A cosmic ray muons tomography system with triangular bar plastic scintillator detectors and improved 3d image reconstruction algorithm: A simulation study

Zhao Yanwei,Luo Xujia,Qin Kemian,Liu Guorui,Chen Daiyuan,Augusto R.S.,Zhang Weixiong,Luo Xiaogang,Liu Chunxian,Liu Juntao,Liu Zhiyi 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.2

Purpose: Muons are characterized by a strong penetrating ability and can travel through thousands of meters of rock, making them ideal to image large volumes and substances typically impenetrable to, for example, electrons and photons. The feasibility of 3D image reconstruction and material identification based on a cosmic ray muons tomography (MT) system with triangular bar plastic scintillator detectors has been verified in this paper. Our prototype shows potential application value and the authors wish to apply this prototype system to 3D imaging. In addition, an MT experiment with the same detector system is also in progress. Methods: A simulation based on GEANT4 was developed to study cosmic ray muons' physical processes and motion trails. The yield and transportation of optical photons scintillated in each triangular bar of the detector system were reproduced. An image reconstruction algorithm and correction method based on muon scattering, which differs from the conventional PoCA algorithm, has been developed based on simulation data and verified by experimental data. Results: According to the simulation result, the detector system’s position resolution is below 1 ~ mm in simulation and 2 mm in the experiment. A relatively legible 3D image of lead bricks in size of 20 cm 5 cm 10 cm used our inversion algorithm can be presented below 1 104 effective events, which takes 16 h of acquisition time experimentally. Conclusion: The proposed method is a potential candidate to monitor the cosmic ray MT accurately. Monte Carlo simulations have been performed to discuss the application of the detector and the simulation results have indicated that the detector can be used in cosmic ray MT. The cosmic ray MT experiment is currently underway. Furthermore, the proposal also has the potential to scan the earth, buildings, and other structures of interest including for instance computerized imaging in an archaeological framework.

Orthosteric and allosteric action of the C5a receptor antagonists

Liu, Heng,Kim, Hee Ryung,Deepak, R. N. V. Krishna,Wang, Lei,Chung, Ka Young,Fan, Hao,Wei, Zhiyi,Zhang, Cheng Nature Publishing Group 2018 Nature Structural and Molecular Biology Vol. No.

An improved Big Bang-Big Crunch algorithm for structural damage detection

Zhiyi Yin,Jike Liu,Wei-Li Luo,Zhongrong Lu 국제구조공학회 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.68 No.6

The Big Bang-Big Crunch (BB-BC) algorithm is an effective global optimization technique of swarm intelligence with drawbacks of being easily trapped in local optimal results and of converging slowly. To overcome these shortages, an improved BB-BC algorithm (IBB-BC) is proposed in this paper with taking some measures, such as altering the reduced form of exploding radius and generating multiple mass centers. The accuracy and efficiency of IBB-BC is examined by different types of benchmark test functions. The IBB-BC is utilized for damage detection of a simply supported beam and the European Space Agency structure with an objective function established by structural frequency and modal data. Two damage scenarios are considered: damage only existed in stiffness and damage existed in both stiffness and mass. IBB-BC is also validated by an existing experimental study. Results demonstrated that IBB-BC is not trapped into local optimal results and is able to detect structural damages precisely even under measurement noise.

An experiment investigation on the effect of Coulomb friction on the displacement transmissibility of a quasi-zero stiffness isolator

Xingtian Liu,Qiang Zhao,ZhiYi Zhang,Xubin Zhou 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.1

The effect of the Coulomb friction on a quasi-zero stiffness (QZS) isolator which configured by combining an Euler buckled beam negative stiffness corrector and a linear isolator is presented in this paper. Assuming friction damping provided by linear roller guider, the dynamic responses of the vibration isolation system and the equivalent linear one are obtained by using harmonic balance method (HBM). The static and dynamic characteristics of the QZS isolator are both investigated. For the linear isolator, the resonance frequency will increase and the peak transmissibility will decrease with the increasing of Coulomb friction or the decreasing of the excitation amplitude. However, in the case of QZS isolator, the natural frequency is decreased with the help of the negative stiffness mechanism and the amplification factor at the resonance is not obvious with the presence of the friction damping. Theory and experiment show good accordance. Therefore, it is recommend that one should add light Coulomb friction damping into the system to get better performance when using the QZS isolator in practice. The results present here can be a useful guideline when design such kind of vibration isolator.

Transition of Crack Propagation from a Transgranular to an Intergranular Path in an Overaged Al-Zn-Mg-Cu Alloy During Cyclic Loading

Xu Chen,Zhiyi Liu,Peng Xia,Ailin Ning,Sumin Zeng 대한금속·재료학회 2013 METALS AND MATERIALS International Vol.19 No.2

The fatigue crack propagation behavior in the overaged Al-Zn-Mg-Cu alloy was characterized by optical microscopy, scanning electron microscopy, transmission electron microscopy and electron backscatter diffraction. The results revealed that a fatigue crack tended to transgranularly propagate in the near-threshold regime, whereas intergranular crack propagation was dominant at the high ΔK regime. The transition of crack propagation from a transgranular to an intergranular path that occurred in the Paris regime was strongly influenced by the misorientation of adjacent grains and precipitate free zones. In addition, a crystallographic model of crack propagation was proposed to interpret the transition. The fatigue short crack propagation on a single slip plane was responsible for the formation of a transgranular propagation path in the near-threshold regime. The fatigue long crack propagation, which was conducted by a duplex slip mechanism in the Paris regime, led to the formation of fatigue striations. The formation of a zigzag crack in the near-threshold regime was ascribed to the high misorientation of adjacent grains.

Texture Evolution of Hot Rolled Al–Cu–Mg–Zr Alloy During Annealing

Qi Zhao,Zhiyi Liu 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.12

Texture growth and relative mechanism of Al–Cu–Mg–(Zr) alloy during annealing have been investigated by three dimensionalOrientation Distribution Functions (ODFs), Electron Back Scattered Diffraction (EBSD) and Transmission ElectronMicroscopy (TEM). The results show that Zr addition in Al–Cu–Mg alloy restricts the preferable growth of recrystallizedGoss grain, and fails to improve the total intensity of Goss texture. Recrystallized Goss is difficult to nucleate within Brassorientation even after full recrystallization, and Copper and S grains cannot preferably transform into Cube grains in Al–Cu–Mg–Zr alloy. Instead, the growth of random textures is favorable at the expense of deformed Brass, Copper and S textures. These phenomena can be well explained by relating to the disappearance of Σ5, Σ7 and Σ9 boundaries caused by Al3Zrpinningdislocation. In addition, it is found that the Brass texture of Al–Cu–Mg–Zr alloy can be enhanced at specific annealingtemperature, which is attributed to the formation of recrystallized Brass grains. Lastly, the deformed Goss of Al–Cu–Mg–Zralloy is energy-unstable as compared with Brass during annealing, and these deformed Goss grains will subsequently evolveinto recrystallized Brass or random orientations.

Effects of Temperature Distribution on Microstructure and Mechanical Properties of Hot Extruded Al–Zn–Mg–Cu Alloy Pipe with Variable Cross-Section

Lei Luo,Zhiyi Liu,Song Bai,Jing Cao,Fei Liu,Linnan Ou,Juangang Zhao 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.9

The microstructures and mechanical properties of a hot extruded Al–Zn–Mg–Cu alloy pipe with variable cross-section areinvestigated by transmission electron microscopy, electron backscattering diffraction, hardness testing and finite elementmethod. The results suggest that the variable temperature distribution at different positions along the extrusion directionafter hot extrusion attribute to the changes in hot deformation degrees. The extruded profile at billet temperature of 410 °Cand a ram speed of 1.5 mm/s shows a gradual increase in temperature from 416 to 467 °C at strains from 3.7 to 8.6 alongthe extrusion direction. The dynamic recovery (DRV) and partial dynamic recrystallization (DRX) are observed in the hotextruded profile, and high-angle grain boundaries fraction exponentially rises along the extrusion direction. The hardnessat different positions of the hot extruded profile shows a nearly exponential decline along the extrusion direction, mainlyascribes to the decrease of the dislocation density that caused by the dynamic softening.

Effects of Aging Temperature on the Precipitation Behavior of Ω Phase in an Al-Cu-Mg-Ag Alloy

Yao Li,Zhiyi Liu,Qingkun Xia,Song Bai,Xu Chen 대한금속·재료학회 2011 METALS AND MATERIALS International Vol.17 No.1

Microstructures and mechanical properties of an Al-Cu-Mg-Ag alloy aged for 1 h at temperatures in a range 25 °C to 450 °C were characterized in the present work by means of hardness tests, electrical conductivity measurements, and transmission electron microscopy (TEM). In-situ X-ray diffraction (XRD) was also employed to examine the precipitation behavior of Ω phase in a temperature range of 25 °C to 400 °C The in-situ Xray diffraction peak at 2θ = 26°-28° detected at elevated aging temperatures between 165 °C and 400 °C was attributed to the formation of Ω phase. TEM observations demonstrated the existence of Ω phase in the alloy when aged for 1 h at temperatures in a range 145 °C to 450 °C.

Ginsenosides as dietary supplements with immunomodulatory effects: a review

Tang Ping,Liu Sitong,Zhang Junshun,Ai Zhiyi,Hu Yue,Cui Linlin,Zou Hongyang,Li Xia,Wang Yu,Nan Bo,Wang Yuhua 한국응용생명화학회 2024 Applied Biological Chemistry (Appl Biol Chem) Vol.67 No.-

Immune disorders have become one of the public health problems and imposes a serious economic and social burden worldwide. Ginsenosides, the main active constituents of ginseng, are regarded as a novel supplementary strategy for preventing and improving immune disorders and related diseases. This review summarized the recent research progress of ginsenosides in immunomodulation and proposed future directions to promote the development and application of ginsenosides. After critically reviewing the immunomodulatory potential of ginsenosides both in vitro and in vivo and even in clinical data of humans, we provided a perspective that ginsenosides regulated the immune system through activation of immune cells, cytokines, and signaling pathways such as MAPK, PI3K/ Akt, STAT, and AMPK, as well as positively affected immune organs, gut flora structure, and systemic inflammatory responses. However, the evidence for the safety and efficacy of ginsenosides is insufficient, and the immune pathways of ginsenosides remain incompletely characterized. We believe that this review will provide a valuable reference for further research on ginsenosides as dietary supplements with immunomodulatory effects.

Effects of Aging Temperature on the Mechanical Properties and Precipitation Behavior of a Pre-strained Al–Cu–Mg–Ag Alloy

Jian Wang,Jingpei Xie,Zhiyi Liu,Aiqin Wang,Wenyan Wang 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.2

In this work, effects of artificial aging temperature on the mechanical properties and precipitation behavior of a pre-strainedAl–Cu–Mg–Ag alloy were investigated by hardness and tensile tests, and quantitative transmission electron microscopeanalysis. Three aging conditions, a single aging at a high temperature (T8H), a single aging at a low temperature (T8L) andan interrupted aging at low temperature following under-aging at a higher temperature (T8I4), were compared. Based on thequantitative analysis of the strengthening phases, the evolution law of the average diameter, thickness and volume fractionof Ω plates with the aging time for a pre-stretched Al–Cu–Mg–Ag alloy aged at 190 °C/160 °C may be predicted by themodified equations. The precipitation behavior of Ω precipitates was confirmed by considering the coarsening kinetics ofthem. Results show that a higher aging temperature can increase the precipitation kinetics of Ω phase and inhibit the precipitationof θ′ phase. Thus, a new type of interrupted aging treatment, T8I4 (3.2% pre-stretch + 190 °C/1 h + 160 °C/10 h),was proposed to enhance the strength of the pre-stretched Al–Cu–Mg–Ag alloy.