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198 results on '"Liu, Qianru"'

4. Phase transitions driven by Lévy noise and Gaussian white noise in an asymmetric tristable system(Lévy噪声和高斯白噪声驱动的非对称三稳系统的相转移问题研究)

Author

刘倩茹(LIU Qianru) and 郭永峰(GUO Yongfeng)

Subjects
asymmetric tristable system(非对称三稳系统), lévy noise(lévy噪声), stationary probability density noise(稳态概率密度), noise induced phase transition(噪声诱导相变), Electronic computers. Computer science, QA75.5-76.95, Physics, QC1-999
Abstract

In this paper, the phenomenon of phase transition is studied in an asymmetric tristable model driven by Lévy noise and Gaussian white noise. First, the fourth-order Runge-Kutta algorithm is used to simulate the stationary probability density of the system. Then we observe the shape of the stationary probability density curve by adjusting the system parameters and noise parameters. It has been found that asymmetric parameter, additive noise intensity, multiplicative noise intensity, the stability index, and the skewness parameter can all induce phase transition. Moreover, the influence of additive noise intensity and multiplicative noise intensity on the number and height of stationary probability density peaks is opposite. We also found that under the same asymmetric parameters, the influence of positive and negative skewness parameters on the stationary probability density is different.(讨论了非对称三稳系统在Lévy噪声和高斯白噪声共同驱动下的相转移问题。采用四阶Runge-Kutta算法，计算了系统的稳态概率密度函数，通过改变系统参数和噪声参数观察其稳态概率密度函数曲线形态的变化情况。研究发现，非对称参数、加性噪声强度、乘性噪声强度、稳定性指标、偏斜参数均可诱导系统相转移，当分别改变加性噪声强度和乘性噪声强度时，概率密度函数的峰数与高度的变化情况相反。此外，在相同的非对称参数下，随着偏斜参数正负取值的变化，概率密度曲线图中峰的结构亦呈现不同的现象。)

Published
2024
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5. Parameter Choices for Sparse Regularization with the $\ell_1$ Norm

Author

Liu, Qianru, Wang, Rui, Xu, Yuesheng, and Yan, Mingsong

Subjects
Mathematics - Numerical Analysis, Mathematics - Optimization and Control
Abstract

We consider a regularization problem whose objective function consists of a convex fidelity term and a regularization term determined by the $\ell_1$ norm composed with a linear transform. Empirical results show that the regularization with the $\ell_1$ norm can promote sparsity of a regularized solution. It is the goal of this paper to understand theoretically the effect of the regularization parameter on the sparsity of the regularized solutions. We establish a characterization of the sparsity under the transform matrix of the solution. When the fidelity term has a special structure and the transform matrix coincides with a identity matrix, the resulting characterization can be taken as a regularization parameter choice strategy with which the regularization problem has a solution having a sparsity of a certain level. We study choices of the regularization parameter so that the regularization term alleviates the ill-posedness and promote sparsity of the resulting regularized solution. Numerical experiments demonstrate that choices of the regularization parameters can balance the sparsity of the solutions of the regularization problem and its approximation to the minimizer of the fidelity function.

Published
2022
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16. Toxic epidermal necrolysis complicated with primary cutaneous aspergillosis: A report of four cases.

Author

Liu, Qianru, Su, Huilin, Hong, Chunli, Han, Jiande, Chen, Xiaohong, and Tang, Xuhua

Abstract

Primary cutaneous aspergillosis (PCA) is a rare opportunistic infection caused by Aspergillus that can be life‐threatening. PCA is mainly reported in immunocompromised hosts such as patients with AIDS, those with hematologic malignancy, or infants with occlusive dressings. However, no study has previously reported PCA associated with toxic epidermal necrolysis (TEN). This study reports four cases of TEN complicated with PCA, presenting with discrete gray or black spots over newly formed epithelia. Risk factors of PCA in patients with TEN include host factors, iatrogenic factors, indoor environment, and wound care. Two of the four cases eventually died, highlighting the importance of further exploring PCA in patients with TEN. [ABSTRACT FROM AUTHOR]

Published
2024
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25. Methanotroph biotransformation for nutrient recovery:a review of current strategies and future opportunities

Author

Zheng, Xin, Liu, Qianru, Khademi, Sahar, Khoshnevisan, Benyamin, Xu, Mingyi, Zhang, Yifeng, Lou, Yu, Liu, Hongbin, Duan, Na, Zheng, Xin, Liu, Qianru, Khademi, Sahar, Khoshnevisan, Benyamin, Xu, Mingyi, Zhang, Yifeng, Lou, Yu, Liu, Hongbin, and Duan, Na

Abstract

The escalating global demand for protein and the imperative to meet sustainable development goals have driven the emergence of biotransformation platforms, with methanotrophs showing significant potential in this field. In this paper, the metabolism, nutritional requirements, cultivation strategies, and bioreactors of methanotrophs are reviewed. Integrating upstream and downstream technologies is also advocated to advance the development of methanotroph biotransformation platforms toward a circular economy model. The advancements in utilizing biogas as a viable carbon source and wastewater as a nitrogen source are discussed, emphasizing the need for detailed quality control and safety assessments to ensure the suitability of single-cell protein as animal feed. In general, by integrating advanced nutrient recovery technologies to define new process routes, methanotroph biotransformation platforms can bring better environmental benefits by reducing carbon emissions and saving resources. Shifting to renewable energy is crucial for achieving environmental sustainability. By using renewable energy to power microbial fermentation, biomass dehydration, and waste recycling, the platform can offset high energy consumption and attain significant market competitiveness with traditional protein sources.

Published
2024

35. Enantioselective Palladium(II)‐Catalyzed Desymmetrizative Coupling of 7‐Azabenzonorbornadienes with Alkynylanilines.

Author

Meng, Junjie, He, Hui, Liu, Qianru, Xu, Hanhong, Huang, Huicai, Ni, Shao‐Fei, and Li, Zhaodong

Subjects
PALLADIUM, COVALENT bonds, HOMOGENEOUS catalysis, ASYMMETRIC synthesis, PLATINUM
Abstract

A PdII‐catalyzed, domino enantioselective desymmetrizative coupling of 7‐azabenzonorbornadienes with alkynylanilines is disclosed herein. This operationally simple transformation generates three covalent bonds and two contiguous stereocenters with excellent enantio‐ and diastereo‐selectivity. The resulting functionalized indole‐dihydronaphthalene‐amine conjugates served as an appealing platform to streamline the diversity‐oriented synthesis (DOS) of other valuable enantioenriched compounds. DFT calculations revealed that the two stabilizing non‐covalent interactions contributed to the observed enantioselectivity. [ABSTRACT FROM AUTHOR]

Published
2024
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