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During the pipeline plugging process, both the pipeline and the pipe isolation tool (PIT) will be greatly damaged, due to the violent vibration of the flow field. In this study, it was proposed for the first time to reduce the vibration of the flow field during the plugging process by optimizing the surface structure of the PIT. Firstly, the central composite design (CCD) was used to obtain the optimization schemes, and the drag coefficient and pressure coefficient were proposed to evaluate the degree of flow field changes. Secondly, a series of computational fluid dynamics (CFD) simulations were performed to obtain the drag coefficient and pressure coefficient during dynamic plugging. And the mathematical model of drag coefficient and pressure coefficient with the surface structure of the PIT were established respectively. Then, a modified particle swarm optimization (PSO) was applied to predict the optimal value of the surface structure of the PIT. Finally, an experimental rig was built to verify the effectiveness of the optimization. The results showed that the improved method could reduce the flow field vibration by 49.5 6%. This study provides a reference for the design of the PIT surface structure for flow field vibration technology.

The pipe isolation tool (PIT) demonstrates remarkable advantages in safety and efficiency compared with traditional plugging devices. However, its utilization in plugging operations is limited by the operation duration. In addition, the existing energy recovery system has low energy saving efficiency. In this paper, a real-time control energy-saving system of the PIT was designed based on a reinforcement learning algorithm. First, an experimental device for energy-saving was designed. Secondly, the energy distribution scheme of a hydraulic pump and accumulator based on experimental data was proposed. Finally, the reinforcement learning algorithm was used to adjust the opening of the hydraulic pump and the accumulator valves in real time during the plugging process to improving energy saving efficiency. The results verify that the energy saving efficiency of the PIT control system based on reinforcement learning could reach 23.71%, which satisfies the objectives of energy-saving and environmental applicability.

The surface area of liquid crystal (LC) devices in different applications, such as displays, signage devices and smart windows is becoming larger and larger. The electrical driving of such devices does not pose many problems when working on centimetre sized devices. Different types of driving issues arise when up-scaling such devices to areas of several square metre, due to the fact that the thin-film transparent conductors used in these devices exhibit a finite sheet conductivity. One of the resulting issues is the non-uniformity of the electric field across the area of the device and the resulting non-uniform optical behaviour. In this work, we present a simulation model that is able to predict the optical and electrical behaviour of large-sized liquid crystal devices with different applied voltage signals, including the power consumption. The simulation results are compared with optical and electrical measurements on a liquid crystal device of 1.5 m by 1.2 m.

This study designs an energy-saving structure with an energy recovery system which is developed to improve the efficiency of the smart plugging tool. This structure can produce energy through the impeller is assembled in the tail of speed control devices, and then the energy generated by the rotation of the impeller is transmitted to the accumulator through the hydraulic circuit. At first, a simple three-dimensional model is designed to simulate the real devices. Secondly, in order cto measure the rotating speed of impeller, this model is put in the flow field, and the speed and pressure are measured, and then analyzing the stress and strength of the model. At last , this study simulated the hydraulic system circuit to calculate the energy recovery efficiency , and increased the closed-loop feedback for system to improve stability. Simulation results verify this hydraulic system is satisfied for the energy-saving goal.

We demonstrate a laser beam combiner based on four photo-patterned Pancharatnam–Berry (PB) phase gratings, which is compact and has high diffraction efficiency for incident circularly polarized light. The nematic liquid crystal mixture E7 is used as anisotropic material, and the thickness of the layer is controlled by spacers. The beam combiner can bring two parallel laser beams closer to each other while remaining parallel. This work shows the potential to realize components based on flat optical LC devices.

In this work, the design, fabrication and characterization are reported for a distributed Bragg reflector (DBR) filter with a specific wavelength and angular dependency, which aims to improve the light collection from a wavelength-converter-based light source into a smaller angle than the full angle Lambertian emission. The desired design is obtained by optimizing the transmission characteristics of a multi-layer structure. Titania (TiO2) and silica (SiO2) are used as high and low refractive index materials, respectively. The deposition is made by electron beam evaporation without substrate heating, followed by a post-annealing procedure. The optical properties of the evaporated layers are analyzed by ellipsometer and spectrometer measurements. The angular and wavelength dependency of the fabricated DBR is in good agreement with simulations for the designed structure. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement