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Numerical simulation of a direct internal reforming solid oxide fuel cell using computational fluid dynamics method

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2008年第7期9卷 961-969页

作者： Jun LI Ying-wei KANG Guang-yi CAO xin-jian ZHU Heng-yong TU jian LI Institute of Fuel Cell Department of Automalion Shanghai Jiao Tong University Shanghai 200240 China College of Materials Science and Engineering Huazhong University of Science and Technology Wuhan 430074 China

A detailed mathematical model of a direct internal reforming solid oxide fuel cell(DIR-SOFC) incorporating with simulation of chemical and physical processes in the fuel cell is presented. The model is developed based on the reforming and electrochemical reaction mechanisms,mass and energy conservation,and heat transfer. A computational fluid dynamics(CFD) method is used for solving the complicated multiple partial differential equations(PDEs) to obtain the numerical approximations. The resulting distributions of chemical species concentrations,temperature and current density in a cross-flow DIR-SOFC are given and analyzed in detail. Further,the influence between distributions of chemical species concentrations,temperature and current density during the simulation is illustrated and discussed. The heat and mass transfer,and the kinetics of reforming and electrochemical reactions have significant effects on the parameter distributions within the cell. The results show the particular characteristics of the DIR-SOFC among fuel cells,and can aid in stack design and control.

关键词： Direct internal reforming (DIR) Solid oxide fuel cell (SOFC) Computational fluid dynamics (CFD) Numerical simulation

Gold Catalysts Supported on Crystalline Fe_2O_3 and CeO_2/Fe_2O_3 for Low-temperature CO Oxidation

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Chemical Research in Chinese Universities 2010年第1期26卷 98-104页

作者： LIU Rui-hui ZHANG Cun-man MA jian-xin School of Environmental Science and Engineering Tongii University Shanghai 200092 P. R. China Clean Energy Automotive Engineering Center School of Automotive Studies Tongji University Shanghai 201804 P. R. China

High active and stable gold catalysts supported on crystalline Fe203 and CeO2/Fe2O3 were prepared via the deposition-precipitation method. The catalyst with a Au load of 1.0% calcined at 180 ℃ showed a CO conversion of 100% at -8.9℃, while Au/CeO2/Fe2O3 converted CO completely at -16.1 ℃. Even having been calcined at 500 ℃, Au/Fe2O3 still exhibited significant catalytic activity, achieving full conversion of CO at 61.6℃. The catalyst with a low Au load of 0.5% could convert CO completely at room temperature and kept the activity unchanged for at least 150 h. N2 adsorption-desorption measurements show that the crystalline supports possessed a high specific surface area of about 200 m2/g. Characterizations of X-ray diffraction and transmission electron microscopy indicate that gold species were highly dispersed as nano or sub-nano particles on the supports. Even after the catalyst was calcined at 500 ℃, the Au particles remained in a nano-size of about 6--10 nm. X-ray photoelectron spectra reveal that the supported Au existed in metallic state Au0. The modification of Au/Fe2O3 by CeO2 proved to be beneficial to the inhibition of crystallization of Fe2O3 and the stabilization of gold particles in dispersed state, consequently promoting catalytic activity.

关键词： Gold catalyst Low-temperature CO oxidation Iron oxide Nanoparticle Additive

Atomic Coherent Trapping and Properties of Trapped Atom

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Communications in Theoretical Physics 2006年第3X期46卷 556-560页

作者： YANG Guo-jian XIA Li-xin XIE Min Department of Physics Beijing Normal University Beijing 100875 China

Based on the theory of velocity-selective coherent population trapping, we investigate an atom-laser system where a pair of counterpropagating laser fields interact with a three-level atom. The influence of the parametric condition on the properties of the system such as velocity at which the atom is selected to be trapped, time needed for finishing the coherent trapping process, and possible electromagnetically induced transparency of an altrocold atomic medium, etc., is studied.

关键词： velocity selective coherent population trapping ultracold atom

Phase Structure in a Quark Mass Density-and-Temperature-Dependent Model

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Communications in Theoretical Physics 2007年第1期47卷 78-84页

作者： WEN xin-jian PENG Guang-Xiong SHEN Peng-Nian Institute of High Energy Physics the Chinese Academy of Sciences Beijing 100049 China Graduate University of the Chinese Academy of Sciences Beijing 100049 China

The phase diagram of bulk quark matter in equilibrium with a finite hadronic gas is studied. Different from previous investigations, we treat the quark phase with the quark mass density-and-temperature-dependent model to take the strong quark interaction into account, while the hadron phase is treated by hard core repulsion factor. It is found that the phase diagram in this model is, in several aspects, different from those in the conventional MIT bag model, especially at high temperature. The new phase diagram also has strong effects on the mass-radius relation of compact hybrid stars.

关键词： phase diagram quark matter hadron matter

Multi-mesh Adaptive Finite Element Algorithms for Constrained Optimal Control Problems Governed By Semi-Linear Parabolic Equations

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Acta Mathematicae Applicatae Sinica 2014年第2期30卷 411-428页

作者： Tie-jun CHEN jian-xin XIAO Hui-ying WANG Medical College of Yiyang

In this paper, we derive a posteriori error estimators for the constrained optimal control problems governed by semi-linear parabolic equations under some assumptions. Then we use them to construct reliable and efficient multi-mesh adaptive finite element algorithms for the optimal control problems. Some numerical experiments are presented to illustrate the theoretical results.

关键词： semi-linear parabolic equations constrained optimal control problems adaptive finite element methods a posteriori error estimators

Correlation of the retinopathy degree with the change of ocular surface and corneal nerve in patients with type 2 diabetes mellitus

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International Journal of Ophthalmology(English edition) 2021年第5期14卷 750-758页

作者： Jia-xin Han He Wang Huan-Huan Liang jian-xin Guo Xuzhou Medical University Xuzhou 221002Jiangsu ProvinceChina Department of Ophthalmology Affiliated Hospital of Xuzhou Medical UniversityXuzhou 221002Jiangsu ProvinceChina

AIM:To investigate the change of ocular surface and corneal nerve and their correlation in patients suffering from type 2 diabetes mellitus under different degrees of ***:Totally 129 type 2 diabetes mellitus patients(257 eyes)were *** were divided into three groups:no diabetic retinopathy(NDR)group(33 cases,66 eyes),non-proliferative diabetic retinopathy(NPDR)group(32 cases,64 eyes),and proliferative diabetic retinopathy(PDR)group(34 cases,67 eyes).Healthy normal individuals were enrolled as controls(30 cases,60 eyes).Ocular Surface Disease Index(OSDI)questionnaire was completed by all subjects,and dry eye analyzer was applied to examine tear meniscus height(TMH),first tear break-up time(FTBUT),average tear break-up time(ATBUT),tear film lipid layer thickness classification,and meibomian gland loss(MGL)*** nerve fiber density(CNFD),corneal nerve branch density(CNBD),corneal nerve fiber length(CNFL),and corneal nerve fiber tortuosity(CNFT)were examined by in vivo confocal microscopy(IVCM).The differences and correlation among these parameters were ***:Total OSDI score,TMH,FTBUT,ATBUT,tear film lipid layer thickness,MGL score,CNFD,CNBD,CNFL,and CNFT were statistically different among the four groups(P<0.05).In NDR group,CNFL was positively correlated with TMH(r=0.493,both P<0.01)and ATBUT(r=0.437,P<0.05).CNFL in NPDR group was positively correlated with TMH(r=0.642,P<0.01)and ATBUT(r=0.6,P<0.01).CNFL in PDR group was positively correlated with TMH(r=0.364,P<0.05)and ATBUT(r=0.589,P<0.01),with low negative correlation with MGL score(r=-0.331,P<0.05).CONCLUSION:With the progression of diabetic retinopathy,TMH,BUT,lipid layer thickness,CNFL,CNFD,and CNBD gradually decreased,while total OSDI score,MGL score,and CNFT *** is correlated with TMH and ATBUT in diabetic patients.

关键词： type 2 diabetes retinopathy ocular surface corneal nerve in vivo confocal microscopy

Mechanism of high-temperature oxidation effects in fatigue crack propagation and fracture mode for FGH97 superalloy

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Rare Metals 2019年第7期38卷 642-652页

作者： Chao Xu Zhi-Hao Yao jian-xin Dong Yu-Kun jiang School of Materials Science and Engineering University of Science and Technology Beijing

The high-temperature fatigue crack growth behaviors in powder metallurgy (P/M) Ni-based superalloy FGH97 for turbine disk application were investigated at different temperatures (650, 700 and 800℃) in air using a combination a servohydraulic test system, fractographic and microanalytical investigations. It is found that there is a temperature-sensitive region in which the fatigue life of FGH97 alloy decreases sharply. To further evaluate the crack propagation mode and oxidation effects, interruption experiments were conducted at 700 and 300℃, respectively. The results indicate that the reduction of the fatigue lifetime for FGH97 takes place when the fracture mechanism transforms from a predominantly transgranular mode to an intergranular one as the temperature increases. Although the microstructures and mechanical properties may vary with the temperature, they are not the dominating factors contributing to the temperature sensitivity of fatigue property for FGH97. It is the oxidation that governs the fatigue crack growth behaviors in air at elevated temperature. The enhanced thermal activity of oxygen and certain active metal elements result in accelerated oxidation reaction. The brittle oxide intrusions formed at the crack tip and grain boundaries of crack frontier lead to grain boundary weakness, which is responsible for the transformation of crack growth mode and degradation of the fatigue property of FGH97 alloy.

关键词： FGH97 Fatigue crack growth Temperature sensitivity Fracture mode Oxidation

Processing limit maps for the stable deformation of dieless drawing

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International Journal of Minerals,Metallurgy and Materials 2011年第3期18卷 330-337页

作者： Yong He Xue-feng Liu jian-xin Xie Hong-gang Zhang Key Laboratory for Advanced Materials Processing （MOE） University of Science and Technology Beijing Beijing 100083 China State Key Laboratory for Advanced Metals and Materials University of Science and Technology Beijing Beijing 100083 China

Tin bronze wires were produced by dieless drawing. The effects of heating power, the distance between cooler and heater as well as feeding speed on the diameter, the temperature field, and the deformation region profile of the wires were investigated. The results indi-cated that each processing parameter exhibited both lower and upper limits of stable deformation based on the criterion of stable deformation with the diameter fluctuation of ±0.05 mm. Both the temperature and its gradient of the deformation region increased with increasing heating power under stable deformation, but decreased with an increase in feeding speed. As the distance between cooler and heater increased, the temperature of the deformation region increased and the slope of the deformation region profile decreased. The processing limit map of sta-ble deformation exhibited a closed curve and the unstable deformation consisted of wire breakage and diameter fluctuations.

关键词： tin bronze wire dieless drawing processing parameters turning method

Evolution of Mount Cameroon volcanism: Geochemistry, mineral chemistry and radiogenic isotopes(Pb, Sr, Nd)

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Geoscience Frontiers 2020年第6期11卷 2157-2168页

作者： Emmanuel Wenjeh Wembenyui Kenneth D.Collerson jian-xin Zhao School of Earth and Environmental Sciences The University of QueenslandSt.Lucia CampusQLD4072BrisbaneAustralia Institute for Geological and Mining Research(IRGM)//Hydrological Research Centre Cameroon Ministry of Scientific Research and InnovationNkolbissonYaoundeCameroon

Mount Cameroon volcano has erupted several times in the 20 th Century with documented eruptions in 1909,1922,1954,1959,1982,1999 and *** of historic volcanism is represented by several older lava flows and lahar deposits around the flanks of the *** study aims to assess the evolution of Mount Cameroon volcanism through its eruptive history via interpretation of mineralogical,whole rock geochemical and Pb,Sr,Nd isotope data generated from historic and recent lava *** this study,samples were collected from the 1959,1982,1999 and 2000 eruptions and from several historic eruption sites with unknown eruption *** of major and trace element data demonstrates that Mount Cameroon is geotectonically associated with within-plate Ocean Island Basalt *** than 90%of the studied historic lavas(n=29)classify as tephrites and basanites whereas the modern lavas(n=38)are predominantly trachybasalts,demonstrating evolution from primitive to evolved lavas over time typically in response to fractional ***,the lavas are porphyritic with main mineral phases being olivine,clinopyroxene,plagioclase feldspars and Fe-Ti-Cr *** 1982 lavas are predominantly aphyric and dominated by lath-shaped flow-aligned plagioclase in the *** chemistry shows variable forsterite compositions from *** vary from diopside through augite to titanaugite with chemical composition ranges from Wo45En32Fs7 to *** feldspars vary from labradorite(An567 O)to bytownite(An80-87).For the Fe-Ti-Cr oxides,calculated ulvospinel component shows a wide variation from ***-normative classification on the Di-Ol-Hy-Qz-Ne system shows that all Mount Cameroon lavas are nepheline-normative(Ne ranges from4.20 wt.%to 11.45 wt.%).Radiogenic isotope data demonstrate that Mount Cameroon lavas are HIMU(or high μ=238U/204Pb),characterized by 206Pb/204Pb=20.19-20.46,207Pb/204Pb=15.63-15.69,208Pb/204

关键词： Mount Cameroon HIMU Petrogenesis Geochemical evolution Radiogenic isotopes Mineral chemistry