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Application of numerical simulation to flow induced corrosion in flowing seawater system

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中国有色金属学会会刊：英文版 2004年第Z1期14卷 439-442页

作者： LIU jing-jun LIN yu-zhen YONG Xing-yue LI Xiao-yu School of Materials Science and Engineering Beijing University of Chemical Technology Beijing 100029 China School of Materials Science and Engineering Beijing University of Chemical Technology Beijing 100029 China School of Materials Science and Engineering Beijing University of Chemical Technology Beijing 100029 China School of Materials Science and Engineering Beijing University of Chemical Technology Beijing 100029 China

An established model was presented as a new kind of means for investigating flow induced corrosion. In this method the near-wall hydrodynamic parameters including wall shear stress τ and mass transfer coefficient k near the wall of materials can be numerically calculated, and combining corrosive kinetics tested by experiments, the corrosion rates can be also calculated accurately. The flow induced corrosion mechanism was further verified by numerical results in this model, and the various corrosion phenomena were explained. The modelled results also show that the ability to accurately utilize numerical method to study flow induced corrosion strongly to some extent depends on material corrosive kinetics processes tested by experiments.

关键词： flow induced corrosion numerical simulation near-wall hydrodynamic parameters mechanism

Effect of Degree-of-Symmetry on Kinetostatic Characteristics of Flexure Mechanisms:A Comparative Case Study

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Chinese Journal of Mechanical Engineering 2018年第2期31卷 54-65页

作者： Xiao-Bing He jing-jun yu Wan-Wan Zhang Guang-Bo Hao School of Mechanical Engineering and Automation Beihang University School of Engineering-Electrical and Electronic Engineering University College Cork

The current research of kinetostatic characteristics in flexure mechanisms mainly focus on the improvement of accuracy. To reduce or eliminate the parasitic motion is considered as an approach by using the common knowledge of symmetry. However, there is no study on designing the flexure mechanisms with symmetrical features as many as possible for better kinetostatic performance, when considering the resulting cost by the symmetry. In this paper, the concept of degree of symmetry(DoS) is proposed for the first time, which is committed to symmetry design in the phase of conceptual design. A class of flexure mechanisms with 0?DoS, 1?DoS, 2?DoS and 3?DoS are synthesized respectively based on the Freedom and Constraint Topology method. Their overall compliance matrices in an analytical form formulated within the framework of the screw theory are used to analyze and compare the effect of different number of DoS on the kinetostatic characteristics for flexure mechanisms. The finite element analysis(FEA) simulations are implemented to verify the analytical results. These results show that the higher the DoS is, the smaller the parasitic motion error will be. The flexure model with 3?DoS is optimized according to the overall compliance matrix and then tested by using the FEA simulation. The testing result shows that with the best combination parameters, the parasitic motion error for 3?DoS mechanism is almost eliminated. This research introduces a design principle which can alleviate the unwanted parasitic motion for better accuracy.

关键词： Flexure mechanism Symmetry Kinetostatic characteristics FEA simulation

A Scenario on the Stepwise Evolution of the Genetic Code

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Genomics, Proteomics & Bioinformatics 2007年第3期5卷 143-151页

作者： jing-Fa Xiao jun yu CAS Key Laboratory of Genome Sciences and Information Beijing Institute of Genomics Chinese Academy of Sciences Beijing 100029 China

It is believed that in the RNA world the operational （ribozymes） and the informational （riboscripts） RNA molecules were created with only three （adenosine, uridine, and guanosine） and two （adenosine and uridine） nucleosides, respectively, so that the genetic code started uncomplicated. Ribozymes subsequently evolved to be able to cut and paste themselves and riboscripts were acceptive to rigorous editing （adenosine to inosine）; the intensive diversification of RNA molecules shaped novel cellular machineries that are capable of polymerizing amino acids-a new type of cellular building materials for life. Initially, the genetic code, encoding seven amino acids, was created only to distinguish purine and pyrimidine; it was later expanded in a stepwise way to encode 12, 15, and 20 amino acids through the relief of guanine from its roles as operational signals and through the recruitment of cytosine. Therefore, the maturation of the genetic code also coincided with （1） the departure of aminoacyl-tRNA synthetases （AARSs） from the primordial translation machinery, （2） the replacement of informational RNA by DNA, and （3） the co-evolution of AARSs and their cognate tRNAs. This model predicts gradual replacements of RNA-made molecular mechanisms, cellular processes by proteins, and informational exploitation by DNA.

关键词： genetic code codon aminoacyl-tRNA synthase GC content

ANALYSIS OF BIOLOGICAL GEOCHEMISTRY OFCHEMICAL ELEMENTS IN Betula ermanii FORESTIN CHANGBAI MOUNTAINS,CHINA

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Chinese Geographical Science 2001年第4期11卷 64-69页

作者： LIU jing-shuang, yu jun-bao (Changchun Institute of Geography, the Chinese Academy of Sciences, Changchun 130021, P. R. China) Changchun Institute of Geography the Chinese Academy of Sciences Changchun P. R. China

ABSTRACT: Based on catalogue of biology and geochemistry of chemical elements, content characteristics and variation law of the large nutrient elements, the needful trace elements, the uncertain needful elements, the non-needful elements and the toxic elements in Betula ermanii trees are analyzed. The result shows that the content of the large nutrient elements in Betula ermanii trees is higher than that of other kinds of element; the contents of all kinds of elements in foliage with vigorous metabolism are higher than those in other parts; the content variations of the large nutrient elements and the needful trace elements with similar chemical property, geochemical property and biological function in different parts of Betula ermanii trees show the similar laws; but the other three kinds of elements variations are without laws. It is indicated that the variation of the needful elements in the plant follows a certain law, they are in relative equilibrium under undisturbed condition.

关键词： Betula ermanii forest chemical element variation law

Low Correspondence of EGFR Mutations in Tumor Tissue And Paired Serum of Non-Small-Cell Lung Cancer Patients

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Chinese Journal of Cancer Research 2010年第1期22卷 27-31页

作者： Guo-hong Song,jun Ren,Li-jian Zhang,Li-jun Di, Yan-hua yuan,jing yu,jun Jia Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education) Department of Medical Oncology,Peking University School of Oncology,Beijing Cancer Hospital & Institute,Beijing 100142,China Key laboratory of Carcinogenesis and Translational Research (Ministry of Education) Department of Medical Oncology Peking University School of Oncology Beijing Cancer Hospital & Institute Beijing China

Objective： Epidermal growth factor receptor （EGFR） mutations are strong determinants of tumor response to EGFR tyrosine kinase inhibitors in non-small-cell lung cancer （NSCLC） patients. The aim of this study was to evaluate the correspondence between EGFR mutations in non-small-cell lung cancer tissues and in circulating DNA. Methods： The research was conducted in 50 non-small-cell lung cancer patients who had undergone curative surgery, and in whom both serum and neoplastic tissues were available. Meanwhile sera of 33 cases of advanced NSCLC patients were also analyzed. DNA were extracted from each sample. Mutations of EGFR in exonl8-21 were examined by PCR amplification method and direct sequencing. Results： EGFR mutations were detected in 15 （30%） of 50 neoplastic tissue samples, 6 cases were in-frame deletion del E746-A750 in exonl9, 9 cases were substitution in exon 21 （all were L858R except one was L861Q）, but no mutated DNA resulted in paired serum circulating DNA samples of 50 resectable patients. As the 33 advanced NSCLC patients, EGFR mutations were detected in only 2 serum circulating DNA samples, all were L858R mutation in exon 21. Conclusion： These data indicated that it was difficult to identify EGFR mutations in circulating DNA of NSCLC patients. The use of EGFR mutation in serum as a clinical method for decision making of TKI therapy is unsatisfactory.

关键词： Circulating DNA Epidermal growth factor receptor (EGFR) Mutation Non-small-cell lung cancer (NSCLC)

Influence of the femoral head size on early postoperative gait restoration after total hip arthroplasty

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Chinese Medical Journal 2009年第13期122卷 1513-1516页

作者： ZHOU Yi-xin GUO Sheng-jie LIU Qing TANG jing LI yu-jun Department of Orthopaedic Surgery Beijing Jishuitan Hospital Fourth Clinical College of Peking University Beijing 100035 China

Background We investigated the effects of using large-diameter femoral heads in total hip prostheses on early postoperative gait restoration in patients undergoing total hip arthroplasty （THA）. Methods We collected data for 19 primary THAs using 28-mm metal-on-polyethylene heads （conventional group） and for 12 THAs （BHR group） using metal-on-metal femoral heads with an average size of 45 mm （range, 40-49mm）. All patients had unilateral femoral head avascular necrosis. All patients underwent Harris Hip Scores evaluation and gait analysis with the IDEEA device at the same 3 time points which were before surgery and then at 1 month and again at 3 months after surgery, and the parameters measured were walking speed, stride length （SL）, single limb support （SLS）, cycle duration （CD）, and swing power （SP）. Harris Hip Scores and gait analysis parameters for both groups were compared. Results Intraclass comparison indicated that Harris Hip Scores, speed scores, and gait parameter measures in both groups improved significantly with the passage of time; Interclass comparison showed no significance between Harristm postop - HarriSpreop and Harris3m postop- HarriSpreop in both groups. The speed in the BHR group at 1 month and at 3 months after surgery was significantly higher than that of conventional group. At 1 month after surgery, each mean for SLnormal - SLaffected, （SLSnormal - SLSaffected）/CD, and SPnormal - SPaffected in the BHR group was significantly lower than that for the conventional group. At 3 months after surgery, the differences between means for both groups for SLnormal - SLaffected, （SLSnormal- SLSaffected）/CD, and SPnormal - SPaffected were not significant, but the mean of SPnorrnal - SPaffected in the BHR group was significantly lower than that in the conventional group. Conclusions Our data suggest that large-diameter femoral heads in THA provide better early gait restoration than conventional-size femoral heads.

关键词： total hip arthroplasty femoral head size Harris Hip Score gait analysis

A Scenario on the Stepwise Evolution of the Genetic Code

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Genomics,Proteomics & Bioinformatics 2007年第Z1期 143-151页

作者： jing-Fa Xiao and jun yu CAS Key Laboratory of Genome Sciences and Information,Beijing Institute of Genomics,Chinese Academy of Sciences,Beijing 100029,China.

It is believed that in the RNA world the operational (ribozymes) and the infor-mational (riboscripts) RNA molecules were created with only three (adenosine,uridine,and guanosine) and two (adenosine and uridine) nucleosides,respectively,so that the genetic code started uncomplicated. Ribozymes subsequently evolved to be able to cut and paste themselves and riboscripts were acceptive to rigor-ous editing (adenosine to inosine); the intensive diversification of RNA molecules shaped novel cellular machineries that are capable of polymerizing amino acids-a new type of cellular building materials for life. Initially,the genetic code,encoding seven amino acids,was created only to distinguish purine and pyrimidine; it was later expanded in a stepwise way to encode 12,15,and 20 amino acids through the relief of guanine from its roles as operational signals and through the recruitment of cytosine. Therefore,the maturation of the genetic code also coincided with (1) the departure of aminoacyl-tRNA synthetases (AARSs) from the primordial translation machinery,(2) the replacement of informational RNA by DNA,and (3) the co-evolution of AARSs and their cognate tRNAs. This model predicts gradual replacements of RNA-made molecular mechanisms,cellular processes by proteins,and informational exploitation by DNA.

关键词： genetic code codon aminoacyl-tRNA synthase GC content

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高负荷压气机静叶根部叶型气动性能实验研究

推进技术 2017年第3期38卷 581-587页

作者：李晓东钟兢军高宇大连海事大学轮机工程学院辽宁大连116026

为研究高负荷压气机静叶根部流动状态,抽取该静叶根部叶型并模化成为平面叶栅进行吹风实验,冲角变化范围为-6°^+6°、进口马赫数变化范围为0.5~0.7。对叶栅出口截面气动参数进行了详细的测量,结果表明:非正冲角时叶展中部节距平均总压... 详细信息

为研究高负荷压气机静叶根部流动状态,抽取该静叶根部叶型并模化成为平面叶栅进行吹风实验,冲角变化范围为-6°^+6°、进口马赫数变化范围为0.5~0.7。对叶栅出口截面气动参数进行了详细的测量,结果表明:非正冲角时叶展中部节距平均总压损失系数小于等于0.036,尾迹宽度和总压损失峰值随马赫数变化均不明显,正冲角时尾迹宽度和总压损失峰值急剧增加;端壁处的压力梯度随马赫数和冲角的增加而增加;0°冲角下随马赫数的增大,出口叶展中部截面二次流动能系数增加,二次流动得到加强,高能量损失区域增大并且尾迹略有变宽。

关键词：静叶高负荷平面叶栅气动性能实验研究

基于整车行驶稳定性的电机故障和同步控制分析

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微特电机 2016年第8期44卷 70-75,81页

作者：景玉军中山职业技术学院中山528400

电驱动平地机行驶路况复杂,行驶过程中时常会出现部分电机发生通讯或系统故障,需要在驱动控制过程中采用主动的故障控制机制,以确保车辆安全行驶。当平地机在两侧附着系数相差较大的路面行驶时,易出现单侧驱动轮过度滑转和偏载工况。针... 详细信息

电驱动平地机行驶路况复杂,行驶过程中时常会出现部分电机发生通讯或系统故障,需要在驱动控制过程中采用主动的故障控制机制,以确保车辆安全行驶。当平地机在两侧附着系数相差较大的路面行驶时,易出现单侧驱动轮过度滑转和偏载工况。针对以上问题,基于整车行驶稳定性,对电机故障控制和同步控制策略进行分析,制定了电机故障工况各轮驱动转矩再分配的安全控制解决方案。利用Simulink搭建故障控制器和同步控制器模型,分析故障工况对整车行驶性能的影响。结果表明:故障和同步控制提高了车辆故障行驶的稳定性和通过性。利用设计的故障和同步控制器对车辆在对开路面加速过程的打滑工况进行分析,分析车轮打滑对整车行驶性能的影响,同步控制提高了有效驱动功率,增强了整车通过性和稳定性。

关键词：六轮电驱动平地机牵引电机故障控制同步控制行驶稳定性通过性