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[en] Breakdown characteristics of a gap breakdown load was investigated in this paper, and a reversely switched dynistor (RSD) discharge circuit was designed based on the load. Based on the characteristics of the load, the RSD discharge circuit was improved and optimized. The volume of the magnetic switch was reduced. To protect the thyristor and RSD, a diode was anti-parallely connected with the thyristor, which reduced the time requirement when a power voltage was applied to RSD. Experimental results show the circuit designed in this paper can switch a high voltage and high current smoothly, and allows the power voltage to change in a wider range.
[en] The study of the electrochemical behavior of wrought and welded Alloy 22 was carried out in 5 M CaCl2 between 45 and 120 C with Multiple Crevice Assembly (MCA) specimens. The susceptibility to corrosion was found to increase with increase in temperature in both the wrought and the welded forms of the alloy. The weld metal was found to be less susceptible to localized corrosion under the conditions tested
[en] A number of recent papers describing a model of breakdown and high gradient limits should be directly applicable to all rf and DC applications. Although based on low frequency rf measurements, the model can explain and reproduce the effects of a wide range of variables, (B fields, gas pressure, materials, breakdown rate dependence on electric fields, frequency and pulse length, etc.), and also some superconducting rf behavior. Highlights of this program include: the highest accelerating gradients ever recorded, new models of breakdown and high gradient operation that seem to explain all high gradient behavior, and new technology for surface measurement and control.
[en] Faulted bipolar transistors in a voltage source transistor inverter are protected against shootthrough fault current, from the filter capacitor of the d-c voltage source which drives the inverter over the d-c bus, by interposing a small choke in series with the filter capacitor to limit the rate of rise of that fault current while at the same time causing the d-c bus voltage to instantly drop to essentially zero volts at the beginning of a shootthrough fault. In this way, the load lines of the faulted transistors are effectively shaped so that they do not enter the second breakdown area, thereby preventing second breakdown destruction of the transistors
[en] Experimental and computational analyses of jet formation at the boundary of a decaying pulse discharge in an ambient quiescent air at 1 atm are presented. High velocity jets are observed attributed to the channel curvature set during the initial breakdown phase. The general convex-to-concave jet direction is explained, and the mechanisms of jets formation are discussed.
[en] This paper proposes a new shallow trench and planar gate MOSFET (TPMOS) structure based on VDMOS technology, in which the shallow trench is located at the center of the n- drift region between the cells under a planar polysilicon gate. Compared with the conventional VDMOS, the proposed TPMOS device not only improves obviously the trade-off relation between on-resistance and breakdown voltage, and reduces the dependence of on-resistance and breakdown voltage on gate length, but also the manufacture process is compatible with that of the VDMOS without a shallow trench, thus the proposed TPMOS can offer more freedom in device design and fabrication. (semiconductor devices)
[en] Complete text of publication follows. Wheat grain is a complex structure made of the germ and starchy endosperm surrounded by several peripheral tissues differing in their structure and chemical compositions. In traditional wheat milling processes, this part of the grain is discarded as the bran, mostly used in animal feed. Bran could be however used for food ingredient preparation if it is fractionated to remove unwanted parts and increase bioactive compounds accessibility. Wheat outer layers mechanical properties are key properties to explain differences observed for bran fractionation. Up to now, these properties are deduced by tensile tests of hand-isolated tissues after wheat humidification, a procedure that could induce artefacts. Pulsed laser ablation have demonstrated a potential technique to reveal wheat tissue properties (Martelli et al., J Cereal Sci, in press.). Ablation rate was deduced from microscopic observations which are time consuming. Taking advantage of compositional heterogeneity within the peripheral tissues, laser-induced breakdown spectroscopy (LIBS) could be a powerful tool to follow wheat tissue ablation. With this aim, native grains of a soft common wheat (Crousty) were gradually ablated with a pulsed excimer laser ArF (193 nm, 15 ns, 1 Hz, 2 J · cm-2) coupled to a miniature optical fibre spectrometer. Spectra were acquired from each pulse. Chemometrics were successfully applied to exploit the complex LIBS spectral data. The bran tissues (pericarp, seed coat, aleurone layer) and the endosperm were successfully predicted by a partial least square discriminant analysis (PLS-DA) model. These results were validated by microscopic observations Tissue hardness was deduced from the ablation rate but also directly from LIBS spectra, by exploring the ionic to atomic magnesium line ratio (Mg II 279.55 nm/Mg I 285.22 nm). Tissue ablation rate were indirectly related to Mg II/Mg I, suggesting the LIBS potential to estimate tissue hardness. Even though, the Mg II/Mg I ratio needs to be compared to other values of tissue properties, like the rupture energy given by tensile tests. The LIBS simplicity and easiness could introduce laser ablation as a technique to investigate physico-chemical bases of wheat tissues fractionation. The authors kindly acknowledge the financial support from the European Commission in the Communities 6th Framework Programme, Project HEALTHGRAIN (FP6-514008).