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Nitrogen–sulfur co-doped porous carbon derived from asphalt as efficient catalyst for oxygen reduction

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Rare Metals 2024年第1期43卷 380-388页

作者： Jing-Sheng Ma Ming-zai wu Ling Chen Li-Xing zhang Ying Xiong Key Laboratory of Structure and Functional Regulation of Hybrid Materials Ministry of EducationInstitute of EnergyHefei Comprehensive National Science CenterAnhui UniversityHefei 230601China

As an environment-friendly and low-cost petrochemical by-product, asphalt has great potential in the preparation of metal-free oxygen reduction electrocatalysts with excellent performance and outstanding stability. In this paper, we converted asphalt into porous carbon nanosheets by a simple activation method, using potassium citrate as the swelling agent.

关键词： stability porous catalyst

Ignition processes and characteristics of charring conductive polymers with a cavity geometry in precombustion chamber for applications in micro/nano satellite hybrid rocket motors

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Defence Technology（防务技术） 2024年第2期32卷 55-66页

作者： Zhiyuan zhang Hanyu Deng Wenhe Liao Bin Yu zai Yu Nanjing University of Science and Technology Nanjing 210094China

The arc ignition system based on charring polymers has advantages of simple structure,low ignition power consumption and multiple ignitions,which bringing it broadly application prospect in hybrid propulsion system of micro/nano ***,charring polymers alone need a relatively high input voltage to achieve pyrolysis and ignition,which increases the burden and cost of the power system of micro/nano satellite in practical *** conductive substance into charring polymers can effectively decrease the conducting voltage which can realize low voltage and low power consumption repeated ignition of arc ignition *** this paper,a charring conductive polymer ignition grain with a cavity geometry in precombustion chamber,which is composed of PLA and multiwall carbon nanotubes(MWCNT)was *** detailed ignition processes were analyzed and two different ignition mechanisms in the cavity of charring conductive polymers were *** ignition characteristics of charring conductive polymers were also investigated at different input voltages,ignition grain structures,ignition locations and injection schemes in a visual ignition *** results demonstrated that the ignition delay and external energy required for ignition were inversely correlated with the voltages applied to ignition ***,the incremental depth of cavity shortened the ignition delay and external energy required for ignition while accelerated the propagation of *** the depth of cavity increased from 2 to 6 mm(at 50 V),the time of flame propagating out of ignition grain changed from 235.6 to 108 ms,and values of mean ignition delay time and mean external energy required for ignition decreased from 462.8 to 320 ms and 16.2 to 10.75 J,*** rear side of the cavity was the ideal ignition position which had a shorter ignition delay and a faster flame propagation speed in comparison to other ignition *** to direct injection scheme,swirlin

关键词： Micro/nano satellite hybrid propulsion Arc ignition Charring conductive polymer Ignition mechanism Ignition characteristic Repeated ignition

New low-rank optimization model and algorithms for spectral compressed sensing

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Science China Mathematics 2024年

作者： zai Yang Xunmeng wu Zongben Xu School of Mathematics and Statistics Xi'an Jiaotong University

In this paper,we investigate the recovery of an undamped spectrally sparse signal and its spectral components from a set of regularly spaced samples within the framework of spectral compressed sensing and *** show that the existing Hankel-based optimization methods suffer from the fundamental limitation that the prior of undampedness cannot be *** propose a new low-rank optimization model partially inspired by forward-backward processing for line spectral estimation and show its capability to restrict the spectral poles to the unit *** present convex relaxation approaches with the model and show their provable accuracy and robustness to bounded and sparse *** our results are generalized from one-dimensional to arbitrary-dimensional spectral compressed *** simulations are provided to corroborate our analysis and show the efficiency of our model and the advantageous performance of our approach in terms of accuracy and resolution compared with the state-of-the-art Hankel and atomic norm methods.

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Dual-ion carrier storage through Mg^(2+) addition for high-energy and long-life zinc-ion hybrid capacitor

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International Journal of Minerals,Metallurgy and Materials 2024年第1期31卷 179-185页

作者： Junjie zhang Xiang wu School of Materials Science and Engineering Shenyang University of TechnologyShenyang 110870China

Cation additives can efficiently enhance the total electrochemical capabilities of zinc-ion hybrid capacitors (ZHCs).However their energy storage mechanisms in zinc-based systems are still under ***,we modulate the electrolyte and achieve dual-ion storage by adding magnesium *** we assemble several Zn//activated carbon devices with different electrolyte concentrations and investigate their electrochemical reaction dynamic *** zinc-ion capacitor with Mg^(2+)mixed solution delivers 82 mAh·g^(-1)capacity at 1 A·g^(-1) and maintains 91%of the original capacitance after 10000 *** is superior to the other assembled zinc-ion devices in single-component *** finding demonstrates that the double-ion storage mechanism enables the superior rate performance and long cycle lifetime of ZHCs.

关键词： zinc-ion hybrid capacitor MgSO_(4) electrolyte rate performance storage mechanism

Comparative Study on Different Methods for Prediction of Thermal Insulation Performance of Thermal Barrier Coating Used on Turbine Blades

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Journal of Thermal Science 2024年第1期33卷 172-189页

作者： zhang Zhixin ZENG wu zhang Xiaodong ZENG Yuntao Advanced Gas Turbine Laboratory Institute of Engineering ThermophysicsChinese Academy of SciencesBeijing 100190China Key Laboratory of Advanced Energy and Power Institute of Engineering ThermophysicsChinese Academy of SciencesBeijing 100190China Innovation Academy for Light-duty Gas Turbine Chinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China

As turbine inlet temperature gets higher and higher,thermal barrier coating(TBC) is more and more widely used in turbine *** turbine blades with TBC,it is of great significance to evaluate the temperature distribution of its substrate metal quickly and accurately,especially during the design *** different degrees of simplification such as whether to consider the change of the geometric size of the fluid domain by TBC and whether to consider the planar heat conduction in TBC,three different methods used in conjugate heat transfer(CHT) simulation to model the TBC of the turbine blades have been developed and widely used by ***,little research has been conducted to investigate the influence of the three methods on the temperature distribution of turbine *** fill this gap,three geometric models were *** are a solid conduction model with a substrate metal layer and a TBC layer,a transonic turbine vane with internal cooling and TBC,and a plate cylindrical film hole cooling model with *** methods were used in these geometric models and their differences were carefully analyzed and *** result shows that for the conduction model used in this paper,with the same TBC surface temperature distribution,the difference between the three methods is very small and can be *** a transonic turbine vane with internal cooling,regarding the local maximum temperature of the substrate-TBC interface,the largest difference between the method in which TBC is considered as a thermal resistance or a virtual layer of cells and the method in which three-dimensional heat conduction equation of TBC is solved occurs at the trailing *** difference near the leading edge is below *** employed to the film cooling model,the difference of the laterally averaged temperature of the substrate-TBC interface can be 8 K which is mainly due to the change of the length to diameter ratio of the film cooling hole by *** the substrate

关键词： turbine blade thermal barrier coating conjugate heat transfer film cooling hole

Integrated strategy for real-time wind power fluctuation mitigation and energy storage system control

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Global Energy Interconnection 2024年第1期7卷 71-81页

作者： Yu zhang Yongkang zhang Tiezhou wu Hubei University of Technology Hubei Key Laboratory of Solar Energy Efficient Utilization and Energy Storage Operation ControlHubeiWuhan 430068P.R.China

To address the impact of wind-power fluctuations on the stability of power systems,we propose a comprehensive approach that integrates multiple strategies and methods to enhance the efficiency and reliability of a ***,we employ a strategy that restricts long-and short-term power output deviations to smoothen wind power fluctuations in real ***,we adopt the sliding window instantaneous complete ensemble empirical mode decomposition with adaptive noise(SW-ICEEMDAN)strategy to achieve real-time decomposition of the energy storage power,facilitating internal power distribution within the hybrid energy storage ***,we introduce a rule-based multi-fuzzy control strategy for the secondary adjustment of the initial power allocation commands for different energy storage *** simulation validation,we demonstrate that the proposed comprehensive control strategy can smoothen wind power fluctuations in real time and decompose energy storage *** with traditional empirical mode decomposition(EMD),ensemble empirical mode decomposition(EEMD),and complete ensemble empirical mode decomposition with adaptive noise(CEEMDAN)decomposition strategies,the configuration of the energy storage system under the SW-ICEEMDAN control strategy is more ***,the state-of-charge of energy storage components fluctuates within a reasonable range,enhancing the stability of the power system and ensuring the secure operation of the energy storage system.

关键词： SW-ICEEMDAN HESS Real-time smoothing Rule-based multi-fuzzy control SoC

Mutual aid instead of mutual restraint:interactive probing for topological charge and phase of a vortex beam of large aberrations

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Photonics Research 2024年第1期12卷 172-182页

作者： SHENGYANG wu BENLI YU LEI zhang Key Laboratory of Opto-electronic Information Acquisition and Manipulation Ministry of EducationAnhui UniversityHefei 230601China Information Materials and Intelligent Sensing Laboratory of Anhui Province Anhui UniversityHefei 230601China

An imperfect propagation environment or optical system would introduce wavefront aberrations to vortex *** phase aberrations and orbital angular momentum in a vortex beam are proved to be mutually restrictive in parameter *** make traditional topological charge(TC)probing methods ineffective while the phase singularity makes phase retrieval difficult due to the aliasing between the wrapped phase jump and the vortex phase *** interactive probing method is proposed to make measurements of the aberrated phase and orbital angular momentum in a vortex beam assist rather than hinder each *** phase unwrapping is liberated from the phase singularity by an annular shearing interference technique while the TC value is determined by a Moirétechnique immune to *** and experimental results proving the method effective are *** is of great significance to judge the characteristics of vortex beams passing through nonideal environments and optical systems.

关键词： vortex topological beam

2-Independent Domination in Trees

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Journal of the Operations Research Society of China 2024年第2期12卷 485-494页

作者： Gang zhang Baoyindureng wu College of Mathematics and System Sciences Xinjiang UniversityUrumqi830046XinjiangChina

A subset D■V(G)in a graph G is a dominating set if every vertex in V(G)I D is adjacent to at least one vertex of S.A subset S■V(G)in a graph G is a 2-independent set if△(G[S])<*** 2-independence numberα2(G)is the order of a largest 2-independent set in ***,a subset D■V(G)in a graph G is a 2-independent dominating set if D is both dominating and *** 2-independent domination number i^(2)(G)is the order of a smallest 2-independent dominating set in *** this paper,we characterize all trees T of order n with i^(2)(T)=n/***,we prove that for any tree T of order n≥2,i^(2)(T)≤2/3α2(T),and this bound is sharp.

关键词： Domination-Independent domination 2-Independent domination:2-Independence.Trees

Facilitating prelithiation of silicon carbon anode by localized high-concentration electrolyte for high-rate and long-cycle lithium storage

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Carbon Energy 2024年第6期6卷 216-233页

作者： Yuanxing zhang Borong wu Jiaying Bi Xinyu zhang Daobin Mu Xin-Yu zhang Ling zhang Yao Xiao Feng wu School of Materials Science and Engineering Beijing Institute of TechnologyBeijingChina Chongqing Innovation Center Beijing Institute of TechnologyChongqingChina College of New Energy Xi′an Shiyou UniversityXi′anChina Institute for Carbon Neutralization College of Chemistry and Materials EngineeringWenzhou UniversityWenzhouChina Key Laboratory of Advanced Energy Materials Chemistry(Ministry of Education) Nankai UniversityTianjinChina

The commercialization of silicon-based anodes is affected by their low initial Coulombic efficiency(ICE)and capacity decay,which are attributed to the formation of an unstable solid electrolyte interface(SEI)***,a feasible and cost-effective prelithiation method under a localized highconcentration electrolyte system(LHCE)for the silicon-silica/graphite(Si-SiO_(2)/C@G)anode is designed for stabilizing the SEI layer and enhancing the *** thin SiO_(2)/C layers with-NH2 groups covered on nano-Si surfaces are demonstrated to be beneficial to the prelithiation process by density functional theory calculations and electrochemical *** SEI formed under LHCE is proven to be rich in ionic conductivity,inorganic substances,and flexible organic ***,faster Li+transportation across the SEI further enhances the prelithiation effect and the rate performance of Si-SiO_(2)/C@G *** also leads to uniform decomposition and high stability of the SEI with abundant organic *** a result,the prepared anode shows a high reversible specific capacity of 937.5 mAh g^(-1)after 400 cycles at a current density of 1 *** 811‖Li-SSGLHCE full cell achieves a high-capacity retention of 126.15 mAh g^(-1)at 1 C over 750 cycles with 84.82%ICE,indicating the great value of this strategy for Si-based anodes in large-scale applications.

关键词： localized high-concentration electrolytes prelithiation SEI layer silicon anode