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Evolution of Residual Stresses in Micro-arc Oxidation Ceramic Coatings on 6061 Al Alloy

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Chinese Journal of Mechanical Engineering 2013年第6期26卷 1149-1153页

作者： SHEN Dejiu CAI Jingrui GUO Changhong liu peiyu State Key Laboratory of Metastable Materials Science and Technology Yanshan University College of Materials Science and Engineering Yanshan University Dalian Huarui Heavy Industry Group Co. Ltd.

Most researches on micro-arc oxidation mainly focus on the application rather than discovering the evolution of residual stresses. However, residual stresses in the surface coatings of structural components have adverse effects on their properties, such as fatigue life, dimensional stability and corrosion resistance, etc. The micro-arc oxidation ceramic coatings are produced on the surfaces of 6061 aluminum alloy by a homemade asymmetric AC type of micro-arc oxidation equipment of 20 kW. A constant current density of 4.4___0.1 A/dm2 and a self-regulated composite electrolyte are used. The micro-arc oxidation treatment period ranges from 10 min to 40 min, and the thickness of the ceramic coatings is more than 20 Bin. Residual stresses attributed to 7-A1203 constituent in the coatings at different micro-arc oxidation periods are analyzed by an X-ray diffractometer using the sin2~u method. The analysis results show that the residual stress in the ceramic coatings is compressive in nature, and it increases first and then decreases with micro-arc oxidation time increase. The maximum stress value is 1 667_＋20 MPa for period of 20 min. Through analyzing the coating thickness, surface morphology and phase composition, it is found that the residual stress in the ceramic coatings is linked closely with the coating growth, the phase composition and the micro cracks formed. It is also found that both the heat treatment and the ultrasonic action release remarkably the residual compressive stress. The heat treatment makes the residual compressive stress value decrease 1 378 MPa. The ultrasonic action even alters the nature of the residual stress, making the residual compressive stress change into a residual tensile stress.

关键词： residual stress ceramic coating micro-arc oxidation 6061 aluminum alloy

MCR-YOLO model for underwater target detection based on multi-color spatial features

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Optoelectronics Letters 2024年第5期20卷 313-320页

作者： liu peiyu XING Weiwei MA Yixuan School of Software Engineering Beijing Jiaotong UniversityBeijing 100044China

Within the fields of underwater robotics and ocean information processing, computer vision-based underwater target detection is an important area of research. Underwater target detection is made more difficult by a number of problems with underwater imagery, such as low contrast, color distortion, fuzzy texture features, and noise interference, which are caused by the limitations of the unique underwater imaging environment. In order to solve the above challenges, this paper proposes a multi-color space residual you only look once(MCR-YOLO) model for underwater target detection. First, the RGB image is converted into YCb Cr space, and the brightness channel Y is used to extract the non-color features of color-biased images based on improved Res Net50. Then, the output features of three scales are combined between adjacent scales to exchange information. At the same time, the image features integrated with low-frequency information are obtained via the low-frequency feature extraction branch and the three-channel RGB image, and the features from the three scales of the two branches are fused at the corresponding scales. Finally, multi-scale fusion and target detection are accomplished utilizing the path aggregation network(PANet) framework. Experiments on relevant datasets demonstrate that the method can improve feature extraction of critical targets in underwater environments and achieve good detection accuracy.

关键词： underwater image utilizing

Development of permanent magnetic refrigerator at room temperature

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Rare Metals 2006年第Z1期25卷 641-644页

作者： HUANG Jiaohong liu Jinrong JIN peiyu YAN Hongwei QIU Jufeng XU Laizi ZHANG Jiuxing Key Lab of Advanced Functional Materials the Ministry of Education Beijing University of Technology Beijing 100022 China Baotou Research Institute of Rare Earths Baotou 014030 China Baotou Research Institute of Rare Earths Baotou 014030 China Baotou Research Institute of Rare Earths Baotou 014030 China Baotou Research Institute of Rare Earths Baotou 014030 China Baotou Research Institute of Rare Earths Baotou 014030 China Baotou Research Institute of Rare Earths Baotou 014030 China Key Lab of Advanced Functional Materials the Ministry of Education Beijing University of Technology Beijing 100022 China

A reciprocating magnetic refrigerator was developed based on the active magnetic regeneration technology. Rare earth metal Gd and intermetallic compound LaFe11.2Co0.7Si1.1 were used as the magnetic operating materials in the machine. The particles of the magnetic operating materials, with diameter of 0.5-2 mm and total mass of 950 g, were mounted in the cooling bed. A magnetic field was assembled using NdFeB rare earth permanent magnets. It had the magnetic field space of Φ 34×200 and the magnetic induction of 1.5 T. The water at pH=10 is used as a heat transfer fluid. When the ambient temperature is 296 K, a temperature span of 18 K was achieved after operation of 45 min at a frequency of 0.178 Hz. The temperature span and the output power increase significantly with the increasing velocity of heat transfer.

关键词： room temperature magnetic refrigerator NdFeB permanent magnet rare earth metal

Analysis of microscopic pore structures of rocks before and after water absorption

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Mining Science and Technology 2011年第2期21卷 287-293页

作者： Li Dejian Wang Guilian Han Liqiang liu peiyu He Manchao Yang Guoxing Tai Qimin Chen Cheng State Key Laboratory of Geomechanics and Deep Underground Engineering Beijing 100083 China Institute of Geotechnical Engineering China University of Mining ＆ Technology Beijing 100083 China Sichuan Staff University of Science and Technology Sichuan 610101 China Engineering Research Institute of General Armament Department Beijing 100083 China

Hydrophilic characteristics of rocks are affected by their microscopic pore structures,which clearly change after water *** absorption tests and scanning electron microscopic（SEM） experiments on rock samples,located at a site in Tibet,China,were carried out Changes of rock pore structures before and after water absorption were studied with the distribution of pore sizes and fractal characteristics of *** results show that surface porosities,fractal dimensions of pores and the complexity of pore structures increased because the number of new small pores produced increased or the original macropore flow channels were expanded after rocks absorbed *** were points of inflection on their water absorption *** water absorption of other rocks,surface porosities and fractal dimensions of pores and complexity of pore structures decreased as the original pore flow channels became *** absorption curves did not *** porosity and the pore fractal dimensions of rocks have good linear relationships before and after water absorption.

关键词： Hydrophilic characteristics Pore structures Pore size distribution Pore fractal characteristics

Key gene networks that control magnetosome biomineralization in magnetotactic bacteria

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National Science Review 2023年第1期10卷 166-177页

作者： peiyu liu Yue Zheng Rongrong Zhang Jinling Bai Kelei Zhu Karim Benzerara Nicolas Menguy Xiang Zhao Andrew P.Roberts Yongxin Pan Jinhua Li Key Laboratory of Earth and Planetary Physics Institute of Geology and GeophysicsInnovation Academy for Earth ScienceChinese Academy of Sciences Laboratory for Marine Geology Qingdao National Laboratory for Marine Science and Technology Southern Marine Science and Engineering Guangdong Laboratory College of Earth and Planetary Sciences University of Chinese Academy of Sciences State Key Laboratory of Marine Environmental Science College of the Environment and Ecology Xiamen University Sorbonne Université UMR CNRS 7590MNHN IRD Institut de Minéralogie de Physique des Matériaux et de CosmochimieIMPMC Research School of Earth Sciences Australian National University

Magnetotactic bacteria(MTB) are a group of phylogenetically and morphologically diverse prokaryotes that have the capability of sensing Earth’s magnetic field via nanocrystals of magnetic iron *** crystals are enclosed within intracellular membranes or organelles known as magnetosomes and enable a sensing function known as *** MTB were discovered over half a century ago,the study of the magnetosome biogenesis and organization remains limited to a few cultured MTB ***,we present an integrative genomic and phenomic analysis to investigate the genetic basis of magnetosome biomineralization in both cultured and uncultured strains from phylogenetically diverse MTB *** magnetosome gene contents/networks of strains are correlated with magnetic particle morphology and chain *** propose a general model for gene networks that control/regulate magnetosome biogenesis and chain assembly in MTB systems.

关键词： magnetotactic bacteria magnetosome biomineralization chain assembly gene networks integrative genomics and phenomics

Diverse intracellular inclusion types within magnetotactic bacteria: implications for paleomagnetic and paleoenvironmental studies

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Diverse intracellular inclusion types within magnetotactic b...

作者： Jinhua LI peiyu liu Yan liu Yongxin PAN Institute of Geology and Geophysics Chinese Academy of Sciences

Microorganisms play a key role in the functioning and evolution of biogeochemical cycles because they were the sole inhabitants of our planet for almost 3 billion years, and because of their tremendous metabolic capac... 详细信息

关键词： Diverse intracellular inclusion types within magnetotactic bacteria implications for paleomagnetic and paleoenvironmental studies

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使令句句法结构对致使事件的压制及相关问题

湖南师范大学社会科学学报 2017年第3期46卷 130-136页

作者：刘培玉长沙理工大学文法学院

使令句包括三个动词:V1、V2和隐动词"使",隐动词"使"是使令句语义角色的指派成分和语义结构核心。方式动词V1构成的从属结构VP1通过隐动词"使"与VP2扣合在一起,VP1在附加语位置与隐动词"使"构成的主体结构合并。N2的格不是由动词V1和V2... 详细信息

使令句包括三个动词:V1、V2和隐动词"使",隐动词"使"是使令句语义角色的指派成分和语义结构核心。方式动词V1构成的从属结构VP1通过隐动词"使"与VP2扣合在一起,VP1在附加语位置与隐动词"使"构成的主体结构合并。N2的格不是由动词V1和V2指派的,而是由隐动词"使"指派的。

关键词：使令句核心合并派格

深部软岩与水作用后的强度软化特性及化学分析

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岩石力学与工程学报 2018年第A1期37卷 3374-3381页

作者：郭宏云赵健柳培玉北京特种工程设计研究院北京100028 中国矿业大学深部岩土力学与地下工程国家重点实验室北京100026 中国建筑科学研究院北京100013

应用自主研发的深部软岩水理作用智能测试系统,针对辽宁铁法集团大强煤矿深部软岩,对室内有压、无压吸水实验结束后的岩样分别进行单轴抗压强度实验,研究软岩在天然和干燥状态2种状态下的有压吸水和无压吸水的强度软化规律。实验结果表... 详细信息

应用自主研发的深部软岩水理作用智能测试系统,针对辽宁铁法集团大强煤矿深部软岩,对室内有压、无压吸水实验结束后的岩样分别进行单轴抗压强度实验,研究软岩在天然和干燥状态2种状态下的有压吸水和无压吸水的强度软化规律。实验结果表明:深部软岩的抗压强度随含水率的增加而线性减小,具有相同初始状态的岩石在无压吸水过程中的强度衰减速率相比有压吸水较大,而软岩在干燥状态下的单轴抗压强度随吸水率增加而衰减速率相比天然软岩较大。为了更好地研究岩样吸水后的强度软化机制,将吸水实验结束前后的水溶液化学成分及岩石微观结构进行对比分析。分析表明:在软岩与水的作用过程中,表面吸附的催化作用以及黏土颗粒具有较大的表面能造成了易溶性矿物在水里的溶解以及离子交换作用,产生了矿物溶蚀以及次生作用,使得吸水实验结束后的水溶液中的溶解性固体浓度有大幅度的增加、阴/阳离子浓度有了较大的变化,是岩石吸水后单轴抗压强度衰减的主要原因之一。

关键词：岩石力学深部软岩吸水实验强度软化化学分析微观结构

局域网环境下ORACLE数据库的多用户共享技术研究

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计算机工程与应用 2000年第7期36卷 114-115,141页

作者：刘培玉山东师范大学计算机科学系济南250014

该文首先剖析了ORACLE数据库的存贮结构及在局域网环境下多用户共事时产生冲突的原因；然后提出了在不修改ORACLE数据库系统本身的前提下，利用ORACLE数据库的分布功能，解决单用户ORACLE数据库在局域网环境下并发控制和多用户共享技术... 详细信息

该文首先剖析了ORACLE数据库的存贮结构及在局域网环境下多用户共事时产生冲突的原因；然后提出了在不修改ORACLE数据库系统本身的前提下，利用ORACLE数据库的分布功能，解决单用户ORACLE数据库在局域网环境下并发控制和多用户共享技术与策略。这种共享技术已在实际应用系统中得到应用，获得了满意的效果。

关键词：数据库局域网 ORACLE 管理信息系统共享