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Surface texture parameters are a quantitative way of characterising surface topographical features and are closely related to tribological properties. In this paper, the correlation between surface topographic features and friction coefficient is investigated on the basis of the proposed improved correlation analysis model for high-speed milling surface topography of hardened steel. It was found that the friction coefficient could not be accurately reflected by a single parameter, so a prediction model for the friction coefficient based on Sxp, Sq, Sp, Sz, Sku and Sdq was developed. In this paper, the parameter screening was completed based on the changing characteristics of the data, and a multi-parameter prediction model of the friction coefficient in the stable wear stage was established, which provides a new idea to investigate the influence of the characteristics of surface topography on tribological performance. [ABSTRACT FROM AUTHOR]

The surface texture parameter is a real reflection of the surface topography, which is closely related to the tribological properties of the surface, and the study of the correlation between the surface texture parameter and wear resistance is of great significance in revealing the tribological influence mechanism of the surface and realising the functional manufacturing of the surface. This paper takes the ball-end milling surface as the research object, establishes the three-dimensional simulation model of the surface topography, and analyses the surface topography and the surface texture parameter change rule. Based on the improved correlation analysis model, the correlation characteristics between the surface texture parameters, and between the surface texture parameters and the relative wear rate of per unit sliding distance KV, were investigated, and the prediction model of KV was established based on the surface texture parameters Sku, Sa, Sxp, Sp, and Ssk, and the correctness of the model was verified by experiments. The study in this paper provides a new idea to further reveal the relationship between surface topographical features and wear resistance and to guide the functional manufacturing of surfaces. [ABSTRACT FROM AUTHOR]

(1) The vicious cycle of innate immune response and reactive oxygen species (ROS) generation is an important pathological process of osteoarthritis (OA). Melatonin may be a new hope for the treatment of OA because of its antioxidant capacity. However, the mechanism of melatonin in the treatment of OA is still not completely clear, and the physiological characteristics of articular cartilage make melatonin unable to play a long-term role in OA. (2) The effects of melatonin on ROS and the innate immune response system in OA chondrocytes and the therapeutic effect in vivo were evaluated. Then, a melatonin-loaded nano-delivery system (MT@PLGA-COLBP) was prepared and characterized. Finally, the behavior of MT@PLGA-COLPB in cartilage and the therapeutic effect in OA mice were evaluated. (3) Melatonin can inhibit the activation of the innate immune system by inhibiting the TLR2/4-MyD88-NFκB signal pathway and scavenging ROS, thus improving cartilage matrix metabolism and delaying the progression of OA in vivo. MT@PLGA-COLBP can reach the interior of cartilage and complete the accumulation in OA knee joints. At the same time, it can reduce the number of intra-articular injections and improve the utilization rate of melatonin in vivo. (4) This work provides a new idea for the treatment of osteoarthritis, updates the mechanism of melatonin in the treatment of osteoarthritis, and highlights the application prospect of PLGA@MT-COLBP nanoparticles in preventing OA. [ABSTRACT FROM AUTHOR]

The hydraulic transformer is the core component when it works with the common pressure rail system, which integrates the functions of the pump and the motor, and thus possesses sensitive pressure characteristics. The rotating speed has significant influence on the pressure characteristics of a hydraulic transformer while it has not been considered previously. In this study, aimed at improving the working performance, a novel double rotor hydraulic transformer is proposed and a comprehensive mathematical model considering the dynamic characteristics of the cylinder block is established. At the same time, a prototype is made and the experiment is conducted. The test results show that the robust rotor structure enables a larger pressure range, and the numerical results exhibit a good match with the test results. The parameter sensitivity study shows that the delivery pressure is mainly subject to the valve plate control angle δ and, under the effects of the resistance torques, pressure loss will occur especially under a large control angle and a high rotating speed. The magnitude of the instantaneous angular velocity fluctuation increases sharply when the speed is lower than 400 r/min, which is the main reason for the serious pressure pulsation at a low speed. As a result of the improved low-speed stability and output flow uniformity, the pressure pulsation rate of the double rotor hydraulic transformer is greatly reduced. However, the pulsation rate is still high at an extremely low speed. In addition, when the rotating speed exceeds the capability of the damping grooves, the pressure undershoot becomes serious at the A-T transition region around the control angle of −30°. Consequently, from the perspective of pressure characteristics, the limitation on the rotating speed under small control angles is suggested for the design of the double rotor hydraulic transformer controller. [ABSTRACT FROM AUTHOR]

Knowledge of aircraft wake vortex circulation is very essential for promoting aviation safety and airport capacity. In foggy conditions, cloud water droplets suspended as fog (here called fog drops) inside the wake have almost identical velocity with the wake vortex due to the weak inertia of the droplets. By taking this property into account, we propose two methods to retrieve the circulation of wake vortex in fog with a side-looking scanning radar. In the methods, while the radar beam scans alternatively up and down, the vortex cores are identified from the Doppler spectra at different incident angles, and the circulation is finally boiled down to very simple expressions related to the Doppler velocities. Numerical simulation results verify the good performance of the methods. [ABSTRACT FROM AUTHOR]

The present work is dedicated to the modeling and simulation of the radar signature of raindrops within wake vortices. This is achieved through the computation of the equation of raindrop motion within the wake vortex flow. Based on the inhomogeneous distribution of raindrops within wake vortices, the radar echo model is computed for raindrops in a given resolution cell. Simulated Doppler radar signatures of raindrops within wake vortices are shown to be a potential criterion for identifying wake vortex hazards in air traffic control. The dependence of the radar signature on various parameters, including the radial resolution and antenna elevation angle, is also analyzed. [ABSTRACT FROM AUTHOR]

Knowledge of radar scattering characteristics is very important to the development of radar detection technology on aircraft wake vortices. In this paper, the high range resolution (HRR) profile of the wake vortex is investigated. The HRR profile is observed to have a particular structure, from which the wingspan of the aircraft can be easily identified. This characteristic could be very useful to identify the wake vortex from the ambient air. At the same time, the Bragg scattering, whose characteristic and applicability are further explored, is used to explain the mechanism of such particular HRR profiles. [ABSTRACT FROM AUTHOR]