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Error Analysis for a Non-Monotone FEM for a Singularly Perturbed Problem with Two Small Parameters

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Advances in Applied Mathematics and Mechanics 2015年第2期7卷 196-206页

作者： Yanping Chen Haitao Leng li-bin liu School of Mathematical Sciences South China Normal UniversityGuangzhou 510631China Department of Mathematics and Computer Science Chizhou CollegeAnhui 247000China

In this paper,we consider a singularly perturbed convection-diffusion *** problem involves two small parameters that gives rise to two boundary lay-ers at two endpoints of the *** this problem,a non-monotoneﬁnite element methods is used.A priori error bound in the maximum norm is *** on the a priori error bound,we show that there exists Bakhvalov-type mesh that gives optimal error bound of O(N-2)which is robust with respect to the two perturbation *** results are given that conﬁrm the theoretical result.

关键词： Non-monotone singularly perturbed convection-diffusion Bakhvalov-type two s-mall parameters

A Large Gap of Atmospheric Pressure RF-DBD Glow Discharges in Ar and Mixed Gases

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Chinese Physics Letters 2011年第1期28卷 142-144页

作者： li bin CHEN Qiang liu Zhong-Wei WANG Zheng-Duo Laboratory of Plasma Physics and Alaterials Beijing Institute of Graphic Communication Beijing 102600

A large gap （up to 5.5 mm） between electrodes is acquired at Ar atmospheric pressure glow discharge （APGD） in radio frequency dielectric barrier discharge （RF-DBD）. The characteristics of I - V in single barrier... 详细信息

关键词： Plasma physics

Anomaly Detection System Based on Principal Component Analysis and Support Vector Machine

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Wuhan University Journal of Natural Sciences 2006年第6期11卷 1769-1772页

作者： li Zhanchun li Zhitang liu bin Network and Computing Center Huazhong University of Science and Technology Wuhan 430074 Hubei China

This article presents an anomaly detection system based on principal component analysis （PCA） and support vector machine （SVM）. The system first creates a profile defining a normal behavior by frequency-based scheme, and then compares the similarity of a current behavior with the created profile to decide whether the input instance is norreal or anomaly. In order to avoid overfitting and reduce the computational burden, normal behavior principal features are extracted by the PCA method. SVM is used to distinguish normal or anomaly for user behavior after training procedure has been completed by learning. In the experiments for performance evaluation the system achieved a correct detection rate equal to 92.2% and a false detection rate equal to 2.8%.

关键词： anomaly detection principal component analysis (PCA) support vector machine (SVM)

New high-strength Ti–Al–V–Mo alloy: from high-throughput composition design to mechanical properties

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International Journal of Minerals,Metallurgy and Materials 2019年第9期26卷 1151-1165页

作者： Di Wu Wan-lin Wang li-gang Zhang Zhen-yu Wang Ke-chao Zhou li-bin liu School of Metallurgy and Environment Central South UniversityChangsha 410083China School of Material Science and Engineering Central South UniversityChangsha 410083China Key Laboratory of Non-Ferrous Metallic Materials Science and Engineering Ministry of EducationChangsha 410083China State Key Laboratory of Powder Metallurgy Changsha 410083China

The high-throughput diffusion-multiple technique and thermodynamics databases were used to design new high-strength Ti alloys. The composition–microstructure–property relationships of the Ti64–xMo alloys were obtained. The phase fraction and composition of the α and β phases of the Ti64–xMo alloys were calculated using the Thermo-Calc software. After aging at 600℃, the Ti64–6 Mo alloy precipitated ultrafine α phases. This phenomenon was explained on the basis of the pseudo-spinodal mechanism by calculating the Gibbs energy curves of the α and β phases of the Ti64–xMo alloys at 600℃. Bulk forged Ti64–6 Mo alloy exhibited high strength and moderate plasticity after α/β-phase-field solution treatment plus aging. The tensile properties of the alloy were determined by the size and morphology of the primary and secondary α phases and by the β grain size.

关键词： high-strength titanium alloy Ti–6Al–4V–xMo diffusion multiple Thermo-Calc microstructure and mechanical properties

Pseudo-spinodal mechanism approach to designing a near-βhigh-strength titanium alloy through high-throughput technique

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Rare Metals 2021年第8期40卷 2099-2108页

作者： li-Gang Zhang Jing-Lu Tang Zhen-Yu Wang Jing-Ya Zhou Di Wu li-bin liu Patrick J.Masset School of Material Science and Engineering Central South UniversityChangsha410083China Key Laboratory of Nonferrous Metallic Materials Science and Engineering Ministry of EducationChangsha410083China State Key Laboratory of Powder Metallurgy Changsha410083China Faculty of Mechanical Engineering Koszalin University of TechnologyKoszalin75-453Poland

The main reason for the high strength in near-βtitanium alloys is the ultrafine precipitation of the acicular secondary a phase in theβ*** purpose of this study is to use the pseudo-spinodal mechanism to obtain the ultrafine a phase for the design of a new high-strength near-γtitanium *** calculations and TC21-(TC21+15 Mo)diffusion couple composition gradient experiments were used to demonstrate that TC21+3 Mo alloy can undergo a pseudo-spinodal decomposition to obtain the ultrafine a phase,resulting in a high-strength *** adjusting the heat treatment process to obtain a bimodal microstructure,the alloy exhibits a good balance between ultimate tensile strength(1351 MPa)and plasticity(8.5%strain).Thus,it was demonstrated that the pseudospinodal mechanism combined with a high-throughput diffusion couple technique is an effective method for designing high-strength titanium alloys.

关键词： High-strength titanium alloy TC21+xMo Diffusion couple Pseudo-spinodal mechanism Microstructure and mechanical properties

Preparation and magnetic hardening of low Ti content(Sm,Zr)(Fe,Co,Ti)_(12) magnets by rapid solidification non-equilibrium method

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Chinese Physics B 2024年第9期33卷 576-580页

作者： Xing-Feng Zhang li-bin liu Yu-Qing li Dong-Tao Zhang Wei-Qiang liu Ming Yue College of Materials Science and Engineering Key Laboratory of Advanced Functional MaterialsMinistry of Education of ChinaBeijing University of TechnologyBeijing 100124China

The Sm–Zr–Fe–Co–Ti quinary-alloys with ThMn12 structure has attracted wide attention for ultra-high intrinsic magnetic properties,showing potentiality to be developed into rare-earth permanent *** Ti element in alloys is crucial for phase stability and magnetic properties,and lower Ti content can increase intrinsic magnetic properties but reduce phase *** this study,the 1:12 single-phase melt-spun ribbons with low Ti content was successfully prepared using a rapid solidification non-equilibrium method for the Sm1.1Zr_(0.2)Fe_(9.2)Co_(2.3)Ti_(0.5) ***,this non-equilibrium ribbon did not achieve good magnetic hardening due to the uneven microstructure and ***,annealing was carried out to eliminate micro-strain and homogenize microstructure,therefore,remanence and coercivity were significantly improved even the precipitation of a small amount of a-Fe phase which were not conducive to *** remanence of 86.1 emu/g and coercivity of 151 kA/m was achieved when annealing at 850℃ for 45 *** hot pressing,under the action of high temperature and pressure,a small portion of ThMn12 phases in the magnet decompose into Sm-rich phases and a-Fe,while remanence of 4.02 kGs(1 Gs=10^(-4) T),and coercivity of 1.12 kOe(1 Oe=79.5775 A·m^(-1))were still *** findings can provide reference for exploring practical permanent magnets made of 1:12 type quinary-alloys.

关键词： magnetic materials (Sm Zr)(Fe Co Ti)_(12) magnets nanocrystalline magnet microstructure

Integrating machine learning and CALPHAD method for exploring low-modulus near-β-Ti alloys

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Rare Metals 2024年第1期43卷 309-323页

作者： Hao Zou Yue-Yan Tian li-Gang Zhang Ren-Hao Xue Zi-Xuan Deng Ming-Ming Lu Jian-Xin Wang li-bin liu School of Computer Science and Engineering Central South UniversityChangsha 410083China School of Materials Science and Engineering Central South UniversityChangsha 410083China State Key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China

Traditional theoretical and empirical calculation methods can guide the design of β-and metastable β-alloys for bio-titanium. However, it is still difficult to obtain novel near-β-Ti alloys with low modulus. This study developed a method that combines machine learning with calculation of phase diagrams(CALPHAD) to facilitate the design of near-β-Ti alloys. An elastic modulus database of Ti–Nb–Zr–Mo–Ta–Sn system was constructed first, and then three features(the electron to atom ratio, mean absolute deviation of atom mass, and mean electronegativity) were selected as the key factors of modulus by performing a three-step feature selection. With these features, a highly accurate model was built for predicting the modulus of near-β-Ti alloys. To further ensure the accuracy of modulus prediction, machine learning with the elastic constants calculated was leveraged by CALPHAD database. The root mean square error of the well-trained model can be as low as 6.75 GPa. Guided by the prediction of machine learning and CALPHAD, three novel near-β-Ti alloys with elastic modulus below 50 GPa were successfully designed in this study. The best candidate alloy(Ti–26Nb–4Zr–4Sn–1Mo–Ta) exhibits an ultra-low modulus(36.6 GPa) after cold rolling with a thickness reduction of 20%. Our method can greatly save time and resources in the development of novel Ti alloys, and experimental verifications have demonstrated the reliability of this method.

关键词： Near-β-Ti alloy Machine learning Calculation of phase diagram Low-modulus alloy Feature selection

Fatal hemolysis due to clostridium perfrigens blood stream infection

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Chinese Medical Journal 2013年第18期126卷 3572-3573页

作者： CAO bin SU ling-ling li bin-bin liu Ying-mei Department of Infectious Diseases and Clinical Microbiology Beijing Chao-Yang Hospital Capital Medical University Beijing Institute of Respiratory Medicine Beijing 100020 China

Here we reported a 59-year-old woman with diabetes who was found to have massive hemolysis associatedwith clostridium （C.） perfringens blood stream infection. She died 13 hours after admission in spite of aggressive treatment. The lady referred to our hospital with high fever, chills, body ache and right hypochondriac pain for 1 day. Physical examination revealed a temperature of 39, heart rate of 110 beats/min, blood pressure of 101/69 mmHg, and a respiratory rate of 25 breaths/min. Pulse oximetry was 94% on room air. Chest auscultation revealed good air movement without rales. Tenderness of right upper abdomen was found. Abnormal laboratory results included white blood cell （WBC） count of 20x109/L with 90.9% neutrophils,

关键词： hemolysis sepsis blood stream infection bacteremia clostridium perfringens

Dynamic Simulation and Opening Bouncing Analysis of Vacuum Circuit Breaker with Permanent Magnetic Actuator

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高电压技术 2013年第7期39卷 1772-1777页

作者： liN Xin CAO Chen li bin liu Yang XU Jianyuan School of Electric Engineering Shenyang University of Technology Shenyang 110023 China

In order to research the dynamic characteristics of circuit breaker(CB) in opening process,taking a 12kV vacuum circuit breaker(VCB) with permanent magnetic actuator as the example,a dynamic model of the VCB is established based on the virtual prototype technology,and dynamic equations of the model are *** and experiment are carried out on the VCB of both opening and closing *** simulative opening time and closing time are 39.5ms and 54.6ms *** factors of opening bouncing and their effect principles are analyzed through dynamic simulations of opening bouncing *** results indicate that the increase in the stiffness coefficient of contact spring limits the opening bouncing;meanwhile increases in the preload of contact spring and the mass of shaft can enlarge the opening bouncing.

关键词：断路器动态模拟分析弹簧关闭时间