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Short-term prediction of the influent quantity time series of wastewater treatment plant based on a chaos

LI Xiaodong, ZENG Guangming, HUANG Guohe, LI Jianbing, JIANG Ru

《环境科学与工程前沿（英文）》 2007年 第1卷 第3期   页码 334-338 doi: 10.1007/s11783-007-0057-6

摘要： By predicting influent quantity, a wastewater treatment plant (WWTP) can be well controlled. The nonlinear dynamic characteristic of WWTP influent quantity time series was analyzed, with the assumption that the series was predictable. Based on this, a short-term forecasting chaos neural network model of WWTP influent quantity was built by phase space reconstruction. Reasonable forecasting results were achieved using this method.

关键词： nonlinear     reconstruction     WWTP influent     characteristic     Reasonable forecasting    

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Optimal dispatch of multi energy system using power-to-gas technology considering flexible load on user side

Zi LING, Xiu YANG, Zilin LI

《能源前沿（英文）》 2018年 第12卷 第4期   页码 569-581 doi: 10.1007/s11708-018-0595-6

摘要：

The relation between power-to-gas technology (P2G) and energy interconnection becomes increasingly close. Meanwhile, the participation of flexible load on user side in system optimization has attracted much attention as an efficient approach to relieve the contradiction between energy supply and energy demand. Based on the concept of energy hub, according to its series characteristic, this paper established a generic multi-energy system model using the P2G technology. The characteristic of flexible load on user side was considered and optimal dispatch analysis was made, so as to reduce the cost, to reasonably dispatch the flexible load, to reduce the discharge, to enhance the new energy output, and to increase the power-to-gas conversion efficiency. Finally, a concrete analysis was made on the optimal dispatch result of the multi-energy system using the P2G technology considering flexible load on user side in the calculating example, and optimal dispatch of the system was verified via four different scenarios. The results indicate that cooperative dispatch of multi-energy system using the P2G technology considering flexible load on user side is the most economic, and can make a contribution to absorption of new energy and P2G conversion. In this way, environmental effects and safe and stable operation of the system can be guaranteed.

关键词： multi-energy system     energy hub     series characteristic     optimal dispatch     flexible load    

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Analyzing construction safety through time series methods

Houchen CAO, Yang Miang GOH

《工程管理前沿（英文）》 2019年 第6卷 第2期   页码 262-274 doi: 10.1007/s42524-019-0015-6

摘要： The construction industry produces a large amount of data on a daily basis. However, existing data sets have not been fully exploited in analyzing the safety factors of construction projects. Thus, this work describes how temporal analysis techniques can be applied to improve the safety management of construction data. Various time series (TS) methods were adopted for identifying the leading indicators or predictors of construction accidents. The data set used herein was obtained from a large construction company that is based in Singapore and contains safety inspection scores, accident cases, and project-related data collected from 2008 to 2015. Five projects with complete and sufficient data for temporal analysis were selected from the data set. The filtered data set contained 23 potential leading indicators (predictors or input variables) of accidents (output or dependent variable). TS analyses were used to identify suitable accident predictors for each of the five projects. Subsequently, the selected input variables were used to develop three different TS models for predicting accident occurrences, and the vector error correction model was found to be the best model. It had the lowest root mean squared error value for three of the five projects analyzed. This study provides insights into how construction companies can utilize TS data analysis to identify projects with high risk of accidents.

关键词： time series     temporal     construction safety     leading indicators     accident prevention     forecasting    

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General expression for linear and nonlinear time series models

Ren HUANG, Feiyun XU, Ruwen CHEN

《机械工程前沿（英文）》 2009年 第4卷 第1期   页码 15-24 doi: 10.1007/s11465-009-0015-z

摘要： The typical time series models such as ARMA, AR, and MA are founded on the normality and stationarity of a system and expressed by a linear difference equation; therefore, they are strictly limited to the linear system. However, some nonlinear factors are within the practical system; thus, it is difficult to fit the model for real systems with the above models. This paper proposes a general expression for linear and nonlinear auto-regressive time series models (GNAR). With the gradient optimization method and modified AIC information criteria integrated with the prediction error, the parameter estimation and order determination are achieved. The model simulation and experiments show that the GNAR model can accurately approximate to the dynamic characteristics of the most nonlinear models applied in academics and engineering. The modeling and prediction accuracy of the GNAR model is superior to the classical time series models. The proposed GNAR model is flexible and effective.

关键词： linear and nonlinear     autoregressive model     system identification     time series analysis    

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Decreasing complexity of glucose time series derived from continuous glucose monitoring is correlated

《医学前沿（英文）》 2023年 第17卷 第1期   页码 68-74 doi: 10.1007/s11684-022-0955-9

摘要： Most information used to evaluate diabetic statuses is collected at a special time-point, such as taking fasting plasma glucose test and providing a limited view of individual’s health and disease risk. As a new parameter for continuously evaluating personal clinical statuses, the newly developed technique “continuous glucose monitoring” (CGM) can characterize glucose dynamics. By calculating the complexity of glucose time series index (CGI) with refined composite multi-scale entropy analysis of the CGM data, the study showed for the first time that the complexity of glucose time series in subjects decreased gradually from normal glucose tolerance to impaired glucose regulation and then to type 2 diabetes (P for trend < 0.01). Furthermore, CGI was significantly associated with various parameters such as insulin sensitivity/secretion (all P < 0.01), and multiple linear stepwise regression showed that the disposition index, which reflects β-cell function after adjusting for insulin sensitivity, was the only independent factor correlated with CGI (P < 0.01). Our findings indicate that the CGI derived from the CGM data may serve as a novel marker to evaluate glucose homeostasis.

关键词： complexity of glucose time series     continuous glucose monitoring     impaired glucose regulation     insulin secretion and sensitivity     refined composite multi-scale entropy    

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Analysis of the dynamic hysteresis characteristic of finger seal

LEI Yanni, CHEN Guoding

《机械工程前沿（英文）》 2007年 第2卷 第1期   页码 32-36 doi: 10.1007/s11465-007-0005-y

摘要： The research about hysteresis characteristic of finger seal (FS), which was carried out based on the model with static loads, could not reflect the dynamics behavior of FS system when the rotor runs at high speed. To solve this problem, the relations between the dynamics parameters, structure parameters as well as working parameters in the system were given out through the analysis of finite element analysis result. A mass spring damper dynamics model of FS system was proposed and the hysteresis characteristic of the FS system was analyzed. This work shows that the dynamics characteristic analysis of the FS is necessary and the dynamics model proposed in this paper is valid. This dynamics model is the basis for the optimization design of FS system.

关键词： FS     necessary     hysteresis characteristic     optimization     spring    

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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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A MATLAB code for the material-field series-expansion topology optimization method

《机械工程前沿（英文）》 2021年 第16卷 第3期   页码 607-622 doi: 10.1007/s11465-021-0637-3

摘要： This paper presents a MATLAB implementation of the material-field series-expansion (MFSE) topo-logy optimization method. The MFSE method uses a bounded material field with specified spatial correlation to represent the structural topology. With the series-expansion method for bounded fields, this material field is described with the characteristic base functions and the corresponding coefficients. Compared with the conventional density-based method, the MFSE method decouples the topological description and the finite element discretization, and greatly reduces the number of design variables after dimensionality reduction. Other features of this method include inherent control on structural topological complexity, crisp structural boundary description, mesh independence, and being free from the checkerboard pattern. With the focus on the implementation of the MFSE method, the present MATLAB code uses the maximum stiffness optimization problems solved with a gradient-based optimizer as examples. The MATLAB code consists of three parts, namely, the main program and two subroutines (one for aggregating the optimization constraints and the other about the method of moving asymptotes optimizer). The implementation of the code and its extensions to topology optimization problems with multiple load cases and passive elements are discussed in detail. The code is intended for researchers who are interested in this method and want to get started with it quickly. It can also be used as a basis for handling complex engineering optimization problems by combining the MFSE topology optimization method with non-gradient optimization algorithms without sensitivity information because only a few design variables are required to describe relatively complex structural topology and smooth structural boundaries using the MFSE method.

关键词： MATLAB implementation     topology optimization     material-field series-expansion method     bounded material field     dimensionality reduction    

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Performance analysis of series/parallel and dual side LCC compensation topologies of inductive power

P. Srinivasa Rao NAYAK, Dharavath KISHAN

《能源前沿（英文）》 2020年 第14卷 第1期   页码 166-179 doi: 10.1007/s11708-018-0549-z

摘要： In an inductive battery charging system, for better power transfer capability and attaining required power level, compensation is necessary. This paper analyzes series/parallel (S/P) and dual side inductor-capacitor-capacitor (LCC) compensation topologies for inductive power transfer of electric vehicle (EV) battery charging system. The design and modeling steps of inductive power transfer for electric vehicle battery charging system are presented. Besides, the equivalent electrical circuits are used to describe the circuit compensation topologies. The results convey that the efficiency of dual side LCC compensation is higher than that of S/P compensation at variable mutual inductance (misalignment).

关键词： series/parallel compensation     electric vehicle (EV)     dual side LCC compensation     inductive power transfer    

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Achieving desired nodal lines in freely vibrating structures via material-field series-expansion topology

《机械工程前沿（英文）》 2023年 第18卷 第3期 doi: 10.1007/s11465-023-0758-y

摘要： Accurately controlling the nodal lines of vibrating structures with topology optimization is a highly challenging task. The major difficulties in this type of problem include a large number of design variables, the highly nonlinear and multi-peak characteristics of iteration, and the changeable orders of eigenmodes. In this study, an effective material-field series-expansion (MFSE)-based topology optimization design strategy for precisely controlling nodal lines is proposed. Here, two typical optimization targets are established: (1) minimizing the difference between structural nodal lines and their desired positions, and (2) keeping the position of nodal lines within the specified range while optimizing certain dynamic performance. To solve this complex optimization problem, the structural topology of structures is first represented by a few design variables on the basis of the MFSE model. Then, the problems are effectively solved using a sequence Kriging-based optimization algorithm without requiring design sensitivity analysis. The proposed design strategy inherently circumvents various numerical difficulties and can effectively obtain the desired vibration modes and nodal lines. Numerical examples are provided to validate the proposed topology optimization models and the corresponding solution strategy.

关键词： nodal line     topology optimization     structural dynamics design     material-field series-expansion    

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Flow characteristic and wastewater treatment performance of a pilot-scale airlift oxidation ditch

Hongtao PANG, Hanchang SHI, Huiming SHI,

《环境科学与工程前沿（英文）》 2009年 第3卷 第4期   页码 470-476 doi: 10.1007/s11783-009-0143-z

摘要： A pilot-scale airlift oxidation ditch using bubble diffuser and baffle as aerator was operated in a wastewater treatment plant (WWTP) to investigate its flow characteristic and wastewater treatment performance. Compared with the conventional oxidation ditch process, effective depth and oxygen utilization efficiency of this new process was improved by underwater aeration. Furthermore, it had a reversed velocity distribution, which decreased from the bottom to the top on vertical section. Velocity measurement showed that a velocity over 0.2m/s at the bottom was sufficient to prevent sludge settlement during long term operation. Application of these concepts would save land area and energy consumption by about 25%―50% and 55%, respectively. In this new system, organic biodegradation and nitrification could be well achieved. Denitrification could occur steadily in the straight part by adjusting the airflow rate. An average TN removal rate of 63% was achieved with dissolved oxygen (DO) concentrations between 0.6mg/L and 1.5mg/L. The main pollutants in the effluent could meet the strictest discharge standard (COD<50mg/L, NH―N<5mg/L, and TN<15mg/L) in China now.

关键词： airlift oxidation ditch     flow characteristic     wastewater treatment    

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Weak characteristic information extraction from early fault of wind turbine generator gearbox

Xiaoli XU, Xiuli LIU

《机械工程前沿（英文）》 2017年 第12卷 第3期   页码 357-366 doi: 10.1007/s11465-017-0423-4

摘要：

Given the weak early degradation characteristic information during early fault evolution in gearbox of wind turbine generator, traditional singular value decomposition (SVD)-based denoising may result in loss of useful information. A weak characteristic information extraction based on µ-SVD and local mean decomposition (LMD) is developed to address this problem. The basic principle of the method is as follows: Determine the denoising order based on cumulative contribution rate, perform signal reconstruction, extract and subject the noisy part of signal to LMD and µ-SVD denoising, and obtain denoised signal through superposition. Experimental results show that this method can significantly weaken signal noise, effectively extract the weak characteristic information of early fault, and facilitate the early fault warning and dynamic predictive maintenance.

关键词： wind turbine generator gearbox     µ-singular value decomposition     local mean decomposition     weak characteristic information extraction     early fault warning    

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Employing electricity-consumption monitoring systems and integrative time-series analysis models: A case

Seiya MAKI, Shuichi ASHINA, Minoru FUJII, Tsuyoshi FUJITA, Norio YABE, Kenji UCHIDA, Gito GINTING, Rizaldi BOER, Remi CHANDRAN

《能源前沿（英文）》 2018年 第12卷 第3期   页码 426-439 doi: 10.1007/s11708-018-0560-4

摘要：

The Paris Agreement calls for maintaining a global temperature less than 2°C above the pre-industrial level and pursuing efforts to limit the temperature increase even further to 1.5°C. To realize this objective and promote a low-carbon society, and because energy production and use is the largest source of global greenhouse-gas (GHG) emissions, it is important to efficiently manage energy demand and supply systems. This, in turn, requires theoretical and practical research and innovation in smart energy monitoring technologies, the identification of appropriate methods for detailed time-series analysis, and the application of these technologies at urban and national scales. Further, because developing countries contribute increasing shares of domestic energy consumption, it is important to consider the application of such innovations in these areas. Motivated by the mandates set out in global agreements on climate change and low-carbon societies, this paper focuses on the development of a smart energy monitoring system (SEMS) and its deployment in households and public and commercial sectors in Bogor, Indonesia. An electricity demand prediction model is developed for each device using the Auto-Regression eXogenous model. The real-time SEMS data and time-series clustering to explore similarities in electricity consumption patterns between monitored units, such as residential, public, and commercial buildings, in Bogor is, then, used. These clusters are evaluated using peak demand and Ramadan term characteristics. The resulting energy-prediction models can be used for low-carbon planning.

关键词： electricity monitoring     electricity demand prediction     multiple-variable time-series modeling     time-series cluster analysis     Indonesia    

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长征三号系列运载火箭

龙乐豪

《中国工程科学》 1999年 第1卷 第1期   页码 11-18

摘要：

论述了长征三号系列运载火箭诞生的背景、设计思路、总体技术方案、应用发射结果及其在技术与研制工作方面的特点，展望了其发展前景，指出该系列运载火箭是我国目前性能先进的大型主力商业应用发射火箭群体。

关键词： 航天     大型运载火箭     发射服务     长征三号系列    

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Fractal characteristic evaluation and interpolation reconstruction for surface topography of drilled

《机械工程前沿（英文）》 2021年 第16卷 第4期   页码 840-854 doi: 10.1007/s11465-021-0643-5

摘要： In this paper, an improved fractal interpolation model is proposed to reconstruct the surface topography of composite hole wall. This model adopts the maximum positive deviations and maximum negative deviations between the measured values and trend values to determine the contraction factors. Hole profiles in 24 directions are measured. Fractal parameters are calculated to evaluate the measured surface profiles. The maximum and minimum fractal dimension of the hole wall are 1.36 and 1.07, whereas the maximum and minimum fractal roughness are 4.05 × 10 −5 and 4.36 × 10 −10 m, respectively. Based on the two-dimensional evaluation results, three-dimensional surface topographies in five typical angles (0°, 45°, 90°, 135°, and 165°) are reconstructed using the improved model. Fractal parameter D s and statistical parameters Sa, Sq, and Sz are used to evaluate the reconstructed surfaces. Average error of D s, Sa, Sq, and Sz between the measured surfaces and the reconstructed surfaces are 1.53%, 3.60%, 5.60%, and 9.47%, respectively. Compared with the model in published literature, the proposed model has equal reconstruction effect in relatively smooth surface and is more advanced in relatively rough surface. Comparative results prove that the proposed model for calculating contraction factors is more reasonable.

关键词： surface topography     fractal evaluation     fractal interpolation     reconstruction     composite    

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标题 作者 时间 类型 操作

Short-term prediction of the influent quantity time series of wastewater treatment plant based on a chaos

LI Xiaodong, ZENG Guangming, HUANG Guohe, LI Jianbing, JIANG Ru

期刊论文

Optimal dispatch of multi energy system using power-to-gas technology considering flexible load on user side

Zi LING, Xiu YANG, Zilin LI

期刊论文

Analyzing construction safety through time series methods

Houchen CAO, Yang Miang GOH

期刊论文

General expression for linear and nonlinear time series models

Ren HUANG, Feiyun XU, Ruwen CHEN

期刊论文

Decreasing complexity of glucose time series derived from continuous glucose monitoring is correlated

期刊论文

Analysis of the dynamic hysteresis characteristic of finger seal

LEI Yanni, CHEN Guoding

期刊论文

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

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

期刊论文

A MATLAB code for the material-field series-expansion topology optimization method

期刊论文

Performance analysis of series/parallel and dual side LCC compensation topologies of inductive power

P. Srinivasa Rao NAYAK, Dharavath KISHAN

期刊论文

Achieving desired nodal lines in freely vibrating structures via material-field series-expansion topology

期刊论文

Flow characteristic and wastewater treatment performance of a pilot-scale airlift oxidation ditch

Hongtao PANG, Hanchang SHI, Huiming SHI,

期刊论文

Weak characteristic information extraction from early fault of wind turbine generator gearbox

Xiaoli XU, Xiuli LIU

期刊论文

Employing electricity-consumption monitoring systems and integrative time-series analysis models: A case

Seiya MAKI, Shuichi ASHINA, Minoru FUJII, Tsuyoshi FUJITA, Norio YABE, Kenji UCHIDA, Gito GINTING, Rizaldi BOER, Remi CHANDRAN

期刊论文

长征三号系列运载火箭

龙乐豪

期刊论文

Fractal characteristic evaluation and interpolation reconstruction for surface topography of drilled

期刊论文