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Some New Results on Transition Probability

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Acta Mathematica Sinica,English Series 2008年第12期24卷 1965-1984页

作者： Yu quan xie School of Mathematics and Computational Science Xiangtan University Xiangtan 411105 P. R. China

In this paper, we study the basic properties of stationary transition probability of Markov processes on a general measurable space （E, δ）, such as the continuity, maximum probability, zero point, positive probability set,standardization, and obtain a series of important results such as Continuity Theorem, Representation Theorem, Levy Theorem and so on. These results are very useful for us to study stationary tri-point transition probability on a general measurable space （E, δ）. Our main tools such as Egoroff＇s Theorem, Vitali-Hahn-Saks＇s Theorem and the theory of atomic set and well- posedness of measure are also very interesting and fashionable.

关键词： Markov processes stationary transition probability maximum probability uniformly standard representation theorem

Willmore Submanifolds in the Unit Sphere via Isoparametric Functions

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Acta Mathematica Sinica,English Series 2015年第12期31卷 1963-1969页

作者： Yu quan xie Department of Mathematics Hangzhou Normal University

In this paper,we show that both focal submanifolds of each isoparametric hypersurface in the sphere with six distinct principal curvatures are Willmore,hence all focal submanifolds of isoparametric hypersurfaces in th... 详细信息

关键词： Willmore submanifold isoparametric hypersurface focal submanifold

Relationship between the Thickness of β-FeSi_2 Thin Film and the Solar Photo Wavelength

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Chinese Journal of Mechanical Engineering 2012年第2期25卷 315-319页

作者： XIONG Xicheng xie quan YAN Wanjun Institute of Advanced Optoelectronic Materials and Technology College of ScienceGuizhou UniversityGuiyang 550025China

The β-FeSi2 thin film has been applied in the research field of the solar cell,and the thickness of β-FeSi2 absorption layer was chosen through the ***,Up to now neither the optimal thickness of β-FeSi2 absorption layer nor the relationship between the thickness of β-FeSi2 absorption layer and the solar photo wavelength has been theoretically *** this paper,the relationship between the thickness of the absorption layer of β-FeSi2 thin film solar cell and the solar photo wavelength is calculated and analyzed by *** results show that the thickness of the absorption layer of β-FeSi2 is at least 200 nm when the optical absorption efficiency of the solar energy reaches 90%,and that the optimal thickness range is from 200 nm to 250 nm,and that the optimal wavelength of the photon absorbed by β-FeSi2 thin film solar cell is from 0.46 μm？0.6 μ***,two formulas are put forward to indicate the relationship between the thickness of the absorption layer of β-FeSi2 thin film solar cell and the solar photo *** thickness of the absorption layer of β-FeSi2 thin film solar cell increases linearly with the solar photo wavelength within the optimal photo *** formulas provide a reliable theoretical basis of determining the thickness of the β-FeSi2 thin film in the solar cell.

关键词： β-FeSi2 solar cell absorption layer thickness

Enhancing anoxic denitrification of low C/N ratio wastewater with novel ZVI composite carriers

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Journal of Environmental Sciences 2022年第2期34卷 180-191页

作者： Yanping Shi Tao Liu Hongtao Yu xie quan Key Laboratory of Industrial Ecology and Environmental Engineering(Ministry of Education) School of Environmental Science and TechnologyDalian University of TechnologyDalian 116024China

External organic carbon sources are needed to provide electron donors for the denitrification of wastewater with a low COD/NO_(3)^(-)-N(C/N)ratio,increasing the treatment *** economic strategy is to enhance the bioactivity and/or biodiversity of denitrifiers to efficiently utilize organic substances in *** this study,novel zero-valent iron(ZVI)composite carriers were prepared and implemented in a suspended carrier biofilm reactor to enhance the bioactivity and/or biodiversity of *** the influent C/N ratio of 4(COD was 179.5±5.0 mg/L and TN was 44.2±0.8 mg/L),COD and TN removal efficiencies were 85.1%and 66.4%,respectively,in the reactors filled with 3 wt%ZVI composite *** contrast,COD and TN removal efficiencies were 70.4%and 55.3%,respectively,in the reactor filled with conventional high-density polyethylene(HDPE)biofilm *** biofilm formation on the 3 wt%ZVI composite carriers was optimized due to its higher roughness(surface square roughness increased from 76.0 nm to 93.8 nm)and favorable hydrophilicity(water contact angle dropped to 72.5°±1.4°from 94.3°±3.2°)compared with the HDPE biofilm *** addition,heterotrophic denitrifiers,Thauera and Dechloromonas,were enriched,whereas autotrophic denitrifiers,Raoultella and Thiobacillus,exhibited high relative abundance in the biofilm of ZVI composite *** coexistence of heterotrophic denitrifiers and autotrophic denitrifiers on the surface of ZVI composite carriers provided mixotrophic metabolism of denitrification(including heterotrophic and iron-based autotrophic),thereby ensuring effective denitrification for wastewater with a low C/N ratio without external organic carbon source addition.

关键词： ZVI Biofilm carrier Low C/N ratio Integrated floating fixed-film and activated sludge(IFFAS) Denitrification

Hydrogen Storage Performance During Underground Hydrogen Storage in Depleted Gas Reservoirs:A Review

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Engineering 2024年第9期40卷 211-225页

作者： Lingping Zeng Regina Sander Yongqiang Chen quan xie CSIRO Energy MelbourneVIC 3168Australia Hydrogen Industry Mission CSIROMelbourneVIC 3168Australia CSIRO Energy KensingtonWA 6151Australia Permanent Carbon Locking Future Science Platform CSIRO EnergyKensingtonWA 6151Australia WA School of Mines:Minerals Energy and Chemical EngineeringCurtin UniversityKensingtonWA 6151Australia

Hydrogen has emerged as a promising alternative to meet the growing demand for sustainable and renewable energy *** hydrogen storage(UHS)in depleted gas reservoirs holds significant potential for large-scale energy storage and the seamless integration of intermittent renewable energy sources,due to its capacity to address challenges associated with the intermittent nature of renewable energy sources,ensuring a steady and reliable energy *** the existing infrastructure and well-characterized geological formations,depleted gas reservoirs offer an attractive option for large-scale hydrogen storage ***,significant knowledge gaps regarding storage performance hinder the commercialization of UHS *** deliverability,hydrogen trapping,and the equation of state are key areas with limited *** literature review critically analyzes and synthesizes existing research on hydrogen storage performance during underground storage in depleted gas reservoirs;it then provides a high-level risk assessment and an overview of the techno-economics of *** significance of this review lies in its consolidation of current knowledge,highlighting unresolved issues and proposing areas for future *** these gaps will advance hydrogen-based energy systems and support the transition to a sustainable energy *** efficient and safe deployment of UHS in depleted gas reservoirs will assist in unlocking hydrogen’s full potential as a clean and renewable energy *** addition,this review aids policymakers and the scientific community in making informed decisions regarding hydrogen storage technologies.

关键词： Underground hydrogen storage Storage performance Hydrogen deliverability Hydrogen trapping Risk assessment Techno-economic analysis

Gold modified microelectrode for direct tetracycline detection

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Frontiers of Environmental Science & Engineering 2012年第3期6卷 313-319页

作者： Hongtao WANG Huimin ZHAO xie quan Key Laboratory of Industrial Ecology and Environmental Engineering (MOE) School of Environmental Science and Technology Dalian University of Technology Dalian 116024 China

The residues of tetracycline antibiotics in water have attracted many concerns due to their harmful impact to human health. This paper reports an electrochemical sensor for the determination of tetracycline (TC) by the microelectrode, which was fabricated by electrodeposited gold colloids on tungsten tip. Cyclic voltammerty was used to study the electrochemical behavior of TC on the microelectrode. Well anodic wave was obtained at about 1.5 V in acidic solutions. Electrochemical determination of tetracycline was investigated using microelectrode by cyclic voltammetry. Under optimized conditions, the calibration curves for TC were obtained. The oxidation peak currents were linearly related to TC concentrations in the range of 1–10 mg·L?1 and 10–100 mg·L?1, respectively. The detection limit was 0.09 mg·L?1 (S/N = 3).

关键词： microelectrode tungsten tip gold colloids tetracycline

Conductive and stable polyphenylene/CNT composite membrane for electrically enhanced membrane fouling mitigation

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Frontiers of Environmental Science & Engineering 2024年第1期18卷 35-47页

作者： Huijuan xie Haiguang Zhang Xu Wang Gaoliang Wei Shuo Chen xie quan Key Laboratory of Industrial Ecology and Environmental Engineering(Ministry of Education) School of Environmental Science and TechnologyDalian University of TechnologyDalian 116024China

Nanocarbon-based conductive membranes, especially carbon nanotube (CNT)-based membranes, have tremendous potential for wastewater treatment and water purification because of their excellent water permeability and selectivity, as well as their electrochemically enhanced performance (e.g., improved antifouling ability). However, it remains challenging to prepare CNT membranes with high structural stability and high electrical conductivity. In this study, a highly electroconductive and structurally stable polyphenylene/CNT (PP/CNT) composite membrane was prepared by electropolymerizing biphenyl on a CNT hollow fiber membrane. The PP/CNT membrane showed 3.4 and 5.0 times higher electrical conductivity than pure CNT and poly(vinyl alcohol)/CNT (PVA/CNT) membranes, respectively. The structural stability of the membrane was superior to that of the pure CNT membrane and comparable to that of the PVA/CNT membrane. The membrane fouling was significantly alleviated under an electrical assistance of −2.0 V, with a flux loss of only 11.7% after 5 h filtration of humic acid, which is significantly lower than those of PP/CNT membranes without electro-assistance (56.8%) and commercial polyvinylidene fluoride (PVDF) membranes (64.1%). Additionally, the rejection of negatively charged pollutants (humic acid and sodium alginate) was improved by the enhanced electrostatic repulsion. After four consecutive filtration-cleaning cycle tests, the flux recovery rate after backwashing reached 97.2%, which was much higher than those of electricity-free PP/CNT membranes (67.0%) and commercial PVDF membranes (61.1%). This study offers insights into the preparation of stable conductive membranes for membrane fouling control in potential water treatment applications.

关键词： Polyphenylene CNTs Membrane Electro-assistance Membrane fouling mitigation

Covering α-Fe2O3 protection layer on the surface of p-Si micropillar array for enhanced photoelectrochemical performance

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Frontiers of Environmental Science & Engineering 2017年第6期11卷 119-127页

作者： Jing Gu Hongtao Yu xie quan Shuo Chen Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education) School of Environmental Science and Technology Dalian University of Technology Dalian 116024 China

The spontaneous oxidation process of pristine silicon （Si） limits its application as photocatalyst or electrode in aqueous solution or moist air. Covering a protection layer on Si surface is an effective approach to overcome this disadvantage. In this paper, α-Fe2O3 is demonstrated to be an excellent alternative as a protection material, α-Fe2O3 layer was deposited around each p-type Si micropillar （SiMP） in well-ordered array by chemical bath ＂deposition ＂method. The diameter of SiMP was 3 μm and the thickness of α-Fe2O3 layer was about 20 nm. The photoeletrochemical stability of SiMP/α-Fe2O3 was proved by 10 circles cyclic voltammetr7 testing. Compared with SiMP, its optical absorption and photocurrent density improved 2 times and 4 times, respectively, and its onset potential for hydrogen evolution moved positively about 0.4 V. These improved performances could be ascribed to the enhanced photogenemted-charge-separation efficiency deriving from built-in electric field at the interface between Si and α-Fe2O3. The above results show an effective strategy to utilize Si material as photocatalyst or electrode in aqueous solution or moist air.

关键词： Si α-Fe2O3 Photoelectrochemistry Photogenemted charge separation

Catalytic reductive dechlorination of p-chlorophenol in water using Ni/Fe nanoscale particles

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Journal of Environmental Sciences 2007年第3期19卷 362-366页

作者： ZHANG Wei-hua quan xie ZHANG Zhuo-yong College of Urban and Environmental Sciences Northeast Normal University Changchun 130024 China School of Environmental and Biological Science and Technology Dalian University of Technology Dalian 116023 China College of Chemistry Inner Mongolia University for the Nationalities Tongliao 028043 China

Nanoscale bimetallic Ni/Fe particles were synthesized from the reaction of sodium borohydride （NaBH4） with reduction of Ni^2＋ and Fe^2＋ in aqueous solution. The obtained Ni/Fe particles were characterized by TEM （transmission electron microscope）, XRD （X-ray diffractometer）, and N2-BET. The dechlorination activity of the Ni/Fe was investigated using p-chlorophenol （p-CP） as a probe agent. Results demonstrated that the nanoscale Ni/Fe could effectively dechlorinate p-CP at relatively low metal to solution ratio of 0.4 g/L （Ni 5 wt%）. The target with initial concentration ofp-CP 0.625 mmol/L was dechlorinted completely in 60 rain under ambient temperature and pressure. Factors affecting dechlorination efficiency, including reaction temperature, pH, Ni loading percentage over Fe, and metal to solution ratio, were investigated. The possible mechanism of dechlorination ofp-CP was proposed and discussed. The pseudo-first- order reaction took place on the surface of the Ni/Fe bimetallic particles, and the activation energy of the dechlorination reaction was determined to be 21.2 kJ/mol at the temperature rang of 287-313 K.

关键词： Ni/Fe bimetal nanoscale particles catalytic reduction p-CP dechlorination