Nonlinear Uzawa methods for solving nonsymmetric saddle point problems

Yanhua Cao,Yiqin Lin,Yimin Wei 한국전산응용수학회 2006 Journal of applied mathematics & informatics Vol.21 No.1-2

Abstract. In [A new nonlinear Uzawa algorithm for generalized saddle point problems, Appl. Math. Comput., 175(2006), 1432-1454], a nonlinear Uzawa algorithm for solving symmetric saddle point problems iteratively, which was defined by two nonlinear approximate inverses, was considered. In this paper, we extend it to the nonsymmetric case. For the nonsymmetric case, its convergence result is deduced. Moreover, we compare the convergence rates of three nonlinear Uzawa methods and show that our method is more ecient than other nonlinear Uzawa methods in some cases. The results of numerical experiments are presented when we apply them to Navier-Stokes equations discretized by mixed finite elements. AMS Mathematics Subject Classification : 65F10; 65F15 xy

Facile preparation of antifouling g-C3N4/Ag3PO4 nanocomposite photocatalytic polyvinylidene fluoride membranes for effective removal of rhodamine B

Yanhua Cui,Lili Yang,Minjia Meng,Qi Zhang,Binrong Li,Yilin Wu,Yunlei Zhang,Jihui Lang,Chunxiang Li 한국화학공학회 2019 Korean Journal of Chemical Engineering Vol.36 No.2

A simplified strategy for facilely fabricating antifouling graphite carbon nitride/silver phosphate (g-C3N4/ Ag3PO4) nanocomposite photocatalytic polyvinylidene fluoride (PVDF) porous membranes was developed for effective removal of rhodamine B (RhB). g-C3N4/Ag3PO4 heterojunction was strongly fixed to the interior of the PVDF membranes via phase inversion method. The membrane structure was analyzed by Fourier transform spectrophotometer (FT-IR). The morphology of the prepared membranes was investigated using scanning electron microscopy (SEM), EDX-mapping and atomic force microscopy (AFM), respectively. All prepared nanocomposite photocatalytic PVDF membranes exhibited a typically porous structure, and g-C3N4/Ag3PO4 nanocomposites were well dispersed inside the membranes. The obtained g-C3N4/Ag3PO4 heterojunction nanoparticle decorated PVDF membrane had a lower water contact angle of 79o and higher porosity of 85% than that of other two control membranes. The nanocomposite photocatalytic PVDF porous membranes had extremely high permeation flux over 1,083 L·m−2·h−1, and could be used for the removal of RhB. The removal efficiency of g-C3N4/Ag3PO4-PVDF membranes towards RhB solution under visible light irradiation reached 97%, higher than that of the pure PVDF membranes (41%) and g-C3N4-PVDF membranes (85%). Remarkably, the flux performance and flux recovery ratio (FRR) of membranes revealed that the g-C3N4/Ag3PO4- PVDF membranes could recover high flux after fouling, which presented better fouling resistance. Furthermore, the fabricated antifouling g-C3N4/Ag3PO4 nanocomposite photocatalytic PVDF porous membranes exhibited excellent recyclability. Therefore, it is expected that g-C3N4/Ag3PO4-PVDF membranes could provide an energy-saving strategy for effective removal of organic dyes wastewater and have a great potential for practical wastewater treatment in the future.

Facile synthesis of imprinted submicroparticles blend polyvinylidene fluoride membranes at ambient temperature for selective adsorption of methyl p-hydroxybenzoate

Yanhua Cui,Minjia Meng,Dongshu Sun,Yan Liu,Jianming Pan,Xiaohui Dai,Yongsheng Yan 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.3

We developed a simple phase inversion technique to prepare molecularly imprinted membrane (MIM) at room temperature for membrane selective adsorption and separation of methyl p-hydroxybenzoate (M4HB). The prepared SMIP-MIM was characterized by SEM, FT-IR, TGA. Compared with non-imprinted membrane (NIM1-5) adsorbent, SMIP-MIM1-5 adsorbent with high specific surface area and showed higher binding capacity, faster kinetic and better selectively adsorption capacity for M4HB. The maximum isotherm adsorption capacity for M4HB of SMIPMIM4 was 3.519mg·g−1, and the experimental data was well fitted to the slips model by multiple analysis. The maximum kinetic adsorption capacity and equilibrium adsorption time for SMIP-MIM4 were 1.335mg·g−1 and 160 min, respectively. The mechanism for dynamic adsorption of M4HB onto SMIP-MIM4 was found to follow pseudo-firstorder model and pseudo-second-order model. Additionally, the permeability separation factor of SMIP-MIM4 for M4HB compared to a structural analogues methyl 2-hydroxybenzoate (M2HB) could reach 2.847. The adsorption capacity of SMIP-MIM4 for M4HB and M2HB was 0.549mg·cm−2 and 1.563mg·cm−2, respectively. The adsorption behavior of M4HB through SMIP-MIM4 followed the retarded permeation mechanism.

On geometry dependent R-curve from size effect law for concrete-like quasibrittle materials

Yanhua Zhao,Jian-mei Chang,Hong-bo Gao 사단법인 한국계산역학회 2015 Computers and Concrete, An International Journal Vol.15 No.4

R-curve based on the size effect law previously developed for geometrically similar specimens (geometry type III) is extended to geometries with variable depth (geometry type I) as well as with variable notch (geometry type II), where the R-curve is defined as the envelope of the family of critical strain energy release rates from specimens of different sizes. The results show that the extended R-curve for type I tends to be the same for different specimen configurations, while it is greatly dependent on specimen geometry in terms of the initial crack length. Furthermore, the predicted load-deflection responses from the suggested R-curve are found to agree well with the testing results on concrete and rock materials. Besides, maximum loads for type II specimen are predicted well from the extended R-curve.

Dynamic behavior of SRC columns with built-in cross-shaped steels subjected to lateral impact

Yanhua Liu,Lei Zeng,Changjun Liu,Jinxu Mo,Buqing Chen 국제구조공학회 2020 Structural Engineering and Mechanics, An Int'l Jou Vol.76 No.4

This paper presents an investigation on the dynamic behavior of SRC columns with built-in cross-shaped steels under impact load. Seven 1/2 scaled SRC specimens were subjected to low-speed impact by a gravity drop hammer test system. Three main parameters, including the lateral impact height, the axial compression ratios and the stirrup spacing, were considered in the response analysis of the specimens. The failure mode, deformation, the absorbed energy of columns, as well as impact loads are discussed. The results are mainly characterized by bending-shear failure, meanwhile specimens can maintain an acceptable integrity. More than 33% of the input impact energy is dissipated, which demonstrates its excellent impact resistance. As the impact height increases, the flexural cracks and shear cracks observed on the surface of specimens were denser and wider. The recorded time-history of impact force and mid-span displacement confirmed the three stages of relative movement between the hammer and the column. Additionally, the displacements had a notable delay compared to the rapid changes observed in the measured impact load. The deflection of the mid-span did not exceed 5.90mm while the impact load reached peak value. The impact resistance of the specimen can be improved by proper design for stirrup ratios and increasing the axial load. However, the cracking and spalling of the concrete cover at the impact point was obvious with the increasing in stiffness.

Updates in the Pathologic Classification of Thyroid Neoplasms: A Review of the World Health Organization Classification

Yanhua Bai,Kennichi Kakudo,정찬권 대한내분비학회 2020 Endocrinology and metabolism Vol.35 No.4

Advances in medical sciences and evidence-based medicine have led to momentous changes in classification and management of thyroid neoplasms. Much progress has been made toward avoiding overdiagnosis and overtreatment of thyroid cancers. The new 2017 World Health Organization (WHO) classification of thyroid neoplasms updated the diagnostic criteria and molecular and genetic characteristics reflecting the biology and behavior of the tumors, and newly introduced the category of borderline malignancy or uncertain malignant potential. Some neoplasms were subclassified, renamed, or redefined as a specific entity. This review introduces changes in the fourth edition WHO classification of thyroid tumors and updates the contemporary diagnosis and classification of thyroid tumors. We also discuss several challenges with the proposal of new diagnostic entities, since they have unique histopathologic and molecular features and clinical relevance.

Research of Road Pricing System Based on P System

Yanhua Zhong,Wei Wei,Zhiyong Liu 보안공학연구지원센터 2015 International Journal of u- and e- Service, Scienc Vol.8 No.6

For urban traffic congestion problem, a communication P systems using parallel computing principles congested road-use pricing model, considering congestion charges in the case, the establishment of travelers travel decision algorithm, travelers dynamic evolution in traffic P system, External charging parameters can be adjusted to influence traveler decisions, thereby affecting the whole system evolution. The congestion pricing model based on P system (CPS_ DTAM) of the simulation experiment shows that the algorithm is feasible. This model and particle swarm optimization congestion pricing model (PSO_ DTAM) were compared based on the same parameters; the results show that this pricing model taking into accounts the dynamic decision travelers more in line with the real situation.

Joint Optimization Method Combining Genetic Algorithm and Numerical Algorithm Based on MATLAB

Yanhua Guo,Feifei Liu,Ning Zhang,Tao Wang 보안공학연구지원센터 2016 International Journal of Hybrid Information Techno Vol.9 No.11

A two-bar plane truss is builtin MATLAB based on mathematical model. Then the authors use genetic algorithm toolbox to solve this problem. The parametric truss model is set up in the finite element analysis software ANSYS. It is analyzed by first-order algorithm. The comparison of two kinds results show the pure genetic algorithm doesn’t always have an advantage over other algorithms. In the end, a joint optimization method is put forward on the basis of genetic algorithm. It combines genetic algorithm based on MATLAB toolbox and numerical algorithm based on quasi-Newton method. This method is illustrated by the numerical example of the two-bar plane truss. The results show this joint optimization method can get the global optimal solution of this problem every time.

Human Reliability Analysis for Digitized Nuclear Power Plants: Case Study on the LingAo II Nuclear Power Plant

Yanhua Zou,Li Zhang,Licao Dai,Pengcheng Li,Tao Qing 한국원자력학회 2017 Nuclear Engineering and Technology Vol.49 No.2

The main control room (MCR) in advanced nuclear power plants (NPPs) has changed from analog to digital control system (DCS). Operation and control have become more automated, centralized, and accurate due to the digitalization of NPPs, which has improved the efficiency and security of the system. New issues associated with human reliability inevitably arise due to the adoption of new accident procedures and digitalization of main control rooms in NPPs. The LingAo II NPP is the first digital NPP in China to apply the stateoriented procedure. In order to address issues related to human reliability analysis for DCS and DCS + state-oriented procedure, the Hunan Institute of Technology conducted a research project based on a cooperative agreement with the LingDong Nuclear Power Co. Ltd. This paper is a brief introduction to the project.

Image Restoration Based on Quadtree Data Structures

Yanhua Ma 보안공학연구지원센터 2015 International Journal of Signal Processing, Image Vol.8 No.8

This paper investigates the problem of image restoration when the image is corrupted by Pepper-and-salt noise and proposes a new restoration algorithm based on quadtree data structures. The crucial parts of the algorithm are picking noise and fuzzy estimation, so that unlike some other usual denoising methods, it avoids blurring and averaging edges and non-noise pixels. This paper describes, analyzes and compares several methods and results of removing noise from image. Experimental results indicate that the new algorithm proposed by this paper is superior.