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Oil-filled motors (OFMs) are widely used in deep-sea exploration and oil well extraction. During motor operation, the rotor stirs the oil in the air gap, causing viscous loss. Viscous loss affects the temperature distribution inside the motor. Accurately calculating the viscous loss and temperature rise in OFMs can provide a basis for optimizing the motor's structural design. Motor structural parameters, including the rotor's outer diameter, air gap, and slot opening, have a significant impact on viscous loss. The working conditions of OFMs, such as rotor speed and environmental temperature, also affect viscous loss. The viscosity of hydraulic oil is highly influenced by temperature, and changes in viscosity can lead to changes in viscous loss. These changes in viscous loss, in turn, alter the temperature distribution. Therefore, the coupling relationship between viscous loss and temperature must be considered. Additionally, when Taylor vortices occur in the fluid, the surface roughness of the rotor also has a significant influence on viscous loss. Currently, both domestic and international research on viscous loss and thermal analysis struggle to simultaneously consider the coupling of viscous loss and the temperature field, rotor surface roughness, and the effect of motor structure. This paper summarizes the methods used in recent years for studying viscous loss and thermal analysis, and puts forward some suggestions for future research on the coupling of the OFM temperature field and viscous loss. [ABSTRACT FROM AUTHOR]

Abstract: Both substitutional and interstitial nitrogen-doped titanium dioxides (N-TiO2) were prepared. Their surface states were clarified by XPS spectra of N 1s, O 1s and Ti 2p. The results of photocatalysis show that both substitutional and interstitial N impurities greatly enhance the photoactivity of TiO2 in visible light. Moreover, the visible light activity of interstitial N-doped TiO2 is higher than that of substitutional N-doped TiO2. The microwave synthesis presented in this paper is a promising and practical method to produce interstitial nitrogen-doped photocatalysts with high visible light activity. [Copyright &y& Elsevier]

Oxygen vacancies play crucial roles in defining physical and chemical properties of materials to enhance the performances in electronics, solar cells, catalysis, sensors, and energy conversion and storage. Conventional approaches to incorporate oxygen defects mainly rely on reducing the oxygen partial pressure for the removal of product to change the equilibrium position. However, directly affecting reactants to shift the reaction toward generating oxygen vacancies is lacking and to fill this blank in synthetic methodology is very challenging. Here, a strategy is demonstrated to create oxygen vacancies through making the reaction energetically more favorable via applying interfacial strain on reactants by coating, using TiO 2 (B) as a model system. Geometrical phase analysis and density functional theory simulations verify that the formation energy of oxygen vacancies is largely decreased under external strain. Benefiting from these, the obtained oxygen-deficient TiO 2 (B) exhibits impressively high level of capacitive charge storage, e.g., ≈53% at 0.5 mV s -1 , far surpassing the ≈31% of the unmodified counterpart. Meanwhile, the modified electrode shows significantly enhanced rate capability delivering a capacity of 112 mAh g -1 at 20 C (≈6.7 A g -1 ), ≈30% higher than air-annealed TiO 2 and comparable to vacuum-calcined TiO 2 . This work heralds a new paradigm of mechanical manipulation of materials through interfacial control for rational defect engineering., (© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

In the development of beyond-line-of-sight (BLOS) Unmanned Aerial Vehicle (UAV) systems, communication between the UAVs and the ground control station (GCS) is of critical importance. The commonly used economical wireless modules are restricted by the short communication range and are easily blocked by obstacles. The use of a communication relay system provides a practical way to solve these problems, improving the performance of UAV communication in BLOS and cross-obstacle operations. In this study, a communication relay system, in which a quadrotor was used to relay radio communication for another quadrotor was developed and tested. First, the UAVs used as the airborne platform were constructed, and the hardware for the communication relay system was selected and built up. Second, a set of software programs and protocol for autonomous mission control, communication relay control, and ground control were developed. Finally, the system was fully integrated into the airborne platform and tested both indoor and in-flight. The Received Signal Strength Indication (RSSI) and noise value in two typical application scenarios were recorded. The test results demonstrated the ability of this system to extend the communication range and build communication over obstacles. This system also shows the feasibility to coordinate multiple UAVs' communication with the same relay structure., Competing Interests: The authors declare no conflict of interest.