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The Formation of Nano-Size SiO_2 Thin Film on an Aluminum Plate with hexamethyldisilazane (hMDSA) and hexamethyldisiloxane (hMDSO)

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Journal of Thermal Science 2003年第1期12卷 89-96页

作者： h.K.ma E.Zhao K.M.Chung C.L.Yeh Dept of Mechanical Engineering National Taiwan UniversityDept of Mechanical Engineering National Taiwan UniversityDept of Mechanical Engineering National Taiwan UniversityDept of Mechanical Engineering Da-Yeh University 112 Taipei Taiwan 10764 China Taipei Taiwan 10764 ChinaTaipei Taiwan 10764 ChinaShan-Jeau Rd Dah-Tsuen Chang-Hwa Taiwan 51505 China

This study is using hMDSA (C6h19NSi2) or hMDSO (C6h18OSi2) vapor into C3h8/air premixed flames to form SiO2 thin film on the surface of an aluminum plate. With the addition of hMDSO or hMDSA to premixed flames, an orange secondary flame or a flame brush appeared and was contributed to the formation of Sio2 particles. Based upon the EDS, XPS and FTIR analysis, it is believed that the synthesized products consist of mainly SiO2 and a small amount of SiO. The pure SiO2 crystal structure, was proved by XRD analysis, which may form from the SiO2 amorphous structure after high temperature (1300C) thermal treatment. The nano-size SiO2 particles, which ranged from 2.5-25 nm, are proved by analysis of the BET and TEM. A 2-D CFD-RC code with 12 reduced chemical reaction mechanism, based upon the SIMPLER procedure, was successfully employed to predict the flame temperature and both of the SiO2 and SiO concentration profiles. Compared with the experimental results, the calculated temperature profiles in the post-flame region are in good agreement with the measured data and observation phenomena.

关键词： nano size thin film SiO2.

Optimizing the crystallinity and acidity of h-SAPO-34 by fluoride for synthesizing Cu/SAPO-34 Nh_3-SCR catalyst

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Journal of Environmental Sciences 2016年第3期28卷 244-251页

作者： Jing ma Zhichun Si Xiaodong Wu Duan Weng Yue ma The Key Laboratory of Advanced materials of Ministry of Education School of Materials Science and EngineeringTsinghua University Advanced materials Institute Graduate School at ShenzhenTsinghua University

A series of h-SAPO-34 zeolites were synthesized by a hydrothermal method in fluoride *** as-synthesized h-SAPO-34 zeolites were characterized by X-ray diffraction（XRD）,scanning electron microscopy（SEM）,N_2 physisorption,temperature-programmed desorption of Nh_3（Nh_3-TPD） and nuclear magnetic resonance（NMR） *** results showed that a certain concentration of F- anions promoted the nucleation and crystallization of *** h-SAPO-34 synthesized in the fluoride media showed high crystallinity,uniform particle size distribution,large specific surface area and pore volume,and enhanced ***,Cu/SAPO-34 based on the fluoride-assisted zeolite showed a broadened temperature window for the selective catalytic reduction of NO by Nh_3（Nh_3-SCR） reaction due to the enhanced acidity of the zeolite and the improved dispersion of copper species.

关键词： h-SAPO-34 Fluoride media Crystallinity Acidity Selective catalytic reduction(SCR)of NO

Relevant Region sampling strategy with.a.a.tive heuristic for asymptotically optimal path planning

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Biomimetic Intelligence & Robotics 2023年第3期3卷 21-29页

作者： Chenming Li Fei Meng han ma Jiankun Wang max Q-h.Meng Department of Electronic Engineering The Chinese University of Hong KongHong Kong 999077China Department of Electronic and Electrical Engineering Southern University of Science and TechnologyShenzhen 518055China Shenzhen Research Institute of the Chinese University of hong Kong Shenzhen 518057China

Sampling-based planning algorithm is a powerful tool for solving planning problems in highdimensional state *** this article,we present a novel approach to sampling in the most promising regions,which significantly reduces planning *** RRT#algorithm defines the Relevant Region based on the cost-to-come provided by the optimal forward-searching ***,it uses the cumulative cost of a direct connection between the current state and the goal state as the *** improve the path planning efficiency,we propose a batch sampling method that samples in a refined Relevant Region with a direct sampling strategy,which is defined according to the optimal cost-to-come and the adaptive cost-to-go,taking advantage of various sources of heuristic *** proposed sampling approach allows the algorithm to build the search tree in the direction of the most promising area,resulting in a superior initial solution quality and reducing the overall computation time compared to related *** validate the effectiveness of our method,we conducted several simulations in both SE(2)and SE(3)state *** the simulation results demonstrate the superiorities of proposed algorithm.

关键词： Path planning Asymptotical optimality Relevant Region Adaptive heuristic

Rh2O3/hexagonal CePO4 nanocatalysts for N2O decomposition

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Frontiers of Chemical Science and Engineering 2017年第4期11卷 586-593页

作者： huan Liu Zhen ma Shanghai Key Laboratory of Atmospheric Particle Pollution & Prevention (LAP3) Department of Environmental Science & Engineering Fudan University Shanghai 200433 China

hexagonal CePO4 nanorods were prepared by a precipitation method and hexagonal CePO4 nanowires were prepared by hydrothermal synthesis at 150 ℃. Rh （NO3）3 was then used as a precursor for the impregnation of Rh203 onto these CePO4 materials. The Rh203 supported on the CePO4 nanowires was much more active for the catalytic decomposition of N20 than the RhzO3 supported on CePO4 nanorods. The stability of both catalysts as a function of time on stream was studied and the influence of the co-feed （CO2, O2, h20 or O2/h20） on the N20 decomposition was also investigated. The samples were characterized by N2 adsorption-desorption, induc- tively coupled plasma optical emission spectroscopy, X- ray diffraction, transmission electron microscopy, X-ray photoelectron microscopy, hydrogen temperature-pro- grammed reduction, oxygen temperature-programmed desorption, and CO2 temperature-programmed desorption in order to correlate the physicochemical and catalytic properties.

关键词： Rh2O3 CePO4 N2O decomposition

Unconfined compressive strength and failure behaviour of completely weathered granite from a fault zone

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Journal of Mountain Science 2024年第6期21卷 2140-2158页

作者： DU Shaohua ma Jinyin ma Liyao ZhAO Yaqian School of Civil Engineering and Architecture Henan University of Science and TechnologyLuoyang 471023China School of Resources and Safety Engineering Central South UniversityChangsha 410083China China Railway 18th Bureau Group Co. LtdTianjin 300222 China China General Nuclear Power Corporation Shenzhen 518031China

Understanding the strength characteristics and deformation behaviour of the tunnel surrounding rock in a fault zone is significant for tunnel stability *** this study,a series of unconfined compression tests were conducted to investigate the mechanical characteristics and failure behaviour of completely weathered granite(CWG)from a fault zone,considering with height-diameter(h/d)ratio,dry densities(ρd)and moisture contents(ω).Based on the experimental results,a regression mathematical model of unconfined compressive strength(UCS)for CWG was developed using the Multiple Nonlinear Regression method(MNLR).The research results indicated that the UCS of the specimen with a h/d ratio of 0.6 decreased with the increase ofω.When the h/d ratio increased to 1.0,the UCS increasedωwith up to 10.5%and then ***ρd is conducive to the improvement of the UCS at anyω.The deformation and rupture process as well as final failure modes of the specimen are controlled by h/d ratio,ρd andω,and the h/d ratio is the dominant factor affecting the final failure mode,followed byωandρ*** specimens with different h/d ratio exhibited completely different fracture mode,i.e.,typical splitting failure(h/d=0.6)and shear failure(h/d=1.0).By comparing the experimental results,this regression model for predicting UCS is accurate and reliable,and the h/d ratio is the dominant factor affecting the UCS of CWG,followed byρd and thenω.These findings provide important references for maintenance of the tunnel crossing other fault fractured zones,especially at low confining pressure or unconfined condition.

关键词： Fault fracture zone Completely weathered granite(CWG) Unconfined compression strength(UCS) Multiple nonlinear regression model

Robust h_∞ control for networked control systems

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Journal of Systems Engineering and Electronics 2008年第5期19卷 1003-1009页

作者： ma Weiguo Shao Cheng Inst. of Advanced Control Technology School of Electronic and Information Engineering Dalian Univ. of Technology Dalian 116024 P. R. China

The robust h∞ control for networked control systems with both stochastic network-induced delay and data packet dropout is studied. When data are transmitted over network, the stochastic data packet dropout process can be described by a two-state markov chain. The networked control systems with stochastic network-induced delay and data packet dropout are modeled as a discrete time markov jump linear system with two operation modes. The sufficient condition of robust h∞ control for networked control systems stabilized by state feedback controller is presented in terms of linear matrix inequality. The state feedback controller can be constructed via the solution of a set of linear matrix inequalities. An example is given to verify the effectiveness of the method proposed.

关键词： networked control systems h∞ control markov jump linear systems linear matrix inequality.

Rh_2O_3/monoclinic CePO_4 composite catalysts for N_2O decomposition and CO oxidation

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Chinese Journal of Chemical Engineering 2018年第1期26卷 109-115页

作者： huan Liu Zhen ma Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention Department of Environmental Science and EngineeringFudan University

CePO4 （in particular, monoclinic CePO4） has been rarely used to make supported catalysts. herein, monoclinic CeP04 nanoparticles were prepared by calcining hexagonal CePO4 nanomds （prepared by precipitation） in air at 900 ℃. Monoclinic CePO4 nanowires were prepared by calcining hexagonal CePO4 nanowires （prepared by hydrothermal synthesis at 150 ℃） in air at 900 ℃. Both monoclinic CePO4 materials were used to support Rh2O3 by impregnation using Rh（NO3）3 as a precursor （followed by calcination）. The catalytic performance of Rh2O3/monoclinic CePO4 composite materials in N2O decomposition and CO oxidation was investigated. It was found that Rh2O3 supported on monoclinic CePO4 nanowims was much more active than Rh2O3 supported on monoclinic CePO4 nanoparticles. The stability of catalysts as a function of reaction time on stream was studied in both reactions. The influence of co-fed CO2, O2, and h2O on the catalytic activity in N20 decomposition was also studied. These catalysts were characterized by employing N2 adsorption-desorption, ICP-OES, XRD, TEM, XPS, h2-TPR, O2-TPD, and CO2-TPD. The correlation between physicochemical properties and catalytic properties was discussed.

关键词： Rh2O3 CePO4 N2O decomposition CO oxidation Catalyst

Electron capture in collisions of Li3+ ions with ground and excited states of Li atoms

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Chinese Physics B 2020年第1期29卷 246-253页

作者： M X ma B h Kou L Liu Y Wu J G Wang Institute of Modern Physics Fudan UniversityShanghai 200433China Key Laboratory of Nuclear Physics and Ion-beam ApplicationMOE Fudan UniversityShanghai 200433China Institute of Applied Physics and Computational mathematics Beijing 100088China Kents hill School 12 th GradeMaine 04349USA

The electron capture processes in collisions of Li3+ion with Li(1s22s)and Li(1s22p0,1)are investigated by using the two-center atomic orbital close-coupling method in the energy range from 0.1 keV/u to 300 keV/*** interaction of the active electrons with the target ion is represented by a model *** present results for the Li3+–Li(1s22s)system are compared with the available theoretical data and general agreement is obtained for the high collision *** is also found that the total and partial electron capture cross sections are sensitive to the initial charge cloud alignment in the low energy region.

关键词： two-center atomic orbital closed coupling electron capture cross section

Investigation on dynamic characteristics of a rod fastening rotor-bearing coupling system with fixed-point rubbing

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Applied mathematics and Mechanics(English Edition) 2022年第7期43卷 1063-1080页

作者： Yang YANG hJOUYANG Jin ZENG hui ma Yiren YANG Dengqing CAO School of Mechanics and Engineering Southwest Jiaotong UniversityChengdu 610031China Centre for Engineering Dynamics School of EngineeringUniversity of LiverpoolLiverpool L693GHU.K. School of Mechanical Engineering and Automation Northeastern UniversityShenyang 110819China School of Astronautics Harbin Institute of TechnologyHarbin 150001China

The aim of this paper is to gain insight into the nonlinear vibration feature of a dynamic model of a gas ***,a rod fastening rotor-bearing coupling model with fixed-point rubbing is proposed,where the fractal theory and the finite element method are *** contact analysis,a novel contact force model is introduced in this ***,the Coulomb model is adopted to expound the friction ***,the governing equations of motion of the rotor system are numerically solved,and the nonlinear dynamic characteristics are analyzed in terms of the bifurcation diagram,Poincarémap,and time ***,the potential effects provided by contact degree of joint interface,distribution position,and amount of contact layer are discussed in ***,the contrast analysis between the integral rotor and the rod fastening rotor is conducted under the condition of fixed-point rubbing.

关键词： rod fastening rotor joint interface fixed-point rubbing nonlinear dynamic characteristic