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Exact solution of Heisenberg model with site-dependent exchange couplings and Dzyloshinsky–Moriya interaction

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Chinese Physics B 2015年第10期24卷 460-466页

作者：杨丽君曹俊鹏杨文力 beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of Sciences collaborative innovation Center of Quantum Matter institute of Modern Physics Northwest University beijing Center for Mathematics and Information Interdisciplinary Sciences

We propose an integrable spin-1/2 Heisenberg model where the exchange couplings and Dzyloshinky-Moriya interactions are dependent on the sites. By employing the quantum inverse scattering method, we obtain the eigenvalues and the Bethe ansatz equation of the system with the periodic boundary condition. Furthermore, we obtain the exact solution and study the boundary effect of the system with the anti-periodic boundary condition via the off-diagonal Bethe ansatz. The operator identities of the transfer matrix at the inhomogeneous points are proved at the operator level. We construct the T -Q relation based on them. From which, we obtain the energy spectrum of the system. The corresponding eigenstates are also constructed. We find an interesting coherence state that is induced by the topological boundary.

关键词： Bethe ansatz Yang-Baxter equation T-Q relation

Solidification Structure of Continuous Casting Large Round Billets under Mold Electromagnetic Stirring

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Journal of Iron and Steel Research International 2016年第4期23卷 329-337页

作者： Tao SUN Feng YUE Hua-jie WU Chun GUO Ying li Zhong-cun MA Metallurgical Engineering Research institute University of Science and Technology Beijing collaborative innovation Center of Steel Technology University of Science and Technology Beijing Beiman Special Steel Co. Ltd.

The solidification structure of a continuous casting large round billet was analyzed by a cellular-automaton-finite-element coupling model using the ProCAST software. The actual and simulated solidification structures were compared under mold electromagnetic stirring （MEMS） conditions （current of 300 A and frequency of 3 Hz）. Thereafter, the solidification structures of the large round billet were investigated under different superheats, casting speeds, and secondary cooling intensities. Finally, the effect of the MEMS current on the solidification structures was obtained under fixed superheat, casting speed, secondary cooling intensity, and MEMS frequency. The model accurately simulated the actual solidification structures of any steel, regardless of its size and the parameters used in the continuous casting process. The ratio of the central equiaxed grain zone was found to increase with decreasing superheat, increasing casting speed, decreasing secondary cooling intensity, and increasing MEMS current. The grain size obviously decreased with decreasing superheat and increasing MEMS current but was less sensitive to the casting speed and secondary cooling intensity.

关键词： continuous casting large round billet solidification structure cellular-automaton-finite-element method mold electromagnetic stirring central equiaxed grain zone grain size

Effects of Chromium,Vanadium and Austenite Deformation on Transformation Behaviors of High-strength Spring Steels

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Journal of Iron and Steel Research International 2016年第12期23卷 1323-1332页

作者： Gang NIU Yin-li CHEN Hui bin WU Xuan WANG Mao-fang ZUO Zhi-jun XU collaborative innovation Center of Steel Technology University of Science and Technology BeijingBeijing 100083China Engineering Research institute University of Science and Technology BeijingBeijing 100083China beijing Laboratory of Metallic Materials and Processing for Modern Transportation Beijing 100083China

The phase transformation behavior during continuous cooling of high-strength spring steels containing different amounts of Cr was studied. Furthermore, the effects of combining Cr with V as well as austenite deformation on the transformation kinetics were investigated in the method of dilatometry and metallography hardness. The re suits showed that, with the increase of Cr, the pearlite transformation field was enlarged, the ferrite transformation field was narrowed, and the entire phase field shifted to the right. With the addition of V, the start transformation temperature of undercooling austenite （Ar3） was gradually increased, but the ferrite and pearlite transformation fields were not affected. Besides, the minimum critical cooling rate of martensilic transformation was also reduced. In addition, the dynamic continuous cooling transformation （CCT） curve moves to the top left compared with the static CCT curve. The transformed microstructures showed that the addition of V and the deformation not only refined the overall transformed microstructures but also reduced the lamellar spacing of pearlite. The alloying elements Cr and V promoted the Vickers hardness. However, the effect of Cr on the Vickers hardness of martensite was stronger and the influence of V on that of pearlite was stronger. Moreover, the Vickers hardness affected by the austenite deformation was more complex and strongly depended on the transformed microstructures.

关键词： spring steel phase transformation Chromium deformation microstructure

Multiproduct and multistage integrated production planning model and algorithm based on an available production capacity network

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International Journal of Minerals,Metallurgy and Materials 2021年第8期28卷 1343-1352页

作者： Zhi-min Lü Tian-ru Jiang Zai-wei li collaborative innovation Center of Steel Technology University of Science and Technology BeijingBeijing 100083China institute of Engineering Technology University of Science and Technology BeijingBeijing 100083China China Ordins Group CO. LTDBeijing 100089China

This research attempts to devise a multistage and multiproduct short-term integrative production plan that can dynamically change based on the order priority and virtual occupancy for application in steel plants. Considering factors such as the delivery time, varietal compatibility between different products, production capacity of variety per hour, minimum or maximum batch size, and transfer time, we propose an available production capacity network with varietal compatibility and virtual occupancy for enhancing production plan implementation and quick adjustment in the case of dynamic production changes. Here available means the remaining production capacity after virtual *** quickly build an available production capacity network and increase the speed of algorithm solving, constraint selection and cutting methods with order priority were used for model solving. Finally, the genetic algorithm improved with local search was used to optimize the proposed production plan and significantly reduce the order delay rate. The validity of the proposed model and algorithm was numerically verified by simulating actual production practices. The simulation results demonstrate that the model and improved algorithm result in an effective production plan.

关键词： short-term integrated plan constraint satisfaction model available production capacity varietal compatibility virtual capacity occupancy

Evidence for Multiple Underlying Fermi Surface and Isotropic Energy Gap in the Cuprate Parent Compound Ca2CuO2Cl2

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Chinese Physics Letters 2018年第6期35卷 84-89页

作者： Cheng Hu Jian-Fa Zhao Ying Ding Jing liu Qiang Gao lin Zhao Guo-Oong liu li Yu Chang-Qing Jin Chuang-Tian Chen Zu-Yan Xu Xing-Jiang Zhou beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of SciencesBeijing 100190 University of Chinese Academy of Sciences Beijing 100049 Technical institute of Physics and Chemistry Chinese Academy of SciencesBeijing 10019 collaborative innovation Center of Quantum Matter Beijing 100871

The parent compounds of the high-temperature cuprate superconductors are Mott *** has been generally agreed that understanding the physics of the doped Mott insulators is essential to understanding the mechanism of high temperature superconductivity.A natural starting point is to elucidate the basic electronic structure of the parent *** we report comprehensive high resolution angle-resolved photoemission measurements on Ca_2CuO_2Cl_2,a Mott insulator and a prototypical parent compound of the *** *** Fermi surface sheets are revealed for the first *** high energy waterfall-like band dispersions exhibit different behaviors near the nodal and antinodal *** distinct energy scales are identified：a d-wave-like low energy peak dispersion and a nearly isotropic lower Hubbard band *** observations provide new information of the electronic structure of the cuprate parent compound,which is important for understanding the anomalous physical properties and superconductivity mechanism of the high temperature cuprate superconductors.

关键词： CuO Evidence for Multiple Underlying Fermi Surface and Isotropic Energy Gap in the Cuprate Parent Compound Ca2CuO2Cl2 Ca Cl

Spinel-type bimetal sulfides derived from Prussian blue analogues as efficient polysulfides mediators for lithium-sulfur batteries

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Chinese Chemical Letters 2021年第12期32卷 4063-4069页

作者： Ruijian li Zhe Bai Wenshuo Hou Jinshuo Qiao Wang Sun Yu Bai Zhenhua Wang Kening Sun beijing Key Laboratory for Chemical Power Source and Green Catalysis School of Chemistry and Chemical EngineeringBeijing Institute of TechnologyBeijing 100081China collaborative innovation Center of Electric Vehicles in beijing Beijing 100081China

More and more attentions have been attracted by lithium-sulfur batteries(li-S), owing to the high energy density for the increasingly advanced energy storage system. While the poor cycling stability, due to the inherent polysulfide shuttle, seriously hampered their practical application. Recently, some polar hosts,like single metal oxides and sulfides, have been employed as hosts to interact with polysulfide intermediates. However, due to the inherent poor electrical conductivity of these polar hosts, a relatively low specific capacity is obtained. Herein, a spinel-type bimetal sulfide NiCo_(2)S_(4)through a Prussian blue analogue derived methodology is reported as the novel host of polysulfide, which enables highperformance sulfur cathode with high Coulombic efficiency and low capacity decay. Notably, the li-S battery with NiCo_(2)S_(4)-S composites cathode still maintains a capacity of 667 m Ah/g at 0.5 Cafter 300 cycles, and 399 m Ah/g at 1 C after 300 cycles. Even after 300 cycles at the current density of 0.5C, the capacity decays by 0.138% per cycle at high sulfur loading about 3 mg/cm;. And the capacity decays by0.026% per cycle after 1000 cycles, when the rate is 1C. More importantly, the cathode of Ni Co_(2)S_(4)-S composite shows the outstanding discharge capacity, owing to its good conduction, high catalytic ability and the strong confinement of polysulfides.

关键词： Polysulfide shuttle NiCo_(2)S_(4)L Ithium-Sulfur batteries

Multidimensional Co_(3)O_(4)/NiO heterojunctions with richboundaries incorporated into reduced graphene oxide network for expanding the range of lithiophilic host

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InfoMat 2022年第8期4卷 93-104页

作者： Qianqian Meng Minrong Guan Yongxin Huang li li Feng Wu Renjie Chen beijing Key Laboratory of Environmental Science and Engineering School of Materials Science and EngineeringBeijing Institute of TechnologyBeijingChina institute of Advanced Technology Beijing Institute of TechnologyJinanChina collaborative innovation Center of Electric Vehicles in beijing BeijingChina

The commercial application of lithium(li)metal anode is hindered by the growth of li ***,we develop a multidimensional composite struc-ture composed of Co3O4/NiO heterojunction particles and reduced graphene oxide(rGO)nanosheets,that allows li to nucleate and deposit selectively in one ***,two transition metal oxides(TMOs)without lit-hiophilicity are transformed into lithiophilic species due to the rich phase boundaries and high li adsorption energies on interfaces,which can provide uniform active sites and reduce nucleation overpotential for li ***,the rGO substrate with high electrical conductivity and large spe-cific surface area can form a conductive network between TMOs and alleviate volume expansion caused by li *** from the synergistic effect of the heterojunctions and carbon substrate,the Co_(3)O_(4)/NiO-rGO regu-lates the local current density and enables the dendrite-free li plating/stripping *** a current density of 1 mA cm^(-2),the li metal anode with the Co_(3)O_(4)/NiO-rGO host exhibits remarkable electrochemical performance,consistently maintaining high Coulombic efficiency(>93.8%)over 1000 ***,the full cells matched with liFePO_(4)cathode also display high rate capability of 130 mAh g^(-1)at 1 C and stable cycling life over 500 cycles.

关键词： 3D rGO network lithiophilic host lithium metal anode rich-boundaries heterojunctions

Antioxidant and ACE inhibitory activities of peptides prepared from adzuki bean by semi-solid enzymatic hydrolysis

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Food Bioscience 2022年第3期47卷 253-261页

作者： Mengdi Cao Wenhui li He li Jian Zhang Yu liu Xinqi liu National Soybean Processing Industry Technology innovation Center School of Food and HealthBeijing Technology and Business UniversityBeijing100048China beijing institute of collaborative innovation Beijing100094China Chinese Academy of Inspection and Quarantine Beijing100123China

In this study,adzuki bean peptides were prepared by semi-solid enzymatic hydrolysis(SEH)and their antioxidant and Angiotensin-I-converting enzyme(ACE)inhibitory activities and internal absorption were *** modifying different enzymatic hydrolysis times and enzyme additions,the optimal enzymatic hydrolysis condition for SEH could be obtained as adzuki bean powder:water=4:1(w/w),alcalase:neutrase=2:1(w/w),enzyme addition 3.75%(w/w),4 h enzymatic hydrolysis at 50℃ and pH=*** these hydrolysis conditions,the content of adzuki bean peptides was 11.37%,the OH−scavenging rate of 1 mg/mL peptides was 72.75%,the total antioxidant capacity was 0.88±0.02 mmol/L FeSO4,the ACE inhibition rate was 77.49%.In vivo absorption test proved that the peptides prepared by SEH were absorbed faster and exhibited higher antioxidant activity compared with liquid enzymatic *** conclusion,the process of SEH can improve not only the efficiency of hydrolysis,but also the antioxidant and ACE inhibitory activity as well as the internal absorption of adzuki bean peptides.

关键词： Adzuki bean peptides Semi-solid enzymolysis Antioxidant ACE inhibition Absorption

Effects of strain states on stability of retained austenite in medium Mn steels

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Journal of Iron and Steel Research International 2017年第11期24卷 1125-1130页

作者： Mei Xu Yong-gang Yang Jia-yong Chen Di Tang Hai-tao Jiang Zhen-li Mi institute of Engineering Technology University of Science and Technology BeijingBeijing 100083China BYD Auto Industry Company limited Shenzhen 518116GuangdongChina collaborative innovation Center of Steel Technology University of Science and Technology BeijingBeijing 100083China

Based on uniaxial tensile and plane strain deformation tests, the effects of strain states on the stability of RA （retained austenite） in medium Mn steels, which were subjected to IA （intercritical annealing） and Q＆P （quenching and partitioning） processing, were investigated. The volume fractions of RA before and after deformation were measured at different equivalent strains. The transformation behaviors of RA were also investigated. The stability of RA differed across two different transformation stages at the plane strain state： the stability was much lower in the first stage than in the second stage. For the uniaxial ten sion strain state, the stability of RA corresponded only to a single transformation stage. The main reason was that there were two types of transformations from RA in the medium Mn steel for the plane strain state. One type was that the martensite originated in the strain-induced stacking faults （SISF）. The other type was the strain-induced directly twin martensite at a certain equivalent strain. However, for the uniax- ial tension state, only the strain-induced twin martensite was observed. Dislocation lines and dislocation tangles were also observed in specimens deformed at different strain states. In addition, complex micro- structures of stacking faults and lath-like phases were observed within a grain at the plane strain state.

关键词： Medium Mn steel Strain state Retained austenite Stability Stacking fault Twin martensite