A 1 ns, 1 W, 2.5 V, 32 Kb NTL-CMOS SRAM macro using a memory cellwith PMOS access transistors

While an ECL-CMOS SRAM can achieve both ultra high speed and high density, it consumes a lot of power and cannot be applied to low power supply voltage applications. This paper describes an NTL (Non Threshold Logic)-CMOS SRAM macro that consists of a PMOS access transistor CMOS memory cell, an NTL decoder with an on-chip voltage generator, and an automatic bit line signal voltage swing controller. A 32 Kb SRAM macro, which achieves a 1 ns access time at 2.5 V power supply and consumes a mere 1 W, has been developed on a 0.4 μm BiCMOS technology     

Formal approach to scenario analysis

Scenarios offer promise as a way to tame requirements analysis, but progress has been impeded by the lack of a systematic way to analyze, generate, and validate them. The authors propose such a method and apply it to a simple PBX system. Their method has a formal mathematical base, generates precise scenarios, accommodates change, and keeps users involved in the process     

Correlations between the spread of ventricular activation and map patterns of measured and difference maps

Three kinds of torso surface isopotential maps (measured, simulated, and difference maps) were delineated at every 1.5 (or 3) msec. during the QRS duration from the 85 unipolar lead ECG's led from the surface of a cylindrical torso model filled with perfusate and containing a canine heart undergoing Langendorff's perfusion. These three maps were compared as to the propagation process of ventricular activation obtained from the same heart and close correlations were found between the spread of ventricular activation and the map patterns of measured and difference maps. The difference map mainly reflected the proximity potential at each instant of ventricular activation in QRS duration and, when used in combination with the measured map, it was useful to estimate the spread of ventricular activation, especially around the stage of epicardial breakthrough of the activation front. It was confirmed that the interpretation of the difference map expressed in the present paper would not be misleading even if applied to a difference map obtained in a human torso model experiment.     

The ductile to brittle transition in tin-lead alloys near melting temperatures

Tensile tests were carried out on tin containing up to 2.0 wt pct lead between 160 and 220 °C at strain rates of 8.3 x 10^-3 and 8.3 x 10^-4 s^-1. Both as-cast and heavily deformed samples were examined. The samples exhibited a ductile-brittle transition at a temperatureTDB below the equilibrium solidus temperature of the corresponding alloy.TDB was found to increase with decreasing strain rate and was sensitive to the structure of the test sample. The smooth faceted surface of the brittle failures indicated the presence of a liquid layer at the grain boundaries at failure. Homogenizing the samples prior to testing markedly increasedTDB to near the solidus temperature. Formerly Visiting Scientist, Department of Metallurgical Engineering, University of British Columbia     

Radioactivation of structural material of the superconducting magnet for a fusion reactor

Radioactivation of five types of candidate steel alloys for the structural materials of superconducting toroidal field coils (TFC) of a D-T fusion reactor has been comparatively studied. As a result, the use of a high Mn steel in place of 316 SS is shown to reduce the dose rate at the He vessel of the TFC to ～ 1/3 the value with 316 SS at 1 day after shutdown, and to ～ 1/1000 at 10 years after shutdown. These reductions are mostly caused by the 0.28 wt% Co assumed to be included in 316 SS but none in the high Mn steel. Newly defined dose rate sensitivities of constituent elements are shown to be useful in identifying the cause of dose rate change brought on by the steel composition change. They can also be utilized in estimating the dose rate change brought on by the replacement of 316 SS with any new steel alloy with similar composition.     

Inhibition effect of CO on hydrogen permeability of Pd–Ag membrane applied in a microchannel module configuration

The surface adsorption effect of CO on the hydrogen permeability of a 12.5 micron-thick Pd₇₇Ag₂₃ membrane has been evaluated quantitatively under experimental conditions close to the operating conditions of the highly-efficient membrane reformer (MRF) system developed by Tokyo Gas. The permeability of the membrane was measured in the conditions of CO concentration between 1 and 5 vol.% at a temperature and pressure of up to 500 °C and 0.6 MPa, respectively. High feed flow rates and a microchannel module configuration were applied in the flux measurements to ensure that the results are obtained with limited influence of concentration polarization adjacent to the membrane surface and hydrogen depletion along the microchannel length. While the CO inhibition effect was close to negligible at 500 °C, it was significant at lower temperatures. At a feed pressure of 0.2 MPa, the CO inhibition effect was only 0.2% at a CO concentration of 1 vol.% and the effect was 3.6% at a CO concentration of 5 vol.% at 500 °C. The CO inhibition effect were 3.4% for 1 vol.% CO and 14.1% for 5 vol.% CO at 400 °C. Measurements were also carried out at a high feed pressure of 0.6 MPa to evaluate the pressure dependence of the CO inhibition effect. The CO inhibition effect decreased to 0.7% at a CO feed concentration of 5 vol.% at 500 °C. Lower CO inhibition effect were also observed at 450 and 400 °C compared to the data obtained with the feed pressure of 0.2 MPa, while the inhibition levels were almost the same at 350 °C. Though the CO inhibition effect is larger at a lower feed pressure of 0.2 MPa, the effect was only 0.2% at 1 vol.% CO at 500 °C, which is close to the operating conditions of the MRF system. This study quantitatively revealed that the CO inhibition effect on hydrogen flux is extremely small when the membrane is operated at temperatures equal to or higher than 500 °C, even for state-of-the-art thin membranes. The performance of the Tokyo Gas MRF seems thus mainly limited by concentration polarization effects.     

Quantitative source identification of dioxin-like PCBs in Yokohama, Japan, by temperature dependence of their atmospheric concentrations

The source and environmental behavior of dioxin-like polychlorinated biphenyls (PCBs) together with other PCBs and polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDDs/PCDFs) were evaluated based on analysis of variations in their atmospheric concentrations in Yokohama, Japan. Potential factors responsible for variations in the atmospheric concentrations of the congeners were investigated by principal component analysis and multiple regression analysis of the data. Two major variations were seen: one had strong temperature dependence, while the other had no significant temperature dependence. A possible explanation for this difference is that the former is related to congeners released by volatilization (e.g., volatilization from commercial PCB products and past polluted environments), while the latter is related to congeners emitted from thermal processes. The relative contributions of dioxin-like PCBs released by volatilization and those emitted from thermal processes were estimated based on the temperature dependence of the atmospheric concentrations. The results suggest that both dioxin-like PCBs emitted from thermal processes and those released by volatilization are significant sources of air pollution in this area in terms of the toxic equivalent (TEQ) for dioxin-like PCBs. We demonstrated that the present approach based on variations in atmospheric concentrations can be useful in providing a qualitative as well as quantitative understanding of source information.     

Identification of a novel nuclear localization signal in Sam68

Landmarks in the development of treatment of retinal detachment include the recognition of the significance of retinal breaks that resulted in the distinction between rhegmatogenous retinal detachment (RRD) and exudative retinal detachment, the development of indirect ophthalmoscopy and scleral depression that allow better visualization of the peripheral area of the retina and better identification of retinal breaks, the recognition of the need to seal all retinal breaks, and the realization that vitreous traction is the major underlying cause of retinal tears and RRD. Scleral buckling procedures combine retinopexy to provide a scar around retinal breaks to seal them and scleral indentation to neutralize vitreous traction; they provided the first effective treatment of RRD. As surgeons gained experience with scleral buckling, they became aware that some RRDs, particularly those with fixed folds and/or a funnel configuration, often could not be repaired using this approach. It was thought that excessive vitreous traction was at fault, and the condition was called "massive vitreous retraction."