A nonlinear friction-cohesive model for characterizing mode II fracture of laminated composites

Ruoyu Li,Chaocan Cai,Zhonghai Xu,Xiaocan Zou,Chunxing Hu,Xiaodong He 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.5

In this paper, the Coulomb friction is incorporated into the exponential cohesive law, so a nonlinear friction-cohesive model combining sliding friction and interfacial debonding is developed to characterize the mechanical responses of mode II fracture. This model can well simulate the load-displacement curve of ENF test, after properly calibrating the parameters through the experimental data available in the literature. Then, a parametric study to investigate the effects of interfacial parameters on the load-displacement curves of ENF test has been carried out. The results show that, compared with the bi-linear cohesive model and exponential cohesive model, the proposed model is closer to the experimental data. Friction parameters will affect the initial delamination stage and stable delamination stage of ENF test, and interfacial characteristic lengths and interfacial shear strength will affect the peak load of ENF test.

Trajectory Planning of Rail Inspection Robot Based on an Improved Penalty Function Simulated Annealing Particle Swarm Algorithm

Ruoyu Xu,Jianyan Tian,Jifu Li,Xinpeng Zhai 제어·로봇·시스템학회 2023 International Journal of Control, Automation, and Vol.21 No.10

To ensure the smooth operation of each joint and shorten the joint movement time of a rail inspection robot, a trajectory planning method based on time optimization with a penalty function is proposed. According to the Denavit-Hartenberg (D-H) model of the inspection robot, a kinematic solution is found, and the trajectory of each joint is generated using a mixed polynomial interpolation algorithm. Taking time optimization as the standard, the traditional particle swarm algorithm cannot handle complex constraints, easily falls to local optimum solutions, and has a slow convergence speed. An improved simulated annealing particle swarm algorithm with a penalty function (IPF-SA-PSO) is proposed to optimize the trajectory generated by the mixed polynomial interpolation algorithm. The simulation results show that the proposed algorithm, compared with the mixed polynomial interpolation method, can limit the angular velocity and reduce the running time of each manipulator joint. The two algorithms are experimentally verified based on a rail inspection robot, and the results show that after adopting the optimization algorithm, the angular velocity of each joint is within the angular velocity limit, the run time is shorter, and the operation is smoother, which indicates the effectiveness of the proposed algorithm. The proposed algorithm can optimize the robot running time, improve the smoothness, and be applied to the fields of the automatic tracking of abnormal targets and video acquisition.

Combining Adaptive Filtering and IF Flows to Detect DDoS Attacks within a Router

( Ruoyu Yan ),( Qinghua Zheng ),( Haifei Li ) 한국인터넷정보학회 2010 KSII Transactions on Internet and Information Syst Vol.4 No.3

Traffic matrix-based anomaly detection and DDoS attacks detection in networks are research focus in the network security and traffic measurement community. In this paper, firstly, a new type of unidirectional flow called IF flow is proposed. Merits and features of IF flows are analyzed in detail and then two efficient methods are introduced in our DDoS attacks detection and evaluation scheme. The first method uses residual variance ratio to detect DDoS attacks after Recursive Least Square (RLS) filter is applied to predict IF flows. The second method uses generalized likelihood ratio (GLR) statistical test to detect DDoS attacks after a Kalman filter is applied to estimate IF flows. Based on the two complementary methods, an evaluation formula is proposed to assess the seriousness of current DDoS attacks on router ports. Furthermore, the sensitivity of three types of traffic (IF flow, input link and output link) to DDoS attacks is analyzed and compared. Experiments show that IF flow has more power to expose anomaly than the other two types of traffic. Finally, two proposed methods are compared in terms of detection rate, processing speed, etc., and also compared in detail with Principal Component Analysis (PCA) and Cumulative Sum (CUSUM) methods. The results demonstrate that adaptive filter methods have higher detection rate, lower false alarm rate and smaller detection lag time.

Dynamic plant-wide process monitoring based on distributed slow feature analysis with inter-unit dissimilarity

Ruoyu Huang,Zetao Li,Bin Cao 한국화학공학회 2022 Korean Journal of Chemical Engineering Vol.39 No.2

In order to overcome the dynamic and large-scale characteristics of the plant-wide processes, this paper proposed a distributed slow feature analysis (SFA) with inter-unit dissimilarity method for process monitoring task. Firstly, to highlight the local dynamic features, the whole process is decomposed into several units according to the prior knowledge. Based on this, SFA monitoring model is built parallelly to handle the dynamic features. Considering the possible information loss caused by the process decomposition, the inter-unit dissimilarity index is carried out to monitor the variations between adjacent units. Finally, the fusion center is conducted by Bayesian inference to combine the results of SFA monitoring models and inter-unit dissimilarity statistics. The effectiveness of the proposed method is tested on the Tennessee Eastman process and an aluminum electrolysis process.

Case-based reasoning approach to estimating the strength of sustainable concrete

구충완,Ruoyu Jin,Bo Li,차승현,Dariusz Wanatowski 사단법인 한국계산역학회 2017 Computers and Concrete, An International Journal Vol.20 No.6

Continuing from previous studies of sustainable concrete containing environmentally friendly materials and existing modeling approach to predicting concrete properties, this study developed an estimation methodology to predicting the strength of sustainable concrete using an advanced case-based reasoning approach. It was conducted in two steps: (i) establishment of a case database and (ii) development of an advanced case-based reasoning model. Through the experimental studies, a total of 144 observations for concrete compressive strength and tensile strength were established to develop the estimation model. As a result, the prediction accuracy of the A-CBR model (i.e., 95.214% for compressive strength and 92.448% for tensile strength) performed superior to other conventional methodologies (e.g., basic case-based reasoning and artificial neural network models). The developed methodology provides an alternative approach in predicting concrete properties and could be further extended to the future research area in durability of sustainable concrete.

Seismic performance of beam-to- SST column connection with external diaphragm

Bin Rong,Shuhao Yin,Ruoyu Zhang,Lei Wang,Ziheng Yang,Hongtao Li,Wenyu Wan 국제구조공학회 2020 Steel and Composite Structures, An International J Vol.37 No.6

This paper aims to study the seismic performance of external diaphragm connection between SST (square steel tube) column and H-shaped beam through experimental and analytical study involving finite element (FE) method and theoretical analysis. In the experimental study, three external diaphragm connection specimens with weak panel zone were tested under axial pressure on the top of the column and antisymmetric cyclic loads at the beam end to investigate the seismic performance of the panel zone. The hysteretic behavior, failure mode, stiffness and ductility of the specimens were discussed. Key point to be explored was the influence of the thickness of the steel tube flange on the shear capacity of the specimens. In the analytical study, three simplified FE models were developed to simulate the seismic behavior of the specimens for further analysis on the influence of steel tube flange. Finally, four existing calculation formulas for the shear capacity of the external diaphragm connection were evaluated through comparisons with the results of experiments and FE analysis, and application suggestions were put forward.

Adipose-Derived Stem Cell Exosomes Promoted Hair Regeneration

Wu Jinyan,Yang Quyang,Wu Sainan,Yuan Ruoyue,Zhao Xiansheng,Li Yue,Wu Wenyu,Zhu Ningwen 한국조직공학과 재생의학회 2021 조직공학과 재생의학 Vol.18 No.4

Background: Some scholars have found that dermal papilla spheroid–derived exosomes could promote the development of hair follicles. However, whether adipose-derived stem cell exosomes (ADSC-Exos) have a similar effect on hair growth has not been determined yet. Thus, the purpose of this article was to detect whether ADSC-Exos could promote hair regeneration. Methods: Adipose-derived stem cells (ADSCs) were isolated from 6-week-old C57BL/6 mice. Then, ADSC-Exos were isolated from the ADSCs. Western blotting was used to detect specific exosome markers. The particle size and distribution of the exosomes were analyzed by NanoSight dynamic light scattering. A total of 12 nude mice were randomly divided into two groups (n = 6 each): the ADSC-Exos group and the control group. For the control group, a mixture of freshly isolated dermal cells (DCs) and epidermal cells (ECs) was grafted. For the ADSC-Exos group, a mixture of DCs, ECs, and 50 μg/ml of ADSC-Exos was grafted. Gross evaluation of the hair regeneration was carried out 2–3 weeks after the transplantation, and the graft site was harvested for histology at the third week. Results: The existence of exosomes derived from ADSCs was evidenced by CD63, ALX1, and CD9 expression. Two or three weeks after the grafting, the number of regenerated hairs in the ADSC-Exos group was higher than that in the control group (p < 0.001). Histologically, the terminal hairs were remarkable in the ADSC-Exos group, whereas the hair follicles observed in the control group were comparatively immature. The ADSC-Exos group had a higher number of regenerated follicles than the control group (p < 0.001). In addition, we found that the skin tissues in the ADSC-Exos group had higher PDGF and vascular endothelial growth factor expressions and lower transforming growth factor beta 1 levels than those in the control group. Conclusion: Our results indicated that ADSC-Exos could promote in vivo hair follicle regeneration. Background: Some scholars have found that dermal papilla spheroid–derived exosomes could promote the development of hair follicles. However, whether adipose-derived stem cell exosomes (ADSC-Exos) have a similar effect on hair growth has not been determined yet. Thus, the purpose of this article was to detect whether ADSC-Exos could promote hair regeneration. Methods: Adipose-derived stem cells (ADSCs) were isolated from 6-week-old C57BL/6 mice. Then, ADSC-Exos were isolated from the ADSCs. Western blotting was used to detect specific exosome markers. The particle size and distribution of the exosomes were analyzed by NanoSight dynamic light scattering. A total of 12 nude mice were randomly divided into two groups (n = 6 each): the ADSC-Exos group and the control group. For the control group, a mixture of freshly isolated dermal cells (DCs) and epidermal cells (ECs) was grafted. For the ADSC-Exos group, a mixture of DCs, ECs, and 50 μg/ml of ADSC-Exos was grafted. Gross evaluation of the hair regeneration was carried out 2–3 weeks after the transplantation, and the graft site was harvested for histology at the third week. Results: The existence of exosomes derived from ADSCs was evidenced by CD63, ALX1, and CD9 expression. Two or three weeks after the grafting, the number of regenerated hairs in the ADSC-Exos group was higher than that in the control group (p < 0.001). Histologically, the terminal hairs were remarkable in the ADSC-Exos group, whereas the hair follicles observed in the control group were comparatively immature. The ADSC-Exos group had a higher number of regenerated follicles than the control group (p < 0.001). In addition, we found that the skin tissues in the ADSC-Exos group had higher PDGF and vascular endothelial growth factor expressions and lower transforming growth factor beta 1 levels than those in the control group. Conclusion: Our results indicated that ADSC-Exos could promote in vivo hair follicle regeneration.

The compressive behavior of CFRP laminates with delamination of different shapes using numerical and experimental approaches

Chunxing Hu,Yujiao Bai,Zhonghai Xu,Ruoyu Li,Rongguo Wang,Xiaodong He 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.9

Composite laminates often produce delamination due to a series of factors during the manufacture and service process. In order to research the effect of containing oblique elliptical and circular initial delamination damage on the compressive strength of composite laminates, numerical and experimental methods are used in this paper. Finite element models (FEMs) and the progressive damage subroutine USDFLD are developed to predict the damage initiation and extension behavior of the intralaminar of the laminate. Interlaminar damage is predicted based on cohesive zone models (CZM). At the same time, four compression tests containing different initial delamination damage are performed. The results show that experimental measurements of compression tests concur with the numerical predictions and validate the FEMs. The strength and stiffness of the specimens gradually decrease with the increase of the initial delamination area. It reveals that, for the compression process, the delamination damage extends from the edge of the initial damage to the surroundings. The bearing capacity of the composite laminates is mainly determined by the material properties of the fibers and matrix, rather than the initial delamination.

Stem Cell-Derived Exosomes: A New Method for Reversing Skin Aging

Wu Jinyan,Wu Sai-Nan,Zhang Li-Ping,Zhao Xiansheng,Li Yue,Yang Quyang,Yuan Ruoyue,Liu Jian-Lan,Mao Hong-Ju,Zhu Ningwen 한국조직공학과 재생의학회 2022 조직공학과 재생의학 Vol.19 No.5

Senescence is an inevitable natural life process that involves structural and functional degeneration of tissues and organs. Recently, the process of skin aging has attracted much attention. Determining a means to delay or even reverse skin aging has become a research hotspot in medical cosmetology and anti-aging. Dysfunction in the epidermis and fibroblasts and changes in the composition and content of the extracellular matrix are common pathophysiological manifestations of skin aging. Reactive oxygen species and matrix metalloproteinases play essential roles in this process. Stem cells are pluripotent cells that possess self-replication abilities and can differentiate into multiple functional cells under certain conditions. These cells also possess a strong ability to facilitate tissue repair and regeneration. Stem cell transplantation has the potential for application in anti-aging therapy. Increasing studies have demonstrated that stem cells perform functions through paracrine processes, particularly those involving exosomes. Exosomes are nano-vesicular substances secreted by stem cells that participate in cell-to-cell communication by transporting their contents into target cells. In this chapter, the biological characteristics of exosomes were reviewed, including their effects on extracellular matrix formation, epidermal cell function, fibroblast function and antioxidation. Exosomes derived from stem cells may provide a new means to reverse skin aging.

Drug Reaction with Eosinophilia and Systemic Symptoms Associated with Reactivation of Epstein-Barr Virus and/or Cytomegalovirus Leading to Hemophagocytic Syndrome in One of Two Patients

( Jianhua Liang ),( Hui Qu ),( Xiaowen Wang ),( Aiping Wang ),( Lingling Liu ),( Ping Tu ),( Ruoyu Li ),( Mingyue Wang ) 대한피부과학회 2018 Annals of Dermatology Vol.30 No.1

Drug reaction with eosinophilia and systemic symptoms (DRESS) is a hypersensitivity reaction characterized by maculopapular rash, exfoliative dermatitis, lymphadenopathy, fever, eosinophilia, and involvement of internal organs. Evidence for reactivation of herpes family viruses has been observed in some DRESS patients, and activated CD8+ T lymphocytes are largely directed against Epstein-Barr virus. Here, we report two cases complicated with this infection. Both patients received antibiotics and non-steroidal anti-inflammatory drugs. These patients manifested clinically with high fever, facial edema, diffuse pruritic erythroderma and maculopapules over the entire body, purpuric rashes in both lower limbs and lymphadenopathy of cervical and inguinal nodes. Laboratory tests revealed abnormal liver function, blood eosinophils, and ferritin levels. The patients recovered completely; however, the female patient developed hemophagocytic syndrome on the 15th day of illness. She developed new itchy rash, and laboratory tests rapidly worsened with fibrinogen levels dramatically reduced to 0.61 g/L. Bone marrow aspiration revealed an increased number of macrophages with hemophagocytosis and a reversed CD4/CD8 ratio of 0.45. These cases suggest that human herpes virus and coagulation function evaluations are necessary in DRESS patients. (Ann Dermatol 30(1) 71∼74, 2018)