Tetragonal to monoclinic transformation and microstructural evolution in ZrO2–9.7 mol% MgO during cyclic heating and cooling

The tetragonal (t) to monoclinic (m) transformation behaviour and its relationship to microstructural evolution were investigated by means of dilatometry and transmission electron microscopy for ZrO2–9.7 mol% MgO during cyclic heating and cooling between room temperature and 1490 K. In the as-sintered specimens, fine oblate ellipsoidal t-phase precipitates, 20–50 nm in diameter and 100–200 nm long, were distributed in the cubic (c)-phase matrix. They were below a critical size for transformation and exhibited no transformation in the first three cycles. In the fourth and further cycles, transformation occurred in two distinct stages. A low-temperature stage appeared at 850–1000 K on heating and at 400–700 K on cooling, while a high-temperature stage appeared at 1350–1400 K on heating and at 1000–1200 K on cooling. With the increasing number of cycles, at first the size of low-temperature stages increased and then decreased above ten cycles accompanying the development of the high-temperature stage. During cyclic heating and cooling, coarsening of ellipsoidal precipitates and decomposition of c- and t-phases occurred. As a result of the decomposition, MgO particles and a new m-phase containing a very low concentration of MgO were produced. The coarsened ellipsoidal t-phase precipitates were responsible for the low-temperature stage. The new m- or t-phase containing very low MgO produced by the decomposition was responsible for the high-temperature stage.     

Effects of Oxygen Absorber and Temperature on ω3 Polyunsaturated Fatty Acids of Sardine Oil during Storage

To prevent loss of w3 polyunsaturated fatty acids over long-term preservation, the effects of temperature and oxygen absorber on the fatty acids of sardine oil stored in air-tight film were studied. The fatty acids of sardine oil and lipids in the diet of experimental animals rapidly decreased over 1 month at 22°C. The amounts in the diet decreased slowly at 2°C; however, no alterations in the oil samples were observed for 6 months. Also, the amounts did not change at -30°C. Significant changes in samples treated with oxygen absorber were not observed under all temperatures during 6 months storage (P > 0.05). These results indicate that treatment with an oxygen absorber and/or freezing can prevent ω3 polyunsaturated fatty acids of fish oil from decreasing during storage.     

S06 桂花幻想之月夜——梦天

作为厦门园博会风景园林师园之一,本园以"梦天"为主题,结合东端开阔的水面条件,以月、桂、石为材,以天气的变化、月亮的位置、植物的变化、庭园本身的变化为主轴进行设计,使其成为一座可持续的庭园.     

Design of a fixed-point smoother based on an innovations theory for white gaussian plus coloured observation noise

The optimal fixed-point smoother is designed based on an innovations theory for the white gaussian plus coloured observation noise in linear continuous systems. The signals to be estimated are non-stationary or stationary stochastic processes. The proposed fixed-point smoothing algorithm calculates estimates sequentially by using the observed value, the autocovariance function of the signal plus the coloured observation noise process and the cross-covariance function of the signal with the observed value.     

Stable identification scheme for linear discrete-time systems

This paper is concerned with the problem of identifying parameters in stochastic systems described by single-input single-output linear discrete-time equations. A stable estimation error system is developed by using the extended Kalman filter technique and the concept of strictly positive real transfer function. The identifier corresponding to the estimation error system is constructed, and the convergence of parameter estimates to the exact values is proved under some bounded conditions. It is shown that the recursive maximum likelihood identifier and the recursive extended least squares identifier are obtained by neglecting the correction terms in the proposed identifier. Numerical examples for a fourth-order system are presented to illustrate the effectiveness of the proposed method.     

Acid Urease: Reduction of Ethyl Carbamate Formation in Sherry under Simulated Baking Conditions

Acid urease derived from Lactobacillus fermentum was applied to reduce ethyl cthe target level (90 μg/L). However, complete prearbamate (EC) formation in California sherry production. Commercial sherry and sherry base were treated with urease under different conditions. Amounts of urea were determined and EC amounts were monitored by gas chromatography. Urea removal by acid urease reduced EC formation during the baking process and effectively maintained EC concentrations below vention of EC was not achieved because of precursors other than urea.     

Electrical Breakdown Strength of Alumina at High Temperatures

The dc electrical strength of sapphire and poly crystalline alumina was studied up to 1400°C. The electrical strength was essentially identical for both materials. It was > 10⁶ V/cm at room temperature and decreased gradually with temperature up to 900°C (2.6×10⁵ V/ cm), then dropped rapidly to 2×10⁴ V/cm at 1400°C for a sample thickness of ∼ 100 μm. The electrical strength decreased with the sample thickness. It was inversely proportional to the thickness for samples thicker than ∼ 600 μm at 1200°C. The breakdown behavior was explained on the basis of a thermal breakdown model.     

Fuzzy control of a manipulator using an actuator and multibrakes

This paper is concerned with the control of a manipulator with n-degrees of freedom by one actuator and n ? 1 brakes using fuzzy inference. All the links of the manipulator are excited by a motor placed on the base link, and the excitation torque is successively transmitted through each link from the base link until the final link. The brakes on the joints act at identical frequency with different phases, and the phases of timing on the brakes are controlled by fuzzy inference such that all the joint angles of links are followed to the desired trajectories. The effectiveness of the proposed method is illustrated by a simple example.     

Active control for the suspension of large-sized buses using fuzzy logic

An active suspension of large-sized buses by using fuzzy logic is considered. The active control for the suspension is determined by minimizing the mean squares of vertical and rotary accelerations of vehicle body subject to the constraints of suspension and tyre deflections. The vehicle model is assumed to be a linear system with six degrees of freedom excited by road profiles. The tuning of fuzzy control rules and associated parameters that characterize the active control is carried out where two kinds of road profiles are considered. In the simulation results, the proposed active suspension shows improved performance over passive suspension     

Angular correction of sea surface temperature observed by thermal infrared radiometer

Abstract

A thermal infrared radiometer indicates a lower sea surface temperature at a large observation angle than the directly measured one. In order to explain this decrease in the apparent temperature, the intensity of the radiation reaching the radiometer is formulated as a function of observation angles of the radiometer. In the equation, we assume that a reflection loss occurs at the sea surface for the radiation from below the surface. The temperature predicted from this formula at the large observation angles fits well to the observed one, indicating that temperatures observed at large observation angles can be corrected