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.     

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.     

A Hybrid Technique Combining FDTD and Series Solution for Near-to-Far-Field Transformation

A new near-to-far-field transformation that combines the FDTD and the series solution is presented. In this method, near-field data is calculated by FDTD and far-field data is also expressed by series solution. The boundary condition is applied to a virtual surface, which encloses arbitrarily shaped scatterers. In order to verify this method, scattering patterns from this transformation are compared with scattering patterns from exact solution. Numerical results show that errors in the far-field data from this method is less than surface equivalence theorem. Thus, this method is valid for obtaining the far-field data.     

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.     

Reflection of the transitional electromagnetic wave by inhomogeneous ionized media having a peak of electron density

The reflection coefficient of an inhomogeneous ionized medium having a peak in electron density is analysed. The result shows the existence of peak influences for the phase term of non-peak linearly varying electron density in the medium. The characteristic of the reflection coefficient phase delay versus frequency is related to the electron density at a peak point and the position of the electron peak. Using this theory we can obtain the electron density distribution map in the inhomogeneous ionized medium. To verify the theory the reflection coefficient is compared with the results from the finite difference time domain method; both results give a good agreement.     

Kinetics of Solid-State Reactive Diffusion in the (Ni-Cr)/Sn System

The kinetics of solid-state reactive diffusion in the (Ni-Cr)/Sn system was experimentally observed to examine the influence of the addition of Cr into Ni on the growth behavior of compounds at the interconnection between Sn-based solder and multilayer Au/Ni/Cu conductor during energization heating. In the experiment, Sn/(Ni-Cr)/Sn diffusion couples with Cr mol fractions of y?=?0.051 to 0.282 were isothermally annealed at temperatures of T?=?433?K to 473?K for various times up to t?=?3167?h. During annealing at T?=?453?K to 473?K, a two-phase compound layer with rather uniform thickness consisting of Ni₃Sn₄ and CrSn₂ is produced at the initial (Ni-Cr)/Sn interface in the diffusion couple, where the compound layer indicates a periodic lamellar microstructure parallel to the initial interface typically for y?=?0.150. On the other hand, at T?=?433?K, Ni₃Sn₄ and CrSn₂ are formed also as a two-phase layer for y?=?0.117 but as granular particles for y?=?0.051 and y?=?0.150 to 0.282. The mean thickness l of the compound layer is proportional to a power function of the annealing time t. Since the exponent n of the power function takes values of 0.58 to 0.85, interface reaction as well as diffusion contribute to the rate-controlling process for compound growth. The overall growth rate of the compound layer reaches a maximum value at y?=?0.12 within the experimental annealing times. Thus, the compound growth at the interconnection is remarkably accelerated by the addition of Cr with y?=?0.12 into Ni in the multilayer Au/Ni/Cu conductor, though the addition of Cr improves the heat resistance of Ni.     

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.     

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.