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排序方式： 共有795条查询结果，搜索用时 15 毫秒
31.
Antonio Di Bartolomeo Aniello Pelella Xiaowei Liu Feng Miao Maurizio Passacantando Filippo Giubileo Alessandro Grillo Laura Iemmo Francesca Urban Shi‐Jun Liang 《Advanced functional materials》2019,29(29)
Few‐layer palladium diselenide (PdSe2) field effect transistors are studied under external stimuli such as electrical and optical fields, electron irradiation, and gas pressure. The ambipolar conduction and hysteresis are observed in the transfer curves of the as‐exfoliated and unprotected PdSe2 material. The ambipolar conduction and its hysteretic behavior in the air and pure nitrogen environments are tuned. The prevailing p‐type transport observed at atmospheric pressure is reversibly turned into a dominant n‐type conduction by reducing the pressure, which can simultaneously suppress the hysteresis. The pressure control can be exploited to symmetrize and stabilize the transfer characteristics of the device as required in high‐performance logic circuits. The transistors are affected by trap states with characteristic times in the order of minutes. The channel conductance, dramatically reduced by the electron irradiation during scanning electron microscope imaging, is restored after an annealing of several minutes at room temperature. The work paves the way toward the exploitation of PdSe2 in electronic devices by providing an experiment‐based and deep understanding of charge transport in PdSe2 transistors subjected to electrical stress and other external agents. 相似文献
32.
Filippo Biondi 《International journal of remote sensing》2019,40(13):5158-5178
Coherent change detection (CCD) use the sample degree of coherence as a measure of the temporal change collected between two complex-valued SAR images observed in the same area and using also the same geometry and polarization. The problem of classical CCD approaches shows a temporal change only when there are in areas of the image that have high clutter-to-noise power ratio. All experiments regarding the maximum-likelihood (ML) CCD, found to estimate useful information also in lower clutter-to-noise power ratio. Experiments used only electromagnetic transmissions in the same polarization. This work extends the formulation of the probability distribution function of the CCD in a multi-dimensional version useful for multi-polarization SAR data. Results of this ML-polarimetric interferometric SAR-CCD (ML-PolInSAR-CCD) show surprising recovery of both amplitude and phase CCD information. This information recovery is useful for improved interferometric SAR (InSAR), permanent scatterers interferometry (PS-InSAR) and SAR tomography applications. 相似文献
33.
Giulia Morettini Claudio Braccesi Filippo Cianetti 《Fatigue & Fracture of Engineering Materials & Structures》2019,42(4):827-837
In the literature there are many experimental results of multiaxial fatigue testing, usually generated by the combination of two or more cyclical loads. The cases in which samples are randomly stressed are rarer. Moreover, to generate particular stress states, the use of specific machinery for fatigue tests is usually required. For these reasons, the authors have created a particular geometry of specimens, which, when solicited by a single input of a random type, guarantees the creation of specific multiaxial stress states without using complex and costly instruments. The experimental tests were finally used for the validation of the multiaxial reduction method developed and currently utilized in the authors' design phase, though potentially used to verify all the other methodologies present in the literature. 相似文献
34.
Marcello Lepore Filippo Berto Angelo R. Maligno Joris Fellinger 《Fatigue & Fracture of Engineering Materials & Structures》2019,42(8):1711-1721
Simulation of the fatigue crack propagation in a Wendelstein 7‐X baffle module is performed in this study using both a finite element method‐based software and the UniGrow nonlinear model for small‐scale yielding (SSY) conditions. Some experimental fatigue tests of several cracked baffle modules have been performed through a servo‐hydraulic machine. One of these experimental tests has been considered to simulate fatigue crack propagation in the baffle module. Before starting the experimental test, a first crack partly contained in the welding seam and partly in the steel pipe is found. Subsequently, owing to the applied load, the crack propagated both into the welding seam and into the steel pipe until the plastic zone in the near field attains SSY conditions. Finally, owing to the increase in the extension of the plastic zone, SSY conditions are not more valid, and the breakage of the steel pipe is produced by plastic collapse. 相似文献
35.
Miguel Muiz‐Calvente Adrin lvarez‐Vzquez Sergio Cicero Jos A.F.O. Correia Abilio M.P. de Jesus Sergio Blasn Alfonso Fernndez‐Canteli Filippo Berto 《Fatigue & Fracture of Engineering Materials & Structures》2019,42(12):2663-2673
The fracture assessment of notched components based on cracked components approaches leads to over‐conservative failure predictions. In the research literature, several approaches are proposed to overcome this problem using an apparent fracture toughness, . Nevertheless, most of these approaches are based on deterministic assumptions despite the large and variable scatter exhibited by for different notch radii (ρ) or temperatures (T). This paper proposes a methodology for deriving a probabilistic field including the effect of temperature on the failure of notched components. First, the theory of critical distances is applied to transform each apparent fracture toughness into the equivalent fracture toughness for ρ = 0. Then, the temperature is supposed to act as a scale effect in the Weibull cumulative distribution function of the equivalent fracture toughness, and the corresponding scale effect function is derived. Finally, the applicability of the proposed methodology is illustrated by an example using two ferritic‐pearlitic steels: S275JR and S355J2. 相似文献
36.
Emanuela Schilir Raffaella Lo Nigro Fabrizio Roccaforte Ioannis Deretzis Antonino La Magna Angelo Armano Simonpietro Agnello Bela Pecz Ivan G. Ivanov Rositsa Yakimova Filippo Giannazzo 《Advanced Materials Interfaces》2019,6(10)
Atomic layer deposition (ALD) is the method of choice to obtain uniform insulating films on graphene for device applications. Owing to the lack of out‐of‐plane bonds in the sp2 lattice of graphene, nucleation of ALD layers is typically promoted by functionalization treatments or predeposition of a seed layer, which, in turn, can adversely affect graphene electrical properties. Hence, ALD of dielectrics on graphene without prefunctionalization and seed layers would be highly desirable. In this work, uniform Al2O3 films are obtained by seed‐layer‐free thermal ALD at 250 °C on highly homogeneous monolayer (1L) epitaxial graphene (EG) (>98% 1L coverage) grown on on‐axis 4H‐SiC(0001). The enhanced nucleation behavior on 1L graphene is not related to the SiC substrate, but it is peculiar of the EG/SiC interface. Ab initio calculations show an enhanced adsorption energy for water molecules on highly n‐type doped 1L graphene, indicating the high doping of EG induced by the underlying buffer layer as the origin of the excellent Al2O3 nucleation. Nanoscale current mapping by conductive atomic force microscopy shows excellent insulating properties of the Al2O3 thin films on 1L EG, with a breakdown field > 8 MV cm−1. These results will have important impact in graphene device technology. 相似文献
37.
Filippo Fratini Simone Mancini Barbara Turchi Daniele Sparagni Alaa Abd Al‐Gwad Basma Najar Luisa Pistelli Domenico Cerri Francesca Pedonese 《Flavour and Fragrance Journal》2019,34(5):339-348
Essential oils (EOs) are categorized as having antimicrobial, insecticidal, and antioxidant activities. For their antibacterial activity, EOs are widely studied as alternatives to antibiotics in human and veterinary medicines. The inhibitory and bactericidal activities of three EOs (Cinnamomum zeylanicum, Leptospermum scoparium, and Satureja montana) were determined against Listeria monocytogenes ATCC 7644. The chemical compositions of the EOs were determined through gas chromatography mass spectrometry (GC‐MS). Essential oils were tested alone or in binary and ternary combinations for both their inhibitory and their bactericidal activities. Binary and ternary mixtures were tested through a chequerboard assay, and thus fractional inhibitory and fractional bactericidal concentration indices were obtained in relation to the activity of each EO alone. The chemical composition of each EO had different percentages of the main classes of compounds. EOs showed high levels of monoterpenes (hydrocarbons and oxygenated), sesquiterpenes (hydrocarbons and oxygenated), and phenylpropanoids for winter savory, manuka, and cinnamon, respectively. Several synergistic activities against Listeria monocytogenes were demonstrated in binary and ternary mixtures of the EOs. Mixtures of the EOs tested showed potential for use as antibacterial products; moreover, because of the synergistic activities the mixtures could be used in lower quantities than individual EOs on their own. 相似文献
38.
Kihong Lee Sebastian F. Maehrlein Xinjue Zhong Daniele Meggiolaro Jake C. Russell Douglas A. Reed Bonnie Choi Filippo De Angelis Xavier Roy Xiaoyang Zhu 《Advanced materials (Deerfield Beach, Fla.)》2019,31(36)
The coupling of phonons to electrons and other phonons plays a defining role in material properties, such as charge and energy transport, light emission, and superconductivity. In atomic solids, phonons are delocalized over the 3D lattice, in contrast to molecular solids where localized vibrations dominate. Here, a hierarchical semiconductor that expands the phonon space by combining localized 0D modes with delocalized 2D and 3D modes is described. This material consists of superatomic building blocks (Re6Se8) covalently linked into 2D sheets that are stacked into a layered van der Waals lattice. Using transient reflectance spectroscopy, three types of coherent phonons are identified: localized 0D breathing modes of isolated superatom, 2D synchronized twisting of superatoms in layers, and 3D acoustic interlayer deformation. These phonons are coupled to the electronic degrees of freedom to varying extents. The presence of local phonon modes in an extended crystal opens the door to controlling material properties from hierarchical phonon engineering. 相似文献
39.
Fabio Calefato Filippo Lanubile Tayana Conte Rafael Prikladnicki 《Empirical Software Engineering》2016,21(3):1002-1034
Communication in global software development is hindered by language differences in countries with a lack of English speaking professionals. Machine translation is a technology that uses software to translate from one natural language to another. The progress of machine translation systems has been steady in the last decade. As for now, machine translation technology is particularly appealing because it might be used, in the form of cross-language chat services, in countries that are entering into global software projects. However, despite the recent progress of the technology, we still lack a thorough understanding of how real-time machine translation affects communication. In this paper, we present a set of empirical studies with the goal of assessing to what extent real-time machine translation can be used in distributed, multilingual requirements meetings instead of English. Results suggest that, despite far from 100 % accurate, real-time machine translation is not disruptive of the conversation flow and, therefore, is accepted with favor by participants. However, stronger effects can be expected to emerge when language barriers are more critical. Our findings add to the evidence about the recent advances of machine translation technology and provide some guidance to global software engineering practitioners in regarding the losses and gains of using English as a lingua franca in multilingual group communication, as in the case of computer-mediated requirements meetings. 相似文献
40.
Tiziana Siciliano Marco TeporeAlessandra Genga Gioacchino MicocciAntonio Tepore Emanuela Filippo 《Materials Chemistry and Physics》2012
In this paper, we report the obtention of In2O3 nanostructured microwires by the decomposition thermal treatment of InSe single crystal in two-steps under an oxygen–ammonia flow without the presence of any catalyst. Long In2O3 microwires with uniform shape and homogeneous surface were first synthesized through thermal treatment of InSe single crystal at temperature of about 640 °C; then, furnace temperature was increased to 750 °C and, as annealing time proceeded, the obtained microwires served as substrates on which nanorod branches grew. The shape and the structure of the microarchitectures were characterized by means scanning electron microscopy, transmission electron microscopy, selected area diffraction pattern, X-Ray diffraction and Raman spectroscopy. Our results indicated that In2O3 primary wires with a clean surface grew in the [100] direction and that the secondary protuberances grew in the [011] direction. A possible growth mechanism of the hierarchical microwires was also proposed. 相似文献