Multi-storey timber buildings: breaking industry path dependency

The Swedish legal restriction on construction of multi-storey timber buildings was imposed in 1888 and repealed in 1994. The subsequent emergence of such a timber building system in Sweden is analysed in the context of the existing concrete-based construction system. The characteristics of the construction industry and its path dependency over the past century hamper the development of a timber building system. However, government policies and funding, the wood industry's interest in an enhanced market for value-added wood products, and involvement of the wood research community has helped develop such a construction system. Investments in knowledge creation, incentives for the entry of new firms, and increased prefabrication may facilitate a transition from this formative phase to a growth phase in the diffusion of timber buildings.

En Suède, les restrictions juridiques frappant la construction de bâtiments en bois de plusieurs étages ont été édictées en 1888 et annulées en 1994. L'auteur analyse l'arrivée résultante d'un tel système de construction en bois en Suède face à la construction en béton qui existe actuellement. Les caractéristiques de l'industrie du bâtiment et sa dépendance au chemin au cours du siècle dernier empêchent le développement d'un système de construction en bois. Toutefois, les politiques officielles et les financements ainsi que les intérêts de l'industrie du bois dans un marché amélioré pour des produits en bois à valeur ajoutée et l'engagement des chercheurs dans le domaine du bois ont aidé à développer un tel système de construction. Les investissements dans la création du savoir, les incitations à l'arrivée de nouvelles entreprises et l'augmentation de la préfabrication peuvent faciliter le passage de cette phase de formation à une phase de croissance à la diffusion des bâtiments en bois.

Mots clés: système d'innovation, restriction, bâtiments de plusieurs étages, dépendance au chemin, systèmes technologiques, charpente en bois, bâtiments en bois, Suède     

Building energy-efficiency standards in a life cycle primary energy perspective

In this study we analyze the life cycle primary energy use of a wood-frame apartment building designed to meet the current Swedish building code, the Swedish building code of 1994 or the passive house standard, and heated with district heat or electric resistance heating. The analysis includes the primary energy use during the production, operation and end-of-life phases. We find that an electric heated building built to the current building code has greater life cycle primary energy use relative to a district heated building, although the standard for electric heating is more stringent. Also, the primary energy use for an electric heated building constructed to meet the passive house standard is substantially higher than for a district heated building built to the Swedish building code of 1994. The primary energy for material production constitutes 5% of the primary energy for production and space heating and ventilation of an electric heated building built to meet the 1994 code. The share of production energy increases as the energy-efficiency standard of the building improves and when efficient energy supply is used, and reaches 30% for a district heated passive house. This study shows the significance of a life cycle primary energy perspective and the choice of heating system in reducing energy use in the built environment.     

A numerical Hartree-Fock program for diatomic molecules

This paper describes an algorithm and a computer program which solves numerically (virtually exactly) equations of the restricted open-shell Hartree-Fock and Hartree-Fock-Slater model for diatomic molecules     

A comparison of methods for linear prediction of apple flavour from gas chromatographic measurements

A comparative study of linear methods for prediction of sensory profiles from gas chromatography (GC) measurements was performed. The data used came from an experiment on the effect of storing apples at various oxygen concentrations. Partial least-squares regression and continuum regression showed the best performance, measured by a two-step cross-validation principle. The traditional prediction error sum of squares (PRESS) overestimated the predictive ability of a multiple linear regression approach. The quality of the predictions of sensory properties from GC analyses was measured in terms of a ‘panel size equivalent’. Thus, the predictions obtained in the present study were as accurate as predictions from an assessor panel consisting of 4–9 assessors, depending on the sensory property in question.     

A portable virtual machine for Ada

A portable compiler can be constructed by letting it generate code for a virtual machine, which is then implemented on the real target machines. The design of a virtual machine which is especially suitable as a target machine for compiled Ada programs is described. The main design goals, implementability on mini-computers and portability, are discussed and the resulting design is described in some detail. Some implementation strategies for the machine are proposed and the feasibility of the virtual machine approach is discussed.     

Dynamics of casein micelles in skim milk during and after high pressure treatment

The effect of high hydrostatic pressure on turbidity of skim milk was measured in situ together with casein micelle size distribution. High pressure (HP) treatment reduced the turbidity of milk with a stronger pressure dependency between 50 and 300 MPa when the temperature was decreased from 20 to 5 °C, while at 30 °C (50–150 MPa) turbidity exceeded that of untreated milk. At 250 and 300 MPa turbidity decreased extremely. During pressurization of milk at 250 and 300 MPa, the turbidity initially decreased, but treatments longer than 10 min increased the turbidity progressively, indicating that re-association followed dissociation of casein micelles. Especially at 40 °C and at 250 and 300 MPa, the turbidity increased beyond untreated milk. Dynamic light scattering was used to investigate casein micelle sizes in milk immediately after long time (up to 4 h) pressurization at 250 and 300 MPa and casein micelle size distributions were bimodal with micelle sizes markedly smaller and markedly larger than those of untreated milk. Pressure modified casein micelles present after treatment of milk at 250 and 300 MPa were concluded to be highly unstable, since the larger micelles induced by pressure showed marked changes toward smaller particle sizes in milk left at ambient pressure.     

Localized surface plasmon resonance spectroscopy of single silver nanocubes

In this work, we use dark-field microscopy to observe a new plasmon resonance effect for a single silver nanocube in which the plasmon line shape has two distinct peaks when the particles are located on a glass substrate. The dependence of the resonance on nanocube size and shape is characterized, and it is found that the bluer peak has a higher figure of merit for chemical sensing applications than that for other particle shapes that have been studied previously. Comparison of the measured results with finite difference time domain (FDTD) electrodynamics calculations enables us to confirm the accuracy of our spectral assignments.     

Equal unpleasantness matching of malodorous substances in the community.

5 different odorants, produced through combustion procedures of animal manure, were matched with hydrogen sulfide with regard to unpleasantness by 30 female 20-47 yr olds. Power functions described the unpleasantness matchings for 5 combustion toilets tested. The exponents of the equal sensation functions indicated a relative invariance of the various combustion procedures on the exponent. Different combustion procedures resulted in different levels of odor unpleasantness, but these differences were small from a practical point of view. Results demonstrate the practical applicability of psychophysical methods in environmental health research. (18 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Formation of cracks in Soederberg electrodes used in aluminum reduction plants

Shrinkage and crack formation during baking of Soederberg anode paste for aluminum furnaces is discussed, and the authors demonstrate how this shrinkage may be reduced by applying suitable raw materials and paste compositions.