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Li Zhao,Jianhui Zhi,Ningning Yin,Yong Chen,Jin Li,Jiaolong Liu 대한전기학회 2019 Journal of Electrical Engineering & Technology Vol.14 No.2
In this paper, a novel fi nite time parameter estimation method is proposed to solve the parameter estimation problem for a class of linearly parameterized nonlinear systems. The main feature of the proposed method is that the existing method is modifi ed via concurrent learning technique such that the strict persistence of excitation ( PE ) condition on the regression matrix is relaxed to a rank condition on the recorded data. This makes the presented method more practical. Furthermore, the convergence rate is improved signifi cantly by sliding mode technique in fi nite time sense. The simulation results of the existing general nonlinear system illustrate the aforementioned features. Comparison with existing methods from literature proves the eff ectiveness of the proposed method.
Li Xiang,Peng Zhiming,Long Lingli,Lu Xiaofang,Zhu Kai,Tuo Ying,Chen Ningning,Zhao Xiaoyang,Wang Le,Wan Yong 생화학분자생물학회 2020 Experimental and molecular medicine Vol.52 No.-
Traditional therapeutic strategies for spinal cord injury (SCI) are insufficient to repair locomotor function because of the failure of axonal reconnection and neuronal regeneration in the injured central nervous system (CNS). Neural stem cell (NSC) transplantation has been considered a potential strategy and is generally feasible for repairing the neural circuit after SCI; however, the most formidable problem is that the neuronal differentiation rate of NSCs is quite limited. Therefore, it is essential to induce the neuronal differentiation of NSCs and improve the differentiation rate of NSCs in spinal cord repair. Our results demonstrate that both Wnt5a and miRNA200b-3p could promote NSC differentiation into neurons and that Wnt5a upregulated miRNA200b-3p expression through MAPK/JNK signaling to promote NSC differentiation into neurons. Wnt5a could reduce RhoA expression by upregulating miRNA200b-3p expression to inhibit activation of the RhoA/Rock signaling pathway, which has been reported to suppress neuronal differentiation. Overexpression of RhoA abolished the neurogenic capacity of Wnt5a and miRNA200b-3p. In vivo, miRNA200b-3p was critical for Wnt5a-induced NSC differentiation into neurons to promote motor functional and histological recovery after SCI by suppressing RhoA/Rock signaling. These findings provide more insight into SCI and help with the identification of novel treatment strategies.
Mechanical Analysis of Secondary Lining of High-Speed Railway Tunnel
Ningning Zhang,Qian Fang,Yue Li,Dingli Zhang 대한토목학회 2018 KSCE JOURNAL OF CIVIL ENGINEERING Vol.22 No.7
To investigate the mechanical responses of secondary lining of high-speed railway tunnel, two numerical models for simulatingReinforced Concrete Secondary Lining (RCSL) and Plain Concrete Secondary Lining (PCSL) are built respectively based on theprinciple of soil-structure interaction. The simulations are performed under different values of coefficient of lateral pressure (λ). Thenumerical results indicate that the embedded reinforcement enhances the strength of secondary lining. The coefficient of lateralpressure has significant influence on the secondary lining strength.
Li Zhongwen,Bai Ningning,Cheng Zhiping,Wang Yi,Si Jikai 대한전기학회 2024 Journal of Electrical Engineering & Technology Vol.19 No.2
With the increasing use of renewable energy sources connected to inverters in modern power systems, traditional units’ rotary inertia and frequency regulation capacity are becoming inadequate. Therefore, exploring various types of frequency regulation resources is essential. However, these resources come with diferent system models, capacities, and response speeds, posing a signifcant challenge to automatic generation control (AGC). To address this issue and enhance the frequency regulation performance of these resources, a novel distributed coordination AGC method is proposed. The proposed method allows each frequency regulation unit to utilize a separate load frequency control (LFC) controller to participate in frequency regulation based on the area control error information calculated by the dispatching center. To ensure the coordination between the heterogeneous frequency regulation resources, an adaptive chaotic gray wolf algorithm is proposed to tune the parameters of the LFC controller. Furthermore, to release the fast frequency regulation ability of high-speed frequency regulation units and better prepare for the next round of frequency regulation service, an event-triggered power dispatching strategy is proposed. Simulation results of a single-area power system with fve diferent frequency regulation units demonstrate the superior performance of the proposed AGC method.
Yan Li,Ningning Song,Kairong Wang 한국화학공학회 2019 Korean Journal of Chemical Engineering Vol.36 No.5
A novel graphene/biochar composite (BG composite) was synthesized by mixing graphene (Gr) onto feedstock biomass followed by slow pyrolysis. The composite was then tested for its sorption capacity of Cd from aqueous solutions. Structure and morphology analysis showed that graphene was coated on the biochar surface, resulting in a larger surface area, more functional groups, greater thermal stability, and higher removal efficiency of Cd in comparison to unmodified biochar. The sorption capacity of the BG composite for Cd was 1.26-2.36 times that of biochar. A pseudo second-order model adequately simulated sorption kinetics. The sorption isotherms were simulated well by Langmuir models, and calculated maximum Cd adsorption capacities did not change significantly with increasing temperature. Thermodynamic parameters showed that the sorption process of Cd onto the BG composite was feasible and spontaneous. The results of the adsorption experiments, as well as the characteristics of biochar, demonstrate that the process of Cd adsorption on BG composites is mainly physical adsorption accompanied by other chemical adsorption phenomena, such as complexation and ion exchange. This study highlights the use of a BG composite as a multifunctional adsorbent for the efficient, economic, and environmentally friendly treatment of pollutants.
Functional roles and mechanisms of ginsenosides from Panax ginseng in atherosclerosis
Qianqian Xue,Ningning He,Zhibin Wang,Xiuxiu Fu,Lynn Htet Htet Aung,Yan Liu,Min Li,Jae Youl Cho,Yanyan Yang,Tao Yu 고려인삼학회 2021 Journal of Ginseng Research Vol.45 No.1
Atherosclerosis (AS) is a leading cause of cardiovascular diseases (CVDs) and it results in a high rate of death worldwide, with an increased prevalence with age despite advances in lifestyle management and drug therapy. Atherosclerosis is a chronic progressive inflammatory process, and it mainly presents with lipid accumulation, foam cell proliferation, inflammatory response, atherosclerotic plaque formation and rupture, thrombosis, and vascular calcification. Therefore, there is a great need for reliable therapeutic drugs or remedies to cure or alleviate atherosclerosis and reduce the societal burden. Ginsenosides are natural steroid glycosides and triterpene saponins obtained mainly from the plant ginseng. Several recent studies have reported that ginsenosides have a variety of pharmacological activities against several diseases including inflammation, cancer and cardiovascular diseases. This review focuses on describing the different pharmacological functions and underlying mechanisms of various active ginsenosides (Rb1,-Rd, -F, -Rg1, -Rg2, and -Rg3, and compound K) for atherosclerosis, which could provide useful insights for developing novel and effective anti-cardiovascular drugs.
Chen Guoliang,Li Xianlong,Zhu Hongzhang,Wu Huachuan,He Dacheng,Shi Liangyu,Wei Fuxin,Liu Xizhe,Chen Ningning,Liu Shaoyu 생화학분자생물학회 2022 Experimental and molecular medicine Vol.54 No.-
The poor survival and low efficiency of neuronal differentiation limits the therapeutic effects of transplanted neural stem cells in the treatment of spinal cord injury. Neurofibromatosis-1 (NF-1) is a tumor suppressor gene that restricts the rapid and abnormal growth and differentiation of neural cells. In the present study, lentiviral vectors were used to knock out NF-1, Ricotr (the core member of mTORC2) or NF-1+Ricotr in neural stem cells in vitro, and the NF-1, Ricotr or NF-1+Ricotr knockout neural stem cells were transplanted at the lesion site in a rat model of spinal cord injury (SCI). We first demonstrated that targeted knockout of NF-1 had an antiapoptotic effect and improved neuronal differentiation by enhancing the mTORC2/Rictor pathway of neural stem cells in vitro. Subsequently, transplanting NF-1 knockout neural stem cells into the injured site sufficiently promoted the tissue repair and functional recovery of rats with spinal cord injury by enhancing the survival and neuronal differentiation of grafted neural stem cells. Collectively, these findings reveal a prominent role of NF-1 in neural stem cell biology, which is an invaluable step forward in enhancing the benefit of neural stem cell-mediated regenerative cell therapy for spinal cord injury and identifies the transplantation of NF-1 knockout neural stem cells as a promising strategy for spinal cord injury.
Effect of surface roughness on the flotation separation of hematite from fine quartz
Zhanglei Zhu,Zhen Li,Wanzhong Yin,Bin Yang,Ningning Zhang,Jinzhou Qu,Songjiang Chen,Jing Chang,Yuexian Yu,Lijun Liu 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.109 No.-
Although the effect of surface roughness on the floatability of a single mineral has been investigatedextensively, a systematic study for the effect of surface roughness on the flotation separation of differentminerals, e.g., flotation recovery, has never been dwelled. To fulfill this gap, in this study, the effect of surfaceroughness on the flotation separation of hematite from quartz was investigated with a series ofexperiments and detections. Micro-flotation experiments demonstrated that hematite particles withhigher roughness resulted in higher recoveries for both hematite and quartz, but the improvement ofhematite recovery was more significant, which promoted the flotation separation of hematite fromquartz with a higher separation index (SI). Adhesion force measurements revealed that after interactingwith 125 mg/L sodium oleate at pH 9, increasing nano-scaled roughness improved the hydrophobicity ofhematite surface, and reduced the adhesion force of water droplet on hematite surface. Scanning ElectronMicroscope – Energy Dispersive Spectrometer observations confirmed that increasing nano-scaled roughnessincreased the number of fine quartz particles coating on hematite surface. Combined with the analysisof adhesion of water droplet and observation of fine particles coating on hematite surface, the effectof surface roughness on minerals flotation separation could be better understood.
Liu, Yiqi,Chen, Qichao,Li, Ningning,Xie, Bing,Wang, Jianze,Ji, Yanchao The Korean Institute of Power Electronics 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.1
In this study, we first briefly introduce the effect of circulating current control on the modulation signal of a modular multilevel converter (MMC). The maximum modulation index is also theoretically derived. According to the optimal modulation index analysis and the model in the continuous domain, different DC-side output impedance equivalent models of MMC with/without compensating component are derived. The DC-side impedance of MMC inverter station can be regarded as a series xR + yL + zC branch in both cases. The compensating component of the maximum modulation index is also related to the DC equivalent impedance with circulating current control. The frequency characteristic of impedance for MMC, which is observed from its DC side, is analyzed. Finally, this study investigates the prediction of the DC voltage ripple transfer between two-terminal MMC high-voltage direct current systems under unbalanced conditions. The rationality and accuracy of the impedance model are verified through MATLAB/Simulink simulations and experimental results.