Preparations for a special issue, trends in research and development in 2003, have been initiated at committee level of the Fundamentals and Material Society (FMS). In this issue, technical committee of Instrumentation and Measurement summarized the latest topics and future technical trends. It is reported that 1 THz optical sampling oscilloscope is possible.
Manipulation and analytical method for single DNA molecules has been under development. The manipulation uses the transformation of DNA to globular state. Using the reverse transformation, single DNA molecules can be fixed in stretched mode for characterization. Fragments of the stretched DNA molecule can be cut and amplified by PCR (Polymerase Chain Reaction) using droplets as a container of single molecules and chemical agent. These techniques can be incorporated for micro-total analysis system.
This paper deals with the inverse problem of estimating the refractive-index profile of a lossless stratified medium by using back-scattering responses of pulsed waves.In the reconstruction procedure, the stratified medium is approximated by a multilayered model, and back-scattering responses from the estimated profile is obtained in a sense of geometrical optics.Introducing a cost functional concerning the responses from the estimated profile and the responses from the true profile, we can derive a simultaneous equation to update iteratively the refractive index of each layer of the model.Two-layered slabs and a five-layered slab located in free space are reconstructed, and the validity of the presented technique is numerically investigated.
By use of the Photonic Band Gap in the photonic crystal, the waveguide and the devices for the light wavelength range can be developed.Due to the fine structure of these ones, the simulation is indispensable to grasp and predict the properties of those.So far, many analyses by FDTD and BPM have been performed. In this paper, the treatment of uni-axial anisotropic dielectric by the Condensed Node Spatial Network for vector potential is proposed, and it is also shown that this method has the advantage in parallel computation algorithm.The improvement of TM wave transmission property through the sharp bend in 2-D air-hole type photonic crystal waveguide on the uni-axial anisotropic substrate are presented.
In order to calculate 3-D electromagnetic scattering problems by dielectric objects which we need to solve a big size simultaneous linear equation, we present a rapid algorithm on the Yasuura method where we accelerate the convergence rate of solution by using an array of multipoles as well as a conventional multipole. As a result, we can obtain the radar cross sections of dielectric objects in the optical wave region over a relative wide frequency range and a TDG pulse response. Furthermore, we analyze the scattering data about dielectric objects by using the pulse responses cut by an appropriate window function in the time domain and clarify the scattering processes on dielectric objects.
Optical near-field in the aperture in the thick metallic screen is analyzed numerically by the three-dimensional volume integral equation with Generalized Minimum Residual Method. Numerical results have been confirmed by the invariance of the results of the discretized size and reciprocity. The dependence of the scattering cross section on the thickness of the screen have been calculated. It is found that near-field distribution around the small aperture is a slightly different from Bethe's results.
Diffraction from a uniaxial chiral slab with a two-dimensional periodic array of conducting patches is analyzed by the 4 × 4 matrix-based approach. Equitorial anisotropy is assumed for the chirality whose optical axis is parallel to the plane of incidence. In the analysis, the total fields are given by the superposition of the current-dependent scattered fields which are expanded in terms of the two-dimensional space harmonics and the primary fields. The coupled mode equations for the equitorial uniaxial chiral media give the general solutions of fields as the superposition of elliptically-polarized eigen modes. The unknown currents on the patches are determined by applying Moment method to the boundary condition of the conducting array. In the numerical computations, the polarization characteristics of diffracted waves are investigated considering the design parameters.
We analyze the scattering problems of the dielectric gratings in conical mounting by applying Inverse Rule to matrix eigenvalue method that is using the Fourier series expansion for relative permittivity and the spatial harmonics expansion for electromagnetic fields.The surface relief profile of the dielectric gratings can be expressed by using multilayered step method.The convergence of our method for surface relief gratings is faster than that of the conventional method.Moreover, we analyze about the characteristics of scattering electromagnetic wave by using this method.
This paper has developed a multiband single-layer frequency selective surface (FSS) designed by using the optimization technique (genetic algorithm). The characteristics of the designed FSS are superior to those of the Fractal FSS in the close separation between two reflection bands. As a typical example, we design the FSS for passing L and S bands and reflecting Ku and Ka bands. Finally, the agreement between the calculated and measured transmission response for the designed FSS proves the validity of the present method.
We have analyzed the effective constitutive parameters for a random medium containing small chiral spheres embedded in an achiral background medium by using our approach.The approach is based on an unconventional multiple scattering method by which wave scattering can be systematically treated in a medium whose dielectric particles are randomly displaced from a uniformly ordered spatial distribution.We have made clear the characteristics of the effective medium parameters by changing the volume fraction and constitutive parameters of chiral spheres.
It is necessary to know the effective permittivity and permeability of an artificial material, when one tries to utilize it for microwave resonators. The proposal is to calculate them easily by use of a commercial software for electromagnetic wave analysis. After examining the validity of the present method, they carry out the parametric study of an artificial dielectric based on metallic unit particles and its control. By adjusting the geometrical parameters, the material composed of metal strips acquires high anisotropy and permittivity. The material is made up of sheet-type print boards to measure the permittivity.
A simple but useful human head model for handset antenna designs is discussed at the frequency band of 900 MHz.First, the effect of the head model's shape on the radiation characteristics of a dipole antenna is investigated by using various homogeneous head models.Next, the effect of material constants of the tissue on the radiation characteristics is discussed by using a homogeneous head model.A qualitative and quantitative discussion reveals that the effect of the head model's shape on the antenna characteristics is larger than that of the heterogeneity of the model.In particular, radiation characteristics are found to be not a ected so much by material constants of the homogeneous head model.
Recently, MEMS technology is growing rapidly in RF field and the accurate design of RF MEMS devices require the computationally effective modeling of their transient and steady-state behaviors. In this paper, a numerical method to solve these MEMS devices using body fitted grid generation method with moving boundaries is proposed. This method is based on the finite-difference time-domain (FD-TD) method with an adaptive implementation of grid generation. The key feature of this method is time factor is added to the conventional numerical grid generation. Employing this transformation, it is possible to apply the grid generation technique to the analysis of geometries with time -changing boundary conditions. With such grid, the FD-TD method can be solved very easily using a time-invariant square grid regardless of the shape and the motion of the physical region. With this procedure, the numerical method for analysis of variable capacitor is shown. This technique can be easily generalized for the numerical simulation of RF MEMS structures that involve motion.
To achieve high confinement properties of a tokamak plasma, it is necessary to control the plasma position, current profile, shape of magnetic surface etc.. In addition to these, it has been found that a resistive wall mode (RWM) may limit the achievable plasma beta in present tokamak devices. Therefore, it is expected that an active feedback control using external coils is necessary to stabilize the RWM. A power supply for plasma control coils requires an accurate controllability and a fast response against such plasma disturbances. Recent development of high power and fast switching semiconductors, such as Insulated Gate Bipolar Transistor (IGBT) and MOSFET, improves the temporal response of power supply with a great extent. A small tokamak device, HYBTOK-II, is equipped with IGBT inverter power supplies for Joule and vertical field coils. In this paper a real-time feedback control of the plasma horizontal position has been employed with Digital Signal Processor (DSP). The experimental results on plasma response with such a feedback control have been compared with analysis of plasma column motion using transfer functions.
It is known that critical current density Jc in Bi-Based superconductors increases with the length of sintering time, and further increases with cold isostatic pressing (CIP) process. Analysis of excess conductivity due to the thermal fluctuation above Tc provides information about fluctuation amplitude and the dimensionality of conduction, and makes it possible to evaluate the superconducting correlation length. In this study, the mechanism of how Jc of Bi-based copper oxide improves by increasing sintering time is discussed on the basis of fluctuation-conductivity analysis. The temperature dependence of the resistance of Bi-based superconductors with various sintering time was measured. It was found that correlation length and effective cross-sectional area obtained from analysis systematically decrease with the sintering time, and that these parameters correlate well with Jc of the samples. It is widely accepted that the increase in Jc of the samples is due to the improvement in the crystallinity, (i.e., the increase in crystal density and better alignment of the crystal grains) which brings about decrease in correlation length and effective cross-sectional area. Therefore, the effect of the improvement in the density and alignment of the crystals, an important factor for increasing critical current density, was evaluated from the fluctuation conductivity analysis.
Polyethylene (PE) consists of non polar molecular chain having simple structure unit. Physically, it is so stable and flexible that this polymer is used widely for electric wire, electric power cable and various molding goods. Among the fundamental properties of PE, the crystalline texture, the formation of spherulite, has a pronounced influence on it's mechanical and electric properties. For the purpose of improving these properties of PE the spherulites is disappeared completely by heat mixing of PE with Li2CO3. Thus obtained PE has no spherulites, uniform structure, and excellent electrical and mechanical and thermal properties, e.g. short treeing length and high electric break down strength, and high tearing impact strength.
Characteristics of ozone production have been investigated by irradiation of intense, pulsed relativistic electron beam (IREB). The 1.8-m-long gas-treatment chamber is filled up with dry-N2-balanced O2 gas mixture with the pressure of 98 kPa and is irradiated by IREB. The kinetic energy, current and pulse width of the IREB are - 2 MeV, - 2.9 kA, and - 80 ns (FWHM), respectively. It is found that - 340 ppm of ozone is produced by firing 10 shots of the IREB. We have also obtained the production yield of ozone of 9 - 21 g/kWh.