Search results for " construction"
showing 10 items of 1627 documents
Landfill gas upgrading with pilot-scale water scrubber: Performance assessment with absorption water recycling
2012
Abstract A pilot-scale counter current absorption process for upgrading municipal solid waste (MSW) landfill gas to produce vehicle fuel was studied using absorption, desorption and drying units and water as an absorbent. Continuous water recycling was used without adding new water to the system. The process parameters were defined by a previous study made with this pilot system. The effect of pressure (20–25 bar), temperature (10–25 °C) and water flow speed (5.5–11 l/min) on the upgrading performance, trace compounds (siloxanes, halogenated compounds) and water quality were investigated. Raw landfill gas flow was kept constant at 7.41 Nm3/h. Methane (CH4) and carbon dioxide (CO2) contents …
Promoting children’s participation: the role of teachers in preschool and primary school learning sessions
2010
The aim of this study is to provide insights into the social construction of participation in joint activities in Finnish preschool and primary school classrooms. The article deals with two issues: How do teachers promote participation in a preschool classroom as compared with a primary school classroom? What similarities and differences are found? It also considers the question of how the similarities contribute to the continuity from preschool to primary school in terms of participation. Based on observation data insights are provided into the interactions between teachers and children by using extracts from teacher‐led learning sessions. The teachers used a diversity of strategies to pro…
Feasibility of using more polishable aggregates in dense-graded asphalt surface mixture: Case study of dolomite
2022
This study aimed to evaluate the feasibility of using more dolomite aggregates in asphalt surface mixtures that are typically used by West Virginia Division of Highways (WVDOH). The laboratory test results indicated that increasing dolomite content in asphalt surface mixtures resulted in a faster deterioration rate at the early polishing stage. In addition, asphalt surface mixtures containing more than 50% dolomite coarse aggregates would significantly reduce roadway safety. The field test results validated that dolomite shall not exceed 50% of coarse aggregate in asphalt surface mixture if the projected traffic volume is greater than 3.0 million equivalent single axle loads (ESALs).
Technical Note: Prediction Models of Airborne Sound Insulation of Multilayer Materials with Viscoelastic Thin Sheets
2008
The growing introduction of new insulation materials in building acoustics has caused an increase of the importance of the prediction tools. Appropriate simulations allow strictly necessary laboratory measurements to be identified. In this way, costs are reduced. The demands of new legislation has resulted in the appearance of various software designed to facilitate prediction. The prediction models are based on different hypotheses: adaptation of impedances, spatial behaviour of spectral components, statistical energy distribution, the Finite Element Method (FEM), etc. Each of these models and methods offer advantages and contain limitations. In this paper, different models for prediction…
Tinkering with the two-to-one interview: Reflections on the use of two interviewers in qualitative constructionist inquiry
2021
Abstract Typically, qualitative interviews implicate a single interviewer. In this article, we consider an alternative comprising the simultaneous, active involvement of two interviewers. We base our considerations on experiences using the two-to-one interview in a nationwide research project on disability and physical activity. In addition to untapping and developing a qualitative interview method, the article provides an example in action of tinkering in qualitative inquiry. Tinkering entails a constant questioning of what to do, what is best, and what is appropriate within each moment of the research. Echoing social constructionist scholars, we argue that this flexible approach is useful…
Novel solutions for closed-loop Reverse Electrodialysis: thermodynamic characterisation and perspective analysis
2019
Abstract Closed-loop Reverse Electrodialysis is a novel technology to directly convert low-grade heat into electricity. It consists of a reverse electrodialysis (RED) unit where electricity is produced exploiting the salinity gradient between two salt-water solutions, coupled with a regeneration unit where waste-heat is used to treat the solutions exiting from the RED unit and restore their initial composition. One of the most important advantages of closed-loop systems compared to the open systems is the possibility to select ad-hoc salt solutions to achieve high efficiencies. Therefore, the properties of the salt solutions are essential to assess the performance of the energy generation a…
Nanotechnology and earth construction: the mechanical properties of adobe brick stabilized by Laponite nanoparticles
2014
The contribution describes the experimental analysis for the improvement of the mechanical properties of samples of earth with the addition of Laponite nanoparticles. Were made two types of samples: the first consisting of soil, sand and water; the second consisting of soil, water, sand and Laponite nanoparticles. The operations performed were: chemical analysis of soil and sand; preparation of samples; Scanning Electron Microscope (SEM) observation of samples for the distribution of the elements, especially the Laponite nanoparticles; testing of compression strength and flexural strength of two types of samples; comparisons of the resulted of the mechanical tests. The improvement of the me…
Evolution of lactase persistence: an example of human niche construction
2011
Niche construction is the process by which organisms construct important components of their local environment in ways that introduce novel selection pressures. Lactase persistence is one of the clearest examples of niche construction in humans. Lactase is the enzyme responsible for the digestion of the milk sugar lactose and its production decreases after the weaning phase in most mammals, including most humans. Some humans, however, continue to produce lactase throughout adulthood, a trait known as lactase persistence. In European populations, a single mutation (−13910*T) explains the distribution of the phenotype, whereas several mutations are associated with it in Africa and the Middle …
Effect of fall direction on the lower hip fracture risk in athletes with different loading histories : A finite element modeling study in multiple si…
2022
Physical loading makes bones stronger through structural adaptation. Finding effective modes of exercise to improve proximal femur strength has the potential to decrease hip fracture risk. Previous proximal femur finite element (FE) modeling studies have indicated that the loading history comprising impact exercises is associated with substantially higher fracture load. However, those results were limited only to one specified fall direction. It remains thus unclear whether exercise-induced higher fracture load depends on the fall direction. To address this, using magnetic resonance images of proximal femora from 91 female athletes (mean age 24.7 years with >8 years competitive career) and …
The guilty, the unlucky, or the unaware? Assessing self-reported behavioral contributors and attributions on pedestrian crashes through structural eq…
2020
Introduction: Recent literature suggests that the causation of pedestrians' crashes and the contribution of safety-related behaviors within them may substantially differ compared to other road users. This study aimed to test the effect of individual factors and safety-related road behaviors on the self-reported walk- ing crashes suffered by pedestrians and, complementarily, to analyze the causes that pedestrians attrib- uted to the crashes they suffered as pedestrians during the previous five years. Method: For this cross- sectional research performed in Spain, data from a nationwide sample of 2,499 pedestrians from the 17 regions of the country were collected. Participants had a mean age o…