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21.
Burgnies L. Velu G. Houzet G. Blary K. Carru J.-C. Lippens D. 《IEEE transactions on instrumentation and measurement》2008,57(6):1127-1132
We report on a de-embedding technique for measuring the reflection coefficients of comblike capacitors patterned on barium-strontium-titanate (BST) ferroelectric films. The technique is derived from the thru-reflect-line calibration technique and is combined with conformal mapping to retrieve the complex permittivity of BST thin films. The accuracy of the method is demonstrated over a broad frequency for 0.3-mum-thick BaxSr1-xTiO3, with x = 0.5, in a paraelectric state, grown by a sol-gel technique. The samples are characterized up to 35 GHz and exhibit a constant permittivity of 245 plusmn 12%, which is in good agreement with the values deduced from propagation wave constants of BST transmission lines. 相似文献
22.
Vuillaume D. Marchetaux J.-C. Lippens P.-E. Bravaix A. Boudou A. 《Electron Devices, IEEE Transactions on》1993,40(4):773-781
The creation of defects by hot-carrier effect in submicrometer (0.85-μm) LDD n-MOSFETs is analyzed by the floating-gate and the charge-pumping techniques. It is emphasized that the floating-gate technique is an attractive tool for characterizing the oxide traps located in the drain-gate overlap region, near the oxide spacer of the LDD structures. This work gives new insight into the creation of acceptorlike oxide traps which are electrically active only after electron injection phases. These defects are generated in the whole stress gate bias range (from V d/8 to V d) by hot-hole and/or hot-electron injections, and their generation rates (10-9 and 10-2 for electron and hole injections, respectively) are one decade greater than for the interface state generation. Two-dimensional simulations show that they are mainly responsible for the I d-V g degradation of the LDD MOSFETs, and that the trap concentrations deduced from charge-pumping experiments are consistent with the I d-V g degradation 相似文献
23.
In oxidative ammoniacal leaching of some copper sulfides, the dissolution of copper is slowed down by the precipitation of an oxidized phase which is identified as a hydrated tenorite.A simple set of mass balance equations permits determination of the stability limits of the copper ions in ammoniacal solutions with or without acidic ammonium salts. 相似文献
24.
J-C. Bauwens 《Polymer》1980,21(6):699-705
Both the formation of free volume and the elementary motion characterizing the plastic deformation in the glassy state are described here by the same molecular process, consisting of the transition of a given number of chain segments from fundamental to activated states. Using this basic assumption, a model is proposed which makes use of classical laws of thermodynamics. Five parameters need to be adjusted to take into account the thermodynamic properties related to the free volume: one more is necessary to characterize the molecular process of plastic deformation. The pressure dependence of Tg and the difference between the specific volumes found in the glassy state from isothermal and isobaric measurements can be calculated from the model. Fairly good agreement is found between the theoretical and experimental values of these quantities. The physical meaning of constants belonging to a previously-proposed yield criterion is clarified, and these constants are given as a function of the molecular process. Moreover, the treatment confirms that the glass transition temperature is related to a constant fraction of activated segments and not to a constant value of the free volume. 相似文献
25.
Ogier JC Casalta E Farrokh C Saïhi A 《International journal of food microbiology》2008,126(3):286-290
Although Leuconostoc genus is "generally recognized as safe" (GRAS), a few clinically human infections cases by this microorganism have been reported in the literature, leading to their classification as opportunistic pathogens. However, these reported cases concern only severe immunodepressed patients, and none direct relations have yet been proven between Leuconostoc isolation and human diseases. Moreover, no cases of infections have been directly linked to the consumption of fermented food. Considering the long history of use of Leuconostoc in dairy industry, and their poor incidence in human infections cases, this bacterial genus may be reasonably considered as " safe " for its use in fermented dairy products. 相似文献
26.
Lourtioz J.M. de Lustrac A. Gadot F. Rowson S. Chelnokov A. Brillat T. Ammouche A. Danglot J. Vanbesien O. Lippens D. 《Lightwave Technology, Journal of》1999,17(11):2025-2031
In this paper, we present several experimental and theoretical studies showing the feasibility of active photonic crystal controlled either by electrical elements or by light. The controllability of photonic crystals at centimeter wavelengths is proposed with the periodic insertion of diodes along the wires of a two-dimensional (2-D) metallic structure. For only three crystal periods with commercially available devices, more than 30 dB variations of the crystal transmission are predicted over a multigigahertz range by switching the diodes. From calculation models, a tight analogy is shown between these crystals and those consisting of discontinuous metallic rods with dielectric inserts. The numerical models as well as the proposed technology are validated by experimental measurements on 2-D crystals with either continuous or discontinuous metallic rods. The partial control of a 3-D layer-by-layer dielectric structure at millimeter wavelengths is also demonstrated in the second part of the work. A laser light is used to modulate the transmission level of defect modes by photo-induced free carrier absorption. The overall results are expected to contribute to further developments of switchable electromagnetic windows as well as to tunable waveguide structures in the microwave and millimeter wave domains 相似文献
27.
We used an optimized photonic crystal based flat lens for target detection and image reconstruction of micrometer sized objects for an operating wavelength of 1.55 μm. Using numerical retrieval procedures inspired from tomography, the ability to detect subwavelength sized targets and to image metallic objects of complex shapes is shown. The relation between the reconstructed image quality and lens resolution is investigated. 相似文献
28.
29.
Impact of colloidal and soluble organic material on membrane performance in membrane bioreactors for municipal wastewater treatment 总被引:7,自引:0,他引:7
Rosenberger S Laabs C Lesjean B Gnirss R Amy G Jekel M Schrotter JC 《Water research》2006,40(4):710-720
Two parallel membrane bioreactors (2 m3 each) were operated over a period of 2 years. Both pilots were optimised for nitrification, denitrification, and enhanced biological phosphorous elimination, treating identical municipal wastewater under comparable operating conditions. The only constructional difference between the pilots was the position of the denitrification zone (pre-denitrification in pilot 1 and post-denitrification in pilot 2). Despite identical modules and conditions, the two MBRs showed different permeabilities and fouling rates. The differences were not related to the denitrification scheme. In order to find an explanation for the different membrane performances, a one-year investigation was initiated and the membrane performance as well as the operating regime and characteristics of the activated sludge were closely studied. MLSS concentrations, solid retention time, loading rates, and filtration flux were found not to be responsible for the different performance of the submerged modules. These parameters were kept identical in the two pilot plants. Instead, the non-settable fraction of the sludges (soluble and colloidal material, i.e. polysaccharides, proteins and organic colloids) was found to impact fouling and to cause the difference in membrane performance between the two MBR. This fraction was analysed by spectrophotometric and size exclusion chromatography (SEC) methods. In a second step, the origin of these substances was investigated. The results point to microbiologically produced substances such as extracellular polymeric substances (EPS) or soluble microbial products (SMP). 相似文献
30.