High-Frequency Modeling and Optimization of E/O Response and Reflection Characteristics of 40 Gb/s EML Module for Optical Transmitters

Chengzhi Xu,Y.Z. Xu,Yanli Zhao,Kunzhong Lu,Weihua Liu,Shibing Fan,Hui Zou,Wen Liu 한국전자통신연구원 2012 ETRI Journal Vol.34 No.3

A complete high-frequency small-signal circuit model of a 40 Gb/s butterfly electroabsorption modulator integrated laser module is presented for the first time to analyze and optimize its electro-optic (E/O) response and reflection characteristics. An agreement between measured and simulated results demonstrates the accuracy and validity of the procedures. By optimizing the bonding wire length and the impedance of the coplanar waveguide transmission lines, the E/O response increases approximately 5% to 15% from 20 GHz to 33 GHz, while the signal injection efficiency increases from approximately 15% to 25% over 18 GHz to 35 GHz.

Modification of biomass furan-based PEF copolyester with glycerol

Chengzhi Liu,Dongsheng Zhao,Maliang Zhang,Kunmei Su,Zhenhuan Li 한국고분자학회 2024 Macromolecular Research Vol.32 No.1

In order to solve the problem of low molecular weight in the synthesis of poly(ethylene 2,5-furandicarboxylate) (PEF) copolyester with titanium-based catalysts, this paper introduce an appropriate amount of glycerol (GC) into PEF to branch the straight chain polyester though the transesterification-melt polycondensation method, which solve the problem of low resin viscosity and low molecular weight. The structures of the copolymers were characterized by 1H-NMR and 13C-NMR, and the results showed that the modified PEF copolyesters and poly(ethylene-co-glycerol 2,5-furandicarboxylate) (PEGFs) were successfully prepared. The intrinsic viscosity ([η]) of PEGFs copolyesters was characterized by Ubbelohde viscosity, and the results showed that the copolyester [η] was increased from 0.25 dL/g to 0.755 dL/g. The thermal properties of copolyester were characterized by differential scanning calorimetry and thermo gravimetry, and it was found that the glass transition temperature of PEGFs copolyester increased from 67.8 °C to 89.5 °C, and the maximum pyrolysis rate temperature increased from 386.6 °C to 402.8 °C. We characterized the UV resistance of PEGFs copolyester, and the results showed that PEGFs copolyester could be well degraded under ultraviolet light.

Low Chattering Trajectory Tracking Control of Non-singular Fast Terminal Sliding Mode Based on Disturbance Observer

Jiqing Chen,Chaoyang Zhao,Qingsong Tang,Xu Liu,Zhikui Wang,Chengzhi Tan,Jiahua Wu,Teng Long 제어·로봇·시스템학회 2023 International Journal of Control, Automation, and Vol.21 No.2

The improvement of the performance of the multi-joint manipulator control system is of great significance to improve the level of industrial automation. The existing sliding mode control methods are difficult to ensure the high-precision and fast-tracking of joints of a manipulator to the desired trajectory under low chattering control input. Therefore, a non-singular fast terminal sliding mode control method based on a nonlinear disturbance observer is proposed. In addition, a new non-singular fast terminal sliding mode surface is designed. The performance comparison method of the sliding mode surface proves its better control quality. Aiming at the problem of serious chattering, the nonlinear disturbance observer technology, and saturation function method are introduced to effectively weaken the chattering. Finally, taking the 3-DOF manipulator as the research object, a comparative simulation experiment is carried out in the MATLAB / Simulink environment. The results show that under the uncertainty of modeling error, external disturbance, and joint friction, the designed control method not only solves the problems of singular control input and serious chattering but also realizes the high-precision and fast-tracking of each joint to the desired trajectory. Thus, the effectiveness and feasibility of the design method are verified. The improvement of the performance of the multi-joint manipulator control system is of great significance to improve the level of industrial automation. The existing sliding mode control methods are difficult to ensure the high-precision and fast-tracking of joints of a manipulator to the desired trajectory under low chattering control input. Therefore, a non-singular fast terminal sliding mode control method based on a nonlinear disturbance observer is proposed. In addition, a new non-singular fast terminal sliding mode surface is designed. The performance comparison method of the sliding mode surface proves its better control quality. Aiming at the problem of serious chattering, the nonlinear disturbance observer technology, and saturation function method are introduced to effectively weaken the chattering. Finally, taking the 3-DOF manipulator as the research object, a comparative simulation experiment is carried out in the MATLAB / Simulink environment. The results show that under the uncertainty of modeling error, external disturbance, and joint friction, the designed control method not only solves the problems of singular control input and serious chattering but also realizes the high-precision and fast-tracking of each joint to the desired trajectory. Thus, the effectiveness and feasibility of the design method are verified.

Refolding Behavior of Urea-Induced Denaturation Collagen

Xu Wei,Yanqiu Zhao,Jingjing Zheng,Qin Cao,Sheng Li,Lang He,Benmei Wei,Juntao Zhang,Chengzhi Xu,Haibo Wang 한국고분자학회 2021 Macromolecular Research Vol.29 No.6

Exploration of the denaturation and refolding of natural collagen is important for the application of collagen and its denatured products. In this study, using urea as a denaturant, we prepared a denatured natural collagen product and analyzed its structural changes. The denaturation treatment severely destroyed the triple helix conformation of collagen, but had no significant effect on the primary structure of its α chains or the covalent cross-linking between α chains. Next, we observed the refolding behavior of the denatured collagen by removing urea through dialysis. We found that the denatured collagen products from different sources (grass carp skin, bovine tendon) all showed a reconstruction of the triple helix conformation up to 60-75% of the value of natural collagen during the refolding process. The telopeptide did not significantly promote triple helix reconstruction. In conclusion, the reconstruction of the α chains did not perfectly occur in a “head-to-head, tail-to-tail” manner in refolded collagen, as each α chain was participating in the reconstruction of multiple triple helix domains. The refolded collagen still had weak self-assembly ability and formed a unique network-like structure containing small interlaced and closely combined fibers, which shows favorable cell compatibility and potential applications.

Investigation on Texture Evolution Mechanism of NiTiFe Shape Memory Alloy Under Plane Strain Compression

Yulong Liang,Qiang He,Shuyong Jiang,Chengzhi Zhao 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.10

Texture evolution of NiTiFe shape memory alloy (SMA) is investigated during plane strain compression based on crystalplasticity finite element method (CPFEM) and electron back-scatter diffraction (EBSD) experiment. The deformation texturesof NiTiFe SMA are not influenced very considerably after experiencing recrystalline annealing at 600 °C for 1 h. Based onthe results of CPFEM, the main activated slip systems of NiTiFe SMA are ⟨100⟩/{110} and ⟨111⟩/{110} ones during planestrain compression. According to the relationship between texture components and activated slip systems put forward in thisstudy, ⟨110⟩ direction would rotate to rolling direction, whereas ⟨100⟩ and ⟨111⟩ directions would rotate to normal direction. These rotations contribute to the formation of γ-fibre texture and α-fibre texture in NiTiFe SMA. The deformation texturecomponents predicted by CPFEM and determined by EBSD were compared with each other in detail. Due to the startupof the pencil glide and multiple slip in the refined microstructure, there are some differences between texture componentspredicted by CPFEM and texture components determined by EBSD. The deformation heterogeneity is discussed in termsof rotation angle at each integration point in the study.

A New Method for Integrated End-to-End Delay Analysis in ATM Networks

Ng, Joseph Kee-Yin,Song, Shibin,Li, Chengzhi,Zhao, Wei The Korean Institute of Communications and Informa 1999 Journal of communications and networks Vol.1 No.3

For admitting a hard real-time connection to an ATM network, it is required that the end-새둥 delays of cells belong-ing to the connection meet their deadlines without violating the guarantees already provided to the currently active connections. There are two kinds of methods to analyze the end-to-end delay in an ATM network. A decomposed method analyzes the worst case delay for each switch and then computes the total delay as the sum of the delays at individual switches. On the other hand, an integrated method analyzes all the switches involved in an inte-grated manner and derives the total delay directly. In this paper, we present an efficient and effecitive integrated method to compute the end-to-end delay. We evaluate the network performance under different system parameters and we compare the performance of the proposed method with the conventional decomposed and other integrated methods [1], [3], [5]-[9].