Mie scattering from sphere structures in polymer blends

Polymer blends of transparent poly(methyl methacrylate) and polystyrene become opaque due to light scattering at the boundaries of the two polymers. The polymer blend is light brown when it is illuminated by white light. The coloring depends on the spherical domain structures existing in the polymer blend. The coloring was analyzed by using the rigorous Mie theory. The Mie results were compared with the semiempirical results previously reported by the authors. The wavelength dependence of theoretical scattering efficiencies on radii of scattering spheres from 0.05 to 1.2 μm was obtained for polystyrene spheres in poly(methyl methacrylate) matrix, and vice versa. The scattering at the short wavelength region is stronger than at the long wavelength region. The scattering efficiencies become almost constant in the visible wavelength region for sufficiently large spheres.     

感应电机无速度传感器矢量控制系统的定子电阻在线辨识

该文针对利用磁通观测器推算转子磁通的感应电机无速度传感器矢量控制系统，提出了定子电阻在线辨识法。在利用q轴磁通推算转速的基础上，该系统利用d轴磁通误差实现定子电阻在线辨识，该方案的优点是系统简单，解决了低速运行时电压模型的定子电阻变化对系统稳定性和速度控制精度的影响问题。数字仿真和实验结果验证了定子电阻在线辨识的必要性和该方案的有效性。     

Diagnosis Criterion of Abnormality of Transformer Winding by Frequency Response Analysis (FRA)

Frequency response analysis (FRA) is a powerful technique to detect internal abnormalities within power transformers. However, diagnosis criteria of power transformers by FRA have not been fully established yet. In this paper, a new evaluation method of degree of identification between two transfer functions is proposed. In the proposed method, a frequency window is employed and cross‐correlation factor is calculated with moving the window. Furthermore, the proposed method is applied to transfer functions of real transformers with or without some abnormalities. Based on this discussion, objective criteria for diagnosis of abnormalities of transformer windings by FRA are proposed. The proposed criteria are based on a few data of transformers with some abnormalities. Therefore, the proposed criteria are tentative and they would be improved by accumulation of further data.     

广色域印刷

一、广色域印刷产生的背景是什么呢: 1.时代发展的需要 当前,利用数码相机进行原稿输入的普及,喷墨打印机的广泛使用,以及随着RGB数字工作流程体系的构筑,为了适应这佯的印刷环境,使得广色域的印刷开始并将得到广泛的应用.     

A LRT Control Method Using Sensor Information in Distribution Systems with a Large Amount of PVs and EVs

It is of prime importance to maintain voltage profile within the proper range in distribution systems with a large amount of photovoltaics and electric vehicles (EVs). In particular, there is a possibility that line drop compensation (LDC) logic, which is utilized for the control of load ratio tap transformer (LRT) does not work properly when reverse power flow is included partially. Hence, in this paper, we have developed a new LRT control method based on the sensor information supposing that some section switchgears with sensors are introduced in the future distribution systems. Specifically, the extreme value of voltage profile is estimated by convergence calculation in the section between the section switchgear with sensor and LRT. Moreover, the voltage at the end node can be estimated by LDC method using sensor information of section switchgear. The proposed method was tested using a distribution system model and its effectiveness was shown.     

Two-dimensional normal zone propagation in BSCCO-2223 pancake coils

We present the results of an experimental and analytical study of two-dimensional normal zone propagation in pancake test coils, wound with silver-sheathed BSCCO-2223 tapes. Two test coils were studied in detail, one having three and the other eight layers. Each test coil was housed in an adiabatic environment whose temperature (20-70 K) was controlled and maintained by a two-stage G-M cryocooler and placed in a background field (0-6 T) generated by a Bitter magnet. With a test coil carrying a transport current (0-200 A), a local heat disturbance was applied by a heater attached to the outermost layer of the coil. The resulting electrical and thermal responses of the coil were recorded with voltage taps and thermometers attached to the coil. A normal zone propagation code was developed to accurately simulate the voltage and temperature responses of each coil for both quenching and recovering events. The code solves the nonlinear transient heat diffusion equation in two-dimensional cylindrical coordinates with a finite difference method. As an application of this code, a two-coil system, with each coil comprised of one double pancake wound with silver-sheathed BSCCO tape, was studied for its quench behaviour as one of the coils was driven normal locally. The simulation results indicate that the value of a shunt resistor connected across the terminals of each coil has a profound effect on the level of hot-spot temperature reached in the quench initiation spot.     

Integral-equation approach to parameter identification without consideration of initial conditions

The widely used integral-equation approach for identification of continuous systems is investigated. Attention is focused on the initial condition problem which has been puzzling many researchers. A new calculation procedure for the multiple integrations of the system signal derivatives is proposed and a new integral-equation approach is proposed for which the initial conditions need not be identified as unknown parameters. Therefore, the burden of the identification algorithms can be greatly reduced compared to conventional methods. Discussions on the unification of the integral-equation approach with the other methods are also provided.     

Comprehensive evaluation of new urban transportation systems by AHP

Many different kinds of transportation systems such as ‘group rapid transit’, etc., have recently been presented as ideal urban public transportation systems. When planning to introduce such a new transportation system into a city, it is necessary to select the most desirable system for that city from those that have been proposed. The comprehensive evaluation of transportation systems must reflect various aspects such as the costs of construction and maintenance and the viewpoints or both the system users and the local inhabitants. This makes it one of the most difficult and yet vitally important problems in public transportation planning. The analytic hierarchy process (AHP) developed by T. L Saaty is straightforward and has the feature that it can deal with both qualitative and quantitative factors at the same time, and it is suitable for applying to complex evaluation problems, In this paper, three transportation systems are proposed for one of the newly planned towns in Kansai Cultural and Academic Research Complexes, and a comprehensive evaluation of these systems is performed by applying the AHP. It has been proved through the process of evaluation that information which is very useful in reaching a consensus for choosing a system can be obtained.     

The structural color in the polymer blend of poly(methyl methacrylate) and polystyrene

Morphologic and optical studies were performed on the coloring of poly(methyl methacrylate) (PMMA) and polystyrene (PS) opal sheet. It was concluded that the origin of color is the polymer structure itself. There exist three structures in the colored polymer blend: small PS spheres are dispersed in the PMMA matrix, and each PS sphere contains smaller PMMA spheres within it. The dimension of the smaller PMMA spheres is of the same order as the wavelength of visible or near-infrared light. The coloring measured by a spectrometer is well interpreted by the equation of structural color derived by Clewell qualitatively.