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Zhiwei Song,Wei Li,Guirong Liu 국제구조공학회 2012 Structural Engineering and Mechanics, An Int'l Jou Vol.44 No.4
Dynamic instability of beams subjected to periodic axial forces is studied using the discrete singular convolution (DSC) method with the regularized Shannon’s delta kernel. The principal regions of dynamic instability under different boundary conditions are examined in detail, and the non-stationary vibrations near the stability-instability critical regions have been investigated. It is found that the results obtained by using the DSC method are consistent with the analytical solutions, which shows that the DSC algorithm is suitable for the problems considered in this study. It was found that there is a narrow region of beat vibration existed in the vicinity of one side (θ/Ω > 1) of the boundaries of the instable region for each condition.
Song, Zhiwei,Li, Wei,Liu, Guirong Techno-Press 2012 Structural Engineering and Mechanics, An Int'l Jou Vol.44 No.4
Dynamic instability of beams subjected to periodic axial forces is studied using the discrete singular convolution (DSC) method with the regularized Shannon's delta kernel. The principal regions of dynamic instability under different boundary conditions are examined in detail, and the non-stationary vibrations near the stability-instability critical regions have been investigated. It is found that the results obtained by using the DSC method are consistent with the analytical solutions, which shows that the DSC algorithm is suitable for the problems considered in this study. It was found that there is a narrow region of beat vibration existed in the vicinity of one side (${\theta}/{\Omega}$ > 1) of the boundaries of the instable region for each condition.
Zhiwei Song,Wei Li,Xiaoqiao He,De Xie 국제구조공학회 2019 Structural Engineering and Mechanics, An Int'l Jou Vol.72 No.1
This paper proposes a modified matched interface and boundary (MMIB) method to analyze the free vibration of beams with various interfaces caused by steps, intermediate rigid and elastic supports, intermediate concentrated masses and spring-mass systems, etc. A new strategy is developed to determine the parameters in the iterative computation of MMIB. The MMIB procedures are established to deal with boundary conditions and various interface conditions, which overcomes the shortcoming of the traditional MIB. A number of examples are utilized to illustrate the performance of MMIB method. Numerical results indicate that the MMIB method is a highly accurate and convergent approach for solving interface problems.
Zhiwei Song,Xiaoqiao He,Wei Li,De Xie 국제구조공학회 2020 Structural Engineering and Mechanics, An Int'l Jou Vol.76 No.2
This paper deals with free vibration of plates with steps and internal line supports by using a modified matched interface and boundary (MMIB) method. Different kinds of interfaces caused by steps, rigid and elastic line supports and their combinations are taken into account. Detailed MMIB procedures for dealing with these different interfaces are presented. Various examples are chosen to illustrate the accuracy and convergence of MMIB method. Numerical results show that the proposed MMIB is a highly accurate and convergent approach for solving the title issue. This study will extend the application range of MMIB method.
Pavement Crack Detection by Ridge Detection on Fractional Calculus and Dual-thresholds
Song Hongxun,Wang Weixing,Wang Fengping,Wu Linchun,Wang Zhiwei 보안공학연구지원센터 2015 International Journal of Multimedia and Ubiquitous Vol.10 No.4
In this paper, a new road surface crack detection algorithm is proposed; it is based on the ridge edge detection on fractional calculus and the dual-thresholds on a binary image. First, the multi-scale reduction of image data is used to shrink an original image to eliminate noise, which can not only smooth an image but also enhance cracks. Then, the main cracks are extracted by using the ridge edge detection on fractional calculus in a grey scale image. Subsequently, the resulted binary image is further processed by applying both short and long line thresholds to eliminate short curves and noise for getting rough crack segments. Finally the gaps in cracks are connected with a curve connection function which is an artificial intelligence routine. The experiments show that the algorithm for pavement crack images has the good performance of noise immunity, accurate positioning, and high accuracy. It can accurately locate and detect small and thin cracks that are difficult to identify by other traditional algorithms.
Toughening of melamine–formaldehyde foams and advanced applications based on functional design
Bing Song,Xueli Zhu,Wei Wang,Liang Wang,Xiaoyuan Pei,Xiaoming Qian,Liangsen Liu,Zhiwei Xu 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.119 No.-
Owing to the intrinsic flame-retardancy, thermal stability, sound absorption, and easy processing, melamine–formaldehyde foams(MFs) have drawn substantial attention. Typically, the high-porosity and compressibilityof flexible MFs render them suitable for the construction of 3D templates and in thefabrication of porous N-doped carbon materials. But the widespread applications of MFs still suffer highbrittleness and low strength, calling for modifying and toughening MFs with more facile and economicalmethods, and much potential in advanced applications by functional design deserves further exploration. This review comprehensively summarized and evaluated the recent progress of the toughening methodsof MFs. We will also look into the applications of commercial MFs, carbonized MFs and foam-based compositesin flame retardancy and thermal management, oil/water separation, photothermal conversion,electrical energy storage, and other fields, aiming to give a guide for the preparation, modification, andexploitation of MFs both in traditional and emerging areas.
Li Song,Zhiwei Fan,Jian Hou 한국콘크리트학회 2019 International Journal of Concrete Structures and M Vol.13 No.4
The fatigue flexural behavior of corroded reinforced concrete (RC) beams was experimentally and analytically examined. Seven beams were constructed and tested, and an analytical fatigue prediction model (FPM) was proposed to assess the fatigue behavior of the corroded beams. After validating the FPM with the experimental test results, the FPM was then extended to better understand the effects of the degree of steel corrosion, the corrosion pit geometry, and the fatigue load level on the performance of corroded RC beams. The results show that the fatigue behavior of the corroded steel bars determines the fatigue behavior of the beams. Rebar corrosion has a significant detrimental effect on the fatigue performance of RC beams due to stress concentration, loss of steel cross-sectional area, and diminished bonding at the steel-concrete interface. The stress concentrations increase with increasing pit width-to-length and depth-to-diameter ratios. Differences in pit geometry and the resulting changes in stress concentrations due to corrosion should be considered when assessing fatigue performance.
Error modeling and accuracy optimization of rotating ultrasonic vibration assisted EDM machine tool
Minggang Xu,Zhiwei Wu,Feng Gao,Linlin Liu,Enyu Song 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.7
Rotating ultrasonic vibration assisted EDM is a composite machining method that uses EDM to etch a metal surface and adds rotating and ultrasonic vibration. It has high efficiency and a wide range of workpiece materials. Aiming at the structural characteristics of rotary ultrasonic vibration assisted EDM machine tool, the errors caused by the main moving parts of the machine tool were analyzed. The structure relationship is described by multi-body system theory, and the geometric error model is deduced by homogeneous coordinate transformation method. The aim was to improve the overall accuracy, reduce the cost, trace the error source, and get the corresponding relationship between the basic geometric errors and the precision parameters of the related parts. Under the requirement of ensuring the overall accuracy, an optimization function was established that minimizes the cost and relaxes all accuracy parameters to the greatest extent. Finally, MATLAB and its genetic algorithm toolbox was used for analysis. Verification shows that this model can properly reduce the cost on the premise of ensuring the accuracy.
Cao Yang,Xinghuo Wu,Zhiwei Liao,Kun Wang,Wenbin Hua,Xianzhe Liu,Yu Song,Yukun Zhang,Shuhua Yang 생화학분자생물학회 2019 Experimental and molecular medicine Vol.51 No.-
Intervertebral disc degeneration (IDD) is characterized by excessive apoptosis of nucleus pulposus (NP) cells and hyperactive extracellular matrix (ECM) catabolism. Our previous studies revealed the relationship between human islet amyloid polypeptide (hIAPP) and NP cell apoptosis. However, the role of hIAPP aggregates in IDD has not yet been investigated. This study aimed to determine whether the accumulation of hIAPP aggregates promotes IDD progression. The aggregation of hIAPP increased in human NP tissues during IDD. The deposition of hIAPP aggravated the compression-induced IDD that promoted NP cell apoptosis and ECM degradation via IL-1β/IL-1Ra signaling in an ex vivo rat disc model. Moreover, neutralizing IL-1β augmented the protective effects of hIAPP overexpression by decreasing hIAPP aggregation in human NP cells. These results suggest that the aggregation of hIAPP promotes NP cell apoptosis and ECM degradation ex vivo and in vitro by disrupting the balance of IL-1β/IL-1Ra signaling.