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Rongzhen Zheng,김철 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.8
Solid-state electrolyte batteries are excellent candidates for the development of safe and high-performance lithium batteries. However, the low ionic conductivity and poor interfacial contact of current solid-state electrolytes severely hinder the commercialization of solidstate batteries. Moreover, a higher stress is caused by the use of solid-state electrolytes compared with that in the case of liquid electrolytes. To increase the physical contact area between the solid/solid interfaces of all-solid-state batteries (ASSBs), this study constructed two types of interfaces with sine-curved and trapezoidal shapes to replace the general planar interface and used the Nelder-Mead algorithm to optimize the curved interface and geometric parameters of the battery cells. ASSBs are composed of a sulfide-based LI6PS5Cl solid electrolyte, a lowdensity lithium metal anode, and a high-theoretical-capacity LCO cathode. The optimization results show that the curved interface can achieve a higher energy density than a flat-interface battery. The stress caused by lithium deposition during battery charging was also calculated. The low modulus of the soft solid electrolyte significantly reduced the stress inside the battery.
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An Enhanced Topology Optimization Approach Based on the Combined MMC and NURBS-Curve Boundaries
Rongzhen Zheng,Cheol Kim 한국정밀공학회 2020 International Journal of Precision Engineering and Vol.21 No.8
An efficient topology optimization method is developed newly in this study by combining the Non-uniform rational B-spline (NURBS) curves and moving morphable components (MMC). The MMC-based topology optimization is an explicit and geometrical method that utilizes a set of morphable components to create basic blocks for optimization. Optimum topologies may be obtained by optimizing shapes, lengths, thicknesses, orientations and layout of these components. The combined method adopts a different way in the creation of morphable components that consist of NURBS curves. Various kinds of complicated curved components can be built with NURBS curves or surfaces. Here, the NURBS curve is applied for shaping the geometries of structural basic components, and the coordinates of control points become design variables for topology optimization. A MATLAB optimization code has been developed. Four numerical examples of a short cantilever, a MBB beam, a simply supported beam with two point loadings, and a vehicle lower chassis structure subjected to crash loadings are provided to prove that the combined topology optimization approach coupled with NURBS curves and basic morphable components can get optimum topologies with clear topological boundaries successfully. As results of comparison study with other approaches, we can obtain the same topologies and faster convergence rates for the three separate cases. The combined approach can improve the smoothness of the topological boundaries that are similar to the shape optimization results obtained by post-optimization after the density-based topology optimization.
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Bifurcations of a predator-prey system with weak Allee effects
Rongzhen Lin,Shengqiang Liu,Xiaohong Lai 대한수학회 2013 대한수학회지 Vol.50 No.4
We formulate and study a predator-prey model with non-monotonic functional response type and weak Allee effects on the prey,which extends the system studied by Ruan and Xiao in [Global analysisin a predator-prey system with nonmonotonic functional response, SIAMJ. Appl. Math. 61 (2001), no. 4, 1445–1472] but containing an extraterm describing weak Allee effects on the prey. We obtain the global dy-namics of the model by combining the global qualitative and bifurcationanalysis. Our bifurcation analysis of the model indicates that it exhibitsnumerous kinds of bifurcation phenomena, including the saddle-node bi-furcation, the supercritical and the subcritical Hopf bifurcations, and thehomoclinic bifurcation, as the values of parameters vary. In the genericcase, the model has the bifurcation of cusp type of codimension 2 (i.e.,Bogdanov-Takens bifurcation).
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Rongzhen Jiang,Yincheng Teng,Yajuan Huang,Jinghong Gu,Li Ma,Minglin Shi,Yuedi Zhou 생화학분자생물학회 2014 Experimental and molecular medicine Vol.46 No.-
In women with preeclampsia (PE), endothelial cell (EC) dysfunction can lead to altered secretion of paracrine factors that induce peripheral vasoconstriction and proteinuria. This study examined the hypothesis that PE sera may directly or indirectly, through human umbilical vein ECs (HUVECs), stimulate phospholipase C-γ1-1,4,5-trisphosphate (PLC-γ1-IP3) signaling, thereby increasing protein kinase C-α (PKC-α) activity, collagen I expression and intracellular Ca2+ concentrations ([Ca2+]i) in human umbilical artery smooth muscle cells (HUASMCs). HUASMCs and HUVECs were cocultured with normal or PE sera before PLC-γ1 silencing. Increased PLC-γ1 and IP3 receptor (IP3R) phosphorylation was observed in cocultured HUASMCs stimulatedwith PE sera (Po0.05). In addition, PE serum significantly increased HUASMC viability and reduced their apoptosis (Po0.05); these effects were abrogated with PLC-γ1 silencing. Compared with normal sera, PE sera increased [Ca2+]i in cocultured HUASMCs (Po0.05), which was inhibited by PLC-γ1 and IP3R silencing. Finally, PE sera-induced PKC-α activity and collagen I expression was inhibited by PLC-γ1 small interfering RNA (siRNA) (Po0.05). These results suggest that vasoactive substances in the PE serum may induce deposition in the extracellular matrix through the activation of PLC-γ1, which may in turn result in thickening and hardening of the placental vascular wall, placental blood supply shortage, fetal hypoxia–ischemia and intrauterine growth retardation or intrauterine fetal death. PE sera increased [Ca2+]i and induced PKC-α activation and collagen I expression in cocultured HUASMCs via the PLC-γ1 pathway.
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Zhong, Rongzhen,Xiao, Wenjun,Ren, Guopu,Zhou, Daowei,Tan, Chuanyan,Tan, Zhiliang,Han, Xuefeng,Tang, Shaoxun,Zhou, Chuanshe,Wang, Min Asian Australasian Association of Animal Productio 2011 Animal Bioscience Vol.24 No.12
The beneficial effects of tea catechins (TCs) are related not only to their antioxidant potential but also to the improvement of animal meat quality. In this study, we assessed the effects of dietary TC supplementation on plasma biochemical parameters, hormone responses, and glutathione redox status in goats. Forty Liuyang goats were randomly divided into four equal groups (10 animals/group) that were assigned to four experimental diets with TC supplementation at 4 levels (0, 2,000, 3,000 or 4,000 mg TC/kg DM feed). After a 60-day feeding trial, all goats were slaughtered and sampled. Dietary TC treatment had no significant effect on blood biochemical parameters, however, low-density lipoprotein cholesterol (p<0.001), triglyceride (p<0.01), plasma urea nitrogen (p<0.01), and glucose (p<0.001) decreased and total protein (p<0.01) and albumin (p<0.05) increased with the feeding time extension, and day 20 was the turning point for most of changes. Interactions were found in glutathione (p<0.001) and the ratio of reduced and oxidized glutathione (p<0.05) in whole blood between treatment and feeding time. Oxidized glutathione in blood was reduced (p<0.05) by 2,000 mg TC/kg feed supplementation, and a similar result was observed in longissimus dorsi muscle. Though plasma glutathione peroxidase (p<0.01) and glutathione reductase (p<0.05) activities were affected by treatment and feeding time interactions, and glutathione S-transferases activity increased with feeding day extension, no changed values appeared in longissimus dorsi muscle. In conclusion, dietary TC supplementation affected the concentrations of some blood metabolites and accelerated GSH depletion in the blood of goats. In terms of less high-density lipoprotein cholesterol, the highest insulin and IGF-I concentrations, the highest ratio of reduced and oxidized glutathione in plasma, the dosage of 2,000 mg TC/kg feed might be desirable for growing goats to prevent glutathione depletion and keep normal physiological metabolism.
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BIFURCATIONS OF A PREDATOR-PREY SYSTEM WITH WEAK ALLEE EFFECTS
Lin, Rongzhen,Liu, Shengqiang,Lai, Xiaohong Korean Mathematical Society 2013 대한수학회지 Vol.50 No.4
We formulate and study a predator-prey model with non-monotonic functional response type and weak Allee effects on the prey, which extends the system studied by Ruan and Xiao in [Global analysis in a predator-prey system with nonmonotonic functional response, SIAM J. Appl. Math. 61 (2001), no. 4, 1445-1472] but containing an extra term describing weak Allee effects on the prey. We obtain the global dynamics of the model by combining the global qualitative and bifurcation analysis. Our bifurcation analysis of the model indicates that it exhibits numerous kinds of bifurcation phenomena, including the saddle-node bifurcation, the supercritical and the subcritical Hopf bifurcations, and the homoclinic bifurcation, as the values of parameters vary. In the generic case, the model has the bifurcation of cusp type of codimension 2 (i.e., Bogdanov-Takens bifurcation).
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Linfeng Deng,Rongzhen Zhao 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.4
Feature extraction is the most important step for machine fault diagnosis, but useful features are very difficult to extract from the vibrationsignals, especially for intelligent fault diagnosis based on data-driven technique. An integral method for fault feature extraction basedon local mean decomposition (LMD) and Teager energy kurtosis (TEK) is proposed in this paper. The raw vibration signals are firstprocessed via LMD to produce a group of product functions (PFs). Then, the Teager energies are computed using the derived PFs. Subsequently,each Teager energy data set is directly used to calculate the corresponding TEK. A vibration experiment was performed on arotor-bearing rig with rub-impact fault to validate the proposed method. The experimental results show that the proposed method canextract different TEKs from the mechanical vibration signals under two different operating conditions. These TEKs can be employed toidentify the normal and rub-impact fault conditions and construct a numerical-valued machine fault decision table, which proves that thismethod is suitable for fault feature extraction of the rotor-bearing system.
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Peng YaFeng,Su XinYu,Hu LiWei,Wang Qian,Ouyang RongZhen,Sun AiMin,Guo Chen,Yao XiaoFen,Zhang Yong,Wang LiJia,Zhong YuMin 대한영상의학회 2021 Korean Journal of Radiology Vol.22 No.9
Objective: To investigate the feasibility of cine three-dimensional (3D) balanced steady-state free precession (b-SSFP) imaging combined with a non-local means (NLM) algorithm for image denoising in evaluating cardiac function in children with repaired tetralogy of Fallot (rTOF). Materials and Methods: Thirty-five patients with rTOF (mean age, 12 years; range, 7–18 years) were enrolled to undergo cardiac cine image acquisition, including two-dimensional (2D) b-SSFP, 3D b-SSFP, and 3D b-SSFP combined with NLM. End-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV), and ejection fraction (EF) of the two ventricles were measured and indexed by body surface index. Acquisition time and image quality were recorded and compared among the three imaging sequences. Results: 3D b-SSFP with denoising vs. 2D b-SSFP had high correlation coefficients for EDV, ESV, SV, and EF of the left (0.959– 0.991; p < 0.001) as well as right (0.755–0.965; p < 0.001) ventricular metrics. The image acquisition time ± standard deviation (SD) was 25.1 ± 2.4 seconds for 3D b-SSFP compared with 277.6 ± 0.7 seconds for 2D b-SSFP, indicating a significantly shorter time with the 3D than the 2D sequence (p < 0.001). Image quality score was better with 3D b-SSFP combined with denoising than with 3D b-SSFP (mean ± SD, 3.8 ± 0.6 vs. 3.5 ± 0.6; p = 0.005). Signal-to-noise ratios for blood and myocardium as well as contrast between blood and myocardium were higher for 3D b-SSFP combined with denoising than for 3D b-SSFP (p < 0.05 for all but septal myocardium). Conclusion: The 3D b-SSFP sequence can significantly reduce acquisition time compared to the 2D b-SSFP sequence for cine imaging in the evaluation of ventricular function in children with rTOF, and its quality can be further improved by combining it with an NLM denoising method.
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