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141 results on '"Chen, Zhengpeng"'

28. Syringaldehyde‐DOPO derivative for enhancing flame retardancy and mechanical properties of epoxy resin.

Author

Chen, Zhengpeng, He, Xin, Cao, Zhengshuai, Li, Yunfan, Chen, Denglong, Yang, Zhiwang, and Lei, Ziqiang

Subjects
HEAT release rates, FIREPROOFING, ELECTRONIC packaging, RESIN adhesives, PACKAGING materials, EPOXY resins
Abstract

With the wide application of epoxy resins in adhesives, electronic packaging materials, and aerospace fields, it is necessary to prepare high‐performance flame‐retardant epoxy resins to reduce the fire risk caused by their flammability. In this study, the rigid structure intermediate Schiff base (DMDA‐SH) was synthesized by condensation reaction of syringaldehyde (SH) with O‐Tolidine (DMDA). Then, DMDA‐SH‐DOPO, a novel P/N‐structured biobased flame‐retardant curing agent, was synthesized by addition reaction with 9,10‐dihydro‐9‐oxaza‐10‐phosphame‐10‐oxide (DOPO) and was applied to the preparation of intrinsic flame‐retardant epoxy resin. As expected, DMDA‐SH‐DOPO has good flame‐retardant properties due to the synergistic action of N/P elements. Epoxy resin with only 2.5% DMDA‐SH‐DOPO (P = 0.16%) can pass the UL‐94 V‐0 test. Compared with DGEBA/DDM, DMDA‐SH‐DOPO‐7.5's (P = 0.49%) peak heat release rate was reduced by 48.4% and the limiting oxygen index (LOI) reached 27%, making it a flame‐retardant material. From the point of view of carbonaceous residue performance, the expansion height of carbon residue after DMDA‐SH‐DOPO‐7.5 combustion is significantly increased, and the amount of carbon residue at 800°C is increased by 36.4%. In addition, appropriate DMDA‐SH‐DOPO can effectively improve the bending property of epoxy resin. This study provides a new idea for preparing renewable high‐performance intrinsic flame‐retardant epoxy resin. [ABSTRACT FROM AUTHOR]

Published
2024
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31. Numerical Study on the Design of an Anti-Backflow Injector for Combustion Chambers.

Author

Yang, Jie, Chen, Zhengpeng, Li, Guangyu, Geng, Xue, Yuan, Bo, and Chen, Yong

Subjects
*COMBUSTION chambers, *INJECTORS, *PROPELLANTS, *COMBUSTION efficiency, *COMPUTATIONAL fluid dynamics, *COMBUSTION products
Abstract

The backflow of high-temperature products in an engine's combustion chamber is a key issue which can significantly reduce combustion efficiency. This is particularly problematic for hypergolic propellants, as the high-temperature products may still contain fuel or an oxidizer. If either the fuel or the oxidizer backflows into the manifold of the other, it can easily lead to micro-explosions, thereby creating a threat. To address this problem, this paper proposes a new design of an anti-backflow injector, aimed at effectively preventing the backflow of combustion products to the propellant manifold. A steady-state, non-reactive Computational Fluid Dynamics (CFD) model is employed to evaluate the steady internal flow characteristics of the proposed anti-backflow injector. Additionally, a complementary transient, multiphase fluid dynamics simulation is carried out to assess the response characteristics of the anti-backflow injector. Our analysis focuses on the response characteristics of the concave valve core. The study also explores the impact of different expansion port angles on the injection effect, finding that the vortex diameter at the injector outlet is positively related to the expansion port angle. It is also shown that the injection angle becomes more stable as the expansion angle increases. When the expansion port angles are 10° and 20°, the injection angles show similar trends. In terms of anti-backflow effect, taking the injection stiffness of 150% and a time range of 300 µs as examples, the response time of the anti-backflow models with expansion ports of 10°, 15°, and 20° is increased by 67 µs, 99 µs, and 213 µs, respectively, compared to the base models with the same expansion angles. Meanwhile, when the injection stiffness is 50%, the response time of the anti-backflow models with expansion ports of 10°, 15°, and 20° is increased by 207 µs, 210 µs, and 207 µs, respectively. When the injection stiffness is 20%, the response recovery speed of the anti-backflow models with expansion ports of 10° and 15° is increased by 41 µs and 96 µs, respectively. However, the performance of the anti-backflow model with a 20° expansion port is 216 µs of the base model. The optimized design of the anti-backflow injector has potential applications in solving the propellant backflow problem and contributes to the advancement of combustors. [ABSTRACT FROM AUTHOR]

Published
2024
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36. Nature-Inspired Computational Model for Solving Bi-objective Traveling Salesman Problems

Author

Chen, Xuejiao, Chen, Zhengpeng, Xin, Yingchu, Li, Xianghua, Gao, Chao, Hutchison, David, Series Editor, Kanade, Takeo, Series Editor, Kittler, Josef, Series Editor, Kleinberg, Jon M., Series Editor, Mattern, Friedemann, Series Editor, Mitchell, John C., Series Editor, Naor, Moni, Series Editor, Pandu Rangan, C., Series Editor, Steffen, Bernhard, Series Editor, Terzopoulos, Demetri, Series Editor, Tygar, Doug, Series Editor, Weikum, Gerhard, Series Editor, Geng, Xin, editor, and Kang, Byeong-Ho, editor

Published
2018
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38. An Enhanced Particle Swarm Optimization Based on Physarum Model for Community Detection

Author

Chen, Zhengpeng, Liu, Fanzhen, Gao, Chao, Li, Xianghua, Zhang, Zili, Hutchison, David, Series editor, Kanade, Takeo, Series editor, Kittler, Josef, Series editor, Kleinberg, Jon M., Series editor, Mattern, Friedemann, Series editor, Mitchell, John C., Series editor, Naor, Moni, Series editor, Pandu Rangan, C., Series editor, Steffen, Bernhard, Series editor, Terzopoulos, Demetri, Series editor, Tygar, Doug, Series editor, Weikum, Gerhard, Series editor, Tan, Ying, editor, Takagi, Hideyuki, editor, Shi, Yuhui, editor, and Niu, Ben, editor

Published
2017
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40. Interspecies and intraspecific variability in the trilobites Duyunaspis and Balangia from the Cambrian Series 2 (Stage 4) of Jianhe, South China

Author

Chen, Zhengpeng, Zhao, Yuanlong, Yang, Xinglian, Esteve Serrano, Jorge Vicente, Liu, Xiong, Chen, Shengguang, and Feng, Rong

Subjects
Paleontology, Paleontología, Ecology, Evolution, Behavior and Systematics
Abstract

Though morphological variation among trilobites has been studied for some time, it is difficult to identify differences between interspecific and intraspecific variations. In this study, the intergeneric, interspecific, and intraspecific variations of the Cambrian oryctocephalid trilobites Duyunaspis and Balangia from Jianhe, South China are analysed using geometric morphometrics. In addition to the number of thoracic segments and the relative size of the pygidium compared to the cephalon mentioned in previous studies, the results in this study suggest that the predominant variation of Duyunaspis and Balangia is the presence or absence of the glabellar furrow. The interspecific variations of Duyunaspis (D. duyunensis, D. paiwuensis and D. jianheensis) mainly lie in the types of facial suture, occipital ring and glabella. Although the differences of D. duyunensis or D. jianheensis from adjacent sections have been observed, these variations may be caused by ontogeny, and do not reach the magnitude of interspecific variations in Duyunaspis. This research provides a better quantitative understanding of the variability in oryctocephalid trilobites.

Published
2022

43. Life cycle evolution in the trilobites Balangia and Duyunaspis from the Cambrian Series 2 (Stage 4) of South China

Author

Chen, Zhengpeng, Zhao, Yuanlong, Yang, Xinglian, Esteve Serrano, Jorge Vicente, Liu, Xiong, Chen, Shengguang, Chen, Zhengpeng, Zhao, Yuanlong, Yang, Xinglian, Esteve Serrano, Jorge Vicente, Liu, Xiong, and Chen, Shengguang

Abstract

The evolution process can be reconstructed by tracking the changes in the dynamic characters of life cycles. A number of related trilobites from the Cambrian of South China provide additional information for the study of trilobite evolutionary patterns, which has been hampered by previous incomplete fossil record though. Here, Balangia and Duyunaspis represent related Cambrian oryctocephalid trilobites from South China, are comprehensively discussed over the ontogeny, and the results show that, from B. balangensis via D. duyunensis to D. jianheensis, their exoskeletal morphology shows a directional evolution. Based on the direction of evolutionary changes in the development of Balangia and Duyunaspis, we speculate that Duyunaspis likely evolved from Balangia instead of Balangia evolved from Duyunaspis, as was previously assumed. This inference is also supported by the phylogenetic tree. This research provides not only a better understanding of the mechanisms of evolution in trilobites, but also new insights for the relationship between developmental evolutionary changes and phylogeny in trilobites., National Natural Science Foundation of China, Guizhou Bureau of Science and Technology, Priority Research Program of Chinese Academy of Sciences, Depto. de Geodinámica, Estratigrafía y Paleontología, Fac. de Ciencias Geológicas, TRUE, pub

Published
2023

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