1,720,982 research outputs found
pOp: Parameter Optimization of Differentiable Vector Patterns
No full textProcedural materials are extensively used in computer graphics, since they provide editable, resolution-independent representation of textures. However, tuning the parameters of procedural generators to achieve a desired result remains time-consuming for users. Recently, inverse procedural material algorithms have been developed, exploiting differentiable rendering methods to find the parameters of a procedural model that match a target image. These approaches focus on raster textures. We propose pOp, a practical method for estimating the parameters of vector patterns, that are formed by collections of vector shapes arranged by an arbitrary procedural program. In our approach, patterns are defined as arbitrary programs, that control the translation, rotation and scale or vector graphics elements. We support elements typical of vector graphics, namely points, lines, circle, rounded rectangles, and quadratic Bèzier drawings, in multiple colors. We optimize the program parameters by automatically differentiating the signed distance field of the drawing, which we found to be significantly more reliable than using differentiable rendering of the final image. We demonstrate our method on a variety of cases, representing the variations found in structured vector patterns
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
Design of a Portable Low-Cost I-V Curve Tracer for On-Line and In Situ Inspection of PV Modules
No full textIdentifying underperforming photovoltaic (PV) modules is crucial to ensure optimal energy production and financial returns, as well as preventing potential safety hazards in case of severe damage. To this aim, current–voltage (I-V) curve tracing can be employed as in situ monitoring technique for the early detection of faults. In this paper, we introduce a novel low-cost, microcontroller-based I-V tracer for the diagnosis of individual PV modules. The tool features a unique power conditioning circuit, facilitating accurate data acquisition under static conditions as well as the even distribution of the measured points along the I-V curve. A specific active disconnecting circuit enables in situ and on-line measurement without interrupting the string power generation. The designed prototype is used to characterize a set of PV modules under real operating conditions. The measured I-V curves exhibit expected trends, with the measured data closely matching theoretical values and an estimated mean relative error less than 3%
A Wireless Self-Powered I-V Curve Tracer for On-Line Characterization of Individual PV Panels
No full textThe behavior of a photovoltaic (PV) generator under specific irradiance and temperature conditions is mainly described by its current-voltage (I-V) characteristic. Therefore, the I-V curve tracing has to be considered the most accurate and effective diagnostic tool for the proper identification of PV panels' failures. In this article, an innovative I-V curve tracer for individual PV panels is presented. It ensures the following advantages. 1) An optimized I-V curve measurement due to an innovative tracing algorithm. 2) In-situ characterization during normal operation owing to a proper disconnection circuit. 3) Full portability thanks to a Li-ion battery power supply and a Bluetooth communication. The proposed tool has been designed and realized. The resulting prototype has been used to measure the I-V curve of a PV panel both in uniform and partial shading conditions
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
Impedance Spectroscopy as On-Field Monitoring Technique for PV Modules
No full textDetecting degradation phenomena on photovoltaic (PV) module working under real operating conditions is challenging. In recent years, impedance spectroscopy (IS) has been explored as a promising technique for the detection of faults in PV systems. The adoption of IS in on-field monitoring and diagnostic tools requires a reliable and straightforward ac model of the device under test. To this aim, the authors analyze the frequency response of standard crystalline silicon (c-Si) based PV module working under real operating conditions by means of technology computer aided design (TCAD) simulations in Sentaurus environment. The simulated experiments emulate the behavior of the PV module both in healthy and faulted conditions. Finally, the considerations arising from this analysis help to define practical guidelines as well as highlighting limitations of the adopted technique
A tool providing I-V curve and IS analysis of a PV module embedded in a string
No full textTo sustain the green transition, the Photovoltaic (PV) source is called to play a relevant role. To this aim the optimal energy yield of PV plants must be ensured by smart monitoring and diagnostics tools based on module-level characterization devices declined as IoT (Internet of Things) sensors. In this paper, the authors discuss the applicability of a I-V (current-voltage) tracer conceived to perform online electrical characterization of individual PV modules, to be adopted also for impedance spectroscopy analysis. Numerical simulation performed in Spice environment proves the applicability of the proposed approach. Nevertheless, challenging design aspects are also highlighted
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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