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Effects of Friction Heat on the Tribological Properties of the Woven Self-lubricating Liner

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Chinese Journal of Mechanical Engineering 2009年第6期22卷 918-924页

作者： yang yulin ZU Dalei ZHANG Ruijun QI Xiaowen Key Laboratory of Fundamental Science of Mechanical Structure and Material Science under Extreme Condition for National Defence Yanshan University Qinhuangdao 066004 China State Key Laboratory of Metastable Materials Science and Technology. Yanskan Universiry Qinhuangdao 066004 China

In the dry-sliding process of the woven self-lubricating liner which is used in the self-lubricating spherical plain bearing, the friction heat plays an important role in the tribological performances of the liner. It has important value to study on the relationship between tribological performances of the liner and the friction heat. Unforttmately, up to now, published work on this relationship is quite scarce. Therefore, the effect of friction heat on the tribological performances of the liner was investigated in the present work. The tribological behaviors of the liner were evaluated by using the high temperature end surface wear tester. Scanning electron microscopy （SEM） was utilized to examine the morphologies of worn surfaces of the liner and study the failure modes. Differential scanning calorimetry （DSC） measurement and X-ray diffraction （XRD） analysis were performed to study the behaviors of the wear debris. The temperature rise on the worn surface was calculated according to classical models. SEM observation shows that the dominating wear mechanism for the liner is mainly affected by friction shear force, contact pressure and friction heat. Higher fusion heat for the wear debris than that for the pure polytetrafluroethylene （PTFE） indicates that the PTFE is the main portion of the wear debris, and, the PTFE in the wear debris shows a higher crystallisation degree owing to the effects of friction shear force and the friction heat. Combining the calculated temperature rise results with the wear rate of the liner, it can be concluded that the effects of temperature rise o n the tribological performances of the liner become more obvious when the temperature rise exceeds the glass transition temperature （Tg） of the PTFE. The wear resistance of the liner deteriorates dramatically when the temperature rise approaches to the melting point （Ton） of the PTFE. The tribological performances of the liner can be improved when the temperature rise exceeds Tg but is far l

关键词： woven fabric self-lubricating liner friction and wear friction heat differential scanning calorimetry thermal analysis transfer film

Precise time frequency synchronization technology for bistatic radar

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Journal of Systems Engineering and Electronics 2008年第5期19卷 929-933页

作者： Huang yulin yang Jianyu Wu Junjie Xiong Jintao School of Electronic Engineering Univ. of Electronic Science and Technology of China Chengdu 610054 P. R. China

A complete method of synchronization technology of bistatic radar using global position system （GPS） is presented. The pulse per second signal （1PPS） is elaborately modified to increase the time synchronization precision and keep loop locking. A very high time synchronization precision is achieved. Using the modified 1PPS to discipline the local OCXO, the reference frequency signal achieves both high long term stability （LTS） and short term stability （STS） properties. An algorithm, named phase abrupt change CFAR is presented to restrain the 1PPS phase abrupt change and keep loop locking. The experimental results indicate that this time and frequency synchronization method is effective and the time synchronization precision of the synchronization system can be improved from ±100 ns to ±25 ns. In addition, the phase noise is improved to 20 dB.

关键词： bistatic radar GPS time synchronization frequency phase synchronization.

Influence of Weave Structures on the Tribological Properties of Hybrid Kevlar/PTFE Fabric Composites

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Chinese Journal of Mechanical Engineering 2012年第5期25卷 1044-1051页

作者： GU Dapeng yang yulin QI Xiaowen DENG Wei SHI Lei Key Laboratory of Fundamental Science of Mechanical Structure and Material Science under Extreme Condition for National Defence Yanshan UniversityQinhuangdao 066004China

The existing research of the woven fabric self-lubricating liner mainly focus on the tribological performance improvements and the service life raised by changing different fiber type combinations, adding additive modification, and performing fiber surface modification. As fabric composites, the weave structures play an important role in the mechanical and tribological performances of the liners. However, hardly any literature is available on the friction and wear behavior of such composites with different weave structures. In this paper, three weave structures （plain, twill 1/3 and satin 8/5） of hybrid Kevlar/PTFE fabric composites are selected and pin-on-flat linear reciprocating wear studies are done on a CETR tester under different pressures and different frequencies. The relationship between the tensile strength and the wear performance are studied. The morphologies of the worn surfaces under the typical test conditions are analyzed by means of scanning electron microscopy （SEM）. The analysis results show that at 10 MPa, satin 8/5 performs the best in friction-reduction and antiwear performance, and plain is the worst. At 30 MPa, however, the antiwear performance is reversed and satin 8/5 does not even complete the 2 h wear test at 16 Hz. There is no clear evidence proving that the tensile strength has an influence on the wear performance. So the different tribological performance of the three weave structures of fabric composites may be attributed to the different PTFE proportions in the fabric surface and the different wear mechanisms. The fabric composites are divided into three regions： the lubrication region, the reinforced region and the bonding region. The major mechanisms are fatigue wear and the shear effects of the friction force in the lubrication region. In the reinforced region fiber-matrix de-bonding and fiber breakage are involved. The proposed research proposes a regional wear model and further indicates the wear process and the wear mechanism o

关键词： hybrid Kevlar/PTFE fabric composite friction wear weave structure scanning electron microscopy

Sliding Wear of the Hybrid Kevlar/PTFE Fabric Reinforced Phenolic Composite Filled with Nano-titania

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Chinese Journal of Mechanical Engineering 2011年第1期24卷 154-159页

作者： yang yulin HUANG Shijun ZU Dalei ZHANG Ruijun QI Xiaowen Key Laboratory of Fundamental Science of Mechanical Structure and Material Science under Extreme Condition for National Defence Yanshan University Qinhuangdao 066004 China State Key Laboratory of Metastable Materials Science and Technology Yanshan University Qinhuangdao 066004 China

The Kevlar/polytetrafluroethylene（Kevlar/PTFE） fabric composite can be used as a self-lubricating liner of the self-lubricating *** types of nano-particles can improve the tribological performance of the polymer-based ***,up to now,published work on the effect of nano-particles on the tribological performance of the fabric composite which can be used as a self-lubricating liner is quite ***,for the purpose of exploring a way to significantly improve the tribological performance of the fabric composite,the tribological performance of the Kevlar/PTFE fabric composite filled with nano-titania is evaluated by using the block-on-ring wear *** scanning electron microscopy is utilized to observe the morphologies of worn surfaces of the fabric composites and the *** tensile properties of the composites are evaluated on the universal material testing *** test results show that the addition of nano-titania at a proper mass fraction of the matrix resin improves the wear resistance and the tensile strength,decreases the friction coefficient,and makes the wear volume of the composite reach a relative steady state more quickly;plastic deformation and microcutting are important for the wear of the fabric composite;a lubricating layer is formed on the worn surface of the composite during sliding,and the lubricating layer is critical for the tribological performance of the composite;the formation and properties of the lubricating layer are influenced by the nano-titania *** proposed study on the effect of nano-titania on the tribological performance of the Kevlar/PTFE fabric composite,especially on the evolution of the worn surface of the composite,provides the basis for further understanding of the influence mechanism of the nano-particles on the tribological performance of the composite and explores a method of improving the tribological performance of the composite.

关键词： hybrid Kevlar/PTFE fabric composite self-lubricating liner nano-titania friction and wear lubricating layer

Spatiotemporal Evolution and Linkage Analysis of Mutton Price in Xinjiang

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Journal of Systems Science and Information 2024年第5期12卷 667-689页

作者： yulin yang Jian XU Lean YU School of Economics and Management University of Chinese Academy of SciencesBeijing 100190China Business School Sichuan UniversityChengdu 610065China School of Business Shenzhen Institute of TechnologyShenzhen 518116China

The mutton industry plays a pivotal role in the animal husbandry industry of Xinjiang Uygur Autonomous *** better monitor the volatility movement and risk warning of mutton price,the fluctuation characteristics of mutton prices and the future trend of prices are analyzed *** the one hand,the Hodrick Prescott(HP)filter method is used to analyze the long-term trends and cyclical characteristics of mutton prices in Xinjiang and explored the spatial evolution characteristics of mutton price fluctuations in various regions of *** the other hand,the Threshold Auto-Regressive(TAR)model is used to analyze the linkage relationship between mutton prices and the prices of other livestock *** empirical results show that 1)the overall volatility of mutton price in Xinjiang is high,showing a trend of rising first,then falling and then rising from the temporal perspective.2)At the regional level,the price in the south is higher than that of the north,showing a decreasing trend from south to north on the whole from the spatial viewpoint.3)From the linkage relationship perspective,mutton and beef are complementary in the short term,but they are substitutes each other in the long *** paper explores the characteristics of mutton price fluctuations in Xinjiang from the single time series of mutton prices and the linkage with other livestock products,which provides a reliable basis for the monitoring and risk warning of mutton price fluctuation.

关键词： mutton price fluctuation spatiotemporal volution linkage analysis Hodrick Prescott filtering method threshold autoregressive model

Heterojunction Incorporating Perovskite and Microporous Metal–Organic Framework Nanocrystals for Efficient and Stable Solar Cells

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Nano-Micro Letters 2020年第6期12卷 203-213页

作者： Xuesong Zhou Lele Qiu Ruiqing Fan Jian Zhang Sue Hao yulin yang MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage School of Chemistry and Chemical EngineeringHarbin Institute of TechnologyHarbin 150001People’s Republic of China

In this paper,we present a facile approach to enhance the efficiency and stability of perovskite solar cells(PSCs)by incorporating perovskite with microporous indium-based metal–organic framework[In12O(OH)16(H2O)5(btc)6]n(In-BTC)nanocrystals and forming heterojunction light-harvesting *** interconnected micropores and terminal oxygen sites of In-BTC allow the preferential crystallization of perovskite inside the regular cavities,endowing the derived films with improved morphology/crystallinity and reduced grain boundaries/***,the In-BTC-modified PSC yields enhanced fill factor of 0.79 and power conversion efficiency(PCE)of 20.87%,surpassing the pristine device(0.76 and 19.52%,respectively).More importantly,over 80%of the original PCE is retained after 12 days of exposure to ambient environment(25°C and relative humidity of^65%)without encapsulation,while only about 35%is left to the pristine device.

关键词： Metal–organic framework Nanocrystal Heterojunction Light-harvesting layer Perovskite solar cell

Synthesis of Hydroxyapatite Nanorods under Mild Conditions and Their Drug Release Properties

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Chinese Journal of Chemistry 2015年第9期33卷 1024-1030页

作者： Deyan Kong Xinli Xiao Xueying Qiu Wenbo Zhang yulin yang Department of Chemistry School of Science Harbin Institute of Technology Harbin Heilongjiang 150001 China

Hydroxyapatite （HAp） nanorods possess vast potential applications in various fields, and here HAp nanorods with high aspect ratio were synthesized via a convenient two-stage precipitation-hydrolysis process at 60℃ under atmospheric pressure. The precursor of CaHPO4 at precipitation stage is well crystallized as nubby morphology with CTAB as surfactant, while CaHPO4 was dissolved and CTA＋ stabilized the HAp nuclei during the hydrolysis stage. OH- ions were absorbed onto the active crystal surface, where Ca2＋ and PO4 3- reacted with OH- to make the nuclei grow into larger crystals, and highly crystalline HAp nanorods were obtained by Ostwald ripening. The loaded drug of IBU on the HAp crystals can be 100% released in 24 h. PVP modified HAp nanorods can increase the drug-loading capacity and release drug faster than pure HAp nanorods. The results indicate that HAp nanorods modified with suitable surfactants are of great use in drug delivery system.

关键词： synthesis design nanoparticles drug delivery crystal growth

Selective hydrogenation improves interface properties of high-k dielectrics on 2D semiconductors

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Nano Research 2022年第5期15卷 4646-4652页

作者： yulin yang Tong yang Tingting Song Jun Zhou Jianwei Chai Lai Mun Wong Hongyi Zhang Wenzhang Zhu Shijie Wang Ming yang Fujian Provincial Key Laboratory of Optoelectronic Technology and Devices School of Optoelectronic and Communication EngineeringXiamen University of TechnologyXiamen 361024China Department of Applied Physics The Hong Kong Polytechnic UniversityHung HomKowloonHong Kong SARChina College of Physics and Space Science China West Normal UniversityNanchong 637002China Institute of Materials Research and Engineering Agency for ScienceTechnology and Research(A*STAR)2 Fusionopolis WayInnovis 138634Singapore

The integration of high-k dielectrics with two-dimensional(2D)semiconductors is a critical step towards high-performance nanoelectronics,which however remains challenging due to the high density of interface states and the damage to the monolayer 2D *** this study,we propose a selective hydrogenation strategy to improve the interface properties while the 2D semiconductors are not *** the interface of monolayer molybdenum disulfide(MoS_(2))and silicon nitride as an example,we show substantially improved interface properties for electronic applications after the interfacial hydrogenation,as evidenced by reduced inhomogeneous charge redistribution,increased band offset,and nearly intact electronic properties of MoS_(2).Importantly,this hydrogenation process selectively occurs only at the silicon nitride surface and is compatible with the current semiconductor fabrication *** further show that this strategy is general and applicable to other interfaces between high-k dielectrics and 2D semiconductors such as hafnium dioxide(HfO_(2))on the monolayer MoS_(2).Our results demonstrate a simple yet viable way to improve the integration of high-k dielectrics on a broad range of 2D transition metal disulfide semiconductors,shedding light on practical electronic and optoelectronic applications.

关键词： two-dimensional(2D)materials high-k dielectrics molybdenum disulfide interfacial properties transition metal disulfide(TMD)

High efficient removal of HCN over porous CuO/CeO2 micro-nano spheres at lower temperature range

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Chinese Journal of Chemical Engineering 2021年第10期34卷 155-164页

作者： Zhihao Yi Jie Sun Jigang Li Tian Zhou Shouping Wei Hongjia Xie yulin yang Department of Chemistry Defense Institute of NBC DefenseBeijing 102205China

The porous CeO2 flowerlike micro-nano spheres based materials were prepared to remove HCN effectively at lower temperature *** CeO2 and a serious of porous flowerlike ceria based materials loaded with metal species including Cu,Ag,Ni,Co and Fe were synthesized by hydrothermal method and precipitation method *** physicochemical properties were probed by means of XRD,H2-TPR,BET,SEM and *** removal ability for 130 mg·m﹣3 HCN over CuO/CeO2 showed the highest activity,the breakthrough time of which was more than 70 min at the condition of 30℃,120,000 h-1 and b 5%(volume)H2O,owe to a higher relative atomic ratio of oxygen vacancies and Oβ,the stronger interaction between metal particle and support,the optimum redox *** reaction mechanism was speculated by detecting the reaction products selectivity at different reaction *** was shown that the reaction system for removal of HCN over CuO/CeO2 catalytic material involved chemisorption,catalytic hydrolysis,catalytic oxidation as well as NH3-SCR reactions.

关键词： Rice(Oryza sativa L.) Saline-alkaline stress Abscisic acid(ABA) OsABA8ox1-kd Endogenous ABA levels