http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Chuan-Dong Bai,Tong Mu,Zhong-Hua Pang,Jian Sun,Guo-Ping Liu 제어·로봇·시스템학회 2023 International Journal of Control, Automation, and Vol.21 No.2
In this paper, the output tracking control problem is investigated for a networked control system with twochannel random network delays and packet dropouts as well as stochastic noise. To actively compensate for these random communication constraints in the feedback and forward channels, a novel networked predictive control (NPC) method is proposed based on the input-output difference equation model, where the two-channel communication constraints are handled separately according to their different features. Furthermore, different from the existing NPC methods based on round-trip time delays, actual control inputs rather than the predicted ones are employed to generate future control commands. Then a delay-independent closed-loop stability condition is obtained, and a condition to guarantee a zero steady-state output tracking error is derived. Also, theoretical analysis shows that the proposed NPC method can achieve the same output tracking performance as the corresponding local control system. Finally, the effectiveness of the proposed method is evaluated by simulation and experimental results.
Xiao‑Bo Mei,Bao‑Chuan Liu,Wei Jiang,Quan Xu,Qi‑Dong Zhang,Yu‑Bai Ma,Fang‑Qiu Zu 대한금속·재료학회 2020 METALS AND MATERIALS International Vol.26 No.9
The influence of cooling rates on the mechanical properties of a Zr-based bulk metallic glass prepared with high rheologicalrate forming (HRRF) was investigated and compared with traditional suction cast methods. Amorphous samples of Zr57Cu-20Ni8Al10Ag5 were prepared in copper molds with different sizes in order to obtain different cooling rates for both HRRFand traditional cast methods. These specimens were subjected to compression experiments, including microhardness testing,X-ray diffraction testing and differential scanning calorimetry analysis. The results indicate that the plasticity of the samplesformed by HRRF are higher than that of the as-cast ones at the same cooling rates, while the microhardness manifests theopposite principle. As the cooling rate increases further, the difference in plasticity further increases between two methods,indicating that the plasticity of metallic glasses is more sensitive to cooling rates during the HRRF process. At the core ofthis phenomenon is the fact that HRRF methods can introduce more free volume into glasses than traditional cast methodswith an elevated cooling rate are able to.
Xiao Cui,Jing Guo,Qi‑dong Zhang,Xiao‑jun Meng,Bing‑chuan Bian,Ren‑gao Zhao,Yu‑bai Ma,Fang‑qiu Zu 대한금속·재료학회 2020 METALS AND MATERIALS International Vol.26 No.10
The slow β relaxation which occurring at temperatures far below glass transition temperature, typically playing importantroles in the plastic deformation behavior of metallic glasses. Compared with polymer glasses, most of the metallic glasses donot exhibit obvious β relaxation based on dynamic mechanical analysis. In the current work, prominent β relaxation behaviorsof a series (LaxCe100−x) Al10Co25(x = 50, 60, 70, 80) bulk metallic glasses (BMGs) at low temperature are observed usingdynamic mechanical analysis. Compared with other BMGs, the LaCe based BMGs show a pronounced β relaxation peak andrelative low peak temperature, the activation energy of the β relaxation based on Arrhenius equation are calculated around79.3 kJ/mol to 86.4 kJ/mol, which obey an empirical rule that Eβ ≈ (26 ± 4) RTg, with the coefficient of 23. Experimentalresults from room temperature compression tests for the LaCe based BMGs indicate that low temperature activated β relaxationbehaviors facilitate the good plasticity of the LaCe based BMGs.