Key Engineering Materials Vol. 459

Abstract: The modified Smith predictor is well known as an effective time-delay compensator for a plant with large time-delays, and several papers on the modified Smith predictor have been published. The parameterization of all stabilizing modified Smith predictors for single-input/single-output time-delay plants is obtained by Yamada et al. However, they do not examine the parameterization of all stabilizing modified Smith predictors for multiple-input/multiple-output time-delay plants. The purpose of this paper is to expand the result by Yamada et al. and to propose the parameterization of all stabilizing modified Smith predictors for multiple-input/multiple-output time-delay plants. Control characteristics of the control system using obtained parameterization of all stabilizing modified Smith predictors are also given. Finally, a numerical example is illustrated to show the effectiveness of proposed parameterization of all stabilizing modified Smith predictors.

Abstract: A novel linked thermoelectric system (LTES), fabricated by a simple structural modification of a conventional thermoelectric system (CTES) with the use of conductive metal rods, is characterized experimentally. The LTES generates higher power to the external load in comparison with the CTES, and the power increases with increasing length of the metal rods when the low temperature side of the system is set in the air at room temperature. In addition, measurements of Seebeck voltages of both the systems indicate that the Seebeck coefficient of thermoelectric materials in the LTES is about 1.2 times higher than that in the CTES.

Abstract: This paper proposes new architectures for envelope-tracking power supplies for base stations. (1) The proposed multiphase DC-DC converter circuit uses multiple switching circuits with hysteresis comparators (as well as a voltage follower circuit), each optimized for a different envelope frequency, to realize both high efficiency and wide bandwidth. (2) We also propose the one using interleaved PWM switching circuits. The operation of the circuits, and simulation results, are described.

Abstract: In this paper, we propose new pulse-shaping techniques using raised cosine signaling instead of using conventional digital signals (rectangular waves), to reduce Inter-symbol interference (ISI) and crosstalk noise. Unlike a rectangular pulse, the raised cosine pulse takes on the shape of a sinc pulse that minimizes ISI. Also, limited bandwidth of the signal can reduce crosstalk noise. We show the simulation and experimental results of the raised cosine signaling scheme to show the new signaling method plays a critical part in maintaining signal integrity in high-speed VLSI systems.

Abstract: This paper describes a Pulse-Width Modulation (PWM) pre-emphasis technique which utilizes time-domain information processing to increase the data rate for a given bandwidth of interconnection. The PWM pre-emphasis method does not change the pulse amplitude as for conventional FIR pre-emphasis, but instead exploits timing resolution. This fits well with recent CMOS technology trends toward higher switching speeds and lower voltage headroom. We discuss multiple-valued data transmission based on time-domain pre-emphasis techniques in consideration of higher-order channel effects.

Abstract: In order to control a large number of microbubbles with a pumping ultrasonic wave, it is essential to consider a bubble-to-bubble interaction. This paper proposes a simplified microbubble dynamics simulation method considered with bubble-to-bubble interaction in ultrasonic wave field. The microbubble dynamics is solved with difference method based on the Stokes’s low and the secondary Bjerknes force between microbubbles. The laminar flow is considered in the cylindrical calculation region. The effectiveness of the frequency sweep method in laminar flow is shown with simulation results. And a usefulness of this dynamics simulation is also discussed through the experimental result.