1,721,085 research outputs found
Uncut free pocketing tool-paths generation using pair-wise offset algorithm
No full textFor die-cavity pocketing, contour-parallel machining is the most popular machining strategy. Two issues in generating contour-parallel tool paths for pocketing are: (1) a robust two-dimensional (2D)-curve offsetting algorithm; and (2) detecting and removing uncut regions. The 2D-curve offsetting solution has been widely studied, because it has so many potential applications. However, though the importance of the uncut problem in pocketing has long been recognized there have been few reported investigations on detecting and removing uncut regions. This paper presents a procedure for generating pocketing tool paths leaving no uncut regions. For the 2D-curve offsetting algorithm, we employ the PWID offset algorithm suggested by Choi and Park (Computer Aided Design, 31(12) (1999) 735) and expand the algorithm for offsetting areas having islands. Based on the expanded PWID offset algorithm, our solution to the uncut problem removes the uncut regions. Empirical tests show the usefulness of the proposed procedure for improving the productivity of pocket machining. (C) 2001 Elsevier Science Ltd. All rights reserved
FINITE-ELEMENT BASIS FOR THE EXPANSION OF RADIAL WAVE-FUNCTION IN QUANTUM SCATTERING CALCULATIONS
No full textRadial wavefunctions in quantum scattering calculations are expanded in terms of two shape functions for each finite element. This approach is the R matrix version of Kohn's variational method and also directly applicable to S matrix in the log-derivative version. The linear algebra involved amounts to solving definite banded systems. In this basis set method, R matrix or log-derivative matrix is greatly simplified and the computational effort is linearly proportional to the number of radial basis functions, promising computational efficiencies for large scale calculations. Convergences for test vases are also reasonably rapid
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
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
ELECTRICAL-PROPERTIES OF CDTE-FILMS PREPARED BY CLOSE-SPACED SUBLIMATION WITH SCREEN-PRINTED SOURCE LAYERS
No full textCdTe films have been deposited by a close-spaced sublimation process with screen-printed CdTe layers as a new source. The source-layers were fabricated by screen printing and sintering slurries consisting of propylene glycol, CdCl2 and either CdTe powder or (Cd+Te) powder. When CdTe powder was used as a starting material for the source-layer, the electrical resistivity of the CdTe film deposited in O-2 was about one-tenth lower than that of the film deposited in He. AES, EDS and PIXE analysis showed that the Cd content in the CdTe films deposited in O-2 was Smaller than that in the CdTe films deposited in He. Especially, no oxygen element was detected in the CdTe films deposited in O-2. It turned out that the Sublimated Cd(g) and CdTe(g) from the source-layer formed cadmium oxides in O-2 and as a result the overall composition of vapor source became more Cd-deficient. The CdTe film with less Cd content increased cadmium vacancy defects (V2-Cl+ and ed V-Cd(2-)) and hole concentrations. As the Cd/Te ratio in the starting (Cd+Te) powder decreased, the ed resistivity of the CdTe films decreased and reached at a constant value of about 3x10(4) Omega . cm, regardless of deposition atmosphere. In addition, the resistivity decrease by O-2 treatment was diminished when the Cd/Te ratio was below 0.7, where the composition of CdTe film might be limited by solid solubility (Cd0.92Te1.0) The above results indicated that the resistivity decrease of CdTe films deposited in O-2 was not due to the effect of previously-known oxygen doping but due to the effect of Cd/Te compositional change. (C) 1995 American Institute of Physics
Photovoltaic properties of close-space sublimated CdTe solar cells
No full textCdS/CdTe solar cells were fabricated by close-space sublimation with a screen-printed Te-rich CdTe source and their photovoltaic properties were investigated by varying the substrate temperature, cell area, and thicknesses of CdTe and ITO layers. The resistivity of CdTe layers employed in this study was 3 x 10(4) Omega cm. The optimum substrate temperature and thickness for CdTe deposition were 600 degrees C and 5 mu m, respectively. The CdTe bulk resistance degraded the cell performance above 6 mu m. As the cell area increased the V-oc remained almost constant, while the J(ae) and FF were strongly degraded because of the increase of the lateral resistance of the ITO layer. The optimum thickness of the ITO layer in this study was 300-450 nm. In this experiment we obtained an efficiency of 9.4% in the 0.5 cm(2) cells. The series resistance of the cell should be further reduced to increase the fill factor and improve the efficiency. (C) 1998 Elsevier Science Ltd. All rights reserved
Electrical properties of CuInSe2-films prepared by evaporation of Cu2Se and In2Se3 compounds
No full textWe prepared CuInSe2 films by evaporating In2Se3 and Cu2Se compounds instead of elemental sources, The resulting CuInSe2 film grown at 680 degrees C had a smooth and dense microstructure with the grain size of 2 similar to 3 mu m. But the CuInSe2 films were Cu-rich, with a low resistivity of about 0.1 Omega cm. So we conducted H-2 post annealing to control the electrical resistivity and composition of CuInSe2 films. In a H-2 atmosphere, the resistivity increased to about 100 Omega cm by annealing at 350 degrees C for 1 h. The resistivity decreased again when the annealing temperature was above 350 degrees C, This resistivity change might be related to the contents of Cu, In, Se atoms and the valency states of Cu and In ions in the films. We discussed the reason of resistivity change caused by H-2 post annealing in this paper
- …
