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关键词

Griewank；双尺度结构；多尺度量子谐振子算法；量子隧道效应 1

低频振荡 1

分歧理论 1

奇异 1

并网逆变器；模型预测控制；直接功率控制；三矢量；恒定开关频率；功率误差 1

弹性应变能密度 1

断裂判据 1

潜在危险区（带） 1

煤与瓦斯突出 1

矿井中的动力现象 1

稳定性系数 1

非线性 1

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Experimental study of structural damage identification based on modal parameters and decay ratio of acceleration signals

Zhigen WU, Guohua LIU, Zihua ZHANG

《结构与土木工程前沿（英文）》 2011年 第5卷 第1期   页码 112-120 doi: 10.1007/s11709-010-0069-3

摘要： A novel damage assessment method based on the decay ratio of acceleration signals (DRAS) was proposed. Two experimental tests were used to show the efficiency. Three beams were gradually damaged, and then the changes of dynamic parameters were monitored from initial to failure state. In addition, a new method was compared with the linear modal-based damage assessment using wavelet transform (WT). The results clearly show that DRAS increases in linear elasticity state and microcrack propagation state, while DRAS decreases in macrocrack propagation state. Preliminary analysis was developed considering the beat phenomenon in the nonlinear state to explain the turn point of DRAS. With better sensibility of damage than modal parameters, probably DRAS is a promising damage indicator in damage assessment.

关键词： damage assessment     decay ratio of acceleration signals (DRAS)     wavelet transform (WT)     modal analysis     reinforced concrete beam     beat phenomenon    

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Comparison of human nasal epithelial cells grown as explant outgrowth cultures or dissociated tissue cultures

null

《医学前沿（英文）》 2013年 第7卷 第4期   页码 486-491 doi: 10.1007/s11684-013-0287-x

摘要：

The purpose of this study was to compare cell growth characteristics, ciliated cell differentiation, and function of human nasal epithelial cells established as explant outgrowth cultures or dissociated tissue cultures. Human nasal mucosa of the uncinate process was obtained by endoscopy and epithelial cell cultures were established by explant outgrowth or dissociated tissue culture methods. Epithelial cell growth characteristics were observed by inverted phase contrast microscopy. Ciliated cell differentiation was detected by β-tubulin IV and ZO-1 immunocytochemistry. Basal and ATP-stimulated ciliary beat frequency (CBF) was measured using a high-speed digital microscopic imaging system. Both the explant and dissociated tissue cultures established as monolayers with tight junctions and differentiated cell composition, with both types of cultures comprising ciliated and non-ciliated epithelial cells. Fibroblasts were also frequently found in explant cultures but rarely seen in dissociated tissue cultures. In both culture systems, the highest ciliated cell density appeared at 7th–10th culture day and declined with time, with the lifespan of ciliated cells ranging from 14 to 21 days. Overall, 10% of the cells in explant cultures and 20% of the cells in the dissociated tissue cultures were ciliated. These two cultures demonstrated similar ciliary beat frequency values at baseline (7.78±1.99 Hz and 7.91±2.52 Hz, respectively) and reacted equivalently following stimulation with 100 μM ATP. The results of this study indicate that both the explant outgrowth and dissociated tissue culture techniques are suitable for growing well-differentiated nasal ciliated and non-ciliated cells, which have growth characteristics and ciliary activity similar to those of nasal epithelial cells in vivo.

关键词： ciliated cells     ciliary beat frequency     dissociated tissue culture     explant culture     nasal epithelial cells    

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电力系统低频振荡中的非线性奇异现象

马景兰,王伟,万京生,张永丽

《中国工程科学》 2009年 第11卷 第8期   页码 93-96

摘要：

低频振荡是影响电力系统稳定运行的一个重要方面。阐述了低频振荡产生的机理和分析方法，利用Hopf分歧理论，针对一个四阶模型的单机无穷大系统，分析了在临界点附近时可能出现的非线性奇异现象。研究表明：由于分歧的存在，导致系统稳定性在临界点附近出现奇异，从而影响了电力系统的稳定域。

关键词： 低频振荡     分歧理论     非线性     奇异    

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Vibration analysis of medium and small span bridges subjected to mixed marshalling freight trains

LI Qi, WU Dingjun, HUANG Xiaobin

《结构与土木工程前沿（英文）》 2008年 第2卷 第2期   页码 133-138 doi: 10.1007/s11709-008-0019-5

摘要： It has been reported several times that train derailment occurs when mixed marshalling freight trains traverse bridges at high speeds in China. This study aims to explain this phenomenon numerically based on the train-bridge coupling vibration theory and its associated computer program. The train-bridge vibration characteristic is analyzed by a computer program when mixed marshalling freight trains traverse 32-meter-span prestressed concrete simple beam bridges. The mechanism that dynamic responses of the bridges are prominent and that empty trains are inclined to derail are derived from the dynamic responses analysis. The analysis indicates that the significant differences of axle loads between heavy vehicles and empty vehicles produce periodic forced loadings of large amplitudes. These periodic loadings cause severe vibration of bridges. In turn, severe vibration of the bridges produces intensive counteraction to empty vehicles.

关键词： train-bridge vibration     vibration characteristic     associated computer     train-bridge     phenomenon    

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Piezoelectric diffuser/nozzle micropump with double pump chambers

WANG Wei, ZHANG Ying, TIAN Li, CHEN Xiaojie, LIU Xiaowei

《机械工程前沿（英文）》 2008年 第3卷 第4期   页码 449-453 doi: 10.1007/s11465-008-0076-4

摘要： To eliminate check valve fatigue and valve clogging, diffuser/nozzle elements are used for flow rectification in a valveless diffuser/nozzle micropump instead of valves. However, the application of this type of micropump is restricted because of its pulsating or periodic flow and low pump flux. In this paper, a diffuser/nozzle Si/Glass micropump with two pump chambers by IC and MEMS technology is designed. The fabrication process requires only one mask and one etch step, so that the fabrication has the advantages of low cost, short processing period, and facilitation of miniaturization. The pump is equipped with a glass cover board so as to conveniently observe the flow status. Pump-chambers and diffuser elements are fabricated by the anisotropic KOH-etch technique on the silicone substrate, and the convex corner is designed to compensate for an anisotropic etch. The driving force of the micropump is produced by the PZT piezoelectric actuator. The pump performance with both actuators actuated in anti- or same-phase mode is also researched. The result indicates that the micropump achieves great performance with the actuators working at anti-phase. This may be because the liquid flows steadily, pulse phenomenon is very weak, and the optimal working frequency, pump back pressure, and flow rate are both double that of the pump driven in same-phase.

关键词： diffuser/nozzle Si/Glass     phenomenon     rectification     diffuser/nozzle micropump     frequency    

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Solid-state transformer-based new traction drive system and control

Jianghua FENG, Jing SHANG, Zhixue ZHANG, Huadong LIU, Zihao HUANG

《机械工程前沿（英文）》 2018年 第13卷 第3期   页码 411-426 doi: 10.1007/s11465-018-0467-0

摘要：

A new type of traction drive system consisting of solid-state traction transformer (SSTT), inverter unit, auxiliary inverter, traction motor and other key components is built in order to suit the demand of developing the next-generation electric traction system which will be efficient and lightweight, with high power density. For the purpose of reducing system volume and weight and improving efficiency and grid-side power quality, an efficient SSTT optimized topology combining high-voltage cascaded rectifiers with high-power high-frequency LLC resonant converter is proposed. On this basis, an integrated control strategy built upon synchronous rotating reference frame is presented to achieve unified control over fundamental active, reactive and harmonic components. The carrier-interleaving phase shift modulation strategy is proposed to improve the harmonic performance of cascaded rectifiers. In view of the secondary pulsating existing in a single-phase system, the mathematical model of secondary power transfer is built, and the mechanism of pulsating voltage resulting in beat frequency of LLC resonant converter is revealed, so as to design optimum matching of system parameters. Simulation and experimental results have verified that the traction system and control scheme mentioned in this paper are reasonable and superior and that they meet the future application requirements for rail transit.

关键词： solid-state traction transformer     high-voltage cascaded rectifier     LLC resonant converter     synchronous rotating reference frame     carrier-interleaving phase shift control     secondary pulsating voltage     beat frequency    

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用于并网逆变器的改进三矢量无差拍模型预测直接功率控制策略 None

Chen-wen CHENG, Heng NIAN, Long-qi LI

《信息与电子工程前沿（英文）》 2018年 第19卷 第11期   页码 1420-1431 doi: 10.1631/FITEE.1601874

摘要： 用于并网逆变器的传统模型预测直接功率控制，在每个控制周期只使用一个逆变器电压矢量，导致并网电流和功率出现大量谐波分量，降低电能质量。为提高稳态性能，预测控制需要很高的采样频率，同时由于计算复杂，预测算法需要较长执行时间，二者存在矛盾。为解决这个问题，提出一种新的无差拍模型预测直接功率控制策略，在每个控制周期使用2个有效电压矢量和1个零电压矢量。采用三矢量策略保证开关频率恒定，提高电流和功率质量。不同于传统三矢量模型预测直接功率控制策略，该方法根据功率误差而非电网电压矢量位置选择三个矢量，保证矢量计算时间始终为正。同时，无需迭代计算，有利于在数字信号处理芯片上执行算法。最后，搭建1 kW逆变器实验平台，验证了该方法的有效性。

关键词： 并网逆变器；模型预测控制；直接功率控制；三矢量；恒定开关频率；功率误差    

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煤与瓦斯突出潜在危险区（带）预测

鲜学福,许江,王宏图

《中国工程科学》 2001年 第3卷 第2期   页码 39-46

摘要：

煤矿的生产和实践证明，发生在矿井中的动力现象具有分区和成带的特点。文章探讨了把煤、岩和瓦斯作为一个体系，采用力学方法的划分问题。根据对煤岩复合样及含瓦斯煤样在复杂应力状态下力学性质的分析，基于对Drucker-prager理论的修正和完善，建立了它们的断裂判据，并给出了计算稳定性系数和潜在弹性应变能密度的公式，提出了按这两个指标划分煤与瓦斯突出潜在危险区（带）的基本方法。

关键词： 矿井中的动力现象     煤与瓦斯突出     潜在危险区（带）     断裂判据     稳定性系数     弹性应变能密度    

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Pluripotent stem cells exhibiting similar characteristics can be isolated from human fetal bone marrow, heart, liver, muscle, lung, derma, kidney, and fat

FANG Baijun, SONG Yongping, LIN Quande, ZHAO Chunhua, SHI Mingxia

《医学前沿（英文）》 2007年 第1卷 第2期   页码 185-191 doi: 10.1007/s11684-007-0035-1

摘要： Previously, we reported that a cell population derived from human fetal bone marrow (BM), termed here Flk1CD34 postembryonic pluripotent stem cells (PPSCs) that have the characteristics of mesenchymal stem cells (MSCs), could differentiate into ectodermal, endodermal and mesodermal cell types at the single cell level , and that these cells could also differentiate into the epithelium of liver, lung, gut, as well as the hematopoietic and endothelial lineages after transplantion into irradiated non-obese diabetic/severe combined immunodeficient (NOD/SCID) mice. In this study, we further isolated pluripotent stem cells from human fetal heart, liver, muscle, lung, derma, kidney, and fat and then analyzed the characteristics and function of these stem cells. It was found that the phenotype of the culture-expanded pluripotent stem cells from different fetal tissues was similar to BM-derived Flk1CD34 PPSCs, i.e. Flk1 and CD44 positive, GlyA, CD34, CD45, class I-HLA and HLA-DR negative. Morphologically, these cells were fibroblast-like and the doubling time was about 30 h. More importantly, culture-expanded pluripotent stem cells from all these fetal tissues were able to differentiate into cells with morphologic and phenotypic characteristics of adipocytes, osteocytes, neurons, glial cells and hepatocytes. These pluripotent stem cells with characteristics similar to fetal BM-derived Flk1CD34 PPSCs can be selected and cultured from tissues other than the BM. This phenomenon may help explain the stem cell plasticity found in multiple human tissues. In addition, as fetal BM-derived Flk1CD34 PPSCs, these pluripotent stem cells from different fetal tissues had the capacity for self-renewal and multi-lineage differentiation even after being expanded for more than 40 population doublings . Thus, they may be an ideal source of stem cells for treatment of inherited or degenerative diseases.

关键词： endothelial     phenomenon     ectodermal     Flk1CD34 postembryonic     irradiated non-obese    

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Griewank函数优化过程中的独特现象研究 Research Article

Yan Huang, Jian-ping Li, Peng Wang,hep128@qq.com,jpli2222@uestc.edu.cn,qhoalab@163.com

《信息与电子工程前沿（英文）》 2019年 第20卷 第10期   页码 1344-1360 doi: 10.1631/FITEE.1900155

摘要： Griewank函数是一类由二次凸函数和振荡非凸函数构成的典型多模测试函数。这两个组成部分在不同维数下显示出不同的相对重要性。不同于其他多数测试函数，随着函数维数增加，Griewank函数在优化过程出现优化难度先变难、后变易的现象。本文首先通过结构分析、数学分析和量子分析，从方法论角度解释该现象。然后，通过频率变换和幅度变换对Griewank函数作一般化处理。运用具有量子隧道效应的多尺度量子谐振子算法验证Griewank函数特性。实验结果表明Griewank函数的双尺度结构是该现象的主要原因。本文所提量子隧道效应可用于多种群体优化算法中分析解的生成和变化。

关键词： Griewank；双尺度结构；多尺度量子谐振子算法；量子隧道效应    

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标题 作者 时间 类型 操作

Experimental study of structural damage identification based on modal parameters and decay ratio of acceleration signals

Zhigen WU, Guohua LIU, Zihua ZHANG

期刊论文

Comparison of human nasal epithelial cells grown as explant outgrowth cultures or dissociated tissue cultures

null

期刊论文

电力系统低频振荡中的非线性奇异现象

马景兰,王伟,万京生,张永丽

期刊论文

Vibration analysis of medium and small span bridges subjected to mixed marshalling freight trains

LI Qi, WU Dingjun, HUANG Xiaobin

期刊论文

Piezoelectric diffuser/nozzle micropump with double pump chambers

WANG Wei, ZHANG Ying, TIAN Li, CHEN Xiaojie, LIU Xiaowei

期刊论文

Solid-state transformer-based new traction drive system and control

Jianghua FENG, Jing SHANG, Zhixue ZHANG, Huadong LIU, Zihao HUANG

期刊论文

用于并网逆变器的改进三矢量无差拍模型预测直接功率控制策略

Chen-wen CHENG, Heng NIAN, Long-qi LI

期刊论文

煤与瓦斯突出潜在危险区（带）预测

鲜学福,许江,王宏图

期刊论文

Pluripotent stem cells exhibiting similar characteristics can be isolated from human fetal bone marrow, heart, liver, muscle, lung, derma, kidney, and fat

FANG Baijun, SONG Yongping, LIN Quande, ZHAO Chunhua, SHI Mingxia

期刊论文

Griewank函数优化过程中的独特现象研究

Yan Huang, Jian-ping Li, Peng Wang,hep128@qq.com,jpli2222@uestc.edu.cn,qhoalab@163.com

期刊论文