1,720,953 research outputs found
The remote sensing of forest canopy gaps in a selectively logged submontane tropical forest reserve in Kenya
No full textA thesis submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy to the Faculty of Science, University of the Witwatersrand, 2022Forests constitute 31% (about 4 billion ha) of the land area of the earth, and tropical forests cover is about 2 billion ha. Tropical forests play a significant role in supporting the earth's life and natural ecosystems. But many conservation and protection efforts have not been effective, as they are being cleared in many countries for timber and expansion of agricultural land. Few undisturbed tropical forests remain today, and unsustainable selective logging (SL) is probably the single biggest factor contributing to the global degradation of tropical forests. The amount of forest degradation that is not detected using currently available remote sensing (RS) techniques is unknown. Many methods used to map SL in tropical forests using low/medium spatial resolution datasets have a high rate of false detections. As a result, reliable and operational methods for monitoring SL in tropical forests ought to be utilized. Recently, very high resolution (VHR) RS datasets have caught the interest of researchers studying SL in tropical forests.
Therefore, this study was aimed to apply spectral-texture analysis approach to detect canopy gaps caused by illegal logging of Ocotea usambarensis (East African camphor) in Mt. Kenya Forest Reserve (MKFR) in Chuka, Tharaka Nithi County, Kenya using the VHR WorldView-3 (WV-3) satellite data. Several features were derived from the WV-3 data— however, a large number of features results to longer computing time, and might result in reduced classification accuracy. Therefore, feature ranking measures—the mean decrease accuracy, the mean decrease Gini, and the pairwise feature correlation were used. The JeffriesMatusita distance, the transformed divergence index, the G-statistic, and the Euclidean distance were used to calculate the separability of the forest landscape classes. First, the study reviewed and discussed RS techniques used to map SL in the tropical forests. Second, the threatened trees species (TS) in the selectively logged MKFR were mapped. Third, gaps in the forest canopy were detected and quantified using two approaches—initially, only spectral features were used to detect gaps in the forest canopy. A total of 55 spectral features were extracted from the WV-3 dataset—23 means (of 15 vegetation indices–VIs and 8 visible-near-infrared– VNIR bands), and 23 standard deviations–SDs (of 15 VIs and 8 VNIR bands). Also extracted were 8 ratios (of 8 VNIR bands), and 1 brightness feature (average of the means of bands 1 to 8). The study also explored the potential of rich textural features combined with color to model canopy gaps using GLCM-, LBP-, and MLBP-based rotation-invariant feature descriptors derived from WV-3 imagery. Due to their excellent performance and clear logic, two advanced machine learning (ML) classification models—the random forest (RF) and support vector machine (SVM) models were used to identify and classify canopy gaps in the spectral and texture domains of the WV-3 data. During the training process the learning parameters of RF (mtry and ntree) and SVM (γ and C) algorithms were optimised to obtain the best possible settings. Finally, the study reviewed Kenya’s forest policy and law on participatory forest management (PFM).
The best tree species classification results reported F1-scores of 68.56 ± 2.6% and 64.64 ± 3.4% for RF and SVM, respectively. The RF and SVM models used to map canopy gaps using the spectral features reported average overall accuracies (OAs) of 92.3 ± 2.6% and 94.0 ± 2.1%, respectively. Average kappa coefficients (ĸ) were 0.88 ± 0.03 for RF and 0.90 ± 0.02 for SVM. The user’s accuracy (UA) and producer’s accuracy (PA) were in the range of 84– 100%. The OA for the classification of canopy gaps using textural/spectral features reported values between 80 (RF, block F’s MLBP/ASM) and 95.1% (SVM, block E’s MLBP/CON). The average OA scores were 84.68 ±3.1, 84.54 ±2.5, 84.86 ±3.0, 86.46 ±3.9, 87 ±4.0, and 85.44 ±3.7 for image blocks A, B, C, D, E, and F, respectively, for the RF classifier, and 85.44 ±3.6, 87.2 ±1.8, 86.3 ±4.3, 89.84 ±2.8, 87.28 ±4.5 and 86.12 ±3.6 for the SVM classifier. The iii UA and PA were in the range of 67-75% and 77-100% for the univariate LBP and MLBP models, respectively. Texture fused with colour resulted to higher classification accuracies.
Overall, the approach used in this study demonstrated improved ability of VHR satellite data and ML classification models to accurately map fine canopy gaps resulting from SL. Knowledge about where canopy gaps are located and how they are distributed is critical in accurate estimation of carbon densities of forests, and also for managing the proliferation of invasive species, among other applications. LiDAR datasets acquire the three-dimensional (3- D) structure of forest vegetation—repeat surveys can thus detect the removal of individual trees. The integration of optical images and LiDAR data may boost canopy gap classification.PC(2023
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
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
- …
