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Reliability of multi-state systems with free access to repairable standby elements

RELIABILITY ENGINEERING & SYSTEM SAFETY 2017年 167卷 192-197页

作者： Levitin, Gregory Jia, Heping Ding, Yi Song, Yonghua Dai, Yuanshun Univ Elect Sci & Technol China Sch Comp Sci Collaborat Auton Comp Lab Chengdu Sichuan Peoples R China Israel Elect Corp Ltd POB 10 IL-31000 Haifa Israel Zhejiang Univ Coll Elect Engn Hangzhou Zhejiang Peoples R China

The paper presents an approach for evaluating reliability of standby systems composed of multi-state elements with constant state transition rates. Any standby elements can be repaired, whereas no repairs are possible in operation. When an operating element fails the standby element with the best technical state is activated. Time-to-failure distributions of operating elements depend on their states at the time of activation. An iterative algorithm for reliability evaluation based on element state probabilities is suggested. An example of using the algorithm for evaluating reliability of standby system is presented. (C) 2017 Elsevier Ltd. All rights reserved.

关键词： Reliability analysis Multi-state system Repairable standby element iterative algorithm

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Recovering the potential term in a fractional diffusion equation

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IMA JOURNAL OF APPLIED MATHEMATICS 2017年第3期82卷 579-600页

作者： Zhang, Zhidong Zhou, Zhi Texas A&M Univ Dept Math College Stn TX 77843 USA Columbia Univ Dept Appl Phys & Appl Math New York NY 10027 USA

In this article, we consider an inverse problem of recovering the potential term in a 1D time-fractional diffusion equation from the overdetermined final time data. We introduce a reconstruction operator and show its contractivity and monotonicity, which give the unique determination and an efficient algorithm. Further, for noisy data, we propose a regularized iterative algorithm based on mollification and derive error estimates for the approximation. Extensive numerical experiments for both smooth and nonsmooth potential data are provided to illustrate the efficiency and stability of the algorithm, and to verify the convergence theory.

关键词： fractional diffusion inverse potential problem monotonicity contraction regularization iterative algorithm

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A Novel SWMM Based algorithm Application to Storm Sewer Network Design

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WATER 2017年第10期9卷 747-747页

作者： Shao, Zhiyu Zhang, Xiaoyuan Li, Shuang Deng, Shihu Chai, Hongxiang Chongqing Univ Minist Educ Key Lab Ecol Environm Gorges Reservoir Area 3 Chongqing 400044 Peoples R China Chongqing Univ Sch Urban Construct & Environm Engn Chongqing 400045 Peoples R China Chongqing Zhixing Geog Informat Consulting Serv L Chongqing 401121 Peoples R China

An automated algorithm based on the dynamic hydrological and hydraulic simulation modules in Storm Water Management Model (SWMM) was developed to aid the design of storm sewer networks, provided that a layout is given. Numerical performance of the proposed algorithm was compared with the existing design methods with two application cases. The automated computation process of the sewer network design was divided into two stages and solved iteratively, determining pipe diameter and pipe slope, respectively. In the first stage, starting with a set of initial values including pipe diameter, pipe cover depth, and ground elevation at manholes, the iteration was carried out from the downstream to the upstream while the pipe slopes of the network were assumed to be fixed and the diameter of each pipe segment was calculated. In the second stage, pipe diameters calculated from the first stage were fixed and the pipe slopes were calculated successively from the downstream pipe segment to the upstream pipe segment. Every time the diameter or slope of a pipe segment was adjusted, the pipe flow rate, velocity, and flow depth were obtained by running SWMM hydrological and hydraulic simulation modules. The iteration terminated once the combination scheme of pipe diameters and slopes met the design ordinance which requires the pipe flows full under gravity in a design return period. A real urban sewer system in a hilly city and a benchmark sewer network from the literature were tested to validate the proposed automated algorithm, and good performance was shown. The automated design results explicitly show that the proposed storm sewer design approach leads to a quality solution with reduced computational effort.

关键词： storm sewer network design iterative algorithm SWMM

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Real-Time Optimal State Estimation of Multi-DOF Industrial Systems Using FIR Filtering

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IEEE TRANSACTIONS ON INDUSTRIAL INFORMATICS 2017年第3期13卷 967-975页

作者： Zhao, Shunyi Shmaliy, Yuriy S. Ahn, Choon Ki Shi, Peng Jiangnan Univ Key Lab Adv Proc Control Light Ind Minist Educ Wuxi 214122 Jiangsu Peoples R China Univ Alberta Edmonton AB T6G 2R3 Canada Univ Guanajuato Dept Elect Engn Salamanca 36885 Mexico Korea Univ Sch Elect Engn Seoul 136701 South Korea Harbin Engn Univ Coll Automat Harbin 150001 Peoples R China

Industrial processes are often organized using mechanical systems with multiple degrees-of-freedom (DOF). For real-time operation of such systems in noise environments, fast, optimal, and robust estimators are required. In this paper, information gathering about multi-DOF system states is provided using the optimal finite impulse response (OFIR) filter. To use this filter in real time, a fast iterative algorithm is developed with a pseudocode available for immediate use. Although the iterative algorithm utilizes Kalman recursions, it is more robust against uncertainties and model errors owing to the transversal structure. We use this algorithm to estimate state in the 1-DOF torsion system and the 3-DOF helicopter system.

关键词： Automation process finite impulse response (FIR) filter iterative algorithm Kalman filter (KF) state estimation time-variant system

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Accurate Insect Orientation Extraction Based on Polarization Scattering Matrix Estimation

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IEEE GEOSCIENCE AND REMOTE SENSING LETTERS 2017年第10期14卷 1755-1759页

作者： Hu, C. Li, W. Wang, R. Liu, C. Zhang, T. Li, W. Beijing Inst Technol Radar Res Lab Sch Informat & Elect Beijing 100081 Peoples R China Beijing Inst Technol Minist Educ Key Lab Elect & Informat Technol Satellite Nav Beijing 100081 Peoples R China

A novel insect orientation extraction method is proposed based on the target polarization scattering matrix (PSM) estimation, which is applicable for traditional vertical-looking insect radar with noncoherent reception as well as the coherent radar. The insect echo signal at different polarization directions on the radar polarization plane is usually acquired by means of rotating linearly polarized antenna. In this letter, the insect echo signal is first used to accurately estimate insect PSM by an iterative algorithm based on the second-order polynomial approximation. Meanwhile, the Cramer-Rao lower bound is also analyzed to test the estimation performance. Next, based on the assumption that the target orientation is consistent with the dominant eigenvector, the insect orientation is extracted from the estimated PSM. Finally, both theoretical simulations and real experimental data are used to validate the effectiveness and feasibility of our proposed method, which can achieve good orientation estimation accuracy at low signal-to-noise ratio.

关键词： Entomological radar insect iterative algorithm orientation extraction polarization scattering matrix (PSM)

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An improved algorithm for fast resonant Mie scatter correction of infrared spectra of cells and tissues

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JOURNAL OF BIOPHOTONICS 2018年第1期11卷 2018 Jan;11(1)页

作者： Konevskikh, Tatiana Lukacs, Rozalia Kohler, Achim Norwegian Univ Life Sci Dept Math Sci & Technol IMT N-1430 Trondheim Norway

Mie scattering effects create serious problems for the interpretation of Fourier-transform infrared spectroscopy spectra of single cells and tissues. During recent years, different techniques were proposed to retrieve pure absorbance spectra from spectra with Mie distortions. Recently, we published an iterative algorithm for correcting Mie scattering in spectra of single cells and tissues, which we called the fast resonant Mie scatter correction algorithm. The algorithm is based on extended multiplicative signal correction (EMSC) and employs a meta-model for a parameter range of refractive index and size parameters. In the present study, we suggest several improvements of the algorithm. We demonstrate that the improved algorithm reestablishes chemical features of the measured spectra, and show that it tends away from the reference spectrum employed in the EMSC. We suggest strategies for choosing parameter ranges and other model parameters such as the number of principal components of the meta-model and the number of iterations. We demonstrate that the suggested algorithm optimizes an error function of the refractive index in a forward Mie model. We suggest a stop criterion for the iterative algorithm based on the error function of the forward model.

关键词： complex refractive index extended multiplicative signal correction Hilbert transform infrared microscopy iterative algorithm Mie scattering

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Modeling reward expiry for loyalty programs in a competitive market

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INTERNATIONAL JOURNAL OF PRODUCTION ECONOMICS 2017年 193卷 352-364页

作者： Bazargan, Amirhossein Karray, Salma Zolfaghari, Saeed Ryerson Univ Toronto ON Canada Univ Ontario Inst Technol UOIT Oshawa ON Canada

This paper investigates reward expiry for loyalty programs. It provides insights into the profitability of setting reward expiry for competing firms and identifies conditions under which such a policy would be beneficial. We develop and solve a game-theoretic model that reflects consumer behavior in choosing products and redeeming rewards. Applying a new iterative algorithm, we get the Nash equilibrium outputs for three scenarios (games): (1) neither firm sets an expiry date, (2) both firms set an expiry date, and (3) only one firm sets an expiry date. Comparison of the firms' profits across scenarios shows that the firms' prices and profits are affected by the loyalty program of the competing firm and by consumers' valuation of rewards and of time to rewards. In particular, a firm offering rewards that do not expire should increase its price if the competing firm changes its reward policy from no expiry to expiry, even when the expiry period is quite long. Finally, when customers highly value rewards and time, reward expiry is a dominant strategy for both firms. This means that firms would benefit from setting expiry on their loyalty rewards only if their customers highly value both rewards and time. Alternatively, both firms' rewards should not expire if consumers have low valuations of both rewards and time.

关键词： Loyalty programs iterative algorithm Multinomial logit models Game theory Reward expiry Marketing-operations interface

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A generalized elastic net regularization with smoothed l_q penalty for sparse vector recovery

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COMPUTATIONAL OPTIMIZATION AND APPLICATIONS 2017年第2期68卷 437-454页

作者： Zhang, Yong Ye, Wanzhou Zhang, Jianjun Shanghai Univ Dept Math Coll Sci Shanghai 200444 Peoples R China Jiangsu Univ Sci & Technol Sch Sci Zhenjiang 212003 Peoples R China

In this paper, we propose an iterative algorithm for solving the generalized elastic net regularization problem with smoothed penalty for recovering sparse vectors. We prove the convergence result of the algorithm based on the algebraic method. Under certain conditions, we show that the iterative solutions converge to a local minimizer of the generalized elastic net regularization problem and we also present an error bound. Theoretical analysis and numerical results show that the proposed algorithm is promising.

关键词： iterative algorithm Compressed sensing Convergence Elastic net regularization l(q) minimization

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A general model for preload calculation and stiffness analysis for combined angular contact ball bearings

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JOURNAL OF SOUND AND VIBRATION 2017年 411卷 435-449页

作者： Zhang, Jinhua Fang, Bin Hong, Jun Wan, Shaoke Zhu, Yongsheng Xi An Jiao Tong Univ State Key Lab Mfg Syst Engn Xian 710049 Peoples R China Xi An Jiao Tong Univ Key Lab Educ Minist Modern Design & Rotor Bearing Syst Xian 710049 Peoples R China

The combined angular contact ball bearings are widely used in automatic, aerospace and machine tools, but few researches on the combined angular contact ball bearings have been reported. It is shown that the preload and stiffness of combined bearings are mutual influenced rather than simply the superposition of multiple single bearing, therefore the characteristic calculation of combined bearings achieved by coupling the load and deformation analysis of a single bearing. In this paper, based on the Jones quasi-static model and stiffness analytical model, a new iterative algorithm and model are proposed for the calculation of combined bearings preload and stiffness, and the dynamic effects include centrifugal force and gyroscopic moment have to be considered. It is demonstrated that the new method has general applicability, the preload factors of combined bearings are calculated according to the different design preloads, and the static and dynamic stiffness for various arrangements of combined bearings are comparatively studied and analyzed, and the influences of the design preload magnitude, axial load and rotating speed are discussed in detail. Besides, the change rule of dynamic contact angles of combined bearings with respect to the rotating speed is also discussed. The results show that bearing arrangement modes, rotating speed and design preload magnitude have a significant influence on the preload and stiffness of combined bearings. The proposed formulation provides a useful tool in dynamic analysis of the complex bearing-rotor system. (C) 2017 Elsevier Ltd. All rights reserved.

关键词： Combined angular contact ball bearing iterative algorithm Preload Stiffness

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GOSIM: A multi-scale iterative multiple-point statistics algorithm with global optimization

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COMPUTERS & GEOSCIENCES 2016年第Apr.期89卷 57-70页

作者： Yang, Liang Hou, Weisheng Cui, Chanjie Cui, Jie Sun Yat Sen Univ Sch Earth Sci & Geol Engn B410 Dihuan Bldg135 Xingangxi Rd Guangzhou 510275 Guangdong Peoples R China Guangdong Prov Key Lab Mineral Resource Explorat Guangzhou 510275 Guangdong Peoples R China Guangdong Technoecon Res & Dev Ctr Guangzhou 510070 Guangdong Peoples R China

Most current multiple-point statistics (MPS) algorithms are based on a sequential simulation procedure, during which grid values are updated according to the local data events. Because the realization is updated only once during the sequential process, errors that occur while updating data events cannot be corrected. Error accumulation during simulations decreases the realization quality. Aimed at improving simulation quality, this study presents an MPS algorithm based on global optimization, called GOSIM. An objective function is defined for representing the dissimilarity between a realization and the TI in GOSIM, which is minimized by a multi-scale EM-like iterative method that contains an E-step and M-step in each iteration. The E-step searches for TI patterns that are most similar to the realization and match the conditioning data. A modified PatchMatch algorithm is used to accelerate the search process in E-step. M-step updates the realization based on the most similar patterns found in E-step and matches the global statistics of TL During categorical data simulation, k-means clustering is used for transforming the obtained continuous realization into a categorical realization. The qualitative and quantitative comparison results of GOSIM, MS-CCSIM and SNESIM suggest that GOS1M has a better pattern reproduction ability for both unconditional and conditional simulations. A sensitivity analysis illustrates that pattern size significantly impacts the time costs and simulation quality. In conditional simulations, the weights of conditioning data should be as small as possible to maintain a good simulation quality. The study shows that big iteration numbers at coarser scales increase simulation quality and small iteration numbers at finer scales significantly save simulation time. (C) 2016 Elsevier Ltd. All rights reserved.

关键词： MPS algorithm Global optimization iterative algorithm Geostatistical simulation

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