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Vibrational behaviour of higher-order cylindrical shells
Longjie Zhang Techno-Press 2023 Advances in concrete construction Vol.15 No.2
Dynamic analysis of a shear deformable shell is investigated with accounting thickness stretching using Hamilton's principle. Through this method, the total transverse is composed into bending, shearing and stretching portions, in which the third part is responsible for deformation along the transverse direction. After computation of the strain, kinetic and external energies, the governing motion equations are derived using Hamilton's principle. A comparative study is presented before presentation of full numerical results for confirmation of the formulation and methodology. The results are presented with and without thickness stretching to show importance of the proposed theory in comparison with previous theories without thickness stretching.
삼온제어와 상하부가열 축열조를 갖는 태양열 시스템의 실증실험
이용걸(Longjie Li),김종현(Jong-Hyun Kim),홍희기(Hiki Hong) 대한설비공학회 2015 대한설비공학회 학술발표대회논문집 Vol.2015 No.11
The verification experiment for a solar thermal system with upper-and-lower heating storage tank and three-temperature-point control was conducted at a laboratory building of Kyung Hee University . Three-temperature-point control uses the temperatures at uppermost storage tank other than at collector and storage tank exits. It was verified whether the setting values used in the device are appropriate. As a result of the experiment, it was turned out that the stratification is enhanced through upper heating and the hot water can be suppied earlier because of rapid increase of the uppermost temperature at the storage tank.
Yang Zhou,Longjie Shi,Gang Ceng,Tiebing Liu,Yang Shi,Zhengwei Chen,Fenglin Wang,Yuefeng Ceng 한양대학교 세라믹연구소 2020 Journal of Ceramic Processing Research Vol.21 No.3
The thickness of glaze is one of the important indicators in the quality evaluation of Longquan celadon. But till now, there isno automatic and non-destructive method to measure it. In order to satisfy this demand, an automated method has beenproposed to measure the glaze thickness based on optical coherence tomography (OCT) technique. According to themorphological characteristics of celadon glaze in OCT image, the proposed method locates the upper and lower boundariesof the glaze layer, then the glaze thickness is automatically calculated after the axial resolution calibration of the OCT imagesfor different categories of Longquan celadon. In the experiment, the glaze OCT images of 6 different categories of Longquanceladon were applied in the glaze thickness estimation. By comparing with the physical measuring result, this method is provedto be able to measure the glaze thickness rapidly and non-destructively and the performance is enough to meet the demandof the industrial application.
Sliding Mode Based Nonlinear Load Frequency Control for Interconnected Coupling Power Network
Gafary Mahmoud,Yong Chen,Longjie Zhang,Meng Li 제어·로봇·시스템학회 2022 International Journal of Control, Automation, and Vol.20 No.11
This paper investigates the nonlinear load frequency control (NLFC) issue in the interconnected coupling power network (ICPN), which includes a wind turbine, photovoltaic (PV), and second-order turbine governor systems. The main target of proposed scheme is to zero out the frequency deviations and preserve the consumption of batteries energy at the desired standards for the ICPN, which is divided into control areas, where each area is defined by an equivalent generation subsystem. Firstly, a super twisting sliding mode control (STWSMC) is designed for the secondary control area to make the state converge quickly. Secondly, to make sure the stability of the system states, the proportional integral (PI) technique is used for the initial phase control. Furthermore, the stability analysis shows that the asymptotic convergence can be recognized by pressuring the state of the power system on an appropriately designed sliding surface. Finally, the simulation results confirm the effectiveness of the proposed methodology.
FHOSM Tolerant Control for Networked Control Systems with Disturbances and Faults
Gafary Mahmoud,Yong Chen,Longjie Zhang,Meng Li 제어·로봇·시스템학회 2021 International Journal of Control, Automation, and Vol.19 No.9
This paper investigates the networked control system (NCS) with faults and disturbances which affect both actuator and sensor. A fast high-order sliding mode (FHOSM) controller is proposed to compensate for actuator faults and sensor disturbances, which is constructed based on the estimated information of the NCS. Accordingly, an adaptive observer with multi-stage is designed to estimate the states and sensor disturbances and protect the NCS from actuator faults. Furthermore, a new sliding function is assembled to realize the finite-time convergence of system states. The stability of the system with the suggested procedure is illustrated by the stability analysis underneath the designed control law. Finally, the simulation results are implemented and confirm the effectiveness of the proposed method in defending the system against both issues and inhibiting system failures.
Lin Jialiang,Wang Longjie,Wu Yuhao,Xiang Qian,Zhao Yongzhao,Zheng Xuanqi,Jiang Shuai,Sun Zhuoran,Fan Dongwei,Li Weishi 생화학분자생물학회 2024 Experimental and molecular medicine Vol.56 No.-
Intervertebral disc degeneration (IDD) is an important pathological basis for degenerative spinal diseases and is involved in mitophagy dysfunction. However, the molecular mechanisms underlying mitophagy regulation in IDD remain unclear. This study aimed to clarify the role of DJ-1 in regulating mitophagy during IDD pathogenesis. Here, we showed that the mitochondrial localization of DJ-1 in nucleus pulposus cells (NPCs) first increased and then decreased in response to oxidative stress. Subsequently, loss- and gain-of-function experiments revealed that overexpression of DJ-1 in NPCs inhibited oxidative stress-induced mitochondrial dysfunction and mitochondria-dependent apoptosis, whereas knockdown of DJ-1 had the opposite effect. Mechanistically, mitochondrial translocation of DJ-1 promoted the recruitment of hexokinase 2 (HK2) to damaged mitochondria by activating Akt and subsequently Parkin-dependent mitophagy to inhibit oxidative stress-induced apoptosis in NPCs. However, silencing Parkin, reducing mitochondrial recruitment of HK2, or inhibiting Akt activation suppressed DJ-1-mediated mitophagy. Furthermore, overexpression of DJ-1 ameliorated IDD in rats through HK2-mediated mitophagy. Taken together, these findings indicate that DJ-1 promotes HK2-mediated mitophagy under oxidative stress conditions to inhibit mitochondria-dependent apoptosis in NPCs and could be a therapeutic target for IDD.
JONG HYUN KIM,이욱재,LongJie Li,김철,홍희기 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.7
In the present study, we investigated the effects of a combined system-control method in a solar thermal system; specifically, prevention of temperature reversal plus a reduced circulation rate. A 3-way valve is adopted as a remedy of the temperature reversal in the water storage tank and a 2-stage flowrate is implemented as the flowrate control strategy. To evaluate the effects, we perform five experiments and TRNSYS based simulations with a carefully developed system-control algorithm. As the main result, we experimentally validated that a 3-way valve is effective for the prevention of temperature reversal and a 2-stage flowrate extends the solar energy collection time. Annual simulation results show that the proposed combined method improves the system performances (1.9%p increase of collector efficiency, 2.2%p increase of solar fraction, and 5.3% additional collected energy) compared to the conventional forced circulation system. Our results should be applied to the water storage tank proposed in this study.
Heat kernel estimates for Dirichlet fractional Laplacian with gradient perturbation
Peng Chen,Renming Song,Longjie Xie,Yingchao Xie 대한수학회 2019 대한수학회지 Vol.56 No.1
We give a direct proof of the sharp two-sided estimates, recently established in \cite{C-K-S-1, P-R}, for the Dirichlet heat kernel of the fractional Laplacian with gradient perturbation in $C^{1, 1}$ open sets by using Duhamel's formula. We also obtain a gradient estimate for the Dirichlet heat kernel. Our assumption on the open set is slightly weaker in that we only require $D$ to be $C^{1,\theta}$ for some $\theta\in (\alpha/2, 1]$.
Yanxu Zhang,Yinli Bi,Huihui Shen,Longjie Zhang 한국미생물·생명공학회 2020 Journal of microbiology and biotechnology Vol.30 No.6
Land subsidence induced by underground coal mining leads to severe ecological and environmental problems. Arbuscular mycorrhizal fungi (AMF) have the potential to improve plant growth and soil properties. We aimed to assess the effects of AMF on the growth and soil properties of sea buckthorn under field conditions at different reclamation times. Inoculation with AMF significantly promoted the survival rate of sea buckthorn over a 50-month period, while also increasing plant height after 14, 26, and 50 months. Crown width after 14 months and ground diameter after 50 months of inoculation treatment were significantly higher than in the uninoculated treatment. AMF inoculation significantly improved plant mycorrhizal colonization rate and promoted an increase in mycelial density in the rhizosphere soil. The pH and electrical conductivity of rhizosphere soil also increased after inoculation. Moreover, after 26 and 50 months the soil organic matter in the inoculation treatment was significantly higher than in the control. The number of inoculated soil rhizosphere microorganisms, as well as acid phosphatase activity, also increased. AMF inoculation may play an active role in promoting plant growth and improving soil quality in the long term and is conducive to the rapid ecological restoration of damaged mining areas.