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基于仿真机理和改进回归决策树的二噁英排放建模
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作者 夏恒 汤健 +1 位作者 余文 乔俊飞 《自动化学报》 EI CAS CSCD 北大核心 2024年第8期1601-1619,共19页
城市固废焚烧(Municipal solid waste incineration,MSWI)过程是“世纪之毒”二噁英(Dioxin,DXN)的重要排放源之一.截止目前为止,DXN的演化机理和实时检测仍是尚未解决的难题.现有研究主要基于离线化验数据构建数据驱动模型,DXN的检测... 城市固废焚烧(Municipal solid waste incineration,MSWI)过程是“世纪之毒”二噁英(Dioxin,DXN)的重要排放源之一.截止目前为止,DXN的演化机理和实时检测仍是尚未解决的难题.现有研究主要基于离线化验数据构建数据驱动模型,DXN的检测未有效结合燃烧过程机理.针对该问题,本文提出基于仿真机理和改进线性回归决策树(Linear regression decision tree,LRDT)的DXN排放建模.首先,采用基于床层固废燃烧模拟软件FLIC(Fluid dynamic incinerator code)和过程工程先进系统软件(Advanced system for process engineering Plus,Aspen Plus)耦合的数值仿真模型,获取蕴含多运行工况的虚拟机理数据;接着,利用虚拟机理数据构建基于改进LRDT的CO_(2)、CO和O_(2)燃烧状态表征变量模型;然后,以真实CO_(2)、CO、O_(2)作为输入和以DXN真值作为输出,构建多入单出LRDT的过程映射模型(Process mapping model,PMM),再利用该模型进行半监督学习和结构迁移得到机理映射模型1(Mechanism mapping models1,MMM1);最后,通过结构增量学习获得基于半监督迁移学习的MMM2模型.在实验室的半实物平台和北京某MSWI厂的边侧验证平台对所提方法进行了工业应用验证.实验结果证明了所提方法与研发的软测量系统可有效实现二噁英排放浓度在线检测. 展开更多
关键词 城市固废焚烧 二噁英 燃烧状态 数值仿真机理 线性回归决策树 半监督迁移学习
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Wind?Induced Interference Effect Between Newly?Built Cooling Tower and Existing Cooling Tower
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作者 DU Lin KE Shitang +2 位作者 YANG Jie ZHU Rongkuan GE Yaojun 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI CSCD 2020年第1期88-98,共11页
Disturbance effect is one of the important factors for wind damage to large cooling towers.Existing studies on the wind-induced interference of cooling tower groups are aimed at the same size and the lack of wind-indu... Disturbance effect is one of the important factors for wind damage to large cooling towers.Existing studies on the wind-induced interference of cooling tower groups are aimed at the same size and the lack of wind-induced interference effects between cooling towers of different sizes.With the background of the additional cooling tower project at Shandong Luxi Power Plant in China,the rigid body pressure wind tunnel test is carried out to obtain 194 conditions for the three combinations of the existing four-tower combination(small size),the new two-tower combination(large size)and the six-tower combination surface wind pressure distribution.Numerical simulation of the surrounding flow field of the cooling tower group with the most unfavorable interference condition of the six-tower combination is conducted using the computational fluid dynamics(CFD)method.Based on this,the characteristics of the average and pulsating wind pressure distribution of the cooling tower surface under the six-tower combination are mainly studied,and the load interference coefficients of the large-sized cooling tower and the small-sized cooling tower under the three tower group combinations are compared.The velocity flow field and vorticity changes around the cooling tower group at unfavorable wind angles are analyzed,and the wind-induced interference mechanism between cooling tower groups of different sizes is mainly refined.Research shows that the interference effect between such cooling tower groups of different sizes is much larger than that of cooling tower groups of the same size,which is specifically manifested as the enhancement effect of small-sized cooling towers and the shielding effect of large-sized cooling towers.The interference coefficient of large-sized cooling tower groups increases by 28%,and the interference coefficient of small-sized cooling tower groups decreases by 6.4%.The airflow acceleration caused by the pinch effect between small-sized cooling tower groups has an adverse effect on large-sized cooling towers and can significantly increase the magnitude of local wind load.The shielding effect of large-sized cooling towers can reduce the overall wind load of small-sized cooling towers.The research conclusions can provide the basis of wind load value design for wind resistance design of such large cooling tower addition projects. 展开更多
关键词 cooling tower wind tunnel test wind-induced interference effect mechanism of action numerical simulation
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空间介质充放电研究现状及展望 被引量:12
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作者 李盛涛 李国倡 《科学通报》 EI CAS CSCD 北大核心 2017年第10期990-1003,共14页
空间环境与航天器介质材料相互作用引起的介质充放电现象是威胁航天器安全运行的重要因素之一.尤其是随着航天器工作电压的提高,该问题尤为突出,严重制约了高电压、大功率航天器的发展.本文综述了国内外空间介质充放电领域的研究现状、... 空间环境与航天器介质材料相互作用引起的介质充放电现象是威胁航天器安全运行的重要因素之一.尤其是随着航天器工作电压的提高,该问题尤为突出,严重制约了高电压、大功率航天器的发展.本文综述了国内外空间介质充放电领域的研究现状、存在的问题及未来发展.首先,介绍了空间介质充放电现象及其危害,当前我国航天器发展对空间介质的工程需求;分析了空间介质充放电发展历程及新时期深空探测、国际空间站的发展对空间介质的新要求和挑战.其次,从介质充放电机理、放电抑制措施、数值计算和计算机仿真等方面,总结了介质表面充放电和介质深层充放电的研究现状和存在问题.再次,介绍了空间介质充放电试验与材料特性的研究热点问题.包括:电子辐射下表面电位衰减与材料特性;电子辐射下介质内部空间电荷原位测量与材料特性;电子辐射下介质真空沿面闪络特性.最后,结合当前研究中存在的问题,展望了空间介质带电领域亟需解决的科学问题. 展开更多
关键词 空间环境 介质充放电效应 机理分析与数值仿真 介质充放电试验
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