1,721,028 research outputs found
Large-bandwidth reflection fiber-optic sensors for turbomachinery rotor blade diagnostics
No full textIt is possible to measure rotating blade vibrations in a turbomachine by stationary sensors mounted on the casing. Optical sensors appear best suited for these measurements. A prototype fiber-optic sensor is proposed, its scheme is described and its performance presented. The design choices are discussed with respect to the desired performance; general conclusions about the use of optical sensors for such measurements are drawn
Soft-sensing reconstruction of in-depth defect geometry from active IR-thermography data
Full text linkThis paper proposes a new approach for processing measured data from active Infra Red (IR) thermography, where a soft sensing algorithm is exploited for in depth defect reconstruction. This is achieved by propagating the information gathered at the wall surface to the inner layers. Correlating the experimental 2D measurements to a Finite Element (FE) model of the tested specimen it is possible to update the model with the measured data and change the geometry of the simulated inner defect, until the surface temperature distribution calculated corresponds to the measured one. Following that strategy, the unknown defect geometry can be determined. The method developed and presented in this paper consists of an optimization problem based on the minimization of the difference between the surface temperature distribution measured on the sample subjected to an active thermography test and the one resulting from the FE model. The optimization variables are the geometrical parameters (depth, width, thickness and position) characterizing the defect which will be fully determined at the complete convergence, within a given tolerance, of the optimization problem. The method includes also a preprocessing algorithm, based on the same experimental data and FE model, which allows to determine thermal and mechanical properties of the object under test, like surface emissivity, heat capacity and material conductivity and density, which are often unknown especially in the case of works of art. This soft-sensing procedure has been applied to a virtual experiment to estimate the accuracy of the reconstructed geometry and to a simulacrum of ancient fresco including defects realized on purpose
Innovative data regression incorporating deterministic knowledge for soft sensing in the process industry
No full textSoft sensing is a monitoring technique for the indirect assessment of a target variable by means of direct measurements of others and the application of data mining on the historical log, as well as simplified models of the system. Due to technical and economic advantages respect to hardware sensing, soft sensing has been increasingly used in many scenarios, in particular within the process industry. Despite the literature being wide regarding the application of conventional regression techniques on data provided by the monitoring hardware, a systematic approach for supporting and improving data regression through the deterministic knowledge of the process is still missing. This contribution presents an innovative regression method based on first principle modeling. The method is introduced and tested under the case scenario of conventional clinker making process, for predicting the instantaneous fraction of the unburned calcium oxide. A second test case involves an innovative clinkering stage based on microwaves application
Design and experimental characterization of a non intrusive measurement system of rotating blade vibration
No full text: A measurement system for non-intrusive monitoring of rotating blade vibration in turbomachines based on fiber optic sensors is presented. The design of the whole system is discussed; the development of special purpose sensors, their interfacing to the data acquisition system and the signal processing are outlined. The processing algorithms are tested by software simulation for several possible blade vibrations. Experimental tests performed on different bladed simultaneous strain gauge measurements
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
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