1,721,084 research outputs found
Measuring soil bulk density profiles with a single probe gamma density gauge
Get PDFCalibrating neutron depth gauges for measuring soil water content profiles requires
soil bulk density data. In this study, the feasibility of using a single probe gamma
density gauge to measure the soil wet bulk density was investigated for use in neutron
gauge calibration. The same sites, access tubes, and conventional gravimetric soil data
used for the ASCE Neutron Gauge Calibration Study were used for the Gamma Gauge
Study. Iterative procedures were successfully developed to calibrate the gamma
density gauge, and then to convert wet bulk density to dry bulk density data for the
three soil sites studied
Error analysis of bulk density measurements for neutron moisture gauge calibration
Get PDFSix bulk density sampling methods were evaluated for use in neutron gauge
calibration. All six methods provided estimates of bulk density which were
generally within 5% of bulk density profiles measured using a gamma probe.
Standard errors of estimate ranged from 3 to 7 %. When used with care,
downhole, coring, and drive samplers can be used to successfully measure soil
moisture and bulk density profiles for use in neutron probe calibration
The ASCE neutron probe calibration study: overview
Get PDFA workshop was held at Logan, Utah to gather field information on
neutron probe calibration and operation. Several techniques and instruments
were compared. This paper serves to establish the background information for
the work and describe the overall approaches, conditions, and equipment. Other
papers presented at this conference provide detailed procedures and results
Soil bulk density sampling for neutron gauge calibration
Get PDFThe ASCE Task Committee on Neutron Gauge Calibration met in Logan, Utah in July
1992 to investigate the various methods of soil sampling, installation of access tubes,
effect of various parameters on gauge readings, methods of developing field calibration
curves and comparison of neutron gauge characteristics. Details of the overall objectives
of the study are covered by Stone (1993, this volume). This paper discusses the soil
sampling methods and presents a comparative result based on bulk density, time required
for sampling and cost of sampling equipment Other papers developed from this study
describe the soils, the three sites investigated and the problems related to the tube
installation process
Neutron gauge calibration comparison of methods
Get PDFSeveral methods for obtaining soil samples for determining soil water content were used
for field calibration of neutron gauges. This paper compares the results of calibration
curves obtained from the study data by comparing intercepts, slopes and correlation
coefficients ("r" values). The study found differences in characteristics between gauges
of the same brand, differences between brands and a great effect by access tube
materials on the calibration curve
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
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