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Effect of order–disorder transition on thermodynamic and electronic properties of σ and χ phases in W–Re alloy: the first-principles calculation

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Tungsten 2025年第1期7卷 195-213页

作者： Zhi-Peng Zhu Dian Jia William Yi Wang Jun-Lei Yin Xing-Yu Gao Shu-Feng Yang Hai-Feng Song Jin-Shan Li State Key laboratory of Solidification Processing Northwestern Polytechnical University laboratory of computational Physics Institute of Applied Physics and Computational Mathematics School of Metallurgical and Ecological Engineering University of Science and Technology Beijing

The Tungsten-Rhenium(W-Re) alloys,celebrated for their high melting point,strength at elevated temperatures,electrical resistivity,and radiation resistance,have been widely utilized in high-temperature components,aerospace,electronics,and nuclear *** constituents of the topologically close-packed(TCP) phases,the sigma phase(σ) and chi phase(χ) formed within W-Re alloys wield considerable influence on the mechanical properties and the stability of the *** calculations were utilized in the present work to explore the structural,thermodynamic,and electronic properties of both ordered and disordered configurations within the σ and χ phases,culminating in a systematic elucidation of the higher phase stability exhibited by the ordered *** is found that the bulk modulus of these two phases is directly proportional to the concentration of Re in the alloy,while the equilibrium volume is inversely *** thermodynamic parameters of the σ and χ phases are calculated via the mean-field potential *** similar trends observed in the isobaric heat capacity,enthalpy increment,and entropy change curves for these two phases suggest they possess comparable thermodynamic *** is noteworthy that the contribution of ionic vibrations predominantly affects the isobaric heat capacity,while the contribution of thermal electronic excitations increases linearly with *** the structure and thermodynamic properties of TCP phases in W-Re alloys at low temperatures has profound significance for optimizing material performance,microstructures features,establishing theoretical foundations,and predicting material behavior.

关键词： First-principles calculations Phase stability TCP phases Thermodynamic properties W–Re alloy

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Barrierless reactions of C2 Criegee intermediates with H_(2)SO_(4)and their implication to oligomers and new particle formation

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Journal of Environmental Sciences 2025年第3期149卷 574-584页

作者： Yang Cheng Chao Ding Tianlei Zhang Rui Wang Ruxue Mu Zeyao Li Rongrong Li Juan Shi Chongqin Zhu Institute of Theoretical and computational Chemistry Shaanxi Key Laboratory of CatalysisSchool of Chemical&Environment ScienceShaanxi University of TechnologyHanzhongShaanxi 723001China College of Chemistry Key Laboratory of Theoretical&Computational Photochemistry of Ministry of EducationBeijing Normal UniversityBeijing 100190China

The formation of oligomeric hydrogen peroxide triggered by Criegee intermediate maybe contributes significantly to the formation and growth of secondary organic aerosol(SOA).However,to date,the reactivity of C2 Criegee intermediates(CH_(3)CHOO)in areas contaminated with acidic gas remains poorly ***,high-level quantum chemical calculations and Born-Oppenheimer molecular dynamics(BOMD)simulations are used to explore the reaction of CH_(3)CHOO and H_(2)SO_(4)both in the gas phase and at the airwater *** the gas phase,the addition reaction of CH_(3)CHOO with H_(2)SO_(4)to generate CH_(3)HC(OOH)OSO_(3)H(HPES)is near-barrierless,regardless of the presence of water *** simulations showthat the reaction at the air-water interface is even faster than that in the gas *** calculations reveal that the HPES has a tendency to aggregate with sulfuric acids,ammonias,and water molecules to form stable clusters,meanwhile the oligomerization reaction of CH_(3)CHOO with HPES in the gas phase is both thermochemically and kinetically ***,it is noted that the interfacial HPES−ion can attract H_(2)SO_(4),NH_(3),(COOH)_(2)and HNO_(3)for particle formation from the gas phase to the water ***,the results of this work not only elucidate the high atmospheric reactivity of C2 Criegee intermediates in polluted regions,but also deepen our understanding of the formation process of atmospheric SOA induced by Criegee intermediates.

关键词： Criegee intermediates H_(2)SO_(4) Atmospheric behavior Air-water interface Chemical processes

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Online Fault-Tolerant Tracking Control With Adaptive Critic for Nonaffine Nonlinear Systems

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IEEE/CAA Journal of Automatica Sinica 2025年第1期12卷 215-227页

作者： Ding Wang Lingzhi Hu Xiaoli Li Junfei Qiao IEEE the School of Information Science and Technology Beijing Key Laboratory of Computational Intelligence and Intelligent SystemBeijing Laboratory of Smart Environmental Protection and Beijing Institute of Artificial Intelligence Beijing University of Technology

In this paper, a fault-tolerant-based online critic learning algorithm is developed to solve the optimal tracking control issue for nonaffine nonlinear systems with actuator ***, a novel augmented plant is constructed by fusing the system state and the reference trajectory, which aims to transform the optimal fault-tolerant tracking control design with actuator faults into the optimal regulation problem of the conventional nonlinear error system. Subsequently, in order to ensure the normal execution of the online learning algorithm, a stability criterion condition is created to obtain an initial admissible tracking policy. Then, the constructed model neural network(NN) is pretrained to recognize the system dynamics and calculate trajectory control. The critic and action NNs are constructed to output the approximate cost function and approximate tracking control,respectively. The Hamilton-Jacobi-Bellman equation of the error system is solved online through the action-critic framework. In theoretical analysis, it is proved that all concerned signals are uniformly ultimately bounded according to the Lyapunov *** tracking control law can approach the optimal tracking control within a finite approximation error. Finally, two experimental examples are conducted to indicate the effectiveness and superiority of the developed fault-tolerant tracking control scheme.

关键词： Adaptive critic control neural network (NN) nonaffine nonlinear systems online fault-tolerant tracking design uniform ultimate boundedness

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Unraveling atomistic and electronic origins of multiaxial magnetic anisotropy

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Science China(Physics,Mechanics & Astronomy) 2025年第2期68卷 175-182页

作者： Boyu Liu Xueyang Li Junsheng Feng Changsong Xu Hongjun Xiang Key laboratory of computational Physical Sciences(Ministry of Education) Institute of Computational Physical SciencesState Key Laboratory of Surface Physics and Department of PhysicsFudan UniversityShanghai200433China Shanghai Qi Zhi Institute Shanghai200030China School of Physics and Material Engineering Hefei Normal UniversityHefei230601China

Multiaxial magnetic anisotropy(MA)refers to the phenomenon that multiple axes of the magnetic crystal correspond to different energy *** with the common uniaxial magnetic anisotropy,multiaxial MA facilitates novel forms of applications in ***,by combining the first-principles-based spin Hamiltonian and tight-binding(TB)method,we reveal the microscopic origins,instead of the common phenomenological understanding,of biaxial MA and triaxial *** the example system of NiO,it is found that the multiple minima result from the fourth-order and the sixth-order single ion interactions,while the difference between[110]and[110]directions originates from a second-order bond-dependent anisotropic pair interaction(i.e.,the so-called Gamma interaction).Moreover,through the application of a newly developed general spin dependent TB approach,it is revealed that the triaxial MA arises from the special spin-orbital entangled Hund term,which is different from the orbital-independent Hund term in the usual Slater Koster TB *** work thus not only leads to a thorough understanding of the multiaxial MA in NiO,but also establishes a methodology that can be widely used to explore the microscopic origins of MA in different magnets.

关键词： multiaxial magnetic anisotropy origin of multiaxial magnetic mnisotropy effective spin Hamiltonian tight-binding model antiferromagnetism

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Molecular dynamics simulation of quartz deformation under slow earthquake background

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Science China Earth Sciences 2025年第2期68卷 598-610页

作者： Jingxian SUN Qianqian GUO Quanlin HOU College of Earth and Planetary Sciences University of Chinese Academy of SciencesKey Laboratory of Computational GeodynamicsCASBeijing 100049China

Slow earthquakes are the primary mechanism of slow energy release,and research on the focal mechanism has been *** have primarily focused on the friction law based on physical mechanisms and have suggested that slow earthquakes are caused by brittle ***,the focal strength and structural characteristics of slow earthquakes in subduction zones provide evidence of plastic *** is the role of plastic deformation in the focal mechanisms of slow earthquakes?Mechanochemical study have shown that mechanical forces can directly affect chemical *** this study,we examine the storage and release of chemical energy during plastic deformation and consider a mechanochemical process in the focal mechanism of slow *** with the Tersoff potential,molecular dynamics simulation on the shear deformation process of twoα-quartz crystals show that the shear modulus ofα-quartz is 18 GPa,and that the crystal model primarily exhibits atoms flowing and changing in the direction of chemical bonds during the steady-state flow *** molecular potential energy and stress vary in an oscillating up-and-down curve during shear,indicating that chemical energy can be stored and released during plastic *** is consistent with the energy variation during slow *** the initial simple-shear loading condition,α-quartz crystals undergo general shear deformation instead of plane strain and the angle between the longest instantaneous stretching axis(ISA_(1))and the shearing direction is approximately 30°,not 45°.Both the deformation type and direction of ISA_(1)are contrary to basic deformation theory,which may provide clues for future *** study reveals the process of quartz elastic-plastic shear deformation on an atomic *** information is useful for understanding focal mechanisms of slow *** study is part of a series of investigations on tectonic stress chemistry.

关键词： Slow earthquake α-quartz Plastic strain energy Tectonic stress chemistry Tersoff potential

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Laser‑Induced Highly Stable Conductive Hydrogels for Robust Bioelectronics

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Nano-Micro Letters 2025年第3期17卷 117-120页

作者： Yibo Li Hao Zhou Huayong Yang Kaichen Xu State Key laboratory of fluid Power and Mechatronic Systems School of Mechanical EngineeringZhejiang UniversityHangzhou 310058People’s Republic of China

Despite the promising progress in conductive hydrogels made with pure conducting polymer,great challenges remain in the interface adhesion and robustness in longterm *** address these challenges,*** Hwan Ko and Taek-Soo Kim’s team introduced a laserinduced phase separation and adhesion method for fabricating conductive hydrogels consisting of pure poly(3,4-ethylenedioxythiophene):polystyrene sulfonate on polymer *** laser-induced phase separation and adhesion treated conducting polymers can be selectively transformed into conductive hydrogels that exhibit wet conductivities of 101.4 S cm^(−1) with a spatial resolution down to 5μ***,they maintain impedance and charge-storage capacity even after 1 h of *** micropatterned electrode arrays demonstrate their potential in long-term in vivo signal recordings,highlighting their promising role in the field of bioelectronics.

关键词： Laser processing Conductive hydrogels Stable interface Bio-interfacing electrodes Bioelectronic application

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Influence of trains meeting on the ventilation performance of equipment compartment with independent air duct in high-speed train:numerical and experimental study

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Railway Engineering Science 2025年第1期33卷 127-150页

作者： Yitong Wu Wei Zhou Xifeng Liang Xinchao Su Kewei Xu Yutao Xia Zhixin Wang Sinisa Krajnović Key laboratory of Traffic Safety On Track Ministry of EducationSchool of Traffic and Transportation EngineeringCentral South UniversityChangsha 410075China Joint International Research laboratory of Key Technology for Rail Traffic Safety Central South UniversityChangsha 410075China Division of fluid dynamics Department of Mechanics and Maritime SciencesChalmers University of TechnologySE‑41296 GothenburgSweden

During the train meeting events,train equipment compartments are exposed to the worst pressure changes,potentially affecting the ventilation performance of equipment,particularly for electrical facilities equipped with independent air *** this paper,a two-step method is used for numerical computation:(1)obtaining the temporal and spatial transient node data of the flow field sections during the train-passing simulation and(2)using the data as the input data for the equipment compartment *** addition,this paper also compares the difference in equipment ventilation between the single-train and trainpassing scenarios in real vehicle *** results indicate that the primary factors influencing ventilation effectiveness are the aerodynamic compression and deceleration of airflow induced by the other train's nose,as well as the instability of the external flow field in the wake of the other *** train crossing,the air is forced into the air duct,with a maximum ratio of the airflow in-duct to the airflow out-duct reaching *** average mass flow falls below the rated mass flow for the *** to the rated air volume of converter,the maximum suppression rates obtained from testing and simulation are-24.5%and-16.8%,*** to the single-train operation,the maximum suppression rates obtained from testing and simulation are-15%and-18%,*** findings provide valuable insights into the design and operation of high-speed trains.

关键词： Train-passing event Electrical facilities Independent air duct Ventilation performance

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A regularization method for delivering the fourth-order derivative of experimental data and its applications in fluid-structure interactions

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Science China Technological Sciences 2025年第3期68卷 363-380页

作者： Fan DUAN Jin-Jun WANG fluid Mechanics Key laboratory of Education Ministry Beijing University of Aeronautics and Astronautics

In the experimental investigation of fluid-structure interactions regarding the undulatory motion like flag flapping or fish swimming, solving the force distribution on the flexible body stands as an indispensable endeavor to gain insights into the underlying dynamic mechanisms. However, the solving process entails high-order numerical derivatives of experimental data, which poses a formidable challenge for experimental studies on fluid-structure interactions, given that the measurement noise inherent in experimental data renders the problem ill-posed. The commonly practiced regularization methods for numerical derivatives are feeble to tackle the fourth-order derivative associated with the bending force; those methods, in particular, require predetermined parameters about the unknown noise. We introduce here an empirical regularization method founded upon the kernel-term modification in the frequency domain, notably capable of determining the fourth derivative of experimental *** leveraging the potentials of the iterative operations, our method enables the reliable estimation of an approximately optimal regularization parameter, all without reliance on any a priori knowledge about the noise characteristics. To demonstrate the reliability, robustness, and accuracy of the method, we perform rigorous numerical assessments using different data models that are infused with noise varying several orders of magnitude. Additionally, practical application of this method is achieved in the experiment on a flexible film flapping in the gusty flow, where the spatiotemporal distribution of the bending force density on the film is calculated by integrating this method with a linear reconstruction.

关键词： high-order numerical derivative regularization film fluid-structure interactions bending force

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Flat-band based high-temperature ferromagnetic semiconducting state in the graphitic C4N3 monolayer

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Fundamental Research 2025年第1期5卷 138-144页

作者： Chaoyu He Yujie Liao Tao Ouyang Huimin Zhang Hongjun Xiang Jianxin Zhong laboratory for Quantum Engineering and Micro-Nano Energy Technology and School of Physics and Optoelectronics Xiangtan UniversityXiangtan 411105China Key laboratory of computational Physical Sciences(Ministry of Education) Institute of Computational Physical SciencesDepartment of PhysicsFudan UniversityShanghai 200433China

Half-filled isolated flat-band paves a new way to realize high-temperature ferromagnetic semiconductor for spintronics applications,but it is extremely rare in lattice models and lacking in realistic ***,the 2×2 super-cell of the honeycomb lattice with a single-hole defect is proposed as a new lattice model(HL-D-1/8)to realize nontrivial isolated *** further demonstrate that C_(4)N_(3)monolayer of the experimentally realized graphitic carbon nitride(***.,22,1004,2010;***.,9,3366,2018)is a perfect system holding such a lattice to host flat-bands.A new corrugated Pca21 configuration is proposed as the ground state for the free-standing C_(4)N_(3)monolayer,which is dynamically stable and energetically more favorable than the widely-used flat one without dynamical *** Pca21 configuration is found to be an intrinsic ferromagnetic half-semiconductor(T_(c)≈241 K)with one semiconducting spin-channel(1.75 eV)and one insulating spin-channel(3.64 eV),which is quite rare in two-dimensional *** ferromagnetic semiconducting property originates from the isolated pz-state flat-band as the corrugation shifts the flat-band upward to the Fermi ***,such a corrugated Pca21 C_(4)N_(3)monolayer is found to be both piezoelectric and ferroelectric,which makes it an unusual metal-free two-dimensional multiferroic.

关键词： Graphitic C_(4)N_(3) Isolated flat-band Ferromagnetic semiconductor Two-dimensional multiferroic First-principles calculation Tight-binding model

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High-resolution imaging through dynamic scattering media:Iterative optimization based on polarimetric characteristics

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Science China(Technological Sciences) 2025年第1期68卷 78-80页

作者： Meng XIANG Kai DENG Tianyu WANG Jinpeng LIU Xue DONG Teli XI Fei LIU Xiaopeng SHAO School of Optoelectronic Engineering Xidian UniversityXi’an 710071China Xi’an Key laboratory of computational Imaging Xi’an 710071China National Key laboratory of Infrared Detection Technologies Shanghai 200083China

High-resolution imaging through randomly dynamic scattered fields and highly scattered walls is an extensively sought-after capability with potential applications in various fields such as underwater imaging,biomedical imaging,and seeing through *** methods have been proposed to unscramble object information from degraded scattered images,resulting in considerable improvements in image contrast in degraded scenarios[1].

关键词： scattered dynamic resolution

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