1,720,958 research outputs found
Boilers Emissions Under Different Stack Configurations at a School in Saranac Lake, NY
No full textA 1.7 MMBTU wood pellet boiler was installed in a container outside the Petrova Elementary School, Saranac Lake to provide heat to the building and reduce the dependence on fuel oil. The exhaust stack was initially 25’ high, i.e. less than the school building height and the effluent stream could then enter through the building air intakes. Computational fluid dynamics modeling was performed to assess the emission impacts for a taller stack. Results showed if the stack height was raised to 45’ (10’ above the roof), the plume would loft over the building and avoid the air intakes. However, the USEPA best practices guidelines suggested the stack should be 2.5 times the height of the structure.
From December 2015, a sampling campaign was conducted to evaluate if the increased stack height was sufficient to reduce the air pollutant concentrations at the roof top and, thus, if the stack configuration was sufficient to avoid boiler exhausts be drawn into the school. CO, black carbon and PM were measured on the roof of the school. Weather and wind parameters were also measured. Air pollution data were recorded in periods without boiler emissions and then with both the short and taller stacks in place. A series of chemometric tools were thus applied for: (i) comparing the levels of pollutants during different stack configurations; (ii) investigating the relationships among pollutants and boiler operation modes; (iii) detect possible effects of meteorology on the levels of air pollutants. The results of this evaluation will be presented
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
Hourly land-use regression models based on low-cost PM monitor data
Get PDFLand-use regression (LUR) models provide location and time specific estimates of exposure to air pollution and thereby improve the sensitivity of health effects models. However, they require pollutant concentrations at multiple locations along with land-use variables. Often, monitoring is performed over short durations using mobile monitoring with research-grade instruments. Low-cost PM monitors provide an alternative approach that increases the spatial and temporal resolution of the air quality data. LUR models were developed to predict hourly PM concentrations across a metropolitan area using PM concentrations measured simultaneously at multiple locations with low-cost monitors. Monitors were placed at 23 sites during the 2015/16 heating season. Monitors were externally calibrated using co-located measurements including a reference instrument (GRIMM particle spectrometer). LUR models for each hour of the day and weekdays/weekend days were developed using the deletion/substitution/addition algorithm. Coefficients of determination for hourly PM predictions ranged from 0.66 and 0.76 (average 0.7). The hourly-resolved LUR model results will be used in epidemiological studies to examine if and how quickly, increases in ambient PM concentrations trigger adverse health events by reducing the exposure misclassification that arises from using less time resolved exposure estimates
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
Predicting the Spatial Variability of PM in Urban Areas with Low-Cost Monitors and Land Use Regression Modelling
No full textUrban air monitoring stations are used to measure city-wide pollution levels (i) for regulatory purposes and (ii) to estimate the average exposure for the population. However, the spatial coverage from one or at most a few regulatory monitoring stations is insufficient to capture the spatial variability in PM concentrations across urban areas. This lack of spatial data represents a serious knowledge gap when performing human inhalation exposure studies. Inadequate spatial resolution may mask the exposure variability in the study population and may lead to potential exposure misclassifications.
The intra-urban variation of air quality can be resolved by using land-use regression (LUR) models, which require sampling measurement campaigns at multiple locations along with a set of predictor variables derived from geographic information systems (e.g., various traffic representations, population density, land use, physical geography and climate). However, such sampling campaigns are usually short in time or use mobile monitoring networks due to the high cost for deployment and maintenance of scientific-grade instruments. The recent development of low-cost PM monitors is potentially a viable solution to increase the spatial resolution of air quality monitoring and to perform long-term sampling campaigns at multiple sites.
This study aims to produce an hourly-resolved LUR model to predict hourly PM concentrations at individual locations across Monroe County, NY. The study uses spatially-resolved PM data measured with low-cost monitors for the development of the LUR model. Low cost PM monitors (Speck, Airviz Inc. PA, USA) were placed at 23 sites across Monroe County, NY during the 2015/16 heating season (November to March). Data were handled according to the results of previous intercomparison studies with reference instruments to assure a robust and reliable dataset. Coefficients of determination for hourly PM predictions between 0.6 and 0.65 for the various sites, which is comparable with previous LUR studies for daily PM predictions
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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