Noncontact conveyance of conductive plate using omni-directional magnet wheel

A magnet wheel is chosen as the driving method to transfer a conductive plate without mechanical contact in space, due to its high force density. When permanent magnets (hereafter PMs) constituting the magnet wheel rotate below the conductive plate, not only a repulsive type of normal force but also a traction torque is generated on the plate. To utilize the torque as a thrust force, the magnetic fields from PMs are covered partially using a magnetic shield plate. So, in-plane positions of the conductive plate are controlled by turning the shield plate opened partially. In this paper, the operating principle of the noncontact conveyance system using a magnet wheel is discussed, including experimental verification. Specially, the resulting force from the suggested magnet wheel is AC force with oscillation, but it can be minimized through varying entry or exit shape of the open area of the magnetic shield plate.     

Effects of focused ion beam milling on the compressive behavior of directionally solidified micropillars and the nanoindentation response of an electropolished surface

Focused ion beam (FIB) milling is the typical method used to fabricate micropillars to study small-scale plasticity and size effects in uniaxial compression. However, FIB milling can introduce defects into the milled pillars. To investigate the effects of FIB damage on mechanical behavior, we tested Mo-alloy micropillars that were FIB milled following directional solidification, and compared their compressive response to pillars that were not FIB milled. We also FIB milled at glancing incidence a Mo-alloy single-crystal surface, and compared its nanoindentation response to an electropolished surface of the same crystal. Implications for the interpretation of data obtained from FIB-milled micropillars are discussed.     

Load-adaptive, low switching-noise output buffer

An output buffer is described which employs built-in load monitoring in order to bound the transition time over a wide range of load conditions. The adaptive control of driving current enables the switching-noise to be kept to a minimum value. The experimental chip, which was designed to bound the fall time within 6 ns for loading capacitance up to 100 pF, revealed a reduced switching-noise level, 15-35% of a conventional buffer     

A new polarization-insensitive 1.55-μm InGaAsP-InGaAsPmultiquantum-well electroabsorption modulator using astrain-compensating layer

In a conventional polarization-insensitive multiquantum-well electroabsorption modulator, it is normal to apply tensile and compressive strain on the well and the barrier, respectively. But the main disadvantages of such a structure are a low conduction band offset (0.04-0.06 eV), a high heavy-hole band offset (0.20-0.24 eV), and a relatively large well thickness (110-120 Å). We propose a new method of overcoming these disadvantages by placing a tensile strain on both the well and the barrier and compensating for them with a compressive strained intrinsic layer     

Digital signal processing applied to the detection of partialdischarge: an overview

This article is the first of a four-part series by the authors that treats various aspects of digital signal processing applied to partial discharge detection. It is shown that manufacturers and users of high-voltage apparatus are interested in on-site, off-line and on-line analysis of partial discharge to identify and locate defects in insulation systems     

Sorption of C. I. Disperse Red 60 in polystyrene and PMMA films and polyester and Nylon 6 textiles in the presence of supercritical carbon dioxide

C. I. Disperse Red 60 (DR60) was absorbed into polymer films and textile fibers in the presence of supercritical carbon dioxide at pressures between 5 and 33MPa and at temperatures between 308.2 and 423.2 K. Polystyrene (PS) and poly(methyl methacrylate) (PMMA) films and polyester (polyethylene terephthalate: PET) and Nylon 6 textiles were used as absorbents. The amount of equilibrium sorption of dye increased both with pressure and temperature. The sorption behavior was successfully analyzed with the quasi dual-mode sorption model.     

Cycling performance of a lithium-ion polymer cell assembled by in-situ chemical cross-linking with fluorinated phosphorous-based cross-linking agent

Lithium-ion polymer cells composed of a carbon anode and a LiCoO₂ cathode are assembled with a gel polymer electrolyte cured by in-situ chemical cross-linking with novel cross-linking agents. The strong interfacial adhesion between the electrodes and the porous polyethylene membrane by the chemical cross-linking results in the stable capacity retention of the cell. However, a reduction in the ionic mobility in both the electrolyte and the electrodes adversely affects the high rate performance of the cell. These results imply that proper control of the cross-linking density in the cell is imperative for achieving good capacity retention and high rate performance of the cell.     

Piezoresistive effects of copper-filled polydimethylsiloxane composites near critical pressure

Piezoresistive properties of polydimethylsiloxane (PDMS) filled with copper particles in volume fraction above the electrical percolation threshold (25.3–50.7 vol%) were investigated. Piezoresistive behavior of the PDMS-copper composites under compressive pressure showed not only a change in resistance by approximately six orders of magnitude (∼1.5 MPa), but also a change in the critical pressure due to variations in the hardness of the composites. Resistivity relaxation was observed near the critical pressure and was explained through a stress relaxation and percolation mechanism. The mean tunneling distance was calculated by using a theoretical equation for percolation under compression. When the gauge factors of the composites were plotted versus strain, a universal curve was obtained regardless of the copper contents. Finally, the PDMS-copper composite demonstrated good repeatability, showing only small differences in the relative resistance after five successive tests.     

Preparation of silica-layered multi-walled carbon nanotubes activated by grafting of poly(4-vinylpyridine)

Herein, uniformly silica coated carbon nanotubes (CNTs) were fabricated by step reactions with minimized damage of CNTs during oxidation process. First, hydroxyl groups were generated on the surface of CNTs using KMnO₄ in conjunction with tetrapropyl ammonium bromide (TPABr) as a phase transfer catalyst, followed by the grafting of a vinyl group carrying silane coupling agent, methacryloxypropyl trimethoxy silane (MPTMS). Utilizing terminal vinyl groups in in-situ solution polymerization, poly(4-vinylpyrridine) (P4VP) brush was grown from the CNTs which promotes the acid–base interaction between CNTs and tetraethylorthosilicate (TEOS). By means of well-known ammonia catalyzed sol–gel reaction of TEOS in the presence of P4VP-functionalized CNTs, uniformly silica-coated CNTs were obtained. The thickness of the silica layer could be readily controlled by the amounts of reactants. After calcination of silica-coated CNTs, only outer silica remained which resulted in silica nanotubes.