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Rare Metals 2024年第4期43卷 1786-1792页

作者： Yuan-Feng Xie Xing-Cheng Xie Zhong-Wu Li Rui-Jun Cao Zhong-Kun Lin Qing Li Chen-Guang Lin Powder Metallurgy and special Materials research Department General Research Institute for Nonferrous MetalsBeijing100088China

The effects of cryogenic treatment(CT)and tempering-cryogenic treatment(TCT)on the microstructure and properties of coarse-grained WC-10Co cemented carbides with different carbon contents were *** binder phase,WC mean grain sizes,W solubility in the binder,relative magnetic s aturation,densities,hardness,wear resistance and second phase precipitation of cemented carbides with different heat treatments were *** results show that there are significant changes of microstructure and properties in the samples with CT and TCT,especially due to the precipitation of metastable nanoparticles W_(x)Co_(y)C_(z) in the binder during the heat treatments of CT and *** the simultaneous combination of microstructure and nanoparticle-reinforced binder,a dramatically improved combination of hardness and wear resistance of the samples after TCT has been achieved.

关键词： Cryogenic treatment Tempering Coarsegrained cemented carbide Carbon content Nanoparticlereinforced binder

Underwater Directional Acoustic Source Based on Pentamode Material

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Acta Mechanica Solida Sinica 2024年第1期37卷 1-9页

作者： Binghao Zhao Peng Wang Dongwei Wang Gengkai Hu School of Aerospace Engineering Beijing Institute of TechnologyBeijing 100081China Wuhan Second Ship design and research institute Wuhan 430205China

An underwater directional acoustic emitter is conceived with a highly anisotropic lattice material,whose acoustic characteristics manifest strong dependence on the orientation of the lattice material’s principal *** these features,a cylindrical structure made of such anisotropic lattice material is engineered to possess distinct impedance values in different directions,thereby facilitating wave emission along the principal axis while inducing reflection in other ***,through numerical simulations,it is demonstrated that the emission direction can be effectively manipulated by adjusting the principal axis orientation,concurrently enhancing the emitted *** contrast to previous directional acoustic structures,the compact emitter presented in this study can get rid of the size-wavelength constraint,enabling effective control of low-frequency waves.

关键词： Underwater Directional emission Pentamode material Broadband frequency

Investigations of the mechanical response of dummy HTPB propellant grain under ultrahigh acceleration overload conditions using onboard flight-test measurements

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Defence Technology（防务技术） 2024年第2期32卷 473-484页

作者： Yiming Zhang Ningfei Wang Weihua Ma Ran Wang Long Bai Yi Wu School of Aerospace Engineering Beijing Institute of TechnologyBeijing 100081China beijing System design institute of Electro-mechanic Engineering Beijing 100854China Xi'an Changfeng research institute of Mechanism and Electricity Xi'an 710065China

In this paper,to study the mechanical responses of a solid propellant subjected to ultrahigh acceleration overload during the gun-launch process,specifically designed projectile flight tests with an onboard measurement system were *** projectiles containing dummy HTPB propellant grains were successfully recovered after the flight tests with an ultrahigh acceleration overload value of 8100 *** onboard-measured time-resolved axial displacement,contact stress and overload values were successfully obtained and *** compression tests of the dummy HTPB propellant used in the gunlaunched tests were carried out at low and intermediate strain rates to characterize the propellant's dynamic properties.A linear viscoelastic constitutive model was employed and applied in finite-element simulations of the projectile-launching *** the launch process,the dummy propellant grain exhibited large deformation due to the high acceleration overload,possibly leading to friction between the motor case and propellant *** calculated contact stress showed good agreement with the experimental results,though discrepancies in the overall displacement of the dummy propellant grain were *** dynamic mechanical response process of the dummy propellant grain was analysed in *** results can be used to estimate the structural integrity of the analysed dummy propellant grain during the gun-launch process.

关键词： Gun-launched flight test Dummy HTPB propellant Onboard measurements Utrahigh overload Mechanical response

Hydrodynamics and OCM reaction performance in a bubbling fluidized bed reactor and a riser reactor

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Particuology 2024年第3期86卷 188-204页

作者： Min Cai Shuangzhu Kong Sheng Chen Mengxi Liu Chunxi Lu State Key Laboratory of Heavy Oil Processing China University of PetroleumBeijing102249China China special Equipment Inspection and research institute Beijing102249China

The reasonable reactor design is of great importance for increasing the C_(2) yield(C2H4 and C2H6)of the oxidative coupling of methane(OCM),and the OCM reactor should remove the heat released in reactions quickly and efficiently and minimize the consecutive reaction of ethylene to carbon *** fluidized bed reactor is characterized by excellent heat transfer,superior mass transport,and large handling capacity,while fewer studies focused on large-scale fluidized bed reactors for the OCM ***,large cold-model experiments and computational fluid dynamics simulations were conducted to investigate hydrodynamics and the OCM reaction performance in a large-scale bubbling fluidized bed(BFB)and a large-scale *** the BFB reactor,consecutive reactions of ethylene are acute because of the strong gas back-mixing,high solids holdup,and non-uniform solids *** the consecutive reactions of ethylene are negligible due to the plug flow structure and low solids holdup in the riser ***,both reactors can achieve isothermal operation for the OCM *** C_(2) selectivity of 45.4% and C_(2) yield of 21.1% are obtained in the riser reactor,increasing by 20.3% and 5.8% individually than that in the BFB *** study provides useful information and reference to the OCM reactor designandcommercialization.

关键词： Oxidative coupling of methane Bubbling fluidized bed reactor Riser reactor Hydrodynamics Isothermal operation

A Planning Method for Operational Test of UAV Swarm Based on Mission Reliability

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Computer Modeling in Engineering & Sciences 2024年第8期140卷 1889-1918页

作者： Jingyu Wang Ping Jiang Jianjun Qi College of Systems Engineering National University of Defense TechnologyChangsha410073China beijing special Engineering design Institution Beijing100028China

The unmanned aerial vehicle(UAV)swarm plays an increasingly important role in the modern battlefield,and the UAV swarm operational test is a vital means to validate the combat effectiveness of the UAV *** to the high cost and long duration of operational tests,it is essential to plan the test in *** solve the problem of planning UAV swarm operational test,this study considers the multi-stage feature of a UAV swarm mission,composed of launch,flight and combat stages,and proposes a method to find test plans that can maximize mission ***,a multi-stage mission reliability model for a UAV swarm is proposed to ensure successful implementation of the mission.A multi-objective integer optimization method that considers both mission reliability and cost is then formulated to obtain the optimal test *** study first constructs a mission reliability model for the UAV swarm in the combat ***,the launch stage and flight stage are integrated to develop a complete PMS(Phased Mission Systems)reliability ***,the Binary Decision Diagrams(BDD)and Multi Objective Quantum Particle Swarm Optimization(MOQPSO)methods are proposed to solve the *** optimal plans considering both reliability and cost are *** proposed model supports the planning of UAV swarm operational tests and represents a meaningful exploration of UAV swarm test planning.

关键词： UAV swarm PMS MOQPSO BDD mission reliability operational test planning

Seismic effectiveness evaluation and optimized design of tie up method for securing museum collections

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Earthquake Engineering and Engineering Vibration 2024年第3期23卷 741-763页

作者： Wang Meng Yan Yi Yang Weiguo Liu Pei Ge Jiaqi Ma Botao School of Civil Engineering Beijing Jiaotong UniversityBeijing 100044China beijing’s Key Laboratory of Structural Wind Engineering and Urban Wind Environment Beijing 100044China beijing General Municipal Engineering design&research institute Co. LtdBeijing 100082China China Aviation Planning and design institute(Group)Co.Ltd. Beijing 100120China

To quantify the seismic effectiveness of the most commonly used fishing line tie up method for securing museum collections and optimize fixed strategies for exhibitions,shaking table tests of the seismic systems used for typical museum collection replicas have been carried *** influence of body shape and fixed measure parameters on the seismic responses of replicas and the interaction behavior between replicas and fixed measures have been *** on the results,seismic effectiveness evaluation indexes of the tie up method are *** suggestions for fixed strategies are given,which provide a basis for the exhibition of delicate museum collections considering the principle of minimizing seismic responses and *** analysis results show that a larger ratio of height of mass center to bottom diameter led to more intense rocking *** the initial pretension of fishing lines was conducive to reducing the seismic responses and stress variation of the *** comprehensive consideration of the interaction forces and effective securement,it is recommended to apply 20%of breaking stress as the initial *** specific museum collections that cannot be effectively protected by the independent tie up method,an optimized strategy of a combination of fishing lines and fasteners is recommended.

关键词： tie up method museum collections shaking table test seismic effectiveness optimized design

Adaptive PI Control Based Stability Margin Configuration of Aircraft Control Systems with Unknown System Parameters and Time Delay

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Journal of Systems Science & Complexity 2024年第4期37卷 1507-1525页

作者： ZHANG Zhibing ZHOU Dapeng WANG Yeguang GAO Wanxin ZHANG Yanjun AVIC Shenyang Aircraft design and research institute Shenyang 110035China School of Automation Beijing Institute of TechnologyBeijing 100081China State Key Lab of Autonomous Intelligent Unmanned Systems Beijing Institute of TechnologyBeijing 100081China

The stability margin is a vital indicator for assessing the safety level of aircraft control *** should maintain sufficient stability margin to ensure safety during flight,especially in the process of large maneuver *** stability margin is generally quantified by the Bode diagram,which strictly depends on the system parameters and the open-loop transfer ***,due to the uncertain flight environments,transmission delays of sensors and mode switchings,etc.,there exist large parameter and structure uncertainties in the aircraft control systems,which make it difficult to precisely configure the stability margin to the desired value by the usual control *** address this problem,an indirect adaptive control strategy is proposed in this paper,where an adaptive PI control law with the capability of self-configuration of stability margin is *** developed control law not only achieves stable time-varying command tracking in the time domain,but also is able to automatically configure the phase margin and gain margin in the frequency ***,the simulation of the one-degree-of-freedom roll rate control model of the air vehicle verifies the validity of the proposed control method.

关键词： Adaptive control aircraft control parameter uncertainty stability margin configuration

Tube-based robust reinforcement learning for autonomous maneuver decision for UCAVs

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Chinese Journal of Aeronautics 2024年第7期37卷 391-405页

作者： Lixin WANG Sizhuang ZHENG Haiyin PIAO Changqian LU Ting YUE Hailiang LIU School of Aeronautical Science and Engineering Beihang UniversityBeijing 100191China Shenyang Aircraft design&research institute Shenyang 110035China

Reinforcement Learning(RL)algorithms enhance intelligence of air combat AutonomousManeuver Decision(AMD)policy,but they may underperform in target combat environmentswith *** enhance the robustness of the AMD strategy learned by RL,thisstudy proposes a Tube-based Robust RL(TRRL)***,this study introduces a tube todescribe reachable trajectories under disturbances,formulates a method for calculating tubes basedon sum-of-squares programming,and proposes the TRRL algorithm that enhances robustness byutilizing tube size as a quantitative ***,this study introduces offline techniques forregressing the tube size function and establishing a tube library before policy learning,aiming toeliminate complex online tube solving and reduce the computational burden during ***,an analysis of the tube library demonstrates that the mitigated AMD strategy achievesgreater robustness,as smaller tube sizes correspond to more cautious *** finding highlightsthat TRRL enhances robustness by promoting a conservative *** effectively balanceaggressiveness and robustness,the proposed TRRL algorithm introduces a“laziness factor”as aweight of ***,combat simulations in an environment with disturbances confirm thatthe AMD policy learned by the TRRL algorithm exhibits superior air combat performance comparedto selected robust RL baselines.

关键词： Air combat Autonomous maneuver decision Robust reinforcement learning Tube-based algorithm Combat simulation

Study of interfacial transition zones between magnesium phosphate cement and Portland cement concrete pavement

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Journal of Traffic and Transportation Engineering(English Edition) 2024年第3期11卷 523-537页

作者： Fei Liu Baofeng Pan Changjun Zhou Ge Li Xiaocun Wang Jiaquan Li Faculty of Infrastructure Engineering Dalian University of TechnologyDalian 116024China Tongren City Transportation Bureau Tongren 554300China beijing Civil Aviation design and research institute of China design Group Beijing 101318China

The Portland cement concrete pavement(PCCP)often suffers from different environmental distresses and vehicle load failure,resulting in slab corner fractures,potholes,and other *** repair has become one of the effective ways to open traffic *** this study,a novel type of rapid repair material,basalt fiber reinforced polymer modified magnesium phosphate cement(BFPMPC),is used to rapidly repair ***,the mechanical properties and characteristics of the repair interfaces which are named interfacial transition zones(ITZs)formed by BFPMPC and cement concrete are focused on as a decisive factor for the performance of the rapid *** changing trend of the elastic moduli was studied by nanoindentation experiments in the ITZs with the deconvolution analysis that the elastic moduli of certain kinds of substances can be *** experimental results show that the elastic modulus of ITZ-1 with a width of about20μm can be regarded as 0.098 times of the aggregate,and 0.51 times of the ordinary Portland cement(OPC)*** BFPMPC-OPC mortar ITZ has roughly the same mechanical properties as the ITZ between aggregate and BFPMPC.A multi-scale representative two-dimensional model was established by random aggregate and a two-dimensional extended finite element method(XFEM)to study the mechanical properties of the repair *** simulation results show that the ITZ formed by the interface of BFPMPC and OPC mortar and basalt aggregate is the most vulnerable to failure,which is consistent with the nano-indentation experimental results.

关键词： Portland cement concrete pavement Interfacial transition zone Magnesium phosphate cement Repair interface Nanoindentation Mechanical properties and characteristics

Ru-doped functional porous materials for electrocatalytic water splitting

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Nano research 2024年第3期17卷 982-1002页

作者： Chongao Tian Rui Liu Yu Zhang Wenxiu Yang Bo Wang beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials Advanced Technology Research Institute(Jinan)Advanced Research Institute of Multidisciplinary ScienceSchool of Chemistry and Chemical EngineeringBeijing Institute of TechnologyBeijing 100081China beijing institute of Technology Library Beijing Institute of TechnologyBeijing 100081China

Electrolytic water splitting(EWS)is an attractive and promising technique for the production of hydrogen ***,the sluggish kinetic rate of hydrogen/oxygen evolution reactions leads to a high overpotential and low energy *** to date,Pt/Ir-based nanocatalysts have become the state-of-the-art EWS catalysts,but disadvantages such as high cost and low earth abundance greatly limit their applications in EWS *** an attractive candidate for the Pt/Ir catalysts,series of Ru-based nanomaterials have aroused much attention for their low price,Pt-like hydrogen bond strength,and high EWS *** particular,Ru-doped functional porous materials have been becoming one of the most representative EWS catalysts,which can not only achieve the dispersion and adjustment for active Ru sites,but also simultaneously solve the problems of mass transfer and catalytic conversion in *** this review,the design and preparation strategies of Ru-doped functional porous materials toward EWS in recent years are summarized,including Ru-doped metal organic frameworks(MOFs),Ru-doped porous organic polymers(POPs),and their ***,detailed structure–activity relationships induced by the tuned geometric/electronic structures of Ru-doped functional porous materials are further depicted in this *** but not least,the challenges and perspectives of Ru-doped functional porous materials catalysts are reasonably proposed to provide fresh ideas for the design of Ru-based EWS catalysts.

关键词： Ru-based catalyst functional porous materials electrolytic water splitting oxygen evolution reaction hydrogen evolution reaction