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A new method for estimating the longevity and degradation of photovoltaic systems considering weather

Amir AHADI,Hosein HAYATI,Joydeep MITRA,Reza ABBASI-ASL,Kehinde AWODELE

《能源前沿（英文）》 2016年第10卷第3期页码 277-285 doi: 10.1007/s11708-016-0400-3

摘要： The power output of solar photovoltaic (PV) systems is affected by solar radiation and ambient temperature. The commonly used evaluation techniques usually overlook the four weather states which are clear, cloudy, foggy, and rainy. In this paper, an ovel analytical model of the four weather conditions based on the Markov chain is proposed. The Markov method is well suited to estimate the reliability and availability of systems based on a continuous stochastic process. The proposed method is generic enough to be applied to reliability evaluation of PV systems and even other applications. Further aspects investigated include the new degradation model for reliability predication of PV modules. The results indicate that the PV module degradation over years, failures, and solar radiation must be considered in choosing an efficient PV system with an optimal design to achieve the maximum benefit of the PV system. For each aspect, a method is proposed, and the complete focusing methodology is expounded and validated using simulated point targets. The results also demonstrate the feasibility and applicability of the proposed method for effective modeling of the chronological aspects and stochastic characteristics of solar cells as well as the optimal configuration and sizing of large PV plants in terms of cost and reliability.

关键词： photovoltaic (PV) systems solar cell Markov model weather effects

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Research on pedestrian escape route without visibility based on Markov chain model

Xiaoping ZHENG, Lijuan DU, Hongjiang WANG,

《化学科学与工程前沿（英文）》 2010年第4卷第3期页码 283-289 doi: 10.1007/s11705-009-0272-8

摘要： It is a pioneering work to use a Markov chain model to study the pedestrian escape route without visibility. In this paper, based on the Markov chain probability transition matrix, the algorithms with random numbers and the spatial-grid, an escape route in a limited invisible space is obtained. Six pace states (standing, crawling, walking, leaping, jogging, and running) are applied to describe the characteristics of pedestrian behaviors. Besides, eight main direction changes are used to describe the transition characteristic of a pedestrian. At the same time, this paper analyzes the escape route from two views, i.e., pedestrian pace states and directions. The research results show that the Markov chain model is more realistic as a means of studying pedestrian escape routes.

关键词： pioneering direction spatial-grid realistic transition characteristic

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Generating capacity adequacy evaluation of large-scale, grid-connected photovoltaic systems

Amir AHADI,Seyed Mohsen MIRYOUSEFI AVAL,Hosein HAYATI

《能源前沿（英文）》 2016年第10卷第3期页码 308-318 doi: 10.1007/s11708-016-0415-9

摘要： Large-scale, grid-connected photovoltaic systems have become an essential part of modern electric power distribution systems. In this paper, a novel approach based on the Markov method has been proposed to investigate the effects of large-scale, grid-connected photovoltaic systems on the reliability of bulk power systems. The proposed method serves as an applicable tool to estimate performance (e.g., energy yield and capacity) as well as reliability indices. The Markov method framework has been incorporated with the multi-state models to develop energy states of the photovoltaic systems in order to quantify the effects of the photovoltaic systems on the power system adequacy. Such analysis assists planners to make adequate decisions based on the economical expectations as well as to ensure the recovery of the investment costs over time. The failure states of the components of photovoltaic systems have been considered to evaluate the sensitivity analysis and the adequacy indices including loss of load expectation, and expected energy not supplied. Moreover, the impacts of transitions between failures on the reliability calculations as well as on the long- term operation of the photovoltaic systems have been illustrated. Simulation results on the Roy Billinton test system has been shown to illustrate the procedure of the proposed frame work and evaluate the reliability benefits of using large-scale, grid-connected photovoltaic system on the bulk electric power systems. The proposed method can be easily extended to estimate the operating and maintenance costs for the financial planning of the photovoltaic system projects.

关键词： adequacy assessment Markov method large-scale grid-connected photovoltaic(PV) systems long-term operation

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Identification of pollution sources in rivers using a hydrodynamic diffusion wave model and improved Bayesian-Markov

《环境科学与工程前沿（英文）》 2023年第17卷第7期 doi: 10.1007/s11783-023-1685-1

摘要：

● A hydrodynamic-Bayesian inference model was developed for water pollution tracking.

关键词： Identification of pollution sources Water quality restoration Bayesian inference Hydrodynamic model Inverse problem

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火灾事故的灰色-马尔可夫模型预测研究

毛占利,朱毅,杨伯忠,朱磊

《中国工程科学》 2010年第12卷第1期页码 98-101

摘要：

鉴于火灾事故的发生受多种复杂因素的影响，并且具有较大的随机性和波动性的特点，笔者等将灰色模型和马尔可夫模型相结合，建立火灾事故的灰色–马尔可夫模型，利用灰色模型的灰色性和马尔可夫模型的随机性来体现各自的优点，并运用该模型对全国农村火灾事故进行预测。实际应用表明，灰色–马尔可夫模型的预测精度明显高于灰色模型的预测精度，完全能满足预测精度的要求，可以较好地用于火灾事故的预测。

关键词：灰色模型马尔可夫模型火灾事故预测

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马尔可夫网络排队模型在电梯配置中的应用

宗群,程义菊,宋军远

《中国工程科学》 2003年第5卷第10期页码 69-72

摘要：

利用马尔可夫网络排队理论建立了电梯交通模型，在此基础上对各服务站的电梯配置交通进行计算，得到电梯的配置参数。通过与传统的电梯配置方法相比较，显示出明显的优越性，也表明了利用马尔可夫网络排队模型进行电梯配置的有效性和可行性。

关键词：马尔可夫网络排队理论电梯交通模型优化电梯配置

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Sequential degradation-based burn-in test with multiple periodic inspections

《工程管理前沿（英文）》 2021年第8卷第4期页码 519-530 doi: 10.1007/s42524-021-0166-0

摘要： Burn-in has been proven effective in identifying and removing defective products before they are delivered to customers. Most existing burn-in models adopt a one-shot scheme, which may not be sufficient enough for identification. Borrowing the idea from sequential inspections for remaining useful life prediction and accelerated lifetime test, this study proposes a sequential degradation-based burn-in model with multiple periodic inspections. At each inspection epoch, the posterior probability that a product belongs to a normal one is updated with the inspected degradation level. Based on the degradation level and the updated posterior probability, a product can be disposed, put into field use, or kept in the test till the next inspection epoch. We cast the problem into a partially observed Markov decision process to minimize the expected total burn-in cost of a product, and derive some interesting structures of the optimal policy. Then, algorithms are provided to find the joint optimal inspection period and number of inspections in steps. A numerical study is also provided to illustrate the effectiveness of our proposed model.

关键词： burn-in degradation multiple inspections Wiener process partially observed Markov decision process

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基于广义极值分布和马尔科夫随机场的全极化合成孔径雷达图像潮间带区域地物分类方法 None

Ting-ting JIN, Xiao-qiang SHE, Xiao-lan QIU, Bin LEI

《信息与电子工程前沿（英文）》 2019年第20卷第2期页码 253-264 doi: 10.1631/FITEE.1700462

摘要：考虑到潮汐波动的复杂性和剧烈性，合成孔径雷达（SAR）图像的潮间带区域地物分类是一个重要且具有挑战性的问题。潮间带区域地物分类难点在于，潮间带有很大比例区域经常被海水淹没，使得利用空间信息的统计建模方法常常失效。考虑到极化熵和各向异性在潮间带特征描述中的重要作用，提出一种新的无监督地物分类算法。该算法将广义极值分布模型（GEV）的极化特征与马尔可夫随机场（MRF）的平滑滤波结合，并加入拟合优度检验，以确定统计模型各组成部分的显著性。将极化熵和各向异性的分类结果有效结合，得到最终分类结果。最后，基于中国高分三号SAR卫星获得的全极化数据进行实验，实验结果证明所提方法的可行性和优越性。

关键词：潮间带区域地物分类；极化合成孔径雷达；有限混合模型；马尔可夫随机场；广义极值分布模型

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Image-based fall detection and classification of a user with a walking support system

Sajjad TAGHVAEI, Kazuhiro KOSUGE

《机械工程前沿（英文）》 2018年第13卷第3期页码 427-441 doi: 10.1007/s11465-017-0465-7

摘要：

The classification of visual human action is important in the development of systems that interact with humans. This study investigates an image-based classification of the human state while using a walking support system to improve the safety and dependability of these systems. We categorize the possible human behavior while utilizing a walker robot into eight states (i.e., sitting, standing, walking, and five falling types), and propose two different methods, namely, normal distribution and hidden Markov models (HMMs), to detect and recognize these states. The visual feature for the state classification is the centroid position of the upper body, which is extracted from the user’s depth images. The first method shows that the centroid position follows a normal distribution while walking, which can be adopted to detect any non-walking state. The second method implements HMMs to detect and recognize these states. We then measure and compare the performance of both methods. The classification results are employed to control the motion of a passive-type walker (called “RT Walker”) by activating its brakes in non-walking states. Thus, the system can be used for sit/stand support and fall prevention. The experiments are performed with four subjects, including an experienced physiotherapist. Results show that the algorithm can be adapted to the new user’s motion pattern within 40 s, with a fall detection rate of 96.25% and state classification rate of 81.0%. The proposed method can be implemented to other abnormality detection/classification applications that employ depth image-sensing devices.

关键词： fall detection walking support hidden Markov model multivariate analysis

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Reliability evaluation of future photovoltaic systems with smart operation strategy

Amir AHADI,Hosein HAYATI,Seyed Mohsen MIRYOUSEFI AVAL

《能源前沿（英文）》 2016年第10卷第2期页码 125-135 doi: 10.1007/s11708-015-0392-4

摘要： This paper investigates a new operation strategy for photovoltaic (PV) systems, which improves the overall reliability of the system as a result of the improvement in the reliability of the critical components. First, a mathematical model is proposed using the fault tree analysis (FTA) to estimate the reliability of the PV systems in order to find the suitable maintenance strategies. The implementations demonstrate that it is essential to employ smart maintenance plans and monitor the identified most critical components of PV systems. Then, an innovative analytical method based on the Markov process is presented to model smart operation plans in PV systems. The impact of smart operation strategy on the PV systems is then evaluated. The objective of this paper is to develop plans for improving the reliability of PV systems. A series of case studies have been conducted to demonstrate the importance of smart operation strategies for PV systems as well as the applicability and feasibility of the proposed method.

关键词： smart operation strategy renewable energy fault tree analysis (FTA) Markov model

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State identification of home appliance with transient features in residential buildings

《能源前沿（英文）》 2022年第16卷第1期页码 130-143 doi: 10.1007/s11708-022-0822-z

摘要： Nonintrusive load monitoring (NILM) is crucial for extracting patterns of electricity consumption of household appliance that can guide users’ behavior in using electricity while their privacy is respected. This study proposes an online method based on the transient behavior of individual appliances as well as system steady-state characteristics to estimate the operating states of the appliances. It determines the number of states for each appliance using the density-based spatial clustering of applications with noise (DBSCAN) method and models the transition relationship among different states. The states of the working appliances are identified from aggregated power signals using the Kalman filtering method in the factorial hidden Markov model (FHMM). Thereafter, the identified states are confirmed by the verification of system states, which are the combination of the working states of individual appliances. The verification step involves comparing the total measured power consumption with the total estimated power consumption. The use of transient features can achieve fast state inference and it is suitable for online load disaggregation. The proposed method was tested on a high-resolution data set such as Labeled hIgh-Frequency daTaset for Electricity Disaggregation (LIFTED) and it outperformed other related methods in the literature.

关键词： nonintrusive load monitoring (NILM) load disaggregation online load disaggregation Kalman filtering factorial hidden Markov model (FHMM) Labeled hIgh-Frequency daTaset for Electricity Disaggregation (LIFTED)

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Time-series prediction based on global fuzzy measure in social networks

Li-ming YANG,Wei ZHANG,Yun-fang CHEN

《信息与电子工程前沿（英文）》 2015年第16卷第10期页码 805-816 doi: 10.1631/FITEE.1500025

摘要： Social network analysis (SNA) is among the hottest topics of current research. Most measurements of SNA methods are certainty oriented, while in reality, the uncertainties in relationships are widely spread to be overridden. In this paper, fuzzy concept is introduced to model the uncertainty, and a similarity metric is used to build a fuzzy relation model among individuals in the social network. The traditional social network is transformed into a fuzzy network by replacing the traditional relations with fuzzy relation and calculating the global fuzzy measure such as network density and centralization. Finally, the trend of fuzzy network evolution is analyzed and predicted with a fuzzy Markov chain. Experimental results demonstrate that the fuzzy network has more superiority than the traditional network in describing the network evolution process.

关键词： Time-series network Fuzzy network Fuzzy Markov chain

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多带同步模型用于噪声环境下语音识别

孙暐,吴镇扬

《中国工程科学》 2006年第8卷第3期页码 31-34

摘要：

根据人耳听觉特性，提出新的同步多带最大似然线性回归算法用于噪声环境下语音识别。该算法采用最大似然作为参数估计准则，利用各频带信号同步感知和噪声污染假定的方法进行语音模型补偿，有效地提高了识别系统在噪声环境下的识别性能。

关键词：隐马尔可夫模型最大似然多带同步模型语音识别

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无线局域网上IP语音传输的容量分析

陈立全,胡爱群,周雪莉

《中国工程科学》 2005年第7卷第7期页码 81-85

摘要：

由于无线媒介的易变性，IP语音在无线局域网上传输受到极大的限制。通过对无线局域网媒体接入层机制的分析，考虑了碰撞概率因素，提出了采用马尔可夫链模型来推导在IEEE 80211b/a/g标准下单个接入点同时支持IP语音用户最大容量的方法，计算出针对不同IP语音编码标准如G711，G729和G723.1下的用户容量上限。并在NS2仿真环境下进行结果验证。

关键词：无线局域网 IP语音容量马尔可夫链

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Capacity analysis for cognitive heterogeneous networks with ideal/non-ideal sensing

Tao HUANG, Ying-lei TENG, Meng-ting LIU, Jiang LIU

《信息与电子工程前沿（英文）》 2015年第16卷第1期页码 1-11 doi: 10.1631/FITEE.1400129

摘要： Due to irregular deployment of small base stations (SBSs), the interference in cognitive heterogeneous networks (CHNs) becomes even more complex; in particular, the uncertainty of spectrum mobility aggravates the interference context. In this case, how to analyze system capacity to obtain a closed-form expression becomes a crucial problem. In this paper we employ stochastic methods to formulate the capacity of CHNs and achieve a closed-form expression. By using discrete-time Markov chains (DTMCs), the spectrum mobility with respect to the arrival and departure of macro base station (MBS) users is modeled. Then an integral method is proposed to derive the interference based on stochastic geometry (SG). Also, the effect of sensing accuracy on network capacity is discussed by concerning false-alarm and miss-detection events. Simulation results are illustrated to show that the proposed capacity analysis method for CHNs can approximate the conventional sum methods without rigorous requirement for channel station information (CSI). Therefore, it turns out to be a feasible and efficient way to capture the network capacity in CHNs.

关键词： Cognitive heterogeneous networks Markov chain Stochastic geometry Homogeneous Poisson point process (HPPP)