Evaluation of superposition technique for calculating cogging torque in permanent-magnet brushless machines

We evaluate the superposition method for calculating the cogging torque in permanent-magnet brushless machines, the resultant torque being synthesized from cogging torque components associated with a pair of magnets. Although finite-element analyses and measurements show that the resultant cogging torque cannot be synthesized directly from the torque components due to a single magnet, we use the concept of a fictitious single magnet to analytically establish the relationship between the cogging torque and key design parameters. The method is particularly useful in assessing the influence of the slot number and pole number combination.     

XML技术在控制回路识别中的应用

介绍了一种基于XML的可视化软集成电路系统,给出其设计思想和体系结构。并在总结前人控制回路识别方法的基础上,推出XML技术在回路识别方法中的应用。     

Core-referenced ratiometric fluorescent potassium ion sensors using self-assembled ultrathin films on europium nanoparticles

Nanoengineered fluorescent sensor coatings on colloidal carriers have been developed for use intracellularly. These nanosensors are fabricated via the electrostatic layer-by-layer self-assembly technique to form ultrathin polyelectrolyte films containing indicators on fluorescent nanoparticles. The fluorescent nanoparticle templates and the fluorescent indicator are chosen such that their optical properties are complementary, enabling the inert nanoparticle templates to serve as internal intensity references for the fluorescent probe. In this work, the potassium ion indicator, potassium-binding benzofuran isophthalate potassium-binding benzofuran isophthalate was immobilized within poly(styrene sulfonate)/poly(allylamine hydrochloride) films assembled on the surface of fluorescent europium nanoparticles. The indicator retains its sensitivity to potassium ions after immobilization within the films and exhibits sensitivity to increases in potassium concentration over a broad range. In addition, the sensors demonstrate excellent leaching stability, with less than 1% of loaded indicator leached after 14 days of wet storage. The core-referenced nanosensor scheme described here is a simple and elegant way to co-immobilize fluorescent indicator and intensity reference within a single nanoscale package, which may be deployed intracellularly; furthermore, the separation of fluorescent indicator from the cellular environment is attractive, as it may prevent complications due to use of liquid-phase fluorescent sensors intracellularly, such as cytotoxicity and probe compartmentalization.     

Knight：一个通用知识挖掘工具

现有知识挖掘系统普遍存在通用性不好，发现方法单一的弱点。     

Hochdynamische Leistungsregelung eines dreiphasigen Hochleistungs-netzstromrichters zur Speisung von Gleichspannungszwischenkreisen

Übersicht In dieser Arbeit wird ein neues Regelungsverfahren für U-Netzstromrichter sehr hoher Leistung beschrieben. Die Einspeisungsschaltung besteht aus zwei GTO-Dreipunktstromrichtern, die über Dreiwicklungstransformatoren mit in Stern bzw. Dreieck geschalteten Sekundärwicklungen ans Netz geschaltet sind. Für den Betrieb als Netzstromrichter wird eine Steuerstrategie entwickelt, wobei eine möglichst geringe Verzerrung der netzseitigen Spannung unter Einhaltung der geringen zulässigen Schaltfrequenz der Ventile das Ziel ist. Die Regelung für netzfreundlichen hochdynamischen Energieaustausch zwischen Netz und Zwischenkreis ist auf der Basis der sogenannten Stromrichterflußbahn konzipiert.

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Highly dynamic control for a three-phase high power AC/DC converter

Contents This paper describes the implementation of a new control approach for a high power three-phase AC/DC converter. The converter consists of two three-level inverters connected to the line via a three-winding transformer with the secondaries connected in star and delta. The control scheme is developed to minimise the network distortion voltage while keeping the small permitted switching frequency of the valves. The control for highly dynamic exchange of energy between the network and the dc link voltage is proposed on the basis of the converter voltage space vector time integral.

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Diese Arbeit wurde von der Deutschen Forschungsgemeinschaft gefördert.     

Dielectric breakdown of a residual SF6 plasma at 3000 Kunder diatomic equilibrium

A residual plasma at 3000 K and under diatomic equilibrium is left inside an axially blown gas blast SF₆ circuit breaker after the thermal extinction of an arc. The breakdown of such a residual plasma depends on the electron generation and loss mechanisms. Altogether six ionization and chemical reactions relevant to the time scale of breakdown have been taken into account. It has been found that the critical field strength for breakdown is proportional to the pressure and is equal to 2.0 V/(m.Pa). This field strength is in agreement with the experimental results     

德布罗意波及其非相对论近似

通过分析德布罗意义和速度特性，说明了它是相对论意义下的波，讨论了在非相对论量子力学中，以经典能量代入德布罗意关系式进行了计算的原因。     

Application of fuzzy logic in computer-aided VLSI design

Application of fuzzy logic structures in CAD of digital electronics substantially improves quality of design solutions by providing designers with flexibility in formulating goals and selecting tradeoffs. In addition, the following aspects of a design process are positively impacted by application of fuzzy logic: utilization of domain knowledge, interpretation of uncertainties in design data, and adaptation of design algorithms. We successfully applied fuzzy logic structures in conjunction with constructive and iterative algorithms for selecting of design solutions for different stages of the design process. We also introduced fuzzy logic software development tool to be used in CAD applications     

FEM for evaluation of weight functions for SIF, COD and higher-order coefficients with application to a typical wedge splitting specimen

In the evaluation of accurate weight functions for the coefficients of first few terms of the linear elastic crack tip fields and the crack opening displacement (COD) using the finite element method (FEM), singularities at the crack tip and the loading point need to be properly considered. The crack tip singularity can be well captured by a hybrid crack element (HCE), which directly predicts accurate coefficients of first few terms of the linear elastic crack tip fields. A penalty function technique is introduced to handle the point load. With the use of these methods numerical results of a typical wedge splitting (WS) specimen subjected to wedge forces at arbitrary locations on the crack faces are obtained. With the help of appropriate interpolation techniques, these results can be used as weight functions. The range of validity of the so-called Paris equation, which is widely used in the evaluation of the COD from the stress intensity factors (SIFs), is established.