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Vibration simulation of a multi-story high-speed railway station
Gao, Mangmang,Xiong, Jianzhen,Xu, Zhaojun Techno-Press 2010 Interaction and multiscale mechanics Vol.3 No.4
Station is an important building in high-speed railway, and its vibration and noise may significantly affect the comfort of waiting passengers. A coupling vibration model for train-structure system is established to analyze and evaluate the vibration level of a typical waiting hall under dynamic train load. The motion of a four-axle vehicle with two suspension system is modeled in multi-body dynamics with linear springs and dampers employed. The station is modeled as a whole finite element structure which is 113 m in longitudinal and 163.5 m in lateral, and the stiffness of the station foundation is considered. According to the assumptions that both wheel and rail are rigid bodies and keep contact to each other in vertical direction, and the wheel/rail interaction and displacement coordination in horizontal direction is defined by the simplified Kalker creep theory, the vehicle spatial vibration model has 27 degrees-of-freedom. An overall analysis procedure is made of the train moving through the station, by which the dynamic responses of the train and the station are calculated. According to the comparison between analysis and test results, the actual connection status between different parts of the station is estimated and the vibration level of the waiting hall is evaluated.
Molecular dynamics simulation of nanoindentation influence of indenter velocity on 3C-SiC ceramics
Yu Dongling,Liu Dongliang,Yi Jiaqi,Zhou Jianzhen,Wu Nanxing 한양대학교 청정에너지연구소 2023 Journal of Ceramic Processing Research Vol.24 No.2
To investigate the effect of nanoindentation velocity on dislocation nucleation, development and elastic deformation of 3C-SiCceramic specimens, the nanoindentation loading process of 3C-SiC ceramic specimens under a diamond indenter is simulated. The molecular dynamics models of diamond indenter and 3C-SiC amorphous layer are constructed, and the nanoindentationconditions such as potential function, relaxation synthesis and time step are optimized. The dislocation analysis method andthe identify diamond structure method are used to analyze the internal structure change of the specimen and the dislocationgeneration, change and transfer of different positions after nanoindentation simulation. It is found that with the increase ofindenter velocity, the elastic threshold decreases and the plasticity increases, and tends to be stable at a certain stage. The loadfluctuation tends to be flat, the total amount of dislocation generated continues to decrease, and the diffusion rate of dislocationslows down. The length of 1/2<110> and 1/6<112> type dislocation becomes shorter, indentation formation of the 'lotus' shapemore regularly. The elastic-plastic threshold of 3C-SiC ceramic material also changes with the change of indenter velocity, andthe dislocation formation rate and total amount also affect while show a certain regularity.
Sliding Mode Control for Nonlinear Discrete Networked Cascade Control Systems With Uncertain Delay
Zhaoping Du,Zhilin Zou,Hui Ye,Jianzhen Li 제어·로봇·시스템학회 2023 International Journal of Control, Automation, and Vol.21 No.12
In this paper, the problems of modeling and sliding mode control for a class of nonlinear discrete networked cascade control systems (NCCSs) are studied. Firstly, a class of discrete networked cascade control systems with nonlinear disturbance is considered, the sliding mode control is introduced and the model of the system is established. Based on this model and the Lyapunov functional method, the state feedback primary controller and the sliding mode secondary controller for this system are co-designed. Finally, an example of a thermal power plant is given to illustrate the effectiveness of the proposed co-design method. The main advantages are that the sliding mode control is introduced into cascade control system (CCS) and the design method of sliding mode controller for this system is proposed for the first time. On the premise of ensuring the stability of the system, it can be driven to the sliding mode surface in a limited time, and remain on the sliding mode surface in all subsequent times. The method can achieve better results and be applied to the corresponding industrial system with networked cascade control structure.
Jieguang Song,Yue Liu,Chunxiao Wu,Xueqing Yang,Yipeng Gong,Jianzhen Huang,Chunyan He,Huihui Luo,Aixia Chen 한양대학교 세라믹연구소 2020 Journal of Ceramic Processing Research Vol.21 No.1
Cermet application is extensive because it retains the characteristics of ceramic materials and has the advantages of metalmaterials. In this paper, alumina/aluminum cermet materials were prepared through powder metallurgy method. Theinfluence of raw material formula on the properties of alumina/aluminum cermet was investigated on the basis that ceramicmaterials have good wear resistance and high thermal conductivity. Results show that when the mass ratio of alumina toaluminum is 1:3, the prepared cermet samples have excellent properties, highest density, and uniform distribution ofaluminum and alumina. MgO addition exhibits better effect, higher degree of densification, and renders higher hardness andstrength for the sample as compared with SiO2 and Y2O3 addition. The sintered cermet with composite powder prepared viaprecipitation has better properties and higher densities and surface hardness than that prepared via the ball mill method. Therelative density was 97.1%, surface hardness was 875 HV, and electric resistance was 0.0169 Ω·m.
Yue Liu,Xueqing Yang,Kangliang Peng,Qiong Wang,Jianzhen Huang,Zilin Zhang,Jiang Lu,Hao Xu,Jieguang Song,Lin Chen 한양대학교 세라믹연구소 2019 Journal of Ceramic Processing Research Vol.20 No.4
Yttrium aluminum garnet (YAG), which possesses excellent properties, is investigated and applied. The sintering technology of YAG porous ceramics is optimized. Results show that the porosity initially increases and then decreases with an increase of increasing temperature rate, the porosity are decreased with an increase of removing carbon temperature, the porosity are decreased with an increase of sintering temperature, the porosity are decreased with an increase of holding time. Meanwhile, the compressive strength constantly exhibits an opposite tendency. The optimization of the sintering technology of YAG porous ceramics is based on porosity and compressive strength. A good sintering technology are an increasing temperature rate of 8 oC/min, a removing carbon temperature of 800 oC, removing carbon time of 1 h, a sintering temperature of 1450 oC and holding time of 2 h. The porosity of the prepared YAG porous ceramics is 57.4%, and the compressive strength is 8.89 MPa.
Ruptured Spinal Dermoid Cysts with Lipid Droplets into the Syrinx Cavity : Reports of Fourteen Cases
Cheng, Cheng,Li, Rong,Gao, Haihao,Tao, Benzhang,Wang, Hui,Sun, Mengchun,Gao, Gan,Wang, Jianzhen,Shang, Aijia The Korean Neurosurgical Society 2022 Journal of Korean neurosurgical society Vol.65 No.3
Objective : Dermoid cysts are uncommon in spinal cord tumors, and the phenomenon of their spontaneous rupture into the syrinx cavity is quite rare. We aimed to analyze the imaging characteristics and etiologies, and propose some surgical strategies, for this uncommon phenomenon. Methods : We retrospectively reviewed 14 cases with spinal dermoid cysts that ruptured into the cervical and thoracic syrinx cavity. There were six male and eight female cases, aged 21 to 46 years, who had lipid droplets in the syrinx cavity from C1 to L3. The dermoid cysts were always located at the conus. Based on patients' complaints, clinical manifestations, and imaging results, we adopted tumor excision and/or syrinx cavity aspiration in one stage or multiple stages. Results : Three patients had only a syrinx cavity aspiration surgery due to a history of dermoid cyst excision. Eight patients had dermoid cyst resection and syrinx cavity aspiration in one stage. One patient was operated upon in two stages due to the development of new symptoms at nine months follow-up. Two patients underwent only tumor resection since they did not show similar symptoms or signs caused by the cervicothoracic syrinx. The axial magnetic resonance imaging indicated that the lipid droplets were always not at the center but were eccentric. The clinical effect was satisfactory during the follow-up period in this group. Conclusion : The lipid droplets filled the spinal syrinx cavity, not entirely confined to the central canal. Based on the chief complaints and associated signs, we adopted different surgical strategies and had satisfactory clinical results.
Effect of JAK-STAT pathway in regulation of fatty liver hemorrhagic syndrome in chickens
Zhu, Yaling,Mao, Huirong,Peng, Gang,Zeng, Qingjie,Wei, Qing,Ruan, Jiming,Huang, Jianzhen Asian Australasian Association of Animal Productio 2021 Animal Bioscience Vol.34 No.1
Objective: To explore the molecular mechanisms of fatty liver hemorrhagic syndrome (FLHS) in laying hens, an experiment was conducted to reveal the differences in histopathological observation and gene expression between FLHS group and normal group. Methods: We compared the histopathological difference using hematoxylin and eosin staining and proceeded with RNA sequencing of adipose tissue to search differentially expressed genes and enriched biological processes and pathways. Then we validated the mRNA expression levels by real-time polymerase chain reaction and quantified protein levels in the circulation by enzyme-linked immunosorbent assay. Results: We identified 100 differentially expressed transcripts corresponding to 66 genes (DEGs) were identified between FLHS-affected group and normal group. Seven DEGs were significantly enriched in the immune response process and lipid metabolic process, including phospholipase A2 group V, WAP kunitz and netrin domain containing 2, delta 4-desaturase sphingolipid 2, perilipin 3, interleukin-6 (IL-6), ciliary neurotrophic factor (CNTF), and suppressor of cytokine signaling 3 (SOCS3). And these genes could be the targets of immune response and be involved in metabolic homeostasis during the process of FLHS in laying hens. Based on functional categories of the DEGs, we further proposed a model to explain the etiology and pathogenesis of FLHS. IL-6 and SOCS3 mediate inflammatory responses and the satiety hormone of leptin, induce dysfunction of Jak-STAT signaling pathway, leading to insulin resistance and lipid metabolic disorders. Conversely, CNTF may reduce tissue destruction during inflammatory attacks and confer protection from inflammation-induced insulin resistance in FLHS chickens. Conclusion: These findings highlight the therapeutic implications of targeting the JAK-STAT pathway. Inhibition of IL6 and SOCS3 and facilitation of CNTF could serve as a favorable strategy to enhance insulin action and improve glucose homoeostasis, which are of importance for treating obesity-related disorders for chickens.