Comparison of image masking methods for pump impeller blade region PIV experiments

Xiaodong Liu,Tingting Yan,Qiang Zhong,Zhuqing Liu,Fujun Wang,Yaojun Li,Wei Yang 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.6

Due to the blade reflection effect when applying the PIV technology to the internal flow field measurement of rotating machinery, the blade area requires special treatment. In this paper, zero-value, particle image, random number, and mean-value masking methods are compared and analyzed based on particle images from the PIV challenge and rotating impeller. The peak significance and coordinates deviations are used as the masking effect evaluation criteria. The results indicate that an increase in the interrogation window masking area proportion causes a weakening of the PIV calculation particle cluster displacement peak value. The peak position is shifted, which leads to the wrong velocity vector. The masking area proportion should not be higher than 0.7, 0.5, 0.19, and 0.22 for mean-value, random number, zero-value, and particle image masking methods, respectively. The results show that flow field calculation results near the blade boundary are more accurate for mean-value masking.

Relationships Among Character Strengths, Self-efficacy, Social Support, Depression, and Psychological Well-being of Hospital Nurses

Xie Jianfei,Liu Min,Zhong Zhuqing,Zhang Qiuxiang,Zhou Jianda,Wang Lu,Ma Keke,Ding Siqing,Zhang Xiaohong,Sun Qian,Cheng Andy S.K. 한국간호과학회 2020 Asian Nursing Research Vol.14 No.3

Purpose: From the perspective of positive psychology, our study aimed to explore depressive symptoms and psychological well-being among Chinese nurses, as well as analyze the impacts of character strengths, self-efficacy and social support on the mental health of nurses. Methods: A cross-sectional and descriptive design using five self-reported questionnaires was used to investigate a cohort of 4238 nurses during 2018. A structural equation modeling analysis was used to verify a hypothetical model linking character strengths, self-efficacy, social support, depressive symptoms, and psychological well-being. Results: The prevalence of depression among this cohort of Chinese nurses was 58.1%. The mean scores for caring, inquisitiveness, and self-control were 19.93 (SD ¼ 2.82), 15.94 (SD ¼ 3.00), and 16.34 (SD ¼ 2.95), respectively. The hypothesized model was a good fit of the data (c2/df ¼ 1.77, p ¼ .183, root mean square error of approximation ¼ 0.04, goodness of fit index ¼ 1.00, comparative fit index ¼ 1.00, TuckereLewis index ¼ 1.00). Except for the path from self-control to depression, the other hypothetical paths investigated were statistically significant. Conclusion: Character strengths were directly and positively associated with psychological well-being. Inquisitiveness was the strongest direct protective factor for depression. In addition, character strengths indirectly alleviated depression and increased psychological well-being through mediating variables of social support and self-efficacy. This study should alert nurse managers that more attention should be paid to the character strengths and mental health of nurses. This study provides evidence for interventions based on character strengths as a management strategy to support the mental health of nurses.

Prediction model of stall evolution stages in a centrifugal impeller based on characteristic analysis of the hydraulic torque of blades and support vector machine

Luan Shi,Zhuqing Liu,Wei Yang,Yaojun Li,Xiaodong Liu,Ran Tao 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.10

If a centrifugal impeller is in deep stall, it requires a large amount of additional energy to break free. As such, it is crucial to study the prediction method of impeller stall and establish its relationship with force and torque. This study employs a computational fluid dynamics numerical simulation method to analyze the flow field within the impeller of a centrifugal pump, while monitoring the changes in hydraulic torque of the blades. By examining the impeller’s internal flow field characteristics and external (energy performance) characteristics curves under different working conditions, the stall process was classified into three stages: germination, transition and stabilization. The evolution of stall cells under different stall stages was also analyzed. We utilized time-frequency conversion and analysis to extract characteristic parameters from instantaneous hydraulic torque results generated under different working conditions. A more effective model for predicting impeller stall stages was built by virtue of support vector machine algorithm. The proposed model exhibits improved feasibility and effectiveness in comparison to traditional prediction methods. It is expected to have significant implications for stable operation monitoring and safety protection of centrifugal pumps.

The complete mitochondrial genome of cricket Sclerogryllus punctatus (Orthoptera: Gryllidae) and phylogenetic analysis

Yu Zheyuan,Xie Huicong,Liu Yijiao,Li Kai,He Zhuqing 한국응용곤충학회 2022 Journal of Asia-Pacific Entomology Vol.25 No.3

The crickets of genus Sclerogryllus Gorochov, 1985 belongs to subfamily Sclerogryllinae of family Gryllidae. In this study, we report the first complete mitogenome sequences of the genus Sclerogryllus, and analyze the features of mitogenomes of S. punctatus. The mitogenome of S. punctatus was 15,438 bp and consisted of 37 genes, coding for 13 proteins, 2 ribosomal RNA (rRNA) and 22 transfer RNA (tRNA), and a control region. S. punctatus shares the arrangement of trnE-trnS-trnN with most mitogenomes of Grylloidea. Besides, the tRNAs possess the typical cloverleaf secondary structure except for the trnS1 (AGN) gene. The phylogenetic analysis using 13 proteincoding genes and 2 rRNA represents that genus Sclerogryllus is included in subfamily Gryllinae. Our results uncover the phylogenetic position of genus Sclerogryllus by mitogenome data within the family Gryllidae.

The complete mitochondrial genome of cricket Sclerogryllus punctatus (Orthoptera: Gryllidae) and phylogenetic analysis

Yu Zheyuan,Xie Huicong,Liu Yijiao,Li Kai,He Zhuqing 한국응용곤충학회 2022 Journal of Asia-Pacific Entomology Vol.25 No.2

The crickets of genus Sclerogryllus Gorochov, 1985 belongs to subfamily Sclerogryllinae of family Gryllidae. In this study, we report the first complete mitogenome sequences of the genus Sclerogryllus, and analyze the features of mitogenomes of S. punctatus. The mitogenome of S. punctatus was 15,438 bp and consisted of 37 genes, coding for 13 proteins, 2 ribosomal RNA (rRNA) and 22 transfer RNA (tRNA), and a control region. S. punctatus shares the arrangement of trnE-trnS-trnN with most mitogenomes of Grylloidea. Besides, the tRNAs possess the typical cloverleaf secondary structure except for the trnS1 (AGN) gene. The phylogenetic analysis using 13 proteincoding genes and 2 rRNA represents that genus Sclerogryllus is included in subfamily Gryllinae. Our results uncover the phylogenetic position of genus Sclerogryllus by mitogenome data within the family Gryllidae.

Potato tillage method is associated with soil microbial communities, soil chemical properties, and potato yield

Ma Haiyan,Xie Chen,Zheng Shunlin,Li Peihua,Cheema Hafsa Nazir,Gong Jing,Xiang Zhuqing,Liu Juanjuan,Qin Jiahao 한국미생물학회 2022 The journal of microbiology Vol.60 No.2

Intensive potato continuous cropping (IPCC) results in low potato yields compared with non-intensive potato continuous cropping (PCC) and potato-maize rotation (PMRC). However, it is still unclear whether the degree of potato continuous cropping obstacle is related to the soil environment formed by the previous crop. To investigate the effect of planting potatoes and planting maize after harvesting the spring potatoes on soil chemical properties and soil microbial community structure, an experiment was carried out in the same origin soil environment over a period of seven years: (a) PCC, i.e., spring planting; (b) IPCC, i.e., autumn and spring planting (IPCC); (c) PMRC, i.e., spring potatoes and summer maize (PMRC), and (d) fallow (CK). We confirmed that the potato yield under PMRC was significantly higher than that under PCC and IPCC. Under IPCC, soil total phosphorus content was significantly higher than other treatments, whereas ammonium nitrogen content was the lowest. Compared with PCC and IPCC, PMRC had a higher ammonium nitrogen content and lower total phosphorus content. The significantly different fungal taxa in IPCC (Glomerellales, Plectosphaerella, Thelebolales) may threaten the health of the plant and positive correlated with soil total phosphorus, while other microbial taxa in PMRC (Bacillales, Polythrincium, Helotiales) can mainly promotes plant nitrogen uptake and protects plants against diseases. The PMRC-promoting taxa were positively correlated with the ammonium nitrogen content and negative correlated with soil total phosphorus content. In summary, the cropping systems might have affected potato yields by changed soil microorganism community structures – especially fungal community structures – and by the chemical properties of the soils that also depends on microbes.