An investigation on the dynamics of domain switching of Bi0.5Na0.5TiO3-based ferroelectric ceramics

Zhipeng Gao,Hang Zhang,Yi Liu,Lingfeng Wu,Jia Yang,Tao Zhang,Haiyan Wang,Xuefeng Chen,Genshui Wang,Hongliang He 한국물리학회 2017 Current Applied Physics Vol.17 No.4

The dynamics of domain switching of Bi0.5Na0.5TiO3-based ferroelectric ceramic was investigated. With the electric field increasing, the domain switch experienced three sections of no domain switch region, creep region and flow region. In the creep region, the domain switch is dominated by the thermally activated domain wall movement. In flow region, the domain wall experience the viscous flow motion. For the BNT-BA-Zn ceramic, the activation energy of creep domain switch is much higher than it in flow region. With temperature increasing, the sensitivity of domain wall motion to the frequency is decreasing. This result demonstrated the domain switch of different ferroelectric materials could be quantitatively analyzed and compared based on the simple polarization - current - electric field data.

Live Media Streaming in VANETs using Traffic Flow

Shuoping Wang,Zhipeng Wang,Jun Liu,Honghao Gao,Meng Kuai 보안공학연구지원센터 2015 International Journal of Multimedia and Ubiquitous Vol.10 No.1

Multimedia streaming is a trend in VANETs infotainment service with establishment of infrastructure and communication standards. This paper considers the scenario of live multimedia streaming multicast to vehicles. We propose the relay selection scheme to deliver media streaming with stable link to improve QoS (quality of service). Through evaluation, our proposed scheme is able to have video delivered with a satisfying delay and acceptable loss ratio.

Evolution and recovery of original total organic carbon for muddy source rocks with different total organic carbon in the Western Sichuan Depression, Sichuan Basin, China

Zhipeng Huo,Yan Gao,Yi Zhao,Tianyu Zheng,Jinchuan Zhang,Jianghui Ding 한국지질과학협의회 2019 Geosciences Journal Vol.23 No.1

According to the new quantitative model for original total organic carbon (TOCo) evolution and recovery of source rocks, The TOCo evolution of muddy source rocks with different TOCs (MSRDTOC) (0.5% < TOC ≤ 1.5%, 2.5% < TOC ≤ 3.5% and 4.0% < TOC ≤ 6.0%, and their average values were 1.0%, 3.0% and 5.0%, respectively) and type III kerogen were investigated in the Western Sichuan Depression (WSD) of Sichuan Basin, China, finally recovery coefficients of TOCo were calculated. Studies showed that TOCo evolution of the MSRDTOC have similarities and differences. The similarities reveal that with the increase of thermal evolution level, varied TOC all reduce gradually and the sharp reduction occurs at the stage of a large number of hydrocarbon generation and expulsion (0.7% ≤ vitrinite reflectance (VR) ≤ 1.3%). The differences indicate that the starting time and decrease range for varied TOC are different. For TOCo = 1.0%, 3.0% and 5.0%, their starting time of TOC reduction are VR = 1.05%, 0.80% and 0.60%, respectively. When VR reaches to 3.0%, their TOC decrease ranges are 30.54%, 38.52% and 44.00% and their recovery coefficients are 1.44, 1.63 and 1.79, respectively. The higher the TOC is, the earlier the starting time of TOC reduction is, the bigger the range of TOC reduction and recovery coefficient are. It must restore TOCo when we evaluate source rocks at high-over mature stage and predict oil and gas resources. The MSRDTOC and their TOCo recovery should be evaluated, respectively.

Quantitative analysis of carbon emissions in precision turning processes and industrial case study

Zhipeng Jiang,Dong Gao,Yong Lu,Linghao Kong,Zhendong Shang 한국정밀공학회 2021 International Journal of Precision Engineering and Vol.8 No.1

With growing concerns regarding the global environment, the industrial sector has played a significant role; that is, it is responsible for consuming large amount of energy and resources, while simultaneously producing wastes and carbon dioxide. A quantitative calculation of carbon emission in the turning process is presented in this paper. A generic carbon emission system boundary based on exergy balance is proposed first to avoid blurred system boundaries or the omission of elements. Then, a carbon emission model (iERWC) is formed by converting energy consumption (E), resource depletion (R) and waste generation (W) to equivalent carbon emissions (C) based on information flow (i), which effectively solves the problem of quantifying the impact of the machining process on the environment. Finally, the model is verified by experiments, and a simulation analysis is carried out. Additionally, the influence rule of processing parameters on carbon emissions is analyzed, and the cutting parameter that produces the lowest carbon emission is given.

Methanol dehydrogenation to methyl formate catalyzed by SiO2-, hydroxyapatite-, and MgO-supported copper catalysts and reaction kinetics

Zhipeng Lu,Hengbo Yin,Dezhi Gao,Aili Wang,Shuxin Liu 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.31 No.-

Catalytic dehydrogenation of methanol to methyl formate over SiO2-, hydroxyapatite (HAP)-, and MgOsupportedcopper catalysts was investigated. Metallic copper (Cu0) was the active site for the methanoldehydrogenation to methyl formate. Cu/SiO2 catalyst with low basicity and weak-strength basic siteeffectively catalyzed the methanol dehydrogenation to methyl formate. Cu/HAP and Cu/MgO catalystswith high basicities and strong-strength basic sites caused the degradation of the resultant methylformate to CO and H2. Over Cu(5)/SiO2 catalyst, the reaction activation energies for methanoldehydrogenation to methyl formate and methyl formate degradation to CO and H2 were 58.3 and91.1 kJ mol 1, respectively.

Non-circular gear transmission mechanism with variable-involute and variable-cycloid composite tooth profile

Jiangang Liu,Zhipeng Tong,Gao-Hong Yu,Xiong Zhao,Haili Zhou 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.5

Non-circular gears with small curvature radius pitch curve are often used in the mechanical transmission of special motion path, but this kind of non-circular gear produces serious undercutting. Therefore, this research presented a kind of variable-involute and variable-cycloid composite tooth profile (VIVC-CTF). A transmission ratio curve of non-circular gear was designed by using Fourier function. The tooth profile equation of VIVC-CTF and its conjugate tooth profile equation were constructed on the basis of the normal and envelope methods. The influence of slip coefficient and ellipse eccentricity on the VIVC-CTF was investigated, and the variation of slip coefficient and eccentricity on the meshing line length, theoretical contact ratio, and pressure angle at pitch curve was analyzed. The meshing experiment of the VIVCCTF non-circular gear transmission mechanism was carried out on the basis of high-speed camera technology. The theoretical results of the transmission ratio were consistent with the experimental results.

Microstructural Effect on Cold Strengthening Mechanism of MP159 Alloys

Luorong Dengzhu,Leiming Fang,Bin Gan,Zhengwei Xiong,Qian Liu,Yi Liu,Jia Yang,Jun Li,Zhipeng Gao 대한금속·재료학회 2024 METALS AND MATERIALS International Vol.30 No.2

Previous investigations on MP159 alloys have largely reported the striking reinforcement performance after cold deformation,which the deformation mechanism was attributed to HCP phases and deformed twins and so on. To data, the microstructuraleffect on cold strengthening mechanism of MP159 alloy was still controversial. In this work, the processes of microstructuralevolution were elaborated through multi-scale structural characterizations. In the initial MP159, the recrystallized grainsand Σ3 twins (<111> 60°) play a dominant role in the microstructures. After cold drawing, the microcosmic dislocationswere significantly increased in the deformed grains. The mesoscopic Σ3 twins were seriously deformed to become thedeformed twins, inducing that the grains were refined. Meanwhile, the grain boundaries were broken and the HAGBs weresubsequently transformed to the LAGBs. The microstructural transition of dislocations → LAGBs ← HAGBs was confirmed. The high stacking fault energy in the deformed twins promoted a high strain energy stored in the MP159, forming the macroscopical<111> //RD texture. The series of microstructural changes induced the significant enhancement of the strengthand hardness. The microstructural effect on cold strengthening mechanism of MP159 alloys was clarified, which would bea great significance to strengthening metallic materials in the current investigations.