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低温热致相分离法制备PVDF-CTFE多孔膜的研究

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膜科学与技术 2024年第2期44卷 55-63页

作者：林帅吕晓龙张绍哲谷杰任凯天津工业大学省部共建分离膜与膜过程国家重点实验室材料科学与工程学院生物化工研究所天津300387 膜材料与膜应用国家重点实验室天津膜天膜科技股份有限公司天津300457

利用低温热致相分离法制备了PVDF-CTFE多孔膜,重点考察了甘油含量和凝固浴温度对成膜机理和性能的影响.结果表明,甘油有促进热致相分离(TIPS)和非溶剂致相分离(NIPS)的双重作用.甘油含量的提高,一方面作为非溶剂使铸膜液浊点温度与凝固... 详细信息

利用低温热致相分离法制备了PVDF-CTFE多孔膜,重点考察了甘油含量和凝固浴温度对成膜机理和性能的影响.结果表明,甘油有促进热致相分离(TIPS)和非溶剂致相分离(NIPS)的双重作用.甘油含量的提高,一方面作为非溶剂使铸膜液浊点温度与凝固浴温度的温差变大,加强了TIPS效应,使膜结构呈TIPS效应为主的双连续结构,避免了NIPS效应所致典型的指状孔结构;另一方面作为NIPS的致孔剂,会加强NIPS效应,促使发生双扩散,生成更多孔结构,二者竞争共同作用.最终甘油含量的提高使TIPS效应占主导,NIPS所致的皮层结构变薄,膜断面结构从致密堆积状向多孔蜂窝状结构转变,提高了膜的通透性.当甘油添加量为7.5%(质量分数)时,PVDF-CTFE中空纤维多孔膜综合性能最佳,拉伸断裂强度达2.6 MPa,纯水通量达860 L/(m^(2)·h·MPa).凝固浴温度的提高,减少了铸膜液浊点温度与凝固浴的温差,减弱了TIPS效应,加强了NIPS效应的传质过程,使膜结构从蜂窝状结构向指状孔结构转变,皮层厚度增加,导致膜孔隙率和纯水通量提高,力学性能下降.当凝固浴温度为80℃时,PVDF-CTFE平板多孔膜的纯水通量为1510 L/(m^(2)·h·MPa),拉伸断裂强度为2.1 MPa.

关键词：聚偏氟乙烯-三氟氯乙烯低温热致相分离成膜机理多孔膜凝固浴温度

Fault Diagnosis of Proton Exchange Membrane Fuel Cell Based on Nonlinear Impedance Spectrum

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Automotive Innovation 2023年第4期6卷 597-610页

作者： Hao Yuan shaozhe zhang Xuezhe Wei Haifeng Dai School of Automotive Studies Tongji UniversityShanghaiChina

Electrochemical impedance spectroscopy(EIS)contributes to developing the fault diagnosis tools for fuel cells,which is of great significance in improving service *** conventional impedance measurement techniques are limited to linear responses,failing to capture high-order harmonic ***,nonlinear electrochemical impedance analysis incorporates additional nonlinear information,enabling the resolution of such *** study proposes a novel multi-stage fault diagnosis method based on the nonlinear electrochemical impedance spectrum(NEIS).First,the impact of alternating current excitation amplitude on NEIS is ***,a series of experiments are conducted to obtain NEIS data under various fault conditions,encompassing recoverable faults like flooding,drying,starvation,and their mixed faults,spanning different degrees of fault *** on these experiments,both EIS and NEIS datasets are established,and principal component analysis is utilized to extract the main features,thereby reducing the dimensionality of the original ***,a fault diagnosis model is constructed with the support vector machine(SVM)and random forest algorithms,with model hyperparameters optimized by a hybrid genetic particle swarm optimization(HGAPSO)*** results show that the diagnostic accuracy of NEIS is higher than that of traditional EIS,with the HGAPSO-SVM model achieving a 100%accurate diagnosis under the NEIS dateset and self-defined fault labels.

关键词： Fuel cell Nonlinear electrochemical impedance spectrum Fault diagnosis

Realisation of the reconfigurable pulsed high magnetic field facility and its scientific application at Wuhan National Pulsed High Magnetic Field Centre

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High Voltage 2023年第5期8卷 898-906页

作者： Jianfeng Xie shaozhe zhang Jiangtao Shi Junfeng Wang Liang Li Xiaotao Han Wuhan National High Magnetic Field Center Huazhong University of Science and TechnologyWuhanChina State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and TechnologyWuhanChina

To generate arbitrary shape magnetic field waveforms for advanced scientific research,a reconfigurable pulsed high magnetic field facility(PHMFF)was developed at Wuhan National Pulsed High Magnetic Field Centre(WHMFC).First,the basic elements of PHMFF are introduced,and a ternary physical model composed of energy storage unit,magnet,transmission circuits and other auxiliary units is summarised to describe various magnetic field ***,in order to realise the reconfiguration of magnetic field systems based on detailed elements,the control system with the ability of dynamic construction and control sequence reconfiguration is *** this basis,the PHMFF has been realised and various magnetic field systems are constructed to produce arbitrary shape magnetic field waveforms,such as half‐sine,ultra‐high,flat‐top and repetitive field pulses,which not only enhances the capability and efficiency of PHMFF,but also makes more scientific research possible in pulsed magnetic *** far,a peak magnetic field of 94.8 T,a flat‐top magnetic field of 64 T/10 ms and a repetitive magnetic field waveform of 20 T/60 Hz have been achieved,and some experiments and studies on the physical properties of materials have been carried out at WHMFC.

关键词： magnetic field pulsed

基于双电容器耦合和线性补偿的高稳定度平顶脉冲强磁场调控系统分析与设计

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电工技术学报 2024年第2期39卷 303-312页

作者：张绍哲魏文琦樊俊显谢剑峰韩小涛华中科技大学国家脉冲强磁场科学中心武汉430074 强电磁技术全国重点实验室(华中科技大学电气与电子工程学院) 武汉430074

平顶脉冲磁场具备脉冲磁场强度高和稳态磁场稳定度高的双重优势,是现代物理科学研究的重要工具。为满足脉冲场核磁共振、I-V测量等科学实验对平顶脉冲磁场高稳定度的需求,该文提出基于双电容器回路耦合放电和线性补偿的平顶磁场调控方... 详细信息

平顶脉冲磁场具备脉冲磁场强度高和稳态磁场稳定度高的双重优势,是现代物理科学研究的重要工具。为满足脉冲场核磁共振、I-V测量等科学实验对平顶脉冲磁场高稳定度的需求,该文提出基于双电容器回路耦合放电和线性补偿的平顶磁场调控方案。为此,理论分析双电容器回路耦合放电过程,建立配置主/辅回路电容电压和放电时序的优化方法,基于IGBT有源区的流控特性,设计线性调节补偿回路和前馈反馈相结合的控制器,研制与主磁体解耦的1 T补偿磁体,对双电容器回路耦合放电产生的背景磁场进行高精度调控,最终实现了强度为45.2 T、持续时间为8 ms以及稳定度为0.02%的平顶脉冲磁场,满足相关固态核磁共振等科学实验需求。

关键词：平顶脉冲磁场双电容器耦合磁场补偿线性调控高稳定度

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基于语谱图滤波去噪的语音增强技术研究

电声技术 2024年第2期48卷 45-47页

作者：白燕燕白帆张少哲韩宗祥西安工商学院信息与工程学院陕西西安710200

在日常生活通信中,语音起着至关重要的作用。然而,环境噪声污染问题严重影响着语音处理系统的性能。为有效应对噪声干扰问题,可以采用语音增强技术。语谱图作为一种融合了时域和频域优势的工具,能够清晰地揭示语音频谱随时间的变化情况... 详细信息

在日常生活通信中,语音起着至关重要的作用。然而,环境噪声污染问题严重影响着语音处理系统的性能。为有效应对噪声干扰问题,可以采用语音增强技术。语谱图作为一种融合了时域和频域优势的工具,能够清晰地揭示语音频谱随时间的变化情况。因此,文章基于语谱图进行滤波去噪,旨在提升语音的质量,使其更加清晰可辨。

关键词：语音增强语谱图时域频域滤波

Fault Diagnosis of Proton Exchange Membrane Fuel Cell Based on Nonlinear Impedance Spectrum

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Fault Diagnosis of Proton Exchange Membrane Fuel Cell Based ...

2022中国汽车工程学会年会暨展览会

作者： Yuan Hao zhang shaozhe Wei Xuezhe Dai Haifeng School of Automotive Studies Tongji University

Electrochemical impedance spectroscopy(EIS) contributes to developing the fault diagnosis tool for fuel cells,which is of great significance to improve their service *** conventional impedance measurement is limited to the linear response,while nonlinear electrochemical impedance can resolve higher-order frequency response,taking additional nonlinear information into *** this manuscript,a novel multi-stage fault diagnosis method is proposed based on the nonlinear electrochemical impedance spectrum(NEIS).Firstly,the effect of alternating current excitation amplitude on the NES are *** experiments of NEIS under various fault conditions are conducted,where typical recoverable faults,such as flooding,drying,starvation,and their mixed faults,are included and meanwhile covering different fault *** on this,EIS and NEIS data sets are established accordingly,and the principal component analysis is utilized to extract the main features to reduce the original data ***,the fault model is constructed with the support vector machine(SVM) and random forest(RF).The results show that the diagnostic accuracy can reach97.78% by both SVM and RF based on the NEIS data set,presenting higher accuracy than traditional EIS-based ***,the RF holds higher computing efficiency,which is more suitable for vehicular applications.

关键词：

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首席执行官学术经历与企业绿色技术创新

科技管理研究 2022年第3期42卷 135-144页

作者：张少喆石浩悦华南理工大学工商管理学院广东广州510640

基于高层梯队理论,研究利用2008—2019年中国A股上市公司绿色专利数据,考察首席执行官(CEO)学术经历与企业绿色创新之间的关系。研究发现,CEO学术经历能够在一定程度上促进企业绿色技术创新,结果在一系列的检验后依旧稳健。进一步研究发... 详细信息

基于高层梯队理论,研究利用2008—2019年中国A股上市公司绿色专利数据,考察首席执行官(CEO)学术经历与企业绿色创新之间的关系。研究发现,CEO学术经历能够在一定程度上促进企业绿色技术创新,结果在一系列的检验后依旧稳健。进一步研究发现,提高研发投入水平与缓解融资约束是CEO学术经历提升企业绿色技术创新水平的重要作用机制;且国有企业中CEO学术经历对绿色技术创新的促进作用更强。主要管理启示为,学术经历可以作为一种内部的治理机制,在外部治理不够完备的情况下,加强高管团队的建设可以作为促进发展绿色经济一个可能的思路。

关键词： CEO学术经历绿色技术创新高层梯队理论

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质子交换膜燃料电池电化学阻抗谱敏感性研究

机械工程学报 2021年第14期57卷 40-51页

作者：张少哲戴海峰袁浩明平文魏学哲同济大学汽车学院上海201804 同济大学新能源工程中心上海201804

电化学阻抗谱能被用来表征燃料电池内部状态和电化学行为信息,通过构建合适的等效电路模型拟合电化学阻抗谱,可辨识和量化燃料电池内部不同的极化过程及状态。针对质子交换膜燃料电池,系统研究电流密度、工作温度、压力、阴/阳极进气过... 详细信息

电化学阻抗谱能被用来表征燃料电池内部状态和电化学行为信息,通过构建合适的等效电路模型拟合电化学阻抗谱,可辨识和量化燃料电池内部不同的极化过程及状态。针对质子交换膜燃料电池,系统研究电流密度、工作温度、压力、阴/阳极进气过量系数和阴/阳极进气湿度7种外部工作条件对燃料电池电化学阻抗谱的影响。基于等效电路法,对阻抗谱各频段阻抗的变化及其对工作条件的敏感性进行分析和讨论。研究表明,燃料电池损耗在低、中、高电流密度下分别由活化损耗、欧姆损耗和传质损耗主导;在固定电流密度下,电池温度、压力、阴极进气过量系数和阴极进气湿度对阻抗谱影响较大;欧姆阻抗是对阴阳极进气湿度变化最敏感;阳极活化阻抗仅对阳极进气过量系数和阳极进气湿度较为敏感;阴极活化阻抗是对阴极过量系数最敏感,其次是温度和压力;传质阻抗对阴极过量系数敏感程度最大,压力和温度次之;为燃料电池工作条件优化和内部状态的监测与诊断研究提供指导。

关键词：质子交换膜燃料电池电化学阻抗谱等效电路模型工作条件敏感性分析

Magnetic resonance imaging characteristics of patients with neuropsychiatric systemic lupus erythematosus

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Chinese Medical Journal 2024年第3期137卷 373-375页

作者： Yanli Huang Shuoqi zhang shaozhe Cai Bingxia Ming Rongfen Gao Ziwei Hu Lingli Dong Department of Rheumatology and Immunology Tongji Hospital of Tongji Medical College of Huazhong University of Science and TechnologyWuhanHubei 430030China Department of Rheumatology and Immunology Yueyang Central HospitalYueyangHunan 414000China Department of Radiology Tongji HospitalTongji Medical CollegeHuazhong University of Science and TechnologyWuhanHubei 430030China

To the Editor:Neuropsychiatric systemic lupus erythematosus(NPSLE)is a group of serious complications of systemic lupus erythematosus(SLE)with poor prognosis and high mortality.^([1])Therefore,identifying risk factors for NPSLE is particularly crucial for the improvement of the outcomes of *** resonance imaging(MRI)is currently the imaging test of choice for diagnosing patients with ***,almost half of the patients with NPSLE show no abnormalities on conventional MRI.^([2])Therefore,the correlation between neuropsychiatric symptoms,which refer to multiple neuropsychiatric manifestations directly related to SLE,and MRI findings should be urgently *** this study,we investigated the clinical features,outcomes,and prognostic factors of NPSLE and analyzed the correlation of neuropsychiatric symptoms with MRI features.

关键词： psychiatric patients erythematosus