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Chaotic dynamic characteristics of pressure fluctuation signals in hydro-turbine
Wen-Tao Su,Xiao-Bin Li,Chao-Feng Lan,Shi An,Jiansheng Wang,Feng-Chen Li 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.11
The pressure fluctuation characteristics in a Francis hydro-turbine running at partial flow conditions were studied based on the chaotic dynamic methods. Firstly, the experimental data of pressure fluctuations in the draft tube at various flow conditions was de-noised using lifting wavelet transformation, then, for the de-noised signals, their spectrum distribution on the frequency domain, the energy variation and the energy partition accounting for the total energy was calculated. Hereby, for the flow conditions ranging from no cavitation to severe cavitation, the chaos dynamic features of fluctuation signals were analyzed, including the temporal-frequency distribution, phase trajectory, Lyapunov exponent and Poincaré map etc. It is revealed that, the main energy of pressure fluctuations in the draft tube locates at low-frequency region. As the cavitation grows, the amplitude of power spectrum at frequency domain becomes larger. For all the flow conditions, all the maximal Lyapunov exponents are larger than zero, and they increase with the cavitation level. Therefore, it is believed that there indeed exist the chaotic attractors in the pressure fluctuation signals for a hydro-turbine.
The simple and easy way to manufacture counter electrode for dye-sensitized solar cells
Jo-Lin Lan,Yung-Yun Wang,Chi-Chao Wan,Tzu-Chien Wei,Hsien-Ping Feng,Chao Peng,Hai-Peng Cheng,Ya-Huei Chang,Wen-Chi Hsu 한국물리학회 2010 Current Applied Physics Vol.10 No.2
We previously developed poly-N-vinyl-2-pyrrolidone (PVP)-capped Pt nanoclusters on ITO glass via a simple ‘‘2-step dip coating process” as counter electrode for DSSC. This new counter electrode was examined by transmission electron microscopy (TEM), inductively coupled plasma-atomic emission spectroscopy (ICP-AES), electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and current–voltage curve (I–V curve). The TEM results revealed that PVP-capped Pt nanoclusters’ size is about 3 nm, and the amount of Pt deposited on ITO glass is about 5 ㎍/㎠. Comparing with sputtered Pt and Solaronix thermal cluster Pt-catalyst T/SP, the PVP-capped Pt counter electrode has lower amount of Pt deposited on TCO glass,more positive potential of tri-iodide reduction, and better performance for the charge-transfer resistance (RCT) and the cell efficiency (g).
Overexpression of the AtSTK Gene Increases Salt, PEG and ABA Tolerance in Arabidopsis
Lei Bing,Cui-Cui Feng,Jing-Lan Li,Xiao-Xu Li,Baocun Zhao,Yin-Zhu Shen,Zhan-Jing Huang,Rong-Chao Ge 한국식물학회 2013 Journal of Plant Biology Vol.56 No.6
AtSTK (At5g02800), which is a serine-threonineprotein kinase gene of Arabidopsis thaliana, was cloned, andits function was studied. The study found that the overexpressionof AtSTK could significantly improve the ability of A. thaliana to tolerate salt, PEG, and ABA stresses. RT-PCRanalysis revealed that the expression of the AtSTK genecould be obviously induced by salt, PEG, and ABA. Theexamination of the physiological characteristics showed thatthe overexpression of AtSTK in Arabidopsis significantlyreduced the plasma membrane permeability, significantlyincreased the proline content, and decreased the MDA content. These changes may reflect the physiological mechanismsthrough which AtSTK overexpression improves stress resistancein Arabidopsis. In addition, the overexpression of the AtSTKgene significantly antagonised the inhibitory effect of highconcentrations of exogenous ABA on Arabidopsis seedgermination. The subcellular localisation results showed thatAtSTK is located in both the cytosol and the nucleus. Theexamination of its tissue-specific expression showed thatAtSTK is expressed in various Arabidopsis tissues and isparticularly strongly expressed in the vessels. The signallingpathway analysis indicated that AtSTK might transfer thesalt stress signal in Arabidopsis through the MAPK pathway.