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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

Sustainable and practical semi-heterogeneous photosynthesis of 5-amino-1,2,4-thiadiazoles over WS_(2)/TEMPO

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Chinese Chemical Letters 2024年第8期35卷 250-253页

作者： jia-Cheng Hou Hong-Tao Ji Yu-Han Lu jia-Sheng Wang Yao-Dan Xu yan-yan Zeng Wei-Min He School of Chemistry and Chemical Engineering University of South ChinaHengyang 421001China

An eco-friendly and practical method for the clean preparation of 5-amino-1,2,4-thiadiazoles was *** WS_(2)as the semiconductor photocatalyst,both TEMPO and O_(2)(in air)as the redox catalysts,a variety of thiadiazoles were semi-heterogeneously formed in high to quantitative yields and could be easily collected by CPME extraction and ***,the catalytic system can be reusable for at least 5 reaction runs.

关键词： Green chemistry Thiadiazoles Heterogeneous catalyst Redox catalyst Extraction

Special Unipotent Representations of Simple Linear Lie Groups of Type A

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Acta Mathematica Sinica,English Series 2024年第3期40卷 707-716页

作者： Dan BARBASCH jia jun MA Bin Yong SUN Chen Bo ZHU Department of Mathematics Cornell UniversityIthacaNY 14853USA School of Mathematical Sciences Xiamen UniversityXiamen 361005P.R.China Department of Mathematics Xiamen University Malaysia CampusSepangSelangor Darul Ehsan43900Malaysia Institute for Advanced Study in Mathematics&New Cornerstone Science Laboratory Zhejiang UniversityHangzhou 310058P.R.China Department of Mathematics National University of Singapore10 Lower Kent Ridge RoadSingapore 119076

Let G be a special linear group over the real,the complex or the quaternion,or a special unitary *** this note,we determine all special unipotent representations of G in the sense of Arthur and Barbasch-Vogan,and show... 详细信息

关键词： Special unipotent representations unitary representations coherent continuation Weyl group representations

Switched-capacitor Based Seven-level Boost Inverter with a Reduced Number of Devices

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CSEE Journal of Power and Energy Systems 2024年第1期10卷 381-391页

作者： Weijie Lin jun Zeng Bo Fu Zhixing yan junfeng Liu School of Electric Power Engineering South China University of TechnologyGuangzhou 510641China WISDRI Engineering&Research Incorporation Limited Wuhan 430074China Department of Energy Aalborg UniversityAalborg 9220Denmark School of Automation Science and Engineering South China University of TechnologyGuangzhou 510641China

The conventional multilevel inverters(MLIs)have the disadvantages of numerous devices,incapacity of boost,unbalance for capacitor’s voltage,high complexity for control,and *** by this issue,a seven-level boost inverter(7LBI)based on a switched capacitor is presented for singlephase applications in this *** proposed 7LBI using only seven transistors can achieve seven output levels,1.5 voltage gain,and natural balance of capacitors’voltages without sensors or other auxiliary methods,which illustrates its suitability for the applications of renewable energy *** configuration of topology and operating principles are illustrated in *** natural balance of capacitors and capacitance calculations are deduced as ***,the comparative study is conducted for different types of *** results illustrate the merits of the proposed 7LBI with respect to reduced devices,lower voltage stress,and less power ***,a simulation for the proposed 7LBI with PWM modulation is realized based on the theoretical analysis;an experimental prototype is also implemented,verifying multilevel output,boost ability,natural balance for switched capacitors,and performance of transient response.

关键词： Multilevel inverters voltage gain natural balance renewable energy generation reduced number of elements

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

Simultaneous Bulk-and Surface-initiated Living Polymerization Studied with a Heterogeneous Stochastic Reaction Model

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Chinese Journal of Polymer Science 2024年第3期42卷 364-372,I0008页

作者： jia-Shu Ma Zhi-Ning Huang jia-Hao Li Bang-Ping jiang yan-Da Liao Shi-Chen Ji Xing-Can Shen State Key Laboratory for Chemistry and Molecular Engineering of Medicinal Resources Key Laboratory for Chemistry and Molecular Engineering of Medicinal Resources(Ministry of Education of China)School of Chemistry and Pharmaceutical SciencesGuangxi Normal UniversityGuilin 541004China School of Computer Science and Engineering&School of Software Guangxi Normal UniversityGuilin 541004China

To better characterize the properties of surface-initiated polymers, simultaneous bulk-and surface-initiated polymerizations are usually carried out by assuming that the properties of the surface-initiated polymers resemble those of the bulk-initiated polymers. Through a Monte Carlo simulation using a heterogeneous stochastic reaction model, it was discovered that the bulk-initiated polymers exhibit a higher molecular weight and a lower dispersity than the corresponding surface-initiated polymers, which indicates that the equivalent assumption is invalid. Furthermore, the molecular weight distributions of the two types of polymers are also different, suggesting different polymerization mechanisms. The results can be simply explained by the heterogeneous distributions of reactants in the system. This study is helpful to better understand surface-initiated polymerization.

关键词： Surface-initiated polymerization Polymer brush Stochastic reaction model Heterogeneous polymerization Simultaneous polymerization

High-entropy oxide-supported platinum nanoparticles for efficient hydrogen evolution reaction

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Rare Metals 2024年第4期43卷 1537-1546页

作者： Ming-Yu Fan jia-jun Wang jun Zhao Hong Zhang Tian-Yi Ma Xiao-Peng Han Wen-Bin Hu School of Materials Science and Engineering Tianjin Key Laboratory of Composite and Functional Materials Key Laboratory of Advanced Ceramics and Machining TechnologyTianjin UniversityTianjin300350China Joint School of National University of Singapore and Tianjin University International Campus of Tianjin UniversityFuzhou350207China School of Science RMIT UniversityMelbourneVIC3000Australia

High-entropy oxides(HEOs)are a new class of single-phase structures with unique electronic and catalytic properties;therefore,it is worthwhile to explore their applications in *** this study,a Pt/(FeCoNiCrAl)_(3)O_(4)nanohybrid using HEO as a support was developed as an efficient catalyst for the hydrogen evolution reaction(HER).Pt/(FeCoNiCrAl)_(3)O_(4)exhibited high HER activity with a low overpotential of 22 mV at10 mA·cm^(-2),outperforming other binary,ternary,and quaternary *** HER activity of Pt/(FeCoNiCrAl)_(3)O_(4)was higher than that of a commercial Pt/C with a significantly lower Pt *** catalyst exhibited good activity and long-term stability(60 h)in an electrolytic water-splitting *** good activity can be attributed to the fact that the introduction of Pt effectively facilitates electronic interactions between Pt and the *** addition,the HEO substrate was more favorable for dispersing Pt particles,optimizing the electrochemical specific surface area,and significantly reducing the charge resistance of the *** study extends the application of HEOs in electrocatalysis and demonstrates the promising prospects of HEOs as supports for electrocatalysts.

关键词： High-entropy oxides Hydrogen evolution reaction Nanohybrid Water electrolysis

A Novel Disturbance Observer Based Fixed-Time Sliding Mode Control for Robotic Manipulators With Global Fast Convergence

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IEEE/CAA Journal of Automatica Sinica 2024年第3期11卷 661-672页

作者： Dan Zhang jiabin Hu jun Cheng Zheng-Guang Wu Huaicheng yan IEEE Zhejiang University of Technology Guangxi Normal University Zhejiang University the East China University of Science and Technology

This paper proposes a new global fixed-time sliding mode control strategy for the trajectory tracking control of uncertain robotic ***,a fixed-time disturbance observer(FTDO) is designed to deal with the adverse effects of model uncertainties and external disturbances in the manipulator *** an adaptive scheme is used and the adaptive FTDO(AFTDO) is developed,so that the priori knowledge of the lumped disturbance is not ***,a new non-singular fast terminal sliding mode(NFTSM) surface is designed by using an arctan function,which helps to overcome the singularity problem and enhance the robustness of the *** on the estimation of the lumped disturbance by the AFTDO,a fixed-time non-singular fast terminal sliding mode controller(FTNFTSMC)is developed to guarantee the trajectory tracking errors converge to zero within a fixed *** settling time is independent of the initial state of the *** addition,the stability of the AFTDO and FTNFTSMC is strictly proved by using Lyapunov ***,the fixed-time NFESM(FTNFTSM) algorithm is validated on a 2-link manipulator and comparisons with other existing sliding mode controllers(SMCs) are *** comparative results confirm that the FTNFTSMC has superior control performance.

关键词： Disturbance observer(DO) fixed-time non-singular sliding mode control robotic manipulator trajectory tracking

近红外光谱技术(NIRS)在牧草领域中的应用研究进展

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光谱学与光谱分析 2012年第7期32卷 1748-1753页

作者：严旭白史且鄢家俊干友民刀志学四川农业大学草业科学系四川雅安625014 四川省草原科学研究院四川成都611731 西南民族大学生命科学与技术学院四川成都610041

牧草是草食动物最主要的营养来源。牧草品质的优劣不仅影响家畜的生长发育和生产效率,也决定着最终畜产品的产量与品质。牧草品质的优劣主要取决于牧草营养成分及其消化率、适口性、以及牧草中所含抗营养因子和真菌毒素、霉菌毒素的含... 详细信息

牧草是草食动物最主要的营养来源。牧草品质的优劣不仅影响家畜的生长发育和生产效率,也决定着最终畜产品的产量与品质。牧草品质的优劣主要取决于牧草营养成分及其消化率、适口性、以及牧草中所含抗营养因子和真菌毒素、霉菌毒素的含量水平。近红外光谱技术(NIRS)是一种低成本、快速、简单、无损的定性、定量分析技术,已在许多领域广泛应用。该文简要介绍了NIRS的原理和特点,详细综述了NIRS在牧草品质分析、牧草育种、牧草品种鉴定和性状分类中的应用。通过较全面综述NIRS在牧草领域中的应用现状,以期有助于NIRS在我国牧草领域中的发展。

关键词：牧草近红外光谱技术(NIRS) 品质育种鉴定分类