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Shuhao Zhu,Pengcheng Zhu,Binbin Wang,Liang Zhang,Yufeng Sun,Shaokang Guan 대한금속·재료학회 2024 METALS AND MATERIALS International Vol.30 No.1
This study proposes a method to improve the mechanical strength of martensitic welded joints by minimizing the effect ofmartensitic tempering. The high-strength martensitic steel plate exhibiting a tensile strength of 1500 MPa was successfullyjoined in this study utilizing additional water-cooling by friction stir welding (FSW) technique. Concurrently, conventionalair-cooled welded joints were produced utilizing identical welding parameters for comparison. Notwithstanding the macrostructureof both FSW joints was similar, the air-cooled joint contained a larger stir zone (SZ) and wider heat-affectedzone (HAZ). The air-cooled joint SZ exhibited a microstructure featuring coarse martensite, while the water-cooled jointSZ displayed a microstructure consisting of fine martensite. The degree of self-tempering of the martensite in the HAZ wassignificantly reduced, together with fewer and finer carbide particles than in the HAZ of air-cooled joints, by applying watercooling. The tensile test results indicated that the water-cooled FSW joint showed a significant improvement (23.6%) inultimate tensile strength compared to its air-cooled counterparts.
Diversity-Guided Dynamic Step Firefly Algorithm
Shuhao Yu,Shenglong Zhu,Renjin Liu,Xiancun Zhou 보안공학연구지원센터 2016 International Journal of Hybrid Information Techno Vol.9 No.8
Firefly Algorithm is a nature-inspired optimization method, which has been shown to implement well on numerous optimization problems. But it can easily fall into the local optima and low precision. Therefore, it is very important to overcome these defects. In this paper, we use a dynamic strategy for step setting, which takes into account the population diversity of fireflies. The experiments show that the proposed algorithm improves the performance of original firefly algorithm.
An Improved Firefly Algorithm Based on Nonlinear Time-varying Step-size
Shuhao Yu,Shenglong Zhu,Xiancun Zhou 보안공학연구지원센터 2016 International Journal of Hybrid Information Techno Vol.9 No.7
Firefly algorithm (FA) is a novel population-based stochastic optimization algorithm and has been shown to yield good performance for solving varieties of optimization problems. Meanwhile, it sustains premature convergence because it is easily to fall into the local optima which may generate a low accuracy of solution or even fail. To overcome this defect, a nonlinear time-varying step strategy for firefly algorithm (NTSFA) is presented. It uses a nonlinear decreasing and time-varying step-size for fireflies to better balance the algorithm’s ability of exploration and exploitation. Numerical simulation on 20 test benchmark functions display that the proposed algorithm can increase the accuracy of the original FA. Finally, we apply NTSFA to integrate into k-means clustering for mouse dataset. The results show that NTSFA is an effective optimization algorithm.
Shuhao Deng,Yao Sun,Jian Yang,Qi Zhu,Mei Su 전력전자학회 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.6
The full-bridge inverter, widely used for single-phase photovoltaic grid-connected applications, presents a leakage current issue. Therefore, an AC bypass branch is introduced to overcome this challenge. Nevertheless, existing modulation strategies entail drawbacks that should be addressed. One is the zero-crossing distortion (ZCD) of the AC current caused by neglecting the AC filter inductor voltage. Another is that the system cannot deliver reactive power because the AC bypass branch switches at the power frequency. To address these problems, this work proposes an optimized hybrid modulation strategy. To reduce ZCD, the phase angle of the inverter output voltage reference is shifted, thereby compensating for the neglected leading angle. To generate the reactive power, the interval of the negative power output is calculated using the power factor. In addition, the freewheeling switch is kept on when power is flowing into the grid and commutates at a high frequency when power is fed back to the DC side. In this manner, the dead-time insertion in the high-frequency switching area is minimized. Finally, the performances of the proposed modulation strategy and traditional strategies are compared on a universal prototype inverter. Experimental results validate the theoretical analysis.
Deng, Shuhao,Sun, Yao,Yang, Jian,Zhu, Qi,Su, Mei The Korean Institute of Power Electronics 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.6
The full-bridge inverter, widely used for single-phase photovoltaic grid-connected applications, presents a leakage current issue. Therefore, an AC bypass branch is introduced to overcome this challenge. Nevertheless, existing modulation strategies entail drawbacks that should be addressed. One is the zero-crossing distortion (ZCD) of the AC current caused by neglecting the AC filter inductor voltage. Another is that the system cannot deliver reactive power because the AC bypass branch switches at the power frequency. To address these problems, this work proposes an optimized hybrid modulation strategy. To reduce ZCD, the phase angle of the inverter output voltage reference is shifted, thereby compensating for the neglected leading angle. To generate the reactive power, the interval of the negative power output is calculated using the power factor. In addition, the freewheeling switch is kept on when power is flowing into the grid and commutates at a high frequency when power is fed back to the DC side. In this manner, the dead-time insertion in the high-frequency switching area is minimized. Finally, the performances of the proposed modulation strategy and traditional strategies are compared on a universal prototype inverter. Experimental results validate the theoretical analysis.
Wang, Shuhao,Zhang, Lin,Li, Jiaolong,Cong, Jiahui,Gao, Feng,Zhou, Guanghong Asian Australasian Association of Animal Productio 2017 Animal Bioscience Vol.30 No.1
Objective: This experiment was conducted to investigate the effects of dietary supplementation with marigold extract on growth performance, pigmentation, antioxidant capacity and meat quality in broiler chickens. Methods: A total of 320 one-day-old Arbor Acres chickens were randomly divided into 5 groups with 8 replicates of 8 chickens each. The chickens of control group were fed with basal diet and other experimental groups were fed with basal diet supplemented with 0.075%, 0.15%, 0.30%, and 0.60% marigold extract respectively (the corresponding concentrations of lutein were 15, 30, 60, and 120 mg/kg). Results: The results showed that marigold extract supplementation increased the yellowness values of shank, beak, skin and muscle and the redness ($a^*$) value of thigh muscle (linear, p<0.01). Marigold extract supplementation significantly increased the total antioxidant capacity, and the activities of superoxide dismutase in liver and thigh muscle (linear, p<0.01) and significantly decreased the malondialdehyde contents of liver and thigh muscle (linear, p<0.01). Marigold extract supplementation significantly decreased the drip loss and shear force of thigh muscles (linear, p<0.01). There was no significant effect on growth performance with marigold extract supplementation. Conclusion: In conclusion, dietary supplementation of marigold extract significantly increased the yellowness values of carcass, antioxidant capacity and meat quality in broiler chickens.