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Introduction to the Special Issue on the Bottleneck of Blockchain Techniques Scalability,Security and Privacy Protection

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Computer Modeling in engineering & Sciences 2024年第12期141卷 1933-1937页

作者： Shen Su Daojing He Neeraj Kumar Cyberspace Institute of Advanced Technology Guangzhou UniversityGuangzhou510006China School of Computer Science and Technology Harbin Institute of Technology(Shenzhen)Shenzhen518055China Department of Computer Science and Engineering Thapar Institute of Engineering and TechnologyPatiala147004India

Blockchain technology has been extensively studied over the past decade as a foundation for decentralized information-sharing platforms due to its promising *** the success of existing blockchain architectures like Bitcoin,Ethereum,Filecoin,Hyperledger Fabric,BCOS,and BCS,current blockchain applications are still quite *** struggles with scenarios requiring high-speed transactions(e.g.,online markets)or large data storage(e.g.,video services)due to consensus efficiency *** restrictions pose risks to investors in blockchain-based economic systems(e.g.,DeFi),deterring current and potential *** protection challenges make it difficult to involve sensitive data in blockchain applications.

关键词： services Ether limitations

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Anticipating the lifespan: Predicting the durability of an anode-supported solid oxide fuel cell short stack over 50,000 h

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Progress in Natural Science:Materials International 2024年第3期34卷 606-613页

作者： Muhammad Zubair Khan Amjad Hussain Seung-Bok Lee Tak-Hyoung Lim Rak-Hyun Song Department of Materials Science & Engineering Pak-Austria Fachhochschule: Institute of Applied Sciences and Technology Hydrogen Energy Research Division Korea Institute of Energy Research Department of Advanced Energy and System Engineering Korea University of Science and Technology (UST)

In the present study, the operational lifetime of a solid oxide fuel(SOFC) short stack is predicted by investigating the performance degradation of both the short stack and its cells throughout 1000 h at 800°C. The short stack and integral cell voltages are continuously measured during the long-term test, with electrochemical impedance spectroscopy(EIS) conducted every 200 h. The short stack voltage decreased rapidly for the initial 200–300 h and afterwards, it decreased at a slow rate due to the increase in the Ohmic and polarization resistances in the same manner. Scanning electron microscopy results show that there is no delamination or cracking among constituent layers of the short-stack cells. The single degradation effects of the Ni coarsening in the anode, cation migration and surface segregation in cathode and oxide scale growth in metallic interconnect mesh are successfully integrated into a comprehensive lifetime prediction model. The experimentally measured voltage degradation data of the short stack fits well with the developed mathematical model and allows the successful prediction of the lifetime up to 50,000 h.

关键词： SOFC Stack Degradation Impedance Lifetime

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Identifying the crystal structure of T 1 precipitates in Al-Li-Cu alloys by ab initio calculations and HAADF-STEM imaging

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Journal of Materials Science & technology 2023年第2期133卷 41-57页

作者： Shuo Wang Xianghai Yang Junsheng Wang Chi Zhang Chengpeng Xue School of Materials Science and Engineering Beijing Institute of TechnologyBeijing 100081China Advanced Research Institute of Multidisciplinary Science Beijing Institute of TechnologyBeijing 100081China

Controversial experimental reports on the crystal structure of T 1 precipitates in Al-Li-Cu alloys have ex-isted for a long time,and all of them can be classified into five *** clarify its ground-state atomic structure,herein,we have combined high-throughput first-principles calculations and CALPHAD,as well as aberration-corrected HAADF-STEM *** the special quasi-random structure(SQS)and supercell approximation(SPA)methods to simulate the local disorder on Al-Cu sub-lattices,we find that none of the present models can satisfy the phase stability in Al-Li-Cu ternary system based on temperature-dependent convex hull *** the cluster expansion(CE)formulas,structural predic-tions derived from the five-frame models were ***,by introducing the vibrational contribution to the free energy at aging temperatures,we proposed a novel ground-state T 1 structure that maintains a coherent relationship with Al-matrix at the<112>Al *** underlying phase transition between the variants of T 1 precipitates was further *** means of ab initio molecular dynamics(AIMD)simulations,we resolved the controversy regarding the number of atomic layers con-stituting the T 1 phase and acknowledged the existence of Al-Li corrugated *** root cause of this structural distortion is triggered by atomic forces and *** work can have an positive impact on the novel fourth generation of Al-Cu-Li alloy designs by engineering the T 1 strengthening phase.

关键词： Al-Cu-Li alloys T 1 precipitates Cluster expansion First-principle calculations ab initio molecular dynamics HAADF-STEM

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MULTI-STEP ACTOR-CRITIC FRAMEWORK FOR REINFORCEMENT LEARNING IN CONTINUOUS CONTROL

Journal of Applied and Numerical Optimization

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Journal of Applied and Numerical Optimization 2023年第2期5卷 189-200页

作者： Huang, Tianyi Chen, Guangfeng Institute of Advanced Technology Westlake Institute for Advanced Study Hangzhou China School of Engineering Westlake University Hangzhou China

Continuous control is an important issue in control theory. It controls an agent to take action in continuous spaces for transiting from one state to another until achieving the desired goal. A useful tool for this issue is the reinforcement learning where an optimal policy is learned for the agent by maximizing the cumulative reward of the state transitions. However, most existing reinforcement learning methods consider only the one-step transition and one-step reward in each state. In this case, it is hard to recognize the information hidden in the sequence of the previous states and accurately estimate the cumulative reward. Therefore, these methods cannot learn the optimal policy both fast and effectively for continuous control. To solve this problem, in this paper, we propose a new framework, called Multi-step Actor-critic Framework (MAF) for reinforcement learning. In MAF, the convolutional deterministic policy is used to learn the information hidden in the sequence of the previous states by convolutional neural networks, and then n-step temporal difference learning is used to accurately estimate the cumulative reward by considering the rewards from n-step states. Based on an effective reinforcement learning method, TD3, the implementation of our MAF is in nTD3. The theoretical analysis and experiment illustrate that our nTD3 can learn the policy not only better but also faster than the existing RL methods for continuous control. © 2023 Journal of Applied and Numerical Optimization.

关键词： Reinforcement learning

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Boosting bidirectional sulfur conversion enabled by introducing boron-doped atoms and phosphorus vacancies in Ni_(2)P for lithium-sulfur batteries

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Journal of Energy Chemistry 2025年第1期100卷 760-769页

作者： Lin Peng Yu Bai Hang Li Meixiu Qu Zhenhua Wang Kening Sun Advanced Research Institute of Multidisciplinary Science Beijing Institute of TechnologyBeijing 100081China Beijing Key Laboratory of Chemical Power Source and Green Catalysis School of Chemistry and Chemical EngineeringBeijing Institute of TechnologyBeijing 100081China

Lithium-sulfur (Li-S) batteries have gained great attention due to the high theoretical energy density and low cost,yet their further commercialization has been obstructed by the notorious shuttle effect and sluggish redox ***,we supply a strategy to optimize the electron structure of Ni_(2)P by concurrently introducing B-doped atoms and P vacancies in Ni_(2)P (Vp-B-Ni_(2)P),thereby enhancing the bidirectional sulfur *** study indicates that the simultaneous introduction of B-doped atoms and P vacancies in Ni_(2)P causes the redistribution of electron around Ni atoms,bringing about the upward shift of d-band center of Ni atoms and effective d-p orbital hybridization between Ni atoms and sulfur species,thus strengthening the chemical anchoring for lithium polysulfides (LiPSs) as well as expediting the bidirectional conversion kinetics of sulfur ***,theoretical calculations reveal that the incorporation of B-doped atoms and P vacancies in Ni_(2)P selectively promotes Li2S dissolution and nucleation ***,the Li-S batteries with Vp-B-Ni_(2)P-separators present outstanding rate ability of 777 m A h g^(-1)at 5 C and high areal capacity of 8.03 mA h cm^(-2)under E/S of 5μL mg^(-1)and sulfur loading of 7.20 mg cm^(-2).This work elucidates that introducing heteroatom and vacancy in metal phosphide collaboratively regulates the electron structure to accelerate bidirectional sulfur conversion.

关键词： B-doped atoms P vacancies Nickel phosphide Bidirectional sulfur conversion Lithium-sulfur batteries

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Silicon photonic Bessel-Gaussian beam generation unlocks new possibilities for long-range sensing

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Light(Science & Applications) 2023年第7期12卷 1178-1179页

作者： Sangsik Kim School of Electrical Engineering Korea Advanced Institute of Science and TechnologyDaejeon 34141Republic of Korea

Concentrically distributed silicon photonic grating arrays generate long-range Besse-Gaussian beams,enabling rotational and range measurements over *** compact and mass-producible chip unlocks new potentials for long-... 详细信息

关键词： Gaussian Bessel beam

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Novel C_(sf)/SiBCN composites prepared by densifying C_(sf)/MA-SiBCN with the PIP process:Oxidation behavior and damage mechanism

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Journal of advanced Ceramics 2024年第5期13卷 666-678页

作者： Wenhao Dou Daxin Li Bingzhu Wang Zhihua Yang Jun Chen Dechang Jia Ralf Riedel Yu Zhou Institute for Advanced Ceramics School of Materials Science and EngineeringHarbin Institute of TechnologyHarbin 150001China Key Laboratory of Advanced Structural-Functional Integration Materials and Green Manufacturing Technology Harbin Institute of TechnologyHarbin 150001China Chongqing Research Institute of HIT Chongqing 401135China Beijing Institute of Control Engineering Beijing 100094China Institut für Materialwissenschaft Technische Universität DarmstadtDarmstadt D-64287Germany School of Materials Science and Engineering Harbin Institute of Technology(Shenzhen)Shenzhen 518055China

To improve the oxidation resistance of short carbon fiber(C_(sf))-reinforced mechanically alloyed SiBCN(MA-SiBCN)(C_(sf)/MA-SiBCN)composites,dense amorphous C_(sf)/SiBCN composites containing both MA-SiBCN and polymer-derived ceramics SiBCN(PDCs-SiBCN)were prepared by repeated polymer infiltration and pyrolysis(PIP)of layered C_(sf)/MA-SiBCN composites at 1100℃,and the oxidation behavior and damage mechanism of the as-prepared C_(sf)/SiBCN at 1300–1600℃ were compared and discussed with those of C_(sf)/*** C_(sf)/MA-SiBCN composites resist oxidation attack up to 1400℃ but fail at 1500℃ due to the collapse of the porous framework,while the PIP-densified C_(sf)/SiBCN composites are resistant to static air up to 1600℃.During oxidation,oxygen diffuses through preexisting pores and the pores left by oxidation of carbon fibers and pyrolytic carbon(PyC)to the interior of the *** to the oxidative coupling effect of the MA-SiBCN and PDCs-SiBCN matrices,a relatively continuous and dense oxide layer is formed on the sample surface,and the interfacial region between the oxide layer and the matrix of the as-prepared composite contains an amorphous glassy structure mainly consisting of Si and O and an incompletely oxidized but partially crystallized matrix,which is primarily responsible for improving the oxidation resistance.

关键词： mechanically alloyed SiBCN(MA-SiBCN) polymer-derived ceramics SiBCN(PDCs-SiBCN) short carbon fiber-reinforced SiBCN(C_(sf)/SiBCN)composites polymer infiltration and pyrolysis(PIP) oxidation damage mechanism

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Insight into the capacity degradation and structural evolution of single-crystal Ni-rich cathodes

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Journal of Energy Chemistry 2024年第8期95卷 68-76,I0003页

作者： Xiaodong Zhang Jiao Lin Ersha Fan Qingrong Huang Su Ma Renjie Chen Feng Wu Li Li Beijing Key Laboratory of Environmental Science and Engineering School of Materials Science and EngineeringBeijing Institute of TechnologyBeijing 100081China Advanced Technology Research Institute Beijing Institute of TechnologyJinan 250300ShandongChina Collaborative Innovation Center of Electric Vehicles in Beijing Beijing 100081China

Single-crystal Ni-rich cathodes are a promising candidate for high-energy lithium-ion batteries due to their higher structural and cycling stability than polycrystalline ***,the phase evolution and capacity degradation of these single-crystal cathodes during continuous lithation/delithation cycling remains *** the mapping relationship between the macroscopic electrochemical properties and the material physicochemical properties is ***,we investigate the correlation between the physical-chemical characteristics,phase transition,and capacity decay using capacity differential curve feature identification and in-situ X-ray spectroscopic *** systematically clarify the dominant mechanism of phase evolution in aging *** high cut-off voltages can mitigate the slow kinetic and electrochemical properties of single-crystal *** also find that second-order differential capacity discharge characteristic curves can be used to identify the crystal structure disorder of Ni-rich *** findings constitute a step forward in elucidating the correlation between the electrochemical extrinsic properties and the physicochemical intrinsic properties and provide new perspectives for failure analysis of layered electrode materials.

关键词： Single-crystal cathodes Capacity decay Phase transition Differential capacity analysis

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Enhancement of strength and ductile-brittle transition temperature of SA508 Gr.3 low-alloy steel by controlling heat accumulation in laser powder-directed energy deposition

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Journal of Materials Science & technology 2024年第35期202卷 240-252页

作者： Wonjong Jeong Young-Bum Chun Suk Hoon Kang Chang Kyu Rhee Chang Hyoung Yoo Seongjin Yoo Hongmul Kim Muhammad Akmal Ho Jin Ryu Department of Nuclear and Quantum Engineering Korea Advanced Institute of Science and TechnologyYuseong-guDaejeon34141Republic of Korea Korea Atomic Energy Research Institute Yuseong-guDaejeon34057Republic of Korea Advanced powder technology team HANA AMTCheongwon-guCheongju-si28126Republic of Korea Department of Material Science and Engineering Korea Advanced Institute of Science and TechnologyYuseong-guDaejeon34141Republic of Korea

The safety and longevity of small modular reactors are affected by reactor pressure vessels,which are complex integral components made of SA508 Gr.3 low-alloy *** this study,the impacts of heat accumulation on the microstructural and mechanical characteristics(tensile properties and Charpy V-notched impact energy)of SA508 Gr.3 steel fabricated using laser powder-directed energy deposition were *** samples were prepared using long raster and short raster scanning strate-gies for changing heat buildup,and the mechanical tests were conducted depending on build *** time-temperature profile measured at a fixed point in the long raster sample showed a lower max-imum temperature and a higher cooling rate,indicating lower heat accumulation compared to that of the short raster *** each build direction,the yield strength of the long raster sample was 45.8%-60.5%higher and its ductile-brittle transition temperature was 76.8-103.8℃ lower than that of the short raster ***,compared to conventionally made samples and without requiring heat treat-ment,the long raster sample exhibited over a 45%increase in yield strength and a 22.7℃ reduction in the ductile-brittle transition *** superior combination in long raster samples is induced by smaller effective grain size,smaller cementite,and a higher pre-existing dislocation *** re-sults emphasize the importance of controlling heat accumulation throughout the additive manufacturing process and provide valuable insights into the use of additive manufacturing for manufacturing reactor pressure vessels in the nuclear industry.

关键词： Reactor pressure vessel Laser powder directed energy deposition SA508 Gr.3 Low-alloy steel Heat accumulation Ductile-brittle transition temperature

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Cl-terminated decoration to modulate the permittivity of MXene for enhanced electromagnetic-absorbing performance

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Journal of Materials Science & technology 2024年第12期179卷 187-197页

作者： Yunfei He Dongdong Liu Qiang Su Bo Zhong Long Xia Xiaoxiao Huang School of Materials Science and Engineering Harbin Institute of Technology at WeihaiWeihai 264009China School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001China MIIT Key Laboratory of Advanced Structural-Functional Integration Materials&Green Manufacturing Technology Harbin Institute of TechnologyHarbin 150001China

The explosive growth of communication technology has given rise to a large number of high-quality electromagnetic wave(EMW)absorbing materials,and single-component materials are often difficult to satisfy the *** this study,we propose an etching method of molten chlorine salts under vac-uum to prepare Cl-terminated MXene(MX-Cl)which can meet the requirements of"thin,light,wide and strong"and realize the application of single-component absorbing *** the X and Ku bands,MX-Cl achieves a strong reflection loss of-42.99 dB and an effective absorption bandwidth of 3.44 GHz with the 1.2 mm matching *** presence of Cl groups restricts the free electron movement of surface-Ti,which controls the conductivity of the MX-Cl and optimizes its *** polarization induced by Ti-Cl,interfacial polarization between MXene layers and multiple scattering effects inside the layers all significantly increase the dielectric loss of the MX-Cl *** study provides a new approach to investigating the effect of single atoms on the dielectric properties of *** work also offers a simple and low-cost process for the preparation of single-component MXene EMW-absorbing materials.

关键词： Cl-terminated MXene Conductivity mechanism Multi-polarization effect Electromagnetic wave absorption

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