检索结果-内蒙古大学图书馆

arXiv 2024年

作者： Hu, Zheyuan Kawaguchi, Kenji Zhang, Zhongqiang Em Karniadakis, George Department of Computer Science National University of Singapore 119077 Singapore Department of Mathematical Sciences Worcester Polytechnic Institute WorcesterMA01609 United States Division of Applied Mathematics Brown University ProvidenceRI02912 United States Advanced Computing Mathematics and Data Division Pacific Northwest National Laboratory RichlandWA United States

Fractional and tempered fractional partial differential equations (PDEs) are effective models of long-range interactions, anomalous diffusion, and non-local effects. Traditional numerical methods for these problems are mesh-based, thus struggling with the curse of dimensionality (CoD). Physics-informed neural networks (PINNs) offer a promising solution due to their universal approximation, generalization ability, and mesh-free training. In principle, Monte Carlo fractional PINN (MC-fPINN) estimates fractional derivatives using Monte Carlo methods and thus could lift CoD. However, this may cause significant variance and errors, hence affecting convergence;in addition, MC-fPINN is sensitive to hyperparameters. In general, numerical methods and specifically PINNs for tempered fractional PDEs are under-developed. Herein, we extend MC-fPINN to tempered fractional PDEs to address these issues, resulting in the Monte Carlo tempered fractional PINN (MC-tfPINN). To reduce possible high variance and errors from Monte Carlo sampling, we replace the one-dimensional (1D) Monte Carlo with 1D Gaussian quadrature, applicable to both MC-fPINN and MC-tfPINN. We validate our methods on various forward and inverse problems of fractional and tempered fractional PDEs, scaling up to 100,000 dimensions. Our improved MC-fPINN/MC-tfPINN using quadrature consistently outperforms the original versions in accuracy and convergence speed in very high dimensions. © 2024, CC BY.

关键词： Monte Carlo methods

来源：评论

学校读者我要写书评

暂无评论

RANDOMLY PERTURBED ERGODIC AVERAGES

引用

Proceedings of the American Mathematical Society, Series B 2021年第19期8卷 224-244页

作者： Choi, Jaeyong Reinhold-Larsson, Karin DIVISION OF MATHEMATICS AND COMPUTER SCIENCE (DMACS) COLLEGE OF NATURAL AND APPLIED SCIENCES (CNAS) UNIVERSITY OF GUAM (UOG) ALS 319 UOG STATION MANGILAO 96923 Guam DEPARTMENT OF MATHEMATICS AND STATISTICS UNIVERSITY AT ALBANY SUNY ALBANY 12222 NY United States

We consider a class of random ergodic averages, containing averages along random non–integer sequences. For such averages, Cohen & Cuny obtained ∫ uniform universal pointwise convergence for functions in L² with max(1, log(1 + |t|))dμf < ∞ via a uniform estimation of trigonometric poly-nomials. ∫ We extend this result to L² functions satisfying the weaker condition max(1, log log(1+|t|))dμf < ∞. We also prove that uniform universal point-wise convergence in L² holds for the corresponding smoothed random averages or for random averages whose kernels exhibit sufficient decay at infinity. © 2021 by the authors under Creative Commons Attribution-Nonommerial 3.0 Liense (CC BY NC 3.0).

关键词： Random ergodic averages universal convergence

来源：评论

学校读者我要写书评

暂无评论

Process Flow and Design Optimization of a Microbolometer

Process Flow and Design Optimization of a Microbolometer

引用

International Conference on Electrical Information and Communication Technology (EICT)

作者： Mukti Rana Abdulaziz T. Almaktoom Division of Physics Engineering Mathematics and Computer Sciences and Optical Science Center for Applied Research Delaware State University Dover USA Department of Operations and Supply Chain Management Jeddah Kingdom of Saudi Arabia

Microbolometers using a-Si 0.15 Ge 0.85 O 0.0236 thin films were fabricated using radio frequency magnetron sputtering and lift of technique. When a 200 nm-thick and 40 × 40 μm 2 Si 0.15 Ge 0.85 O 0.0236 pixels on top of the electrode arm was used, it was observed that the electrode arms and the pixels were wrapped after they were subjected to the surface micromachining process. In order to fix this problem, the design and process flow of the microbolometer array were optimized to obtain mechanically stable microbolometers. We used Ge x Si 1-x O y , silicon nitride, NiCr and silicon nitride to provide mechanical strength and stability to the microbolometer pixels. With the modified structure and process flow optimization it was found that the detectors of bridge structure were suspended on top of the substrate. We performed forming gas passivation at 250 o C for seven hours to minimize the 1/f-noise. A temperature coefficient of resistance (TCR) of 4.8%/K was obtained at 295 K. We obtained the highest detectivity and responsivity values 1 × 10 4 V/W and 8.3 × 10 6 cm-Hz 1/2 /W.

关键词：

来源：评论

学校读者我要写书评

暂无评论

Butterfly-Accelerated Solution of Coupled Volume Integral and Hydrodynamic Equations

Butterfly-Accelerated Solution of Coupled Volume Integral an...

引用

USNC-URSI Radio science Meeting (Joint with AP-S Symposium)

作者： Doolos Aibek Uulu Yang Liu Abdulkadir C. Yucel Hakan Bagci Department of Mathematics and Natural Sciences University of Central Asia (UCA) Naryn Kyrgyzstan Applied Mathematics & Computational Research Division Lawrence Berkeley National Laboratory Berkeley USA School of Electrical and Electronic Engineering Nanyang Technological University (NTU) Singapore Computer Electrical and Mathematical Science and Engineering Division King Abdullah University of Science and Technology (KAUST) Thuwal Saudi Arabia

ISBN: (数字)9789463968119

ISBN: (纸本)9798350359497

In recent years, advancements in plasmonic devices have enabled the localization of electromagnetic fields at subwavelength scales, contributing to breakthroughs in various scientific and engineering fields (J. C. Ndukaife, et al., ACS Nano, 2014,8,9,9035-9043). These structures are often made of metals and their electric properties are typically represented by the classical Drude model (S. A. Maier, 2007, Springer, New York). As the size of the plasmonic structures approaches the nanoscale, the classical Drude model falls short in explaining the collective movement of free electrons in metals. The interaction between moving charges and the electromagnetic fields can be described by a coupled system of the Maxwell and hydrodynamic equations (X. Zheng, et al., IEEE Trans. Antennas Propag., 2018,66,9, 4759-4771).

关键词： Location awareness Conferences Integral equations Metals Plasmons Hydrodynamics Mathematical models

来源：评论

学校读者我要写书评

暂无评论

Forward Brillouin Point Sensor in a Multi-Core Fiber 27

Forward Brillouin Point Sensor in a Multi-Core Fiber

引用

27th International Conference on Optical Fiber Sensors, OFS 2022

作者： Shemer, Keren Bashan, Gil Zehavi, Elad Diamandi, Hilel Hagai Bernstein, Alon Sharma, Kavita London, Yosef Barrera, David Sales, Salvador Zadok, Avi Faculty of Engineering and Institute for Nano-Technology and Advanced Materials Bar-Ilan University Ramat-Gan5290002 Israel Department of Computer Science and Applied Mathematics Weizmann Institute of Science Rehovot7610001 Israel Currently with Applied Physics Division Soreq NRC Yavne81800 Israel Photonics Research Labs Universitat Politècnica de València Valencia46022 Spain

Forward Brillouin point sensing is demonstrated in a multi-core fiber. Acoustic waves are stimulated by light in one core and monitored using a grating in another. Measurements distinguish between ethanol and water ou... 详细信息

ISBN: (纸本)9781957171142

关键词： Effective refractive index Fiber optic sensors Forward scattering Multicore fibers Phase modulation Tunable diode lasers

来源：评论

学校读者我要写书评

暂无评论

Modeling of Measurement Error in Financial Returns Data

arXiv

引用

arXiv 2024年

作者： Jasra, Ajay Maama, Mohamed Mijatović, Aleksandar School of Data Science The Chinese University of Hong Kong Shenzhen China Applied Mathematics and Computational Science Program Computer Electrical and Mathematical Sciences and Engineering Division King Abdullah University of Science and Technology Thuwal23955-6900 Saudi Arabia Department of Statistics University of Warwick United Kingdom

In this paper we consider the modeling of measurement error for fund returns data. In particular, given access to a time-series of discretely observed log-returns and the associated maximum over the observation period, we develop a stochastic model which models the true log-returns and maximum via a Lévy process and the data as a measurement error there-of. The main technical difficulty of trying to infer this model, for instance Bayesian parameter estimation, is that the joint transition density of the return and maximum is seldom known, nor can it be simulated exactly. Based upon the novel stick breaking representation of [12] we provide an approximation of the model. We develop a Markov chain Monte Carlo (MCMC) algorithm to sample from the Bayesian posterior of the approximated posterior and then extend this to a multilevel MCMC method which can reduce the computational cost to approximate posterior expectations, relative to ordinary MCMC. We implement our methodology on several applications including for real data. Copyright © 2024, The Authors. All rights reserved.

关键词： Markov chains

来源：评论

学校读者我要写书评

暂无评论

Deep learning models for early and accurate diagnosis of ventilator-associated pneumonia in mechanically ventilated neonates

引用

computers in Biology and Medicine 2025年 189卷 109942-109942页

作者： Hsu, Jen-Fu Lin, Ying-Chih Lin, Chun-Yuan Chu, Shih-Ming Cheng, Hui-Jun Xu, Fan-Wei Huang, Hsuan-Rong Liao, Chen-Chu Fu, Rei-Huei Tsai, Ming-Horng Division of Neonatology and Pediatric Hematology/Oncology Department of Pediatrics Chang Gung Memorial Hospital Yunlin Taiwan Division of Pediatric Neonatology Department of Pediatrics Chang Gung Memorial Hospital Taoyuan Taiwan College of Medicine Chang Gung University Taoyuan Taiwan Department of Computer Science and Information Engineering Asia University Taichung Taiwan Department of Applied Mathematics Feng Chia University Taichung Taiwan Department of Artificial Intelligence Application Minth University of Science and Technology HsinChu County Taiwan

Background: Early and accurate confirmation of critically ill neonates with a suspected diagnosis of ventilator-associated pneumonia (VAP) can optimize the therapeutic strategy and avoid unnecessary use of empirical antibiotics. We aimed to examine whether deep learning (DL) methods can assist the diagnosis of VAP of intubated neonates in the neonatal intensive care unit (NICU). Methods: A total of 670 neonates with mechanical ventilation were prospectively observed in a tertiary-level NICU in Taiwan between October 2017 and March 2022, during which image data were collected. All neonates with clinically suspected VAP were enrolled, and various DL methods were used to test the prediction ability of VAP diagnosis. The accuracy, precision, sensitivity, specificity, F1-score, and area under curves (AUCs) of several DL methods were compared. Results: A total of 900 chest X-ray images derived from 670 neonates with VAP and/or bronchopulmonary dysplasia (BPD) were enrolled, including 399 images from patients with definite diagnosis of VAP based on the strict criteria and 501 images from neonates without VAP. Compared with conventional DNN models such as ResNet, VGG, DenseNet, the RegNetX80 achieved the best specificity of 0.8378, which facilitates a low false positive rate. For accurate diagnosis of neonatal VAP, a combinatorial model of ResNet50 and RegNetX80, created through ensemble learning, further enhanced the AUC to 0.8023 for neonates with VAP on mechanical ventilation. In addition, the consistent XAI results in the left-lower region of chest X-ray image provided informative feedback and increased confidence to AI-assisted doctors. Conclusions: Deep learning methods are applicable with good predictive accuracy using chest X-ray images to help diagnosis of VAP in the NICU, which can help clinicians make decisions regarding the choices of empiric antibiotics for critically ill neonates. Future prospective trials are warranted to document its clinical usefulness and

关键词： Contrastive Learning

来源：评论

学校读者我要写书评

暂无评论

Correction to: Global Well-Posedness for the Thermodynamically Refined Passively Transported Nonlinear Moisture Dynamics with Phase Changes

引用

Journal of Nonlinear science 2023年第5期33卷 1-2页

作者： Hittmeir, Sabine Klein, Rupert Li, Jinkai Titi, Edriss S. Fakultät für Mathematik Universität Wien Wien Austria FB Mathematik and Informatik Freie Universität Berlin Berlin Germany South China Research Center for Applied Mathematics and Interdisciplinary Studies School of Mathematical Sciences South China Normal University Guangzhou People’s Republic of China Department of Mathematics Texas A &M University College Station USA Department of Applied Mathematics and Theoretical Physics University of Cambridge Cambridge UK Department of Computer Science and Applied Mathematics Weizmann Institute of Science Rehovot Israel

来源：评论

学校读者我要写书评

暂无评论

A Traffic Evacuation Model for Enhancing Resilience During Railway Disruption

arXiv

引用

arXiv 2025年

作者： Ge, Hangli Yang, Xiaojie Chen, Jinyu Flammini, Francesco Koshizuka, Noboru Interfaculty Initiative in Information Studies The University of Tokyo Tokyo Japan Graduate School of Interdisciplinary Information Studies The University of Tokyo Tokyo Japan Department of Mathematics and Computer Science Ulisse Dini University of Florence Florence Italy IDSIA USI-SUPSI University of Applied Sciences and Arts of Southern Switzerland Lugano Switzerland

This paper introduces a traffic evacuation model for railway disruptions to improve resilience. The research focuses on the problem of failure of several nodes or lines on the railway network topology. We proposed a holistic approach that integrates lines of various operator companies as well as external geographical features of the railway system. The optimized evacuation model was mathematically derived based on matrix computation using nonlinear programming. The model also takes into account the capacity of the surrounding evacuation stations, as well as the travel cost. Moreover, our model can flexibly simulate disruptions at multiple stations or any number of stations and lines, enhancing its applicability. We collected the large-scale railway network of the Greater Tokyo area for experimentation and evaluation. We simulated evacuation plans for several major stations, including Tokyo, Shinjuku, and Shibuya. The results indicate that the evacuation passenger flow (EPF) and the average travel time (ATT) during emergencies were optimized, staying within both the capacity limits of the targeted neighboring stations and the disruption recovery time. © 2025, CC BY.

关键词： Nonlinear programming

来源：评论

学校读者我要写书评

暂无评论

Motility Induced Phase Separation and Frustration in Active Matter Swarmalators

arXiv

引用

arXiv 2023年

作者： Adorjáni, B. Libál, A. Reichhardt, C. Reichhardt, C.J.O. Mathematics and Computer Science Department Babeş-Bolyai University Cluj400084 Romania Theoretical Division Center for Nonlinear Studies Los Alamos National Laboratory Los AlamosNM87545 United States

We introduce a system of active matter swarmalators composed of elastically interacting run- and-tumble active disks with an internal phase i. The disks experience an additional attractive or repulsive force with neighboring disks depending upon their relative difference in i. In the absence of the internal phase, the system forms a Motility-Induced Phase Separated (MIPS) state, but when the swarmalator interactions are present, a wide variety of other active phases appear depending upon whether the interaction is attractive or repulsive and whether the particles act to synchronize or anti-synchronize their internal phase values. These include a gas-free gel regime, arrested clusters, a labyrinthine state, a regular MIPS state, a frustrated MIPS state for attractive anti-synchronization, and a superlattice MIPS state for attractive synchronization. Copyright © 2023, The Authors. All rights reserved.

关键词： Phase separation

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：