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Accelerated life-time test of MEA durability under vehicle operating conditions in PEM fuel cell

Tian TIAN, Jianjun TANG, Wei GUO, Mu PAN

《能源前沿(英文)》 2017年 第11卷 第3期   页码 326-333 doi: 10.1007/s11708-017-0489-z

摘要: In this paper, a novel accelerated test method was proposed to analyze the durability of MEA, considering the actual operation of the fuel cell vehicle. The proposed method includes 7 working conditions: open circuit voltage (OCV), idling, rated output, overload, idling-rated cycle, idling-overload cycle, and OCV-idling cycle. The experimental results indicate that the proposed method can effectively destroy the MEA in a short time (165 h). Moreover, the degradation mechanism of MEA was analyzed by measuring the polarization curve, CV, SEM and TEM. This paper may provide a new research direction for improving the durability of fuel cell.

关键词: polymer electrolyte membrane fuel cell     accelerated life-time test     load cycling test     durability    

Sustainability of steel structures: towards an integrated approach to life-time engineering design

Raffaele LANDOLFO, Lucrezia CASCINI, Francesco PORTIOLI

《结构与土木工程前沿(英文)》 2011年 第5卷 第3期   页码 304-314 doi: 10.1007/s01709-011-0123-9

摘要: Nowadays, the construction sector is more and more oriented toward the promotion of sustainability in all its activities. The goal to achieve is the optimization of performances, over the whole life-cycle, with respect to environmental, economic and social requirements. According to the latest advances, the concept of sustainability applied to constructions covers a number of branches such as life-cycle costing, ecology, durability and even structural design. Several procedures and design tools have been implemented in the framework of international research. Indeed the current trend in civil engineering research is moving towards life-time engineering, with the aim to implement integrated methodologies to consider as a whole all the sustainability requirements according to time-dependent multi-performance-based design approaches. Following a general introduction of the concept of sustainability applied to constructions, this paper presents an overview of life-time engineering methodologies according to the current state-of-the-art. In particular the methods currently received by International Standards are discussed. A special focus is devoted to the durability design of metal structures with respect to the degradation phenomena able to impair the structural capacity over time. Finally a proposal towards an integrated approach to life-time engineering design of steel structures and needs for further advances are presented.

关键词: sustainability     life-time engineering     performance based design     durability     metal structures    

Erratum to: Determination of cut-off time of accelerated aging test under temperature stress for LED

Jian Hao, Lei Jing, Hong-liang Ke, Yao Wang, Qun Gao, Xiao-xun Wang, Qiang Sun, Zhi-jun Xu,sunq@ciomp.ac.cn

《信息与电子工程前沿(英文)》 2017年 第18卷 第10期   页码 1678-1678 doi: 10.1631/FITEE.15e0483

摘要: Erratum to: , 2017 18(8):1197-1204. doi:

关键词: LED lamp     Accelerated aging test     Medium lifetime     Moving average error    

基于风险分析的可靠性指标加速验证方法研究

张辉睿

《中国工程科学》 2015年 第17卷 第5期   页码 31-37

摘要:

传统的可靠性验证试验由于一般在使用条件下进行,且只利用失效数据进行判定,往往需要大量的时间和费用。这对于高可靠长寿命船舶设备可靠性指标的验证是不可接受的。本文提出一种基于风险分析的可靠性指标加速验证方法,该方法利用退化数据进行分析,在试验风险可接受的条件下提前截止试验,得出验证结果。同时,利用高环境应力可以加速退化过程,进一步减少试验时间。本文具体给出了分析和计算提前截止试验和利用高应力进行试验产生的额外风险的方法,保证了验证结果的真实可靠。最后利用案例证实了该方法在减少验证试验时间上的有效性。

关键词: 退化数据;加速验证试验;可靠性验证;风险分析;优化设计    

钱学森——科技界的一面旗帜

涂元季

《中国工程科学》 2002年 第4卷 第2期   页码 1-7

摘要:

文章回顾了钱学森的生平,介绍了他得益于良好的家庭教育和学校教育所形成的优秀品格,展示了钱学森在美国师从冯·卡门以后的出众才华和取得的丰硕成就;文章以鲜为人知的大量事实描述了钱学森为争取返回祖国而进行的不屈不挠的斗争,以及他回到祖国后为了我国的航天事业呕心沥血的事迹,并以具体事例向人们揭示了钱学森对待金钱、荣誉和地位的崇高思想境界与高尚品德。

关键词: 生平     求知     科技攻关     工作作风     思想品德     革命情操    

LED灯具温度应力加速老化截止时间的确定 Article

Jian HAO, Lei JING, Hong-liang KE, Yao WANG, Qun GAO, Xiao-xun WANG, Qiang SUN, Zhi-jun XU

《信息与电子工程前沿(英文)》 2017年 第18卷 第10期   页码 1678-1678 doi: 10.1631/FITEE.1500483

摘要: 在LED灯具加速老化过程中,为获得最小截止时间,对其寿命进行快速预估,本文采用5阶滑动平均误差方法分析数据。选用同批次的16个样本,分别进行80℃和85℃应力条件下的加速老化。首先,采用e指数对光通维持率进行拟合,获得每个灯具的加速寿命,进而采用威布尔分布对加速寿命进行拟合,获得中位寿命。其次,采用平均滑动误差方法,可获取不同截止时间下中位寿命预估误差。结果表明:加速老化过程中,存在最小截止时间,该时间可通过滑动平均误差和截止时间的关系确定;当截止时间小于该值时,寿命预估不合理;寿命预估误差随截止时间增加而逐渐减小。对于该类LED灯具,80℃时最小截止时间为1104小时,寿命预估误差为1.15%;85℃时最小截止时间为936小时,寿命预估误差为1.24%。当寿命估计误差约为0.46%时,80 ℃和85 ℃对应的中位寿命分别为7310小时和4598小时。

关键词: LED灯具;加速老化测试;中位寿命;滑动平均误差    

Pretest analysis of shake table response of a two-span steel girder bridge incorporating accelerated

Elmira SHOUSHTARI, M. Saiid SAIIDI, Ahmad ITANI, Mohamed A. MOUSTAFA

《结构与土木工程前沿(英文)》 2020年 第14卷 第1期   页码 169-184 doi: 10.1007/s11709-019-0590-y

摘要: This paper presents pretest analysis of a shake table test model of a 0.35-scale, two-span, steel plate girder bridge. The objective of pretest analysis was to obtain an insight on the seismic response of the bridge model during the shake table tests. The bridge included seat type abutments, full-depth precast deck panels, and a two-column bent in which columns were pinned to the footing and integral with superstructure. Six accelerated bridge construction connections were incorporated in the bridge model. An analytical model was developed in OpenSees and was subjected to ten input bi-directional earthquake motions including near-fault and far-field records. The overall seismic response of the bridge was satisfactory for all the earthquake records at 100%, 150%, and 200% design level. All connections and capacity-protected components remained elastic, and the average ductility capacity surpassed the ductility demand even at 200% design level. Using experimental fragility curves developed for RC bridge columns, it was predicted that there was a probability of 45% that columns would undergo the imminent failure in the last run and a probability of 30% for their failure.

关键词: shake table test     accelerated bridge construction     steel girder bridge     OpenSEES     UHPC     simple for dead continuous for live    

基于飞机结构寿命包线的飞机结构单机寿命监控

何宇廷

《中国工程科学》 2006年 第8卷 第6期   页码 23-27

摘要:

在分析基准使用条件下飞机结构寿命包线的基础上,给出飞机结构在非基准使用条件下的寿命包线的绘制方法,阐明了在非基准使用条件下对飞机结构进行单机寿命监控的原理与方法。最后以飞机首翻后进行第二次大修的大修间隔期监控为例进行了分析说明。

关键词: 飞机结构     寿命包线     寿命监控     大修间隔期    

Monitoring corrosion of reinforcement in concrete structures via fiber Bragg grating sensors

Zhupeng ZHENG, Xiaoning SUN, Ying LEI

《机械工程前沿(英文)》 2009年 第4卷 第3期   页码 316-319 doi: 10.1007/s11465-009-0040-y

摘要: Corrosion of steel and rebar in concrete structures is one of the most frequent reasons for civil infrastructure failures. Thus, improving the effective corrosion sensor technology can greatly reduce cost and provide safe structures with long service lives. However, assessing the corrosion condition of rebars is not simple because they are buried in concrete. In this paper, using fiber Bragg grating (FBG), a corrosion sensor for monitoring steel rebars embedded in a concrete structure is developed and validated by experiments. Based on the fact that the volume and diameter of a rebar embedded in concrete will enlarge due to corrosion, an FBG packaged with fiber-reinforced plastics (FRP) is wrapped on the steel bar. During corrosion, the increase in the bar diameter leads to the increase in fiber strain, which can be measured by the shift of the wavelength of FBG. Performances of the corrosion sensor are validated by accelerating corrosion in lab experiments. The corrosion sensor is embedded in a concrete specimen put in a 5% sodium chloride solution with a constant current. Experimental results show that the corrosion sensor can monitor the concurrence of corrosion of rebars in concrete. The corrosion extent can be quantitatively evaluated through the change in the wavelength of FBG. Therefore, the corrosion sensor developed in this paper is feasible for monitoring the early corrosion of rebars in concrete.

关键词: fiber Bragg grating (FBG)     corrosion     concrete structures     accelerated corrosion test    

Enhancing fatigue life of cylinder-crown integrated structure by optimizing dimension

Weiwei ZHANG,Xiaosong WANG,Zhongren WANG,Shijian YUAN

《机械工程前沿(英文)》 2015年 第10卷 第1期   页码 102-110 doi: 10.1007/s11465-015-0329-y

摘要:

Cylinder-crown integrated hydraulic press (CCIHP) is a new press structure. The hemispherical hydraulic cylinder also functions as a main portion of crown, which has lower weight and higher section modulus compared with the conventional hydraulic cylinder and press crown. As a result, the material strength capacity is better utilized. During the engineering design of cylinder-crown integrated structure, in order to increase the fatigue life, structural optimization on the basis of the adaptive macro genetic algorithms (AMGA) is first conducted to both reduce weight and decrease peak stress. It is shown that the magnitude of the maximum principal stress is decreased by 28.6%, and simultaneously the total weight is reduced by 4.4%. Subsequently, strain-controlled fatigue test is carried out, and the stress-strain hysteresis loops and cyclic hardening curve are obtained. Based on linear fit, the fatigue properties are calculated and used for the fatigue life prediction. It is shown that the predicted fatigue life is significantly increased from 157000 to 1070000 cycles after structural optimization. Finally, according to the optimization design, a 6300 kN CCIHP has been manufactured, and priority application has been also suggested.

关键词: cylinder-crown integrated hydraulic press (CCIHP)     adaptive macro genetic algorithms (AMGA)     strain-controlled fatigue test    

Time-domain and frequency-domain approaches to identification of bridge flutter derivatives

Zhengqing CHEN

《结构与土木工程前沿(英文)》 2009年 第3卷 第2期   页码 173-179 doi: 10.1007/s11709-009-0034-1

摘要: Flutter derivatives are essential for flutter analysis of long-span bridges, and they are generally identified from the vibration testing data of a sectional model suspended in a wind tunnel. Making use of the forced vibration testing data of three sectional models, namely, a thin-plate model, a nearly streamlined model, and a bluff-body model, a comparative study was made to identify the flutter derivatives of each model by using a time-domain method and a frequency-domain method. It was shown that all the flutter derivatives of the thin-plate model identified with the frequency-domain method and time-domain method, respectively, agree very well. Moreover, some of the flutter derivatives of each of the other two models identified with the two methods deviate to some extent. More precisely, the frequency-domain method usually results in smooth curves of the flutter derivatives. The formulation of time-domain method makes the identification results of flutter derivatives relatively sensitive to the signal phase lag between vibration state vector and aerodynamic forces and also prone to be disturbed by noise and nonlinearity.

关键词: long-span bridges     wind-induced vibration     flutter derivatives     forced vibration test     time-domain method     frequency-domain method    

综合使用飞行小时在飞机构件腐蚀疲劳寿命分析中的应用

林明,金平,孙明礼

《中国工程科学》 2001年 第3卷 第3期   页码 65-67

摘要:

飞机使用环境谱中飞行环境谱和停放环境谱的组合就是飞行─停放─飞行环境谱。大多数军用飞机地面停放时间占飞机使用寿命的90%以上。海军飞机所处的高温、高湿、高盐雾腐蚀环境对飞机使用寿命有很大影响。腐蚀疲劳直接影响疲劳裂纹形成寿命。飞机使用寿命必须应用飞机使用环境谱,考虑飞行小时、日历时间和综合使用飞行小时。列举海军某直升机主桨毂轴向铰轴颈裂纹故障,通过波音公司飞机结构疲劳分析方法,在飞行小时、日历时间和综合使用飞行小时方面对其翻修期进行了探讨。

关键词: 腐蚀     腐蚀疲劳     飞行小时     日历时间     综合使用飞行小时    

Digitalization optical open loop test system for fiber optic gyroscope

ZHANG Deng-wei, SHU Xiao-wu, MU Xu-dong, LIU Cheng

《机械工程前沿(英文)》 2006年 第1卷 第4期   页码 434-438 doi: 10.1007/s11465-006-0053-8

摘要: In order to receive and process the open loop signal from fiber optic gyroscopes speedily, stably and expediently, and to realize the amity interface between human and machine, a digital system that can convert GPIB (general purpose interface bus ) parallel bus into Universal Serial Bus is developed. All the interface functions of GPIB and the hardware system are realized through FPGA. With a digital sampling and processing system designed with VC++ in Windows platform, the real-time controlling procedure, high-speed receiving and sending data can be carried out, and the results can be displayed too. So the design of the system is flexible, the reliability and the stability are improved, error rate is no more than 10, the highest bit rate is 8 MB/s and the open loop detection system for optic fiber gyros achieves standardization and complete digitalization simultaneously.

关键词: stability     real-time controlling     standardization     controlling procedure     complete digitalization    

A new procedure combining GC-MS with accelerated solvent extraction for the analysis of phthalic acid

Tingting MA, Ying TENG, Peter CHRISTIE, Yongming LUO, Yongshan CHEN, Mao YE, Yujuan HUANG

《环境科学与工程前沿(英文)》 2013年 第7卷 第1期   页码 31-42 doi: 10.1007/s11783-012-0463-2

摘要: An optimized procedure based on gas chromatography-mass spectrometry (GC-MS) combined with accelerated solvent extraction (ASE) is developed for the analysis of six phthalic acid esters (PAEs), which are priority soil pollutants nominated by United States Environmental Protection Agency (USEPA). Quantification of PAEs in soil employs ultrasonic extraction (UE) (USEPA 3550) and ASE (USEPA 3545), followed by clean up procedures involving three different chromatography columns and two combined elution methods. GC-MS conditions under selected ion monitoring (SIM) mode are described and quality assurance and quality control (QA/QC) criteria with high accuracy and sensitivity for target analytes were achieved. Method reliability is assured with the use of an isotopically labeled PAE, di- -butyl phthalate-d4 (DnBP-D4), as a surrogate, and benzyl benzoate (BB) as an internal standard, and with the analysis of certified reference materials (CRM). QA/QC for the developed procedure was tested in four PAE-spiked soils and one PAE-contaminated soil. The four spiked soils were originated from typical Chinese agricultural fields and the contaminated soil was obtained from an electronic waste dismantling area. Instrument detection limits (IDLs) for the six PAEs ranged 0.10–0.31 μg·L and method detection limits (MDLs) of the four spiked soils varied from a range of 20–70 μg·kg to a range of 90– 290 μg·kg . Linearity of response between 20 μg·L and 2 mg·L was also established and the correlation coefficients ( ) were all>0.998. Spiked soil matrix showed relative recovery rates between 75 and 120% for the six target compounds and about 93% for the surrogate substance. The developed procedure is anticipated to be highly applicable for field surveys of soil PAE pollution in China.

关键词: phthalic acid esters     quality assurance and quality control     soil type     accelerated solvent extraction     certified reference materials    

Precast steel–UHPC lightweight composite bridge for accelerated bridge construction

Shuwen DENG, Xudong SHAO, Xudong ZHAO, Yang WANG, Yan WANG

《结构与土木工程前沿(英文)》 2021年 第15卷 第2期   页码 364-377 doi: 10.1007/s11709-021-0702-3

摘要: In this study, a fully precast steel–ultrahigh performance concrete (UHPC) lightweight composite bridge (LWCB) was proposed based on Mapu Bridge, aiming at accelerating construction in bridge engineering. Cast-in-place joints are generally the controlling factor of segmental structures. Therefore, an innovative girder-to-girder joint that is suitable for LWCB was developed. A specimen consisting of two prefabricated steel–UHPC composite girder parts and one post-cast joint part was fabricated to determine if the joint can effectively transfer load between girders. The flexural behavior of the specimen under a negative bending moment was explored. Finite element analyses of Mapu Bridge showed that the nominal stress of critical sections could meet the required stress, indicating that the design is reasonable. The fatigue performance of the UHPC deck was assessed based on past research, and results revealed that the fatigue performance could meet the design requirements. Based on the test results, a crack width prediction method for the joint interface, a simplified calculation method for the design moment, and a deflection calculation method for the steel–UHPC composite girder in consideration of the UHPC tensile stiffness effect were presented. Good agreements were achieved between the predicted values and test results.

关键词: accelerated bridge construction     ultrahigh-performance concrete     steel–UHPC composite bridge     UHPC girder-to-girder joint    

标题 作者 时间 类型 操作

Accelerated life-time test of MEA durability under vehicle operating conditions in PEM fuel cell

Tian TIAN, Jianjun TANG, Wei GUO, Mu PAN

期刊论文

Sustainability of steel structures: towards an integrated approach to life-time engineering design

Raffaele LANDOLFO, Lucrezia CASCINI, Francesco PORTIOLI

期刊论文

Erratum to: Determination of cut-off time of accelerated aging test under temperature stress for LED

Jian Hao, Lei Jing, Hong-liang Ke, Yao Wang, Qun Gao, Xiao-xun Wang, Qiang Sun, Zhi-jun Xu,sunq@ciomp.ac.cn

期刊论文

基于风险分析的可靠性指标加速验证方法研究

张辉睿

期刊论文

钱学森——科技界的一面旗帜

涂元季

期刊论文

LED灯具温度应力加速老化截止时间的确定

Jian HAO, Lei JING, Hong-liang KE, Yao WANG, Qun GAO, Xiao-xun WANG, Qiang SUN, Zhi-jun XU

期刊论文

Pretest analysis of shake table response of a two-span steel girder bridge incorporating accelerated

Elmira SHOUSHTARI, M. Saiid SAIIDI, Ahmad ITANI, Mohamed A. MOUSTAFA

期刊论文

基于飞机结构寿命包线的飞机结构单机寿命监控

何宇廷

期刊论文

Monitoring corrosion of reinforcement in concrete structures via fiber Bragg grating sensors

Zhupeng ZHENG, Xiaoning SUN, Ying LEI

期刊论文

Enhancing fatigue life of cylinder-crown integrated structure by optimizing dimension

Weiwei ZHANG,Xiaosong WANG,Zhongren WANG,Shijian YUAN

期刊论文

Time-domain and frequency-domain approaches to identification of bridge flutter derivatives

Zhengqing CHEN

期刊论文

综合使用飞行小时在飞机构件腐蚀疲劳寿命分析中的应用

林明,金平,孙明礼

期刊论文

Digitalization optical open loop test system for fiber optic gyroscope

ZHANG Deng-wei, SHU Xiao-wu, MU Xu-dong, LIU Cheng

期刊论文

A new procedure combining GC-MS with accelerated solvent extraction for the analysis of phthalic acid

Tingting MA, Ying TENG, Peter CHRISTIE, Yongming LUO, Yongshan CHEN, Mao YE, Yujuan HUANG

期刊论文

Precast steel–UHPC lightweight composite bridge for accelerated bridge construction

Shuwen DENG, Xudong SHAO, Xudong ZHAO, Yang WANG, Yan WANG

期刊论文