Crystallographic Analysis of the Cubic-to-Tetragonal Phase Transformation in the ZrO2-Y2O3 System

The crystallography of diffusion-induced and diffusionless cubic-to-tetragonal phase transformations in the ZrO₂-Y₂O₃ system is examined on the basis of the phenomenological crystallographic theory by adopting the lsqb;011rsqb; (0 1 1) twinning system as the lattice invariant deformation system. Numerical calculation indicates that the principal axes of the cubic phase are not exactly parallel to those of the tetragonal phase and that the habit plane orientation is sensitive to the lattice parameters of the cubic and tetragonal phases. The calculated results are compared with the observed crystallography of the tetragonal precipitates formed by diffusion and of the metastable tetragonal phase formed in a diffusionless manner. In many aspects, the present results were in good agreement with experimental observations. In particular, the crystallography and morphology of the so-called "herringbone" structure are very well explained by the present analysis.     

Thermoelectric properties of ZnO-based materials

Abstracts are not published in this journal     

TiO2 Produced by Vapor-Phase Oxygenolysis of TiCI4

The formation of TiO₂ powders by oxygenolysis of TiCI₄ was studied with emphasis on the effects of reaction conditions on the particle size of the products. The particle size of TiO₂(anatase) decreased with increasing reaction temperature or O₂concentration and with decreasing TiCI₄ concentration. The results are compared with those for the oxygenolysis of AlBr₃and SiCI₄. It was found that the reactivity of metal halides with O₂ is closely related to the ease of dissociation of the first halogen atom.     

Soft-X-ray damage to biological samples

X-ray damage to biological samples was investigated in the wavelength region of 2.7–5 nm, which overlaps the so-called 'water window', the wavelength range of 2.4–4.3 nm usually used in X-ray microscopy. Yeast cells and myofibrils were chosen as representatives of whole cell samples and motile protein systems, respectively. The samples were exposed to X-rays using an apparatus composed mainly of a laser-plasma X-ray source, a Wolter mirror condenser, and a sample cell. The yeast cells lost their dye exclusion ability when the X-ray flux was higher than 1 × 10⁶ photons μm⁻², while the myofibrils lost contractility when the X-ray flux was higher than 4 × 10⁵ photons μm⁻². These X-ray fluxes are lower than the flux required for the X-ray microscope observation of biological samples at a resolution higher than that of light microscopes.     

A Study on Influence of Ramp Event of Aggregated Power Output of Photovoltaic Power Generation on Electric Power System Frequency

This paper examines the influence of aggregated power output fluctuation of photovoltaic power generation system (PVS) on the power system frequency focusing on ramp events of aggregated PVS power output. A numerical simulation model of economic load dispatching control (EDC) and load frequency control (LFC) is used together with a PVS power output forecasting model and a unit commitment (UC) scheduling model developed in our preceding study. As a result, in the case of ramp event with long duration and high ramp rate, the frequency violation occurs when the power output of controllable generators with high load‐following capability reaches to upper/lower limit even if the power output of low load‐following capability generators is still available. If the load dispatching scheme is tentatively changed from the conventional EDC using an equal incremental fuel cost rule to, for example, a dispatching policy based on the capacity without the consideration of fuel cost, the aggregated load‐following capability can be kept, avoiding the frequency violation.     

Properties of Space Charge Distributions and Conduction Current in XLPE and LDPE under DC High Electric Field

Space charge behavior and conduction current in polyethylene under dc stress were investigated. One of the reasons for the different breakdown property in cross‐linked polyethylene (XLPE) from that in low‐density polyethylene (LDPE) may be based on the existence of cross‐linking by‐products in XLPE. Furthermore, a thermal history in cross‐linking process for XLPE may also cause of the difference. It is generally accepted that the existence of the cross‐linking by‐products increase the conduction current in XLPE under dc stress. It is also said that an anneal treatment in air atmosphere may affect to the electrical properties under dc stress. Therefore, we investigated the effect of the cross‐linking by‐products and the anneal treatment on space charge behavior and conduction current in polyethylene under dc stress. In our research, it is thought that the increasing dissipation power in XLPE is the cause of the breakdown in it under dc stress. Therefore, to calculate the dissipation power in the bulk of test sample, we measured the space charge distribution and the external circuit current simultaneously. Based on the results, we discussed the reason of the difference of the space charge properties in XLPE and LDPE focusing on the cross‐linking by‐products and the oxidation of the test samples.     

Two-line neuristor with active element in series and in parallel†

A neuristor of a constant K two-line active circuit proposed by the authors was realised and the dependence of neuristor characteristics on the circuit parameters was obtained. It is known that the neuristor proposed as a micro-logic device has many advantages. However, no functional device which works as the neuristor has been completed. The proposed neuristor models have not been satisfactorily developed as a micro-electronic device because they cannot be integrated due to their structural difficulties, or even if the integration is realized, the relation between the structure and the neuristor characteristics was often obscure.

From the above point of view, a two-line circuit is proposed in this paper which is easily integrated because of its simple structure and is easy to explain theoretically. The neuristor is realized by a lumped-constant K active circuit to obtain the dependence of the neuristor characteristics on the circuit parameters. As a circuit, a series and a parallel type neuristor are used into which an S-shaped and an N-shaped negative resistive element are inserted, respectively.

First, by transmitting pulses the circuit shows that the neuristor characteristics are realized by the constant K circuit. Next the dependence of the neuristor characteristics on the circuit parameters is obtained as a function of the impedance of the circuit element, and finally, to explain theoretically the measured results, the circuit is analysed by Gauss-Seidels method which improves the conventional phase plane analysis.

As a result, it is demonstrated experimentally that the neuristor can be realized using the constant K two-line circuit. The relation between the neuristor characteristics and the circuit parameters is also obtained. Almost all the experimental results are proved theoretically. The difference of the neuristor characteristics between the S-shaped and the N-shaped negative resistance element is demonstrated. Thus now knowledge for the optimum circuit structure in order to realize the neuristor with new negative resistance elements is presented.     

气-固-固流化床用于燃煤电厂尾气同时脱硫脱硝

采用新型干法气–固–固流化床反应器进行模拟燃煤电厂尾气的高效同时脱硫、脱硝. 在内径53 mm的流化床中,以砂粒作为固相介质、自制的K2CO3/Al2O3为吸附剂,考察了温度、吸附剂粒径、吸附剂活性组份(K)与气相中污染组份(SO2,NO)的摩尔比、模拟气中SO2/NO摩尔比等工艺条件对脱硫脱硝效率的影响. 在无氨条件下同时脱硫、脱硝的效率可分别达到100%和92%. 大量数据表明,尾气中的SO2对吸附剂表面NO的脱除反应有显著促进作用.     

Sintering behaviour of monodispersed ZnS powders

The sintering behaviour of monodispersed ZnS powders having particle size of 0.1–0.9 μm, which were prepared from aqueous zinc nitrate solution by a homogeneous precipitation method using thioacetamide, was studied. Dry-pressed pellets of ZnS powders were fired at 900–1250 °C for 2 h in a nitrogen atmosphere. Monodispersed ZnS powders showed high sinterability in comparison with agglomerated or aggregated ZnS powders. The sinterability increased with decrease in particle size, and ZnS powders with particle size of 0.1 μm were densified to above 98% theoretical density by conventional sintering at 1000 °C for 2 h. Ultrafine monodispersed, spherical particles gave a uniform and fine-grained microstructure. This revised version was published online in November 2006 with corrections to the Cover Date.