FIDAS: Detailed subchannel analysis code based on the three-fluid and three-field model

The Film Dryout Analysis Code in Subchannels, FIDAS, has been developed with the main objective of predicting dryout and post-dryout heat transfer in a channel and in rod bundles. In FIDAS, two-phase flow consisting of continuous liquid film, continuous vapor and entrained droplets is modeled by a three-fluid, three-field representation of 12 field equations, i.e. three continuity, three energy and six momentum equations. FIDAS can predict dryout without any empirical CHF correlations by introducing annular flow modeling and the ‘film dryout criterion’. Experiments on film flow characteristics, subchannel flow and enthalpy distributions, dryout and post-dryout heat transfer in tubes and rod bundles were analyzed to demonstrate the performance of FIDAS. The predictions of FIDAS are in close agreement with the experiments.     

Photoconductive imaging in a photon scanning tunnelling microscope capable of point-contact current sensing using a conductive fibre probe

A photoconductive photon scanning tunnelling microscope was developed to investigate the point-contact photoconductive properties of condensed matter. In order to detect the current and the optical signal at a local point on a surface, we coated the edge of a bent type fibre probe with indium tin oxide. Thus it was possible to measure both photocurrent and optical property with subwavelength resolution. The performance of the novel microscope was evaluated by analysing an organic thin film of copper phthalocyanine (CuPc), which is known to be an efficient photoconductive material. Photocurrent and current–voltage characteristics were observed at the local point on the CuPc thin films. Furthermore, photoconductive images were obtained with topography and near-field optical imaging using this system. The photoconductive PSTM shows potential in various areas of future optics and electronics.     

A high-density NAND EEPROM with block-page programming formicrocomputer applications

A high-density, 5-V-only, 4-Mb CMOS EEPROM with a NAND-structured cell using Fowler-Nordheim tunneling for programming is discussed. The block-page mode is utilized for high-speed programming and easy microprocessor interface. On-chip test circuits for shortening test time and for evaluating cell characteristics yield highly reliable EEPROMs. The NAND EEPROM has many applications for microcomputer systems that require small size and large nonvolatile storage systems with low power consumption     

Observation of Frequency Down-Shift in a Submillimeter Wave Gyrotron

Frequency down-shift in the initial stage of CW or long pulse operation of a submillimeter wave gyrotron, Gyrotron FU IV, is observed. The shift occurs in a few minutes after turning on the operation and the amount of the shift attains even 0.1 GHz. The observation results are analyzed on the basis of a simple model for heat conduction in the region of a resonant cavity. The frequency shift is explained consistently by expansion of the cavity.     

Global open ethernet (GOE) system and its performance evaluation

This paper presents an overview of global open Ethernet (GOE) architecture as a cost-effective Ethernet-based virtual private network (VPN) solution, and discusses a hardware and software implementation of a prototype system. Three main approaches have been proposed for a VPN solution on metro-area network: resilient packet ring, Ethernet over multiprotocol label switching (EoMPLS), virtual bridged local area network-tag stacking (Q-in-Q). None of these schemes can satisfy the following requirements at the same time: network topology flexibility, affordable network functionalities, low equipment cost, and low operational cost. The proposed GOE system is designed to solve VPN management problems of these approaches with MPLS VPN functionality at a low cost of Ethernet-based solution. The key components of GOE are: 1) a novel GOE tag for high-speed switching and 2) a novel routing and protection module via per-destination multiple rapid spanning tree protocol (PD-MRSTP). Via the analytical performance evaluation of EoMPLS, Q-in-Q, and GOE, we show that the memory cost and the network utilization of GOE is two-three times smaller and 22% higher than the other approaches, respectively. We also have developed a GOE prototype system and obtained the following remarkable hardware and software performance results. The GOE core switch delivered 100% of theoretical maximum throughput (10 G) with zero packet loss even with the field programmable gate array platform, and its 10-G port density is 1.5 times denser than the best currently available products. The GOE switch using PD-MRSTP also delivered a significantly fast protection switching time (1.975 ms), which was significantly faster than legacy Ethernet switches. These performance evaluation results prove that the proposed GOE system can be used as a cost-effective high-performance Ethernet-based VPN solution.     

Examination of the dual‐band microwave wireless access system using radio on fiber technique

The Radio on Fiber (ROF) technique has great potential in wireless communication systems. In this paper, we report on a fundamental examination of microwave wireless access systems based on Radio on Fiber. First, we designed and constructed examination systems by applying dual band (2.4 and 5 GHz) multiservice transmission systems and confirmed that there was sufficient performance through a transmission experiment. Then, application of FP‐LD (Fabry Perot Laser Diode) was considered in order to reduce the system cost, and for the most part degradation of the transmission characteristics was not observed when FP‐LD was used. Finally, a BIDI (bidirectional) module which integrated LD and PD within one package was made to further reduce costs. By measuring the transmission performance, applying the BIDI module to ROF systems was shown to be effective. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 160(4): 32–40, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20471     

High-efficiency enhancement-mode power heterojunction FET with buried p/sup +/-GaAs gate structure for low-voltage-operated mobile applications

This letter describes a successfully developed enhancement-mode double-doped AlGaAs/InGaAs/AlGaAs heterojunction FET with a buried p/sup +/-n junction gate structure for low-voltage-operated mobile applications. The buried p/sup +/-GaAs gate structure effectively reduced on-resistance (R/sub on/) and suppressed drain-current frequency dispersion for the device with high positive threshold voltage, resulting in high-efficiency characteristics under low-voltage operation. The fabricated p/sup +/-gate HJFET exhibited a low R/sub on/ of 1.4 /spl Omega//spl middot/mm with a threshold voltage of +0.4 V. Negligible frequency dispersion characteristics were obtained through pulsed current-voltage measurements for the device. Under a single 2.7-V operation, a 19.8-mm gate width device exhibited a power added efficiency of 51.9% with 26.8-dBm output power and a -40.1-dBc adjacent channel power ratio using a 1.95-GHz wideband code-division multiple-access signal.     

A PWM signal processing core circuit based on a switched currentintegration technique

A highly functional circuit for pulse width modulation (PWM) signal processing is proposed as a core of the A-D merged circuit architecture for time-domain information processing. The core circuit employs a switched-current integration technique as its computing architecture and functions as a linear arithmetic operator, a memory, and also a delaying device of PWM signals. A 0.8-μm CMOS test chip includes 110 transistors plus two capacitors and performs parallel additions and multiplications at the accuracy of 1.2 ns. A cumulative property of the technique allows the circuit to serve as a low-power accumulator that consumes 23% of the energy of the full digital 7-b accumulator. A PWM multiply-accumulate unit and a nonlinear operation unit are also proposed to extend functionality of the circuit. Since the PWM signal carries multibit data in a binary amplitude pulse, these circuits can be favorably applicable to low-voltage and low-power designs in the deep submicrometer era     

Rapidly destructive arthropathy of the hip in siblings

A case of rapidly destructive arthropathy of the hip in male siblings aged 74 and 76 years is reported. Hip joints of the brothers were destroyed 12 and 4 months after the onset of symptoms, respectively. Results of clinical and laboratory examinations did not show any features of neuropathic, inflammatory, or septic arthropathy. Pathologically in both patients, osteoarthrotic changes with small foci of bone necrosis and nonspecific inflammation and moderate amount of hemosiderosis in the synovium were observed.