This paper discusses a novel, compact sound absorption solution with high performance at various frequencies, including low frequencies, achieved through the effective use of Computational Design and Additive Manufacturing (AM). Sound absorption is widely applied for reducing noise and improving room acoustics; however, it is often constrained by conventional design, material properties and production techniques, which offer limited options for customising performance. This research highlights that AM, in combination with computational design tools, can support the development of novel sound-absorbing products with high performance based on the principle of viscothermal wave propagation in prismatic tubes. The potential of these designs was explored via two studies of customised sound-absorbing panels whose performance was measured in a reverberation room. A custom measurement technique was used based on logarithmic sweeps with high-resolution FFT analysis. A comparison of the measurement results with the theory of viscothermal wave propagation indicated good agreement; thus, this study demonstrates the possibility of developing new concepts and design methods for novel room acoustic devices.@en

This paper focuses on the circular economy (CE), the building industry, and on the disruptive technological innovations that intersect in these arenas. It outlines how disruptive, often digital, technologies can potentially enable a CE in the building industry, primarily within the two most wasteful phases of the building cycle, the construction and demolition phases. This is achieved through an analysis of the potential of each technology type to enable a CE, using existing literature and desktop research on applied examples of the technological solutions in question. The paper aims to clarify the implementation scenarios of digital technologies for the circular building industry and are organised according to technology type, CE principle, building phase, material family, estimated TRL, and type of application.

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In recent years, natural disaster and military conflicts forced vast numbers of people to flee their home countries, contributing to the migration crisis we are facing today. According to the UNHCR, the number of forcibly displaced people worldwide reached the highest level since World War II. Post-disaster housing is by nature diverse and dynamic, having to satisfy unique socio-cultural and economical requirements. Currently, however, housing emergencies are tackled inefficiently. Post-disaster housing strategies are characterized by a high economic impact and waste production, and a low adaptability to location-based needs. As an outcome, low quality temporary shelters are provided, which often exceed by far their serving time. Focusing on temporary shelters suitable for the transitioning period between emergency accommodation and permanent housing, TERRA-ink addresses new construction methods that allow for time and cost efficiency, but also for flexibility to adapt to different contexts. TERRA-ink aims to develop a method for layering local soil, by implementing 3D printing technologies. With the aid of such a construction system, the goal is to create durable structures that can be easily de-constructed once they served their purpose. The use of locally sourced materials in combination with additive manufacturing is investigated aiming at reductions in financial investments, resources and human labor, as well as at simplified logistics, low environmental impact and adaptability to different situations and requirements. Such a building system has the potential of combining low-and high-tech technologies, in order to facilitate a fully open and universal solution for large scale 3D-printing using any type of soil.

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The possibility of using a mix of recycled polypropylene (PP) with new glass fibre reinforced polypropylene as a materials source for 3D printed engineering components is investigated. The strength and elongation to fracture are determined for various grades of material and in relation to the print direction. The measured values are compared with literature values for these materials in an as new condition. It is shown that the use of recycled PP degrades the material properties. PP recycled from house hold waste has significantly worse properties than PP recycled from industrial waste.@en