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Defects evolution and element segregation of Ni-Mo-Cr alloy irradiated by 30 keV Ar ions
Liu Min,Liu Wenguan,He Xiujie,Gao Yantao,Liu Renduo,Zhou Xingtai 한국원자력학회 2020 Nuclear Engineering and Technology Vol.52 No.8
In present study, TEM foils of Ni-Mo-Cr alloy were directly irradiated with 30 keV Ar ions to allow direct characterization. The defects evolution and element segregation after irradiation were investigated by TEM and HAADF-EDS linear scanning. At low irradiation doses (1.38 and 2.76 dpa), black dots were formed and grew with increasing dose. Complicated defects including peas-shaped dislocation loops, polygon dislocation networks and large loops were visible in samples irradiated to high doses (13.8 and 27.6 dpa). Meanwhile, dislocation channels appeared, in which defects were swept out. Significant Mo depletions at dislocation lines and grain boundaries were induced by irradiation due to large misfits between Mo-Ni atoms and high content of Mo.
Failure behaviors of C/C composite tube under lateral compression loading
Yantao Gao,Yuexia Guan,Ke Li,Min Liu,Can Zhang,Jinliang Song 한국원자력학회 2019 Nuclear Engineering and Technology Vol.51 No.7
Mechanical responses and failure behaviors of advanced C/C composite tube are very important for structural component design in nuclear reactor. In this study, an experimental investigation was conducted to study mechanical properties of C/C composite tube. Quasi-static compression loading was applied to a type of advanced composite tube to determine the response of the quasi-static load displacement curve during progressive damage. Acoustic emissions (AE) signals were captured and analyzed to characterize the crack formation and crack development. In addition, the crack propagation of the specimens was monitored by imaging technique and failure mode of the specimen was analyzed. FEM is appled to simulate the stress distribution. Results show that advanced C/C composite tube exhibits considerable energy absorption capability and stability in load-carrying capacity.
Aerosol Synthesis of Cargo-FilledGraphene Nanosacks
Chen, Yantao,Guo, Fei,Jachak, Ashish,Kim, Sang-Pil,Datta, Dibakar,Liu, Jingyu,Kulaots, Indrek,Vaslet, Charles,Jang, Hee Dong,Huang, Jiaxing,Kane, Agnes,Shenoy, Vivek B.,Hurt, Robert H. American ChemicalSociety 2012 Nano letters Vol.12 No.4
<P>Water microdroplets containing graphene oxide and a secondsoluteare shown to spontaneously segregate into sack-cargo nanostructuresupon drying. Analytical modeling and molecular dynamics suggest thesacks form when slow-diffusing graphene oxide preferentially accumulatesand adsorbs at the receding air–water interface, followed bycapillary collapse. Cargo-filled graphene nanosacks can be nanomanufacturedby a simple, continuous, scalable process and are promising for manyapplications where nanoscale materials should be isolated from theenvironment or biological tissue.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/nalefd/2012/nalefd.2012.12.issue-4/nl2045952/production/images/medium/nl-2011-045952_0004.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nl2045952'>ACS Electronic Supporting Info</A></P>
Zhenze Liu,Qing Yuan,Guangming Nie,Yantao Tian 한국자동차공학회 2021 International journal of automotive technology Vol.22 No.2
In order to be acceptable to drivers, the adaptive cruise control (ACC) systems need to be designed based on the analysis of human driver driving behavior. A new safe distance model is proposed in this paper based on the analysis of real-world driving test data. The goal of the control algorithm is to achieve naturalistic behavior of the vehicle that can comprehensively address the issue of driving safety, tracking performance, fuel economy and ride comfort. Firstly, a hierarchical control architecture is utilized which lower controller compensates for nonlinear vehicle dynamics and enables tracking of the desired acceleration. Then the acceleration rate of the following vehicle is introduced as state variables in the model of the car-following system for a more realistic and comprehensive description of dynamic evolution between the preceding car and the following car. Next, the control objectives above are formulated into a constrained quadratic programming problem under the framework of model predictive control (MPC). Finally, the simulation results show that the control strategy proposed in this paper can provide natural following performance that not only can satisfy driving safety, tracking performance but also can achieve fuel economy and ride comfort.
Efficient End-to-End Failure Probing Matrix Construction in Data Center Networks
Jia, Zequn,Liu, Qiang,He, Ying,Wu, Qianqian,Liu, Ren Ping,Sun, Yantao 한국통신학회 2023 Journal of communications and networks Vol.25 No.4
Data centers play an essential role in the functioningof modern society. However, failures are unavoidable in datacenter networks (DCN) and will lead to negative impact on allapplications. Therefore, researchers are interested in the rapiddetection and localization of failures in DCNs. In this paper, we present a theoretical model to analyze theend-to-end failure detection methods in data center networks. Our numerical results verify that the proposed theoretical modelis accurate. In addition, we propose an algorithm to constructprobing matrices based on an enhanced probing path selectionindicator. We also introduce deep reinforcement learning (DRL)method to solve the problem and propose a DRL-based probingmatrix construction algorithm. Our experimental results showthat both of the proposed algorithms for constructing probingmatrices achieve better performance in detection accuracy thanexisting methods. We discussed different scenarios that thealgorithms are applicable to that can improve detection accuracyor construction speed performance.
Yufeng Lian,Xiaoyu Wang,Yantao Tian,Keping Liu 한국자동차공학회 2018 International journal of automotive technology Vol.19 No.2
This paper presents a new control scheme for lateral collision avoidance (CA) systems to improve the safety of four-in-wheel-motor-driven electric vehicles (FIWMD-EVs). There are two major contributions in the design of lateral CA systems. The first contribution is a new lane-changing model based on vehicle edge turning trajectory (VETT) to make vehicle adapt to different driving roads and conform to drivers’ characteristic, in addition to ensure vehicle steering safety. The second contribution is vehicle semi-uncertainty dynamic model (SUDM), which is SISO model. The problem of stability performance without the information on sideslip angle is solved by the proposed SUDM. Based on the proposed VETT and SUDM, the lateral CA system can be designed with robust controller to restrain the effect of uncertainties resulting from parameter perturbation and lateral wind disturbance. Single and mixed driving cycles simulation experiments are carried out with CarSim to demonstrate the effectiveness in control scheme, simplicity in structure for lateral CA system based on the proposed VETT and SUDM.
ADAPTIVE SLIDING MODE CONTROL OF LATERAL STABILITY OF FOUR WHEEL HUB ELECTRIC VEHICLES
Shou-Tao Li,Hui Liu,Di Zhao,Qiu-Yuan Li,Yantao Tian,De-Jun Wang,Ding-Li Yu 한국자동차공학회 2020 International journal of automotive technology Vol.21 No.3
Some physical parameters of a hub motor-driven four-wheel electric vehicle will change when the vehicle turns or maneuvers and the parameter change is caused by the change of the driving conditions. An adaptive sliding mode control is proposed in this paper to maintain the vehicle’s stability by compensating for the change of these parameters. The control parameter being adapted is the converging rate of the system state towards the sliding mode. As the Lyapunov method is used, so both the vehicle stability and adaptive rate convergence are guaranteed. Moreover, the hierarchical control structure is adopted for this vehicle stability control system. The above adaptive sliding model control forms the upper-layer; while the lower-layer control is to distribute the upper torque to the four wheels in an optimal way, subject to several constraints. In addition, the best feasible reference of the yaw rate and the vehicle side slip angle are obtained and used in the control system. The developed method is simulated under the CarSim/MATLAB co-simulation environment to evaluate the system performance. The simulation results are compared with the non-adaptive existing sliding mode control, and show that the proposed method is superior under different conditions.
A novel scheme to acquire enhanced up-conversion emissions of Ho3+ and Yb3+ co-doped Sc2O3
Chaoyi Zhang,Qian Jiang,Xinyu Wang,Jing Liu,Yantao Xiao,Chun Li,Hai Lin,Fanming Zeng,Zhongmin Su 한국물리학회 2020 Current Applied Physics Vol.20 No.1
A detailed investigation about the effect of Sc2O3: 1 mol%Ho3+/5 mol%Yb3+ co-doped with Ce4+ ions prepared by sol-gel methods was performed systematically. Under the excitation of 980 nm laser diode, both green emission (553 nm, 5F4/5S2→5I8) and red emission (672 nm, 5F5→5I8) were both observed in the emission spectra of the samples, which were found to be two-photon process and sensitized by Yb3+ ions. With the increasing of Ce4+ ions, the up-conversion green emission intensity are increased by 6.52, 8.69, 10.85, 13.92 and 16.66 fold, corresponding to the Ce4+ ions concentrations from 5 mol% to 13 mol%, respectively. The number of photons are necessary to populate the upper emitting state decreases to 2 and the infrared absorption coefficient is reduced, when the Ce4+ ions concentration increase to 13 mol%. Ce4+ ions play an important role in tailoring the local crystal field around Ho3+ ions, lowering the highest phonon cut-off energy of matrix and reducing the infrared absorption coefficient, thus hindering the non-radiative processes, which contribute to the increased emission intensity. The excellent enhancement makes it a promising multifunctional optical luminescence material.