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An Investigation on Optimal Initial Self-Stress Design of Tensegrity Grid Structures
Xiaodong Feng 한국강구조학회 2018 International Journal of Steel Structures Vol.18 No.3
To achieve the optimal feasible force density vector of a given geometry confi guration tensegrity grid structure, an effi cient procedure is presented for optimal initial self-stress design of tensegrity grid structures by consecutively solving two linear homogeneous systems in conjunction with a minimization problem. The nonlinear constrained optimization algorithm, known as the Interior-Point Method (I-PM), is utilized to obtain the minimal solution, leading to a set of force densities which guarantee the non-degeneracy condition of the force density matrix. The evaluation of the eigenvalues of tangent stiff ness matrix is also introduced to check the geometric stability of the tensegrity grid structures. Finally, three numerical examples have been investigated comprehensively to prove the capability of the proposed method in optimal initial self-stress design of tensegrities. Furthermore, division of number of member group has been discussed in detail for the purpose of demonstrating the effi ciency of the proposed method in seeking initial force densities of tensegrity grid structures.
Yanmei Feng,Zhiqiang Wang,Yunfeng Yang,Xiang-Feng Wu,Xiaodong Gong,Yajian Liu,Yufei Li,Zuo-Lin Cao,Chao Wang,Xin Tong 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2018 NANO Vol.13 No.7
The Ag2SO3/NaNbO3 hybrids have been fabricated via a facile method at room temperature. Several methods such as X-ray diffraction, UV-Vis diffuse reflectance spectroscopy, scanning electron microscopy, electrochemical impedance spectroscopy and X-ray photoelectron spectroscopy were used to characterize the samples. Moreover, the photocatalytic activity of the samples was assessed by degradation of rhodamine B and methyl orange under the visible light illumination. Experimental results indicated the photocatalytic degradation efficiency of the as-fabricated hybrids was first increased and then decreased with increasing the dosage of NaNbO3. When the molar ratio of Ag2SO3 to NaNbO3 was 1:0.7, the as-fabricated composites had the best photodegradation efficiency of 96.4% in 30 min for rhodamine B and 97.1% in 60 min for methyl orange, respectively. These were obviously higher than that of pure samples. Furthermore, Ag2SO3 was conjugated with NaNbO3 via chemical-bonds rather than physical contact. In addition, the possible photocatalytic degradation mechanism was also provided and the main roles during the process of photocatalytic degradation were played by holes.
Xiaodong Yu,Yanan Feng,Yan Zhao,Dianbin Huang,Jianhua Jiao 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.12
Taking the hydrostatic support of the tiltable oil pad double rectangular cavity as the object, the fluid-thermal-solid coupling deformation analysis of the friction pair is carried out, and the three-dimensional morphology of the micro-gap oil film is obtained. An oil film thickness test device is built to verify the rationality of the numerical simulation method. It is found that the elastic deformations of rotational workbench and base under extreme loads are both concave deformations, the thermal deformations are both convex deformations, and the maximum thermal deformation is mainly concentrated on the outer oil sealing edge. The deformation of the downstream side oil sealing edge is higher than that of the reverse side oil sealing edge. The minimum oil film thickness is the minimum distance between the downstream side oil sealing edge and the lower surface of the hydrostatic guideway of the rotational workbench, where tribological failure is prone to occur.
( Feng Wang ),( Xiaodong Tian ),( Chunxin Yang ),( Yinmo Yang ) 대한간학회 2020 춘·추계 학술대회 (KASL) Vol.2020 No.1
Aims: Cancer stem cells (CSCs) indicate multipotent cells exhibiting self-renewal capacity, multilineage differentiation ability and high carcinogenesis, and are closely related to tumor growth, metastasis, recurrence and chemoresistance. As tumorigenic drivers, CSCs should be effectively targeted to achieve long-lasting therapeutic responses. This study aimed to explore the mechanism of the novel Tripterygium wilfordii Hook F (TWHF) extract Demethylzeylasteral (ZST93) on inhibiting human pancreatic CSCs. Methods: Serum-free floating culture system was used to isolate CSCs. CCK-8 assay was used to evaluate the chemosensitivity. Apoptosis was evaluated by flow cytometry. Autophagy level was evaluated by transmission electron microscopy and immunofluorescence. The activity levels of caspase-3, ERK1/2 and Akt/mTOR pathways were determined by Western blot. Results: Tumorspheres had differentiation ability and stem celllike properties. ZST93 could inhibit the number and diameter of tumorspheres. ZST93 could induce apoptotic cell death in pancreatic CSCs at high concentrations, but not at low concentrations. The apoptosis induced by ZST93 was associated with the significant up-regulation of active caspase-3 expression. ZST93 could induce autophagic cell death in pancreatic CSCs at low concentrations, but not at high concentrations. The autophagy induced by ZST93 was associated with the significant up-regulation of p-ERK1/2 and down-regulation of p-Akt and p-mTOR expression. Conclusions: We revealed that ZST93 inhibits pancreatic CSCs through two different mechanisms, low concentrations of ZST93 could induce autophagic cell death by activating ERK1/2 pathway and inhibiting Akt/mTOR pathway, and high concentrations of ZST93 could induce caspase-3-dependent apoptotic cell death. ZST93 is a potential therapeutic agent for developing novel therapeutic strategies in human pancreatic cancer.
Xiaodong Yu,Weicheng Gao,Yanan Feng,Guangqiang Shi,Shihao Li,Minmin Chen,Ruiming Zhang,Junfeng Wang,Wentao Jia,Jianhua Jiao,Ruichun Dai 한국정밀공학회 2023 International Journal of Precision Engineering and Vol.24 No.6
Hydrostatic bearing has the advantages of wide speed range, large bearing capacity, high precision and stability. Hydrostatic-hydrodynamic hybrid bearing can make up for the lack of stiffness of hydrostatic bearing and prevent tribological failure under the condition of high speed and heavy load. Therefore, hydrostatic bearing and hydrostatic-hydrodynamic hybrid bearing have become important bearing parts of high-end computer numerical control (CNC) machine equipment. The research on hydrostatic and hydrostatic-hydrodynamic open a new way for precision improvement of high-end CNC machine equipment. This paper reviews research progress of hydrostatic linear guideway, hydrostatic rest and ram, hydrostatic thrust bearing, hydrostatic-hydrodynamic thrust bearing and hydrostatic-hydrodynamic spindle of high-end CNC machine equipment, and discusses the influence of structure and working parameters on lubrication performance, accuracy and stability of bearing parts. Finally, the future research direction in hydrostatic bearing and hydrostatic-hydrodynamic hybrid bearing are suggested. This review provides a theoretical basis for design and development of high-end CNC machine equipment in the future.
Effect of sintering atmosphere on ferroelectric properties of SBT ferroelectric ceramics
Feng-Qing Zhang,Chunzhen Li,Haiwen Li,Xiaodong Guo,Suhua Fan 한양대학교 세라믹연구소 2018 Journal of Ceramic Processing Research Vol.19 No.2
The effect of sintering atmosphere on the properties of SBT ferroelectric ceramics was studied by sol-gel method and interlayerannealing process. It was found that the sintered samples in oxygen atmosphere had more a-axis-oriented grains and moregrains which are perpendicular to the plane than those in air atmosphere. The Curie temperature of the samples obtained bysintering in oxygen and air atmosphere is Tc = 273 oC and Tc = 265 oC, and the conductivating energy Ea = 0.94 eV and Ea =0.66 eV, respectively. The residual polarization intensity of the samples sintered in air atmosphere is 2Pr = 15.3 μC/cm2, thecorresponding coercive field is Ec = 51 kV/cm; the residual polarization intensity of the sample sintered in oxygen atmosphereis 2Pr = 16.6 μC/cm2, and the corresponding coercive field is about Ec = 45 kV/cm. That is because the samples sintered in theoxygen atmosphere has larger lattice distortion, lower oxygen vacancy concentration and larger a-axis oriented grains, whichare favorable for the increase of the remnant polarization and reduction of the coercive field.
Feng Xiaona,Wang Kaifeng,Yang Ting,Liu Yanhui,Wang Xiaodong 한국유전학회 2022 Genes & Genomics Vol.44 No.4
Background: We have clarified the role of miR-382-3p in chronic thromboembolic pulmonary hypertension (CTEPH), but what is less clear lies in its upstream regulatory mechanism. Objective: To explore the regulation mechanism of GAS5/miR-382-3p axis on CTEPH. Methods: In vitro, we constructed cell models by treating Pulmonary Artery Smooth Muscle Cells (PASMCs) with platelet-derived growth factor-BB (PDGF-BB). The effects of different concentrations of PDGF-BB on the activity of PASMCs were tested by cell counting kit-8 (CCK-8). The upstream lncRNA of miR-382-3p was screened and confirmed through bioinformatics analysis, RNA pull-down, quantitative reverse transcription polymerase chain reaction (qRT-PCR), dual luciferase reporter gene and RNA immunoprecipitation assays. The effects of GAS5/miR-382-3p axis on the viability, migration, and expressions of autophagy- and angiogenesis-related proteins were confirmed by rescue experiments (CCK-8, wound healing and western blot). In vivo, animal models by perfusing autologous blood vessels, the effects of GAS5 overexpression or silencing on the expressions of miR-382-3p, angiogenesis- and autophagy-related genes, mean pulmonary arterial pressure (mPAP) and pulmonary artery wall were determined by biological signal acquisition system, hematoxylin-eosin staining, qRT-PCR and western blot. Results: PDGF-BB dose-dependently promoted PASMCs viability. XIST and GAS5 expressions in PASMCs were affected by the concentration of PDGF-BB, but only GAS5 can be pulled down by miR-382-3p probe. GAS5 targeted miR-382-3p to inhibit the viability and migration of PAMSCs, mPAP in CTEPH rats, pulmonary artery wall thickening and angiogenesis, and promote autophagy. Conclusions: GAS5/miR-382-3p axis is involved in the regulation of pulmonary artery remodeling and autophagy in CTEPH.