Discussion on Failure Mechanism and Strength Criterion of Sandstone Based on Particle Discrete Element Method

Shuguang Zhang,Lei Chen,Pingping Lu,Wenbo Liu 대한토목학회 2021 KSCE Journal of Civil Engineering Vol.25 No.6

In order to study the mechanism of loading failure process of deep rock mass, particle flow numerical simulation (PFC2D) was used to carry out rock mechanical unit tests under different loading strain rates for sandstone in Haitangshan Tunnel, Fuxin. The applicability of several classical strength criteria was compared according to the test. The results show that, except Poisson's ratio, the other mechanical parameters are positively correlated with the loading strain rate, including peak strength, elastic modulus, cohesion, internal friction angle and tensile strength. And the Poisson's ratio is negatively correlated with the loading strain rate. And the crack initiation stress σci and dilatation stress σcd increased gradually, but the effects on σci/σpk, σcd/σpk and σci/σcd were not obvious; and at the same volume strain, the corresponding axial strain decreased gradually. The anisotropy of normal and tangential contact forces between particles increases with the increase of loading strain rate. The normal contact force was approximately symmetrical distributed up and down, while the tangential contact force was approximately symmetrical distributed in the center. The cumulative number of cracks and the number of cracks every 10 steps gradually increased with the loading strain rate, and the crack development and failure degree gradually increased, and the crack hot spot map at the shear fracture zone gradually tended to be irregular. By comparing different strength criteria, it was found that the error of ROCKER strength criterion was relatively small, and the calculation was simple. It was considered that ROCKER strength criterion was more suitable for sandstone strength prediction under different loading strain rates.

Osteogenic and Angiogenic Potency of VEGF165-Transfected Canine Bone Marrow Mesenchymal Cells Combined with Coral Hydroxyapatite in Vitro

Zhang Quanyin,Zhang Jie,Chen Lin,Fan Yunjian,Long Jiazhen,Liu Shuguang 한국조직공학과 재생의학회 2021 조직공학과 재생의학 Vol.18 No.5

BACKGROUND: To explore the osteogenic and angiogenic potential of human vascular endothelial growth factor 165 (hVEGF165) gene-transfected canine bone marrow mesenchymal stem cells (BMSCs) combined with coral hydroxyapatite (CHA) scaffold. METHODS: We constructed a lentiviral vector and transfected canine BMSCs with the best multiplicity of infection. Osteogenesis was induced in the transfected groups (GFP-BMSCs group and hVEGF-BMSCs group) and non-transfected group (BMSCs group), followed by the evaluation of alkaline phosphatase (ALP) activity and alizarin red S staining. Cells from the three groups were co-cultured with CHA granules, respectively to obtain the tissue-engineered bone. MTT assay and fluorescence microscopy were employed to assess cell proliferation and adhesion. The expression of osteogenic and angiogenic related genes and proteins were evaluated at 7, 14, 21, and 28 days post osteoinduction in cell culture alone and cell co-culture with CHA, respectively using RT-PCR and ELISA. RESULTS: The hVEGF165 gene was transfected into BMSCs successfully. Higher ALP activity and more calcified nodules were found in the hVEGF-BMSCs group than in the control groups (p < 0.001). Cells attached and proliferated in CHA particles. Both cells cultured alone and cells co-culture with CHA expressed more osteogenic and angiogenic related genes and proteins in the hVEGF-BMSCs group compared to the GFP-BMSCs and BMSCs groups (p < 0.05). CONCLUSION: High expression of hVEGF165 in BMSCs potentially promote the osteogenic potential of BMSCs, and synergically drive the expression of other osteogenic and angiogenic factors. hVEGF-BMSCs co-cultured with CHA expressed more osteogenic and angiogenic related factors, creating a favorable microenvironment for osteogenesis and angiogenesis. Also, the findings have allowed for the construction of a CHA-hVEGF-BMSCs tissue-engineered bone. BACKGROUND: To explore the osteogenic and angiogenic potential of human vascular endothelial growth factor 165 (hVEGF165) gene-transfected canine bone marrow mesenchymal stem cells (BMSCs) combined with coral hydroxyapatite (CHA) scaffold. METHODS: We constructed a lentiviral vector and transfected canine BMSCs with the best multiplicity of infection. Osteogenesis was induced in the transfected groups (GFP-BMSCs group and hVEGF-BMSCs group) and non-transfected group (BMSCs group), followed by the evaluation of alkaline phosphatase (ALP) activity and alizarin red S staining. Cells from the three groups were co-cultured with CHA granules, respectively to obtain the tissue-engineered bone. MTT assay and fluorescence microscopy were employed to assess cell proliferation and adhesion. The expression of osteogenic and angiogenic related genes and proteins were evaluated at 7, 14, 21, and 28 days post osteoinduction in cell culture alone and cell co-culture with CHA, respectively using RT-PCR and ELISA. RESULTS: The hVEGF165 gene was transfected into BMSCs successfully. Higher ALP activity and more calcified nodules were found in the hVEGF-BMSCs group than in the control groups (p < 0.001). Cells attached and proliferated in CHA particles. Both cells cultured alone and cells co-culture with CHA expressed more osteogenic and angiogenic related genes and proteins in the hVEGF-BMSCs group compared to the GFP-BMSCs and BMSCs groups (p < 0.05). CONCLUSION: High expression of hVEGF165 in BMSCs potentially promote the osteogenic potential of BMSCs, and synergically drive the expression of other osteogenic and angiogenic factors. hVEGF-BMSCs co-cultured with CHA expressed more osteogenic and angiogenic related factors, creating a favorable microenvironment for osteogenesis and angiogenesis. Also, the findings have allowed for the construction of a CHA-hVEGF-BMSCs tissue-engineered bone.

Modeling Vehicle Dynamics Based on Modelica

Shuguang Feng,Jifeng He,Lichen Zhang 보안공학연구지원센터 2013 International Journal of Multimedia and Ubiquitous Vol.8 No.3

Fault analysis of CNC equipment based on DEMATEL/ISM/ANP

Sun Shuguang,Zhou Wenjie,Zhang Meng,Liu Xiyu,Mou Xiaowan 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.8

To make a reasonable reliability improvement strategy for CNC equipment, it is necessary to clearly understand the fault relation characteristics and the weak links of reliability. While the fault complexity of CNC equipment makes the fault relation characteristics unclear, it is very difficult to determine the weak link of reliability. Therefore, a fault analysis method for CNC equipment based on decision-making and trial evaluation laboratory (DEMATEL)/ interpretive structure modeling (ISM)/analytic network process (ANP) is proposed in this study to describe the relationship between CNC equipment faults accurately and identify reliability weaknesses. First, the fault mechanism was analyzed by the fault phenomenon, and the fault factors of the CNC equipment were identified in view of the system. Second, DEMATEL/ISM/ ANP method was adopted to integrate the interaction direction and intensity between the failure factors, hierarchical structure of the factors, and their relative importance, and a hierarchical network structure model for CNC equipment fault factors was built. Finally, according to the analysis results of the aforementioned model, the fault factors of the CNC equipment were divided into drive, link, dependence, and independent fault factors, and the identification of the weak link of reliability was completed. Results show that the proposed method can quantify the fault factors of the CNC equipment and clearly identify the main direction of its reliability improvement.

Adaptive Differential Evolution-Based Distributed Model Predictive Control for Multi-UAV Formation Flight

Boyang Zhang,Xiuxia Sun,Shuguang Liu,Xiongfeng Deng 한국항공우주학회 2020 International Journal of Aeronautical and Space Sc Vol.21 No.2

The complicated formation flight for multi-unmanned aerial vehicles is a challenge, especially when multi-mission requirements are taken into account. This paper studies the adaptive differential evolution-based distributed model predictive control approach to deal with the multi-unmanned aerial vehicle flight achieving obstacle/collision avoidance and formation keeping simultaneously in the complex environment. Specifically, the distributed model predictive controller is designed to achieve stable flight for each unmanned aerial vehicle as well as taking the state and input saturation into account, where the local optimization problem is solved by the adaptive differential evolution algorithm. Besides, the adaptive adjustment to the prediction horizon for the model predictive controller is introduced, while the asymptotic convergence of the rolling optimization is analyzed as well. Finally, simulation examples are provided to illustrate the validity of the proposed control structure.

Fault Diagnosis for Conventional Circuit Breaker Based on One-Dimensional Convolution Neural Network

Sun Shuguang,Zhang Tingting,Wang Jingqin,Yang Feilong 대한전기학회 2023 Journal of Electrical Engineering & Technology Vol.18 No.3

The vibration signal generated by the operating mechanism of conventional circuit breaker contains abundant mechanical state information. Aiming at traditional fault diagnosis methods that need to realize signal feature extraction based on feature selection, a fault diagnosis model based on one-dimensional convolutional neural network is proposed. In the diagnosis model, multiple convolutional neural networks are designed according to the type and degree of faults, and the network is set as a large convolutional kernel to enlarge the receptive field region; the raw vibration signal is used as the model input for training, and the corresponding fault type and degree are output after hierarchical diagnosis. The experimental results show that the model can automatically extract the fault signal features, effectively complete the fault diagnosis of the contact system for the conventional circuit breaker, and has good generalization ability. The model in this paper has a higher comprehensive diagnosis recognition rate compared with other methods, reaching 98.84%.

Formation Control of Multiple UAVs Incorporating Extended State Observer-Based Model Predictive Approach

Boyang Zhang,Xiuxia Sun,Shuguang Liu,Xiongfeng Deng 한국항공우주학회 2019 International Journal of Aeronautical and Space Sc Vol.20 No.4

This paper studies the extended state observer-based state space predictive control approach to deal with the multiple unmanned aerial vehicle formation flight with unknown disturbances. The distributed control problem for a class of multiple unmanned aerial vehicle systems with reference trajectory tracking and disturbance rejection is formulated. Firstly, a local distributed controller is designed by using the state space predictive control approach based on an error model to achieve stable tracking. Then, a feedforward compensation controller is introduced by using the extended state observer to estimate and compensate disturbances and improve the ability of anti-interference. Besides, the bounded stability of the designed extended state observer is analyzed as well. Finally, the simulation examples are provided to illustrate the validity of the proposed control structure.

Adaptive Differential Evolution-based Receding Horizon Control Design for Multi-UAV Formation Reconfiguration

Boyang Zhang,Xiuxia Sun,Shuguang Liu,Xiongfeng Deng 제어·로봇·시스템학회 2019 International Journal of Control, Automation, and Vol.17 No.12

The complicated and constrained reconfiguration optimisation for unmanned aerial vehicles (UAVs) is a challenge, particularly when multi-mission requirements are taken into account. In this study, we evaluate the use of the adaptive differential evolution-based centralised receding horizon control approach to achieve the formation reconfiguration along a given formation group trajectory for multiple unmanned aerial vehicles in a three-dimensional (3D) environment. A rolling optimisation approach which combines the receding horizon control method with the adaptive differential evolution algorithm is proposed, where the receding horizon control method divides the global control problem into a series of local optimisations and each local optimisation problem is solved by an adaptive differential evolution algorithm. Furthermore, a novel quadratic reconfiguration cost function with the topology information of UAVs is presented, and the asymptotic convergence of the rolling optimisation is analysed. Finally, simulation examples are provided to illustrate the validity of the proposed control structure.

Penalized relative error estimation of functional multiplicative regression models with locally sparse properties

Fan Ruiya,Zhang Shuguang,Wu Yaohua 한국통계학회 2022 Journal of the Korean Statistical Society Vol.51 No.3

Based on functional relative errors, we develop a functional penalized smooth least absolute relative error (FPSLARE) criterion for locally sparse functional multiplicative regression models. Under some mild conditions, we establish the oracle properties of FPSLARE estimators, including the consistency of model selection and the asymptotic normality for the estimator. In addition, numerical studies and a real data analysis are carried out to evaluate the performance of the proposed approaches.

Energy Evolution of Rock under Different Stress Paths and Establishment of a Statistical Damage Model

Wenbo Liu,Shuguang Zhang,Boyi Sun 대한토목학회 2019 KSCE Journal of Civil Engineering Vol.23 No.10

In consideration of the influence of energy dissipation on the rock compression process, the traditional elastic stress-strain relationship was improved by adding the energy release rate. The microintensity of the rock was assumed to satisfy the Weibull distribution. The improved stress-strain relationship was transformed into a triaxial stress-strain model in consideration of the loading damage combined with mesodamage mechanics. The characteristic points of the stress-strain curve and the experimental data were utilized to calculate the distribution parameters of the rock under different conditions. The model curve was compared with the experimental data. Results showed that the stress-strain curve of the rock has peak points in the conventional triaxial compression test, but the radial peak of the rock was not evident in the unloading test. The energy of the rock under the loading path was smaller than that under the unloading path. The model curve exhibited a high degree of fitting with the experimental data, and its correlation coefficient was relatively large (> 0.90), which indicated that the model can clearly represent the actual damage and evolution law of the surrounding rock. Furthermore, the established model can also reflect the rock’s stress-strain relationship, which can serve as a practical guide for relevant applications. Finally, the distribution parameters also reflected the evolution law of rock energy and provided a method for the assessment of rock energy and damage trend.