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Effect of preparation methods on Pt/alumina catalysts for the hydrogen iodide catalytic decomposition

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Chinese Chemical Letters 2009年第1期20卷 102-105页

作者： Zhi Chao wang lai jun wang Ping Zhang Song Zhe Chen Jing Ming Xu Jing Chen Laboratory 201 Institute of Nuclear and New Energy Technology Tsinghua University Beijing 102201 China

Three kinds of Pt/alumina catalysts were prepared by impregnation-hydrogen reduction, impregnation-hydrazine reduction and electroless plating methods. Their differences in the structures, specific areas and particle sizes were characterized by XRD, BET and TEM, respectively. Furthermore, their catalytic activities for the hydrogen iodide （HI） decomposition were evaluated in a fixed bed reactor. The results show that the catalyst 5%Pt/Al2O3 prepared by the electroless plating has the optimum catalytic properties for HI decomposition owing to the high dispersion of the platinum nano-particles （〈5 nm） on the alumina supports.

关键词： Hydrogen iodide Catalytic decomposition Pt/At2O3 Preparation methods

A Multi-faceted View of the X-Ray Spectral Variability in Seyfert Galaxy Ark 120

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Research in Astronomy and Astrophysics 2025年第1期25卷 228-239页

作者： Lu-Xin Ren jun-Xian wang Jia-lai Kang CAS Key Laboratory for Research in Galaxies and Cosmology Department of AstronomyUniversity of Science and Technology of China School of Astronomy and Space Science University of Science and Technology of China

Utilizing a range of techniques including multi-band light curves,softness ratio analysis,structure functions,rms spectra,cross-correlation functions,and ratios of spectra from different intervals,we present a comprehensive study of the complex X-ray spectral variability in Seyfert 1 galaxy Ark 120,through re-analyzing its six XMM-Newton observations taken between 2003 and *** find a clear“softer-when-brighter”trend in the 2–10 ke V power-law component over long timescales,with this trend being timescale dependent,as it is much weaker on shorter timescales,similar to that previously detected in NGC ***,a rare“harder-when-brighter”trend is observed during one exposure,indicating dynamic changes in the spectral variability behavior of the power-law *** exceptional exposure,with the spectral variability indeed marked by a power-law pivoting at an unusually low energy of～2 ke V,suggests intricate variations in the thermal Comptonization processes within the ***,when the data below 2 ke V are included,we identify that the soft excess component adds significant complexity to the spectral variability,such as evidenced by a transition from“harder-when-brighter”to“softer-when-brighter”during another single *** extra complexity arises because the variability of the soft excess sometimes follows and sometimes does not follow the changes in the power-law *** findings underscore the necessity of applying multiple analytic techniques to fully capture the multifaceted spectral variability of AGNs.

关键词： galaxies: active galaxies: Seyfert X-rays: galaxies

Preparation of High Surface Area, Large Pore Volume Alumina by Using β-Cyclodextrin as a Non-surfactant Template

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Chinese Chemical Letters 2006年第9期17卷 1239-1242页

作者： lai jun wang Ming Fen WEN Yu Shan LI Dong YANG Jing CHEN Chong Li SONG Laboratory 201 Institute of Nuclear and New Energy Technology Tsinghua University Beijing 102201

A series of alumina samples were prepared using β-cyclodextrin as the non-surfactant template. These samples were characterized by XRD, BET and TEM. The results showed that the alumina samples prepared using β-cyclodextrin template had the higher surface areas （124-484 m^2/g）, larger pore volumes （0.7-1.27 mL/g） and more thermal stability than samples prepared without using β-cyclodextrin.

关键词： Al2O3 β-cyclodextrin templating method specific surface area.

Structural Modal Parameter Recognition and Related Damage Identification Methods under Environmental Excitations: A Review

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Structural Durability & Health Monitoring 2025年第1期19卷 25-54页

作者： Chao Zhang Shang-Xi lai Hua-Ping wang School of Civil Engineering and Mechanics Lanzhou UniversityLanzhou730000China Key Laboratory of Special Functional Materials and Structural Design Ministry of EducationLanzhou UniversityLanzhou730000China

Modal parameters can accurately characterize the structural dynamic properties and assess the physical state of the ***,it is particularly signiﬁcant to identify the structural modal parameters according to the monitoring data information in the structural health monitoring(SHM)system,so as to provide a scientiﬁc basis for structural damage identiﬁcation and dynamic model modiﬁ*** view of this,this paper reviews methods for identifying structural modal parameters under environmental excitation and brieﬂy describes how to identify structural damages based on the derived modal *** paper primarily introduces data-driven modal parameter recognition methods(e.g.,time-domain,frequency-domain,and time-frequency-domain methods,etc.),brieﬂy describes damage identiﬁcation methods based on the variations of modal parameters(e.g.,natural frequency,modal shapes,and curvature modal shapes,etc.)and modal validation methods(e.g.,Stability Diagram and Modal Assurance Criterion,etc.).The current status of the application of artiﬁcial intelligence(AI)methods in the direction of modal parameter recognition and damage identiﬁcation is further *** on the pre-vious analysis,the main development trends of structural modal parameter recognition and damage identiﬁcation methods are given to provide scientiﬁc references for the optimized design and functional upgrading of SHM systems.

关键词： Structural health monitoring data information modal parameters damage identiﬁcation AI method

Boron shielding design for neutron and gamma detectors of a pulsed neutron tool

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Nuclear Science and Techniques 2025年第1期36卷 115-126页

作者： Xin-Yang wang jun-Yan Chen Qiong Zhang University of Electronic Science and Technology of China Chengdu 611731China

Shielding materials are critical for downhole pulsed neutron tool design because they directly influence the accuracy of formation measurements.A well-designed shield configuration ensures that the response of the tool is maximally representative of the formation without being affected by the tool and borehole *** study investigated the effects of boron-containing materials on neutron and gamma detectors based on a newly designed logging-while-drilling tool that is currently undergoing *** the boron content increased,the ability to absorb thermal neutrons increased *** simulation,it was proven that boron carbide(B_(4)C)can be used as an effective boron shielding material for thermal neutrons,and is therefore employed in this *** shield against thermal neutrons migrating from the mud pipes,the optimal shielding thicknesses for the near-and far-neutron detectors were determined to be 5 and 4 *** a porosity of 25 p.u.,near-neutron sensitivity exhibited a 5.6%***,to shield the capture gamma generated by thermal neutrons once they enter the tool from the mud pipe and formation,internal and external shields for the gamma detector were *** results show that the internal shield requires a boron content of 75%,whereas the external shield has a thickness of 14.2 mm thickness and a boron content of 25%to minimize the tool effect.

关键词： Nuclear well logging Pulsed neutron tool Boron shielding

Civil aviation emissions in China in 2019:Characteristics and abatement potential

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Journal of Environmental Sciences 2025年第5期151卷 225-237页

作者： Haowen An Yu wang Yaxin wang jun Liu Xiaolong Tang Honghong Yi Department of Environmental Engineering School of Energy and Environmental EngineeringUniversity of Science and Technology BeijingBeijing 100083China Key Laboratory of Beijing Municipal Industry Pollutant Resources Processing Beijing 100083China

Civil aviation is one of the industries facing the greatest challenge in reaching carbon neutrality by the middle of this century,and this sector also contributes to adverse impacts on the regional air quality and human *** exhibits the second highest air passenger turnover *** understanding of civil aviation emissionsmust be urgently enhanced,and themitigation potential should be *** this study,on the basis of real domestic flight information for 2019,we built a greenhouse gas and air pollution emission inventory for the civil aviation sector in China with the fuel flowmethod based on the cruise and other *** thoroughly analyzed emissions by region,aircraft and engine types,and aircraft age,based on which we designed four measures to evaluate the abatement *** found that the hydrocarbon(HC),CO,NO_(x),SO_(2),particulate matter(PM)and CO_(2)emissions in 2019 reached 79.9 kt(95%CI[51.6–114.5]),176.3 kt(95%CI[114.5–248.2]),304.2 kt(95%CI[203.4–420.7]),23.2 kt(95%CI[14.2–33.7]),1.0 kt(95%CI[0.61–1.44])and 87.0 Mt(95%CI[57.4–119.6]),*** cruise phase was the major emission phase,accounting for 67%-87%of the total pollutant *** four measures were jointly implemented,the HC,CO,NO_(x),SO_(2),PM and CO_(2)emissions could be reduced by 61%,54%,55%,45%,32%and 38%,*** lower-emission aircraft and switching travel modes could substantially reduce civil aviation emissions in China.

关键词： Emission inventory Fuel flow method Cruise emission Age structure Reduction measures

Adsorption of typical NDMA precursors by superfine powdered activated carbon:Critical role of particle size reduction

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Journal of Environmental Sciences 2025年第1期147卷 101-113页

作者： Ying wang Zhichen Zhang Zhihang Yin jun wang Xiaojian Zhang Chao Chen State Key Joint Laboratory of Environmental Simulation and Pollution Control School of EnvironmentTsinghua UniversityBeijing 100084China Research Institute for Environmental Innovation(Suzhou) TsinghuaSuzhou 215163China

Control of N-nitrosodimethylamine(NDMA)in drinking water could be achieved by removing its precursors as one practical ***,superfine powdered activated carbons with a diameter of about 1μm(SPACs)were successfully prepared by grinding powdered activated carbon(PAC,D50=24.3μm)and applied to remove model NDMA precursors,***(RAN)and nizatidine(NIZ).Results fromgrain diameter experiments demonstrated that the absorption velocity increased dramatically with decreasing particle size,and the maximum increase in k2 was 26.8-folds for RAN and 33.4-folds for ***,kinetic experiments explained that rapid absorption could be attributed to the acceleration of intraparticle diffusion due to the shortening of the diffusion ***,performance comparison experiments suggested that the removal of RAN and NIZ(C_(0)=0.5 mg/L)could reach 61.3%and 60%,respectively,within 5 min,when the dosage of SAPC-1.1(D_(50)=1.1μm)was merely 5 mg/L,while PAC-24.3 could only eliminate 17.5%and 18.6%.The adsorption isotherm was well defined by Langmuir isotherm model,indicating that the adsorption of RAN/NIZ was a monolayer coverage *** adsorption of RAN or NIZ by SAPC-1.1 and PAC-24.3 was strongly pH dependent,and high adsorption capacity could be observed under the condition of pH>pk_(a)+*** coexistence of humic acid(HA)had no significant effect on the adsorption performance because RAN/NIZ may be coupled with HA and removed *** coexistence of anions had little effect on the adsorption *** study is expected to provide an alternative strategy for drinking water safety triggered by NDMA.

关键词： Adsorption NDMA Kinetics Superfine powdered activated carbon Intraparticle diffusion Drinking water

Carbody sway behaviour of railway vehicles due to track irregularity from rail alternate side wear

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RAILWAY ENGINEERING SCIENCE 2025年第1期33卷 27-42页

作者： Wei, lai Zeng, Jing Luo, Ren Gan, Feng Gong, Jijun Jiang, jun Southwest Jiaotong Univ State Key Lab Rail Transit Vehicle Syst Chengdu 610031 Peoples R China China Railway Mat Operat & Maintenance Technol Co Beijing 10071 Peoples R China

Track irregularity from rail alternate side wear is manifested as uneven rail wear waveforms alternating in the left and right rails with equal intervals, which will cause carbody sway behaviour of railway vehicles and greatly influences the passenger comfort. In this work, the carbody sway behaviour and mechanism due to track irregularity from rail alternate side wear and possible solutions to this issue were studied by the field testing and numerical calculation approaches. First, the carbody sway of an urban rail transit train is introduced with full-scale field tests, through which the rail alternate side wear is characterized and the formatted track irregularity are presented. Then, multibody vehicle dynamic models are developed to reproduce the carbody sway behaviour induced by the track irregularity from the rail alternate side wear. The creep forces acting on the wheel and rail are preliminarily discussed to study the influence of the carbody sway on the wear of the wheel flange and the rail corner. Finally, some potential solutions, e.g. improving the damping ratio of carbody rigid mode and rail grinding, are proposed to relieve this issue. It is concluded that an increased damping ratio of the carbody mode can alleviate the carbody sway and wheel-rail interactions, while properly maintaining track conditions can improve the vehicle performance.

关键词： Carbody sway Track irregularity Rail wear Creep force Carbody mode

Hausdorff Measure of Space Anisotropic Gaussian Processes with Non-stationary Increments

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Acta Mathematicae Applicatae Sinica 2025年第1期41卷 114-132页

作者： jun wang Zhen-long CHEN Wei-jie YUAN Guang-jun SHEN School of Mathematics and Physics Anhui Polytechnic UniversityWuhu 241000China School of Statistics and Mathematics Zhejiang Gongshang UniversityHangzhou 310018China Department of Mathematics Anhui Normal UniversityWuhu 241000China

Let X={X(t),t∈R+} be a centered space anisotropic Gaussian process values in R^(d) with non-stationary increments,whose components are independent but may not be identically *** certain conditions,then almost surely c_(1)≤ϕ-m(X([0,1]))≤c_(2),where ϕ denotes the exact Hausdorff measure associated with function ϕ(s)=s1/α_(k)+Σ_(i=1)k(1-αi/αk)log log 1/s for some 1≤k≤d,(α_(1),…,α_(d))∈(0,1]^(d).We also obtain the exact Hausdorff measure of the graph of X on[0,1].

关键词： Hausdorff measure self-similar Gaussian processes non-stationary increment Lamperti theorem