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Monte-Carlo parameter variation study of cardiovascular pathologies to quantify parameter specific signal uncertainty

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Current Directions in Biomedical Engineering 2018年第1期4卷 379-383页

作者： Krickl, Stefan Bernhard, Stefan Pforzheim University of Applied Sciences Pforzheim Germany Department of Mathematics and Computer Science FU Berlin Berlin Germany

Cardiovascular diseases are the leading cause of death worldwide. Early detection of abnormal vascular morphologies like aneurysms in the abdominal (abdominal aortic aneurysm, AAA) or thoracic aorta (thoracic aortic aneurysm, TAA) are essential to prevent fatal events. The aim of this study is the development of a patient-specific simulation model to obtain statistical information about ab/normal pressure-flow conditions to improve the basic understanding and methods for the early detection of diseases. For this purpose, the numerical cardiovascular modeling tool SISCA was used, to generate a series of simulations by Monte-Carlo parameter variation. The considered variational scenario was built upon a control group of normal patients, deriving two pathological conditions for AAA and TAA with different severity and location. Therefore, the nominal diameters were enlarged between 200 % and 500 %, while the length of the aneurysms were modified within a range of 30 and 90 mm. Within each statistical set the convergence was tested by the bootstrap method ensuring that within a set of 3500 runs a 2 % deviation error of the mean value of the blood pressure was obtained compared to a set of 10000 *** parameter variation method allows the generation of disease specific data in the context of physiological/clinical findings and consequently the disease specific quantification of signal uncertainties and variances. © 2018 Stefan Krickl and Stefan Bernhard.

关键词： Sensitivity analysis

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NDDR-LCS: A Multi-Task Learning Method for Classification of Carotid Plaques

NDDR-LCS: A Multi-Task Learning Method for Classification of...

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IEEE International Conference on Image Processing

作者： Huayu Shen Wu Zhang Haiya Wang Guangtai Ding Jiang Xie School of Computer Engineering and Science Shanghai University Shanghai China Shanghai Institute of Applied Mathematics and Mechanics School of Mechanics and Engineering Science Shanghai University Shanghai China Department of Geriatric Shanghai Jiao Tong University Shanghai China

ISBN: (数字)9781728163956

ISBN: (纸本)9781728163963

Carotid plaque classification plays a critical role in the identification of vulnerable plaques, so it is crucial for early risk estimation of cardiovascular and cerebrovascular events. Carotid ultrasound examination with ultrasound images and reports produced by professional doctors is the most common way to assess atherosclerotic plaques in clinical practice. However, existing deep learning methods for carotid ultrasound image analysis ignore the information in the ultrasound report. In this paper, we propose a multi-task learning (MTL) method named NDDR-LCS based on convolutional neural network (CNN) that leverages auxiliary information from ultrasound reports to assist the carotid plaque classification task. NDDR-LCS utilizes dense blocks as feature descriptors and organically combines three novel MTL mechanisms that are Neural Discriminative Dimensionality Reduction (NDDR), Learning Mixtures, and Cross-Stitch, to learn dependencies between ultrasound images and ultrasound reports. Based on carotid ultrasound images and their corresponding diagnostic reports, we conduct sufficient experiments to prove that NDDR-LCS outperforms state-of-the-art CNN methods for carotid plaque classification.

关键词： Task analysis Ultrasonic imaging Feature extraction Atherosclerosis Dimensionality reduction Image analysis

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Regularity and numerical approximation of fractional elliptic differential equations on compact metric graphs

arXiv

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arXiv 2023年

作者： Bolin, David Kovács, Mihály Kumar, Vivek Simas, Alexandre B. Statistics Program Computer Electrical and Mathematical Sciences and Engineering Division King Abdullah University of Science and Technology Thuwal23955-6900 Saudi Arabia Department of Mathematical Sciences Chalmers University of Technology University of Gothenburg GothenburgSE-41296 Sweden Department of Differential Equations Budapest University of Technology and Economics Mauegyetem rkp. 3. BudapestH-1111 Hungary Faculty of Information Technology and Bionics Pázmány Péter Catholic University Práter utca 50/a. BudapestH-1083 Hungary Theoretical Statistics and Mathematics Unit Indian Statistical Institute Bangalore Centre 8th Mile Mysore Road Karnataka Bangalore560059 India

The fractional differential equation Lβu = f posed on a compact metric graph is considered, where β > 0 and L = κ2 − ∇(a∇) is a second-order elliptic operator equipped with certain vertex conditions and sufficiently smooth and positive coefficients κ, a. We demonstrate the existence of a unique solution for a general class of vertex conditions and derive the regularity of the solution in the specific case of Kirchhoff vertex conditions. These results are extended to the stochastic setting when f is replaced by Gaussian white noise. For the deterministic and stochastic settings under generalized Kirchhoff vertex conditions, we propose a numerical solution based on a finite element approximation combined with a rational approximation of the fractional power L−β. For the resulting approximation, the strong error is analyzed in the deterministic case, and the strong mean squared error as well as the L2(Γ×Γ)error of the covariance function of the solution are analyzed in the stochastic setting. Explicit rates of convergences are derived for all cases. Numerical experiments for L = κ2 − ∆, κ > 0 are performed to illustrate the *** Codes 35R02, 35A01, 35A02, 60H15, 60H40 Copyright © 2023, The Authors. All rights reserved.

关键词： Errors

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Effects of the selection of characteristic values on the accuracy of results in the COMET method

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Procedia computer science 2020年 176卷 3581-3590页

作者： Bartłomiej Kizielewicz Joanna Kołodziejczyk Research Team on Intelligent Decision Support Systems Department of Artificial Intelligence and Applied Mathematics Faculty of Computer Science and Information Technology West Pomeranian University of Technology in Szczecin ul. Z.ołnierska 49 71-210 Szczecin Poland

This paper describes preliminary research on the relationship between the selection of characteristic values in the COMET method and the accuracy of the final ranking. Simulation studies on three test functions are presented. These functions are references to the conducted simulations and have been taken from the literature. Thanks to their application, human error can be excluded and focus only on methodical error. The presented experiment compares two approaches in determining characteristic values. For each function, 10000 randomly selected sets are generated and based on which the similarity of the ranking calculated by the COMET method with a reference ranking is calculated. The results are interpreted by means of box diagrams. The research showed the high effectiveness of both approaches and was used to determine the next directions for future works.

关键词： Optimization decision-making multi-criteria decision analysis COMET numerical analysis fuzzy logic

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Hyperuniformity order metric of Barlow packings

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Physical Review E 2019年第2期99卷 022111-022111页

作者： T. M. Middlemas F. H. Stillinger S. Torquato Department of Chemistry Department of Physics Princeton Institute for the Science and Technology of Materials and Program in Applied and Computational Mathematics Princeton University New Jersey 08544 USA

The concept of hyperuniformity has been a useful tool in the study of density fluctuations at large length scales in systems ranging across the natural and mathematical sciences. One can rank a large class of hyperuniform systems by their ability to suppress long-range density fluctuations through the use of a hyperuniformity order metric Λ¯. We apply this order metric to the Barlow packings, which are the infinitely degenerate densest packings of identical rigid spheres that are distinguished by their stacking geometries and include the commonly known fcc lattice and hcp crystal. The “stealthy stacking” theorem implies that these packings are all stealthy hyperuniform, a strong type of hyperuniformity, which involves the suppression of scattering up to a wave vector K. We describe the geometry of three classes of Barlow packings, two disordered classes and small-period packings. In addition, we compute a lower bound on K for all Barlow packings. We compute Λ¯ for the aforementioned three classes of Barlow packings and find that, to a very good approximation, it is linear in the fraction of fcc-like clusters, taking values between those of least-ordered hcp and most-ordered fcc. This implies that the value of Λ¯ of all Barlow packings is primarily controlled by the local cluster geometry. These results highlight the special nature of anisotropic stacking disorder, which provides impetus for future research on the development of anisotropic order metrics and hyperuniformity properties.

关键词： Classical statistical mechanics

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Phase equilibrium of water with hexagonal and cubic ice using the SCAN functional

arXiv

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arXiv 2021年

作者： Piaggi, Pablo Miguel Panagiotopoulos, Athanassios Z. Debenedetti, Pablo G. Car, Roberto Department of Chemistry Princeton University PrincetonNJ08544 United States Department of Chemical and Biological Engineering Princeton University PrincetonNJ08544 United States Princeton Institute for the Science and Technology of Materials Princeton University PrincetonNJ08544 United States Department of Physics Princeton University PrincetonNJ08544 United States Program in Applied and Computational Mathematics Princeton University PrincetonNJ08544 United States

Machine learning models are rapidly becoming widely used to simulate complex physicochemical phenomena with ab initio accuracy. Here, we use one such model as well as direct density functional theory (DFT) calculations to investigate the phase equilibrium of water, hexagonal ice (Ih), and cubic ice (Ic), with an eye towards studying ice nucleation. The machine learning model is based on deep neural networks and has been trained on DFT data obtained using the SCAN exchange and correlation functional. We use this model to drive enhanced sampling simulations aimed at calculating a number of complex properties that are out of reach of DFT-driven simulations and then employ an appropriate reweighting procedure to compute the corresponding properties for the SCAN functional. This approach allows us to calculate the melting temperature of both ice polymorphs, the driving force for nucleation, the heat of fusion, the densities at the melting temperature, the relative stability of ice Ih and Ic, and other properties. We find a correct qualitative prediction of all properties of interest. In some cases, quantitative agreement with experiment is better than for state-of-the-art semiempirical potentials for water. Our results also show that SCAN correctly predicts that ice Ih is more stable than ice Ic. Copyright © 2021, The Authors. All rights reserved.

关键词： Ice

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Optimal Control by the Queue with Rate and Quality of Service Depending on the Amount of Harvested Energy as a Model of the Node of Wireless Sensor Network 22nd

Optimal Control by the Queue with Rate and Quality of Servic...

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22nd International Conference on Distributed and computer and Communication Networks, DCCN 2019

作者： Dudin, Alexander Kim, Chesoong Dudin, Sergey Department of Applied Mathematics and Computer Science Belarusian State University Minsk220030 Belarus 6 Miklukho-Maklaya St Moscow117198 Russia Sangji University WonjuKangwon26339 Korea Republic of

ISBN: (纸本)9783030366131

A queueing model with energy harvesting and multi-threshold control by service regimes is analysed. The available service regimes are characterized by the different service rate, requirements to the number of energy units for a request service and the probability of error occurrence during service. Error accounting is vital for adequate modelling wireless networks due to existence of an interference in a transmission thread. The increase of the number of energy units for service of a request implies an opportunity to send a stronger signal what implies the higher transmission rate and a lower probability of error occurrence during transmission. Error occurrence causes the repeated transmission and, therefore, consumption of more energy. Under the fixed parameters of the control strategy, the system dynamics is described by a continuous-time six-dimensional Markov chain. This allows to compute the steady-state distribution of the system states and, then, formulate and solve optimization problems. Numerical results are presented. © Springer Nature Switzerland AG 2019.

关键词： Energy harvesting

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An inverse potential problem for subdiffusion: stability and reconstruction

arXiv

引用

arXiv 2020年

作者： Jin, Bangti Zhou, Zhi Department of Computer Science University College London Gower Street LondonWC1E 6BT United Kingdom Department of Applied Mathematics Hong Kong Polytechnic University Kowloon Hong Kong

In this work, we study the inverse problem of recovering a potential coefficient in the subdiffusion model, which involves a Djrbashian-Caputo derivative of order α ∈ (0,1) in time, from the terminal data. We prove that the inverse problem is locally Lipschitz for small terminal time, under certain conditions on the initial data. This result extends the result in [6] for the standard parabolic case to the fractional case. The analysis relies on refined properties of two-parameter Mittag-Leffler functions, e.g., complete monotonicity and asymptotics. Further, we develop an efficient and easy-to-implement algorithm for numerically recovering the coefficient based on (preconditioned) fixed point iteration and Anderson acceleration. The efficiency and accuracy of the algorithm is illustrated with several numerical examples. Copyright © 2020, The Authors. All rights reserved.

关键词： Inverse problems

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Restricting loop expansions in gauge theories coupled to matter

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Annals of Physics 2021年 434卷

作者： McKeon, D.G.C. Brandt, F.T. Frenkel, J. Martins-Filho, S. Department of Applied Mathematics The University of Western Ontario London Ontario N6A 5B7 Canada Department of Mathematics and Computer Science Algoma University Sault Ste. Marie Ontario P6A 2G4 Canada Instituto de Física Universidade de São Paulo São Paulo SP 05508-090 Brazil

Quantizing any model in which a Lagrange multiplier (LM) field is used to restrict field configurations to those that satisfy the classical equations of motion, leads to at most one-loop radiative corrections. This approach can be used with both the Yang–Mills (YM) and Einstein–Hilbert (EH) action;the resulting theory is both renormalizable and unitary, has a positive energy spectrum and has no negative norm states contributing to physical processes. Although this approach cannot be consistently used with scalar fields alone, scalar fields can be coupled to gauge fields so that loop effects in the gauge sector are restricted to one-loop order in a way that satisfies the usual criterion for a consistent quantum field theory. The tree-level diagrams are those of the classical theory in which the metric couples to the energy–momentum tensor. © 2021 Elsevier Inc.

关键词： Gauge theory Perturbation theory Renormalization

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Load balancing for multi-physics simulations 21

Load balancing for multi-physics simulations

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21st IEEE International Conference on High Performance Computing and Communications, 17th IEEE International Conference on Smart City and 5th IEEE International Conference on Data science and Systems, HPCC/SmartCity/DSS 2019

作者： Chen, Chunsen Li, Kenli Liu, Xu Li, Keqin College of Information Science and Engineering Hunan University Changsha China Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics Beijing China Department of Computer Science State University of New York New York United States

ISBN: (纸本)9781728120584

Multi-physics simulations are usually essential to simplify researches on complex physical phenomena. In this paper, we extend the rectangular partitioning from single-physics simulations to multi-physics simulations. This work presents the Single-rectangle Tightly-coupled algorithm (ST) and Multirectangle Tightly-coupled algorithm (MT) based on rectangular partitioning. The MT algorithm is more flexible and achieves higher load balancing efficiency than the ST algorithm by greedily assigning the remaining unallocated most loaded rectangle to the least loaded processor and assigning k rectangles to each of the processors. To study the effect of machine characteristics on load balancing, the experiments use two types of machine parameters based on Tianhe-2 supercomputer. Inspired by the roofline model, this paper analyzes the relationship among the choice of the load balancing algorithms, the load characteristics of multi-physics application and the features of high performance parallel computer through the comparison experiment of looselycoupled algorithm and tightly-coupled algorithm. In the case of LARED-P, MT algorithm can further reduce the total simulation time compared with the ST algorithm. Through experiments, we show that whether the load balancing algorithm is effective depends on both the load characteristics of multi-physics simulation and the features of high performance parallel computer. © 2019 IEEE.

关键词： Supercomputers

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