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Tokamak plasma disruption precursor onset time study based on semi-supervised anomaly detection
X.K. Ai,W. Zheng,M. Zhang,D.L. Chen,C.S. Shen,B.H. Guo,B.J. Xiao,Y. Zhong,N.C. Wang,Z.J. Yang,Z.P. Chen,Z.Y. Chen,Y.H. Ding,Y. Pan Korean Nuclear Society 2024 Nuclear Engineering and Technology Vol.56 No.4
Plasma disruption in tokamak experiments is a challenging issue that causes damage to the device. Reliable prediction methods are needed, but the lack of full understanding of plasma disruption limits the effectiveness of physics-driven methods. Data-driven methods based on supervised learning are commonly used, and they rely on labelled training data. However, manual labelling of disruption precursors is a time-consuming and challenging task, as some precursors are difficult to accurately identify. The mainstream labelling methods assume that the precursor onset occurs at a fixed time before disruption, which leads to mislabeled samples and suboptimal prediction performance. In this paper, we present disruption prediction methods based on anomaly detection to address these issues, demonstrating good prediction performance on J-TEXT and EAST. By evaluating precursor onset times using different anomaly detection algorithms, it is found that labelling methods can be improved since the onset times of different shots are not necessarily the same. The study optimizes precursor labelling using the onset times inferred by the anomaly detection predictor and test the optimized labels on supervised learning disruption predictors. The results on J-TEXT and EAST show that the models trained on the optimized labels outperform those trained on fixed onset time labels.
Concomitant nitrates enhance clopidogrel response during dual anti-platelet therapy
Lee, D.H.,Kim, M.H.,Guo, L.Z.,De Jin, C.,Cho, Y.R.,Park, K.,Park, J.S.,Park, T.H.,Serebruany, V. Elsevier/North-Holland Biomedical Press 2016 INTERNATIONAL JOURNAL OF CARDIOLOGY Vol.203 No.-
<P>Background: Despite advances in modern anti-platelet strategies, clopidogrel still remains the cornerstone of dual anti-platelet therapy (DAPT) in patients undergoing percutaneous coronary interventions (PCI). There is some inconclusive evidence that response after clopidogrel may be impacted by concomitant medications, potentially affecting clinical outcomes. Sustained released nitrates (SRN) are commonly used together with clopidogrel in post-PCI setting for mild vasodilatation and nitric oxide-induced platelet inhibition. Methods: We prospectively enrolled 458 patients (64.5 +/- 9.6 years old, and 73.4% males) following PCI undergoing DAPT with clopidogrel and aspirin. Platelet reactivity was assessed by the VerifyNow (TM) P(2)Y12 assay at the maintenance outpatient setting. Results: Concomitant SRN (n = 266) significantly (p = 0.008) enhanced platelet inhibition after DAPT (251.6 +/- 80.9 PRU) when compared (232.1 +/- 73.5 PRU) to the SRN-free (n = 192) patients. Multivariate logistic regression analysis with the cut-off value of 253 PRU for defining heightened platelet reactivity confirmed independent correlation of more potent platelet inhibition during DAPT and use of SRN (Relative risk = 1.675; Odds ratio [1.059-2.648]; p = 0.027). In contrast, statins, calcium-channel blockers, beta blockers, angiotensin receptor blockers, ACE-inhibitors, diuretics, and anti-diabetic agents did not significantly impact platelet inhibition following DAPT. Conclusion: The synergic ability of SRN to enhance response during DAPT may have important clinical implications with regard to better cardiovascular protection, but extra bleeding risks, requiring further confirmation in a large randomized study. (C) 2015 Elsevier Ireland Ltd. All rights reserved.</P>
Guo, X.,Hu, B.,Wei, C.,Sun, J.,Jung, Y.G.,Li, L.,Knapp, J.,Zhang, J. Pergamon Press ; Elsevier Science Ltd 2016 INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER - Vol.100 No.-
Lanthanum zirconate (La<SUB>2</SUB>Zr<SUB>2</SUB>O<SUB>7</SUB>) is a promising candidate material for thermal barrier coating (TBC) applications due to its low thermal conductivity and high-temperature phase stability. In this work, a novel image-based multi-scale simulation framework combining molecular dynamics (MD) and finite element (FE) calculations is proposed to study the thermal conductivity of La<SUB>2</SUB>Zr<SUB>2</SUB>O<SUB>7</SUB> coatings. Since there is no experimental data of single crystal La<SUB>2</SUB>Zr<SUB>2</SUB>O<SUB>7</SUB> thermal conductivity, a reverse non-equilibrium molecular dynamics (reverse NEMD) approach is first employed to compute the temperature-dependent thermal conductivity of single crystal La<SUB>2</SUB>Zr<SUB>2</SUB>O<SUB>7</SUB>. The single crystal data is then passed to a FE model which takes into account of realistic thermal barrier coating microstructures. The predicted thermal conductivities from the FE model are in good agreement with experimental validations using both flash laser technique and pulsed thermal imaging-multilayer analysis. The framework proposed in this work provides a powerful tool for future design of advanced coating systems.
First principles study of nanoscale mechanism of oxygen adsorption on lanthanum zirconate surfaces
Guo, X.,Wu, L.,Zhang, Y.,Jung, Y.G.,Li, L.,Knapp, J.,Zhang, J. North-Holland 2016 Physica E, Low-dimensional systems & nanostructure Vol.83 No.-
<P>Lanthanum zirconate (La2Zr2O7) is a rare-earth pyrochlore material, which has been proposed as a promising thermal barrier coating (TBC) material due to its low thermal conductivity and high temperature phase stability. At elevated temperatures, degradation of La2Zr2O7 may occur due to adsorption of oxygen (02) on La2Zr2O7 surfaces. This paper investigates nanoscale mechanism of O-2 adsorption on La2Zr2O7 coating surfaces using the density functional theory (DFT) calculations. La2Zr2O7 surface energies on (001), (011) and (111) planes are calculated. The surface free energy of (011) plane is lower than those of (001) and (111) planes. On (001), (011) and (111) planes of La2Zr2O7, the lowest adsorption energy occurs at 4-fold site, bridge site, and 3-fold-FCC site, respectively. Among all calculated cases, the lowest adsorption energy site is 3-fold-FCC on (111) plane, which is confirmed by the Bader charge transfer analyses. Charge density difference analyses show that the 3-fold-FCC site on (111) surface has the largest charge density, suggesting the strongest interaction between O-2 and La2Zr2O7 surface. (C) 2016 Elsevier B.V. All rights reserved.</P>
Guo, J.,Hu, X.,Liu, J.,Feng, T.,Yoon, E.Y.,Kim, H.S. PAS 2015 ARCHIVES OF METALLURGY Vol.60 No.2
<B>Abstract</B><P>Amorphous alloys or metallic glasses have attracted significant interest in the materials science and engineering communities due to their unique physical, mechanical, and chemical properties. The viscous flow of amorphous alloys exhibiting high strain rate sensitivity and homogeneous deformation is considered to be an important characteristic in thermoplastic forming processes performed within the supercooled liquid region because it allows superplastic-like deformation behavior. Here, the correlation between the superheated liquid fragility, and the onset temperature of crystallization for Al-based alloys, is investigated. The activation energy for viscous flow of the liquid is also investigated. There is a negative correlation between the parameter of superheated liquid fragility and the onset temperature of crystallization in the same Al-based alloy system. The activation energy decreases as the onset temperature of crystallization increases. This indicates that the stability of a superheated liquid can affect the thermal stability of the amorphous alloy. It also means that a liquid with a large superheated liquid fragility, when rapidly solidified, forms an amorphous alloy with a low thermal stability.</P>
Guo, Y.Q.,Zou, Y.,Cao, Z.J.,Xu, X.F.,Yang, Z.S.,Li, Shengli Asian Australasian Association of Animal Productio 2013 Animal Bioscience Vol.26 No.7
Eight multiparous Holstein cows ($569{\pm}47$ kg of BW; $84{\pm}17$ DIM) were used to evaluate the effects of different levels of coarsely ground wheat (CGW) as replacements for ground corn (GC) in diets on feed intake and digestion, ruminal fermentation, lactation performance, and plasma metabolites profiles in dairy cows. The cows were settled in a replicated $4{\times}4$ Latin square design with 3-wk treatment periods; four cows in one of the replicates were fitted with rumen cannulas. The four diets contained 0, 9.6, 19.2, and 28.8% CGW and 27.9, 19.2, 9.6, and 0% GC on dry matter (DM) basis, respectively. Increasing dietary levels of CGW, daily DM intake tended to increase quadratically (p = 0.07); however, apparent digestibility of neutral detergent fiber (NDF) and acid detergent fiber (ADF) were significantly decreased (p<0.01) in cows fed the 28.8% CGW diets. Ruminal pH remained in the normal physiological range for all dietary treatments at all times, except for the 28.8% CGW diets at 6 h after feeding; moreover, increasing dietary levels of CGW, the daily mean ruminal pH decreased linearly (p = 0.01). Increasing the dietary levels of CGW resulted in a linear increase in ruminal propionate (p<0.01) and ammonia nitrogen ($NH_3$-N) (p = 0.06) concentration, while ruminal acetate: propionate decreased linearly (p = 0.03) in cows fed the 28.8% CGW diets. Milk production was not affected by diets; however, percentage and yield of milk fat decreased linearly (p = 0.02) when the level of CGW was increased. With increasing levels of dietary CGW, concentrations of plasma beta-hydroxybutyric acid (BHBA) (p = 0.07) and cholesterol (p<0.01) decreased linearly, whereas plasma glucose (p = 0.08), insulin (p = 0.02) and urea nitrogen (p = 0.02) increased linearly at 6 h after the morning feeding. Our results indicate that CGW is a suitable substitute for GC in the diets of dairy cows and that it may be included up to a level of 19.2% of DM without adverse effects on feed intake and digestion, ruminal fermentation, lactation performance, and plasma metabolites if the cows are fed fiber-sufficient diets.