PLZT fiber-optic switch

This paper describes a nonmechanical two-input two-output (2 × 2) optical switch using the electrooptic effect in PLZT ceramics. An alkoxide process and a hot-pressing technique are used to obtain homogeneous PLZT ceramics. This switch has low insertion loss (<1.9 dB) and fast response (<70 ns), and it is easily applicable to multimode fibers with connectors.     

Studies on syntheses and permeabilities of special polymer membranes. 62. Active transport of alkali metal ions through poly(vinyl alcohol) membranes crosslinked with glutaraldehyde

The transport of alkali metal ion through poly(vinyl alcohol) crosslinked with glutaraldehyde without dissociating groups in a diaphragm cell, at one side being an alkaline and at the other an acidic solution, was investigated under various conditions. The active transport fraction of alkali metal ions from the alkaline side to the acidic side was significantly influenced by the degree of crosslinking of the membrane, size of anion species, initial pH on the acidic side, and the electric potential difference across the membrane.     

Growth pressure-temperature region of cubic BN in the system BN-Mg

The growth pressure-temperature region of cBN in the system BN-Mg was determined under the conditions up to 8 GPa and 2300° C. Hexagonal BN with different oxygen contents (1.9 wt % for R-type and 7.9 wt % for N1-type) was used as a starting material. The lower temperature limit of the cBN region obtained from the R-type is about 1380° C under pressures of 6 to 8 GPa. This limit can be compared with the eutectic point in the system hBN-Mg₃B₂N₄. The data suggest that cBN crystals grow through the dissolution and precipitation process from a eutectic liquid. The cBN region obtained from the N1-type is located at higher temperatures than that of the R-type, the lower limit of which is reached at about 1700° C at 6 GPa. MgO and/or Mg₃ (BO₃)₂ are formed as by-products in such a system. The finding implies that Mg₃B₂N₄, a solvent of BN, reacts with oxide impurities (especially B₂O₃) by the following reaction; Mg₃B₂N₄+3/2O₂=3MgO+2BN+N₂ or Mg₃B₂N₄+3O₂=Mg₃ (BO₃)₂+2N₂. It is deduced that the cBN growth region shifts towards higher temperatures depending on the effect of oxygen.     

Theory of failure of concrete and similar brittle solid on the basis of strain

The present paper shows that these results fit a static statistical theory corresponding to a Weibull distribution of strain mortar in compression. The results of these experiments can be formulated in terms of an ultimate strain criterion. The present paper shows that these results fit a statistical theory corresponding to a Weibull distribution of strain at failure. The absence of a significant change in ultimate strain upon application of repeated loading indicates the inapplicability of a stochastic process theory.

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Zusammenfassung Diese Arbeit faßt Bruchversuche unit Beton und Mörtel unter Druck zusammen, die der Autor während der vergangenen Jahre ausgeführt hat. Die Ergebnisse dieser Versuche können mit einer kritischen Endbelastung formuliert werden. Diese Arbeit zeigt, daß die Ergebnisse mit einer statisch-statistischen Theorie entsprechend einer Weibullschen Belastungsverteilung beim Bruck übereinstimmen. Es ist keine wesentliche Änderung in der Endbelastung bei wiederholter Belastung vorhanden, sodaß eine stochastische Prozeßtheorie nicht anwendbar ist.

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Résumé Le présent rapport résume les etudes exécutées par l'auteur durant les dernières années sur la rupture en compression du béton et du mortier. Les résultats des expériences peuvent être exprimés sous forme d'un critère de contrainte extrême. L'étude montre que ces résultats obéissent une théorie statistique statique correspondant à une distribution Weibull de contrainte à la rupture. L'absence d'un changement sensible de la contrainte extrême sous l'application répétée de charges indique l'inapplicabilité d'une théorie pour un procédé stochastique.

     

Reconstruction of time-varying 3-D left-ventricular shape from multiview X-ray cineangiocardiograms

This paper reports on the clinical application of a system for recovering the time-varying three-dimensional (3-D) left-ventricular (LV) shape from multiview X-ray cineangiocardiograms. Considering that X-ray cineangiocardiography is still commonly employed in clinical cardiology and computational costs for 3-D recovery and visualization are rapidly decreasing, it is meaningful to develop a clinically applicable system for 3-D LV shape recovery from X-ray cineangiocardiograms. The system is based on a previously reported closed-surface method of shape recovery from two-dimensional occluding contours with multiple views. To apply the method to "real" LV cineangiocardiograms, user-interactive systems were implemented for preprocessing, including detection of LV contours, calibration of the imaging geometry, and setting of the LV model coordinate system. The results for three real LV angiographic image sequences are presented, two with fixed multiple views (using supplementary angiography) and one with rotating views. 3-D reconstructions utilizing different numbers of views were compared and evaluated in terms of contours manually traced by an experienced radiologist. The performance of the preprocesses was also evaluated, and the effects of variations in user-specified parameters on the final 3-D reconstruction results were shown to be sufficiently small. These experimental results demonstrate the potential usefulness of combining multiple views for 3-D recovery from "real" LV cineangiocardiograms.     

Deduction Systems for BDI Logics with Mental State Consistency

BDI Logics, introduced by Rao et al., have been used as the theoretical basis of specification and implementation of rational agents. The aim of our research is to make full use of the expressive power of BDI Logics as executable specification languages of rational agents. To this end, we previously presented deduction systems for CTL-based propositional BDI Logics using sequent calculus. Since these systems have a decision algorithm that is extended from Wang's algorithm, they are suitable for applications such as automatic proving. However, they do not incorporate mental state consistency features, which are important for dealing with rational agents. In this paper, we extend our deduction systems by introducing mental state consistency features and explain their soundness and completeness. This approach allows us to check and prove the specifications and properties described by BDI Logics for rational agents.     

Equivalence in Harmonics Between Cycloconverters and Bridge Converters

The similarity between a six-pulse three-phase cycloconverter operating in the circulating current-free mode and a six-pulse three-phase bridge converter is discussed analytically with regard to the rms value and the harmonics of the respective output voltages. A method is presented for calculating the rms voltage of a family of sideband frequencies which are generated in the output voltage of the cycloconverter. The results obtained from the analysis help to predict the amplitudes of subharmonics and beat frequencies with the cycloconverter and are essential for the design of the output filters. Analytical results are verified by comparison with those of experiment and digital computer simulation.