Surface curvature-confined strategy to ultrasmall nickel-molybdenum sulfide nanoflakes for highly efficient deep hydrodesulfurization

Size-controlled synthesis of two-dimensional(2D)catalysts with low stacking numbers and small nanoflake lengths is crucial for promoting the catalytic performance in diverse heterogeneous catalysis.Herein,we report a facile and general“surface curvature-confined synthesis”strategy to modulate the slab lengths and stacking numbers of 2D transition metal sulfides by controlling the strain induced by different surface curvature of supports.An efficient NiMo sulfide with shorter slab length(average 3.71 nm),less stacking number(1–2 layers)and more edge active sites is synthesized onto ZSM-5 zeolites with the average size of 100 nm,which shows superior kHDS value of dibenzothiophene(14.05×10^−7 mol/(g·s)),enhanced stability up to 80 h,and high direct desulfurization selectivity(>95%).This design concept is also proved to be generally applicable to modulate the slab lengths and stacking numbers of other 2D catalysts such as MoS2 and WS2 nanoflakes,which shows great potentials for developing more ultrasmall 2D catalysts with controlled sizes and excellent catalytic activities.

RIGIDITY OF COMPACT SURFACES IN HOMOGENEOUS 3-MANIFOLDS WITH CONSTANT MEAN CURVATURE

In this paper, we establish a rigidity theorem for compact constant mean curva- ture surfaces of the Berger sphere in terms of the surfaces＇ geometric invariants. This extends the previous similar result on compact minimal surfaces of the Berger sphere.

Numerical Optimization of Pressure Force from Multiple Jets Impinging on a Moving Curved Surface for Industrial Drying Machines

Jet force on the surface is typical for impinging jets towards the surface and it is very important in drying applications for force-sensitive surfaces. The designer should optimize the design parameters of industrial drying equipment to achieve minimum pressure force between multiple jets and a moving curved surface. SST k-ω turbulence model is used to simulate a real geometry for industrial drying applications. The SST k-ω turbulence model succeeded with reasonable accuracy in reproducing the experimental results. The jet to surface distance, jet to jet spacing, jet inlet velocity, jet angle, and surface velocity are chosen as the design parameters. For the optimization of the impinging round jet, the pressure force coefficient on the moving curved surface is set as the objective function to be minimized. The SHERPA search algorithm is used to search for the optimal point from the weighted sum of all objectives method. One correlation is developed and validated for the pressure force coefficient. It is found that the pressure force coefficient is highly dependent on the nozzle to surface distance and jet angle but relatively insensitive to jet inlet velocity, jet to jet spacing, and surface velocity. The minimum pressure force coefficient correlates with a high value of nozzle to surface distance (tenfold diameter in this analysis) and a low value of the jet angle (40? in this analysis). The agreement in the prediction of the pressure force coefficient between the numerical simulation and developed correlation is found to be reasonable and all the data points deviate from the correlation approximately 8% on average.

Isotropic compression behavior of granular assembly with non-spherical particles by X-ray micro-computed tomography and discrete element modeling

The particle morphological properties,such as sphericity,concavity and convexity,of a granular assembly significantly affect its macroscopic and microscopic compressive behaviors under isotropic loading condition.However,limited studies on investigating the microscopic behavior of the granular assembly with real particle shapes under isotropic compression were reported.In this study,X-ray computed tomography(mCT)and discrete element modeling(DEM)were utilized to investigate isotropic compression behavior of the granular assembly with regard to the particle morphological properties,such as particle sphericity,concavity and interparticle frictions.The mCT was first used to extract the particle morphological parameters and then the DEM was utilized to numerically investigate the influences of the particle morphological properties on the isotropic compression behavior.The image reconstruction from mCT images indicated that the presented particle quantification algorithm was robust,and the presented microscopic analysis via the DEM simulation demonstrated that the particle surface concavity significantly affected the isotropic compression behavior.The observations of the particle connectivity and local void ratio distribution also provided insights into the granular assembly under isotropic compression.Results found that the particle concavity and interparticle friction influenced the most of the isotropic compression behavior of the granular assemblies.

曲面上的一些整体定理

A、Svec[1]用积分公式,极大值原理和广义解析函数三种方法研究了Weingarten曲面,主要是研究球面的特征。本文用广义解析函方法,得到一些其它曲面的特征。定理2得到旋转曲面,定理3—4得到常中曲率曲面。

Classification of Lagrangian Surfaces of Curvatureε in Non-fiat Lorentzian Complex Space Form ■_1~2(4ε)

It is well known that a totally geodesic Lagrangian surface in a Lorentzian complex space form M12（4ε） of constant holomorphic sectional curvature 4s is of constant curvature 6. A natural question is ＂Besides totally geodesic ones how many Lagrangian surfaces of constant curvature εin M12（46） are there？＂ In an earlier paper an answer to this question was obtained for the case e = 0 by Chen and Fastenakels. In this paper we provide the answer to this question for the case ε≠0. Our main result states that there exist thirty-five families of Lagrangian surfaces of curvature ε in M12（4ε） with ε ≠ 0. Conversely, every Lagrangian surface of curvature ε≠0 in M12（4ε） is locally congruent to one of the Lagrangian surfaces given by the thirty-five families.

飞机复杂双曲率整体壁板压弯成形路径设计与优化(英文)

In order to find out the optimal press bend forming path in fabricating aircraft integral panels, this article proposes a new method on the basis of the authors＇ previous work. It is composed of the finite element method （FEM） equivalent model, the surface curvature analysis, the artificial neural network response surface and the genetic algorithm. The method begins with analyzing the objective＇s shape curvature to determine the bending position. Then it optimizes the punch travel at each bending position by the following steps： （1） Establish a multi-step press bend forming FEM equivalent model, with which the FEM ex- periments designed with the Taguchi method are performed. （2） Construct a back-propagation （BP） neural network response surface with the data from the FEM experiments. （3） Use the genetic algorithm to optimize the neural network response surface as the objective function. Finally, this method is verified by press bending a complicated double-curvature grid-type stiffened panel and bears out its effectiveness and intrinsic worth in designing the press bend forming path.