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Affine Power Flow Multi-scenario Uncertainty Analysis Method for Power System

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Dianwang Jishu/Power System Technology 2025年第1期49卷 252-262页

作者： Chen, Feixiong Wu, Hongbin Shao, Zhenguo li, yimin Zhang, He Su, Weiqi Key Laboratory of Energy Digitalization Fujian Province University Fuzhou University Fujian Province Fuzhou 350108 China Quanzhou Power Supply Company of State Grid Fujian Power Co. Ltd. Fujian Province Quanzhou 362000 China

The power flow solution calculated by the existing affine power flow method can only reflect the power flow distribution of the system in a certain range of the source load power, which is difficult to meet the online calculation requirements of multi-scenario uncertainty analysis. To solve these problems, an affine power flow multi-scenario uncertainty analysis method is proposed in this paper. Various holomorphic embedding variables with different physical meanings are used to scale the central values and partial deviation coefficients of the affine injection power. In this way, the interval variation of uncertain injection power is tracked and described, and the analytical dimension of the affine power flow is expanded from one dimension to multiple dimensions. The calculation of affine power flow is divided into two parts: analytic expression solving and online calculation. The multivariate power series coefficients of affine status variables are solved recursively, and the analytical expression for affine power flow is obtained. The online calculation of affine power flow in specific scenarios is realized by substituting the target value of embedded variables. The simulation results verify the advantages of the proposed method in convergence, conservatism and multi-scenario analysis efficiency. © 2025 Power System Technology Press. All rights reserved.

关键词： Load flow control

Assessment of Flue Gas Reinjecting Operating Strategy in Performance of CCHP System using Energy Level Difference Analysis

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Journal of Thermal Science 2023年第1期32卷 125-134页

作者： WANG Zefeng HAN Wei li yimin Beijing Huairou Laboratory Beijing 101400China Institute of Engineering Thermophysics Chinese Academy of SciencesBeijing 100190China University of Chinese Academyof Sciences Beijing 100049China

A proper operating strategy is helpful to improve the off-design performance of combined cooling,heating and power(CCHP)systems,providing high efficiency and low *** energy level difference graphic analysis method is used to identify energy level as well as exergy destruction of the part-load *** method illustrates the energy efficiency upgrading mechanism of the flue gas reinjecting(FGR)operating *** is referenced to a reducing turbine inlet temperature(TIT)operating *** comparison,the FGR operating strategy leads to a 2.62%exergy distribution reduction in a gas turbine at an 85%load level due to the decrease of the energy level *** the output power is reduced further,the FGR operating strategy is supplanted by the TIT operating strategy with the limit of compressor inlet ***,the opposite results of exergy distribution are presented in the exhaust-heat recovery devices.A heat-driven refrigeration and power cycle is introduced in a typical CCHP system as a ***,the results suggest that the operational flexibility of the CCHP system is improved by enlarging the ratio of cooling to electricity.

关键词： CCHP systems off-design performance energy level difference analysis operating strategies

基于优化MaxEnt模型的怒江州滑坡易发性评价

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河南理工大学学报（自然科学版） 2025年第1期44卷 57-67页

作者：李益敏向倩英邓选伦冯显杰云南大学地球科学学院云南昆明650500 云南大学云南省高校国产高分卫星遥感地质工程研究中心云南昆明650500 云南大学国际河流与生态安全研究院云南昆明650500

目的怒江州是典型的高山峡谷地区,地质灾害(滑坡)频发,严重制约着当地的发展。为解决这一问题,方法综合考虑怒江州实际情况,从气象水文、地形地貌、地层岩性、植被生态和人类活动5个方面选取坡向,高程等14个影响因子,判断滑坡与各影... 详细信息

目的怒江州是典型的高山峡谷地区,地质灾害(滑坡)频发,严重制约着当地的发展。为解决这一问题,方法综合考虑怒江州实际情况,从气象水文、地形地貌、地层岩性、植被生态和人类活动5个方面选取坡向,高程等14个影响因子,判断滑坡与各影响因子间相关性,构建评价指标体系,对最大熵(maximum entropy, MaxEnt)模型的特征类(feature combination,FC)和正则化乘数(regularization multiplier, RM)参数进行优化,对比优化前后小样本赤池信息量准则(akaikeinformationcriterion,AIC)、遗漏率(omissionrate,OR)和AUC(areaunder curve),并基于优化的MaxEnt模型预测滑坡灾害的发生,实现怒江州滑坡易发性评价。结果结果表明:优化后的MaxEnt模型在研究区滑坡易发性预测中适用性优秀(AUC=0.913);运用刀切法(Jackknife)计算各影响因子对易发性的影响程度,高程(S3, 23.2%)、坡度(S9, 22.4%)、居民点密度(S5, 14.2%)、距河流距离(S13, 13.7%)、距道路距离(S4, 9.6%)和岩性(S7, 8.7%)是前六位影响因子,累计贡献度达91.8%;极高、高、中、低滑坡易发性等级的空间占比分别为4.88%,8.96%,18.40%,67.76%,县域中极高和高易发区占比最大的是泸水市,整体上看,极高、高易发区主要沿河流和道路分布于峡谷中,低易发区主要分布于人类活动少、河谷不发育的区域。结论优化后的MaxEnt模型更适合怒江州滑坡易发性预测,研究结果可为怒江州防灾减灾与土地利用规划提供参考。

关键词：怒江州最大熵模型滑坡易发性

Simulation and control scheme of microstructure in magnetic fluids

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Science China(Technological Sciences) 2007年第3期50卷 371-379页

作者： li Qiang XUAN yimin li Bin School of Power Engineering Nanjing University of Science&TechnologyNanjing 210094China

By accounting for the external and internal force acting on the suspended magnetic nanoparticles and motion characteristics of the suspended magnetic nanoparticles in the magnetic fluids,the three-dimensional microstructure of magnetic fluids is investigated by means of the molecular dynamics simulation method. The distribu-tion of suspended magnetic nanoparticles and microstructure of the magnetic fluid are simulated in both absence and presence of an external magnetic field. The ef-fects of the nanoparticles volume fraction,the dipole-dipole interaction potential and the particle-field interaction potential on the microstructures of the magnetic fluids are discussed. The main results obtained here are summarized as follows. The suspended magnetic nanoparticles tend to aggregate and make the irregular distribution structure in the absence of an external magnetic field. When the mag-netic fluid is exposed to a magnetic field,the magnetic nanoparticles suspended in the carrier fluid tend to remain chained-alignment in the direction of the external magnetic field. The tendency of chain-alignment morphology of the suspended magnetic nanoparticles is enhanced with the nanoparticles volume fraction,the dipole-dipole interaction potential and the particle-field interaction potential.

关键词： magnetic fluid molecular dynamics simulation microstructure chained-alignment

Preparation and properties of PPSU/GO mixed matrix membrane

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Chinese Journal of Chemical Engineering 2017年第4期25卷 408-414页

作者： Shujuan Xiao shouwu Yu li Yan Ying liu Xiaoyao Tan School of Material Science and Engineering Tianjin Polytechnic UniversityTianjin 300387China Qing gong College North China University of Sdence and TechnologyYangshan 063009China College of Materials Sdence and Engineering North China University of Science and TechnologyYangshan 063009China College of Foreign Languages North China University of Science and TechnologyTangshan 063009China

Polyphenylene sulfone/graphene oxide(PPSU/GO) mixed matrix membranes with different GO contents are prepared by phase inversion technique using, PEG-1000 as porogen, and N,N-dimethylacetamide(DMAC) as *** hydrophilicity and pure water flux of the membrane are investigated. The morphology, hydrophilicity, thermodynamic stability and compatibility of the membranes are characterized by various techniques such as SEM,TGA, FTIR and so on. The permeation properties of the membrane are measured in terms of pure water flux and bovine serum albumin(BSA) retention. The results indicate that when the GO content is 1.5 wt%, an evenly distributed finger structure has been formed in the mixed matrix membranes. Owing to the presence of GO,the hydrophilicity and the thermal stability of the membranes are improved, and the fouling resistance is also enhanced.

关键词： finger permeation DMAC fouling thermodynamic evenly albumin irreversible dispersed porosity

Application of Sturm Theorem in the Global Controllability of a Class of High Dimensional Polynomial Systems

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Journal of Systems Science & Complexity 2015年第5期28卷 1049-1057页

作者： XU Xueli li Qianqian SUN yimin Guangdong Province Key Laboratory of Computational Science School of Mathematics and Computational Science Sun Yat-Sen University

In this paper, the global controllability for a class of high dimensional polynomial systems has been investigated and a constructive algebraic criterion algorithm for their global controllability has been obtained. By the criterion algorithm, the global controllability can be determined in finite steps of arithmetic operations. The algorithm is imposed on the coefficients of the polynomials only and the analysis technique is based on Sturm Theorem in real algebraic geometry and its modern ***, the authors will give some examples to show the application of our results.

关键词： Global controllability high dimensional systems number of sign variations polynomial Sturm theorem.

Spatial-temporal variation features and law of gas concentration in the fully mechanized working face under the condition of intermittent ventilation

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International Journal of Mining Science and Technology 2019年第6期29卷 963-969页

作者： Yinpin Cao yimin li Zhongning Zhou School of Electrical and Power Engineering China University of Mining & Technology

Based on the fluid mechanics and mass transfer theory,a mathematical model of the spatial-temporal variation of gas was derived to avoid the gas accident caused by the main fan stopping ventilation under the condition of intermittent ventilation in the *** to the actual parameters of the tunnel,a numerical calculation model was *** spatial-temporal variation of gas concentration in the fully mechanized working face under the condition of intermittent ventilation was calculated by using the commercial package Fluent,and the correctness of the calculated results was verified by the actual monitoring data of the ***,the gas concentration was calculated under different wind velocities at driving face in coal tunnel,and the result showed that the gas can be carried effectively by the wind when the wind velocity is about 1.8 m/***,the distributions of wind velocity and gas concentration at driving face were studied at 1.8 m/s,and the result showed the gas concentration increased gradually with the distance close to the outlet,but the gas concentration almost kept constant at the height of driving ***,the distribution of gas concentration was investigated with time after the ventilation was stopped and restarted,*** gas concentration of test point gradually increased with the increment of downtime,when the downtime was 40 min,the gas concentration of test point 3 reached the maximum *** gas concentration increased gradually and reached the maximum after10 min of restart,then sharply decreased and kept constant.

关键词： Fully mechanized working face Intermittent ventilation Gas concentration

IMPROVEMENT OF RHEOLOGICAL AND SHAPE RETENTION PROPERTIES OF WAX-BASED MIM BINDER BY MULTI-POLYMER COMPONENTS

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中国有色金属学会会刊：英文版 1999年第1期9卷 24-31页

作者： li, yimin Huang, Baiyun Qu, Xuanhui Central South Univ of Technology Changsha China

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关键词： rheological property metal injection molding (MIM) binder polymer component

Reliability-based Maintenance Optimization under Imperfect Predictive Maintenance

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Chinese Journal of Mechanical Engineering 2012年第1期25卷 160-165页

作者： li Changyou ZHANG yimin XU Minqiang School of Astronautics Harbin Institute of TechnologyHarbin 150001China School of Mechanical Engineering and Automa tion Northeastern UniversityShenyang 110004China

The reliability-based maintenance optimization model has been focused by the engineers and scholars but it has never been solved effectively to formulate the effect of a maintenance action on the optimization model. In existing works, the system reliability was assumed to be increased to 1 after a predictive maintenance. However, it is very difficult in the most practical systems. Therefore, a new reliability-based maintenance optimization model under imperfect predictive maintenance (PM) is proposed in this paper. In the model, the system reliability is only restored to R i (0lity in two cases whether there is an unexpected fault in one cycle are derived respectively and the system expected uptime model is given. To formulate the system expected downtime, the probability of each imperfect PM number in one cycle is calculated. Then, the system expected total time model is obtained. The total expected long-term operation cost is composed of the expected maintenance cost, the expected loss due to the downtime and the expected additional cost due to the occurrence of an unexpected failure. They are modeled respectively in this work. Jointing the system expected total time and long-term operation cost in one cycle, the expected long-term operation cost per time could be computed. Then, the proposed maintenance optimization model is formulated where the objective function is to minimize the expected long-term operation cost per time. The results of numerical example show that the proposed model could scheme the optimal maintenance actions for the considered system when the required parameters are given and the optimal solution of the proposed model is sensitive to the parameters of effective age model and insensitive to other parameters. The proposed model effectively solves the problem of evaluating the effect of an imperfect PM on the system reliability and presents

关键词： imperfect predictive maintenance reliability maintenance optimization cost