Three-phase induction motor operating from single-phase supply with an electronically controlled capacitor

In this paper the performance of a three-phase induction motor operating from single-phase supply with a new electronically controlled capacitor using an electronic switch in series with a fixed capacitor to achieve a minimum unbalance of the motor phase voltages at all loading conditions is proposed. No mechanical or centrifugal switch is used here. Basic system operation, theoretical analysis, simulated and experimental results in comparison with conventional operation using one and two fixed capacitors are presented in this paper. The optimum effective capacitor value can be on-line adjusted at any operating speed by periodically changing the duty cycle of the controlled switch to achieve minimum unbalance in phase voltages to improve the motor performance at different speeds.     

重构在框架开发中的研究与应用

框架和应用能够通过重构相互促进,应用和框架的并行开发可以加速框架的开发过程.从框架与应用的中间层,框架与应用的接口的结构和形式等方面,对此过程中的重构方法进行了讨论,提出了几种适应于框架与应用并行开发的重构手段.     

Polyol-mediated synthesis of water-soluble LaF3:Yb,Er upconversion fluorescent nanocrystals

Well-crystallized LaF₃:Yb,Er nanoparticles were prepared by the polyol method and three kinds of polyols (glycol, diethylene glycol and glycerol) were chosen as the reaction medium respectively. All of the obtained LaF₃:Yb,Er nanoparticles have roughly spherical shapes, and the average sizes of these nanoparticles ranged from 5 to 7 nm. These nanoparticles could be well dispersed in water or ethanol to form colloidal solutions. When these nanoparticles were excited by the 980 nm laser, several upconversion emissions were observed.     

The evolution of Cu-rich domains in the Cu60Zr30Ti10 metallic glass by ASAXS

The structure of the melt-spun Cu₆₀Zr₃₀Ti₁₀ metallic glass is investigated by anomalous small angle X-ray scattering (ASAXS). It is confirmed that the compositional segregation in the diameter range of 30–50 nm exists in the as-quenched state. ASAXS results have convincingly shown the aggregation of Cu atoms and the formation of Cu-rich domains in the amorphous matrix. The Cu-rich domains grow slightly with low growth rate below the glass transition temperature, while the sizes of these domains drastically increase with high growth rate in the supercooled liquid temperature region. The Cu-rich domains are presumed to be associated with nucleation for the primary crystallization process.     

烧结助剂对Si3N4/BN层状复合陶瓷结构与性能的影响

研究了MgO—Y2O3—Al2O3体系(相应的层状复合陶瓷试样记为A)、Y2O3—Al2O33体系(相应的层状复合陶瓷试样记为B)及La2O3—Y2O3—Al2O3体系(相应的层状复合陶瓷试样记为C)烧结助剂对Si3N4／BN层状复合陶瓷结构与性能的影响．研究表明：在相同的烧结工艺下，试样A、B、C的抗弯强度分别为700、630、610MPa，断裂功分别为2100、1600、3100J／m^2．试样A、B以脆性断裂为主，裂纹偏转现象不明显，而试样C的载荷-位移曲线显示了明显的“伪塑性”特征，裂纹的偏转与扩展现象明显．试样A中Si3N4晶粒大小不均且长径比较小，而试样C中长柱状Si3N4晶粒发育完善，有较大的长径比．     

On the relationship between parity space and approaches to fault detection

Parity space approach and H₂ approach are two important fault detection approaches. This paper studies the relationship between these two approaches, which reveals frequency domain characteristics of the optimal solution of the parity space approach on the one side and provides a numerical solution of the H₂-optimal design of residual generators on the other side.     

Robust Digital Terrestrial TV Broadcasting System with Error-Resilient Schemes

In this paper, error-resilient schemes are proposed to support robust video transmission for digital terrestrial TV broadcasting (DTTB). In particular, a temporal error concealment incorporated with a low-complexity block-matching is developed, achieving an effective reception of predictive pictures in harsh terrestrial environment. Special algorithms are also designed for isolated I-pictures. Moreover, combined with an intra/inter case prediction, an adaptive error concealment scheme is further contrived to fit for different error conditions. Extensive simulations have been conducted under various DTTB channel conditions, even with a very high packet error rate, to verify the effectiveness of the proposed schemes.     

A linear RFQ ion trap for the Enriched Xenon Observatory

The design, construction, and performance of a linear radio-frequency ion trap (RFQ) intended for use in the Enriched Xenon Observatory (EXO) are described. EXO aims to detect the neutrinoless double-beta decay of ¹³⁶Xe to ¹³⁶Ba. To suppress possible backgrounds EXO will complement the measurement of decay energy and, to some extent, topology of candidate events in a Xe filled detector with the identification of the daughter nucleus (¹³⁶Ba). The ion trap described here is capable of accepting, cooling, and confining individual Ba ions extracted from the site of the candidate double-beta decay event. A single trapped ion can then be identified, with a large signal-to-noise ratio, via laser spectroscopy.     

A frequency domain approach to fault detection in sampled-data systems

This paper deals with fault detection problems in sampled-data (SD) systems. A tool is first introduced for the analysis of intersample behavior of SD systems in the frequency domain from the viewpoint of fault detection and isolation. Based on it, a direct design approach of fault detection systems for SD systems is proposed, and further the problem of full decoupling from unknown disturbances is studied.     

A Multi-View Face Recognition System

In many automatic face recognition systems,posture constraining is a key factor preventing them from application.In this paper a series of strategies will be described to achieve a system which enables face recognition under varying pose.These approaches include the multi-view face modeling,the threschold image based face feature detection,the affine transformation based face posture normalization and the template matching based face identification.Combining all of these strategies,a face recognition system with the pose invariance is designed successfully,Using a 75MHZ Pentium PC and with a database of 75 individuals,15 images for each person,and 225 test images with various postures,a very good recognition rate of 96.89% is obtained.