In order to improve the surface quality and corrosion resistance of DD6 nickel-based single crystal superalloy，the electrochemical polishing experiment of DD6 nickel-based single crystal superalloy was carried out by formamidesulfamic acid solution，and the effects of polishing voltage，electrolyte concentration and polishing time on the surface quality after polishing were studied. The results show that under the conditions of 20 V，electrolyte concentration 1.2 mol/L and of 2 min，the surface roughness is the lowest value of 0.358 m，and the surface effect reaches the best at this time. Under the conditions of high voltage （30 V） and high acid concentration （1.6 mol/L），irregular pits and impurity particles appeare on the surface of DD6 samples，and the surface quality is poor. After electrochemical polishing，the brightness of DD6 samples is improved，and the polishing voltage is the key parameter affecting the surface brightness.It is analyzed that the surface O element content is low after polishing，indicating that no passivation film containing metal oxides is formed during the polishing process.The Tafel curves before and after polishing of DD6 samples show that the corrosion potential of DD6 samples is larger and the corrosion current is smaller after polishing，so the corrosion resistance of DD6 samples is improved by electrochemical polishing.
A comprehensive review of the research progress of solar-powered drones，energy systems，and aerodynamic configuration was provided，aiming to guide the perpetual flight of solar-powered drones.In terms of research history，Sunglider has become the largest known solar-powered drones with a wingspan of 80 m，while the 29 500 m flight altitude record set by Helios remains unbroken to this day.PHASA-35 has become the fastest solar-powered drone with its top speed of 40 m/s.The payload ratio of solar-powered drones is steadily increasing，with China's Rainbow T4 having a payload ratio of approximately 0. 286，second only to Helios at 0. 457.In terms of energy systems gallium arsenide thin-film multi-junction batteries，with an efficiency of up to 33. 6% are the focus of future applications.Lithium-sulfur batteries，with an energy density of 650 Wh/kg are the highest energy-density storage batteries，but their stability issues require further research and improvement.In terms of aerodynamic configuration，the flying wing configuration has a high aerodynamic efficiency，but it has lower stability and poor controllability.The future research direction is to optimize the stability and operability while maintaining its aerodynamic efficiency.
With the development of the aerospace field and advancement of science and technology，the application field of die-less spinning is becoming more and more extensive.Pre-formed workpieces can be obtained by spinning without a mandrel support，which can really achieve the purpose of high efficiency and low consumables.However，the lack of mandrel support makes it difficult to determine the direction and speed of metal flow of the original blank during forming process.The study of the formed workpiece microstructure can reflect the metal flow and plastic deformation on the macroscopic level，and it can also deeply reveal the related mechanism of the spin forming method.So far，there are few studies on the evolution of the microstructure of die-less spinning forming，which is summarized in this paper.According to the microanalysis of the influence of the spinning parameters on the forming accuracy； through the microstructure of the grain orientation and grain size of the spinning process to carry out a detailed analysis of the metal flow； according to the microstructural characteristics of the spinning workpiece can be the study of the mechanical properties，which helps to reveal the spinning process.The study of the mechanical properties of the spinning workpiece can help to reveal the forming mechanism of the spinning process.
With the rapid development of the aerospace industry，high quality repair technology of aerospace aluminum alloy castings has significant economic benefits and scientific research mirits.Accordingly，a study on the laser deposition repair technology of ZL105 aluminum alloy was carried out.Optimal laser deposition repair process parameters were explored.The microstructure morphology of the laser repair area，the microhardness and room temperature tensile properties of the specimens were measured.The results show that good metallurgical bonding between the repair area and the substrate are obtained.Restoration areas are finely organized and composed of columnar dendrites and isometric crystals.The microhardness of the repaired area increased 16% compared to the substrate，and the strength of the repair parts can reach more than 96% of the strength of the substrate.What’s more，as the repair ratio increases，the strength of the repair parts decreases gradually but the plasticity improves.The fracture mechanism of the repaired specimen is a mixed fracture of tough and brittle.
In order to measure and analyze the forces on skis during skiing，It is necessary to develop the snowboard measuring system.On the basis of summarizing and analyzing the use of similar products，the integrated circuit design of signal conditioning and wireless transmission，and two dimensional force sensor combination were adopted，a five-dimensional force measurement system for snowboard was developed successfully.The system has higher stiffness，natural frequency and better dynamic measurement performance.The static accuracy of the three-dimensional force sensor is better than 0.2%FS，and the static accuracy is better than 0.4%FS.The dynamic performance of landing impact is tested by the system，and the test results are in good agreement with the theoretical analysis.In the testing process，all the sensors return to zero well，the dynamic performance is stable，and the law of measuring load is reasonable.The successful development of the system provides reference for the research and development of multimensional force measuring system for skiing and skating，and lays a good foundation for the localization and self-control of sports testing device.
In order to gain a theoretical understanding of the heat transfer mechanism of C/SiC materials，Monte Carlo method was applied to analyze heat transfer of C/SiC corrugated lattice structure composite material.The heat transfer mechanism of the corrugated lattice structure was studied from three aspects： the beam emission position，the beam emission direction and the judgment of the beam occlusion.At the same time，the influencing factors of the heat transfer coefficient of the lattice structure were studied by changing the structural geometric parameters，the emissivity of the solid surface and the temperature applied by the upper panel.The number of samples can be accurate to 4.0×106 and the heat transfer coefficient converges to 0.554 9 by using the heat transfer coefficient derived from the formula of Monte Carlo method.The results show that，the linear relationship between the heat transfer coefficient，the geometric parameters of the corrugated lattice and the reasons for its change are given，the optimal thermal insulation model parameters of the corrugated lattice structure are obtained.The theoretical research provides certain engineering application value for thermal insulation of aerospace material and composite material research.
In wireless multi-hop networks，using the broadcast backbone to forward messages can effectively improve network efficiency.Based on the existing ECHO protocol，an optimized ECHO-OPT scheme was proposed，which considered the energy factor of nodes in the decision-making process of critical nodes，and optimized the redundant nodes in the critical node set in the process of message forwarding.In the experiments，the influence of communication range on redundant nodes was studied and the network performance of the protocol was tested under fixed network density and dynamic network density.The simulation results show that compared with ECHO，ECHO-OPT can optimize the size of critical node set by an average of 4.67 in high-density networks，and reduce the network load by 65% and 32% respectively compared with MPR and ECHO.At the same time，ECHO-OPT also has a higher network lifetime.
To address the issues of low efficiency， blind spots in vision， and high costs of traditional manual security patrols， a security patrol system based on the DiMP （discriminative model prediction） algorithm was designed. The system adopted a modular design and implements autonomous flight control and tracking functions for UAV （unmanned aerial vehicle） on an embedded onboard computer. To enhance the tracking precision and accuracy of small targets during the patrol process， a multi-scale feature fusion strategy was employed to improve the DiMP target tracking algorithm. This strategy involved fusing image pyramid features of different scales with the backbone network features， providing the backbone network with information-rich fused features. The optimized DiMP algorithm achieved a 2.6% increase in target tracking success rate and a 3.4% increase in precision on the UAV123 dataset， while also reaching a tracking speed of 38 fps on the VOT2018 dataset. Finally， the effectiveness of the UAV security patrol was verified in an outdoor environment. The results show that the improved tracking algorithm is capable of operating in real time on the UAV and stably tracking the target for a long time.
In order to solve the problem that rolling bearing fault features were difficult to be extracted under strong noise background， parameter optimized variational mode decomposition （VMD） and maximum correlation kurtosis deconvolution （MCKD） were proposed to extract rolling bearing fault features. Firstly， the original signal was decomposed by the optimal combination of parameters obtained by offline optimization of the VMD parameters using the improved sparrow algorithm. Secondly， in order to screen and reconstruct each IMF after decomposition， a new screening metric was constructed based on the envelope spectrum peak factor and sample entropy. Then， the reconstructed signal was augmented with MCKD optimized by the online method of the improved sparrow algorithm. Finally， the bearing failure frequency information was extracted from the enhanced signal by envelope demodulation analysis. Simulation and experimental results show that the proposed method is able to enhance the shock components submerged in the strong noise and effectively extract rolling bearing fault features.
Hydroxylated boron nitride nanosheets （BN—OH） were prepared by using 30% hydrogen peroxide solvent to strip and modify hexagonal boron nitride （h—BN） by the method of combined hydrothermal/ultrasound preparation. BN—OH/APTES—HPCTP intumescent refractory coatings were prepared by melt blending method using BN—OH， silane coupling agent （APTES） and hexaphenoxycyclictriphosphonitrile （HPCTP） as filler materials. The impact of BN—OH and HPCTP on flame retardant and smoke suppression property of intumescent refractory coatings was explored. According to the cone calorimeter （CCT） test， the BN—OH/APTES—HPCTP intumescent refractory coatings had the lowest fire growth index （FGI）， and the thermal release rate peak （pHRR） and smoke release rate peak （pSPR） were reduced by 17.37% and 22.39%， respectively， compared with conventional intumescent refractory coatings. It is found that HPCTP-assisted intumescence system （IFR） catalyses the expansion of epoxy resin （EP） to form a carbon layer. The modified boron nitride （BN—OH/APTES） is beneficial to improving the compactness of the carbon layer and preventing the flammable gas from approaching the substrate， thereby reducing the damage of the substrate caused by fire.
To explore the impact of enterprise standardization capabilities grounded in the theory of resource conservation，a meta-analysis structural equation model was constructed based on data from 20 empirical research samples to reveal the potential relationship between them. Research results indicate that Standardization capability positively promotes innovation performance.For technology-based enterprise，the positive impact of standardization capability on innovation performance is more significant；when considering mediating variables，the positive impact of standardization capability on innovation performance is more significant；knowledge conversion partially mediates the impact of standardization capability on innovation performance. It is recommended that enterprises should formulate reasonable standardization strategies based on their own situations，actively engage in standardization formulation，and strengthen the utilization of knowledge resources.
