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11.
D. Fortunato 《Annali di Matematica Pura ed Applicata》1979,119(1):317-331
Summary Let A=
be an elliptic differential operator inR
u, If, for |α|=l, the coefficients aα are ? nearly constant ? and, for |α|<l, they tend to zero at infinity with a certain swiftness, it is proved that A is a
Fredholm operator with indexx(A)=0 between a suitable weighted Sobolev space M contained in Wl,p (R n) and Lp(R
n, (1+|x|)lp)==
. It is shown, by counterexamples, that the above result, holds only if n>l, p>n/(n−l) and that isomorphism results can be
obtained, in general only if the coefficients aα(|α|<l) are assumed to be ? sufficiently small ? also on compact sets. Then a Sturm-Liouville type problem is studied and
a class of negative and falling off at infinity potentials V(x) is constructed in such a way that the Schr?dinger operator
H=−Δ+V(x), in L2(R
n), has a zero eigenvalue.
Entrata in Redazione il 10 agosto 1977.
Work supported by C.N.R. (G.N.A.F.A.). 相似文献
Sunto Sia un operatore differenziale ellittico inR n. Se, per |α|=l, i coefficienti aα sono ? quasi costanti ? e, per |α|<l, tendono a zero all'infinito con una certa rapidità, si dimostra che A è un operatore di Fredholm con indiceX(A)=0 tra un opportuno spazio di Sobolev con peso M contenuto in Wl,p(R n) ed Lp(R n, (1+|x|)lp)== . Si prova, mediante controesempi, che tale risultato è valido solo se n>l, p>n/(n−l) e che teoremi di isomorfismo si possono ottenere, in generale, solo se si assume che i coefficienti aα (|α|<l) sono ? sufficientemente piccoli ? anche su insiemi compatti. Si studia quindi un problema del tipo Sturm-Liouville e si costruisce una classe di potenziali V(x) negativi e convergenti a zero all'infinito, tali che l'operatore di Schr?dinger H=−δ+V(x) in L2(R n) abbia un autovalore nullo.
Entrata in Redazione il 10 agosto 1977.
Work supported by C.N.R. (G.N.A.F.A.). 相似文献
12.
Alexsandro J. dos Santos Matheus S. Kronka Guilherme V. Fortunato Marcos R.V. Lanza 《Current Opinion in Electrochemistry》2021
This short review presents a critical overview of the most recent works published in the literature related to the use of electrochemical advanced oxidation processes (EAOPs) for the treatment of antibiotics present in synthetic and real wastewaters. The first section focuses on novelties within the traditional EAOPs, including electrochemical oxidation and electrochemical Fenton-based processes. The second section is devoted to new electrochemical technologies, including heterogeneous electro-Fenton, electrochemically activated persulfate processes, and combined processes. Future perspectives about these processes are also presented to aid the continuous evolution of research in the area. 相似文献
13.
Concatenated coding provides a general strategy to achieve the desired level of noise protection in quantum information processing. We report the implementation of a concatenated quantum error-correcting code able to correct phase errors with a strong correlated component. The experiment was performed using liquid-state nuclear magnetic resonance techniques on a four spin subsystem of labeled crotonic acid. Our results show that concatenation between active and passive quantum error correction is a practical tool to handle realistic noise involving both independent and correlated errors. 相似文献
14.
Giuseppe Curr Marco Camalleri Denise Calì Francesca Monforte Fortunato Neri 《Microelectronics Reliability》2007,47(4-5):798
A detailed study of the carrier trapping properties shown by the silicon/oxynitride/oxide gate layers in PowerVDMOS technologies is reported. A quantitative analysis of hole and electron trap densities versus the specific N2O based nitridation process, extracted from Fowler–Nordheim constant current stress kinetics, allows a deep understanding of the role played by those defects in the susceptibility of every nitrided layer. 相似文献
15.
Laser welding of non-ferrous alloys is a high-productivity and cost-effective joining technology, which gained an undoubted interest especially in aerospace, chemical and medical industry, where high strength and corrosion resistant mechanical parts are required. Unfortunately some of the most used non-ferrous alloys are highly reactive with respect to the components of the environmental atmosphere: oxygen, nitrogen, hydrogen and humidity. This reactivity leads to the formation of porosities and to oxides and nitrides inclusion, which are responsible for a decrease of ductility and strength in welded joints.According to this a good shielding technique of the weld pool is of primary importance in order to obtain sound beads and reliable manufacturings. This paper deals with the opportunity of simulating the shielding gas behavior by means of Computational Fluid Dynamics software in order to understand the relationship among the outlet position, the shielding gas type and its flow rate.A simulation activity was carried out in order to evaluate the behavior of shielding gas concentration surrounding the weld pool. The simulated welding environment was simplified without considering the presence and the effect of the plasma plume. The main results concern the shielding gas contamination prediction with respect to the distance from the beam-material interaction zone. 相似文献
16.
Polysilicon TFT structures for kink-effect suppression 总被引:1,自引:0,他引:1
Mariucci L. Fortunato G. Bonfiglietti A. Cuscuna M. Pecora A. Valletta A. 《Electron Devices, IEEE Transactions on》2004,51(7):1135-1142
Experimental results and numerical simulations of asymmetric fingered polysilicon thin-film transistors (AF-TFTs) are analyzed in detail. In the AF-TFTs, the transistor channel region is split into two zones with different lengths separated by a floating n/sup +/ region. This structure allows an effective reduction of the kink effect depending on the relative length of the two subchannels, without introducing any additional series resistance. In addition, an appreciable reduction of the leakage current is also observed. The AF-TFTs characteristics have been analyzed by two-dimensional numerical simulation and by modeling the device with two transistors in series. This model clarifies the mechanisms of kink effect suppression in AF-TFT. On the basis of this analysis, two new modified device structures for kink-effect suppression are also proposed and discussed. 相似文献
17.
Today there is a strong interest in the scientific and industrial community concerning the use of biopolymers for electronic applications, driven mainly by low‐cost and disposable applications. Adding to this interest, we must recognise the importance of the dream of wireless auto‐sustained and low‐energy‐consumption electronics. This dream can be fulfilled by cellulose paper, the lightest and the cheapest known substrate material, as well as the Earth's major biopolymer and of tremendous global economic importance. Most of the paper used up to now is optimised in terms of the required mechanical and physical properties to be used as the support of inks of different origins. In the future, specific electronic heterogeneous paper sheets should be fabricated aiming to get paper fibers with required bulk and surface functionalities, proper water/vapour barrier, size and diameter/thickness of the fibrils and full paper thickness. This will be the function of components/devices to be incorporated/integrated such as thin‐film transistors, complementary metal oxide semiconductor devices, passive electronic components (resistances, inductors and capacitors), memory transistors, electrochromics and thin‐film paper batteries. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
18.
Paula C. Barbosa Luísa C. Rodrigues Maria Manuela Silva Michael J. Smith Prudência B. Valente Alexandra Gonçalves Elvira Fortunato 《先进技术聚合物》2011,22(12):1753-1759
Solid polymer electrolyte (SPE) systems based on interpenetrating blends of poly(ethylene oxide‐co‐propylene oxide) and poly(methyl methacrylate) host matrices, with lithium perchlorate as guest salt, were prepared. These electrolytes were presented as free‐standing films, and their thermal and electrochemical properties were characterized by conductivity and electrochemical stability measurements. The properties of the interpenetrating blends of poly(ethylene oxide‐co‐propylene oxide) and poly(methyl methacrylate) host matrices as the electrolyte component of a solid‐state electrochromic device are reported and the results obtained suggest that this electrolyte provides an encouraging performance in this application. The most conducting electrolyte composition of this SPE system is the formulation designated as SPE2‐0PC (5.01 × 10?4 S cm?1 at about 57°C). The lowest decomposition temperature was registered with the SPE6‐15PC composition (233°C). The average transmittance in the visible region of the spectrum was above 41% for all the samples analyzed. After coloration the device assembled with 71 wt% PC presented an average transmittance of 15.71% and an optical density at 550 nm of 0.61. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
19.
Giuseppe Curr Marco Camalleri Denise Calì Francesca Monforte Fortunato Neri 《Microelectronics Reliability》2007,47(4-5):819
A detailed study of the interface state properties shown by the silicon/oxynitride/oxide gate layers used in Vertically Diffused PowerMOSFET (PowerVDMOS) technologies is reported. A quantitative analysis of interface states versus the specific N2O based nitridation process, extracted from current–voltage characteristics in depletion regime, provided a clear trend and turns to be of great importance for reliability performances of the final device. 相似文献
20.
A most debated topic of the last years is whether simple statistical physics models can explain collective features of social dynamics. A necessary step in this line of endeavor is to find regularities in data referring to large-scale social phenomena, such as scaling and universality. We show that, in proportional elections, the distribution of the number of votes received by candidates is a universal scaling function, identical in different countries and years. This finding reveals the existence in the voting process of a general microscopic dynamics that does not depend on the historical, political, and/or economical context where voters operate. A simple dynamical model for the behavior of voters, similar to a branching process, reproduces the universal distribution. 相似文献