Reuse-oriented common structure discovery in assembly models

Pan Wang,Jie Zhang,Yuan Li,Jianfeng Yu 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.1

Discovering the common structures in assembly models provides designers with the commonalities that carry significant design knowledge across multiple products, which helps to improve design efficiency and accelerate the design process. In this paper, a discovery method has been developed to obtain the common structure in assembly models. First, this work proposes a graph descriptor that captures both the geometrical and topological information of the assembly model, in which shape vectors and link vectors quantitatively describe the part models and mating relationships, respectively. Then, a clustering step is introduced into the discovery, which clusters the similar parts by comparing the similarities between them. In addition, some rules are also provided to filter the frequent subgraphs in order to obtain the expected results. Compared with the existing method, the proposed approach could overcome the disadvantages by providing an independent description of the part model and taking into consideration the similar parts in assemblies, which leads to a more reasonable result. Finally, some experiments have been carried out and the experimental results demonstrate the effectiveness of the proposed approach.

Phase lag compensation for improving the stability of LCL‑type converters under weak grid condition

Jianfeng Wang,Guobing Pan,Jing Ouyang,Chengyao Liu,Yinghao Zhou,Gong Fei 전력전자학회 2022 JOURNAL OF POWER ELECTRONICS Vol.22 No.5

LCL-type converters are widely used in the sustainable energy generation system due to their flexible current control strategies and high efficiency. The LCL filter has a resonance peak, which needs to be handled appropriately; otherwise, it causes system instability. Single-loop feedback control strategy is very popular at present; it does not require additional sensors to measure the state variables for active damping. Under weak grid condition, the resonance peak of LCL filter shifts to the left evidently and greatly reduces the stability margin; thus, maintaining the stability of single-loop control is a challenging task. This paper presents an improved grid current feedback (GCF) single-loop control strategy, which is designed to raise the stability margin of system to adapt weak grid condition. Low pass filter controller is used for phase lag compensation. A phase margin design method is proposed to ensure system stability, and the corresponding discrete method in z-domain has been proposed in detail. Experiments performed on a three-phase converter platform are finally presented to verify the effectiveness of the proposed phase lag compensation for GCF control strategy.

Constant current/voltage characteristics inductive power transfer system with variable static S-T/FC compensation

Jianfeng Hong,Fei Pan,Ziheng Zhang,Jia Teng,Dekai He 전력전자학회 2024 JOURNAL OF POWER ELECTRONICS Vol.24 No.3

Continuous mode changes during battery charging present a significant challenge for the application of inductive power transfer (IPT) in battery charging. Achieving constant-current (CC) and constant-voltage (CV) charging characteristics is crucial for its successful implementation. This paper proposes a variable static S-T/FC compensation topology based on switching state changes. It offers the advantages of being able to handle various load conditions, facilitating soft switching of the inverter throughout the operation process, and achieving CC and CV charging without changing the operating frequency of the system. The characteristics of the proposed topology were confirmed through a theoretical analysis. Additionally, a completely new parameter design method is proposed. The CC and CV characteristics of the proposed topology are verified through theoretical derivation and simulation analysis. Finally, a validation prototype is constructed to assess the feasibility and rationality of the proposed method, achieving a 3.5 A output current in the CC mode and a 70 V output voltage in the CV mode.

Efficient Expression and Purification of Recombinant Alcohol Oxidase in Pichia pastoris

Yunping Liu,Jianfeng Pan,Peilian Wei,Jianzhong Zhu,Lei Huang,Jin Cai,Zhinan Xu 한국생물공학회 2012 Biotechnology and Bioprocess Engineering Vol.17 No.4

In order to improve the production of alcohol oxidase (AOX), a recombinant Pichia pastoris (P. pastoris)system was constructed by transformation of the plasmid pPIC9K-AOX into P. pastoris GS115. The effects of different expression conditions on alcohol oxidase activity in the culture supernatant were investigated in the shake flask scale. The results showed that the highest extracellular activity (562 U/L) of alcohol oxidase was obtained after 56h induction with 4% methanol at OD600 1.0 in the medium containing 50 g/L maltose, which is about 4.2 folds higher than previously reported. High-purity functional recombinant AOX (>90%) was purified from the culture with the Ni-NTA affinity column and Sephadex G-100 chromatographical methods, with a total recovery rate of 68.9%. Further studies showed that the purified rAOX had similar enzymatic characteristics as the native enzyme, except that the thermal stability and resistance to H2O2 inhibition of rAOX were significantly greater compared to the previous report. The purified rAOX was well tolerant to various water-miscible organic solvents. This efficient expression and purification process will be promising for large-scale production of rAOX as an important diagnostic enzyme for alcohol detection in many areas.

Preparation and characterization of molecularly-imprinted magnetic microspheres for adsorption of 2,4,6-trichlorophenol from aqueous solutions

Ping Yu,Qilong Sun,Jianfeng Li,Zhenjiang Tan,Jianming Pan,Yongsheng Yan 한국화학공학회 2015 Korean Journal of Chemical Engineering Vol.32 No.4

Magnetic molecularly imprinted microspheres (MMIS) were successfully prepared by suspension polymerization,and then as-prepared MMIS were used as adsorbents for selective recognition of 2,4,6-trichlorophenol (2,4,6-TCP) from aqueous solutions. The results composites were characterized by Fourier transform infrared (FT-IR), X-raydiffraction (XRD), thermo gravimetric analysis (TGA), scanning electron microscope (SEM) and vibrating samplemagnetometer (VSM). The results demonstrated that MMIS possesses porous spherical morphology, and exhibits goodthermal stability and magnetic property (Ms=10.14 emu g−1). Then batch mode of binding experiments was used todetermine the equilibrium, kinetics and selectivity recognition. The Langmuir isotherm model fitted the equilibriumdata better than did the Freundlich model, and the maximum adsorption capacity on MMIS was about 1.7 times higherthan that of MNIS. Kinetics behaviors of MMIS were well described by the pseudo-second-order model. MMIS possessedoutstanding selectivity recognition for 2,4,6-TCP in the presence of other competitive phenols (such as sesamol,3-CP, thymol, 2,4-DCP). Furthermore, the reusability performance of MMIS showed about 17.53% loss after five repeatedcycles. Finally, the MMIS were successfully applied to the selective extraction of 2,4,6-TCP from the vegetablesamples.

Fast-convergence trilinear decomposition algorithm for angle and range estimation in FDA-MIMO radar

Wang, Cheng,Zheng, Wang,Li, Jianfeng,Gong, Pan,Li, Zheng Electronics and Telecommunications Research Instit 2021 ETRI Journal Vol.43 No.1

A frequency diverse array (FDA) multiple-input multiple-output (MIMO) radar employs a small frequency increment across transmit elements to produce an angle-range-dependent beampattern for target angle and range detection. The joint angle and range estimation problem is a trilinear model. The traditional trilinear alternating least square (TALS) algorithm involves high computational load due to excessive iterations. We propose a fast-convergence trilinear decomposition (FC-TD) algorithm to jointly estimate FDA-MIMO radar target angle and range. We first use a propagator method to obtain coarse angle and range estimates in the data domain. Next, the coarse estimates are used as initialized parameters instead of the traditional TALS algorithm random initialization to reduce iterations and accelerate convergence. Finally, fine angle and range estimates are derived and automatically paired. Compared to the traditional TALS algorithm, the proposed FC-TD algorithm has lower computational complexity with no estimation performance degradation. Moreover, Cramer-Rao bounds are presented and simulation results are provided to validate the proposed FC-TD algorithm effectiveness.