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Nonlinear Seebeck and Peltier effects in a Majorana nanowire coupled to leads

Chinese Physics B 2024年第7期33卷 547-552页

作者：迟锋刘佳付振国刘黎明易子川 School of Electronic and Information Engineering UESTC of ChinaZhongshan InstituteZhongshan 528400China School of Science Inner Mongolia University of Science and TechnologyBaotou 014010China Institute of Applied Physics and Computational Mathematics Beijing 100088China

We theoretically study nonlinear thermoelectric transport through a topological superconductor nanowire hosting Majorana bound states(MBSs) at its two ends, a system named as Majorana nanowire(MNW). We consider that the MNW is coupled to the left and right normal metallic leads subjected to either bias voltage or temperature gradient. We focus our attention on the sign change of nonlinear Seebeck and Peltier coefficients induced by mechanisms related to the MBSs, by which the possible existence of MBSs might be proved. Our results show that for a fixed temperature difference between the two leads, the sign of the nonlinear Seebeck coefficient(thermopower) can be reversed by changing the overlap amplitude between the MBSs or the system equilibrium temperature, which are similar to the cases in linear response regime. By optimizing the MBS–MBS interaction amplitude and system equilibrium temperature, we find that the temperature difference may also induce sign change of the nonlinear thermopower. For zero temperature difference and finite bias voltage, both the sign and magnitude of nonlinear Peltier coefficient can be adjusted by changing the bias voltage or overlap amplitude between the MBSs. In the presence of both bias voltage and temperature difference, we show that the electrical current at zero Fermi level and the states induced by overlap between the MBSs keep unchanged, regardless of the amplitude of temperature difference. We also find that the direction of the heat current driven by bias voltage may be changed by weak temperature difference.

关键词： quantum dot nonlinear Seebeck coefficient Peltier coefficient Majorana bound states sign change

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Construction of flower-like MoS_(2)decorated on Cu doped CoZn-ZIF derived N-doped carbon as superior microwave absorber

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Nano research 2024年第9期17卷 8250-8260页

作者： Yun Han Di Lan Mengjun Han Zihao Xia Jiaxiao Zou Zirui Jia College of Chemistry and Chemical Engineering Qingdao UniversityQingdao 266071China School of Materials Science and Engineering Hubei University of Automotive TechnologyShiyan 442002China

The rational design of composition nanostructures and morphologies of the carbon-based composites materials has a significant potential for tuning electromagnetic parameters and thereby improving their performance as electromagnetic wave(EMW)*** this work,the flower-like Cu/Co-NC/MoS_(2)(NC=N-doped carbon skeleton)composites were successfully prepared by employing CuCoZn-ZIF(ZIF=zeolitic imidazolate framework)as precursor with subsequent annealing and hydrothermal *** unique flower-like morphology and electromagnetic synergy strategy between components enable the as-obtained Cu/Co-NC/MoS_(2)composites to exhibit outstanding microwave absorption ***,the minimum reflection loss of Cu/Co-NC/MoS_(2)reaches-54.36 dB at 2.7 *** the thickness reduces to 2.2 mm,the maximum effective absorption bandwidth can be achieved as large as 6.72 *** research develops useful ideas for optimizing multicomponent microwave absorbing materials.

关键词： ternary metal-organic frameworks(MOFs) MoS_(2) flower-like morphology microwave absorption

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Accelerating Asteroidal Period and Pole Inversion from Multiple Lightcurves Using Parallel Differential Evolution and Cellinoid Shape Model

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research in Astronomy and Astrophysics 2024年第4期24卷 271-286页

作者： Yong-Xiong Zhang Wen-Xiu Guo Xiao-Ping Lu Hua Zheng Hai-Bin Zhao Jun Tian Wei-Lin Wang School of Engineering Guangzhou College of Technology and BusinessGuangzhou 510850China School of Computer Science and Engineering Macao University of Science and TechnologyTaipaMacao 999078China School of Mathematics and Statistics Shaoguan UniversityShaoguan 512099China State Key Laboratory of Lunar and Planetary Sciences Macao University of Science and TechnologyMacao 999078China Key Laboratory of Planetary Sciences Purple Mountain ObservatoryCASNanjing 210023China

Determining asteroid properties provides valuable physical insights but inverting them from photometric lightcurves remains computationally *** paper presents a new approach that combines a simplified Cellinoid shape model with the Parallel Differential Evolution(PDE)algorithm to accelerate *** PDE algorithm is more efficient than the Differential Evolution algorithm,achieving an extraordinary speedup of 37.983 with 64 workers on multicore *** PDE algorithm accurately derives period and pole values from simulated *** analysis of real asteroid lightcurves validates the method’s reliability:in comparison with results published elsewhere,the PDE algorithm accurately recovers the rotational periods and,given adequate viewing geometries,closely matches the pole *** PDE approach converges to solutions within 20,000 iterations and under one hour,demonstrating its potential for large-scale data *** work provides a promising new tool for unveiling asteroid physical properties by overcoming key computational bottlenecks.

关键词： methods:numerical minor planets asteroids:general techniques:photometric astrom

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A Review on the Security of the Ethereum-Based DeFi Ecosystem

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Computer Modeling in Engineering & Sciences 2024年第4期139卷 69-101页

作者： Yue Xue Dunqiu Fan Shen Su Jialu Fu Ning Hu Wenmao Liu Zhihong Tian Cyberspace Institute of Advanced Technology Guangzhou UniversityGuanzhou510000China innovation Center NSFOCUS Inc.Beijing100089China Engineering research Center of Integration and Application of Digital Learning Technology Ministry of EducationBeijing100816China

Decentralized finance(DeFi)is a general term for a series of financial products and *** is based on blockchain technology and has attracted people’s attention because of its open,transparent,and intermediary *** them,the DeFi ecosystem based on Ethereum-based blockchains attracts the most ***,the current decentralized financial system built on the Ethereum architecture has been exposed to many smart contract vulnerabilities during the last few ***,we believe it is time to improve the understanding of the prevailing Ethereum-based DeFi ecosystem security *** that end,we investigate the Ethereum-based DeFi security issues:1)inherited from the real-world financial system,which can be solved by macro-control;2)induced by the problems of blockchain architecture,which require a better blockchain platform;3)caused by DeFi invented applications,which should be focused on during the project *** on that,we further discuss the current solutions and potential directions ofDeFi *** to our research,we could provide a comprehensive vision to the research community for the improvement of Ethereum-basedDeFi ecosystem security.

关键词： Blockchain smart contract decentralized finance DeFi security

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A review on Bi_(2)WO_(6)-based photocatalysts synthesis, modification, and applications in environmental remediation, life medical, and clean energy

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Frontiers of Environmental Science & Engineering 2024年第7期18卷 87-108页

作者： Wei Mao Xuewu Shen Lixun Zhang Yang Liu Zehao Liu Yuntao Guan guangdong Provincial Engineering Technology research Center for Urban Water Cycle and Water Environment Safety Tsinghua Shenzhen International Graduate SchoolTsinghua UniversityShenzhen 518055China State Environmental Protection Key Laboratory of Microorganism Application and Risk Control School of EnvironmentTsinghua UniversityBeijing 100084China

Photocatalysis has emerged a promising strategy to remedy the current energy and environmental crisis due to its ability to directiy convert clean solar energy into chemical *** tungstate(Bi_(2)WO_(6))has been shown to be an excellent visible light response,a well-defined perovskite crystal structure,and an abundance of oxygen atoms(providing efficient channels for photogenerated carrier transfer)due to their suitable band gap,effective electron migration and separation,making them ideal *** has been extensively applied as photocatalyst in aspects including pollutant removal,carbon dioxide reduction,solar hydrogen production,ammonia synthesis by nitrogen photocatalytic reduction,and cancer *** this review,the fabrication and application of Bi_(2)WO_(6) in photocatalysis were comprehensively *** photocatalytic properties of BizwO-based materials were significantly enhanced by carbon modification,the construction of heterojunctions,and the atom doping to improve the photogenerated carrier migration rate,the number of surface active sites,and the photoexcitation ability of the *** addition,the potential development directions and the existing challenges to improve the photocatalytic performance of Bi_(2)WO_(6)-based materials were discussed.

关键词： Bismuth tungstate Synthesis and modification Photocatalytic application Environmental remediation Clean energy Medical science

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Dimensional reduction enhances photocatalytic carbon dioxide reduction performance of metal-organic frameworks

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Nano research 2024年第5期17卷 3653-3659页

作者： Kaiyue Ma Jixin Li Jinlu Liu Chunguang Li Zhan Shi Shouhua Feng State Key Laboratory of Inorganic Synthesis and Preparative Chemistry College of ChemistryJilin UniversityChangchun 130012China

Metal-organic frameworks(MOFs)have shown significant potential as *** has been widely assumed that all catalytic active sites within MOFs are functional in photocatalytic reactions but for a three-dimensional MOF,whether the internal catalytic active sites can effectively absorb light and actively contribute to photocatalytic reactions remains to be *** this context,we synthesized a two-dimensional nanosheet MOF(2D-MOF)and a three-dimensional bulk MOF(3D-MOF)composed of Zr^(6) clusters and tetracarboxylic porphyrin(TCPP)by the approach described in the ***(bpy)(CO)^(3)Cl(bpy=2,2’-bipyridine),which has remarkable CO_(2) photoreduction ability,was introduced to the two MOFs to create two new photocatalysts 2D-MOF-Re and 3D-MOF-Re,*** CO_(2) reduction experiments show that based on the equal number of catalytic active sites,the CO turnover number(TON)of 2D-MOF-Re reaches 27.8 in 6 h,which is 50 times that of *** result shows that certain catalytic active sites inside the bulk MOF are inactive due to the inability to absorb *** study illuminates the potential of the dimensional reduction approach in the design of photocatalysts to exploit the capabilities fully.

关键词： photocatalysis CO_(2)reduction metal-organic frameworks(MOFs) nanosheets light absorption

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Active self-training for weakly supervised 3D scene semantic segmentation

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Computational Visual Media 2024年第3期10卷 425-438页

作者： Gengxin Liu Oliver van Kaick Hui Huang Ruizhen Hu College of Computer Science&Software Engineering Shenzhen UniversityShenzhen 518060China School of Computer Science Carleton UniversityOttawa K1S 5B6Canada

Since the preparation of labeled datafor training semantic segmentation networks of pointclouds is a time-consuming process, weakly supervisedapproaches have been introduced to learn fromonly a small fraction of data. These methods aretypically based on learning with contrastive losses whileautomatically deriving per-point pseudo-labels from asparse set of user-annotated labels. In this paper, ourkey observation is that the selection of which samplesto annotate is as important as how these samplesare used for training. Thus, we introduce a methodfor weakly supervised segmentation of 3D scenes thatcombines self-training with active learning. Activelearning selects points for annotation that are likelyto result in improvements to the trained model, whileself-training makes efficient use of the user-providedlabels for learning the model. We demonstrate thatour approach leads to an effective method that providesimprovements in scene segmentation over previouswork and baselines, while requiring only a few userannotations.

关键词： semantic segmentation weakly supervised self-training active learning

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Effects of BN on the Mechanical and Thermal Properties of PP/BN Composites

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Journal of Wuhan University of Technology(Materials Science) 2024年第2期39卷 345-352页

作者：陈厚振王艳芝 NAN Yu WANG Xu YUE Xianyang ZHANG Yifei FAN Huiling School of Textiles Zhongyuan University of TechnologyZhengzhou 451191China Kaifeng Power Supply Company State Grid Henan Electric Power CompanyKaifeng 475000China School of Materials Science and Engineering Zhejiang University of TechnologyHangzhou 310014China Zhengzhou Hengtian Copper Co. Ltd.Zhengzhou 451100China

In order to explore the thermal conductivity of polypropylene(PP)/hexagonal boron nitride(BN) composites,PP composites filled with different proportions of BN were prepared through extrution compounding,injection moulding and compression *** composites were filled with BN particles of 5 and 20 μm respectively,and their mass fractions in composites were *** of BN was varied from 0 to 25wt% in steps of 5wt%.The effects of BN filler on mechanical properties of the composites were *** thermal behaviors were studied using DSC and TGA,and the thermal conductivity was also investigated by Laser Flash Device and the Model of 3D Heat Conduction *** experimental results show that impact strength of PP/BN can be enhanced with the addition of BN,but that composites exhibit lower breaking elongation & tensile strength when compared to unfilled *** is found that mass fraction of BN influenced the final thermal stability and degree of crystallization of PP matrix,the degree of crystallization of PP with 15wt% of 20 μm BN can be improved by 25% than neat ***,crystallization temperatures of PP composites are elevated by about 10 ℃.The thermal conductivity results demonstrate that the maximum value of the thermal conductivity is achieved from PP/BN with 20wt% of 20 μm BN,higher than that of pure PP by 95.65%,close to the simulation one.

关键词： thermal properties polypropylene composites hexagonal boron nitride

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Ancient mitochondrial genome depicts sheep maternal dispersal and migration in Eastern Asia

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Journal of Genetics and Genomics 2024年第1期51卷 87-95页

作者： Liu Yang Xing Zhang Yaning Hu Piao Zhu Hua Li Zhenyu Peng Hai Xiang Xinying Zhou Xingbo Zhao National Engineering Laboratory for Animal Breeding Key Laboratory of AnimalGeneticsBreeding and ReproductionMinistry of Agriculture and Rural AffairsCollege of Animal Science and TechnologyChina Agricultural UniversityBeijing 100193China guangdong Provincial Key Laboratory of Animal Molecular Design and Precise Breeding School of Life Science and EngineeringFoshan UniversityFoshanGuangdong 528225China State Key Laboratory of Agricultural Genomics BGI-ShenzhenShenzhenGuangdong 518083China Key Laboratory of Vertebrate Evolution and Human Origins Institute of Vertebrate Paleontology and PaleoanthropologyChinese Academy of SciencesBeijing 100044China

Sheep have been one of the most important groups of animals since ancient ***,the knowledge of their migration routes and genetic relationships is still poorly *** investigate sheep maternal migration histories alongside Eurasian communications routes,in this study,we obtain mitochondrial genomes(mitogenomes)from 17 sheep remains in 6 Chinese sites and 1 Uzbekistan site dated 4429–3100 years before present(BP).By obtaining the mitogenomes from the sheep(4429–3556 BP)found in the Tongtian Cave site in Xinjiang,Altai region of northwest China,our results support the emergence of haplogroup C sheep in Xinjiang as early as 4429–3556 *** combined phylogenetic analyses with extant ancient and modern sheep mitogenomes suggest that the Uzbekistan-Altai region may have been a migration hub for early sheep in eastern *** least two migration events have taken place for sheep crossing Eurasia to China,one passing by Uzbekistan and Northwest China to the middle and lower reaches of the Yellow River at approximately 4000 BP and another following the Altai region to middle Inner Mongolia from 4429 BP to 2500 ***,this study provides further evidence for early sheep utilization and migration patterns in Eastern Asia.

关键词： Sheep Ancient DNA Eastern Asia Mitochondrial genome Migration Altai

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Analysis and Design of Time-Delay Impulsive Systems Subject to Actuator Saturation

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IEEE/CAA Journal of Automatica Sinica 2024年第1期11卷 196-204页

作者： Chenhong Zhu Xiuping Han Xiaodi Li IEEE the School of Mathematics and Statistics Shandong Normal UniversityJi'nan 250014China the Center for Control and Engineering Computation Shandong Normal UniversityJi'nan 250014China

This paper investigates the exponential stability and performance analysis of nonlinear time-delay impulsive systems subject to actuator saturation. When continuous dynamics is unstable, under some conditions, it is shown that the system can be stabilized by a class of saturated delayed-impulses regardless of the length of input delays. Conversely, when the system is originally stable, it is shown that under some conditions, the system is robust with respect to sufficient small delayed-impulses. Moreover, the design problem of the controller with the goal of obtaining a maximized estimate of the domain of attraction is formulated via a convex optimization problem. Three examples are provided to demonstrate the validity of the main results.

关键词： Delayed impulses impulsive control impulsive disturbance nonlinear systems saturation

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