1,721,004 research outputs found
Characterisation of the hygric inertia of a room for a reliable prediction of interior humidity variations
No full textIn existing building simulation tools two methods can typically be found to account for the moisture buffer effect of porous materials as claddings, furniture, etc. when solving the moisture balance of a building zone. In the first method, often called effective capacitance model, the buffer effect of adsorptive materials is solved within the moisture balance of the room by correcting the moisture capacity of the indoor air. This is a very easy method, but most of the time no guidelines are found for the correction factor. The second model, mostly referred to as buffer storage model, calculates the moisture storage in the sorptive material separately. This can be done in a simplified way, as in the effective moisture penetration depth models, or in a more precise way, really solving the moisture storage and flow in the material with a finite element or control volume method. Though more precise, the buffer storage model has the disadvantage that it is hardly applicable on furnishing, often the most important buffer capacity in the room. The present paper proposes an easy but reliable characterisation of the hygric inertia of a building zone, taking into account claddings, furnishing and even books etc. resulting in a reliable prediction of the interior humidity variations. In the first part of the present study, the hygric inertia of a room (HIR) is characterised as a function of the moisture buffer potential (MBP) of the finishing materials and furniture in the room. The MBP is derived similar to the prescriptions in the Nordtest-protocol [1], but to account for the different time schedules of moisture loads, a weighted average between a short term and long term moisture buffer potential value as proposed in the companion paper [2] is used. The validity of the proposed expression is studied numeri-cally, by simulating the dynamic response of a room with combinations of different cladding materials and furnishing. It is shown that the hygric inertia of an entire room can be determined from its different contrib-uting components, independent of the boundary conditions considered. An appreciable unique relationship between the dampening of the interior RH-variations and the HIR-value of the building zone is found. The second part of the paper focuses on the quantitative prediction of moisture buffering in building zones. Two methodologies are applied. In the first, the HIR-model is implemented into the moisture balance for a building zone by adding the hygric inertia of the room to the moisture capacity of the zone air. This corre-sponds to the simple moisture capacitance model, but now a reliable prediction of the effective moisture capacitance of the zone can be deduced. The second methodology uses the buffer storage model. By taking into account the short term and long term HIR-value, the hygric inertia of the whole room can be transformed into an equivalent moisture storage layer as implemented in the TRNSYS and Clim2000-codes. Numerical simulations show that both methodologies can be used as simple tools to assess the dampening of indoor humidity variations but that the second methodology gives a more reliable prediction of the RH-course with time. [1] Rode C, Peuhkuri R, Time B, Svennberg K, Ojanen T. Moisture buffer value of building materials. Journal of ASTM International 2007: 4(5). [2] Janssen H, Roels S. The dependable characterisation of the moisture buffer potential of interior clad-dings. Paper submitted for Nordic Symposium on Building Physics 2008.Presenters:
name: staf roels
affiliation: (Laboratory of Building Physics, K.U.LEUVEN)
email: [email protected]
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
On site thermal performance characterization of building envelopes: How important are heat exchanges with neighbouring zones
No full textThe dependable characterisation of the moisture buffer potential of interior claddings
No full textThe influences of interior humidity on the performance of building zones, building parts and building occu¬pants are strongly multifaceted and highly interrelated. The levels of interior humidity substantially influence the energy performance of a building zone, via the latent cooling and transmission loads, the appearance and stability of a building part, via the biological activity of moulds and fungi, and the health and comfort of a building occupant. For all these reasons and more, (some) control over the interior humidity levels is often desired. Such control can be maintained with active measures like HVAC, but recently the focus has shifted to the passive contributions of the interior enclosure's hygric inertia. While whole-building simulations or full-scale measurements may be applied to assess such contributions, these are expensive, both time and cost wise, and a simplified methodology is thus required. Such simplified methodology is presented in this paper and its companion paper [1]: this paper examines the dependable characterisation of the moisture buffer capacity (MBP) of single claddings, while the companion paper focuses on its generalisation towards entire room enclosures and its application for quantification of interior humidity variations. Recently numerous proposals for the MBP characterisation of single claddings or finishing materials have been suggested. It will be shown that cyclic-step-change-(de)sorption based methods, as proposed in the Japanese Industrial Standard A 1470-1, the Draft International Standard 24353, and the Nordtest Moisture Buffer Value protocol [2], are most promising. The three proposals do though comprise different prescriptions for the cyclic (de)sorption measurements, and an analysis of their influence on the MBP characterisation is executed. To that goal, a numerical study of cyclic (de)sorption of seven different materials is presented. Finally, it is shown that the resulting MBP characterisation indeed yields a dependable characterisation, by relating the MBP values to the dynamic response of a small room with each of the materials used in turns as finishing material. It is shown that an appreciably unique relation between the MBP and the dampening of the interior humidity variations – taken as measure for the moisture buffering effect by the cladding – exists, but only if there is a close agreement between the loading protocol used for the MBP determination and the production protocol applied in the room simulation. To account for the multitude of different real production protocols, the weighted average between a short term and long term MBP value is shown to be generally applicable. In the companion paper, the presented MBP characterisation will be shown generalisable to the room level. The resulting room hygric inertia will finally be demonstrated to be applicable for the approximate quantifica-tion of interior humidity variations by simplified means. [1] Roels S, Janssen H: Characterisation of the hygric inertia of a room for a reliable prediction of interior humidity variations. Paper submitted for Nordic Symposium on Building Physics 2008. [2] Rode C, Peuhkuri R, Time B, Svennberg K, Ojanen T: Moisture buffer value of building materials. Journal of ASTM International 2007: 4(5).Presenters:
name: Hans Janssen
affiliation: (Department of Civil Engineering, Technical University of Denmark)
email: [email protected]
Airflow effects on the hygrothermal behaviour of lightweight wall structures
No full textSeveral research projects have already indicated the importance of airflow and air leakage when considering hygrothermal responses of building components. In order to study the influence of airflow on the hygrothermal behaviour of lightweight wall structures, a test-setup has been constructed at the K.U.Leuven Vliet test building. A terraced house has been built up. First measurements are carried out on the ground level part. The test-setup has two outer walls. The SW-wall is a cavity wall with a plaster finish on the inside. The NE-wall consists of three separate wall-sections, each with different air tightness. Measurements are carried out on the NE-walls, in order to evaluate the influence of air tightness on the thermal and hygric performance of the walls. These walls are subjected to an exfiltration airflow and thus have a higher risk of internal moisture problems. Variations in the test-setup are made by adding extra infiltration and exfiltration openings, thereby influencing the airflow pattern in the test-house and the NE-walls. Furthermore the impact of minor perforations, imperfections in construction but also the influence of wind speed and wind direction are studied.Presenters:
name: Joachim Verhaeghen
affiliation: (/)
email: [email protected]
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
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