1,720,958 research outputs found
Influence of Bus Rapid Transit (BRI) on mixed-traffic capacity utilization and its time headway implications.
No full textDoctoral Degree. University of KwaZulu-Natal, Durban.Bus Rapid Transit (BRT) systems are sustainable mobility interventions that provide commuters with fast, safe, and efficient mobility. Unfortunately, they have been characterized by fundamental traffic flow parameter anomalies, especially speed changes, with attendant consequences on capacity utilization, capacity differentials, and time headway implications. Consequently, this study was carried out to determine the influence of Bus Rapid Transit (BRT) on mixed traffic capacity utilization and implications for time headways. The overarching objective was to develop a capacity utilization criteria table for assessing roadway performance and determining the Level of Capacity Utilization (LCU) with and without the influence of BRT. Criteria tables serve as standards by which the performance of a roadways in terms of capacity utilization is decided. Traffic data at peak and off-peak periods were collected for a ‘with and without’ BRT impact study at four selected road segments along route R27, located on BRT major trunk route T02 which connects Atlantis, Table View, and Sunset City. Data were logged for 12 weeks continuously using an Automatic Traffic Counter (ATC).
The study assumed that density was a function of speed and flow and hence was not directly impacted by BRT infrastructure based on the conditions at the time of the survey. It suggests that capacity utilization is triggered by variations in speed, and the attendant variations in density, capacity, and time headways were used to estimate capacity utilization rates and determine the LCU. Traffic data on speed, vehicle classes, and volumes were collected, and the results were analyzed. The collected traffic volumes were converted to flow using the South African passenger car equivalent (PCE) values. The results showed speed reductions with attendant differentials in other parameters such as capacity, density, travel time, and time headways. From the developed criteria table, the estimated capacity utilization rates for the BRT dedicated lanes scenario showed poor LCU at E (9% and 36%) across the four sites SS001 to SS004, under steady flow conditions. The capacity utilization rates of the mixed traffic ‘without BRT’ scenario showed fair utilization within the range of 37% and 79%, with average LCU at C across the four sites, whilst the capacity utilization rates of mixed traffic ‘with BRT’ scenario also showed fair utilization (between 40% and 75%), with average LCU C. The time headway implications induced by the capacity utilization and its differentials were also modelled, and the empirical time headway data were fitted to continuous probability distribution models. The Burr continuous probability distribution model, which is known for its compatibility, flexibility and appropriateness in modelling headway data under different traffic conditions, provided the best fit, having emerged with the largest Log-likelihood, and the smallest Akaike Information Criterion (AIC) values at 95% confidence and 0.05 significance levels across the four sites. At sites SS002, SS003, and SS004, it ranked first with the lowest AIC values of 3623.33, 4002.73, 3857.44, and corresponding largest LLH values of -1807.64, -1997.35, and -1924.70, respectively, while the Gaussian distribution performed best at site SS001, with the lowest AIC value of 4356.01 and largest LLH value of -2176.00, closely followed by the Generalized Extreme Value (GEV) distribution with the lowest AIC and largest LLH values of 4368.09 and -2181.03, respectively at off-peak traffic period. The Burr distribution however performed second best at peak traffic with the lowest AIC and largest LLH values of 4352.49 and -2172.23. The P-values, which ranged between 0.65 and 0.81 across the four sites showed the likelihood of the occurrence of the data sets under the null hypothesis. Hence the null hypothesis was accepted. In conclusion, the study showed that mixed traffic operations ‘with BRT’ and its associated minimized time headways, could significantly enhance capacity utilization. In view of the mixed traffic scenarios considered with and without BRT, it is hereby recommended for future research consider analysing traffic capacity through the development and application of microscopic fundamental diagrams, and a simulation of the time headway distribution of the mixed traffic scenario with BRT should also be considered. In traffic engineering practice, the curbside and mixed traffic designs are therefore recommended for implementation in future BRT infrastructure as the way forward for the South African BRT system for enhanced capacity utilization and sustainable mobility
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
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