1,721,237 research outputs found
An Area-Efficient Variable-Size Fixed-Point DCT Architecture for HEVC Encoding
Full text linkThis paper proposes an area-efficient fixed-point architecture for the computation of the discrete cosine transform (DCT) of multiple sizes in high efficiency video coding (HEVC). This result is obtained by comparing different DCT factorizations in order to find the most suitable one for implementation in the HEVC encoder. The recursive structure of fast algorithms, which decompose the N-point DCT by means of two N/2-point DCTs, is exploited to execute computations of small-size DCTs in parallel, thus maximizing the hardware reusability while maintaining a constant throughput. The simulation results prove that the proposed solution features reduced rate-distortion losses, with relevant complexity saving compared with the state-of-the-art implementations. Finally, the proposed architecture is exploited to design two families of architectures for the 2D-DCT, namely, folded and full-parallel
Decision Support for existing buildings: An LCC-based proposal for facade retrofitting technological choices
Full text linkThe goal of this paper is to present a usable and effective tool to evaluate residential façade retrofitting solutions in early stages of design, keeping into account envelope features and installation issues. Decarbonisation goals set for 2050 impose existing building stock renovation and energy retrofit. Several drivers are available in EU Countries to trigger these operations. Nonetheless, the renovation rate in EU Member States remains low: barriers to building retrofit are identified, and a main issue in this sense is the lack of use of Decision Support Systems. DSS exist but are often neglected by building designers or owners, due to different reasons. Existing methodologies do not take into account the quantity and quality of information available at the various stages of building life cycle; furthermore, they mainly focus on energy related aspects, neglecting technological and installation related factors. This paper aims at providing an LCC-based decision framework to help decision makers in early stages of design to choose the most suitable technology for building façade retrofitting. A Utility Function expressing LCC for residential building renovation is provided, focusing on façades renovation and on installation and morphology related aspects. Information and data flow through the phases is presented and discussed, showing how the proposed method can be adapted to different stages, and testing its robustness through sensitivity and uncertainty analyses. Three main categories of renovation technologies are analysed (ventilated façade, ETICS, and prefabricated solutions). The proposed method is applied to a residential case study building. The adaptability of the tool to different stages of design is discussed, and further potential applications are presented
Methodologies for assessing building embodied carbon in a circular economy perspective
Full text linkThe global warming effect represents an increasingly severe environmental issue in the contemporary world, with the construction industry contributing up to 40% of greenhouse gas emissions. Therefore, as advancements in technology have enabled the realization of net-zero energy buildings, there has recently been a growing focus on research primarily aimed at reducing the embodied carbon (EC) of building materials. Assessment and calculation of EC emissions in buildings typically utilize life cycle assessment (LCA) methodologies, evaluating both direct and indirect carbon emissions throughout all stages, from raw material extraction to end-of-life demolition. However, the substantial potential of carbon reduction within the material beyond life cycle stage in the building, which is the decisive process of closing the loop of circular economy, is often overlooked. This paper examines a large number of research cases on EC in buildings over the past 20 years, selectively identifying those including the benefits beyond life cycle of buildings. By conducting a case-by-case analysis of methods and tools employed for the assessment of circular practices, their respective strengths, weaknesses, and variances are evaluated. Following the normalization of EC in phase A-D, a significant research finding revealing that buildings can offset an average of -113.9 kg CO2e/m2 of carbon emissions through recycling and reuse in phase D, accounting for 16.85% of the total EC assessed in LCA. Steel recycling offsets the highest amount of carbon emissions, with an average number of -183.86 kg CO2e/m2. The objective of this paper is to identify the key factors that influence carbon emissions in the circular economy and to identify methods and tools for integrating building materials at the early design stage to minimize EC emissions throughout the entire lifecycle of buildings
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
Gli involucri sensibili: progetto e costruzione di pareti ventilate ad inerzia variabile
No full textUse of 3D tessellation in curtain wall facades to improve visual comfort and energy production in buildings
Full text linkIn the vast majority of new buildings, energy and comfort requirements are met mostly by active systems that are often expensive, energy intensive, and complex to maintain. At the same time, advances in the use of digital tools for the design and fabrication of unitised curtain wall systems have substantially reduced the costs associated to non-planar surfaces in building envelopes. As a result, buildings deploy an increasing level of surface geometry articulation that is mostly used for decorative effects. By and large, the flourishing of a new formal vocabulary, enabled by digital tools, rarely translated into buildings that perform better. The research proposes the use of non-planar surface geometries for precise calibration in tilt angle and orientation of individual panels in curtain walls, as an effective passive design strategy. The goal is to improve visual comfort for users, limiting potential glare without the use of shading or blinds and, at the same time, to provide high potential for PV production without negatively affecting daylighting levels in the building interiors. The study explores four families of three-dimensional geometries, based on size limitations and other design constraints typically associated to unitized curtain wall systems. The investigation takes into account aspects such as local climate data, orientation, glass properties, morphology of the façade unit, indoor visual comfort, energy efficiency and energy production. Results show that all four families can be optimised to meet LEED requirements of sDA > 50% and ASE < 10% in office buildings, delivering better performances when compared to a flat facade
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