scispace - formally typeset
Search or ask a question

Showing papers by "Chalmers University of Technology published in 2004"


Journal ArticleDOI
TL;DR: The proposed functional, which includes van der Waals forces in a seamless fashion, is applied to rare gas and benzene dimers, where it is shown to give a realistic description.
Abstract: A scheme within density functional theory is proposed that provides a practical way to generalize to unrestricted geometries the method applied with some success to layered geometries [Phys. Rev. Lett. 91, 126402 (2003)]]. It includes van der Waals forces in a seamless fashion. By expansion to second order in a carefully chosen quantity contained in the long-range part of the correlation functional, the nonlocal correlations are expressed in terms of a density-density interaction formula. It contains a relatively simple parametrized kernel, with parameters determined by the local density and its gradient. The proposed functional is applied to rare gas and benzene dimers, where it is shown to give a realistic description.

4,713 citations


Journal ArticleDOI
TL;DR: The LCA framework and procedure is introduced, how to define and model a product's life cycle is outlined, and an overview of available methods and tools for tabulating and compiling associated emissions and resource consumption data in a life cycle inventory (LCI) is provided.

2,357 citations


Journal ArticleDOI
TL;DR: Quantitative evaluation and comparison show that the proposed Bayesian framework for foreground object detection in complex environments provides much improved results.
Abstract: This paper addresses the problem of background modeling for foreground object detection in complex environments. A Bayesian framework that incorporates spectral, spatial, and temporal features to characterize the background appearance is proposed. Under this framework, the background is represented by the most significant and frequent features, i.e., the principal features , at each pixel. A Bayes decision rule is derived for background and foreground classification based on the statistics of principal features. Principal feature representation for both the static and dynamic background pixels is investigated. A novel learning method is proposed to adapt to both gradual and sudden "once-off" background changes. The convergence of the learning process is analyzed and a formula to select a proper learning rate is derived. Under the proposed framework, a novel algorithm for detecting foreground objects from complex environments is then established. It consists of change detection, change classification, foreground segmentation, and background maintenance. Experiments were conducted on image sequences containing targets of interest in a variety of environments, e.g., offices, public buildings, subway stations, campuses, parking lots, airports, and sidewalks. Good results of foreground detection were obtained. Quantitative evaluation and comparison with the existing method show that the proposed method provides much improved results.

1,120 citations


Journal ArticleDOI
TL;DR: In this article, the development and diffusion of technologies that utilize renewable energy sources in Germany, Sweden and the Netherlands is analyzed. And the authors enlarges the life cycle model of industry evolution to one where the focus is on the formation and evolution of new technological systems, explaining success and failures in shifting from a formative phase into one characterized by positive feedbacks.
Abstract: This paper analyses the development and diffusion of technologies that utilize renewable energy sources in Germany, Sweden and the NetherlandsThe analysis enlarges the life cycle model of industry evolution to one where the focus is on the formation and evolution of new technological systems Particular focus is on explaining success and failures in shifting from a formative phase into one characterized by positive feedbacks A set of challenges is identified for policy makers attempting to influence the process of transforming the energy sector

862 citations


Journal ArticleDOI
TL;DR: This paper introduces and analyze a finite element method for elasticity problems with interfaces and proposes a general approach that can handle both perfectly and imperfectly bonded interfaces without modifications of the code.

791 citations


Journal ArticleDOI
TL;DR: In this paper, a comprehensive presentation of the consequential approach to system boundaries, allocation and data selection is presented, based on a text produced within the SETAC-Europe working group on scenarios in consequential life cycle assessment (LCA).
Abstract: A consequential life cycle assessment (LCA) is designed to generate information on the consequences of decisions. This paper includes a comprehensive presentation of the consequential approach to system boundaries, allocation and data selection. It is based on a text produced within the SETAC-Europe working group on scenarios in LCA. For most of the methodological problems, we describe ideal methodological solutions as well as simplifications intended to make the method feasible in practice. We compile, summarize and refine descriptions of consequential methodology elements that have been presented in separate papers, in addition to methodological elements and general conclusions that have not previously been published. A consequential LCA ideally includes activities within and outside the life cycle that are affected by a change within the life cycle of the product under investigation. In many cases this implies the use of marginal data and that allocation is typically avoided through system expansion. The model resulting from a consequential life cycle inventory (LCI) also includes the alternative use of constrained production factors as well as the marginal supply and demand on affected markets. As a result, the consequential LCI model does not resemble the traditional LCI model, where the main material flows are described from raw material extraction to waste management. Instead, it is a model of causal relationships originating at the decision at hand or the decision-maker that the LCI is intended to inform.

707 citations


Journal ArticleDOI
01 Jun 2004-Fuel
TL;DR: In this article, the feasibility of using an oxygen carrier based on oxides of iron, nickel, copper, copper and manganese was investigated for a chemical-looping combustion (CLC) with inherent separation of CO2.

616 citations


Journal ArticleDOI
TL;DR: This work explains how MIMO and diversity antennas with mutual coupling can be analyzed by classical embedded element patterns that can be computed by standard computer codes and how the radiation efficiency, diversity gain, correlation, and channel capacity can be measured in a reverberation chamber.
Abstract: MIMO systems are characterized by their maximum available capacity, which is reduced if there is correlation between the signals on different channels. The correlation is primarily caused by mutual coupling between the elements of the antenna arrays on both the receiving and transmitting sides. Similarly, diversity antennas can be characterized by a diversity gain that also is affected by mutual coupling between the antennas. We explain how such MIMO and diversity antennas with mutual coupling can be analyzed by classical embedded element patterns that can be computed by standard computer codes. In the MIMO example under investigation, the mutual coupling reduces both correlation, which increases the capacity, and radiation efficiency, which decreases it, and the combined effect is a net capacity reduction. We also explain how the radiation efficiency, diversity gain, correlation, and channel capacity can be measured in a reverberation chamber. The measurements show good agreement with simulations.

588 citations


Journal ArticleDOI
TL;DR: In this article, the authors discuss factors that influence development of trust and co-operation in client-contractor relationships in construction projects, and argue that a higher level of trust would improve project performance.

567 citations


Journal ArticleDOI
TL;DR: In this paper, the role of water in the hydration process of Ca 3 SiO 5 (C 3 S) cement is investigated, and accelerating effects of adding colloidal silica (CS) are established.

562 citations


Journal ArticleDOI
TL;DR: In this paper, the authors give the theoretical basis of a possible explanation for two stylized facts observed in long log return series: the long-range dependence (LRD) in volatility and the integrated GARCH (IGARCH).
Abstract: We give the theoretical basis of a possible explanation for two stylized facts observed in long log-return series: the long-range dependence (LRD) in volatility and the integrated GARCH (IGARCH). Both these effects can be explained theoretically if one assumes that the data are nonstationary.

Journal ArticleDOI
TL;DR: In this paper, the authors compared the emissions from commercial residential boilers fired with wood logs and wood pellets, and found that the mass concentration of particles was 180 times larger in the worst old-type case (a water-cooled wood boiler without heat storage tank) compared to the best modern case (wood pellets).

Journal ArticleDOI
TL;DR: In this paper, the authors discuss theoretical assumptions and the practical usefulness of the LCC approach in making environmentally responsible investment decisions and propose research solutions to handle inconsistencies in future development of environmental decision support tools.

Journal ArticleDOI
TL;DR: In this article, a density functional theory study of water adsorption on metal surfaces is presented, where the water-surface interaction is dominated by the lone pair-d band coupling through the surface states and a simultaneous enhancement of hydrogen bonding is generally observed in many adsorbed structures.
Abstract: We present a density functional theory study of water adsorption on metal surfaces. Prototype water structures including monomers, clusters, one-dimensional chains, and overlayers have been investigated in detail on a model system-a Pt(111) surface. The structure, energetics, and vibrational spectra are all obtained and compared with available experimental data. This study is further extended to other metal surfaces including Ru(0001), Rh(111), Pd(111), and Au(111), where adsorption of monomers and bilayers has been investigated. From these studies, a general picture has emerged regarding the water-surface interaction, the interwater hydrogen bonding, and the wetting order of the metal surfaces. The water-surface interaction is dominated by the lone pair-d band coupling through the surface states. It is rather localized in the contacting layer. A simultaneous enhancement of hydrogen bonding is generally observed in many adsorbed structures. Some special issues such as the partial dissociation of water on Ru(0001) and in the RT39 bilayer phase, the H-up and H-down conversion, and the quantum-mechanical motions of H atoms are also discussed.

Journal ArticleDOI
TL;DR: RT-QPCR gene expression measurements are comparable only when the same priming strategy and reaction conditions are used in all experiments and the samples contain the same total amount of RNA.
Abstract: Background: In most measurements of gene expression, mRNA is first reverse-transcribed into cDNA. We studied the reverse transcription reaction and its consequences for quantitative measurements of gene expression. Methods: We used SYBR green I-based quantitative real-time PCR (QPCR) to measure the properties of reverse transcription reaction for the β-tubulin, glyceraldehyde-3-phosphate dehydrogenase, Glut2, CaV1D, and insulin II genes, using random hexamers, oligo(dT), and gene-specific reverse transcription primers. Results: Experimental variation in reverse transcription-QPCR (RT-QPCR) was mainly attributable to the reverse transcription step. Reverse transcription efficiency depended on priming strategy, and the dependence was different for the five genes studied. Reverse transcription yields also depended on total RNA concentration. Conclusions: RT-QPCR gene expression measurements are comparable only when the same priming strategy and reaction conditions are used in all experiments and the samples contain the same total amount of RNA. Experimental accuracy is improved by running samples in (at least) duplicate starting with the reverse transcription reaction.

Journal ArticleDOI
TL;DR: In this article, pullout tests were carried out to evaluate the effects of corrosion on bond and bond-slip behavior, for a series of specimens with varying reinforcement corrosion levels between 0% and 9%, and for specimens with and without stirrups that provide confinement.

Journal ArticleDOI
19 Sep 2004
TL;DR: Finite functions over hereditarily finite algebraic datatypes are used to implement natural language morphology in the functional language Haskell to make it easy for linguists, who are not trained as functional programmers, to apply the ideas to new languages.
Abstract: This paper presents a methodology for implementing natural language morphology in the functional language Haskell. The main idea behind is simple: instead of working with untyped regular expressions, which is the state of the art of morphology in computational linguistics, we use finite functions over hereditarily finite algebraic datatypes. The definitions of these datatypes and functions are the language-dependent part of the morphology. The language-independent part consists of an untyped dictionary format which is used for synthesis of word forms, and a decorated trie, which is used for analysis.Functional Morphology builds on ideas introduced by Huet in his computational linguistics toolkit Zen, which he has used to implement the morphology of Sanskrit. The goal has been to make it easy for linguists, who are not trained as functional programmers, to apply the ideas to new languages. As a proof of the productivity of the method, morphologies for Swedish, Italian, Russian, Spanish, and Latin have already been implemented using the library. The Latin morphology is used as a running example in this article.

Journal ArticleDOI
TL;DR: In this article, the authors examined how the floc characteristics affect dewaterability of activated sludge and extracted extracellular polymeric substances (EPS), including the polymeric compounds protein, humic substances, carbohydrates and the ions Ca2+, Mg2+, Fe3+ and Al3+ in terms of the bound water content and capillary suction time.

Journal ArticleDOI
TL;DR: In this article, various protein-rich model compounds were pyrolyzed with the aim of finding features that are protein-specific, making conclusions regarding the model compounds applica-ble for biomass fuels in general.

Journal ArticleDOI
TL;DR: Compared with DNA modified with one cholesterol moiety only, the binding strength to lipid membranes appears to be significantly stronger and even irreversible over the time scale investigated, which means that the bivalent coupling can be used to precisely control the number of DNA per lipid-membrane area.
Abstract: By mimicking Nature's way of utilizing multivalent interactions, we introduce in the present work a novel method to improve the strength of cholesterol-based DNA coupling to lipid membranes. The bivalent coupling of DNA was accomplished by hybridization between a 15-mer DNA and a 30-mer DNA, being modified with cholesterol in the 3' and 5' end, respectively. Compared with DNA modified with one cholesterol moiety only, the binding strength to lipid membranes appears to be significantly stronger and even irreversible over the time scale investigated ( approximately 1 hr). First, this means that the bivalent coupling can be used to precisely control the number of DNA per lipid-membrane area. Second, the strong coupling is demonstrated to facilitate DNA-hybridization kinetics studies. Third, exchange of DNA between differently DNA-modified vesicles was demonstrated to be significantly reduced. The latter condition was verified via site-selective and sequence-specific sorting of differently DNA-modified lipid vesicles on a low-density cDNA array. This means of spatially control the location of different types of lipid vesicles is likely to find important applications in relation to the rapid progress currently made in the protein chip technology and the emerging need for efficient ways to develop membrane protein arrays.

Journal ArticleDOI
TL;DR: In this paper, the environmental and economic consequences of four recycling and disposal options for municipal sewage sludge have been assessed using the energy system model MARTES, and the results showed that agricultural application had the lowest cost of the options, whereas co-incineration had the highest cost.
Abstract: The environmental and economic consequences of four recycling and disposal options for municipal sewage sludge have been assessed. The four options were: agricultural application, co-incineration with waste, incineration combined with phosphorus recovery (Bio-Con) and fractionation including phosphorus recovery (Cambi-KREPRO). Life cycle assessment (LCA) was used to assess the environmental consequences, while effects in the district heating system were analysed using the energy system model MARTES. Co-incineration had the best energy balance, but without recovery of phosphorus. In the Bio-Con and Cambi-KREPRO processes both phosphorus and energy could be recovered. Compared to Cambi-KREPRO, Bio-Con was more effective in most respects, but suffered from higher emissions to air. Spreading sludge on agricultural land was the least preferable option from an environmental point of view. Energy was required for transportation, spreading and pasteurisation of the sludge, whereas the other three options enabled energy recovery. Spreading also caused release of nutrients and acidifying substances and transferred the content of heavy metals in the sludge to agricultural soil. The economic assessment showed that agricultural application had the lowest cost of the options, whereas co-incineration had the highest cost. The difference in cost between Bio-Con and Cambi-KREPRO was small, but since the technologies are new and untried in a commercial context, these results are uncertain. This study has shown that two sludge handling options, incineration and direct application to agricultural soil, have respectively economic and environmental restrictions. The development of relatively low cost phosphorus recovery technologies has the potential to reconcile the environmental and economic aspects of sustainability.

Journal ArticleDOI
TL;DR: It is demonstrated for the first time, how the kinetics of the process during which adsorbed vesicles are spontaneously transformed into a supported phospholipid bilayer (SPB) on SiO(2) can be quantitatively separated into its two dominating states: adsor beds and supported planar bilayer patches.
Abstract: Simultaneous quartz crystal microbalance with dissipation monitoring (QCM-D) and surface plasmon resonance (SPR) measurements are used to analyze the surface kinetics of two biomacromolecular systems, one lipid and one protein based, undergoing surface-induced conformational changes. First we establish a theoretical platform, which allows quantitative analysis of the combined SPR and QCM-D data. With this theoretical base, new information can be extracted, not obtainable with either technique alone. As an example we demonstrate how time-resolved measurements with these two techniques in combinationyielding three independent measured quantitiesadd new information about (i) kinetics, i.e. number of adsorbed molecules per unit area versus time, and (ii) temporal variation in the mass fraction of coupled water versus coverage. In particular, it is demonstrated for the first time, how the kinetics of the process during which adsorbed vesicles are spontaneously transformed into a supported phospholipid bilayer ...

Journal ArticleDOI
TL;DR: In this article, isolated nanometric holes in optically thin Au films exhibit a localized surface plasmon resonance in the red to near-infrared region, analogous to a dipolar particle plasmoron.
Abstract: Elastic scattering measurements show that isolated nanometric holes in optically thin Au films exhibit a localized surface plasmon resonance in the red to near-infrared region. The hole plasmon red shifts with increasing hole diameter or increasing refractive index of the surrounding medium, analogous to a dipolar particle plasmon. A pronounced blue shift is observed when the distance between holes is decreased, indicating an enhanced coupling between holes mediated by surface plasmon polaritons of the intervening flat film surface.

Journal ArticleDOI
TL;DR: In this article, the use of iron oxide as an oxygen carrier has been investigated in a chemical-looping combustion (CLC) technology with inherent separation of the greenhouse gas CO2.
Abstract: Chemical-looping combustion (CLC) is a combustion technology with inherent separation of the greenhouse gas CO2. The technique involves the use of a metal oxide as an oxygen carrier that transfers oxygen from the combustion air to the fuel. The use of iron oxide as an oxygen carrier has been investigated. Particles composed of 40−80 wt % Fe2O3, together with Al2O3, ZrO2, TiO2, or MgAl2O4, have been prepared by freeze granulation. Particles have been sintered at different temperatures in the range of 950−1400 °C, and particles 0.125−0.180 mm in diameter have been obtained by sieving. The reactivity of the oxygen-carrier particles has been evaluated in a laboratory fluidized bed of quartz, where the alternating atmosphere that an oxygen carrier encounters in a CLC system is simulated by exposing the sample to alternating reducing (50% CH4, 50% H2O) and oxidizing (5% O2) conditions at a temperature of 950 °C. The oxides are characterized prior to, and following, reactivity testing, with respect to crushing s...

Journal ArticleDOI
TL;DR: In this article, a stabilization technique for finite element methods for convection-diffusion-reaction equations, originally proposed by J. Douglas, Jr. and T. Dupont, was presented.

Journal ArticleDOI
TL;DR: This paper starts with a gradual introduction to GF, going through a sequence of simpler formalisms till the full power is reached, followed by a systematic presentation of the GF formalism and outlines of the main algorithms: partial evaluation and parser generation.
Abstract: Grammatical Framework (GF) is a special-purpose functional language for defining grammars. It uses a Logical Framework (LF) for a description of abstract syntax, and adds to this a notation for defining concrete syntax. GF grammars themselves are purely declarative, but can be used both for linearizing syntax trees and parsing strings. GF can describe both formal and natural languages. The key notion of this description is a grammatical object, which is not just a string, but a record that contains all information on inflection and inherent grammatical features such as number and gender in natural languages, or precedence in formal languages. Grammatical objects have a type system, which helps to eliminate run-time errors in language processing. In the same way as a LF, GF uses dependent types in abstract syntax to express semantic conditions, such as well-typedness and proof obligations. Multilingual grammars, where one abstract syntax has many parallel concrete syntaxes, can be used for reliable and meaning-preserving translation. They can also be used in authoring systems, where syntax trees are constructed in an interactive editor similar to proof editors based on LF. While being edited, the trees can simultaneously be viewed in different languages. This paper starts with a gradual introduction to GF, going through a sequence of simpler formalisms till the full power is reached. The introduction is followed by a systematic presentation of the GF formalism and outlines of the main algorithms: partial evaluation and parser generation. The paper concludes by brief discussions of the Haskell implementation of GF, existing applications, and related work.

Journal ArticleDOI
TL;DR: Experimental studies of light dripline nuclei are reviewed in this paper, including masses, spins, moments, reaction data over a wide energy range and beta-decays.

Journal ArticleDOI
TL;DR: Free films based on glucuronoxylan isolated from aspen wood were prepared by casting from aqueous solutions and drying in a controlled environment and thus examination of the material properties of these films found that films with xylitol gave lower extensibility.


Journal ArticleDOI
TL;DR: In this paper, three-terminal nanorelay structures were fabricated with multi-wall carbon nanotubes (MWNTs), and the nanotube relays were deflected by applying a gate voltage until contact (mechanical and/or electrical) was made with a drain electrode, thus closing the circuit.
Abstract: Three-terminal nanorelay structures were fabricated with multiwall carbon nanotubes (MWNTs). The nanotube relays were deflected by applying a gate voltage until contact (mechanical and/or electrical) was made with a drain electrode, thus closing the circuit. It was possible to achieve multiple switching cycles, showing that carbon nanotubes are suitable and practical systems for developing nanoelectromechanical devices of this kind.