1,720,956 research outputs found
An investigation into the design of precision weeding mechanisms for inter or intra-row weed control
Get PDFThere is an increasing interest in the use of mechanical intra-row weeders because of
concern over environmental degradation and a growing demand for organically
produced food. The aim of this study was to investigate the factors that influence the
design of precision weeding mechanisms for inter-and intra-row weed control. The
purpose is to increase the understanding of the dynamics of the soil-machine
interactions and to develop a system for either organic farming or to reduce the
environmental loading of agrochemicals in conventional agriculture.
Both the graphical computer simulation studies and the use of a mathematical model
(O’Dogherty et al., 2007) for the kinematics of discs were used as tools to aid the disc
design to determine the optimum geometric characteristics for a rotating disc that will
be able to treat the intra-row area between the crop plants undisturbed circle. The
model has wide applicability for the interactive design of discs for a range of crops.
A force prediction model for shallow asymmetric static and rotating discs (about a
vertical axis) developed to predict the forces on rotating discs. The model takes into
account the geometric parameters of the discs, the speed of operation, the working
depth and the physical properties of the soil based upon those required for the general
soil mechanics equation which obeys the Mohr-Coulomb failure criterion. A
comparison of all experimental work encompassing the laboratory experiments with
non-rotating and rotating discs, incorporating the deflection effect of the shaft when
working at 0o inclination angle showed that the model is able to predict the draught
force with good accuracy. The predicted forces were 3.5% more than the measured
forces overall for a linear regression line (with a coefficient of determination of 0.7)
and 61% of the data were within bounds of ± 25% a line of equal magnitude.
The effect of working depth, inclination angle and disc geometry on draught and
penetration force requirements for flat and convex discs were assessed under
controlled laboratory conditions. Because of its simplicity a flat disc was an obvious
one to study as it is a circular blade with incorporating a cut-out sector, whilst the convex disc has the advantage of underside clearance. The effect of the concavity on
soil failure proved to be of interest by providing smaller aggregates. Four inclination
angles (0o - 15o) were examined at 0.5 m s-1 (1.8 km h-1) driving speed and 1 rev s-1
rotational speed at 10 mm deep. Four depths (10 mm - 25 mm) were examined at 0.5
m s-1 driving speed and 1 rev s-1 rotational speed at 10 mm deep and 0o inclination
angle were tested under controlled conditions. Inclination angle and disc geometry
had a significant effect on disc forces and soil failure. A small increase in inclination
angle to the direction of travel reduces the magnitude of draught and vertical force by
70% and 80% respectively on average for both flat and convex disc geometries. The
convex disc requires 15% less draught force than an equivalent flat disc. This allowed
the optimum working parameters for a disc to be selected to eliminate the weeds with
the minimum force requirements.
The results of a field experiment after 16; 23; and 33 days transplanting with a
working speed of 0.5 m s-1 (1.8 km h-1) showed that the proposed novel mechanical
weed control system can achieve a weed reduction within the crop row up to 87%.
The disc-hoe has a lower cost for an area of 125 ha of £81 ha-1,in comparison to £139
ha-1 for the inter-row and hand weeding combination and £690 ha-1 for a six man gang
manual intra-row weeding, for two passes. It is also less expensive than the cost of the
24 m tractor mounted sprayer of £100 ha-1
The use of the rotating disc-hoe for mechanical weed control would have the benefits
of lower mechanical weeding cost, increased potential for organic production and
reduction in the number of weeding operations through better targeting to minimise
problems caused by frequent soil disturbance and reduced herbicide use having the
benefits of environmental advantage
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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
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