A 12 MHz data cycle 4 Mb DRAM with pipeline operation

A 12 MHz data-cycle 4 Mb DRAM (dynamic RAM) with pipeline operation was designed and fabricated using 0.8 μm twin-tub CMOS technology. The pipeline DRAM outputs data corresponding to addresses that were accepted in the previous inverted random access storage (RAS) input cycle. The latter half of the previous read operation and the first half of the next read operation take place simultaneously, so the inverted RAS input cycle time is reduced. This pipeline DRAM technology needs no additional chip area and no process modification. A 95 ns inverted RAS input cycle time was obtained under worst conditions while this value is 125 ns for conventional DRAMs     

Decomposition of chlorofluorocarbons in the presence of water over zeolite catalyst

The decomposition of chlorofluorocarbons (CFCs) in the presence of water was examined over a variety of solid acid catalysts. More than 40% of the conversion of CFC was observed on HY zeolite, H-mordenite, H-ZSM-5, γ-Al₂O₃, and SiO₂TiO₂ catalysts, and the selectivity to CO and CO₂ was nearly 100% except on γ-Al₂O₃. Although the H-mordenite had the highest activity among the tested catalysts, it was gradually deactivated during the reaction due to the elimination of Al atoms from the zeolite framework. A good relationship was found between the reactivity on H-mordenite and the bond energy of CCl in compounds of CCl₄, CCl₃F, CCl₂F₂, and CClF₃, suggesting that the rate controlling step was the cleavage of the CCl bond.     

Property of upgraded solid product from low rank coal by thermal reaction with solvent

The upgrading process for the production of clean solid fuel from subbituminous and brown coals is receiving current attention. We propose upgrading of low rank coal with solvent at 350–450 °C under 2 MPa of initial nitrogen atmosphere. Upgrading of German Fortuna brown coal (heating value: 25.4 MJ/kg, daf) at 440 °C in the presence of t-decalin gave 66 wt.% of solid products with heating value of 35.4 MJ/kg, daf. Gaseous product consisted of mainly carbon dioxide (80 wt.%) and methane. Therefore, cracking of carboxylic functional group took place effectively in this condition. Ignition temperature of the upgraded solid product, measured by thermogravimetry under airflow, increased to higher than 400 °C, while raw brown coal showed corresponding temperature of 290 °C. From the XRD patterns by X-ray diffractometry for the upgraded product, distribution of aromatic stacking layer number (N) shifted to larger N by upgrading with solvent. It is obvious that the effective carbonization occurs under these conditions. This suggests the possibility to produce value-added solid fuel or carbonaceous liquid and solid chemicals, from low rank coal, whose quality is comparable to the bituminous coal.     

Synergistic catalysis of carbon black oxidation by Pt with MoO3 or V2O5

A series of SiO₂-supported MoO₃, V₂O₅, and Pt catalysts were prepared for the study of model soot oxidation with simulated diesel exhaust gas. Composite samples of Pt with the metal oxides demonstrated higher oxidation activities than the single-component SiO₂-supported MoO₃, V₂O₅ or Pt catalysts in the absence of SO₂ in the reactant gas. Based on the effects of NO₂ on carbon oxidation, a synergistic reaction mechanism was suggested to explain the effects of combining Pt with the oxides: Pt catalyzes the oxidation of NO with gas phase O₂ to NO₂, while MoO₃ and V₂O₅ catalyze the oxidation of carbon with NO₂. Finally, the effects of SO₂ on the carbon oxidation reaction were examined and discussed.     

Decomposition of benzene using a nonthermal plasma reactor packedwith ferroelectric pellets

The decomposition of benzene in air was carried out using a nonthermal plasma discharge reactor packed with ferroelectric materials. It was found that ferroelectric materials of 1-2 mm in diameter with a relative dielectric constant of ϵ_r>1100 decomposed benzene with greatest energy efficiency. Benzene at low concentrations (below 50 ppm) was completely decomposed to CO and CO₂ with no formation of other hydrocarbons. The ratio of CO to CO₂ produced from benzene was minimized under an atmosphere containing more than 5% O₂     

A 1.6-GByte/s DRAM with flexible mapping redundancy technique andadditional refresh scheme

We implemented 72-Mb direct Rambus DRAM with new memory architecture suitable for multibank. There are two novel schemes: flexible mapping redundancy (FMR) technique and additional refresh scheme. This paper shows that multibank reduces redundancy area efficiency. But with the FMR technique, this 16-bank DRAM realizes the same area efficiency as a single-bank DRAM. In other words, FMR reduces chip area by 13%. This paper also describes that additional refresh scheme reduces data retention power to 1/4. Its area efficiency is about four times better than that of the conventional redundancy approach     

Decomposition of benzene using alumina-hybrid and catalyst-hybridplasma reactors

In order to investigate the effects of alumina and metal ions in plasma discharge, plasma reactors packed with a mixture of BaTiO₃ pellets and porous Al₂O₃ pellets (alumina-hybrid reactor), and with a-mixture of BaTiO₃ pellets and metal-supported Al₂O₃ pellets (catalyst-hybrid reactor) were examined for oxidation of dilute benzene in air. It was found that the oxidative decomposition of benzene was enhanced by concentrating benzene on the Al₂O₃ pellets and the catalyst pellets. Furthermore, the selectivities to CO ₂ in the alumina-hybrid reactor and the catalyst-hybrid reactors were higher than those in the plasma reactor packed with BaTiO ₃ pellets alone. In particular, the selectivities to CO₂ in the catalyst-hybrid reactors using Ag, Co, Cu and Ni/Al₂ O₃ were higher than those from the alumina-hybrid reactor. In addition, the presence of the alumina and catalysts suppressed the formation of N₂O     

Removal of dilute benzene using a zeolite-hybrid plasma reactor

The decomposition of benzene was carried out using a plasma reactor packed with a mixture of BaTiO₃ and zeolite pellets, the zeolite-hybrid reactor. The reactor performance was characterized by measuring CO_x formed during plasma discharge and CO_x adsorbed on the solid surface, The decomposition efficiency of benzene in the hybrid reactor was 1.4-2.1× higher than that in a conventional plasma reactor packed with BaTiO₃ alone. Benzene existing outside a zeolite crystalline pore was found to decompose more easily than that inside a zeolite pore. In addition, the presence of zeolites suppressed the formation of NO_x     

Oxidation of carbon black over various Pt/MOx/SiC catalysts

Catalytic activities of various Pt/MO_x/SiC systems for carbon oxidation under simulated diesel exhaust gas were investigated in temperature-programmed reactions. When Pt/MO_x (MO_x=TiO₂, ZrO₂, Al₂O₃) was loaded onto silicon carbide (SiC), the oxidation activities became higher than those of Pt/MO_x alone or other Pt/MO_x/SiC systems (MO_x=Ta₂O₅, WO₃, Nb₂O₅, SnO₂, SiO₂, CeO₂, MoO₃, V₂O₅). Among them, Pt/TiO₂/SiC exhibited the highest activity. We discuss the activity of MO_x=TiO₂, ZrO₂, and Al₂O₃ in connection with NO oxidation activity, adsorption of sulfate onto the support, Pt dispersion, and specific surface area of the catalyst. Furthermore, we investigated the catalytic performance of Pt/TiO₂/SiC in more detail under isothermal conditions and in a staged arrangement.     

An experimental 295 MHz CMOS 4K×256 SRAM using bidirectionalread/write shared sense amps and self-timed pulsed word-linedrivers

An experimental 4 K word by 256 b CMOS synchronous SRAM employing read/write shared sense amplifiers and self-timed pulsed word-lines is described. The read/write shared sense amplifier allows the RAM to have 256 I/Os and the self-timed pulsed word-line scheme reduces power consumption. Fully differential I/O buses, laid out in fourth metal over the memory cell arrays, use a 0.3 V differential swing. The SRAM is fabricated in a 0.35 μm four-layer metal CMOS process employing a 6-T SRAM cell measuring 5.2 μm×6.6 μm. The die measures 13.22 mm×4.80 mm. The SRAM operates at 295 MHz with a 3.3 V supply, achieving a bandwidth of 9.44 Gbyte/s