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This paper proposes an analytical multi-element thermal modelling method for predicting the sleeve and magnet thermal fields for high-speed permanent magnet machines (HSPMMs). The analytical model is developed based on the conduction heat equations and the continuity equations of heat transfer. The rotor temperature distributions and hotspots can be accurately predicted with the aid of the boundary conditions from a lumped-parameter thermal model. The proposed method is applied to investigate the influences of different PM segmentations and rotor sleeve materials on the rotor thermal performance. Based on a 3-slot/2-pole HSPMM, it is shown that the PM segmentation parallel to the magnetisation direction together with the carbon fibre sleeve can significantly ease the rotor thermal stress. The finite element analyses and experiments have been used for validation.

In this paper, a novel magnetization state (MS) control method is proposed by utilizing torque deviation to achieve the MS closed-loop control for variable flux memory machine. Firstly, the relationship between the MSs and the demand magnetizing current pulses is built into a look-up table, which also contains information on the flux linkages and the dq-axis inductances under different MSs. Afterwards, a model-based torque calculation is adopted for torque estimation, and then, the torque deviation between the present MS and the target MS can be obtained and utilized to generate the MS switch signal, which will determine the type of MS manipulation. Subsequently, the calculated torque will also be used for real-time monitoring of MS. The feasibility of the proposed MS control method is verified by simulation. Finally, experiments are carried out on a hybrid magnet memory machine control system for validation.

Based on a simple analytical model, combinations of primary and secondary pole numbers for linear switched-flux permanent magnet (LSFPM) machines with odd pole number of primary are compared, with respect to back electromotive force (EMF) and electromagnetic thrust force. The winding configurations are also determined according to the coil-EMF vector diagram. Based on optimized LSFPM machines, some basic electromagnetic performances are compared in LSFPM machines with 9 primary poles. It is shown that the secondary pole number should be close to the primary pole number and the higher secondary poles can lead to a better performance.

The free piston energy converter (FPEC) is a combination of a combustion engine and a linear electrical machine which develops a new type of power unit for hybrid electric vehicle. The movement component of the FPEC is a multi-input multi-output coupling nonlinear system. As a consequence, an adaptive decoupling control strategy is presented in this paper for controlling the piston motion. Two neural PID controllers in parallel are employed as the decoupling controller, in which PID gains are auto adjusted by supervised Hebbs learning rule. Simulation results show that the utilization of the neural adaptive PID decoupling controller gives rise to stabilize the piston motion.

According to the requirement for variable-frequency power supply when a liner motor runs in a household appliance, a variable frequency speed regulation system of three-phase SPWM is designed based on ATmega48 Micro-controller. The hardware structure, the SPWM technology of software program and V/f control strategy are analyzed. In the end of this paper, experiment waves are illustrated. The results show that the running of the system is simple and convenient; the reliability of the system is excellent.

The operation of linear oscillating system is complicated, involving system nonlinearities of both actuator and load, and variations of driving frequency in order to track the mechanical resonance. In this paper, the state-variable modeling technique is used to analytically investigate the influence of actuator reluctance force on the performance of linear oscillating systems. The analytical derivations will be validated by simulations, and good agreements are achieved.

This paper presents a sinusoidal permanent magnet (PM) shaping technique with third harmonic to improve the electromagnetic thrust force in linear slotless PM machines without sacrificing the thrust force ripple. Slotless PM linear machine possesses relatively low thrust force ripple due to the absence of cogging force, compared with slotted topology. However, thrust force ripple of the machine with rectangular PM shape still exists due to nonsinusoidal airgap flux density distribution produced by PMs. Sinusoidal shaping techniques can be used to reduce the thrust force ripple but the average thrust force is reduced as well. Therefore, a simple PM shaping technique with optimal 3rd harmonic is presented to improve the output thrust force but not to increase the thrust force ripple. The sinusoidal plus 3rd harmonic shaping technique is analytically demonstrated together conventional sinusoidal shaping method and verified with finite element method. The results show that the electromagnetic performance can be significantly improved.

This paper proposes a new type of linear motor based on the concept of variable flux reluctance motor (VFRM). By adopting segmented primary stator, the segmented linear VFRM (SLVFRM) can eliminate asymmetry between phases due to end-effect. Meanwhile, multi-phase SLVFRM of any number of phases can be obtained by adjusting number of segments directly. The stator/mover tooth pitch combination and segments arrangement rules are also illustrated. An optimized 3-phase SLVFRM is analyzed by finite element analysis, with focus on characteristics such as cogging force, back-EMF and winding inductances. Further, both brushless AC (BLAC) and brushless DC (BLDC) drive for SLVFRM are investigated. Besides much smaller force ripple, BLDC drive can obtain higher average force at same RMS current due to trapezoidal back-EMF. The force characteristicwith variousAC and DC currents and current angles are also investigated in the paper, and it shows that SLVFRM has negligible reluctance force while keeping the same AC and DC currents is optimal for maximum efficiency operation under a fixed copper loss.

This paper proposes a linear sandwiched switched flux permanent magnet (LSSFPM) machine and two double-sided linear switched flux permanent magnet (LSFPM) machines havingtoroidal windings. Bothmachines are optimized and then compared with the conventional 6-slot/5-pole LSFPM machine. It is found that the proposed machines exhibithigher magnet usage efficiencies than the conventional LSFPM machine, and the double-sided machines show shorter end-windings, which are benefited from toroidal windings. The performance, including back-EMF, cogging force and average thrust force, are analyzedby two-dimensional (2-D) finite element analysis (FEA).

For embedded power generation within civil gas turbine engines, generators are anticipated to endure high rotor speeds coupled with large rotor diameters. With variable frequency permanent magnet generators finding increased roles because of the perceived higher torque density, the issue of rotor integrity becomes a critical issue. Although banding has been previously used in surface mounted PM (SPM) machines, they inevitably increase the airgap and hence reduce the torque capability of the machine. The flux-switching PM (FSPM) machine has been an intense topic of research for many years. By combining its armature and field sources in the stator, its rotor is a passive single piece, salient steel lamination, making it inherently suitable for high speed applications. This study compares both machines when optimised for high speed applications by designing the rotors of both machines for mechanical integrity and comparing the electromagnetic performance. The electromagnetic trade off in the mechanical optimisation of the FSPM machine is found to be negligible, in contrast to the ∼33 reduction of SPM flux linkage because of the increased airgap length. The performance of FSPM machine is validated on a scaled FSPM prototype.

This article describes a novel algorithm for cosmicray rejection in single spectroscopic CCD images. This algorithm is based on a variation of template matching. It focuses on identifying those pixels belong to spectra, while other conventional algorithms tried to locate the cosmicray hits directly. The main principle is applying template matching to find suspicious blocks, which is followed by surface patching to locate the legitimate pixels accurately. Therefore, the rest pixels are the ones corrupted by cosmicray hits. Meanwhile, almost all the parameters are automatically extracted from the images. Examples of its performance are given for both simulated and observed images. It shows an advantage of significantly low false alarm rate with relatively high detection rate © 2009 WILEYVCH Verlag GmbH & Co. KGaA, Weinheim

Internal stator winding faults in salient-pole synchronous machines can cause serious damage to a machine and the system to which it is connected. Thus, it is highly desirable to be able to accurately model their transient behaviour and to predict the resulting currents and voltages in order to develop appropriate protection schemes, particularly for high power machines. Based on the Multi-loop Circuit Method, a general mathematical model for a salient-pole synchronous machine with internal faults is established, and subsequently employed to simulate both the steady-state and transient behaviour for three different types of internal fault. Predicted results are validated by experimental measurements.

Permanent magnet brushless machines employing multipole Halbach magnetised rotors are being developed for various applications, since they offer a number of attractive features. Alternative Halbach machine topologies are reviewed, and the realisation of Halbach magnetised magnets from pre-magnetised sintered rare earth magnet segments (which approximate the Halbach magnetisation distribution and thereby compromise their performance), and as bonded isotropic and anisotropic NdFeB ring magnets (which are subsequently impulse magnetised with a Halbach field distribution), is considered. Radial- and axial-field, slotted and slotless, rotary and linear (tubular and planar), and spherical Halbach magnetised brushless machines are described, and potential applications, including a motor/generator for a high-speed flywheel peak power buffer, high-performance linear and rotary servo motors, and passive magnetic bearings are considered.

2D and 3D finite-element techniques are used to investigate the influence of geometric asymmetries and the leading dimensions of the stator core, namely the diameter and thickness of the yoke, the width and number of poles, the lamination notches, and the stator windings on the natural frequencies and vibration modes of switched reluctance motors. Predictions are validated against measurements on various experimental models. Both finite-element analysis and experimental measurements are used to quantify the influence of the mass and stiffness of the laminated core and the windings on the natural frequencies and vibration modes, and thereby to obtain the effective material properties.

Acoustic noise emissions from a direct torque controlled (DTC) induction motor drive are investigated. Due to the hysteresis control of the flux and torque, DTC results in a variable switching frequency and dispersed voltage and current harmonic spectra. It is shown that both the bandwidths of the flux and torque hysteresis controllers and the equivalent modulation indices can have a significant influence on the switching frequency and the spread spectrum of the harmonic content. The acoustic noise is compared with that which results with space vector PWM (SVPWM) and random PWM (RPWM), and is shown that, in contrast to SVPWM, which results in cluster harmonic spectra and tonal acoustic noise, DTC and RPWM controlled drives have similar spread spectrum features and atonal noise emissions which are generally regarded as less irritating. However, the wideband of their harmonic spectra is more likely to induce mechanical resonances, and thus may sometimes result in higher noise emissions. The influence of the load and the flux level on the emitted noise is investigated, and it is shown that the noise level increases with the load, but there is an optimal flux level for minimal noise.

A new strategy for generating abzyme was developed. Glutathione peroxidase (GPX, EC 1.11.1.9 ) is one of the important members of antioxidation enzyme system; it catalyzes the reductions of a variety of hydroperoxides in presence of glutathione (GSH). We have first prepared the monoclonal antibody (McAb) with GSH binding sites, then incorporated GPX catalytic group selenocystein (SeCys) into the antibody combining sites by using chemical mutation. Thus the mutated antibody displays high GPX activity, which approaches the magnitude level of native GPX, exhibits the kinetic behavior similar to native GPX, and has some advantages over native GPX.Copyright 1994, 1999 Academic Press

Improved methods for predicting the electromagnetic noise radiated by electrical machines are presented. The preferred method is based on the calculation of the sound-pressure and stator-vibration velocity distributions on a finite-cylindrical acoustic model. It results in a simple formula for calculating the acoustic power from the relative sound intensity and the stator-surface vibration, and is therefore eminently suitable for use during routine design. The method eliminates the need to calculate the sound-pressure and air-velocity distributions around a machine, as is required for existing methods. It can also account for the effect of an axial variation of the radial vibration. In an alternative method the relative sound intensity is calculated from a spherical acoustic model in which the radial vibration of a machine is expressed as a function of the circumferential mode order in the form of a Fourier series rather than a Legendre series, as in previous analyses. This makes it possible to use Fourier series throughout the various stages leading up to the prediction of electromagnetic noise. Predictions of the relative sound intensity from the different models are compared, and the sound-pressure distribution and the acoustic power are investigated both theoretically and experimentally on a TEFC 3-phase induction motor. It is shown that methods based on a spherical acoustic model are only geometrical and physical approximations, whilst a finite-cylindrical acoustic model is more generally applicable.

The donor- and acceptor-like levels at ZnSe/GaAs heterovalent interfaces with different interfacial bonding configurations have been observed by photoluminescence, and electric fields at the interfaces have been detected by photovoltage measurements. The most striking feature is the appearance of a new band near 1.405 eV, followed by several replicas due to LO phonons at energy 33 meV. This band is only present in samples of ZnSe grown on Zn-treated As-rich GaAs surfaces and we tentatively attribute the peak to a free electron--acceptor recombination. The PL spectra from an Se-treated Ga-rich sample shows two dominant emissions at 1.45 and 1.46 eV which may be related to donor-like levels at the interface, and have been observed for the first time in our samples. Photovoltage measurements show that the electric field at the interface is quite large in a Zn-treated As-rich sample but is small in a Se-treated Ga-rich sample; this means the electric charges at the interface of ZnSe/GaAs are different for these two kinds of samples.

We successfully prepared the Se-containing abzyme (Se-abzyme) with glutathione peroxidase (GPX) activity and futher studied its physicochemical and enzymic properties and stabilities. Data showed that the isoelectric point of the abzyme was 6.95-7.08, and its molecular weight was 158 KD. The ranges of optimum pH and temperature of the Se-abzyme were wider than the native GPX. The store stability of the abzyme was higher than the native GPX. The Se content in the abzyme was found to be 5 mol Se/mol abzyme by X-ray photoelectron spectrum, and binding constant 1.11×107M−1by using ELISA method. The Se-abzyme was inhibited competitively by dithiobis (2-nitrobenzoic acid) (DTNB), and inhibition constant was determined to be 1.25×10−3M−1.

The power dependence and the temperature dependence of the luminescence intensity of ultra-thin pseudomorphic ZnSe quantum wells, grown on high index GaP substrates were investigated. A blue shift of PL with power excitation is mainly related to the band filling of interfacial ZnSe clusters while it is found that the piezoelectric field has only a small influence. Luminescence spectra of ultra-thin ZnSe/ZnS single quantum wells are characterized by an excitation dependent excitonic localization phenomenon.

Ultrathin ZnSe quantum structures embedded in ZnS are investigated in a wide range of atomic layer epitaxy (ALE) growth conditions. The optical properties of the grown ZnSe/ZnS quantum structures are studied by photoluminescence (PL), photoluminescence excitation (PLE), and cathodoluminescence (CL) spectroscopy. A sharp PL emission is observed at around 3.05 eV, which reveals exciton localization tentatively associated with quasi-0D ZnSe quantum dots (QDs) formed on a wetting layer of 1 monolayer (ML) ZnSe.

There are two potential causes of cogging force in linear permanent magnet motors, resulting from the slotting and the finite length of the iron-cored armature. The paper is concerned with slotless motors, for which a technique is described for minimising the cogging force which is produced when the armature has a mild steel sleeve (yoke). By analysing the cogging-force waveform developed at one end of the sleeve and optimising its axial length so that an opposing cogging-force waveform is developed at the other end, it is possible to obtain nearly zero resultant force. The technique has been validated on a prototype motor and found to be effective and simple to implement.

A novel technique, referred to as software waiting loop length control (SWLLC), for reducing the radiated EMI from microprocessor-based PWM drive systems is presented. By randomly changing the length of the software waiting loops, the energy concentrated into discrete bands by the action of periodic signals on the external and internal buses of the microprocessor system can be spread across a larger frequency range. Using this technique, significant reduction of radiated interference levels has been observed in a typical PWM drive system.

The white matter of resected temporal lobes from patients with intractable complex partial seizures shows increased cellularity which appears to be related to glia and neurons. This study, using quantitative methods, defines an increase in glial cell numbers and a significant increase in glial nuclear size within a defined area of white matter in the lateral temporal lobe. Evaluation was made on specimens from ten patients with complex partial seizures compared with two patients with non-epileptic brain lesions and five autopsy patients with no neurologic disease. The importance of recognizing these alterations in glia and the possible relevance to the pathoetiology of epilepsy are discussed.