1,720,957 research outputs found
A physical model for the assessment of indoor environmental quality in buildings
No full textReducing energy consumption while providing the required air-change rate is one of the main scopes in the design of energy-efficient buildings, among which the superinsulated nearly Zero Energy Buildings (nZEB). However, high airtightness and other features (e.g., vapor barrier) may yield mold formation and hinder the removal of air pollutants, thus compromising indoor air quality. Understanding and managing these mechanisms can promote a healthier and more sustainable living and working environment. The conducted study is focused on devising and developing a predictive methodology for the evaluation of indoor air quality in compartments endowed with mechanical ventilation, with specific emphasis on risk factors for mold. A storage area located in a residential building served as a representative scenario, where significant environmental quantities (e.g., temperature, relative humidity, carbon dioxide and radon concentration) were monitored over a one-year timeframe. The proposed model successfully highlights the most critical conditions within actual buildings
A hybrid model for the assessment of indoor environmental quality in buildings: An insight into mold growth
No full textReducing energy consumption while providing the required air-change rate is one of the main scopes in the design of energy-efficient buildings, among which the superinsulated nearly Zero Energy Buildings (nZEB). However, high airtightness and other features (e.g., vapor barrier) may yield mold formation and hinder the removal of air pollutants, thus compromising indoor air quality. Understanding and managing these mechanisms can promote a healthier and more sustainable living and working environment. The conducted study was focused on devising and developing a predictive methodology for evaluating indoor air quality in compartments endowed with mechanical ventilation, with particular emphasis on mold risk factor. Towards assessing mold growth risk, a comprehensive approach was developed, integrating environmental telemetry data with Finite Element Method (FEM) simulations and a dedicated physical model. To the purpose, a storage area in a residential building was selected as a representative scenario, where key environmental parameters (e.g., temperature, relative humidity, pollutant concentration) were monitored over a one-year timeframe. The proposed model proved successful in highlighting the most critical conditions within actual buildings
A lumped-parameter model of a smart ventilation unit for Nearly Zero Energy Buildings
Get PDFIn the present work, a simple model of a ventilation unit used for residential purposes is proposed, which was developed by means of MATLAB Simulink and the Simscape toolbox, also including the Moist Air and Two-Phase fluid libraries. This study falls in the realm of air conditioning in nearly Zero Energy Buildings. The model presented here is focused mostly on the aeraulic system. A parametric analysis of various installation conditions was conducted to assess and enhance the combined heat pump and the air distribution system performance, under various operating conditions. Therefore, the overall approach included several parameters, such as outdoor and indoor air temperature, humidity, static pressure, pressure drop in the intake and the distribution ducts, and filter fouling. The model serves as a predictive tool to evaluate the effectiveness of the whole system, in both design and off-design conditions; notably, critical conditions are emphasized, which are associated to severe fouling conditions, making the use of an additional fan ineffective
An analytical model of evaporator performance under frosting conditions for lumped-parameter simulations of heat pumps
Get PDFEnhancing the energy efficiency of HVAC systems is crucial for meeting the nZEB standards. This involves developing analytical models for simulating building-system dynamics over time with low computational resources. However, existing models struggle with accuracy in heating mode due to evaporator frosting, a factor not usually accounted for commercial software. To address this, a new heat exchanger block that accurately models frosting and its impact on system performance is developed using the SimscapeTM language in Simulink ® environment. This innovative block enhances the predictive capability of heat-pump simulations that use a lumped-parameter approach, ensuring compatibility and easy integration with existing toolboxes. The improved model overcomes conventional limitations, offering reliable simulations in heating mode and providing insights into energy transport and efficiency. Incorporating accurate frosting representation aids in developing more effective defrost strategies, minimizing energy losses and improving compliance with energy efficiency standards
Comprehensive modeling of ventilation systems for Nearly Zero Energy Buildings
Get PDFIn the present work, a lumped-parameter model of a multifunctional ventilation unit for residential applications was developed in the Simulink environment, also relying on the Simscape toolbox with Moist Air and Two-phase fluid libraries. A simple, yet effective method to analyze and optimize the efficiency of the combined HVAC – air distribution system is proposed. To investigate the impact of boundary conditions on system performance, a parametric study of different installation conditions was also carried out, including outdoor air and indoor air temperature, humidity, static pressure, filter fouling, pressure drop in the intake and distribution ducts. The model highlights a strong decrease in the useful cooling/heating heat flow rate produced by the system as the installation and maintenance conditions become more challenging
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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