A maximum neural network algorithm for route selection problems in multihop radio networks

In a multihop radio network, packets are transmitted from course nodes to destination nodes by activating several links between nodes. Each node can either send a packet to, or receive a packet from, at most one of its adjacent nodes simultaneously. To minimize the transmission time for given requests, the problems must be solved by selecting a transmission route for each request (the routing problem) and by finding a link activation schedule (the link activation problem). The routing problem is decomposed into two subproblems: the candidate extraction problem and the route selection problem. In this paper, we propose a neural network algorithm using the maximum neuron model for the route selection problem. We verify through simulations that our algorithm finds better solutions in a shorter time than the existing algorithms. We also probe the NP‐hardness of this problem. © 1999 Scripta Technica, Electr Eng Jpn, 129(2): 78–86, 1999     

The fracture toughness measured on sensitized 304 stainless steel in simulated reactor water

The environmental conditions chemically equivalent to BWR primary water, e.g. 288°C, 0.2 ppm O₂ and/or 98°C, air-saturated, were found to influence considerably the in-water fracture toughness values of furnace-sensitized Type 304 stainless steel.Notched compact tension and three point bend specimens sampled from two heats of standard materials (0.06% C) showed significant reduction in dJ/da values reflecting consistently the effects of loading rate, temperature, dissolved oxygen concentration and degree of sensitization. In particular the crack enhancement with lowering the loading rate was significant. The effect became apparent with dJ dt at and below 1× 10−1 kg·mm/mm²/min (1.6 × 10 J/m²/s) in the typical BWR environment.Based on the results, it is suggested that a critical consideration is needed on the significance of such an environmental effect in the LWR structural safety evaluation, in particular that the probability of instable fracture at the “rings” of sensitized material near welded joints is subject to reviewing.     

InSb-added TiO2 nanocomposite films by RF sputtering

This study investigates the preparation of InSb-added TiO₂ nanocomposite films by RF sputtering. The optical absorption spectra are obviously shifted to visible and near-infrared regions. High-resolution transmission electron microscopy indicates that sphere-shaped InSb nanocrystals with a size of about 15 nm are dispersed in a matrix. The X-ray diffraction result reveals that the matrix forms a phase mixture of TiO₂ and In₂O₃, which is also produced by decomposing the InSb during postannealing at 723 K. Therefore, the absorption shift is clearly due to quantum size effects of the InSb nanocrystals embedded in the wide-gap oxides TiO₂ and In₂O₃.     

Compositional optimization of magnetite thin films prepared by rf sputtering from a composite target of wüstite and Ge

This study investigated the compositional optimization of magnetite (Fe₃O₄) thin films containing a small amount of Ge to enhance magnetization. No substrate bias was applied during deposition. In a pure Ar atmosphere, the film structure changed from the phase mixture of magnetite and wüstite (Fe_1 − xO) to the weak appearance of wüstite with increasing Ge content. The antiferromagnetic wüstite thus obtained was employed as a starting material to prepare single-phase magnetite, and a gas mixture of Ar and O₂ was then applied. Single-phase magnetite thin films exhibit ferrimagnetic behavior with maximum magnetization of 0.42 T at 1196 kA m⁻¹(15 kOe), which exceeds that of a composite target of ceramic magnetite with Ge chips. Simultaneously adding Ge to the iron-excess wüstite target therefore effectively enhanced magnetization.     

Microbial community analyses using a simple, rapid detection method for DNA fingerprints with a fluorescence scanner

A simple detection procedure was developed for terminal restriction fragment length polymorphism and ribosomal intergenic spacer analysis for microbial community analysis. A fluorescence scanner enables generation of fingerprinting data in these methods within 3 h of obtaining PCR products of microbial communities.     

Mechanisms and kinetics of C4AF hydration with gypsum

The mechanisms and kinetics of early stage C₄AF hydration with gypsum was studied by measuring the heat of hydration with a conduction calorimeter. The heat of the reaction was 173 cal/ g-C₄AF. The reaction equation was estimated to be

$\text{C}{}_4\text{AF}\text{+ 4}\text{CaSO}{}_4\text{·2}\text{H}{}_2\text{O}\text{+ 35}\text{1}\text{3}\text{H}{}_2\text{O}\text{→}\text{4}\text{3}\text{C}{}_3\text{(}\text{A}{}_{0.75}\text{,}\text{F}{}_{0.25}\text{)·3}\text{C}\text{S}\text{H}{}_{31}\text{+}\text{2}\text{3}\text{FH}{}_3$

The equation for rate of hydration was ζ = 0.25t as the thickness (ζ) or hydrated C₄AF increased from 0 to 0.6 μm.     

Vibrational Spectra of Ca3SiO5: Ultraviolet Laser Raman Spectroscopy at High Temperatures

The Raman spectra of Ca₃SiO₅ have been successfully obtained at temperatures up to 1353 K by a continuous-wave ultraviolet Raman spectroscopic system. The Raman spectra do not change significantly with an increase in temperature, despite triclinic ( T )→monoclinic ( M )→rhombohedral ( R ) transitions. The present result is described in terms of the parameter related to temperature variation at constant pressure, defined in a manner similar to the Gruneisen parameter. Raman bands located above 350 cm⁻¹ show smaller values of the parameter than lower frequency modes, suggesting that these higher frequency modes are assigned to SiO₄ internal modes.     

Hydrazinodeoxycellulose for collection of metal ions from aqueous solution

We measured ellipsometrically the adsorption of polystyrene and polymethylmethacrylate on high-vacuum-vapoured chromium-, platinum- and gold-mirrors from various solvents under variation of the molecular weight of polymers. For both polymers we find an increase in thickness and adsorbed amount with an increase in polymer-concentration of solution. The concentration of the adsorbed polystyrene-film decreases, the concentration of the adsorbed polymethylmethacrylate-film increase with the polymer concentration of solution. Molecules of high molecular weight produce bigger thicknesses and adsorbed amounts than molecules of low molecular weight. With increasing polarity of the adsorbent we find an increase of thickness and amount of the adsorbed layer and a decrease of concentration. An increasing polarity of the solvent results in a decrease of thickness and amount and in an increase of concentration of the adsorbed layer. In saturation the polystyrene-molecules adsorb in the conformation of statistical coils. For the polar PMMA-molecules we find a divergent behaviour of the adsorption as a result of the strong interactions between the polar polymer-segments.     

Hydration of tetracalcium aluminoferrite in presence of lime and sulfates

The first part of the paper describes conduction calorimetric and SEM studies of the initial first hour hydration of C₄AF and C₃A with water and saturated solutions of lime, gypsum and gypsum with lime. Lime accelerates while gypsum and gypsum with lime strongly retard the hydration of C₄AF. In case of C₃A, the effect is less pronounced. The second part deals with the hydration of C₄AF at later stages in presence of various additives and the same results as above are obtained. Anhydrite has very little influence while the presence of C₃A reduces the effect of gypsum and hemihydrate on hydration of C₄AF. A detailed investigation of the hydration process by means of X-RD, DTA, SEM and calorimetry has also been made.     

Effective Utilization of Concrete Sludge as Soil Improvement Materials

The amount of muddy soil generated from various kinds of construction sites is always problematic. It is very difficult to treat muddy soil because of its low strength and high water content. But, the reuse of muddy soil is necessary to reduce the total amount of industrial wastes. Surplus concrete is also in a similar situation. Coarse and fine aggregates are removed from surplus concrete as an intermediate treatment, however, concrete sludge still remains. The authors propose a reuse method that involves the muddy soil being mixed with concrete sludge as an improvement material. The possibility of the utilization of concrete sludge was investigated through laboratory experiments. As a result, it was found that the unconfined compressive strength of the improved soil mixed with concrete sludge increased as the curing proceeded.