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Comparison Between North-South Aid and South-South Cooperation:Based on the Analysis of the New Development Finance Institutions

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Journal of Shanghai Jiaotong university(Science) 2016年第1期21卷 25-32页

作者：崔文星 center for BRICS studies Fudan Development Institute Fudan University

According to the different players, development cooperation is often divided into North-South Aid and South-South Cooperation, both of which have a history of several decades. Since the beginning of the 21st century, the rise of a number of emerging economies has brought South-South Cooperation into a new stage, which can be seen from the establishment of some new development finance institutions led by developing countries. BRICS Bank, Asia Infrastructure Investment Bank(AIIB) and Silk Road Fund are three important new development finance institutions. Compared with the traditional development finance institutions like World Bank and International Monetary Fund(IMF), they have their own concepts of development cooperation, which are different from the traditional ones. First, the new finance institutions pay more attention to the equality between partners, not imposing conditions and respecting the ownership of development partners. Second, the new development finance institutions value the market philosophy, which means that they emphasize the importance of field investigation and implement development cooperation in accordance with the actual needs of the partners and the comparative advantages of the providers. Finally, the new development finance institutions focus their resources on problem-solving and avoid doctrines-imposing. They believe that it is easier for the developing countries to achieve development through a gradual and bottom-up model. Although there are differences between the traditional and new development finance institutions, the latter is not parallel to or substitute of the *** can cooperate with each other and provide better public goods for international cooperation through inclusive competition.

关键词： development cooperation South-South Cooperation BRICS Bank Asia Infrastructure Investment Bank(AIIB)

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Twistronics in graphene-based van der Waals structures

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Chinese Physics B 2020年第11期29卷 1-16页

作者： Ya-Ning Ren Yu Zhang Yi-Wen Liu Lin He center for Advanced Quantum studies Department of PhysicsBeijing Normal UniversityBeijing 100875China

The electronic properties of van der Waals(vd W) structures can be substantially modified by the moiré superlattice potential, which strongly depends on the twist angle among the compounds. In twisted bilayer graphene(TBG), two lowenergy Van Hove singularities(VHSs) move closer with decreasing twist angles and finally become highly non-dispersive flat bands at the magic angle(~1.1°). When the Fermi level lies within the flat bands of the TBG near the magic angle,Coulomb interaction is supposed to exceed the kinetic energy of the electrons, which can drive the system into various strongly correlated phases. Moreover, the strongly correlated states of flat bands are also realized in other graphene-based vd W structures with an interlayer twist. In this article, we mainly review the recent scanning tunneling microscopy(STM)advances on the strongly correlated physics of the magic-angle TBG(MATBG) and the small-angle twisted multilayer graphene. Lastly we will give out a perspective of this field.

关键词： twisted bilayer graphene correlated states superconductivity

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Anomalous magnetoresistance in detwinned EuFe2As2

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Chinese Physics B 2020年第7期29卷 495-501页

作者： Zhuang Xu Junxiang Pan Zhen Tao Ruixian Liu Guotai Tan center for Advanced Quantum studies and Department of Physics Beijing Normal UniversityBeijing 100875China

The in-plane magnetotransport of detwinned EuFe2As2 single crystal has been *** the antiferromagnetic phase of Eu^2+spins,very different magnetoresistance results are observed upon the change of the external magnetic field direction and the current *** could be attributed to the tunable orientation of the Eu^2+spins under magnetic *** scattering by spin fluctuation,superzone boundary effect,and cyclotron motion of charge carriers are used to interpret the observed anomalous magnetoresistance which is measured by using a current along a *** remarkable features of magnetoresistance suggest that itinerant electrons strongly couple with the spin configuration of Eu^2+,which has a huge influence on the transport properties of EuFe2As2.

关键词： magnetoresistance spin reorientation iron pnictides

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The detrimental effect of autofrettage on externally cracked modern tank gun barrels

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Defence Technology（防务技术） 2019年第2期15卷 146-153页

作者： M.Perl T.Saley Pearlstone center for Aeronautical Engineering studies Department of Mechanical Engineering Ben-Gurion University of the Negev

Overstraining gun tubes has a twofold advantage. First, it enables the increase of the Safe Maximum Pressure(SMP) in the tube, resulting in a higher muzzle velocity which extends the gun's range and its projectile kinetic energy. Second, it reduces the tube's susceptibility to internal cracking which prolongs its fatigue life. Unfortunately, autofrettage also bears an inherent detrimental effect as it considerably increases the tensile hoop stress at the outer portion of the barrel's wall, which enhances external cracking of the tube by increasing the prevailing Stress Intensity Factor(SIF). In order to quantify this disadvantageous effect, 3-D Mode I SIFs distributions along the front of a single external radial semielliptical crack initiating from the outer surface of an autofrettaged modern gun barrel, overstrained by either the Swage or the Hydraulic autofrettage processes, are evaluated. The analysis is performed by the finite element(FE) method, using singular elements along the crack front. Innovative residual stress fields(RSFs), incorporating the Bauschinger effect for both types of autofrettage are applied to the ***'s [1] RSF is also applied to the tube for comparison reasons. All three RSFs are incorporated in the FE analysis, using equivalent temperature fields, Values for K_(IA)-the SIF resulting from the tensile residual stresses induced by autofrettage are evaluated for: a typical barrel of radii ratio R_o/R_i = 2, crack depth to wall-thickness ratios(a/t = 0.005-0.1),crack ellipticities(a/c = 0.2-1.0),and five levels of Swage,Hydraulic and Hill's autofrettage(e = 40%,60%,70%,80%,and 100%). In total,375 different 3-D cases are analyzed. The analysis demonstrates undoubtedly the detrimental effect of all types of autofrettage in increasing the prevailing effective stress intensity factor of external cracks, resulting in crack initiation enhancement and crack growth rate acceleration which considerably shortens the total fatigue life of the bar

关键词： Gun barrel Swage and hydraulic autofrettage External crack 3-D Finite element

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Recursive Least Square Vehicle Mass Estimation Based on Acceleration Partition

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Chinese Journal of Mechanical Engineering 2014年第3期27卷 448-459页

作者： FENG Yuan XIONG Lu YU Zhuoping QU Tong School of Automotive studies Tongji University Clean Energy Automotive Engineering center Tongji University

Vehicle mass is an important parameter in vehicle dynamics control systems. Although many algorithms have been developed for the estimation of mass, none of them have yet taken into account the different types of resistance that occur under different conditions. This paper proposes a vehicle mass estimator. The estimator incorporates road gradient information in the longitudinal accelerometer signal, and it removes the road grade from the longitudinal dynamics of the vehicle. Then, two different recursive least square method （RLSM） schemes are proposed to estimate the driving resistance and the mass independently based on the acceleration partition under different conditions. A 6 DOF dynamic model of four In-wheel Motor Vehicle is built to assist in the design of the algorithm and in the setting of the parameters. The acceleration limits are determined to not only reduce the estimated error but also ensure enough data for the resistance estimation and mass estimation in some critical situations. The modification of the algorithm is also discussed to improve the result of the mass estimation. Experiment data on asphalt road, plastic runway, and gravel road and on sloping roads are used to validate the estimation algorithm. The adaptability of the algorithm is improved by using data collected under several critical operating conditions. The experimental results show the error of the estimation process to be within 2.6%, which indicates that the algorithm can estimate mass with great accuracy regardless of the road surface and gradient changes and that it may be valuable in engineering applications. This paper proposes a recursive least square vehicle mass estimation method based on acceleration partition.

关键词： mass estimation recursive least square method acceleration partition

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Invariants of Multi-Component Ermakov Systems

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Communications in Theoretical Physics 2010年第9期54卷 393-396页

作者：屈长征闫璐 center for Nonlinear studies Northwest University Department of Mathematics Northwest University

It is shown that certain multi-component Ermakov systems admit Lewis-Ray-Reid *** extendsthe result to the two-component Ermakov system.

关键词： multi-component Ermakov system Lewis-Ray-Reid invariant affine invariant symmetry

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Emergent Quantum Dynamics of Vortex-Line under Linear Local Induction Approximation

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Chinese Physics Letters 2019年第12期36卷 52-56页

作者： Gui-Hao Jia Yu Xu Xiao Kong Cui-Xian Guo Si-Lei Liu Su-Peng Kou center for Advanced Quantum studies Department of PhysicsBeiing Normal UniversityBeijing 100875

Using the linear local induction approximation, we investigate the self-induced motion of a vortex-line that corresponds to the motion of a particle in quantum mechanics. Provided Kelvin waves, the effective Schr?dinger equation, physical quantity operators, and the corresponding path-integral formula can be obtained. In particular,the effective Planck constant defined by parameters of vortex-line motion shows the mathematical relation between the two fields. The vortexline–particle mapping may help in understanding particle motion in quantum mechanics.

关键词： vortex quantum Approximation

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State-Dependent Topological Invariants and Anomalous Bulk-Boundary Correspondence in Non-Hermitian Topological Systems with Generalized Inversion Symmetry

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Chinese Physics Letters 2020年第11期37卷 87-92页

作者： Xiao-Ran Wang Cui-Xian Guo Qian Du Su-Peng Kou center for Advanced Quantum studies Department of PhysicsBeijing Normal UniversityBeijing 100875China

Breakdown of bulk-boundary correspondence in non-Hermitian(NH)topological systems with generalized inversion symmetries is a controversial *** non-Bloch topological invariants determine the existence of edge states,but fail to describe the number and distribution of defective edge states in non-Hermitian topological *** state-dependent topological invariants,instead of a global topological invariant,are developed to accurately characterize the bulk-boundary correspondence of the NH systems,which is very different from their Hermitian *** the same time,we obtain the accurate phase diagram of the one-dimensional non-Hermitian Su–Schrieffer–Heeger model with a generalized inversion symmetry from the state-dependent topological ***,these results will be helpful for understanding the exotic topological properties of various non-Hermitian systems.

关键词： topological invariants correspondence

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EBSD Investigation on Effect of Cooling Rate on Microstructure and Transformation Textures of High Strength Hot-rolled Steel Plates

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Journal of Iron and Steel Research International 2016年第3期23卷 261-269页

作者： Nancy M.LOPEZ GRANADOS Armando SALINAS RODRIGUEZ Department of Metallurgical Engineering and Materials Science Center of Research and Advanced StudiesCINVESTAV-Unidad Saltillo

The effect of cooling rate on the microstructure and transformation textures of high strength hot-rolled steels was *** treated samples subjected to different cooling conditions were characterized by optical and scanning electron microscopes using orientation imaging microscopy（OIM）.The experimental results demonstrate that there is a significant effect of cooling rate on microstructures and textures resulting from phase *** cooling rates lead to the appearance of the cube（001）[010],rotated cube（001）[110]/（001）[110],Goss（110）[001]and rotated Goss（110）[110]*** contrast,textures developed at rapid cooling rates are preferably of Cu（112）[111],Br（110）[112],transformed Cu（113）[110]and transformed Br（332）[113]/（112）[131].These texture changes are attributed to the selective character of the phase *** OIM technique was used to have a better understanding of the formation of phases and their relationship between microstructure and processing *** volume fraction of micro-constituents resulting from phase transformation such as bainite,martensite and different types of ferrite,can be measured satisfactorily by this technique correlating image quality of EBSD patterns to specific phases.

关键词： orientation imaging microscopy texture phase transformation microstructure steel

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Local measurements of tunneling magneto-conductance oscillations in monolayer, Bernal-stacked bilayer, and ABC-stacked trilayer graphene

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Science China(Physics,Mechanics & Astronomy) 2021年第8期64卷 72-77页

作者： Ya-Ning Ren Mo-Han Zhang Chao Yan Yu Zhang Lin He center for Advanced Quantum studies Department of PhysicsBeijing Normal UniversityBeijing 100875China

Shubnikov-de Haas oscillations are the most well-known magneto-oscillations in transport measurements. They are caused by Landau quantization of two-dimensional(2D) electron systems in the presence of a magnetic field. Here we demonstrate that a scanning tunneling microscope(STM) can locally measure similar magneto-oscillations in 2D systems. In Landau level spectroscopy measurements with fine magnetic-field increments, we observed fixed-energy magnetic-field-dependent oscillations of the local density of states. From the measured tunneling magneto-conductance oscillations acquired by STM, energymomentum dispersions and Berry phases of a monolayer, Bernal-stacked bilayer, and ABC-stacked trilayer graphene were obtained. The reported method is applicable to a wide range of materials because it can obtain the magneto-oscillations of 2D systems larger than the magnetic length;importantly, it also requires no gate electrode.

关键词： graphene magneto-conductance oscillations scanning tunneling microscopy energy-momentum dispersion Berry phase

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