This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. AbstractA simple method based on potentiostatic polymerization was developed for the preparation of ternary manganese oxide-based nanocomposite films. The ternary nanocomposites, which were characterized using x-ray diffraction spectroscopy and x-ray photoelectron spectroscopy, showed that the manganese oxide within the film consisted of MnO 2 and Mn 2 O 3 . Electrochemical measurements showed that the ternary nanocomposite electrode exhibited high specific capacitance (up to 320.6 F/g), which was attributed to the morphology of a polypyrrole/graphene/manganese-oxide (PPy/GR/MnO x ) ternary nanocomposite. The experimental approach maximized the pseudocapacitive contribution from redox-active manganese oxide (MnO x ) and polypyrrole (PPy), as well as the electrochemical double layer capacitive (EDLC) characteristic from graphene (GR) sheets. Long cyclic measurements indicated that the specific capacitance of the ternary nanocomposite film could retain 93% of its initial value over 1,000 charge/discharge cycles, in the potential range of -0.2 to 0.7 V vs. silver/silver chloride electrode (Ag/AgCl).

A one-step electrochemical process had been employed to synthesize nanocomposite films of polypyrrole/graphene (PPy/GR) by electrochemical polymerisation on indium tin oxide (ITO) from an aqueous solution containing pyrrole monomer, graphene oxide (GO) nanosheets and sodium p-toluenesulfonate (NapTS). The X-ray diffraction (XRD) patterns showed that the typical peak of GO at 9.9o was missing from the nanocomposite's diffraction pattern, suggesting that the GO had been stripped off of its oxygenous groups after the reaction. We postulated that a nanocomposite film was produced through a layer-by-layer deposition based on field emission scanning electron microscope (FESEM) images. The Raman spectroscopy profiles exhibited that the D/G intensity ratio (ID/IG) of PPy was not altered by the inclusion of GO due to the low concentration of the material used. However, the concentration was sufficient to increase the specific capacitance of the nanocomposite by 20 times compared to that of pure PPy, reflecting a synergistic effect between PPy and GR, as analysed by a threeelectrode electrochemical cell. The electrochemical performance of the nanocomposites was affected by varying the deposition parameters such as concentrations of pyrrole and GO, scan rate, deposition time and deposition potential.

This paper reports a rapid and in-situ electrochemical polymerization method for the fabrication of polypyrrole nanoparticles incorporated reduced graphene oxide (rGO@PPy) nanocomposites on a ITO conducting glass and its application as a counter electrode for platinum-free dye-sensitized solar cell (DSSC). The scanning electron microscopic images show the uniform distribution of PPy nanoparticles with diameter ranges between 20 and 30 nm on the rGO sheets. The electrochemical studies reveal that the rGO@PPy has smaller charge transfer resistance and similar electrocatalytic activity as that of the standard Pt counter electrode for the I3−/I− redox reaction. The overall solar to electrical energy conversion efficiency of the DSSC with the rGO@PPy counter electrode is 2.21%, which is merely equal to the efficiency of DSSC with sputtered Pt counter electrode (2.19%). The excellent photovoltaic performance, rapid and simple fabrication method and low-cost of the rGO@PPy can be potentially exploited as a alternative counter electrode to the expensive Pt in DSSCs.

SUMMARYA flexible polypyrrole/graphene oxide/manganese oxide-based supercapacitor was prepared via an electrodeposition process. The polypyrrole, graphene oxide, and manganese oxide were deposited onto a flexible and highly porous nickel foam, which acted as a current collector to enhance the electrochemical performances. The good coverage of the polypyrrole, graphene oxide, and manganese oxide onto the scaffold of the nickel foam was evidenced using field emission scanning electron microscopy and X-ray diffraction. The manganese species, which were present in the oxidation states of Mn 3+ and Mn 4+ , were shown using X-ray photoelectron spectroscopy. The presence of Mn 2 O 3 and MnO 2 polymorphs was detected using Fourier transform infrared and Raman spectroscopies. The cyclic stability of the ternary supercapacitor was consistent regardless of its geometry and curvature. In contrast, an activated carbon supercapacitor possesses limited energy storage capability compared to a ternary supercapacitor, which suppresses the electrochemical performances of activated carbon. The ternary as-fabricated supercapacitor could retain a specific capacitance of 96.58% after 1000 cycles, and the as-synthesized energy storage device was able to light up a light emitting diode.

No abstract

A one-step electrochemical process has been employed to synthesize composite films of polypyrrole/graphene (PPy/ GR) by electrochemical polymerization on indium tin oxide (ITO) from an aqueous solution containing pyrrole monomer, graphene oxide (GO) nanosheets and sodium p-toluenesulfonate (NapTS). Thermogravimetric analysis (TGA) confirmed the formation of a composite; the degradation temperature of the new hybrid was between those of PPy and GO. Moreover, the bulbous surface of PPy and the almost transparent tissue-like GO nanosheets were replaced by the new appearance of the composite where the surface was flat but creased. As GO is nonconductive, we deduced that it had been reduced to conducting graphene in the composite film during the electrodeposition process, based on an electrical conductivity study measured with a four-point probe. On average, the electrical conductivity of the PPy/GR composites was twofold higher than that of the pure PPy film, indicating that the incorporation of graphene was able to enhance the conductivity of PPy film.

In South Korea, use of the smart card to pay public transit fares has grown since its introduction in 1996. The proportion of smart card use in Seoul, South Korea, is more than 90% for buses and 75% for Metro. In 2004, the Seoul metropolitan government introduced a new smart card system that has a distance-based fare system, which requires the input of detailed user data, such as boarding time and Global Positioning System–based vehicle location. To investigate the reliability of smart card data, the number of users of every Metro station in Seoul, gathered from smart card data, was directly compared with data obtained from the Seoul Metro Company. By using two simple manipulations to include daily variations and the number of cash users, smart card data appear to be statistically similar to the surveyed data obtained from the Seoul Metro Company. By analyzing the line-specific proportions of smart card use rather than the average smart card use, the accuracy of the results is improved. From the results, it can be seen that smart card data show potential as a basis for describing the characteristics of public transit users, such as the number of transfers, boarding time, hourly trip distribution of the number of trips for different transit modes, and travel time distribution for all transit modes and user types.

Several approaches have been developed to cope with the limits of conventional origin-destination (O-D) trip matrix collecting methods. One is the bilevel programming method, which uses a sensitivity analysis-based (SAB) algorithm to solve a generalized least-squares problem. However, the SAB algorithm has revealed a critical shortcoming when there is a significant difference between the target O-D matrix and the true O-D matrix. This problem stems from the heavy dependence of the SAB algorithm on historical O-D information. Such dependence may lead to a state in which the O-D estimator cannot produce a correct solution, especially when travel patterns are dramatically changed. To avoid the problem of dependency, a robust and stable method is required. A solution method is developed with a genetic algorithm, which is widely used in optimization problems to obtain a global solution. From the results of numerical examples, the proposed algorithm is superior to the SAB algorithm regardless of travel patterns.