Perpendicular oriented cylinders via directional coalescence of spheres embedded in block copolymer films induced by solvent annealing

Polystyrene-b-poly(methyl acrylate) (PS-b-PMA) block copolymer with PS volume fraction of 25.2 vol% was synthesized by atom transfer radical polymerization. Non-pretreated silicon wafers were used as the substrates to prepare perpendicular oriented PS cylinders in PMA matrix via solvent annealing which could induce the transformation of spheres to vertically oriented and hexagonally packed cylinders. The spherical microdomains were formed after the evaporation of solvents from the solutions of the block copolymer in selective solvents mixed from methanol, acetone and dichloromethane. The thickness of films could be as thick as 1000 nm, which were much thicker than usual cases and the cylinders came from the directional coalescence of the spheres, thus any pre-treatments of the substrates were not required for perpendicular orientation. The structures were characterized by small angle X-ray scattering (SAXS), transmission electron microscope (TEM), atom force microscopy (AFM) and grazing incidence small angle X-ray scattering (GISAXS).     

Anti‐windup synthesis for a model predictive control system

In this paper, an anti‐windup design problem for a model predictive control system is studied. The plant is assumed to be stable. First, we propose the structure of an output feedback model predictive controller with an anti‐windup compensator. Then we show a design method of the anti‐windup compensator that guarantees closed‐loop stability and improves the transient response. The design problem of the anti‐windup compensator is reduced to a linear matrix inequality (LMI) optimization problem. Further, it is shown that there always exists an anti‐windup compensator that ensures global asymptotic stability. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Analysis of spatial smoothing effect of short‐term fluctuation of global solar radiation based on data including quantization error

Photovoltaic (PV) systems are attracting attention as one of the promising countermeasures against global warming and the environmental issues. However, the generation output from PV systems is generally unstable and unpredictable. Therefore, large penetration of PV systems may cause some serious impacts on power system operation, such as load frequency control, voltage regulation, etc. Estimation of the influences of PV system installation is becoming important, but it requires simultaneous multipoint solar radiation measurements. The Japan Meteorological Business Support Center has provided 1‐minute meteorological data observed in Japan, but its solar radiation data includes quantization errors. This paper proposes a regeneration method for solar radiation data including quantization errors. It also analyzes the spatial smoothing effect of global solar radiation fluctuations. © 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 180(3): 55–63, 2012; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21274     

Seismic soil–structure interaction analysis of wind turbines in frequency domain

In this paper, the seismic behavior of wind turbines sitting on a finite flexible soil layer is investigated in three‐dimensional space. A numerical algorithm formulated in frequency domain is proposed in order to simulate the dynamic soil–structure interaction (SSI). The wind turbine is discretized using finite element method (FEM) while, the underlying soil is represented by complex dynamic stiffness functions based on cone models. A parametric study consisting of 24 ground motions and three soil profiles is carried out, and different response quantities of the wind tower model are calculated and presented in the paper. The free‐field ground motions are estimated based on an equivalent linear approach using SHAKE2000 computer software. Transfer functions for total acceleration of the wind tower are obtained under the considered soil profiles and the modal frequencies of the coupled wind turbine–soil foundation are estimated. It is shown that the response quantities such as displacement, rotation, acceleration, base shear and moment are significantly affected by SSI, although the effect of SSI on the fundamental frequencies of the wind tower is insignificant. The moment and shear force distribution along the height of the tower is highly influenced as the soil stiffness decreases. The change in seismic demand distribution along the tower height because of SSI is not addressed by simplified design approached and should be carefully considered in seismic design of wind towers. Copyright © 2016 John Wiley & Sons, Ltd.     

Effect of chloride ions on leaching rate of chalcopyrite

The effect of chloride on chalcopyrite leaching has been investigated by performing batch leaching tests with three kinds of leaching solutions and using Hiroyoshi’s model, which suggests that a zone of rapid leaching exists between the critical potential (E_c, equilibrium redox potential for the reduction of CuFeS₂ to Cu₂S) and the oxidation potential (E_ox, equilibrium redox potential for the oxidation of Cu₂S). The results of the leaching tests show that the leaching rate in hydrochloric acid solution is the fastest and that the relationship between the Cu leaching rate and oxidation–reduction potential (ORP) follows Hiroyoshi’s model. Thermodynamic calculations indicate that, with an increase in the chloride concentration, the concentration of cuprous ions increases as the chlorocuprate(I) complex ions are formed and the contribution of cuprous ions to the critical potential is greater than that of cupric ions, even though the concentration of cuprous ions is lower than that of cupric ions. This fact suggests that the formation of chlorocuprate(I) ions in a chloride solution may improve the chalcopyrite leaching rate by increasing the critical potential.     

Coprecipitation of Cefuroxime Axetil-PVP composite microparticles by batch supercritical antisolvent process

Batch supercritical antisolvent precipitation (SAS) process was used to coprecipitate Cefuroxime Axetil amorphous (CFA, antibiotic) and Polyvinylpyrrolidone (PVP-K30) for preparing drug-polymer composite particles. Solutions of CFA and PVP-K30 in methanol with overall concentrations of 50-150 mg/ml and polymer/drug ratios of 1/1-4/1 were sprayed into the CO₂ at 70-200 bar and 35-50 °C with drug + polymer solution injection rates of 0.85 and 2.5 ml/min. Spherical particles having mean diameters of 1.88-3.97 μm, distribution ranges of 0.82-9.7 μm (the narrowest distribution) and 0.91-46.64 μm (the broadest distribution) were obtained. Mean particle size was not affected significantly with the change of process parameters. It was only affected by pressure change. On the other hand particle size distribution was affected by pressure, temperature, drug + polymer solution injection rate and concentration. It was observed that temperature and polymer/drug ratio affected the particle morphology most. The drug release rate of SAS-coprecipitated CFA-PVP (1/1) particles was almost 10 times slower than the drug alone. As the ratio of the polymer increased drug release rate also increased due to the wetting effect of PVP.     

Influence of wood species on the properties of biopolyurethane prepared from liquefied wood with residue

Biopolyurethane prepared from liquefied wood with the residue of the liquefied wood product was investigated in this article. Previous results indicated that the residue of the liquefaction product was composed mostly of compounds originated from lignin. The chemical structures of lignin in softwood and hardwood are different. The influence of soft‐ and hardwood species on the chemical structure and mechanical properties of biopolyurethane prepared from liquefied wood with residue was investigated by tensile testing and Fourier transform infrared spectroscopy. The experimental results showed that the liquefaction of softwood occurs within a shorter time than that of hardwood and the biopolyurethane prepared from softwood was harder than that prepared from hardwood, which suggests that the properties of the liquefaction product and biopolyurethane are influenced by the chemical structure of the lignin. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Design of stabilized laser for optically pumped atomic frequency standards

The influence of a stabilized laser's fluctuations in an optically pumped atomic frequency standard is considered. It is important to use a laser with narrow linewidth and select the modulation frequency where the laser's free‐running frequency fluctuation at twice the modulation frequency is the lowest. Employing these considerations, the stabilized laser for our optically pumped cesium beam frequency standard is designed. © 2001 Scripta Technica, Electr Eng Jpn, 136(2): 31–37, 2001