Tapered thickness MQW waveguide BH MQW lasers

We propose and demonstrate a novel 1.3 μm InGaAsP/InGaAsP multiple-quantum-well (MQW) BH Fabry-Perot laser diode monolithically integrated with a MQW tapered thickness waveguide. A selective area growth (SAG) technique is used to fabricate the tapered thickness waveguide with low absorption loss and to integrate it with the MQW gain region with a high coupling efficiency. We achieve very narrow vertical and lateral far-field FWHM of 11.8° and 8.0°, with low threshold current of 19 mA and high slope efficiency of 0.25 mW/mA     

Artificial neural networks for document analysis and recognition

Artificial neural networks have been extensively applied to document analysis and recognition. Most efforts have been devoted to the recognition of isolated handwritten and printed characters with widely recognized successful results. However, many other document processing tasks, like preprocessing, layout analysis, character segmentation, word recognition, and signature verification, have been effectively faced with very promising results. This paper surveys the most significant problems in the area of offline document image processing, where connectionist-based approaches have been applied. Similarities and differences between approaches belonging to different categories are discussed. A particular emphasis is given on the crucial role of prior knowledge for the conception of both appropriate architectures and learning algorithms. Finally, the paper provides a critical analysts on the reviewed approaches and depicts the most promising research guidelines in the field. In particular, a second generation of connectionist-based models are foreseen which are based on appropriate graphical representations of the learning environment.     

Changes in physical properties of polycarbonate by absorbed water

In this paper, we report the changes in physical properties of polycarbonate caused by absorbed water and supply basic data for the application of this effect. Absorbed water increases monotonously with increase in relative humidity. Along with the increase in absorbed water, the relaxation time of the β process increases, the glass transition temperature rises, the area of the endothermic peak at the glass transition temperature increases, and the dynamic Young's modulus decreases. We conclude that the absorbed water fills holes but does not function as a crosslinking agent.     

Potential of predominant activated sludge bacteria as recipients in conjugative plasmid transfer

We investigated the possibility of conjugative plasmid transfer to the predominant bacteria in activated sludge and the factors influencing the transfer frequency in the activated sludge process. We performed conjugative transfers of a self-transmissible, broad-host-range plasmid RP4 from Escherichia coli C600 to activated sludge bacteria by broth mating. Most of the activated sludge bacteria tested could acquire plasmid RP4, although the transfer frequencies varied from 8.8 x 10(-7) to 1.3 x 10(-2) transconjugants per recipient. The transfer frequencies in several strains were similar to, or higher than, that in intraspecific transfer to E. coli HB101. Matings under various environmental conditions showed that factors relevant to physiological activity, such as temperature and nutrient conditions, seemed to affect the transfer frequency. In addition, conjugative transfer was detected even in filtered raw and treated wastewaters. Thus, the predominant activated sludge bacteria seem to have sufficient potential as recipients in conjugative plasmid transfer under the conditions likely to occur in the activated sludge process. Transfer frequency was reduced by agitation in the presence of suspended solid. This may suggest that conjugative plasmid transfer is physically inhibited in aeration tanks.     

Cavitation erosion of a flat surface near a rotating shaft

To clarify the phenomenon of cavitation erosion in the sliding bearings of internal combustion engines, an apparatus was prepared and tests were conducted on cavitation in the oil between the cylindrical face of a rotating shaft and the tip of a horn attached to an ultrasonic oscillator. This apparatus produces an oil flow and a plus-minus oil pressure between a shaft and a horn tip to simulate erosion and its distribution on bearing surfaces.From patterns of cavitation erosion on the tip of a horn made of an Al-Sn alloy and the pressure distribution on the wedge oil film, it was determined that the region where cavitation bubbles occur and the region where erosion occurs owing to the collapse of the bubbles do not necessarily coincide.Cavitation erosion was found to occur in both the plus and the minus oil film pressure regions and erosion due to bubble collapse occurs in the regions where pressure increases in the direction of oil flow.The test results allow the postulation of the mechanism and the reasons for the occurrence of cavitation erosion on actual sliding bearing surfaces.     

Data categorization using decision trellises

We introduce a probabilistic graphical model for supervised learning on databases with categorical attributes. The proposed belief network contains hidden variables that play a role similar to nodes in decision trees and each of their states either corresponds to a class label or to a single attribute test. As a major difference with respect to decision trees, the selection of the attribute to be tested is probabilistic. Thus, the model can be used to assess the probability that a tuple belongs to some class, given the predictive attributes. Unfolding the network along the hidden states dimension yields a trellis structure having a signal flow similar to second order connectionist networks. The network encodes context specific probabilistic independencies to reduce parametric complexity. We present a custom tailored inference algorithm and derive a learning procedure based on the expectation-maximization algorithm. We propose decision trellises as an alternative to decision trees in the context of tuple categorization in databases, which is an important step for building data mining systems. Preliminary experiments on standard machine learning databases are reported, comparing the classification accuracy of decision trellises and decision trees induced by C4.5. In particular, we show that the proposed model can offer significant advantages for sparse databases in which many predictive attributes are missing     

Culture characteristics of carotenoid-producing filamentous fungus T-1, and carotenoid production

The culture characteristics, carotenoid production, and associated biosynthetic pathway of strain T-1 were examined. As a result of examining the culture temperature and light irradiation, an increase of neurosporaxanthin and neurosporaxanthin beta-D-glucopyranoside was observed at a low temperature and 0 lx. It was suggested that highly polar carotenoids, such as neurosporaxanthin, and carotenoid glycosides were involved in the stabilization of membrane during nutrition storage other than the defense function of fungus bodies. Strain T-1 produced lycopene, beta-carotene, gamma-carotene, torulene, neurosporaxanthin, and neurosporaxanthin beta-D-glucopyranoside, as assessed by HPLC, LC-MS, and NMR analysis. Carotenoid biosynthesis begins with neurosporene, passing to lycopene and gamma-carotene through cyclization, and produces beta-carotene. In addition, it is saturated, gamma-carotene is converted to torulene, and neurosporaxanthin is produced. Thus, the carotenoid biosynthetic pathway in strain T-1 was estimated.     

Observation of small fatigue crack growth behavior in the extremely low growth rate region of low carbon steel in a hydrogen gas environment

To investigate the effects of hydrogen on crack propagation in the extremely low growth rate range, fully reversed bending fatigue tests were performed on low carbon steel (JIS S10C) in hydrogen and in nitrogen gas environments at a low pressure. A crack showed almost the same non-propagation behavior in nitrogen as that in air. However, a crack in hydrogen continued to propagate even near $10^{7}$ cycles in the same testing strain range as that in nitrogen. In hydrogen gas, a crack grew intermittently by coalescing with a new micro-crack generated by slip behavior. This implies that hydrogen could inhibit the action of any factor affecting non-propagation.