Anchor damage is one of the main risk factors for the safe operation of submarine cables. Additionally, due to a scour effect induced by seabed currents, submarine cables are prone to exposure or even suspension, increasing the risk of being dragged by anchors. Therefore, it is necessary to study the global response of exposed and suspended submarine cables subjected to anchor dragging. In this study, the tensile and bending stiffnesses of submarine cables are calculated by theoretical methods, and the accuracy of these calculations is verified by establishing a detailed finite element model. Then, the mechanical properties of the submarine cables are equivalently modeled using beam elements, and a large-scale finite element model for exposed and suspended cables under anchor dragging is established. Considering different dragging forces, exposed lengths, spanning lengths, and spanning heights, the overall deformation and mechanical responses of exposed and suspended cables are analyzed separately. The results show that under dragging forces, axial forces are uniformly distributed along exposed and suspended segments, while bending moments concentrate at the central hooking area and the ends of exposed and suspended segments. The influence of dragging force, exposed length, spanning length, and spanning height on the stress and deformation of submarine cables is significant. The results can be used for submarine cable damage assessments caused by anchor dragging.
We report an alumina-encapsulated microcircuit on a diamond anvil for high-pressure and high-temperature electrical conductivity measurement. An alumina thin film was deposited on a diamond anvil as a thermal insulation layer for laser heating, on which a molybdenum film was deposited and photolithographically fabricated to a van der Pauw circuit. The introduction of the alumina layer significantly improves the laser heating performance. This specially fabricated diamond anvil permits us to measure the resistivity of (Mg0.875Fe0.125)2SiO4 at 3450K and 35GPa in a laser-heated diamond anvil cell. We expect to substantially extend the pressure-temperature scale of in situ resistivity measurement.
The 500kV submarine cable route of Hainan Networking System starts from Nanling Village, Jiaowei Township, Xuwen County, Zhanjiang City, Guangdong Province. It crosses the Qiongzhou Strait to Linshi Village, Qiaotou Town, Chengmai County, Hainan Province. Hainan Networking System 500kV AC Submarine Cable is the first ultra-high voltage, large capacity and long-distance cross-sea networking power cable in China. It is 31 km. In this article, there are three main parts. The first part introduces the status of submarine cable monitoring and the BOTDA test principle. The second part is to design a calibration experiment to calibrate the Brillouin temperature coefficient and the Brillouin strain coefficient for the test fiber of the submarine cable. The third part is to design the spatial distribution rate verification experiment of Brillouin optical time domain reflectometry analyzer to ensure the error of equipment and experiment, so that it can be applied in submarine cable in the future.
The helicopter surveillance radar transmitter is characterized by high power and small space,while the helicopter itself can not provide any cooling air.Besides,the size and weight of the air-borne radar transmitter are strictly limited.Therefore,it is difficult to design the lightweight and highly reliable transmitter in the limited space.According to the work environment characteristics of the helicopter surveillance radar transmitter,the overall structure design method of the transmitter is proposed.The key issues of the thermal design,the strength design and the high voltage insulation design are focused.The design result and the final test have proved that the transmitter has good work stability and reliability.The design result can be used as an important reference to the structure design of helicopter radar products.
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