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Dependence of Plastic Stability on 3D Interface Layer in Nanolaminated materials

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Acta Metallurgica Sinica(English Letters) 2022年第11期35卷 1759-1764页

作者： Shuimiao Jiang Lichen Bai Qi An Zhe Yan Weiming Li Kaisheng Ming Shijian Zheng Tianjin Key laboratory of materials Laminating Fabrication and Interface Control Technology School of Materials Science and EngineeringHebei Universityof TechnologyTianjin 300130China State Key laboratory of reliability and Intelligence of Electrical Equipment Hebei University of TechnologyTianjin 300130China

The nanolaminated materials generally exhibit poor plasticity due to the fast onset of shear *** interface structure is an eff ective approach for enhancing plasticity via postponing or suppressing the shear ***,we introduce 4 nm thick CuNb 3D amorphous interface layers and Nb 3D crystalline interface layers in Cu nanolaminated materials,*** situ micro-pillar compression tests show that samples with crystalline interface layers exhibit shear instability,while the samples with amorphous interface layers display uniform *** the plastic deformation of the singlecrystal crystalline interface layer is anisotropic,except for well-aligned slip systems,dislocations on other slip systems have a poor ability to transmit the 3D crystalline interface layer,leading to localized dislocations pileups and shear *** contrast,the amorphous interface layer which is plastically isotropic accommodates dislocations from arbitrary slip systems of the matrix,which can alleviate the stress concentrations at the interface,and thus suppresses the shear instability.

关键词： Multilayers Interface Plastic deformation Dislocation Amorphous interface

Theoretical predictions on α-decay properties of some unknown neutrondeficient actinide nuclei using machine learning

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Chinese Physics C 2022年第2期46卷 79-89页

作者： Ziyi Yuan Dong Bai Zhongzhou Ren Zhen Wang School of Physics Science and Engineering Tongji UniversityShanghai 200092China Key laboratory of Advanced Micro-structure materials Ministry of EducationShanghai 200092China

Neutron-deficient actinide nuclei provide a valuable window to probe heavy nuclear systems with large proton-neutron ratios. In recent years, several new neutron-deficient Uranium and Neptunium isotopes have been observed using α-decay spectroscopy [Z. Y. Zhang et al., Phys. Rev. Lett. 122, 192503(2019);L. Ma et al., Phys. ***. 125, 032502(2020);Z. Y. Zhang et al., Phys. Rev. Lett. 126, 152502(2021)]. In spite of these achievements,some neutron-deficient key nuclei in this mass region are still unknown in experiments. Machine learning algorithms have been applied successfully in different branches of modern physics. It is interesting to explore their applicability in α-decay studies. In this work, we propose a new model to predict the α-decay energies and half-lives within the framework based on a machine learning algorithm called the Gaussian process. We first calculate the α-decay properties of the new actinide nucleus 214 U. The theoretical results show good agreement with the latest experimental data, which demonstrates the reliability of our model. We further use the model to predict the α-decay properties of some unknown neutron-deficient actinide isotopes and compare the results with traditional models. The results may be useful for future synthesis and identification of these unknown isotopes.

关键词： alpha decay machine learning actinide nuclei

Design and Performance Analysis of Permanent Magnet Claw Pole Machine with Hybrid Cores

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CES Transactions on Electrical Machines and systems 2023年第3期7卷 275-283页

作者： Chengcheng Liu Zheng Chao Shaopeng Wang Youhua Wang IEEE State Key laboratory of reliability and Intelligence of Electrical Equipment Hebei University of Technology and Key Laboratory of Electromagnetic Field and Electrical Apparatus Reliability of Hebei ProvinceHebei University of TechnologyTianjin 300130China

Permanent magnet claw pole machine(PMCPM) is a special kind of transverse flux permanent magnet machine. Compared with other electrical machines, it has the advantages of high torque density and high efficiency for high speed operation. However, because of its complex irregular structure, the manufacturing process using silicon sheets is complicated. Soft magnetic composite material(SMC) is manufactured by powder metallurgy technology, which can produce various shapes of stator core structures, so it is easier to produce various irregular shapes of the stator core. However, the raw SMC material is relatively expensive, and the mechanical strength of SMC is weak. In this paper, a PMCPM with hybrid cores is proposed. With the adoption of hybrid silicon sheet-SMC cores and amorphous alloy-SMC cores, the torque ability of PMCPM can be improved greatly and it can have higher efficiency for more wide operation frequency. Meanwhile, its mechanical strength has been improved and it can be designed for high torque direct drive applications as it is a modular machine. Furthermore, three methods are proposed to reduce the additional eddy current loss which resulted from the employment of hybrid cores in PMCPM.

关键词： Permanent magnet claw pole machine(PMCPM) Soft magnetic materials(SMC) Hybrid cores Eddy current loss

The fabrication of nickel silicide ohmic contacts to n-type 6H-silicon carbide

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Chinese Physics B 2007年第6期16卷 1753-1756页

作者：郭辉张义门乔大勇孙磊张玉明 Microelectronic School Xidian University Key Laboratory of Ministry of Education for Wide Band-Gap Semiconductor Materials and Devices Xi'an 710071 China Micro and Nano electromechanical systems laboratory Northwestern Polytechnical University Xi'an 710072 China

This paper reports that the nickel silicide ohmic contacts to n-type 6H-SiC have been fabricated. Transfer length method test patterns with NiSi/SiC and NiSi2/SiC structure axe formed on N-wells created by N^＋ ion implantation into Si-faced p-type 6H-SiC epilayer respectively. NiSi and NiSi2 films are prepared by annealing the Ni and Si films separately deposited. A two-step annealing technology is performed for decreasing of oxidation problems occurred during high temperature processes. The specific contact resistance Pc of NiSi contact to n-type 6H-SiC as low as 1.78× 10^-6Ωcm^2 is achieved after a two-step annealing at 350 ℃for 20 min and 950℃ for 3 min in N2. And 3.84×10-6Ωcm^2 for NiSi2 contact is achieved. The result for sheet resistance Rsh of the N＋ implanted layers is about 1210Ω/□. X-ray diffraction analysis shows the formation of nickel silicide phases at the metal/n-SiC interface after thermal annealing. The surfaces of the nickel silicide after thermal annealing are analysed by scanning electron microscope.

关键词： ohmic contact silicon carbide nickel silicide N^+ ion implantation

Finding Short-Range Parity-Time Phase-Transition Points with a Neural Network

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Chinese Physics Letters 2021年第5期38卷 7-10页

作者： Songju Lei Dong Bai Zhongzhou Ren Mengjiao Lyu School of Physics Nanjing UniversityNanjing 210093China School of Physics Science and Engineering Tongji UniversityShanghai 200092China Key laboratory of Advanced Micro-structure materials(Ministry of Education) Shanghai 200092China College of Science Nanjing University of Aeronautics and Astronautics(NUAA)Nanjing 210016China Key laboratory of Aerospace Information materials and Physics(NUAA) MIITNanjing 211106China

The non-Hermitian PT-symmetric system can live in either unbroken or broken PT-symmetric phase. The separation point of the unbroken and broken PT-symmetric phases is called the PT-phase-transition ***, given an arbitrary non-Hermitian PT-symmetric Hamiltonian, one has to solve the corresponding Schrodinger equation explicitly in order to determine which phase it is actually in. Here, we propose to use artificial neural network(ANN) to determine the PT-phase-transition points for non-Hermitian PT-symmetric systems with short-range potentials. The numerical results given by ANN agree well with the literature, which shows the reliability of our new method.

关键词： ANN Hamiltonian Finding Short-Range Parity-Time Phase-Transition Points with a Neural Network

Porous carbon microspheres assembled by defective nitrogen and sulfur co-doped nanosheets as anode materials for lithium-/sodium-ion batteries

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Science China materials 2024年第11期67卷 3637-3647页

作者： Yutian Chen Jie You Xiaoran Zhao Mai Li Xiaolei Han Hui Liu Hongran Sun Xiaojun Wang Huifang Li Peng Wang Zhiming Liu College of electromechanical Engineering Shandong Engineering Laboratory for Preparation and Application of High-performance Carbon-MaterialsQingdao University of Science&TechnologyQingdao 266061China

Carbon-based anode materials are widely used in various battery energy storage systems due to their low cost,wide source,high conductivity and easy morphology ***,current commercially available anode materials as active materials for lithium-/sodium-ion batteries generally suffer from large volume changes and poor rate *** response,we synthesized defect-rich N,S co-doped two dimensional(2D)nanosheet-assembled porous carbon microspheres(N,S-PCS)via simple hydrothermal,carbonization and etching process based on the principle of Schiff base *** N,S-PCS structure is thus constructed by removing Fe7S8 nanoparticles from the carbon skeleton to form porous microspheres with N,S ***,the micromorphology characteristic,pore structure and electroconductivity of carbon materials are effectively optimized via heteroatom doping and surface *** expected,the prepared N,S-PCS electrodes exhibit excellent electrochemical performance in both lithium-ion and sodium-ion *** lithium-ion batteries,it achieves reversible capacities of 1045 and 237 mAh g^(-1) at 0.1 and 20 A g^(-1),*** sodium-ion batteries,it shows good cycling stability with a capacity of 157 mAh g^(-1) after 500 cycles at 1 A g^(-1).Experimental and theoretical calculation results confirm that the N,S co-doping strategies help to improve the structural stability,shorten the ion diffusion paths,and promote the reaction kinetics,thus achieving excellent electrochemical *** work is instructive for the practical application of nonmetal doping functionalized porous carbon structures for metal-ion batteries.

关键词： porous carbon microspheres element doping lithium-ion batteries sodium-ion batteries electrochemical performance

Exact Bayesian and Fiducial Limits for the Mean of Lognormal Distribution

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Journal of systems Engineering and Electronics 1994年第2期5卷 41-46页

作者： Zhou, Yuanquan Weng, Zhaoxi Liu, Zhengxian Beijing Inst of structure and Environment Beijing China

In this paper, the exact Bayesian limits, taking conjugate and noninformative prior distribution, and the exact fiducial limits for the mean of the lognormal distribution are presented. They can be found iteratively by one-dimension integral on a finite interval. The new algorithm is very convenient and with high accuracy. It can meet the practical engineering need excellently. However, the primitive algorithm is rather cumbersome. By the way, the very close approximate limits with a simple algorithm are derived. They can be applied immediately to engineering. Otherwise, they can also be used as a search interval to find the root of equation for the exact limits.

关键词： Algorithms Approximation theory Engineering research Failure analysis Integral equations Integration Iterative methods materials testing reliability theory Service life Statistical tests

Super twisting sliding mode approach applied to voltage orientated control of a stand-alone induction generator

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Protection and Control of Modern Power systems 2021年第1期6卷 233-241页

作者： Yacine Bendjeddou Abdelhakim Deboucha Larafi Bentouhami Elkheir Merabet Rachid Abdessemed laboratory of electrical and materials engineering(LGEM) Higher School of Electrical and Energetic Engineering of Oran31000Bir El DjirAlgeria Ecole Supérieure des Sciences Appliquées d’Alger Electrical Engineering Department16000AlgiersAlgeria Department of electromechanical University of Bordj Bou Arréridj34000El AnceurAlgeria laboratory LEB Department of Electrical EngineeringUniversity of Batna-205000FesdisAlgeria

To enhance the robustness and dynamic performance of a self-excited induction generator (SEIG) used in a stand-alone wind energy system (WES), a virtual flux oriented control (VFOC) based on nonlinear super-twisting sliding mode control (STSMC) is adopted. STSMC is used to replace the conventional proportional-integral-Fuzzy Logic Controller (PI-FLC) of the inner current control loops. The combination of the proposed control strategy with space vector modulation (SVM) applied to a PWM rectifier brings many advantages such as reduction in harmonics, and precise and rapid tracking of the references. The performance of the proposed control technique (STSMC-VFOC-SVM) is verified through simulations and compared with the traditional technique (PI-FLC-VFOC-SVM). It shows that the proposed method improves the dynamics of the system with reduced current harmonics. In addition, the use of a virtual flux estimator instead of a phase-locked loop (PLL) eliminates the line voltage sensors and thus increases the reliability of the system.

关键词： Self-excited induction generator Virtual flux oriented control Back-to-back converter Super twisting sliding mode control PI-fuzzy controller wind energy

A review of welding residual stress test methods

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China Welding 2022年第2期31卷 45-55页

作者： Gan Shiming Liu Huaying Zhai Zhiping Han Yongquan School of Mechanical Engineering Inner Mongolia University of TechnologyHohhot 010051China School of materials Science and Engineering Inner Mongolia University of TechnologyHohhot 010051China Key laboratory of electromechanical control of Inner Mongolia Autonomous Region Hohhot 010051China

Due to local uneven heating during the welding process,the residual stress of the structure after welding affects the reliability of *** order to ensure the reliability,it is of great significance to test the residual stress distribution of the welded *** has always been the focus to find a simple and feasible method for residual stress testing to quickly and accurately obtain the residual stress distribution of welded *** mechanical measurement method has high measurement accuracy,convenient and easy operation,but it will cause certain damage to the *** measurement method can avoid damage to components,but its test cost is usually high,and its measurement accuracy can also be affected by the material microstructure characteristics of welded *** on the advantages and disadvantages of these two residual stress test methods,a modal test method is *** method is a non-destructive measurement *** on the mathematical relationship between the residual stress of the welded structure and the natural frequency(mathematical model),the natural frequency is measured through the modal test to calculate the residual stress ***,it is difficult to establish a mathematical model with this method,and it is not suitable for realization.

关键词： welding residual stress mechanical measurement method physical measurement method modal test method