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Application of cost-sensitive LSTM in water level prediction for nuclear reactor pressurizer
Zhang Jin,Wang Xiaolong,Zhao Cheng,Bai Wei,Shen Jun,Li Yang,Pan Zhisong,Duan Yexin 한국원자력학회 2020 Nuclear Engineering and Technology Vol.52 No.7
Applying an accurate parametric prediction model to identify abnormal or false pressurizer water levels (PWLs) is critical to the safe operation of marine pressurized water reactors (PWRs). Recently, deeplearning-based models have proved to be a powerful feature extractor to perform high-accuracy prediction. However, the effectiveness of models still suffers from two issues in PWL prediction: the correlations shifting over time between PWL and other feature parameters, and the example imbalance between fluctuation examples (minority) and stable examples (majority). To address these problems, we propose a cost-sensitive mechanism to facilitate the model to learn the feature representation of later examples and fluctuation examples. By weighting the standard mean square error loss with a costsensitive factor, we develop a Cost-Sensitive Long Short-Term Memory (CSLSTM) model to predict the PWL of PWRs. The overall performance of the CSLSTM is assessed by a variety of evaluation metrics with the experimental data collected from a marine PWR simulator. The comparisons with the Long ShortTerm Memory (LSTM) model and the Support Vector Regression (SVR) model demonstrate the effectiveness of the CSLSTM
Heat transfer of a sustainable personal garment cooling system
Yijie Zhang,Ziyi Guo,Tao Li,Yexin Lyu,FengYuan Zou 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.10
This paper provides examines sustainable personal cooling systems. The impact of micro-fan configuration and inflow airspeed was tested. First, three different types of test models-a garment with side seam micro-fans, scatter-fans, and bottom-fans, was used to analyze and compare the heat transfer characteristic. Second, a new index of convective heat transfer was used to evaluate the cooling performance of these models. Third, the selected model was calculated with three different inflow properties, and the performance of efficiency and energy saving was analyzed. The results show that the bottom-fans model yields the best performance both on efficiency and cooling effect. The evaluation of thermal environment shows that the defined indexes are reliable to reflect heat transfer characteristics in the air gap. The comparison study of different airspeeds shows that the inflow air velocity should be set at a suitable range due to the view of energy saving.
Local Joule heating targets catalyst surface for hydrocarbon combustion
Qian Xiong,Xingbao Zhu,Ri He,Xueyi Mei,Yexin Zhang,Zhicheng Zhong,Wei Zhao,Weiming Nie,Jian Zhang 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.117 No.-
Most industrial catalytic reactions are achieved by external heating and catalysts are entirely heated tooffer enough thermal energy to surface active sites. However, there is an inherent drawback that mostinput energy is dissipated into the bulk while minor is donated to the surface, leading to high energywaste. Here, we proposed a so-called local Joule heating method via passing an electric current throughpacked catalyst nanoparticles with a large contact resistance, which can generate sufficient heat to targetat the surface region. We selected hydrocarbon combustion, a common way to eliminate unburned pollutants,as a probe reaction and used the conductive antimony-doped tin oxide (ATO) as a model catalyst. Compared with traditional external heating, this method consumed one order lower energy input,reduced the macroscopically average temperature for same conversion by 100 C, improved the durabilitywith smaller activity loss within 100 h operation, and suppressed water poisoning effect by 60 %. Also, the combustion was sparked in seconds by pulsing electric current into the catalyst bed, allowing anapplication in prompt treatment of leaked hydrocarbons. The local Joule heating between contactednanoparticles, which could focus thermal energy on catalyst surface, is prospective to improve catalysisefficiency.