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- 저자 : Liangliang Dong (검색결과 5 건)
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Influence of oil pipe corrosion defects on the sealing performance of annular BOP
Liangliang Dong,Yuan Tang,Liuyang Wang 국제구조공학회 2022 Structural Engineering and Mechanics, An Int'l Jou Vol.84 No.3
Due to corrosion defects on the surface of the oil pipe, the sealing performance of the annular blowout preventer (BOP) decreases, and the leakage of toxic and harmful gases such as H2S and SO2 will threaten the safety of operators on the well. Therefore, this paper establishes the FE model for evaluating the sealing performance of BOP-oil pipe corrosion defects, which is based on the rubber large deformation theory and rubber core sealing mechanism, and designs the experiment of BOP sealing performance to verify the accuracy of the FE model. The sealing performance of BOP sealing oil pipe with corrosion defects is studied. The research results show that the sealing performance of BOP is more sensitive to the axial size of corrosion defects. With the increase of oil pipe outer diameter, the critical size of defects increases continuously. The sensitivity of radial and depth dimensions is low, When for 88.9 mm outer diameter oil pipe, the axial critical size of corrosion defect is 20 mm, the radial critical size is 16 mm and the critical depth is 2 mm. Fit the formula between the outer diameter of oil pipe and the piston increment. According to the formula, the operator can calculate the piston stroke increment required by the BOP to complete the sealing when the oil pipe is corroded.
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Research on steady characteristics of human-robot system for preventing elderly falls during walking
Xiao Dong Zhang,Xiaoqi Mu,Liangliang Li,Ahmad Bala Alhassan,Khaled Kadry Hamza 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.9
Due to the ever-increasing demand of caregivers and the high cost of nursing the elderly, researchers have been developing the elderly assistant robots (EARs) for assisting the elderly. To improve the safety of the elderly during walking, the steady characteristics of the EAR are discussed for preventing elderly falls during walking in this paper. Initially, the walking elderly was modeled as an inverted pendulum, and the steadiness region of the human and the general elderly fall conditions were obtained. The dynamics of the human-robot system were derived for preventing the general elderly falls. Also, the steadiness of the human and the robot were analyzed, respectively. Finally, experiments were conducted to verify the effectiveness of the models. The results demonstrated that the system met the requirements of steadiness, and hence, the designed robot could prevent elderly fall during walking. Thus, this study provides a theoretical basis for the effective control and the practical application of the EARs.
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Xianan Dong,Liangliang Kong,Lei Huang,Yong Su,Xuewang Li,Liu Yang,Pengmin Ji,Weiping Li,Weizu Li The Korean Society of Ginseng 2023 Journal of Ginseng Research Vol.47 No.3
Background: As a complication of Type II Diabetes Mellitus (T2DM), the etiology, pathogenesis, and treatment of cognitive dysfunction are still undefined. Recent studies demonstrated that Ginsenoside Rg1 (Rg1) has promising neuroprotective properties, but the effect and mechanism in diabetes-associated cognitive dysfunction (DACD) deserve further investigation. Methods: After establishing the T2DM model with a high-fat diet and STZ intraperitoneal injection, Rg1 was given for 8 weeks. The behavior alterations and neuronal lesions were judged using the open field test (OFT) and Morris water maze (MWM), as well as HE and Nissl staining. The protein or mRNA changes of NOX2, p-PLC, TRPC6, CN, NFAT1, APP, BACE1, NCSTN, and Ab1-42 were investigated by immunoblot, immunofluorescence or qPCR. Commercial kits were used to evaluate the levels of IP3, DAG, and calcium ion (Ca<sup>2+</sup>) in brain tissues. Results: Rg1 therapy improved memory impairment and neuronal injury, decreased ROS, IP3, and DAG levels to revert Ca<sup>2+</sup> overload, downregulated the expressions of p-PLC, TRPC6, CN, and NFAT1 nuclear translocation, and alleviated Aβ deposition in T2DM mice. In addition, Rg1 therapy elevated the expression of PSD95 and SYN in T2DM mice, which in turn improved synaptic dysfunction. Conclusions: Rg1 therapy may improve neuronal injury and DACD via mediating PLC-CN-NFAT1 signal pathway to reduce Aβ generation in T2DM mice.
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Effect of Free Water on the Mechanical Properties and Blast Resistance of Concrete
Ruiyuan Huang,Liangliang Hu,Jian Qin,Dong Jiang,Long Meng 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.8
This study investigates the effect of free water on the mechanical properties and blast resistance of concrete. For this purpose, comparative experiments on saturated and normal concretes subjected to quasi-static compression, cyclic loading–unloading, quasi-static splitting, and dynamic compression are conducted. Thereafter, contact explosion tests are performed on saturated and normal concrete slabs. The results show that free water reduces the blast resistance of concrete slabs. This is primarily because free water alters the mechanical properties of concrete, including its compressive strength, tensile strength, damage evolution rate, and strain rate effect. Therefore, the material parameters of saturated concrete differed from those of normal concrete. It is unreasonable to employ the material parameters of normal concrete for simulating the cracks and damage modes in hydraulic concrete structures subjected to underwater explosions. Then, the material parameters of Holmquist–Johnson–Cook constitutive model for the saturated and normal concrete slabs are determined based on experimental data, respectively. Finally, the numerical simulation of concrete slabs subjected to contact explosions was carried out. The results show that the numerical predictions and the test data both for the saturated and normal concrete slabs subjected to contact explosions were in good agreement.
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