检索结果-南通市图书馆

Clustering behavior of solid particles in two-dimensional liquid-solid fluidized-beds

在线全文

学校读者我要写书评

暂无评论

Particuology 2007年第5期5卷 305-311页

作者： Xiaodong Ana, Mingyan Liua,b,, Yunguan Fua a School of chemical Engineering and Technology, tianjin University, tianjin 300072. china b State Key Laboratory of chemical Engineering, tianjin University, tianjin 300072. china School of chemical Engineering and Technology Tianjin University Tianjin 300072 China State Key Laboratory of chemical Engineering Tianjin University Tianjin 300072 China

In this paper, the clustering behavior of solid particles in a two-dimensional (2.) liquid-solid fluidized-bed was studied by using the charge coupled devices (CCD) imaging measuring and processing technique and was characterized by fractal analysis. CCD images show that the distribution of solid particles in the 2. liquid-solid fluidised-bed is not uniform and self-organization behavior of solid particles was observed under the present experimental conditions. The solid particles move up in the 2. fluidized-bed in groups or clusters whose configurations are often in the form of horizontal strands. The box fractal dimension of the cluster images in the 2. liquid-solid fluidized-bed increases with the rising of solid holdup and reduces with the increment of solid particle diameter and superficial liquid velocity. At given solid holdup and solid particle size, the lighter particles show smaller fractal dimensions.

关键词： CCD Liquid–solid ?uidized-bed Fractal dimension Cluster Self-organization structure

Hilbert transform and its application to modulation of capillary gravity waves

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Acta Oceanologica Sinica 2001年第3期20卷 309-315页

作者： Yin Zhongbin, Lu Jun, Tian Jiwei 1. physical Oceanography Laboratory, Ocean University of Qingdao, Qingdao 2.6003, china 2. {2. Polytechnic University, {2.. china physical Oceanography Laboratory Ocean University of Qingdao Qingdao 266003 China tianjin Polytechnic University Tianjin China

In this paper, the following important problem is answered: Under what condition can the Hilbert transform be put in the simple form. Then, using the Hilbert technique, it is demonstrated that, with some relative weak restrictions, the particle motion at the sea surface and energy transmission may be obtained from a wave record. The analysis show that for the two-dimensional and narrow-band mo- tion (or a physical phenomena, such as capillary waves breaking, which satisfy the narrow-band approx- imation) the local kinetic energy fluctuates in time as the envelope equared multiplied by a constant factor and can be obtained directly from a wave record. It is pointed that the local fluctuatiom of the potential energy as well as the local fluctuations of the total energy can be separated into a slowly varying part and a more rapid oscillating Part. Both Parts can be evaluated by meaas of the Hilbert transform. Finally, a physical interpretation of the envelope of the two-dimensional capillary waves as well as the method for wave group analysis is presented.

关键词： Hilbert tranform capillary gravity waves

Piezoelectric and dielectric properties of Cr-doped PSN-PZN-PZT qua-ternary piezoelectric ceramics

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2005年第2期24卷 185-189页

作者： SUNQingchi WANGLifeng LIUPing NIEQiang SchoolofMaterialsScienceandEngineering TianjinUniversityTianjin300072China SchoolofchemicalEngineeringandTechnology TianjinUniversityTianjin300072China

PSN-PZN-PZT + x wt. %Cr2.3, X = 0.0-0-9, were prepared by conventional mixed oxide techniques at sintering temperatures of 12.0 degrees C-1300 degrees C for 2.h. The effect of sintering temperature on the microstructure and the piezoelectric properties was investigated by XRD, SEM, and other conventional measurement. The result indicated that with temperature increasing, the valence of Cr ion from Cr5+ or Cr6+ changes into C3+, and the piezoelectric properties turn hard. With increasing Cr2.3 content, the amount of rhombohedral phases increases and the morphotropic boundary phase is correspondingly shifts to rhombohedral phase. A uniform microstructure and excellent comprehensive properties were obtained at 12.0 degrees C as the amount of Cr2.3 is 0.5 wt.%.

关键词： inorganic nonmetallic materials PSN-PZN-PZT conventional solid reaction process Cr2.3 content sintering temperature piezoelectric properties

Runaway Criterion in Fixed Bed Catalytic Reactors with Radial Temperature Profile

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of chemical Engineering 1999年第4期7卷 307-314页

作者：吴鹏樊勇李绍芬天津大学化工学院天津 300072 天津大学化工学院天津

The discrepancy between pseudo-homogeneous one-dimensional model and pseudo-homogeneous two-dimensional model is studied. It is found that there are great differences between two models. This paper compares the maximum and minimum values of the radial temperature in the hot spot in case that a single exothermic reaction is carried out, a correlation is obtained with pseudo-homogeneous one-dimensional model to describe the entire reactor behavior. A new runaway criterion, based on the occurrence of inflection in the hot spot locus, is developed for the case of pseudo-homogeneous two-dimensional model. This criterion predicts the maximum allowable temperature for safe operation and the regions of runaway, respectively. The calculated results show that, compared with the results based on pseudo-homogeneous one-dimensional model, runaway will easily occur when the radial temperature gradient has to be considered.

关键词： parametric sensitivity runaway fixed bed catalytic reactor

Influence of p-layer on the performance of n-i-p μc-Si:H thin film solar cells

在线全文

学校读者我要写书评

暂无评论

Science china(Physics,Mechanics & Astronomy) 2010年第11期53卷 2042-2046页

作者： YUAN YuJie 1,2.ZHANG KaiLiang 1,2.WEI Zhen 1,2.& GENG XinHua 3 1 College of Electronics Information Engineering,tianjin University of Technology,tianjin 300384,{2. 2.tianjin Key Laboratory of Film Electronic and Communication Devices,tianjin University of Technology,tianjin 300384,{2. 3 Institute of Photo-Electronics Thin Film Devices and Technique,Nankai University,tianjin 300071,{2. tianjin University of Technology College of Electronics Information Engineering Tianjin China (GRID:grid.265025.6) tianjin University of Technology Tianjin Key Laboratory of Film Electronic and Communication Devices Tianjin China (GRID:grid.265025.6) Nankai University Institute of Photo-Electronics Thin Film Devices and Technique Tianjin China (GRID:grid.216938.7) (ISNI:***)

The high pressure radio frequency plasma enhanced chemical vapor deposition (RF-PECVD) process was adopted to prepare the n-i-p microcrystalline silicon solar cells,the influence of p-type layers on the performance of the solar cells was investigated,and the optimum p layer suited to the n-i-p microcrystalline silicon solar cells was *** experimental results demonstrate that the performance of the solar cells can be highly affected by the structural and optical properties of the p-layers,and the performance of solar cells can be greatly improved by optimizing p *** have achieved an initial active-area efficiency of 8.17% (V oc =0.49 V,J sc =2..9 mA/cm 2.,FF=67%) for the μc-Si:H single-junction n-i-p solar cells and an initial active-area efficiency of 10.93% (V oc =1.31 V,J sc =13.09 mA/cm 2.,FF=64%) for the a-Si:H/μc-Si:H tandem n-i-p solar cells.

关键词： microcrystalline silicon solar cells quantum confinement effect p-type layers

A Study of Spiral Tap with Large Diameter

在线全文

学校读者我要写书评

暂无评论

厦门大学学报（自然科学版） 2002年第S1期41卷 134-135页

作者： LI Lin 1, LI Da-wei 1, CHAI De-ming 2.(1. tianjin Chinese-German Vocational Training Center, tianjin 300191 ,{2. 2. The Experimental Eanipent-Making Factory under physical Chemistry Academy Spiral, tianjin 300180,{2.)

The design and manufacture of spiral tap yet are in r esearch stage at present. This paper mainly introduces how to calculate its geom etric parameters and scientific selection of them with vector method. In additio n, an empiric formula of the tool life of spiral tap with large diameter is esta blished by method of correlation. The practice of design, manufacture and applying proves the advantage of spiral tap by the comparison between the spiral tap and common tap with same size. In the application of spiral tap has got better economic effect. The cutting fea ture and economic effect are obvious, that mean spiral tap greatly better than c ommon tap. The bright and wide prospect are going to come. No greatly increasing the ω can be effective to improve the cutting condition. Scientific selection of cutting speed V can increase the tool life of tapping and life of tapping too l.

关键词： spiral tap large diameter service life durabil ity formula

FKBP2. in ER binds to BiP specifically

在线全文

学校读者我要写书评

暂无评论

Science china Chemistry 2004年第1期47卷 17-23页

作者： ZHANG Wanqi, LI Hui, ZHANG Xiaobin, SHEN Ye, WANG Yinong, Ml Huaifeng & HE BinglinState Key Laboratory of Functional Polymer Materials for Adsorption and Separation, chemical School of Nankai University, tianjin 300071,{2. Hygienic School of tianjin Medical University, tianjin 300071,{2. Medical School of Nankai University, tianjin 300071,{2. State Key Laboratory of Functional Polymer Materials for Adsorption and Separation Chemical School of Nankai University Tianjin China Hygienic School of tianjin Medical University Tianjin China Medical School of Nankai University Tianjin China

FKBP2. was found in mouse endoplasmic reticulum (ER) in 1998. It consists of an N-terminal peptidyl-prolyl cis-trans isomerase (PPlase) domain and a C-terminal domain with Ca2. binding sites. The fusion protein of mouse FKBP2. and glutathione S-transferase (GST), GST-FKBP2., and the fusion protein of BiP, a member of heat shock protein 70 (Hsp 70) in ER, and GST, GST-BiP, were subcloned in E. coli, expressed and purified. The fusion proteins were restrictively digested by Factor Xa (FaXa) to obtain the free cloned proteins FKBP2. and BiP. With the assay of adsorption of free FKBP2. or BiP with GST-BiP or GST-FKBP2. attached to the Glutathione-Sepharose 4B, the adsorbed FKBP2. or BiP could be detected by Immunoblot. It means that FKBP2. binds to BiP. Furthermore, BiP in leukocyte ER-extract can be adsorbed with GST-FKBP2. attached to the glutathione-Sepharose 4B. It shows that FKBP2. binds to natural BiP in ER, too. These experiments show that a PPIase binds to a molecular chaperone of the Hsp70 family.

关键词： peptidyl-prolyl cis/trans isomerase, FKBP2., BiP, endoplasmic reticulum, specific binding.

Alkylation mechanism of benzene with 1-dodecene catalyzed by Et_3NHCl-AlCl_3

在线全文

学校读者我要写书评

暂无评论

Science china Chemistry 2010年第5期53卷 1101-1106页

作者： QI GuoPeng 1,JIANG Feng 1,SUN XueWen 2.& ZHAO SuoQi 2.1School of chemical Engineering,tianjin University,tianjin 300072.china 2.tate key Laboratory of Heavy Oil Processing,Petroleum University of china,Beijing 102.49,china School of chemical Engineering Tianjin University Tianjin China State key Laboratory of Heavy Oil Processing Petroleum University of China Beijing China

The isotope exchange method was employed to investigate the catalytic mechanism of ionic liquid in alkylation of benzenes with *** is proposed that alkylation was induced by the Lewis acid AlCl3 which attracted π electrons of 1-dodecene to shift toward 1-carbon,thus forming a carbonium *** carbonium ion further reacted with benzenes to form a *** to unstabilit of the complex,a deuterated ring proton was transferred into an electronegative 1-carbon of the side chain to substitute for the AlCl3,accordingly 2.phenyldodecane was generated.

关键词： ionic liquid alkylation mechanism deuteriobenzene isotope exchange method

Conversion of Methane to C_2.Hydrocarbons via Cold Plasma Reaction

在线全文

学校读者我要写书评

暂无评论

Journal of Natural Gas Chemistry 2003年第3期12卷 178-182页

作者： Baowei Wang, Genhui XuSchool of chemical Engineering and Technology, tianjin University, tianjin 300072. china School of chemical Engineering and Technology Tianjin University

Direct conversion of methane to C_2.hydrocarbons via cold plasma reactionwith catalysts has been studied at room temperature and atmospheric pressure. Methane can beconverted into C_2.hydrocarbons in different selectivity depending on the form of the reactor, powerof plasma, flow rate of methane, ratio of N_2.CH_4 and nature of the catalysts. The selectivity toC_2.hydrocarbons can reach as high as 98.64%, and the conversion of methane as high as 60% and theyield of C_2.hydrocarbons as high as 50% are obtained. Coking can be minimized under the conditionsof: proper selection of the catalysts, appropriate high flow rate of inlet methane and suitableratio of N_2.to CH_4. The catalyst surface provides active sites for radical recombination.

关键词： methane C_2.hydrocarbons cold plasma catalyst