Fuzzy comprehensive performance evaluation method of rolling linear guide based on improved analytic hierarchy process

Yali Ma,Jiayong Wei,Cancan Li,Chen Liang,Guochao Liu 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.7

Aiming at the problem that the multi-objective evaluation of performance and the weighting coefficients of indexes is difficult to find, a fuzzy comprehensive performance evaluation method of rolling linear guide (RLG) is proposed. Considering the static and dynamic indexes, a structure model containing nine weighting coefficients was constructed. The performance evaluation function was established by the compromise programming method and the average power method, while weighting coefficients were determined by the improved analytic hierarchy process (I-AHP); the mathematical model was obtained to evaluate the RLG in a certain application. The evaluation results show that the confidence of the static, dynamic and comprehensive performance of the RLG is 59.21 %, 81.97 %, and 63.34 %, respectively. The feasibility of the method was verified by numerical simulation. This method indicates the pros and cons of the performance of the RLG and also indicates the direction for its optimized design.

Exponential Synchronization of Delayed Neural Networks with Actuator Failure Using Stochastic Sampled-data Control

Ganlei Zhang,Jiayong Zhang,Wei Li,Chao Ge,Yajuan Liu 제어·로봇·시스템학회 2022 International Journal of Control, Automation, and Vol.20 No.2

This paper investigates the exponential synchronization issue for delayed neural networks with stochastic sampling. The variable sampling period of controller is assumed to switch stochastically between different values with given probability. In addition, the actuator failure phenomenon may occur in many actual systems which is taken into account. By using input delay method, the sampling system is converted to the continuous system. Then, a neoteric time-delay Lyapunov-Krasovskii functional (LKF) that contains delay bounds information is constructed and by using reciprocally convex approach, the sufficient conditions are derived to guarantee the exponentially mean-square stable of the delayed neural networks. The corresponding sampled-data controller can be obtained in terms of the solution to linear matrix inequalities (LMIs). Finally, one numerical example is used to illustrate the effectiveness of proposed method.

Decoupling Analysis of Interaction between Tunnel Surrounding Rock and Support in Xigeda Formation Strata

Ping Zhou,Feicong Zhou,Jiayong Lin,Jinyi Li,Yifan Jiang,Bao Yang,Zhijie Wang 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.12

The Xigeda Formation has the characteristics of poor cementation, variable structure, and softening in water. It is prone to lead to failure of the initial support structures, arch collapse, and even roof fall. The key to the problem lies in the exploration of the interaction between surrounding rock and support. Therefore, based on the constraint loss theory of the tunnel face space effect, this paper constructively introduces multiple dependent variables, including the intermediate principal stress, the dilatancy of the surrounding rock, the timeliness of the shotcrete support stiffness, and the water content of the Xigeda formation, to decouple the whole process of the interaction between the surrounding rock and support, and discusses the influence of each variable. The research results show that: i) there is a critical support point in the tunnel under the influence of the unified strength theoretical parameter b and water content, and when the unified strength theoretical parameter b is constant, the critical distance of the support will decrease with the increase of the water content; ii) from the perspective of deformation control, the stress of support structure will increase with the increase of dilatancy angle of Xigeda surrounding rock; iii) considering the hardening characteristics of shotcrete, the initial support stiffness of Xigeda tunnel increases nonlinearly, and the whole process of stress and deformation can be divided into four stages; iv) the combined support structure of section steel and grille has little difference in the deformation control effect of the surrounding rock and the stress of the support structure, but the combined support structure of the grille steel frame is more sensitive to the hardening parameters.

H∞ Synchronization of Uncertain Chaotic Lur’e Systems with Timevarying Delay via Stochastic Sampling

Hanxiao Zhao,Wei Li,Jiayong Zhang,Chao Ge,Yajuan Liu 제어·로봇·시스템학회 2022 International Journal of Control, Automation, and Vol.20 No.4

In this article, the problem of H∞ synchronization for uncertain chaotic systems with time-varying delay controlled by random sampling is considered. The variable sampling period is assumed to switch stochastically between different values with given probability. In addition, the disturbance and the parameter uncertainty that may occur in many actual system are taken into account. With the help of input delay method, the chaotic Lur’e systems (CLSs) with probability sampling is converted to a continuous system. Then, based on the Lyapunov-Krasovskii functional (LKF) theory, a novel LKF is proposed. By using the reciprocal convex method, sufficient conditions are obtained to guarantee the stability of the error system and to reduce the influence of external disturbances under the condition of bounded H∞ norm. By solving a series of linear matrix inequalities (LMIs) which are obtained, the corresponding sampled data controller can be obtained. Finally, a numerical example is used to illustrate the superiority and effectiveness of proposed method.

External Fixation Using Femoral Less Invasive Stabilization System Plate in Tibial Proximal Metaphyseal Fracture

Jingwei Zhang,,Nabil Ebraheim,Ming Li,Xianfeng He,Jiayong Liu,Limei Zhu,Yihui Yu 대한정형외과학회 2015 Clinics in Orthopedic Surgery Vol.7 No.1

Background: The locking plates are often used for internal fixation of closed tibial fractures. The use of a locking plate as an externalfixator is still controversial, particularly for closed fractures. The purpose of this study is to evaluate the results of externalfixation using the femoral less invasive stabilization system (LISS) plate in proximal metaphyseal fractures of the tibia. Methods: We prospectively evaluated 35 patients (26 males and 9 females) with a mean age of 42 years (range, 21 to 62 years)who presented with fresh tibial proximal metaphyseal fractures. According to the AO Foundation and Orthopaedic Trauma Association(AO/OTA) classification, the fractures were identified as type 41-A2 in 18 cases and type 41-A3 in 17 cases, including 25closed fractures and 10 open fractures. The femoral LISS plate was used to fix these fractures, which was placed on the anteromedialaspect of the tibia as an external fixator. The mean follow-up period was 18 months (range, 13 to 22 months). Results: All fractures healed in a mean time of 14 weeks (range, 10 to 20 weeks). There was no case of nonunion, deep infection,and loosening of screws and plates. One month after the appearance of cortical bridging on biplanar radiographs, the locking platewas removed within 3 minutes in the clinic without any difficulty. According to the Hospital for Special Surgery (HSS) knee scoringsystem and American Orthopaedic Foot & Ankle Society (AOFAS) ankle scoring system, the mean HSS score was 91 (range, 85 to100) and 98 (range, 93 to 100), and the mean AOFAS score was 94 (range, 90 to 100) and 98 (range, 95 to 100) at 4 weeks postoperativelyand final follow-up, respectively. Conclusions: For proximal metaphyseal fracture of the tibia, external fixation using the femoral LISS plate is a safe and reliabletechnique with minimal complications and excellent outcomes. Its advantages include ease of performing the surgery, use of a lessinvasive technique, and convenience of plate removal after fracture healing.

Key Parameters Design Method of AGF Method for Metro Connecting Passage in Water-Rich Coastal Area

Feicong Zhou,Ping Zhou,Jinyi Li,Tiancheng Ge,Jiayong Lin,Zhijie Wang 대한토목학회 2022 KSCE JOURNAL OF CIVIL ENGINEERING Vol.26 No.12

Artificial Ground Freezing Method (AGF) is an efficient, environmentally friendly reinforcement method for the construction of metro connecting passage in water-rich and weak stratum. The core of AGF is the design of frozen wall thickness and freezing temperature. In order to obtain the quantitative relationship between the freezing temperature and the frozen wall thickness, this study firstly equates the frozen wall to a rectangular frame mechanical model based on the stress state of the frozen wall formed by AGF. And then the calculation method of frozen wall thickness based on strength conditions is obtained by theoretical estimation. Furthermore, based on the relationship between the strength of the frozen soil and the freezing temperature obtained from the experiment, the freezing temperature and the frozen wall thickness are related to propose a frozen wall thickness design method considering the freezing temperature. In addition, experimental studies revealed that the compressive strength and shear strength of frozen soil increase linearly as the freezing temperature decreases. Secondly, the lower the freezing temperature, the smaller the frozen wall thickness required. Notably, the relationship between the frozen wall thickness and freezing temperature formed by the AGF method can be obtained through the design method proposed in this paper. Taking actual case as an example, when the frozen wall thickness is selected from 1.2 to 2.2 m, the required freezing temperature range is (-5) to (-25)oC. Finally, the feasibility of the designed freezing parameters in the connecting passage construction is verified through numerical simulation and field measurement, which shows that the design method has a promotion prospect.

RGS2 promotes estradiol biosynthesis by trophoblasts during human pregnancy

Tang Chao,Jin Meiyuan,Ma Bingbing,Cao Bin,Lin Chao,Xu Shouying,Li Jiayong,Xu Qiang 생화학분자생물학회 2023 Experimental and molecular medicine Vol.55 No.-

Production of estradiol (E2) by the placenta during human pregnancy ensures successful maintenance of placental development and fetal growth by stimulating trophoblast proliferation and the differentiation of cytotrophoblasts into syncytiotrophoblasts. Decreased levels of E2 are closely associated with obstetrical diseases such as preeclampsia (PE) in the clinic. However, the mechanisms underlying the inhibition of placental E2 biosynthesis remain poorly understood. Here, we report that regulator of G-protein signaling 2 (RGS2) affects E2 levels by regulating aromatase, a rate-limiting enzyme for E2 biosynthesis, by using human trophoblast-derived JEG-3 cells and human placental villus tissues. RGS2 enhanced the protein degradation of the transcription factor heart and neural crest derivatives expressed 1 (HAND1) by suppressing ubiquitin-specific protease 14 (USP14)-mediated deubiquitination of HAND1, resulting in the restoration of HAND1-induced trans-inactivation of the aromatase gene and subsequent increases in E2 levels. However, aromatase bound to RGS2 and repressed RGS2 GTPase activating protein (GAP) activity. Moreover, we observed a positive correlation between RGS2 and aromatase expression in clinical normal and preeclamptic placental tissues. Our results uncover a hitherto uncharacterized role of the RGS2-aromatase axis in the regulation of E2 production by human placental trophoblasts, which may pinpoint the molecular pathogenesis and highlight potential biomarkers for related obstetrical diseases.