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Pressure fluctuation is the primary reason for unstable operations of double-suction centrifugal pumps. By using flush mounted pressure transducers in the semispiral suction chamber and the volute casing of a double-suction pump, the pressure fluctuation signals were obtained and recorded at various operating conditions. Spectral analyses were performed on the pressure fluctuation signals in both frequency domain and time-frequency domain based on fast Fourier transform (FFT) and an adaptive optimal-kernel time-frequency representation (AOK TFR). The results show that pressure fluctuations at the impeller rotating frequency and some lower frequencies dominated in the semispiral suction chamber. Pressure fluctuations at the blade passing frequency, the impeller rotating frequency, and their harmonic frequencies were identified in the volute casing. The amplitude of pressure fluctuation at the blade passing frequency significantly increased when the flow rate deviated from the design flow rate. At 107% of the design flow rate, the amplitude increased more than 254% than that at the design flow rate. The time-frequency characteristics of these pressure fluctuations were affected greatly by both operating conditions and measurement locations. At partial flow rates the pulsation had a great irregularity and the amplitudes at the investigated frequencies were much larger than ones at the design flow rate. An asymmetrical pressure fluctuation structure in the volute casing was observed at all flow rates. The pulsation behavior at the blade passing frequency was the most prominent near the volute tongue zone, and the pressure waves propagated in both the radial and circumferential directions.

The transient analysis was carried out to investigate the dynamic stress and vibration of volute casing for a large double-suction centrifugal pump by using the transient fluid-structure interaction theory. The flow pulsations at flow rate ranging from 60% to 100% of the nominal flow rate ( ) were taken as the boundary conditions for FEM analysis of the pump volute casing structure. The results revealed that, for all operating conditions, the maximum stress located at the volute tongue region, whereas the maximum vibration displacement happened close to the shaft hole region. It was also found that the blade passing frequency and its harmonics were dominant in the variations of dynamic stress and vibration displacement. The amplitude of the dominant frequency for the maximum stress detected at 0.6 was 1.14 times that at , lower than the related difference observed for pressure fluctuations (3.23 times). This study provides an effective method to quantify the flow-induced structural dynamic characteristics for a largescale double-suction pump. It can be used to direct the hydraulic and structural design and stable operation, as well as fatigue life prediction for large-scale pumps.

We aimed to analyze the expression of Cyclin D1 (CCND1) gene in ovarian cancer and the influence of silencing its expression on ovarian cancer cells based on the Oncomine database. The expression of CCND1 gene in ovarian cancer was analyzed by utilizing the relevant information in different tumors and Oncomine database. The correlation between CCDN1 expression level and prognosis of ovarian cancer was analyzed by the online database Kaplan-Meier (kmplot.com). The expression of CCND1 gene in ovarian cancer and the effect of silencing its expression on cancer cells were analyzed by cell experiments. After mining and comprehensively analyzing 7 studies on the differential expression of CCND1 gene in ovarian cancer tissue and normal ovarian tissue included in the Oncomine database, it was found that the median value of CCND1 gene ranked 218.0 (P = 8.03 × 10 −6 ) among all differentially expressed genes, suggesting that CCND1 gene expression in ovarian cancer tissue was higher than that in normal ovarian tissue. Adib Ovarian, Bonome Ovarian and Hendrix Ovarian microarrays revealed that the expression of CCND1 gene in ovarian cancer tissue was significantly higher than that in normal ovarian tissue (P < 0.05). Kaplan-Meier Plotter database showed that the overall survival and progression-free survival of ovarian cancer patients with high CCND1 expression were significantly shorter than those of patients with low CCND1 expression (P < 0.05). The expression levels of CCND1 gene in normal ovarian epithelial cells and SKOV3 ovarian cancer cells were detected by RT-PCR. The expression of CCND1 gene was significantly higher in SKOV3 group than that in control group (P < 0.01). Flow cytometry revealed that the percentage of cells in G 0 /G 1 phase was significantly higher, while that in S phase was lower in SKOV3 + siCCND1 group than the values of SKOV3 and SKOV3 + siNC groups (P < 0.05). The apoptosis rate of ovarian cancer cells was significantly higher in SKOV3 + siCCND1 group than those of SKOV3 and SKOV3 + siNC groups (P < 0.01). CCND1 gene is highly expressed in ovarian cancer tissue and related to prognosis. Preoperative evaluation of CCND1 gene expression in ovarian cancer patients may benefit the assessment of risk and prognosis.