Characteristic of an AC chopper circuit with LC filters in the input and output side

LC filters are connected to both the input and output side of the AC chopper circuit in order to remove the switching ripple and harmonics. Characteristics of THD and input power factor are examined by simulation and experiments. When the load is resistive, characteristics are minimally influenced by the filters. In the case of an inductive load, since two poles exist owing to the input and output filters, waveform distortion becomes large. This paper shows that THD can be improved by reducing input filter capacitance. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 155(2): 45–52, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20304     

Acetylation of poly(2-hydroxyethyl acrylate) gel beads obtained from sedimentation polymerization

Sedimentation polymerization of an aqueous 2-hydroxyethyl acrylate solution with some crosslinkers was carried out using a simple sedimentation polymerization apparatus to give millimeter-size and very narrow size distributed poly(2-hydroxyethyl acrylate) (PHEA) gel beads. Also, heterogeneous acetylation of the resulting PHEA gel beads with acylating agents such as acetic anhydride, a mixture of acetic anhydride and pyridine, and chloroacetic anhydride was performed under various conditions. The selective esterification of PHEA gel beads proceeded smoothly in toluene from surface to give a novel core-shell type gel consisting of an unreacted core and acetylated shell, and finally afforded almost quantitatively acetylated PHEA gel. The unreacted core became small while maintaining a spherical shape during reaction. The reaction resembled to that of the corresponding cylindrical PHEA gel, and was strongly affected by the network structure of the obtained PHEA gel beads and the reactivity of acylating agents.     

Implementing Web-Based Project Management Systems in the United States and Japan

This paper reports on results of research conducted at the University of Washington to investigate the means and methods for overcoming barriers to the implementation of Web-based project management systems (WPMS), and to develop a set of best practices in both the United States and Japanese construction industries. The United States and Japanese economies are high-tech intensive and both cultures have embraced technology. However, a relatively small sector of the construction industry in each country has implemented WPMS. The question posed here is why have these drivers not resulted in the industry’s adoption of this new technology, and further, perhaps there are lessons learned from those who have successfully implemented WPMS. This research seeks to broaden our understanding of implementation barriers that are limiting the use of WPMS tools as well as means and methods of overcoming those barriers based on successful implementation in both countries.     

Architecture dependence of thermal fluctuation effects on the order-disorder transition of block copolymer melts

Small-angle X-ray scattering has done to explore the difference in the strength of the thermal fluctuation effects between A-B diblock copolymer and (A/2)₂-B Y-shaped copolymer. SAXS profiles for both systems in their disordered states were analyzed with the Brazovskii-type non-mean field theory by Fredrickson and Helfand. The analyses yielded Ginzburg number characterizing the strength of thermal fluctuation effects. Ginzburg number of Y-shaped copolymer is larger than that of diblock copolymer, suggesting that the strength of the thermal fluctuation effects is affected by the architecture of copolymers.     

Influence of diets enriched with flaxseed oil on the α-linolenic, eicosapentaenoic and docosahexaenoic fatty acid in Nile tilapia (Oreochromis niloticus)

This study examined the effects of different levels of flaxseed oil in increasing the α-linolenic (LNA), eicosapentaenoic (EPA) and docosahexaenoic (DHA) fatty acids contents in tilapias raised in captivity. Nile tilapia were raised in captivity for a period of five months, receiving increasing levels (0%; 1.25%; 2.50%; 3.75% and 5.00%) of flaxseed oil in substitution for sunflower oil (control). No significant differences (P>0.05) of moisture or total lipids contents were found among fillets from tilapia fed the different diets. Analyses of the fatty acid methyl esters (FAMEs) were quantitatively measured by capillary gas chromatography against a C_23:0 internal standard. Increases of the concentration of LNA, EPA and DHA (in mg/g of total lipids), were well established in the fillets, with a significant difference (P<0.05) among all the treatments, as the replacement of the sunflower oil by flaxseed oil was increased.     

Extraction of the Mayer wave component in blood pressure from the instantaneous phase difference between electrocardiograms and photoplethysmograms

To analyze the human baroreflex function noninvasively, a beat-by-beat blood pressure signal is often measured by tonometry or plethysmogram using continuous blood pressure sensors. However, these sensors are too expensive and bulky to be used for home healthcare or telemedicine. On the other hand, it is well known that the pulse transmission time (PTT) is strongly correlated with the beat-by-beat blood pressure, especially in the Mayer wave-related frequency band (0.05–0.15 Hz). To obtain a new physiological parameter with a higher correlation with blood pressure in this band compared with that obtained using the PTT alone, we proposed the samephase temporal difference (SPTD) based on electrocardiogram and photoplethysmogram signals. By examining 94 healthy subjects using a combination of SPTD and conventional PTT, it was revealed that the correlation with blood pressure for 25 subjects could be improved using the SPTD instead of the PTT, by applying the criterion of the ratio of their powers. However, for 7 subjects, the correlation decreased.     

Real‐time compensation for positioning performance using on‐line parameter identification and initial value compensation

Variations and/or uncertainties in environments of mechatronic systems, such as electrical/mechanical parameter changes and nonlinear components, generally deteriorate the motion control performance. In our research, the fast and precise position settling performance for parameter variations in positioning devices can be improved by techniques of an on‐line parameter identification and an initial value compensation. The proposed technique allows the positioning systems to be adaptive and robust for unknown parameter variations. The effectiveness of the approach has been verified by numerical simulations and experiments using a prototype. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 171(2): 40–49, 2010; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20926     

Dry etching properties of methyl-BCN film with C4F8 gas for Cu/low-k interconnection

Methyl-BCN is an attractive low-k material for the fabrication of next generation LSI device system. This paper describes dry etching of methyl-BCN film in order to develop interconnections for future devices. The methyl-BCN films were deposited by plasma-assisted chemical-vapor deposition (PACVD) using tris(dimethylamino)boron (TMAB) gas at 350 °C. We have investigated dry etching properties and mechanism of the methyl-BCN film using C₄F₈ gas with induced coupling plasma (ICP) etching equipment. In this study we used C₄F₈ gas whose atmospheric lifetime is less than one-sixteenth of the conventional CF₄ gas for suppression greenhouse gases. It was found that methyl bonds in the methyl-BCN film can be kept after dry etching, because the peak of C–H (2962 cm^?1) in Fourier transform infrared absorption (FTIR) spectra didn't significantly change after dry etching. X-ray photoelectron spectroscopy (XPS) analysis shows the presence of C–F₂ and C–F₃ bonds just on the methyl-BCN surface after dry etching and no traces of these bonds inside the film. It is observed that intensities of B–N and B–C bonds decrease after dry etching. This suggests that the etching of methyl-BCN films by C₄F₈ gas mainly involves boron desorption.     

Photoinduced surface crosslinking of superabsorbent polymer particles

Superabsorbent polymer particles, consisting of partly neutralized, slightly crosslinked poly(acrylic acid), have been surface‐crosslinked photochemically. Surface crosslinking is required for many applications of superabsorbent polymers, such as disposable diapers, to control the flow and absorption of liquids in the gel bed. Photoinduced surface crosslinking has been achieved under UV irradiation (200–300 nm) with (NH₄)₂S₂O₈ as a photoactivated crosslinking agent. In comparison with the currently used thermal ester bridging method for surface crosslinking, the new photochemical method generates superabsorbent particles with superior properties, such as an improved flow of liquid through the gel bed, which utilizes the entire gel bed. These improved properties have been shown by water absorption capacity studies, fluid flow dynamics, environmental scanning electron microscopy, and low‐energy ion‐scattering studies. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009