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A New Well-Balanced Finite Volume CWENO Scheme for Shallow Water Equations over Bottom Topography

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Advances in Applied Mathematics and Mechanics 2023年第6期15卷 1515-1539页

作者： Wei Guo Ziming Chen Shouguo Qian Gang Li Qiang Niu School of Mathematics and Statistics Qingdao UniversityQingdaoShandong 266071China Department of Applied Mathematics Xi’an Jiaotong–Liverpool UniversitySuzhouJiangsu 215123China

In this article,we develop a new well-balanced finite volume central weighted essentially non-oscillatory(CWENO)scheme for one-and two-dimensional shallow water equations over uneven bottom.The well-balanced property is of paramount importance in practical applications,where many studied phenomena can be regarded as small perturbations to the steady state.To achieve the well-balanced property,we construct numerical fluxes by means of a decomposition algorithm based on a novel equilibrium preserving reconstruction procedure and we avoid applying the traditional hydrostatic reconstruction technique accordingly.This decomposition algorithm also helps us realize a simple source term discretization.Both rigorous theoretical analysis and extensive numerical examples all verify that the proposed scheme maintains the well-balanced property exactly.Furthermore,extensive numerical results strongly suggest that the resulting scheme can accurately capture small perturbations to the steady state and keep the genuine high-order accuracy for smooth solutions at the same time.

关键词： Shallow water equations source term CWENO scheme decomposition algorithm well-balanced property

Hydration Characteristics and Microstructure of Alkali-Activated Slag Concrete: A Review

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Engineering 2023年第1期20卷 162-179页

作者： qiang Fu Mengxin Bu Zhaorui Zhang Wenrui Xu qiang Yuan Ditao niu School of Civil Engineering Xi’an University of Architecture and TechnologyXi’an 710055China State Key Laboratory of Green Building in Western China Xi’an University of Architecture and TechnologyXi’an 710055China School of Civil Engineering Central South UniversityChangsha 410075China

Alkali-activated slag concrete (AASC) is a new green building material. The amount of CO_(2) produced by AASC is 1/5th of that produced by ordinary Portland cement concrete (OPCC). In addition, AASC promotes the reuse of slag and other wastes and saves resources. Furthermore, the scope of use of slag has been expanded. The progress of the research on the hydration characteristics, microstructure, interfacial transition zone, and pore structure of AASC based on the relevant literatures was analyzed and summarized in this study. The influences of the slag composition, the type and dosage of the alkali activator, and the curing conditions on the hydration characteristics and the microstructure of the AASC were discussed. Relatively few research results on the microstructure of AASC are available, and the relevant conclusions are not completely consistent. Moreover, there are many constraints on the development of AASC (e.g., complex composition of raw materials of slag, large shrinkage deformation, and low fluidity). Therefore, further research is required.

关键词： Alkali-activated slag concrete Hydration characteristics Pore structure Inter facial transiti on zone Micr ostructure

Molecular mechanisms underlying cell-in-cell formation:core machineries and beyond

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Journal of Molecular Cell Biology 2021年第5期13卷 329-334页

作者： Zubiao niu Meifang He qiang Sun Laboratory of Cell Engineering Institute of BiotechnologyBeijing 100071China Laboratory of General Surgery The First Affiliated HospitalSun Yat-sen UniversityGuangzhou 510080China Research Unit of Cell Death Mechanism Chinese Academy of Medical Sciences2020RU009Beijing 100071China

Although cell-in-cell structures(CICs),with one or more cells present inside another cell,had been identified for a century,it was not until recent years that scientists started to uncover their pivotal roles in multiple biological processes,primarily via mediating the death of internalized cells.Meanwhile,considerable progresses were made on deciphering the mechanisms underlying their formation based on different models.Entosis was one of the best investigated CIC models,where cell internalization was coordinately driven by adherens junction and contractile ac-tomyosin,the two spatially polarized and complementary core elements that were coupled by mechanical ring,a recently identified core element.Meanwhile,an expanding group of factors were found capable of regulating CIC formation by targeting these core elements.The elucidation of the molecular machinery controlling CIC formation enables synthetic engineering of cells used for clinical and research purposes。

关键词： mechanisms beyond complementary

Co-delivery of nigericin and decitabine using hexahistidine-metal nanocarriers for pyroptosis-induced immunotherapeutics

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Acta Pharmaceutica Sinica B 2022年第12期12卷 4458-4471页

作者： Qiang Niu Yu Liu Yujing Zheng Ziwei Tang Yuna Qian Ruogu Qi Jianliang Shen Ping Zhao School of Chemistry and Chemical Engineering Guangdong Pharmaceutical UniversityGuangzhou 510006China State Key Laboratory of Ophthalmology Optometry and Vision ScienceSchool of Ophthalmology and OptometrySchool of Biomedical EngineeringWenzhou Medical UniversityWenzhou 325027China Wenzhou Institute University of Chinese Academy of SciencesWenzhou 325001China School of Medicine&Holistic Integrative Medicine Nanjing University of Chinese MedicineNanjing 210023China

Pyroptosis provides a new window for relieving the tumor immunosuppressive microenvironment(TIM)and promoting systemic immune responses for tumor treatments.However,gasdermin D(GSDMD),a key protein in the pyroptosis process mediated by caspase-1,is low expressed in the majority of tumor cells and small-molecule inhibitors of DNA methylation suffer from nonspecific or single-function defects.To address these issues,hexahistidine(His6)-metal assembly(HmA)was employed as the drug delivery vector to load nigericin(Nig)and decitabine(DAC)affording a dual-drug delivery system(Nig^(+)DAC)@HmA.The(Nig^(+)DAC)@HmA nanoparticles are efficiently internalized by cells through endocytosis,easily escape from the lysosome,and are highly distributed in the tumor sites.DAC up-regulates the expression of GSDMD which is then cleaved by the nucleotide-binding oligomerization domain-like receptor protein 3(NLRP3)inflammasome and caspase-1 protein activated by Nig.Effective cancer cell pyroptosis is thus achieved and induces a significant systemic antitumor immunity for impressive tumor suppression with negligible side effects in vivo.Our results suggest that such an easy-to-manipulate self-assembled nano-system(Nig^(+)DAC)@HmA provides a new anticancer path by enhancing pyroptosis through reinforced inflammation.

关键词： Self-assembled nanoparticle Pyroptosis NLRP3 GSDMD Inflammation IL-8 Immunotherapy responses Solid tumor

Multi-Sensor Estimation for Unreliable Wireless Networks with Contention-Based Protocols

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Journal of Computer Science & Technology 2018年第5期33卷 1072-1085页

作者： Shou-Wan Gao Peng-Peng Chen Xu Yang Qiang Niu Key Laboratory of Gas and Fire Control for Coal Mines China University of Mining and Technology Xuzhou 221116 China School of Computer Science and Technology China University of Mining and Technology Xuzhou 221116 China

The state estimation plays an irreplaceable role in many real applications since it lays the foundation for decision-making and control. This paper studies the multi-sensor estimation problem for a contention-based unreliable wireless network. At each time step, no more than one sensor can communicate with the base station due to the potential contention and collision. In addition, data packets may be lost during transmission since wireless channels are unreliable. A novel packet arrival model is proposed which simultaneously takes into account the above two issues. Two scenarios of wireless sensor networks （WSNs） are considered： the sensors transmit the raw measurements directly and the sensors send the local estimation instead. Based on the obtained packet arrival model, necessary and sufficient stability conditions of the estimation at the base station side are provided for both network scenarios. In particular, all offered stability conditions are expressed by simple inequalities in terms of the packet arrival rates and the spectral radius of the system matrix. Their relationships with existing related results are also discussed. Finally, the proposed results are demonstrated by simulation examples and an environment monitoring prototype system.

关键词： wireless sensor network packet loss state estimation contention-based protocol

AHigh-OrderWell-Balanced Discontinuous Galerkin Method Based on the Hydrostatic Reconstruction for the Ripa Model

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Advances in Applied Mathematics and Mechanics 2020年第6期12卷 1416-1437页

作者： Jiaojiao Li Gang Li Shouguo Qian Jinmei Gao Qiang Niu School of Mathematics and Statistics Qingdao UniversityQingdaoShandong 266071China Department of Mathematical Sciences Xi’an Jiaotong-Liverpool UniversitySuzhouJiangsu 215123China

In this work,we present a high-order discontinuous Galerkin method for the shallow water equations incorporating horizontal temperature gradients(also known as the Ripa model),which exactly maintains the lake at rest steady state.Herein,we propose original numerical fluxes defined on the basis of the hydrostatic reconstruction idea and a simple source term approximation.This novel approach allows us to achieve the well-balancing of the discontinuous Galerkin method without complication.Moreover,the proposed method retains genuinely high-order accuracy for smooth solutions and it shows good resolution for discontinuous solutions at the same time.Rigorous numerical analysis as well as extensive numerical results all verify the good performances of the proposed method.

关键词： Ripa model lake at rest steady state source term discontinuous Galerkin method,well-balancing property hydrostatic reconstruction.

An Investigation of Restarted GMRES Method by Using Flexible Starting Vectors

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Numerical Mathematics(Theory,Methods and Applications) 2010年第3期3卷 338-351页

作者： Qiang Niu Lin-Zhang LU BNU-HKBU United International College Zhuhai 519085 China. School of Mathematics and Computer Science Guizhou Normal University Guiyang 550001 China. School of Mathematical Sciences Xiamen University Xiamen 361005 China.

We discuss a variant of restarted GMRES method that allows changes of the restarting vector at each cycle of iterations.The merit of the variant is that previously generated information can be utilized to select a new starting vector,such that the occurrence of stagnation be mitigated or the convergence be accelerated.The more appealing utilization of the new method is in conjunction with a harmonic Ritz vector as the starting vector,which is discussed in detail.Numerical experiments are carried out to demonstrate that the proposed procedure can effectively mitigate the occurrence of stagnation due to the presence of small eigenvalues in modulus.

关键词： GMRES方法载体 Ritz向量柔性迭代周期数值实验吸引力特征值

A RELAXED HSS PRECONDITIONER FOR SADDLE POINT PROBLEMS FROM MESHFREE DISCRETIZATION＊

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Journal of Computational Mathematics 2013年第4期31卷 398-421页

作者： Yang Cao Linquan Yao Meiqun Jiang Qiang Niu School of Transportation Nantong University Nantong 226019 China School of Urban Rail Transportation Soochow University Suzhou 215006 China School of Mathematical Sciences Soochow University Suzhou 215006 China Mathematics and Physics Center Xi 'an Jiaotong-L iverpool University Suzhou 215123 China

In this paper, a relaxed Hermitian and skew-Hermitian splitting （RHSS） preconditioner is proposed for saddle point problems from the element-free Galerkin （EFG） discretization method. The EFG method is one of the most widely used meshfree methods for solving partial differential equations. The RHSS preconditioner is constructed much closer to the coefficient matrix than the well-known HSS preconditioner, resulting in a RHSS fixed-point iteration. Convergence of the RHSS iteration is analyzed and an optimal parameter, which minimizes the spectral radius of the iteration matrix is described. Using the RHSS pre- conditioner to accelerate the convergence of some Krylov subspace methods （like GMRES） is also studied. Theoretical analyses show that the eigenvalues of the RHSS precondi- tioned matrix are real and located in a positive interval. Eigenvector distribution and an upper bound of the degree of the minimal polynomial of the preconditioned matrix are obtained. A practical parameter is suggested in implementing the RHSS preconditioner. Finally, some numerical experiments are illustrated to show the effectiveness of the new preconditioner.

关键词： Meshfree method Element-free Galerkin method Saddle point problems Pre-conditioning HSS preconditioner Krylov subspace method.

The virological impacts of SARS-CoV-2 D614G mutation

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Journal of Molecular Cell Biology 2021年第10期13卷 712-720页

作者： Chenxi Wang You Zheng Zubiao niu Xiaoyi jiang qiang Sun Laboratory of Cell Engineering Institute of BiotechnologyResearch Unit of Cell Death MechanismChinese Academy of Medical ScienceBeijing 100071China

The coronavirus diseases 2019(COVID-19)caused by the infection of severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)emerged in December 2019 has caused more than 140 million infections worldwide by the end of April 2021.As an enveloped single-stranded positive-sense RNA virus,SARS-CoV-2 underwent constant evolution that produced novel variants carrying mutation conferring fitness advantages.The current prevalent D614G variant,with glycine substituted for aspartic acid at position 614 in the spike glycoprotein,is one of such variants that became the main circulating strain worldwide in a short period of time.Over the past year,intensive studies from all over the world had defined the epidemiological characteristics of this highly contagious variant and revealed the underlying mechanisms.This review aims at presenting an overall picture of the impacts of D614G mutation on virus transmission,elucidating the underlying mechanisms of D614G in virus pathogenicity,and providing insights into the development of effective therapeutics.

关键词： SARS-CoV-2 COVID-19 D614G infectivity virus mutation