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Photocatalytic degradation of formaldehyde by diffuser of solar light pipe coated with nanometer titanium dioxide thin films

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Science china(Technological Sciences) 2010年第1期53卷 150-154页

作者： WU YanPeng1,ZHANG WenMing1,MA ChongFang2,LU YuanWei2 & LIU Li1 1 School of Civil and Environmental Engineering,University of Science and technology beijing,beijing 100083,china 2 college of Environmental and energy Engineering,beijing University of technology,beijing 100022,china School of Civil and Environmental Engineering University of Science and Technology Beijing Beijing China college of Environmental and energy Engineering Beijing University of Technology Beijing China

The even and transparent nanometer TiO2 thin films named DegussaP25 as photocatalysis deposited on the surface of diffusers of solar light pipe were prepared by sol-gel *** rugged side of the diffusers of solar light pipe was coated evenly with DegussaP25 solution for the quality of 1.75 *** experiments had showed that when the coated side was away from the sun the lighting degree may be reduced compared with that facing the *** average reduction was only 3.03%,which would not have a significant impact on *** are important parts of a light pipe which can diffuse light evenly to the place needed to be *** experiments showed that in a sunny summer day under the direct sunlight,the solar light pipe combined with photocatalysis could reduce the formaldehyde volume fraction in a box of 0.1 m3 from 1.0×10-6 to 0.16×*** 1 h of photodegradation the formaldehyde volume changed from 1.0×10-6 down to 0.1×10-6 with faster and more complete degradation of *** rate of degradation under cloudy and partly cloudy conditions was slower than that under sunny *** was slower in winter than in summer under sunny *** experimental results also showed that the performance of photocatalysis combined with diffusers of light pipe had better effect in a small *** performance in large space,such as open space,will be the next work in the future,which will be a great challenge.

关键词： solar light pipes diffusers photocatalysis decomposition formaldehyde titanium dioxide

Fractal model for simulation of frost formation and growth

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Science china(Technological Sciences) 2010年第3期53卷 807-812页

作者： LIU YaoMin,LIU ZhongLiang,HUANG LingYan&SUN junFang Education Ministry key Laboratory of Enhanced Heat Transfer and energy conservation,college of Environmental and energy Engineering,beijing University of technology,beijing 100124,china Education Ministry key Laboratory of Enhanced Heat Transfer and energy conservation College of Environmental and Energy Engineering Beijing University of Technology Beijing China

A planar fractal model for simulation of frost formation and growth was proposed based on diffusion limited aggregation(DLA)model and the computational simulation was carried out in this *** changing the times of program running circulation and the ratio of random particles generated,the simulation figures were gained under different conditions.A microscope is used to observe the shape and structure of frost layer and a digital camera with high resolution is used to record the pattern of frost layer at different *** comparing the simulation figures with the experimental images,we find that the simulation results agree well with the experimental images in shape and the fractal dimension of simulation figures is nearly equal to that of experimental *** results indicate that it is reasonable to represent frost layer growth time with the program circulation times and to simulate the frost layer density variation during its growth process by reducing the random particle generation *** feasibility of using the suggested model to simulate the process of frost formation and growth was *** insufficiencies and its causes of this fractal model are also discussed.

关键词： fractal frost formation and growth DLA simulation

Crystallization behavior of zeolite beta from acid-leached metakaolin

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Petroleum Science 2010年第4期7卷 541-546页

作者： Li Qiang Zhang Ying Cao Zhijun Gao Wei Cui Lishan Department of Materials Science and technology China University of Petroleum Beijing 102249 China National key Laboratory of Multiphase complex System Institute of Process Engineering Chinese Academy of Sciences Beijing 100190 China Microstructure Laboratory for energy Materials China University of Petroleum Beijing 102249 China

Well-crystallized zeolite beta was synthesized by using acid-leached metakaolin as the silica-alumina source and tetraethylammonium hydroxide structure-directing *** influence of the composition of the reaction mixture on product crystallinity was investigated,and the crystallization process was studied by examining solid samples obtained at different synthesis *** showed that the acid-leached metakaolin was fully converted into soluble aluminum and silicon species,which is crucial for the formation of well-crystallized zeolite *** the beginning of the crystallization process,these soluble aluminum and silicon species formed a aluminum-rich intermediate structure with layer *** the crystallization proceeding,more silicon species were incorporated into the zeolite beta framework and the layered structure was changed into spherical particles of zeolite beta with high SiO 2 /Al 2 O 3 ratio and crystallinity.

关键词： Zeolite beta acid-leached metakaolin tetraethylammonium hydroxide (TEAOH) liquid phase transformation mechanism

Influence of synthesis parameters on the crystallinity and Si/Al ratio of NaY zeolite synthesized from kaolin

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Petroleum Science 2010年第3期7卷 403-409页

Well-crystallized high-silica NaY zeolites （Si/Al〉2.5） were prepared from a reaction mixture consisting of metakaolin, sodium silicate solution and seed solution via optimization of the mixture composition and reaction conditions. The transformation from kaolin to high-silica NaY zeolite was confirmed by XRD, SEM and IR techniques. Subsequently, the influence of synthesis parameters, i.e. initial SIO2/Al2O3, initial Na2O/SiO2, initial H2O/SiO2, aging time of the seed solution, crystallization temperature and crystallization time, on the NaY growth was investigated in terms of crystallinity and Si/Al ratio. The results showed that the effects of initial SiO2/Al2O3, initial Na2O/SiO2 and initial H2O/ SiO2 on the crystaIlinity and Si/Al ratio of NaY zeolite are similar to those observed in the conventional syntheses of NaY zeolites only using sodium silicate solution as silicon source. However, due to the use of metakaolin as the main silicon and aluminum sources in the present study, a long crystallization induction period of 20 h was achieved, which can be attributed to the dissolution of metakaolin. In addition, different from the conventional syntheses of zeolite NaY, pure NaY zeolites （i.e. without NaP zeolite impurity） were still obtained even at 120℃ because of the use of a large quantity of seed solution （23 wt%） in the reaction mixture. As the aging time of the seed solution increased from 3.5 h to 22 h, the relative crystallinity of the NaY zeolite first increased sharply and then reached a plateau, while the Si/Al ratio first increased rapidly up to a maximum value of 2.75 corresponding to an aging time of 6.5 h, and then decreased sharply with the aging time.

关键词： kaolin NaY zeolite high-silica seed solution aging time crystallinity

A Creep Equation Based on Thermal Activation

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International journal of Minerals,Metallurgy and Materials 1998年第1期12卷 44-46页

作者： jiyue Sun Guoliang Chen (State key Laboratory for Advanced Metals and Materials, 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

The creep equation proposed in so called θ projection concept is developed in the concept of thermal activation of creep. The measured creep curves of A286 alloy are fitted by the equation. The activation energy in theequation is evaluated, and creep rupture lives are predicted. The results are confirmed by creep tests of up to 13years.

关键词： creep creep curve equation creep rupture life A286 superalloy

Effect of powder mixing process on the microstructure and thermal conductivity of Al/diamond composites fabricated by spark plasma sintering

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Rare Metals 2010年第1期29卷 86-91页

作者： CHU ke, jIA Chengchang, LIANG Xuebing, and CHEN Hui School of Materials Science and Engineering, University of Science and technology beijing, beijing 100083, china School of Materials Science and Engineering University of Science and Technology Beijing Beijing China

Two powder mixing processes, mechanical mixing （MM） and mechanical alloying （MA）, were used to prepare mixed Al/diamond powders, which were subsequently consolidated using spark plasma sintering （SPS） to produce bulk Al/diamond composites. The effects of the powder mixing process on the morphologies of the mixed powders, the microstructure and the thermal conductivity of the composites were investigated. The results show that the powder mixing process can significantly affect the microstructure and the thermal conductivity of the composites. Agglomerations of the particles occurred in mixed powders using MM for 30 min, which led to high pore content and weak interfacial bonding in the composites and resulted in low relative density and low thermal conductivity for the composites. Mixed powders of homogeneous distribution of diamond particles could be obtained using MA for 10 min and MM for 2 h. The composite prepared through MA indicated a high relative density but low thermal conductivity due to its defects, such as damaged particles, Fe impurity, and local interfacial debonding, which were mainly introduced in the MA process. In contrast, the composite made by MM for 2 h demonstrated high relative density and an excellent thermal conductivity of 325 W.m^-1.k^-1, owing to its having few defects and strong inter-facial bonding.

关键词： metal matrix composites thermal properties sintering powder mixing

Finite-dimensional (*)-serial algebras

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Science china Mathematics 2010年第12期53卷 3049-3056页

作者： YAO HaiLou & FAN WeiLi college of Applied Science, beijing University of technology, beijing 100124, china college of Applied Science Beijing University of Technology Beijing China

Let A be a finite-dimensional associative algebra with identity over a field k. In this paper we introduce the concept of (*)-serial algebras which is a generalization of serial algebras. We investigate the properties of (*)-serial algebras, and we obtain suficient and necessary conditions for an associative algebra to be (*)-serial.

关键词： (*)-serial algebras biserial modules uniserial modules

Analysis on the Microstructure and Performance Evolvement of Alloyed Tool Steel Hot Rolling Strip Produced by CSP technology

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journal of Iron and Steel Research International 2011年第S1期18卷 621-624页

作者： CHEN jing-hu 1,2,jIE Xiao-hua 1 (1.Faculty of Materials and energy,Guangdong University of technology,Guangzhou510006,Guangdong,china 2.technology Center of Guangzhou Steel Group co.ltd.,Guangzhou510380,Guangdong,china) Guangdong Univ Technol Fac Mat & Energy Guangzhou 510006 Guangdong Peoples R China Guangzhou Steel Grp co ltd Ctr Technol Guangzhou 510380 Guangdong Peoples R China

This thesis determinates the microstructure and inclusions of the alloyed tool steel by CSP processing with the help of *** results show that the slab microstructures are the fine branched crystalline grains and the branch width has little disparity from the surface to the central *** the product,the grain microstructures are fine pearlites and few ferrites with the pearlite space 0.4μm to 0.2μm.

关键词： compact strip production alloyed tool steel microstructure grain

Exploration of combined adjustment laws about IGV,stator and rotational speed in off-design conditions in an axial compressor

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中国科学：技术科学英文版 2010年第4期53卷 969-975页

作者： HU YanMing1,2 & NIE ChaoQun1 1 key Laboratory of Advanced energy and Power technology,Institute of Engineeting Thermophysics,Chinese Academy of Science,beijing 100190,china 2 Graduate School of Chinese Academy of Sciences,beijing 100190,china key Laboratory of Advanced energy and Power technology Institute of Engineeting Thermophysics Chinese Academy of Science Beijing China Graduate School of Chinese Academy of Sciences Beijing China

Experimental investigations are performed in a three-stage low-speed axial compressor with variable inlet guide vanes(IGV) and adjustable *** characteristics of the compressor,especially the efficiency and stall margin,are analyzed in design and off-design operation conditions by adjusting stagger angles of IGV and stators as well as changing the rotational *** experimental results show that the off-design performance of the multistage axial compressor is improved by restaggering of IGV and stators related to rotational *** the background of engineering applications,digital signal processing(DSP) technique is used to realize online adjustment of stagger angles according to the corresponding relations between incidence angles of rotor and rotational speed.

关键词： axial compressor IGV surge DSP techniques off-design