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STABILITY AND CONVERGENCE ANALYSIS OF SECOND-ORDER SCHEMES FOR A DIFFUSE INTERFACE MODEL WITH peng-ROBINSON EQUATION OF STATE

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Journal of Computational Mathematics 2017年第6期35卷 737-765页

作者： Qiujin peng Zhonghua Qiao Shuyu Sun Institute for Mathematical Sciences Renmin University of China Beijing 100872 China Department of Applied Mathematics The Hong Kong Polytechnic University Hung Horn Hong Kong Division of Physical Sciences and Engineering King Abdullah University of Science and Technology Thuwal 23955-6900 Kingdom of Saudi Arabia

In this paper, we present two second-order numerical schemes to solve the fourth order parabolic equation derived from a diffuse interface model with peng-Robinson Equation of state （EOS） for pure substance. The mass conservation, energy decay property, unique solvability and L~ convergence of these two schemes are proved. Numerical results demon- strate the good approximation of the fourth order equation and confirm reliability of these two schemes.

关键词： Diffuse interface model Fourth order parabolic equation Energy stability,Convergence.

Model test of the mechanism underpinning water-and-mud inrush disasters during tunnel excavation in sandstone and slate interbedded Presinian strata

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2022年第11期23卷 882-899页

作者： peng XU Peng Peng Rong-hua WEI Zhi-qiang ZHANG School of Civil Engineering Southwest Jiaotong UniversityChengdu 610031China Key Laboratory of Transportation Tunnel Engineering Ministry of EducationSouthwest Jiaotong UniversityChengdu 610031China

Water-and-mud inrush disasters have become a major challenge in underground engineering for the construction of tunnels in sandstone and slate interbedded Presinian strata.Disaster prediction and prevention rely in part on realistic modeling and observation of the disaster process,as well as the identification and examination of the underlying mechanisms.Based on the geological conditions and the historical records of the Xinping Tunnel on the China–Laos Railway,an engineering geological model of the water-and-mud inrush was established.A physical model test that accurately reproduced water-and-mud inrush during tunnel excavation in sandstone and slate interbedded strata was also carried out.Then,testing was conducted that examined the stress and strain,seepage pressure,and high-leakage flow of the surrounding rock.The results indicated that the water-and-mud inrush proceeded through three stages:seepage stage,high-leakage flow stage,and attenuation stage.In essence,the disaster was a catastrophic process,during which the water-resistant stratum was reduced to a critical safety thickness,a water-inrush channel formed,and the water-resistant stratum gradually failed under the influence of excavation unloading and in situ stress–seepage coupling.Parameters such as the stress and strain,seepage pressure,and flow of the surrounding rock had evident stage-related features during water-and-mud inrush,and their variation indicated the formation,development,and evolution of the disaster.As the tunnel face advanced,the trend of the stress–strain curve of the surrounding rock shifted from sluggish to rapid in its speed of increase.The characteristics of strain energy density revealed the erosion and weakening effect of groundwater on the surrounding rock.The seepage pressure and the thickness of the water-resistant stratum had a positive linear relationship,and the flow and thickness a negative linear relationship.There was a pivotal point at which the seepage pressure changed from high to low and the flow shifted from low

关键词： Water-and-mud inrush Sandstone and slate interbedded Presinian strata Model test Evolution law Thickness of water-resistant stratum Inducing mechanism

彭清华益气养阴活血利水法治疗视网膜脱离术后经验

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中华中医药杂志 2020年第7期35卷 3433-3436页

作者：蒋鹏飞彭俊彭清华湖南中医药大学长沙410208 湖南中医药大学第一附属医院长沙410007 湖南中医药大学第一附属医院国家眼底病中医医疗中心长沙410007 中医药防治眼耳鼻咽喉疾病湖南省重点实验室长沙410208

文章总结了彭清华教授运用益气养阴、活血利水法治疗视网膜脱离术后的经验,在组方特色上阐述了彭清华教授将“水血同治”理论灵活运用于眼科专科辨证体系中的临床思路,以益气养阴、活血利水的复明片治疗视网膜脱离术后;在用药特色上阐... 详细信息

文章总结了彭清华教授运用益气养阴、活血利水法治疗视网膜脱离术后的经验,在组方特色上阐述了彭清华教授将“水血同治”理论灵活运用于眼科专科辨证体系中的临床思路,以益气养阴、活血利水的复明片治疗视网膜脱离术后;在用药特色上阐述了彭清华教授擅于利用黄芪益气活血之能、虫类药无所不达之性、车前子利水明目之功治疗视网膜脱离术后,取得较好的临床疗效。

关键词：彭清华视网膜脱离术后名医经验益气养阴活血利水

Laser Erasing and Rewriting of Flexible Copper Circuits

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Nano-Micro Letters 2021年第11期13卷 409-420页

作者： Xingwen Zhou Wei Guo Peng Peng School of Mechanical Engineering and Automation Beihang UniversityBeijing 100191People’s Republic of China Department of Mechanical and Mechatronics Engineering Centre for Advanced Materials JoiningUniversity of WaterlooWaterlooON N2L 3G1Canada

Integrating construction and reconstruction of highly conductive structures into one process is of great interest in developing and manufacturing of electronics,but it is quite challenging because these two involve contradictive additive and subtractive processes.In this work,we report an all-laser mask-less processing technology that integrates manufacturing,modifying,and restoring of highly conductive Cu structures.By traveling a focused laser,the Cu patterns can be fabricated on the flexible substrate,while these as-written patterns can be selectively erased by changing the laser to a defocused state.Subsequently,the fresh patterns with identical conductivity and stability can be rewritten by repeating the writing step.Further,this erasing–rewriting process is also capable of repairing failure patterns,such as oxidation and cracking.Owing to the high controllability of this writing–erasing–rewriting process and its excellent reproducibility for conductive structures,it opens a new avenue for rapid healing and prototyping of electronics.

关键词： Laser writing Laser erasing Copper electrodes Electronic repairing Flexible electronics

In situ strength profiles along two adjacent vertical drillholes from digitalization of hydraulic rotary drilling

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Journal of Rock Mechanics and Geotechnical Engineering 2023年第1期15卷 146-168页

作者： Xuefan Wang Peng Peng Zhigang Shan Zhongqi Yue Department of Civil Engineering The University of Hong KongHong KongChina PowerChina Huadong Engineering Corporation Limited HangzhouChina

Drilling speed and associated analyses from factual field data of hydraulic rotary drilling have not been fully utilized.The paper provides the reference and comparison for the utilization of drilling information from two adjacent vertical drillholes that were formed with the same hydraulic rotary drilling machine and bit.The analysis of original factual data is presented to obtain the constant drilling speed during net drilling process.According to the factual data along two adjacent drillholes,the digitalization results respectively include 461 linear zones and 210 linear zones with their constant drilling speeds and associated drilling parameters.The digitalization results can accurately present the spatial distributions and interface boundaries of drilled geomaterials and the results are consistent with the paralleled site loggings.The weighted average drilling speeds from 2.335 m/min to 0.044 m/min represent 13 types of drilled geomaterials from soils to hard rocks.The quantitative relation between drilling speed and strength property is provided.The digitalization results can statistically profile the basic strength quality grades of III to VI from soils to hard rocks.The thickness distributions of four strength quality grades are presented for each individual type of geomaterials along two drillholes.In total,50.2%of geomaterials from drillhole A are grade IV and 57.4%of geomaterials from drillhole B are grade III.The digitalization results can offer an accurate and cost-effective tool to quantitatively describe the spatial distribution and in situ strength profile of drilled geomaterials in the current drilling projects.

关键词： Drilling process monitoring(DPM) Hydraulic rotary coring process Constant drilling speed Coring-resistant strength

Analysis on phase selection and microstructure evolution in directionally solidified Zn-Al-Mg-Ce alloy

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China Foundry 2023年第4期20卷 347-355页

作者： Ji-peng Li De-gao Qiao Shi-wen Dong Peng Peng Xian-tao Yan Xu-dong Zhang Gansu Jiu Steel Group Hongxing Iron and Steel Co. Ltd.Jiayuguan 735199GansuChina School of Materials and Energy Lanzhou UniversityLanzhou 730000China School of Physics and Electronic Information Engineering Qinghai Normal UniversityXining 810016QinghaiChina

In the process of hot-dip Zn-Al-Mg alloy coating,the plating solution dissipates heat in the direction perpendicular to the steel plate,which is considered to be a process of directional solidification.To understand the relationship between microstructure and cooling rate of Zn-Al-Mg alloys,both the phase constitution and microstructure characteristic length scales of Zn-9.5Al-3Mg-0.01Ce(wt.%)alloy were investigated by the directional solidification experiments at different growth velocities(V=40,80,160,250μm·s^(-1)).The experimental results show that the microstructure of directionally solidified Zn-9.5Al-3Mg-0.01Ce alloy is composed of primary Al dendrites and(Zn-Al-Mg2Zn11)ternary eutectics at the growth velocities ranging from 40 to 250μm·s^(-1).The primary Al dendrites are aligned regularly along the growth direction,accompanied with obvious secondary dendrites.The relationship between the microstructure length scale and the thermal parameters of solidification is obtained:λ1=374.66V-0.383,andλ2=167.5V-0.563(λ1is the primary dendrite arm spacing,andλ2 is the secondary dendrit arm spacing).In addition,through the interface response function(IRF)and the nucleation and constitutional undercooling(NCU),the phase selection of Zn-9.5Al-3Mg-0.01Ce is obtained:(Zn+Al+Mg2Zn11)ternary eutectics in the Zn-9.5Al-3Mg-0.01Ce alloy will be replaced by ternary eutectics(Zn+Al+MgZn2)when the growth rate is lower than 7.53μm·s^(-1).

关键词： Zn-Al-Mg alloy directional solidification microstructure length scale phase selection

基于优化VMD与改进阈值降噪的滚动轴承早期故障特征提取

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振动与冲击 2021年第13期40卷 146-153页

作者：陈鹏赵小强兰州理工大学电气工程与信息工程学院兰州730050 甘肃省工业过程先进控制重点实验室兰州730050 兰州理工大学国家级电气与控制工程实验教学中心兰州730050

针对复杂工况和强背景噪声干扰下,滚动轴承早期故障信号微弱导致故障特征难以提取的问题。提出了优化变分模态分解(VMD)与改进阈值降噪的滚动轴承故障特征提取方法。首先,通过鲸鱼优化算法(WOA)优化VMD实现振动信号的自适应分解,建立了L... 详细信息

针对复杂工况和强背景噪声干扰下,滚动轴承早期故障信号微弱导致故障特征难以提取的问题。提出了优化变分模态分解(VMD)与改进阈值降噪的滚动轴承故障特征提取方法。首先,通过鲸鱼优化算法(WOA)优化VMD实现振动信号的自适应分解,建立了L-峭度和相关系数的最优模态分量选取准则;然后对选取的最佳分量进行改进阈值降噪;最后,对降噪后的信号进行希尔伯特包络谱分析实现故障特征频率的提取。在仿真信号和美国西储大学工程数据集上,对提出的方法进行了验证,同时与Teager能量算子降噪的方法和基于包络熵准则的优化方法进行了对比,结果表明提出的方法效果更优。

关键词：特征提取故障诊断鲸鱼优化算法(WOA) 变分模态分解(VMD) 阈值降噪

Regulating Thermogalvanic Effect and Mechanical Robustness via Redox Ions for Flexible Quasi‑Solid‑State Thermocells

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Nano-Micro Letters 2022年第5期14卷 153-167页

作者： Peng Peng Jiaqian Zhou Lirong Liang Xuan Huang Haicai Lv Zhuoxin Liu Guangming Chen College of Materials Science and Engineering Shenzhen UniversityShenzhen 518055People’s Republic of China College of Physics and Optoelectronic Engineering Shenzhen UniversityShenzhen 518060People’s Republic of China

The design of power supply systems for wearable applications requires both flexibility and durability.Thermoelectrochemical cells(TECs)with large Seebeck coefficient can efficiently convert lowgrade heat into electricity,thus having attracted considerable attention in recent years.Utilizing hydrogel electrolyte essentially addresses the electrolyte leakage and complicated packaging issues existing in conventional liquid-based TECs,which well satisfies the need for flexibility.Whereas,the concern of mechanical robustness to ensure stable energy output remains yet to be addressed.Herein,a flexible quasisolid-state TEC is proposed based on the rational design of a hydrogel electrolyte,of which the thermogalvanic effect and mechanical robustness are simultaneously regulated via the multivalent ions of a redox couple.The introduced redox ions not only endow the hydrogel with excellent heat-to-electricity conversion capability,but also act as ionic crosslinks to afford a dual-crosslinked structure,resulting in reversible bonds for effective energy dissipation.The optimized TEC exhibits a high Seebeck coefficient of 1.43 mV K−1 and a significantly improved fracture toughness of 3555 J m^(−2),thereby can maintain a stable thermoelectrochemical performance against various harsh mechanical stimuli.This study reveals the high potential of the quasi-solid-state TEC as a flexible and durable energy supply system for wearable applications.

关键词： Thermocells Thermoelectric Flexible energy devices Wearable applications Hydrogel electrolytes

Spiral Vector Modeling of Brushless Doubly-fed Induction Machines with Short-circuited Rotor Windings

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Chinese Journal of Electrical Engineering 2021年第3期7卷 29-41页

作者： peng Han Ming Cheng Zhiwei Zhang Peng Peng Ansys Inc.San JoseCA 95134USA School of Electrical Engineering Southeast UniversityNanjing 210096China Department of ECE The Ohio State UniversityColumbusOH 43210USA Milwaukee Electric Tool Corporation MilwaukeeWI 53005USA

A unified spiral vector model is presented that can be used to assist the finite element method-based performance analysis of brushless doubly-fed induction machines with various short-circuited rotor windings.Specifically,magnet-free brushless doubly-fed induction machines working in doubly-fed or singly-fed synchronous mode are investigated.A dynamic model in spiral vector notation is developed,based on which the torque-angle and power-angle characteristics are derived.It is shown that the investigated brushless machines are equivalent to a traditional non-salient-pole synchronous machine with brushes.By introducing a conversion factor,they can also be analyzed with methods similar to the conventional phasor theory.A comparison is made between the brushless doubly-fed induction machine and non-salient-pole wound-field synchronous machine with brushes,revealing that the performance of the brushless machine degrades faster when the laminated core is saturated.A scaled-down prototype is tested to validate the effectiveness of the theoretical analysis.

关键词： AC machine brushless machine modeling performance evaluation synchronous machine