A Quasi-ARMAX approach to modelling of non-linear systems

This paper proposes a class of quasi-ARMAX models for non-linear systems. Similar to ordinary non-linear ARMAX models, the quasi-ARMAX models are flexible black-box models, but they have various linearity properties similar to those of linear ARMAX models. A modelling scheme is introduced to construct models consisting of two parts: a macro-part and a kernel-part. By using Taylor expansion and other mathematical transformation techniques, it is first constructed as a class of quasi-ARMAX interfaces (macro-parts) that have various linearity properties but contain some complicated coefficients. MIMO neurofuzzy models (kernel-parts) are then introduced to represent the complicated coefficients. It is shown that the proposed quasi-ARMAX models have both good approximation ability and some easy-to-use properties. The proposed models have been successfully applied to prediction, fault detection and adaptive control of non-linear systems.     

Oxygen release behavior of metastable tetragonal t′meta-(Ce0.5Zr0.5)2 phases prepared by reduction and successive oxidation of t′ phase

Tetragonal CaF₂-related-type t′-/Ce_0.5Zr_0.5)O₂ phase was reduced at 773 K ≤ T_red. ≤ 1073 K to prepare precursors with various oxygen compositions: Ce₂Zr₂O_712d /0.111 < δ < 0.379). Metastable tetragonal t^′_meta-(Ce_0.5Zr_0.5)O₂ phases were prepared by oxidizing in O₂ at 873 K the precursors, and subjected to evolved oxygen gas analysis by heating the samples at a constant rate. When the precursor was prepared at T_red: ? 773 K; i.e. δ ? 0:379; the oxygen release behavior of the tetragonal phase agreed approximately with that of the t^′. For δ < 0.29, distinct features of the t^′_meta-(Ce_0.5Zr_0.5)O₂ appeared in the XRD results and Raman spectra. The temperature exhibiting the maximum release rate of oxygen from the t^′_meta became lower with decreasing the d value. It could be concluded that the thermodynamic behavior of the t^′_meta is related closely to the precursor composition and becomes more unstable with decrease in the δ value. The t^′ and t^′_meta phases with disordered arrangement of Ce and Zr ions may belong to the same space group; nevertheless, difference in the random arrays of the Ce and Zr ions was suggested on the basis of the present experimental results.     

Numerical analyses on liquid-metal magnetohydrodynamic flow in sudden channel expansion

Three-dimensional numerical calculations have been performed on the magnetohydrodynamic (MHD) flows through a rectangular channel with sudden expansion, particularly in order to estimate the pressure drop through the sudden expansion. The sudden expansion is in the directions both perpendicular and parallel to the applied magnetic field. The Hartmann number, the Reynolds number and the magnetic Reynolds number are set to ～100, ～1000 and ～0.001, respectively, in simulating laboratory conditions. The continuity equation, the momentum equation and the induction equation were solved numerically by the finite difference method as discretization following the MAC method as solution procedure. On the whole, in the sudden expansion in the direction perpendicular to applied magnetic field, the loss coefficient is estimated to be nearly zero or small. In particular, the loss coefficient becomes negative for small aspect ratios. The reason of negative loss coefficient is attributable to decrease in the induced current just upstream of the expansion. On the other hand, in the sudden expansion in the direction of applied magnetic field, all the cases give positive and large loss coefficients, meaning that the pressure drop through the expansion becomes large. In particular, the loss coefficient becomes considerably large when the Hartmann number increases.     

Synthesis of charge transporting block copolymers containing 2,7-dimethoxycarbazole units for light emitting device

The block copolymers consisting of 2,7-dimethoxycarbazole- and oxadiazole-containing segments as hole and electron transporting units, respectively, were synthesized by NMRP manner. OLED devices were fabricated using block copolymer, random copolymer, and polymer blend for matrix of the emitting layer with Ir(ppy)₃ as a phosphorescent dopant in order to investigate morphological effect on the performance. From the finding that the block copolymer system overwhelmed the others in EQE, we assumed that a morphology with dimethoxycarbazole units assembled to the surface of PEDOT:PSS played a considerable role for effective recombination of charges as well as sufficient charge injection into the emitting layer.     

Criteria for versatile GaN MOVPE tool:high growth rate GaN by atmospheric pressure growth

Growth rate has a direct impact on the productivity of nitride LED production.Atmospheric pressure growth of GaN with a growth rate as high as 10μm/h and also Al_0.1Ga_0.9N growth of 1μm/h by using 4 inch by 11 production scale MOVPE are described.XRD of（002） and（102） direction was 200 arcsec and 250 arcsec, respectively.Impact of the growth rate on productivity is discussed.     

Slug to annular flow transition during boiloff in a rod bundle under high-pressure conditions

High-pressure boiloff experiments in a wide range of bundle powers by using the Two-Phase Flow Test Facility (TPTF) were conducted. Two kinds of boiloff patterns were observed in these experiments. One is the boiloff pattern in a low bundle power, in which the dryout points of rods locate at a certain elevation in the bundle because the mixture level controls the dryout points. The other is the boiloff pattern in a high bundle power, in which the clear mixture level can not be observed and the dryout points of rods locate in a wide range of vertical directions. The vertical scatter of the dryout points is considered to be due to the break of the thin water film on the heater rods under the annular flow pattern.A simple model to predict the slug to annular flow transition in the rod bundle is proposed. In the model, the slug to annular flow transition takes place when the interferences of the water films on the neighboring rods cease. The model appeares to give good predictions of the previous flow transition experiment conducted in a rod bundle. The slug-annular transition below the dryout points was predicted with the present model in the high power boiloff experiments of TPTF. No slug-annular transition below the dryout points is predicted with the present model in the low power boiloff experiments.     

Chemical Modification of Phage-Displayed Helix-Loop-Helix Peptides to Construct Kinase-Focused Libraries

Conformationally constrained peptides hold promise as molecular tools in chemical biology and as a new modality in drug discovery. The construction and screening of a target-focused library could be a promising approach for the generation of de novo ligands or inhibitors against target proteins. Here, we have prepared a protein kinase-focused library by chemically modifying helix-loop-helix (HLH) peptides displayed on phage and subsequently tethered to adenosine. The library was screened against aurora kinase A (AurA). The selected HLH peptide Bip - 3 retained the α-helical structure and bound to AurA with a K_D value of 13.7 μM. Bip - 3 and the adenosine-tethered peptide Bip - 3 - Adc provided IC₅₀ values of 103 μM and 7.7 μM, respectively, suggesting that Bip - 3 - Adc bivalently inhibited AurA. In addition, the selectivity of Bip - 3 - Adc to several protein kinases was tested, and was highest against AurA. These results demonstrate that chemical modification can enable the construction of a kinase-focused library of phage-displayed HLH peptides.     

Liquid‐phase sintering of highly Na+ ion conducting Na3Zr2Si2PO12 ceramics using Na3BO3 additive

Na₃Zr₂Si₂PO₁₂ (NASICON) is a promising material as a solid electrolyte for all‐solid‐state sodium batteries. Nevertheless, one challenge for the application of NASICON in batteries is their high sintering temperature above 1200°C, which can lead to volatilization of light elements and undesirable side reactions with electrode materials at such high temperatures. In this study, liquid‐phase sintering of NASICON with a Na₃BO₃ (NBO) additive was performed for the first time to lower the NASICON sintering temperature. A dense NASICON‐based ceramic was successfully obtained by sintering at 900°C with 4.8 wt% NBO. This liquid‐phase sintered NASICON ceramic exhibited high total conductivity of ~1 × 10^?3 S cm^?1 at room temperature and low conduction activation energy of 28 kJ mol^?1. Since the room‐temperature conductivity is identical to that of conventional high‐temperature‐sintered NASICON, NBO was demonstrated as a good liquid‐phase sintering additive for NASICON solid electrolyte. In the NASICON with 4.8 wt% NBO ceramic, most of the NASICON grains directly bonded with each other and some submicron sodium borates segregated in particulate form without full penetration to NASICON grain boundaries. This characteristic composite microstructure contributed to the high conductivity of the liquid‐phase sintered NASICON.     

Mechanisms of concurrent SiO desorption with oxide layer formation at Si(001) surface

Oxidation reactions at Si(001) surfaces have been studied via real‐time in situ photoemission spectroscopy with synchrotron radiation for chemical bonding states of Si and O atoms and mass spectrometry for desorption of SiO molecules with supersonic O₂ molecular beams in a temperature region from 900 K to 1300 K. In our previous studies, the SiO desorption yield decreased with increasing incident energy in a temperature region from 900 K to 1000 K. In that case, the time evolutions of Si 2p photoemission spectra showed that SiO₂ structure on the surface was easily formed by the action of larger incident energy and the increased SiO₂ coverage correlated with the decreased SiO desorption yield. In this study, simultaneous measurements of Si 2p photoemission spectra and SiO desorption yield revealed that the decrease of SiO correlated with the increase of Si²⁺ component, and the SiO desorption was terminated at the oxide thickness of 0.22 nm. These facts suggest that the SiO desorption takes place at the topmost Si dimers and a precursor for SiO desorption is a so‐called T site, in which O atoms are bonding with the dangling bonds of the dimers. Consequently, M1 and M2 in the Dual‐Oxide‐Species (DOS) model have been clarified to be a T site and a Si²⁺ state, respectively. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 164(3): 60–68, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20678