检索结果-南通市图书馆

Cosmological interpretation for the stochastic signal in pulsar timing arrays

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4期67卷 43-50页

作者： Yu-Mei wu zu-Cheng Chen Qing-Guo Huang School of Fundamental Physics and Mathematical Sciences Hangzhou Institute for Advanced StudyUniversity of Chinese Academy of SciencesHangzhou 310024China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100049China Department of Astronomy Beijing Normal UniversityBeijing 100875China Advanced Institute of Natural Sciences Beijing Normal UniversityZhuhai 519087China Department of Physics and Synergistic Innovation Center for Quantum Effects and Applications Hunan Normal UniversityChangsha 410081China CAS Key Laboratory of Theoretical Physics Institute of Theoretical PhysicsChinese Academy of SciencesBeijing 100190China

The pulsar timing array(PTA)collaborations have recently reported compelling evidence for a stochastic signal consistent with a gravitational-wave *** this paper,we combine the latest data sets from NANOGrav,PPTA,and EPTA to explore cosmological interpretations for the PTA signal from first-order phase transitions,domain walls,and cosmic strings,*** find that the domain wall model is strongly disfavored with the Bayes factors compared with the first-order phase transitions and cosmic strings being 1/90 and 1/189,respectively,breaking the degeneracy among these models in individual data *** also find that:(1)a strong phase transition at temperatures below the electroweak scale is favored,and the bubble collisions make the dominant contribution to the energy density spectrum;(2)a small reconnection probability p<1.55×10^(-1)allowed by strings in(super)string theory is favored at the 95%confidence level,and ground-based detectors can further constrain the parameter space.

关键词： puslar timing arrays gravitational-wave background first-order phase transitions domain walls cosmic strings

High-yield production of porous carbon spheres derived from enzymatic hydrolysis lignin for zinc ion hybrid capacitors

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

Frontiers of Chemical Science and Engineering 2024年第2期18卷 127-136页

作者： tao Huang Xihong zu Jianhui Ma Wenbin Jian Xueqing Qiu Wenli Zhang Guangdong Provincial Key Laboratory of Plant Resources Biorefinery School of Chemical Engineering and Light IndustryGuangdong University of TechnologyGuangzhou 510006China School of Advanced Manufacturing Guangdong University of TechnologyJieyang 522000China Jieyang Branch of Chemistry and Chemical Engineering Guangdong Laboratory(Rongjiang Laboratory) Jieyang 515200China

The widespread implementation of supercapacitors is hindered by the limited energy density and the pricey porous carbon electrode *** cost of porous carbon is a significant factor in the overall cost of supercapacitors,therefore a high carbon yield could effectively mitigate the production cost of porous *** study proposes a method to produce porous carbon spheres through a spray drying technique combined with a carbonization process,utilizing renewable enzymatic hydrolysis lignin as the carbon source and KOH as the activation *** purpose of this study is to examine the relationship between the quantity of activation agent and the development of morphology,pore structure,and specific surface area of the obtained porous carbon *** demonstrate that this approach significantly enhances the carbon yield of porous carbon,achieving a yield of 22%in contrast to the conventional carbonization-activation method(9%).The samples acquired through this method were found to contain a substantial amount of mesopores,with an average pore size of 1.59 to 1.85 nm and a mesopore ratio of 25.6%.Additionally,these samples showed high specific surface areas,ranging from 1051 to 1831 m2·g^(−1).Zinc ion hybrid capacitors with lignin-derived porous carbon cathode exhibited a high capacitance of 279 F·g^(−1) at 0.1 A·g^(−1) and an energy density of 99.1 Wh·kg^(−1) when the power density was 80 kW·kg^(−1).This research presents a novel approach for producing porous carbons with high yield through the utilization of a spray drying approach.

关键词： enzymatic hydrolysis lignin porous carbon spheres spray drying zinc ion hybrid capacitors

Ultrasound sensing with optical microcavities

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Light(Science & Applications) 2024年第8期13卷 1487-1511页

作者： Xuening Cao Hao Yang zu-Lei wu Bei-Bei Li Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China School of Optical and Electronic Information Huazhong University of Science and TechnologyWuhan 430074China Songshan Lake Materials Laboratory Dongguan 523808 GuangdongChina

Ultrasound sensors play an important role in biomedical imaging,industrial nondestructive inspection,*** ultrasound sensors that use piezoelectric transducers face limitations in sensitivity and spatial resolution when miniaturized,with typical sizes at the millimeter to centimeter *** overcome these challenges,optical ultrasound sensors have emerged as a promising alternative,offering both high sensitivity and spatial *** particular,ultrasound sensors utilizing high-quality factor(Q)optical microcavities have achieved unprecedented performance in terms of sensitivity and bandwidth,while also enabling mass production on silicon *** this review,we focus on recent advances in ultrasound sensing applications using three types of optical microcavities:Fabry-Perot cavities,π-phase-shifted Bragg gratings,and whispering gallery mode *** provide an overview of the ultrasound sensing mechanisms employed by these microcavities and discuss the key parameters for optimizing ultrasound ***,we survey recent advances in ultrasound sensing using these microcavity-based approaches,highlighting their applications in diverse detection scenarios,such as photoacoustic imaging,ranging,and particle *** goal of this review is to provide a comprehensive understanding of the latest advances in ultrasound sensing with optical microcavities and their potential for future development in high-performance ultrasound imaging and sensing technologies.

关键词： optical millimeter offering

Almost Periodic Type Group Actions on Compact Quantum Metric Spaces

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2024年第2期40卷 568-594页

作者： Bo tao LONG Wei wu College of Mathematics MIIT Key Laboratory of Mathematical Modelling and High Performance Computing of Air VehiclesNanjing University of Aeronautics and AstronauticsNanjing 211106P.R.China School of Mathematical Sciences Shanghai Key Laboratory of Pure Mathematics and Mathematical PracticeEast China Normal UniversityShanghai 200241P.R.China

A compact quantum metric space is a complete order unit space A endowed with a Lipnorm *** give some characterizations of almost periodic type group actions on a compact quantum metric space(A,L)by means of several kinds of subsets of A,its induced equicontinuous actions on several important subsets of the dual Banach space A*,and the Lip-norm L with its induced metric space structures on the state space S(A)of A.

关键词： Lip-norm compact quantum metric space Lipschitz isomorphism almost periodicity Arzela-Ascoli theorem metric set

Status and trends of carbon emissions research at the county level in China

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

Advances in Climate Change Research 2024年第2期15卷 338-352页

作者： Ang-zu CAI Ru GUO Yu-Hao ZHANG Jiang wu College of Environmental Science and Engineering Institute of Environmental Planning and ManagementTongji UniversityShanghai 200092China Institute of Carbon Neutrality Tongji UniversityShanghai 200092China Shanghai Institute of Pollution Control and Ecological Security Shanghai 200092China College of Architecture and Urban Planning Tongji UniversityShanghai 200092China Megacity Elaborated Urban Governance Institute Tongji UniversityShanghai 200092China

This study provides a comprehensive overview of the challenges to achieving carbon neutrality at the county level in China and offers targeted recommendations,laying the groundwork for future specialized research in this area.A total of 283 relevant studies(2004-2023)were analyzed to assess county-level carbon emissions through three phases:bibliometric analysis,frontier analysis,and future *** findings reveal that publication trends were largely influenced by domestic and foreign *** cluster discerns ten primary themes,ranging from conceptual frameworks to research *** frontier analysis of the literature highlights the leading research areas,which include carbon neutrality pathway,driving factors,spatiotemporal variation of carbon emissions,the co-effects of pollutants and carbon reduction,and carbon emissions in China's rural *** from the results of bibliometric and frontier analyses,this study elucidates the recommendations for achieving carbon neutrality at the county level from three perspectives:effective regional policy guidance,emphasis on ecological conservation,and the deployment of advanced carbon reduction and sequestration *** study enriches the body of knowledge on carbon emissions at the county level and holds significant implications for China's comprehensive push towards achieving its carbon neutrality objectives.

关键词： Carbon emissions Emission reduction County Carbon neutrality Sustainability

Combination of High Yield Strength and Improved Ductility of 21Cr Lean Duplex Stainless Steel by Tailoring Cold Deformation and Low-Temperature Short-Term Aging

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2024年第4期37卷 695-702页

作者： Zhenghong Liu Zhigang wu Ying Han Xiaolei Song Guoqing zu Weiwei Zhu Xu Ran Key Laboratory of Advanced Structural Materials Ministry of EducationChangchun University of TechnologyChangchun130012China School of Materials Science and Engineering Changchun University of TechnologyChangchun130012China Jilin Province Key Laboratory of Advanced Materials Processing and Application for Rail Transit Changchun University of TechnologyChangchun130012China

Proper matching of cold-rolled deformation and low-temperature short-term aging can simultaneously enhance the strength and ductility of the lean duplex stainless steel. To investigate this, the microstructure evolution of cold-rolled and aging steels was observed by using scanning electron microscopy, transmission electron microscopy and electron backscattered diffraction. Additionally, the phase volume fraction was measured using X-ray diffraction. In this study, it was observed that the elongation of 21Cr lean duplex stainless steel significantly increased to 16.7% after undergoing moderate cold deformation (~ 40% reduction) and subsequent aging treatment at 550 ℃ for 30 min. Remarkably, the material still maintained a high yield strength of 1045 MPa. Such an excellent mechanical property was attributed to a unique microstructure combination of fine α'-martensite, twins, coarsened austenite resulting from partial martensite reverse transformation, and two-phase fine layered structure. The result of this study may open up new horizons for the alloy development in order to overcome the low ductility of cold-rolled high-strength lean duplex stainless steel.

关键词： Lean duplex stainless steel Cold rolling Aging Microstructure Mechanical properties Use our pre-submission checklist

Comparison-embedded evidence-CNN model for fuzzy assessment of wear severity using multi-dimensional surface images

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Friction 2024年第6期12卷 1098-1118页

作者： tao SHAO Shuo WANG Qinghua WANG Tonghai wu Zhifu HUANG Key Laboratory of Education Ministry for Modern Design and Rotor-Bearing System Xi’an Jiaotong UniversityXi’an 710049China State Key Laboratory for Mechanical Behavior of Materials Xi’an Jiaotong UniversityXi’an 710049China

Wear topography is a significant indicator of tribological behavior for the inspection of machine health *** intelligent in-suit wear assessment method for random topography is here ***-dimension(3D)topography is employed to address the uncertainties in wear ***,3D topography reconstruction from a worn surface is accomplished with photometric stereo vision(PSV).Then,the wear features are identified by a contrastive learning-based extraction network(WSFE-Net)including the relative and temporal prior knowledge of wear ***,the typical wear degrees including mild,moderate,and severe are evaluated by a wear severity assessment network(WSA-Net)for the probability and its associated uncertainty based on subjective *** integrating the evidence information from 2D and 3D-damage surfaces with Dempster–Shafer(D–S)evidence,the uncertainty of severity assessment results is further *** proposed model could constrain the uncertainty below 0.066 in the wear degree evaluation of a continuous wear experiment,which reflects the high credibility of the evaluation result.

关键词： wear severity assessment contrastive learning subjective logic Dempster-Shafer(D-S)evidence theory

Bibliometric analysis and systematic review of electrochemical methods for environmental remediation

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2024年第10期144卷 113-136页

作者： Wenbin Huang Shibin Liu tao Zhang Hao wu Shengyan Pu College of Earth Sciences Chengdu University of TechnologyChengdu 610059China State Key Laboratory of Geohazard Prevention and Geoenvironment Protection(Chengdu University of Technology) Chengdu 610059China College of Ecology and Environment Chengdu University of TechnologyChengdu 610059China Key Laboratory of Biodiversity Formation Mechanism and Comprehensive Utilization of the Qinghai-Tibet Plateau in Qinghai Province Qinghai Normal UniversityXining 810008China Scientific Research Academy of Guangxi Environmental Protection Nanning 530022China

Electrochemical methods are increasingly favored for remediating polluted environments due to their environmental compatibility and reagent-saving ***,a comprehensive understanding of recent progress,mechanisms,and trends in thesemethods is currently *** of Science(WoS)databases were utilized for searching the primary data to understand the knowledge structure and research trends of publications on electrochemical methods and to unveil certain hotspots and future trends of electrochemical methods *** original data were sampled from 9080 publications in those databases with the search deadline of June 1st,*** and VOSviewer software facilitated data visualization and analysis of document quantities,source journals,institutions,authors,and *** discussed principles,influencing factors,and progress related to seven major ***,publications on this subject have experienced significant growth since *** most frequently-investigated areas in electrochemical methods included novel materials development,heavy metal remediation,organic pollutant degradation,and removal mechanism identification.“Advanced oxidation process”and“Nanocomposite”are currently trending *** major remediation mechanisms are adsorption,oxidation,and *** efficiency of electrochemical systems is influenced by material properties,system configuration,electron transfer efficiency,and power ***-Fenton exhibits significant advantages in achieving synergistic effects of anodic oxidation and electro-adsorption among the seven *** research should prioritize the improvement of electron transfer efficiency,the optimization of electrode materials,the exploration of emerging technology coupling,and the reduction in system operation and maintenance costs.

关键词： Electrochemical remediation Bibliometric analysis Heavy metals Organic pollutants Electrode materials

Selective photosynthesis of imines from biomass-derived aldehydes over Ni/TiO_(2)

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Rare Metals 2024年第3期43卷 1116-1124页

作者： wu-Lin Li Qing-Qing Zhang Lin Dong Wen-Jun Zhang Li-Li Lin zu-Peng Chen Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources International Innovation Center for Forest Chemicals and MaterialsCollege of Chemical EngineeringNanjing Forestry UniversityNanjing210037China Institute of Industrial Catalysis State Key Laboratory of Green Chemistry Synthesis TechnologyCollege of Chemical EngineeringZhejiang University of TechnologyHangzhou310014China

Photocatalytic reductive amination of biomass-derived aldehydes is a desirable way to selectively upgrade biomass into value-added nitrogen-containing chemicals under mild ***,it is challenging to produce imines in high selectivity because of the undesirable side reactions caused by the activity of functional ***,we demonstrate the highly reactive and selective production of imines from biomass derived aldehydes via the photocatalytic reductive amination,using a defective TiO_(2)supported nickel *** employment of methanol as the hydrogen donor and ammonia solution as the nitrogen source avoids the use of high-pressure H_(2)and expensive amines,rendering the current catalytic process safe,economical,and environmentally *** depth investigations attribute the improved separation and transfer of photogenerated charge carriers to the presence of oxygen vacancies and decorated Ni nanoparticles,thereby accelerating the production of imines from benzaldehyde amination(conversion,95.8%;seleetivity,95.2%).Furthermore,the developed system could be easily translated to the photocatalytic conversions of various biomass derived aldehydes,which provided an example of a cost-effective and sustainable approach for the valorization of biomass derived feedstocks.

关键词： Photocatalysis Biomass derivatives Imines Reduction amination Heterogeneous catalyst