Nonstationary electron/hole transport in sub-0.1 μm MOS devices:correlation with mobility and low-power CMOS application

We have experimentally studied the high-lateral-field carrier velocity near the source edge in sub-0.1 μm MOSFETs. It is demonstrated that the high-field electron velocity and hole velocity have universal low-field mobility dependence. This shows that the hole velocity is lower than the electron velocity due to the hole's lower mobility. Moreover, we have investigated the low-power CMOS operation using the velocity overshoot. It is verified that there is a most suitable supply voltage for improving the CMOS operation using velocity overshoot. The most suitable supply voltage is shown to be about 1 V. Therefore, the velocity overshoot will be very useful for low voltage CMOS operation in the future     

Morphology control of goethite acicular particles during aging by nitrogen bubbling and subsequent reactive aeration

Conditions for synthesizing acicular fine particles of goethite with high aspect ratio were devised by oxidizing mixed slurry comprising ferrous carbonate and hydroxide after neutralizing by alkali carbonate. By bubbling N₂ after neutralization into the slurry containing FeCO₃ and Fe(OH)₂, dissolved CO₂ is ejected. As a consequence, the relative concentration of CO₃²⁻ decreases and that of hydroxide increases. These favor the increase of the aspect ratio of the goethite particles via two factors, i.e., (1) decrease in the critical size of the nuclei and (2) suppression of growth inhibition at the tip of needle-like particles due to CO₃²⁻ adsorption. We propose a reaction scheme for the entire processing.     

Verification of the energy-saving effect of the district heating and cooling system—Simulation of an electric-driven heat pump system

A district heating and cooling system (DHC) is expected to be a promising energy-saving measure for high-density business areas in Japan. However, it has not been verified what advantages of the DHC are important for energy conservation. The clarification of this issue is supposed to contribute to improving the energy efficiency of the DHC.     

High-speed and low-driving-Voltage thin-sheet X-cut LiNbO/sub 3/ Modulator with laminated low-dielectric-constant adhesive

We present a novel thin-sheet X-cut LiNbO/sub 3/ optical modulator structure which can be fabricated by precise polishing and lapping to obtain a thinner LiNbO/sub 3/ substrate for a lower driving voltage in addition to velocity matching and impedance matching. We demonstrated that the fabricated modulator had a driving voltage V/spl pi/ of 2 V and zero chirp for 40-Gb/s operation and had a high potential for suppressed dc drift, and long-term reliability.     

High-speed source-heterojunction-MOS-transistor (SHOT) utilizing high-velocity electron injection

We have developed the source-heterojunction-MOS-transistor (SHOT), a novel high-speed MOSFET with relaxed-SiGe/strained-Si heterojunction source structures for quasi-ballistic or full-ballistic transistors. Using the band-offset energy at the source SiGe/strained-Si heterojunction, high velocity electrons can be injected into the strained-Si channel from the SiGe source region. For the first time, we have experimentally demonstrated that the transconductance is enhanced in SHOT for high applied drain voltage, compared to that of strained- and conventional silicon-on-insulator MOSFETs. We have also shown that the transconductance enhancement in SHOT depends on both the gate drive and the drain bias.     

Upward vertical two-phase flow local flow regime identification using neural network techniques

Traditionally, the flow regimes in two-phase flow are considered in a global sense. However, a local flow regime is required to understand and model the interfacial structures present in the flow. In this work, a new approach has been used to identify both global and local flow regimes in a two-phase upward flow in a 50.8 mm internal diameter pipe under adiabatic conditions. In the present method, the bubble chord length distributions, which are measured simultaneously with three double-sensor conductivity probes, have been used to feed a self-organized neural network. The global flow regime identification results show a reasonable agreement with the visual observation for all the flow conditions. Nonetheless, only the local flow regimes measured at the center of the pipe agree with the global ones. The local flow regime combinations found are analyzed using the flow map information, cross-correlations between the probe signals, and previous correlations. In this way, it is possible to identify eight different global flow regime configurations.     

Transport of direct dye into cellulose membrane

The dyeing process for a cellulose membrane–direct dye system is analyzed based on a parallel transport mechanism of surface and pore diffusion with Freundlich isotherm. Numerical solutions were obtained in order to clarify how the surface and pore diffusion resistances affect the uptake curve. The numerical solutions were also compared with an analytical solution for surface diffusion control to establish the range where the analytical solution can be considered as an acceptable approximation. The uptake curves in the cellulose membrane-chromophore (C.I. Direct Yellow 12) system in the presence of inorganic electrolyte were measured. The rate of adsorption and the maximum amount of adsorption increased with an increase in the concentration of those electrolytes. The rate of adsorption was approximately controlled by the surface diffusion rather than by pore diffusion. The surface diffusivities of the dye were little affected by either the concentration and or nature of the electrolyte.     

Millimeter-Wave Radiometer for the Measurement of Stratospheric ClO Using a Superconductive (SIS) Receiver Installed in the Southern Hemisphere

A new sensitive radiometer for atmospheric minor constituents has been developed by Nagoya University and the National Institute for Environmental Studies (NIES). The instrument equipped low-noise superconducting (SIS) mixer with a system noise temperature of ≈200K (SSB) at 204GHz. The SIS mixer is operated in a single side band mode with a side band ratio grater than 10dB by adjusting the two tunable backshorts of the mixer. Since any additional SSB filters are not necessary, we can simplify the quasi-optical system and reduce the standing waves which makes difficult to achieve a flat spectral baseline. We installed the observation system at Las Campanas Observatory, Chile in December 1999, and started the test observation from 2000 October. We have detected significant ClO emission at 204.3 GHz with an actual observation time of only 4 hours. This is the first detection of the ClO at 40km altitude from the mid-latitude region of the southern hemisphere. The Nagoya-NIES system has enabled continuous monitoring of ClO in the stratosphere with a time resolution of 4 or 5 hours.     

Data-driven approach to solve vertical drain under time-dependent loading

Currently, the vertical drain consolidation problem is solved by numerous analytical solutions, such as time-dependent solutions and linear or parabolic radial drainage in the smear zone, and no artificial intelligence (AI) approach has been applied. Thus, in this study, a new hybrid model based on deep neural networks (DNNs), particle swarm optimization (PSO), and genetic algorithms (GAs) is proposed to solve this problem. The DNN can effectively simulate any sophisticated equation, and the PSO and GA can optimize the selected DNN and improve the performance of the prediction model. In the present study, analytical solutions to vertical drains in the literature are incorporated into the DNN–PSO and DNN–GA prediction models with three different radial drainage patterns in the smear zone under time-dependent loading. The verification performed with analytical solutions and measurements from three full-scale embankment tests revealed promising applications of the proposed approach.     

Beer brewing using a fusant between a sake yeast and a brewer's yeast

Beer brewing using a fusant between a sake yeast (a lysine auxotrophic mutant of sake yeast K-14) and a brewer's yeast (a respiratory-deficient mutant of the top fermentation yeast NCYC1333) was performed to take advantage of the beneficial characteristics of sake yeasts, i.e., the high productivity of esters, high tolerance to ethanol, and high osmotolerance. The fusant (F-32) obtained was different from the parental yeasts regarding, for example, the assimilation of carbon sources and tolerance to ethanol. A brewing trial with the fusant was carried out using a 100-l pilot-scale plant. The fusant fermented wort more rapidly than the parental brewer's yeast. However, the sedimentation capacity of the fusant was relatively low. The beer brewed using the fusant contained more ethanol and esters compared to that brewed using the parental brewer's yeast. The fusant also obtained osmotolerance in the fermentation of maltose and fermented high-gravity wort well.