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Dynamic impact of boulders on different types of concrete dam

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Journal of Mountain Science 2022年第10期19卷 2920-2934页

作者： feng Zhu-jun WANG xiu-li RAN Yong-hong School of Civil Engineering Lanzhou University of TechnologyLanzhou 730050China Western Center of Disaster Mitigation in Civil Engineering of Ministry of Education Lanzhou University of TechnologyLanzhou 730050China

Concrete dams are reliable when subjected to static loads such as earth pressure and water ***,the dam failure would be abrupt and catastrophic if it is impacted by *** study simulated the dynamic response of flat dam,concave dam,and convex dam under the impact of boulders by using ANSYS/LS-DYNA finite element *** the numerical simulation,the strain rate effect under the impact load is considered,and Holmquist-Johnson-Cook(HJC)model-a dynamic damage constitutive model is applied to concrete *** show that the peak impact force of concave dam is ***,for different dam types(flat dam,concave dam,and convex dam)and impactor velocities(5,10,and 15 m/s),the impact force fluctuates with the height of the impact point and it reaches the maximum value when the height of the impact point is 2/3 of the dam *** simulation mainly considers different masses and velocities and obtains empirical formulae of impact force for three dam *** established empirical formula for the flat dam is compared with the existing classical formula and several similar experimental *** was found that the newly empirical formulae are reasonable and effective,and it provides design suggestions for similar concrete dams.

关键词： Concrete dam Boulders impact Impact force Numerical simulation HJC constitutive model

Experimental Study of Isopropanol Dehydrogenation over Amorphous Alloy Raney Nickel Catalysts

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Journal of Thermal Science 2013年第6期22卷 613-618页

作者： XIN Fang XU Min LI Xun-feng HUAI xiu-Lan Institute of Engineering Thermophysics Chinese Academy of Sciences University of Chinese Academy of Sciences

The dehydrogenation reaction of isopropanol occurring at low temperature is of great industrial importance. It is a key procedure in isopropanol/acetone/hydrogen chemical heat pump system. An experimental investigation was performed to study the behavior of the liquid phase dehydrogenation of isopropanol over amorphous alloy Raney nickel catalysts. Un-promoted and promoted catalysts were used and their performances were compared under various catalyst amounts, acetone content in the reactant and reaction temperature ranging from 348 K to 355 *** is found that there exists an optimum catalyst concentration which is about 0.34 g in 300 ml isopropanol. The temperature has evident effect on the reaction. The presence of activities of Fe-promoted catalyst decrease slightly compared to the un-promoted catalyst when the temperature are 348 K and 351 K. Besides, the reaction rate decreases almost linearly with the increase of acetone volume fraction in the reactant.

关键词： Chemical heat pump Liquid-phase dehydrogenation Isopropanol

Equilibrium dividend strategies in the dual model with a random time horizon

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Applied Mathematics(A Journal of Chinese Universities) 2023年第4期38卷 510-522页

作者： ZHAO Yong-xia YE Chuan-xiu cheng Gong-pin School of Statistics and Data Science Qufu Normal UniversityQufu 273165China School of Mathematical Sciences Qufu Normal UniversityQufu 273165China School of Economics Nanjing University of Finance and EconomicsNanjing 210046China

This paper investigates the dividend problem with non-exponential discounting in a dual *** assume that the dividends can only be paid at a bounded rate and that the surplus process is killed by an exponential random *** the non-exponential discount function leads to a time inconsistent control problem,we study the equilibrium HJB-equation and give the associated verification *** the case of a mixture of exponential discount functions and exponential gains,we obtain the explicit equilibrium dividend strategy and the corresponding equilibrium value ***,numerical examples are shown to illustrate our results.

关键词： equilibrium dividend strategies non-exponential discounting time inconsistence dual model equilibrium HJB-equation

Synthesis and Reactivity of Trifluoromethylthiophosphonium Salts

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Chinese Journal of Chemistry 2023年第21期41卷 2779-2787页

作者： Wen-Qi Xu xiu-Hua Xu feng-Ling Qing Key Laboratory of Organofluorine Chemistry Shanghai Institute of Organic ChemistryUniversity of Chinese Academy of SciencesChinese Academyof Sciences345 LinglingLuShanghai 200032China

This article described an unprecedented synthesis of trifluoromethylthiophosphonium salts from allyl trifluoromethyl sulfoxide and phosphines in the presence of trimethylsilyl trifluoromethanesulfonate(TMSOTf)through Mislow-Evans-type *** resulting trifluoromethylthiophosphonium salts were firstly isolated and fully *** fluoroalkylphosphonium salts,as exemplified by trifluoromethylthio triphenylphosphonium salt(6a),exhibited unique and versatile reaction with nucleophiles and deoxygenative trifluoromethylthiolation reaction of carboxylic ***,the photoredox catalytic tunable radical hydrotrifluoromethylation and hydrotrifluoromethythiolation of unactivated alkenes with 6a was successfully.

关键词： Phosphonium salts Fluorine Rearrangement Trifluoromethylthiolation Synthetic methods

Practical Synthesis of NFSI Derivatives through ArSO_(2) NHF without F_(2)

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Chinese Journal of Chemistry 2022年第24期40卷 2956-2962页

作者： Yu-Yang Zhang xiu-Hua Xu feng-Ling Qing Key Laboratory of Organofluorine Chemistry Shanghai Institute of Organic ChemistryUniversity of Chinese Academy of ScienceChinese Academy of Sciences345 Lingling LuShanghai200032 China

N-Fluorobenzenesulfonimide (NFSI) is one of the most popular fluorine-containing reagents for fluorination, imidation, sulfonylation, and oxidation reactions. Consequently, a variety of NFSI derivatives were designed and synthesized to modify the reactivity and/or selectivity of the parent reagent. However, the hazardous F_(2) was inevitably required for the synthesis of NFSI derivatives. Herein, we disclosed a practical synthesis of various NFSI derivatives without F_(2) in common organic chemistry laboratories. This synthetic protocol started from NFSI through pyridine-promoted desulfonylation for formation of N-fluoroarenesulfonamide (ArSO_(2)NHF) and followed by condensation with arenesulfonyl chlorides. The reduction potentials and fluorinating reactivities of these NFSI derivatives demonstrated that NFSI derivatives bearing the electron-withdrawing groups on benzene ring had the higher oxidizing and fluorinating abilities than NFSI.

关键词： Fluorine Fluorinating reagent Sulfonamides Synthetic methods Desulfonylation NFSI Condensation

Estimating Survival Treatment Effects with Covariate Adjustment Using Propensity Score

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Acta Mathematica Sinica,English Series 2022年第11期38卷 2057-2068页

作者： Yong xiu CAO Xin cheng ZHANG Ji Chang YU School of Statistics and Mathematics Zhongnan University of Economics and LawWuhan 430073P.R.China

Propensity score is widely used to estimate treatment effects in observational *** covariate adjustment using propensity score is the most straightforward method in the literature of causal *** this article,we estimate the survival treatment effect with covariate adjustment using propensity score in the semiparametric accelerated failure time *** establish the asymptotic properties of the proposed estimator by simultaneous estimating *** conduct simulation studies to evaluate the finite sample performance of the proposed method.A real data set from the German Breast Cancer Study Group is analyzed to illustrate the proposed method.

关键词： Accelerated failure time model covariate adjustment observational study propensity score simultaneous estimating equations

Future Digital Design and Manufacturing: Embracing Industry 4.0 and Beyond

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Chinese Journal of Mechanical Engineering 2017年第5期30卷 1047-1049页

作者： Sheng-feng Qin Kai cheng School of Design Northumbria University College of Engineering Design and Physical SciencesBrunel University London

Digital design and manufacturing have been around for several decades from the numerical control of machine tools and automating engineering design in 1960s, through early Computer Aided Design （CAD）/Computer Aided Engineering analysis （CAE）/Computer Aided Manufacturing （CAM）, to modem digital design and manufacturing [1], and cloud manufacturing [2] converging into product lifecycle management （PLM） [3, 4] and Internet-enabled personalized manufacturing [5].

关键词： Digital design Future manufacturing Industry 4.0

A quantitative colorimetric assay of H_2O_2 and glucose using silver nanoparticles induced by H_2O_2 and UV

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Chinese Chemical Letters 2013年第12期24卷 1053-1058页

作者： Yu Zhang Yan-Jun Zhang Xiao-Dong Xia Xiao-Qi Hou cheng-Ting feng Jian-xiu Wang Liu Deng College of Chemistry and Chemical Engineering Central South University

A simple spectrophotometric assay of H2O2 and glucose using Ag nanoparticles has been carried out. Relying on the synergistic effect of H2O2 reduction and ultraviolet （UV） irradiation, Ag nanoparticles with enhanced absorption signals were synthesized. H2O2 served as a reducing agent in the Ag nanoparticles formation in which Ag＋ was reduced to Ago by O2- generated via the decomposition of H2O2 in alkaline media. On the other hand, photoreduction of Ag＋ to Ago under UV irradiations also contributed to the nanoparticles formation. The synthesized nanoparticles were characterized by TEM, XPS, and XRD. The proposed method could determine H2O2 with concentrations ranging from 5.0× 10^-7 to 6.0× 10^-5 tool/ L The detection limit was estimated to be 2.0 × 10^-7 mol/L. Since the conversion of glucose to gluconic acid catalyzed by glucose oxidase was companied with the formation of H2O2, the sensing protocol has been successfully utilized for the determination of glucose in human blood samples. The results were in good agreement with those determined by a local hospital. This colorimetric sensor thus holds great promises in clinical applications.

关键词： Silver nanoparticles Colorimetric assay H2O2 Glucose

Synthesis and Properties of CF3(OCF3)CH-Substituted Arenes and Alkenes

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Chinese Journal of Chemistry 2020年第8期38卷 847-854页

作者： Wen-Qi Xu xiu-Hua Xu feng-Ling Qing Key Laboratory of Organofluorine Chemistry Center for Excellence in Molecular SynthesisShanghai Institute of Organic ChemistryUniversity of Chinese Academy of ScienceChinese Academy of Science345 Lingling LuShanghai 200032China Key Laboratory of Science and Technology of Eco-Textiles Ministry of EducationCollege of ChemistryChemical Engineering and BiotechnologyDonghua University2999 North Renmin LuShanghai 201620China

A silver-mediated oxidative trifluoromethylation of easily accessibleαα-trifluoromethyl alcohols with TMSCF3 was developed to access novel CF3(OCF3)CH-containing *** of CF3(OCF3)CH-substituted arenes afforded synthetically useful CF3O-substituted ***,evaluation of the lipophilicities(log P)indicated that CH(OCF3)CF3 is more lipophilic than the common fluorinated motifs such as CF3,OCF3,and SCF3,thus rendering the CH(OCF3)CF3 motif appealing in drug discovery.

关键词： compounds substituted rendering