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Partial discharge (PD) is one of the major causes of insulation accidents in oil-immersed transformers, generating a large number of signals that represent the health status of the transformer. In particular, acoustic signals can be detected by sensors to locate the source of the partial discharge. However, the array, type, and quantity of sensors play a crucial role in the research on the localization of partial discharge sources within transformers. Hence, this paper proposes a novel sensor array for the specific localization of PD sources using COMSOL Multiphysics software 6.1 to establish a three-dimensional model of the oil-immersed transformer and the different defect types of two-dimensional models. “Electric-force-acoustic” multiphysics field simulations were conducted to model ultrasonic signals of different types of PD by setting up detection points to collect acoustic signals at different types and temperatures instead of physical sensors. Subsequently, simulated waveforms and acoustic spatial distribution maps were acquired in the software. These simulation results were then combined with the time difference of arrival (TDOA) algorithm to solve a system of equations, ultimately yielding the position of the discharge source. Calculated positions were compared with the actual positions using an error iterative algorithm method, with an average spatial error about 1.3 cm, which falls within an acceptable range for fault diagnosis in transformers, validating the accuracy of the proposed method. Therefore, the presented sensor array and computational localization method offer a reliable theoretical basis for fault diagnosis techniques in transformers.

With the consumption of terrestrial metal resources, deep-sea polymetallic nodule minerals have been widely exploited around the world. Therefore, the environmental impact of deep-sea polymetallic nodule mining cannot be ignored. In this study, for the first time, a field disturbance and observation device, integrated with multiple sensors, is used to simulate the disturbance process of mining on seabed sediments in the polymetallic nodule area of the western Pacific Ocean at a depth of 5700 m. The impact of the process of stroking and lifting on the bottom sediment in the polymetallic nodule area is 30 times higher than that caused by the waves or the current. The time for turbidity to return to normal after the increase is about 30 min, and the influence distance of a disturbance to the bottom bed on turbidity is about 126 m. The time it takes for density to return to normal is about four hours, and the influence is about 1000 m. At the same time, the resuspension of the bottom sediment leads to an increase in density anomaly and salinity. Moreover, suspended sediments rich in metal ions may react with dissolved oxygen in water, resulting in a decrease in the dissolved oxygen content and an increase in ORP. During the observation period, the phenomenon of a deep-sea reciprocating current is found, which may cause the suspended sediment generated by the continuous operation of the mining vehicle to produce suspended sediment clouds in the water near the bottom of the mining area. This could lead to the continuous increase in nutrients in the water near the bottom of the mining area and the continuous reduction in dissolved oxygen, which will have a significant impact on the local ecological environment. Therefore, the way mining vehicles dig and wash in water bodies could have a marked impact on the marine environment. We suggest adopting the technology of suction and ore separation on mining ships, as well as bringing the separated sediment back to the land for comprehensive utilization.

Aiming at the real-time observation requirements in marine science and ocean engineering, based on underwater acoustic communication and satellite communication technology, a seabed real-time sensing system for in-situ long-term multi-parameter observation applications (SRSS/ILMO) is proposed. It consists of a seabed observation system, a sea surface relay transmission buoy, and a remote monitoring system. The system communication link is implemented by underwater acoustic communication and satellite communication. The seabed observation system adopts the “ARM + FPGA” architecture to meet the low power consumption, scalability, and versatility design requirements. As a long-term unattended system, a two-stage anti-crash mechanism, an automatic system fault isolation design, dual-medium data storage, and improved Modbus protocol are adopted to meet the system reliability requirements. Through the remote monitoring system, users can configure the system working mode, sensor parameters and acquire observation data on demand. The seabed observation system can realize the observation of different fields by carrying different sensors such as those based on marine engineering geology, chemistry, biology, and environment. Carrying resistivity and pore pressure sensors, the SRSS/ILMO powered by seawater batteries was used for a seabed engineering geology observation. The preliminary test results based on harbor environment show the effectiveness of the developed system.

A novel gas-sealed capacitive pressure sensor with a temperature compensation structure is reported. The pressure sensor is sealed by Au-Au diffusion bonding under a nitrogen ambient with a pressure of 100 kPa and integrated with a platinum resistor-based temperature sensor for human activity monitoring applications. The capacitance-pressure and capacitance-temperature characteristics of the gas-sealed capacitive pressure sensor without temperature compensation structure are calculated. It is found by simulation that a ring-shaped structure on the diaphragm of the pressure sensor can mechanically suppress the thermal expansion effect of the sealed gas in the cavity. Pressure sensors without/with temperature compensation structures are fabricated and measured. Through measured results, it is verified that the calculation model is accurate. Using the compensation structures with a 900 μm inner radius, the measured temperature coefficient is much reduced as compared to that of the pressure sensor without compensation. The sensitivities of the pressure sensor before and after compensation are almost the same in the pressure range from 80 kPa to 100 kPa.

Single-crystal silicon carbide (SiC)-based pressure sensors can be used in harsh environments, as they exhibit stable mechanical and electrical properties at elevated temperatures. A fiber-optic pressure sensor with an all-SiC sensor head was fabricated and is herein proposed. SiC sensor diaphragms were fabricated via an ultrasonic vibration mill-grinding (UVMG) method, which resulted in a small grinding force and low surface roughness. The sensor head was formed by hermetically bonding two layers of SiC using a nickel diffusion bonding method. The pressure sensor illustrated a good linearity in the range of 0.1–0.9 MPa, with a resolution of 0.27% F.S. (full scale) at room temperature.