A method of determining the advanced angle of square-wave currentsin a bearingless switched reluctance motor

Bearingless switched reluctance motors, which can control rotor radial positions with magnetic force, have been proposed. These motors have combined the characteristics of switched reluctance motors and magnetic bearings. This paper proposes a method of determining the advanced angle of square-wave currents in a bearingless switched reluctance motor. Under any torque condition, from no load to full load, stable operation is realized by controlling the advanced angle of square-wave currents with the proposed method. It is shown experimentally that the proposed method is effective in realizing stable operation     

Quantitative analysis of collaborative and mobility networks

This study proposes a quantitative analysis of researcher mobility (i.e. transfer from one institution to another) and collaborative networks on the basis of author background data extracted from biographical notes in scientific articles to identify connections that are not revealed via simple co-authorship analysis. Using a top-ranked journal in the field of computer vision, we create a layered network that describes various aspects of author backgrounds, demonstrating a geographical distribution of institutions. We classify networks according to various dimensions including authors, institutions and countries. The results of the quantitative analysis indicate that mobility networks extend beyond the typical collaborative networks describing institutional and international relationships. We also discuss sectoral collaboration considering the mobility networks. Our findings indicate a limitation of collaborative analysis based on bibliometric data and the importance of tracing researcher mobility within potential networks to identify the true nature of scientific collaboration.     

Miscibility Between Ethylene Vinyl Acetate Copolymers and Tackifier Resins

A series of ethylene vinyl acetate copolymer (EVA) were blended with various kinds of tackifiers and the miscibility between the components was investigated. The miscibility of the blend is illustrated as a phase diagram. The EVA and modified rosin systems tended to have a phase diagram with lower critical solution temperature (LCST), whereas the EVA and petroleum resin systems tended to have that with upper critical solution temperature (UCST). The phase diagrams of EVA/tackifier resins systematically changed as VAc content in the copolymer increased, which is accounted for by the classical Flory-Huggins theory.     

Effect of different copper fillers on the electrical resistivity of conductive adhesives

The effects of different copper fillers with different morphology and particle size have been studied in terms of electrical resistivity and thermal stability on the electrically conductive adhesives. The copper fillers used in this study were prepared by wet chemical reduction, electrolytic and gas atomization method, respectively. The as cured ECAs filled with different type of Cu fillers showed significant difference in electrical resistivity. Cu filler with smaller particle size showed higher packing density and larger surface area, which would enhance formation of conductive channels and increased conductive network in the ECAs, leading to a lower electrical resistivity. In addition, thermal stability of the ECAs were investigated under high temperature exposure at 125 °C and high humidity aging at 85 °C/85% RH for 1,000 h. Results showed that ECAs with Cu fillers of relatively small particle size and rough particle surface have excellent thermal stability due to enhanced adhesion and contact area between Cu fillers and the polymer matrix. A very low resistivity at an order of magnitude of 10^?4 ?? cm could be maintained for these ECAs after 1,000 h at 125 and 85 °C/85% RH.     

Ultrasonic-Assisted Soldering of 5056 Aluminum Alloy Using Quasi-Melting Zn-Sn Alloy

To obtain sound butt-joints of 5056 aluminum alloy rods, ultrasonic-assisted soldering was conducted using Zn-18Sn and Zn-60Sn alloys. Each solder foil was inserted between rods of 5056 aluminum alloy. Ultrasonic vibration was propagated to faying surfaces at soldering temperatures below the liquidus temperature of the solder alloys, and then the samples were air cooled to room temperature. The optimum vibration time at the soldering temperature must be more than 2 seconds to have complete wetting and less than 4 seconds to avoid excessive dissolution of the 5056 alloy. The 5056 alloy joints soldered using quasi-melting. Zn-Sn alloys showed greater strength than the joints soldered at the temperatures over its respective liquidus temperature. As the soldering temperature was increased, the increased formation of the intermetallic compound Mg₂Sn or phases containing Mg generated by dissolution of 5056 into the solder layer decreased the joint strength. Ultrasonic-assisted soldering at an optimum temperature between solidus and liquidus of the Zn-Sn alloys is an important consideration for producing sound joints with sufficient strength.     

Electrolyte properties of 1-alkyl-2,3,5-trimethylpyrazolium cation-based room-temperature ionic liquids for lithium secondary batteries

The physicochemical and electrochemical properties of three 1-alkyl-2,3,5-trimethylpyrazolium cation-based room-temperature ionic liquids with various alkyl chain lengths were investigated. The temperature dependences of density, viscosity, and ionic conductivity were obtained by precise measurements. Electrolyte properties of these room-temperature ionic liquids were also examined from the viewpoint of their uses in lithium secondary batteries ([LiCoO₂ positive electrode|electrolyte|lithium metal negative electrode]). It was found that the alkyl chain length affects the charge–discharge performances of cells.     

Position command shaping for vibration suppression considering target position correction

This paper presents a command shaping technique based on a minimum jerk control approach that takes into consideration target position correction during motion, for the fast and precise positioning in vibratory mechatronic systems. The positioning controller is designed using a two‐degree‐of‐freedom control: a feedback compensator is synthesized by H_∞ control design to ensure the robust stability, while a feedforward compensator suppresses the vibration in response based on a coprime factorization expression of the plant mechanism. The command shaping, on the other hand, eliminates the corresponding vibration components of the primary and secondary models in the position command, where the continuity of jerk component in the command can be ensured against the target position correction. The effectiveness of the proposed shaping technique has been verified by experiments using a table drive system on a machine stand. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 168(3): 38–47, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20838     

Tomatine,chlorophyll, β‐carotene and lycopene content in tomatoes during growth and maturation

Tomato (Lycopersicon esculentum) plants synthesise nutrients, pigments and secondary metabolites. These include the green pigment chlorophyll, the yellow pigment β‐carotene, the red pigment lycopene and the colourless glycoalkaloid α‐tomatine. The levels of these compounds are strongly influenced by the maturity of the tomatoes. Widely consumed Japanese tomato varieties Momotaro, Momotaro‐T93 and First Memory at five different stages of ripeness, each harvested at 10, 20, 30, 40 and 50 days after flowering of the plants, were analysed for the contents of these compounds. Additionally, tomato clusters from different locations along the vine on the same plant were also evaluated. The results show that chlorophyll and tomatine concentrations decrease rapidly during the growth of the tomatoes. By contrast, β‐carotene and lycopene levels are low in immature and high in mature tomatoes. The location of the tomato clusters and tomato variety did not significantly affect these results. The possible usefulness of these results to optimise health‐promoting effects of tomatoes is discussed. © 2003 Society of Chemical Industry