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To build the new power system with the main body of new energy, the offshore wind farm (OWF) is an important part and has been rapidly developed in coastal cities. However, the large-scale OWFs also reduce the inertia of power systems, which significantly decreases the anti-disturbance capability of system frequency Therefore, a synthetic inertia control strategy for OWF based on dual phase-locked loops (PLL) was proposed. First, the influence mechanism of PLL on virtual inertia of wind turbine was theoretically analyzed for variable parameter PLL. And the variation rule of wind turbine inertia support capacity and system frequency response characteristics with parameter changing PLL was explored. Then, the double PLL based OWF frequency regulation strategy was proposed through analyzing the negative effect of primary frequency regulation characteristics caused by the variable parameter of PLL. Finally, the effectiveness of the proposed frequency regulation strategy was verified though simulations. The results show that the proposed method has significant advantages in frequency response speed and frequency measurement noise suppression.

The aim of the present study was to investigate the protective effect of S-ketamine (S-KET) against carbon tetrachloride (CCl4)-induced liver damage and oxidative stress, as well as to elucidate the related underlying mechanisms. Blood was collected to measure biochemical parameters (alanine transaminase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP), total bilirubin (TB) and [gamma]-glutamyltransferase ([gamma]-GT)) and the liver was harvested for histopathological analysis of enzymes related to the antioxidant response (malondialdehyde (MDA), superoxide dismutase (SOD), glutathione (GSH), and glutathione peroxidase (GSH-PX)). Liver cell apoptosis was evaluated using the TUNEL assay. In addition, the expression levels of apoptosis-related proteins and the nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) signaling pathway were detected by Western blot analysis to explore potential mechanisms. S-KET protected the liver from CCl4-induced damage. The changes to the liver biochemical parameters (increased ALT, AST, ALP, TB, and [gamma]-GT) and oxidative stress-related indicators (increased MDA; depleted SOD, GSH, and GSH-PX) induced by CCl4 were inhibited by S-KET. S-Ket also inhibited CCl4-induced cell apoptosis, the changes in expression of related proteins, and blocked CCl4-induced liver injury and oxidative stress via activation of the Nrf2/HO-1 signaling pathway. S-KET effectively protected the liver by inhibition of CCl4-induced damage via upregulation the Nrf2/HO-1 signaling pathway. Key words: S-ketamine, liver injury, inflammatory response, oxidative stress, Nrf2/HO-1 signaling pathway. Cette etude portait sur l'effet protecteur de la S-ketamine (S-KET) contre les dommages hepatiques provoques par le tetrachlorure de carbone (CCl4) et le stress oxydatif, ainsi que les modes d'action sous-jacents. Nous avons preleve du sang en vue de mesurer des parametres biochimiques (ALT, AST, phosphatase alcaline, bilirubine totale et [gamma]-GT) et le foie en vue d'epreuves histopathologiques d'enzymes liees a la reaction antioxydante (MDA, SOD, GSH, and GSH-PX). Nous avons evalue l'apoptose des cellules hepatiques a l'aide de l'epreuve de TUNEL. De plus, nous avons etudie les taux d'expression de proteines liees a l'apoptose et la voie de signalisation Nrf2/HO-1 a l'aide de l'immunobuvardage de Western en vue d'explorer les modes d'action eventuels. La S-KET permettait de proteger le foie contre les dommages provoques par le CCl4. Les variations des parametres biochimiques hepatiques (hausse de l'ALT, de l'AST, de la phosphatase alcaline et des [gamma]-GT) et des indicateurs du stress oxydatif (hausse du MDA; depletion en SOD, GSH et GSH-PX) provoques par le CCl4 pouvaient etre inhibees par la S-KET. La S-KET entrainait aussi une inhibition de l'apoptose cellulaire engendree par le CCl4 et des variations de l'expression des proteines qui y sont liees, avec une attenuation des lesions hepatiques provoquees par le CCl4 de meme que du stress oxydatif par l'intermediaire de l'activation de la voie de signalisation Nrf2/HO-1. La S-KET permettait de proteger le foie efficacement par l'inhibition des dommages provoques par le CCl4 par l'intermediaire de la regulation a la hausse de la voie de signalisation Nrf2/HO-1. [Traduit par la Redaction] Mots-cles: S-ketamine, lesions hepatiques, reaction inflammatoire, stress oxydatif, voie de signalisation Nrf2/HO-1., Introduction Liver injury and disease threaten human health and quality of life (Hoek and Pastorino 2002; Peng et al. 2018). Oxidative stress due to frequent exposure to detrimental environmental factors, [...]

In underground coal mining, there is an urgent need for reducing the noise, hydraulic shock, and leakage of reciprocating pumps. Flow pulsation is strongly dependent on the number of pistons for single-acting reciprocating pumps. Water hydraulic radial piston pumps (RPPs) allow the pistons to be radially distributed, which makes the multi-piston design easier compared to traditional single-acting reciprocating piston pumps. In this study, a novel valve-distributed water RPP was developed in which the star wheel assembled on the camshaft is used to drive the connecting rod-crosshead-piston assembly and realize the reciprocation of the piston and suction-discharge of the pump check valves. Mathematical and numerical models representing the RPP were built using MATLAB and AMESim, respectively. Three-dimensional computational fluid dynamics analyses were performed to investigate the internal flow field of the suction and discharge circuits as well as the flow characteristics of the discharge valve opening. A prototype pump was manufactured and tested for 200 h and then disassembled to evaluate the wear condition. The tested instant flow rates were lower than those obtained from the theoretical and simulation analyses. The experimental results also revealed that the average flow rates were almost independent of the output pressure and that the volumetric efficiency decreased with increasing rotational speed when the output pressure was larger than 25 MPa. Inspecting the disassembled water RPP revealed that scuffing problems occurred in the pistons, whereas the other components remained intact. The findings of this study offer a reference for water hydraulic power units in various applications and for investigating the intensity of water hydraulics. [ABSTRACT FROM AUTHOR]

[Introduction] In view of the fatigue problem of support structure for offshore wind turbine, fatigue performance of transition piece with external stiffening ring was studied. [Method] Static and fatigue tests of A1/5 scale simplified support structure model were carried out to obtain their hot spot stress and fatigue life. Finite element analysis for the test model was conducted with different element type according to DNV rules. Fatigue damage obtained from experimental tests was compared with that calculated by numerical simulations. [Result] The results show that the main discrepancy between test results and specification methods is the selection of S-N curves. [Conclusion] Finally, on the basis of experimental data and DNV rules, two different methods for evaluating the fatigue damage of transition piece are given. This work provides some guidance for further application.

This study aimed to investigate the potential nephrotoxicity of icaritin and the underlying mechanism by in vitro-in vivo experiment technology combined with proteomics technology. First, icaritin showed a significant cytotoxic effect on HK-2 cells, which was accompanied by increased LDH and TNF-α in the supernatant, decreased protein expressions of Bcl-2 and increased Bax and enhanced apoptosis of HK-2 cells as measured by TUNEL staining. Moreover, icaritin induced obvious tubular damage and up-regulation of BUN and CRE levels in plasma in mice. Second, intracellular uptake of icaritin was considerably higher in hOAT1-HEK293 cells than in mock-HEK293 cells, suggesting that icaritin might accumulate in renal cells via OAT1 uptake. Importantly, icaritin caused significant changes in the PPAR signaling pathway in HK2 cells through proteomic analysis. Then, in vitro and in vivo results verified that icaritin significantly downregulated the protein expression of PPAR-α as well as downregulated APOB, ACSL3, ACSL4, and upregulated 5/12/15-HETE, implying that a lipid metabolism disorder was involved in the icaritin-induced nephrotoxicity. Finally, icaritin was found to increase the accumulation of iron and LPO levels while reducing the activity of GPX4, suggesting that ferroptosis was involved in the nephrotoxicity induced by icaritin. [ABSTRACT FROM AUTHOR]

The 110 mining method is a high-efficiency entry-retaining technology without coal pillars or filling materials. At present, there is no precedent for its application in the Huaneng Group. In order to introduce this technology, it is planned to carry out experimental application research in the Yuwang NO.1 Coal Mine of the Huaneng Diandong mining area. The Yuwang NO.1 Coal Mine is a typical coal and gas outburst mine with a coal seam group. In view of the introduction of the 110 mining method under these conditions, first, the geological conditions of the Yuwang NO.1 Coal Mine in the Huaneng Diandong mining area are analyzed, the geological characteristics of the test mining face are summarized, and the practical feasibility of the 110 mining method is analyzed according to the geological characteristics of "one soft, one low, two high, and two complex". Then, according to the engineering experience, calculations, and analysis, the key parameters of roof cutting of the test mining face in the Yuwang NO.1 Coal Mine are obtained, and with the help of a numerical simulation, the roof-cutting height, the roof-cutting angle, and the blasting parameters are numerically simulated and analyzed. The roof-cutting key parameters of the test face are obtained as follows: the roof-cutting depth is 7 m, the roof-cutting angle is 15°, and the blasting method is continuous hole blasting with 500 mm spacing. After that, according to the coal and gas outburst and the occurrence conditions of coal seams in the Yuwang NO.1 Coal Mine, a variety of gob closure design schemes and gob gas drainage design schemes are put forward, and the field effect investigation scheme is given. After the tunnels and open-off cut of the test coal mine's first mining face are connected, under the guidance of the above research results, the field blasting test and the 110 mining method entry-retaining test are further carried out to verify the rationality of the design of the roof-cutting parameters and the feasibility of the gangue wall closure and gas drainage design. Furthermore, in the process of the field practice, continuous research is carried out on the stope pressure law and the adjacent layer gas drainage technology under the 110 mining method, and finally, the 110 mining method application technology system in the Diandong Mining Area is formed. [ABSTRACT FROM AUTHOR]