Influence of rub groove on rotordynamics associated with leakage air flow through a labyrinth seal

Wei Zhe Wang,Ying Zheng Liu,Guang Meng,Pu Ning Jiang 대한기계학회 2010 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.24 No.8

An extensive investigation of influence of rub grooves on dynamics and stability of the rotor, which is subjected to aerodynamic forcing associated with the leakage flow through 44 straight-through seals, was performed by using numerical calculations based on the single control-volume method and the perturbation analysis. Three cases of different groove configurations were chosen for the comparative study, e.g., the seal without rub groove (case1), the seal with upstream shifting of the seal tooth in respect to the rub groove (case2) and the seal with location of the seal tooth in the middle station of the rub groove (case3). The orifice contract coefficient adopted in reduction of rotordynamic coefficients was provided by using Computational Fluid Dynamics (CFD). Influence of rub grooves on the leakage flow was obtained in terms of the close-up view of the flow pattern near the seal tooth, leakage flow rate, distributions of the mean pressure and circumferential velocity in cavities. In comparison to case 1, the leakage flow in case 3 is considerably intensified, while which in case 2 is slightly increased. Dynamics and instability of the rotor in all cases was discussed in terms of the rotordynamic coefficients and the logarithmic decrement, respectively. The results disclosed that the aerodynamic forcing in case 2 intensified the destabilization of the rotor system.

Seroprevalence of Encephalitozoon cuniculi and Toxoplasma gondii in domestic rabbits (Oryctolagus cuniculus) in China

Qing-Feng Meng,Wei-Lin Wang,Xiao-Ting Ni,Hai-Bin Li,Gui-Zhe Yao,Xiao-Lin Sun,Wei-Li Wang,Wei Cong 대한기생충학열대의학회 2015 The Korean Journal of Parasitology Vol.53 No.6

The breeding of domestic rabbits (Oryctolagus cuniculus) for human consumption has a long tradition in China. Infections that can affect the production of meat or even be transmitted from animals to humans are important to monitor, especially for public health reasons as well as for their impact on animal health. Thus, a total of 1,132 domestic rabbit sera from 4 regions in China were collected for serological screening for Encephalitozoon cuniculi and for Toxoplasma gondii by ELISA and modified agglutination test (MAT), respectively. Antibodies to E. cuniculi were detected in 248/1,132 (21.9%) sera tested while antibodies against T. gondii revealed a seroprevalence of 51/1,132 (4.5%). We believe that the present results are of epidemiological implications and public health importance due to the acknowledged susceptibility of humans to E. cuniculi and T. gondii infections. Therefore, routine screening tests of domestic rabbits are proposed considering the zoonotic potential of these parasites.

In Vivo Detection of Lipid-Core Plaques by Coronary CT Angiography: A Head-to-Head Comparison with Histologic Findings

Wei-hua Yin,Yan Zhang,Xiang-nan Li,Hong-yue Wang,Yun-qiang An,Yang Sun,Zhi-hui Hou,Yang Gao,Bin Lu,Zhe Zheng 대한영상의학회 2020 Korean Journal of Radiology Vol.21 No.2

Objective: We sought to distinguish lipid plaques using a CT quantitative pixel density histogram, based on the pathological diagnosis of lipid cores as the gold standard. Materials and Methods: Eight patients awaiting heart transplantation due to end-stage coronary heart disease underwent coronary CT angiography (CCTA) spectroscopy prior to heart transplantation; coronary artery pathological analysis was performed for all patients. Lipid-core plaques were defined pathologically as manifesting a lipid core diameter > 200 μm, a circumference > 60 degrees, and a cap thickness < 450 μm. The percentage distributions of CT pixel attenuation ≤ 20, 30, 40, and 50 HU were calculated using quantitative histogram analysis. Results: A total of 271 transverse sections were co-registered between CCTA and pathological analysis. Overall, 26 lipid cores and 16 fibrous plaques were identified by pathological analysis. There was no significant difference in median CT attenuation between the lipid and fibrous plaques (51 HU [interquartile range, 46–63] vs. 57 HU [interquartile range, 50–64], p = 0.659). The median percentage of CT pixel attenuation ≤ 30 HU accounted for 11% (5–17) of lipid-core plaques and 0% (0–2) of fibrous plaques (p < 0.001). The sensitivity and specificity of the method for diagnosing lipid plaques by the average CT pixel attenuation ≤ 30 HU were 80.8% and 87.5%, respectively. The area under the receiver operator characteristics curve was 0.898 (95% confidence interval: 0.765–0.970; 3.0% was the best cut-off value). The diagnostic performance was significantly higher than those of the average pixel CT attenuation percentages ≤ 20, 40, and 50 HU and the mean CT attenuation (p < 0.05). Conclusion: In in vivo conditions, with the pathological lipid core as the gold standard, quantification of the percentage of average CT pixel attenuation ≤ 30 HU in the histogram can be useful for accurate identification of lipid plaques.

A new integrative evaluation method for candidate reservoirs of hydrocarbon gas drive

Wei Hu,Zhe Wang,Jingchen Ding,Zhilin Wang,Quanzheng Ma,Yu Gao 한국자원공학회 2015 Geosystem engineering Vol.18 No.1

Before implementing hydrocarbon gas drive, an applicable evaluation of reservoirs for hydrocarbon gas drive can improve the success rate and economic benefit. On the basis of a large amount of literature research, 11 factors affecting the hydrocarbon gas injection development have been screened out. These 11 factors constitute the suitability evaluation indexes of candidate reservoirs for hydrocarbon gas drive. Meantime, the classification of 11 evaluation indexes has also been set up, and fuzzy statistical method, analytic hierarchy process, and expert assessment method have been adopted to obtain the weight value of each evaluation index. Three candidate reservoirs have been taken for example; using multi-level fuzzy comprehensive evaluation to optimize the most suitable candidate reservoir, the potential size of three candidate reservoirs for hydrocarbon gas drive is provided. By comparing the evaluation results with the numerical reservoir simulation results, the evaluation method not only gives a correct evaluation for candidate reservoirs but also has a high practicability and reliability.

Leaching characteristics and curing mechanism of magnesium phosphate cement solidified zinc-contaminated soil in an acid rain environment

Zhe Wang,Hangjun Zhu,Xuehui Wu,Binpin Wei,Hongli Zhou,Sifa Xu 대한환경공학회 2021 Environmental Engineering Research Vol.26 No.4

A semi-dynamic leaching test was used to simulate the erosion effect of acid rain on magnesium phosphate cement (MPC)-stabilized/solidified zinc-contaminated soil. The leaching characteristics and curing mechanism were studied with a combination of X-ray diffraction (XRD) and scanning electron microscopy (SEM). Influences of the initial pH value of the simulated acid rain, the ratio of the curing agent (MgO/KH₂PO₄, abbreviated M/P), and the mass of water glass on the leaching characteristics of Zn<SUP>2+</SUP> and conductivity in the leachate of the sample were studied. It is shown that the curing effect of the cement component on Zn<SUP>2+</SUP> is better for M/P = 6 when compared to M/P = 4 in a strong acid environment. While in a weak acid environment, it is observed that the curing effect is superior when M/P = 4. Also it is observed that 4% water glass content can effectively improve the cement curing effect of heavy metal Zn in an acid rain environment. These results indicate that water glass can be effectively applied to MPC solidified heavy metal Zn.

Effects of Exopolysaccharide Production on Liquid Vegetative Growth, Stress Survival, and Stationary Phase Recovery in Myxococcus xanthus

Wei Hu,Jing Wang,Ian McHardy,Renate Lux,Zhe Yang,Yuezhong Li,Wenyuan Shi 한국미생물학회 2012 The journal of microbiology Vol.50 No.2

Exopolysaccharide (EPS) of Myxococcus xanthus is a wellregulated cell surface component. In addition to its known functions for social motility and fruiting body formation on solid surfaces, EPS has also been proposed to play a role in multi-cellular clumping in liquid medium, though this phenomenon has not been well studied. In this report, we confirmed that M. xanthus clumps formed in liquid were correlated with EPS levels and demonstrated that the EPS encased cell clumps exhibited biofilm-like structures. The clumps protected the cells at physiologically relevant EPS concentrations, while cells lacking EPS exhibited significant reduction in long-term viability and resistance to stressful conditions. However, excess EPS production was counterproductive to vegetative growth and viable cell recovery declined in extended late stationary phase as cells became trapped in the matrix of clumps. Therefore, optimal EPS production by M. xanthus is important for normal physiological functions in liquid.

A New Boiler-turbine-heating Coordinated Control Strategy to Improve the Operating Flexibility of CHP Units

Wei Wang,Guangming Zhang,Yuguang Niu,Zhenyu Chen,Peiran Xie,Zhe Chen 제어·로봇·시스템학회 2022 International Journal of Control, Automation, and Vol.20 No.5

The operating flexibility of the power units is getting increasing attention from power systems especially those with large-scale fluctuating renewable energies. However, the combined heat and power (CHP) units are getting a bottleneck because their electricity productions are restricted by heat productions. This study aims to develop an electric-heat coordinated control strategy to make the CHP units more flexible. First of all, the dynamic model for a 300 MW CHP unit is set up, and its linear state-space description is obtained. A control strategy based on linear quadratic regulator (LQR) is then developed to satisfy different heat-power demands in various operating conditions. The control weights Q and R are optimized by particle swarm optimization. Moreover, the improved coordinated control strategy based on precise energy balance is put forward to increase the CHP power ramp rate considering electricity priority strategy and recovery control of the heat source. Finally, the simulation results show that the improved strategy is suitable for various CHP operating scenarios, and the case for electricity priority and heat recovery control significantly improves the unit power rate on the premise of stable heat supply. This work provides a reliable and flexible control mode for CHP units, which can support the power system stability and renewable energy integration.

Enhancement of Protective Effects of Radix Scutellariae on UVB-induced Photo Damage in Human HaCaT Keratinocytes

Wang, Yu-shuai,Cho, Jin-Gyeong,Hwang, Eun-Son,Yang, Jung-Eun,Gao, Wei,Fang, Min-zhe,Zheng, Sheng-dao,Yi, Tae-Hoo Springer-Verlag 2018 Applied biochemistry and biotechnology Vol.184 No.4

MTHFR C667T Polymorphism Association with Lung Cancer Risk in Henan Province: A Case-control Study

Cheng, Zhe,Wang, Wei,Dai, Ling-Ling,Kang, Yan Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.6

The current study was performed to assess any association between the methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism and risk of lung cancer in Henan province. This case-control study involved94 patients with newly histological confirmed lung cancer and 78 healthy controls. Genotyping was achieved with peripheral blood lymphocytes DNA and association of the polymorphism with risk of lung cancer was estimated by unconditional logistic regression analysis. The frequencies of the MTHFR 667TT genotype were 37.2% in cases compared with 23.1% in controls (${\chi}^2$ = 4.008, P = 0.045). Individuals with the 667CC/CT genotype displayed a significantly reduced risk of lung cancer compared with those with the TT genotypes [adjusted odds ratio (OR), 0.506; 95% confidence interval (95% CI), 0.258 - 0.991]. The C667T polymorphism might have a significant effect on the occurrence of lung cancer in Henan province.

hOGG1, p53 Genes, and Smoking Interactions are Associated with the Development of Lung Cancer

Cheng, Zhe,Wang, Wei,Song, Yong-Na,Kang, Yan,Xia, Jie Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.5

This study aimed to investigate the effects of Ser/Cys polymorphism in hOGG1 gene, Arg/Pro polymorphism in p53 gene, smoking and their interactions on the development of lung cancer. Ser/Cys polymorphism in hOGG1 and Arg/Pro polymorphism in p53 among 124 patients with lung cancer and 128 normal people were detected using PCR-RFLP. At the same time, smoking status was investigated between the two groups. Logistic regression was used to estimate the effects of Ser/Cys polymorphism and Arg/Pro polymorphisms, smoking and their interactions on the development of lung cancer. ORs (95% CI) of smoking, hOGG1 Cys/Cys and p53 Pro/Pro genotypes were 2.34 (1.41-3.88), 2.12 (1.03-4.39), and 2.12 (1.15-3.94), respectively. The interaction model of smoking and Cys/Cys was super-multiplicative or multiplicative, and the OR (95% CI) for their interaction item was 1.67 (0.36 -7.78). The interaction model of smoking and Pro/Pro was super-multiplicative with an OR (95%CI) of their interaction item of 5.03 (1.26-20.1). The interaction model of Pro/Pro and Cys/Cys was multiplicative and the OR (95%CI) of their interaction item was 0.99 (0.19-5.28). Smoking, hOGG1 Cys/Cys, p53 Pro/Pro and their interactions may be the important factors leading to the development of lung cancer.