2 resultados para Central composite design

em Duke University


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For efficient use of metal oxides, such as MnO(2) and RuO(2), in pseudocapacitors and other electrochemical applications, the poor conductivity of the metal oxide is a major problem. To tackle the problem, we have designed a ternary nanocomposite film composed of metal oxide (MnO(2)), carbon nanotube (CNT), and conducting polymer (CP). Each component in the MnO(2)/CNT/CP film provides unique and critical function to achieve optimized electrochemical properties. The electrochemical performance of the film is evaluated by cyclic voltammetry, and constant-current charge/discharge cycling techniques. Specific capacitance (SC) of the ternary composite electrode can reach 427 F/g. Even at high mass loading and high concentration of MnO(2) (60%), the film still showed SC value as high as 200 F/g. The electrode also exhibited excellent charge/discharge rate and good cycling stability, retaining over 99% of its initial charge after 1000 cycles. The results demonstrated that MnO(2) is effectively utilized with assistance of other components (fFWNTs and poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) in the electrode. Such ternary composite is very promising for the next generation high performance electrochemical supercapacitors.

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This paper contributes to the literature in nancial aid and authoritarian institutions.

For a long time, scholars are debating whether nancial aid is able to facilitate

development and governance. Though abundant evidence is provided, the answer is

still inconclusive. On the other hand, scholars investigating China argue that the

leadership uses various institutions to ensure local ocials' compliance. In this paper,

we nd that the nancial aid does not bring a positive impact and the central

government in China does not have enough monitoring capacity to force local o-

cials to comply. We study a redevelopment program established by Chinese central

government after the 2008 Wenchuan earthquake. By adopting a geographic regression

discontinuity combining with a dierence-in-dierences design, we show that

the redevelopment program does not signicantly develop the disaster area. On the

contrary, the evidence implies that the economy in the disaster area is worse after

receiving the aid. The results imply that local ocials do not follow the central government's

regulations and misuse the aid money for other purposes. In the future, we

expect to further investigate through which mechanism do local ocials undermine

the existing institutions.

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