Electrochemical Synthesis of Mesoporous Architectured Ru Films Using Supramolecular Templates

The electrochemical synthesis of mesoporous ruthenium (Ru) films using sacrificial self‐assembled block polymer micelles templates, and its electrochemical surface oxidation to RuO_x is described. Unlike standard methods such as thermal oxidation, the electrochemical oxidation method described here retains the mesoporous structure. Ru oxide materials serve as high‐performance supercapacitor electrodes due to their excellent pseudocapacitive behavior. The mesoporous architectured film shows superior specific capacitance (467 F g^?1 _Ru) versus a nonporous Ru/RuO_x electrode (28 F g^?1 _Ru) that is prepared via the same method but omitting the pore‐directing polymer. Ultrahigh surface area materials will play an essential role in increasing the capacitance of this class of energy storage devices because the pseudocapacitive redox reaction occurs on the surface of electrodes.     

Epipolar geometry of opti-acoustic stereo imaging

Optical and acoustic cameras are suitable imaging systems to inspect underwater structures, both in regular maintenance and security operations. Despite high resolution, optical systems have limited visibility range when deployed in turbid waters. In contrast, the new generation of high-frequency (MHz) acoustic cameras can provide images with enhanced target details in highly turbid waters, though their range is reduced by one to two orders of magnitude compared to traditional low-/midfrequency (10s-100s KHz) sonar systems. It is conceivable that an effective inspection strategy is the deployment of both optical and acoustic cameras on a submersible platform, to enable target imaging in a range of turbidity conditions. Under this scenario and where visibility allows, registration of the images from both cameras arranged in binocular stereo configuration provides valuable scene information that cannot be readily recovered from each sensor alone. We explore and derive the constraint equations for the epipolar geometry and stereo triangulation in utilizing these two sensing modalities with different projection models. Theoretical results supported by computer simulations show that an opti-acoustic stereo imaging system outperforms a traditional binocular vision with optical cameras, particularly for increasing target distance and (or) turbidity.     

A computational intelligence‐based approach for short‐term traffic flow prediction

This paper proposes alternative approaches for the prediction of short‐term traffic flow using three branches of computational intelligence techniques, namely linear genetic programming (LGP), multilayer perceptron (MLP) and fuzzy logic (FL). Different LGP, MLP and FL models are developed for estimating the 5‐ and 30‐min traffic flow rates. New LGP‐ and MLP‐based prediction equations are derived for the traffic flow rates in the 5‐ and 30‐min time intervals. The models are established upon extensive databases of the traffic flow records obtained from Iran's Rasht‐Qazvin highway. The results indicate that the proposed models are effectively capable of predicting the target values. The LGP‐based models are found to be simple, straightforward and more practical for predictive purposes compared with the other derived models.     

Thermal characteristics of bagasse

Bagasse is a solid waste that remains after crushing sugarcane. Since bagasse is used as a fuel in sugar mills, characterization of its thermal degradation is rather important in order to use it efficiently. Thermal analysis of bagasse was carried out using differential thermal analysis (DTA) and thermogravimetry (TG) under oxidizing and inert atmospheres. Kinetic studies were based on weight loss obtained from TG analysis. Thermal degradation of bagasse takes place in two stages: volatilization and carbonization. The reaction rate, activation energy, entropy change, enthalpy change, and Gibbs free energy for the two thermal stages were calculated. The results indicated that activation energy for the volatilization stage is higher than that of decarbonization stage, and that both the rate constant and activation energy for combustion are higher than those of pyrolysis. © 1996 John Wiley & Sons, Inc.     

Evaluation of isotopic boron (11B) for the fabrication of low activation Mg11B2 superconductor for next generation fusion magnets

In this study, we analyze the properties of boron isotope (¹¹B)-rich powders from three different sources, that is, American, Cambridge, and Pavezyum, to fabricate the bulk Mg¹¹B₂ superconductors and evaluate their superconducting properties. While ¹¹B-rich powder is an essential precursor to fabricate Mg¹¹B₂ superconductors for fusion magnet applications, the properties of the ¹¹B powder turned out to be critical to determine the quality of the final superconducting product. Therefore, appropriate control of processing conditions is needed to comply with the requirements of the nuclear fusion application. Analysis of the B isotope ratio by accelerator mass spectroscopy and neutron transmission revealed that all three types of powder are enriched with ¹¹B to better than 99 at % quality. In addition, Pavezyum's ¹¹B shows the lowest crystallinity and smallest crystalline domain size as evidenced by the high-resolution X-ray diffractometer and scanning electron microscopy. The chemical states of the boron isotope investigated with near edge X-ray absorption fine structure spectroscopy and X-ray photoemission spectroscopy also reveals that Pavezyum boron has amorphous structure. Mg¹¹B₂ bulks and multi-filamentary (12-filament) wires have been manufactured, sintered at different temperatures and characterized via the transport critical current density. The wire with Pavezyum ¹¹B shows three times higher current carrying capacity at a particular magnetic field compared to the wire using Cambridge ¹¹B and hence, Pavezyum ¹¹B boron has the potential for manufacturing fusion grade Mg¹¹B₂ based magnets. The results of this study demonstrated that Boron powders with higher purity, smaller grain size and lower crystallinity are critical for improving the superconducting and electronic properties of Mg¹¹B₂ samples fabricated from the powder. Thus, the low-neutron-activation Mg¹¹B₂ is possibly an affordable and technically viable candidate to replace NbTi superconductors in the low field poloidal field and correction coils for the next-generation fusion reactors.     

Single Crystal Electron Spin Resonance Studies of the Photochemical Reaction Center from Rhodobacter sphaeroides Wild Type Strain 2.4.1

Single crystals were obtained from the photochemical reaction center protein of the photosynthetic bacterium Rhodobacter sphaeroides wild type strain 2.4.1. At low temperatures, the crystals display pronounced anisotropy in their triplet state electron spin resonance (ESR) spectra. An analysis of the angle dependence of the resonance field positions revealed two to four magnetically nonequivalent primary donor molecules per unit cell. This is consistent with the symmetry assignment of P deduced from previous X-ray diffraction studies (Frank, H.A.; Taremi, S.S.; Knox, J.R. J. Mol. Biol., 1987, 198 : 139–141). However, the ESR data could not be fit assuming that the unit cell axes coincide with the crystal morphological axes as was the case previously for Rb. sphaeroides R26 (Gast, P.; Norris, J.R. FEBS Lett., 1984, 177 : 277–280). In order to explain the present data, it was necessary to assume a rhombic crystal cross-section with the unit cell axes lying along the diagonals of the rhombus. The unit cell axes b and c were found to make angles of 60 ± 2° and 30 ± 2°, respectively, with one of the faces of the crystal. The orientation of the triplet state dipolar tensor axes relative to the unit cell axes differs slightly from that in Rb. sphaeroides R26 crystals, suggesting that the Rb. sphaeroides 2.4.1 reaction center is rotated by approximately 7° relative to the orientation found in Rb. sphaeroides R26.     

Critical micelle concentration of non-ionic surfactants by polaro-graphic and spectrophotometric methods-A comparative study

The polarographic micelle point (PMP) values of non-ionic surfactants, viz., Nonidet P40, Nonidet P42 and Nonex 501 have been determined by a polarographic maximum suppression method in the presence of electrolytes (used for polarographic reduction) and compared with the critical micelle concentration (c.m.c.) values of nonionic surfactants obtained by other methods (spectrophotometric and electrocapillary curves methods). The PMP values are always lower than those obtained by other methods. The difference in c.m.c. values is due to the presence of ions of depolarizer and supporting electrolytes. The presence of electrolytes is likely to influence the water structure, thereby causing a lowering in c.m.c. values.     

An econometrics view of worldwide fossil fuel consumption and the role of US

Crude oil, coal and gas, known as fossil fuels, play a crucial role in the global economy. This paper proposes new econometrics modelling to demonstrate the trend of fossil fuels consumption. The main variables affecting consumption trends are: world reserves, the price of fossil fuels, US production and US net imports. All variables have been analysed individually for more than half a century. The research found that while the consumption of fossil fuels worldwide has increased trends in the US production and net imports have been dependent on the type of fossil fuels. Most of the US coal and gas production has been for domestic use, which is why it does not have a strong influence on worldwide fossil fuel prices. Moreover, the reserves of fossil fuels have not shown any diminution during the last couple of decades and predictions that they were about to run out are not substantiated. The nominal and real price of fossil fuels was found to change depending on the type. Finally, estimates of three econometric models for the consumption of fossil fuels from 1949 to 2006 are presented which identify the effects of significant variables.