Search

Your search keyword '"Wu, Youcai"' showing total 31 results
Start Over Author "Wu, Youcai"
31 results on '"Wu, Youcai"'

12. Chiral Phosphoric Acid Catalyzed (4+1) Annulation of 3‐Diazooxindoles/4‐Diazooxisoquinolines with para ‐Quinone Methides to Access Chiral Spiro[dihydrobenzofuran‐2,3′‐oxindoles/2,4′‐oxisoquinolines]

Author

Nan-Wei Wan, Wenyong Han, Yan Long, Wei-Cheng Yuan, Wu Youcai, Yongzheng Chen, and Baodong Cui

Subjects
chemistry.chemical_compound, Annulation, Metal free, Chemistry, Organocatalysis, Para-quinone, Organic chemistry, General Chemistry, Phosphoric acid, Catalysis
Published
2021

13. Palladium-catalyzed asymmetric allylic alkylation of 3-aminooxindoles to access chiral homoallylic aminooxindoles

Author

Yongzheng Chen, Chao Zhang, Nan-Wei Wan, Wenyong Han, Wu Youcai, Baodong Cui, and Lian Li

Subjects
Tsuji–Trost reaction, Chemistry, Organic Chemistry, Enantioselective synthesis, chemistry.chemical_element, Physical and Theoretical Chemistry, Biochemistry, Combinatorial chemistry, Palladium, Catalysis
Abstract

An organometal catalytic conversion of 3-aminooxindoles for the diastereo- and enantioselective synthesis of homoallylic aminooxindoles has been described. The asymmetric allylic alkylation of 3-aminooxindoles with allyl carboxylates proceeded smoothly to afford a series of chiral 3-allyl-3-aminooxindoles. This work offers an alternative route to build these scaffolds. The application of this protocol is also highlighted by a significant conversion of products to the potential applicable spiro[indoline-3,2'-pyrrolidin]-2-one derivatives.

Published
2021

18. Outline of Classical and Current Approaches to the Research of Morphology of Selected Mineral Crystals in China (CD-ROM)

Author

Zhao Shan-rong, WU Youcai, Lei Xin-rong, and Wang Wen-kui

Subjects
Wolframite, Mineral, Morphology (linguistics), Bertrandite, Diamond, Mineralogy, chemistry.chemical_element, Geology, Hsianghualite, engineering.material, Uranium, Crystal morphology, chemistry, engineering
Abstract

The research on morphology of mineral crystals in China includes classical goniometry of 100 minerals such as hsianghualite, orthobrannerite, jamesonite and bertrandite and surface microtopography of 20 minerals such as wolframite and diamond, among which 5 new minerals and 34 uranium minerals were discovered and measured by Chinese mineralogists. These have enriched mineralogy and crystal morphology and strengthened the study of information of morphological genesis.

Published
2010

27. Strain gradient stabilization with dual stress points for the meshfree nodal integration method in inelastic analyses.

Author

Wu, Cheng‐Tang, Chi, Sheng‐Wei, Koishi, Masataka, and Wu, Youcai

Subjects
GALERKIN methods, LAGRANGIAN functions, MESHFREE methods, STRAINS & stresses (Mechanics), KERNEL (Mathematics), ELASTOPLASTICITY
Abstract

A nonlinear nodal-integrated meshfree Galerkin formulation based on recently proposed strain gradient stabilization (SGS) method is developed for large deformation analysis of elastoplastic solids. The SGS is derived from a decomposed smoothed displacement field and is introduced to the standard variational formulation through the penalty method for the inelastic analysis. The associated strain gradient matrix is assembled by a B-bar method for the volumetric locking control in elastoplastic materials. Each meshfree node contains two coinciding integration points for the integration of weak form by the direct nodal integration scheme. As a result, a nonlinear stabilized nodal integration method with dual nodal stress points is formulated, which is free from stabilization control parameters and integration cells for meshfree computation. In the context of extreme large deformation analysis, an adaptive anisotropic Lagrangian kernel approach is introduced to the nonlinear SGS formulation. The resultant Lagrangian formulation is constantly updated over a period of time on the new reference configuration to maintain the well-defined displacement gradients as well as strain gradients in the Lagrangian computation. Several numerical benchmarks are studied to demonstrate the effectiveness and accuracy of the proposed method in large deformation inelastic analyses. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Published
2016
Full Text
View/download PDF

31. Stability in Lagrangian and Semi-Lagrangian Reproducing Kernel Discretizations Using Nodal Integration in Nonlinear Solid Mechanics.

Author

Oñate, E., Leitão, V. M. A., Alves, C. J. S., Armando Duarte, C., Chen, Jiun-Shyan, and Wu, Youcai

Abstract

Stability analyses of Lagrangian and Semi-Lagrangian Reproducing Kernel (RK) approximations for nonlinear solid mechanics are performed. It is shown that the semi-Lagrangian RK discretization yields a convective term resulting from the non-conservative coverage of material points under the kernel support. The von Neumann stability analysis shows that the discrete equations of both Lagrangian and semi-Lagrangian discretizations are stable when they are integrated using stabilized conforming nodal integration. On the other hand, integrating the semi-Lagrangian discretization with a direct nodal integration yields an unstable discrete system which resembles the tensile instability in SPH. Under the framework of semi-Lagrangian discretization, it is shown that the inclusion of convective term yields a more stable discrete system compared to the semi-Lagrangian discretization without convective term as was the case in SPH. [ABSTRACT FROM AUTHOR]

Published
2007
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results