Delamination identification of laminated composite plates using measured mode shapes

Yongfeng Xu,Da-Ming Chen,Weidong Zhu,Guoyi Li,Aditi Chattopadhyay 국제구조공학회 2019 Smart Structures and Systems, An International Jou Vol.23 No.2

An accurate non-model-based method for delamination identification of laminated composite plates is proposed in this work. A weighted mode shape damage index is formulated using squared weighted difference between a measured mode shape of a composite plate with delamination and one from a polynomial that fits the measured mode shape of the composite plate with a proper order. Weighted mode shape damage indices associated with at least two measured mode shapes of the same mode are synthesized to formulate a synthetic mode shape damage index to exclude some false positive identification results due to measurement noise and error. An auxiliary mode shape damage index is proposed to further assist delamination identification, by which some false negative identification results can be excluded and edges of a delamination area can be accurately and completely identified. Both numerical and experimental examples are presented to investigate effectiveness of the proposed method, and it is shown that edges of a delamination area in composite plates can be accurately and completely identified when measured mode shapes are contaminated by measurement noise and error. In the experimental example, identification results of a composite plate with delamination from the proposed method are validated by its C-scan image.

Approximate Optimal Stabilization Control of Servo Mechanisms based on Reinforcement Learning Scheme

Yongfeng Lv,Xuemei Ren,Shuangyi Hu,Hao Xu 제어·로봇·시스템학회 2019 International Journal of Control, Automation, and Vol.17 No.10

A reinforcement learning (RL) based adaptive dynamic programming (ADP) is developed to learn the approximate optimal stabilization input of the servo mechanisms, where the unknown system dynamics are approximated with a three-ayer neural network (NN) identifier. First, the servo mechanism model is constructed and a three-layer NN identifier is used to approximate the unknown servo system. The NN weights of both the hidden layer and output layer are synchronously tuned with an adaptive gradient law. An RL-based critic three-layer NN is then used to learn the optimal cost function, where NN weights of the first layer are set as constants, NN weights of the second layer are updated by minimizing the squared Hamilton-Jacobi-Bellman (HJB) error. The optimal stabilization input of the servomechanism is obtained based on the three-layer NN identifier and RL-based critic NN scheme, which can stabilize the motor speed from its initial value to the given value. Moreover, the convergence analysis of the identifier and RL-based critic NN is proved, the stability of the cost function with the proposed optimal input is analyzed. Finally, a servo mechanism model and a complex system are provided to verify the correctness of the proposed methods.

Stimuli-Responsive Polymers: Fundamental Considerations and Applications

Yongfeng Gao,Menglian Wei,Xue Li,Wenwen Xu,Andrews Ahiabu,Juliana Perdiz,Zining Liu,Michael J. Serpe 한국고분자학회 2017 Macromolecular Research Vol.25 No.6

Stimuli-responsive polymers are capable of changing their chemical and/ or physical properties in response to environmental stimuli. This unique feature has allowed stimuli-responsive polymers to be used in a variety of applications. In this review, we present a basic introduction to the theories that have been developed to describe polymer chains, brushes, and networks. We then detail numerous examples of how stimuli-responsive polymers can be used for sensing and biosensing, drug delivery, and as artificial muscles. While we focus the review on these particular areas, there are numerous other demonstrations of the applications of these fascinating materials, and we are certain that many applications have yet to be discovered.

Expression of Neurotrophin 4 and Its Receptor Tyrosine Kinase B in Reproductive Tissues during the Follicular and Luteal Phases in Cows

Sun, Yongfeng,Li, Chunjin,Sun, Yanling,Chen, Lu,Liu, Zhuo,Ma, Yonghe,Wang, Chunqiang,Zhang, Wei,Zhou, Xu Asian Australasian Association of Animal Productio 2011 Animal Bioscience Vol.24 No.3

The neurotrophins, required for the survival and differentiation of the nervous system, are known to be important for the development of the reproductive tissues. However, the signals initiating the growth of follicles, gamete development, and transport and the development of zygote in the reproductive system of cows remain ambiguous. The purpose of the present study was to identify the transcripts and proteins of Neurotrophin 4 (NT4) and its receptor tyrosine kinase B (TrkB) in bovine reproductive tissues. The transcripts and immunoreactivity of NT4 and TrkB proteins were detected by reverse transcription polymerase chain reaction and western blot analysis. Using immunohistochemistry, the specific immunoreactivity of NT4 and TrkB were detected in the oocytes of primordial follicles and in the growing primary follicles. The NT4 and TrkB immunoreactivity was predominantly observed in granulosa cells, cumulus granulosa cells, cumulus oocyte complexes, theca cells of mature follicles, as well as in the oviduct epithelial cells, uterine gland cell, and epithelium cells of the uterus during the follicular and luteal phases in cows. Expressions of NT4 and TrkB mRNAs were not significantly different among the ovary, oviduct, and uterus of the follicular phase. For the luteal phase, the expression of NT4 mRNA in the ovary was significantly higher than that in the oviduct and uterus, and the expression of TrkB mRNA in the oviduct was significantly higher than that in the ovary and uterus, as determined by fluorescence quantitative reverse transcription polymerase chain reaction. The expression of NT4 mRNA was significantly higher than that of TrkB mRNA in the ovary and uterus, whereas NT4 mRNA expression was lower than that of TrkB mRNA in the oviduct during the luteal phase. The present study hypothesizes that NT4 participates in the regulation of both gonads and extra-gonadal reproductive tissues in cows.

Effects of Different Raising Ways on the Early Growth and Development Performance of Nanjiang Yellow Goat

Luo Hailing,Xu Yongfeng,Zhang Yingjun,Zhang Xiaohong,Liu Kai 한국초지조사료학회 2009 한국초지조사료학회 학술대회논문집 Vol.2009 No.08

A total of 106 two month-old Nanjiang yellow goats (male were 32, female were 34 and castrated were 40) were divided into treatment group and control group to determine the growth performance. The treatment group was reared in grazing mode, experimental group was pastured with supplement feeding. The results showed that the body weight of male in experiment group was heavier by 9.82%(P<0.05), 11.87%(P<0.01), 16.91%(P<0.01) and 23.99%(P<0.05) than that in control group in 3,4,5 and 6 month-age. The body weight of female in experimental group was heavier by 11.54%(P<0.05), 13.79%(P<0.01), 17.47%(P<0.01) and 21.15%(P<0.01) than that in control group in 3,4,5 and 6 month-old. The body weight of castrator in experimental group was heavier by 1.58%, 1.99%, 13.08%(P<0.01) and 15.76%(P<0.01) than that in control group in 3,4,5 and 6 month-age. The daily increasing weight and body measurements of experimental group is improved more than control group, especially in 6 month-age.

Experimental and Theoretical Study on High Strength Steel Extended Endplate Connections After Fire

Xuhong Qiang,Nianduo Wu,Yongfeng Luo,Xu Jiang,Frans Bijlaard 한국강구조학회 2018 International Journal of Steel Structures Vol.18 No.2

In order to reveal more information and better understanding on the behavior and failure mechanisms of high strength steel (HSS) extended endplate connections at ambient temperature and after fi re, an experimental and theoretical study has been conducted and presented in this paper. The provisions of Eurocode 3 are verifi ed with the test results. Because strength of bolts decreases more rapidly than that of structural steels, failure modes of endplate connections may change after fi re. Hence, a series of equations are proposed to predict failure modes of endplate connections after fi re. Furthermore, FE simulations which can predicate the performance of HSS extended endplate connections with reasonable accuracy are adopted to study the behaviors of the connections after cooling down from various fi re temperatures and to validate the accuracy of the proposed equations. Moreover, a parametric study is carried out to explore an optimization design method. It is found that the current provisions of EC3 can justifi ably predict failure modes and plastic fl exural resistances of HSS extended endplate connections both at ambient temperature and cooling down from 550 °C, but it is not the case for their initial rotational stiff - ness and rotation capacity. In order to avoid brittle failure mode of endplate connections after fi re, appropriately increasing the diameter or grade of bolts in the design is suggested. What is more, the match of steel grade and thickness of column fl ange and endplate as well as beam should be considered in the optimization design of beam-column endplate connections.

Block Tearing and Local Buckling of Aluminum Alloy Gusset Joint Plates

Xiaonong Guo,Zhe Xiong,Yongfeng Luo,Han Xu,Shuiping Liang 대한토목학회 2016 KSCE JOURNAL OF CIVIL ENGINEERING Vol.20 No.2

Aluminum Alloy Gusset (AAG) joints widely used in the single-layer latticed shells have a significant application prospect in spatial structures. Unfortunately, studies on the resistance of AAG joints are insufficient, leading to a lack of applicative design methods for this joint system. This paper is devoted to investigate the resistance of AAG joint plates. Firstly, tests on fourteen AAG joint specimens are carried out to explore their collapse modes. Experimental phenomena show that the main collapse modes of AAG joint plates include the block tearing of top plates and the local buckling of bottom plates. Secondly, Finite Element (FE) simulations to investigate the mechanical behavior of AAG joints are performed by means of the non-linear FE code ABAQUS. Thirdly, formulae for predicting the block tearing resistance and the local buckling resistance of AAG joint plates are proposed, which are based on theoretical analyses. Fourthly, test results are of great help in the determination of parameters k and α which are adopted to modify the block tearing resistance and the local buckling resistance respectively. Finally, a comparison of test results verifies that theoretical formulae are applicable. In addition, in order to avoid the block tearing and the local buckling of AAG joint plates, convenient design criteria are provided.

Experimental and Numerical Analysis on Full High Strength Steel Extended Endplate Connections in Fire

Xuhong Qiang,Nianduo Wu,Xu Jiang,Yongfeng Luo,Frans Bijlaard 한국강구조학회 2018 International Journal of Steel Structures Vol.18 No.4

Full-scale experimental study and numerical analysis on behaviors and failure mechanisms of full high strength steel extended endplate connections in fi re have been carried out and presented in this paper. The experimental behaviors of the connections were compared with the provisions of Eurocode 3. The test results show that the failure modes of the connections in fi re are bolt failure with yielding of the fl ange, as same as those at ambient temperature. The failures of the bolts in fi re are ductile while they are brittle at ambient temperature. The rotation capacity of the connections in fi re is proved suffi cient. What is more, at elevated temperature 550 °C, the plastic moment resistances of Q690 and Q960 full high strength steel endplate connections are only 40% of those at ambient temperature, while their initial rotation stiff ness are 66 and 63% respectively. But the rotation capacities of Q690 and Q960 high strength steel endplate connections are 1.38 and 1.74 times of those at ambient temperature. Moreover, it is found that the component method Eurocode 3 proposed based on connections made of mild steels can be used to calculate plastic resistances and to predict failure modes of high strength steel endplate connections in fi re, but it is not suitable to predict their stiff ness. The suggestions about rotation capacity of connections in Eurocode 3 are found too conservative for high strength steel endplate connections in fi re.

Detection of the SRY Transcript and Protein in Bovine Ejaculated Spermatozoa

Li, Chunjin,Sun, Yongfeng,Yi, Kangle,Li, Chengjiao,Zhu, Xiaoling,Chen, Lu,Zhou, Xu Asian Australasian Association of Animal Productio 2011 Animal Bioscience Vol.24 No.10

The sex-determining region on the Y (SRY) gene is important in mammalian sex determination and differentiation. We report a study of the abundance of SRY gene products in bovine ejaculate. RT-PCR experiments using RNA extracted from bovine spermatozoa with SRY-specific primers yielded a 456 bp product, but the amount of SRY mRNA in sperm was lower than that in the testes (p<0.01). A protein of approximately 27 KDa was detected by western blotting. The SRY transcript was detected in the midpiece of approximately half the spermatozoa by in situ hybridization, and the SRY protein was detected in the heads of half the spermatozoa by immunofluorescence, indicating that SRY mRNA and protein may only be present in Y-bearing spermatozoa. These results suggest that the SRY transcript and protein are present in bovine ejaculated Y-sperm. The roles of the SRY gene in spermatogenesis, sperm motility, and the sperm-oocyte interaction merit further investigation.

Enhanced photocatalytic activity on elemental mercury over pink BiOIO3 nanosheets with abundant oxygen vacancies

Yang Ling,Jiachen Li,Jiang Wu,Hailong Liu,Xu Mao,Yongfeng Qi,Qian Ma,Qizhen Liu,Zhanwei Qiao,Weiqun Chu 한국화학공학회 2022 Korean Journal of Chemical Engineering Vol.39 No.2

Elemental mercury removal in coal-fired power plants is the key to global mercury pollution control, and photocatalytic oxidation is an effective and stable method. As a typical bismuth-based photocatalyst, BiOIO3 has a large band gap which is not conducive to the absorption and utilization of visible light, and its specific surface area also limits the diffusion and adsorption of reactants. In this work, pink BiOIO3 (PB) was first prepared successfully via vacuum calcination under absolute pressure of 1*103 Pa. The specific surface area of pink BiOIO3 is significantly increased to 44.52m2/g, which is 1.5-times compared with the traditional BiOIO3 prepared by hydrothermal method (only 29.60 m2/g). Abundant oxygen vacancy defects exist on sample surface, and the formed local BiOI Zero-dimensional (0-D) nanodots provide heterojunction-like effect combined with the BiOIO3, obtaining better photocatalytic property in the oxidation of elemental mercury. The as-prepared pink BiOIO3 and the preparation technology also have strong application potential in the field of energy and environment.