Identification of plant model of linear induction motors for a traction system intended for use in a high‐performance controller

A linear induction motor (LIM) is suitable for use in trains. The motor can be used in both wheel‐suspended and contact‐less types such as the Linear Metro and HSST trains in Japan. The LIM has end winding as well as asymmetrical winding. The end effect is a major problem in the LIM, and it makes the analysis, design, and control of motors difficult. This paper describes a method that combines numerical analysis and the equivalent circuit for the LIM in order to design a high‐performance controller for the LIM that includes the end effect. A sample basic field‐oriented control scheme that is based on the plant model is applied to the LIM in order to check the control performance. The theory of rotary induction motors is used for verification. © 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 179(2): 44–54, 2012; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21171     

Fabrication of vertically aligned single-walled carbon nanotubes in atmospheric pressure non-thermal plasma CVD

A fabrication technique of high-purity vertically aligned single-walled carbon nanotubes (VA-SWCNTs) using atmospheric pressure plasma enhanced chemical vapor deposition is presented. Although densely mono-dispersed Fe-Co catalysts of a few nanometers is primarily responsible for VA-SWCNT growth, carbon precipitation was virtually absent in the thermal CVD regime at 700 °C. On the other hand, high-purity VA-SWCNTs without measurable defects were grown at 4 μm min⁻¹ by applying atmospheric pressure radio-frequency discharge (APRFD) which has been previously developed for this purpose. The results proved that cathodic ion sheath adjacent to the substrates, where a large potential drop exists, also plays an essential role for the controlled growth of SWCNTs, while ion damage to the VA-SWCNTs is inherently avoided due to high collision frequency among molecules in atmospheric pressure. Operation regime of APRFD and tentative reaction mechanisms for VA-SWCNT growth are discussed along with optical emission spectroscopy of near substrate region.     

Forecasting electric power generation in a photovoltaic power system for an energy network

Recently, there has been an increase in concern about the global environment. Interest is growing in developing an energy network by which new energy systems such as photovoltaic and fuel cells generate power locally and electrical power and heat are controlled with a communication network. We developed the power generation forecast method for photovoltaic power systems in an energy network. The method makes use of weather information and regression analysis. We carried out forecasting power output of the photovoltaic power system installed in Expo 2005, Aichi Japan. As a result of comparing measurements with prediction values, the average prediction error per day was about 26% of the measured power. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 167(4): 16–23, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20755     

Treatment of domestic sewage by a metal membrane bioreactor

A submerged flat metal MBR (membrane bioreactor) was used to treat synthetic domestic sewage in this study. The experiment was continued for 270 days and ran under two modes as AMBR (aerobic membrane bioreactor) and A/O-MBR (anoxic/aerobic membrane bioreactor) at a permeate flux of 0.4-1 m3/(m2 d). PVA (polyvinyl alcohol) gel beads were added to the aeration tank with a volume ratio of 10% at the end of the A/O-MBR mode. The mean COD and TN removal efficiencies achieved 96.69 and 32.12% under the AMBR mode, and those were 92.17 and 72.44% under the A/O-MBR mode, respectively. SND (simultaneous nitrification and denitrification) occurred at high MLSS (mixed liquor suspended solids) concentration. The metal membranes reduced effluent COD during filtration. The system ran stably for 115 days at a permeate flux of 0.8-1 m3/(m2 d) without changing membranes under the AMBR mode, but the membrane filterability decreased gradually under high MLSS or A/O-MBR mode, and the addition of PVA worsened the membrane filterability on the contrary. PSD (particle size distribution) and sludge fractions had evident influence on membrane fouling. The main fouling mechanism was cake formation under the AMBR mode, and that was pore blocking under the A/O-MBR mode.     

Combined electrocoagulation and TiO(2) photoassisted treatment applied to wastewater effluents from pharmaceutical and cosmetic industries

The treated wastewater consists of refractory materials and high organic content of hydrolyzed peptone residues from pharmaceutical factory. The combination of electrocoagulation (EC) followed by heterogeneous photocatalysis (TiO(2)) conditions was maximized. The EC: iron cathode/anode (12.50 cmx2.50 cmx0.10 cm), current density 763Am(-2), 90min and initial pH 6.0. As EC consequence, the majority of the dissolved organic and suspended material was removed (about 91% and 86% of the turbidity and chemical oxygen demand (COD), respectively). After EC, refractory residues still remained in the effluent. The subsequent photocatalysis: UV/TiO(2)/H(2)O(2) (mercury lamps), pH 3.0, 4h irradiation, 0.25gL(-1) TiO(2) and 10mmolL(-1) H(2)O(2) shows high levels of inorganic and organic compounds eliminations. The obtained COD values: 1753mgL(-1) for the sample from the factory, 160mgL(-1) after EC and 50mgL(-1) after EC/photocatalyzed effluents pointed out that the combined treatment stresses this water purification.     

Notch effect on creep–fatigue life for Sn–3.5Ag solder

This paper studies the creep–fatigue crack initiation and failure lives of Sn–3.5Ag solder notched specimens focused on the multiaxial strain at the notch root. Push–pull creep–fatigue tests were performed using three circumferential notched specimens using four kinds of creep–fatigue strain waveforms. Multiaxial strains at the notched section were calculated by finite element (FE) analysis under four kinds of creep–fatigue loading. Creep–fatigue damage laws were applied for evaluating the crack initiation and failure lives using the multiaxial strains obtained by the FE analysis. von Mises equivalent strain at the notch root estimated the crack initiation lives with a large scatter as well as the failure lives. Instead, the mean value of von Mises equivalent strain over the cross section of the notch root estimated the crack initiation and failure lives with a small scatter.     

Restoration of solid oxide fuel cell stacks after failure of partial cells

We investigated a solid oxide fuel cell stack that employs anode-supported planar cells in which two intermediate plates are installed every 10 cells to determine the influence of the separation and reconnection of the intermediate plates after high temperature operation. We showed that this separation and reconnection caused no significant degradation in stack performance. A 30-cell stack, which was constructed by removing two 10-cell sub-stacks from a 50-cell stack that had operated stably 1200 h, functioned well. The difference between the average voltages of the cells in the 50- and 30-cell stacks was less than 3% when the current density, fuel utilization, and oxygen utilization were 0.30 A cm⁻², 60%, and 15%, respectively. The 30-cell stack operated stably for about 1200 h with almost no degradation. These findings indicate that our stack can be restored after cells in the stack have broken down simply by removing the 10-cell sub-stacks that contain the broken cells and replacing them with undamaged 10-cell sub-stacks.     

Synthesis of π-conjugated copolymer with dibenzo[d,d′]benzo[1,2-b:4,5-b′]difuran unit in the main chain

New π-conjugated polymers with dibenzo[d,d′]benzo[1,2-b:4,5-b′]difuran (DBBDF) unit in the main chains were synthesized. Copolymerization of 6,12-diiodo-DBBDF with p-diethynylbenzene or 2,7-diethynylfluorene derivative under Sonogashira–Hagiwara coupling-reaction condition gave the corresponding copolymer. The resulting copolymers were soluble in organic solvents such as tetrahydrofuran and chloroform. In UV–vis absorption spectra, both copolymers showed red-shifted spectra compared to their monomer units. In the chloroform solutions, the copolymer with DBBDF and p-diethynylbenzene units showed yellowish-green emission, while the copolymer with DBBDF and 2,7-diethynylfluorene units did greenish-blue emission.     

Ionic effects on the transport characteristics of nanowire-based FETs in a liquid environment

For the development of ultra-sensitive electrical bio/chemical sensors based on nanowire field effect transistors （FETs）, the influence of the ions in the solution on the electron transport has to be understood. For this purpose we establish a simulation platform for nanowire FETs in the liquid environment by implementing the modified Poisson-Boltzmann model into Landauer transport theory. We investigate the changes of the electric potential and the transport characteristics due to the ions. The reduction of sensitivity of the sensors due to the screening effect from the electrolyte could be successfully reproduced. We also fabricated silicon nanowire Schottky-barrier FETs and our model could capture the observed reduction of the current with increasing ionic concentration. This shows that our simulation platform can be used to interpret ongoing experiments, to design nanowire FETs, and it also gives insight into controversial issues such as whether ions in the buffer solution affect the transport characteristics or not.