Morphology of the growth tip of carbon microcoils/nanocoils

Single-helix twisted carbon nanocoils and single-helix spring-like carbon micro/nanocoils were prepared by the CVD process of the catalytic pyrolysis of acetylene at 700–800 °C over Fe-containing alloys in large scale, with a high purity and good reproducibility and with the coil yield of about 60%. The morphology and microstructure were examined. The catalyst grains on the growth tip of the nanocoils were observed closely. The results indicated that most of the twisted nanocoils grown by a two directional growth mode; that is, two twisting nanocoils grew out of a catalyst grain in opposite chirality and the fibers are grown in the herring-bone structure. Spring-like carbon coils were prepared with over sputtered Fe alloys on ceramics supporters, with a high purity and good reproducibility and with the coil yield of about 20%. All of the spring-like carbon coils are of one directional growth mode, and their coiling diameter and coil pitch are about the same size of several hundred nanometers. It is very common to observe spring-like nanocoils with laces, TEM investigation results showed that the spring-like nanocoils are of tubular coils.     

Preparation of carbon microcoils by catalytic methane hot-wire CVD process

Three-dimensional (3D) double-helix carbon microcoils (CMCs) were synthesized by the catalytic pyrolysis of methane using Ni catalyst in various hot-wire CVD processes. The most effective process is: using preheating method, in which methane was preheated at 1500 °C in a upper reaction tube by a hot wire, and chemical vapor deposition of carbon then occurred at 700-750 °C in a lower reaction tube, where CMCs were synthesized. The growth morphologies and microstructure were examined and compared with the conventional CMCs grown by acetylene catalytic pyrolysis.     

Characterization of interface state density of three-dimensional Si nanostructure by charge pumping measurement

Adopting the gated p–i–n diode configuration, the interface state density (D_it) at the Si/SiO₂ interface of Si fin structures on Silicon-on-Insulator (SOI) wafers has been systematically studied using charge pumping method. The optimal forming gas annealing temperature for the three-dimensional (3D) surface is extracted. A new methodology for separately quantifying the local D_it at different regions of the 3D surfaces (i.e., the top/side walls and the corners) is also derived by characterizing the fins with various widths and the planar counterparts. The results validate the necessity to independently consider the corner regions, at which substantially high local D_it situates, and thus further clarify the origin of high D_it at 3D surfaces.     

Preparation and properties of nickel silicide layers by the diffusion and CVD processes using Si2Cl6 as a source of silicon

Nickel plate was siliconized with a gas mixture of Si₂Cl₆, H₂ and argon in the temperature range 400 to 900° C, and the siliconizing conditions and some of its properties were examined, Appreciable weight increase of the nickel plate was observed above 450° C, which is 200 to 300° C lower than that obtained using SiCl₄ as a source of silicon. Siliconizing of the surface and the resistance to high-temperature oxidation and hot corrosion were improved, Nickel silicide layers were also obtained by the CVD process using a gas mixture of Si₂Cl₆, H₂ and argon.     

The measurement of radiating pattern by using the cylindrical function

The paper proposes a new method of measuring radiating patterns from antennas or EMI sources. In this method, the cylindrical function is adopted for the near-to-far-field transformation. The new measuring method does not require the large free space prescribed by FCC and CISPR. The radiated electric field is described by using the series cylindrical function, i.e. the Hankel function, with unknown series coefficients. Applying the boundary condition on the virtual boundary, which surrounds the radiating objects in free space, the unknown series coefficients in the radiated field can be determined. Using asymptotic expansion of the Hankel function with the known series coefficients, the far-field data, that is the radiating patterns, are given. In order to verify the proposed method, numerical experiments are performed with a line sources array. The results show good agreement with the array antenna pattern equation. Moreover, two types of measurement systems are suggested for the radiating patterns, both employing a vector network analyser. Accurate radiating patterns can be measured with compact systems using the proposed method.     

Preparation of helical TiO2/CMC microtubes and pure helical TiO2 microtubes

Helical TiO₂/CMC (carbon microcoils) microtubes and helical TiO₂ microtubes were obtained by making TiO₂ layer coatings on the surface of CMC templates using a sol-gel and chemical vapor deposition (CVD) processes. The preparation conditions, morphologies and some properties were examined. Uniform TiO₂ (anatase) layers were obtained on the CMC templates by a CVD process using vapor phase hydrolysis of titanium tetra-isopropoxide at 300°C followed by heat treatment in N₂ or by calcination in air at 500–;650°C. The helical TiO₂/CMC microtubes showed good photocatalytic activity. It was considered that the helical structure activated and enhanced the photocatalytic activity of TiO₂, probably caused by the generation of inductive microelectric current induced by the irradiation of UV light, resulting in the generation of micromagnetic fields around the tubes.     

Preparation and properties of TiC micro-coils and micro-tubes by the vapour phase titanizing of carbon micro-coils

TiC micro-coils and micro-tubes were prepared by the vapour phase titanizing of the regular carbon micro-coils, and the preparation conditions and some properties were examined. The carbon coils were titanized from the surface of the fiber to the core with full preservation of the coiling morphology to form TiC micro-coils or micro-tubes. The bulk electrical resistivity was 0.1–0.01 ·cm depending on the titanized rate and the bulk density. The specific surface area of the source carbon coils (about 100 m²/g) was significantly decreased with increasing reaction temperature and reaction time. The tensile strength of a TiC micro-tube was 660 MPa. The attenuation ratio against an electromagnetic wave of the TiC micro-tubes (30 wt % in epoxy resin) was about 90% (dB = –10) for 800–900 MHz.     

Effective input order of dynamics learning tree

In this paper, we discuss about the learning performance of dynamics learning tree (DLT) while mainly focusing on the implementation on robot arms. We propose an input-order-designing method for DLT. DLT has been applied to the modeling of boat, vehicle, and humanoid robot. However, the relationship between the input order and the performance of DLT has not been investigated. In the proposed method, a developer is able to design an effective input order intuitively. The proposed method was validated in the model learning tasks on a simulated robot manipulator, a real robot manipulator, and a simulated vehicle. The first/second manipulator was equipped with flexible arm/finger joints that made uncertainty around the trajectories of manipulated objects. In all of the cases, the proposed method improved the performance of DLT.