SPH Modeling of Surge Overflow over RCC Strengthened Levee

Li, Lin,Amini, Farshad,Rao, Xin,Tang, Hongwu Korean Society of Ocean Engineers 2012 International journal of ocean system engineering Vol.2 No.4

Surge overflow may cause damage on earthen levees. Levee strengthened on the levee crest and landward-side slope can provide protection against the erosion damage induced by surge overflow. In this paper, surge overflow of a roller compacted concrete RCC strengthened levee was studied in a purely Lagrangian and meshless approach, the smoothed particle hydrodynamics (SPH) method. After verifying the developed model with analytical solution and comparing the results with full-scale experimental data, the roughness and erosion parameters were calibrated. The water thickness, flow velocity, and erosion depth at crest, landward-side slope and toe were calculated. The characteristics of flow hydraulics and erosion on the RCC strengthened levee are given. The results indicate that the RCC strengthened levee can resist erosion damage for a long period.

SPH Modeling of Hydraulics and Erosion of HPTRM Levee

Li, Lin,Rao, Xin,Amini, Farshad,Tang, Hongwu Korean Society of Ocean Engineers 2015 Journal of advanced research in ocean engineering Vol.1 No.1

Post-Katrina investigations revealed that most earthen levee damage occurred on the levee crest and landward-side slope as a result of either wave overtopping, storm surge overflow, or a combination of both. In this paper, combined wave overtopping and storm surge overflow of a levee embankment strengthened with high performance turf reinforcement mat (HPTRM) system was studied in a purely Lagrangian and meshless approach, two-dimensional smoothed particle hydrodynamics (SPH) model. After the SPH model is calibrated with full-scale overtopping test results, the overtopping discharge, flow thickness, flow velocity, average overtopping velocity, shear stress, and soil erosion rate are calculated. New equations are developed for average overtopping discharge. The shear stresses on landward-side slope are calculated and the characteristics of soil loss are given. Equations are also provided to estimate soil loss rate. The range of the application of these equations is discussed.

Efficiency Analysis of Planetary Gear Train under Ring Gear Deformation

Shao Yimin,Li Xuzhong,Li Hongwu,Chen Yan,Xu Jin 제어로봇시스템학회 2018 제어로봇시스템학회 국제학술대회 논문집 Vol.2018 No.10

Transmission efficiency is a key parameter of planetary gear train, it has a significant effect on power density of transmission systems. Usually, ring gear is regard as a rigid part in the efficiency calculation of planetary gear train. However, most of the planetary gear train adopt flexible ring gear design, which means the deformation of ring gear is large. In addition, the deformation of the ring gear leads to the change of the meshing relationship of the gears in the planetary gear train, thus both the dynamic load, sliding speed and friction force in the planetary gear train are affected. Besides, the meshing power loss in planetary gear train is also changed. Therefore, this paper takes the elastic deformation of the flexible ring gear and the dynamic friction force along the contact path of the gear teeth into consideration. Then the vibration responses of the planetary gear train are calculated based on a new established concentrated mass dynamic model. Next, power loss on the meshing interface and the meshing efficiency of the planetary gear trains are evaluated with the consideration of ring gear deformation. The calculation results show that the elastic deformation of the ring gear has a great influence on the meshing efficiency of the planetary gear train.

Control Strategies for a High-Performance 2x27 MVA Machine Test Bench with Multilevel IGCT Converters

Bo Qu,Jingkui Shi,Hongwu She,Jie Shen,Stefan Schroeder,Zhuohui Tan,Kunlun Chen,Jianmei Zhang,Yulong Li,Fan Zhang,Richard Zhang 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

In this paper, control strategies of a 22 MW / 27 MVA machine test bench using pumpback topology are introduced. The current loop design at extremely low pulse ratios (e.g. 600 Hz carrier frequency / 80 Hz load frequency) is developed. The system stability and dynamic response are analyzed. The challenges for high-power machine control with a sine filter and a transformer connected between the voltage-source-inverter and the machine are listed and solutions are given. Afterwards, some specific test modes are introduced as well. Finally, the control strategy is validated with the motor test at the customer site.

New generation software of structural analysis and design optimization--JIFEX

Gu, Yuanxian,Zhang, Hongwu,Guan, Zhenqun,Kang, Zhan,Li, Yunpeng,Zhong, Wanxie Techno-Press 1999 Structural Engineering and Mechanics, An Int'l Jou Vol.7 No.6

This paper presents the development and applications of the software package JIFEX, a new finite element system which can be used for structural analysis and optimum design by the modern computer hardware and software technologies such as MS Windows95/NT and Pentium PC platforms. The complete system of JIFEX is programmed with $C/C^{++}$ language to make full use of advanced facilities of MS Windows95/NT. In the system, the finite element data pre-processing, based on the most popular CAD package AutoCAD (R13, R14), has been implemented, so that the finite element modeling could be integrated with geometric modeling of CAD. The system not only has interactive graphics facility for data post-processing, but also realizes the real-time computing visualization by means of the Dynamic Data Exchange (DDE) technique. Running on the Pentium computers, JIFEX can solve large-scale finite element analysis problems such as the ones with more than 60000 nodes in the finite element model.

Efficiency Analysis of Gear System Based on Gear Surface Micro-topography

Wei Liu,Yimin Shao,Hongwu Li,Yan Cheng,Jin Xu 제어로봇시스템학회 2018 제어로봇시스템학회 국제학술대회 논문집 Vol.2018 No.10

In order to accurately calculate the gear transmission efficiency, a new efficiency evaluation method is proposed considering the 3D micro-topography of the tooth surface. Firstly, a digital microsystem is used to obtain the surface micro-topography of gears. The roughnesses of the gears at different meshing positions are then calculated according to the tooth surface micro-topography parameters and the gear meshing principle. Subsequently, the calculated roughnesses are substituted into the gear system dynamic model with the ROMAX software employed, and the distribution of friction coefficient and efficiencies of gear system can be simulated at different input torques and roughnesses. The simulation results show that the greater the surface roughness, the lower the efficiency of gear transmission. Conversely, the greater the torque, the greater the efficiency of the gear transmission. Finally, to further validate the effectiveness of the proposed method, efficiency experiments at same working conditions are carried out and a sound comparative analysis of previous studies is launched. The results show that the proposed method is effective with an error of less than 2%.

Can CD44+/CD24- Tumor Cells Be Used to Determine the Extent of Breast Cancer Invasion Following Neoadjuvant Chemotherapy?

Hong Wu,Ruhui Li,XiaoDong Hang,Ming Yan,Feng Niu,Lidi Liu,Wei Liu,Song Zhao,Shaokun Zhang 한국유방암학회 2011 Journal of breast cancer Vol.14 No.3

Purpose: To investigate the distribution of CD44+/CD24- cells in breast cancers in relation to tumor size before and after the administration of neoadjuvant chemotherapy. Methods: CD44+/CD24- tumor cells obtained from breast cancer specimens were characterized in vivo and in vitro using tumor formation assays and mammosphere generation assays, respectively. The distribution of CD44+/CD24- tumor cells in 78 breast cancer specimens following administration of neoadjuvant chemotherapy was also evaluated using immunofluorescence assays, and this distribution was compared with the extent of tumor invasion predicted by Response Evaluation Criteria in Solid Tumours (RECIST). Results: In 27/78 cases, complete remission (CR) was identified using RECIST. However, 18 of these CR cases were associated with a scattered distribution of tumor stem cells in the outline of the original tumor prior to neoadjuvant chemotherapy. After neoadjuvant chemotherapy, 24 cases involved cancer cells that were confined to the tumor outline, and 21 cases had tumor cells or tumor stem cells overlapping the tumor outline. In addition, there were 6 patients who were insensitive to chemotherapy, and in these cases, both cancer cells and stem cells were detected outside the contours of the tumor volume imaged prior to chemotherapy. Conclusion:CD44+/CD24- tumor cells may be an additional parameter to evaluate when determining the extent of breast cancer invasion.

Negative-refraction Effect for Both TE and TM Polarizations in Two-dimensional Annular Photonic Crystals

Hong Wu,Feng Li 한국광학회 2018 Current Optics and Photonics Vol.2 No.1

We systematically investigated the negative-refraction effect for both TE and TM polarizations in annular photonic crystals. Since two polarization waves are excited in different bands, they result in different refractive angles, and so polarization beam splitters can be made of annular photonic crystals. It was found that, in comparison to normal square-lattice air-hole photonic crystals, annular photonic crystals have a much wider common frequency band between TE-1 and TM-2, which is quite beneficial to finding the overlap between the negative-refraction regions belonging to TE-1 and TM-2 respectively. Further analyses of equifrequency surfaces and the electric-field distribution of annular photonic crystals with different parameters have not only demonstrated how the filling factor of annular cells affects the formation of the common negative-refraction region between TE-1 and TM-2, but also revealed some ways to improve the performance of a polarization beam splitter based on the negative-refraction effect in an annular photonic crystal.