Guest Editors' Introduction: Haptic User Interfaces for Multimedia Systems

The guest editors talk a little about haptic interfaces and give an overview of the articles for this special issue.     

Activation process-dependent characteristics of novel thermionic oxide cathodes for CRT application

The emission and conductivity characteristics of oxide cathodes depend largely on the activation process. In this paper, the electrical properties of new type of oxide cathodes for cathode ray tube (CRT) application, supplied by LG Philips Displays, have been investigated in relation to different cathode activation regimes. The influence of the activation process over different durations has been investigated. A temperature of T=1425 K was chosen to be higher than the optimum cathode activation temperature (T=1200 K), and the other temperature of T=1125 K was lower than that. The electron activation energy (E) was found to vary in the range from 0.58 to 2.28 eV for cathodes activated at the higher temperature regime, and from 1.08 to 1.9 eV for those activated at the lower temperature regime. Scanning electron microscopy (SEM) and electron diffraction X-ray (EDX) analyses show a structural phase transformation in the oxide material that was activated at 1125 K for a period of 1-12 hours. The SEM mapping shows a large contamination of Ba in the top layer of oxide material. The activator agents tungsten and aluminum are found to penetrate into the BaO/spl bsol/SrO layer in two different ways.     

An array-compensated spherical reflector antenna for a very large number of scanned beams

There are many stringent demands imposed on the applications of spaceborne antenna systems. One of the most challenging demands is the generation of multiple beams with the ability to scan a very large number of beamwidths. Since the parabolic reflectors have limitations in this application, a 35-m spherical reflector antenna is proposed for a geostationary radar antenna at Ka-band (35.6 GHz) due to its inherent capability of scanning the beams to very large number of beamwidths. The utility of using planar array feeds for correcting spherical phase aberrations is investigated to overcome the performance degradation effects. Two different methodologies are developed for the array excitation coefficients determination based on phase conjugate matching and the results are compared. Using the compensating feed array, the radiation characteristics of the compensated spherical reflector are simulated for no scan and large scan cases and the results are compared with the uncompensated case to show performance improvement. In order to demonstrate the technological readiness of the concept a 1.5-m breadboard model is designed to be built for experimental measurements. Some important mechanical design tolerances and realistic array feed topologies are investigated. The antenna concept developed in this paper is advocated to be used in the next generation of geostationary satellite antenna systems for remote sensing radar applications.     

Fiber-optic devices for local area network application

Recent developments on fiber-optic devices are reviewed from the local area network (LAN) application viewpoint. Future technical trends are also discussed, along with current research activities. In local area network systems, low device cost and easy maintenance or maintenance-free devices are especially required. Light sources and photodetectors suitable for the systems are described. InGaAsP/InP light emitting diodes can cover a broad application field, up to a gigabits per second super high-speed network region. Optical passive devices, which include branching couplers, switches and connectors, are mentioned as essential components. Compact transmitter/receiver module technology is a key factor in realizing optical-fiber local area network systems. An example of 200-Mbit/s transmitter/receiver module is reported.     

Conditional Time Before Ruin of an Insurance Company

The statistical characteristics of conditional time before ruin of an insurance company, including the distribution function of conditional time and its moments are examined.     

Monolithic 2.1 Gbit/s decision circuit with a decision threshold ambiguity width of less than 10 mV

An Si bipolar monolithic decision circuit for practical use is developed using an improved circuit technique and super self-aligned process technology with the reliable 1.25 ?m rule. The circuit consists of a slice amplifier, a master-slave D flip-flop and an output buffer. This circuit is capable of operating up to 2.1 Gbit/s with a decision threshold ambiguity width of less than 10 mV. In addition, a clock phase margin of 250 degrees and power dissipation of 640 mW at VEE=?6 V can be achieved.