Characterization of a Closed-Loop Controlled Current-Fed Reluctance Machine Taking into Account Saturation

A current-fed inverter-reluctance motor drive controlled in a closed-loop is described. A method of characterization is presented which takes the saturation into account in direct and quadrature axes. An experimental method is described which is able to determine direct and quadrature inductances with influence of the magnetomotive force (MMF) in one axis upon the flux in the other axis. The model is then used for the investigation of the electromechanical characteristics of the converter-machine system. Calculated results are compared with experimental results.     

Local modal reduction in explicit dynamics with domain decomposition. Part 1: extension to subdomains undergoing finite rigid rotations

We present an extension of the dual Schur multidomain method with local linear modal reduction previously introduced by Gravouil, Combescure, Herry and Faucher to the case of modal reduction on geometrically non‐linear vibrating subdomains. This first part of a two‐part paper describes a new formalism, based on an original set of parameters, to represent a subdomain's finite rigid‐body motion. Special attention is paid to the stability issues with time integration using the central difference scheme. The method is validated on an academic example and its efficiency is demonstrated on a large‐scale example. Copyright © 2004 John Wiley & Sons, Ltd.     

Low‐volatility acetals to upgrade the performance of melamine–urea–formaldehyde wood adhesive resins

1,1,2,2‐Tetramethoxyethane (TME), a high boiling point acetal derived from glyoxol, lhas been shown to upgrade the performance of melamine‐urea‐formaldehyde (MUF) and some UF resins used for wood adhesives. This affords the possibility of decreasing the percentage of resin used in the preparation of wood panels without volatilizing the TME acetal used.     

Electron beam nanolithography in AZnLOF 2020

We present a lithography process using electron beam lithography with an optical resist AZnLOF 2020 for pattern transfer. High-resolution 100 keV electron beam lithography in 400 nm layers of negative resist AZnLOF 2020 diluted 10:4 with PMGEA is realized. After the electron beam lithography process, the resist is used as a mask for reactive ion etching. We performed the transfer of patterns by RIE etching of the substrate allowing a final resolution of 100 nm. We demonstrate the patterning in an insulating layer, thus simplifying the fabrication process of various multilayer devices; proximity correction has been applied to improve pattern quality and also to obtain lines width according to their spacing. This negative resist is removed by wet etching or dry etching, could allow combining pattern for smallest size down to 100 nm by EBL techniques and for larger sizes by traditional lithography using photomask.     

Notorious discrepancies in crystal field analyses eliminated by configuration interaction

Some conspicuous discrepancies between experimental and calculated energy levels in the crystal field analysis of rare earth (4f²) or actinide (5f²) electronic spectra are eliminated if one includes in the interaction matrix the participation of the 4f¹6p¹ (or 5f¹7p¹) excited configuration in addition to the ground configuration. This was recently demonstrated in the case of the tetravalent uranium U⁴⁺ in the cubic centrosymmetric sites of elpasolithe compounds (M.D. Faucher, O.K. Moune, D. Garcia and P. Tanner, Phys. Rev. B, 53 (1996) 9501). The present work is a step towards the generalization of the proposition. It is shown that it is also true for the 4f³ configuration of Nd³⁺ in non-centrosymmetric sites. Indeed, the notorious discrepancy between experimental and calculated sublevels of the ²H(2)_11/2 group at 15000 cm⁻¹ is eliminated by configuration interaction with the excited 4f²6p¹ configuration. The experimental case of Nd₂O₂S is quoted as an example, but the demonstration is valid for all neodymium compounds.     

Using the multilevel imbricated cells topologies in the design of low-power power-factor-corrector converters

Power-factor-corrector (PFC) converters are now commonly used in low-power supply systems connected to AC networks. In addition to their basic PFC properties, they constitute the best technical solution to directly obtain the compatibility with a large range of AC voltages provided by different distribution networks around the world (typically, from 85 to 265 V rms). It is the main application of these converters. This function is achieved with an additional cost and volume, and this extra price to pay needs to be minimized. In this context, we first recall the main approaches of the design of conventional PFCs based on the boost converter topology. We emphasize the different critical points of the sizing that mainly concern the input choke and the silicon devices, in regard with the choice of the switching frequency. Few ways of improvement are then presented for these conventional PFCs. In a second part, always in the context of a large input voltage range, we consider the possibility to introduce the multi-level concept to reduce the input choke and filters. A solution using a multi-level flying capacitor two-cell converter is presented. It is shown that it can lead to a significant increase of the performances, with several options of sizing which can be suited to different requirements of the applications.     

Comparisons of Contact Chemoreception and Food Acceptance by Larvae of Polyphagous Helicoverpa armigera and Oligophagous Bombyx mori

We compared food choice and the initial response to deterrent treated diet between fifth instars of Helicoverpa armigera, a polyphagous generalist pest, and Bombyx mori, an oligophagous specialist beneficial. Bombyx mori was more behaviorally sensitive to salicin than to caffeine. The relative sensitivities were reversed for H. armigera, which was tolerant to the highest levels of salicin found in natural sources but sensitive to caffeine. A single gustatory receptor neuron (GRN) in the medial styloconic sensillum of B. mori was highly sensitive to salicin and caffeine. The styloconic sensilla of H. armigera did not respond consistently to either of the bitter compounds. Phagostimulants also were tested. Myo-inositol and sucrose were detected specifically by two GRNs located in B. mori lateral styloconic sensillum, whereas, in H. armigera, sucrose was sensed by a GRN in the lateral sensillum, and myo-inositol by a GRN in the medial sensillum. Myo-inositol responsiveness in both species occurred at or below 10^?3 mM, which is far below the naturally occurring concentration of 1 mM in plants. Larval responses to specific plant secondary compounds appear to have complex determinants that may include host range, metabolic capacity, and gustatory repertoire.