Archive

  • 2021 Volume 38 Issue 4
    Published: 18 March 2021
      
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  • Geometric Feature Reconstruction and Quality Inspection of Automatic Hole Making for Aircraft Skin
    2021, 38(4): 1-8.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Automatic processing of online hole making for skin based on robot has successfully solved the problems of low efficiency and poor quality in traditional hole making and has been widely used in aircraft assembly.Due to the limited accuracy of on-line measurement, it is necessary to evaluate the hole making process by analyzing and inspecting the hole making quality accurately.The measurement planning is aimed at the quality inspection analysis of hole making, and the data collection based on the inspection characteristics of CMM is realized.The modeling method of simple geometric shape and complex surface features is designed, and the geometric model reconstruction of test features is completed.The correlative geometric information of quality analysis is extracted, the evaluation model of quality analysis is established, and the comprehensive evaluation index is calculated.The experimental results show that this method can meet the requirement of high precision comprehensive evaluation of hole making quality and provide reliable analytical data for the improvement of hole making process.
  • Research Progress on stability of Two-dimensional material MXene
    2021, 38(4): 9-17.
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    MXene is a new type of transition metal carbide two-dimensional nano-layered material. It is usually prepared by etching the "A" atomic layer in the MAX phase by a chemical liquid method, and it can be divided into few-layered MXene after a certain treatment process. In an aerobic environment, MXene is prone to oxidation, leading to changes in structure and morphology, and performance degradation in all aspects. Summarize the preparation and layering methods of MXene, and focus on the research progress related to the stability of MXene. It is clear that treatment methods such as improving the storage environment, adding antioxidants, and silanization can effectively improve the stability of MXene, in order to improve the stability of MXene Process provides reference basis.
  • On orbit construction technology of large truss based on metamorphic theory
    2021, 38(4): 18-25.
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    By comparing and analyzing the current truss construction methods at home and abroad, on orbit assembly technology has certain advantages in the construction of large truss, but it requires the machine responsible for assembly to meet the requirements of carrying space and construction conditions. In this paper, a new method of modular truss on orbit assembly based on metamorphic theory is proposed, and the assembly process is preliminarily designed. In order to further design the metamorphic assembly mechanism in the proposed method, large truss structures are analyzed and selected to determine the basic elements of the truss, and the influence of the material and the length of the truss beam on the fundamental frequency is analyzed. The conceptual design and analysis of truss unit module and metamorphic assembly mechanism in the scheme system are carried out. This method solves the problem that the mass and volume of the large truss are limited by the carrying space, and has certain advantages in expandable capacity and work efficiency, which can provide reference for the construction of large space truss in the future.
  • Research on the hardness of graphene reinforced aluminum composites
    2021, 38(4): 26-34.
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    In order to improve the performance of aluminum alloy to meet the requirements, a graphene as a reinforcing phase was employed to fabricate the aluminum composite . The ball milling process is the core link in the preparation of composite materials. In this paper, the influence of ball milling process parameters (ball milling medium, rotation speed, ball-to-powder mass ratio, ball milling time) on the morphology of the composite powder is studied, and the optimal ball milling parameters are determined by comparative analysis. The 0.05w.t.% and 0.1w.t.% aluminum matrix composite was fabricated by hot isostatic pressing and the hardness was tested. The results show that the composite powder obtained by wet ball milling at a rotation speed of 240r/min, a ball-to-powder ratio of 6:1, and a ball milling time of 16h is evenly wrapped by graphene, and the hardness of the formed aluminum-based composite material is 23.59% higher than that of pure Zl114A when the mass fraction of graphene is 0.1%.
  • Research on Tensile Properties of Graphene Reinforced Nylon Composites
    2021, 38(4): 35-42.
    Abstract ( )   Knowledge map   Save
    In the field of polymer composite materials, the type, amount and dispersion of fillers seriously affect the overall performance of composite materials. Graphene, as an emerging nanomaterial with excellent mechanical, electrical and thermal properties, is an ideal filler for reinforcing polymer composites. Nylon is a polyamide material, which has the characteristics of high specific strength, high specific stiffness, good toughness, low price and wide application fields. In this experiment, graphene nanosheets were uniformly wrapped on the surface of nylon spherical powder through the original formic acid-water-nylon ternary mechanical mixing method to obtain graphene-reinforced nylon composite materials. It is made into a test piece by hot pressing, and it is analyzed and characterized by mechanical performance test and electron microscope. The results show that the mechanical properties of the composite material perform best when the loading is 0.1wt%. The tensile limit reaches 46.51±2.29MPa, and the elongation at break reaches 55.74±7.18%. As the amount of graphene added continues to increase, the Young's modulus of the material slowly increases, but the tensile limit and elongation at break begin to decline rapidly.
  • Review of wearable fall detection systems
    2021, 38(4): 43-53.
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    Globally, falls are a major public health problem among the elderly. Wearable fall detection systems can automatically detect a fall event and effectively mitigate fall-related complications. The successful deployment of a wearable fall detection system among the elderly in the real world depends on three factors: algorithm performance, battery life, and user acceptance. Firstly, this paper introduces the influence of sensor (type, placement position and sampling rate), extracted features, classification algorithms on these three factors, and discusses their merit and potential drawbacks. Then, the datasets used to develop and test the algorithm, and the performance metrics used to evaluate the algorithm are summarized. Finally, the low power technology of the wearable fall detection systems is summarized.
  • An optimized SVM based on color and texture Research on Fire Recognition Method
    2021, 38(4): 54-60.
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    This paper proposes an extraction method based on flame color and texture features, using quantum genetic algorithm to optimize the support vector machine, and constructing a QGA-SVM flame image classifier. The algorithm uses flame color features to extract fire suspected areas on the image hat has been de-noised and enhanced, then extract its texture features by uniform LBP, after that uses the KPCA algorithm to reduce the dimensionality of the feature vector, and inputs these features selected by KPCA to the quantum genetic algorithm optimized Support vector machine (QGA-SVM) for image recognition. Experimental results show that the recognition effect of the algorithm proposed in this paper is better than SVM and GA-SVM, the accuracy of fire flame recognition is over 90%, and the detection rate is effectively improved.
  • Target Recognition Research of Anti-shock Hammer Resetting Robot of Transmission Line
    2021, 38(4): 61-69.
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    Abstract:Target recognition, positioning and navigation of robots are the basis and key for industrial robots to accurately complete specific tasks. Based on shock hammer resetting problemwhich the robot homework depends on homework personnel of mechanical arm operation proficiency, in this paper, machine vision algorithm is used instead of manual target detection and localization task, torealize the shock hammer resetting robot precise positioning and accurate operation for the bolt..Firstly, the improved canny algorithm is used to extract the edge of the collected image of theshockproof hammer bolt, and then the improved Hough transform algorithm is used to accurately locatethe frame and center of the fastening bolt of the shockproof hammer, so as to complete theoperation task of the shockproof hammer resetting robot. The experimental results show that themethod proposed in this paper can effectively identify and locate the shock hammer bolts, andthe accuracy meets the requirements of robot operation. Key words: anti-shock hammer resetting robot; machine vision; canny algorithm; hough transform; Bolt positioning
  • Comparative study on prediction model of civil aviation accident symptom
    2021, 38(4): 70-77.
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    For accurately predicting civil aviation accident signs, based on the statistical bulletin of the civil aviation industry development, total turnover in 2009-2016 civil aviation transport, passenger transport, transport fleet number, fixed assets investment and 16 factors indicators, using the correlation analysis of grey theory and predict, at the same time, using the theory of multiple linear regression analysis. The above method is applied to predict the accident symptom number of CAAC in 2017-2018. The results show that the average relative error of the 2-year prediction using GM (1,1) model is 9.24%. In the GM (1, N) model, the average relative error predicted by the GM (1,2) model is 7.73%. The average relative error of GM (1,3) model is 7.54%. The average relative error predicted by GM (1,4) model was 7.43%. The average relative error of the multiple linear regression model is 34.27%. GM (1,2) is used to improve the short-term prediction accuracy. GM (1,4) can be used to predict the future number of civil aviation accidents in China, so as to guide the development planning of civil aviation.
  • Research on the Impact of R&D Investment on Enterprise Performance under the New Normal Economy——Based on the empirical analysis of 1004 listed companies
    2021, 38(4): 78-88.
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    Based on the background of the new economic normal, this article uses 1,004 A-share listed companies from 2010 to 2018 as research samples to construct a panel threshold model, and uses the panel threshold model to study the impact of R&D investment on corporate performance. Through empirical research, the following conclusions have been drawn: First, the implementation of national policies has promoted the growth of R&D investment. In comparison, it is found that after the introduction of the new economic normal, China’s R&D investment has increased significantly in recent years; second, R&D investment There is a certain correlation between R&D and corporate performance, but the correlation is not very strong in the current period. Due to the time constraints of technological innovation, the performance and effectiveness of R&D investment has shown a certain lag; third, under the new economic normal, R&D There is a structural mutation threshold for the impact of investment on corporate performance, indicating that the policy is effective.
  • The latest research Hotspot and Evolution of Green Innovation in China -- Visual analysis based on CiteSpace
    2021, 38(4): 89-96.
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    Abstract: Based on literature measurement and content analysis, the literature related to green innovation of CNKI from 2000 to 2019 was selected for visual analysis by using CiteSpace software, and the insufficiency of research on green innovation and its future research direction were discussed. Research findings: The current domestic research on green innovation centers on nine clusters, namely, manufacturing industry, environmental regulation, manufacturing green innovation system, enterprise performance, industrial cluster, environmental tax, government subsidy, ecological civilization and ethical leadership. Although its research subject is in the stage of diffusion, it lacks of detailed exploration. Empirical studies rely on questionnaires to obtain data, and there are ambiguities in measurement indicators. This paper argues that the measurement design of empirical research should be optimized, the reputation mechanism and the third-party contract mechanism should be explored to explore the impact path of green innovation, and a comprehensive and systematic study should be carried out in the field of green innovation.