Titanium nitride precipitation behavior in thin-slab cast high-strength low-alloy steels

To assess the potential for obtaining and utilizing titanium nitride (TiN) refinement via the increased postsolidification cooling rates associated with thin-slab casting, TiN particle size distributions were evaluated by transmission electron microscope (TEM) examination of carbon extraction replicas. Eight commercially produced thin-slab cast TiN steels, nominally 0.05 pct C, 1.2 pct Mn, and one conventionally cast steel were received. Thin slab samples were taken from three locations in the production process: quenched after casting before the tunnel furnace, quenched after tunnel furnace soaking, and the as-rolled and air-cooled final product. Effects of cooling rate were evident in the results and agree with previously documented behavior, where precipitate size decreases with increased cooling rate. Statistical differences in particle size between specimens from steels with different chemistries were shown. These variations result from differences in the driving force for precipitation, rates of coarsening, and differences in volume fraction due to changes in steel composition. The interaction of composition and processing, such as soaking in the tunnel furnace and rolling, was found to be important. For example, the hyperstoichiometric steel (excess Ti) exhibited fine TiN after casting and soaking, but dramatic coarsening after hot rolling. This behavior was attributed to deformation enhanced particle coarsening, or incomplete precipitation after soaking, followed by continued growth during subsequent processing.     

Reliability of nonhermetic bias-free LiNbO/sub 3/ modulators

Reliability for nonhermetic bias-free LiNbO/sub 3/ optical modulators is estimated from aging data in both dry and damp heat conditions. The two dominant failure modes for these devices are: 1) device performance degradation due to temperature-activated drift of the annealed proton-exchange waveguide; and 2) optical insertion loss increase due to humidity-induced deterioration of glued fiber joints. A total failure rate of 30 failures in time (FITs) is predicted for 20 years operation at 45/spl deg/C and moderate humidity conditions (40% RH). This estimate based on laboratory-test data is consistent with a field failure rate <5 FITs observed in fielded devices.     

Mobile robot control by neural networks using self-supervisedlearning

A reinforcement learning algorithm based on supervised learning is described. It uses associative search to discover and learn actions that make the system perform a desired task. One problem with associative search is that the system's actions are often inconsistent. In the searching process, the system's actions are always decided stochastically, so the system cannot perform learned actions more than once, even if they have been determined to be suitable actions for the desired task. To solve this problem, a neural network that can predict an evaluation of an action and control the influence of the stochastic element is used. Results from computer simulations using the algorithms to control a mobile robot are described     

Electrochemical noise analysis for estimation of corrosion rate of carbon steel in bicarbonate solution

We have investigated the electrochemical noise behavior of carbon steel in fully deaerated aqueous bicarbonate solutions, and discussed the optimum conditions of the noise analysis for estimating corrosion rate of the steel. Noise of the potential difference and of the short-circuit current between two identical steel coupons were successfully measured. The time-series noise patterns were transformed into frequency domain by fast Fourier transformation, and then their power spectrum densities (PSDs) at a frequency were determined to be compared with the corrosion rate. The PSDs of the potential and of the current varied with changing environmental factors of bicarbonate concentration, pH, and immersion time. The factors also controlled the corrosion rate of the steel. The PSDs were associated with the corrosion rate, and then it was found that the PSDs of the potential and of the current showed linear correlation with the corrosion rate in log-log scale. There was also linear relationship between the corrosion rate and a spectral noise resistance obtained from the PSDs of the potential and the current. The linearities of the three correlations were better at a lower analyzed frequency. Furthermore, the PSDs of the current and the noise resistance indicated more linear correlation with the corrosion rate than that of the potential. As the simplicity of the measurement system is additionally considered, it is concluded that the PSD of the current noise at an analyzed frequency of 3 mHz is the optimum conditions for estimating the corrosion rate from 10⁻² to 10⁰ A m⁻² in this study.     

Aprotinin reduces homologous blood transfusions when pediatric cardiac surgery must be redone

The hemostatic effect of aprotinin in pediatric cardiac surgery is controversial. This study demonstrated the usefulness of aprotinin in cases undergoing additional surgery. In a retrospective study, three groups of children were investigated. In group I (n = 10), no aprotinin or Cell saver was used (control). In group II (n = 12), Cell saver was used intraoperatively. In group III (n = 14), aprotinin 30,000 KIU/kg was added to the prime of cardiopulmonary bypass, and another 10,000 KIU/kg was given every hour during extracorporeal circulation. Both blood loss and use of homologous blood during operation were significantly (p < 0.01) reduced in group III compared to those in the other two groups. In group III, blood loss both 12 and 48 hours postoperatively were one-third less than those in group I (no significant difference). The use of homologous blood 48 hours postoperatively was significantly reduced in group III compared to that in group I (p < 0.01) or group II (p < 0.05). We conclude that aprotinin administration during cardiopulmonary bypass reduced blood loss and homologous blood requirements both operatively and postoperatively when pediatric cardiac surgery must be redone.     

Identification of osteopontin in human dental calculus matrix

Osteopontin is a prominent non-collagenous component of bone matrix, although it is expressed in several other tissues. Recently, osteopontin was reported to be involved in urinary stone formation and atherosclerotic lesions of the aorta, suggesting that it may be a key protein associated with these types of pathological mineralization. In this study, whether or not human dental calculus contains osteopontin was investigated by immunoblotting and immunohistochemical analyses. After extraction of calculus proteins with EDTA and separation of the proteins by electrophoresis, immunoblotting analysis revealed the presence of osteopontin. Two forms of osteopontin appeared at 61 and 68 kDa on 10% polyacrylamide gel and the proteins were digested with thrombin, a highly specific protease. Moreover, immunohistochemical analysis revealed that osteopontin was localized in dental calculus adherent to tooth roots. These findings indicate that osteopontin is, in fact, present in human dental calculus and may be involved in calculus formation as the stone matrix.     

Bottom-up multi-agent reinforcement learning by reward shaping for cooperative-competitive tasks

Applied Intelligence - A multi-agent system (MAS) is expected to be applied to various real-world problems where a single agent cannot accomplish given tasks. Due to the inherent complexity in the...     

Heme pigment content in meat as affected by the addition of curing agents

The effects of curing agents on the content of heme pigments (HP) in meat were examined. Minced porcine skeletal muscle was treated with NaCl, NaNO(2) and sodium ascorbate (NaAsA), separately or in combination, and stored at 2-3°C for 7 days. HP content decreased with increase in NaCl concentration and the decrease was about 50% and 80% at NaCl concentrations of 2% and 10%, respectively. Two percent NaCl prevented HP destruction, when previously mixed with 100 ppm NaNO(2) or 0·1% NaAsA. Although some decrease in HP content was noted following application of a mixture of NaCl, NaNO(2) and NaAsA, it was essentially the same as that of the control during 7 days of refrigerated storage. In a model solution containing the same curing agents as those applied to the meat. NaCl had no effect and myoglobin (Mb) content remained constant during storage. From the present results, endogenous muscle constituents appear to act in concert with NaCl to bring about a decrease in HP content.     

Investigation of CH4 Reforming with CO2 on Meso-Porous Al2O3-Supported Ni Catalyst

Meso-porous Al₂O₃-supported Ni catalysts exhibited the highest activity, stability and excellent coke-resistance ability for CH₄ reforming with CO₂ among several oxide-supported Ni catalysts (meso-porous Al₂O₃ (Yas1-2, Yas3-8), -Al₂O₃, -Al₂O₃, SiO₂, MgO, La₂O₃, CeO₂ and ZrO₂). The properties of deposited carbons depended on the properties of the supports, and on the meso-porous Al₂O₃-supported Ni catalyst, only the intermediate carbon of the reforming reaction formed. XRD and H₂-TPR analysis found that mainly spinel NiAl₂O₄ formed in meso-porous Al₂O₃ and -Al₂O₃-supported catalysts, while only NiO was detected in -Al₂O₃, SiO₂, CeO₂, La₂O₃ and ZrO₂ supports. The strong interaction between Ni and meso-porous Al₂O₃ improved the dispersion of Ni, retarded its sintering and improved the activated adsorption of CO₂. The coking reaction via CH₄ temperature-programed decomposition indicated that meso-porous Al₂O₃-supported Ni catalysts were less active for carbon formation by CH₄ decomposition than Ni/-Al₂O₃ and Ni/-Al₂O₃.