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Exact solutions of the piezoelectric transducer under multi loads
Zhang Taotao,Shi Zhifei 국제구조공학회 2011 Smart Structures and Systems, An International Jou Vol.8 No.4
Under the external shearing stress, the external radial stress and the electric potential simultaneously, the piezoelectric hollow cylinder transducer is studied. With the Airy stress function method, the analytical solutions of this transducer are obtained based on the theory of piezo-elasticity. The solutions are compared with the finite element results of Ansys and a good agreement is found. Inherent properties of this piezoelectric cylinder transducer are presented and discussed. It is very helpful for the design of the bearing controllers.
Zhifei Liu,Liangyi Xue,Weiliang Shen,Jun Ying,Zhenhua Zhang 한국유전학회 2014 Genes & Genomics Vol.36 No.2
Follistatin is a multifunctional regulatory proteininvolved in numerous physiological activities. Tobetter understand its functions in Larimichthys crocea (L.crocea), the entire cDNA sequence of follistatin from L. crocea was cloned, the transcript abundance of follistatinwas measured at different development stages and in differentgender. A fasting-refeeding protocol was also performedto correlate follistatin tissue expression withnutritional status in the juvenile stage of L. crocea. Theresults showed that follistatin transcripts were weaklydetected before gastrula stage (9 h post-fertilization; hpf),and at the highest level at myogenesis stage (15 hpf) and 30days after hatching (30 dah). In adult fish, follistatin transcriptswere observed in all the ten tissues examined andmost abundant in eye, gill, muscle, brain and intestine. Moreover, the abundance of follistatin transcripts in mosttissues was influenced by the age and gender. Duringfasting and refeeding period, the regulatory response offollistatin in muscle, liver, gonad, spleen and brain of L. crocea varied greatly. Altogether, these findings supportthe evidence that follistatin plays a profound role in theteleost development and that it is an indispensable factorfor the survival of teleosts when challenged with environmentalstresses like fasting.
Exact analyses for two kinds of piezoelectric hollow cylinders with graded properties
Zhang, Taotao,Shi, Zhifei Techno-Press 2010 Smart Structures and Systems, An International Jou Vol.6 No.8
Based on the theory of piezo-elasticity, the paper obtains the exact solutions of functionally graded piezoelectric hollow cylinders with different piezoelectric parameter $g_{31}$. Two kinds of piezoelectric hollow cylinders are considered herein. One is a multi-layered cylinder with different parameter $g_{31}$ in different layers; the other is a continuously graded cylinder with arbitrarily variable $g_{31}$. By using the Airy stress function method with plane strain assumptions, the exact solutions of the mechanic and electrical components of both cylinders are obtained when they are subjected to external voltage (actuator) and pressure (sensor), simultaneously. Furthermore, good agreement is achieved between the theoretical and numerical results, and useful conclusions are given.
Exact analyses for two kinds of piezoelectric hollow cylinders with graded properties
Taotao Zhang,Zhifei Shi 국제구조공학회 2010 Smart Structures and Systems, An International Jou Vol.6 No.8
Based on the theory of piezo-elasticity, the paper obtains the exact solutions of functionally graded piezoelectric hollow cylinders with different piezoelectric parameter g31. Two kinds of piezoelectric hollow cylinders are considered herein. One is a multi-layered cylinder with different parameter g31 in different layers; the other is a continuously graded cylinder with arbitrarily variable g31. By using the Airy stress function method with plane strain assumptions, the exact solutions of the mechanic and electrical components of both cylinders are obtained when they are subjected to external voltage (actuator) and pressure (sensor), simultaneously. Furthermore, good agreement is achieved between the theoretical and numerical results, and useful conclusions are given.
Cao Sishi,Zhang Zhifei,Huang Yunwei,Zhang Quanzhou,Xu Zhongming 한국자동차공학회 2021 International journal of automotive technology Vol.22 No.1
In this study, the discrete adjoint approach with the grid deformation technique based on radial basis function was presented to solve the tough problem that the complex shape of the defrosting duct is very difficult to be optimized with multiple parameters in the improvement of the defrosting performance of vehicle. Firstly, the defrosting performance of a light truck was analyzed. Then the discrete adjoint approach was applied by taking the average Nusselt-number as the objective function. The normal surface sensitivity was used in the deformation of the defrosting duct. After 10 optimization cycles, the optimal model was acquired. The results show that, after optimization, the sum of the average Nusselt-number is increased from 3164.16 to 3350.54, which has a positive effect on improving the convection and heat transfer capacity on the windshield effectively. Compared with the initial model, the airflow of the outlet near the windshield is increased from 95.07 g/s to 96.94 g/s, the defrosting time required by the optimal model is reduced by more than 20s. Therefore, the discrete adjoint approach can optimize the complex shape of defrosting duct with multiple parameters effectively, which provides an effective method in the study of automobile defrosting performance.
Liu, Di,Zhang, Ting,Chen, Zhifei,Wang, Ying,Ma, Shuang,Liu, Jiyun,Liu, Jingbo The Korean Society of Ginseng 2017 Journal of Ginseng Research Vol.41 No.2
Background: Ginsenosides are the main pharmacological components of Panax ginseng root, which are thought to be primarily responsible for the suppressing effect on oxidative stress. Methods: 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity and oxygen radical absorption capacity were applied to evaluate the antioxidant activities of the ginsenosides. Human embryonic kidney 293 (HEK-293) cells were incubated with ginsenosides extracted by pulsed electric field (PEF) and solvent cold soak extraction (SCSE) for 24 h and then the injury was induced by $40{\mu}M$ $H_2O_2$. The cell viability and surface morphology of HEK-293 cells were studied using MTS assay and scanning electron microscopy, respectively. Dichloro-dihydro-fluorescein diacetate fluorescent probe assay was used to measure the level of intracellular reactive oxygen species. The intracellular antioxidant activities of ginsenosides were evaluated by cellular antioxidant activity assay in HepG2 cells. Results: The PEF extracts displayed the higher 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity and stronger oxygen radical absorption capacity (with an oxygen radical absorption capacity value of $14.48{\pm}4.04{\mu}M\;TE\;per\;{\mu}g/mL$). The HEK-293 cell model also suggested that the protective effect of PEF extracts was dose-dependently greater than SCSE extracts. Dichloro-dihydro-fluorescein diacetate assay further proved that PEF extracts are more active (8% higher than SCSE extracts) in reducing intracellular reactive oxygen species accumulation. In addition, scanning electron microscopy images showed that the HEK-293 cells, which were treated with PEF extracts, maintained more intact surface morphology. Cellular antioxidant activity values indicated that ginsenosides extracted by PEF had stronger cellular antioxidant activity than SCSE ginsenosides extracts. Conclusion: The present study demonstrated the antioxidative effect of ginsenosides extracted by PEF in vitro. Furthermore, rather than SCSE, PEF may be more useful as an alternative extraction technique for the extraction of ginsenosides with enhanced antioxidant activity.