Design of overvoltage suppression filter based on high-frequency modeling of cable in SiC based motor drive

SiC-based motor drives have the advantages of achieving higher efficiency and higher power density than traditional Si-based motor drives, and are gradually being widely used in electric power transmission. Due to different application situations such as oil field and airplane, a long cable is applied between the motor drive and three-phase motor and the distance may exceed hundreds of meters, which will cause serious voltage reflection problem, damaging working life of the motor. Meanwhile, the high slew rate of output voltage created by SiC-based motor drive deteriorates this phenomenon. In order to solve this problem, we first analyze the principle and influencing factors of voltage reflection, and establish the equivalent circuit model of the long cable. Then we put forward design method of LRC passive filter to suppress voltage reflection, and give simulation analysis. At last we built an experimental platform to verify the effectiveness of the LRC passive filter in SiC-based motor drive, and the experimental results show that the LRC passive filter with optimized parameters has good suppression effect of voltage reflection

Numerical Simulation of a Deep Excavation near a Shield Tunnel

A conveyance water shield tunnel under the Yangtze River, which was designed for the Jiangsu Changshu Power Plant Co., Ltd., was damaged due to water leakage and submersion. In order to complete the engineering, the shield tunnel should be repaired, and the connection between the shield and standpipes should be completed. Therefore, a deep excavation recovery program was designed. According to the excavation design, the distance between the axes of the two tunnels is only 20.8 m, but the depth of excavation reaches 15.1 m. Because of the small distance between the deep excavation and the adjacent west line tunnel, the new excavation in the east line tunnel might have large effects on the west line tunnel, and the environmental effects on the west tunnel due to the excavation should be evaluated. Simulations using 3D and 2D finite element methods were performed. The variations in the loads and lateral deformations on the retaining structures due to earth pressure differences outside and inside the foundation pit were analyzed in detail. The environmental effects on the west line tunnel due to deep excavation were evaluated. The 2D and 3D numerical simulation results were compared. The numerical simulation results agree with practical engineering and are applicable and reliable

2-(Pyrimidin-2-ylsulfan­yl)acetic acid

The mol­ecule of the title compound, C6H6N2O2S, lies on a crystallographic mirror plane with the methyl­ene H atoms related by mirror symmetry. In the crystal packing, mol­ecules are linked into layers by inter­molecular O—H⋯N and C—H⋯O hydrogen bonds

Hypoxia-mimetic agents inhibit proliferation and alter the morphology of human umbilical cord-derived mesenchymal stem cells

<p>Abstract</p> <p>Background</p> <p>The therapeutic efficacy of human mesenchymal stem cells (hMSCs) for the treatment of hypoxic-ischemic diseases is closely related to level of hypoxia in the damaged tissues. To elucidate the potential therapeutic applications and limitations of hMSCs derived from human umbilical cords, the effects of hypoxia on the morphology and proliferation of hMSCs were analyzed.</p> <p>Results</p> <p>After treatment with DFO and CoCl₂, hMSCs were elongated, and adjacent cells were no longer in close contact. In addition, vacuole-like structures were observed within the cytoplasm; the rough endoplasmic reticulum expanded, and expanded ridges were observed in mitochondria. In addition, DFO and CoCl₂treatments for 48 h significantly inhibited hMSCs proliferation in a concentration-dependent manner (<it>P </it>< 0.05). This treatment also increased the number of cells in G0/G1 phase and decreased those in G2/S/M phase.</p> <p>Conclusions</p> <p>The hypoxia-mimetic agents, DFO and CoCl₂, alter umbilical cord-derived hMSCs morphology and inhibit their proliferation through influencing the cell cycle.</p

Associations of Social, Cultural, and Community Engagement With Health Care Utilization in the US Health and Retirement Study

IMPORTANCE: There is growing evidence for the health benefits associated with social, cultural, and community engagement (SCCE), including for supporting healthy behaviors. However, health care utilization is an important health behavior that has not been investigated in association with SCCE. OBJECTIVE: To examine the associations between SCCE and health care utilization. DESIGN, SETTING, AND PARTICIPANTS: This population-based cohort study used data from the 2008 to 2016 waves of the Health and Retirement Study (HRS), a longitudinal panel study using a nationally representative sample of the US population aged 50 years and older. Participants were eligible if they reported SCCE and health care utilization in the relevant HRS waves. Data were analyzed from July to September 2022. EXPOSURES: SCCE was measured with a 15-item Social Engagement scale (including community, cognitive, creative, or physical activities) at baseline (frequency) and longitudinally over 4 years (no, consistent, increased, or decreased engagement). MAIN OUTCOMES AND MEASURES: Health care utilization was assessed in association with SCCE within 4 overarching categories: inpatient care (ie, hospital stays, hospital readmissions, length of hospital stays), outpatient care (ie, outpatient surgery, physician visits, number of physician visits), dental care (including dentures), and community health care (ie, home health care, nursing home stays, nights in a nursing home). RESULTS: A total of 12 412 older adults (mean [SE] age, 65.0 [0.1] years; 6740 [54.3%] women) were included in short-term analyses with 2 years of follow-up. Independent of confounders, more SCCE was associated with shorter hospital stays (incidence rate ratio [IRR], 0.75; 95% CI, 0.58-0.98), greater odds of outpatient surgery (odds ratio [OR], 1.34; 95% CI, 1.12-1.60) and dental care (OR, 1.73; 95% CI, 1.46-2.05), and lower odds of home health care (OR, 0.75; 95% CI, 0.57-0.99) and nursing home stays (OR, 0.46; 95% CI, 0.29-0.71). Longitudinal analysis included 8635 older adults (mean [SE] age, 63.7 [0.1] years; 4784 [55.4%] women) with data on health care utilization 6 years after baseline. Compared with consistent SCCE, reduced SCCE or consistent nonparticipation in SCCE was associated with more inpatient care utilization, such as hospital stays (decreased SCCE: IRR, 1.29; 95% CI, 1.00-1.67; consistent nonparticipation: IRR, 1.32; 95% CI, 1.04-1.68) but lower levels of subsequent outpatient care, such as physician visits (decreased SCCE: OR, 0.68; 95% CI, 0.50-0.93; consistent nonparticipation: OR, 0.62; 95% CI, 0.46-0.82) and dental care utilization (decreased SCCE: OR, 0.68; 95% CI, 0.57-0.81; consistent nonparticipation: OR, 0.51; 95% CI, 0.44-0.60). CONCLUSIONS AND RELEVANCE: These findings suggest that more SCCE was associated with more dental and outpatient care utilization and reduced inpatient and community health care utilization. SCCE might be associated with shaping beneficial early and preventive health-seeking behaviors, facilitating health care decentralization and alleviating financial burden by optimizing health care utilization

Tetra­aqua­hexa­kis(μ2-quinoline-4-carboxyl­ato)diyttrium(III) dihydrate

In the title centrosymmetric binuclear complex, [Y2(C10H6NO2)6(H2O)4]·2H2O, each YIII atom is nine-coordin­ated by nine O atoms from five ligands and two water mol­ecules in a slightly distorted monocapped square-anti­prismatic coordination environment. The YIII atoms are separated by a distance of 4.0363 (9) Å. The ligands coordinate in three different modes: chelating, bridging and a mixed chelating bridging mode. In the crystal structure, the binuclear complexes are linked by O—H⋯O and O—H⋯N hydrogen bonds, forming a three-dimensional network