Molecular Dynamics Simulation of supercritical spray at micro & nano scale

( Zhang Yunxiao ),( Fu Qingfei ),( Mo Chaojie ),( Yang Lijun ) 한국액체미립화학회 2017 한국액체미립화학회 학술강연회 논문집 Vol.2017 No.-

The supercritical jets have many applications in many fields ranging from aerospace propulsion to chemical engineering. However, there is still lack of relevant theoretical research on the characteristics of supercritical fluids, and also lack of deep understanding of the destabilization mechanism of supercritical jets. Molecular dynamics method, which has been quite mature, can simulate extreme harsh physical conditions and exceptionally complex geometric model. The simulation process spontaneously contains all the physical effects. Therefore, the purpose of this paper is to study the characteristics and destabilization mechanism of supercritical jets from the microcosmic perspective using molecular dynamics method. Firstly, the molecular dynamics simulation of EOS (Equation of State) of liquid nitrogen was carried out. The influence of different simulation parameters on the simulation results was analyzed and then compared with the theoretical results. Four conditions were selected to study the influences of different time step, total simulation steps and truncation distance on the simulation results. The results show that the truncation distance has a great influence on the simulation precision, the time step and the total simulation steps have no significant impact on the EOS of liquid nitrogen. The results are in good agreement with the SRK (Soave-Redlich-Kwong) equation, which show the correctness of the simulation of supercritical fluids using molecular dynamics method. Secondly, the molecular dynamics simulation of supercritical nitrogen jet was carried out at different conditions. The supercritical jets ejected into a supercritical environment and a subcritical environment, respectively. Through the analysis of the results, the distribution of jet velocity, density, temperature and other jet characteristics was obtained. The interface was determined where concentration of supercritical fluid component reached 50% because the supercritical jet has no obvious vapor-liquid interface. Stable analysis of the results was performed and the disturbance growth rate of the supercritical shear layer at different conditions was obtained. Finally, the growth rate achieved by processing the results of molecular simulation was compared to the results by the linear stability analysis.

Security of the Country

Zhang Yunxiao 한국콘텐츠학회 2019 ICCC International Digital Design Invitation Exhib Vol.2019 No.5

Diagnostic value of Contrast-Enhanced Ultrasound Parametric Imaging in Breast Tumors

Zhang Yuan,Jiang Quan,Zhang Yunxiao,Chen Jian,He Zhu,Gong Liping 한국유방암학회 2013 Journal of breast cancer Vol.16 No.2

Purpose: This study aimed to evaluate the diagnostic value of SonoLiver software for parametric imaging in breast tumors. Methods: Contrast-enhanced ultrasound (CEUS) was performed in 216 breast lesions (113 malignant, 103 benign). The CEUS parameters were compared between benign and malignant lesions. The rise time, the time to peak, the mean transit time and dynamic vessel pattern (DVP) were analyzed using SonoLiver software. Results: Quantitative analysis showed that the rise time was 16.52±4.15 seconds in the benign group vs. 13.86±3.36 seconds in the malignant group (p=0.007), and the time to peak was 19.86±4.87 seconds in the benign group vs. 16.52±4.85 seconds in the malignant group (p=0.009). The mean transit time was 80.55±18.65 seconds in the benign group vs. 65.16±20.28 seconds in the malignant group (p=0.006). The difference between the distribution of DVP in benign and malignant tumors was statistically significant. One hundred one malignant tumors (89.4%) performed an irregular red/yellow fill in the region of interest (ROI) and 85 benign tumors (82.5%) performed a single blue/green fill in the ROI. The sensitivity, specificity, and accuracy of parametric imaging in breast tumors were 84.1%, 85.4%, 84.7%, respectively. Conclusion: The CEUS parametric imaging can distinguish differences between malignant and benign breast tumors as well as provide diagnostic information on breast lesions.

Electrochemical enhanced heterogeneous activation of peroxymonosulfate by CoFe2O4 nanoparticles to degrade moxifloxacin

Meng Zhang,Lili Liu,Jianan Li,Rui Zhan,Zhiping Wang,Haosheng Mi,Yunxiao Zhang 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.127 No.-

The catalytic mechanism of CoFe2O4 nanoparticles (NPs) was investigated in the system of electrochemicalenhanced heterogeneous activation of peroxymonosulfate (EC/CoFe2O4/PMS) with moxifloxacin(MOX) as target contaminant. The removal efficiencies of MOX in PMS, CoFe2O4, EC, CoFe2O4/PMS, andEC/CoFe2O4/PMS system were 18.3%, 36.1%, 43.7%, 96.9%, and 98.3%, respectively. Although there wasno synergy effect between EC and heterogeneous catalytic oxidation reaction (HCOR) on MOX removal,the value of apparent rate constant (karc) was much higher in EC/CoFe2O4/PMS system (0.24 min1) comparedwith CoFe2O4/PMS system (0.13 min1). Therefore, EC not only kept the structure of CoFe2O4 NPsstable, but also significantly accelerated the reaction rate of HCOR. Meanwhile, according to electrochemicalimpedance spectra of catalysts synthesized based on ion-substitution strategy and the EC-HCORexperimental results, the decisive role of „Co in PMS activation and the electron transfer between„Co and „Fe were confirmed. The TOC removal efficiency was reached 74.4% as the ratio of PMS toCoFe2O4 NPs being 0.8 mM to 50 mg/L (30 min), and further improved to 87.6% with batch addition(0.25 mM per 30 min) of PMS (120 min, CoFe2O4 = 100 mg/L). The research results could improve theunderstanding of catalytic mechanism of spinel oxide in electrochemical system.

Analysis and Design of Railway Communication Control System Based AADL

Yunxiao Li,Lichen Zhang,Minglv Chen 보안공학연구지원센터 2013 International Journal of Control and Automation Vol.6 No.3

An Anti-wind Modeling Method of Quadrotor Aircraft and Cascade Controller Design Based on Improved Extended State Observer

Houyin Xi,Dong Zhang,Tao Zhou,Yunxiao Yang,Qiang Wei 제어·로봇·시스템학회 2021 International Journal of Control, Automation, and Vol.19 No.3

Wind disturbance may significantly reduce the flight control performance of quadrotors when flying. In order to meet high performance flight control requirements, this paper presents a quadrotor anti-wind model (QAWM) and a flight control scheme for quadrotors. The QAWM takes the influence of aerodynamic effects on the propeller, gyroscopic effect and wind disturbance into account. The model can represent more flight states including not only hovering but also flight in windy conditions even maneuver flight. A cascade control schemewith an improved extended state observer (IESO) is adopted to decompose the quadrotor flight control problem into position control loop and attitude control loop. In the attitude control loop, the IESO is used to estimate the unmodeled dynamics, parameter uncertainties and external disturbances, as well as compensate the angular velocity control. In addition, the stability of IESO and the closed loop system are proved. Simulation and experimental results show the effectiveness of the nonlinear quadrotor model and control scheme, and the control scheme can effectively improve the flight performance of quadrotors under wind disturbance even maneuver flight.

Identification and Functional Characterization of R3 MYB Transcription Factor Genes in Soybean

Shucai Wang,Jinsong Pang,Hongwei Xun,Zhibing Zhang,Yunxiao Zhou,Xueyan Qian,Yingshan Dong,Xianzhong Feng,Bao Liu 한국식물학회 2018 Journal of Plant Biology Vol.61 No.2

In Arabidopsis, trichome formation is regulatedby a MYB-bHLH-WD40 (MBW) transcriptional activatorcomplex, which can activate the expression of GLABRA2(GL2) and R3 MYB genes. GL2 is required for trichomeformation, whereas R3 MYBs inhibit trichome formation byblocking the formation of the MBW complex, thus inhibitingthe expression of GL2. By using the amino acid sequence of theArabidopsis R3 MYB transcription factor TRICHOMELESS1(TCL1) to BLAST the soybean (Glycine max) protein database,we found that there are a total of six R3 MYB genes insoybean, namely Glycine max TRICHOMELESS1 through 6(GmTCL1-GmTCL6). By generating transgenic plants, wefound that trichome formation in soybean plants overexpressingeach of the GmTCLs remained largely unchanged, and theexpression of putative GL1 and GL2 genes in the transgenicplants was unaffected. However, all the GmTCLs interactedwith GLABRA3 (GL3) in transfected Arabidopsis protoplasts,expression each of the GmTCLs in Arabidopsis inhibitedtrichome formation, and the expression levels of GL1 andGL2 were greatly reduced in the Arabidopsis transgenicplants. Moreover, phenotypic complementary analysis showedthat GmTCL1 is functionally equivalent to TCL1. Takentogether, these results suggest that GmTCLs are functionalR3 MYBs, however, they do not regulate trichome formationin soybean.