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In order to solve the end-effector force control response speed hysteresis and mechanical vibration problems caused by parameter perturbations and other disturbances during the processing of wind turbine blades by polishing robots, this paper proposes a robot pneumatic end-effector polishing force control strategy based on adaptive sliding mode backstepping algorithm. Based on the establishment of the mathematical model of the end-effector pneumatic system, a smooth and continuous sliding mode control law is adopted to solve the design conflict between sliding mode control theory and backstepping method, and to suppress output chattering in sliding mode control. By utilizing the insensitivity of the sliding mode control to the system model, the influence of matching disturbances on the system is eliminated. The non-matching disturbances of the known model are accurately compensated by backstepping control, and parameter uncertainty is effectively handled by adaptive control. Simulation and experimental results show that this method can effectively solve the uncertainty of system parameters and has good disturbance suppression ability, significantly improving the surface quality of wind turbine blades. [ABSTRACT FROM AUTHOR]

A TiB2-based cermet tool material with excellent mechanical performance was rapidly prepared by microwave hybrid sintering. Microwave hybrid sintering is based on pure microwave sintering with the addition of high microwave absorbing materials (e.g., SiC coating and SiC powder) to assist in the heating of the sample, which has the characteristics of hybrid heating. The effects of two different microwave hybrid sintering methods and nano-HfC content on mechanical properties and microstructure of cermets were investigated. The experimental results indicated that different sintering methods changed the distribution of microwave electric field in the furnace, which affected the sample heating mechanism. SiC-buried powder hybrid sintering was more efficient than SiC coating hybrid sintering, so the sintered material had higher densities and mechanical properties. The fracture toughness and flexural strength of cermets containing 20 wt.% HfC were 36.7% and 45.4%, respectively, higher than those without HfC, and the fracture toughness reached 10.68 MPa·m1/2. With the increase of nano-HfC content, the TiB2 grains changed from coarse irregular shape to fine rectangular shape, and the average grain size can be reduced by 2.6 times. The toughening and strengthening mechanisms of the nano-HfC added phase were mainly fine-grain strengthening, particle dispersion strengthening, solid solution strengthening, crack deflection, and pinning effect. [ABSTRACT FROM AUTHOR]

In the process of aero-engine blade polishing, parameter uncertainties and unmodeled disturbances in the pneumatic end-effector cause fluctuation of the polishing force, affecting the quality of blade processing. To solve the problems mentioned above, a polishing force adaptive controller based on dual extended state observer is proposed. A novel mathematical model of the pneumatic end-effector is established based on the flow characteristics near the zero position of the proportional valve, and a matched disturbance factor is introduced. The controller proposed in this paper contains parameter adaptive law and dual extended state observer. The former aims to compensate for the parameter uncertainties, and the latter aims to compensate for the matched and unmatched disturbances, respectively. The experimental analysis including aero-engine blade polishing constant contact stress control is applied. Simulation and experimental studies show that the controller proposed in this paper can effectively compensate for the influence of parameter uncertainties and unmodeled disturbances on the fluctuation of the polishing force. The fluctuation of the polishing force is 0.41 N, and the quality of the surface finish of aero-engine blades is improved. [ABSTRACT FROM AUTHOR]

The aero-engine blade grinding system has time delay problem, which leads to large fluctuation of grinding force and eventually affects the surface roughness of the blade. To address this problem, this paper combines the improved Smith prediction algorithm with active disturbance rejection control (ADRC) to propose the filter Smith-ADRC control algorithm, which consists of three parts, namely, the main controller, the compensator and the filter. It is firstly simulated and analyzed in Matlab/Simulink platform, and then the robot grinding system is constructed for experimental verification, which is executed by the robot for position control and by the end-effector for force control. Both simulation and experimental results show that the grinding system with filter Smith-ADRC controller has good control effect and stability. The surface roughness of the blade is 0.3503 μm after grinding, which is better than other control algorithms such as ADRC and Smith's predictive control. Consequently, the filter Smith-ADRC control algorithm can overcome the time delay problem of the system and improve the grinding accuracy and quality. [ABSTRACT FROM AUTHOR]

To enrich material types applied to additive manufacturing and enlarge application scope of additive manufacturing in conformal cooling tools, M2 high-speed steel specimens were fabricated by selective laser melting (SLM). Effects of SLM parameters on the microstructure and mechanical properties of M2 high-speed steel were investigated. The results showed that substrate temperature and energy density had significant influence on the densification process of materials and defects control. Models to evaluate the effect of substrate temperature and energy density on hardness were studied. The optimized process parameters, laser power, scan speed, scan distance, and substrate temperature, for fabricated M2 are 220 W, 960 mm/s, 0.06 mm, and 200 ℃, respectively. Based on this, the hardness and tensile strength reached 60 HRC and 1000 MPa, respectively. Interlaminar crack formation and suppression mechanism and the relationship between temperature gradient and thermal stress were illustrated. The inhibition effect of substrate temperature on the cracks generated by residual stresses was also explained. AM showed great application potential in the field of special conformal cooling cutting tool preparation. [ABSTRACT FROM AUTHOR]

In the process of aeroengine blade grinding, the vibration of the robot reduces the precision of grinding force control at the end, which seriously affects the processing quality of the blade. Thus, a macro–micro grinding system composed of a robot and a pneumatic end-effector is constructed. The system is controlled by the robot to realize the position and the end-effector to realize the force control. Based on a simplified model of the robot and the end-effector, a force compensation strategy combining a dynamic matrix prediction algorithm and an impedance compensation method is proposed. The axial grinding force and vibration compensation force are rolling optimized in a limited time domain in a way of minimizing the quadratic performance index, the time lag of the force compensation process and the uncertainty of model parameters are compensated, and the grinding force can be tracked stably is realized. The simulation and experimental results indicate that the method can quickly suppress the vibration, decrease the force fluctuation, and improve the blade grinding quality. [ABSTRACT FROM AUTHOR]

Isoflurane (ISO) has been widely used in clinical anesthesia, and exposure to ISO leads to cognitive dysfunction. Our paper aimed to investigate the effect of miR-128-3p on cognitive impairment, inflammation, and oxidative stress elicited by ISO anesthesia in Sprague–Dawley (SD) rats. The SD rats were treated with ISO to mimic the ISO-injured situation, and the concentration of miR-128-3p was quantified utilizing real-time PCR. The miR-128-3p's impacts in ISO-engendered rat models on the respects of inflammatory condition and oxidative activities were measured by the commercial kits. The Morris water maze test was adopted to measure the neuro-function regarding miR-128-3p. Additionally, the target was tested by the alternation of luciferase activity. The irritation of ISO suppressed miR-128-3p expression in rats, which was enhanced by the injection of miR-128-3p agomir. The adverse roles of ISO on inflammation, oxidative stress, and cognitive disorders were partially abrogated by an increment of miR-128-3p. A miR-128-3p's interconnection with specificity protein 1 (SP1) was pinpointed, and aggrandized mRNA levels of SP1 were found under ISO state. MiR-128 acted as a regulator in ISO damage in the respects of cognition, inflammation, and oxidative stress. The SP1's link of miR-128-3p was showcased. [ABSTRACT FROM AUTHOR]

To improve the processing efficiency of Ti6Al4V alloy and prove cutting compatibility of TiB2-based cermet tool and Ti6Al4V alloy, a dry turning experiment of Ti6Al4V was carried out using the two TiB2-based cermet tools with VC additive or without. The cutting performance, wear mechanism, and machining quality were studied to validate the effect of VC additive on cutting compatibility of TiB2-based cermet tools and Ti6Al4V alloys. It was found that TiB2-based cermet tool with VC additive showed a longer tool life than commercial WC–Co cemented carbide tool and TiB2-based cermet tool without VC additive. The addition of VC could increase the hardness to improve abrasive wear resistance and could also reduce chemical affinity and concentration gradient to inhibit adhesion wear and diffusion wear, thus extending the tool life of TiB2-based cermet tools due to the reduction of cutting force and cutting temperature. Furthermore, TiB2-based cermet tools with VC additive contribute finer surface roughness and more regular helical chip based on the more favorable cutting compatibility of TiB2-based cermet tools with VC additive and Ti6Al4V alloy. This study could provide a guideline to design and optimize TiB2 cermet tool materials for cutting Ti6Al4V alloy. [ABSTRACT FROM AUTHOR]

Mycotoxin contamination is a serious threat to food safety and human health. The development of efficient degradation strategies targeting mycotoxins is valuable. In this paper, magnetic TiO2@SiO2 hybrid photonic crystal microspheres (MHPCMs) were designed and prepared by the water-in-oil droplet method through a simple two-phase home-made microfluidic device for the degradation of deoxynivalenol (DON), the most serious mycotoxin contaminating cereals and feeding samples among natural mycotoxins. The morphologies of the synthesized microspheres were investigated by both metallurgical microscope and scanning electronic microscope (SEM), confirming that MHPCMs have a spherical shape and regular photonic crystal nanostructures. In the self-assembly system, TiO2 and Fe3O4 nanoparticles were responsible to form photocatalytic sites and magnet response, respectively. The effect of the TiO2 and Fe3O4 contents in the microspheres on their morphology and photocatalytic degradation activity was studied in detail. Finally, the optimized MHPCM could degrade DON in water under the light irradiation and be recycled easily by magnet. [ABSTRACT FROM AUTHOR]

In the process of two-pass micro plasma arc welding of titanium alloy sheet, based on the thermal contact resistance theory, a three-dimensional transient heat transfer finite element model of contact heat transfer between titanium alloy sheet and flexible fixture was established. The effects of contact upper surface temperature, micro-contact thermal resistance, micro-gap thermal resistance, DC and pulse welding on thermal contact resistance were investigated, and the simulation and experimental results were compared. The results show that the thermal contact resistance increases as the temperature increases when the temperature of the contact upper surface (titanium alloy sheet) is in the range of 290–350 K. The effect of micro-contact thermal resistance on the thermal contact resistance is 26.1%–46.3% larger than the micro-gap thermal resistance. The thermal contact resistance of pulse welding is 3.1%–3.5% larger than DC welding. The error of simulation and experimental results of weld pool depth is 8.6%, which verifies the reliability of the model. [ABSTRACT FROM AUTHOR]

In the traditional gait skeleton model, the fixed length proportions among different bones cause the loss of model personality, and the shoulder and hip points that are blocked by the body are difficult to be extracted. For those problems, a method based on the spatial and temporal fusion between vision and tactility is proposed, by which a equal proportion 3D gait skeleton model can be restructured in the camera coordinate system accurately through a single-frame image. In the geometric analysis process, some logical assumptions are proposed according to human anatomy and the laws of human movement, and an effective method is proposed for the extraction of thigh slope. The experimental result shows that the consistent equal proportion models, in which single bone length error is eventually controlled within ± 5 mm , can be extracted in different position under the premise of rapidity with the aid of this method. The extracted shoulder and hip points also meet the real human body skeleton structure, which lays the foundation for the integrity and rationality of the entire skeletal model. [ABSTRACT FROM AUTHOR]

Most of the current studies focus on the moving heat source model of straight wheel. However, these cannot be applied to calculate the cup wheel grinding temperature field, especially for the grinding processes performed with an adaptive end-effector. Based on the moving heat method and the principle of heat source superposition, the analytical thermal model of annular moving heat source for large surface workpiece is deduced. According to the parameters of the grinding instance, the numerical model is established by the finite element method for comparison and validating in this paper. The comparison results show that the characteristics of temperature distribution predicted by the analytical model and the numerical model agree very well. Two evident peak temperatures in grinding zone appear at both edges at the back of the grinding wheel in the feed direction, and test results with different grinding parameters show the relative errors do not exceed 19%. The feasibility of the analytical model and the numerical model based on different mathematical foundations is mutually validated. In the view of the non-uniform features of temperature distribution, especially the location of the peak temperature values, there are some reasonable explanations and analyses in this paper. [ABSTRACT FROM AUTHOR]