Search

Your search keyword '"Wu, Yinong"' showing total 243 results
Start Over Author "Wu, Yinong"
243 results on '"Wu, Yinong"'

1. Inference for a New Signed Integer Valued Autoregressive Model Based on Pegram's Operator

Author

Wu, Yinong and Wang, Dehui

Subjects
Statistics - Applications
Abstract

In the current study, a brand-new SINARS(1) model is proposed for stationary discrete time series defined on $\boldsymbol{Z}$, based on extended binomial distribution and the Pegram's operator. The model effectively characterizes the series of positive and negative integer values generated after differencing some non-stationary time series. The model's attributes are addressed. For the parameter estimation of the model, the conditional maximum likelihood method and Yule-Walker method are taken into consideration. And we prove the asymptotic normality of CML method. By using these two methods, we simulate our model comparing with some relevant ones proposed before. The model can deal with positive or negative autocorrelation data. The analysis of the number of differenced daily new cases in Barbados is done using the suggested model., Comment: 32 pages, 2 figures

Published
2023

29. Organocatalytic Asymmetric Cascade Bicyclization of 2‐Indolylmethanols with α‐(2‐Indolyl) Propargylic Alcohols to Access Chiral Fluorescent Hexacyclic Bisindoles.

Author

Rui, Kanghua, Wu, Yinong, and Lin, Xufeng

Subjects
*FLUORESCENCE yield, *PHOSPHORIC acid, *FLUORESCENCE, *CATALYSIS
Abstract

A cascade regioselective 1,8‐addition/biscyclization of 2‐indolylmethanols with α‐(2‐indolyl) propargylic alcohols has been developed via chiral phosphoric acid (CPA) catalysis. A series of chiral cyclopenta[4,5]pyrrolo biindoles bearing a quaternary stereogenic center were obtained in modest to good yields (72–95%) with high enantioselectivities (82–94%). Additionally, the photophysical properties of these hexacyclic bisindoles are examined, revealing bright fluorescence with high quantum yields. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

30. Bulk Stereoselective Cationic Polymerization of Vinyl Ethers by the Coordination of ZrCl4 with Tunable Spirocyclic Phosphoric Acids.

Author

Wu, Yinong, Liu, Xiong, Zhang, Chengjian, Zhang, Xinghong, and Lin, Xufeng

Subjects
*ADDITION polymerization, *VINYL ethers, *STERIC hindrance, *STEREOCHEMISTRY, *PHOSPHORIC acid
Abstract

Control over stereochemistry in poly(vinyl ether)s leads to a notable change in their physical properties, yet remains a grand challenge. Here, we demonstrate the bulk stereoselective cationic polymerization of vinyl ethers using ZrCl4 coordinated with a spirocyclic phosphoric acid (SPA). The widely variable substituents in SPAs exert a profound impact on the stereochemical and activity outcome of the polymerization: the % m of poly(vinyl ether)s linearly increases with the Hammett substituent constant (σ) of SPAs; the catalytic activity increases with the σ; the large steric hindrance groups lead to decreased polymerization activity. Mechanism studies suggest that the coordination of ZrCl4 with three equivalents of SPAs generates the chiral complex. The complex can abstract chlorine from the initiator/chain end to form the chiral ion pair allowing the selective facial addition of incoming monomers. The catalyst system features characteristics of no solvent, low loads, high tacticity control, high monomer scope, and recyclability. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

36. Numerical Study on the Effect of Various Working Fluids on the Performance of Loop Heat Pipes Based on Two-Dimensional Simulation

Author

Shao, Bo, Lin, Bingyao, Li, Nanxi, Liu, Le, Jiang, Zhenhua, Dong, Deping, and Wu, Yinong

Abstract

The Computational Fluid Dynamics (CFD) method is often used to study the heat and mass transfer mechanism in loop heat pipe (LHP). However, there are few numerical studies have been conducted on the whole loop heat pipe system. In this work, a two-dimensional simulation model of LHP was developed. The wicking process was described by capillary pressure model which was realized by user defined functions(UDFs). The flow, phase change and heat transfer process varies with the change of the working fluid. Therefore, the effects of ammonia, propylene and R245fa on the heat transfer performance of LHP were analyzed in the simulation. According to the simulation results, the LHP charged with ammonia had the best heat transfer performance, followed by the LHP charged with propylene, and the LHP charged with R245fa had the worst heat transfer performance. The simulation results are consistent with the predictions of figures of merits (FOMs). Moreover, In-depth details of the temperature field and vapor-liquid distribution during LHP operation can also be obtained from the model. Experiments of an LHP with the three working fluids were also designed to verify the rationality of the model. The experimental results are in agreement with the simulation results. The two-dimensional LHP simulation model in this paper can realistically simulate the operating process of LHPs with various working fluids.

Published
2025
Full Text
View/download PDF

41. An extension of ℤ-valued time series with Poisson difference innovation via logistic regression.

Author

Liu, Ye, Wu, Yinong, and Wang, Dehui

Abstract

Abstractℤ-valued time series are a type of models that are extremely significant and widely utilized. The Poisson difference distribution is a crucial element in this kind of time series. This paper considers an extension of ℤ-valued autoregressive models with Poisson difference innovation by introducing the random coefficient composed of logistic regression. The estimation process is examined using conditional maximum likelihood and conditional least squares methods. A two-step approach is suggested to further optimize the estimation results. The likelihood ratio test is utilized to ascertain the presence of the random coefficient. Both simulation studies and analysis of real data demonstrate that the suggested model and method demonstrate outstanding performance. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

42. Organocatalytic enantioselective (4+3) cyclization for the synthesis of spiro-fused heterocyclic compounds containing isoindolinone, oxepine and indole moieties.

Author

Rui, Kanghua, Huang, Shaoying, Wu, Yinong, Shen, Hanxiao, and Lin, Xufeng

Subjects
HETEROCYCLIC compounds synthesis, SOLID solutions, RING formation (Chemistry), INDOLE, FLUORESCENCE
Abstract

A refined strategy has been developed to control the regioselective asymmetric (4+3) cyclization of α-(3-isoindolinonyl) propargylic alcohols with 2-indolylmethanols, utilizing chiral phosphoric acid catalysis. This innovative organocatalytic cyclization yields spiro isoindolinone-oxepine-fused indoles featuring a spiro-quaternary stereocenter in high yields and enantioselectivities, facilitated by the solvent of 1,1-dichloro-1-fluoroethane and the additive of hexafluoroisopropanol. Additionally, the photophysical properties of product 3k are examined, revealing bright fluorescence both in the solution and the solid state. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results