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Microstructures and mechanical behaviors of CVI-based C/C composites containing h-BN powdered additives

Journal of Materials Science & Technology 2019年第12期35卷 2824-2831页

作者： Peng Xiao Zhichao Li zeyan liu Zhuan Li Bengu Zhang Jinwei Li Yang Li National Key Laboratory of Science and Technology for National Defence on High-strength Structural Materials Central South UniversityChangsha 410083China State Key Laboratory of Powder Metallurgy Central South UniversityChangsha410083China

Hexagonal boron nitride(h-BN) powders were introduced into carbon fiber preform by powder addition and subsequent combined with chemical vapor infiltration(CVI) for densification to prepare carbon fiber reinforced/carbon and boron nitride dual matrix composites(C/C-BN). Microstructures and mechanical properties of C/C composites with three different volume contents of h-BN powders were investigated in comparison to pure C/C composites. Results indicated that the introduction of h-BN powders into C/C composites significantly reduced the size of Py C and the anisotropy of thermal contraction in matrix,leading to a gradual disappearance of ring defects as the h-BN content increased. In addition, an enhanced interfacial bonding between fiber and matrix obtained due to higher-textured Py C and rougher fiber surface. Thereby, the flexural strengths and modulus of as-prepared composites decreased firstly and then increased, while the impact toughness presented a decreasing tendency as the content of BN powders increased. Furthermore, with the increasing of h-BN content, anisotropies of compressive properties were weakened, and the compressive strength of C/C-BN composites were always higher than that of pure C/C composit. However, when C/C composites modified by 13.5 vol% content of h-BN, excessive loose BN aggregates appeared in C/C-BN composites, leading to a relatively slight reduction of compressive strength.

关键词： C/C composites h-BN Pyrolytic carbon Interfacial bonding Mechanical properties

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Improving hydrogen evolution reaction efficiency through lattice tuning

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Nano Research 2024年第7期17卷 5907-5913页

作者： Zipeng Zhao Haotian liu Wenpei Gao Praveen Kolla Wang Xue zeyan liu Jinghua Guo Sanjeev Mukerjee Xiaoqing Pan Qingying Jia Xiangfeng Duan Yu Huang Department of Materials Science and Engineering University of CaliforniaLos AngelesCalifornia 90095USA Department of Chemical Engineering and Materials Science University of CaliforniaIrvineCalifornia 92697USA Materials Science and Engineering North Carolina State UniversityRaleighNorth Carolina 27695USA Department of Chemistry and Chemical Biology Northeastern UniversityBostonMassachusetts 02115USA Department of Chemistry and Biochemistry University of CaliforniaLos AngelesCalifornia 90095USA Advanced Light Source Lawrence Berkeley National LaboratoryBerkeleyCalifornia 94720USA Department of Chemistry and Biochemistry University of CaliforniaSanta CruzCalifornia 95064USA Department of Physics and Astronomy University of CaliforniaIrvineCalifornia 92697USA California Nanosystems Institute University of CaliforniaLos AngelesCalifornia 90095USA

The intermittent nature of renewable energy sources sets a requirement for efficient energy storage to mitigate the conflict between energy supply and *** is a promising choice for energy storage due to its high energy ***,the conversion of electrical energy to chemical energy stored in hydrogen through water electrolysis suffers from low efficiency,and the electricity cost dominates the total cost of hydrogen ***,we report the study of improving the hydrogen evolution reaction activity of Pt-based catalysts by building a nanoscale surface NiO and Pt interface,further optimizing the performance via tuning the lattice parameter of the core of nanoparticles,which can be achieved by varying the dealloying annealing *** optimized PtCuNi-O/C and PtNi-O/C catalysts are demonstrated to be one of the best catalysts,with a mass activity(MA)of 9.1 and 8.7 mA/μgPt,which is 9.9-fold and 9.5-fold of that of Pt/C,respectively.

关键词： lattice tuning Pt-based catalyst hydrogen evolution reaction electrocatalysis

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Effects of Heat Exchange Tube Structural Parameters on Performance of Vehicle Radiator

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Journal of Power and Energy Engineering 2020年第9期8卷 1-7页

作者： zeyan liu Xilei Kong Xiaobiao Han Hui liu Quanzhen Wang Zhenling Wang School of Transportation and Vehicle Engineering Shandong University of Technology Zibo China

In order to improve the performance of vehicle radiators, a two-dimensional heat transfer steady-state model of the radiator was set up. The influence of the structural parameters (axial ratio) of the heat exchange tube on the windward side on the heat transfer performance of the radiator was studied. With the increase of the axial ratio of the heat exchange tube on the windward side, the heat exchange capacity of the heat exchange tube surface slightly decreases. The heat exchange area increases significantly, which increases the total heat exchange of the radiator and improves the heat transfer performance of the radiator. When the axial ratio increases from 1.0 to 2.0, the average surface heat transfer capacity decreases from 5664.16 W/m2 to 5623.57 W/m2.

关键词： Vehicle Radiator Heat Transfer Performance Heat Exchange Tube Structure Parameters Axial Ratio

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Design of Fibonacci Sequence RFID Antenna Using Differential Evolution

Design of Fibonacci Sequence RFID Antenna Using Differential...

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第37届中国控制会议

作者： Li Peng Hai Zhang zeyan liu Hui Wang Huasheng Zhu Nanchang University Nanchang University Library School of Information Engineering Nanchang Institute of Technology Jiangxi Province Key Laboratory of Water Information Cooperative Sensing and Intelligent Processing Nanchang Institute of Technology School of Mathematics and Statistics Wuhan University

Differential evolution（DE） is an excellent global optimizer, which has been used to optimize various engineering problems. In recent years, the radio frequency identification technology（RFID） has been applied to many fields. However, it is not an easy task to design an efficient RFID antenna. The antenna structure is usually complex and it is difficult to find a suitable parameter set. In this paper, we try to use DE to design a RFID antenna with Fibonacci sequence quasi Yagi structure. Simulation results show that DE can successfully design the antenna. The obtained antenna size is 30 mm × 20 mm. Its simulation center frequency is 60 GHz and the center frequency gain approximates 8 dB. In the frequency band 59.5-60.5 GHz, the frequency echo loss is less than-10 dB and the minimum value is-111 dB.

关键词： Differential Evolution(DE) RFID Antenna Design Fibonacci Sequence Optimization

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1D PtCo nanowires as catalysts for PEMFCs with low Pt loading

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Science China Materials 2022年第3期65卷 704-711页

作者： Jin Huang Bosi Peng Thomas Stracensky zeyan liu Ao Zhang Mingjie Xu Yang liu Zipeng Zhao Xiangfeng Duan Qingying Jia Yu Huang Department of Materials Science and Engineering University of CaliforniaLos AngelesCA 90095USA Department of Chemistry and Biochemistry University of CaliforniaLos AngelesCA 90095USA Department of Chemistry and Chemical Biology Northeastern UniversityBostonMA 02115USA Irvine Materials Research Institute University of CaliforniaIrvineCA 92697USA Department of Materials Science University of CaliforniaIrvineCA 92697USA California NanoSystems Institute University of CaliforniaLos AngelesCA 90095USA

The high cost of platinum(Pt)-group metal(PGM)-based catalysts used in proton-exchange membrane fuel cells(PEMFCs)poses a critical roadblock to their widespread *** using low PGM loading PEMFCs can largely address this challenge,high current density performance will be severely compromised *** overcome this dilemma,we report the development of ultrathin platinum-cobalt nanowires(PtCoNWs)as the cathode catalysts for ultralow Pt loading and high-performance membrane electrode assembly(MEA).The Pt Co NWs delivered a record-high mass activity(MA)of 1.06±0.14 A mg_(Pt)^(-1) of Pt-alloy catalysts towards oxygen reduction reaction(ORR)in MEA,yielding an impressive total Pt utilization of 5.14 W_(rate)mg_(Pt)^(-1).The PtCoNWs retained a respectable endof-life MA of 0.45 Amg_(Pt)^(-1) after the 30,000 cycles square-wave accelerated stability test,which is still above the Department of Energy 2020 beginning-of-life target for ***-situ Xray absorption spectroscopy studies suggest that the high degree of alloying in the Pt Co NWs stabilizes the ultrathin structure and may contribute to the high ORR activity and power density performance in PEMFC.

关键词： ultralow loading PtCo nanowires high mass activity high Pt utilization fuel cell

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基于直接驱动和自增力技术的AMT换挡系统

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农业机械学报 2014年第9期45卷 1-7页

作者：葛文庆李波赵彦峻刘泽砚山东理工大学交通与车辆工程学院淄博255049 山东理工大学机械工程学院淄博255049

为进一步提高电控机械式自动变速器(AMT)的换挡品质和系统鲁棒性,提出一种应用直驱自增力换挡系统的AMT方案。设计了直接驱动装置的结构并对其性能进行测试,针对直接驱动技术存在的问题,研究一种具有自增力和提高换挡系统鲁棒性功能的... 详细信息

为进一步提高电控机械式自动变速器(AMT)的换挡品质和系统鲁棒性,提出一种应用直驱自增力换挡系统的AMT方案。设计了直接驱动装置的结构并对其性能进行测试,针对直接驱动技术存在的问题,研究一种具有自增力和提高换挡系统鲁棒性功能的增力式同步器,参考实车的相关参数,研制了直驱自增力换挡系统的原理性样机,完成了技术方案可行性与功能性的试验研究。结果表明,追求的换挡品质相同时,直驱自增力换挡系统同步阶段需要驱动装置提供的最大瞬时驱动力较小,降低了换挡过程中的能量损耗;当增力斜面角θ=116°时,增力式同步器的力放大系数nF约为1.54,实现了换挡系统放大驱动装置输出力和提高换挡系统鲁棒性的功能,为缩小驱动装置体积和降低换挡控制系统设计难度奠定了良好的技术基础。

关键词：电控机械式自动变速器直接驱动技术增力式同步器换挡能耗

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胃息肉的中医辨证治疗

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河南中医 2006年第10期26卷 82-83页

作者：刘泽延陆丰市碣石镇刘泽延个体诊所广东陆丰516545

胃息肉是指胃粘膜上皮和/或间质成分增生所引起的息肉状病变。中医药对本病的报道很少。胃息肉归属于中医学的“胃脘痛”,“痞满”;若有出血则属“血证”范畴。然《灵枢·水胀篇》曾提及:“寒气客于肠外,与卫气相搏,气不得荣,因有所系,... 详细信息

胃息肉是指胃粘膜上皮和/或间质成分增生所引起的息肉状病变。中医药对本病的报道很少。胃息肉归属于中医学的“胃脘痛”,“痞满”;若有出血则属“血证”范畴。然《灵枢·水胀篇》曾提及:“寒气客于肠外,与卫气相搏,气不得荣,因有所系,癖而内着,恶气乃起,息肉乃生。”认为胃肠道息肉的病因病机,为寒客肠胃,气血壅塞。然而据笔者临床所得,本病应以气滞痰阻、痰热郁结、痰瘀互结、脾胃虚寒四型进行辨证为宜,临床上以痰热郁结,气滞血瘀较为多见。笔者在临床上运用中医辨证治疗本病,获得了较好的疗效,现将体会简介如下。[第一段]

关键词：胃息肉气滞痰阻证痰热郁结证痰瘀互结证脾胃虚寒证

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基于PLC和物联网技术的砂石骨料生产线研究

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四川水力发电 2020年第6期39卷 56-59页

作者：刘泽艳中国水利水电第七工程局有限公司四川成都610213

阐述了如何集成运用PLC和物联网技术实现砂石骨料生产线主要设备运行参数的采集、传输与处理,并从实际需求出发进行系统架构设计和软硬件平台的搭建,以实现对整个砂石骨料生产线进行实时控制和在线监测、最终达到优化系统产能、提高产... 详细信息

阐述了如何集成运用PLC和物联网技术实现砂石骨料生产线主要设备运行参数的采集、传输与处理,并从实际需求出发进行系统架构设计和软硬件平台的搭建,以实现对整个砂石骨料生产线进行实时控制和在线监测、最终达到优化系统产能、提高产品质量的目的。

关键词： PLC 物联网砂石骨料生产线设备参数乌东德水电站

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抑郁焦虑导致心肌梗死的危险因素

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黑龙江科学 2024年第6期15卷 93-95,99页

作者：刘泽岩安徽医科大学第二附属医院合肥230601

探讨抑郁和焦虑导致心肌梗死的危险因素,为合理预防心肌梗死提供科学依据。选取来我院住院治疗的300名心肌梗塞患者,采用住院焦虑和抑郁量表(HADS)来确定心肌梗死患者出院时的焦虑和抑郁情况,观察患者的性别、年龄、吸烟情况、入院时的... 详细信息

探讨抑郁和焦虑导致心肌梗死的危险因素,为合理预防心肌梗死提供科学依据。选取来我院住院治疗的300名心肌梗塞患者,采用住院焦虑和抑郁量表(HADS)来确定心肌梗死患者出院时的焦虑和抑郁情况,观察患者的性别、年龄、吸烟情况、入院时的生命体征和胸部疼痛严重程度、糖尿病、高血压、左心室射血分数(LVEF)以及心室颤动、持续性室性心动过速、心源性休克等并发症。结果显示,抑郁评分高的患者(8~21分)比抑郁评分低的患者(0~7分)更容易出现并发症(χ^(2)=34.15,P<0.001),男性低于女性,且ST段抬高型的心肌梗死更为常见,说明抑郁和焦虑是易感人群发生心肌梗死的危险因素,故预防、治疗抑郁及焦虑可减少心肌梗死的发生。

关键词：抑郁焦虑心肌梗塞危险因素

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聚偏氟乙烯膜亲水改性及其乳液分离与重金属吸附应用

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化工学报 2021年第S01期72卷 421-429页

作者：吴中杰刘则艳谢连科崔美黄仁亮国网山东省电力公司电力科学研究院山东济南250002 天津大学海洋科学与技术学院天津300072

聚偏氟乙烯(PVDF)膜因其优异的化学和力学稳定性而被广泛应用于水处理领域,但PVDF膜本身的疏水性,容易使其在处理含油废水的过程中被油滴污染,造成膜孔堵塞。以PVDF微滤膜为基底,通过单宁酸(TA)和聚乙烯亚胺(PEI)共沉积形成了TA/PEI黏附... 详细信息

聚偏氟乙烯(PVDF)膜因其优异的化学和力学稳定性而被广泛应用于水处理领域,但PVDF膜本身的疏水性,容易使其在处理含油废水的过程中被油滴污染,造成膜孔堵塞。以PVDF微滤膜为基底,通过单宁酸(TA)和聚乙烯亚胺(PEI)共沉积形成了TA/PEI黏附层,经戊二醛共价交联和接枝半胱氨酸(Cys),制备了一种PVDF改性膜(PVDF@TA/PEI-Cys)。改性后的PVDF膜具有良好的亲水性和水下超疏油性,水接触角和水下油接触角分别为22.2°和150.2°。在0.09 MPa下,PVDF@TA/PEI-Cys膜的纯水通量达6328 L/(m^(2)·h),水包油型乳液分离效率高达99.9%。此外,该改性膜还可同时吸附水中的汞离子,最大吸附量为24.7 mg/g。

关键词：膜分离重金属吸附乳液亲水性

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