1,721,059 research outputs found
Chemical sensing employing plant electrical signal response-classification of stimuli using curve fitting coefficients as features
No full textIn order to exploit plants as environmental biosensors, previous researches have been focused on the electrical signal response of the plants to different environmental stimuli. One of the important outcomes of those researches has been the extraction of meaningful features from the electrical signals and the use of such features for the classification of the stimuli which affected the plants. The classification results are dependent on the classifier algorithm used, features extracted and the quality of data. This paper presents an innovative way of extracting features from raw plant electrical signal response to classify the external stimuli which caused the plant to produce such a signal. A curve fitting approach in extracting features from the raw signal for classification of the applied stimuli has been adopted in this work, thereby evaluating whether the shape of the raw signal is dependent on the stimuli applied. Four types of curve fitting models—Polynomial, Gaussian, Fourier and Exponential, have been explored. The fitting accuracy (i.e., fitting of curve to the actual raw signal) depicted through R-squared values has allowed exploration of which curve fitting model performs best. The coefficients of the curve fit models were then used as features. Thereafter, using simple classification algorithms such as Linear Discriminant Analysis (LDA), Quadratic Discriminant Analysis (QDA) etc. within the curve fit coefficient space, we have verified that within the available data, above 90% classification accuracy can be achieved. The successful hypothesis taken in this work will allow further research in implementing plants as environmental biosensors
C-planarity testing of embedded clustered graphs with bounded dual carving-width
No full textFor a clustered graph, i.e, a graph whose vertex set is recursively partitioned into clusters, the C-Planarity Testing problem asks whether it is possible to find a planar embedding of the graph and a representation of each cluster as a region homeomorphic to a closed disk such that 1. the subgraph induced by each cluster is drawn in the interior of the corresponding disk, 2. each edge intersects any disk at most once, and 3. the nesting between clusters is reflected by the representation, i.e., child clusters are properly contained in their parent cluster. The computational complexity of this problem, whose study has been central to the theory of graph visualization since its introduction in 1995 [Feng, Cohen, and Eades, Planarity for clustered graphs, ESA'95], has only been recently settled [Fulek and Tóth, Atomic Embeddability, Clustered Planarity, and Thickenability, to appear at SODA'20]. Before such a breakthrough, the complexity question was still unsolved even when the graph has a prescribed planar embedding, i.e, for embedded clustered graphs. We show that the C-Planarity Testing problem admits a single-exponential single-parameter FPT algorithm for embedded clustered graphs, when parameterized by the carving-width of the dual graph of the input. This is the first FPT algorithm for this long-standing open problem with respect to a single notable graph-width parameter. Moreover, in the general case, the polynomial dependency of our FPT algorithm is smaller than the one of the algorithm by Fulek and Tóth. To further strengthen the relevance of this result, we show that the C-Planarity Testing problem retains its computational complexity when parameterized by several other graph-width parameters, which may potentially lead to faster algorithms
Subexponential-time and FPT algorithms for embedded flat clustered planarity
No full textThe C-Planarity problem asks for a drawing of a clustered graph, i.e., a graph whose vertices belong to properly nested clusters, in which each cluster is represented by a simple closed region with no edge-edge crossings, no region-region crossings, and no unnecessary edge-region crossings. We study C-Planarity for embedded flat clustered graphs, graphs with a fixed combinatorial embedding whose clusters partition the vertex set. Our main result is a subexponential-time algorithm to test C-Planarity for these graphs when their face size is bounded. Furthermore, we consider a variation of the notion of embedded tree decomposition in which, for each face, including the outer face, there is a bag that contains every vertex of the face. We show that C-Planarity is fixed-parameter tractable with the embedded-width of the underlying graph and the number of disconnected clusters as parameters
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
The parametrized complexity of the segment number
No full textGiven a straight-line drawing of a graph, a segment is a maximal set of edges that form a line segment. Given a planar graph G, the segment number of G is the minimum number of segments that can be achieved by any planar straight-line drawing of G. The line cover number of G is the minimum number of lines that support all the edges of a planar straight-line drawing of G. Computing the segment number or the line cover number of a planar graph is there exists R-complete and, thus, NP-hard. We study the problem of computing the segment number from the perspective of parameterized complexity. We show that this problem is fixed-parameter tractable with respect to each of the following parameters: the vertex cover number, the segment number, and the line cover number. We also consider colored versions of the segment and the line cover number
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
Carbon Dioxide Electroreduction on Gas Diffusion Electrodes: A study on electro-deposited copper catalysts
No full textRapid industrialization and use of carbon based fuels has caused a drastic increase in the atmospheric CO2 levels in the last few decades. The rising anthropogenic CO2 levels pose a significant threat to the environment as evidenced by the increase in the mean global temperature levels, and the rising ocean levels. To mitigate the challenges associated with rising CO2 levels, there is an urgent need to move towards carbon neutral sources of energy and to curb carbon emission from large scale point emitters such as industries. Additionally, emitted CO2 could be converted into energy dense organic fuels using carbon-neutral forms of energy. This not only helps in reducing the carbon emissions but also balances the intermittent nature of renewable energy supply. CO2 could also be converted into platform chemicals such as ethylene/CO, which can be further up-converted or directly used in industry. Ethylene is particularly interesting due to its highenergy density and wide industrial usage as a precursor in the polymer industry. Electroreduction of CO2 provides one such approach to electrochemically convert CO2 produced at large scale emitters to useful organic compounds. Different metallic catalysts are known to catalyse the electrochemical reduction towards different products, which follows from Sabatier’s principle. In this study copper is used as the model catalyst due to its unique ability to electrochemically convert CO2 to multi-carbon products, such as ethylene. From a cell design perspective conventional electrochemical reduction of CO2 in aq. media suffers from low production rates due to the low solubility of CO2 in aq. electrolytes which makes it not feasible from an industrial standpoint. To overcome the low production rates, this study was carried out on novel gas diffusion electrodes. Another factor limiting the implementation of CO2 electrolysers on an industrial scale, is the scalability of the catalyst synthesis. To improve this, electrodeposition of copper catalysts was employed. Electrodeposition is a well-established industrial technique and integrable within the existing infrastructure. Electrodeposition facilitates in-situ growth of the catalyst on gas diffusion layers, thereby providing a facile alternative to the conventional multi-step process for catalyst synthesis. Different morphologies of copper were synthesized by varying the electrodeposition process parameters. Copper nanowires were also synthesized by using templated electro-deposition techniques. The catalysts were characterised before and after the CO2 reduction experiments by Scanning ElectronMicroscopy, and X- Ray Diffraction. CO2 reduction experiments using the synthesised copper catalysts were carried out over a range of potentials. A peak Faradaic Efficiency (FE%) of 15% was measured at -1.5 V vs RHE (uncompensated) for ethylene, 19% FE at -1.1 V vs RHE for formic acid, and 13% FE at -1.5 V vs RHE for methane. It was also seen that the catalyst suffered from stability issues which were overcome by using pulsed electrolysis. Using pulsed electrolysis the lifetime of the catalyst was increased from 30 minutes to 15 hours.Materials Science and EngineeringMechanical Engineering | Vehicle Engineerin
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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