Microstructure of Gear Steels Treated by Shot Peening by X-Ray Line Profile Analysis Method

Pengfei Zhu,Hongzhi Yan,Jibo Zhou,Youliang Zhou,Yin Zhang,Zhi Chen 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.10

Shot peening is a common surface strengthening process of gears. It can induce compressive residual stress, refine grain size and increase dislocation density. However, there are limited reports on the quantitative analysis of dislocation substructures (type, fraction and arrangement), crystallite size and micro-strain in different crystal planes. To further reveal the microstructure strengthening mechanism of gears during shot peening, X-ray diffraction line profile analysis (XRDLPA) method is applied to study the effect of coverage on the microstructure of the gear steels. The results show that with increasing coverage, the dislocation density is increased from 2.62 × 1016 to 3.37 × 1016 m−2 in the form of screw-edge-mixed type as determined from the dislocation characteristic parameter q. The fraction of edge dislocation increases, whereas the fraction of screw dislocation decreases. The dislocation arrangement parameter M is decreased from 7.1 to 5.6, indicating that the formation of dislocation dipoles or dislocation cells in the surface layer can be further enhanced by increasing coverage. Due to the different degrees of atomic slip, the (200) crystallographic plane exhibits the smallest crystallite size and highest micro-strain, whereas the (222) plane shows the smallest micro-strain and the largest crystallite size. In addition, during shot peening, the enhancement of surface hardness of the gear steels is attributed to the phase transformation strengthening, grain-boundary hardening and dislocation hardening. The surface compressive stress of the gear steels induced by shot peening is affected not only by phase transformation, but also by Bauschinger effect, surface topography, grain refinement and so on.

Reliability Evaluation and Prediction of Deep Buried Tunnel Based on Similarity Theory and Model Test

Pengfei Wu,Zhichun Fang,Xue Wang,Guangyi Zhu 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.6

Deep buried tunnel has a complex stress environment and large stress level. At present, it is difficult to dynamic monitoring for such tunnels. In order to make the safety evaluation and prediction of tunnel closer to the engineering practice, this paper deduces the tunnel reliability evaluation algorithm. The time-varying reliability of deep tunnel excavation process is analyzed and predicted. Based on the similarity theory, the actual deep tunnel excavation is simulated by indoor model test, the stress and deformation are monitored. The results show that after the tunnel excavation, the reliability of the structure does not decrease gradually, but increases slowly first and then decreases sharply. With the increase of the buried depth of the tunnel, the structural reliability decreases gradually. When the buried depth reaches a certain depth, the structural reliability will decrease rapidly. The influence of different parameters on the structural reliability has different sensitivity. The sensitivity of friction angle is the highest, and the sensitivity of gravity is the lowest. The sensitivity has little effect with the change of tunnel excavation time and tunnel buried depth. The accuracy of this method is verified by the comparative analysis of model box tests.

Experimental and numerical investigation of non-reaction flow characteristics in a concentric staged dual-swirl combustor

Le Li,Pengfei Zhu,Qiandong Li,Jianqin Suo,Longxi Zheng 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.4

In order to deeply understand the complex swirling flow characteristics of the typical staged and zoned combustor, particle image velocimetry measurement and large eddy simulation were used to study the steady and instantaneous flow field. The results show that an obviously central recirculation zone (CTRZ) cannot be formed by the single pilot stage swirler. When a main stage swirler with strong swirling flow is added, a large CTRZ appears in the concentric staged dual-swirl combustor. The CTRZ size in the co-rotating combustor is obviously larger than that in the counter-rotating combustor. The development process of the CTRZ is divided into three stages: P, P-M and M. The stages P and M are mainly dominated by the pilot stage and main stage swirling air, respectively. In addition, it can be seen from the instantaneous flow field that there is a single spiral precessing vortex core in the co-rotating and counter-rotating combustor.

Investigation of Soil Texture around Livestock Burial site - Chung-buk North Area in Korea -

Hyukjoon Lee,Pengfei Zhu,Changsoo Kim,Jisun Jung,Jungsik Cho,Byungyeol Cho,Ikjun Yeon 한국폐기물자원순환학회 2015 한국폐기물자원순환학회 학술대회 Vol.2015 No.05

These days, animal infectious disease such as AI(Avian Influenza) and FMD(Foot-and-Mouth Disease) breaks out, and increase the number of its occurrence. Offered in "An animal disease prevention" of Ministry of Agriculture and Forestry that to do killed caused livestock order to prevent diffuse pollution of the epidemic when an animal disease has happened. Accordingly, in Ministry of Agriculture and Forestry set up the "Emergency Action Guide", it suggests the emergency cation, disposal method(stamping out, incineration, burying method), disposal method of livestock excretions in the area of origin. Also, the department of the environment makes the livestock burial regional environmental research guidelines, it order to investigate the surround environment, water quality in monitoring well, environment management and so on. In korea, this was the first time confirmed that the foot-and-mouth disease occurred in 1934. The leachate buried underground of livestock is organic waste water and it has been arranged nutrient salts such as nitrogen, phosphorus. So, there is a possibility that can lead to a variety of environmental problems when it can result in river pollution, ground water pollution and soil pollution. Look at domestic and foreign research trend leachate behavior such as contamination analysis through physicochemical properties or physicochemical analysis of the leachate components have been identified and carried out. Because of the leak of the leachate, there is a possibility about the around soil pollution. Thus, we studied that investigation of soil texture around livestock burial site in chung-buk north area of korea. From the result, surface soil was loam and subsoil was clay loam soil in 35% of survey site. In the future, this result will be a important basis data for correlation of leachate leak and consequential soil texture.

Integrate Advantage of Geographic Routing and Reactive Mechanism for Aeronautical Ad Hoc Networks

Xiaoheng Tan,Xiaonan Hu,Pengfei Qu,Zhengnan Zhu,Yan Zhang 보안공학연구지원센터 2015 International Journal of Hybrid Information Techno Vol.8 No.7

Large scale range and high dynamic topology are the two major features of Aeronautical Ad Hoc Networks (AANETs), which present severe challenges to provide efficient and reliable data packet delivery in aviation communication networks. Geographic routing has been studied as an attractive option for routing in aeronautical networks due to its simplicity and scalability. However there are still some problems such as low packet delivery ratio and less reliability for long dynamic links. In this paper, we improve the greedy forwarding strategy and start with the idea of integrating reactive routing mechanism with geographic routing protocol, referred to as IRG (Improved Reactive and Geographic) routing protocol. Variety simulations have been performed to evaluate the performance of the proposed routing protocol, and the results show that it can increase the packet delivery ratio efficiently.

Effect of ages and season temperatures on bi-surface shear behavior of HESUHPC-NSC composite

Yang Zhang,Yanping Zhu,Pengfei Ma,Shuilong He,Xudong Shao Techno-Press 2023 Advances in concrete construction Vol.15 No.6

Ultra-high-performance concrete (UHPC) has become an attractive cast-in-place repairing material for existing engineering structures. The present study aims to investigate age-dependent high-early-strength UHPC (HESUHPC) material properties (i.e., compressive strength, elastic modulus, flexural strength, and tensile strength) as well as interfacial shear properties of HESUHPC-normal strength concrete (NSC) composites cured at different season temperatures (i.e., summer, autumn, and winter). The typical temperatures were kept for at least seven days in different seasons from weather forecasting to guarantee an approximately consistent curing and testing condition (i.e., temperature and relative humidity) for specimens at different ages. The HESUHPC material properties are tested through standardized testing methods, and the interfacial bond performance is tested through a bi-surface shear testing method. The test results quantify the positive development of HESUHPC material properties at the early age, and the increasing amplitude decreases from summer to winter. Three-day mechanical properties in winter (with the lowest curing temperature) still gain more than 60% of the 28-day mechanical properties, and the impact of season temperatures becomes small at the later age. The HESUHPC shrinkage mainly occurs at the early age, and the final shrinkage value is not significant. The HESUHPC-NSC interface exhibits sound shear performance, the interface in most specimens does not fail, and most interfacial shear strengths are higher than the NSC-NSC composite. The HESUHPC-NSC composites at the shear failure do not exhibit a large relative slip and present a significant brittleness at the failure. The typical failures are characterized by thin-layer NSC debonding near the interface, and NSC pure shear failure. Two load-slip development patterns, and two types of main crack location are identified for the HESUHPC-NSC composites tested in different ages and seasons. In addition, shear capacity of the HESUHPC-NSC composite develops rapidly at the early age, and the increasing amplitude decreases as the season temperature decreases. This study will promote the HESUHPC application in practical engineering as a cast-in-place repairing material subjected to different natural environments.

Investigation of Soil Texture around Livestock Burial site - Chung-buk North Area in Korea -

( Hyukjoon Lee ),( Changsoo Kim ),( Pengfei Zhu ),( Jisun Jung ),( Jungsik Cho ),( Byungyeol Cho ),( Ikjun Yeon ) 한국폐기물자원순환학회(구 한국폐기물학회) 2015 한국폐기물자원순환학회 춘계학술발표논문집 Vol.2015 No.-

These days, animal infectious disease such as AI(Avian Influenza) and FMD(Foot-and-Mouth Disease) breaks out, and increase the number of its occurrence. Offered in An animal disease prevention of Ministry of Agriculture and Forestry that to do killed caused livestock order to prevent diffuse pollution of the epidemic when an animal disease has happened. Accordingly, in Ministry of Agriculture and Forestry set up the Emergency Action Guide, it suggests the emergency cation, disposal method(stamping out, incineration, burying method), disposal method of livestock excretions in the area of origin. Also, the department of the environment makes the livestock burial regional environmental research guidelines, it order to investigate the surround environment, water quality in monitoring well, environment management and so on. In korea, this was the first time confirmed that the foot-and-mouth disease occurred in 1934. The leachate buried underground of livestock is organic waste water and it has been arranged nutrient salts such as nitrogen, phosphorus. So, there is a possibility that can lead to a variety of environmental problems when it can result in river pollution, ground water pollution and soil pollution. Look at domestic and foreign research trend leachate behavior such as contamination analysis through physicochemical properties or physicochemical analysis of the leachate components have been identified and carried out. Because of the leak of the leachate, there is a possibility about the around soil pollution. Thus, we studied that investigation of soil texture around livestock burial site in chung-buk north area of korea. From the result, surface soil was loam and subsoil was clay loam soil in 35% of survey site. In the future, this result will be a important basis data for correlation of leachate leak and consequential soil texture.

A Study on Transnational Media Coverage of Sino-US Trade through Semantic Network Analysis

Mei Juan Guo,황미경,PengFei Zhu,주이모 한국멀티미디어학회 2023 The journal of multimedia information system Vol.10 No.2

This study was conducted to analyze the perspectives of transnational media reporting on Sino-US trade. News reports from Associated Press and Xinhua News Agency were collected from March 20, 2018, to October 31, 2018. Text mining and frequency analysis was performed by Python to examine significant keywords from the news reports. Eigenvector centralities and Modularity analysis were conducted by Gephi. QAP correlation analyses were conducted by Ucinet. As a result, Associated Press and Xinhua News Agency had different clusters. There was a significant correlation between the Xinhua News Agency Semantic Network and the Associated Press Semantic Network. This study supports the two perspectives of reporting from different aspects. Xinhua News Agency involved four sub-topics when reporting Sino-US trade frictions, namely China-related clusters, US-related clusters, trade-related clusters, and tariff-related clusters. The Associated Press involved three sub-topics, namely China-US Trade-related clusters, global economy-related clusters, and tariff-related clusters. Xinhua News Agency focused on China-related clusters, while Associated Press focused on Sino-US trade-related clusters. The network structure of Xinhua News Agency and AP shows a positive correlation, which to some extent indicates the global perspectives of Chinese and American media reporting. The division of the two network clusters and the difference in the choice and prominence of the words in the network indicates that the Chinese and American media are still affected by the political stance and culture when constructing the framework strategy. Based on these results, valuable implications are provided for media reporting across countries.

Collisional dynamics in laser-induced plasmas: evidence for electron-impact excitation

Zhang, Liying,Wei, Pengfei,Qin, Meiyan,Yuan, Xiaolong,Liu, Candong,Geng, Tao,Zhu, Haiyong,Duan, Yanmin,Zhuang, Songlin,Lu, Peixiang,Kim, Dong Eon The Optical Society 2018 Optics express Vol.26 No.8

Evaluation of 관-Amyloid Peptides Fibrillation Induced by Nanomaterials Based on Molecular Dynamics and Surface Plasmon Resonance.

Hou, Yafei,Li, Pengfei,Zhou, Hongjian,Zhu, Xiaoli,Chen, Haifeng,Lee, Jaebeom,Koh, Kwangnak,Shen, Zhongming,Chen, Hongxia American Scientific Publishers 2015 Journal of Nanoscience and Nanotechnology Vol.15 No.2

<P>This report investigated the effect of carbon nanomaterials, single-wall carbon nanotube (SWCNT) and graphene oxide, on fibrillation of 관-amyloid 40 (A관40) based on surface plasmon resonance (SPR) and molecular dynamics (MD). MD simulations are carried out in order to reveal the molecular mechanisms of the interaction between nanomaterials and A관40. The strong interaction between A관40 and nanomaterials is related to Van der Waals forces and the Coulomb force, inducing delicate manipulation of the main bonding energy for fibrillation of A관40. The interaction energy between the A관 peptide and graphene is higher than that of SWCNT. Experimental results show both carbon nanomaterials enhance the appearance of a critical nucleus for nucleation of peptide fibrils. Graphene is more beneficial to assist the nucleation process than SWCNT. Combination of SPR and molecular dynamics could be a high-throughput method to screen protein fibrillation.</P>