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An Improved Thermal Conductivity Measurement Scheme for Macroscopic Graphitic Films Using the Laser Flash Method

Journal of Thermal Science 2024年第4期33卷 1480-1490页

作者： ZHANG Peijuan ming Xin LIU Yingjun WANG Xuelong shi Hang HAO Yuanyuan LU Jiahao LIU zheng LAI Haiwen ZHANG Ying GAO Weiwei XU Zhen GAO Chao MOE Key Laboratory of Macromolecular Synthesis and Functionalization Department of Polymer Science and EngineeringKey Laboratory of Adsorption and Separation Materials&Technologies of Zhejiang ProvinceZhejiang UniversityHangzhou310027China Shanxi-Zheda Institute of Advanced Materials and Chemical Engineering Taiyuan030032China Special Equipment Safety Supervision and Inspection Institute of Jiangsu Province National Graphene Products Quality Inspection and Testing Center(Jiangsu)Wuxi214174China Hangzhou Gaoxi Technol Co. LtdHangzhou311113China China Academy of Aerospace Aerodynamics Beijing100074China

Achieving efficient thermal management urges to exploit high-thermal-conductivity materials to satisfy the boosted demand of heat *** is critical to adopt standardized characterization protocols to evaluate the intrinsic thermal conductivity of thermal management ***,for the most representative laser flash method,the lack of standard measurement methodology and systematic description on the thermal diffusivity and influencing factors has led to significant deviations and confusion of the thermal conduction performance in the emerging thermal management ***,the measurement error factors of thermal diffusivity by the common laser flash analyzer(LFA)are *** high-thermal-conductivity graphitic film(GF)as a typical case,the key factors are analyzed to guide the measurement protocol of related carbon-based thermal management *** basic principle of the LFA measurement,actual pre-processing conditions,instrument parameters setting,and data analysis are elaborated for accurate ***,the graphene thick films and common isotropic materials are also extended to meet various thermal measurement *** on the existing practical problems,we propose a feasible test flow to achieve a unified and standardized thermal conductivity measurement,which is beneficial to the rapid development of carbon-based thermal management materials.

关键词： thermal management graphitic film laser flash method thermal conductivity thermal diffusivity

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Experimental observation of spontaneous symmetry breaking in a quantum phase transition

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Science China(Physics,Mechanics & Astronomy) 2024年第2期67卷 34-39页

作者： Wen Ning Ri-Hua zheng Jia-Hao Lu Fan Wu Zhen-Biao Yang shi-Biao zheng Fujian Key Laboratory of Quantum Information and Quantum Optics College of Physics and Information EngineeringFuzhou UniversityFuzhou 350108China Hefei National Laboratory Hefei 230088China

Spontaneous symmetry breaking(SSB)plays a central role in understanding a large variety of phenomena associated with phase transitions,such as superfluid and *** far,the transition from a symmetric vacuum to a macroscopically ordered phase has been substantially *** process bridging these two distinct phases is critical to understanding how a classical world emerges from a quantum phase transition,but so far remains unexplored in *** here report an experimental demonstration of such a process with a quantum Rabi model engineered with a superconducting *** move the system from the normal phase to the superradiant phase featuring two symmetry-breaking field components,one of which is observed to emerge as the classical *** results demonstrate that the environment-induced decoherence plays a critical role in the SSB.

关键词： quantum phase transition Rabi model spontaneous symmetry breaking superconducting circuit Schrodinger cat states

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Train-induced aerodynamic characteristics of vertical sound barriers influenced by several factors

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Railway Engineering Science 2024年第2期32卷 177-193页

作者： Xiaowei Qiu Xiaozhen Li Jing zheng ming Wang State Key Laboratory of Bridge Intelligent and Green Construction Southwest Jiaotong UniversityChengdu 611756SichuanChina Wind Engineering Key Laboratory of Sichuan Province Southwest Jiaotong UniversityChengdu 611756SichuanChina School of Architecture and Civil Engineering West Anhui UniversityLu’anAnhuiChina

Investigations into the aerodynamic properties of vertical sound barriers exposed to high-speed operations employ computational fluid *** primary focus of this research is to evaluate the influence of train speed and the distance(D)from the track centerline under various operating *** findings elucidate a marked elevation in the aerodynamic effect amplitude on sound barriers as train speeds *** single-train passages,the aerodynamic effect amplitude manifests a direct relationship with the square of the train *** two trains pass each other,the aerodynamic amplitude intensifies due to an additional aerodynamic increment on the sound *** increment exhibits an approximate quadratic correlation with the retrograde train ***,the impact of high-speed trains on sound barrier aerodynamics surpasses that of low-speed trains,and this discrepancy amplifies with larger speed differentials between ***,the train-induced aerodynamic effect diminishes significantly with greater distance(D),with occurrences of pressure coefficient(CP)exceeding the standard thresholds during dual-train *** study culminates in the formulation of universal equations for quantifying the influence of train speed and distance(D)on sound barrier aerodynamic characteristics across various operational scenarios.

关键词： Aerodynamic characteristic Sound barrier Two trains passing each other Distance from track centerline CFD simulation

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The design and engineering strategies of metal tellurides for advanced metal-ion batteries

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Journal of Energy Chemistry 2024年第2期89卷 579-598,I0013页

作者： Wenmiao Zhao Xiaoyuan shi Bo Liu Hiroshi Ueno Ting Deng Weitao zheng Key Laboratory of Automobile Materials of MOE School of Materials Science and EngineeringJilin Provincial International Cooperation Key Laboratory of High-Efficiency Clean Energy MaterialsJilin UniversityChangchun 130012JilinChina Key Laboratory of Polyoxometalate Science of Ministry of Education Northeast Normal UniversityChangchun 130024JilinChina Key Laboratory of Preparation and Application of Environmental Friendly Materials(Jilin Normal University) Ministry of EducationChangchun 130103JilinChina Creative Interdisciplinary Research Division The Frontier Research Institute for Interdisciplinary Sciences(FRIS)Department of ChemistryGraduate School of ScienceTohoku UniversitySendai 980-8578Japan

Owning various crystal structures and high theoretical capacity,metal tellurides are emerging as promising electrode materials for high-performance metal-ion batteries(MBs).Since metal telluride-based MBs are quite new,fundamental issues raise regarding the energy storage mechanism and other aspects affecting electrochemical *** volume expansion,low intrinsic conductivity and slow ion diffusion kinetics jeopardize the performance of metal tellurides,so that rational design and engineering are crucial to circumvent these ***,this review provides an in-depth discussion of recent investigations and progresses of metal tellurides,beginning with a critical discussion on the energy storage mechanisms of metal tellurides in various *** the following,recent design and engineering strategies of metal tellurides,including morphology engineering,compositing,defect engineering and heterostructure construction,for high-performance MBs are *** primary focus is to present a comprehensive understanding of the structural evolution based on the mechanism and corresponding effects of dimension control,composition,electron configuration and structural complexity on the electrochemical *** closing,outlooks and prospects for future development of metal tellurides are *** work also highlights the promising directions of design and engineering strategies of metal tellurides with high performance and low cost.

关键词： Metal tellurides Metal-ion battery Energy storage mechanism Material design and engineering

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Local environment regulation of transition metal dichalcogenide-based single-atom catalysts

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Rare Metals 2024年第9期43卷 4019-4037页

作者： ming-Hui Li Jing Li Xiao-Yu zheng Yao Zhou Advanced Research Institute of Multidisciplinary Science and School of Chemistry and Chemical Engineering Beijing Institute of TechnologyBeijing 100081China Laser Micro/Nano Fabrication Laboratory School of Mechanical EngineeringBeijing Institute of TechnologyBeijing 100081China

Single-atom catalysts have risen significant attention in the realm of green electrocatalytic energy conversion to address energy and environmental sustainability *** metal dichalcogenide(TMD)-based single-atom catalysts are considered highly effective in electrocatalysis due to the TMDs'notable specific surface area,tunable elemental species and efficient utilization of single *** order to enhance electrocatalytic performance,it is imperative to elaborately engineer the local environment surrounding the active sites of single atoms within *** this review,we initially explore the effects of synthesis methods on single-atom active sites and the influence of loading of single atoms on catalytic performance for *** modulation strategies of the local environment surrounding single-atom sites in TMDs are elaborated,including substitution engineering,surface adsorption,vacancies,spatial confinement and dual-atom site *** each modulation strategy,the effects of diverse local environments on various electrocatalytic applications are presented,such as the oxygen evolution reaction,oxygen reduction reaction,nitrogen reduction reaction,CO_(2)reduction reaction and CO ***,this study presents a comprehensive overview of the challenges encountered and the potential directions for the advancement of single-atom catalysts based on TMDs in the realm of electrocatalysis.

关键词： Single-atom catalysts Transition metal dichalcogenide Local environment Electrocatalysis

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Asynchronous Learning-Based Output Feedback Sliding Mode Control for Semi-Markov Jump Systems: A Descriptor Approach

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IEEE/CAA Journal of Automatica Sinica 2024年第6期11卷 1358-1369页

作者： zheng Wu Yiyun Zhao Fanbiao Li Tao Yang Yang shi Weihua Gui School of Automation Central South UniversityChangsha 410083China Power Electronics Machines and Control GroupThe University of NottinghamNottingham NG72RDUK Department of Mechanical Engineering University of VictoriaVictoria BC V8W 3P6Canada IEEE

This paper presents an asynchronous output-feed-back control strategy of semi-Markovian systems via sliding mode-based learning *** with most literature results that require exact prior knowledge of system state and mode information,an asynchronous output-feedback sliding sur-face is adopted in the case of incompletely available state and non-synchronization *** holonomic dynamics of the sliding mode are characterized by a descriptor system in which the switching surface is regarded as the fast subsystem and the system dynamics are viewed as the slow *** upon the co-occurrence of two subsystems,the sufficient stochastic admissibility criterion of the holonomic dynamics is derived by utilizing the characteristics of cumulative distribution ***,a recursive learning controller is formulated to guarantee the reachability of the sliding manifold and realize the chattering reduction of the asynchronous switching and sliding ***,the proposed theoretical method is substantia-ted through two numerical simulations with the practical contin-uous stirred tank reactor and F-404 aircraft engine model,respectively.

关键词： Asynchronous switching learning-based control output feedback semi-Markovian jump systems sliding mode con-trol(SMC).

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Real-time UAV path planning based on LSTM network

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Journal of Systems Engineering and Electronics 2024年第2期35卷 374-385页

作者： ZHANG Jiandong GUO Yukun zheng Lihui YANG Qiming shi Guoqing WU Yong School of Electronics and Information Northwestern Polytechnical UniversityXi’an 710129China The Flight Automatic Control Research Institute of AVIC Xi’an 710065China Military Representative Office of Marine Wuhan Bureau in Luoyang Area Luoyang 471000China

To address the shortcomings of single-step decision making in the existing deep reinforcement learning based unmanned aerial vehicle(UAV)real-time path planning problem,a real-time UAV path planning algorithm based on long shortterm memory(RPP-LSTM)network is proposed,which combines the memory characteristics of recurrent neural network(RNN)and the deep reinforcement learning *** networks are used in this algorithm as Q-value networks for the deep Q network(DQN)algorithm,which makes the decision of the Q-value network has some *** to LSTM network,the Q-value network can use the previous environmental information and action information which effectively avoids the problem of single-step decision considering only the current ***,the algorithm proposes a hierarchical reward and punishment function for the specific problem of UAV real-time path planning,so that the UAV can more reasonably perform path *** verification shows that compared with the traditional feed-forward neural network(FNN)based UAV autonomous path planning algorithm,the RPP-LSTM proposed in this paper can adapt to more complex environments and has significantly improved robustness and accuracy when performing UAV real-time path planning.

关键词： deep Q network path planning neural network unmanned aerial vehicle(UAV) long short-term memory(LSTM)

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Passive particles driven by self-propelled particle:The wake effect

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Chinese Physics B 2024年第4期33卷 500-507页

作者：郑凯选汪静文王世锋聂德明 Institute of Fluid Mechanics China Jiliang UniversityHangzhou 310018China Department of Mechanical Engineering Hangzhou Vocational&Technical CollegeHangzhou 310018China

This work focuses on numerically studying hydrodynamic interaction between a passive particle and a self-propelled particle,termed a squirmer,by using a two-dimensional lattice Boltzmann method(LBM).It is found that the squirmer can capture a passive particle and propel it simultaneously,provided the passive particle is situated within the squirmer's *** research shows that the critical capture distance,which determines whether the particle is captured,primarily depends on the intensity of the squirmer's *** stronger dipolarity of squirmer results in an increased critical capture ***,the Reynolds number is found to have minimal influence on this ***,the passive particle,when driven by the squirmer's wake,contributes to a reduction in the squirmer's *** results in a mutual acceleration for both *** findings can provide valuable perspectives for formulating the principles of reducing the drag of micro-swimmers and help to achieve the goal of using micro-swimmers to transport goods without physical tethers.

关键词： lattice Boltzmann method(LBM) self-propelled particles particle-laden flow

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Effect of ginsenoside Rg1 on hematopoietic stem cells in treating aplastic anemia in mice via MAPK pathway

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World Journal of Stem Cells 2024年第5期16卷 591-603页

作者： Jin-Bo Wang ming-Wei Du Yan zheng Internal Medicine of Traditional Chinese Medicine Tongde Hospital of Zhejiang ProvinceHangzhou 310012Zhejiang ProvinceChina Institute of Cardiovascular Disease Shuguang Hospital Affiliated to Shanghai University of Traditional Chinese MedicineShanghai 201203China Shanghai Key Laboratory of Molecular Medical Mycology Second Affiliated Hospital of Naval Medical UniversityShanghai 200003China Shanghai Key Laboratory of Traditional Chinese Clinical Medicine Shanghai 201203China Department of Hepatic The Xixi Hospital of Hangzhou Affiliated to Zhejiang University of Traditional Chinese MedicineHangzhou 310023Zhejiang ProvinceChina

BACKGROUND Aplastic anemia(AA)presents a significant clinical challenge as a life-threatening condition due to failure to produce essential blood cells,with the current the-rapeutic options being notably *** To assess the therapeutic potential of ginsenoside Rg1 on AA,specifically its protective effects,while elucidating the mechanism at *** We employed a model of myelosuppression induced by cyclophosphamide(CTX)in C57 mice,followed by administration of ginsenoside Rg1 over 13 *** invest-igation included examining the bone marrow,thymus and spleen for pathological changes via hematoxylin-eosin ***,orbital blood of mice was collected for blood routine *** cytometry was employed to identify the impact of ginsenoside Rg1 on cell apoptosis and cycle in the bone marrow of AA ***,the study further evaluated cytokine levels with enzyme-linked immunosorbent assay and analyzed the expression of key proteins in the MAPK signaling pathway via western *** Administration of CTX led to significant damage to the bone marrow’s structural integrity and a reduction in hematopoietic cells,establishing a model of *** Rg1 successfully reversed hematopoietic dysfunction in AA *** comparison to the AA group,ginsenoside Rg1 provided relief by reducing the induction of cell apoptosis and inflammation factors caused by ***,it helped alleviate the blockade in the cell *** with ginsenoside Rg1 significantly alleviated myelosuppression in mice by inhibiting the MAPK signaling *** This study suggested that ginsenoside Rg1 addresses AA by alleviating myelosuppression,primarily through modulating the MAPK signaling pathway,which paves the way for a novel therapeutic strategy in treating AA,highlighting the potential of ginsenoside Rg1 as a beneficial intervention.

关键词： Aplastic anemia Ginsenoside Rg1 Myelosuppression MAPK signaling pathway Bone marrow Hematopoietic stem cells

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Nano-Au-decorated hierarchical porous cobalt sulfide derived from ZIF-67 toward optimized oxygen evolution catalysis:Important roles of microstructures and electronic modulation

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Carbon Energy 2024年第5期6卷 1-14页

作者： Hongyu Gong Guanliang Sun Wenhua shi Dongwei Li Xiangjun zheng Huan shi Xiu Liang Ruizhi Yang Changzhou Yuan Department of New Energy Materials School of Environmental and Chemical EngineeringJiangsu University of Science and TechnologyZhenjiangJiangsuChina Advanced Materials Institute Qilu University of Technology(Shandong Academy of Sciences)JinanShandongChina Shandong Saikesaisi Hydrogen Energy Co. Ltd.JinanShandongChina Department of Materials Science and Engineering School of Materials Science&EngineeringUniversity of JinanJinanShandongChina Department of New Energy Science and Engineering College of EnergySoochow Institute for Energy and Materials InnovationsSoochow UniversitySuzhouJiangsuChina

Enhancing both the number of active sites available and the intrinsic activity of Co-based electrocatalysts simultaneously is a desirable ***,a ZIF-67-derived hierarchical porous cobalt sulfide decorated by Au nanoparticles(NPs)(denoted as HP-Au@CoxSy@ZIF-67)hybrid is synthesized by low-temperature sulfuration *** well-defined macroporous-mesoporous-microporous structure is obtained based on the combination of polystyrene spheres,as-formed CoxSy nanosheets,and ZIF-67 *** novel three-dimensional hierarchical structure significantly enlarges the three-phase interfaces,accelerating the mass transfer and exposing the active centers for oxygen evolution *** electronic structure of Co is modulated by Au through charge transfer,and a series of experiments,together with theoretical analysis,is performed to ascertain the electronic modulation of Co by ***,HP-Au@CoxSy@ZIF-67 catalysts with different amounts of Au were synthesized,wherein Au and NaBH4 reductant result in an interesting“competition effect”to regulate the relative ratio of Co^(2+)/Co^(3+),and moderate Au assists the electrochemical performance to reach the highest ***,the optimized HP-Au@CoxSy@ZIF-67 exhibits a low overpotential of 340 mV at 10 mA cm^(-2)and a Tafel slope of 42 mV dec-1 for OER in 0.1 M aqueous KOH,enabling efficient water splitting and Zn-air battery *** work here highlights the pivotal roles of both microstructural and electronic modulation in enhancing electrocatalytic activity and presents a feasible strategy for designing and optimizing advanced electrocatalysts.

关键词： Au nanoparticles cobalt sulfide electronic modulation hierarchical porous structure oxygen evolution reaction

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