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Science China Chemistry 2025年第1期 257-263页

作者： Jiapian Huang Chenxin wang xu wang Xiaoyu Zhou Wei Xiao Jie Wu School of Pharmaceutical and Chemical Engineering & Institute for Advanced Studies Taizhou University State Key Laboratory of Organometallic Chemistry Shanghai Institute of Organic Chemistry Chinese Academy of Sciences School of Chemistry and Chemical Engineering Henan Normal University

The generation of various β-chiral sulfones bearing chiral cyclic sulfinamides through photoredox-catalyzed sulfur dioxide insertion with asymmetric radical cyclization is described. This method features a broad substrate scope and excellent stereospecificity. Computational studies reveal that the dispersion interaction between sulfinyl group and CH2SO2Ph group plays a crucial role in the stereoselectivity control.

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Effect of mixing section configurations on combustion efficiency of Mg-CO_(2)Martian ramjet

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Chinese Journal of Aeronautics 2023年第4期36卷 165-173页

作者： xu wang Yanpeng BU xu xu Qingchun YANG School of Astronautics Beihang UniversityBeijing 100191China Shenyuan Honors College Beihang UniversityBeijing 100191China

Experiments were conducted to determine the effects of the mixing section configurations on the Mg-CO_(2)Martian ramjet combustion *** was carried out at a mainstream mass flow rate of 110 g/s and a temperature of 810 *** chamber pressure was measured under different configurations and Oxidizer to Fuel(O/F)*** showed that the engine achieved self-sustaining combustion and worked stably during *** pre-combustion chamber is needed to increase the combustion efficiency and promote the full combustion of the *** the configuration of the pre-combustion chamber,the best combustion efficiency reached 80%when radial powder injection and lateral carbon dioxide intake were *** addition,the O/F ratio in the pre-combustion chamber decreased from 0.67 to 0.31,resulting in an 8%increase in the combustion *** was speculated that different mixing section configurations and the variations in an O/F ratio within the pre-combustion chamber impacted the combustion efficiency and in essence,all affected the flow velocity and residence time of the two-phase flow in the com-bustion chamber.

关键词： Combustion efficiency Magnesium-base fuel Martian ramjet Mars exploration Structural configurations

Effect of Free-Stream Mach Number on the Base Thermal Environment of LaunchVehicle

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Journal of Thermal Science 2024年第6期33卷 2426-2436页

作者： wang xu xu xu YU Jiaqi YANG Qingchun School of Astronautics Beihang UniversityBeijing 100191China Shenyuan Honors College Beihang UniversityBeijing 100191China

Convective heating of the rocket base caused by high-temperature reverse flow has long been a focus of thermal protection *** distinctive structural characteristics,the base thermal environment of a twin-nozzle engine proves more susceptible to the recirculation region than its multi-nozzle *** the transonic stage,significant alterations in the flow field structure at the rocket base strongly influence the recirculation *** study investigated the thermal environment of the rocket base with a twin-nozzle configuration in freestream at Mach numbers of 0.6 to *** indicate that the freestream Mach number significantly affects the thermal environment at the rocket base during the transonic *** increase of Mach number from 0.6 to 1.0 causes the convective heating of the rocket base to increase by 7.7 *** phenomenon arises due to the plume-induced shock wave caused by the impact of the supersonic free shear layer and plume shear layer while the flight speed exceeds the sound *** interaction between the shock wave and the shear layer amplifies turbulence in the recirculation region and at the inflection point,resulting in a stronger high-temperature reverse *** addition,the cause of low-altitude base heating was analyzed,and it was found that the mechanism is different from the high-temperature countercurrent effect caused by plume interaction.

关键词： rocket base heating free stream Mach number shock-turbulence interaction twin-nozzle

Empirical Likelihood for a First-Order Generalized Random Coefficient Integer-Valued Autoregressive Process

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Journal of Systems Science & Complexity 2023年第2期36卷 843-865页

作者： CHENG Jianhua wang xu wang Dehui School of Mathematics Jilin UniversityChangchun 130012China School of Mathematics and Statistics Liaoning UniversityShenyang 110036China

In this paper,the authors consider the empirical likelihood method for a first-order generalized random coefficient integer-valued autoregressive *** authors establish the log empirical likelihood ratio statistic and obtain its limiting ***,the authors investigate the point estimation,confidence regions and hypothesis testing for the parameters of *** performance of empirical likelihood method is illustrated by a simulation study and a real data example.

关键词： Empirical likelihood generalized random coefficient integer-valued time series thinning operator

Singular Supercritical Trudinger-Moser Inequalities and the Existence of Extremals

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Acta Mathematica Sinica,English Series 2020年第8期36卷 873-888页

作者： xu Min wang School of Mathematical Sciences Beijing Normal UniversityBeijing 100875P.R.China

In this paper,we present the singular supercritical Trudinger-Moser inequalities on the unit ball B in Rn,where n≥*** precisely,we show that for any given α>0 and 0 详细信息

In this paper,we present the singular supercritical Trudinger-Moser inequalities on the unit ball B in Rn,where n≥*** precisely,we show that for any given α>0 and 0

关键词： Singular supercritical Trudinger-Moser inequality radial lemma concentration-compactness principle extremal functions

Lighting up rotaxanes with AIEgens

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Chinese Chemical Letters 2023年第3期34卷 122-133页

作者： Xiao-Qin xu xu-Qing wang Wei wang School of Chemistry and Molecular Engineering East China Normal UniversityShanghai 200062China Guangdong Provincial Key Laboratory of Functional and Intelligent Hybrid Materials and Devices South China University of TechnologyGuangzhou 510640China

Aiming at the construction of novel rotaxanes with desired luminescent properties for practical applications, recently the rapid development of rotaxanes decorated with aggregation-induced emission(AIE) luminogens(i.e., AIEgens) has been witnessed. The combination of AIEgens and rotaxanes leads to the successful construction of a novel type of luminescent rotaxanes with many attractive features. In particular, the unique controllable dynamic feature of rotaxanes endows the resultant AIEgen-based rotaxanes precisely tunable emissions under external stimuli, leading to the construction of a novel type of smart luminescent materials. In this minireview, the recent progress of AIEgen-based rotaxanes has been summarized, with an emphasis on the design strategy and potential applications.

关键词： Mechanically interlocked molecules Aggregation-induced emission Molecular shuttles F?rster resonance energy transfer Light harvesting Aggregate

Consistency check of degradation mechanism between natural storage and enhancement test for missile servo system

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Journal of Systems Engineering and Electronics 2019年第2期30卷 415-424页

作者： wang xu Sun Quan College of Information Systems and Management National University of Defense Technology The Second Academy of China Aerospace Science and Industry Corporation Hunan Ginkgo Reliability Technology Institute Limited Corporation

Reliability enhancement testing(RET) is an accelerated testing which hastens the performance degradation process to surface its inherent defects of design and manufacture. It is an important hypothesis that the degradation mechanism of the RET is the same as the one of the normal stress condition. In order to check the consistency of two mechanisms, we conduct two enhancement tests with a missile servo system as an object of the study, and preprocess two sets of test data to establish the accelerated degradation models regarding the temperature change rate that is assumed to be the main applied stress of the servo system during the natural storage. Based on the accelerated degradation models and natural storage profile of the servo system, we provide and demonstrate a procedure to check the consistency of two mechanisms by checking the correlation and difference of two sets of degradation data. The results indicate that the two degradation mechanisms are significantly consistent with each other.

关键词： reliability enhancement testing (RET) degradation model accelerated equation consistency check Pearson correlation coefficient

DECAGONAL QU ASICRYSTALLINE ELLIPTICAL INCLUSIONS UNDER THERMOMECHANICAL LOADING

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Acta Mechanica Solida Sinica 2014年第5期27卷 518-530页

作者： xu wang Peter Schiavone School of Mechanical and Power Engineering East China University of Science and Technology Department of Mechanical Engineering University of Alberta 4-9 Mechanical Engineering Building Edmonton

In this work, an elegant method is proposed to derive the thermoelastic field in- duced by thermomechanical loadings in a decagonal quasicrystalline composite composed of an infinite matrix reinforced by an elliptical inclusion. The thermomechanical loadings include a uniform temperature change, remote uniform in-plane heat fluxes and remote uniform in-plane stresses. The corresponding boundary value problem is ultimately reduced to the solution of two independent sets of four coupled linear algebraic equations, each of which involves four complex constants characterizing the internal stress field. The solution demonstrates that a uniform tem- perature change and remote uniform stresses will induce an internal uniform stress field, and that uniform heat fluxes will result in a linearly distributed internal stress field within the elliptical inclusion. The induced uniform rigid body rotation within the inclusion is given explicitly.

关键词： elliptical inclusion thermomechanical loadings decagonal quasicrystal complexvariable method

The mechanism of stiffness increase phenomenon of a rubbing disk

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Acta Mechanica Sinica 2010年第3期26卷 441-448页

作者： Shimin wang Jieqiong xu Qi wang Division of General Mechanics Beihang University 100191 Beijing China

The phase characteristic of a disk rubbing with a ring supported elastically is investigated and used to explain the mechanism of stiffness increase phenomenon. As long as the rubbing is maintained, the averaged phase difference between the disk and the rotating mass on the disk is defi- nitely less than π/2. When the rubbing finishes, the phase difference quickly approaches to 7r. This behavior is inde- pendent of the physics parameters of the rubbing system. The theoretical results are qualitatively verified with experiments.

关键词： Stiffness increase phenomenon Phasecharacteristic Rubbing rotor

TIME-HARMONIC DYNAMIC GREEN'S FUNCTIONS FOR ONE-DIMENSIONAL HEXAGONAL QUASICRYSTALS

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Acta Mechanica Solida Sinica 2005年第4期18卷 302-306页

作者： wang xu Shanghai Institute of Applied Mathematics and Mechanics Shanghai University Shanghai 200072 China

Quasicrystals have additional phason degrees of freedom not found in conventional crystals. In this paper, we present an exact solution for time-harmonic dynamic Green＇s function of one-dimensional hexagonal quasicrystals with the Laue classes 6/mh and 6/mhmm. Through the introduction of two new functions φ and ψ, the original problem is reduced to the determination of Green＇s functions for two independent Helmholtz equations. The explicit expressions of displacement and stress fields are presented and their asymptotic behaviors are discussed. The static Green＇s function can be obtained by letting the circular frequency approach zero.

关键词： dynamic Green's function one-dimensional hexagonal quasicrystal Helmholtz equation