On Optimal Redundancy of Multivalue-Output Systems

This paper considers improving the reliability of multivalue-output systems by the use of n-redundant systems in which n copies of systems are used redundantly and the output is determined from the outputs of those copies by the voter. A k-out-of-n redundant system minimizes the mean loss caused by the occurrence of output errors under the condition that the voter can be composed of only two kinds of operators, logical sum and logical product. The optimal k depends on the probability and loss matrices, but it can be specified in some special cases. The mean loss of multivalue-output systems with multichannels can be minimized by adopting k-out-of-n redundancy for each channel. The results provide a powerful guide to the improvement of fail-safe characteristics of many systems and the design of fault-tolerant systems.     

Photochemical Reaction in a Reduced Soda-Lime-Silica Glass Containing Ce3+ and As3

The photochemical reaction between Ce³⁺ and As³⁺ in a reduced 16Na₂O. ¹1CaO.73SiO₂ glass (mol%) was examined by exposing it to an Xe or Hg arc. In addition to Ce⁴⁺, a paramagnetic As(II)OS center having C_2v symmetry and a trapped electron center were identified by ESR. The As(II)O defect is the origin of the unidentified ESR signal which correlates with the discoloration of a borosilicate glass developed for solar energy application .     

Giant thermoelectric Seebeck coefficient of a two-dimensional electron gas in SrTiO3

Enhancement of the Seebeck coefficient (S ) without reducing the electrical conductivity (sigma) is essential to realize practical thermoelectric materials exhibiting a dimensionless figure of merit (ZT=S2 x sigma x T x kappa-1) exceeding 2, where T is the absolute temperature and kappa is the thermal conductivity. Here, we demonstrate that a high-density two-dimensional electron gas (2DEG) confined within a unit cell layer thickness in SrTiO(3) yields unusually large |S|, approximately five times larger than that of SrTiO(3) bulks, while maintaining a high sigma2DEG. In the best case, we observe |S|=850 microV K-1 and sigma2DEG=1.4 x 10(3) S cm-1. In addition, by using the kappa of bulk single-crystal SrTiO(3) at room temperature, we estimate ZT approximately 2.4 for the 2DEG, corresponding to ZT approximately 0.24 for a complete device having the 2DEG as the active region. The present approach using a 2DEG provides a new route to realize practical thermoelectric materials without the use of toxic heavy elements.     

Photodegradation of cellulose acetate film in the presence of benzophenone as a photosensitizer

To study the effectiveness of photosensitizers to accelerate the degradation of cellulose acetate (CA) under ambient environment, CA (degree of substitution = 2.45) films containing benzophenone, which is one of the typical photosensitizers, were prepared and their degradative behavior by photoirradiation was examined. Decrease in molecular weight of CA and generation of carbon dioxide, carbon monoxide, and acetic acid from the CA films were observed by the irradiation of xenon arc lamp light, which was passed through a filter for cutting off the wavelength shorter than 275 nm. With increasing the concentration of benzophenone, the molecular weight of CA decreased and the generation of the degradation products from the CA films increased. These results may suggest that radical reactions of CA films proceed by photoirradiation and lead to oxidation and random cleavage of CA, and that benzophenone is an effective additive to accelerate the degradation of CA under ambient environment. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Excimer laser crystallization of InGaZnO<Subscript>4</Subscript> on SiO<Subscript>2</Subscript> substrate

In this paper, we were able to crystallize InGaZnO₄ (IGZO) by excimer laser on SiO₂ substrate. It was observed that uniform [0001] textured polycrystalline IGZO film has been obtained without any grain boundaries and oxygen vacancies on SiO₂ substrate. This process is very promising in fabricating high quality IGZO thin film transistors (TFT) at low temperature without seed substrate.