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Kinetics of the Oxidative Dehydrogenation of Propane over a VMgO Catalyst

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Journal of Energy Chemistry 2002年第Z1期 33-42页

作者： L.Late,E.A.BlekkanDepartment of Chemical Engineering, Norwegian University of Science and Technology (NTNU), N-7491 Trondheim, Norway[Manuscript received June 6, 2002 revised july 2, 2002]

The reaction kinetics of the oxidative dehydrogenation of propane was studied at 475-550℃ over a VMgO catalyst. Vanadium-magnesium-oxides are among the most selective and active catalysts for the dehydrogenation of propane to propylene. Selectivity to propylene up to about 60% was obtained at 10% conversion, but the selectivity decreased with increasing conversion. No oxygenates were detected, the only by-products were CO and CO2. The reaction rate of propane was found to be first order in propane and close to zero order in oxygen, which is in agreement with a Mars van Krevelen mechanism with the activation of the hydrocarbon as the rate determining step. The activation energy of the conversion of propane was found to be 122±6 kJ/mol.

关键词： propane oxidative dehydrogenation VMgO kinetics

INFLUENCE OF COLD ROLLING TECHNOLOGY ON TEXTURE EVOLUTION OF IF STEEL

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Acta Metallurgica Sinica(English Letters) 2002年第3期15卷 312-316页

作者： J.X. Li, X.H. Liu and G.D. WangState Key Laboratory of Rolling & Automation, Northeastern University, Shenyang 110006, China Manuscript received 16 july 2001 in revised form 6 September 2001 Lab. of Rolling and Automat. Northeastern Univ. Shenyang 110006 China

Two kinds of cold rolling experiments, single cold rolling and double cold rolling, were carried out on one titanium stabilized interstitial free (IF) steel that has been warm rolled at ferrite temperature. The main aim was to investigate the evolution of rolling and annealing textures from the well known behavior observed under single cold rolling condition to the less understood double cold rolling by using orientation distribution function (ODF). In the twice cold rolled samples, the annealing texture comprises only single {111}(110-112) r-fibre texture when it subjected to moderate reduction in the first round of rolling. Accordingly both the once cold rolled sample and the twice cold rolled sample with heavy reduction in the first round of rolling have much complex texture components. They are related to the formation of initial {111} subgrain and the priority growth of stable {111} nucleus.

关键词： double rolling cold rolling reduction deformation texture annealing texture r-value

Kinetics of the Oxidative Dehydrogenation of Isobutane over Cr2O3/La2（CO3）3

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Journal of Energy Chemistry 2002年第Z1期 70-78页

作者： Yanping Sun,Tracey A.Robson,Trevor C.BrownSchool of Biological, Biomedical & Molecular Sciences, University of New England, Armidale, NSW, 2351, Australia [Manuscript received july 23, 2002 revised August 23, 2002]

The oxidative dehydrogenation (ODH) of isobutane over Cr2O3/La2(CO3)3 has been investigated in a low-pressure Knudsen cell reactor, under conditions where the kinetics of the primary reaction steps can be accurately determined. By heating the catalyst at a constant rate from 150-300℃, temperature fluctuations due to non-equilibrium adsorption are minimized. The evolved gas profiles show that ODH to isobutene and water is a primary reaction pathway, while carbon dioxide, which forms from the catalyst during reaction, is the only other product. This CO2 evolution may enhance the activity of the catalyst. Isobutene formation proceeds with the participation of lattice oxygen from the Cr2O3/La2(CO3)3 catalyst. The intrinsic Arrhenius rate constant for the ODH of isobutane isk(s-1) = 1011.5±2.2exp{-((55±5) -ΔHads kJmol-1)/RT}The small pre-exponential factor is expected for a concerted mechanism and for such a catalyst with a small surface area and limited porosity.

关键词： catalytic kinetics oxidative dehydrogenation molecular flow isobutane isobutene Cr2O3/La2(CO3)3

The 3-D non-axisymmetrical Lamb's problem in transversely isotropic saturated poroelastic media

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Science China(Technological Sciences) 2004年第5期47卷 526-549页

作者： HUANG Yi1 & WANG Xiaogang1,2 1. School of Civil Engineering, Xian University of Architecture & Technology, Xian 710055, China 2. Department of Civil Engineering, Qinghai University, Xining 810016, China Correspondence should be addressed to Huang Yi (email: huangyih@***) Received April 15, 2004 revised july 12, 2004 School of Civil Engineering Xi’an University of Architecture & Technology Xi’an China Department of Civil Engineering Qinghai University Xining China

Based on Biots theory on fluid-saturated porous media, the displacement functions are adopted to convert the 3-D Biots wave equations in the cylindrical coordinate for transversely isotropic saturated poroelastic media into two棗one 6-order and one 2-order棗uncoupling differential governing equations. Then, the differential equations are solved by the Fourier expanding and Hankel integral transform method. Integral solutions of soil skeleton displacements and pore pressure as well as the total stresses for poroelastic media are obtained. Furthermore, the systematic study on Lambs problems for the transversely isotropic saturated poroelastic media is performed. Integral solutions for surface radial, vertical and circumferential displacements are obtained in both cases of drained surface and undrained surface under the vertical and horizontal harmonic excitation force. In the end of this paper, the numerical examples are presented. The calculation results indicate that the difference between the model of isotropic saturated poroelastic media and that of transversely isotropic saturated poroelastic media is obvious.

关键词： transversely isotropic saturated poroelastic media, Biot's wave equations, Lamb's problems.

Multi-channel　Associative　Memory　Using　Liquid　Crystal　Photoelectric　Switches

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Chinese Journal of Lasers 1995年第6期B4卷 495-500页

作者： LI Heqiao LIU Wei ZHANG Yimo(Institute of Opto-electronics and Precision Engineering, Tianjin University,Tianjin 300072, China)Received 9 May 1995 revised manuscript received 30 july 1995 Supported by National 863 High Technology Project. Tianjin Univ Tianjin China

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关键词： associative memory liquid crystal photoelectric switch four-channel parallelprocessing

A Study on Numerical Simulation of Core-Shooting Process

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Journal of Materials Science & Technology 2001年第6期17卷 625-628页

作者： Junjiao WU, Yi GUI and Wenzhen LI Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China [Manuscript received july 18, 2000, in revised form August 25, 2000] Dept. of Mech. Eng. Tsinghua Univ. Beijing 100084 China

In order to evaluate the main factors influencing the core-shooting process and to optimize the design of core boxes, the fluid-particle (air-sand) model has been built based on the two-phase flow theory. The fluid phase, air, and the particulate phase, sand granules, have been treated as a continuum. By using this model, it is possible to simulate the flow and compaction behavior of sand particles during the core-shooting process. To benchmark the calculated results, the shooting process has been recorded with a digital high speed camera, and the inlet condition of sand particles has also been achieved by using the camera. The preliminary results have showed that the calculation is in agreement with the testing results.

关键词： A Study on Numerical Simulation of Core-Shooting Process Core Simulation

A Comparative Study of the Atmospheric Layers below First Lifting Condensation Level for Instantaneous Pre-Monsoon Thunderstorm Occurrence at Agartala(23°30′N,91°15′E)and Ranchi(23°14′N,85°14′E)of India

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Advances in Atmospheric Sciences 1997年第1期14卷 94-98页

作者： Sarbari Ghosh and Utpal Kumar De Atmospheric Science Research, Department of Physics, Jadavpur University, Calcutta 700 032, India Received April 8, 1996 revised july 8, 1996

An attempt has been made to investigate the role of vertical wind shear, convective instability and the thermodynamic parameter ( θ es -θ e ) below the first lifting condensation level (FLCL) in the occurrence of instantaneous premonsoon thunderstorm over Agartala (AGT) and Ranchi (RNC) at 12 GMT. Radiosonde data of 1988 have been utilized here. The study has however been confined to 1000 hPa-500 hPa range at most. Here the convectively unstable layers with positive vertical wind shear upto 500 hPa have been termed as ‘Favourable Layers’ (FL) and the level at which an initially stable layer turns out to be convectively unstable for the first time has been termed as ‘Transition Level’ (TL). It is observed that the changes in vertical wind shear are positive at TL at the time of occurrence of thunderstorm (TS) and the corresponding change is negative on fair-weather situation. Moreover, the 90% confidence interval for ( θ es -θ e ) reveals that for AGT the upper layer thermodynamic characteristic is important at the time of occurrence of TS whereas for RNC, the value of ( θ es -θ e ) at the surface is much more effective.

关键词： Convective instability Vertical wind shear Saturated equivalent potential temperature Equivalent potential temperature Confidence interval

Behavior of Zr-Rich Phase in a Cast NiAl-33.5Cr-0.5Zr Alloy during Heat Treatment

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Journal of Materials Science & Technology 2001年第6期17卷 629-632页

作者： Hui LI, sJianting GUQ, Wanhui LAI and Shuhe WANG Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China [Manuscript received july 7, 2000, in revised form October 11, 2000] Inst. of Metal Res. Chinese Acad. of Sci. Shenyang 110016 China

There are many Zr particles in as-cast NiAl-33.5Cr-0.5Zr (at. pct) alloy, which usually exist at the edge of eutectic of beta -NiAl and cx-Cr. After air and furnace cooling solution treatments, far 1400 degreesC, 2 h and 1450 degreesC, 1 h, pure Zr phase remains in the furnace cooling (F.C.) state alloys and Ni2AlZr phase forms in the air cooling (A.C.) state alloys. During solution treatment at 1450 degreesC, bulk and 'fish bone' shape Zr-rich phases form respectively in F.C. and A.C. state alloys. A 'river' shape Ni2AlZr phase forms after 1450 C for 1h F.C. and 850 degreesC for 12 h, F.C.. The alloy has less pure Zr and Ni2AlZr phase after 1400 degreesC with both air and furnace cooling followed by 850 C and 950 C for 12 h, F.C. aging treatments, respectively. Additionally, there is a ternary eutectic of NiAlZr and a phase enriched Zr and Cr forms at the edge of the eutectic of beta -NiAl and alpha -Cr in the alloy treated at 1400 degreesC, 2 h, F.C. and 950 degreesC, 12 h, F.C.

关键词： NiAl Zr Behavior of Zr-Rich Phase in a Cast NiAl-33.5Cr-0.5Zr Alloy during Heat Treatment Cr Cast

Magnetism of Metals, Alloys and of Clusters of Transition Metal Atoms

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Journal of Materials Science & Technology 2001年第6期17卷 581-589页

作者： N.H.March Oxford University, Oxford, England Department of Physics, University of Antwerp (RUCA), Groenenborgerlaan 171, B-2020 Antwerp, Belgium [Manuscript received March 28, 2001, in revised form july 6, 2001] Oxford Univ. Oxford United Kingdom

A condition for local moment formation in metals derived by Stoddart and March (Ann. Phys. NY 1972 64, 174) is first used to discuss the ferromagnetism of body-centred-cubic Fe. A less detailed discussion is also added on Ni and Co. This leads into a treatment of the non- linear response of such 3d ferromagnets to dilute substitutional impurities. Antiferromagnets responding to local changes in the exchange field caused by such impurities are also studied, Mn in Cr being one such system discussed. The paper concludes with a brief summary of clusters of transition metal atoms, with most attention devoted to Cr and to Mn.

关键词： NiCr Alloys and of Clusters of Transition Metal Atoms Magnetism of Metals