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The effect of facial ring jewelry is investigated on the energy absorbed in the head when illuminated by communications-enabled personal data assistant (PDA)-type devices. We study the relative changes in specific absorption rates in the head due to perturbing metallic rings in proximity to the face illuminated by a 1.8 GHz dipole and a monopole on a conducting box. Simple and complex head models used in a validated finite-difference time-domain (FDTD) simulation are compared with measurements from an industry standard DASY4 SAR measurement system. Both simulation and measurement ate referred to the IEEE specific anthropomorphic mannequin head. Results show that metallic rings may alter specific absorption rates (SAR) level distributions within the head. Results are given for several common ring sizes. Index Terms--DASY4, finite-difference time-domain (FDTD), metallic jewelry, personal data assistant (PDA), specific absorption rates (SAR).

A method to detect minute flaws on metal parts is proposed to remove defective parts before assembling in a factory. The input grayscale images of metal parts are directly used to recognize flaws without any image conversion to shorten recognition time. The recognition problem to find flaws and detect their position on the metal parts is converted to another problem that searches for the maximum peak and the variables producing the peak. Then, the recognition problem can be treated as an optimization problem, and this conversion allows us to utilize high genetic algorithm performances in optimization. The effectiveness and problems of the proposed method are studied on the standing points of recognition speed and quantitative recognition ability. Based on the analysis, we furthermore improved our system to increase the flaw detection rate; the lighting direction was changed to find the best lighting condition that can emphasize the contrast between the metal surface and the flaw by using the reflection character of the hairline on the metal, which is resulted by a polishing process. Index Terms--Genetic algorithm (GA), metal surface inspection, model-based matching.

The major limiting factor in the transmission of high-power microwave (HPM) has been the interface between dielectric-vacuum or, even more severely, between dielectric-air, if HPM is to be radiated into the atmosphere. Extensive studies have identified the physical mechanisms associated with vacuum-dielectric flashover, as opposed to the mechanisms associated with air-dielectric flashover, which are not as well known. Surface-flashover tests involving high field enhancement due to the presence of a triple point have shown that volume breakdown threshold (dielectric removed) is approximately 50% higher than the flashover threshold with a dielectric interface over the 90-760 torr range. In order to quantify the role of field enhancement in the flashover process independent of electron injection from metallic surfaces, the effects of the triple point are minimized by carefully choosing the geometry, and in some cases, the triple point is 'removed' from the flashover location. Experimental results were presented, including the impact of gas pressure and the presence of UV illumination, along with temperature analysis of the developing discharge plasma and temporally resolved images of the flashover formation. These results are compared with literature data for volume breakdown in air, with discussion on the similarities and differences between the data. Index Terms--Atmospheric, breakdown, dielectric surface, high-power microwave (HPM), surface flashover.

A new conformal finite-difference time-domain (CFDTD) updating scheme for metallic surfaces nonaligned in the grid is presented in this paper. In contrast to existing conformal models, the new model can be formulated with the original Yee FDTD update equation. Therefore, the proposed scheme can be easily added in standard FDTD codes even if the codes are already parallelized or hardware-accelerated. In addition, based on the commonly used conventional stability criterion, a derivation of the stability is presented and based on the conformal geometric information, a time step reduction formula is presented. The time step reduction is used as a user-defined parameter to tradeoff speed versus accuracy. The achievable geometric precision is optimized to a given time step. Therefore, even with the conventional time step (no reduction) the presented scheme profits from the conformal discretization. To show the performance and the robustness of the proposed scheme canonical validations and two real world applications were investigated. A broadband low profile (circular) antenna was successfully simulated showing the benefit of the conformal FDTD method compared to the conventional scheme. Furthermore, a CAD based mobile phone was conformally discretized and successfully simulated showing that the proposed scheme is highly suited for the simulation of advanced engineering problems. Index Terms--Conformal finite-difference time-domain (CFDTD) method, finite-difference time-domain (FDTD) method, subcell.

Recently, there has been an increased interest in the problem of wave transmission through sub-wavelength apertures, following successful experimental demonstration by several groups for enhancing optical power transmission through nano-scale holes in metallic screens due to properly designed periodic corrugation. Oliner, Jackson, and their co-workers explained and justified this phenomenon as the result of the excitation of the leaky waves supported by the corrugated screen. Here we discuss in detail the mechanism and analysis for another setup we have recently proposed, in which metamaterial layers with special parameters may be utilized as covers over a single sub-wavelength aperture in a perfectly electric conducting (PEC) flat screen in order to increase the wave transmission through this aperture, and we provide a detailed physical insights and analytical explanation for this aperture setup that may lead to similar, potentially even more pronounced effects when the proper metamaterial layers are used in the entrance and the exit face of the hole in the flat PEC screen with no corrugation. Some numerical results confirming this theory are presented and discussed. We also investigate the sensitivity of the transmission enhancement to the geometrical and electromagnetic parameters of this structure. Index Terms--Aperture coupling, aperture enhancement, leaky wave, metamaterials, polariton, sub-wavelength aperture.

The paper presents a method of the evaluation of capacitance of paraboloidal and spherical bowl using the method of moments based on pulse function as the basis function and point matching for testing. The analysis is carried out on dividing the surface into curvilinear rectangular and triangular subsections. Numerical data on capacitance are presented. Index Terms - Capacitance evaluation, isolated paraboloidal bowl, moment method, sperical bowl.

A new model was developed for the calculation of the nonlinear polarization and the intensity of the second harmonic radiation in the case of the metallic surfaces. The radiation is a result of two currents, one from the rapid variation of the normal component of the oscillating electric field and one from the action of the Lorentz force on conduction electrons. An accurate calculation of these currents was shown possible if adiabatic and Thomas-Ferni assumptions were considered.

Auger electron spectroscopic studies of the concentrations of sulfur in OFHC copper show that at concentrations around 10 a/o, the contact resistance values increase. Exposure of the sample to air leads to disappearance of sulfur and formation of an oxide film that enhances the contact resistance. Depending on the quantity of cold work done on the specimen, the thermal kinetics of sulfur segregation varies.

We have studied the morphology, structure and magnetism of Fe films thermally deposited on stepped Cu(111) by scanning tunnelling microscopy (STM), low energy electron diffraction (LEED) and magneto-optical Kerr effect (MOKE). At room temperature, in the submonolayer range Fe films grow as quasi one-dimensional stripes along the upper step edges due to a strong decoration effect. Between 1.4 and 1.8 monolayer coverage the stripes percolate and become two-dimensional films. Between 2.3 and 2.7 monolayer coverage the films undergo a structural transition from fcc(111) to bcc(110) with Kurdjumov-Sachs orientation. In the fcc range the films have a low net magnetic moment, and a perpendicular easy magnetization axis. The magnetization switches to an in-plane high-moment phase correlated with the fcc to bcc structural transformation. Index Terms - Stepped metal surfaces, ultra thin film growth and magnetism

The Fachgebiet Raumfahrttechnik is working on the field of hypervelocity particle accelerators based on the electrothermal and the electromagnetic principle. All these accelerators generate a hypervelocity plasma pulse that also can be used for surface treatment and modification of metals and alloys. The facilities and pulsed power sources used up to now, however, are not adapted nor optimized for the special needs of the surface treatment application. Therefore, an entire new system was designed, built and taken into operation. Besides the mere realization of all technical requirements and aspects, a major objective was the development of a user friendly industrial-like demonstrator facility. Based on the experience of pulsed power system design and surface treatment application, we implemented the mono-pulse technique using the latest developments by ABB in the field of semiconductor switches and diodes. The pulsed power supply consists of two 25 kJ modules with high power thyristors and self-blocking diodes that generate a single half-wave current pulse of up to 200 kA with a length of about 50 [micro]s. The paper describes the overall system with special emphasis on the pulsed power modules. The proper functioning of the electrical system was documented in extensive check-out tests. Finally, first surface modification experiments were conducted with the new facility to show its capability in this field. Index Terms--Acceleration, capacitor discharge, plasma generation, semiconductor switching technology, surface modification.