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Low-temperature conversion of methane to oxygenates by supported metal catalysts: From nanoparticles to single atoms

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Chinese Journal of Chemical Engineering 2021年第10期34卷 18-29页

作者： Geqian Fang Jian Lin xiaodong wang CAS Key Laboratory of Science and Technology on Applied Catalysis Dalian Institute of Chemical PhysicsChinese Academy of SciencesDalian 116023China University of Chinese Academy of Sciences Beijing 100049China

Direct cost-effective conversion of abundant methane to high value-added oxygenates(methanol,formic acid,acetic acid,etc.)under mild conditions is prospective for optimizing the structure of energy ***,the CAH bond of products is more reactive than that of high thermodynamic stable *** an appropriate approach to eliminate the‘‘seesaw effect"between methane conversion and oxygenate selectivity is *** this review,we briefly summarize the research progress in the past decade on low-temperature direct conversion of methane to oxygenates in gas-solid-liquid phase over various transition metal(Fe,Cu,Rh,Pd,Au Pd,etc.)based nanoparticle or single-atom ***,the prospects of catalyst design and catalysis process are also discussed.

关键词： Methane Oxygenates Supported metal catalysts Nanoparticle Single-atom catalysts

On the Uniqueness of the ADS Spacetime

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Acta Mathematica Sinica,English Series 2005年第4期21卷 917-922页

作者： Xiao Dong wang(xiaodong wang) Wells Hall A 306 Michigan State University East Lansing Michigan 48824 USA

The uniqueness of the ADS spacetime among all static vacuum spacetimes with the same conformal infinity is proved for dimension n≤7. For dimension n 〉 7, the same result is established under the spin assumption.

关键词： Static vacuum ADS spacetime Asymptotically hyperbolic manifold Positive mass theorem

Separation of a C_(3)H_(6)/C_(2)H_(4) mixture using Pebax^(■) 2533/PEG600 blend membranes

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Chinese Journal of Chemical Engineering 2023年第2期54卷 192-198页

作者： Xi Zhang xiaodong wang Wei Huang State Key Laboratory of Clean and Efficient Coal Utilization Taiyuan University of TechnologyTaiyuan 030024China Taiyuan Coal Conversion Technology Engineering Co. LtdTaiyuan 030024China

In industry, ethylene(C_(2)H_(4))/propylene(C_(3)H_(6)) separations are usually performed by a cryogenic process,which is energy intensive. Membrane separation technology is an alternative separation process that saves energy and is efficient. In this study, blend membranes were prepared by doping polyethylene glycol(PEG600) into a poly(ether-block-amide)(Pebax^(■) 2533) matrix and were used to separate the C_(2)H_(4)/C_(3)H_(6) mixture. The PEG 600 and Pebax^(■) 2533 polymers have good compatibility because they share hydrogen bonds. The addition of PEG600 is conducive to the hydrophilicity and the free volume of blend membranes, and it is also conducive to the solubility of C_(2)H_(4) and C_(3)H_(6) in the membranes, which improves the ability of the membranes to separate this gas pair. The Pebax^(■) 2533/PEG600 blend membrane with 15%(mass) PEG600 showed the highest separation performance in our investigated membranes, with a C_(3)H_(6)/C_(2)H_(4) selectivity of 8.9 and a C_(3)H_(6) permeability of 196 barrer(1 barrer = 1.33×10^(14)m^(3)(STP)·m·m^(-2)·s^(-1)·kPa^(-1)) at 238 K and 0.2 MPa, which is higher than that of the Pebax^(■) 2533/NaY-6%(mass) membrane(α_(C_(3)H_(6)/C_(2)H_(4)) =6.5, P_(C_(3)H_(6))=211 barrer) reported in our previous work. It is confirmed that incorporating PEG600 into the Pebax^(■) 2533 matrix to fabricate blend membranes is an efficient strategy for separating light olefins.

关键词： Ethylene/propylene separation Blend membranes Pebax^(■)2533 PEG600

Unsteady aerodynamic characteristics of a horizontal wind turbine under yaw and dynamic yawing

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Acta Mechanica Sinica 2020年第2期36卷 320-338页

作者： Zhaoliang Ye xiaodong wang Ziwen Chen Luyao wang Key Laboratory of Power Station Energy Transfer Conversion and System Ministry of EducationNorth China Electric Power UniversityBeijing 102206China China Huaneng Clean Energy Research Institute Beijing 102209China

Horizontal axis wind turbine(HAWT)often works under yaw due to the stochastic variation of wind *** also can be used as one of control methods for load reduction and wake redirection of ***,the aerodynamic performance under yaw is very important to the design of *** further insight into the highly unsteady characteristics aerodynamics of HAWT under yaw,this paper investigates the unsteady variations of the aerodynamic performance of a small wind turbine under static yawed and yawing process with sliding grid method,as well as the there-dimensional effect on the unsteady characteristics,using unsteady Reynolds-averaged Navier-Stokes(URANS)*** simulation results are validated with experimental data and blade element momentum(BEM)*** comparisons show that the CFD results have better agreement with the experimental data than both BEM *** wind turbine power decreases according to a cosine law with the increase of yaw *** torque under yaw shows lower frequency fluctuations than the non-yawed condition due to velocity component of rotation and the influence of *** yawing causes larger fluctuate than static yaw,and the reason is *** aerodynamic fluctuation becomes more prominent in the retreating side than that in the advancing side for dynamic yawing *** of effective angle of attack and aerodynamic forces along the blade span are *** biggest loading position moves from middle span to outer span with the increase of yaw ***-dimensional stall effect presents load fluctuations at the inner board of blade,and becomes stronger with the increase of yaw angle.

关键词： Wind turbine Three-dimensional stall effect Numerical simulation Dynamic yawing

Preface: Wind turbines: aeromechanics and farm optimization

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Acta Mechanica Sinica 2020年第2期36卷 257-259页

作者： Hui Hu xiaodong wang Department of Aerospace Engineering Iowa State UniversityAmesIA50011-1096USA Department of Energy Power and Mechanical Engineering of North China Electric Power UniversityBeijing102206China

1 Preface With the oil and gas supply security and climate change emerging as high concerns,the need for renewable energy sources to alleviate dependence on hydrocarbons and reduce carbon dioxide(CO2)emissions is becoming increasingly *** energy is one of the cleanest renewable power sources in the world *** *** of Energy(DOE)initiated the Wind Vision study where the costs and benefits of continued investments on wind energy was *** study evaluated an ambitious,yet credible scenario in which wind energy will serve 20%of the nation’s total electric power demand by 2030,and 35%by *** Europe,the wind power generation accounted for 15%of all European electricity demand in the past *** power installation in China has been growing by an annual rate of^10%in recent ***,wind power has become the second largest renewable energy in China,only after hydro-power.

关键词： Wind becoming continued

CRITICAL RATE OF HORIZONTAL WELL FOR WATER CREST

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Journal of Hydrodynamics 1992年第4期4卷 5-10页

作者： Liu, Ciqun wang, xiaodong Research Inst of Porous Flow and Fluid Mechanics Academia Sinica Langfang China

Stationary water crest, for two-dimensional porous flow of horizontal well located at any position in vertical cross-section was studied. Using the potential theory for 2-D flow, the formulae and plots of the critical rate were presented. Calculated results indicate that the critical rates of horizontal well are proportional to oil zone height and horizontal length of well. Comparing with the results of the issued paper, the results in this paper obtain some new conclusions.

关键词： Flow of fluids Porous materials

Nonlinear dynamic singularity analysis of two interconnected synchronous generator system with 1:3 internal resonance and parametric principal resonance

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Applied Mathematics and Mechanics(English Edition) 2015年第8期36卷 985-1004页

作者： xiaodong wang Yushu CHEN Lei HOU School of Astronautics Harbin Institute of Technology

The bifurcation analysis of a simple electric power system involving two synchronous generators connected by a transmission network to an infinite-bus is carried out in this paper. In this system, the infinite-bus voltage are considered to maintain two fluctuations in the amplitude and phase angle. The case of 1：3 internal resonance between the two modes in the presence of parametric principal resonance is considered and examined. The method of multiple scales is used to obtain the bifurcation equations of this system. Then, by employing the singularity method, the transition sets determining different bifurcation patterns of the system are obtained and analyzed, which reveal the effects of the infinite-bus voltage amplitude and phase fluctuations on bifurcation patterns of this system. Finally, the bifurcation patterns are all examined by bifurcation diagrams. The results obtained in this paper will contribute to a better understanding of the complex nonlinear dynamic behaviors in a two-machine infinite-bus （TMIB） power system.

关键词： parametric principal resonance internal resonance singularity method,bifurcation

Feature fusion method for edge detection of color images

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Journal of Systems Engineering and Electronics 2009年第2期20卷 394-399页

作者： Ma Yu Gu xiaodong wang Yuanyuan Dept. of Electronic Engineering Fudan Univ. Shanghai 200433 P. R. China

A novel feature fusion method is proposed for the edge detection of color images. Except for the typical features used in edge detection, the color contrast similarity and the orientation consistency are also selected as the features. The four features are combined together as a parameter to detect the edges of color images. Experimental results show that the method can inhibit noisy edges and facilitate the detection for weak edges. It has a better performance than conventional methods in noisy environments.

关键词： color image processing edge detection feature extraction feature fusion

Comprehensive contour prediction model of work rolls in hot wide strip mill

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Journal of University of Science and Technology Beijing 2007年第3期14卷 240-245页

作者： xiaodong wang Quan Yang Anrui He Renzhong wang National Engineering Research Center for Advanced Rolling Technology University of Science and Technology Beijing Beijing 100083 China

The predictive calculation of comprehensive contour of work rolls in the on-line strip shape control model during hot rolling consists of two important parts of wear contour calculation and thermal contour calculation, which have a direct influence on the ac- curacy of shape control. A statistical wear model and a finite difference thermal contour model of work rolls were described. The comprehensive contour is the equivalence treatment of the sum of grinding, wear, and thermal contours. This comprehensive contour calculation model has been applied successfully in the real on-line strip shape control model. Its high precision has been proved through the large amounts of actual roll profile measurements and theoretical analyses. The hit rates （percent of shape index satisfying re- quirement） of crown and head flatness of the strips rolled, by using the shape control model, which includes the comprehensive contour calculation model, have about 16% and 10% increase respectively, compared to those of strips rolled by using manual operation.

关键词： hot rolled strip strip shape control comprehensive contour wear contour thermal contour