The seismic assessment of unreinforced masonry (URM) buildings with cavity walls is of high relevance in regions such as in Central and Northern Europe, Australia, New Zealand and China because of the characteristics of the masonry building stock. A cavity wall consists of two separate parallel walls usually connected by metal ties. Cavity walls are particularly vulnerable to earthquakes, as the out-of-plane capacity of each individual leaf is significantly smaller than the one of an equivalent solid wall. This paper presents the results of an experimental campaign conducted by the authors on metal wall tie connections and proposes a mechanical model to predict the cyclic behaviour of these connections. The model has been calibrated by us- ing the experimental results in terms of observed failure modes and force-displacement responses. Results are also presented in statistical format.
BackgroundMechanical ventilation affects the respiratory muscles, but little is known about long-term recovery of respiratory muscle weakness (RMW) and potential associations with physical functioning in survivors of critical illness. The aim of this study was to investigate the course of recovery of RMW and its association with functional outcomes in patients who received mechanical ventilation.MethodsWe conducted a prospective cohort study with 6-month follow-up among survivors of critical illness who received ≥ 48 hours of invasive mechanical ventilation. Primary outcomes, measured at 3 timepoints, were maximal inspiratory and expiratory pressures (MIP/MEP). Secondary outcomes were functional exercise capacity (FEC) and handgrip strength (HGS). Longitudinal changes in outcomes and potential associations between MIP/MEP, predictor variables, and secondary outcomes were investigated through linear mixed model analysis.ResultsA total of 59 participants (male: 64%, median age [IQR]: 62 [53–66]) were included in this study with a median (IQR) ICU and hospital length of stay of 11 (8–21) and 35 (21–52) days respectively. While all measures were well below predicted values at hospital discharge (MIP: 68.4%, MEP 76.0%, HGS 73.3% of predicted and FEC 54.8 steps/2m), significant 6-month recovery was seen for all outcomes. Multivariate analyses showed longitudinal associations between older age and decreased MIP and FEC, and longer hospital length of stay and decreased MIP and HGS outcomes. In crude models, significant, longitudinal associations were found between MIP/MEP and FEC and HGS outcomes. While these associations remained in most adjusted models, an interaction effect was observed for sex.ConclusionRMW was observed directly after hospital discharge while 6-month recovery to predicted values was noted for all outcomes. Longitudinal associations were found between MIP and MEP and more commonly used measures for physical functioning, highlighting the need for continued assessment of respiratory muscle strength in deconditioned patients who are discharged from ICU. The potential of targeted training extending beyond ICU and hospital discharge should be further explored.
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An important step towards improving performance while reducing weight and maintenance needs is the integration of composite materials into mechanical and aerospace engineering. This subject explores the many aspects of composite application, from basic material characterization to state-of-the-art advances in manufacturing and design processes. The major goal is to present the most recent developments in composite science and technology while highlighting their critical significance in the industrial sector—most notably in the wind energy, automotive, aerospace, and marine domains. The foundation of this investigation is material characterization, which offers insights into the mechanical, chemical, and physical characteristics that determine composite performance. The papers in this collection discuss the difficulties of gaining an in-depth understanding of composites, which is necessary to maximize their overall performance and design. The collection of articles within this topic addresses the challenges of achieving a profound understanding of composites, which is essential for optimizing design and overall functionality. This includes the application of complicated material modeling together with cutting-edge simulation tools that integrate multiscale methods and multiphysics, the creation of novel characterization techniques, and the integration of nanotechnology and additive manufacturing. This topic offers a detailed overview of the current state and future directions of composite research, covering experimental studies, theoretical evaluations, and numerical simulations. This subject provides a platform for interdisciplinary cooperation and creativity in everything from the processing and testing of innovative composite structures to the inspection and repair procedures. In order to support the development of more effective, durable, and sustainable materials for the mechanical and aerospace engineering industries, we seek to promote a greater understanding of composites.
The postdoc candidate, Giuliana Scuderi, will strengthen the connection between the research group Biobased Buildings (BB), (collaboration between Avans University of Applied Sciences and HZ University of Applied Sciences (HZ), and the Civil Engineering bachelor programme (CE) of HZ. The proposed research aims at deepening the knowledge about the mechanical properties of biobased materials for the application in the structural and infrastructural sectors. The research is relevant for the professional field, which is looking for safe and sustainable alternatives to traditional building materials (such as lignin asphalt, biobased panels for bridge constructions, etc.). The study of the mechanical behaviour of traditional materials (such as concrete and steel) is already part of the CE curriculum, but the ambition of this postdoc is that also BB principles are applied and visible. Therefore, from the first year of the programme, the postdoc will develop a biobased material science line and will facilitate applied research experiences for students, in collaboration with engineering and architectural companies, material producers and governmental bodies. Consequently, a new generation of environmentally sensitive civil engineers could be trained, as the labour market requires. The subject is broad and relevant for the future of our built environment, with possible connections with other fields of study, such as Architecture, Engineering, Economics and Chemistry. The project is also relevant for the National Science Agenda (NWA), being a crossover between the routes “Materialen – Made in Holland” and “Circulaire economie en grondstoffenefficiëntie”. The final products will be ready-to-use guidelines for the applications of biobased materials, a portfolio of applications and examples, and a new continuous learning line about biobased material science within the CE curriculum. The postdoc will be mentored and supervised by the Lector of the research group and by the study programme coordinator. The personnel policy and job function series of HZ facilitates the development opportunity.
Recent research by the renowned Royal Institution of Chartered Surveyors (RICS) shows that more than 2/3 of all CO2 is emitted during the building process and less than 1/3 during use to heat the building and the tap water. Lightweight, local and biobased materials such as biocomposites to replace concrete and fossil based cladding are in the framework of climate change, a necessity for future building. Using plant fiber in polymer composites is especially interesting for construction since natural fibers exhibit comparative good mechanical properties with small specific weight, which defines the potential for lightweight constructions. The use of renewable resources, will affect the ecosystem favorably and the production costs of construction materials could also decrease. However, one disadvantage of natural fibers in plastics is their hydrophilic properties. In construction the materials need to meet special requirements like the resistance against fluctuating weather conditions (Ticoalu et al., 2010). In contrast to synthetic fibers, the natural ones are more moisture- and UV-radiation-sensitive. That may lead to degradation of these materials and a decreasing in quality of products. (Lopez et al., 2006; Mokhothu und John, 2017) Tanatex and NPSP have approached CoE BBE/Avans to assist in a study where fibres impregnated with the (modified) Tanatex products will be used for reinforcement of thermoset biopolymers. The influence of the different Tanatex products on the moisture absorption of natural/cellulosic fibers and the adhesion on the fibers on main composite matrix will be measured. The effect of Tantex products can optimize the bonding reaction between the resin and the fibers in the (bio) composite and result to improved strength and physico-chemical properties of the biocomposite materials. (word count: 270)
To decrease the environmental impact caused by the construction sector, biobased materials need to be further developed to allow better integration and acceptance in the market. Mycelium composites are innovative products, with intrinsic properties which rise the attention of architects, designers and industrial companies. Until now, research has focused on the mechanical properties of mycelium products. The aim has been improving their mechanical strength, to achieve wider application in the construction sector. Alongside this, to introduce mycelium composites to a wider market, the aesthetic experience of the public also needs to be considered. In the context of this proposal, it is argued that users of biobased products can shift their attitudes towards their surroundings by adjusting to the visual aesthetics within their environment or products they surround themselves with (Hekkert, 1997). This can be further attributed to colours which can be experienced as warm or cold, aggressive or inviting, leading to experiences that may include pleasure or displeasure indicating the future success of the bio based product. Mycelium composites can be used as building materials, but also as interior design materials, therefore visible to its user. It is to determine the appropriate methodologies to confer colour to mycelium composites that the companies Impershield and Dorable came together to form the consortium for the present project. The investigated ways are: 1. Through the preliminary colouring of fibres and their use as substrate for mycelium growth 2. The surface treatment of the final product. The Centre of Expertise BioBased Economy (CoEBBE) and the Centre of Applied Research for Art and Design (CARADT) will be guiding the research through their experience with mycelium composites. This project will lay the basis to enhance visual appearance of mycelium composites, with the utilization of natural pigments, natural paints and coatings.
