Removal of Cr(VI) from aqueous solution by London plane leaves

The effect of initial metal concentration, contact time and solution temperature on the removal of Cr(VI) from solution by waste London plane leaves, generated by the pruning of street trees, was investigated in batch mode conditions. The removal of Cr(VI) was highly concentration‐dependent and mainly governed by physico‐chemical adsorption under the weak acidic conditions studied. The equilibrium data fit well in the Langmuir isotherm model. The Langmuir constants were calculated at different temperatures and both the adsorption capacity and adsorption intensity increased with rising temperature. The endothermic nature of the Cr(VI) adsorption was confirmed by the thermodynamic parameters. The study has shown that the waste leaves can be used as an effective adsorbent for removal of Cr(VI) from wastewater. Copyright © 2003 Society of Chemical Industry     

Cutting plane methods for Lagrangian relaxation‐based unit commitment algorithm

In this paper, we study cutting plane methods for a Lagrangian relaxation‐based unit commitment algorithm. In the algorithm, nondifferentiable optimization methods can be applied to optimize the dual function, and a subgradient method which needs parameter tuning and has some drawbacks such as computational inefficiency and oscillating behavior is commonly used. The cutting plane method and the central cutting plane method are applied to the algorithm and implemented using reoptimization techniques. A numerical example shows that both methods are accelerated by the reoptimization techniques and have good convergence without parameter tuning. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 141(3): 17–29, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10066     

Electrostatic Field Variation in the Atmosphere Induced by Earth Potential Difference Variation During Seismic Wave Propagation

To clarify the relationship between earthquakes and electrical phenomena, signals of three parameters were observed continuously at Sennan in Akita Prefecture, Japan: ground acceleration (GAC), earth potential difference (EPD), and electrostatic field in the atmosphere (EFA). A large metal plate was used as an electrostatic antenna to observe EFA variation. For this paper, we used the digital natural observation (D-NOB) method as a signal processing technique and found clear EPD and EFA waveforms during seismic wave propagation. Our observation and examination results show that GAC causes EPD variation. Subsequently, the EPD variation induces EFA variation     

Reduction of gaseous contamination by UV/photoelectron method

We have previously reported that UV/photoelectron method, in which particles are charged by photoelectrons emitted from the UV irradiated metal surface and collected on the electrodes by the electric field, is effective to collect particles in the gas phase. This paper represents that the UV/photoelectron method is effective not only to collect particles but also to reduce the gaseous contamination such as hydrocarbon or organic compounds and water molecules. By using the UV/photoelectron method the carbon atom concentration on the Si surface is reduced to 1/4 compared with that stored in the clean room for the storage period of about 40 h. The oxygen concentration is reduced to 1/7 in the same condition     

Advanced evaluation of thermal ratchetting of FBR components

A new prediction method for the thermal ratchetting of a cylinder subjected to an axially moving temperature distribution is proposed in this paper. This ratchetting is quite different from the conventional Bree-type ratchetting, and an advanced evaluation method has been required in the structural design of FBR components. The proposed method considers the work hardening of actual materials for FBR components. Firstly the basic scheme of the prediction method is shown, and secondly the application procedure to the actual design is shown. Predicted results by using this method coincide well with experimental results, when compared with the case by using the previous method.     

DAD: a real-time expert system for monitoring of data packetnetworks

A project is described that has two goals: to explore the use of expert systems techniques for developing advanced operation support systems and to build a useful tool to assist the operators of the Canadian National Datapac network to cope with the rapid growth and evolution. Progress in developing and evaluating an advanced prototype system, DAD (Datapac Advisor), is reported. The prototype's environment and each of its functional components are described. The knowledge based design techniques used are highlighted, and the testing methodology and the results of a technical trial are described. Key findings are summarized, and their significance for the development of future network operation support systems is discussed     

Estimation method of frequency bias using normal operating data

A technique of calculating the frequency bias of an electric power system from frequency fluctuation data and total output power is described. An evaluation method for testing the calculations by the new method is developed. The results are in good agreement with estimates based on generator speed regulation but the method gives an excessively high figure for the load frequency bias.     

Application of Highly Functional Ti-Oxide-Based Photocatalysts in Clean Technologies

Various Ti-oxide based photocatalysts such as the highly dispersed Ti-oxide species within zeolite frameworks, TiO₂ nano-particles hybridized with hydrophobic zeolite adsorbents as well as visible light responsive TiO₂ thin films have been successfully prepared. Characterization studies at the molecular level, such as X-ray absorption fine structure (XAFS) and photoluminescence (PL), revealed that the highly dispersed Ti-oxide species within the nano-spaces of zeolites possess a tetrahedral coordination and that they demonstrate unique and high performance for the photocatalytic decomposition of NOx and the photocatalytic reduction of CO₂ with H₂O. A high photocatalytic reactivity for the TiO₂ semiconducting photocatalysts could be achieved by blending them with hydrophobic siliceous zeolites which was equal to the performance of TiO₂ deposited with expensive Pt particles. The role of the siliceous zeolites can be described as a so-called “catch and release effect of organic compounds”, i.e., (i) the condensation of the reactants within the hydrophobic cavities of zeolites and; (ii) the efficient diffusion of the reactant onto the TiO₂ photocatalytic sites. Furthermore, a novel photocatalytic system which can convert abundant solar energy into renewable H₂ energy by the decomposition of H₂O into H₂ and O₂ can also be achieved by using visible light responsive TiO₂ thin film photocatalysts prepared by a RF-magnetron sputtering deposition method. The conversion efficiency of solar energy into H₂ energy may be estimated at ca. 0.1% from the initial rate of H₂ evolution.     

Morphologic Control of Pt Supported Titanate Nanotubes and Their Photocatalytic Property

Morphologic control of Pt supported titanate nanotubes was attempted by the hydrothermal hot-pressing (HHP) technique in order to improve the handleability as a photocatalyst. The bulk of Pt-nanocrystal supported titanate nanotubes was successfully fabricated without the H₂ reduction process by applying the HHP technique. The bulky Pt-nanocrystal supported titanate nanotubes possessed dense microstructures, significantly sharp distributions of mesopores, and high Brunauer–Emmett–Teller (BET) surface area. Furthermore, the bulky Pt-nanocrystal supported titanate nanotubes showed the photocatalytic degradation activities of 2-propanol aqueous solution under UV-light irradiation.