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In the water-rich karst regions, high water and mud outbursts are common geological disasters in tunnel construction. To ensure the safe and smooth construction of tunnel projects, it is necessary to consider anti-water pressure, water inrush prevention and geological disasters during the design of tunnels. Based on the Yongfutun Tunnel Project, this paper studies the application and effect of radial grouting and curtain grouting, which involves those in high-water-pressure tunnels under double-layer support conditions. To obtain the effects and parameters of radial grouting and curtain grouting, the influences of different grouting ranges on the tunnel’s surrounding rocks and supporting structures were analyzed and the finite difference method was adopted. The results show that the radial grouting of the surrounding rock can notably improve the initial support of the tunnel, but the impact is less obvious when the grouting range exceeds 4 m. The design of radial grouting is recommended to be 4.0 m to 4.5 m. Curtain grouting can effectively reduce the external water pressure of the tunnel lining. The external water pressure of the grouting area is 23% greater than that without curtain grouting. Curtain grouting can slow down the infiltration of external water pressure. This is beneficial to the stress of the tunnel lining structure, but the improvement in initial support force is slight. Moreover, curtain grouting improves the safety reserve of the secondary lining by strengthening the self-stability ability of the surrounding rock. Meanwhile, the double-layer primary support can effectively share the external water pressure and surrounding rock pressure. This study provides a certain reference for the lining design of high-water-pressure tunnels.

Abstract This paper presented a novel method of dissipating solar photovoltaic heat based on the technology of micro-heat-pipe array and the utilization of photovoltaic-cell waste heat. This novel technology solved the problems of low PV electrical efficiency and thermal failure caused by high cell temperature, greatly increased the comprehensive utilization efficiency of solar energy, and extended the service life of photovoltaic modules. One-year experiments were conducted to investigate the electrical and thermal performance of a forced-circulation, household-type photovoltaic/thermal system based on micro-heat-pipe array in Beijing, China. Test results showed that on the four typical days in different seasons, the average electrical efficiencies were 13.76%, 11.92%, 13.71%, and 14.65%; the average thermal efficiencies were 31.62%, 33.07%, 24.99%, and 17.24%; and the average total efficiencies were 45.38%, 44.99%, 38.70%, 31.89%, respectively. The system met the demand of power supply on sunny days and the demand of hot water between March and November, except in cloudy days. These experimental results can provide basis and reference for practical applications of the system.

Abstract In demand of remote control of photographic equipment, we design a remote-control system for photographic equipment. The system uses the stabilizer as the platform to realize the transmission of the state parameters of photographic equipment and stabilizer to the mobile device by the self-designed wireless communication interaction protocol and control protocol. It can also control the camera equipment and stabilizer according their states. The test results show that the remote-control system of the photographic equipment designed in this paper meets the design requirements, facilitates the user’s surveillance filming work and harmonizes the user experience.

Abstract In a passive nuclear plant, the main control room must provide self-support functions for 72 h after an accident occurs. In this isolation mode, the heat generated by indoor occupants and equipment should be removed by using concrete walls that are 610 mm thick, and the finned ceiling made of concrete should maintain thermal habitability. However, the finned ceiling design has not been studied in normal buildings, and the cooling storage effect of plate-shaped fins is usually ignored during the design phase. In this study, a novel parametric resistance–capacitance thermal network is proposed to simulate the thermal performance of different fin-plate layout forms in the case of an accident. An experiment was conducted on a 1200 mm × 1200 mm × 610 mm fin-concrete module for 72 h to validate the model under constant air temperature conditions. Based on the model, multi-objective optimization was conducted to obtain optimal solution sets by using a radial basis function approximation model. The results show that the optimal performance indicators can be classified into unsteady and quasi-steady states, in which the dominant factors for heat transfer include the heat transfer area and the thickness of the finned plate, respectively. Further, the optimal solution sets for different convection and heating conditions obtained through an optimization process are used to design a fin layout based on actual temperature control demands and cooling storage.

In grounding fault of DC system, overvoltage will appear on equipment nodes in converter station. Due to different operation mode and equipment type, it is very different from overvoltage in AC system. Based on Shanghaimiao–Linyi​ ±800kV Ultra High Voltage Direct Current (UHVDC) transmission project, this paper studies the converter station overvoltage characteristics under the conditions of DC pole line grounding, DC bus grounding and converter transformer valve side grounding fault, then analyzes the influence of smoothing reactor, filter capacitor and grounding pole line on overvoltage. In grounding fault at DC pole line near the converter station, the maximum overvoltage occurs on the inductance of DC filter, which is 592.75kV; In grounding fault at the top of the high voltage converter valve, the maximum overvoltage occurs on the neutral bus, which is 272.17kV. Increasing the inductance or capacitance of the smoothing reactor and filter capacitor, shortening the length of grounding electrode wire can significantly reduce the amplitude and steepness of overvoltage. The calculation results provide a reference for the internal overvoltage suppression of DC converter station with layered access at the inverter side.

Abstract This paper highlights the load frequency control using dual mode Bat algorithm based scheduling of PI controllers for interconnected power systems. The bat inspired algorithm based on the echolocation of bats has been developed in 2010. In this study, the bat inspired algorithm based dual mode PI controller is applied to the multi-area interconnected thermal power system in order to tune the parameter PI controllers. The proposed controller is simple in structure and easy for implementation. The proposed controller was compared with those from conventional the PI controllers and Fuzzy gain scheduling of PI controllers. The simulation results show the point that the proposed bat inspired algorithm, based dual mode gain scheduling of PI controllers (BIDPI), provides better transient as well as steady state of response. It is also found that the proposed controller is less sensitive to the changes in system parameters.

The steady-state phase distribution and the structural parameters have been taken as the input for the nuclear physics calculation in the ADS windowless spallation target. The distribution of the extreme large power density of the heat load is imported back as the source term in the energy equation. Then temperature distribution is obtained based on the flow process and heat transfer. The preliminary results show that the temperature distribution reaches the steady-state and its shape is like the broken wings of the butterfly. This is very important for the further design and optimization of the ADS windowless spallation target. So the two-way coupling simulation of the heat transfer process is successfully performed between the computational fluid dynamics and the nuclear physics simulation.

A detailed analysis of the effects of ground grid configuration on grounding performance has been carried out for uniform and horizontally stratified soils with multiple layers. The results of the analysis reveal that the most efficient and cost-effective design is highly dependent on soil structure type and characteristics. In the absence of ground rods, grounding grids with uniform mesh size are quite efficient in soils having a thin (relative to grid size) high resistivity (relative to the lower layers) top soil, while grids with small mesh size at the periphery of the grid provide optimum performance in uniform soils and soils with low resistivity top soils. Ground rods were found to be effective only when a significant portion of their length is in contact with a low resistivity soil, as expected.