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Optimal Model Average Prediction in Orthogonal Kriging Models

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Journal of Systems Science & Complexity 2024年第3期37卷 1080-1099页

作者： WANG jun HE Jiabei liANG Hua li Xinmin School of Mathematics and Statistics Qingdao UniversityQingdao 266071China Department of Statistics George Washington UniversityWashington DC 20052USA

The main objective of this paper is to consider model averaging methods for kriging *** paper proposes a Mallows model averaging procedure for the orthogonal kriging model and demonstrate the asymptotic optimality of the model averaging estimators in terms of mean square *** studies are conducted to evaluate the performance of the proposed method and compare it with the competitors to demonstrate its *** authors also analyse a real dataset for an illustration.

关键词： Asymptotic optimality Mallows criterion optimal model averaging orthogonal kriging model

Experimental Study of Temperature Control Based on Composite Phase Change Materials during Charging and Discharging of Battery

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Journal of Thermal Science 2024年第2期33卷 578-590页

作者： li Xiaolin WANG jun CAO Wenxiang ZHANG Xuesong School of Automotive and Traffic Engineering Jiangsu UniversityZhenjiang212013China

This study is to utilize the heat-absorbing and releasing capabilities of phase change materials(PCM)to regulate the surface temperature fluctuations of batteries during charging and *** goal is to keep the battery within the optimal operating temperature *** impact of PCM thickness and phase change temperature on battery temperature is investigated by encircling a cylindrical battery with a PCM *** improve the thermal conductivity of PCM,expanded graphite(EG) is added to make a composite phase change material(CPCM),and the effects of various EG mass ratios on battery surface temperature and CPCM utilization level are *** findings indicate that increasing PCM thickness effectively extends temperature control time,but its impact is *** difference in phase change temperature of PCM controls the battery temperature in different temperature *** phase change temperatures are unsuitable for controlling battery temperature in high temperature *** addition of EG enhances the thermal conductivity of PCM,leading to further control of battery *** results show that the addition of 6%(mass ratio) EG to CPCM extends the effective temperature control time by 11 min and improves by 28% compared to a single *** CPCM utilization is also more satisfactory and achieved a balance between heat storage and thermal conductivity in a battery thermal management system(BTMS) based on PCM.

关键词： phase change material expanded graphite thermal management system effective control time

Investigation on the influence of vortex generator on particle resuspension

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Particuology 2024年第3期86卷 126-136页

作者： Dongchi Yu jun-li lin Jin-Han Xie ASML 80W Tasman DrSan Jose95134CaliforniaUSA Department of Mechanics and Engineering Science at College of Engineering and State Key Laboratory for Turbulence and Complex Systems Peking UniversityBeijing100081China

The vortex generator(VG)and its well-known effect in flow optimization are widely studied and employed across different engineering ***,while the same working principles of VG may be well suited for the applications on surface-cleaning technologies,such promising potential is hardly,if any,explored in the published ***,in the present study,the influence on flow-induced particle resuspension brought by a rectangular vG in a channel flow is investigated with the help of highfidelity computational fluid dynamics *** increases of particle removal forces and resuspension rates are discovered in long,strip-like regions with reduced boundary-layer thickness resulted from the vG-induced vortices,and the enhancement effect is especially significant for configurations with the VG installed at a greater angle of *** is also shown that while the resuspension enhancements on the lower and the upper surfaces of the channel exhibit distinct statistical characteristics,having a VG in the channel improves the overall particle-removing capability of the channel flow by introducing higher surface-averaged removal forces and particle resuspension *** but not least,the increase of resuspension rate is especially significant for the smaller,micron-scale particles which are otherwise hardly disturbed by a VG-less channel flow,and such resuspension-enhancement effectgenerally subsides with increasing particle size.

关键词： Particle resuspension Vortexgenerator CFD Surface cleaning

In-situ measurement via the flow-through method and numerical simulations for radon exhalation during measurements of the radon exhalation rate

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Nuclear Science and Techniques 2024年第7期35卷 192-207页

作者： ming Xia Yong-jun Ye Shan-Wei Shang Ting Yu Dai-Jia Chen School of Resources Environment and Safety Engineering University of South ChinaHengyang421001China Key Discipline Laboratory for National Defense for Biotechnology in Uranium Mining and Hydrometallurgy University of South ChinaHengyang421001China

Small-scale measurements of the radon exhalation rate using the flow-through and closed-loop methods were conducted on the surface of a uranium tailing pond to better understand the differences between the two *** abnormal radon exhalation behavior was observed,leading to computational fluid dynamics(CFD)-based simulations in which dynamic radon migration in a porous medium and accumulation chamber was *** on the in-situ experimental and numerical simulation results,variations in the radon exhalation rate subject to permeability,flow rate,and insertion depth were quantified and *** in-situ radon exhalation rates measured using the flow-through method were higher than those measured using the closed-loop method,which could be explained by the negative pressure difference between the inside and outside of the chamber during the *** consistency of the variations in the radon exhalation rate between the experiments and simulations suggests the reliability of CFD-based techniques in obtaining the dynamic evolution of transient radon exhalation rates for diffusion and convection at the porous medium-air *** synergistic effects of the three factors(insertion depth,flow rate,and permeability)on the negative pressure difference and measured exhalation rate were quantified,and multivariate regression models were established,with positive correlations in most cases;the exhalation rate decreased with increasing insertion depth at a permeability of 1×10^(−11) m^(2).CFD-based simulations can provide theoretical guidance for improving the flow-through method and thus achieve accurate measurements.

关键词： Radon exhalation Flow-through Numerical simulation Accumulation chamber Multivariate regression

Structural engineering of hard carbon through spark plasma sintering for enhanced sodium-ion storage

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Rare Metals 2024年第9期43卷 4274-4285页

作者： Hao-ming Xiao Heng Zheng Ping Yuan jun-Hui Luo lin-lin Shen Jie-Feng Tan Xian-You Luo De li Yong Chen Guangdong Key Laboratory for Hydrogen Energy Technologies School of Materials Science and Hydrogen EnergyFoshan University State Key Laboratory of Marine Resource Utilization in South China Sea Hainan Provincial Key Laboratory of Research on Utilization of Si-Zr-Ti ResourcesHainan University

Hard carbon （HC） has emerged as one of the superior anode materials for sodium-ion batteries （SIBs）,with its electrochemical performance significantly influenced by the presence of oxygen functional groups and its closed pore ***,current research on the structural adjustment of these oxygen functional groups and the closed pore architecture within HC remains ***,energy-efficient and contamination-free spark plasma sintering technology was employed to tune the structure of coconut-shell HC,resulting in significant adjustments to the content of carboxyl （decreasing from 5.71 at%to 2.12 at%） and hydroxyl groups （decreasing from 7.73 at % to 6.26 at%）.Crucially,these modifications reduced the irreversible reaction of oxygen functional groups with Na+.Simultaneously,a substantial number of closed pores with an average diameter of 1.22 nm were generated within the HC,offering an ideal environment for efficient Na+*** structural changes resulted in a remarkable improvement in the electrochemical performance of the modified *** reversible specific capacity of the modified HC surged from 73.89 mAh·g-1to an impressive 251.97 m Ah·g-1at a current density of 50 mA·*** at 400 mA·g-1,the reversible specific capacity increased significantly from 14.55 to 85.44 mAh·***,this study provides a novel perspective for designing tailored HC materials with the potential to develop high-performance SIBs.

关键词： Closed pores Hard carbon Oxygen functional groups Sodium-ion batteries Spark plasma sintering

Boost VS_(2) electrochemical reactive kinetics by regulating crystallographic planes and coupling carbon matrix for high performance sodium-ion storage

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Rare Metals 2024年第1期43卷 98-112页

作者： Min Zeng ming-Shan Wang lin Chen En-Zhi li Zhen-liang Yang Dan Zhou Hai-Jiao Xie jun-Chen Chen Zhi-Yuan Ma Bing-Shu Guo Bo Yu Xing li School of New Energy and Materials Southwest Petroleum UniversityChengdu 610500China Energy Storage Research Institute Southwest Petroleum UniversityChengdu 610500China Institute of Materials China Academy of Engineering PhysicsMianyang 621908China Beijing Advanced Innovation Center for Materials Genome Engineering University of Science and TechnologyBeijingBeijing 100083China Hangzhou Yanqu Information Technology Co. Ltd.Hangzhou 310003China

Vanadium disulfide(VS_(2)) as a typical two-dimensional transition metal chalcogenide has excellent competitiveness for sodium-ion storage due to its wide layer spacing(0.575 nm),high theoretical capacity of 932mAh·g^(-1) originating from multi-electron electrochemical ***,continuous sodiation process accompanied by crystal structural evolution and collapse cause rapid capacity ***,novel few-layer VS_(2)nanosheets with open(001) crystal planes are in-situ constructed on reduced graphene oxide to solve these issues mentioned *** indicates that few-layer VS_(2)provides more Na^(+) storage activity due to the low Na^(+)surface migration energy barrier on exposed crystal(001)*** flexible and high electronic conductivity of carbon matrix also effectively builds multi-level buffer structure and electron transport kinetics to boost the Na^(+)insertion/conversion reactive activity on VS_(2) as well as Na^(+) pseudocapacitance storage kinetics on edges and defects of nano *** coupling effects result in high rate capability and long cycling stability as a battery/capacitor *** delivers conspicuous high energy density of 81 and 40 Wh·kg^(-1) at power density of 118 and 10,286W·kg^(-1),as well as 80% energy retention rate after 5000cycles,confirming its great application potential in sodiumbased storage devices.

关键词： Vanadium disulfide Reduced graphene oxide Anode Sodium-ion battery Sodium-ion capacitor

Two-way shape memory effect in a Ti-Zr-Nb-Ta high-temperature shape memory alloy

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Rare Metals 2024年第3期43卷 1257-1262页

作者： Cheng-Yang Xiong Tuo li jun Wang Yan li School of Materials Science and Engineering Beihang UniversityBeijing100191China

The two-way shape memory effect in a Ti-18.5Zr-10Nb-3.5Ta high-temperature shape memory alloy was investigated.X-ray diffraction measurem ent shows that the alloy is composed of orthorhombicα"-martensite.ωphase is not found in Ti-18.5Zr-10Nb-3.5Ta alloy due to the suppressing effect of Ta ***α"-martensite laths are found in the transmission electron microscope observation;after the bending deformation,there appear a lot of *** alloy exhibits a shape memory strain of 3.8%aud a high reverse martensite transformation start temperature of 464 *** maximum two-way shape memory strain of 1.2%is obtained in the alloy with the prebending training strain of 10%.The mechanism can be ascribed to the effect of internal stress field caused by dislocations.

关键词： Ti-Zr Shape memory alloys Two-way shape memory effect

CoFe_(2)O_(4) decorated graphene/C_(18)-functionalized mesoporous silica nanocomposites prepared for magnetic enrichment and electrochemical detection of promethazine in beef

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Chinese Chemical Letters 2024年第3期35卷 208-213页

作者： Xingdong Yang Shi-ming Ying Sen Zhang Jinxia Dai Wei Gao Tian-Qi Wang jun-Qin Qiao Hong-Zhen lian li Mao State Key Laboratory of Analytical Chemistry for life Science School of Chemistry&Chemical Engineering and Centre of Materials AnalysisNanjing UniversityNanjing 210023China Ministry of Education(MOE)Key Laboratory of Modern Toxicology School of Public HealthNanjing Medical UniversityNanjing 211166China

Promethazine(PHZ)is used as a sedative in veterinary medicine,and its residue can threaten the health of *** electrochemical detection of PHZ is suitable method for application in the ***,the traditional electroanalysis is difficult to perform directly in meat samples due to matrix *** work integrates magnetic solid-phase extraction and differential pulse voltammetry for highly sensitive and selective determination of PHZ in beef and beef liver for the first ***_(2)O_(4)/graphene coated with C_(18)-functionalized mesoporous silica(MG@mSiO_(2)-C_(18))is synthesized as dispersed magnetic adsorbent to extract *** glassy carbon electrode modified with nitrogen-doped hollow carbon microspheres(HCM)attracts the MG@mSiO_(2)-C_(18)with PHZ,and directly detects the PHZ without elution ***@mSiO_(2)-C_(18)can separate PHZ to avoid the interference of impurities on following detection,and also concentrate PHZ on magnetic ***,the electrode modification with HCM can amplify the electrochemical signal of ***,the integrated PHZ determination method exhibits a wide linear range from 0.08μmol/L to 300μmol/L with a low limit of detection of 9.8 nmol/*** beef sample analysis presents excellent recovery,demonstrating that this protocol is promising for the rapid and onsite detection of PHZ in real meat samples。

关键词： Promethazine(PHZ) Drug residue Magnetic solid phase extraction Electrochemical detection Beef

Classification of complete 3-dimensional self-shrinkers in the Euclidean space R^(4)

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Science China Mathematics 2024年第4期67卷 873-882页

作者： Qing-ming Cheng Zhi li Guoxin Wei Department of Applied Mathematics Faculty of ScienceFukuoka UniversityFukuoka 814-0180Japan College of Mathematics and Information Science Henan Normal UniversityXinxiang 453007China School of Mathematical Sciences South China Normal UniversityGuangzhou 510631China

In this paper,we completely classify 3-dimensional complete self-shrinkers with the constant norm S of the second fundamental form and the constant f3in the Euclidean space R^(4),where hij’s are components of the sec... 详细信息

关键词： mean curvature ow self-shrinker the generalized maximum principle