检索结果-内蒙古大学图书馆

arXiv 2022年

作者： Fan, Xiaohong Yang, Yin Chen, Ke Zhang, Jianping Dong, Ke The School of Mathematics and Computational Science Xiangtan University Key Laboratory of Intelligent Computing & Information Processing of Ministry of Education Xiangtan411105 China The School of Mathematics and Computational Science Xiangtan University Hunan National Applied Mathematics Center Hunan Key Laboratory for Computation and Simulation in Science and Engineering Xiangtan411105 China Centre for Mathematical Imaging Techniques Department of Mathematical Sciences The University of Liverpool Merseyside LiverpoolL6972L United Kingdom The School of Mathematics and Computational Science Xiangtan University Hunan National Applied Mathematics Center Key Laboratory of Intelligent Computing & Information Processing of Ministry of Education Xiangtan411105 China Department of Radiation Oncology Xiangtan Central Hospital Xiangtan411101 China

Although existing deep learning compressed-sensing-based Magnetic Resonance Imaging (CS-MRI) methods have achieved considerably impressive performance, explainability and generalizability continue to be challenging for such methods since the transition from mathematical analysis to network design not always natural enough, often most of them are not flexible enough to handle multi-sampling-ratio reconstruction assignments. In this work, to tackle explainability and generalizability, we propose a unifying deep unfolding multi-sampling-ratio interpretable CS-MRI framework. The combined approach offers more generalizability than previous works whereas deep learning gains explainability through a geometric prior module. Inspired by the multigrid algorithm, we first embed the CSMRI-based optimization algorithm into correction-distillation scheme that consists of three ingredients: pre-relaxation module, correction module and geometric prior distillation module. Furthermore, we employ a condition module to learn adaptively step-length and noise level, which enables the proposed framework to jointly train multi-ratio tasks through a single model. The proposed model not only compensates for the lost contextual information of reconstructed image which is refined from low frequency error in geometric characteristic k-space, but also integrates the theoretical guarantee of model-based methods and the superior reconstruction performances of deep learning-based methods. Therefore, it can give us a novel perspective to design biomedical imaging networks. Numerical experiments show that our framework outperforms state-of-the-art methods in terms of qualitative and quantitative evaluations. Our method achieves 3.18 dB improvement at low CS ratio 10% and average 1.42 dB improvement over other comparison methods on brain dataset using Cartesian sampling mask. Copyright © 2022, The Authors. All rights reserved.

关键词： Distillation

来源：评论

学校读者我要写书评

暂无评论

Are Electric Vehicles Greener than Hybrid Electric Vehicles in Carsharing? Insights from Large-Scale Multi-Objective simulation-Optimization

SSRN

引用

SSRN 2024年

作者： Li, Yan Hu, Lu Li, Haobin Chew, Ek Peng Li, Hao Zhu, Juanxiu Department of Industrial Systems Engineering and Management National University of Singapore Singapore Centre of Excellence in Modelling and Simulation for Next Generation Ports National University of Singapore Singapore School of Transportation and Logistics Southwest Jiaotong University Chengdu China School of Traffic and Transportation Engineering Changsha University of Science and Technology Changsha China Hunan Key Laboratory of Smart Roadway and Cooperative Vehicle Infrastructure Systems Changsha University of Science and Technology Changsha China School of Management Xihua University Chengdu China

Hybrid electric vehicles (HEVs) are perceived as transitional products bridging the gap between fueled vehicles and electric vehicles (EVs) because people intuitively believe that EVs are more environmentally friendly than HEVs. But is this perception true in the context of carsharing services (CSSs)? This paper pioneers a general large-scale multi-objective simulation-optimization (MOSO) method to explore the values of deploying HEVs in CSSs. We firstly develop a physically logical simulation model, emulating operations of CSSs and capturing mesoscopic dynamics of shared vehicles in a link-based traffic network. This model adopts an event-driven discrete-event mechanism, enhancing efficiency while maintaining high fidelity. Subsequently, we design a simulation-optimization framework aimed at achieving Pareto optimality by jointly optimizing station capacity, fleet size, and trip pricing. The goal is twofold: to maximize operational profits and to minimize carbon emissions, thereby quantitatively analysing the potential of shared HEVs (SHEVs). To tackle the high-dimensional MOSO problem, we propose a general algorithm that incorporates the multiple gradient descent algorithm with the simultaneous perturbation stochastic approximation algorithm. Furthermore, we derive its analytical expression for bi-objective optimization problems. We theoretically prove and practically demonstrate its strong global convergence. The efficiency of this method was validated through large-scale computational experiments conducted in Chengdu, Sichuan Province, involving 66,710 decision variables. These experiments showcased the method's superiority over existing MOSO algorithms. Several groups of sensitivity experiments focusing on vehicle types and traffic scenarios reveal some interesting findings. (1) Regardless of the increase in travel distances, SHEVs, which can be viewed as shared EVs (SEVs) without range anxiety (RA), continue to primarily rely on electricity rather than fuel fo

关键词： Stochastic systems

来源：评论

学校读者我要写书评

暂无评论

The Control Design of Space Flying Net Robot System Based on RBF Network

The Control Design of Space Flying Net Robot System Based on...

引用

Chinese Automation Congress (CAC)

作者： Xu Zhang Yuanhe Liu Yan’gang Liang Kebo Li Hunan Key Laboratory of Intelligent Planning and Simulation for Aerospace Missions College of Aerospace Science and Engineering National University of Defense Technology Changsha China

ISBN: (纸本)9781665426480

Space Flying Net Robot System (SFNRS) is a new capture method of space debris. In this paper, the SFNRS dynamic equations are established by using the lumped mass method. The previous studies about controller design assumed that the mass of the maneuvering unit in SFNRS is known and a constant while it is unknown in fact. In addition, the upper boundary of tension in the space net is often assumed as a known constant, but it is difficult to get the value. In this paper, the radial basis function (RBF) network is used to design a controller in order to overcome the shortcomings above. Finally, the simulation is carried out to verify the effectiveness and the robustness of the proposed method.

关键词： Upper bound Control design Space debris simulation Radial basis function networks Aerospace electronics Robustness

来源：评论

学校读者我要写书评

暂无评论

An Improved Third-order CWENO-Z Scheme at critical points 2

An Improved Third-order CWENO-Z Scheme at critical points

引用

2019 2nd International Conference on Advanced Materials, Intelligent Manufacturing and Automation, AMIMA 2019

作者： Tang, Shujiang Li, Mingjun Han, Shuang School of Mathematics and Computational Science Xiangtan University Xiangtan Hunan411105 China Hunan Key Laboratory for Computation and Simulation in Science and Engineering Xiangtan Hunan411105 China

In this paper, by modifying the smoothness factor of the third-order CWENO scheme, we present the two-parameter CWENO-NZ3 scheme to improve accuracy at critical points. We selected some classical examples for numerical simulation, such as one-dimensional Sod shock tube, Shock-entropy wave interaction, Riemann problem with strong discontinuity and Rayleigh-Taylor instability problem. Numerically comparing with the classical third-order CWENO schemes, it is found that the improved schemes not only improve accuracy and resolution at the extreme points, but also reduce dissipation. © Published under licence by IOP Publishing Ltd.

关键词： Shock tubes

来源：评论

学校读者我要写书评

暂无评论

A Two-level Overlapping Schwarz Method Using Energy Minimizing Multiscale Finite Element Functions 25th

A Two-level Overlapping Schwarz Method Using Energy Minimizi...

引用

25th International Conference on Domain Decomposition Methods in science and engineering, DD 2018

作者： Kim, Hyea Hyun Chung, Eric T. Wang, Junxian Department of Applied Mathematics and Institute of Natural Sciences Kyung Hee University Region Korea Republic of Department of Mathematics The Chinese University of Hong Kong SAR Hong Kong Hunan Key Laboratory for Computation and Simulation in Science and Engineering School of Mathematics and Computational Science Xiangtan University Xiangtan China

ISBN: (纸本)9783030567491

关键词： Finite element method

来源：评论

学校读者我要写书评

暂无评论

AN ADAPTIVE FINITE ELEMENT METHOD FOR TWO-DIMENSIONAL ELLIPTIC EQUATIONS WITH LINE DIRAC SOURCES

arXiv

引用

arXiv 2021年

作者： Cao, Huihui Li, Hengguang Yi, Nianyu Yin, Peimeng Hunan Key Laboratory for Computation and Simulation in Science and Engineering School of Mathematics and Computational Science Xiangtan University Hunan Xiangtan411105 China Wayne State University Department of Mathematics DetroitMI48202 United States Multiscale Methods and Dynamics Group Computer Science and Mathematics Division Oak Ridge National Laboratory Oak RidgeTN37831 United States

In this paper, we propose a novel adaptive finite element method for an elliptic equation with line Dirac delta functions as a source term. We first study the well-posedness and global regularity of the solution in the whole domain. Instead of regularizing the singular source term and using the classical residual-based a posteriori error estimator, we propose a novel a posteriori estimator based on an equivalent transmission problem with zero source term and nonzero flux jumps on line fractures. The transmission problem is defined in the same domain as the original problem excluding on line fractures, and the solution is therefore shown to be more regular. The estimator relies on meshes conforming to the line fractures and its edge jump residual essentially uses the flux jumps of the transmission problem on line fractures. The error estimator is proven to be both reliable and efficient, an adaptive finite element algorithm is proposed based on the error estimator and the bisection refinement method. Numerical tests show that quasi-optimal convergence rates are achieved even for high order approximations and the adaptive meshes are only locally refined at singular points. © 2021, CC BY-NC-ND.

关键词： Fracture

来源：评论

学校读者我要写书评

暂无评论

An improved functional dependency network model for information systems effectiveness analysis 2020

An improved functional dependency network model for informat...

引用

2020 International Conference on Wireless Communication and Sensor Networks, icWCSN 2020

作者： Luo, Aimin Yi, Shuanghui Liu, Junxian Kou, Yuxiao Gao, Lanlan Zhang, Mengmeng Science and Technology on Information Systems Engineering Laboratory National University of Defense Technology Changsha Hunan410073 China National Key Laboratory for Complex System Simulation Beijing China Academy of Military Science of the PLA Beijing100000 China

ISBN: (纸本)9781450377638

To address the limitations of the FDNA approach, in this paper, we analyze the dependency of the receiver node on the feeder nodes as well as the impact of the node's operability level on the system effectiveness, and improve the FDNA approach. We also propose a computing method for system effectiveness based on an improved FDNA model, and conduct relevant case verification. © 2020 ACM.

关键词： Information systems

来源：评论

学校读者我要写书评

暂无评论

Developing Finite Element Methods for Simulating Transformation Optics Devices with Metamaterials

引用

Communications in computational Physics 2019年第1期25卷 135-154页

作者： Wei Yang Jichun Li Yungqing Huang Bin He Hunan Key Laboratory for Computation and Simulation in Science and Engineering Xiangtan UniversityXiangtan 411105P.R.China Department of Mathematical Sciences University of Nevada Las VegasLas VegasNevada 89154-4020USA

In this paper,we first develop the mathematical modeling equations for wave propagation in several transformation optics devices,including electromagnetic concentrator,rotator and *** we propose the corresponding finite element time-domain methods for simulating wave propagation in these transformation optics *** implement the proposed algorithms and our numerical results demonstrate the effectiveness of our modeling *** our best knowledge,this is the first work on time-domain finite element simulation carried out for the electromagnetic concentrator,rotator and splitter.

关键词： Maxwell’s equations finite element time-domain methods edge elements transfor-mation optics

来源：评论

学校读者我要写书评

暂无评论

New Result on Interception of Stationary Targets at Arbitrary Time-Varying Velocity

arXiv

引用

arXiv 2021年

作者： Yuanhe, Liu Kebo, Li Yan’gang, Liang College of Aerospace Science and Engineering National University of Defense Technology Changsha410072 China Hunan Key Laboratory of Intelligent Planning and Simulation for Aerospace Missions Changsha410072 China

In this paper, some new results on time-varying missile against a stationary target using pure proportional navigation (PPN) are developed in the planar interception problem. First, the relative motion equation is established in arc-length domain based on the differential geometry theory, which eliminates the influence of time-varying missile speed. Then, the closed-form solution of time-varying speed missile intercepting stationary target with PPN is deduced, and the interception performance is analyzed. Additionally, considering the missile maneuvering acceleration limit, the capture region of time-varying speed missile is analyzed. Finally, the results derived in this paper are verified by numerical simulation analysis for various scenarios. © 2021, CC BY-NC-SA.

关键词： Equations of motion

来源：评论

学校读者我要写书评

暂无评论

Boosting catalytic oxidation of H₂S over activated carbon optimized by the synergistic effect of rich defects and nitrogen sites

引用

Surfaces and Interfaces 2025年 68卷

作者： Liu, Xin Zhao, Minghui Liu, Dongxu Yang, Jianxiao Han, Yinghui Sultana, Rabia Mohamed, Yasser M.A. Nazer, Hossam A.El Elnazer, Ahmed A. Zhang, Xin College of Ecology and Environment Nanjing Forestry University Nanjing 210037 China College of Resources and Environment University of Chinese Academy of Sciences Beijing 101408 China Hunan Province Key Laboratory for Advanced Carbon Materials and Applied Technology College of Materials Science and Engineering Hunan University Changsha 410082 China State Key Joint Laboratory of Environment Simulation and Pollution Control Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Beijing 100085 China Photochemistry Department National Research Centre Dokki Giza 12622 Egypt Geological Sciences Department National Research Centre Dokki Giza 12622 Egypt

H2S selective catalytic oxidation has been considered as the most efficient method for the removal of residual H2S in Claus tail gas. Carbon materials were regarded as a promising candidate for the reaction. However, ... 详细信息

H₂S selective catalytic oxidation has been considered as the most efficient method for the removal of residual H₂S in Claus tail gas. Carbon materials were regarded as a promising candidate for the reaction. However, its performance was rather poor. This study implemented an approach to enhance the catalytic performance of activated carbon catalysts through the synergy effect of rich defects and nitrogen species. The addition of phenanthroline, a nitrogen-containing compound increased the nitrogen content in the carbon framework, and annealing under an NH₃ atmosphere generated abundant surface defects. The pyridinic nitrogen species and defects facilitated the adsorption of H₂S. Moreover, the defects can also promote the generation of superoxide radicals, further resulting in the production of SO₂ and improving the catalytic performance through the Claus reaction. The best catalytic performance was achieved with the C-N-5 catalyst, and the sulfur yield was maintained higher than 95 % even at 220 °C. Furthermore, the oxygen-containing groups on the surface of carbon materials were the reactive oxygen species and the reaction obeyed the MvK mechanism, i.e., the adsorbed H₂S reacted with the oxygen-containing groups to form elemental sulfur, while the consumed oxygen-containing groups were regenerated by molecular oxygen. © 2025

关键词： Activated carbon Defects H2S catalytic oxidation Nitrogen doping Reaction mechanism

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：