Research of the Mechanism of Low Frequency Oscillation Based on Dynamic Damping Effect

Liu, Wenying,Ge, Rundong,Zhu, Dandan,Wang, Weizhou,Zheng, Wei,Liu, Fuchao The Korean Institute of Electrical Engineers 2015 Journal of Electrical Engineering & Technology Vol.10 No.4

For now, there are some low frequency oscillations in the power system which feature low frequency oscillation with positive damping and cannot be explained by traditional low frequency oscillation mechanisms. Concerning this issue, the dynamic damping effect is put forward on the basis of the power-angle curve and the study of damping torque in this article. That is, in the process of oscillation, damping will dynamically change and will be less than that of the stable operating point especially when the angle of the stable operating point and the oscillation amplitude are large. In a situation with weak damping, the damping may turn negative when the oscillation amplitude increases to a certain extent, which may result in an amplitude-increasing oscillation. Finally, the simulation of the two-machine two-area system verifies the arguments in this paper which may provide new ideas for the analysis and control of some unclear low frequency phenomena.

Mechanical and Microscopic Properties of Copper-contaminated Soil Solidified with Calcium Carbide Residue, Metakaolin, and Desulfurization Gypsum under Freeze-thaw Cycles

Qiang Wang,Dandan Ge,Guojun Cai,Man Li,Liuyan Wu,Huangrui Xu 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.2

The solidification/stabilization effect of heavy metal contaminated soils in frozen soil regions may be weakened. A novel binder comprising calcium carbide residue, metakaolin, and desulfurization gypsum was used to solidify and stabilize copper-contaminated soil subjected to freeze-thaw (F-T) cycles. The unconfined compressive strength (UCS), F-T cycles, scanning electron microscope (SEM), X-ray diffraction (XRD), and pH tests were conducted to investigate the characteristics of UCS, deformation, pH value, and microscopic mechanism of contaminated soils. The results demonstrated that the UCS of contaminated soils decreased with the increasing F-T cycles and Cu2+ concentration; the strength loss rate increased first and then decreased as the F-T cycles increased. The failure strain rose first and then reduced with the increase of F-T cycles, and increased with the rise of Cu2+ concentration. There was a considerable correlation between UCS, failure strain, and deformation modulus E50. The pH value decreased with the increasing F-T cycles and Cu2+ concentration. The microscopic characteristics indicated that the formation of hydrated calcium silicate and ettringite was the fundamental reason for the enhanced UCS. Besides, heavy metals could be solidified and stabilized by chemical precipitation, physical encapsulation, and ion exchange. The effect of F-T cycles could significantly damage the internal structure of contaminated soils, and the frost heaving force could loosen the soil skeleton structure, leading to the deterioration of the mechanical properties.

Expression of lncRNA NEAT1 in endometriosis and its biological functions in ectopic endometrial cells as mediated via miR-124-3p

Yuan Donglan,Zhu Dandan,Yin Boyu,Ge Hongshan,Zhao Yinling,Huang Aihua,Wang Xiaosu,Cao Xiuhong,Xia Nan,Qian Hua 한국유전학회 2022 Genes & Genomics Vol.44 No.5

Background: Endometriosis (EM) is a gynecological disease that poses severe health risks to women, although its pathogenesis has yet to be fully elucidated. It has been shown that long non-coding RNAs (lncRNAs) are closely associated with EM initiation and have a role in the development of this disease. Previous studies exploring the expression of the lncRNA nuclear paraspeckle assembly transcript 1 (NEAT1) have shown that this lncRNA functions as a tumor promoter in endometrial cancer. However, its exact mechanism of action in EM remains unclear. Objective: This report was designed to illustrate the potential molecular mechanisms of lncRNA NEAT1 on EM. Methods: Endometrial tissues were extracted from EM model rats and patients with EM. Hematoxylin and eosin staining was applied to detect the morphological changes that occurred in rats after construction of the model. Endometrial stromal cells (ESCs) were extracted from either ectopic endometrium (EC) or eutopic endometrium (EU) tissues from patients with EM. LncRNA NEAT1 and miR-124-3p expression in EM tissues and cells were subsequently evaluated by reverse transcription-quantitative (RT-q)PCR analysis. MTT assay, flow cytometric analysis, western blot assay and Transwell assay were then employed to examine the effect of NEAT1 and miR-124-3p on EC-ESC proliferation, apoptosis, migration and invasion, respectively. The targeted relationship between lncRNA NEAT1 and miR-124-3p was subsequently confirmed by dual-luciferase and co-transfection assays. Results: MiR-124-3p was identified as a target of NEAT1, and could be negatively regulated by NEAT1 in EC-ESCs. The expression level of NEAT1 was evidently increased, whereas that of miR-124-3p was decreased, in the EM in vivo model, EM tissues and EC-ESCs from patients with EM. The loss-of-function assays further established that silencing of NEAT1 could inhibit EC-ESC proliferation, migration, and invasion, but it led to the promotion of apoptosis via targeting miR-124-3p. Conclusions: NEAT1 is significantly upregulated in EM, promoting malignant behavior in EM through targeting miR-124-3p expression.

Research of the Mechanism of Low Frequency Oscillation Based on Dynamic Damping Effect

Wenying Liu,Rundong Ge,Dandan Zhu,Weizhou Wang,Wei Zheng,Fuchao Liu 대한전기학회 2015 Journal of Electrical Engineering & Technology Vol.10 No.4

For now, there are some low frequency oscillations in the power system which feature low frequency oscillation with positive damping and cannot be explained by traditional low frequency oscillation mechanisms. Concerning this issue, the dynamic damping effect is put forward on the basis of the power-angle curve and the study of damping torque in this article. That is, in the process of oscillation, damping will dynamically change and will be less than that of the stable operating point especially when the angle of the stable operating point and the oscillation amplitude are large. In a situation with weak damping, the damping may turn negative when the oscillation amplitude increases to a certain extent, which may result in an amplitude-increasing oscillation. Finally, the simulation of the two-machine two-area system verifies the arguments in this paper which may provide new ideas for the analysis and control of some unclear low frequency phenomena.

Study on the Mechanical Characteristics of Urban Sludge Solidified by Industrial Waste

Liuyan Wu,Qiang Wang,Dandan Ge,Huangrui Xu,Guojun Cai 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.7

Urban sludge is an extensive volume with a prominent environmental impact. The researchexplored an application technology for converting urban sludge into a usable improved soilresource by using industrial waste, providing a new reference for the reuse of industrial waste. In this study, three industrial wastes, namely ground granulated blast slag, calcium carbideresidue, and desulfurized gypsum, were used as curing agents to solidify the urban sludge. Based on the unconfined compressive strength (UCS) test and chamber analysis, the effects ofcuring agent dosing and maintenance age of sludge-cured soil on the UCS and stress- strainwere studied. The results showed that with the increase of curing agent, the UCS of cured soilfirst increased and then decreased, and the breaking strain showed a decreasing trend. Theoptimum ratio of materials was sludge: calcium carbide residue: ground granulated blast slag:desulfurization gypsum = 100:15:15:5, record this material ratio as C15G15D5. Moreover,trials showed that C15G15D5 cured the sludge soil better than the cement alone, whichachieved the purpose of reusing the three industrial wastes and urban sludge. It was analyzedthat the hydrated calcium silicate (C-S-H), calcium aluminate (C-A-H) and ettringite (AFt) inthe hydration products were produced to make the soil skeleton stronger and enhance thestrength of the sludge-cured soil.

Hearing Improvement in A/J Mice via the Mouse Nerve Growth Factor

Lixiang Gao,Ruli Ge,Gang Xie,Dandan Yao,Ping Li,Oumei Wang,Xiufang Ma,Fengchan Han 대한이비인후과학회 2017 Clinical and Experimental Otorhinolaryngology Vol.10 No.4

Objectives. To investigate the otoprotective effects of mouse nerve growth factor (mNGF) in A/J mice. Methods. The mice at postnatal day 7 (P7) were randomly separated into a mNGF treated group (mNGF group) and a distilled water (for injection) treated group (control group). The mNGF dissolved in distilled water or distilled water alone was given to the mice once every other day from P7 by intramuscular injection in the hips. The otoprotective effects of mNGF in A/J mice were observed in a time course manner. The thresholds of auditory-evoked brainstem response (ABR) were tested from the age of the 3rd to the 8th week. Sections of the inner ears were stained by hematoxylin and eosin, and spiral ganglion neurons (SGNs) were observed at the age of the 3rd, the 6th, and the 8th week. Counts of whole mount outer hair cells (OHCs) in the cochleae were made at the age of 8 weeks. Expression of apoptosis related genes was determined by quantitative real-time polymerase chain reaction and Western blotting. Results. ABR thresholds of the mNGF group were significantly lower than those of the control group at the age of the 6th and the 8th week. Moreover, the mNGF preserved OHC and SGN in the mouse cochleae in this period. Further experiments showed that the expression of caspase genes (including caspase-3) was inhibited in the mouse inner ears in the mNGF group. Conclusion. The mNGF improves hearing in A/J mice by preserving SGN and OHC in the cochleae.