检索结果-内蒙古大学图书馆

MATHEMATICAL MODELLING OF CARDIAC PULSE WAVE REFLECTIONS DUE TO ARTERIAL IRREGULARITIES

MATHEMATICAL BIOSCIENCES AND ENGINEERING 2018年第5期15卷 1055-1076页

作者： Cornet, Alexandre Imperial Coll London South Kensington Campus London SW7 2AZ England Ecole Normale Super Paris Saclay 61 Ave President Wilson F-94230 Cachan France

This research aims to model cardiac pulse wave reflections due to the presence of arterial irregularities such as bifurcations, stiff arteries, stenoses or aneurysms. When an arterial pressure wave encounters an irregularity, a backward reflected wave travels upstream in the artery and a forward wave is transmitted downstream. The same process occurs at each subsequent irregularity, leading to the generation of multiple waves. An iterative algorithm is developed and applied to pathological scenarios to predict the pressure waveform of the reflected wave due to the presence of successive arterial irregularities. For an isolated stenosis, analysing the reflected pressure waveform gives information on its severity. The presence of a bifurcation after a stenosis tends do diminish the amplitude of the reflected wave, as bifurcations' reflection coefficients are relatively small compared to the ones of stenoses or aneurysms. In the case of two stenoses in series, local extrema are observed in the reflected pressure waveform which appears to be a characteristic of stenoses in series along an individual artery. Finally, we model a progressive change in stiffness in the vessel's wall and observe that the less the gradient stiffness is important, the weaker is the reflected wave.

关键词： Arterial irregularties blood pressure wave mechanics mathematical modelling iterative algorithm

来源：评论

学校读者我要写书评

暂无评论

Regularized iterative Weiner filter method for blind image deconvolution

引用

JOURNAL OF COMPUTATIONAL AND APPLIED MATHEMATICS 2018年 336卷 425-438页

作者： Li, Fang Lv, Xiao-Guang Deng, Ziwei East China Normal Univ Dept Math Shanghai Peoples R China Huaihai Inst Technol Sch Sci Lianyungang Jiangsu Peoples R China

Blind image deconvolution is a highly ill-posed problem. As a generalization of the well known Weiner filter, the existing iterative Weiner filter (IWF) method for blind image deconvolution is unstable and suffers from serious ringing artifacts. To overcome these drawbacks, in this paper, we propose two novel regularized iterative Weiner filter methods. We assume that both the latent image and the convolution kernel can be estimated by applying two different filters on the observed image. To estimate the filters, we propose to minimize energy functionals combined by the mean square errors with some regularization terms. Both H-1 and total variation (TV) regularization are considered. By applying alternating minimization method and operator splitting technique, we derive iterative algorithms for each regularization method. The proposed methods are effective for blind deconvolution of Gaussian blurred images which is widely observed in real applications such as microscopic images. Numerical experimental results on both synthetic images and real microscopic images are presented. The comparisons show that the proposed regularized algorithms perform better than the closely related state-of-the-art methods in terms of peak signal-to-noise ratio (PSNR) and visual quality. (C) 2018 Elsevier B.V. All rights reserved.

关键词： Weiner filter Blind image deconvolution Regularization iterative algorithm Microscopic image

来源：评论

学校读者我要写书评

暂无评论

A Unified Convergence Analysis for Some iterative algorithms with Applications to Fractional Calculus

引用

International Journal of Applied and Computational Mathematics 2017年第2期3卷 323-332页

作者： Anastassiou, George A. Argyros, Ioannis K. Department of Mathematical Sciences University of Memphis Memphis 38152 TN United States Department of Mathematical Sciences Cameron University Lawton 73505 Ok United States

We present a local as well as a semilocal convergence analysis for some iterative algorithms in order to approximate a locally unique solution of a nonlinear equation in a Banach space setting. In the application part of the study, we present applications to fractional calculus by using some choices of the operators involving the left and right Caputo derivative, where the operators satisfy the convergence conditions. © 2016, Springer India Pvt. Ltd.

关键词： Banach space Fractional calculus Fractional derivatives iterative algorithm Semilocal-local convergence

来源：评论

学校读者我要写书评

暂无评论

iterative Component Mode Synthesis Using a Priori and a Posteriori Criteria

引用

AIAA JOURNAL 2019年第5期57卷 2145-2157页

作者： Kim, Soo Min Kim, Jin-Gyun Park, K. C. Chae, Soo-Won Korea Univ Dept Mech Engn 145 Anam Ro Seoul 02841 South Korea Kyung Hee Univ Dept Mech Engn 1732 Deogyeong Daero Yongin 17104 Gyeonggi Do South Korea Univ Colorado Dept Aerosp Engn Sci Campus Box 429 Boulder CO 80309 USA Univ Colorado Ctr Aerosp Struct Campus Box 429 Boulder CO 80309 USA

An iterative algorithm of component mode synthesis for a rational reduced-order modeling is proposed. The present algorithm consists of three steps: initial mode selection with a priori criterion, model reduction using the selected modes, and a posteriori error evaluation. The algorithm is based on the Craig-Bampton method, which is one of the most widely used techniques. Specifically, the present algorithm uses, in a judicious manner, both an a priori mode selection criterion employing the moment-matching strategy and an a posteriori error estimation technique in evaluating the relative eigenvalue errors. If desired, an optional step of boundary interface reduction offers an additional possibility of obtaining a more compact model. The proposed iterative algorithm is recommended to researchers as well as commercialized software users in developing linear reduced-order structural dynamics models. Numerical examples are presented for its practical usage and performance.

关键词： iterative algorithm Structural Dynamics Aeroplane Flexibility Matrix Elastic Modulus Frequency Response Functions Material Properties Computing Tetrahedral Element Free Vibrations

来源：评论

学校读者我要写书评

暂无评论

EXACT SIMULATION OF MULTIDIMENSIONAL REFLECTED BROWNIAN MOTION

引用

JOURNAL OF APPLIED PROBABILITY 2018年第1期55卷 137-156页

作者： Blanchet, Jose Murthy, Karthyek Columbia Univ Dept Ind Engn & Operat Res SW Mudd Bldg500 W 120 St New York NY 10027 USA Stanford Univ Management Sci & Engn 475 Via Ortega Stanford CA 94305 USA

We present the first exact simulation method for multidimensional reflected Brownian motion (RBM). Exact simulation in this setting is challenging because of the presence of correlated local-time-like terms in the definition of RBM. We apply recently developed so-called epsilon-strong simulation techniques (also known as tolerance-enforced simulation) which allowus to provide a piecewise linear approximation toRBMwith epsilon (deterministic) error in uniform norm. A novel conditional acceptance-rejection step is then used to eliminate the error. In particular, we condition on a suitably designed information structure so that a feasible proposal distribution can be applied.

关键词： Unbiased sampling refine until accept/reject tolerance enforced simulation acceptance-rejection sampling epsilon-strong simulation iterative algorithm intersection layer

来源：评论

学校读者我要写书评

暂无评论

The single-manufacturer single-retailer integrated production-delivery lot sizing model with production capacity under stochastic lead time demand

引用

Procedia CIRP 2019年 83卷 528-533页

作者： Xuefang Sun Renqian Zhang School of Economics and Management Beihang University Beijing 100191 China

This paper develops an integrated production-delivery lot sizing model in which a manufacturer supplies a product a retailer. The manufacturer produces the product at a finite rate and the production rate is assumed to be smaller than market demand rate. Meanwhile, we assume that the lead time demand is stochastic and that shortages are permitted. The lead time and the reorder point are in this model as decision variables. The objective is to determine the optimal ordering quantity, reorder point, lead time and the delivery number during each production cycle which minimize the expected total cost per unit time of the manufacturer and the retailer by giving an effective iterative algorithm. A numerical example is given as an illustration of this algorithm for the integrated system.

关键词： integrated production-delivery lot sizing model stochastic demand lead time reorder point iterative algorithm

来源：评论

学校读者我要写书评

暂无评论

Boundary crash data assignment in zonal safety analysis: An iterative approach based on data augmentation and Bayesian spatial model

引用

ACCIDENT ANALYSIS AND PREVENTION 2018年第Dec.期121卷 231-237页

作者： Zhai, Xiaoqi Huang, Helai Gao, Mingyun Dong, Ni Sze, N. N. Cent S Univ Sch Traff & Transportat Engn Changsha Hunan Peoples R China Hunan Univ Dept Ind & Business Management Changsha Hunan Peoples R China Southwest Jiaotong Univ Sch Transportat & Logist Chengdu Sichuan Peoples R China Hong Kong Polytech Univ Dept Civil & Environm Engn Hong Kong Hong Kong Peoples R China

Boundary effect refers to the issue of ambiguous allocation of crashes occurred on or near the boundaries of neighboring zones in zonal safety analysis. It results in bias estimates for associate measure between crash occurrence and possible zonal factors. It is a fundamental problem to compensate for the boundary effect and enhance the model predictive performance. Compared to conventional approaches, it might be more reasonable to assign the boundary crashes according to the crash predisposing agents, since the crash occurrence is generally correlated to multiple sources of risk factors. In this study, we proposed a novel iterative aggregation approach to assign the boundary crashes, according to the ratio of model-based expected crash number in adjacent zones. To verify the proposed method, a case study using a dataset of 738 Traffic Analysis Zones (TAZs) from the county of Hillsborough in Florida was conducted. Using Bayesian spatial models (BSMs), the proposed approach demonstrated the capability in reasonably compensating for the boundary effect with better model estimation and predictive performance, as compared to three conventional approaches (i.e., half and half ratio method, one to one ratio method, and exposure ratio method). Results revealed that several factors including the number of intersections, road segment length with 35 mph speed limit, road segment length with 65 mph speed limit and median household income, were sensitive to the boundary effect.

关键词： Macroscopic safety analysis Zonal-level CPMs Boundary effect iterative algorithm

来源：评论

学校读者我要写书评

暂无评论

Zonotopic Unknown Input Observer of Discrete-time Descriptor Systems for State Estimation and Robust Fault Detection

引用

IFAC-PapersOnLine 2018年第24期51卷 307-313页

作者： Wang, Ye Puig, Vicen Xu, Feng Cembrano, Gabriela CSIC-UPC Universitat Politècnica de Catalunya C/. Llorens i Artigas 4-6 Barcelona08028 Spain Center of Intelligent Control and Telescience Graduate School at Shenzhen Tsinghua University Shenzhen518055 China Cetaqua Water Technology Centre Ctra. d'Esplugues 75 Cornellà de Llobregat Barcelona08940 Spain

This paper studies a set-based unknown input observer based on zonotopes for discrete-time descriptor systems affected by uncertainties with application to state estimation and robust fault detection. In this paper, two types of uncertainties are considered: (i) disturbances and noise both bounded by zonotopes; (ii) unknown inputs that can be decoupled. In terms of different applications, the observer gain for state estimation is designed to minimize the effects of unknown-but-bounded disturbances and noise as well as state estimation errors. On the other hand, for robust fault detection, in addition to attenuating uncertainties, the designed observer gain is also expected to be sensitive to faults. To achieve this goal, we propose an iterative algorithm to design the fault detection gain. Finally, some illustrative results in an application example show the effectiveness of the proposed algorithms. © 2018

关键词： Fault detection Describing functions iterative methods State estimation Application examples Discrete time descriptor systems Estimation errors iterative algorithm Robust fault detection Unknown but bounded Unknown input observer Zonotopes

来源：评论

学校读者我要写书评

暂无评论

Estimation of the Initial Image's Contributions to the iterative Landweber Reconstruction

引用

IEEE TRANSACTIONS ON RADIATION AND PLASMA MEDICAL SCIENCES 2018年第1期2卷 27-32页

作者： Zeng, Gengsheng L. Weber State Univ Dept Engn Ogden UT 84408 USA Univ Utah Dept Radiol & Imaging Sci Salt Lake City UT 84108 USA

This paper develops a closed-form frequency-domain transfer function to predict the initial image's contributions in an iterative Landweber reconstruction for a given number of iterations. The transfer function shows that the initial image's high frequency components play an important role when the iterative algorithm is stopped before convergence. The contributions from the initial image diminish as the iteration number increases if the imaging matrix has full rank.

关键词： Fourier transform image reconstruction iterative algorithm linear filter numeric analysis tomography

来源：评论

学校读者我要写书评

暂无评论

H∞ Model Reduction for Interval Frequency Negative Imaginary Systems

引用

IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS I-REGULAR PAPERS 2019年第3期66卷 1116-1129页

作者： Yu, Lanlin Xiong, Junlin Univ Sci & Technol China Dept Automat Hefei 230026 Anhui Peoples R China

This paper studies an H-infinity model reduction problem for interval frequency negative imaginary (IFNI) systems. For a given IFNI system, our goal is to find a reduced-order IFNI system satisfying a pre-specified H-infinity approximation error bound over the finite-frequency interval. Necessary and sufficient conditions in terms of matrix inequalities are derived for the existence and construction of an H-infinity reduced-order IFNI system. An improved iterative algorithm is provided to solve the matrix inequalities and to minimize the H-infinity approximation error. The proposed method is further clarified via the application to the electrical circuits, such as high-order Sallen-Key low-pass filter, piezoelectric tube scanner, and RLC circuit. The simulation results on these electrical circuits are compared with the finite-frequency interval Gramians-based model reduction method both in the frequency domain and time domain.

关键词： H-infinity model reduction interval frequency negative imaginary systems iterative algorithm electrical circuits

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：