Preparation of thermoset composites from natural fibres and acrylate modified soybean oil resins

Structural composites with a high content of renewable material were produced from natural fibres and an acrylated epoxidized soybean oil resin. Composites were prepared by spray impregnation followed by compression moulding at elevated temperature. The resulting composites had good mechanical properties in terms of tensile strength and flexural strength. Tensile testing as well as dynamical mechanical thermal analysis showed that increasing the fibre content, increased the mechanical properties. The resin can be reinforced with up to 70 wt % fibre without sacrifice in processability. The tensile modulus ranged between 5.8 and 9.7 GPa depending on the type of fibre mat. The study of the adhesion by low vacuum scanning electron microscopy shows that the fibres are well impregnated in the matrix. The aging properties were finally evaluated. This study shows that composites with a very high content of renewable constituents can be produced from soy bean oil resins and natural fibres. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Creativity and Its Discontents: Professional Ideology and Creativity in Architect Work

Architects are a professional group that is commonly associated with creative and aesthetic work and with strong professional norms, values and identities. While such shared norms and beliefs are positive overall in terms of being constitutive of professional subject‐positions, an overemphasis on specific skills and qualities may also be regarded as a burden on members of the professional community. A study of a major Scandinavian architect office suggests that the perceived lack of creative and innovative thinking and accompanying dialogues and discussions among practising architects tends to produce cynicism and, to some extent, disappointment. As a consequence, professional ideologies may in some cases be out of joint with everyday work realities, and thereby to some extent produce expectations that are complicated to fulfil. Professional ideologies are thus both what integrates and consolidates a profession while at the same time prescribing ideal future scenarios for the professional community.     

On a class of preconditioned iterative methods on parallel computers

The standard implementations of iterative solvers for finite element and finite difference methods frequently use a diagonal (Jacobi) preconditioner, particularly for element-by-element schemes. However, for such methods the actual order of the condition number with respect to mesh size is not reduced by the preconditioner. In the present paper we describe an iterative method where, in addition, the condition number is reduced by an order of magnitude. Moreover, the scheme may also be implemented as an element-by-element method. The method uses a generalized SSOR preconditioner and a wave front or multi-frontal ordering of the mesh nodes. For a general irregular finite element mesh a striped irregular wave front ordering may be used. The performance of the method as well as various iterative acceleration techniques for a parallel computer are examined in the numerical studies.     

Kinematics of the heart: strain-rate imaging from time-resolved three-dimensional phase contrast MRI

A four-dimensional mapping (three spatial dimensions + time) of myocardial strain-rate would help to describe the mechanical properties of the myocardium, which affect important physiological factors such as the pumping performance of the ventricles. Strain-rate represents the local instantaneous deformation of the myocardium and can be calculated from the spatial gradients of the velocity field. Strain-rate has previously been calculated using one-dimensional (ultrasound) or two-dimensional (2-D) magnetic resonance imaging) techniques. However, this assumes that myocardial motion only occurs in one direction or in one plane, respectively. This paper presents a method for calculation of the time-resolved three-dimensional (3-D) strain-rate tensor using velocity vector information in a 3-D spatial grid during the whole cardiac cycle. The strain-rate tensor provides full information of both magnitude and direction of the instantaneous deformation of the myocardium. A method for visualization of the full 3-D tensor is also suggested. The tensors are visualized using ellipsoids, which display the principal directions of strain-rate and the ratio between strain-rate magnitude in each direction. The presented method reveals the principal strain-rate directions without a priori knowledge of myocardial motion directions.     

Thermal destruction of PCB and hexachlorobenzene

PCB and hexachlorobenzene are considered to be two environmental compounds of concern that are most difficult to destroy. This report describes experiments that have been carried out in order to obtain basic data for appraisal of the risks involved in the thermal destruction of PCB and hexachlorobenzene.The investigation indicates that it is possible to destroy PCB by incineration provided that the transit time is sufficiently long. In the pilot scale incinerator used, a transit time of more than two seconds was required to obtain a residue of PCB that was less than 100 mg/kg PCB fed into the incinerator. It was not possible to determine any fixed relationship between the temperature and the PCB residue within the temperature range examined (675–1000°C). The investigation also shows that hexachlorobenzene is formed in association with the combustion of PCB and that the rate of formation increases at high temperatures (35 mg HCB/kg PCB at 1000°C).A temperature of 950°C is needed for the destruction of hexachlorobenzene if the residue is to be less than 100 mg HCB/kg HCB. At 800°C, with a transit time of about 2 s, there is a residue of approximately 1200 mg/kg.     

“It’s Just a Matter of Adjustment”: Residents’ Perceptions and the Potential for Low-impact Home Practices

In addition to material, spatial and thermal standards and norms that influence the resource intensity of home environments, a key indicator of the environmental impact related to housing is found in residents’ ways of life. Of interest to the study presented in this paper is how residents’ perceptions of home and living standards relate to opinions on environmental issues and the reduction of resource use, exploring the potential and willingness to engage in low-impact ways of living. Empirical material from a questionnaire (n = 156) and interview study (n = 22) with residents in a tenant-owned housing association in Sweden provides insights into conventions and perceptions surrounding practices primarily linked to voluntary simplicity, living smaller as well as sharing spaces and resources. The study emphasizes the need for understanding residents’ perspectives and the implications this might have for targeting the resource intensity of homes in future development and policy.     

Collaborative Information Seeking

An examination of the roles and dimensions of collaborative search reveals new opportunities for information-seeking support tools.     

Critical conditions for onset of mould growth under varying climate conditions

A performance-based service life design format based on climatic exposure on one hand and “resistance” of materials against mould growth on the other hand, is presented in this paper. A limit state for onset of mould growth is defined as the occurrence of traces of mould observed by microscopy. A dose–response model is proposed by which onset of mould growth can be predicted for an arbitrary climate history of combined relative humidity ? and temperature T. The model is calibrated and verified against a comprehensive set of experimental data published by Viitanen et al. [Viitanen H, Ritschkoff A-C. Mould growth in pine and spruce sapwood in relation to air humidity and temperature. Uppsala: Swedish University of Agricultural Sciences, Department of Forest Products; 1991. Report No. 221, 49 p.; Viitanen H. Modelling the time factor in the development of mould fungi – effect of critical humidity and temperature conditions in pine and spruce sapwood. Holzforschung 1997;51(1):6–14; Viitanen H. Modelling the time factor in the development of brown rot decay in pine and spruce sapwood – the effect of critical humidity and temperature conditions. Holzforschung 1997;51(2):99–106; Viitanen H, Bjurman J. Mould growth on wood under fluctuating humidity conditions. Material und Organismen 1995;29(1):27–46] describing mould development on spruce and pine sapwood as a function of climatic exposure. The model is applied to predict time to onset of mould growth under natural outdoor climate (under shelter) as well as mould development in building attics and in crawl space foundations. The predicted response shows reasonable agreement with experimental observations and proven experience, although biological processes of this type display great variability. The results show that a generally applicable, quantitative model can be used as a powerful tool for moisture safe design in practice. The model is designed to facilitate continuous improvement of prediction capability by further laboratory testing of various materials under specified climate conditions. In combination with currently available building physics software the model is suitable for moisture safe design of wood-based components in the building envelope.