Structure and Electrochemical Properties of Laser Cladding Al2CoCrCuFeNiTix High‑Entropy Alloy Coatings

Xingwu Qiu 대한금속·재료학회 2020 METALS AND MATERIALS International Vol.26 No.7

Al2CoxCrCuFeNiTi high-entropy alloy coatings were prepared on Q235 steel by laser cladding. The structure was tested byscanning electron microscopy; the corrosion resistances of the alloys were tested by electrochemical workstation. The resultsshow that the microstructures of Ti2.0high entropy alloy are mainly equiaxed grains, spherical particles, white particles and"plum blossom" particles are distributed on it, columnar grains are located near the bonding zone. The corrosion resistanceof Al2CoCrCuFeNiTixhigh-entropy alloy coatings in 1 mol/L NaOH and 0.5 mol/L HCl solutions are excellent. In 1 mol/LNaOH solution, compared with Q235 steel, the corrosion current density of the coating decrease by 5 orders of magnitude,the corrosion potential increased by 0.03–0.34 V. In 0.5 mol/L HCl solution, compared with Q235 steel, the corrosion currentdensity of the coating decreases, the corrosion potential increased by 0.06–0.14 V. With the increase of Ti content,the corrosion resistance of Al2CoCrCuFeNiTixhigh-entropy alloy coating in 0.5 mol/L HCl solution is enhanced, while, in1 mol/L NaOH solution, the corrosion resistance of the coatings decreased. Cyclic polarization curves showed that negativehysteresis loops appeared in Ti0.5high-entropy alloy coating in 1 mol/L NaOH solution and Ti2.0high-entropy alloy coatingin 0.5 mol/L HCl solution, which indicated that the coatings has excellent pitting corrosion resistance.

The construction of multivariable Reissner-Mindlin plate elements based on B-spline wavelet on the interval

Xingwu Zhang,Xuefeng Chen,Zhengjia He 국제구조공학회 2011 Structural Engineering and Mechanics, An Int'l Jou Vol.38 No.6

In the present study, a new kind of multivariable Reissner-Mindlin plate elements with two kinds of variables based on B-spline wavelet on the interval (BSWI) is constructed to solve the static and vibration problems of a square Reissner-Mindlin plate, a skew Reissner-Mindlin plate, and a Reissner-Mindlin plate on an elastic foundation. Based on generalized variational principle, finite element formulations are derived from generalized potential energy functional. The two-dimensional tensor product BSWI is employed to form the shape functions and construct multivariable BSWI elements. The multivariable wavelet finite element method proposed here can improve the solving accuracy apparently because generalized stress and strain are interpolated separately. In addition, compared with commonly used Daubechies wavelet finite element method, BSWI has explicit expression and a very good approximation property which guarantee the satisfying results. The efficiency of the proposed multivariable Reissner-Mindlin plate elements are verified through some numerical examples in the end.

The construction of multivariable Reissner-Mindlin plate elements based on B-spline wavelet on the interval

Zhang, Xingwu,Chen, Xuefeng,He, Zhengjia Techno-Press 2011 Structural Engineering and Mechanics, An Int'l Jou Vol.38 No.6

In the present study, a new kind of multivariable Reissner-Mindlin plate elements with two kinds of variables based on B-spline wavelet on the interval (BSWI) is constructed to solve the static and vibration problems of a square Reissner-Mindlin plate, a skew Reissner-Mindlin plate, and a Reissner-Mindlin plate on an elastic foundation. Based on generalized variational principle, finite element formulations are derived from generalized potential energy functional. The two-dimensional tensor product BSWI is employed to form the shape functions and construct multivariable BSWI elements. The multivariable wavelet finite element method proposed here can improve the solving accuracy apparently because generalized stress and strain are interpolated separately. In addition, compared with commonly used Daubechies wavelet finite element method, BSWI has explicit expression and a very good approximation property which guarantee the satisfying results. The efficiency of the proposed multivariable Reissner-Mindlin plate elements are verified through some numerical examples in the end.

Morphology and ultrastructure of the male reproductive system of the jewel wasp, Nasonia vitripennis (Walker) (Hymenoptera: Pteromalidae)

Nai-Yong Liu,Guo-XingWu,Sang-Zi Ze,Bin Yang,Jia-Ying Zhu 한국응용곤충학회 2017 Journal of Asia-Pacific Entomology Vol.20 No.2

The genital systems of insects are undoubtedly of great key for the success of mating and population reproduction. In the meantime,morphological and ultrastructural characteristics of the reproductive systems also provide valuable evidences for the studies of taxonomy, reproductive biology and evolutionary biology.More previously, the reproductive systemof female Nasonia vitripennis was already described. To complement the information of reproductive systems from this species, the male reproductive system was here dissected and characterized by light microscopy and transmission electron microscopy. Results showed that the system follows the pattern of most Hymenoptera species: paired testes with one follicle, deferent ducts, seminal vesicles, accessory glands and a fused ejaculatory duct ultimately connected to the external aedeagus. Histologically, the testes, seminal vesicles and accessory glands are all composed of three portions, all of which include epithelial and luminal regions. In addition, both lipidic inclusions and nuclei are presented in the three organs with variable sizes and shapes. Spermatozoa are observed in the testes and seminal vesicles, and also vary considerably in size and shape, suggesting different phases of spermatogenesis.Mitochondria are abundant in seminal vesicles and accessory glands. Notably, membranous inclusions and Golgi complexes are found only in seminal vesicles, whereas secretory granules are presented only in accessory glands, being indicative of organ or age specificity. Together, this study complements the information of the reproductive systems from N. vitripennis, and provides an extensive resource for taxonomy, reproductive biology and evolutionary biology.

Damage detection using the improved Kullback-Leibler divergence

Shaohua Tian,Xuefeng Chen,Zhibo Yang,Zhengjia He,Xingwu Zhang 국제구조공학회 2013 Structural Engineering and Mechanics, An Int'l Jou Vol.48 No.3

Structural health monitoring is crucial to maintain the structural performance safely. Moreover, the Kullback-Leibler divergence (KLD) is applied usually to asset the similarity between different probability density functions in the pattern recognition. In this study, the KLD is employed to detect the damage. However the asymmetry of the KLD is a shortcoming for the damage detection, to overcoming this shortcoming, two other divergences and one statistic distribution are proposed. Then the damage identification by the KLD and its three descriptions from the symmetric point of view is investigated. In order to improve the reliability and accuracy of the four divergences, the gapped smoothing method (GSM) is adopted. On the basis of the damage index approach, the new damage index (DI) for detect damage more accurately based on the four divergences is developed. In the last, the grey relational coefficient and hypothesis test (GRCHT) is utilized to obtain the more precise damage identification results. Finally, a clear remarkable improvement can be observed. To demonstrate the feasibility and accuracy of the proposed method, examples of an isotropic beam with different damage scenarios are employed so as to check the present approaches numerically. The final results show that the developed approach successfully located the damaged region in all cases effect and accurately.

Damage detection using the improved Kullback-Leibler divergence

Tian, Shaohua,Chen, Xuefeng,Yang, Zhibo,He, Zhengjia,Zhang, Xingwu Techno-Press 2013 Structural Engineering and Mechanics, An Int'l Jou Vol.48 No.3

Structural health monitoring is crucial to maintain the structural performance safely. Moreover, the Kullback-Leibler divergence (KLD) is applied usually to asset the similarity between different probability density functions in the pattern recognition. In this study, the KLD is employed to detect the damage. However the asymmetry of the KLD is a shortcoming for the damage detection, to overcoming this shortcoming, two other divergences and one statistic distribution are proposed. Then the damage identification by the KLD and its three descriptions from the symmetric point of view is investigated. In order to improve the reliability and accuracy of the four divergences, the gapped smoothing method (GSM) is adopted. On the basis of the damage index approach, the new damage index (DI) for detect damage more accurately based on the four divergences is developed. In the last, the grey relational coefficient and hypothesis test (GRCHT) is utilized to obtain the more precise damage identification results. Finally, a clear remarkable improvement can be observed. To demonstrate the feasibility and accuracy of the proposed method, examples of an isotropic beam with different damage scenarios are employed so as to check the present approaches numerically. The final results show that the developed approach successfully located the damaged region in all cases effect and accurately.

Evaluating optimum tilt angle for PV modules using solar radiation models in Wuhan, China

Fen. Li,Nianjun. Ma,Jinbin. Zhao,Keqing. Qu,Xingwu. Yang,Zhenghong. Chen 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

Four models are used to estimate the hourly solar radiation on 15 pieces of different tilted photovoltaic (PV) modules in Wuhan, China based on power and solar radiation data during a whole year. The optimum tilt angle (OTA) in Wuhan for yearly and semi-yearly adjustment was determined. Then it was determined that the best mode is the tilt angle of PV module adjusted every half a year. In semi-yearly adjustment, OTA in semi-year of winter and summer is found as 45°, 15°, respectively. Experimental results verify the theoretical calculated values of the OTA with high precision. Energy radio (ER) reveals PV modules with adjustment of tilt angle twice a year has a capability to improve nearly 7% in comparison with fixed type. The best model was chosen based on test results from statistical indicators. The statistical results demonstrate that among the studied models, Liu&Jordan model is the most accurate.