Decomposition of Mullite by Silica Volatilization

Thermal decomposition of mullite into corundum was investigated using a high-temperature X-ray single-crystal camera equipped with a gas-flame furnace and by scanning electron microscopy and electron probe microanalysis (EPMA). When heated to ∼1750°C, mullite decomposed to corundum by the liberation of the SiO₂ component with topotaxial relations of:

• (1) 

  (310)_mull∥(001)_cor; [001]_mull∥[110]_cor
• (2) 

  (130)_mull∥(001)_cor; [001]_mull∥[110]_cor
• (3) 

  (110)_mull∥(001)_cor; [001]_mull∥[110]_cor

Thus, it was considered that, when mullite decomposed into corundum, their oxygen close-packed planes were almost preserved. The SEM photographs showed that the crystals of the developed corundum are prismatic and ∼5 μm wide. The EPMA showed that the phase boundary between mullite and developed corundum is discontinuous.     

PHYTOCYSTATINS AND THEIR TARGET ENZYMES: FROM MOLECULAR BIOLOGY TO PRACTICAL APPLICATION: A REVIEW

Cystatins are protein inhibitors of cysteine proteinases. Oryzacystatin I (OC-I) has been cloned and is apparently the first well-defined cystatin of plant origin (phytocystatin). Besides OC-I, various other phytocystatins occur in rice, corn, wheat and soybean. Phytocystatins have endogenous target enzymes whose expression is induced by gibberellin, and also exogenous target enzymes from viruses and insects. It is thus likely that phytocystatins are involved in the regulation of intracellular protein catabolism as well as in the defense from infection. Better understanding of this phenomenon and cloning of appropriate genes will facilitate the creation of transgenic crops with enhanced resistance to viruses and insects.     

ON THE PARAMETER-SPACE CLASSIFICATION OF THE DYNAMIC BEHAVIOR OF A CONTINUOUS MICROBIAL FLOW REACTOR

Recently Agrawal et al.¹ classified the dynamic behavior of continuous stirred tank fermentor for the Monod's model and the two parameter hump function model with variable yield coefficient in the parameter space. We employed the more general three parameter substrate inhibition model which includes the Monod's model as a limiting case, derived the boundary equations which rigorously divide the parameter space of different dynamic behavior, and showed the interesting phenomenon that a limit cycle suddenly vanished for the slight change in the Damköhler number by computer simulation.     

Molecular Composition of Onion Pectic Acid

ABSTRACT: Pectin was extracted, then pectic acid was purified without autolysis. It contained 93.7% uronic acid and 6.3% neutral sugar. Using exopolygalacturonase, exopolygalacturonate lyase and endopolygalacturonase, the molecular composition of onion pectic acid was determined; the proportion of galacturonic acid residue from the nonreducing end to rhamnogalacturonan (RG) was 9.7%, while that of the reducing end to RG was 46.7%. From RG to RG, the proportion of galacturonic acid residue was 41.0%, and the RG region was 2.6%.     

Impact of Retailer and Consumer Behavior on Voltage in Distribution Network Under Liberalization of Electricity Retail Market

The liberalization movement in Japan will be expanded to the residential sector and full liberalization of the retail market will be achieved in the near future. Against this background, it is expected that transactions in a distribution network (DN), which has many consumers of the residential sector, will be activated. Furthermore, consumers can control their loads depending on the selling prices offered by retailers with the introduction of demand response (DR) technologies such as home energy management systems (HEMS). Due to the variation of load by DR, however, the voltage profile in DN may be changed compared to the present situation. This may make voltage management difficult and cause problems such as voltage deviation from an adequate range. In this paper, the impact of DR in a liberalized electricity market on DN is evaluated for efficient voltage management. In order to evaluate the behavior of the retailer and consumers, this paper proposes a bi‐level programming approach based on the Stackelberg game model. Solving the bi‐level programming problem including the power flow equation for a DN model based on the IEEE 13‐bus test feeder, we analyze the impact of the retailer and consumers on the voltage in the DN in order to account for transactions between these market players.     

Two-Phase Flow Regimes and Discharge Characteristics of a Plasma Electrohydrodynamic Atomization

Experimental investigation was conducted to study the flow regimes and discharge characteristics of plasma electrohydrodynamic atomization (EHDA) for decane (C10H22) under pulsed applied negative voltage. The experimental parameters were set as the flow rate of decane from 0 to 10 mL/min and the dc charging voltage from dc 0 to 12 V with a pulse repetition rates of 200 Hz. The flow regime of decane was observed and the volume-to-electrical charge ratio was measured. Unlike a conventional EHDA system, the results show that a corona discharge was initiated at the edge of the hollow electrode at a specific corona on-set voltage of -17 or -20 kV in the case with or without decane flow, respectively. This phenomenon was defined as plasma EHDA.     

Object oriented programming in production management—two pilot systems

This paper discusses AI-oriented production management systems using object oriented programming. The two pilot systems described here are both implemented using the Smalltalk-80 programming environment. One of the systems concerns production planning in dairy industries, while the other is a simulation tool for production flow analysis. The merits of object oriented programming in the design of the user interfaces are emphasised. The flexibility of the object oriented approach for stepwise development has been observed. Simulation method as a communication tool is used in both systems and the applicability of Smalltalk in simulation is demonstrated. Design effectiveness and efficiency has proven surprisingly good. The experiences introduced in the paper are based on two geographically disjoint research groups, having thus impact on the generality of the observations made.     

Application of the singular control test to periodic control problems of a continuous distillation process

The singular control test is applied to periodic control problems of a continuous distillation process in order to determine if the optimal periodic control is proper. It is also shown that the singular control test is easier to apply than the w-teat for the problems of concern. Some numerical calculations are carried out for seeking the optimal periodic controls.     

PMSM Sensorless Control Based on Position Estimation Correction Using All‐Pass Filters

This paper proposes a novel flux estimation method for the position sensorless control of permanent magnet synchronous motors (PMSMs). In general, the stator flux linkage for position estimation in PMSMs is obtained using the pure integration of voltages. The infinite dc gain of the pure‐integrator, however, causes numerical drifts in the obtained stator flux linkage due to the dc offset in the input of this integrator. To address this problem, a quasi‐integrator is often substituted instead of the pure integrator to restrict the dc gain, leading to another problem in which the phase characteristics vary according to the operating frequency. As a result, the ideal phase characteristics (?90° constant) cannot be held, and the position estimation performance deteriorates. Therefore, this paper proposes a phase characteristic correction method for quasi‐integrators using all‐pass filters, which achieves extremely precise estimation under transient conditions as well as in steady state.     

Preparation and properties of Y2O3-doped ZrO2 thin films by the sol–gel process

Y₂O₃-doped ZrO₂ (YZ) thin films were prepared on alumina substrates by the dip-coating process. The dip-coating solution consisted of a homogeneous sol, and was prepared by using the respective chlorides as raw materials, with ethylene glycol, 2-butanol and distilled water as solvents. The thin films containing 0–20 mol % Y₂O₃ were successfully produced by thermal treatment above 600 °C. The characterization for the film preparation was performed by means of thermogravimetric–differential thermal analysis for the thermal analysis, and scanning electron microscopy for the morphological analysis and thickness measurements. The properties of the films were characterized in terms of a study of the crystalline phase, the crystallite size, the microstructure and the electrical conductivity by using X-ray diffraction, scanning electron microscopy and the complex impedance techniques. In all YZ thin films, the tetragonal phase was stable at low temperatures as a result of the crystallite size effect. However, at higher temperatures, the tetragonal phase was transformed into either the monoclinic phase or the cubic phase, depending on the doping concentration. The YZ thin film of 8 mol% Y₂O₃ content was stabilized to almost cubic phase at 1000 °C. Resonable conductivity behaviour at YZ was observed for the YZ thin films. The electrical conductivity of YZ thin films was similar to the values of the sintered body. This revised version was published online in November 2006 with corrections to the Cover Date.