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。     

Basic Study on Islanding Detection Method for PV Systems by Harmonic Impedance Detection in Case of Including Induction Motor in Load System

It is important that photovoltaic (PV) systems detect islanding caused by power system faults to ensure electrical safety. Thus we propose a novel islanding detection method which detects the harmonic impedance by injecting harmonic currents synchronized with the exciting current harmonics of the pole transformer. For the case in which an induction motor load is included in the load system, basic experiments on islanding detection and simulation analysis are conducted to verify the effectiveness of the proposed method.     

Computed tomographic evaluation of gas hole formation and structural quality in Gouda‐type cheese

Computed tomography (CT) was performed on Gouda‐type cheese during ripening to evaluate gas hole formation and structural quality. The cheese was exposed to different ripening conditions, including variations in ripening temperature and concentration of butyric acid bacteria. Computed tomography images were obtained every 2 weeks for 16 weeks to assess the volume, shape and location of gas holes. The results demonstrate that CT makes the nondestructive monitoring of cheese gas hole formation and evaluation of the structural features of cheese possible throughout the ripening period.     

Optimum checking request policies

We discuss checking policies, in which an inspector is requested to perform the check, for a ono-unit system. Applying the unique modifications of Markov renewal processes, we analyse the stochastic behaviour of each CR policy (checking request policy) and CRSL policy (checking request and surveillance limit policy), where it is assumed that the failure time for each unit and the inspector's arrival time havo arbitrary distributions. Introducing replacement eosts, the request for the inspector to perform the check, system failure and surveillance, we derive the optimal policies which maximize the cost effectiveness under suitablo conditions for each model. In particular, wo discuss the optimal policies as a non-linear programming problem with two variables.     

Elastic Moduli and Refractive Indices of Aluminosilicate Glasses Containing Y2O3, La2O3, and TiO2

Glasses in the system Al₂O₃-Y₂O₃-SiO₂, containing TiO₂ and La₂O₃, were investigated. Glasses of high refractive index and elastic modulus were developed. The observed Young's and shear moduli of these glasses show good agreement with theoretical values. Agreement was also found between the observed and calculated values of refractive index when the Appen's empirical coefficients were used.     

EXTRACTION RATE OF W-AMYL ACETATE WITH ALKALINE HYDROLYSIS IN AQUEOUS PHASE

It is confirmed experimentally that a “Diffusion controlled slow reaction model'“ explains very well the alkaline hydrolysis of n-amyl acetate at constant inlerfacial area. Mass transfer coefficient obtained from the model agrees well with that obtained from pure mass transfer experiment. Mass transfer coefficient can be correlated against Reynolds number, Schmidt number and vessel dimensions. Effect of diluents and solutes can also be explained using the above model. From the extraction rate of H-amyl acetate dispersed in aqueous phase in an agitated vessel, the second order reaction rate constant for hydrolysis of the ester with alkali in aqueous phase is estimated based on the above model. The estimated value of second order reaction rate constant for H-amyl acetate is almost identical to that for iso-amyl acetate or n-butyl acetate.     

Formation and microwave dielectric properties of Sr(Ga0.5Ta0.5)O3-based complex perovskites

The Sr(Ga0.5Ta0.5)O3-based perovskites with O2- and/or Sr2+ vacancies were formed by changing the A-site and/or B-site cation ratios. The Sr-deficient perovskites with a limited composition of Sr0.86(Ga0.36Ta0.64)O3 could be obtained, whereas oxygen vacancies were hardly created. The B′-site Ga3+ cation could be replaced with large Sc3+, In3+, Y3+, Nd3+ and La3+. The crystal symmetry of the complex perovskites changed from cubic (B′=Ga3+, Sc3+, In3+) to tetragonal (B′=La3+) through rhombohedral (B′=Y3+, Nd3+). The dielectric permittivities of these ceramics indicated no distinct dependence on the B′-site cation species. The temperature coefficient of permittivity might be associated with the symmetry change of the perovskite phases. Higher microwave Qf values, >Qf=38 000 GHz, were obtained for our complex perovskite ceramics, except with B′=La3+. This revised version was published online in July 2006 with corrections to the Cover Date.     

Novel Measurement of Hypoxanthine in Fish Using Direct Measurement Probe and Chemiluminescence Flow Injection Analysis

Direct measurements of hypoxanthine (Hx) in fish flesh were carried out using a sardine and a grunt twice with the same fish, and the average of 10 successive measurements (from 120 sec to 480 sec after pressing the probe against fish tissue) was taken as the Hx concentration by direct measurement. Results with two nearby tissues of one sample were 42.9 ± 4.9 μM and 42.6 ± 2.6 μM for the sardine, and 639 ± 33 μM and 598 ± 29 μM for the grunt. For sardine, Hx results from this direct method did not agree well with perchloric acid extraction measurements, but they were much better for grunt.     

Cu behaviors and effects of mine drainage in Kosaka River,Hokuroku mining district,Northeast Japan

Focusing on the origin of the heavy metal, this study aims to build an imputed method to estimate the heavy metal content in river water by making a distinction between the heavy metal of natural origins and that caused by human activities. Supported by GIS, Kosaka watershed within the Hokuroku basin was divided into several sub-watershed polygons and the outflows of water and Cu were calculated for each polygon. Compared with the natural origin, the dominant Cu emissions affected the river water more significantly in local. Based on the mass balance closure, the heavy metal content of Cu in the Kosaka River was estimated by the conflux accumulation of tributaries and mine drainages. The estimated Cu concentrations were checked by comparing with the actually measured values at monitoring points along the Kosaka River and the results are coincidence with each other in general. It is revealed that the mainstream water quality could be estimated by seizing the water quality of upstream tributaries and human drainages.     

岩石中主成分和微量成分X射线荧光分析的低稀释比玻璃融珠方法

采用ｍ样品：ｍ熔剂为１：２的低稀释比玻璃熔融技术，Ｘ射线荧光法测定岩石中的主成分和微量成分，既提高了灵敏度又不均质效应。与粉末压片方法相比，对硫的分析得到了更好的结果。同时，使用基本参数程序建立了一种新的校正方法来校正由于烧失量、烧增量、释释比或熔剂挥发而导致的分析误差。