A numerical study on ice failure process and ice-ship interactions by Smoothed Particle Hydrodynamics

Zhang, Ningbo,Zheng, Xing,Ma, Qingwei,Hu, Zhenhong The Society of Naval Architects of Korea 2019 International Journal of Naval Architecture and Oc Vol.11 No.2

In this paper, a Smoothed Particle Hydrodynamics (SPH) method is extended to simulate the ice failure process and ice-ship interactions. The softening elastoplastic model integrating Drucker-Prager yield criterion is embedded into the SPH method to simulate the failure progress of ice. To verify the accuracy of the proposed SPH method, two benchmarks are presented, which include the elastic vibration of a cantilever beam and three-point bending failure of the ice beam. The good agreement between the obtained numerical results and experimental data indicates that the presented SPH method can give the reliable and accurate results for simulating the ice failure progress. On this basis, the extended SPH method is employed to simulate level ice interacting with sloping structure and three-dimensional ice-ship interaction in level ice, and the numerical data is validated through comparing with experimental results of a 1:20 scaled Araon icebreaker model. It is shown the proposed SPH model can satisfactorily predict the ice breaking process and ice breaking resistance on ships in ice-ship interaction.

An improved solid boundary treatment for waveefloat interactions using ISPH method

Xing Zheng,Xipeng Lv,Qingwei Ma,Wenyang Duan,Abbas Khayyer,Songdong Shao 대한조선학회 2018 International Journal of Naval Architecture and Oc Vol.10 No.3

The Smoothed Particle Hydrodynamics (SPH) method has proved to have great potentials in dealing with the wave-structure interactions. Compared with the Weakly Compressible SPH (WCSPH) method, the ISPH approach solves the pressure by using the pressure Poisson equation rather than the equation of state. This could provide a more stable and accurate pressure field that is important in the study of wave-structure interactions. This paper improves the solid boundary treatment of ISPH by using a high accuracy Simplified Finite Difference Interpolation (SFDI) scheme for the 2D wave-structure coupling problems, especially for free-moving structure. The proposed method is referred as the ISPH_BS. The model improvement is demonstrated by the documented benchmark tests and laboratory experiment covering various wavestructure interaction applications.

Characteristic Model-based Adaptive Fault Tolerant Control for Four-motor Synchronization Systems Considering Actuator Failure

Yang Gao,Jiali Ma,Qingwei Chen,Yifei Wu 제어·로봇·시스템학회 2021 International Journal of Control, Automation, and Vol.19 No.12

This article proposes a characteristic model-based adaptive fault tolerant control scheme to deal with actuator failure in four-motor synchronization systems, which usually causes sudden inertia ratio change and backlash increase. Firstly, the characteristic modeling method is applied into servo system to obtain a simplified system model without losing high-order features. Also, this model could reflect real-time system status through three characteristic parameters. Secondly, a particle swarm optimization algorithm-based estimator is designed to identify characteristic parameters online. By this way, the characteristic model could react to inertia ratio changes quickly and eliminate its negative effect in signal tracking. Thirdly, an improved adaptive electric anti-backlash method is used to restrain backlash. Compared to regular anti-backlash technique, this adaptive one uses a neural networkbased fault detector to monitor motors and adjust bias current according to different actuator status, even when one motor breaks down. With these three steps combined, a fast terminal sliding mode controller is finally designed as fault tolerant controller and the stability of this closed-loop system is guaranteed by Lyapunov stability theorem. At last, the simulation and experiment results prove the effectiveness of the proposed control scheme in system control and fault tolerance.

An improved solid boundary treatment for wave-float interactions using ISPH method

Zheng, Xing,Lv, Xipeng,Ma, Qingwei,Duan, Wenyang,Khayyer, Abbas,Shao, Songdong The Society of Naval Architects of Korea 2018 International Journal of Naval Architecture and Oc Vol.10 No.3

The Smoothed Particle Hydrodynamics (SPH) method has proved to have great potentials in dealing with the wave-structure interactions. Compared with the Weakly Compressible SPH (WCSPH) method, the ISPH approach solves the pressure by using the pressure Poisson equation rather than the equation of state. This could provide a more stable and accurate pressure field that is important in the study of wave-structure interactions. This paper improves the solid boundary treatment of ISPH by using a high accuracy Simplified Finite Difference Interpolation (SFDI) scheme for the 2D wave-structure coupling problems, especially for free-moving structure. The proposed method is referred as the ISPH_BS. The model improvement is demonstrated by the documented benchmark tests and laboratory experiment covering various wave-structure interaction applications.

A numerical study on ice failure process and ice-ship interactions by Smoothed Particle Hydrodynamics

Ningbo Zhang,Xing Zheng,Qingwei Ma,Zhenhong Hu 대한조선학회 2019 International Journal of Naval Architecture and Oc Vol.11 No.2

In this paper, a Smoothed Particle Hydrodynamics (SPH) method is extended to simulate the ice failure process and ice-ship interactions. The softening elastoplastic model integrating Drucker-Prager yield criterion is embedded into the SPH method to simulate the failure progress of ice. To verify the accuracy of the proposed SPH method, two benchmarks are presented, which include the elastic vibration of a cantilever beam and three-point bending failure of the ice beam. The good agreement between the obtained numerical results and experimental data indicates that the presented SPH method can give the reliable and accurate results for simulating the ice failure progress. On this basis, the extended SPH method is employed to simulate level ice interacting with sloping structure and three-dimensional iceship interaction in level ice, and the numerical data is validated through comparing with experimental results of a 1:20 scaled Araon icebreaker model. It is shown the proposed SPH model can satisfactorily predict the ice breaking process and ice breaking resistance on ships in ice-ship interaction.

Synthesis of MoSe2/SrTiO3 Heterostructures with Enhanced Ultraviolet-Light-Driven and Visible-Light-Driven Photocatalytic Properties

Xingwang Zhou,Jun Yao,Ming Yang,Jiangquan Ma,Qingwei Zhou,Ershen Ou,Zhen Zhang,Xueni Sun 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2018 NANO Vol.13 No.4

In this research, a series of novel MoSe2/SrTiO3 heterostructures were successfully prepared by a two-step hydrothermal method. The samples were characterized by XRD, UV-Vis, SEM, TEM, EDS and XPS. Results showed that the degradation of MO under UV is better than that under the visible light. And, MoSe2 loaded on SrTiO3 under UV irradiation demonstrated a higher catalytic activity. The degradation rate of methyl orange was 99.46% for MoSe2/SrTiO3 under the optimum loading weight (0.1 wt.%). This is mainly because the combination of MoSe2 and SrTiO3 prevents electrons and holes recombination in SrTiO3 and · O2 - appears in the system. In general, MoSe2/SrTiO3 heterostructures have good environmental friendliness for photocatalytic degradation.

A zonal hybrid approach coupling FNPT with OpenFOAM for modelling wave-structure interactions with action of current

Li, Qian,Wang, Jinghua,Yan, Shiqiang,Gong, Jiaye,Ma, Qingwei Techno-Press 2018 Ocean systems engineering Vol.8 No.4

This paper presents a hybrid numerical approach, which combines a two-phase Navier-Stokes model (NS) and the fully nonlinear potential theory (FNPT), for modelling wave-structure interaction. The former governs the computational domain near the structure, where the viscous and turbulent effects are significant, and is solved by OpenFOAM/InterDyMFoam which utilising the finite volume method (FVM) with a Volume of Fluid (VOF) for the phase identification. The latter covers the rest of the domain, where the fluid may be considered as incompressible, inviscid and irrotational, and solved by using the Quasi Arbitrary Lagrangian-Eulerian finite element method (QALE-FEM). These two models are weakly coupled using a zonal (spatially hierarchical) approach. Considering the inconsistence of the solutions at the boundaries between two different sub-domains governed by two fundamentally different models, a relaxation (transitional) zone is introduced, where the velocity, pressure and surface elevations are taken as the weighted summation of the solutions by two models. In order to tackle the challenges associated and maximise the computational efficiency, further developments of the QALE-FEM have been made. These include the derivation of an arbitrary Lagrangian-Eulerian FNPT and application of a robust gradient calculation scheme for estimating the velocity. The present hybrid model is applied to the numerical simulation of a fixed horizontal cylinder subjected to a unidirectional wave with or without following current. The convergence property, the optimisation of the relaxation zone, the accuracy and the computational efficiency are discussed. Although the idea of the weakly coupling using the zonal approach is not new, the present hybrid model is the first one to couple the QALE-FEM with OpenFOAM solver and/or to be applied to numerical simulate the wave-structure interaction with presence of current.

Efficacy of Different Number of XELOX or SOX Chemotherapy Cycles After D₂ Resection for Stage III Gastric Cancer

Yu, Yuanyuan,Zhang, Zicheng,Meng, Qianhao,Wang, Ke,Li, Qingwei,Ma, Yue,Yao, Yuanfei,Sun, Jie,Wang, Guangyu The Korean Gastric Cancer Association 2022 Journal of gastric cancer Vol.22 No.2

Purpose: We aimed to explore whether the prognosis of patients treated with capecitabine and oxaliplatin (XELOX) or S-1 and oxaliplatin (SOX) regimens who received fewer cycles of chemotherapy after D2 radical resection for gastric cancer (GC) would be non-inferior to that of patients who received the standard number of cycles of chemotherapy. Materials and Methods: Data on patients who received XELOX or SOX chemotherapy after undergoing D2 radical resection at Harbin Medical University Cancer Hospital between January 2011 and May 2016 were collected. Results: In patients who received 4, 6, and 8 cycles of chemotherapy, the 5-year overall survival (OS) rates were 59.4%, 64.8%, and 62.7%, respectively. Compared to patients who received 4 cycles of chemotherapy, those who received 6 cycles (hazard ratio [HR], 0.882; 95% confidence interval [CI], 0.599-1.299; P=0.52) or 8 cycles (HR, 0.882; 95% CI, 0.533-1.458; P=0.62) of chemotherapy did not exhibit significantly prolonged OS. The 3-year disease-free survival (DFS) rate of patients who received 4, 6, and 8 cycles of chemotherapy was 62.1%, 67.2%, and 60.8%, respectively. Compared to patients who received 4 cycles of chemotherapy, those who received 6 cycles (HR, 0.835; 95% CI, 0.572-1.221; P=0.35) or 8 cycles (HR, 0.972; 95% CI, 0.606-1.558; P=0.91) of chemotherapy did not show significantly prolonged DFS. However, the 3-year DFS and 5-year OS rates of patients who received 6 cycles of chemotherapy appeared to be superior to those of patients who received 4 and 8 cycles of chemotherapy. Conclusions: For patients with stage III GC, 4 to 6 cycles of XELOX or SOX chemotherapy may be a favorable option. This study provides a rationale for further randomized clinical trials.