1,720,964 research outputs found
Benchmarking the vibration velocity-based measurement methods to determine the radiated sound power from floor elements under impact excitation
Get PDFThe Rayleigh Integral Method, the Integral Transform Method and the Discrete Calculation Method are all vibration velocity-based measurement methods to determine the radiated sound power from planar objects. Even though all these three methods are based on a well-established theoretical background, which has been known for long time, they are only now gaining popularity in the building acoustics field and the building acoustics community is still rather new to them. They offer advantages compared to the standard methods specially in the low frequency range or on special applications with articulated boundary conditions. In this paper, we want to summarize the three methods in one place to highlight their different theoretical foundations. We present a numerical benchmark of these three methods, based on a simple panel with varying boundary conditions, highlighting similarities and differences between them. In a second step, we compare the radiated sound power levels obtained by the three methods with results obtained by a standard measurement procedure according to the ISO 10140-3, under excitation by an ISO tapping machine. Finally, we present the application of the methods to determine the in-situ impact noise level of a floor structure: a complex system with challenging boundary conditions. The results show a good agreement between all the tested methods, as long as the respective requirements are satisfied. The results also demonstrate how the vibration velocity-based measurement methods can have a broader application compared to the standard laboratory method and deliver additional information on complex test objects.publishedVersio
Vibroacoustic analysis of the Woodsol timber frame building concept
Get PDFThe segment of buildings with four to eight storey is a major share of the building construction market in urban areas. Despite the fact that building with timber has both economical relevance and environmental advantages, the use of timber for urban buildings is still limited to pilot projects. The main reason for this is the limited economical competitiveness of timber buildings due to the risk associated with a lack of knowledge and experience with timber design and construction, compared to the standard concrete and steel buildings. The Woodsol project aims at filling this knowledge gap by developing a timber building concept for urban buildings with a high degree of architectural flexibility. The concept is based on moment resisting timber frames and long-span floor elements. The work presented in this thesis addresses the acoustic aspects and focuses on four main areas of interest: i) the strategy to reliably and accurately determine the acoustic properties of the floor elements, ii) the verification and utilisation of vibration velocity measurement methods to determine the impact sound insulation, iii) the typical properties of the hollow-box floor elements and the influence of the moment resisting connections and iv) possible practical solutions. Low frequency impact sound determines to a large extent occupants’ annoyance in lightweight buildings. At the same time, challenges exist in determining accurately the low frequency sound insulation properties of building elements. Therefore, throughout this work, I put a strong focus on the low frequency range.
I adopted a strategy based on experimental activities on prototype floor elements and a full scale system mock-up. I studied the modal behaviour of the floor elements by means of the Experimental Modal Analysis and determined the radiated sound power under impact excitation using the Integral Transform Method (ITM). I performed a parameter study to investigate the effect of the size and of the boundary conditions of the hollow-box floor elements on the modal behaviour and on the sound radiation. I observed a strong dependency of both aspects on the studied parameters at frequencies below 150 Hz. This highlighted some limitations of the standard laboratory measurement procedure according to ISO 10140-2 and ISO 10140-3 in the low frequency range.
The ITM is still a rather new method within building acoustics and therefore part of the activities was aimed at verifying the adequacy of the method for our purposes. I compared the ITM with other vibration velocity measurement methods and with the standard laboratory measurement procedures. I demonstrated the reliability of the ITM and showed how the ITM can overcome the highlighted limitations. The airborne and impact sound insulation performance of the Woodsol floor element were included in a comparison of the properties of similar objects. The effect of the additional mass in the cavity or on top of the elements was investigated and we determined the effect of different floating floor solutions on top of the hollowbox. This allowed to identify the parameters governing the acoustic performance of this type of elements and their respective relationships. Within the common flooring solutions in the Norwegian building industry, I identified the practical solutions that can fulfil acoustic requirements according to the Norwegian standard for office, residential and educational buildings, when used with the Woodsol floor elements. More advanced solutions were proposed to meet higher requirements.
Overall, within this work I was able i) to highlight the main parameters governing the acoustic behavior of the hollow-box floor elements, ii) to identify and validate a measurement method that allows us to accurately measure the radiated sound power under impact excitation in-situ, iii) to describe the general airborne and impact sound insulation performance of hollow-box floor elements and iv) to finally suggest practical solutions that might fulfil the acoustic requirements according to the Norwegian standards
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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