Design concept of antennas for small mobile terminals and the future perspective

With the progress and rapid increase in mobile terminals, the design of antennas for small mobile terminals is acquiring great importance. In view of this situation, the design concept of antenna systems for small mobile terminals and its future perspective are discussed, referring to the trends in modern mobile communications and the demands for the antenna system. The design concept of antenna systems has changed along with the progress of mobile systems. In the conventional design, the conducting material of the equipment case, existing near the antenna element, is included as a part of the radiator in the antenna system, without regard to whether or not it has been considered. In the latest mobile phones, the design concept has been advanced to aim at improving the antenna's performance, and the treatment of the case, etc., has become a part of this. Some particular considerations for the design are to relieve the degradation of the antenna's performance due to the human-body effect, to overcome the SAR problems, and yet to make the size small. Furthermore, it is now time to proceed to the more-advanced concept, in which implementation of adaptive control and software is considered, even in small mobile terminals. Typical trends in modern communications systems are discussed, and the demands of these trends-which are summarized as down-sizing, function, and intelligence-are taken up for future antenna structures. Small-antenna technology and the application of the integration technology to antenna systems are essential for realizing such future structures.     

Optical and electrical anisotropies of polydiacetylene derivative film aligned by shear stress

The molecular alignment of polydiacetylene (PDA) derivatives and their optical and electrical properties of thin films based on PDA derivatives have been studied. The PDA derivatives were aligned depending on the direction of applied shear stress in the film. From measurements of the polarized absorption and current–voltage characteristics, the optical and electrical anisotropies have been observed, that was discussed by taking the PDA main chain alignment into consideration.     

Analysis of spatial vapor-phase distribution using the LIF method on multi-component fuel

We analyzed the vapor-phase distribution and behavior of each component in multi-component fuel (MCF). Evaporation characteristic of MCF was researched by laser-induced fluorescent (LIF) method. A pulsed Nd-YAG laser was used as incident light, and an experiment was performed in a constant-volume vessel so that optical measurement could be possible. MCF was injected through electronically controlled common rail injector into the vessel. I-octane (C₈H₁₈), n-dodecane (C₁₂H₂₆) and n-hexadecane (C₁₆H₃₄) were selected to be low boiling point (LO-B.P.), mid boiling point (MI-B.P.) and high boiling point (HI-B.P.) components, respectively, and Fuel A, Fuel B and Fuel C, made by compounding those components at different mass fractions, were used as MCF. Experimentation was performed under the conditions that injection pressures were 42MPa, 72MPa and 112MPa, respectively, ambient gas density was 15kg/m3 and ambient gas temperature was 700K. The spatial vapor-phase distribution, dispersion process of mixture, and vaporphase homogeneity were researched. It was ascertained that the vapor-phase of MCF showed stratified distribution and the dispersion of mixture was improved in proportion to the mass fraction of the LO-B.P. component.     

Abnormalities in proliferation and protein synthesis in skin fibroblast cultures from patients with diabetes mellitus

Several aspects of in-vitro cell growth and protein synthesis were assessed in cultures of skin fibroblasts from subjects with juvenile-onset diabetes mellitus (JODM) or adult-onset diabetes mellitus (AODM) and from age-matched nondiabetic controls (C). There was an inverse correlation between increasing age and both the log-phase doubling rate and saturation density at confluence in C fibroblasts. JODM and AODM cells had a reduction in both indices of cell population growth in comparison with age-matched C fibroblasts. Fibroblasts grown in the presence of 0.3 micronM hydrocortisone were stimulated to grow more rapidly and to a greater saturation density. Stimulation of cell division by hydrocortisone accentuated the abnormalities in growth of JODM and AODM fibroblasts. Total protein and collagen synthesis was measured whtn the fibroblasts had grown to confluency in medium with or without hydrocorticone. Hydrocorticone did not produce a significant change in total protein and collagen synthesis per cell by C fibroblasts. Fibroblasts from AODM had a 180 per cent increase in total protein and collagen synthesis in the presence of hydrocortisone. In contrast, total protein and collagen synthesis decreased 40 per cent in fibroblasts from JODM when grown in the hydrocortisone medium. These studies indicate that skin fibroblast cultures from patients with diabetes exhibit abnormalities in cell proliferation. Furthermore, hydrocortisone appears to unmask diffeerences in protein synthesis that distinguish JODM and AODM fibroblasts in culture.     

Nonlinear input-normal realizations based on the differential eigenstructure of Hankel operators

This paper investigates the differential eigenstructure of Hankel operators for nonlinear systems. First, it is proven that the variational system and the Hamiltonian extension with extended input and output spaces can be interpreted as the Ga/spl circ/teaux differential and its adjoint of a dynamical input-output system, respectively. Second, the Ga/spl circ/teaux differential is utilized to clarify the main result the differential eigenstructure of the nonlinear Hankel operator which is closely related to the Hankel norm of the original system. Third, a new characterization of the nonlinear extension of Hankel singular values are given based on the differential eigenstructure. Finally, a balancing procedure to obtain a new input-normal/output-diagonal realization is derived. The results in this paper thus provide new insights to the realization and balancing theory for nonlinear systems.     

GaAs field-effect transistors by selective sulphur-ion implantation

GaAs field-effect transistors without a mesa structure have been fabricated by selective sulphur-ion implantation into Cr-doped GaAs substrates. The transconductance was 16 mS and the maximum oscillation frequency was 30 GHz.