Sluggish Pansition Between Tetragonal and Rhombohedral Phases of Pb(Zr,Ti)03 Prepared by Application of Electric Field

Tetragonal and rhombohedral phases always coexist in Pb(Zr_xTil_1−x)0₃ near the morphotropic phase boundary compositions (0.52≤x≤0.55) when prepared by solid-solid reaction among the constituent oxides. A special technique was developed to obtain perovskite ceramics exhibiting no co-existence in the boundary compositions, in which no compositional fluctuation occurred in the B site of the perovskite structure. Even these monophasic perovskite ceramics of the morphotropic phase boundary compositions were two-phase with the lapse of time after poling. This phenomenon is interpreted in terms of thermodynamics. It is suggested that this phenomenon may closely relate to the origin of aging in piezoelectrics.     

Numerical Study on Periodic Structure Evolution of Output Power in MHD Generator by Using Pulse‐Assisted Ionization Discharge

A pulse‐assisted ionization discharge applied to a magnetohydrodynamic (MHD) generator is proposed as a technique to increase an electrical conductivity of working fluid. In this study, a periodic structure of output power in the MHD generator by using pulse‐assisted ionization discharge was evaluated. As a result, the discharge electrode length and the velocity of working fluid affect the discharge current distribution. The periodic structure of output power was observed in the several conditions. When the velocity of working fluid is roughly same as the sound speed, the periodic structure of output power was not observed.     

A Three‐Position Swing Electromagnetic Actuator with an Integrated Eddy Current Brake for Suppression of the Operating Time and Improvement of the Stopping Accuracy

A closed‐loop control system is commonly used in electromagnetic actuators to ensure operating performance. However, this system frequently leads to high costs. We developed a swing electromagnetic actuator with an integrated eddy current brake to reduce the operating time and improve the stopping accuracy. The developed actuator is a three‐position cylindrical actuator moving within a ±120º angle without closed‐loop control. The rotor is composed of a bulk and thin metal laminations and the stator has three sets of pairs of coils. The rotor is stopped at an intermediate position by magnetic force generated by the coils. This paper describes the electromagnetic design and its evaluation by using an FEM simulation to predict its operating characteristics and measure its performance on a test bench. The superiority of our actuator design is verified by comparing these measurements. The operating time is reduced to one‐sixth of that of a laminated rotor and the over travel is compressed to zero. In addition, this actuator has the advantage that it is electrically robust against variations in the power supply.     

一种永磁同步压缩机三相电流重构方法

为提高永磁同步电机无传感器控制的性能,需要对电动机三相电流进行有效采样.针对电动机相电流检测的原理和采样时间的要求,采用一种基于单电阻采样方式的电动机相电流重构方法.同时,对空间电压矢量非观测区域原理进行分析,提出一种通过附加观测矢量和补偿矢量的方法来合成目标矢量的方法,对非观测区域的三相电流进行了有效的重构.基于IRMCF343芯片设计了一套无传感器永磁同步电机控制的平台.实验结果表明该方法在低成本的变频空调领域具有实用价值.     

Melting Behavior of Gels Prepared from Isolated Subunits of Collagen

Acid-soluble collagen (ASC) was prepared from fresh pigskin corium, and denatured under mild conditions to obtain a mixture of parent gelatins. The mixture was precipitated with ammonium sulfate and preliminarily fractionated into four fractions by step-wise redissolution in ammonium sulfate solutions of decreasing concentration. From these fractions, substantially pure α1, α2, β₁₁, and β₁₂ peptide chains could be obtained by CM-cellulose ion-exchange chromatography. Differential scanning calorimetry (DSC) of the melting process of these peptide gels demonstrated that the thermal stability of α2-gel was very much lower than that of α1-gel.     

Solid Solutions in the System Taeniolite-Sodium Taeniolite and Their Properties

Solid solutions in the system taeniolite (KMg₂LiSi₄O₁₀F₂)-sodium taeniolite (NaMg₂LiSi₄O₁₀F₂) were synthesized to study the solid solubility and swelling characteristics. Based on their melting behavior, crystals were grown for X-ray structural analysis. A complete solid solution series does not form in this system; there are two types of micas, K-rich taeniolite (0≤ x <0.5, x = Na/Na + K) and Na-rich taeniolite (0.8< x ≤l). The Na-rich taeniolite exhibits swelling properties, which become less pronounced with increasing potassium content. Melting and crystallization behavior were investigated by DTA. Solid solutions with higher sodium content melted at lower temperatures and crystallization occurred over a wide range of temperatures. To obtain larger crystals, the samples containing small crystallites were remelted at slightly above their melting points, then cooled slowly.     

Some ways to increase flexibility in manufacturing systems

In recent years, many flexible manufacturing systems have been or are being developed. FMS is important in order to adapt to severe changes in market and technology and also to increase productivity. In this paper, the evaluation variables of flexibility are proposed and factors improving the flexibility of single-stage production systems with different characters are discussed. However, most production systems are multi-stage mixed type systems. This paper also points out the characteristics of the amplification of multi-stage production systems as one of the important factors affecting the flexibility and productivity of the systems. Furthermore, some ways of reducing the amplification by the ordering systems are also presented. The multi-stage ordering models discussed here are simplified, neglecting the characteristics of the single production systems which make up total multi-stage production systems and neglecting parameters concerning transportation and material flows. The flexible manufacturing system of today is treated as a stage which is part of an overall system consisting of a succession of production stages with difference characteristics. However, it should also be considered as a way to increase the flexibility and productivity of the system as a whole.     

Soft‐Switching Interleaved PFC Converter with Lossless Snubber

This paper describes a soft‐switching interleaved power factor correction (PFC) converter with a lossless snubber. AC–DC converters require a unity input power factor characteristic with highly efficient operation to prevent the inflow of harmonic current to the power source. The proposed PFC converter improves the input current ripple with interleave control. The converter realizes a high efficiency by the soft‐switching operation of all switching devices without a large auxiliary resonant circuit. This paper introduces the soft‐switching operation of the converter. In order to confirm the validity of the proposed converter, experiments with a prototype of the PFC converter have been performed. The experimental results indicate that the proposed converter can realize the soft‐switching operation of all switching devices, a reduction in the input current ripple, a unity power factor of 98% or more, a sinusoidal input current, and constant output voltage control. The efficiency of the proposed PFC converter with a lossless snubber is higher than that without the lossless snubber. The results presented in this paper confirm the validity of the proposed converter.     

Generalized exponential functions for system analysis and synthesis

Generalized exponential functions are defined and developed for the analysis and aynthesis of dynamical systems. Approximation of conventional response transforms in the 8-domain is implemented by utilizing non-integer-order complex operator 8v. The analysis technique is applied to a non-inductive long cable and to network systems. In addition, for the synthesis, ?aguorre-?eo functions in the 8-domain are extended into the non-integer-order 8v-domain in terms of generalized exponential functions. The application is demonstrated by an example     

APPLICATION OF ORGANIC SULFUR COMPOUNDS FOR PETROLEUM REFINING PROCESSES

The effects of sulfur compound PTMP and metal naphthenates on the conversion of the atmospheric residue to light oil and on the coke formation were investigated by carrying out thermal decomposition in a tubular type reactor. When 100μg/g of PTMP was added to residue, gas oil yield increased, but the effect was not significant. However, the coke deposition in the reactor was reduced by the addition of PTMP, When 100μg/g of ferric naphthenate was added, the significant effect was observed on the gas oil increase. However, the coke deposition was enhanced with the increase of gas oil yield by the addition of ferric naphthenate. Both of the increase in gas oil yield and the reduction of coke formation were observed when PTMP (1000μg/g) and ferric naphthenate (100μg/g) were simultaneously used. By the addition of the organic sulfur compound, the formation of the coke produced by the recombination of hydrocarbon redicals yielded by thermal decomposition was suppressed. The advantage of this method is that the construction of new equipment is not required and it enables the increase in the light oil fraction of residual oil by using the existing units.