http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
- 中文 을 입력하시려면 zhongwen을 입력하시고 space를누르시면됩니다.
- 北京 을 입력하시려면 beijing을 입력하시고 space를 누르시면 됩니다.
RISS 인기검색어
- 검색키워드
- 저자 : Jianguo Chang (검색결과 5 건)
- 무료
- 기관 내 무료
- 유료
-
Interfacial micromechanics modeling for bolted joints in ultra-precision machine tools
Yu Chang,Jianguo Ding,Hui Fan,Yuanyuan Ding,Hui Zhuang,Peng Chen 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.8
Bolted joints are widely adopted in various mechanical structures. However, the uncertainty and complexity of the contact surfaces affect accurate modeling. Herein, an interfacial micromechanics model is proposed to characterize the contact behaviors of bolted joints in an ultra-precision machine tool (UMT). The bolted joint is modeled as a virtual material layer with transversely isotropic behaviors, whose constitutive relation is identified by fractal theory. The proposed model accurately formulates the multi-scale contact characteristics and allows convenient integration with the structural dynamic modeling of UMT. Dynamic analysis of the simulation results and the experimental measurements in the time and frequency domains was conducted to identify the most sensitive factor affecting the tool tip vibration. On this basis, the structural optimization for the UMT was further implemented, which effectively reduced vibration by 15.5 %. The dynamic predictions were validated by modal and vibration response tests.
-
Nailong Gao,Jianguo Chang,Ziming Zhu,Hui You 한국바이오칩학회 2021 BioChip Journal Vol.15 No.3
Sufficiently long reaction time and low flow velocity are crucial for capillary microfluidic immunoassay chips, especially for truly “one-step” detection with continuous on-chip labelling and capturing. In this study, a multistory stairs-based new delay valve is used to meet the time and flow requirements for protein testing. The delay strategy is capable of slowing down the flow of liquid into the functional region and delaying the time out of the regions as well, thus extending the labelling and capture time to about 100 and 60 s respectively, and further reducing the flow velocity to below 8 μL/min. Based on the principle of sandwich-like immunocomplex, the designed chip is capable of automatically accomplishing on-chip mixing, labelling and capturing procedures via once sample loading and sensitively detecting human Alpha-Fetoprotein (AFP) in 40 μL serum with a wide dynamic ranging from 10 ng/mL to 10 000 ng/mL within 5 min. It could be foreseeable that this microchip has great potential in biomarkers clinical testing.
-
Hui Zhuang,Jianguo Ding,Peng Chen,Yu Chang,Xiaoyun Zeng,Hong Yang,Xingbao Liu,Wei Wei 한국정밀공학회 2021 International Journal of Precision Engineering and Vol.22 No.10
In this paper, four waviness types are presented to investigate the effect of surface waviness on the static performance, dynamic performance and stability of an aerostatic thrust bearing with orifice-type restrictor. The influences of wave amplitude and rotational speed on the bearing performances are studied. The Reynolds equation is first solved through small perturbation method to obtain the static and dynamic characteristics. Subsequently, by adopting an iterative method based on the acquired dynamic coefficients, a numerical method is proposed to analyze the bearing stability. The calculated critical supply pressure is compared with that obtained by the traditional orbit method and it indicates that the proposed method has higher computational efficiency. The results show that the surface waviness has great influence on the bearing performances and the effect becomes increasingly pronounced with the growth of wave amplitude. The performances are more sensitive to the waviness arranged in bearing radial direction than circumferential direction. The enhancement of certain performance is always accompanied by the decline of another performance for the bearing with wave pattern on the surface, which leads to the fact that the bearing performances cannot be comprehensively improved in static characteristic, dynamic characteristic and stability. Besides, high rotational speed will cause pneumatic instability more readily. Finally, a stiff ness measuring experiment and a modal test are performed to verify the accuracy of computational analysis and results.
-
Li, Junjie,Chang, Xiangyu,Yang, Dirui,Liu, Yunlong,Jiang, Jianguo The Korean Institute of Power Electronics 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.6
To achieve a fast dynamic response and to solve the multi-objective control problems of the output currents, capacitor voltages and system constraints, this paper proposes a deadbeat and hierarchical predictive control with space-vector modulation (DB-HPC-SVM) for five-level nested neutral point piloted (NNPP) converters. First, deadbeat control (DBC) is adopted to track the reference currents by calculating the deadbeat reference voltage vector (DB-RVV). After that, all of the candidate switching sequences that synthesize the DB-RVV are obtained by using the fast SVM principle. Furthermore, according to the redundancies of the switch combination and switching sequence, a hierarchical model predictive control (MPC) is presented to select the optimal switch combination (OSC) and optimal switching sequence (OSS). The proposed DB-HPC-SVM maintains the advantages of DBC and SVM, such as fast dynamic response, zero steady-state error and fixed switching frequency, and combines the characteristics of MPC, such as multi-objective control and simple inclusion of constraints. Finally, comparative simulation and experimental results of a five-level NNPP converter verify the correctness of the proposed DB-HPC-SVM.
-
Junjie Li,Xiangyu Chang,Dirui Yang,Yunlong Liu,Jianguo Jiang 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.6
To achieve a fast dynamic response and to solve the multi-objective control problems of the output currents, capacitor voltages and system constraints, this paper proposes a deadbeat and hierarchical predictive control with space-vector modulation (DB-HPC-SVM) for five-level nested neutral point piloted (NNPP) converters. First, deadbeat control (DBC) is adopted to track the reference currents by calculating the deadbeat reference voltage vector (DB-RVV). After that, all of the candidate switching sequences that synthesize the DB-RVV are obtained by using the fast SVM principle. Furthermore, according to the redundancies of the switch combination and switching sequence, a hierarchical model predictive control (MPC) is presented to select the optimal switch combination (OSC) and optimal switching sequence (OSS). The proposed DB-HPC-SVM maintains the advantages of DBC and SVM, such as fast dynamic response, zero steady-state error and fixed switching frequency, and combines the characteristics of MPC, such as multi-objective control and simple inclusion of constraints. Finally, comparative simulation and experimental results of a five-level NNPP converter verify the correctness of the proposed DB-HPC-SVM.
연관 검색어 추천
이 검색어로 많이 본 자료
활용도 높은 자료
