检索结果-内蒙古大学图书馆

A short note on plain convergence of adaptive least-squares finite element methods

COMPUTERS & MATHEMATICS WITH APPLICATIONS 2020年第6期80卷 1619-1632页

作者： Fuhrer, Thomas Praetorius, Dirk Pontificia Univ Catolica Chile Fac Matemat Santiago Chile TU Wien Inst Anal & Sci Comp Wiedner Hauptstr 8-10 A-1040 Vienna Austria

We show that adaptive least-squares finite element methods driven by the canonical least-squares functional converge under weak conditions on PDE operator, mesh refinement, and marking strategy. Contrary to prior works, our plain convergence does neither rely on sufficiently fine initial meshes nor on severe restrictions on marking parameters. Finally, we prove that convergence is still valid if a contractive iterative solver is used to obtain the approximate solutions (e.g., the preconditioned conjugate gradient method with optimal preconditioner). The results apply within a fairly abstract framework which covers a variety of model problems. (C) 2020 Elsevier Ltd. All rights reserved.

关键词： Least squares finite element methods adaptive algorithm Convergence

来源：评论

学校读者我要写书评

暂无评论

adaptive Blind Stokes-Space Based Equalizer for RSOP in SV-DD Systems With High Chromatic Dispersion Tolerance

IEEE PHOTONICS JOURNAL

引用

IEEE PHOTONICS JOURNAL 2020年第2期12卷 1-13页

作者： Jin, Yu Li, Di Yi, Pin Cheng, Mengfan Fu, Songnian Tang, Ming Liu, Deming Deng, Lei Huazhong Univ Sci & Technol Wuhan Natl Lab Optoelect Wuhan 430074 Peoples R China Huazhong Univ Sci & Technol Sch Opt & Elect Informat Wuhan 430074 Peoples R China

Polarization de-multiplexing becomes challenging in Stokes vector-direct detection (SV-DD) systems, especially when the rotation of state of polarization (RSOP) and fiber chromatic dispersion (CD) are induced. To address this issue, an adaptive blind RSOP equalizer based on Stokes space is proposed. After theoretical analysis, it is found that the distribution of transmitted signals in Stokes space keeps a paraboloid. Based on this analysis, an adaptive scheme is proposed to track the symmetry axis of paraboloid for the first time. It is worth noticing that not only CD but also high-order modulation formats could not change the paraboloid distribution. Therefore, our algorithm has strong robustness to CD and good suitability for SV-DD systems with different modulation formats. In our simulation, the conventional Stokes space-based method and the training sequences (TS) method are both evaluated for comparison. The results show that our scheme can track RSOP of 20 Mrad/s and 8 Mrad/s at hard-decision forward error correction threshold in 28 Gbaud 4-level quadrature amplitude modulation (4-QAM) and 16-QAM SV-DD systems after 100 km fiber transmission, respectively. No additional computational complexity is required compared to the conventional Stokes space-based method. Moreover, compared to the TS-based method, there is no need to know the actual channel information, contributing to good flexibility.

关键词： Stokes vector direct detection rotation of sate of polarization Stokes space chromatic dispersion adaptive algorithm

来源：评论

学校读者我要写书评

暂无评论

An adaptive Method for Reducing Second-order Dynamical Systems

引用

IFAC-PapersOnLine 2022年第20期55卷 337-342页

作者： Quirin Aumann Gerhard Müller Technical University of Munich Chair of Structural Mechanics Arcisstr. 21 80333 Munich Germany Chemnitz University of Technology Research Group Mathematics in Industry and Technology Reichenhainer Str. 41 09126 Chemnitz Germany

We present a method to compute reduced models of second-order dynamical systems valid in a desired frequency range without specifying the order of the reduced models prior to the reduction process. The approach is based on a second-order variant of the iterative rational Krylov algorithm (SO-IRKA) and exploits the fact, that an eigenvalue decomposition of the reduced second-order system yields twice as many eigenvalues as its order. By selecting all eigenvalues whose mirror images lie in the frequency range in which the reduced model should be valid during each iteration of SO-IRKA, the order of the reduced model is growing (or shrinking) until a reasonable reduced order is found. Additionally, we show that performing the SO-IRKA optimization steps on an intermediate-sized model yields accurate reduced-order models while the computational cost of the reduction phase is reduced. We show the effectiveness of the proposed method by applying it to numerical models of a vibro-acoustic system.

关键词： Model order reduction Second-order systems adaptive algorithm Dynamic systems Vibration

来源：评论

学校读者我要写书评

暂无评论

Cooperative Fault-Tolerant Control of Microgrids Under Switching Communication Topology

引用

IEEE TRANSACTIONS ON SMART GRID 2020年第3期11卷 1866-1879页

作者： Afshari, Amir Karrari, Mehdi Baghaee, Hamid Reza Gharehpetian, G. B. Karrari, Shahab Amirkabir Univ Technol Dept Elect Engn Tehran 15914 Iran Karlsruhe Inst Technol Inst Tech Phys D-76344 Eggenstein Leopoldshafen Germany

In this paper, to address the problem of multiple actuator faults in autonomous AC microgrids, a cooperative fault-tolerant control (CFTC) algorithm is designed. The proposed algorithm is responsible for the potential heterogeneous faults in units' actuators, like loss of effectiveness (LOE) and unknown bias faults. Furthermore, the communication network is considered as a directed switching graph, which can be viewed as an unreliable network and makes the CFTC problem more challenging. Also, in addition to the distributed generation (DG) units, we consider the presence of distributed energy storage (DES) systems that operate in the islanded microgrid. In addition to the voltage and frequency regulation, it is required to balance the state of charge (SoC) of DESs to achieve accurate active power-sharing. Finally, to evaluate the performance of the proposed CFTC algorithm, simulation studies are carried out on a test microgrid system in MATLAB/Simulink environment, and the results are compared with several previously-reported methods. Simulation results and comparison with other previously-reported techniques reveal the effectiveness and accuracy of the proposed method in regulating microgrid voltage and frequency, balancing of SoC, and providing accurate proportional active power-sharing.

关键词： Microgrids Circuit faults Topology Switches Voltage control Actuators Distributed secondary control actuator fault adaptive algorithm distributed estimation fault-tolerant control switching topology state of charge

来源：评论

学校读者我要写书评

暂无评论

Accurate Fiducial Point Detection Using Haar Wavelet for Beat-by-Beat Blood Pressure Estimation

引用

IEEE JOURNAL OF TRANSLATIONAL ENGINEERING IN HEALTH AND MEDICINE 2020年 8卷 1页

作者： Singla, Muskan Azeemuddin, Syed Sistla, Prasad Int Inst Informat Technol Ctr VLSI & Embedded Syst Technol Hyderabad 500032 India Care Hosp Care Fdn Hyderabad 500034 India

Pulse Arrival Time (PAT) derived from Electrocardiogram (ECG) and Photoplethysmogram (PPG) for cuff-less Blood Pressure (BP) measurement has been a contemporary and widely accepted technique. However, the features extracted for it are conventionally from an isolated pulse of ECG and PPG signals. As a result, the estimated BP is intermittent. Objective: This paper presents feature extraction from each beat of ECG and PPG signals to make BP measurements uninterrupted. These features are extracted by employing Haar transformation to adaptively attenuate measurement noise and improve the fiducial point detection precision. Method: the use of only PAT feature as an independent variable leads to an inaccurate estimation of either Systolic Blood Pressure (SBP) or Diastolic Blood Pressure (DBP) or both. We propose the extraction of supplementary features that are highly correlated to physiological parameters. Concurrent data was collected as per the Association for the Advancement of Medical Instrumentation (AAMI) guidelines from 171 human subjects belonging to diverse age groups. An adaptive Window Wavelet Transformation (AWWT) technique based on Haar wavelet transformation has been introduced to segregate pulses. Further, an algorithm based on log-linear regression analysis is developed to process extracted features from each beat to calculate BP. Results: The mean error of 0.43 and 0.20 mmHg, mean absolute error of 4.6 and 2.3 mmHg, and Standard deviation of 6.13 and 3.06 mmHg is achieved for SBP and DBP respectively. Conclusions: The features extracted are highly precise and evaluated BP values are as per the AAMI standards. Clinical Impact: This continuous real-time BP monitoring technique can be useful in the treatment of hypertensive and potential-hypertensive subjects.

关键词： adaptive algorithm blood pressure detection algorithm electrocardiography feature extraction photoplethysmography regression analysis signal processing wavelet transforms

来源：评论

学校读者我要写书评

暂无评论

Fast adaptive Gradient RBF Networks For Online Learning of Nonstationary Time Series

引用

IEEE TRANSACTIONS ON SIGNAL PROCESSING 2020年 68卷 2015-2030页

作者： Liu, Tong Chen, Sheng Liang, Shan Gan, Shaojun Harris, Chirs J. Chongqing Univ Minist Educ Sch Automat Key Lab Dependable Serv Comp Cyber Phys Soc Chongqing 400044 Peoples R China Univ Southampton Sch Elect & Comp Sci Southampton SO17 1BJ Hants England King Abdulaziz Univ Jeddah 21589 Saudi Arabia Beijing Univ Technol Coll Metropolitan Transportat Beijing Key Lab Traff Engn Beijing 100124 Peoples R China

For a learning model to be effective in online modeling of nonstationary data, it must not only be equipped with high adaptability to track the changing data dynamics but also maintain low complexity to meet online computational restrictions. Based on these two important principles, in this paper, we propose a fast adaptive gradient radial basis function (GRBF) network for nonlinear and nonstationary time series prediction. Specifically, an initial compact GRBF model is constructed on the training data using the orthogonal least squares algorithm, which is capable of modeling variations of local mean and trend in the signal well. During the online operation, when the current model does not perform well, the worst performing GRBF node is replaced by a new node, whose structure is optimized to fit the current data. Owing to the local one-step predictor property of GRBF node, this adaptive node replacement can be done very efficiently. Experiments involving two chaotic time series and two real-world signals are used to demonstrate the superior online prediction performance of the proposed fast adaptive GRBF algorithm over a range of benchmark schemes, in terms of prediction accuracy and real-time computational complexity.

关键词： Nonlinear and nonstationary signals prediction radial basis function (RBF) network gradient RBF network adaptive algorithm tunable nodes

来源：评论

学校读者我要写书评

暂无评论

A novel metaheuristic inspired by Hitchcock birds' behavior for efficient optimization of large search spaces of high dimensionality

引用

SOFT COMPUTING 2020年第8期24卷 5633-5655页

作者： Morais, Reinaldo G. Nedjah, Nadia Mourelle, Luiza M. Univ Estado Rio De Janeiro Fac Engn R Sao Francisco Xavier 524 BR-20550900 Rio De Janeiro RJ Brazil

In this paper, a new optimization algorithm called the Hitchcock bird-inspired algorithm (HBIA) is proposed. It is inspired by the aggressive bird behavior portrayed by Alfred Hitchcock in the 1963 thriller "The Birds." It is noteworthy to emphasize that the bird's behavior as shown in the movie is itself inspired by a considered natural birds behavior when faced with extreme conditions. HBIA is a stochastic swarm intelligence algorithm that captures the essence of the fictional behavior of the phenomenon of birds throughout the Hitchcock's film and model an optimization mechanism. The algorithm is based on the attack pattern of birds in the film, which has the stages of lurking, attack and reorganization, defined by the initialization, movement strategies in the search space and strategy of local minimum escape, respectively. The technique has as differential the use of adaptive parameters, a discretized random initialization and the use of the beta distribution. In contrast to the existing ones, the proposed technique provides an efficient optimization in high-dimensionality cost functions, using adaptive parameters, a discretized random initialization and the use of the beta distribution. Its performance is analyzed and compared to classic techniques, such as PSO, ABC and CS, as well as to the existing adaptive techniques, such as sine cosine algorithm, whale optimization algorithm, teaching-learning-based optimization and vortex search. HBIA's performance is investigated by several experiments implemented through eight cost functions. The results show that the HBIA can find more satisfactory solutions in large search spaces and high dimensionality of the evaluated cost functions when compared to the existing optimization methods.

关键词： Optimization Metaheuristic Swarm intelligence adaptive algorithm

来源：评论

学校读者我要写书评

暂无评论

Local adaptive q-enrichments and generalized finite elements for transient heat diffusion problems

引用

COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING 2020年 372卷 113359-113359页

作者： Iqbal, M. Stark, D. Gimperlein, H. Mohamed, M. S. Laghrouche, O. Heriot Watt Univ Inst Infrastruct & Environm Edinburgh EH14 4AS Midlothian Scotland Creat Engn & Management Serv 367-368 Deans Ctr Peshawar Pakistan Heriot Watt Univ Maxwell Inst Math Sci Edinburgh EH14 4AS Midlothian Scotland Heriot Watt Univ Dept Math Edinburgh EH14 4AS Midlothian Scotland

A residual a-posteriori error estimate is used in conjunction with a q-adaptive procedure for selecting enrichment functions in the modelling of transient heat diffusion problems with the Generalized Finite Element Method (GFEM). The error estimate allows to assess local as well as global errors of the GFEM solutions and provides a tool to adaptively enrich the approximation space. With the proposed adaptive algorithm, the total number of degrees of freedom (DOFs) is significantly reduced in comparison to uniform enrichment. For a comparable accuracy, a reduction of up to 80% in DOFs is achieved. Moreover, the error estimate captures the deterioration of the conditioning of the system matrix typically encountered in enrichment based methods and enables the possibility of keeping the condition number within an acceptable limit. (C) 2020 Elsevier B.V. All rights reserved.

关键词： GFEM Enrichment functions Transient diffusion problems Error estimate adaptive algorithm

来源：评论

学校读者我要写书评

暂无评论

Spherical-Harmonic-Domain Feedforward Active Noise Control Using Sparse Decomposition of Reference Signals from Distributed Sensor Arrays

引用

IEEE-ACM TRANSACTIONS ON AUDIO SPEECH AND LANGUAGE PROCESSING 2020年 28卷 656-670页

作者： Maeno, Yu Mitsufuji, Yuki Samarasinghe, Prasanga N. Murata, Naoki Abhayapala, Thushara D. Sony Corp R&D Ctr Tokyo Japan Australian Natl Univ Res Sch Engn Canberra ACT 2601 Australia

Active acoustic noise attenuation over a sizable space is a challenging problem in signal processing. The noise attenuation performance of feedforward active noise control (ANC) relies on the preciseness of a reference signal of a primary noise field. To capture the precise reference signal for controlling a sizable space, a large number of reference microphones are required, which reduces system viability. In this study, we exploit an efficient representation of the reference signal in spherical harmonic (SH) domain by utilizing the inherent sparseness of the noise field. The main contributions of this work are as follows. (1) A general reference microphone geometry can be used. The implementation difficulty in the array structure, which is recognized as the common issue of SH-domain signal processing, e.g., use of a fully surrounding spherical array, is reduced by using the fields translation based on the addition theorem. (2) The accuracy of low-frequency signal decomposition is improved. The low accuracy of low-frequency signal decomposition in compressive sensing (CS), which is commonly reported in the literature, is improved by applying signal representation in SH domain. (3) System robustness is increased. The robustness of the system is increased by considering a noise source spatial distribution of both the interior and exterior sound fields, which is not possible in the case of a general signal representation in SH domain. Experimental results indicate that the noise attenuation performance of our proposed method exceeds that of existing solutions. The flexibility of the array structure is also increased, which leads to a more feasible practical system setup.

关键词： Active noise control adaptive algorithm sphe-rical harmonic compressive sensing feedforward

来源：评论

学校读者我要写书评

暂无评论

Novel Interference Suppression Null Steering Antenna System for High Precision Positioning

引用

IEEE ACCESS 2020年 8卷 77779-77787页

作者： Pal, Arpan Mehta, Amit Skippins, Andrew Spicer, Paul Mirshekar-Syahkal, Dariush Swansea Univ Coll Engn Swansea SA2 8PP W Glam Wales Univ Essex Dept Comp Sci & Elect Engn Colchester CO4 3SQ Essex England

The high precision (centimetre accuracy) positioning systems are set to play a key role in revolutionising smart farming, self-driving cars, drone deliveries, heavy machine navigation, etc. With so much at stake the technology also needs protection from an intentional sabotage or denial of service. It is very easy with current satellite-based navigation jammers to disrupt a navigation service. Our proposed technology solves this challenge in a compact and cost-effective way. Compared to normal navigation patch antennas our proposed dual ring antenna offers over 30 dB of protection. Thus, if a patch antenna-based navigation system is disturbed at 1 watt of interference power, it will take 1000 watts to disrupt navigation system working on our proposed system. With the size of only 130 mm x 130 mm and cheap large-scale manufacturing, our proposed antenna is perfectly suitable for applications for safety and prosperity of the smart nation-based living.

关键词： Jamming null steering capacitive coupling adaptive algorithm raspberry Pi

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：