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Forecasting COVID-19 Chile' second outbreak by a generalized SIR model with constant time delays and a fitted positivity rate

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MATHEMATICS AND COMPUTERS IN SIMULATION 2022年 193卷 1-18页

作者： Cumsille, Patricio Rojas-Diaz, Oscar Moisset de Espanes, Pablo Verdugo-Hernandez, Paula Univ Biobio Campus Fernando May Fac Sci Dept Basic Sci Av Andres Bello 720Casilla 447 Chillan Chile Neurovision AI San Eugenio 3494 Santiago Chile Univ Santiago Chile Fac Engn Dept Informat Engn Santiago Chile Univ Chile Ctr Biotechnol & Bioengn CeBiB Beaucheff 851 Santiago Chile Univ Talca Fac Ciencias Educ Escuela Pedag Ciencias Nat & Exactas Talca Chile

The COVID-19 disease has forced countries to make a considerable collaborative effort between scientists and governments to provide indicators to suitable follow-up the pandemic's consequences. Mathematical modeling plays a crucial role in quantifying indicators describing diverse aspects of the pandemic. Consequently, this work aims to develop a clear, efficient, and reproducible methodology for parameter optimization, whose implementation is illustrated using data from three representative regions from Chile and a suitable generalized SIR model together with a fitted positivity rate. Our results reproduce the general trend of the infected's curve, distinguishing the reported and real cases. Finally, our methodology is robust, and it allows us to forecast a second outbreak of COVID-19 and the infection fatality rate of COVID-19 qualitatively according to the reported dead cases. (C) 2021 International Association for Mathematics and Computers in Simulation (IMACS). Published by Elsevier B.V. All rights reserved.

关键词： Mathematical modeling parameter estimation method Predictive modeling Computational model Epidemiological modeling

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Non-uniform image blind deblurring by two-stage fully convolution network

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IET IMAGE PROCESSING 2020年第11期14卷 2588-2596页

作者： Wu, Chudan Wo, Yan Han, Guoqing Wu, Zhangyong Liang, Jiyun South China Univ Technol Dept Comp Sci Guangzhou Peoples R China

Deep neural networks have recently demonstrated high performance for deblurring. However, few methods are designed for both non-uniform image blur estimation and removal with highly efficient. In this study, the authors proposed a fully convolutional network that outputs estimated blur and restored image in one feed-forward pass for the non-uniformly blurred image of any input-size. The proposed network contains two subnets. The parameter estimation subnet P-net predicts pixel-wise parameters of multiple blur types with high accuracy. The output of P-net is used as a condition, which guides the blur removal subnet G-net to restore a high quality latent sharp image. P-net and G-net are ultimately integrated into a single framework called PG-net, which guarantees the consistency of parameter estimation and blur removal, thereby improves algorithm efficiency. Experiment results show that the authors blur parameter estimation method as well as their deblurring method outperforms the comparison methods both quantitatively and qualitatively.

关键词： neural nets parameter estimation image restoration nonuniform image blind deblurring two-stage fully convolution network deep neural networks fully convolutional network blur restored image feed-forward pass parameter estimation subnet P-net pixel-wise parameters multiple blur types blur removal subnet G-net high quality latent sharp image PG-net parameter estimation method deblurring method

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The Effect of Population Aging on Healthcare Expenditure from a Healthcare Demand Perspective Among Different Age Groups: Evidence from Beijing City in the People's Republic of China

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RISK MANAGEMENT AND HEALTHCARE POLICY 2020年 13卷 1403-1412页

作者： Li, Lele Du, Tiantian Hu, Yanping Tsinghua Univ Sch Publ Policy & Management Beijing 100084 Peoples R China Tsinghua Univ Inst Hosp Management Shenzhen 518055 Guangdong Peoples R China China Japan Friendship Hosp Dept Med Engn Beijing 100029 Peoples R China

Background: With population aging (PA), the healthcare expenditure (HE) increases. The aim of this study is to analyze the HE of different age groups and the effect of age on HE among different age groups. methods: Combining PA and HE data, this study used the fixed effect model and parameter estimation method to evaluate the influence of different age groups on HE from 2008 to 2014. Results: The age effect of HE for the population aged 65 or over was the most significant among the different age groups. Based on PA and HE data, HE per capita of the age group 65 years or over is 7.25 times as much as the population aged < 25 years, 1.61 times as much as the population aged 25 similar to 59 years, and 3.47 times as much as the population aged 60 similar to 64 years. Based on the result of the fixed effect model, HE per capita of the age group < 25 years was 218.39 Yuan (CNY) (USD $31.2). HE per capita of the age group 25 similar to 59 years old increased to 1,548.62 Yuan (CNY) (USD $221.2). HE per capita of the 60 similar to 64 years age group will be 921.56 Yuan (CNY) (USD $131.7), 4.22 times as much as that of the age group < 25 years. HE per capita in the age group of 65 years or over is 2,538.88 Yuan (CNY) (USD $362.7), 11.63 times as much as that of the age group < 25 years. Conclusion: The results suggest that PA in China is intensifying. In order to control the rising of HE, the government should not only address the supply side such as reforming medical insurance payment, developing new technologies, but also focusing on solving the demand side such as improving the quality of healthcare services, solving environmental pollution, and improving the residents' health.

关键词： population aging healthcare demand healthcare expenditure different age groups fixed effect model parameter estimation method

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Wind Speed Distributions Used in Wind Energy Assessment: A Review

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FRONTIERS IN ENERGY RESEARCH 2021年 9卷

作者： Shi, Huanyu Dong, Zhibao Xiao, Nan Huang, Qinni Shaanxi Normal Univ Sch Geog & Tourism Xian Peoples R China Inner Mongolia Normal Univ Coll Geog Sci Hohhot Peoples R China

With economic development and population growth, energy demand has shown an upward trend. Renewable energy is inexhaustible and causes little pollution, which has broad prospects for development. In recent years, wind energy has been developed as an essential renewable energy source. The use of wind power is very environmentally friendly and plays a critical role in economic growth. Assessing the characteristics and potential of wind energy is the first step in the effective development of wind energy. The wind speed distribution at a specific location determines the available wind energy. This paper reviews the wind speed distribution models used for wind energy assessment, and they are applicable to different wind regimes. All potential wind speed distribution models should be considered for modeling wind speed data at a particular site. Previous studies have selected several parameter estimation methods and evaluation criteria to estimate model parameters and evaluate the goodness-of-fit. This paper discusses their advantages and disadvantages. The characteristics of wind speed distribution are constantly varying geographically and temporally. Wind energy assessment should consider local geographical elements, such as local climate, topography, and thermal properties difference between the land and the sea, and focus on long-term variations in wind characteristics.

关键词： renewable energy wind energy assessment wind speed distribution parameter estimation method goodness-of-fit criteria

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Non-damping system reset schemes for underwater SINS based on intermittent calibration information

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MEASUREMENT 2021年 182卷 109741-109741页

作者： Fang, Tao Qian, Dong Southwest China Inst Elect Technol Chengdu 610036 Peoples R China

For Strap-down Inertial Navigation System (SINS), the estimation accuracy of gyro drifts in system reset is subject to the steady state horizontal attitude errors induced by accelerometer biases. Two non-damping system reset schemes are proposed to solve this problem. First, the Doppler velocity log (DVL) aided parameter estimation method is derived to estimate the accelerometer biases and equivalent horizontal attitude errors;then the P equation of system reset is reformulated in which the horizontal attitude errors are considered and obtained through the parameter estimation method;finally, on the basis of P equation, with intermittent calibration information, two system reset schemes are designed. Simulation results indicate that by compensating accelerometer biases before system reset, the proposed schemes have higher estimation accuracy of gyro drifts, meanwhile they reduce the time of using DVL and have better error suppression performance than existing schemes.

关键词： System reset SINS Gyro drifts Accelerometer biases parameter estimation method

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Dynamic texture classification using Gumbel mixtures in the complex wavelet domain

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IET IMAGE PROCESSING 2019年第1期13卷 9-14页

作者： Qiao, Yulong Liu, Qiufei Liu, Wenhui Harbin Engn Univ Coll Informat & Commun Engn Harbin Heilongjiang Peoples R China

Dynamic texture (DT) classification has attracted extensive attention in the field of image sequence analysis. The probability distribution model, which has been used to analysis DT, can describe well the distribution property of signals. Here, the authors introduce the finite mixtures of Gumbel distributions (MoGD) and the corresponding parameter estimation method based on expectation-maximisation algorithm. Then, the authors propose the DT features based on MoGD model for DT classification. Specifically, after decomposing DTs with the dual-tree complex wavelet transform (DT-CWT), the median values of complex wavelet coefficient magnitudes of non-overlapping blocks in detail subbands are modelled with MoGDs. The model parameters are accumulated into a feature vector to describe DT. During the classification, a variational approximation version of the Kullback-Leibler divergence is used to measure the similarity between different DTs. The experimental evaluations on two popular benchmark DT data sets (UCLA and DynTex++) demonstrate the effectiveness of the proposed approach.

关键词： expectation-maximisation algorithm trees (mathematics) image sequences image texture wavelet transforms image classification statistical distributions approximation theory DT features MoGD model DT classification dual-tree complex wavelet DT-CWT complex wavelet coefficient magnitudes nonoverlapping blocks feature vector dynamic texture classification Gumbel mixtures complex wavelet domain image sequence analysis probability distribution model parameter estimation method expectation-maximisation algorithm signal distribution property finite mixtures-of-Gumbel distributions median values benchmark DT data sets UCLA Kullback-Leibler divergence DynTex plus

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Energy based signal parameter estimation method and a comparative study of different frequency estimators

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MECHANICAL SYSTEMS AND SIGNAL PROCESSING 2011年第1期25卷 452-464页

作者： Lin Huibin Ding Kang S China Univ Technol Sch Mech & Automot Engn Guangzhou 510640 Peoples R China

The influences of window functions and noise on the performance of the energy-based signal parameter estimation method are investigated, and the appropriate parameters and algorithm are recommended accordingly. The frequency, amplitude and phase estimation variances of the energy based method are deduced and verified by computer simulation. The performances of four frequency estimation methods are compared: the energy based method, the interpolation based method, the phase difference based method and the Fourier transform (FT) continuous zoom based method. For the second and third methods, the Quinn algorithm and the phase difference based method with factor eta=0.5 are recommended, respectively. It was found that each method has its own advantages. The energy based method has the best stability compared with others. The interpolated method has the lowest frequency estimation variance when the frequency bias delta is large, while the phase-difference based method does better when delta is low. The change of delta does not influence the maximum frequency estimation error of the FT continuous zoom based method. Comparatively speaking, the phase-difference based method has the least frequency estimation error. (C) 2010 Elsevier Ltd. All rights reserved.

关键词： Digital signal processing parameter estimation method estimation error Spectrum correction

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Estimating the parameters of induction motors in different operating regimes from a set of data containing the rotor cage temperature

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ELECTRICAL ENGINEERING 2018年第1期100卷 139-150页

作者： Klimenta, Dardan Hannukainen, Antti Arkkio, Antero Univ Pristina Kosovska Mitrovica Fac Tech Sci Kneza Milosa 7 K Mitrovica 38220 Serbia Aalto Univ Dept Math & Syst Anal POB 11100 Aalto 00076 Finland Aalto Univ Dept Elect Engn & Automat POB 13000 Aalto 00076 Finland

The purpose of this paper is to propose a method for accurate estimation of the equivalent circuit parameters of induction motors at different operating regimes from a set of measurement data containing the rotor cage temperature and rotor resistance at 25 C. Besides these rotor quantities, the method requires the measurement of supply voltage, stator current, frequency, speed, load torque, stator winding temperature and stator winding resistance at 25 C. It is assumed that stator leakage reactance, core-loss resistance, friction and windage losses and stray load losses corresponding to the nominal operation are known. The proposed method iteratively determines air gap voltage, power factor and some other parameters. The effects of temperature change, frequency change, magnetic saturation and stray load losses are taken into consideration. The application of the method is discussed within the existing examples of five different motors. Excellent accuracy is achieved using the proposed method.

关键词： Equivalent circuit Induction motor parameter estimation method Power-flow diagram Rotor cage temperature

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Electromagnetic scattering characteristics of flapping bird and experimental validation

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JOURNAL OF ENGINEERING-JOE 2019年第19期2019卷 5860-5863页

作者： Hu, Cheng Lang, Tianjiao Wang, Rui Liu, Changjiang Beijing Inst Technol Sch Informat & Elect Beijing Peoples R China

Bird flight has caused many scientists' interest for a long time, of which the flapping is the most common locomotion. Radar provides a powerful tool to observe birds' migration. Aerial birds can be characterised by their electromagnetic scattering characteristics and the radar cross-section (RCS) is one of the most important characteristics. The wings' attitudes of flying birds may induce the RCS values fluctuation;thus the authors can extract the flapping attitudes from the RCS values. In this article, a method of simulating the electromagnetic scattering characteristics of airborne birds was proposed, based on which the flapping attitudes of flapping birds in actual flights were extracted. First, electromagnetic scattering models of a flying bird with different flapping attitudes were built and the FEKO electromagnetic simulation software was used to obtain the bird target's electromagnetic scattering characteristics. Then, the relationship between the flapping angles and the RCS values of the model was studied and the parameters of the flapping angles model were estimated using a parameter estimation method. Finally, based on the measured data, the flapping attitudes of the bird in actual flights were extracted and the accuracy of the scattering model was validated.

关键词： parameter estimation radar cross-sections electromagnetic wave scattering biological techniques zoology computational electromagnetics atmospheric electromagnetic wave propagation flying bird FEKO electromagnetic simulation software electromagnetic scattering characteristics flapping bird bird flight aerial birds radar cross-section RCS values fluctuation airborne birds flapping angle model flapping attitudes parameter estimation method

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Computational Modeling of the Early Development of Embryonic Leaves in Maize 18

Computational Modeling of the Early Development of Embryonic...

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18th IEEE International Conference on Bioinformatics and Bioengineering

作者： Wang, Charles C. N. Chang, Pei-Chun Sheu, Phillip C. Y. Tsai, Jeffrey J. P. Asia Univ Dept Biomed Informat 500 Lioufeng Rd Taichung 41354 Taiwan Univ Calif Irvine Dept Elect Engn & Comp Sci 5200 Engn Hall Irvine CA USA

ISBN: (纸本)9781538662175

Maize is a well-studied crop. It has been used as a model plant for C4 studies of photosynthesis, as its leaves possess the Kranz Structure (KS). Unfortunately, only few studies addressed the use of computational models to describe dry maize. In particular, the mechanism of KS formation remains unclear during leaf development. This study aims to develop a computational model to answer the following two questions for leaf development in dry maze: (1) How Auxin inhibits BDL, and (2) How the MP transcription activates BDL in the seed of dry maize in early stages of embryonic leaves. We first analyze dry maize based on the S-systems model and compare it with two different regulatory networks: (1) Auxin inhibits BODENLOS (BDL), and (2) MONOPTEROS (MP) activates BODENLOS (BDL). Our hypotheses are: (1) Auxin does not inhibit BDL, and (2) MP does not activate BDL. In the second stage, we compare the S-systems parameter estimation method (SPEM) and the engineering method to analyze the two regulatory networks. Our result suggests a general mechanism for studying how the transient accumulation of Auxin activates self-sustaining and how, similar to other genetic switches, it results in unequivocal developmental responses of leaves in dry maize. The MP activates BDL are very important to the Auxin signaling mediated by MP and BDL proteins which are essential for cell-fate specification events in early embryogenesis of maize.

关键词： Maize C4 photosynthesis S-systems model parameter estimation method

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