Decomposition of Two Aluminum Sulfates and Characterization of the Resultant Aluminas

Two special types of anhydrous aluminum sulfate with extreme grain shapes were prepared; one, obtained by precipitation from concentrated sulfuric acid solution, is rhombohedral near cubic single-crystal grains and the other, from acetic acid solution, consists of very thin flaky particles. The morphology of sulfate and calcined alumina, the sulfate decomposition, the η-α alumina transformation, and the crystallite growth of α alumina were studied and compared with those processes for reagent-grade sulfate. The morphology of anhydrous sulfate was shown to greatly affect the heat-treatment characteristics of alumina and the sulfate decomposition behavior.     

11B and 27Al Nuclear Quadrupole Interactions in SiO2-B2O3-Al2O3-R2O Glass Systems

Quadrupole interactions of ¹¹B and ²⁷Al in SiO₂-B₂O₃-Al₂O₃-R₂O glass systems were investigated to determine the structure of these glasses, which should be amenable to chemical strengthening. The ratio of BO₄ units to BO₃ units approached unity as the R₂O/Al₂O₃ ratio for compounds having fixed B₂O₃ contents approached unity. Nuclear quadrupole coupling constants ( e²Qq/h =2.73 to 2.93 MHz) were measured for the NMR spectra of ¹¹B triangles. The line shapes of ²⁷Al spectra varied with chemical composition, but a few glasses exhibited ²⁷Al line shapes similar to those of the AlO₄ triclusters in SiO₂-Al₂O₃-Na₂O glasses. Compositional trends in the formation of BO₄ and AlO₄ were deduced from the NMR spectra.     

Design of type-1 servo systems possessing prescribed stability margins using a generalized Riccati-type equation

A design method for type-1 servo systems having prescribed stability margins at the control input and error channels is presented. The former and latter stability margins affect the properties of sensitivity and robustness and the transient response characteristics, respectively. As a preliminary, a class of state feedback laws for regulators that possess a prescribed stability margin is parametrized by means of a generalized Riccati-type equation. This is applied to designing servo systems, which enables us to specify the stability margins at the above two portions. We can improve the output response of the system by the proposed design procedure and the effect is ascertained by an example. The integrity at the error channel is also investigated.     

Sampled-data optimal control of continuous systems for quadratic criterion function taking account of delayed control action

This paper is concerned with the sampled-data control of a continuous system in the situation where there exists delay for the control action after the measurement of the output at each sampling instant. The optimal control with the quadratic criterion function defined for the continuous system is adopted in this control problem. This paper shows that the problem can be transformed into the optimal control of a discrete system for the quadratic criterion function, and the variation of the control law to the sampling period and to the delay of the control action is clarified. The deterioration of cost performance with respect to delay is derived. A numerical example is also presented.     

Optical and EPR Studies of Redox Interactions of Polyvalent Ions (Cr, Cu) in Glass

Chromium centers in isolated Cr ions and Cr(III)-Cu(II) redox interactions were investigated by optical and EPR spectra. Line shapes and intensities of high-field Cr(III)-Cu(II) superimposed EPR absorption lines were sensitive to alkali content of host glasses. High-field chromium g values (1.94 to 1.99) and intensities (190 to 3600) were calculated. The increase in g values from 1.96 to 1.98 is related to an increase in Cr(V) and to a conversion from Cu(I) to Cu(II) with increased alkali content. Two components of Cr powder spectra near g = 2.0 and g = 5.0 correspond to isolated octahedral Cr centers described by Landry et al. Cr-Cr pair structure was not observed for low Cr₂O₃ concentrations. Three components of optical absorption bands near 340 nm, 430 to 460 nm, and 600 nm were measured in Cr(III)-Cu(II) redox systems. Electronic interactions of Cr(III)-Cu(II) redox systems and the structure of Cr centers are discussed.     

A successive projection method for binary pattern recognition with multilayer feedforward neural networks

Error back-propagation (BP) is one of the most popular ideas used in learning algorithms for multilayer neural networks. In BP algorithms, there are two types of learning schemes, online learning and batch learning. The online BP has been applied to various problems in practice, because of its simplicity of implementation. However, efficient implementation of the online BP usually requires an ad hoc rule for determining the learning rate of the algorithm. In this paper, we propose a new learning algorithm called SPM, which is derived from the successive projection method for solving a system of nonlinear inequalities. Although SPM can be regarded as a modification of online BP, the former algorithm determines the learning rate (step-size) adoptively based on the output for each input pattern. SPM may also be considered a modification of the globally guided back-propagation (GGBP) proposed by Tang and Koehler. Although no theoretical proof of the convergence for SPM is given, some simulation results on pattern classification problems indicate that SPM is more effective and robust than the standard online BP and GGBP     

NUCLEATION AND GROWTH OF OXIDE NANOPARTICLES PREPARED BY INDUCTION THERMAL PLASMAS

The reactive evaporation method of injected metal powders was investigated for preparing oxide nanoparticles. The method has advantages such as evaporation is enhancement of the injected powder owing to exothermic reaction heat of the metal powder oxidation in induction thermal plasmas. Tangential gas flow injection to the plasma tail flame controls the diameter and the yield of the oxide nanoparticles. The purpose of this research is to investigate the effect of the injection gas flow on the preparation mechanism of oxide nanoparticles in thermal plasmas by experimental work and numerical analysis. An increase in the flow rate of the injection gas leads to an increase in the diameter as well as the yield of the prepared nanoparticles. Numerical analysis for nucleation and growth provides the preparation mechanism of the oxide nanoparticles; however, a more sophisticated model should be developed.     

Finite spectrum assignment of linear systems with a class of non-commensurate delays

This paper is concerned with finite spectrum assignment of linear systems with non-commensurate delays. It is proved that if a feedforward pass between states variables does not have multi non-commensurate delays in parallel but only one or no delay in series, then the system is finite spectrum assignable even though the feedback pass has multi non-commensurate delays in parallel.     

Heat-induced Gelation of Chicken Gizzard Myosin

Chicken gizzard myosin solution formed a gel when heated above 40°C. The rigidity of the gel was constant above 65°C. Maximum pH for gel formation was 5.9 at 0.6M and 5.7 at 0.15M KCl. Higher rigidity of the myosin gel was observed at low ionic strength than at high ionic strength. Rigidities of myosin at 0.6M KCl increased by (mg/mL)^2.5 and at 0.15M (mg/mL)^{1, 4} myosin concentration. The strength of gizzard myosin gels was comparable to that of myosin gels from chicken breast muscle under similar conditions.     

Kinetics of Hydration of Monocaldum Aluminate

Hydration of CaAl₂O₄ (CA) was studied by calorimetry, analysis of the liquid phase, measurement of the combined water, and electron microscopy. During the induction period, the solution remains almost unchanged and is equilibrated temporarily with both superficially intrusion-hydrated CA particles and Al(OH)₃ gel formed by dissociation of Al(OH)₄^– ions, the solubility of the Al(OH)₃ gel being 10^–4.24 molkg^–1 at 25°C, while the intrusion-hydrated layer on the CA particles grows following a nearly linear law to reach a critical thickness (∼3 nm at 10° to 20°C, or 12 nm at 30°C). At this point destruction of the layer occurs, nuclei of hydrous compounds are generated, and the induction period terminates. Subsequent reaction proceeds in accordance with the rate equation of Schiller based on the dissolution-crystallization mechanism.