1,721,387 research outputs found
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
Investigation of the Temperature Effects on Copper Losses in Hairpin Windings
Full text linkToday, an extensive electrification is occurring in all industrial sectors, with a special interest seen in the automotive and aerospace industries. The electric motor, surely, is one of the main actors in this context, and an ever-increasing effort is spent with the aim of improving its efficiency and torque density. Hairpin windings are one of the recent technologies which are implemented onto the stator of the electric motor. Compared to conventional random windings, it inherently features lower DC resistance, higher fill factor, better thermal performance, improved reliability, and an automated manufacturing process. However, its bottleneck is the high ohmic losses at high-frequency operations due to skin and proximity effects (AC losses), resulting in a negative impact on the temperature map of the machine. Nevertheless, while it is well-known that DC losses increase linearly with the operating temperatures, the AC losses trend needs further insight. This paper demonstrates that operating the machine at higher temperatures could be beneficial for overall efficiency, especially at high-frequency operations. This suggests that a paradigm shift is required for the design of electric motors equipped with hair-pin windings, which should therefore focus on a temperature-oriented approach. In addition, the effect of the rotor topology on AC losses, which is often overlooked, is also considered in this paper. The combination of these effects is used to carry out observations and, eventually, to provide design recommendations. Finite element electromagnetic and thermal evaluations are performed to prove the findings of this research
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
An innovative formulation for buckling analysis of nano-tapered Timoshenko beams with axially varying materials
Full text linkThis paper presents a novel and low-cost formula based on the first-order shear deformation theory and Eringen's nonlocal elasticity theory for the stability analysis of tapered Timoshenko nanobeams with axially varying materials. The coupled governing differential equations of the problem, involving both the transverse displacements and rotations, stem from the energy method. Based on a mathematical manipulation, the system of equilibrium equations is converted to a novel single fifth-order differential equation with variable coefficients in terms of the vertical deflection, which is solved numerically to obtain the axial buckling load. The accuracy of the proposed formulation is first verified against the available literature, with the additional advantage related to its reduced computational effort, compared to other formulations. A systematic investigation is, thus, performed to check for the influence of the non-local parameter, power-law index, tapering ratio and length-to-thickness aspect ratio on the linear buckling strength of simply supported functionally graded nano-tapered Timoshenko beams. Due to the generality of the derived formula, it can be adjusted for the optimal design of Timoshenko nanobeams with favorable axial changes in material properties as well as the geometrical features
Experimental Validation of Spectral-Spatial Power Evolution Design Using Raman Amplifiers
Full text linkWe experimentally validate a machine learning-enabled Raman amplification framework, capable of jointly shaping the signal power evolution in two domains: frequency and fiber distance. The proposed experiment addresses the amplification in the whole C-band, by optimizing four first-order counter-propagating Raman pumps
Nonlocal analysis of the flexural–torsional stability for FG tapered thin-walled beam-columns
Full text linkThis paper addresses the flexural–torsional stability of functionally graded (FG) nonlocal thin-walled beam-columns with a tapered I-section. The material composition is assumed to vary continuously in the longitudinal direction based on a power-law distribution. Possible small-scale effects are included within the formulation according to the Eringen nonlocal elasticity assump-tions. The stability equations of the problem and the associated boundary conditions are derived based on the Vlasov thin-walled beam theory and energy method, accounting for the coupled interaction between axial and bending forces. The coupled equilibrium equations are solved numer-ically by means of the differential quadrature method (DQM) to determine the flexural–torsional buckling loads associated to the selected structural system. A parametric study is performed to check for the influence of some meaningful input parameters, such as the power-law index, the nonlocal parameter, the axial load eccentricity, the mode number and the tapering ratio, on the flexural–torsional buckling load of tapered thin-walled FG nanobeam-columns, whose results could be used as valid benchmarks for further computational validations of similar nanosystems
Inverse design of a Raman amplifier in frequency and distance domains using convolutional neural networks
Full text linkWe present a convolutional neural network architecture for inverse Raman amplifier design. This model aims at finding the pump powers and wavelengths required for a target signal power evolution in both distance along the fiber and in frequency. Using the proposed framework, the prediction of the pump configuration required to achieve a target power profile is demonstrated numerically with high accuracy in C-band considering both counter-propagating and bidirectional pumping schemes. For a distributed Raman amplifier based on a 100 km single-mode fiber, a low mean set (0.51, 0.54, and 0.64 dB) and standard deviation set (0.62, 0.43, and 0.38 dB) of the maximum test error are obtained numerically employing two and three counter-, and four bidirectional propagating pumps, respectively
Development of high antioxidant / high fiber functional peach nectar containing lutein/lycopene and various dietary fibers using D-optimal mixture design optimization
Full text linkFor developing a type of healthy and functional drink with high fiber and antioxidant properties, three types of dietary fiber (bamboo fiber, citrus fiber, and polydextrose) and two types of carotenoids (lycopene and lutein) were used in the peach nectar-based formulations. Based on the D-optimal mixture design, the ratio of fibers in a constant amount of fiber mixture (6 g) and the ratio of carotenoids in a constant amount of carotenoid mixture (6 mg) were selected as independent variables. 24 formulations were presented by Design Expert software, and based on anti-oxidant and physical stability tests, the highest desirability was achieved by the formulation with 100% polydextrose and 100% lycopene (F8 sample) with a desirability of 0.997. This formulation showed 88% of stability and 85% of DPPH antioxidant activity. In addition to the F8 sample, five other samples were selected for further experiments. These formulations showed total phenolic contents ranging from 85.2 to 123.6 mg GAE/100 ml, total flavonoids from 7.3 to 18.4 mg QE/ 100 ml, and vitamin C content between 9.2 and 15.8 mg/ 100 ml. The retention of lycopene and lutein after 8 weeks of storage at 4 degrees C ranged from 41.2-68.9% and 45.6-74.3 %, respectively. The first-order kinetic model best described lycopene and lutein degradation (R-2> 0.94). Rheological analysis indicated shear-thinning behavior with consistency coefficients (K) ranging from 0.15 to 1.04 Pa.s(n). Sensory evaluation reveals F2 and F8 as the most preferred formulations, with overall acceptability scores of 4.3 and 4.1 out of 5, respectively. The results demonstrate that both fiber type and carotenoid selection significantly affect antioxidant activity, stability, and sensory attributes of fortified peach nectar
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