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基于BP神经网络及烟尘沉积特征的单隔间内起火点预测

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消防科学与技术 2024年第1期43卷 56-64页

作者：牛甜辉耿佃桥苑轶董辉东北大学材料电磁过程研究教育部重点实验室辽宁沈阳110819 东北大学冶金学院辽宁沈阳110819

为帮助火灾调查人员更准确、高效地判定起火点,提出了一种基于BP神经网络的起火点预测模型。通过对单隔间火灾烟尘沉积进行数值模拟,构建了59种不同起火点场景下壁面烟尘沉积数据库,并分析了典型起火点场景下的壁面烟尘沉积特征,发现起... 详细信息

为帮助火灾调查人员更准确、高效地判定起火点,提出了一种基于BP神经网络的起火点预测模型。通过对单隔间火灾烟尘沉积进行数值模拟,构建了59种不同起火点场景下壁面烟尘沉积数据库,并分析了典型起火点场景下的壁面烟尘沉积特征,发现起火点位置与壁面沉积总量及最大浓度平均值之间具有强关联性。选取上述两个参数作为输入,起火点位置作为输出进行神经网络训练,并利用新数据进行预测。结果表明起火点位置预测值的最大绝对误差为0.65 m,最小绝对误差为0.03 m,平均绝对误差为0.37 m,说明本文提出的模型能以较高精度预测起火点位置,是一种较好的火灾调查替代方法。

关键词： BP神经网络烟尘沉积数值模拟单隔间起火点

Effect of electromagnetic swirling flow in slide-gate SEN on flow field in square billet continuous casting mold

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Acta Metallurgica Sinica(English Letters) 2012年第5期25卷 347-356页

作者： dianqiao geng Hong LEI Jicheng HE Haitao LIU Key Laboratory of National Education Ministry for Electromagnetic Processing of Materials North- eastern University Shenyang 110819 China State Key Laboratory of Rolling 8z Automation Northeastern University Shenyang 110819 ChinaManuscript received 15 March 2012 in revised form 16 May 2012

In order to weaken the bias flow in the submerged entry nozzle （SEN） with slide- gate, the rotating magnetic field was imposed. The numerical method was employed to investigate the effect of rotating magnetic field on the flow field in the SEN and the mold under different slide-gate opening ratios. Numerical results showed that when the slide-gate opening ratio is smaller than 100%, the flow field in the SEN and the mold become asymmetry and there is an obvious circulation under the slide- gate in the SEN. With increasing exciting current, the divergent angle of liquid steel at the SEN outlet increases, the impact depth of liquid steel in the mold decreases. With increasing slide-gate opening ratio, the impact depth of liquid steel in the mold increases and the required exciting current to weaken the bias flow should increase.

关键词： Square billet Electromagnetic swirling flow Slide-gate SEN Continuous casting Bias flow

固液密度比对PMMA/HDPE悬浮液粘度的影响

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材料导报 2021年第4期35卷 4181-4185页

作者：梁捷耿佃桥张群东北大学材料电磁过程研究教育部重点实验室沈阳110819 东北大学冶金学院沈阳110819

固液密度比是影响悬浮液粘度的重要参数,准确预测悬浮液的粘度对材料分选具有重要意义。本工作基于实验方法,采用不同密度的PM⁃MA/HDPE颗粒组成两种悬浮液,研究了固液密度比对悬浮液粘度的影响。结果表明:在相同固体体积分数下,悬浮液... 详细信息

固液密度比是影响悬浮液粘度的重要参数,准确预测悬浮液的粘度对材料分选具有重要意义。本工作基于实验方法,采用不同密度的PM⁃MA/HDPE颗粒组成两种悬浮液,研究了固液密度比对悬浮液粘度的影响。结果表明:在相同固体体积分数下,悬浮液的粘度随固液密度比的增加而降低;在不同固液密度比下,低固体体积分数下悬浮液的粘度增长速度低于高固体体积分数下的粘度增长速度;颗粒粒径越小,悬浮液的粘度随固液密度比的增加降低得越快。在实验条件范围内,对PMMA/HDPE两种悬浮液分别采用Batchelor模型和Leighton模型,建立了相应的修正模型,并验证修正模型的准确性。

关键词：悬浮液固液密度比 Batchelor模型 Leighton模型粘度

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闭孔泡沫铝有效热导率模型及传热模拟研究

稀有金属材料与工程 2020年第5期49卷 1637-1642页

作者：李家卉耿佃桥张润雨霍小臭王平东北大学材料电磁过程研究教育部重点实验室辽宁沈阳110819

有效热导率是表征闭孔泡沫铝热性能的重要参数,准确预测闭孔泡沫铝的有效热导率具有重要意义。本研究基于已有的闭孔泡沫铝有效热导率模型,提出了一个改进模型,并采用数值模拟方法针对闭孔泡沫铝的非稳态传热过程进行了分析,基于温度场... 详细信息

有效热导率是表征闭孔泡沫铝热性能的重要参数,准确预测闭孔泡沫铝的有效热导率具有重要意义。本研究基于已有的闭孔泡沫铝有效热导率模型,提出了一个改进模型,并采用数值模拟方法针对闭孔泡沫铝的非稳态传热过程进行了分析,基于温度场分布获得了有效热导率。结果表明与Lu模型相比,改进模型的预测精度更高;与文献中3个理论模型相比,改进模型具有更好的适用性及预测精度;当采用数值模拟方法计算有效热导率时,沿传热方向的胞孔数对有效热导率的预测精度影响较大;在保证泡沫铝胞孔数足够的条件下,数值模拟结果的精度最高;从成本及精度两方面考虑,改进模型有更好的适用性。

关键词：闭孔泡沫铝有效热导率理论模型数值模拟

R32在倾斜微通道中流动沸腾换热的数值模拟

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低温与超导 2020年第10期48卷 62-67,78页

作者：张勇郝奇耿佃桥东北大学材料电磁过程研究教育部重点实验室沈阳110819 东北大学冶金学院沈阳110819

利用VOF(Volume of Fluid Model)多相流模型及相变模型,对不同倾斜角度下R32在内径为1 mm管道中的流动沸腾换热过程进行了二维非稳态数值模拟,模拟工况为:工质饱和温度为15℃,质流密度为100、300 kg/(m^2·s),热流密度为50、80 kW/m^2... 详细信息

利用VOF(Volume of Fluid Model)多相流模型及相变模型,对不同倾斜角度下R32在内径为1 mm管道中的流动沸腾换热过程进行了二维非稳态数值模拟,模拟工况为:工质饱和温度为15℃,质流密度为100、300 kg/(m^2·s),热流密度为50、80 kW/m^2。结果表明,R32在流动沸腾过程中依次经过了泡状流、受限泡状流、弹状流、波状环状流、蒸干区和雾状流。随着管道倾斜角度的增加,大气泡出现的位置后移;在入口段,换热系数随着管道倾斜角度的增加而减小,在中间段和出口段,换热系数随倾斜角度的变化不明显;压降随着倾斜角度的增加而减小。

关键词： R32 倾斜角度微通道流动沸腾数值模拟气液两相流

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内螺纹管流动沸腾气泡行为及换热特性研究

低温与超导 2020年第5期48卷 59-65页

作者：郝奇李家晨耿佃桥东北大学材料电磁过程研究教育部重点实验室沈阳110819 东北大学冶金学院沈阳110819

为探究内螺纹管流动沸腾过程中的气泡行为及其对换热的影响机理,采用VOF模型(Volume of Fluid Model)及相变模型对工质在小尺寸水平内螺纹管中的流动沸腾过程进行二维非稳态数值模拟。获得了不同质量流速下工质在管道内的气相分布以及... 详细信息

为探究内螺纹管流动沸腾过程中的气泡行为及其对换热的影响机理,采用VOF模型(Volume of Fluid Model)及相变模型对工质在小尺寸水平内螺纹管中的流动沸腾过程进行二维非稳态数值模拟。获得了不同质量流速下工质在管道内的气相分布以及管壁不同位置处的温度、换热系数。分析了内螺纹管流动沸腾过程中的气泡行为特点以及不同气泡行为对换热性能的影响。研究表明:在内螺纹管中随着质量流速的增加,管内含气率降低,平均换热系数增大。管壁面上气泡的滑移、长大行为会削弱对流换热,而近壁面气泡的聚并行为会增强对流换热。

关键词：流动沸腾多相流 VOF模型气泡行为数值模拟

Mixed Dead-time Effect Suppression Strategy for Modular Multilevel Converters

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CSEE Journal of Power and Energy Systems 2024年第3期10卷 1075-1084页

作者： Zhi geng Minxiao Han School of Electrical and Electronic Engineering North China Electric Power UniversityBeijing 102206China IEEE

Dead time is necessary for the coupled power switches to prevent shoot-through,especially in the modular multilevel converters(MMCs)with a large number of power *** paper proposes a dead-time effect suppression strategy for MMCs with nearest level *** operational principles of MMCs are first *** to the operational features of MMCs,the method that removes a switching signal from the coupled switches and the reduced switching frequency voltage balancing algorithms(RSFVBAs)are mixed in the proposed *** the intervals that are furthest away from the zerocrossing points(ZCP)of arm currents,the single switching signal method can completely eliminate the dead-time effect(DTE).Alternatively,the DTE is suppressed by the RSFVBA in intervals that are close to the *** the combination of the two methods,the dependence of the DTE suppression method on currents is reduced and the influences of ZCP are also released without degrading the normal operation performance of ***,the output performance of MMCs is improved and the voltage stress on the arm inductor dramatically ***,the validation of the method is verified by the simulation results with the professional tool Matlab/Simulink.

关键词： Dead-time effect modular multilevel converters switching frequency voltage balancing algorithm

Investigation and measurement of old building response to the overlapped shield tunnel of multiple schemes in the sandy cobble stratum

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Underground Space 2024年第2期15卷 260-274页

作者： Xue Li Aopeng geng School of Geoscience and Technology Southwest Petroleum UniversityChengduSichuan 610500China China Railway Construction Bridge Engineering Bureau Group Co. Ltd.Tianjin 300300China

Ground movements due to tunneling are becoming increasingly critical as buildings are located around construction *** study proposes a new combined reinforcement method using a foundation grouting oblique pipe *** former improves the bearing capacity of the subsoil,and the latter blocks the transmission of soil deformation,which weakens the influence of construction during overlapped tunnel *** on this new method,a case study of the shield tunneling response to an old building in Line 6 of China’s Chengdu Metro is ***,three-dimensional numerical models without reinforcement,traditional foundation grouting reinforcement,and the new combined reinforcement schemes were *** numerical simulation performance was verified using a set of field instrumentation data,which demonstrated that the old building response to the overlapped tunnels was under control,and the maximum deformation,angular distortion,and principal tensile strain of the building were 5.25 mm,5.1010–6 rad/m,and 0.0081%,*** with the traditional reinforcement scheme,the deformation,angular distortion,and principal tensile strain in the combined reinforcement scheme were reduced by 54.78%,71.02%,and 70.22%,*** results have important implications for the design and construction of shield tunnels and their response to old buildings.

关键词： Overlapped tunnels Reinforcement schemes Under-crossing Old building Numerical simulation

Boosting electrocatalytic nitrate reduction to ammonia via Cu_(2)O/Cu(OH)_(2)heterostructures promoting electron transfer

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Nano Research 2024年第6期17卷 4898-4907页

作者： Jing geng Sihan Ji Anhui Province International Research Center on Advanced Building Materials School of Materials Science and Chemical EngineeringAnhui Jianzhu UniversityHefei 230601China Anhui Province Key Laboratory of Advanced Building Materials Anhui Jianzhu UniversityHefei 230601China School of Energy Materials and Chemical Engineering Hefei UniversityHefei 230601China

Electrocatalytic nitrate(NO_(3)^(−))reduction to ammonia(NH_(3))offers a viable approach for sustainable NH_(3)production and environmental ***(Cu)possesses a distinctive electronic structure,which can augment the reaction kinetics of NO_(3)^(−)and impede hydrogen evolution reaction(HER),rendering it a promising contender for the electrosynthesis of NH_(3)from NO_(3)^(−).Nevertheless,the role of Cu_(2)O in copper-based catalysts still requires further investigation for a more comprehensive ***,the Cu_(2)O/Cu(OH)_(2)heterostructures are successfully fabricated through liquid laser irradiation using CuO nanoparticles as a *** and theoretical researches reveal that Cu_(2)O/Cu(OH)_(2)heterostructure exhibits enhanced electrocatalytic performance for NO_(3)^(−)to NH_(3)because Cu(OH)_(2)promotes electron transfer and reduces the valence state of Cu active site in Cu_(2)***−0.6 V(*** hydrogen electrode(RHE)),the NH_(3)yield reaches its maximum at 1630.66±29.72μg·h^(−1)·mgcat^(−1),while the maximum of Faraday efficiency(FE)is 76.95%±5.51%.This study expands the technical scope of copper-based catalyst preparation and enhances the understanding of the electrocatalytic mechanism of NO_(3)^(−)to NH_(3).

关键词： Cu_(2)O/Cu(OH)_(2)heterostructures electron transfer ammonia synthesis electrocatalysts nitrate