1,721,137 research outputs found
A probabilistic-based methodology for evaluation of timber facade constructions - The Performance to withstand biodeterioration
Full text linkMould and decay are biodeterioration phenomena that jeopardize the integrity, functionality and durability of timber façade constructions. Accounting for them during the design stage is crucial for the prevention of social problems and financial loss, and to ensure a healthy, safe and comfortable interior environment. The design of façade constructions is replete with uncertainties. They are mainly related to the representation of the outdoor and indoor climate, physical parameters of the materials properties and geometries, and modelling of complex physical phenomena. Current design approaches fail to account for these uncertainties, especially in representing the outdoor climate and microbial growth. The aim of this work is to develop and apply a probabilistic-based methodology, which evaluates the performance of timber façade constructions to withstand biodeterioration and accounts for the involved uncertainties. The time series analysis according to autoregressive-moving-average models is applied to develop the stochastic model representing the outdoor climate. This technique identifies mathematical expressions that can generate probable patterns of the weather data in a time series containing plausible sequences, frequencies and correlations, future trends of the climate and can be long enough to resemble the expected service life. The temperature-dependent thermal conductivity of the insulation material is investigated by carrying out lab measurements, and subsequently, a stochastic model is developed to represent this property. Deficiencies, considering penetration of wind-driven rain, are accounted for and represented by different moisture sources. Moreover, the development of criteria and models representing mould growth in wood-based materials are investigated by carrying out a systematic literature review. Subsequently, three mould models are selected to derive the mould growth outcome as a mixture of their distribution to account for their competencies and diminishing their limitations in representing mould. This outline derives the likelihoods of potential levels of mould growth; hence, facilitates their association to the corresponding consequences adapted from the case study at hand. Uncertainty and sensitivity analysis methods are performed to quantify the ranges of the output, the likelihood of each outcome and to evaluate the significance of key contributors to output uncertainty. The methodology is applied to evaluate traditional and modern façade constructions. The results prove that the probabilistic-based methodology enables a more systematic approach to the evaluation of façade constructions. It accounts for the involved uncertainties, provides a clear association of microbial growth and its likelihood, and enables the identification and significance of the dominant parameters; hence, it delivers a more comprehensive representation to evaluate construction performance. The methodology can facilitate the development of cost-optimisation and risk-based inspection planning methodologies, and enable the upgrading of current codes and standards.
Keywords: mould; decay; façade; probabilistic; uncertainty; sensitivity analysis.Digital full text not availabl
Moisture performance of thermally insulated basement walls in cold climates
No full textClimate change entails frequent and intense events of heavy rainfall and rain-induced floods in many regions with cold climates. In addition, present solutions for stormwater management involve the infiltration of surface runoff into the ground surrounding the buildings. Although sufficient drainage normally prevents water pressure on the basement envelopes in new buildings, the basement envelope is still prone to high moisture strain in the form of high relative humidity (RH) in soil/backfill, precipitation/stormwater, and water from snowmelt.
The primary objective of this thesis has been to make novel contributions to the scientific knowledge regarding the effect of outward drying of thermally insulated concrete basement walls. Several scoping and desktop studies were conducted to map the extent of scientific research available. Furthermore, a novel experimental method that involved applying load cells to monitor the outward drying and precipitated condensation of concrete wall segments insulated with different configurations of thermal insulation and dimpled membranes was developed. In the experiment, the wall segments were exposed to warm interior and cold and humid exterior conditions in a climate simulator. Subsequently, numerical simulations were conducted using COMSOL Multiphysics®. The simulations were performed to investigate the concrete wall segments from the laboratory experiment and the long-term moisture performance of thermally insulated basement walls. The vapour permeability of the exterior thermal insulation, moisture performance of three types of concrete, effect of two dimpled membrane positions, and effect of interior vapour barriers were investigated.
The literature reviews and desktop studies provided an overview of the international recommendations for thermally insulated basements in cold-climate countries and studies focusing on the hygrothermal simulations of basement envelopes. Differences between the recommendations primarily pertained to the exterior damp proofing of the walls, use and position of dimpled membranes and vapour barriers, and use of vapour-permeable thermal insulation. Note that a method for the validation of the hygrothermal simulations of basements using full-scale physical measurements was not found in the literature. Therefore, it was concluded that a recognised method/procedure to determine the below-grade exterior boundary conditions is required. In the experimental study, the three basement wall segments exhibited similar drying rates. Thus, it was concluded that the outward drying was primarily limited by the concrete type and not the exterior thermal insulation or position of the dimpled membrane. This inference was validated by numerical simulations.
Using vapour-permeable thermal insulation on the exterior side of basement walls in dwellings might improve the moisture performance of the interior wall components; however, the effect of the insulation will primarily depend on the capillary moisture transfer of the concrete and the thickness and permeability of the exterior and interior insulation. If the concrete dries slowly, a dimpled membrane positioned between the concrete and exterior insulation might provide sufficient drying, assuming that the air gap behind the membrane is slightly ventilated. Therefore, the span of the moisture properties of concrete used in basements requires a thorough investigation
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
Implementing Climate Adaption in Building Moisture Safety Design
Full text linkClimate adaptation, both to assess local climate characteristics and to estimate future climate developments, pose increasingly significant challenges to the built environment. This has led to a growing focus on climate adaptation and acknowledgement of the need to address climate risks more explicitly, both from regulatory authorities such as the EU Taxonomy regulations for economic activities and from the research on climate adaptation of buildings. In Norway, substantial local climate variations raise buildings vulnerability to moisture-related damages, increasing risks associated with climate-related hazards if adaptation of building designs is not addressed properly. Significant efforts have been made in recent years to lower the risks associated with the acute risks related to floods, landslides and storm-water management. But the chronic risks associated with increased moisture damage to buildings, due to increased precipitation and changing precipitation patterns, have been less developed.
This thesis examines the implementation of climate adaptation into Building Moisture Safety Design (BMSD) in Norway, contextualizing its importance in light of growing climate risks and regulatory requirements. It evaluates current practices through literature reviews and case studies, identifies barriers through interviews with practitioners and document studies, and proposes a framework to improve adaptation measure implementation that aligns with the typical current BMSD workflows. The thesis aims to improve climate adaptation of BMSD for typical Norwegian building projects. The work is conducted through the research centre SFI Klima 2050, which aims to reduce societal risks associated with climate changes and enhanced precipitation and flood water exposure. Climate adaptation of buildings involves designing structures that can withstand both locally specific and future anticipated climate stresses.
Climate adaptation in BMSD requires an operational shift towards explicitly addressing uncertainty and integrating future climate loads into design practices. By using tools like climate indices coupled with robust uncertainty communication, building physicists can efficiently make informed decisions based on risk assessments in a changing climate. Implementing the proposed framework requires alignment with current regulatory and industry practices. Tools like climate indices and recommendations based on index values should be increasingly integrated into existing guidelines such as SINTEF Building Research Design Guidelines (BRDG) to drive widespread adoption of climate adaptation frameworks. The findings in this work are specifically valuable for increased implementation of BMSD climate adaptation in a Norwegian context but are also relevant for other regions facing similar challenges
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
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