Study on Pollen Viability, Longevity and Pistil Receptivity of Self-Compatible Chrysanthemum with Small Inflorescences

Hongbo Zhao,Fadi Chen,Yanfang Wang,Weimin Fang,Sumei Chen,Weiming Guo 한국원예학회 2006 한국원예학회 기타간행물 Vol.- No.-

Analysis and comparison of the 2D/1D and quasi-3D methods with the direct transport code SHARK

Chen Zhao,Xingjie Peng,Hongbo Zhang,Wenbo Zhao,Qing Li,Zhang Chen 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.1

The 2D/1D method has become the mainstream of the direct transport calculation considering the balance of accuracy and efficiency. However, the 2D/1D method still suffers from stability issues. Recently, a quasi-3D method has been proposed with axial Legendre expansion. Analysis and comparison of the 2D/1D and quasi-3D method is conducted in theory from the equation derivation. Besides, the C5G7 benchmark, the KUCA benchmark and the macro BEAVRS benchmark are calculated to verify the theory comparisons of these two methods with the direct transport code SHARK. All results show that the quasi-3D method has better stability and accuracy than the 2D/1D method with worse efficiency and memory cost. It provides a new option for direct transport calculation with the quasi-3D method.

Failure Pressure of Welded Hollow Spherical Joints Containing Grooving Corrosion Defects and Wall Reduction

Huiyun Chen,Hongbo Liu,Zhi-Hua Chen 한국강구조학회 2021 International Journal of Steel Structures Vol.21 No.1

Welded hollow spherical joints (WHSJ) have been widely used in various space structures. Corrosion of WHSJ is inevitable and will eventually threaten the structural safety. This paper makes an assessment of the accuracy of quality inspection procedures commonly employed by spatial grid structure to calculate the failure pressure of corroded WHSJ via fi nite element analyses (FEA). Second, this paper studies the infl uence of the corrosion depth, corrosion pattern, groove height, joint size and other parameters on the bearing capacity of WHSJ also via FEA. Analytical procedures to calculate the failure pressure associated grooving corrosion are not available yet. Thus, based on the parametric analysis results, such a procedure is devised and proposed here. Results indicated that the wall thickness loss and the diameter ratio were the main factors aff ecting the ultimate compressive performances of WHSJ; the volume loss of WHSJ outside the "critical latitude of groove" had nothing to do with the compressive performances; the infl uence of corrosion on the ultimate compressive performances was independent of the diameter and thickness of WHSJ. The derived result would lay a foundation for the prediction and evaluation of the residual bearing capacity of space grid structures with WHSJ.

Numerical and experimental investigation on the temperature distribution of steel tubes under solar radiation

Hongbo Liu,Zhihua Chen,Ting Zhou 국제구조공학회 2012 Structural Engineering and Mechanics, An Int'l Jou Vol.43 No.6

The temperature on steel structures is larger than the ambient air temperature under solar radiation and the temperature distribution on the affected structure is non-uniform and complicated. The steel tube, as a main structural member, has been investigated through experiment and numerical analysis. In this study, the temperature distribution on a properly designed steel tube under solar radiation is measured. A finite element transient thermal analysis method is presented and verified by the experimental results and a series of parametric studies are carried out to investigate the influence of various geometric properties and orientation on the temperature distribution. Furthermore, a simplified approach is proposed to predict the temperature distribution of steel tube. Based on both the experimental and the numerical results, it is concluded that the solar radiation has a significant effect on the temperature distribution of steel tubes. Under the solar radiation, the temperature of steel tubes is about 20.6oC higher than the ambient air temperature. The temperature distribution of steel tubes is sensitive to the steel solar radiation absorption, steel tube diameter and orientation, but insensitive to the solar radiation reflectance and thickness of steel tube.

Sifting process of EMD and its application in rolling element bearing fault diagnosis

Hongbo Dong,Keyu Qi,Xuefeng Chen,Yanyang Zi,Zhengjia He,Bing Li 대한기계학회 2009 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.23 No.8

Among the vibration-based fault diagnosis methods for rolling element bearing, the shock pulse method (SPM) combined with the demodulation method is a useful quantitative technique for estimating bearing running state. However, direct demodulation often misestimates the shock value of characteristic defect frequency. To overcome this disadvantage, the vibration signal should be decomposed before demodulation. Empirical mode decomposition (EMD) can be an alternative for preprocess bearing fault signals. However, the trouble with this method’s application is that it is time-consuming. Therefore, a novel method that can improve the sifting process’s efficiency is proposed, in which only one time of cubic spline fitting is required in each sifting process. As a consequence, the time for EMD analysis can be evidently shortened and the decomposition results simultaneously maintained at a high precision. Simulations and experiments verify that the improved EMD method, combined with SPM and demodulation analysis, is efficient and accurate and can be effectively applied in engineering practice.

Residual Bearing Capacity of Damaged Large-Diameter Drum-Welded Spherical Joints Post Disaster

Hongbo Liu,Haotian Gao,Mashrah Waleed Ali Hamed,Zhi-Hua Chen 한국강구조학회 2021 International Journal of Steel Structures Vol.21 No.1

Building structures may encounter strong wind, earthquake, snowstorm, and other disaster loads during their service period. Therefore, the members and joints may incur diff erent degrees of damages. However, some damaged members and joints can continue functioning after reasonable assessment and repair. In this study, drum-welded hollow spherical joints (DWHSJs) that are used in Beijing’s New International Airport were considered as research objects. Experimental and numerical analyses were conducted to investigate the compressive bearing capacity of the DWHSJs and their degradation when they suff ered damage. Then, using parametric analysis, the eff ect of various factors on the degradation of the bearing capacity of damaged joints was revealed. Finally, according to the experimental and numerical analysis results, a practical formula for calculating the bearing capacity of damaged joints under axial compression was proposed. A reduction factor of the bearing capacity based on the residual deformation of joints was introduced in the formula. A comparison showed that the calculation results were relatively consistent with the experimental results.

Experimental study on ultrasonic-assisted grinding of micro-structured surface on silicon carbide using small diameter grinding wheel

Hongbo Li,Tao Chen,Zhenyan Duan,Yiwen Zhang,Haotian Li 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.7

As an effective machining method for hard and brittle materials, ultrasonicassisted grinding (UAG) was employed to manufacture microstructures on SiC in this study. The kinematic characteristics of abrasive grains during machining were analyzed first. After that, the influence of machining parameters on the shape accuracy and surface quality was revealed experimentally. The results demonstrate that the feed rate and ultrasonic amplitude have significant effects on machining quality. The introduction of ultrasonic vibration can effectively reduce the grinding force and improve the surface finish quality. For the micro cylinder array, by selecting the ultrasonic amplitude rationally, the peak-to-valley (PV) value and surface roughness can be decreased by 15.8 % and 27.5 %. Furthermore, microcracks, dominated by lateral cracks and fractures were found on the sub-surface. Compared with conventional grinding, UAG can reduce the subsurface damage (SSD) depth and gain a more uniform distribution of damage regions along the machined surface.

Intelligent Scheduling Control of Networked Control Systems with Networked-induced Delay and Packet Dropout

Hongbo Li,Zengqi Sun,Badong Chen,Huaping Liu,Fuchun Sun 대한전기학회 2008 International Journal of Control, Automation, and Vol.6 No.6

Networked control systems (NCSs) have gained increasing attention in recent years due to their advantages and potential applications. The network Quality-of-Service (QoS) in NCSs always fluctuates due to changes of the traffic load and available network resources. To handle the network QoS variations problem, this paper presents an intelligent scheduling control method for NCSs, where the sampling period and the control parameters are simultaneously scheduled to compensate the effect of QoS variation on NCSs performance. For NCSs with network-induced delays and packet dropouts, a discrete-time switch model is proposed. By defining a sampling-period-dependent Lyapunov function and a common quadratic Lyapunov function, the stability conditions are derived for NCSs in terms of linear matrix inequalities (LMIs). Based on the obtained stability conditions, the corresponding controller design problem is solved and the performance optimization problem is also investigated. Simulation results are given to demonstrate the effectiveness of the proposed approaches.

A feasible hydrogen evolution process of water electrolysis assisted by TiO2 nanotube photocatalysis

Hongbo He,Aiping Chen,Ming Chang,Lei Ma,Chunzhong Li 한국공업화학회 2013 Journal of Industrial and Engineering Chemistry Vol.19 No.4

A feasible process called as the hydrogen evolution of water electrolysis assisted by photocatalysis (WEAP) was proposed and experimentally achieved. In comparison with traditional alkaline electrolytic cell for water electrolysis with Ni anode, H2-production rate increased by 118% and the applied direct voltage reduced by 14.5% in WEAP with photoactive Ni anode modified by TiO2 nanotubes.

Reinforcement of Circular Steel Tubes Using Welded Casings Under Axial Compression Loading

Hongbo Liu,Jie Hu,Zhi-Hua Chen,Longxuan Wang,W. A. H. Mashrah 한국강구조학회 2022 International Journal of Steel Structures Vol.22 No.3

To explore the mechanical behavior of circular steel tube components strengthened with welded casings, two groups of six specimens are designed, and two working conditions of zero-load reinforcement and load reinforcement are defi ned. Typical failure modes, ultimate bearing capacity, defl ection curves, and strain data of measuring points are obtained. The FE modeling method considering the thermal eff ect of the welding process is proposed and verifi ed. A total of 446 fi nite element models are established to explore the eff ects of the initial defects, the slenderness ratio, the boundary conditions, and the area ratio of the welded casing to the circular steel tube on the ultimate bearing capacity of the strengthened components. In addition, the ultimate bearing capacity equations for zero-load strengthened components is proposed using regression fi tting and considering the adverse eff ects of the residual stresses due to the rolling and welding processes. Moreover, equations for calculating the deformation and the ultimate bearing capacity of the load-strengthened components considering the eff ect of the welding heat are also derived. Finally, the experimental, numerical, and theoretical analyses results were consistent in high calculation validity and effi ciency.