检索结果-南通市图书馆

Eigenstate properties of the disordered Bose-Hubbard chain

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Frontiers of physics 2024年第4期19卷 57-72页

作者： Jie chen chun chen Xiaoqun Wang Key Laboratory of Artificial Structures and Quantum Control(Ministry of Education) School of Physics and AstronomyShanghai Jiao Tong UniversityShanghai 200240China School of Physics Zhejiang UniversityHangzhou 310058China Collaborative Innovation Center of Advanced Microstructures Nanjing UniversityNanjing 210093China

Many-body localization(MBL)of a disordered interacting boson system in one dimension is studied numerically at the filling faction *** von Neumann entanglement entropy Svn is commonly used to detect the MBL phase transition but remains challenging to be directly *** on the U(1)symmetry from the particle number conservation,Svn can be decomposed into the particle number entropy S_(n) and the configuration entropy *** light of the tendency that the eigenstate's S_(c) nears zero in the localized phase,we introduce a quantity describing the deviation of S from the ideal thermalization distribution;finite-size scaling analysis illustrates that it shares the same phase transition point with Sv but displays the better critical *** observation hints that the phase transition to MBL might largely be determined by S and its fluctuations Notably,the recent experiments[***,et al.,Science 364,256(2019);***,et al.,***.19,481(2023)]demonstrated that this deviation can potentially be measured through the Sn ***,our investigations reveal that the thermalized states primarily occupy the low-energy section of the spectrum,as indicated by measures of localization length,gap ratio,and energy density *** low-energy spectrum of the Bose model closely resembles the entire spectrum of the Fermi(or spin XXZ)model,accommodating a transition from the thermalized to the localized ***,owing to the bosonic statistics,the high-energy spectrum of the model allows the formation of distinct clusters of bosons in the random potential *** analyze the resulting eigenstate properties and briefly summarize the associated *** distinguish between the phase regions at the low and high energies,a probing quantity based on the structure of S_(VN) is also *** work highlights the importance of symmetry combined with entanglement in the study of *** this regard,for the disordered Heisenberg XXZ

关键词： entanglement entropy decomposition U(1)symmetry thermalization-to-localization transition

In-situ powder mixing for laser-based directed energy deposition of functionally graded materials

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Advances in Manufacturing 2024年第1期12卷 150-166页

作者： Ji-Peng chen Shou-chun Xie He Huang School of Mechanical and Electronic Engineering Nanjing Forestry UniversityNanjing210037People’s Republic of China Nanjing Huirui Photoelectric Technology Co. LtdNanjing211121People’s Republic of China

The mixing of powders is a highly relevant field under additive manufacturing,however,it has attracted limited interest to *** in-situ mixing of various powders remains a significant *** paper proposes a new method utilizing a static mixer for the in-situ mixing of multiple powders through the laser-based directed energy deposition(DED)of functionally graded ***,a powder-mixing experimental platform was established;WC and 316L powders were selected for the mixing ***,scanning electron microscopy,energy dispersive spectroscopy,and image processing were used to visually evaluate the homogeneity and proportion of the in-situ mixed ***,powder-mixing simulations were conducted to determine the powder-mixing *** the simulations,a powder carrier gas flow field and particle mixing were ***,a WC/316L metal matrix composite sample was produced using laser-based DED to verify the application potential of the static *** was found that the static mixer could adjust the powder ratio online,and a response time of 1–2 s should be considered when adjusting the ratio of the mixed powder.A feasible approach for in-situ powder mixing for laser-based DED was demonstrated and investigated,creating the basis for functionally graded materials.

关键词： Laser Deposition Static mixer Powder mixing Functionally graded materials

A mini review on nickel-based electrocatalysts for alkaline hydrogen evolution reaction

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Nano Research 2016年第1期9卷 28-46页

作者： Ming Gong Di-Yan Wang chia-chun chen Bing-Joe Hwang Hongjie Dai Department of Chemistry Stanford University Stanford CA 94305 USA Department of Chemistry 'National Taiwan Normal University' Taipei 11677 Taiwan China Institute of Atomic and Molecular Science 'Academia Sinica' Taipei 10617 Taiwan China Department of Chemical Engineering 'National Taiwan University of Science and Technology' Taipei 10607 Taiwan China

High gravimetric energy density, earth-abundance, and environmental friendliness of hydrogen sources have inspired the utilization of hydrogen fuel as a clean alternative to fossil fuels. Hydrogen evolution reaction （HER）, a half reaction of water splitting, is crucial to the low-cost production of pure H2 fuels but necessitates the use of electrocatalysts to expedite reaction kinetics. Owing to the availability of low-cost oxygen evolution reaction （OER） catalysts for the counter electrode in alkaline media and the lack of low-cost OER catalysts in acidic media, researchers have focused on developing HER catalysts in alkaline media with high activity and stability. Nickel is well-known as an HER catalyst and continuous efforts have been undertaken to improve Ni-based catalysts as alkaline electrolyzers： In this review, we summarize earlier studies of HER activity and mechanism on Ni surfaces, along with recent progress in the optimization of the Ni-based catalysts using various modern techniques. Recently developed Ni-based HER catalysts are categorized according to their chemical nature, and the advantages as well as limitations of each category are discussed. Among all Ni-based catalysts, Ni-based alloys and Ni-based hetero-structure exhibit the most promising electrocatalytic activity and stability owing to the fine-tuning of their surface adsorption properties via a synergistic nearby element or domain. Finally, selected applications of the developed Ni-based HER catalysts are highlighted, such as water splitting, the chloralkali process, and microbial electrolysis cell.

关键词： hydrogen evolutionreaction nickel alkaline electrolyzer catalyst

Multi-exit self-distillation with appropriate teachers

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Frontiers of Information Technology & Electronic Engineering 2024年第4期25卷 585-599页

作者： Wujie SUN Defang chen Can WANG Deshi YE Yan FENG chun chen College of Computer Science and Technology Zhejiang UniversityHangzhou 310000China

Multi-exit architecture allows early-stop inference to reduce computational cost,which can be used in resource-constrained *** works combine the multi-exit architecture with self-distillation to simultaneously achieve high efficiency and decent performance at different network ***,existing methods mainly transfer knowledge from deep exits or a single ensemble to guide all exits,without considering that inappropriate learning gaps between students and teachers may degrade the model performance,especially in shallow *** address this issue,we propose Multi-exit self-distillation with Appropriate TEachers(MATE)to provide diverse and appropriate teacher knowledge for each *** MATE,multiple ensemble teachers are obtained from all exits with different trainable *** exit subsequently receives knowledge from all teachers,while focusing mainly on its primary teacher to keep an appropriate gap for efficient knowledge *** this way,MATE achieves diversity in knowledge distillation while ensuring learning *** results on CIFAR-100,TinyImageNet,and three fine-grained datasets demonstrate that MATE consistently outperforms state-of-the-art multi-exit self-distillation methods with various network architectures.

关键词： Multi-exit architecture Knowledge distillation Learning gap

Molecular investigation into the transformation of recalcitrant dissolved organic sulfur in refinery sour water during stripping process

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Petroleum Science 2024年第3期21卷 2112-2119页

作者： Yu-Guo Li chen He chun-Mao chen Fan Liu Quan Shi State Key Laboratory of Heavy Oil Processing China University of PetroleumBeijing 102249China State Key Laboratory of Coal Mining and Clean Utilization Beijing 100013China PetroChina Ningxia Petrochemical Company Yinchuan 750021NingxiaChina

Refinery sour water primarily originates from the tops of towers in various units and coker condensate,and cannot be discharged directly to a wastewater treatment plant due to high levels of chemical oxygen demand(COD)and organic sulfur *** after the recovery of H_(2)S from the sour water by the stripping process,the effluent still contains a high concentration of dissolved organic sulfur(DOS),which can have a huge bad *** chemical composition of dissolved organic matter(DOM)in refinery wastewater has been extensively studied,the investigation of recalcitrant DOS from sour waters remains *** the present study,chemical composition of sour water DOMs(especially DOS)was investigated using fluorescence spectroscopy(excitation-emission matrix,EEM)and mass spectrometry,including gas chromatography-mass spectrometry(GC-MS)and high-resolution Orbitrap *** GC-MS and EEM results showed that volatile and low-aromaticity compounds were effectively removed during the stripping process,while compounds with high hydrophilicity and humification degree were found to be more *** Orbitrap MS results showed that weak-polar oxygenated sulfur compounds were easier to be removed than oxygenated ***,the effluent still contained significant amounts of sulfur-containing compounds with multiple sulfur atoms,particularly in the form of highly unsaturated and aromatic *** Orbitrap MS/MS results of CHOS-containing compounds from the effluent indicate that the sulfur atoms may exist as sulfonates,disulfide bonds,*** the composition and structure of sour water DOS is crucial for the development of effective treatment processes that can target polysulfide compounds and minimize their impact on the environment.

关键词： Molecular transformation Dissolved organic sulfur Stripping process Refinery sourwater Orbitrap MS

Modelling smear effect of vertical drains using a diameter reduction method

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Journal of Rock Mechanics and Geotechnical Engineering 2024年第1期16卷 279-290页

作者： Zhichao Shen Siau chen chian Siew Ann Tan chun Fai Leung School of Marine Science and Engineering South China University of TechnologyGuangzhouChina Department of Civil and Environmental Engineering National University of SingaporeSingapore

Vertical drains are used to accelerate consolidation of clays in ground improvement *** zones exist around these drains,where permeability is reduced due to soil disturbance caused by the installation *** solution is widely used in practice to consider the effects of drain discharge capacity and smear on the consolidation *** this study,a computationally efficient diameter reduction method(DRM)obtained from the Hansbo solution is proposed to consider the smear effect without the need to model the smear zone *** by analytical and numerical results,a diameter reduction factor is analytically derived to reduce the diameter of the drain,while achieving similar solutions of pore pressure dissipation profile as the classical full model of the smear zone and *** the DRM,the excess pore pressure u obtained from the reduced drain in the original un-disturbed soil zone is accurate enough for practical applications in numerical *** performance of DRM is independent of soil material *** also show equally accurate performance of DRM under conditions of multi-layered soils and coupled radial-vertical groundwater flow.

关键词： Consolidation Vertical drain Smear effect Pore pressure Soil improvement

Assembly of highly efficient aqueous light-harvesting system from sequence-defined peptoids for cytosolic microRNA detection

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Nano Research 2024年第2期17卷 788-796页

作者： Yang Song Xiaoli Cai Mingming Wang Dan Du Yuehe Lin chun-Long chen Department of Mechanical and Materials Engineering Washington State UniversityPullmanWA 99164USA Division of Physical Sciences Pacific Northwest National LaboratoryRichlandWA 99352USA Department of Chemical Engineering University of WashingtonSeattleWA 98195USA

Precisely controlled spatial distributions of artificial light-harvesting systems in aqueous media are of significant importance for mimicking natural light-harvesting systems;however,they are often restrained by the solubility and the aggregation-caused quenching effect of the hydrophobic ***,we report one highly efficient artificial light-harvesting system based on peptoid nanotubes that mimic the hierarchical cylindrical structure of natural *** high crystallinity of these nanotubes enabled the organization of arrays of donor chromophores with precisely controlled spatial distributions,favoring an efficient Förster resonance energy transfer(FRET)process in aqueous *** FRET system exhibits an extremely high efficiency of 98.6%with a fluorescence quantum yield of 40%and an antenna effect of *** further demonstrated the use of this artificial light-harvesting system for quantifying miR-210 within cancer *** fluorescence intensity ratio of donor to acceptor is linearly related to the concentration of intercellular miR-210 in the range of 3.3–156 copies/*** high sensitivity in intracellular detection of miR-210 using this artificial light-harvesting system offers a great opportunity and pathways for biological imaging and detection,and for the further creation of microRNA(miRNA)toolbox for quantitative epigenetics and personalized medicine.

关键词： light-harvesting peptoid nanotube Förster resonance energy transfer intracellular RNA detection

Quasi-two dimensional Ruddlesden−Popper halide perovskites for laser applications

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Frontiers of physics 2024年第2期19卷 53-71页

作者： Kun chen Qianpeng Zhang Yin Liang Jiepeng Song chun Li Shi chen Fang Li Qing Zhang School of Mechanical and Electrical Engineering Wuhan Institute of TechnologyWuhan 430205China School of Materials Science and Engineering Peking UniversityBeijing 100871China Institute of Applied Physics and Materials Engineering Macao UniversityMacao 999078China

Quasi-two-dimensional(2D)Ruddlesden‒Popper(RP)halide perovskites,as a kind of emerged two-dimensional layered materials,have recently achieved great attentions in lasing materials field owing to their large exciton binding energy,high emission yield,large optical gain,and wide-range tuning of optical *** review will introduce research progresses of RP halide perovskites for lasing applications in aspects of materials,photophysics,and devices with emphasis on emission and lasing properties tailored by the molecular composition and *** materials,structures and fabrications are introduced in the first ***,the optical transitions and amplified spontaneous emission properties are discussed from the aspects of electronic structure,exciton,gain dynamics,and interface ***,the research progresses on lasing devices are summarized and several types of lasers including VCSEL,DFB lasers,microlasers,random lasers,plasmonic lasers,and polariton lasers are *** last,the challenges and perspectives would be provided.

关键词： two-dimensional materials metal halide perovskite Ruddlesden−Popper halide perovskites lasing emission

Elastic three-dimensional phononic topological insulators with Dirac hierarchy

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2024年第5期67卷 54-62页

作者： Shao-Yong Huo Qiu-Shuang Yang Jiu-Jiu chen Hong-Kang Li Long-Chao Yao Fu-chun He chun-Ming Fu College of Mechanical Engineering University of South ChinaHengyang 421001China State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body College of Mechanical and Vehicle EngineeringHunan UniversityChangsha 410082China

Three-dimensional(3D)phononic topological insulators(TIs)featuring two-dimensional(2D)surface states and one-dimensional(1D)hinge states have opened up a new route for multi-dimensional robust wave transport,providing unprecedented methods for integrated acoustic sensors and energy harvesting ***,aiming at the elastic 3D phononic TI with gapless surface states and hinge states,the realization of elastic 3D phononic TIs with gapless surface states and hinge states is a significant challenge due to the complicated multi-mode polarization of elastic waves in 3D *** this study,we demonstrate an elastic 3D phononic TI with a Dirac hierarchy by elaborately operating the corresponding spatial symmetries of the chiral honeycomb ***,a 3D double Dirac cone of elastic wave can be achieved by doubling the lattice along the outof-plane direction to fold two iso-frequency Weyl *** topological phase transitions and 2D gapless two-fold Dirac surface states of elastic wave are realized by breaking the half-lattice spatial translation ***,based on the Brillouin zone folding along the in-plane direction,the 2D gapless two-fold surface Dirac cones are folded into four-fold surface Dirac ***,by inducing the relative radius of adjacent holes to break the in-plane spatial inversion symmetry,the fourfold surface Dirac cones are gapped and associated with a surface state inversion,in which the gapless 1D hinge Dirac dispersion is *** research offers a route for engineering the hierarchies of TIs in 3D elastic wave systems and provides new possibilities for designing 3D ultrasonic devices with unconventional functions.

关键词： Dirac topological hierarchy