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排序方式: 共有382条查询结果,搜索用时 15 毫秒
31.
Davide Marano Gaetano Palumbo Salvatore Pennisi 《Analog Integrated Circuits and Signal Processing》2010,65(2):289-298
The present paper addresses a new compact low-power high-speed output buffer amplifier topology for large-size liquid crystal
display applications. The suggested buffer achieves fast driving performance, draws a low quiescent current during static
operation and offers a rail-to-rail common-mode input range. The circuit provides enhanced slewing capabilities with a limited
power consumption by simultaneously exploiting the push–pull output sections of two basic complementary-type input amplifiers
to realize a dual-path push–pull operation of the output stage. An auxiliary biasing network integrated in the input differential
stage allows the quiescent bias conditions of the class-AB output stage to be inherently controlled without additional current
dissipation. Post-layout simulation results confirm that the proposed amplifier can drive a 1-nF column line load within a
0.9-μs settling time under a 3-V full voltage swing, while drawing only 3.5-μA quiescent current. Monte Carlo simulations
are finally carried out, showing a good degree of robustness of the proposed output buffer against process and mismatch variations. 相似文献
32.
A method has been developed which can predict the backscatter properties of biological tissues from single amplitude spectra. Backscatter analysis from single spectra, based on the ratio of the Fourier transforms, is strongly influenced by the amplitude fluctuations, due to the inhomogeneous nature of biological tissues. The theoretical basis for the developed method is that the tissue produces an asymmetry in the reference amplitude spectrum related to the power law frequency dependence of the backscatter coefficient. Therefore, an estimation of the spectrum asymmetry has potential for estimating backscatter indexes. This method has been tested by using computer simulation and experimental measurements and it has shown a strong rejection to noise effects. 相似文献
33.
The degree of the Gaussian nature of the white noise present in microwave low-noise devices is experimentally investigated. The chosen experimental technique consists of simultaneously digitizing four versions of the noise which are amplified by four parallel independent amplifiers. The four independent signals are then used to compute the second, and, to a good approximation, the fourth moment of the noise. The ratio of the fourth moment to the square of the second moment is the kurtosis of the noise. Gaussian processes are characterized by a kurtosis equal to 3. A deviation from this value gives an indication about the degree of non-Gaussian nature of the noise. By using this technique, the effect of the additive noise introduced by the amplifiers is strongly reduced. In our experiments, the degree of the Gaussian nature of the white noise of some microwave devices is measured in the frequency range from 100 to 500 MHz. In all the investigated devices, the kurtosis is found to be very close to 3. 相似文献
34.
A Celardo G Dell'Elba S Manarini V Evangelista G de Gaetano C Cerletti 《Canadian Metallurgical Quarterly》1997,54(4):699-711
The kinetic profiles of leukotriene B4 (LTB4) and E4 (LTE4) after intravenous administration (30 nmol/kg) of the inflammatory peptide N-formyl-L-methionyl-L-leucyl-L-phenylalanine (FMLP) were evaluated in male rabbits. LTB4 and LTE4 reached the maximal concentration of 84.2 +/- 60.0 and 162.2 +/- 51.4 nmol/L (mean +/- s.d.), at 2 and 5 min, respectively. The first elimination phase for LTB4 and LTE4, after FMLP administration, showed an apparent half-life of 24.6 +/- 6.7 and 36.9 +/- 13.0 min, respectively. The area under the blood concentration-time curve (AUC, nmol min/L) of LTB4 and LTE4 was 2178 +/- 1591 and 7627 +/- 3052, respectively. LTE4 and N-ac-LTE4 were the major components excreted in the urine, mostly in the first time interval (0-12 h) of urinary collection after FMLP treatment; 11-trans-LTE4 was recovered in the second interval (12-24 h). Two other more polar compounds, potential metabolites, were recovered in the first interval of urine collection. Knowledge of the kinetic characteristics of endogenously produced leukotrienes may be useful in understanding the role of these eicosanoids in inflammatory and thrombotic disease, as well as in evaluating the efficacy of drugs designed to modulate their production and effect. 相似文献
35.
Marco Favaro Silvia Leonardi Carlos Valero‐Vidal Silvia Nappini Marianne Hanzlik Stefano Agnoli Julia Kunze‐Liebhuser Gaetano Granozzi 《Advanced Materials Interfaces》2015,2(5)
Anodic production of self‐organized titania nanotubes (TNTs) in an electrolyte enriched with graphene oxide quantum dots (GOQDs) is reported. The TNT‐GOQD composites grown under these conditions show in‐situ carbon doping, leading to the formation of anatase TiO2 domains and to the reduction to substoichiometric oxide (TiOx) and TiC. Surface science and electrochemical techniques are used in synergy to reveal that graphitic carbon is incorporated into TiO2 upon anodic nanotube growth promoting the formation of oxygen vacancies and thus TiO2 reduction. Upon annealing in ultrahigh vacuum, titanium oxycarbide (TiOxCy) is formed at temperatures ≥400 °C, where the material changes from a semiconductor to a semimetal. At the solid/liquid interface, the apparent electron donor density increases from as‐grown TNTs to as‐grown TNT‐GOQD composites due to the carbon doping, and the conductivity increases further with annealing temperature due to the increasing concentration of coordinatively unsaturated C atoms, crystallinity, and TiO2 reduction. The materials synthesized and characterized in this study find application in different areas ranging from visible light photocatalysis and photo‐electrochemistry to use as Li‐ion battery anodes and electrocatalyst supports, because it is possible to gradually tune the density of states below the Fermi level, which can be referred to as band‐gap engineering. 相似文献
36.
Annalisa Dalmoro Anna Angela Barba Marina Lamberti Mina Mazzeo Vincenzo Venditto Gaetano Lamberti 《Journal of Materials Science》2014,49(17):5986-5996
In this work, the degradation phenomena and the release kinetics of an active molecule from matrices systems made of random copolymers of ε-caprolactone (CL) and l-lactide (LA) were investigated by exposing the matrices, shaped as thin films, to simulated physiological environments. α-tocopherol was incorporated into the films as hydrophobic model molecule with the aim to investigate both its release pattern and its effect on erosion phenomena. In particular, the films have been kept at controlled conditions (temperature, stirring, pH) and they were characterized in terms of weight loss, water uptake, thermal properties, and change of number average molecular weight, in order to explain the molecule release kinetics and the degradation pathways of the copolymers. The main findings of this study are that the erosion phenomena take place significantly only when a critical value of the molecular mass was obtained in the sample; that the presence of the drug stabilizes the matrix and it decreases the rate of molecular mass decrease; and that crystallinity, reducing the chain mobility, causes lower erosion rates. 相似文献
37.
Fabio Nardone Gian Piero LignolaAndrea Prota Gaetano ManfrediAntonio Nanni 《Composite Structures》2011
An alternative to fiber reinforced polymer (FRP) materials adhesively bonded to the concrete substrate is the implementation of mechanically fastened FRP (MF-FRP) systems using steel anchors to secure the laminate to the substrate. The benefit of MF-FRP, compared to adhesive bonding for FRP flexural strengthening, is the speed of installation with unskilled labor, minimal or absent surface preparation under any meteorological condition and immediate use of the strengthened structures. Some of the potential shortcomings are: possible concrete damage during anchoring and limited opportunity of installation in the presence of congested internal reinforcement in the members to be strengthened. Laboratory testing and a number of field applications have shown the effectiveness of the MF-FRP method. In this paper, an analytical model is discussed for reinforced concrete (RC) members strengthened with MF-FRP strips. The model accounts for equilibrium, compatibility and constitutive relationships of the constituent materials; in particular, it accounts explicitly for the slip between the substrate surface and the FRP strip due to the behavior of the fasteners. The proposed flexural model, coupled with the computation algorithm, is able to predict the fundamentals of the behavior of RC flexural members strengthened with MF-FRP strips, in terms of both ultimate and serviceability limit states. Comparisons between the analytical predictions and the experimental results have been successfully performed. 相似文献
38.
Ermanno Barni Piero Savarino Gaetano di Modica Rosarina Carpignano Sisto Sergio Papa Giacomo Giraudo 《Dyes and Pigments》1984,5(1):15-36
Data on a series of 65 azo dyes derived from 4-alkylamido-2-hydroxybenzoic acids are reported. The dyes are suitable for application to polyamide fibres.Many correlations between the nature of substituents and the physical, spectroscopic or tinctorial properties of dyes were established. Correlations between structure and colour of dyed fabrics were also found. 相似文献
39.
Gaetano Chiodelli Aldo Magistris Marco Villa John L. Bjorkstam 《Materials Research Bulletin》1982,17(1):1-12
Compounds of the system (AgI)x(Ag2B4O7)1?x can be thought of as a network made by an equal number of BO3 and BO4 groups containing silver iodide polyhedra. Partially crystalline compounds are obtained when the AgI molar fraction, x, is more than two times the Ag2B4O7 fraction. For the same iodine concentration, the ionic conductivities of the AgI : Ag2B4O7 glasses are comparable with those of other AgI : Ag-oxysalt glasses. However, their glass transition temperatures are substantially higher. With increasing silver iodine content, the physical properties which have been investigated approach smoothly the corresponding values expected for α-AgI. However, it is shown that Ag+ within the iodide polyhedra is not the unique current carrier and that a wide distribution of barrier heights exists in these glasses. 相似文献
40.
The national diagnostic reference levels (NDRLs) form an efficient, concise and powerful standard for optimising radiation protection of a patient. However, in a large hospital, where many radiological departments are present, it is also possible to calculate and define lower dose values as local diagnostic reference levels (LDRLs). In our hospital there are eight radiological departments; in each of these, the entrance skin dose (ESD) distributions were determined for 10 standard projections (AP Abdomen, PA and LAT Chest, AP and LAT Lumbar Spine, LAT Lumbo-Sacral Joint, AP Pelvis, PA and LAT Skull and AP Urinary tract) and then the ESDs were compared with data previously published and with Italian NDRLs. All ESD values were below the corresponding NDRLs. The maximum/minimum ratio of ESDs ranged from 3.9 (LAT Skull) to 34.3 (AP Abdomen) for individual adult patients and from 2.1 (PA Skull) to 6.5 (Urinary tract) across the mean values of the radiological departments. Finally, it is shown how LDRLs can be proposed to obtain a more fully optimised radiation protection of patients. 相似文献