Influence of tip clearance on pressure fluctuations in an axial flow pump

Jianjun Feng,Xingqi Luo,Pengcheng Guo,Guangkuan Wu 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.4

Rotor-stator interaction in axial pumps can produce pressure fluctuations and further vibrations even damage to the pump system in some extreme case. In this paper, the influence of tip clearance on pressure fluctuations in an axial flow water pump has been investigated by numerical method. Three-dimensional unsteady flow in the axial flow water pump has been simulated with different tip clearances between the impeller blade tip and the casing wall. In addition to monitoring pressure fluctuations at some typical points, a new method based on pressure statistics was proposed to determine pressure fluctuations at all grid nodes inside the whole pump. The comparison shows that the existence of impeller tip clearance magnifies the pressure fluctuations in the impeller region, from the hub to shroud. However, the effect on pressure fluctuation in the diffuser region is not evident. Furthermore, the tip clearance vortex has also been examined under different tip clearances.

A Robust and Removable Watermarking Scheme Using Singular Value Decomposition

( Ya-feng Di ),( Chin-feng Lee ),( Zhi-hui Wang ),( Chin-chen Chang ),( Jianjun Li ) 한국인터넷정보학회 2016 KSII Transactions on Internet and Information Syst Vol.10 No.12

Digital watermarking techniques are widely applied to protect the integrity and copyright of digital content. In a majority of the literature for watermarking techniques, the watermarked image often causes some distortions after embedding a watermark. For image-quality-concerned users, the distortions from a watermarked image are unacceptable. In this article, we propose a removable watermarking scheme that can restore an original-like image and resist signal-processing attacks to protect the ownership of an image by utilizing the property of singular value decomposition (SVD). The experimental results reveal that the proposed scheme meets the requirements of watermarking robustness, and also reestablishes an image like the original with average PSNR values of 59.07 dB for reconstructed images.

A Robust and Removable Watermarking Scheme Using Singular Value Decomposition

Di, Ya-Feng,Lee, Chin-Feng,Wang, Zhi-Hui,Chang, Chin-Chen,Li, Jianjun Korean Society for Internet Information 2016 KSII Transactions on Internet and Information Syst Vol.10 No.12

Digital watermarking techniques are widely applied to protect the integrity and copyright of digital content. In a majority of the literature for watermarking techniques, the watermarked image often causes some distortions after embedding a watermark. For image-quality-concerned users, the distortions from a watermarked image are unacceptable. In this article, we propose a removable watermarking scheme that can restore an original-like image and resist signal-processing attacks to protect the ownership of an image by utilizing the property of singular value decomposition (SVD). The experimental results reveal that the proposed scheme meets the requirements of watermarking robustness, and also reestablishes an image like the original with average PSNR values of 59.07 dB for reconstructed images.

Role of Intermetallics on Fatigue Behaviuor of Stainless Steel Adhered by Sn

Jianjun Guan,Yan Zhao,Feng Liu,Jie Zhao 대한금속·재료학회 2015 METALS AND MATERIALS International Vol.21 No.6

The fatigue property of 304 stainless steel (SS) adhered by Fe-Sn intermetallics was investigated. The microstructure of crack nucleation and crack propagation was observed, and the influence of Fe-Sn intermetallics on fatigue failure was analyzed. Fatigue tests at stress ratio of R = -1 were performed using a sine waveform at 20 Hz frequency under load control. In addition, the morphology and microfractography of the Fe-Sn intermetallics were examined under a scanning electron microscope. Results demonstrated that the adherence of the interfacial (Fe, Cr)Sn2 layer reduced the fatigue life of the 304 SS substrates. The fatigue cracks also exhibited the intergranular fracture characteristics of the intermetallics. The brittle (Fe, Cr)Sn2 intermetallics were apt to fatigue crack nucleation. The interfacial metallurgical bonding, which was caused by diffusion reaction between Fe and Sn atoms, led to crack propagation into the SS substrate.

Contact toxicity of a new acaricide, SYP-9625, to the natural predator, Chrysopa pallens

Feng Yanjiao,Zhang Lisheng,Chen Hongyin,Wang Mengqing,Liu Chenxi,Li Yuyan,Song Yuquan,Mao Jianjun 한국응용곤충학회 2021 Journal of Asia-Pacific Entomology Vol.24 No.2

SYP-9625 is a novel acaricide synthesized by using cyenopyrafen as lead compound. It is characterized by high acaricidal activity and low toxicity to mammals and has been widely used in Chinese farming areas. However, to date, the toxicity of SYP-9625 to natural enemy insects remained unclear. Here, we evaluated the effects of SYP-9625 on survival, growth, metamorphosis and reproduction of a common natural predator, Chrysopa pallens. Contact toxicity bioassay revealed that SYP-9625 had no significant detrimental impacts on egg hatchability, larval survival and duration, pupation rate, pupal mass, emergence rate, digestive enzyme activity, reproductive output and offspring quality, but drastically reduced adult survival rate, adult lifespan, secondary follicle size and vitellogenin (Vg) transcripts by 27.8%, 15.4%, 33.4% and 59.4%, respectively, suggesting a low contact toxicity of SYP-9625 to C. pallens. This study will strengthen the compatibility of chemical acaricide and natural enemy insects in integrated pest management.

Molecular Cloning and mRNA Expression of the Porcine Insulin-responsive Glucose Transporter (GLUT4)

Zuo, Jianjun,Dai, Fawen,Feng, Dingyuan,Cao, Qingyun,Ye, Hui,Dong, Zemin,Xia, Weiguang Asian Australasian Association of Animal Productio 2010 Animal Bioscience Vol.23 No.5

Insulin-responsive glucose transporter 4 (GLUT4) is a member of the glucose transporter family and mainly presents in skeletal muscle and adipose tissue. To clarify the molecular structure of porcine GLUT4, RACE was used to clone its cDNA. Several cDNA clones corresponding to different regions of GLUT4 were obtained by amplifying reverse-transcriptase products of total RNA extracted from Landrace porcine skeletal muscles. Nucleotide sequence analysis of the cDNA clones revealed that porcine GLUT4 cDNA was composed of 2,491 base pairs with a coding region of 509 amino acids. The deduced amino acid sequence was over 90% identical to human, rabbit and cattle GLUT4. The tissue distribution of GLUT4 was also examined by Real-time RT-PCR. The mRNA expression abundance of GLUT4 was heart>liver, skeletal muscle and brain>lung, kidney and intestine. The developmental expression of GLUT4 and insulin receptor (IR) was also examined by Real-time RT-PCR using total RNA extracted from longissimus dorsi (LM), semimembranosus (SM), and semitendinosus (SD) muscle of Landrace at the age of 1, 7, 30, 60 and 90 d. It was shown that there was significant difference in the mRNA expression level of GLUT4 in skeletal muscles of Landrace at different ages (p<0.05). The mRNA expression level of IR also showed significant difference at different ages (p<0.05). The developmental change in the mRNA expression abundance of GLUT4 was similar to that in IR, and both showed a higher level at birth and 30 d than at other ages. However, there was no significant tissue difference in the mRNA expression of GLUT4 or IR (p>0.05). These results showed that the nucleotide sequence of the cDNA clones was highly identical with human, rabbit and cattle GLUT4 and the developmental change of GLUT4 mRNA in skeletal muscles was similar to that of IR, suggesting that porcine GLUT4 might be an insulin-responsive glucose transporter. Moreover, the tissue distribution of GLUT4 mRNA showed that GLUT4 might be an important nutritional transporter in porcine skeletal muscles.

Cloning and Distribution of Facilitative Glucose Transporter 2 (SLC2A2) in Pigs

Zuo, Jianjun,Huang, Zhiyi,Zhi, Aimin,Zou, Shigeng,Zhou, Xiangyan,Dai, Fawen,Ye, Hui,Feng, Dingyuan Asian Australasian Association of Animal Productio 2010 Animal Bioscience Vol.23 No.9

Glucose is the main energy source for mammalian cells and its absorption is co-mediated by two different families of glucose transporters, sodium/glucose co-transporters (SGLTs) and facilitative glucose transporters (GLUTs). Here, we report the cloning and tissue distribution of porcine GLUT2. The GLUT2 was cloned by RACE and its cDNA was 2,051 bp long (GenBank accession no. EF140874). An AAATAA consensus sequence at nucleotide positions 1936-1941 was located upstream of the poly $(A)^+$ tail. Open reading frame analysis suggested that porcine GLUT2 contained 524 amino acids, with molecular weight of 57 kDa. The amino acid sequence of porcine GLUT2 was 87% and 79.4% identical with human and mouse GLUT2, respectively. GLUT2 mRNA was detected at highest level in porcine liver, at moderate levels in the small intestine and kidney, and at low levels in the brain, lung, muscle and heart. In the small intestine, the highest level was in the jejunum. In conclusion, the mRNA expression of GLUT2 was not only differentially regulated by age, but also differentially distributed along the small intestine of piglets, which may be related to availability of different intestinal luminal substrate concentrations resulting from different food sources and digestibility.

Nonlinear wind-induced instability of orthotropic plane membrane structures

Changjiang Liu,Feng Ji,Zhoulian Zheng,Yuyou Wu,Jianjun Guo 한국풍공학회 2017 Wind and Structures, An International Journal (WAS Vol.25 No.5

he nonlinear aerodynamic instability of a tensioned plane orthotropic membrane structure is theoretically investigated in this paper. The interaction governing equation of wind-structure coupling is established by the Von Kármán\'s large amplitude theory and the D\'Alembert\'s principle. The aerodynamic force is determined by the potential flow theory of fluid mechanics and the thin airfoil theory of aerodynamics. Then the interaction governing equation is transformed into a second order nonlinear differential equation with constant coefficients by the Bubnov-Galerkin method. The critical wind velocity is obtained by judging the stability of the second order nonlinear differential equation. From the analysis of examples, we can conclude that it\'s of great significance to consider the orthotropy and geometrical nonlinearity to prevent the aerodynamic instability of plane membrane structures; we should comprehensively consider the effects of various factors on the design of plane membrane structures; and the formula of critical wind velocity obtained in this paper provides a more accurate theoretical solution for the aerodynamic stability of the plane membrane structures than the previous studies.

Physicochemical Characterization and an Injection Formulation Study of Water Insoluble ZCVI4-2, a Novel NO-Donor Anticancer Compound

Yuan Gao,Jianjun Zhang,Li Li,Feng Su,Zhenhua Gong,Yisheng Lai,Yihua Zhang 대한약학회 2012 Archives of Pharmacal Research Vol.35 No.7

ZCVI4-2 was a novel nitric oxide-releasing glycosyl derivative of oleanolic acid that displayed strong cytotoxicity selectively against human hepatocellular carcinoma in vitro and in vivo. In this study, ZCVI4-2 was characterized by FT-IR spectroscopy, differential scanning calorimetry,powder X-ray diffractometry, Raman spectroscopy, hygroscopicity and stability. A high performance liquid chromatography method was also established for the quantitative determination of solubility and additional stability profile of ZCVI4-2. ZCVI4-2 was found to be an amorphous and stable solid with low solubility of less than 10 μg/mL. Based on the solubilization tests that included methods of cosolvency and micellization, the solution mixture of 5% Solutol HS-15, 5% 1, 2-propylene glycol and 5% anhydrous ethanol was determined to be the system for the preparation of the ZCVI4-2 early injection solution. The effect of pH, temperature, light and injectable isotonic glucose or NaCl solution on ZCVI4-2 injection was also investigated. Good stability was observed at all testing conditions. Under the conditions studied, the NO-releasing rate and amount of ZCVI4-2 from the early injection solution in rat plasma demonstrated a promising therapeutic efficacy while maintaining a good safety profile.

In SR-GIXRD Study of Oxide Film Evaluation on AISI 304 Stainless Steel in High Temperature Water

Yan Zhao,Jianjun Guan,Feng Liu,Ping Liang,Congqian Cheng,Jie Zhao 대한금속·재료학회 2019 METALS AND MATERIALS International Vol.25 No.5

Oxide films on AISI 304 stainless steel in high temperature and high pressure water were detected by a new method thatsynchrotron radiation grazing incidence X-ray diffraction. The morphology, phase structure, thickness and electrochemicalcorrosion resistance of the oxide films were illustrated. A empirical equation for oxide growth is applied to evaluate thechanges in film thickness. Observations suggest that small irregular granular (Fe, Cr)2O3 oxides and polyhedral block (Fe,Cr)3O4 oxides are grown on stainless steel surface. The fine inner (Fe, Cr)2O3 particles preferentially form, and the part isprecipitated by the (Fe, Cr)3O4 structure for the diffusion outward, leading to the formation of external coarse grain oxides. The average size of (Fe, Cr)2O3 is slightly oscillated with the oxidation time, and that of (Fe, Cr)3O4 oxides increases withthe increasing exposure time. The oxide film thickness is less than 500 nm for 24 h oxidation in high temperature water, andfor 240 h oxidation the thickness is less than 800 nm. Polarization and EIS test results indicate that the oxide films of (Fe,Cr)2O3 and (Fe, Cr)3O4 provides corrosion resistance for stainless steel.