1,720,981 research outputs found
Study of naphthenic acid corrosion by neural network
No full textNaphthenic acid corrosion has been investigated since the 1950s, owing to its economic impact on refining operations. Although some significant advances in corrosion control, the best practice is still to blend or neutralise crude oil. Better understanding of the corrosion mechanism in the presence of naphthenic acids is necessary. This paper describes the preliminary evaluation of a neural network approach for rapid prediction of the naphthenic acid corrosion performance of carbon and stainless steels in a crude oil distillation unit
An investigation on corrosion protection layers in pipelines transporting hydrocarbons
Full text linkChemical reactions between carbon steel, water and chemical species produce corrosion layers
(scales) on the internal surface of pipelines transporting hydrocarbons. Scales act as a diffusion barrier and
prevent the progress of corrosion, a dangerous failure initiator. The protective film (10-100 m thickness) can
be removed locally by the action of the internal flow, or by other mechanisms. Adhesion with the substrate and
the failure modes of the corrosion layer can be tested by indentation. Some results are presented of experiments
performed on specimens with scales grown in a controlled environment
POSSIBLE EVIDENCE OF QUANTUM-SIZE EFFECTS IN X-RAY PHOTOEMISSION SPECTRA OF ULTRATHIN SI LAYERS
No full textThis letter reports the experimental evidence of a 2.3 eV blue shift of the plasmon loss lines observed in the x-ray photoelectron spectra of an ultrathin Si layer equivalent to 1.5 X 10(15) at./cm(2) deposited onto a randomly oriented Al2O3 Single crystal. The plasmon line shifts, which is roughly proportional to the deposited Si(mass)(-2/3), are attributed to quantum confinement effects in agreement with electron energy loss measurements performed on nanosized Si particles
Non-linear photoemission from W and Cu investigated by total-yield correlation measurements
No full textNonlinear photoelectric emission from Cu and W is investigated by subpicosecond laser pulses. Using a pump and probe technique, total-yield correlation measurements are obtained without space-charge saturation. The effects of the heating of the conduction electrons induced by the laser pulses are shown, considering the peak to background contrast ratio of the experimental correlation trace. The present analysis clarifies the consequences of a transient nonequilibrium temperature difference between electrons and the lattice on the correlation trace, confirming for W the presence of a thermally assisted photoemission mechanism
Multiphoton Electron-Emission from Cu and W - An Angle-Resolved Study
No full textThe experimental results of multiphoton electron emission from Cu and W induced by 2-eV 100-fs laser pulses with s and p polarizations at incidence angles between 0 degrees and 85 degrees and different intensities are reported. The data show a third-order nonlinear photoemission process for Cu and a fourth-order behavior for W. For both metals the electron emission is higher for the polarization in the incidence plane, with a maximum value at the pseudo-Brewster angle, while the electron yield as a function of the incidence angle exhibits an unambiguous dependence on the bulk absorption coefficient and it can be accounted for on the basis of the Fresnel equations
An innovative laboratory characterization: Hydrogen interaction with X60 pipeline steel
No full textCorrosion is evaluated to be one of the most important cause for pipeline failures. Given the serious consequences of these events in terms of human safety, environmental preservation and cost saving, it is evident that on-field corrosion control could have a fundamental role. The aim of the present work was to meet this need with preliminary feasibility study to develop a test procedure, characterized at the same time by non-invasive approach and scientific rigor, to evaluate the possibility of on-line monitoring and assess the integrity of a pipeline during its operation. The experimental campaign was performed on a HSLA Steel X60, characterized by a ferritic microstructure with fine grains and ultimate tensile strength equal to 520MPa. The hydrogen interaction with steel was investigated by means of an advanced equipment based on an innovative high sensitivity hydrogen gas sensor. The following types of investigations were carried out [1]: - Various permeation tests were performed with reference to EN ISO 17081:2014 increasing test temperature from 10°C to 60°C. - Afterwards a series of Hydrogen Induced Cracking nucleation tests was performed with reference to ASTM STP 692:0. - Finally, permeation concept was applied in an innovative way to Hydrogen Induced Cracking nucleation phenomena
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
- …
