The precision of magnetic field calculation is crucial to predict the arc behavior using magnetohydrodynamic (MHD) model. A integrated calculation method is proposed to couple the calculation of magnetic field and fluid dynamics based on the commercial software ANSYS and FLUENT, which especially benefits to take into account the existence of the ferromagnetic parts. An example concerning air arc is presented using the method.

A dispersion diagram is useful in interpreting the characteristics of a periodic structure. In particular, the fast-wave region, where the wave is radiating, and the slow-wave region, where the wave is guided, can be determined from the dispersion diagram. An electronically-controlled composite right/left-handed (CRLH) transmission line (TL) was previously proposed and utilized as a leaky-wave (LW) antenna operating in the fast-wave region. However, since a guided-wave application operates in the slow-wave region, it is meaningful to study slow-wave effects of the proposed TL. In this paper, the dispersion diagram is used to investigate the slow-wave factor (SWF), which is necessary to understand the fast/slow-wave operations. Furthermore, the frequency characteristics are measured to find the cut-off frequencies in the LH and RH regions. Based on experimental results, it is observed at a fixed frequency, 2.6-GHz, that the phase of a proposed 6-cell structure can be changed by up to 280 in the LH slow-wave region.

The characteristics of two-stage composite right- and left-handed (CRLH) transmission lines are discussed. The dispersion relationship of both balanced and unbalanced two-stage CRLH lines is described, together with numerical calculations that demonstrate their potential.

Various kinds of optical near-field apertures have been proposed for higher throughput and smaller spot size. However, few studies have mentioned the readout characteristics of the recorded marks on an optical disk illuminated by a near field optical light. In this paper, we have investigated the scattering light by a two-dimensional recorded mark on a phase change disk with Finite-Difference Time-Domain (FDTD) simulations. Instead of using Recursive Convolution (RC) and Piecewise Linear Recursive Convolution (PLRC) scheme, we integrated the motion equation of free electron into conventional FDTD method to solve the electromagnetic field in the metallic materials. The validity of the proposed method is illustrated by comparing its results with those from the analytic exact solution. We analyzed the distributions of optical near-field around a two-dimensional metallic nano-aperture, and then calculated the far-field scattering pattern from a two-dimensional recorded mark on a phase change disk while it was illuminated by an optical near-field though a nanoaperture. The sum signal by a condenser lens was calculated from far-field pattern, and its relationships with the width of recorded mark and the thickness of each layer in the phase change disk were illustrated. The cross-talk between the recorded marks was also discussed.

Transmission line metamaterials on coplanar waveguide with series-capacitive and shunt-inductive distributed loading in periodical intervals are characterized using our developed fullwave self-calibrated method of moments. Firstly, the two effective per-unit-length transmission parameters, i.e., complex propagation constant and characteristic impedance, are numerically extracted. The results provide a straightforward insight into the forward- and backward-wave propagation characteristics in several distinctive bands, including the left- and right-handed stopbands and passbands. In particular, it is demonstrated that in the whole left-handed passband, the propagation constant has purely negative phase constant while the characteristic impedance has only positive real quantity. Next, varied left- and right-handed passbands are studied in terms of lower/higher cut-off frequencies based on ideal equivalent circuit model and practical distributed CPW elements, respectively. Of particular importance, the left-handed and right-handed passbands find to be able to be directly connected with a seamless bandgap under the condition that normalized inductance and capacitance of loaded CPW inductive and capacitive elements become exactly the same with each other. Finally, the 9-cell metamaterial circuits on CPW with actual 50 Ω feed lines are designed and implemented for experimental validation on the derived per-unit-length parameters.

Eye tracking is a useful tool for accurately mapping where and for how long an individual learner looks at a video/image, in order to obtain immediate information regarding the distribution of a learner's attention among the elements of a video/image. This paper describes a quantitative investigation into the effect of voice navigation in web-based learning materials.

Near-field imaging has been intensively investigated to observe the shape and the physical properties of objects, aiming at wide applications in the areas of science and engineering. In this research, by using 60 GHz band waveguide-type microscopic aperture probe, the characteristics of the near-field imaging in transmission mode have been studied by simulation and experiment. The probe is made of a WR-15 rectangular waveguide with end-shielded metal plate and a 0.5 mm-diameter aperture. In the simulation, at first, the electric field distribution at the aperture, at the rear (waveguide) and the front positions (free space) are presented. Second, the transmitted electric fields are presented for three cases: (a) scanning of a dielectric slit, (b) by varying the distance between the aperture and a dielectric sample, and (c) scanning of a dielectric groove. In the experiment, the lateral resolution with a two-slit and the depth resolution with grooves having various depths in rectangular format are described and the results show both resolutions to be much shorter than the wavelength. Finally, the scanned images of the letter N punched through a dielectric material and a leaf are demonstrated.

Basic microwave properties of magnetic photonic (MPC) and degenerate band edge (DBE) crystals are investigated mathematically and experimentally. Two dimensional and three dimensional models are considered demonstrating the very high sensitivity and field growth associated with these crystals. A major part of the paper deals with the development of realistic anisotropic periodic structures using a combination of layers constructed from thin film frequency selective surfaces, alumina, titanate and calcium vanadium garnet (CVG) materials. Measurements for antenna applications demonstrate and validate the theoretical performance of the MPC and DBE crystals. The latter part of the paper will present an exciting and promising development relating to microwave circuit applications. Specifically, a novel dual-line printed circuit is presented to emulate propagation in anisotropic media. As such, the MPC and DBE phenomena can be realized using very simple printed circuits (coupled lines). Lastly, physically small printed antennas and arrays based on the coupled transmission lines are presented.

Electromagnetic scattering properties of metamaterial cylinders due to a line source are studied by a multilayer algorithm based on eigenfunctional expansion. Closed forms of electric and magnetic fields are formulated. Both the fields inside the cylinder and field in outer space are plotted for different sizes of the cylinder. The focusing phenomena and the wave propagation in the presence of metamaterial cylinders are investigated and shown. Electromagnetic field distributions are presented for subwavelength metamaterial cylinders and cylinders fabricated by magnetoelectric materials, and resonant scattering and focusing properties are reported. Special designs of scatterer cloaking are proposed and calculated by multilayer algorithm which can reduce scattering cross sections.

Two-Thickness-Method (TTM) based on an open-ended coaxial probe was investigated with an emphasis on uncertainty analysis to perfect this technique. Uncertainty equations in differential forms are established for the simultaneous measurement of complex electromagnetic (EM) parameters in the systematical consideration of various error factors in measurement. Worst-case differential uncertainty equations were defined while the implicit partial derivation techniques were used to find the coefficients in formulation. The relations between the uncertainties and test sample's thicknesses were depicted via 3D figures, while the influence of the coaxial line's dimension on the measurement accuracy is also included based on the same analysis method. The comparisons between the measured errors and theoretical uncertainty prediction are given for several samples, which validate the effectiveness of our analysis.

A particle for artificial magnetic materials in microwave frequency is proposed. It has simple structure composed of two parallel metal strips and is suitable to make a thin material extending in the transverse plane. In order to grasp the characteristic the effective permeability is formulated in the form of a transmission line. The characteristics of effective permeability are discussed based on the transmission line model for miniaturization and increase of the permeability. After discussing the reflection from materials with negative permeability or negative permittivity, a high impedance material is constituted. Total reflection with zero phase from the material composed of modified magnetic particles is measured in a waveguide.

The sputter erosion of arcing contacts is a very complex phenomenon, which is determined by the interaction between electromagnetic force, heat conduction and surface tension of liquid metal. A new model for evaluating the sputter erosion of electrodes is described in this paper, which is based on the electromagnetic forces against the molten pool, flowing velocity, kinetic energy and the surface tension of the molten pool. Erosion tests on AgSnO2, AgNi10 and AgNi0.15 contacts under the loads of resistance, lamp and inductance respectively at 14 VDC have been carried out. Experimental results indicate good agreement with the model's simulation. The model shows how the current and density, specific heat and other parameters of material affect the erosion rate.

A two-dimensional compressible magnetohydrodynamic (MHD) computational model has been developed to study the effect of gassing material on air arc behavior in low voltage circuit breaker. The properties of arc plasma and the electric, magnetic and radiative phenomena have been taken into account in the model. Based on the model, steady state solutions have been performed to study the effect of gassing material on the arc radius and electric field in the arc column. Then, the effect of gassing material on the transient process of arc motion also has been simulated. In addition, using the two-dimensional optical fiber measurement system, experiments have been done to measure the average velocity of arc motion with one model chamber and to verify the simulation model and prediction results. It demonstrates that the action of gassing material may yield the stronger electric field, less arc radius and higher arc motion velocity.

The possibility of using three kinds of new type composite materials as material for high speed sliding contacts was investigated. The results of this investigation were compared with the results of the low speed tests that were reported earlier. As a result of the above, it was discovered that for high speed rotation in the range from 0.014 m/s to 2 m/s, the order of merit did not significantly change. Based on this, it was concluded that if solid lubricant is effectively supplied to the sliding surface, the influence by frictional heat generated by high speed is slight. Of the three kinds of composite material, it was clarified that composite material (CMML-1) had the lowest contact resistance and Composite Material (CMML-3) had the lowest maximum frictional coefficient of friction. 'CM' and 'ML' are initialisms for 'Composite Material' and 'Material of Lubrication' respectively. The number that is attached to the material name is a numeric value that was set by this laboratory.

Eddy-current type proximity sensor is a non-contact type sensing device to detect the approach of a conductor by increase of coil resistance due to eddy-current loss. This paper proposes to add the cap-shaped magnetic flux shield at the top of the ferrite core for the actual sensor. In conventional proximity sensors, main magnetic flux path passes through the air between the target conductor and ferrite core. Proposed sensor, in contrast, has closed magnetic circuit geometry. It means that main magnetic flux path is almost completed by the core and the shield. Therefore, it is predicted that flux does not reach the target conductor and it causes debasement of sensing property. However, it is shown that the calculated results by FEM and measured results of sensing property of the proposed sensor is enhanced compared with the actual sensor. This paper quantitatively accounts the electromagnetisms of the proposed sensor from sensing property, flux distributions and eddy-current loss in each part of the sensor body. Moreover, material characteristics for the proposed shield, such as relative permeability and conductivity, are found.

The paper presents a method for testing transport of composite contacts materials under electrical arc conditions at high currents and for polarized electrodes. Tests and the discussion of results were carried out for silver-metal, silver-metal oxide and silver-tungsten carbide contact materials. Additionally, tungsten electrode was used as the second contact which was either cathode or anode. Spectrometric analysis of arc erosion components transported onto the second electrode and into the surroundings was carried out.

In order to improve the antenna gain, a composite right/left-handed (CRLH) leaky-wave (LW) antenna composed of symmetrical unit cells with short stubs terminated by vertical vias is designed. The use of symmetrical unit cells suppresses the cross-polarization of radiation to less than 23 dB. By comparing the measured radiation characteristics to that of a conventional CRLH LW antenna without short stub in the X-band, it is shown that the presented CRLH LW antenna with 51 unit cells offers a narrower beam and the antenna gain improves 4.1, 2.2 and 3.1 dB in the backward, broadside and forward directions of radiation, respectively.

Frequency-variation method (FVM), reported in [1], was further studied for simultaneously measuring the both complex permittivity and complex permeability by intentionally changing the test frequency to obtain different reflections. An enhanced coaxial-probe-based in-situ measurement system has been established. The spectral domain full-wave model is derived to take place of the quasi-static one. A novel coaxial probe is designed so that the one-port calibration could be performed with Agilent-supplied precise cal-kit instead of the liquid standard. Criterions for a right order of the interpolation polynomial used to approximate the frequency-dependent EM parameters; measures to reduce the residual mismatch errors and random error in reflection measurements and to suppress the ambiguities in solving the transcendent equation system were experimentally studied to resolve the problems and improve the accuracy in dispersive absorbing materials' test. Several typical dispersive absorbing coatings have been tested via FVM. The good comparison between the measured results and reference ones validate the feasibility of the proposed improved technique.

A novel two-dimensional (2D) beam scanning antenna array using composite right/left-handed (CRLH) leaky-wave antennas (LWAs) is proposed. The antenna array consists of a set of CRLH LWAs and a Butler matrix (BM) feeding network. The direction of the beam can be scanned two-dimensionally in one plane by changing frequency and in the other plane by switching the input ports of the BM. A four-element antenna array in the microstrip line configuration operating at 10.5 GHz is designed with the assistance of full-wave simulations based on the method of moment (MoM) and the finite-element method (FEM). The antenna array is fabricated and radiation characteristics are measured. The wide range 2D beam scanning operation with the angle from -30 deg to +25 deg in one plane by sweeping frequency from 10.25 GHz to 10.7 GHz and with four discrete angles of -46 deg, -15 deg, +10 deg, and +35 deg in the other plane by switching the input port is achieved.

A novel structure for a frequency-independent steerable composite right/left-handed (CRLH) leaky wave (LW) antenna in the millimeter-wave band is proposed. This has the advantages of wide beam scanning and low profile, and is a suitable structure for mass-production. The proposed antenna has features wherein a movable dielectric slab is placed above the CRLH LW antenna, and the radiation angle can be steered by changing the distance between the slab and the antenna using compact actuators. Moreover, slots are added to the antenna to control the aperture amplitude distribution of the array antenna in order to enhance aperture efficiency. A prototype CRLH LW antenna has been fabricated with these slots, and backward-to-forward beam scanning characteristics at 76 GHz have been demonstrated successfully by measurement. A wide scanning angle from 73 to 114 deg. has been achieved experimentally. The aperture efficiency is 25.3%.