1,720,964 research outputs found
Trnsys integrated modeling support tool for a fast building-plant system design
Full text linkThe present thesis stems from the benefits of the application of energy analysis in any stage of building-plant system design. The research highlights the barriers that prevent this integration and finally proposes the development of a dynamic modeling support tool able to simulate, with a reasonable workload, a very large number of integrated building-plant systems with different scales and resolutions, in order to have a guided design support for architects and HVAC designers/engineers, reducing their modeling effort and errors. The starting point is represented by a flexible and detailed model created with the calculation engine TRNSYS, which allow for the dynamic and integrated simulation of the building envelope, all the heating plant subsystems, and all the plant components related to the production of domestic hot water.
The research explores then strategies and simplifications that can considerably reduce the number of necessary inputs for the simulations, thus minimizing the modeling, implementation and simulation runtime of the model, while still maintaining an acceptable degree of accuracy with respect to the computational results and real energy consumptions. Those results are achieved by defining a methodology, which consists in developing a sizing protocol and a simplification protocol and applying them to real life, complex case studies, first modeling detailed models and progressively enhancing the level of simplification. At each progressive simplification step, the comparison with the detailed model results is given in terms of building energy needs, power curves, efficiencies, modeling and simulation workloads. In particular results show that the accuracy of the most simplified model is always below the 16% with respect to the most detailed model, with a 90% modeling and simulation workload reductions, able to make the tool easy to be adopted at every stage of building-plant system design
Stationary and Transient Heat Conduction in Multilayer Non-Homogeneous Stratigraphy
Full text linkAbstractThe tendency to speed up the building process and reduce its capital costs is bringing to the increased use of semi-finished products in constructions. One frequent characteristic of those elements is the use of non-homogeneous layers of materials, possibly affecting their thermal properties. In addition to this, the gradual increase in the thickness of insulation layers in buildings is also shifting the focus from the heating loads to the cooling loads, especially for hot climates such as southern Europe, raising the necessity to evaluate the transient properties of construction elements, alongside with the most common stationary properties. The aim of this paper is to correctly evaluate both stationary and transient heat conduction properties of strongly non-homogeneous multi-layered constructions and evaluate the impact of the non-homogeneities. The evaluation of those properties are based on the definitions detailed in the EN ISO 13786 directive, for dynamic thermal characteristics, and in the EN ISO 6946 directive, for stationary thermal characteristics. The stationary thermal transmittance is the parameter considered for the stationary analyses; for transient analyses transient thermal transmittance, time shift and attenuation factor are evaluated. The methodology provided inside the respective directives is applied in order to estimate the parameters. Following, a finite elements model is implemented in the COMSOL Multiphysics software and the same properties are calculated through a finite element analysis performed based on the conditions detailed in the physical definitions of those properties in the respective directives. Each parameter assessed based on the respective directives, EN ISO 13786 and EN ISO 6946, is then compared with the results of the finite elements analyses. Based on those comparisons the impact of the non-homogeneities in the construction for the calculation of its thermal properties are evaluated and conclusions on their relevance in the identification of the thermal properties are given, also the ability of describing non- homogeneous constructions through the directive's methodology is discussed
Rapid Exploitation of Building Energy Design Through Compact TRNSYS Modeling
No full textThis paper presents the development of a new modeling support tool able to simulate, with a reasonable workload, 36 integrated building-plant systems with different scales and resolutions, in order to support architects and HVAC designers/engineers in their modeling efforts, providing them with an extremely flexible, guided and accurate tool which does not require specific expertise during its use. The starting point is represented by a detailed model created with the calculation engine TRNSYS, which allows for dynamic and integrated simulation of the building envelope, heating plant subsystems, and plant components related to the production of the domestic hot water. The paper explores the strategies and simplifications that can considerably reduce the number of necessary inputs for the simulations, thus minimizing the modeling, implementation and simulation runtime of the model, still maintaining a very high degree of accuracy with respect to the computational results and real energy consumptions. The protocols are applied to different case studies, first for the detailed modeling and progressively enhancing the level of simplification. The results show that the accuracy of the most simplified model in terms of heating loads and efficiencies is always below 16% with respect to the most detailed model, but with up to 90% modeling and simulation workload reductions. In this way the dynamic simulations could become an everyday working tool, with a greater amount of outputs in order to avoid plant oversizing and design errors
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
Full text linkWe 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
Full text linkWe 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
- …
