Energy efficiency—a forgotten goal in the Swedish building sector?

The paper analyses trends in energy use and carbon dioxide emissions in the Swedish building sector between 1970 and 2000 with focus on the development of energy efficiency in the average stock of buildings and in the new construction. The energy efficiency improved throughout the seventies and early eighties, and studies revealed major potentials for further improvements. However, the energy efficiency has levelled off with almost no improvement during the nineties. The statistics for new-constructed multi-dwelling buildings indicate increasing energy use per floor area since 1995, and even more amazing: the new-constructed multi-dwelling buildings are at the same level of energy efficiency as the average existing building. Parallel to this development, the best available technology represented by low-energy buildings, uses less than a third of the energy used in average new buildings. Much of this development may be explained by changes in energy prices. The increasing oil price between 1972 and 1985 correlates well with the improvements in energy efficiency, even though the effect was limited by the low electricity price following the nuclear power programme. However, promotion of energy efficiency is complicated by the ineffective distribution of costs and benefits between actors, especially in the new construction. Moreover, to the residents energy cost is a small part of the expenditures and energy efficiency is merely one of many qualities valued in a building. An important factor behind the increasing energy use in new-constructed multi-dwelling buildings may also be new exceptions in the energy standards which were introduced to promote district heating. Finally, the paper gives some policy recommendations to improve the energy efficiency in the Swedish building sector: Not to support supply substitution at the expense of energy efficiency; Regulations for individual measurements and debiting of space and water heating; Strengthening of the energy standards to promote technical efficiency in the new construction.     

Solid–liquid phase equilibria of binary indole mixtures with some aromatic compounds using a solid–liquid–vapor equation-of-state

The separation of useful chemicals, such as indole from coal tar, is an important subject of research in the field of fossil energy, renewable energy, and utilization of byproducts and waste materials. High-pressure crystallization is one of the proposed separation methods. To understand the process requires detailed knowledge of solid–liquid phase behaviors. Solid–liquid phase equilibrium data of various binary mixtures of indole have been reported in the literature. In the present report, we analyze some of the experimental data with our unified solid–liquid–vapor equation-of-state to see whether our model can be useful for the calculation of solid–liquid equilibria in these organic systems. Good correlations of the data and predictions of phase behavior, at very high pressures, are demonstrated.     

Influence of temperature dependent properties on cooling behavior of cylindrical steels

Metallic materials, especially steels, are undertaken to different heat treatment processes in industry and cooling and heating times are of great importance. In this study, influence of variable physical properties of ANSI 1025 and AISI 304 steels and different boundary conditions namely forced convection, free convection and radiation on the calculation of cooling process was investigated. Governing differential equations were solved numerically for non-steady cases. It was found that variable properties should be taken into consideration for ANSI 1025, while the physical properties determined at an average temperature can be used for AISI 304. Another conclusion is that free convection can be neglected compared with radiation especially if forced convection coefficient is low.     

Antireflection coating on InP for semiconductor detectors

Aluminum nitride thin film by RF magnetron sputtering is used to produce antireflection coating on InP. The index of refection variation of aluminum nitride for different thickness at different wavelength in the range of 400 to 1500 nm is investigated using reflection spectroscopy. Subsequent Ar+ ion implantation at 30 keV with different doses on these coated layers has been performed. The morphology of aluminum nitride after ion implantation is characterized using atomic force microscopy AFM.     

An updated correlation for crack-arrest fracture toughness for nuclear reactor pressure vessel steels

An updated and statistically-rigorous correlation is provided for crack-arrest toughness values versus normalized temperature for light-water nuclear reactor pressure vessel (RPV) steels. The database used in this effort is larger than applied heretofore and includes results from tests of laboratory-size specimens and from tests of large-scale specimens, which contain features prototypical of operating RPVs. The mathematical methodology used is based on a lognormal distribution, with its parameters calculated by orthogonal distance regression. This correlation was developed as one of several items updated for use in the US Nuclear Regulatory Commission's extensive program to evaluate and potentially revise its rule for ensuring structural integrity of operating RPVs when subjected to pressurized thermal-shock transients.     

Calculations of optical properties in p-doped nitrides quaternary alloys multiple quantum wells

We present theoretical photoluminescence (PL) and absorption spectra of p-doped InGaN/AlInGaN and AlInGaN/InGaN multiple quantum wells (MQWs). The calculations were performed within the k.p method by means of solving a full eight-band Kane Hamiltonian together with the Poisson equation in a plane wave representation, including exchange–correlation effects within the local density approximation. Strain effects due to the lattice mismatch and an internal electric field are also taken into account. We show that by changing the In and Al composition we can reach short and long emission wavelengths. The trends in the calculated Stokes shift, due to many-body effects within the quasi-two-dimensional hole gas (2DHG), are analyzed as a function of the acceptor doping concentration. Since the studies of optical properties of quantum wells based on nitrides quaternary alloys are at an early stage, the results reported here will provide guidelines for the interpretation of forthcoming experiments.     

Photocatalytic evolution of hydrogen over mesoporous TiO2 supported NiO photocatalyst prepared by single-step sol–gel process with surfactant template

Photocatalytic activity of mesoporous titania supported nickel oxide photocatalyst synthesized by single-step sol–gel (SSSG) process combined with surfactant-assisted template method was investigated for hydrogen evolution from an aqueous methanol solution, in comparison with one prepared by conventional incipient wetness impregnation (IWI) method. In single-step sol–gel process, nickel precursor was introduced into the titania sol prepared with the aid of a surfactant template behaving as pore-controlling agent to attain meso-scaled pore. The single-step sol–gel photocatalyst was experimentally found to enhance the photocatalytic evolution of hydrogen rather than the impregnated one. The optimum level of nickel loading in photocatalytic activity test for single-step sol–gel method was slightly higher than that for incipient wetness impregnation method. Characterization results demonstrated the significant modification of physical characteristics of the single-step sol–gel photocatalyst, anticipated to relating to the observation of higher photocatalytic hydrogen evolution activity.     

Magnetic Field Analysis of Disk Coreless Permanent Magnet Synchronous Motor Based on Thickness Variation Halbach Array

Being a new permanent magnets(PMs) arrangement, the Halbach array could approve the magnetic flux density effectively, through weakening the magnetic flux density in one side of the PMs array, meanwhile strengthening the magnetic flux density in the other side. In the disk coreless PM synchronous motor (PMSM), the magnetic flux density is required to be sine wave and the peak value should be as high as possible. The paper deals with the application of the 90° Halbach array in the disk coreless PMSM, adopting NdFeB PMs. For the thickness of PMs influences the magnetic flux density in the air gap, the thickness variation technology is adopted. Through altering the adjacent PMs thickness, nine different PMs thickness combination is analyzed by FEM methods. And the conclusion is that when the thickness of tangential magnetization PMs is great than that of the radial magnetization PMs, the magnetic flux density wave is closer to sine wave than when the thickness of the tangential magnetization PMs is smaller than that of the radial magnetization PMs. Furthermore, when the thickness of the tangential magnetization PMs is great than that of the radial magnetization PMs, keeping the thickness of the tangential magnetization PMs being 0.006 m and the thickness of the radial magnetization PMs variation from 0.0048 m to 0.006 m, the magnetic flux density in the air gap will become closer to sine wave gradually, and then it becomes nonsinusoidal again. And when the thickness of radial magnetization PMs is 0.0054 m and 0.0055 m, the waves of magnetic flux density in the air gap are better than others.     

Templated titania films with meso- and macroporosities

Porous TiO₂ films with both mesoporosity and macroporosity were fabricated by a templated sol–gel method for applications, such as dye-sensitized solar cells (DSC), photocatalysis and catalysis. With the incorporation of differently sized pores, the resultant structures exhibit high surface areas and possess interpenetrating aligned pore channels, which are believed to be beneficial for applications where diffusion of reactants to interior surface can be rate limiting. Both liquid and solid TiO₂ precursors can be applied for large area coating in this process. Almost crack-free films were produced by templated coating of pre-synthesized TiO₂ nanoparticles. The measured specific surface area and porosity of synthesized films were in the range of 33–137 m²/g and 61–80%, respectively, depending on the size of the selected template.