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Unveiling the size effect of nitrogen-doped carbon-supported copper-based catalysts on nitrate-to-ammonia electroreduction

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Nano Research 2024年第4期17卷 2438-2443页

作者： Ran Li Taotao Gao Wenxi Qiu Minghao Xie Zhaoyu Jin Panpan li College of Materials Science and Engineering Sichuan UniversityChengdu 610065China Institute for Advanced Study Chengdu UniversityChengdu 610106China Materials Science and Engineering Program and Walker Department of Mechanical Engineering The University of Texas at AustinAustinTexas 78712USA Institute of Fundamental and Frontier Sciences University of Electronic Science and Technology of ChinaChengdu 610054China

The electrocatalytic nitrate reduction reaction(NitRR)represents a promising approach toward achieving economically and environmentally sustainable ammonia.However,it remains a challenge to regulate the size effect of electrocatalysts to optimize the catalytic activity and ammonia selectivity.Herein,the Cu-based catalysts were tailored at the atomic level to exhibit a size gradient ranging from single-atom catalysts(SACs,0.15–0.35 nm)to single-cluster catalysts(SCCs,1.0–2.8 nm)and nanoparticles(NPs,20–30 nm),with the aim of studying the size effect for the NO_(3)^(-)-to-NH_(3) reduction reaction.Especially,the Cu SCCs exhibit enhanced metal–substrate and metal–metal interactions by taking advantageous features of Cu SACs and Cu NPs.Thus,Cu SCCs achieve exceptional electrocatalytic performance for the NitRR with a maximum Faradaic efficiency of ca.96%NH_(3)and the largest yield rate of ca.1.99 mg·h^(-1)·cm^(-2) at-0.5 V vs.reversible hydrogen electrode(RHE).The theoretical calculation further reveals the size effect and coordination environment on the high catalytic activity and selectivity for the NitRR.This work provides a promising various size-controlled design strategy for aerogel-based catalysts effectively applied in various electrocatalytic reactions.

关键词： nitrate electroreduction ammonia electrosynthesis size effect single-cluster catalyst

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Formation mechanism of Fe-based amorphous powders produced by spark erosion

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Journal of Materials Science & Technology 2024年第3期170卷 33-46页

作者： Chekai liu Ran Li Jiazi Bi Ding Ma Xiaobin liu Tao Zhang School of Materials Science and Engineering Key Laboratory of Aerospace Materials and Performance(Ministry of Education)Beihang UniversityBeijing 100191China

Spark erosion is a convenient,flexible,and low-cost method to quickly produce fine powders of metals,alloys,and semiconductors in size ranging from nearly a hundred micrometers to submicrometer by repetitive spark discharges.Due to the complexity of the powder-forming journey,normally accompanied by high temperature,high pressure,decomposition,diffusion and rapid quenching caused by discharge plasma,the mechanisms of powder formation and possible contaminant infiltration are still controversial,posing a significant challenge to control particle size and chemical composition of the powder produced by this method.In this study,Fe-based amorphous powders in different particle-size distributions with high sphericity were fabricated by spark erosion under different discharge-energy conditions.The max-imum particle size of the resultant powders can be correlated with discharge parameters,crater depth,and crater radius,respectively.A multi-ring-breakup model is proposed to reveal the particle-size distribution of the powder formed from the electrode melt under a single-pulse discharge.Furthermore,a dielectric-element infiltration model is provided to quantitatively evaluate the infiltration mass ratio of the contaminant elements,stemming from the decomposed products of dielectric liquid,in the resultant powder with different particle sizes.The models verified through the experimental data are significant for the development of high-performance fine Fe-based amorphous powder with controlled particle size and chemical composition.

关键词： Amorphous alloy Particle Spark erosion Infiltration Modeling

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Multi-Time Scale Operation and Simulation Strategy of the Park Based on Model Predictive Control

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Energy Engineering 2024年第3期121卷 747-767页

作者： Jun Zhao Chaoying Yang Ran Li Jinge Song Grid Center State Grid Shanxi Electric Power Company Electric Power Science Research InstituteTaiyuan030000China

Due to the impact of source-load prediction power errors and uncertainties,the actual operation of the park will have a wide range of fluctuations compared with the expected state,resulting in its inability to achieve the expected economy.This paper constructs an operating simulation model of the park power grid operation considering demand response and proposes a multi-time scale operating simulation method that combines day-ahead optimization and model predictive control(MPC).In the day-ahead stage,an operating simulation plan that comprehensively considers the user’s side comfort and operating costs is proposed with a long-term time scale of 15 min.In order to cope with power fluctuations of photovoltaic,wind turbine and conventional load,MPC is used to track and roll correct the day-ahead operating simulation plan in the intra-day stage to meet the actual operating operation status of the park.Finally,the validity and economy of the operating simulation strategy are verified through the analysis of arithmetic examples.

关键词： Demand response model predictive control multiple time scales operating simulation

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Electroencephalogram findings in 10 patients with post-stroke epilepsy:A retrospective study

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World Journal of Clinical Cases 2024年第2期12卷 249-255页

作者： li-Min Wen Ran Li Yan-ling Wang Qing-Xia Kong Min Xia Clinical Medicine College Jining Medical UniversityJining 272067Shandong ProvinceChina School of Basic Medical Sciences Shandong UniversityJinan 250012Shandong ProvinceChina Department of Neurology The Affiliated Hospital of Jining Medical UniversityJining 272007Shandong ProvinceChina

BACKGROUND Post-stroke epilepsy is a common and easily overlooked complication of acute cerebrovascular disease.Long-term seizures can seriously affect the prognosis and quality of life of patients.Electroencephalogram(EEG)is the simplest way to diagnose epilepsy,and plays an important role in predicting seizures and guiding medication.AIM To explore the EEG characteristics of patients with post-stroke epilepsy and improve the detection rate of inter-seizure epileptiform discharges.METHODS From January 2017 to June 2020,10 patients with post-stroke epilepsy in our hospital were included.The clinical,imaging,and EEG characteristics were collected.The stroke location,seizure type,and ictal and interictal EEG manifestations of the patients with post-stroke epilepsy were then retrospectively analyzed.RESULTS In all 10 patients,epileptiform waves occurred in the side opposite to the stroke lesion during the interictal stage;these manifested as sharp wave,sharp-wave complex,or spike discharges in the anterior head lead of the side opposite to the lesion.CONCLUSION In EEG,epileptiform waves can occur in the side opposite to the stroke lesion in patients with post-stroke epilepsy.

关键词： Post-stroke epilepsy Electroencephalogram Seizure Stroke Slow wave

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A Class of m-Complex Symmetric Operators on Hardy Space

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Journal of Mathematical Research with Applications 2024年第1期44卷 63-80页

作者： Jia FU Xinmei li Ran Li School of Mathematics Liaoning Normal University

In this paper,we study the necessary and sufficient condition that the Toeplitz operators with respect to the conjugations of one permutation are 2-complex symmetric.Firstly,we introduce a class of conjugations called the conjugations of one permutations on the classical Hardy space.Secondly,Toeplitz operators are completely characterized as 2-complex symmetric structure under this class of conjugations.The matrix representation of Toeplitz operators in the classical regular orthogonal basis on Hardy space is used to describe this class of 2-complex symmetric Toeplitz operators.Finally,we add two preconditions fn=-f-nand fn=f-nrespectively to the Toeplitz operators,and we get more simplified results.Under the second condition,we study the 3-complex symmetry of Toeplitz operators,and we get the same result for Tfis a 3-CSO with the conjugation C((i,j)) and 2-CSO’s.

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Experimental study on the effect of unloading rate on gneiss rockburst

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第6期16卷 2064-2076页

作者： Dongqiao liu Jie Sun Ran Li Manchao He Binghao Cao Chongyuan Zhang Wen Meng State Key Laboratory for Tunnel Engineering China University of Mining and TechnologyBeijing100083China Key Laboratory of Active Tectonics and Geological Safety Ministry of Natural ResourcesInstitute of GeomechanicsChinese Academy of Geological SciencesBeijing100081China School of Mechanics and Civil Engineering China University of Mining and TechnologyBeijing100083China

Rockburst are often encountered in tunnel construction due to the complex geological conditions.To study the influence of unloading rate on rockburst,gneiss rockburst experiments were conducted under three groups of unloading rates.A high-speed photography system and acoustic emission(AE)system were used to monitor the entire process of rockburst process in real-time.The results show that the intensity of gneiss rockburst decreases with decrease of unloading rate,which is manifested as the reduction of AE energy and fragments ejection velocity.The mechanisms are proposed to explain this effect:(i)The reduction of unloading rate changes the crack propagation mechanism in the process of rockburst.This makes the rockbursts change from the tensile failure mechanism at high unloading rate to the tension-shear mixed failure mechanism at low unloading rate,and more energy released in the form of shear crack propagation.Then,less strain energy is converted into kinetic energy of fragments ejection.(ii)Less plate cracking degree of gneiss has taken shape due to decrease of unloading rate,resulting in the destruction of rockburst incubation process.The enlightenments of reducing the unloading rate for the project are also described quantitatively.The rockburst magnitude is reduced from the medium magnitude at the unloading rate of 0.1 MPa/s to the slight magnitude at the unloading rate of 0.025 MPa/s,which was judged by the ejection velocity.

关键词： Rockburst Unloading rate Crack propagation Influence mechanisms

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A fluorescence-enhanced inverse opal sensing film for multi-sources detection of formaldehyde

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Food Science and Human Wellness 2024年

作者： Xiaokang Lu Bo Han Deyilei Wei Mingzhu Chu Haojie Ma Ran Li Xueyan Hou Yuqi Zhang JiJiang Wang Key Laboratory of New Energy & New Functional Materials Shaanxi Key Laboratory of Chemical Reaction Engineering College of Chemistry and Chemical Engineering Yan’an University

The SiO2inverse opal photonic crystals (PC) with a three-dimensional macroporous structure were fabricated by the sacrificial template method， followed by infiltration of a pyrene derivative， 1-(pyren-8-yl)but-3-en-1-amine (PEA)， to achieve a formaldehyde-sensitive and fluorescence-enhanced sensing film. Utilizing the specific Aza-Cope rearrangement reaction of allylamine of PEA and formaldehyde (FA) to generate a strong fluorescent product emitted at ～480 nm， we chose a PC whose blue band edge of stopband overlapped with the fluorescence emission wavelength. In virtue of the fluorescence enhancement property derived from slow photon effect of PC， FA was detected highly selectively and sensitively. The limit of detection (LoD) was calculated to be 1.38 nmol/L. Furthermore， the fast detection of FA (within 1 min) is realized due to the interconnected three-dimensional macroporous structure of the inverse opal PC and its high specific surface area. The prepared sensing film can be used for the detection of FA in air， aquatic products and living cells. The very close FA content in indoor air to the result from FA detector， the recovery rate of 101.5% for detecting FA in aquatic products and fast fluorescence imaging in 2 min for living cells demonstrate the reliability and accuracy of our method in practical applications.

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All-sky Guide Star Catalog for CSST

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Research in Astronomy and Astrophysics 2024年第4期24卷 35-59页

作者： Hui-Mei Feng Zi-Huang Cao Man I Lam Ran Li Hao Tian Da-Yi Yin Yuan-Yu Yang Xin Zhang Dong-Wei Fan Yi-Qiao Dong Xin-Feng li Wei Wang Long li Hugh RAJones Yi-Han Tao Jia-Lu Nie Pei-Pei Wang Mao-Yuan liu He-jun Yang Chao liu Key Laboratory of Cosmic Rays(Tibet University) Ministry of EducationLhasa 850000China Institute for Frontiers in Astronomy and Astrophysics Beijing Normal UniversityBeijing 102206China National Astronomical Observatories Chinese Academy of SciencesBeijing 100101China University of ChineseAcademy of Sciences Beijing 100049China Shanghai Institute of Technical Physics Chinese Academy of SciencesShanghai200083China Technology and Engineering Center for Space Utilization.Chinese Academy of Sciences Beijing 100094China Changchun Institute of Optics Fine Mechanics and PhysicsChinese Academy of SciencesChangchun 130033China Centre for Astrophysics University of HertfordshireHatfieldUK Beijing University of Technology Beijing 100124China

The China Space Station Telescope(CSST)is a two-meter space telescope with multiple back-end instruments.The Fine Guidance Sensor(FGS)is an essential subsystem of the CSST Precision Image Stability System to ensure the required absolute pointing accuracy and line-of-sight stabilization.In this study,we construct the Main Guide Star Catalog for FGS.To accomplish this,we utilize the information about the FGS and object information from the Gaia Data Release 3.We provide an FGS instrument magnitude and exclude variables,binaries,and high proper motion stars from the catalog to ensure uniform FGS guidance capabilities.Subsequently,we generate a HEALPix index,which provides a hierarchical tessellation of the celestial sphere,and employ the Voronoi algorithm to achieve a homogeneous distribution of stars across the catalog.This distribution ensures adequate coverage and sampling of the sky.The performance of the CSST guide star catalog was assessed by simulating the field of view of the FGS according to the CSST mock survey strategy catalog.The analysis of the results indicates that this catalog provides adequate coverage and accuracy.The catalog's performance meets the FGS requirements,ensuring the functioning of the FGS and its guidance capabilities.

关键词： catalogs astrometry instrumentation:detectors

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Prescribed-time stabilization and inverse optimal control of stochastic high-order nonlinear systems

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Science China(Information Sciences) 2024年第2期67卷 144-156页

作者： Ran LiU Hui WANG Wuquan li School of Mathematics and Statistics Science Ludong University

This paper investigates the prescribed-time state-feedback stabilization and prescribed-time inverse optimality problems for stochastic high-order nonlinear systems. First, a time-varying controller is designed by developing scaled quartic Lyapunov functions, which can guarantee that the system has a unique strong solution almost surely on the prescribed interval for any system initial conditions and that the states and the control converge to the origin in a mean-square form within the prescribed time. Then, the controller is redesigned to address the problem of prescribed-time inverse optimal mean-square stabilization. Finally,a concrete example is provided to confirm the efficiency of the proposed design schemes.

关键词： stochastic high-order nonlinear systems prescribed-time stabilization the scaled design inverse optimality

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Optimization study of spherical tuyere based on BP neural network and new evaluation index

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Building Simulation 2024年第2期17卷 223-234页

作者： Mengchao liu ran Gao Yi Wang Angui li School of Building Services Science and Engineering Xi’an University of Architecture and TechnologyXi’an710055China

The energy consumption of heating,ventilation,and air conditioning(HVAC)systems holds a significant position in building energy usage,accounting for about 65%of the total energy consumption.Moreover,with the advancement of building automation,the energy consumption of ventilation systems continues to grow.This study focuses on improving the performance of spherical tuyeres in HVAC systems.It primarily utilizes neural networks and multi-island genetic algorithms(MIGA)for multi-parameter optimization.By employing methods such as structural parameterization,accurate and fast computational fluid dynamics(CFD)simulations,a minimized sample space,and a rational optimization strategy,the time cycle of the optimization process is shortened.Additionally,a new comprehensive evaluation index is proposed in this research to describe the performance of spherical tuyeres,which can be used to more accurately assess spherical tuyeres with different structures.The results show that by establishing a neural network prediction model and combining it with the multi-island genetic algorithm,a novel spherical tuyere design was successfully achieved.The optimized novel spherical tuyeres achieved a 27.05%reduction in the spherical tuyeres effective index(STEI)compared to the traditional spherical tuyeres.Moreover,the resistance decreased by 15.68%,and the jet length increased by 7.57%.The experimental results demonstrate that our proposed optimization method exhibits high accuracy,good generalization capability,and excellent agreement at different Reynolds numbers.

关键词： spherical tuyeres STEI CFD ventilation

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