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Study on oxygen transport and titanium oxidation in coating cracks under parallel gas flow based on LBM modelling

Chinese Journal of Chemical Engineering 2023年第4期56卷 15-24页

作者： Shengfeng Luo Song Zhang yiping zeng Hui Zhang Lili Zheng Zhaopeng Xu Department of Engineering Physics Tsinghua UniversityBeijing 100084China Department of Mechanics and Aerospace Engineering Southern University of Science and TechnologyShenzhen 518055China Institute for Aero Engine Tsinghua UniversityBeijing 100084China Shenzhen Smart Hua Information Technology Research Co. Ltd.Shenzhen 518000China School of Aerospace Engineering Tsinghua UniversityBeijing 100084China Chinese Academy of Agricultural Mechanization Sciences Beijing 100084China

The oxygen transportation from surrounding air to coating cracks is an important factor in the oxidation and ignition of titanium alloy. In this work, the oxygen transport and surface oxidation of titanium in inclined cracks of coating under parallel airflow are studied with the lattice Boltzmann method(LBM).A boundary scheme of LBM about surface reaction is developed. The conversion factors are utilized to build the relationship between the physical scale and the lattice scale. The reliability of the LBM model is validated by the finite element method(FEM). The results show that the convective mass transport driven by the surrounding airflow and the vortex structure formed inside the crack are the two significant factors that influence the oxygen transport in cracks. The convective mass transfer plays a major role in oxygen transport when the inclination angle of the crack is small. For the cases with a large inclination angle, the oxygen transfer from the top to the bottom of the crack is mainly controlled by mass diffusion mechanism. The oxygen concentration in inclined cracks is generally less than that in vertical cracks, and oxidation and ignition of the substrate titanium might be more likely to occur in relatively vertical cracks.

关键词： Coating crack Oxidation Transport Ignition Numerical simulation

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Deep level defects in high temperature annealed InP

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Science China(Technological Sciences) 2004年第3期47卷 320-326页

作者： DONG Zhiyuan ZHAO Youwen zeng yiping DUAN Manlong LIN Lanying Material Science Centre Institute of Semiconductors Chinese Academy of Sciences Beijing 100080China

Deep level defects in high temperature annealed semi-condctng InP have been studied by deep level transient spectroscopy (DLTS). There is obvious difference in the deep defects between as-grown InP InP annealed in phosphorusambient and iron phosphide ambient, as far as their quantity and coneentration are concerned. Only two defects at 0.24 and 0.64 eV can be detected in InP annealed in iron phosphide amibent, while defects at 0.24,0.42,0.54 and 0.64 eV have been detected in InP annealed in phosphorus ambient, in contrast to two defects at 0.49 and 0.64 eV or one defect at 0.13 eV in as-grown InP. A defect suppression phenomenon related to iron diffusion process has been observed. The formation mechanism and the nature of the defects have been discussed.

关键词： InP defects annealing ambience.

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Forecasting of COVID-19: spread with dynamic transmission rate

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Journal of Safety Science and Resilience 2020年第2期1卷 91-96页

作者： yiping zeng Xiaojing Guo Qing Deng Shengfeng Luo Hui Zhang Institute of Public Safety Research Department of Engineering PhysicsTsinghua UniversityBeijing 100084China

The COVID-19 was firstly reported in Wuhan,Hubei province,and it was brought to all over China by people travelling for Chinese New *** pandemic coronavirus with its catastrophic effects is now a global *** of COVID-19 spread has attracted a great attention for public health ***,few re-searchers look into the relationship between dynamic transmission rate and preventable measures by *** this paper,the SEIR(Susceptible Exposed Infectious Recovered)model is employed to investigate the spread of *** epidemic spread is divided into two stages:before and after *** intervention,the transmission rate is assumed to be a constant since individual,community and government response has not taken into *** intervention,the transmission rate is reduced dramatically due to the societal actions or measures to reduce and prevent the spread of *** transmission rate is assumed to follow an exponential function,and the removal rate is assumed to follow a power exponent *** removal rate is increased with the evolution of the *** the real data,the model and parameters are *** transmission rate without measure is calculated to be 0.033 and 0.030 for Hubei and outside Hubei province,*** the model is established,the spread of COVID-19 in Hubei province,France and USA is *** results,USA performs the worst according to the dynamic *** model has provided a mathematical method to evaluate the effectiveness of the government response and can be used to forecast the spread of COVID-19 with better performance.

关键词： COVID-19 SEIR Emergency management Dynamic transmission rate Basic reproduction number

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The influence of MBE and device structure on the electrical properties of GaAs HEMT biosensors

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Journal of Semiconductors 2018年第12期39卷 95-98页

作者： Jiaming Luo Min Guan Yang Zhang Liqiang Chen yiping zeng Key Laboratory of Semiconductor Materials Science Beijing Key Laboratory of Low Dimensional Semiconductor Materials and DevicesInstitute of SemiconductorsChinese Academy of SciencesBeijing 100083China College of Materials Science and Optoelectronic Devices University of Chinese Academy of SciencesBeijing 100049China Lansus Technologies Inc Shenzhen 518057China

High electron mobility transistors(HEMT) have the potential to be used as high-sensitivity and realtime biosensors. HEMT biosensors have great market prospects. For the application of HEMT biosensors, the electric properties consistency of the inter-chip performance have an important influence on the stability and repeatability of the detection. In this research, we fabricated GaAs/AlGaAs HEMT biosensors of different epitaxial structures and device structures to study the electric properties consistency. We study the relationship between channel size and consistency. We investigated the distribution of device current with location on 2 inch GaAs wafer. Based on the studies, the optimal device of a GaAs HEMT biosensor is an A-type epitaxial structure, and a U-type device structure, L = 40μm, W= 200 μm.

关键词： GaAs HEMT biosensor electrical properties

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Photoelectrochemical Behavior of the GaAs/A1_(x)Ga_(l-x)As Superlattice Elect rode/Electrolyte Interface

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Chinese Physics Letters 1994年第4期11卷 239-241页

作者： LIU Yao XIAO Xurui LI Xueping REN Xinmin ZHENG Haiqun zeng yiping YAN Chunhui SUN Dianzhao The Center of Photoelectrochemistry Institute of Photographic ChemistryAcademia SinicaBeijing 100101 Institute of Semiconductors Academia SinicaBeijing 100083

Single and multiple quantum wells of lattice-matched superlattices material GaAs/A1xGal-xAs have been studied as photoelectrodes in photoelectrochemical cells containing nonaqueous *** photocurrent spectra in the potential range of-1.8 to 1.0 V(vs standard calomel electrode)were *** quantum yields for both superlattice electrodes were estimated and compared.

关键词： As quantum electrochemical

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Empirical Analysis of the Influence of Factors on the Tax Revenue in China

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International Journal of Technology Management 2015年第5期 111-113页

作者： yiping zeng School of economics and management North China Electric Power University Beijing 102206 China

This paper shows the influence of factors on the tax revenue in China using a dataset that includes tax revenue, gross domestic product （GDP）, financial expenditure and commodity retail price index （CRI）. Since the reform and open policy in 1978, the balance of financial revenue and expenditure has changed a lot in China. In order to improve the current prediction method of tax revenue, modem econometric model should be introduced. This paper research the influence of factors above on the tax revenue. First, qualitative analysis is used to clarify the causation between each factor and tax revenue. Second, econometric model is applied to research the quantitative relation. The result of empirical analysis indicates that the effect of the three factor to the financial revenue in China is positive, and the CR1 has the greatest contribution followed by the financial expenditure and GDP.

关键词：财政收入实证分析税收中国国内生产总值财政支出价格指数改革开放

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Progress in Antimonide Based III-V Compound Semiconductors and Devices

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Engineering（科研） 2010年第8期2卷 617-624页

作者： Chao Liu Yanbo Li yiping zeng Key Laboratory of Semiconductor Materials Science Institute of Semiconductors Chinese Academy of Sciences

In recent years, the narrow bandgap antimonide based compound semiconductors (ABCS) are widely regarded as the first candidate materials for fabrication of the third generation infrared photon detectors and integrated circuits with ultra-high speed and ultra-low power consumption. Due to their unique bandgap structure and physical properties, it makes a vast space to develop various novel devices, and becomes a hot research area in many developed countries such as USA, Japan, Germany and Israel etc. Research progress in the preparation and application of ABCS materials, existing problems and some latest results are briefly introduced.

关键词： Antimonide Based Compound Semiconductors (ABCS) IR Laser IR Detector Integrated Circuit Functional Device

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Growth and characterization of 0.8-μm gate length AlGaN/GaN HEMTs on sapphire substrates

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Science in China(Series F) 2005年第6期48卷 808-814页

作者： WANG Xiaoliang WANG Cuimei HU Guoxin WANG Junxi RAN Junxue FANG Cebao LI Jianping zeng yiping LI Jinmin LIU Xinyu LIU Jian QIAN He Institute of Semiconductors Chinese Academy of Sciences Beijing 100083 China Institute of Microelectronics Chinese Academy of sciences Beijing 100029 China

AIGaN/GaN high electron mobility transistor （HEMT） structures were grown on 2 inch sapphire substrates by MOCVD, and 0.8-μm gate length devices were fabricated and measured. It is shown by resistance mapping that the HEMT structures have an average sheet resistance of approximately 380 Ω/sq with a uniformity of more than 96%. The 1-mm gate width devices using the materials yielded a pulsed drain current of 784 mA/mm at Vgs=0.5 V and Vds=7 V with an extrinsic transconductance of 200 mS/mm. A 20-GHz unity current gain cutoff frequency （fT） and a 28-GHz maximum oscillation frequency （fmax） were obtained. The device with a 0.6-mm gate width yielded a total output power of 2.0 W/mm （power density of 3.33 W/mm） with 41% power added efficiency （PAE） at 4 GHz.

关键词： HEMT GaN MOCVD power device

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Long-term results of synovectomy in total knee arthroplasty:a prospective,randomized controlled trial

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Chinese Medical Journal 2023年第1期136卷 73-81页

作者： Weinan zeng Zeping Yu Simeng Wang Anjing Chen yiping zeng Qingjun Yang Yujuan Li Qi Li Zongke Zhou Department of Orthopedics Orthopedic Research InstituteWest China HospitalSichuan UniversityChengduSichuan 610041China Department of Orthopedics Chongqing General HospitalUniversity of Chinese Academy of SciencesChongqing 400014China Department of Radiology West China HospitalSichuan UniversityChengduSichuan 610041China

Background:Synovectomy has been introduced into total knee arthroplasty(TKA)with the aim of relieving pain and inflammation of the ***,there are no long-term,comparative data to evaluate the effect of synovectomy in *** study was aimed at assessing pain,function,and complications in patients undergoing synovectomy during TKA for osteoarthritis(OA)at long-term ***:This was a prospective randomized controlled trial of 42 consecutive patients who underwent staged bilateral *** undergoing the first-side TKA were allocated to receive TKA with or without synovectomy followed by a 3-month washout period and crossover to the other strategy for the opposite-side *** overall efficacy of both strategies was evaluated by determination of blood loss,the Knee Society score(KSS),and knee inflammation conditions during a 3-month postoperative *** postoperative pain,range of motion(ROM),and complications were sequentially evaluated to compare the two groups until 10 years after ***:At the 10-year follow-up,both groups had a similarly significantly improved ROM(114.88±9.84°vs.114.02±9.43°,t=0.221,P=0.815)and pain relief with no differences between the two groups(1.0[1.0]vs.1.0[1.5],U=789.500,P=0.613).Similar changes in total blood loss,KSS,and knee inflammation were found in both groups during 3 months postoperatively(P>0.05).Additionally,there was no significant difference regarding complications and satisfaction between the two groups(P>0.05).Conclusions:Synovectomy in conjunction with TKA for primary OA does not seem to provide any benefit regarding postoperative pain,ROM,and satisfaction during a 10-year *** addition,it may not result in more blood loss and increased incidence of long-term *** on our long-term findings,it should not be performed *** registration:Chinese Clinical Trial Registry,ChiCTR-INR-16008245;https://***/***?proj=13334.

关键词： Randomized controlled trial Synovectomy Clinical outcomes Total knee arthroplasty

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Producing deep UV-LEDs in high-yield MOVPE by improving AlN crystal quality with sputtered AlN nucleation layer

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Journal of Semiconductors 2017年第11期38卷 26-30页

作者： Zejie Du Ruifei Duan Tongbo Wei Shuo Zhang Junxi Wang Xiaoyan Yi yiping zeng Junxue Ran Jinmin Li Boyu Dong Semiconductor Lighting Technology Research and Development Center Institute of Semiconductors Chinese Academy of Sciences Beijing 100083 China Institute of Semiconductors University of Chinese Academy of Sciences Beijing 100083 China PVD Division North Microelectronics Beijing 100176 China

High-quality AlN layers with low-density threading dislocations are indispensable for high-efficiency deep ultraviolet light-emitting diodes（UV-LEDs）. In this work, a high-temperature AlN epitaxial layer was grown on sputtered AlN layer（used as nucleation layer, SNL） by a high-yield industrial metalorganic vapor phase epitaxy（MOVPE）. The full width half maximum（FWHM） of the rocking curve shows that the AlN epitaxial layer with SNL has good crystal quality. Furthermore, the relationships between the thickness of SNL and the FWHM values of（002） and（102） peaks were also studied. Finally, utilizing an SNL to enhance the quality of the epitaxial layer, deep UV-LEDs at 282 nm were successfully realized on sapphire substrate by the high-yield industrial MOVPE. The light-output power（LOP） of a deep UV-LED reaches 1.65 mW at 20 mA with external quantum efficiency of 1.87%. In addition, the saturation LOP of the deep UV-LED is 4.31 mW at an injection current of 60 mA. Hence, our studies supply a possible process to grow commercial deep UV-LEDs in high throughput industrial MOVPE, which can increase yield, at lower cost.

关键词： metalorganic vapor phase epitaxy aluminum nitride deep UV-LED

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