Effects of calcination temperature on phase and microstructure evolution of BaTi4O9 powders

Calcining of the mixture of BaCO₃ and TiO₂ with a ratio 1:4 at different temperatures was carried out to synthesize BaTi₄O₉ powders. Phase evolution of the samples was studied using the differential thermal analysis (DTA) and X-ray diffractometry (XRD). Both techniques confirmed that the formation of BaTi₄O₉ started around 1000 °C. The XRD peaks showed that BaTi₄O₉ was most pronounced at 1250 °C. X-ray line broadening methods were employed to study the variation of particle size and microstrain of the BaTi₄O₉ powders. The Voigt function in a single line and the pseudo-Voigt function in the variance methods were used in our case. We found that both functions resulted in the same trends, i.e., the particle size increased with the temperature with the biggest size of 180 and 160 nm, whilst the microstrain yielded the opposite trend with the lowest values of 6.2 × 10^–3 and 1.1 × 10^–3. The scanning electron microscopy (SEM) study revealed the size of the large particles formed, due to agglomeration, to be about 0.5–1.9 μm. Furthermore, it was shown that irregular shapes of BaTi₄O₉ powders necked to each other appeared at 1000 °C and grew into ellipse and rod shapes at 1250 °C. Electronic Publication     

双螺杆反应挤出模型的研究

详细研究了双螺杆中反应挤出聚合物的动力学模型、流动模型和传热模型。通过实验得到了双螺杆反应器中聚合物的停留时间分布及平均停留时间。     

光纤专用网中基于DSP的Q值在线检测模块的设计

基于误码率与Q值的对应关系，本文介绍一种Q值在线检测方法，模块设计采用DSP技术，并讨论了该模块在光纤工业专用网（FIN）中的应用。     

城市燃气管网设计若干问题的探讨

分析了哈依燃气管道工程在施工及管理过程中存在的问题，并就如何解决这些问题提出了建议。     

计算机辅助设计中浓淡曲线的设计

本文介绍利用Super Frame软件进行色彩浓淡设计的原理、方法和步骤。据此原理和方法,使用C语言设计开发出了应用实例——折线浓淡分布曲线。     

Electrochemical impedance spectroscopy of a free-standing oxide film

The corrosion of low carbon steel in natural sea-water is characterized by the formation and growth of compact and thick layers composed of oxides, insoluble salts and organic materials. These layers are the result of corrosion processes induced by local environmental conditions, water oxygen supply; ionic species; bacteria and organic matter. The exchange of various species (ions, molecules, gas) between sea-water and the rust layers or the metal depends both on the kinetics of the Faradaic reactions of the entities with either the oxides or the metal, as well as on their transport properties through the different strata of the rust layers. In this work, an impedance study was carried out using the 4-electrodes cell arrangement with corrosion products picked up on steel sheet piling immersed for 25 years and analyzed as free standing membranes. This new approach is a good way to reach the specific transport and transfer properties of the oxide without being blurred by the metal influence. The physical model developed in this work was based on a transmission line, and accurately described the experimental diagrams. The electronic resistivity of the oxide layer, its porosity, the mean pore size and the reaction kinetics parameters could be determined from the fittings.     

Sensorless control of synchronous reluctance motors using on‐line parameter identification method not affected by position estimation accuracy

This paper presents a novel on‐line parameter identification method for sensorless control of Synchronous Reluctance Motors (SynRMs). Although conventional sensorless control methods based on mathematical models usually need some complex measurements of motor parameters in advance, the proposed identification method does not require them and can be realized on‐line. The proposed method identifies motor parameters under sensorless control, so rotor position and velocity cannot be used to identify these parameters. However, the proposed method does not need rotor position and velocity, and identified parameters are not affected by these estimation errors. The sensorless control using identified motor parameters is realized, and the effectiveness of the proposed method is verified by experimental results. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 155(3): 62–69, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20258     

A novel robust current control approach using adaptive line enhancer for three‐phase current‐source active power filter

An effective system control method is presented for applying a three‐phase current‐source PWM converter with a deadbeat controller to active power filters (APFs). In the shunt‐type configuration, the APF is controlled such that the current drawn by the APF from the utility is equal to the current harmonics and reactive current required for the load. To attain the time‐optimal response of the APF supply current, a two‐dimensional deadbeat control scheme is applied to APF current control. Furthermore, in order to cancel both the delay in the two‐dimensional deadbeat control scheme and the delay in DSP control strategy, an Adaptive Line Enhancer (ALE) is introduced in order to predict the desired value three sampling periods ahead. ALE has another function of bringing robustness to the deadbeat control system. Due to the ALE, settling time is made short in a transient state. On the other hand, total harmonic distortion (THD) of source currents can be minimized compared to the case where ideal identification of the controlled system can be made. The experimental results obtained from the DSP‐based APF are also reported. The compensating ability of this APF is very high in accuracy and responsiveness although the modulation frequency is rather low. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 150(1): 50–61, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20014     

高职教育网上成绩考核系统的总体设计

本文对网上成绩考核系统进行了总体设计.其中,设计了校园网的网络结构模型、网上成绩考核系统的模块结构及其数据库和数据表.     

Egg white powder in extruded fish crackers

Four levels of egg white powder (EWP), 0, 1.5, 3.0 and 4.5%, were added to fisfc cracker formulation consisting of tapioca starch, fish paste, and water. the mixture was extruded through a single screw extruder, and the extrudate was cut, dried, heated in a microwave, and the degrees of expansion, bulk density, colour and protein content were measured.
The addition of 1.5 and 3.0% EWP had no significant effect ( P < 0.01) on diametral and longitudinal expansion, however, 4.5% EWP significantly ( P < 0.01) reduced them. Bulk density and protein content of the final product increased as the percentage of EWP increased in the formulation. the total colour difference measurement showed a significant increase ( P < 0.01) in brown colouration at 4.5% EWP.