
A 3D virtual fitting system for down jackets based on CLO3D is proposed and implemented in this paper. CLO3D system realizes virtual fitting, including three-dimensional body modeling, parametric punching, three-dimensional virtual sewing fitting, fabric texture attribute setting, and dynamic display, which realizes the design and realization of display. The clothing deformation algorithm based on human input posture is used to deform the clothing model, which presents the physical characteristics of virtual clothing more truly. At the same time, the image acquisition equipment is used to obtain the real-life image, and the clothing image transfer algorithm is used to superimpose the virtual clothes and the real-life image. The position of human joints is obtained by feature extraction technology, and the scaling ratio of the virtual clothes is calculated so that the virtual clothes are closely combined with the real-life image. Compared with similar virtual fitting systems in the industry, the information processing process of this system is more intelligent, the interaction is more natural, and the fitting effect is more realistic. We make every effort to make the virtual fitting system reduce the gap between virtual and reality and tend to be more realistic and popular.Shuxian Huang, Li Huang, Xin Ningwork_lajzi3bomrhwxihnq4j7h7a3emFri, 18 Feb 2022 00:00:00 GMTSewing spacetime with Lorentzian threads: complexity and the emergence of time in quantum gravity
https://scholar.archive.org/work/mt3m4otvwvae5k2ke7qjef6lo4
Holographic entanglement entropy was recently recast in terms of Riemannian flows or 'bit threads'. We consider the Lorentzian analog to reformulate the 'complexity=volume' conjecture using Lorentzian flows -- timelike vector fields whose minimum flux through a boundary subregion is equal to the volume of the homologous maximal bulk Cauchy slice. By the nesting of Lorentzian flows, holographic complexity is shown to obey a number of properties. Particularly, the rate of complexity is bounded below by conditional complexity, describing a multi-step optimization with intermediate and final target states. We provide multiple explicit geometric realizations of Lorentzian flows in AdS backgrounds, including their time-dependence and behavior near the singularity in a black hole interior. Conceptually, discretized flows are interpreted as Lorentzian threads or 'gatelines'. Upon selecting a reference state, complexity thence counts the minimum number of gatelines needed to prepare a target state described by a tensor network discretizing the maximal volume slice, matching its quantum information theoretic definition. We point out that suboptimal tensor networks are important to fully characterize the state, leading us to propose a refined notion of complexity as an ensemble average. The bulk symplectic potential provides a specific 'canonical' thread configuration characterizing perturbations around arbitrary CFT states. Consistency of this solution requires the bulk satisfy the linearized Einstein's equations, which are shown to be equivalent to the holographic first law of complexity, thereby advocating for a principle of 'spacetime complexity'. Lastly, we argue Lorentzian threads provide a notion of emergent time. This article is an expanded and detailed version of [arXiv:2105.12735], including several new results.Juan F. Pedraza, Andrea Russo, Andrew Svesko, Zachary Weller-Davieswork_mt3m4otvwvae5k2ke7qjef6lo4Mon, 14 Feb 2022 00:00:00 GMTA Robust Grid-Based Meshing Algorithm for Embedding Self-Intersecting Surfaces
https://scholar.archive.org/work/o5zoqb774vgovmpeh26qltbufi
The creation of a volumetric mesh representing the interior of an input polygonal mesh is a common requirement in graphics and computational mechanics applications. Most mesh creation techniques assume that the input surface is not self-intersecting. However, due to numerical and/or user error, input surfaces are commonly self-intersecting to some degree. The removal of self-intersection is a burdensome task that complicates workflow and generally slows down the process of creating simulation-ready digital assets. We present a method for the creation of a volumetric embedding hexahedron mesh from a self-intersecting input triangle mesh. Our method is designed for efficiency by minimizing use of computationally expensive exact/adaptive precision arithmetic. Although our approach allows for nearly no limit on the degree of self-intersection in the input surface, our focus is on efficiency in the most common case: many minimal self-intersections. The embedding hexahedron mesh is created from a uniform background grid and consists of hexahedron elements that are geometrical copies of grid cells. Multiple copies of a single grid cell are used to resolve regions of self-intersection/overlap. Lastly, we develop a novel topology-aware embedding mesh coarsening technique to allow for user-specified mesh resolution as well as a topology-aware tetrahedralization of the hexahedron mesh.Steven W. Gagniere, Yushan Han, Yizhou Chen, David A. B. Hyde, Alan Marquez-Razon, Joseph Teran, Ronald Fedkiwwork_o5zoqb774vgovmpeh26qltbufiMon, 17 Jan 2022 00:00:00 GMTThe Sharing Economy in Europe
https://scholar.archive.org/work/ktj7tfndyzfwjkoxxjfy5jrhiu
This open access book considers the development of the sharing and collaborative economy with a European focus, mapping across economic sectors, and country-specific case studies. It looks at the roles the sharing economy plays in sharing and redistribution of goods and services across the population in order to maximise their functionality, monetary exchange, and other aspects important to societies. It also looks at the place of the sharing economy among various policies and how the contexts of public policies, legislation, digital platforms, and other infrastructure interrelate with the development and function of the sharing economy. The book will help in understanding the future (sharing) economy models as well as to contribute in solving questions of better access to resources and sustainable innovation in the context of degrowth and growing inequalities within and between societies. It will also provide a useful source for solutions to the big challenges of our times such as climate change, the loss of biodiversity, and recently the coronavirus disease pandemic (COVID-19). This book will be of interest to academics and students in economics and business, organisational studies, sociology, media and communication and computer science.Andrzej Klimczukwork_ktj7tfndyzfwjkoxxjfy5jrhiuSat, 01 Jan 2022 00:00:00 GMTOutput feedback sliding mode control for time delay systems
https://scholar.archive.org/work/7qyz5lv2p5c4jklnvq7kycma6y
This Thesis considers Sliding Mode Control (SMC) for linear systems subjected to uncertainties and delays using output feedback. Delay is a natural phenomenon in many practical systems, the effect of delay can be the potential cause -of performance deterioration or even instability. To achieve better control performance, SMC with output feedback is considered for its inherent robustness feature and practicality for implementation. In highlighting the main results, firstly a novel output feedback SMC design is presented which formulates the problem into Linear Matrix Inequalities (LMIs). The efficiency of the design is compared with the the existing literature in pole assignment. eigenstructure assignment and other LMI methods, which either require more constraints on system structures or are computationally less tractable. For systems with timevarying Slate delay, the method is extended to incorporate the delay effect in the controUer synthesis. Both sliding surface and controller design are formulated as LMI problems. For systems with input/output delays and disturbances. the robustness of SMC is degraded with arbitrarily small delay appearing in the high frequency switching component of the controller. To solve the problem singular perturbation method is used to achieve bounded performance which is proportional to the magnitudes of delay, disturbance and switching gain. The applied research has produced two practical implementation studies. Firstly it relates to the pointing control of an autonomous vehicle subjected to external disturbances and friction resulting from the motion of the vehicle crossing rough terrain. The second implementation concerns the attitude control of a flexible spacecraft with respect to roil, pitch and yaw attitude angles.Xiaoran Han, Sarah K. Spurgeon, Emilia Fridmanwork_7qyz5lv2p5c4jklnvq7kycma6yAt the intersection between machine learning and econometrics: theory and applications
https://scholar.archive.org/work/j2sm2hz7infzlf2m3bhslepnaq
In the present work, we introduce theoretical and application novelties at the intersection between machine learning and econometrics in social and health sciences. In particular, Part 1 delves into optimizing the data collection process in a specific statistical model, commonly used in econometrics, employing an optimization criterion inspired by machine learning, namely, the generalization error conditioned on the training input data. In the first Chapter, we analyze and optimize the trade-off between sample size, the precision of supervision on a variation of the unbalanced fixed effects panel data model. In the second Chapter we extend the analysis to the Fixed Effects GLS (FEGLS) case in order to account for the heterogeneity in the data associated with different units, for which correlated measurement errors corrupt distinct observations related to the same unit. In Part 2, we introduce applications of innovative econometrics and machine learning techniques. In the third Chapter we propose a novel methodology to explore the effect of market size on market innovation in the Pharmaceutical industry. Finally, in the fourth Chapter, we innovate the literature on the economic complexity of countries through machine learning. The Dissertation contributes to the literature on machine learning and applied econometrics mainly by: (i) extending the current framework to novel scenarios and applications (Chapter 1 - Chapter 2); (ii) developing a novel econometric methodology to assess long-debated issues in literature (Chapter 3); (iii) constructing a novel index of economic complexity through machine learning (Chapter 4).Federico Nutarelliwork_j2sm2hz7infzlf2m3bhslepnaqSewing spacetime with Lorentzian threads: complexity and the emergence of time in quantum gravity
https://scholar.archive.org/work/57i7q73yt5gutgmy5i3zujevim
Holographic entanglement entropy was recently recast in terms of Riemannian flows or 'bit threads'. We consider the Lorentzian analog to reformulate the 'complexity=volume' conjecture using Lorentzian flows — timelike vector fields whose minimum flux through a boundary subregion is equal to the volume of the homologous maximal bulk Cauchy slice. By the nesting of Lorentzian flows, holographic complexity is shown to obey a number of properties. Particularly, the rate of complexity is bounded below by conditional complexity, describing a multi-step optimization with intermediate and final target states. We provide multiple explicit geometric realizations of Lorentzian flows in AdS backgrounds, including their time-dependence and behavior near the singularity in a black hole interior. Conceptually, discretized flows are interpreted as Lorentzian threads or 'gatelines'. Upon selecting a reference state, complexity thence counts the minimum number of gatelines needed to prepare a target state described by a tensor network discretizing the maximal volume slice, matching its quantum information theoretic definition. We point out that suboptimal tensor networks are important to fully characterize the state, leading us to propose a refined notion of complexity as an ensemble average. The bulk symplectic potential provides a specific 'canonical' thread configuration characterizing perturbations around arbitrary CFT states. Consistency of this solution requires the bulk satisfy the linearized Einstein's equations, which are shown to be equivalent to the holographic first law of complexity, thereby advocating for a principle of 'spacetime complexity'. Lastly, we argue Lorentzian threads provide a notion of emergent time. This article is an expanded and detailed version of [1], including several new results.Juan F. Pedraza, Andrea Russo, Andrew Svesko, Zachary Weller-Davieswork_57i7q73yt5gutgmy5i3zujevimVolume 19 : 2021 Issue 3
https://scholar.archive.org/work/vrbh3xhshjaujaey55hnjl6nvu
The views expressed in this publication are those of the author(s) and do not necessarily represent the views of MIP. This journal is a refereed journal. All articles were reviewed by two or three unanimous referees identified by the Institute (MIP).MIP Malaysiawork_vrbh3xhshjaujaey55hnjl6nvuSun, 17 Oct 2021 00:00:00 GMTTopological band crossings in metals, magnets, and non-Hermitian systems
https://scholar.archive.org/work/gnq6qv6otncf5ofjqyaqlpdwmi
Moritz M. Hirschmann, Universität Stuttgartwork_gnq6qv6otncf5ofjqyaqlpdwmiWed, 06 Oct 2021 00:00:00 GMT