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Little Rock, AR, United States

Gelisli K.,Karadeniz Technical University | Seren A.,Karadeniz Technical University | Babacan A.E.,Karadeniz Technical University | Catakli A.,2801 iversity Avenue | And 2 more authors.
Bulletin of Engineering Geology and the Environment | Year: 2011

In 2001, rock falls occurred on the southern slope of the Sumela Monastery, which was built on a cliff in Trabzon, north east Turkey, and is visited by many tourists. Considering the steepness of the slope and difficulty of access, rock classifications were made based on seismic wave velocity, rock mass quality (Q), rock quality designation (RQD) and rock mass rating (RMR). The results indicated extremely poor to very poor rock in the cracked, fractured and weathered parts and poor to fair rock in the intact parts of the monastery slope. As a consequence, rock fall, slide and rolling may occur from time to time. These constitute a hazard to the facilities of the monastery and access paths. It is recommended that cracked areas are strengthened with cement-based materials, that accumulated rocks are removed, and that retaining walls are constructed on solid rock around the unstable rock blocks. © 2010 Springer-Verlag.

Abdulrazzaq O.,2801 iversity Avenue | Bourdo S.E.,2801 iversity Avenue | Woo M.,2801 iversity Avenue | Saini V.,2801 iversity Avenue | And 3 more authors.
ACS Applied Materials and Interfaces | Year: 2015

The aging effect on P3HT:PCBM organic solar cells was investigated with camphorsulfonic doped polyaniline (PANI:CSA) or poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) used as the hole transport layer (HTL). The cells were encapsulated and exposed to a continuous normal atmosphere on a dark shelf and then characterized intermittently for more than two years. The photovoltaic results revealed that the cells with PEDOT:PSS HTL showed better initial results than the cells with PANI:CSA HTL. Over time, PEDOT:PSS-based cells exhibited faster degradation than PANI:CSA-based cells, where the average efficiency of six cells dropped to zero in less than one and a half years. On the other hand, PANI:CSA-based cells exhibited a much more stable performance with an average efficiency drop of only 15% of their initial values after one and a half years and 63% after two years. A single-diode model was utilized to fit the experimental data with the theoretical curve to extract the diode parameters, such as the ideality factor, to explain the effect of aging on the diode's performance. © 2015 American Chemical Society.

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