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Computing top eigenpairs of Hermitizable matrix

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Frontiers of Mathematics in China 2021年第2期16卷 345-379页

作者： Mu-fa CHEN Zhi-Gang JIA Hong-Kui PANG Research Institute of Mathematical Science Jiangsu Normal UniversityXuzhou 221116China School of Mathematical Sciences Beijing Normal UniversityBeijing 100875China Laboratory of Mathematics and Complex Systems(Beijing Normal University) Ministry of EducationBeijing 100875China School of Mathematics and Statistics Jiangsu Normal UniversityXuzhou 221116China

The top eigenpairs at the title mean the maximal, the submaximal, or a few of the subsequent eigenpairs of an Hermitizable matrix. Restricting on top ones is to handle with the matrices having large scale, for which only little is known up to now. This is different from some mature algorithms, that are clearly limited only to medium-sized matrix for calculating full spectrum. It is hoped that a combination of this paper with the earlier works, to be seen soon, may provide some effective algorithms for computing the spectrum in practice, especially for matrix mechanics.

关键词： Hermitizable Householder transformation birth-death matrix isospectral matrices top eigenpairs algorithm

SPECTRAL AND PSEUDOSPECTRAL APPROXIMATIONS IN TIME FOR PARABOLIC EQUATIONS

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Journal of Computational Mathematics 1998年第2期16卷 107-120页

作者： fa-yong Zhang (Department of Mathematics, Heilongjiang University, Harbin 150080, China) Heilongjiang Univ Dept Math Harbin 150080 Peoples R China

In this paper, spectral and pseudospectral methods are applied to both time and space variables for parabolic equations. Spectral and pseudospectral schemes are given, and error estimates are obtained for approximate ... 详细信息

关键词： spectral approximation pseudospectral approximation parabolic equation error estimate

Application of response surface methodology in medium optimization for pyruvic acid production of Torulopsis glabrata TP19 in batch fermentation

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2007年第2期8卷 98-104页

作者： ZHANG Jian GAO Nian-fa Tianjin Key Lab of lndustrial Microbiology College of Biotechnology Tianjin University of Science and Technology Tianjin 300457 China

Response surface methodology (RSM) was used to optimize the fermentation medium for enhancing pyruvic acid production by Torulopsis glabrata TP19. In the first step of optimization, with Plackett-Burman design, ammonium sulfate, glucose and nicotinic acid were found to be the important factors affecting pyruvic acid production significantly. In the second step, a 23 full factorial central composite design and RSM were applied to determine the optimal concentration of each significant variable. A second-order polynomial was determined by the multiple regression analysis of the experimental data. The optimum values for the critical components were obtained as follows: ammonium sulfate 0.7498 (10.75 g/L), glucose 0.9383 (109.38 g/L) and nicotinic acid 0.3633 (7.86 mg/L) with a predicted value of maximum pyruvic acid production of 42.2 g/L. Under the optimal conditions, the practical pyruvic acid production was 42.4 g/L. The determination coefficient (R2) was 0.9483, which ensures adequate credibility of the model. By scaling up fermentation from flask to jar fermentor, we obtained promising results.

关键词： Response surface methodology Torulopsis glabrata Pyruvic acid Fermentation Medium optimization

Intelligent casting:Empowering the future foundry industry

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China Foundry 2024年第5期21卷 409-426页

作者： Jin-wu Kang Bao-lin Liu Tao Jing Hou-fa Shen School of Materials Science and Engineering Key Laboratory for Advanced Materials Processing TechnologyTsinghua UniversityBeijing 100084China

Emerging technological advances are reshaping the casting sector in latest *** technology is evolving towards intelligent casting paradigm that involves automation,greenization and intelligentization,which attracts more and more attention from the academic and industry *** this paper,the main features of casting technology were briefly summarized and forecasted,and the recent developments of key technologies and the innovative efforts made in promoting intelligent casting process were ***,the technical visions of intelligent casting process were also put *** key technologies for intelligent casting process comprise 3D printing technologies,intelligent mold technologies and intelligent process control *** future,the intelligent mold that derived from mold with sensors,control devices and actuators will probably incorporate the Internet of Things,online inspection,embedded simulation,decision-making and control system,and other technologies to form intelligent cyber-physical casting system,which may pave the way to realize intelligent *** is promising that the intelligent casting process will eventually achieve the goal of real-time process optimization and full-scale control,with the defects,microstructure,performance,and service life of the fabricated castings can be accurately predicted and tailored.

关键词： intelligent casting 3D printing intelligent mold process control cyber-physical casting system embedded simulation

Effects of diamond particle size on microstructure and properties of diamond/Al-12Si composites prepared by vacuum-assisted pressure infiltration

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China Foundry 2024年第4期21卷 360-368页

作者： Jia-ping Fu Can-xu Zhou Guo-fa Mi Yuan Liu School of Materials Science and Engineering Henan Polytechnic UniversityJiaozuo 454100HenanChina School of Materials Science and Engineering Tsinghua UniversityBeijing 100084China Key Laboratory for Advanced Materials Processing Technology Ministry of EducationBeijing 100084China

Diamond/aluminium composites have attracted attention in the field of thermal management of electronic packaging for their excellent *** order to solve the interfacial problem between diamond and aluminium,a novel process combining pressure infiltration with vacuum-assisted technology was proposed to prepare diamond/aluminum *** effect of diamond particle size on the microstructure and properties of the diamond/Al-12Si composites was *** results show that the diamond/Al-12Si composites exhibit high relative density and a uniform *** thermal conductivity and coefficient of thermal expansion increase with increasing particle size,while the bending strength exhibits the opposite *** the average diamond particle size increases from 45μm to 425μm,the thermal conductivity of the composites increases from 455 W·m^(-1)·K^(-1)to 713 W·m^(-1)·K^(-1)and the coefficient of thermal expansion increases from 4.97×10^(-6)K^(-1)to 6.72×10^(-6)K^(-1),while the bending strength decreases from 353 MPa to 246 *** research demonstrates that high-quality composites can be prepared by the vacuum-assisted pressure infiltration process and the thermal conductivity of the composites can be effectively improved by increasing the diamond particle size.

关键词： diamond/aluminum composites thermal conductivity electronic packaging vacuum-assisted pressure infiltration

Sulphidization flotation for recovery of lead and zinc from oxide-sulfide ores

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中国有色金属学会会刊：英文版 2005年第5期15卷 1138-1144页

作者： fa Keqing Jan D.Miller 姜涛李光辉 Department of Metallurgical Engineering University of Utah Salt Lake City Utah 84112 USA School of Resources Processing & Bioengineering Central South University Changsha 410083 China

A new flowsheet was developed to recover the valuable minerals from oxide or oxide-sulfide ores of lead and zinc. The flowsheet consisted of flotation of sulfide minerals, desliming and sulphidization-flotation of oxide minerals. The corresponding reagent system and techniques to the flowsheet were investigated. Batch and continuous tests show that the dosage of sodium sulfide, temperature, and collector type are main affecting factors on the recovery of smithsonite and cerussite. For the flotation of cerussite, there is an appropriate dosage of sodium sulfide at which the recovery reaches its maximum value. The required sodium sulfide for smithsonite flotation is higher than that for cerussite and the recovery of smithsonite flotation increases with the dosage of sodium sulfide at low level and becomes insensitive at high dosage. The appropriate temperature for smithsonite and cerussite flotation is found to be 2540℃. Amines are found to be the effective collectors for the flotation of smithsonite after sulphidization. Investigation also shows that desliming prior to sulphidization-flotation is essential to the effective recovery of smithsonite and cerussite, and the desliming process of two-stage hydrocyclon is well feasible and effective for the treatment of lead-zinc oxide ores. A further treatment on the cerussite flotation concentrate by shaking table is proposed to obtain higher lead grade.

关键词：锌氧化物硫化物矿石浮选工艺

Creep rupture behavior and microstructural evolution of modified 9Cr-1Mo heat-resistant steel

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Journal of Iron and Steel Research International 2018年第12期25卷 1303-1310页

作者： fa-cai Ren He Wang Xiao-ying Tang Fei Chen Shanghai Institute of Special Equipment Inspection and Technical Research Shanghai 200062China Capital Aerospace Machinery Corporation Limited Beijing 100076China National Engineering Research Centre of Die &Mold CAD Shanghai Jiao Tong UniversityShanghai 200030China

High-temperature creep rupture behavior of modified 9Cr-lMo steel used for steam cooler was investigated at temperature of 838 and 923 K and stress ranging from 100 to 250 *** on the analysis of creep rate-time curves,it is found that the creep rupture life decreases with the increase in the applied stress and *** creep damage tolerance factor has been identified as a value of *** the normalized and tempered condition,the studied steel shows typical martensitic microstructure with Cr-rich M23C6 and Nb-or V-rich MX ***,the Laves phase has been found along the grain *** fracture morphology characterized by field emission scanning electron microscope is adopted to reveal the creep failure *** investigated results indicate the occurrence of the transgranular fracture under all the creep test conditions.

关键词： Creep rupture behavior Modified 9Cr-1Mo steel Microstructural evolution Fractography

An INS/GNSS integrated navigation in GNSS denied environment using recurrent neural network

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Defence Technology（防务技术） 2020年第2期16卷 334-340页

作者： Hai-fa Dai Hong-wei Bian Rong-ying Wang Heng Ma Navigation Engineering Lab Naval Engineering UniversityWuhanCO430033China

In view of the failure of GNSS signals,this paper proposes an INS/GNSS integrated navigation method based on the recurrent neural network(RNN).This proposed method utilizes the calculation principle of INS and the memory function of the RNN to estimate the errors of the INS,thereby obtaining a continuous,reliable and high-precision navigation *** performance of the proposed method is firstly demonstrated using an INS/GNSS simulation ***,an experimental test on boat is also conducted to validate the performance of the *** results show a promising application prospect for RNN in the field of positioning for INS/GNSS integrated navigation in the absence of GNSS signal,as it outperforms extreme learning machine(ELM)and EKF by approximately 30%and 60%,respectively.

关键词： Inertial navigation system(INS) Global navigation satellite system(GNSS) Integrated navigation Recurrent neural network(RNN)

Cyclic oxidation behavior of NiCoCrAlY/YSZ@Ni composite coatings fabricated by laser cladding

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Journal of Iron and Steel Research International 2020年第10期27卷 1226-1235页

作者： Hai-zhong Zheng Pei-feng Zhou Gui-fa Li Ping Peng School of Materials Science and Engineering Beihang UniversityBeijing 100191China School of Material Science and Engineering Nanchang Hangkong UniversityNanchang 330063JiangxiChina School of Material Science and Engineering Hunan UniversityChangsha 410082HunanChina

Composite coating on GH4169 alloy is prepared by laser cladding yttria-stabilized zirconia(YSZ)@Ni core-shell powdersmixed with NiCoCrAlY alloy *** cyclic oxidation behavior of the coatings,especially the growth process of theoxide layer,is investigated based on experimental research and first-principle *** results indicate that theoxidation resistance of coated GH4169 alloy is beer than that of uncoated GH4169 *** coating has three layers:acellular dendrite outer layer,a planar YSZ interlayer,and an inner layer composed of Cr2O3 formed during laser *** oxidation at 1000 and 1050℃,as the oxidation time increases,the cellular dendrite outer layer becomes thicker,andthe planar yttria-stabilized zirconia interlayer becomes *** the planar interlayer and Cr2O3 inner layer,and Al2O3 layer ***,cracks formed in the intcrface of Al2O3/Cr2O3 owing to thcir weak interface strength,whichled to the failure of the composite coating.

关键词： Laser cladding NiCoCrAlY/YSZ@Ni composite coating Cyelic oxidation-Oxidation mechanism.Crack nucleation