检索结果-南通市图书馆

Chinese Physics B 2024年第8期33卷 526-543页

作者：徐兆文白雪马健万壮壮王超群 Laser Institute Qilu University of Technology(Shandong Academy of Sciences)Jinan 250104China

Quantitative relationship between nanosecond pulsed laser parameters and the characteristics of laser-generated ultrasonic waves in polycrystalline materials was *** high energy of the pulsed laser with a large irradiation spot simultaneously generated ultrasonic longitudinal and shear waves at the epicenter under the slight ablation *** optimized denoising technique based on wavelet thresholding and variational mode decomposition was applied to reduce noise in shear waves with a low signal-to-noise *** approach for characterizing grain size was proposed using spectral central frequency ratio(SCFR)based on time-frequency *** results demonstrate that the generation regime of ultrasonic waves is not solely determined by the laser power density;even at high power densities,a high energy with a large spot can generate an ultrasonic waveform dominated by the thermoelastic *** is ascribed to the intensification of the thermoelastic effect with the proportional increase in laser irradiation spot area for a given laser power ***,both longitudinal and shear wave SCFRs are linearly related to grain size in polycrystalline materials;however,the shear wave SCFR is more sensitive to finer-grained *** study holds great significance for evaluating metal material properties using laser ultrasound.

关键词： laser-ultrasonics polycrystalline materials ultrasonic time-frequency characteristics grain size

Furfural residues derived nitrogen-sulfur co-doped sheet-like carbon: An excellent electrode for dual carbon lithium-ion capacitors

在线全文

学校读者我要写书评

暂无评论

Green Energy & Environment 2024年第9期9卷 1427-1439页

作者： Xiaoying Guo Yan Qiao Zonglin Yi Christian Marcus Pedersen Yingxiong Wang Xiaodong Tian Peide Han College of Materials Science and Engineering Taiyuan University of Technology State Key Laboratory of Coal Conversion Institute of Coal Chemistry Chinese Academy of Sciences university of Chinese Academy of sciences CAS Key Laboratory of Carbon Materials Institute of Coal Chemistry Chinese Academy of Sciences Department of Chemistry University of Copenhagen Universitetsparken 5 College of Chemistry Taiyuan University of Technology

The state-of-the-art lithium-ion capacitors （LICs）,consisting of high-capacity battery-type anode and high-rate capacitor-type cathode,can deliver high energy density and large power density when comparing with traditional supercapacitors and lithium-ion batteries,***,the ion kinetics mismatch between cathode and anode leads to unsatisfied cycling lifetime and anode *** efforts have been devoted to solving the abovementioned *** promising strategy is altering high conductive hard carbon anode with excellent structural stability to match with activated carbon cathode,assembling dual-carbon *** this contribution,one-pot in-situ expansion and heteroatom doping strategy was adopted to prepare sheet-like hard carbon,while activated carbon was obtained involving *** persulfate was used as expanding and doping agent *** furfural residues （FR） were served as carbon *** resulting hard carbon （FRNS-HC） and activated carbon （FRNS-AC）show excellent electrochemical performance as negative and positive electrodes in a lithium-ion battery （LIB）.To be specific,374.2 m Ah g-1and 123.1 m Ah g-1can be achieved at 0.1 A g-1and 5 A g-1when FRNS-HC was tested as *** combined with a highly porous carbon cathode (SBET=2961 m2g-1) synthesized from the same precursor,the LIC showed high specific energy of147.67 Wh kg-1at approximately 199.93 W kg-1,and outstanding cycling life with negligible capacitance fading over 1000 *** study could lead the way for the development of heteroatom-doped porous carbon nanomaterials applied to Li-based energy storage applications.

关键词： Furfural residue Ammonium persulfate Sheet-like carbon Lithium-ion capacitors Hard carbon

Extracting Integrated Features of Electronic Medical Records Big Data for Mortality and Phenotype Prediction

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Electronics 2024年第3期33卷 776-792页

作者： Fei LI Yiqiang CHEN Yang GU Yaowei WANG Institute of Computing technology University of Chinese Academy of Sciences Pengcheng Laboratory

The key to synthesizing the features of electronic medical records(EMR) big data and using them for specific medical purposes,such as mortality and phenotype prediction,is to integrate the individual medical event and the overall multivariate time series feature extraction automatically,as well as to alleviate data imbalance *** paper provides a general feature extraction method to reduce manual intervention and automatically process large-scale *** processing uses two variational auto-encoders(VAEs) to automatically extract individual and global *** avoids the well-known posterior collapse problem of Transformer VAE through a uniquely designed "proportional and stabilizing" mechanism and forms a unique means to alleviate the data imbalance *** conducted experiments using ICU-STAY patients' data from the MIMIC-Ⅲ database and compared them with the mainstream EMR time series processing *** results show that the method extracts visible and comprehensive features,alleviates data imbalance problems and improves the accuracy in specific predicting tasks.

关键词： Databases Time series analysis MIMICs Manuals Big Data Feature extraction Transformers

System error iterative identification for underwater positioning based on spectral clustering

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Systems Engineering and Electronics 2024年第4期35卷 1028-1041页

作者： LU Yu WANG Jiongqi HE Zhangming ZHOU Haiyin XING Yao ZHOU Xuanying College of sciences National University of Defense TechnologyChangsha 410073China

The observation error model of the underwater acous-tic positioning system is an important factor to influence the positioning accuracy of the underwater *** the position inconsistency error caused by considering the underwater tar-get as a mass point,as well as the observation system error,the traditional error model best estimation trajectory(EMBET)with little observed data and too many parameters can lead to the ill-condition of the parameter *** this paper,a multi-station fusion system error model based on the optimal polynomial con-straint is constructed,and the corresponding observation sys-tem error identification based on improved spectral clustering is ***,the reduced parameter unified modeling for the underwater target position parameters and the system error is achieved through the polynomial *** a multi-sta-tion non-oriented graph network is established,which can address the problem of the inaccurate identification for the sys-tem ***,the similarity matrix of the spectral cluster-ing is improved,and the iterative identification for the system errors based on the improved spectral clustering is ***,the comprehensive measured data of long baseline lake test and sea test show that the proposed method can accu-rately identify the system errors,and moreover can improve the positioning accuracy for the underwater target positioning.

关键词： acoustic positioning reduced parameter system error identification improved spectral clustering accuracy analy-sis

Charge transfer complex enabled photoreduction of ether phosphonium salts for the selective oxyalkylation of enamides

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2024年第2期35卷 411-414页

作者： Sen Qiao Kunquan Chen Qiang Liu Zhixiang Wang Xiangyu Chen School of Chemical sciences University of the Chinese Academy of SciencesBeijing 100049China Binzhou Institute of technology Weiqiao-UCAS Science and Technology ParkBinzhou 256606China

A charge transfer complex(CTC)-enabled photoreduction of ether phosphonium salts for the generation of oxyalkyl radicals was *** photoreduction provides a convenient method to achieve selective oxyalkylation of enamid... 详细信息

关键词： Enamides Phosphonium salts Ethers Charge transfer complex Visible light

Studies of an event-building algorithm of the readout system for the twin TPCs in HFRS

在线全文

学校读者我要写书评

暂无评论

Nuclear Science and Techniques 2024年第4期35卷 82-95页

作者： Jing Tian Zhi-Peng Sun Song-Bo Chang Yi Qian Hong-Yun Zhao Zheng-Guo Hu Xi-Meng Chen Institute of Modern Physics Chinese Academy of SciencesLanzhou 730000China School of Nuclear Science and technology University of LanzhouLanzhou 730000China School of Nuclear Science and technology University of Chinese Academy of SciencesBeijing 100049China Advanced Energy Science and technology Guangdong LaboratoryHuizhou 516000China

The High-energy Fragment Separator(HFRS),which is currently under construction,is a leading international radioactive beam *** sets of position-sensitive twin time projection chamber(TPC)detectors are distributed on HFRS for particle identification and beam *** twin TPCs'readout electronics system operates in a trigger-less mode due to its high counting rate,leading to a challenge of handling large amounts of *** address this problem,we introduced an event-building *** algorithm employs a hierarchical processing strategy to compress data during transmission and *** addition,it reconstructs twin TPCs'events online and stores only the reconstructed particle information,which significantly reduces the burden on data transmission and storage *** studies demonstrated that the algorithm accurately matches twin TPCs'events and reduces more than 98%of the data volume at a counting rate of 500 kHz/channel.

关键词： High counting rate Twin TPCs Trigger-less Readout electronics Event building Hierarchical data processing

Probing the Nucleation and Growth Kinetics of Bismuth Nanoparticles via In-situ Transmission Electron Microscopy

在线全文

学校读者我要写书评

暂无评论

Journal of Wuhan university of technology(Materials Science) 2024年第4期39卷 877-887页

作者：王浪李超凡 RAN Maojin YUAN Manman 胡执一 LI Yu State Key Laboratory of Advanced technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan 430070China Nanostructure Research Centre(NRC) Wuhan University of TechnologyWuhan 430070China Institute of Chemistry Henan Academy of SciencesZhengzhou 450002China Henan Academy of sciences Zhengzhou 450046China

The nucleation and growth mechanism of nanoparticles is an important theory,which can guide the preparation of ***,it is still lacking in direct observation on the details of the evolution of intermediate state structure during nucleation and *** this work,the evolution process of bismuth nanoparticles induced by electron beam was revealed by in-situ transmission electron microscopy(TEM)at atomic *** experimental results demonstrate that the size,stable surface and crystallographic defect have important influences on the growth of Bi *** non-classical growth paths including single crystal growth and polycrystalline combined growth,as well as,corresponding layer-by-layer growth mechanism along{012}stable crystal plane of Bi nanoparticles with dodecahedron structure were revealed by in-situ TEM *** results provide important guidance and a new approach for in-depth understanding of the nucleation and growth kinetics of nanoparticles.

关键词： bismuth nanoparticles crystal growth transmission electron microscopy in-situ electron microscopy

Experimental investigation of dynamic characteristics of leaching tubing for solution mining of salt cavern carbon and energy storage

在线全文

学校读者我要写书评

暂无评论

Petroleum Science 2024年第4期21卷 2703-2722页

作者： Yin-Ping Li Xin-Bo Ge Xi-Lin Shi Hong-Ling Ma State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil Mechanics Chinese Academy of Sciences university of Chinese Academy of sciences College of Energy and Mining Engineering Shandong University of Science and Technology State Key Laboratory of Mining Disaster Prevention and Control Co-founded by Shandong Province and the Ministry of Science and technology Shandong University of Science and Technology

Salt caverns are extensively utilized for storing various substances such as fossil energy, hydrogen,compressed air, nuclear waste, and industrial solid waste. In China, when the salt cavern is leached through single-well water solution mining with oil as a cushion, engineering challenges arise with the leaching tubing, leading to issues like damage and instability. These problems significantly hinder the progress of cavern construction and the control of cavern shape. The primary cause of this is the flowinduced vibration instability of leaching tubing within a confined space, which results in severe bending or damage to the tubing. This study presents a model experimental investigation on the dynamic characteristics of leaching tubing using a self-developed liquid-solid coupling physical model experiment apparatus. The experiment utilizes a silicone-rubber pipe(SRP) and a polycarbonate pipe(PCP) to examine the effects of various factors on the dynamic stability of cantilevered pipes conveying fluid. These factors include external space constraint, flexural rigidity, medium outside the pipe, overhanging length, and end conditions. The experiments reveal four dynamic response phenomena: water hammer, static buckling, chaotic motion, and flutter instability. The study further demonstrates that the length of the external space constraint has a direct impact on the flutter critical flow velocity of the cantilevered pipe conveying fluid. Additionally, the flutter critical flow velocity is influenced by the end conditions and different external media.

关键词： Salt cavern storage Solution mining Leaching tubing Experimental investigation Flutter instability

Biomass-based production of trimellitic and trimesic acids

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Green Energy & Environment 2024年第8期9卷 1267-1278页

作者： Lin Yuan Yancheng Hu Guangyi Li Fengan Han Aiqin Wang Yu Cong Tao Zhang Feng Wang Ning Li CAS Key Laboratory of Science and technology on Applied Catalysis Dalian Institute of Chemical PhysicsChinese Academy of Sciences university of Chinese Academy of sciences 19 A Yuquan RoadShijingshan District School of Chemical Engineering and technology China University of Mining and Technology State Key Laboratory of Catalysis Dalian National Laboratory for Clean EnergyDalian Institute of Chemical PhysicsChinese Academy of Sciences

The production of industrial chemicals with renewable biomass feedstock holds potential to aid the world in pursuing a carbon-neutral *** and trimesic acids are important commodity chemicals in industry that are prepared by the oxidation of petroleum-derived *** reduce the dependence on the limited oil source,we develop a potential sustainable alternative towards trimellitic and trimesic acids using biomass-based 2-methyl-2,4-pentandiol （MPD）,acrylate and crotonaldehyde as starting *** process for trimellitic acid includes dehydration/D-A reaction of MPD and acrylate,flow aromatization over Pd/C catalyst,hydrolysis and catalytic aerobic oxidation （60%overall yield）.The challenging regioselectivity issue of D-A reaction is tackled by a matched combination of temperature and deep eutectic solvent ChCl/*** can also participate in the reaction,followed by Pd/C-catalyzed decarbonylation/dehydrogenation and oxidation to provide trimesic acid in 54%overall *** cycle assessment implies that compared to conventional fossil process,our biomass-based routes present a potential in reducing carbon emissions.

关键词： Biomass Trimellitic acid Trimesic acid Deep eutectic solvent Dehydration/D-A reaction

e^(+)e^(-)→Λ_(c)+Λ_(c)^(- ) Cross Sections and the Λ_(c)^(+) Electromagnetic Form Factors within the Extended Vector Meson Dominance Model

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics Letters 2024年第2期41卷 36-41页

作者：陈诚闫冰谢聚军 Institute of Modern Physics Chinese Academy of SciencesLanzhou 730000China School of Nuclear sciences and technology University of Chinese Academy of SciencesBeijing 101408China College of Mathematics and Physics Chengdu University of TechnologyChengdu 610059China Southern Center for Nuclear-Science Theory(SCNT) Institute of Modern PhysicsChinese Academy of SciencesHuizhou 516000China

Within the extended vector meson dominance model,we investigate the𝑒e^(+)e^(-)→Λ_(c)+Λ_(c)^(- ) reaction and the electromagnetic form factors of the charmed baryon𝛬 Λ_(c)^(+)𝑐.The model parameters are determined by fitting them to the cross sections of the process𝑒e^(+)e^(-)→Λ_(c)+Λ_(c)^(- ) and the magnetic form factor|G_(M)|of Λ_(c)^(+) .By considering four charmonium-like states,called𝜓(4500),𝜓(4660),𝜓(4790),and𝜓(4900),we can well describe the current data on the𝑒e^(+)e^(-)→Λ_(c)+Λ_(c)^(- ) reaction from the reaction threshold up to 4.96 *** addition to the total cross sections and|𝐺M|,the ratio|G_(E)/G_(M)|and the effective form factor|Geff|for Λ_(c)^(+) 𝑐are also calculated,and found that these calculations are consistent with the experimental *** the fitted model parameters,we have also estimated the charge radius of the charmed Λ_(c)^(+) baryon.

关键词： fitted radius meson