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Characterization of explosion pressure waves behind embankments
No full textThe increasing urbanization in the world leads to new risks and consequences of an explosion. One possible blast-mitigation procedure is the use of protective embankments. Today, there is a lack of updated standardization and guidelines for the design and effect of such embankments. The aim of this thesis is to investigatethe blast mitigation of different embankment designs to deepen the understanding of how the pressure wave from an explosion will behave after it has interacted withthe embankment. Numerical Computational Fluid Dynamics (CFD) simulations were conducted to study the effect of different embankment designs. Several studies where the results were compared against previous experiments and empirical relations was conducted in order to calibrate the model used. For the subsequent parametric study of the embankment design, two main parameters were studied; the distance of the embankment to the explosive charge, and the height of the embankment. Different combinations of these parameters with different wall types resulted in 68 simulations. The reflected peak pressure and impulse density were extracted from a target behind the embankment with dimensions resembling an arbitrary residential housing. The peak pressure and impulse density were compared with each other in order to understand what parameters and embankment geometry affected the mitigation. The results was also compared with empirical expressions for reduction in reflected pressure and impulse density when a vertical barrier is present. This was done in order to verify the reliability of the use of these empirical expression. The results showcased that an explosion occurring close to the embankment and an embankment that was taller resulted in increased reduction for both reflected pressure and impulse density. However, the effect of these parameters diminished with increased standoff distance, and scaled distance from explosion to the structure located behind the embankment. The chosen embankment type also had an effect on blast mitigation. An embankment resembling a vertical barrier instead of a typical embankment with two slopes on each of its sides, gave better mitigation in all cases that were tested. The embankment resembling a vertical barrier also showed results more in line with the empirical expressions for reduction in reflected pressure and impulse density.
Characterization of explosion pressure waves behind embankments
No full textThe increasing urbanization in the world leads to new risks and consequences of an explosion. One possible blast-mitigation procedure is the use of protective embankments. Today, there is a lack of updated standardization and guidelines for the design and effect of such embankments. The aim of this thesis is to investigatethe blast mitigation of different embankment designs to deepen the understanding of how the pressure wave from an explosion will behave after it has interacted withthe embankment. Numerical Computational Fluid Dynamics (CFD) simulations were conducted to study the effect of different embankment designs. Several studies where the results were compared against previous experiments and empirical relations was conducted in order to calibrate the model used. For the subsequent parametric study of the embankment design, two main parameters were studied; the distance of the embankment to the explosive charge, and the height of the embankment. Different combinations of these parameters with different wall types resulted in 68 simulations. The reflected peak pressure and impulse density were extracted from a target behind the embankment with dimensions resembling an arbitrary residential housing. The peak pressure and impulse density were compared with each other in order to understand what parameters and embankment geometry affected the mitigation. The results was also compared with empirical expressions for reduction in reflected pressure and impulse density when a vertical barrier is present. This was done in order to verify the reliability of the use of these empirical expression. The results showcased that an explosion occurring close to the embankment and an embankment that was taller resulted in increased reduction for both reflected pressure and impulse density. However, the effect of these parameters diminished with increased standoff distance, and scaled distance from explosion to the structure located behind the embankment. The chosen embankment type also had an effect on blast mitigation. An embankment resembling a vertical barrier instead of a typical embankment with two slopes on each of its sides, gave better mitigation in all cases that were tested. The embankment resembling a vertical barrier also showed results more in line with the empirical expressions for reduction in reflected pressure and impulse density.
Parametric design and its role in the early stages of a construction project, as well as the role of the designer in its ecosystem
No full textI byggbranschen har Building Information Modeling (BIM) tillämpats allt mer de senaste åren. Projektering rör sig mot 3D-modellering istället för traditionella 2D-ritningar, och nästa steg kan vara att ha flera versioner av samma modell i en enda fil. Detta är möjligt genom användning av parametrisk design. Program som Grasshopper kan användas för modellering, där användarna enkelt kan ändra sina ingångsvärden och modellens dimensioner och förutsättningar ändras därefter.Computational design (CD) kan anses vara nästa steg, där kombinationer av både modellering och beräkning kan göras. Design med Computer-Aided Design (CAD) är manuellt, vilket innebär att antalet möjligheter som kan övervägas är begränsade. Computational design använder både algoritmer och parametrar för att skapa en design eller modell, vilket möjliggör att ursprungliga ingångsvärden kan ändras och att det skapas oändligt många versioner av en modell utan att behöva börja om själva modellen.Under utbildningen Högskoleingenjör byggteknik och design på KTH, har parametrisk design använts, samt att beräkningar ur konstruktionssyfte har skapats med hjälp av Finite Element Analysis (FEA). Parametrisk design och FEA har däremot inte kombinerats. Det finns stor potential att effektivisera arbetet genom att enkelt kunna ändra dimensioner i modellen och se resultat direkt i beräkningsprogram. Detta kan göra det mer funktionell för konstruktören. Denna metod är inte vanligt inom byggbranschen, och det kan vara användbart för både konstruktörer och projektörer i branschen.Tyréns, liksom andra konsultföretag, strävar efter att bli mer CD-orienterad. För närvarande finns det ett nätverk för att sprida kompetens och inspirera till användning av CD, där de deltar i lunchföreläsningar, delar med sig relevanta artiklar och kurser. Användningen av parametriska verktyg varierar dock mellan olika avdelningar, med en relativt stor grupp av konstruktörer som använder Grasshopper inom hus-konstruktionsavdelningen, medan bara några få använder det inom bro-avdelningen.In the construction industry, Building Information Modeling (BIM) has been increasingly applied in recent years. Design is moving towards 3D modeling instead of traditional 2D drawings, and the next step could be to have several versions of the same model in a single file, enabled by the use of parametric design. Programs such as Grasshopper can be used for modeling, where users can easily change their input values, and the model's dimensions and conditions change almost instantly.Computational design (CD) could be considered the next step, as combinations of both modeling and calculation can be made. Design with Computer-Aided Design (CAD) is manual, which means that the number of possibilities that can be considered is limited. Computational design uses both algorithms and parameters to create a design or model, allowing the original input values to be changed, which creates endless versions of a model without starting over with the actual model.During education, parametric design has been used, as well as creating loads using Finite Element Analysis (FEA), but they have so far not been combined. There is great potential to streamline the work by easily changing the dimensions of the model to make it more functional for the designer. This is not common in the construction industry, and it can be useful for the designer/project manager in the industry.Tyréns, like other consulting firms, is striving to become more CD-oriented. There is currently a network to spread competence and inspire the use of CD, where they participate in lunch lectures, relevant articles, and courses. However, the use of parametric tools varies among different departments, with a relatively large group of designers using Grasshopper in the building design department, while only a few use it in the bridge department
Parametric design and its role in the early stages of a construction project, as well as the role of the designer in its ecosystem
No full textI byggbranschen har Building Information Modeling (BIM) tillämpats allt mer de senaste åren. Projektering rör sig mot 3D-modellering istället för traditionella 2D-ritningar, och nästa steg kan vara att ha flera versioner av samma modell i en enda fil. Detta är möjligt genom användning av parametrisk design. Program som Grasshopper kan användas för modellering, där användarna enkelt kan ändra sina ingångsvärden och modellens dimensioner och förutsättningar ändras därefter.Computational design (CD) kan anses vara nästa steg, där kombinationer av både modellering och beräkning kan göras. Design med Computer-Aided Design (CAD) är manuellt, vilket innebär att antalet möjligheter som kan övervägas är begränsade. Computational design använder både algoritmer och parametrar för att skapa en design eller modell, vilket möjliggör att ursprungliga ingångsvärden kan ändras och att det skapas oändligt många versioner av en modell utan att behöva börja om själva modellen.Under utbildningen Högskoleingenjör byggteknik och design på KTH, har parametrisk design använts, samt att beräkningar ur konstruktionssyfte har skapats med hjälp av Finite Element Analysis (FEA). Parametrisk design och FEA har däremot inte kombinerats. Det finns stor potential att effektivisera arbetet genom att enkelt kunna ändra dimensioner i modellen och se resultat direkt i beräkningsprogram. Detta kan göra det mer funktionell för konstruktören. Denna metod är inte vanligt inom byggbranschen, och det kan vara användbart för både konstruktörer och projektörer i branschen.Tyréns, liksom andra konsultföretag, strävar efter att bli mer CD-orienterad. För närvarande finns det ett nätverk för att sprida kompetens och inspirera till användning av CD, där de deltar i lunchföreläsningar, delar med sig relevanta artiklar och kurser. Användningen av parametriska verktyg varierar dock mellan olika avdelningar, med en relativt stor grupp av konstruktörer som använder Grasshopper inom hus-konstruktionsavdelningen, medan bara några få använder det inom bro-avdelningen.In the construction industry, Building Information Modeling (BIM) has been increasingly applied in recent years. Design is moving towards 3D modeling instead of traditional 2D drawings, and the next step could be to have several versions of the same model in a single file, enabled by the use of parametric design. Programs such as Grasshopper can be used for modeling, where users can easily change their input values, and the model's dimensions and conditions change almost instantly.Computational design (CD) could be considered the next step, as combinations of both modeling and calculation can be made. Design with Computer-Aided Design (CAD) is manual, which means that the number of possibilities that can be considered is limited. Computational design uses both algorithms and parameters to create a design or model, allowing the original input values to be changed, which creates endless versions of a model without starting over with the actual model.During education, parametric design has been used, as well as creating loads using Finite Element Analysis (FEA), but they have so far not been combined. There is great potential to streamline the work by easily changing the dimensions of the model to make it more functional for the designer. This is not common in the construction industry, and it can be useful for the designer/project manager in the industry.Tyréns, like other consulting firms, is striving to become more CD-oriented. There is currently a network to spread competence and inspire the use of CD, where they participate in lunch lectures, relevant articles, and courses. However, the use of parametric tools varies among different departments, with a relatively large group of designers using Grasshopper in the building design department, while only a few use it in the bridge department
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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