Dynamic responses and robustness performance to moving boundary of double-stepped cable during deep-sea mining

Li Yilun,Guo Shuangxi,Guo Yucheng,Yu Xiaoqi,Chen Weimin,Song Jixiang 대한조선학회 2023 International Journal of Naval Architecture and Oc Vol.15 No.-

As the exploration and exploitation of deep-sea oil and gas, along with promising polymetallic nodule&sulfides mining, have been developing toward ultra-deep waters, some innovative concepts of marine cable configuration suitable for ultra-deepwater are proposed, such as stepped cable, hybrid cable and double-stepped cable. For deep-water cables with complex configurations, the structural responses become more complicated due to their non-uniform structural properties. Because the distributed buoyancy modules along cable length might introduce more significant local bending segments. Moreover, the impacts of moving boundary, caused by the motions of top vessel and bottom mining vehicle, should be considered. Through combing the finite element simulations with the hydrodynamic models, the dynamic response analysis approach of ultra-deepwater cables is established in this study. Then the double-stepped cable responses, including axial tension, displacement along with the change of overall configurations caused by moving top vessel and bottom mining vehicle, are calculated. Moreover, wave propagation behaviors during cable response are comprehensively examined, and the influences of non-uniform structural properties on cable response and wave propagation are analyzed using the wave propagation theory of structure with axially varying properties based on the Bessel function. The results show that the presented double-stepped cable can provide suitable configurations during the dynamic response, which has good compliance performance and can effectively buffer its response caused by moving boundary excitation. Finally, we found that the response spatial-temporal evolutions present some interesting phenomena, such as the axially non-uniform characteristics lead to non-monotonic changes in response amplitude and wavelength, with local peaks occurring in the low-tension region, owing to the distributed buoyancy modules, along with axiallyvarying and discontinuous structural properties. And, there exists significant mixed effect coming from both standing waves and traveling waves.

TiO2 nanoparticles anchored on graphene oxide nanosheets as a highly active photocatalyst for decabromodiphenyl ether degradation

Man Yang,Yilun Zou,Lei Ding,Yang Yu,Jinai Ma,Lei Li,Ande Fudja Rafryanto,Jing Zou,Arramel,Haitao Wang 한국탄소학회 2023 Carbon Letters Vol.33 No.5

Decabromodiphenyl ether (BDE209) is a persistent aromatic compound widely associated with environmental pollutants. Given its persistence and possible bioaccumulation, exploring a feasible technique to eradicate BDE209 efficiently is critical for today’s environmentally sustainable societies. Herein, an advanced nanocomposite is elaborately constructed, in which a large number of titanium dioxide ( TiO2) nanoparticles are anchored uniformly on two-dimensional graphene oxide (GO) nanosheets ( TiO2/GO) via a modified Hummer’s method and subsequent solvothermal treatment to achieve efficient photocatalytic degradation BDE209. The obtained TiO2/ GO photocatalyst has excellent photocatalytic due to the intense coupling between conductive GO nanosheets and TiO2 nanoparticles. Under the optimal photocatalytic degradation test conditions, the degradation efficiency of BDE209 is more than 90%. In addition, this study also provides an efficient route for designing highly active catalytic materials.

Structural configurations and dynamic performances of flexible riser with distributed buoyancy modules based on FEM simulations

Chen Weimin,Guo Shuangxi,Li Yilun,Gai Yuxin,Shen Yijun 대한조선학회 2021 International Journal of Naval Architecture and Oc Vol.13 No.1

Flexible risers are usually used as conveying systems to bring ocean resources from sea bed up to onshore. Under ocean environments, risers need to bear complex loads and it is crucial to comprehensively examine riser's configurations and to analyze structural dynamic performances under excitation of bottom vehicle motions, to guarantee structural safe operation and required service lives. In this study, considering a saddle-shaped riser, the influences of some important design parameters, including installation position of buoyancy modules, buoyancy ratio and motion of mining vehicle, on riser's configuration and response are carefully examined. Through our FEM simulations, the spatial distributions of structural tensions and curvatures along of riser length, under different configurations, are compared. Then, the impacts of mining vehicle motion on riser dynamic response are discussed, and structural tolerance performance is assessed. The results show that modules installation position and buoyancy ratio have significant impacts on riser configurations. And, an appropriate riser configuration is obtained through comprehensive analysis on the modules positions and buoyancy ratios. Under this proposed configuration, the structural tension and curvature could moderately change with buoyancy modules and bottom-end conditions, in other words, the proposed saddle-shaped riser has a good tolerance performance to various load excitations.

A new device built to measure the mechanical characters of the double ended tuning Fork

Guo Zhanshe,An Ying,Li Yilun,Wang Jinliang,Fan Shangchun 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.12

A new device is built to measure the mechanical characters of the double ended tuning fork which is used as the sensitive element ofresonant sensor. It is mainly composed of a three dimensional workbench, a force sensor, a servo motor, control circuit and a photodiode. Detailed theoretical analysis is carried out to verify the feasibility of the design and some experiments have been done to test the performanceof the device. Firstly, the calibrated result of the force sensor shows that the applied force possesses good linear relationshipwith the output voltage. Then, zero drift character indicates that the force drift is just 0.1N and the stability performance of the appliedforce is also detected. Finally, the axial force loading test is carried out. In conclusion, the above experiments prove that the designedscheme is right and reliable to measure the mechanical characters of the double ended tuning fork.

Experimental study on shear, tensile, and compression behaviors of composite insulated concrete sandwich wall

Zhang, Xiaomeng,Zhang, Xueyong,Liu, Wenting,Li, Zheng,Zhang, Xiaowei,Zhou, Yilun Techno-Press 2021 Advances in concrete construction Vol.11 No.1

A new type of composite insulated concrete sandwich wall (ICS-wall), which is composed of a triangle truss steel wire network, an insulating layer, and internal and external concrete layers, is proposed. To study the mechanical properties of this new ICS-wall, tensile, compression, and shearing tests were performed on 22 specimens and tensile strength and corrosion resistance tests on 6 triangle truss joints. The variables in these tests mainly include the insulating plate material, the thickness of the insulating plate, the vertical distance of the triangle truss framework, the triangle truss layout, and the connecting mode between the triangle truss and wall and the material of the triangle truss. Moreover, the failure mode, mechanical properties, and bearing capacity of the wall under tensile, shearing, and compression conditions were analyzed. Research results demonstrate that the concrete and insulating layer of the ICS-wall are pulling out, which is the main failure mode under tensile conditions. The ICS-wall, which uses a graphite polystyrene plate as the insulating layer, shows better tensile properties than the wall with an ordinary polystyrene plate. The tensile strength and bearing capacity of the wall can be improved effectively by strengthening the triangle truss connection and shortening the vertical distances of the triangle truss. The compression capacity of the wall is mainly determined by the compression capacity of concrete, and the bonding strength between the wall and the insulating plate is the main influencing factor of the shearing capacity of the wall. According to the tensile strength and corrosion resistance tests of Austenitic stainless steel, the bearing capacity of the triangle truss does not decrease after corrosion, indicating good corrosion resistance.