912 research outputs found

    Entropy Stable Summation-by-Parts Methods for Hyperbolic Conservation Laws on h/p Non-Conforming Meshes

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    In this work we present high-order primary conservative and entropy stable schemes for hyperbolic systems of conservation laws with geometric (h) and algebraic (p) non-conforming rectangular meshes. Throughout we rely on summation-by-parts (SBP) operators which discretely mimic the integration-by-parts rule to construct stable approximations. Thus, the discrete proofs of primary conservation and entropy stability can be done in a one-to-one fashion to the continuous analysis. Here, we consider different SBP operators based on finite difference as well as discontinuous Galerkin approaches. We derive non-conforming schemes by extending ideas of high-order primary conservative and entropy stable SBP methods on conforming meshes. Here, special attention is given to the coupling between non-conforming elements. The coupling is instructed to entropy stable projection operators. However, these projection operators suffer from a suboptimal degree. Therefore, we develop degree preserving SBP operators where the norm matrix has a higher degree compared to classical SBP operators. With these operators it is possible to construct entropy stable projection operators which have the same degree as the SBP differentiationmatrix. Typically, high-order primary conservative and entropy stable schemes are semi-discrete methods with a discretized spatial domain and assuming continuity in time. Therefore, temporal errors are introduced when integrating the conservation laws in time with standard methods, e.g. Runge-Kutta schemes, for which the entropy can have an unpredictable temporal behaviour. Thus, we extend high-order primary conservative and entropy stable semi-discrete methods to fully-discrete schemes on conforming and non-conforming meshes. This results in an implicit space-time method. We introduce a simple mesh generation strategy to obtain quadrilateral meshes surrounding two dimensional complex geometries. Finally, with the generated meshes we simulate a flow around a NACA0012 airfoil to demonstrate the benefits of considering non-conforming elements for a practical simulation

    Learning to learn with an evolutionary strategy applied to variational quantum algorithms

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    Variational Quantum Algorithms (VQAs) employ quantum circuits parameterized by UU, optimized using classical methods to minimize a cost function. While VQAs have found broad applications, certain challenges persist. Notably, a significant computational burden arises during parameter optimization. The prevailing ``parameter shift rule'' mandates a double evaluation of the cost function for each parameter. In this article, we introduce a novel optimization approach named ``Learning to Learn with an Evolutionary Strategy'' (LLES). LLES unifies ``Learning to Learn'' and ``Evolutionary Strategy'' methods. ``Learning to Learn'' treats optimization as a learning problem, utilizing recurrent neural networks to iteratively propose VQA parameters. Conversely, ``Evolutionary Strategy'' employs gradient searches to estimate function gradients. Our optimization method is applied to two distinct tasks: determining the ground state of an Ising Hamiltonian and training a quantum neural network. Results underscore the efficacy of this novel approach. Additionally, we identify a key hyperparameter that significantly influences gradient estimation using the ``Evolutionary Strategy'' method

    The quantum cost function concentration dependency on the parametrization expressivity

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    Although we are currently in the era of noisy intermediate scale quantum devices, several studies are being conducted with the aim of bringing machine learning to the quantum domain. Currently, quantum variational circuits are one of the main strategies used to build such models. However, despite its widespread use, we still do not know what are the minimum resources needed to create a quantum machine learning model. In this article, we analyze how the expressiveness of the parametrization affects the cost function. We analytically show that the more expressive the parametrization is, the more the cost function will tend to concentrate around a value that depends both on the chosen observable and on the number of qubits used. For this, we initially obtain a relationship between the expressiveness of the parametrization and the mean value of the cost function. Afterwards, we relate the expressivity of the parametrization with the variance of the cost function. Finally, we show some numerical simulation results that confirm our theoretical-analytical predictions. To the best of our knowledge, this is the first time that these two important aspects of quantum neural networks are explicitly connected

    De Quaestionibus Seu Tortura Disputatio

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    STRONG POROUS GLASS-CERAMICS FROM ALKALI ACTIVATION AND SINTER-CRYSTALLIZATION OF VITRIFIED MSWI BOTTOM ASH

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    Vitrification of municipal solid waste incineration (MSWI) bottom ash is an effective method to produce a chemically stable glass, with metal recovery. In order to justify the high costs of this process, the vitrified residue can then be upcycled into potential marketable products. In this study, vitrified bottom ash was successfully converted into strong and chemically stable porous glass-ceramics by the combination of alkali activation and sintering. After the activation of the glass in a NaOH solution of low molarity, foams were easily produced by intensive mechanical stirring, with the aid of a surfactant, and stabilized by gelation. The obtained open-celled material was further consolidated by a sintering treatment, at 800-900\ub0C. The addition of recycled soda-lime glass allowed activation at low molarity and sintering at lower temperature, but it reduced the mechanical properties and the stabilization of heavy metals. On the other hand, the increase in molarity of the alkaline solution increased the porosity and also the strength of foams from vitrified bottom ash

    Microstructured blood vessel surrogates reveal structural tropism of motile malaria parasites

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    Plasmodium sporozoites, the highly motile forms of the malaria parasite, are transmitted naturally by mosquitoes and traverse the skin to find, associate with, and enter blood capillaries. Research aimed at understanding how sporozoites select blood vessels is hampered by the lack of a suitable experimental system. Arrays of uniform cylindrical pillars can be used to study small cells moving in controlled environments. Here, an array system displaying a variety of pillars with different diameters and shapes is developed in order to investigate how Plasmodium sporozoites associate to the pillars as blood vessel surrogates. Investigating the association of sporozoites to pillars in arrays displaying pillars of different diameters reveals that the crescent-shaped parasites prefer to associate with and migrate around pillars with a similar curvature. This suggests that after transmission by a mosquito, malaria parasites may use a structural tropism to recognize blood capillaries in the dermis in order to gain access to the blood stream

    As deficiências constitucionais da Teoria do Bem Jurídico

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    Title: The Constitucional Deficiencies of the German "Rechtsgutslehre”Resumo: O presente trabalho questiona os méritos teóricos e a validade constitucional da “Rechtsgutslehre” (teoria da proteção de bens jurídicos), uma teoria amplamente difundida acerca dos limites da criminalização legítima na Alemanha e em outras jurisdições. A causa imediata para esta reanálise é uma decisão recente da Corte constitucional alemã que ratificou a proibição do incesto na Alemanha e ao mesmo tempo rejeitou a tradicional “Rechtsgutslehre” como constitucionalmente irrelevante, o que resultou em considerável controvérsia entre os penalistas. O trabalho tenta demonstrar o porquê a decisão da corte ser acertada, apontando as principais deficiências da teoria, e quais critérios uma teoria mais adequada deve cumprir.Palavras-chave: Limites constitucionais do direito penal, direito penal democrático, proteção de bens jurídicos, legitimidade da punição, Rechtsgutslehre. Abstract: This paper questions the theoretical merits and constitutional validity of the “Rechtsgutslehre” (doctrine of the protection of legal goods), a widely held doctrine about the limits of legitimate criminalization in Germany and some other jurisdictions. The immediate cause for this reassessment is a recent decision of the German constitutional court which upheld the German incest prohibition and simultaneously rejected the traditional “Rechtsgutslehre” as constitutionally irrelevant, thereby stirring up considerable controversy among academic criminal lawyers. The paper tries to show why the court’s view is correct by pointing out the main deficiencies of the doctrine and what criteria a better theory must fulfil.Keywords: Constitutional limits of criminal law, democratic criminal law, protection of legal goods, legitimacy of punishment, Rechtsgutslehre. Título original: The Constitucional Deficiencies of the German "Rechtsgutslehre” Tradução de Lucas Minorell

    PROPOSIÇÃO DE DIRETRIZES ESTRATÉGICAS PARA ELEVAR O CONCEITO DA PÓS-GRADUAÇÃO: ESTUDO DE CASO DO PPGGEO

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    Este artigo apresenta uma proposta de diretrizes para que o Programa de Pós-Graduação Stricto Senso de Gestão Estratégica de Organizações (PPGGEO), Mestrado Profissional, da Universidade Regional Integrada do Alto Uruguai e das Missões, Campus Santo Ângelo-RS, alcance maior conceito na avaliação da Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (Capes), que será realizada em 2016. Caracteriza-se como uma pesquisa qualitativa, sendo descritiva e exploratória, pois a formulação da proposta de diretrizes fundamenta-se em leitura de autores e organismos que tratam do tema bem como na ficha de avaliação que foi aplicada ao PPGGEO pela Capes no ano 2013

    Submillisievert Computed Tomography of the Chest Using Model-Based Iterative Algorithm: Optimization of Tube Voltage With Regard to Patient Size

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    Objective: The aim of this study was to define optimal tube potential for soft tissue and vessel visualization in dose-reduced chest CT protocols using model-based iterative algorithm in average and overweight patients. Methods: Thirty-six patients receiving chest CTaccording to 3 protocols (120 kVp/noise index [NI], 60;100 kVp/NI, 65;80 kVp/NI, 70) were included in this prospective study, approved by the ethics committee. Patients' physical parameters and dose descriptors were recorded. Images were reconstructed with model-based algorithm. Two radiologists evaluated image quality and lesion conspicuity;the protocols were intraindividually compared with preceding control CT reconstructed with statistical algorithm (120 kVp/NI, 20). Mean and standard deviation of attenuation of the muscle and fat tissues and signal-to-noise ratio of the aorta were measured. Results: Diagnostic images (lesion conspicuity, 95%-100%) were acquired in average and overweight patients at 1.34, 1.02, and 1.08 mGy and at 3.41, 3.20, and 2.88 mGy at 120, 100, and 80 kVp, respectively. Data are given as CT dose index volume values. Conclusions: Model-based algorithm allows for submillisievert chest CT in average patients;the use of 100 kVp is recommended
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