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Design and integrated simulation of a pressurized feed system of the dual-thrust hybrid rocket motor

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Science China(Technological Sciences) 2013年第4期56卷 989-1000页

作者： li JunHai YU NanJia ZENG peng cai GuoBiao School of Astronautics Beihang University

A new pressurized feed system of the dual-thrust hybrid rocket motor for flight is presented in this *** feed system supplies 90% hydrogen peroxide (90%H 2 O 2) with two different flows of 4.5 and 2 kg s *** oxidizer flow is changed through regulating the mass flow of the high-pressure gas and switching the performance modes of the unique oxidizer flow control valve *** models of the gas storage container,pressure regulator valve,control orifice,propellant tank,oxidizer flow control valve and cavitating venturi are generated and used to compute the instantaneous pressure,temperature and mass flow *** is a good agreement between the simulated and experimental *** sensitivity analysis is also *** is found that the throat diameter of the cavitating venturi in feed line 1 is the main factor affecting the mass flow in both boost and sustaining *** parameters have limited effects on the mass flow rate and the transition time of the system.

关键词： pressurized feed system mathematical modeling liquid propellant tank variable flow dual-thrust hybrid motor

Rationally designed Ta_(3)N_(5)/BiOCl S-scheme heterojunction with oxygen vacancies for elimination of tetracycline antibiotic and Cr(Ⅵ):Performance,toxicity evaluation and mechanism insight

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Journal of Materials Science & Technology 2022年第28期123卷 177-190页

作者： Shijie li Mingjie cai Chunchun Wang Yanping liu Neng li peng Zhang Xin li Key Laboratory of Health Risk Factors for Seafood of Zhejiang Province National Engineering Research Center for Marine AquacultureCollege of Marine Science and TechnologyZhejiang Ocean UniversityZhoushan 316022China Institute of Innovation&Application Zhejiang Ocean UniversityZhoushan 316022China State Key Laboratory of Silicate Materials for Architectures Wuhan University of TechnologyWuhan 430070China State Center for International Cooperation on Designer Low-Carbon&Environmental Materials(CDLCEM) School of Materials Science and EngineeringZhengzhou UniversityZhengzhou 450001China Institute of Biomass Engineering Key Laboratory of Energy Plants Resource and UtilizationMinistry of Agriculture and Rural AffairsSouth China Agricultural UniversityGuangzhou 510642China

S-scheme heterojunction photocatalysts have been the“stars”in the field of ***,a novel S-scheme heterojunction of Ta_(3)N_(5)/BiOCl with oxygen vacancies(OVs)was fabricated via a facile *** charge separation and transport mechanism of this Ta_(3)N_(5)/BiOCl S-scheme heterojunction was verified by the analyses of band energy structures,active species,photoelectric behaviors and DFT theoretical *** with Ta_(3)N_(5)and BiOCl,the Ta_(3)N_(5)/BiOCl unveils substantially upgraded photocatalytic property under visible light,and the photocatalytic efficiency for removal of tetracycline(TC)and hexavalent chromium(Cr(VI))reaches 89.6%and 91.6%,*** substantial enhancement of the photocatalytic activity is attributed to the synergistic effect of the S-scheme hetero-structure and oxygen vacancies,which improves the visible-light absorption,while promoting the spatial separation of charge carriers with the optimum redox capacity,thereby boosting the production of active species for catalytic *** TC degradation pathway is deduced and the toxicity evolution of TC is appraised using the QSAR *** a nutshell,this work gives a deep understanding of the photocatalytic mechanism based on Ta_(3)N_(5)/BiOCl as well as presents a newfangled thought for developing highly efficient S-scheme heterojunction photocatalysts for water decontamination.

关键词： Ta_(3)N_(5)/BiOCl S-scheme heterojunction Oxygen vacancy Visible-light photocatalysis Antibiotic degradation Cr(Ⅵ)reduction

Feasibility Study on Continuous Mining Method in Deep Position of Jinchuan Nickel Mine, China

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Journal of University of Science and Technology Beijing 2001年第2期8卷 81-85页

作者： meifeng cai, Lan Qiao, Changhong li, Shuanghong Wang (Civil and Environmental Engineering School, University of Science and Technology Beijing, Beijing 100083, China) Civil and Environ. Eng. School University of Science and Technology Beijing 100083 China

Jinchuan nickel mine is the largest nickel mine in China. Cut-and-fill mining method with high density cementing materials is used in the mine. The original mining design divided the mining operation into two steps. The first step stopped the mining rooms and the second step stopped the pillars. Because the two-step method made big trouble for finally mining pillars and strongly limited the mining speed and production, it was successfully changed to a continuous cut-and-fill method without pillars. However, the mining operation in the mine has been down to 800 m and the mining condition is getting worse and more complicated. Through systematical field investigations and 3-D FEM analysis, it is proved that the mining method without pillars is feasible for mining deeper orebodies in Jinchuan nickel mine.

关键词： Jinchuan nickel mine deep position continuous mining feasibility study

Online adaptive Q-learning method for fully cooperative linear quadratic dynamic games

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Science China(Information Sciences) 2019年第12期62卷 164-177页

作者： Xinxing li Zhihong peng Lei JIAO Lele XI Junqi cai School of Automation Beijing Institute of Technology State Key Laboratory of Intelligent Control and Decision of Complex Systems

A model-based offline policy iteration(PI) algorithm and a model-free online Q-learning algorithm are proposed for solving fully cooperative linear quadratic dynamic games. The PI-based adaptive Q-learning method can learn the feedback Nash equilibrium online using the state samples generated by behavior policies, without sending inquiries to the system model. Unlike the existing Q-learning methods, this novel Q-learning algorithm executes both policy evaluation and policy improvement in an adaptive *** prove the convergence of the offline PI algorithm by proving its equivalence to Newton’s method while solving the game algebraic Riccati equation(GARE). Furthermore, we prove that the proposed Q-learning method will converge to the Nash equilibrium under a small learning rate if the method satisfies certain persistence of excitation conditions, which can be easily met by suitable behavior policies. Our simulation results demonstrate the good performance of the proposed online adaptive Q-learning algorithm.

关键词： adaptive dynamic programming reinforcement learning Q-learning fully cooperative linear quadratic dynamic games policy iteration off-policy

Synthesis of chiral phosphine derivatives through a copper（I）-catalyzed desymmetric SNAr reaction

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Science China Chemistry 2025年

作者： Shuai Zhang Pei-Zhi liu Yan-Bo li Qi Zhang Jun-Zhao Xiao Yi-Fan Wang Tian-Yu Wei Jia-Wei Jiang Ye Wang Qian peng liang Yin Key Laboratory of Fluorine and Nitrogen Chemistry and Advanced Materials Shanghai Institute of Organic Chemistry University of Chinese Academy of Sciences Chinese Academy of Sciences State Key Laboratory of Elemento-Organic Chemistry and Tianjin Key Laboratory of Biosensing and Molecular Recognition College of Chemistry Frontiers Science Center for New Organic Matter Nankai University Haihe Laboratory of Sustainable Chemical Transformations

Axially chiral phosphines are a class of extremely important ligands in asymmetric catalysis. Herein, an unprecedented copper（I）-catalyzed asymmetric SNAr reaction with HP（S）R2is uncovered, which delivers a series of axially chiral phosphine derivatives in high yields with excellent enantioselectivity. Furthermore, the diastereoselective reaction with the kinetic resolution of racemic HP（S）ArR proceeds smoothly, providing the products with moderate diastereoselectivity and excellent enantioselectivity. Control experiments indicate that HP（S）Ph2is much more active than HPPh2and HP（O）Ph2as the pronucleophile in the present reaction. It is found that the SNAr reaction （the first SNAr） proceeds in a desymmetric manner, providing the desired chiral products while a continued SNAr reaction （the second SNAr） slightly occurs in a kinetic resolution manner in the present catalytic system, which enhances the ee of the desired chiral products. DFTcalculations support a concerted reaction pathway rather than a step-wise mechanism. Finally, axially chiral olefin-phosphines produced by the present method work as suitable ligands in Pdcatalyzed asymmetric allylic substitution with C-, N-, and O-nucleophiles and Rh-catalyzed asymmetric addition of arylboronic acid to benzil.

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A dual-site Fe-based catalyst for efficient ammonia synthesis under mild conditions

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Science China Chemistry 2025年

作者： Shiyong Zhang Mingyuan Zhang Tianhua Zhang Jizhen Sun Jiaxin li Kailin Su Ruishao Mao Yanliang Zhou Xuanbei peng Yangyu Zhang Jun Ni Bingyu lin Xiuyun Wang lilong Jiang National Engineering Research Center of Chemical Fertilizer Catalyst Fuzhou University Qingyuan Innovation Laboratory

Achieving green ammonia （NH3） synthesis requires developing effective catalysts under mild ***,the competitive adsorption of N2and H2,as well as the strong binding of N-containing intermediates on the catalyst,greatly inhibits the active sites for efficient ***,we constructed a series of ZrH2-modified Fe catalysts with dual active sites to address these issues and realized efficient NH3synthesis under mild *** study shows that ZrH2can not only provide active sites for H2activation but also transfer electrons to Fe sites for accelerating *** interaction between Fe and ZrH2over 40ZrH2-Fe leads to a decrease in work function and a downward shift of the d-band center,which is conducive to N2activation and NH3desorption,*** utilization of distinct sites for activating different reactants can avoid the competitive adsorption of N2and H2,leading to excellent NH3synthesis activity of the 40 wt.%ZrH2-mediated Fe *** a result,40ZrH2-Fe exhibits a high NH3synthesis rate of 23.3 mmol g-1cath-1at 400°C and 1 MPa and robust stability during100 h time-on-stream.

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DRAG REDUCTION OF A CATIONIC SURFACTANT SOLUTION AND ITS SHEAR STRESS RELAXATION

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Journal of Hydrodynamics 2012年第2期24卷 202-206页

作者： cai Shu-peng Institute of High Pressure Water Jet Hunan University of Technology Zhuzhou 412007 China

In order to study the mechanisms of the turbulent frictional drag reduction by surfactant additives,the drag reduction,the shear viscosity and the shear stress relaxation were measured for solutions of a cationic surfactant cetyltrimethyl ammonium bromide （CTAB） with the same molar sodium salicylate as a *** is found that the first step relaxation time decreases with increasing concentration and,thus,with the maximum drag-reducing rates,which indicates that the stiffness of the micellar structures with the first relaxation time,increases with the increase of the concentration of ***,for this surfactant,a viscoelastic property is necessary for reducing drag,while a stronger viscoelasticity characterized by a tail relaxation time does not necessarily mean a higher drag-reducing rate.

关键词： drag reduction shear stress relaxation relaxation time viscoelasticity

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论宣王中兴与王官诗学的裂变

保山学院学报 2025年第1期44卷 82-87页

作者：李鹏安徽师范大学文学院安徽芜湖241002 亳州学院中文与传媒系安徽亳州236800

《大小雅》中存有大量周宣王朝诗,这与宣王中兴有关。“雅中之颂”“‘变雅’作矣”两组感情色彩迥异的诗同时存在于诗文本中,是宣王时期政治社会生态的折射。宣王朝诗文本的编辑活动,以服务礼乐仪式为目的,但客观上导致了诗歌讽谏功能... 详细信息

《大小雅》中存有大量周宣王朝诗,这与宣王中兴有关。“雅中之颂”“‘变雅’作矣”两组感情色彩迥异的诗同时存在于诗文本中,是宣王时期政治社会生态的折射。宣王朝诗文本的编辑活动,以服务礼乐仪式为目的,但客观上导致了诗歌讽谏功能的长足发展,进而引发了王官诗学的裂变。从此,诗教由乐教附庸而趋向独立,并朝着注重德教的伦理化方向发展。

关键词：宣王中兴雅中之颂 “变雅”作矣王官诗学

Supramolecular synthesis of coumarin derivatives catalyzed by a coordination-assembled cage in aqueous solution

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Science China Chemistry 2019年第6期62卷 713-718页

作者： Shao-Chuan li li-Xuan cai li-peng Zhou Fang Guo Qing-Fu Sun State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of Matter Chinese Academy of Sciences College of Chemistry Liaoning University

A self-assembled Pd_4L_2 cage is employed as a water-soluble molecular flask for the synthesis of functionalized coumarins from a series of salicylaldehyde derivatives and cyanoacetates/malononitrile. The catalytic reaction features mild aqueous conditions and broad substrate scope. Crystal structures of the host-guest complexes for two substrates and one analogous intermediate have been obtained, shedding light on the supramolecular reaction mechanism. Michaelis-Menten kinetic studies were performed in one typical case, revealing that the rate of product formation has been enhanced by over 23-fold in contrast to the background reaction without cage. Moreover, the same reaction catalyzed by a smaller Pd_6L_4 cage gives a mixture of products and much lower yields, suggesting that fine-tuning on the size and symmetry of the cages' cavity is crucial for their applications in supramolecular catalysis.

关键词： coordination-assembly cage encapsulation Knoevenagel condensation