1,721,109 research outputs found
Chemical Looping Reforming-Decomposition of Methane with CO2 Utilization in a core-shell type oxygen carrier of NiO-Fe2O3/La0.8Sr0.2FeO3
No full textThe embedment of fiber Bragg grating sensors into filament wound pressure tanks considering multiplexing
Get PDFFilament wound pressure tanks are under high internal pressure during the operation and it has the complexity in damage mechanism and failure modes. For this reason, it is necessary to monitor the tank through its operation as well as during the whole fabrication process. A large number of sensors must be embedded into multiple positions of the tank from its fabrication step for monitoring the whole tank. Fiber optic sensors, especially fiber Bragg grating (FBG) sensors are widely used for various applications because of good multiplexing capabilities. However, we need to develop the embedding technique of FBG sensors into harsh inner environment of the tank for the successful embedment. In this paper, we studied the embedding technique of a number of FBG sensors into filament wound pressure tanks considering multiplexing and conducted in situ structural health monitoring of filament wound pressure tanks during water-pressurizing test using embedded FBG sensor arrays. From the experimental results, it was demonstrated that FBG sensors can be successfully adapted to filament wound pressure tanks for their structural health monitoring by embedding
Design Requirements of Embedded Fiber Bragg Grating Sensors for the Monitoring of Composite Pressure Vessels
No full textSimultaneous monitoring of strain and temperature during and after cure of unsymmetric composite laminate using fibre-optic sensors
No full textIn this paper, we present a simultaneous measurement of strain and temperature during and after cure of unsymmetric cross-ply composite laminate using fibre-optic sensors. Fibre Bragg grating/extrinsic Fabry-Perot interferometric (FBG/EFPI) hybrid sensors are used to measure those measurands. The characteristic matrix of the sensor is derived analytically and measurements can be done without sensor calibration experiments. A wavelength-swept fibre laser is utilized as a light source. Two FBG/EFPI hybrid sensors are embedded in a graphite/epoxy unsymmetric cross-ply composite laminate in different directions and different locations. We perform the real-time measurement of fabrication strains and temperatures at two points within the composite laminate during the cure process in an autoclave. Also, the thermal strains and temperatures of the fabricated unsymmetric laminate are measured afterward in a thermal chamber. Through these experiments, FBG/EFPI sensors are proven to be an efficient choice for smart monitoring of composite structures
The signal characteristics of reflected spectra of fiber Bragg grating sensors with strain gradients and grating lengths
No full textAmong the numerous types of fiber optic sensors, FBG sensors are currently the most actively studied sensors due to their good multiplexing capabilities. The demodulation method of FBG sensors is based on detecting the wavelength shift of their sensor peaks. Properties such as strain, temperature, etc. can be measured simply by detecting them. However, the signal stability of FBG sensors can be influenced by strain gradients induced by structural geometry or cracks on the surface when FBG sensors are embedded into or attached on the structure. In this study, the signal characteristics of reflected spectra of FBG sensors were verified under strain gradients and the correlation between the grating length of FBG sensors and strain gradients were investigated quantitatively. From the experimental results, the optimum working range of the FBG sensors, where FBG sensors could be used without split of the sensor peak, was shown when they were under strain gradients
Lagrangian relaxation approach to the targeting problem
No full textIn this paper, we consider a new weapon-target allocation problem with the objective of minimizing the overall firing cost. The problem is formulated as a nonlinear integer programming model. We applied Lagrangian relaxation and a branch-and-bound method to the problem after transforming the nonlinear constraints into linear ones. An efficient primal heuristic is developed to find a feasible solution to the problem to facilitate the procedure. In the branch-and-bound method, three different branching rules are considered and the performances are evaluated. Computational results using randomly generated data are presented. (C) 1999 John Wiley & Sons, Inc
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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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