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We present measurements of the small-field magnetic response of non-oriented 1.8 wt% SiFe and rapidly-quenched 6.5 wt% SiFe as a function of various magnetic histories. The first part of the return branch originating from a given turning point ([H.sub.0],[B.sub.0]) was fitted by the quadratic law B - [B.sub.0] = [[micron].sub.rev] (H - [H.sub.0]) [+ or -] (b/2) [(H - [H.sub.0]).sup.2] and the dependence of [[micro].sub.rev] and b on ([H.sub.0],[B.sub.0]) and magnetic history was studied. [[micro].sub.rev] and b approximately follow the laws [[micro].sub.rev] [varies as] [1 - [([B.sub.0]/[B.sub.m]).sup.2]] + const, b [varies as] [1 - [the absolute value of][B.sub.0]/[B.sub.m]], [[micro].sub.rev] [varies as] exp[-[[H.sub.0].sup.2]/2[[[Sigma].sub.[micro]].sup.2] + const, and b [varies as] exp[-[[H.sub.0].sup.2]/2[[[Sigma].sub.[micro]].sup.2].

Classically, low frequency losses in soft magnetic materials and ferrites in particular are measured by flux metric method under sinusoidal waveform excitation voltage. However, in typical application of modern power electronics, the frequency currently exceeds 100 kHz. This feature is at the origin of a difficulty: the phase shift between current and voltage can be disturbed by current probe delay. Thus, the results can be affected by large errors. As a consequence, it becomes more and more important to develop alternative methods to measure losses in magnetic materials. It is proposed to use calorimetric method which is by principle free of the above mentioned problems. The experimental device is described in details and the results are reported for experiments conducted on a commercial Mn–Zn ferrite under sinusoidal waveform regime for frequencies varying from 10 to 200 kHz. Comparisons with flux metric measurement show that significant differences appear typically for Bf products above 5000 V/m2 (50 kHz×100 mT). [ABSTRACT FROM AUTHOR]

Presents a study which discussed the computation of the macroscopic fields inside ferromagnetic laminations. Theoretical model; Measurement setup; Experimental and numerical results; Conclusions.

In this paper, an analytical method for the calculation of the electromagnetic field in the airgap of a permanent-magnet synchronous machine is developed, so as to compute the torque of the machine. Such a work is applicable to different machine topologies (even for salient rotor ones), when a two dimensional approximation of the structure is possible. This analytical model can be useful in an optimization task. In the first part, the analytical method of the field computation is explained in detail, both for the magnet's field, and for the armature reaction field. The results are compared to finite elements analysis. [ABSTRACT FROM AUTHOR]

Chemical footprints left behind by true bugs are perceived as contact kairomones by scelionid egg parasitoids. Female wasps encountering a contaminated artificial substrate display a characteristic arrestment posture, holding the body motionless and antennating the surface. In the system Nezara viridula (L.) and its egg parasitoid Trissolcus basalis (Wollaston), previous studies have shown that the kairomone mediating such behavior is part of N. viridula's cuticular hydrocarbons (CHC) and furthermore that the wasp's ability to discriminate host male and female footprints is mainly based on the presence/absence of nonadecane (nC(19)). In this study, the effect of epicuticular waxes of leaves of broad bean, Vicia faba, on wasp responses to footprints of N. viridula females were investigated. Approximately 20% of T. basalis females displayed an arrestment posture when released on the adaxial leaf surfaces of broad bean plants with intact wax layer and without host chemical contamination; whereas approximately 70% of wasps displayed the arrestment posture when intact leaves were contaminated by host female footprints. Adaxial leaf surfaces of broad bean plants dewaxed with an aqueous solution of gum arabic and afterwards contaminated by N. viridula females induced arrestment responses in about 10% of female wasps; the same percentage of arrestment (10%) was observed when the wasps were released on leaves contaminated by host females and subsequently dewaxed. The side of the polymer film that was appressed to the leaf surface, peeled from the contaminated leaves, induced an arrestment posture in about 95% of observed wasps. Scanning electron microscopy (SEM) revealed that the epicuticular waxes occurred as a film densely crystallized as irregularly shaped platelets with spherical granules randomly distributed. These findings demonstrated that epicuticular waxes of broad bean leaves can mediate the foraging behavior of T. basalis females by absorbing contact kairomones of the host.