Design and implementation of an adaptive recurrent neural networks (ARNN) controller of the pneumatic artificial muscle (PAM) manipulator

This paper presents the design, development and implementation of an adaptive recurrent neural networks (ARNN) controller suitable for real-time manipulator control applications. The unique feature of the ARNN controller is that it has dynamic self-organizing structure, fast learning speed, good generalization and flexibility in learning. The proposed adaptive algorithm focuses on fast and efficient optimization by weighting parameters of inverse recurrent neural models used in the ARNN controller. This approach is employed to implement the ARNN controller with a view to controlling the joint angle position of the highly nonlinear pneumatic artificial muscle (PAM) manipulator in real-time. The performance of this novel proposed controller was found to be superior compared with a conventional PID controller. These results can be applied to control other highly nonlinear systems as well.     

Synthesis of vertical arrays of ultra long ZnO nanowires on noncrystalline substrates

Vertically aligned arrays of ultralong ZnO nanowires were synthesized on SiO₂ substrates with carbothermal vapor phase transport method with Au seeding layer. High density of vertically aligned ZnO nanowires with lengths from a few to ∼300 μm could be grown by controlling growth conditions. Supply of high concentration of Zn vapor and control of the ratio between Zn vapor and oxygen are found to have the most significant effects on the growth of long ZnO nanowires in the vapor-solid growth mechanism. The nanowires are of high crystalline quality as confirmed by various structural, compositional, and luminescent measurements. Luminescent and electrical properties of ZnO nanowires with different growth conditions were also investigated.     

Direct assembly of preformed nanoparticles and graft copolymer for the fabrication of micrometer-thick, organized TiO2 films: high efficiency solid-state dye-sensitized solar cells

Solid-state dye-sensitized solar cell with 7.1% efficiency at 100 mW/cm(2) is reported, one of the highest observed for N719 dye. Excellent performance was achieved via a graft copolymer-templated, organized mesoporous TiO(2) film with a large surface area using spindle-shaped, preformed TiO(2) nanoparticles and solid polymer electrolyte.     

A nanoforest structure for practical surface-enhanced Raman scattering substrates

A nanoforest structure for surface-enhanced Raman scattering (SERS) active substrates is fabricated and analyzed. The detailed morphology of the resulting structure can be easily controlled by modifying the process parameters such as initial gold layer thickness and etching time. The applicability of the nanoforest substrate as a label-free SERS immunosensor is demonstrated using influenza A virus subtype H1N1. Selective binding of the H1N1 surface antigen and the anti-H1 antibody is directly detected by the SERS signal differences. Simple fabrication and high throughput with strong in-plane hot-spots imply that the nanoforest structure can be a practical sensing component of a chip-based SERS sensing system.     

Stress-induced domain dynamics and phase transitions in epitaxially grown VO₂ nanowires

We demonstrate that surface stresses in epitaxially grown VO? nanowires (NWs) have a strong effect on the appearance and stability of intermediate insulating M? phases, as well as the spatial distribution of insulating and metallic domains during structural phase transitions. During the transition from an insulating M1 phase to a metallic R phase, the coexistence of insulating M? and M? phases with the absence of a metallic R phase was observed at atmospheric pressure. In addition, we show that, for a VO? NW without the presence of an epitaxial interface, surface stresses dominantly lead to spatially inhomogeneous phase transitions between insulating and metallic phases. In contrast, for a VO? NW with the presence of an epitaxial interface, the strong epitaxial interface interaction leads to additional stresses resulting in uniformly alternating insulating and metallic domains along the NW length.     

Dissecting contact mechanics from quantum interference in single-molecule junctions of stilbene derivatives

Electronic factors in molecules such as quantum interference and cross-conjugation can lead to dramatic modulation and suppression of conductance in single-molecule junctions. Probing such effects at the single-molecule level requires simultaneous measurements of independent junction properties, as conductance alone cannot provide conclusive evidence of junction formation for molecules with low conductivity. Here, we compare the mechanics of the conducting para-terminated 4,4'-di(methylthio)stilbene and moderately conducting 1,2-bis(4-(methylthio)phenyl)ethane to that of insulating meta-terminated 3,3'-di(methylthio)stilbene single-molecule junctions. We simultaneously measure force and conductance across single-molecule junctions and use force signatures to obtain independent evidence of junction formation and rupture in the meta-linked cross-conjugated molecule even when no clear low-bias conductance is measured. By separately quantifying conductance and mechanics, we identify the formation of atypical 3,3'-di(methylthio)stilbene molecular junctions that are mechanically stable but electronically decoupled. While theoretical studies have envisaged many plausible systems where quantum interference might be observed, our experiments provide the first direct quantitative study of the interplay between contact mechanics and the distinctively quantum mechanical nature of electronic transport in single-molecule junctions.     

Drop-on-demand printing of carbon black ink by electrohydrodynamic jet printing

Electrohydrodynamic (EHD) jet printing is a technique using electric fields to eject inks through nozzle apertures. EHD jet printing is very attractive due to its non-contacting nature and compatibility with diverse materials and substrates. In this research, we have fabricated micron-sized dot arrays and line patterns with carbon black ink on Si wafer substrates using EHD jet printing. The effect of operating conditions such as applied voltage, working distance and stage speed on the size and shape of the jetted patterns and jetting cycles is investigated by using optical microscope, high speed camera and atomic force microscopy (AFM). We have also demonstrated the drop-on-demand feature of the EHD jet printing system by patterning carbon black ink lines with various widths and dot arrays with desired diameters and spacing by controlling the operating conditions.     

Evaluation of sulfur and multi-walled carbon nanotube composite synthesized by dissolution and precipitation for Li/S batteries

An elemental sulfur and multi-walled carbon nanotube (S-MWNT) composite was synthesized by dissolving sulfur in ammonium sulfides and then precipitating on MWNT. Morphology observation by scanning electron microscopy (SEM) confirmed that S-MWNT product was successfully prepared by incorporating sulfur into MWNT network. Without additional conducting material, the S-MWNT composite cathodes were prepared for electrochemical tests. The properties measured in discharge-charge cycling test showed that the composite had the initial discharge capacity of 1024 mAh g(-1), which is about 61% sulfur utilization. However, in the subsequent cycling, the capacities faded. To determine the reason of rapid capacity drop, S-MWNT composite cathodes were compared in the cycling tests with varying three kinds of electrolytes and the cathode was subjected to physical force by rolling. The changes in the cycle performances proved that the deterioration of S-MWNT composite cathodes was not related to the electrolytes but to physical bonding that may not maintain the conducting path between sulfur and MWNT.