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Luleå tekniska universitet Övrigt
N/A / Link / Almqvist , Nils / 1994

Luleå tekniska universitet Övrigt
The liberalisation of the West European electricity and gas markets, technological developments in power technology and environmental policies are expected to stimulate continued strong growth in power generation gas consumption. This paper examines the importance of three frequently disregarded considerations in the analysis of expanded gas use in power generation. These include: (a) better use of existing capacity; (b) security of supply concerns; and (c) gas price increases and the entry of new power technologies. While the paper confirms that the future looks bright for gas-fired power generation in Western Europe, it also introduces some important uncertainties about the prospects for gas use and in particular the pace at which gas can be expected to penetrate the West European power sector. In this way, the paper questions some of the more optimistic projections of gas consumption.
N/A / Link / Söderholm , Patrik / 2001

This is the reply to a comment by Andreas Aste on a previous article of mine in Can.J.Phys. The counter-arguments used by Aste utilize a mathematical limit without physical meaning. We still contend that in QCD, the particles "gluons'' and "quarks'' are merely artifacts of an approximation method (the perturbative expansion) and are simply absent in the exact theory.
N/A / Link / Hansson , Johan / 2003

Luleå tekniska universitet Övrigt
91-972568-2-X / Link / Mörtberg , Christina / 1995

Luleå tekniska universitet Övrigt
91-972568-9-7 / Link / Mörtberg , Christina / 2003

Bringing together current ideas in the fields of biomineralization and composite laminate materials, we have attempted to fabricate model materials that mimic abalone nacre through the rapid assembly of inorganic tablets, such as talc. Several physical methods were tested to aid the orientation of the talc tablets in fluid suspensions with a low percentage, 10% by dry weight, of organic binding material. The orientation of talc tablets in the synthesized composites was characterized by X-ray diffraction and scanning electron microscopy. The modulus of rupture of the materials was measured in a three-point bending test. We demonstrate that the alignment of tablets increases by the use of physical methods and from chemical surface treatment. Important factors to consider in making materials that mimic abalone nacre are discussed. Important factors to consider in making materials that mimic abalone nacre are discussed.
N/A / Link / Almqvist , Nils / 1999

Luleå tekniska universitet Övrigt
N/A / Link / Söderholm , Patrik / 1998

We present experimental support for a model of abalone nacre growth that is based on mineral bridges between successive aragonite tablets rather than on heteroepitaxial nucleation. Interlamellar sheets of organic polymers delineate the aragonite tablets but allow the tablets to grow mineral bridges through pores in the sheets. Atomic force microscope images of interlamellar organic sheets from flat pearls made by Haliotis rufescens (red abalone; marine gastropod mollusk) reveal a fibrous core and holes of 5-50 nm in diameter. Scanning ion conductance microscopy shows that these holes are actually pores through the interlamellar sheets. With the help of statistical analysis we can associate the pore-to-pore spacings in the interlamellar sheets with the observed offsets of successive nacre tablets. These results, supplemented by AFM, SEM, and TEM images, support and extend the model of biofabrication of gastropod nacre which is based on mineral bridges between the aragonite tablets.
N/A / Link / Schäffer , Tilman E / 1997

Luleå tekniska universitet Övrigt
There exists a great need for automatic precipitation gauges for effective road maintenance during the winter period. These gauges should be inexpensive, not require mains supply, need little attendance, give information about presence of precipitation and determine type (snow, rain or sleet) while there is no need for high accuracy of the precipitation intensity. Light attenuation precipitation sensors (optical gauges) fulfil several of these requirements and are used in the Swedish National Road Administration Road Weather System. The optical gauges measure the time it takes of particles of snow etc. to pass (attenuate) a light beam and relate this time to precipitation type and intensity. The rain precipitation mass is approximately proportional to the accumulated attenuation time. To investigate whether or not optical gauges could also be used for solid precipitation, the precipitation mass for snow, rain and sleet was measured with a reference gauge and compared to the attenuation time. The passage time of individual hydrometeorologic particles (snow, rain and sleet) was compared with precipitation type and wind speed. Air temperature could be used as a rough guide a distinguish three precipitation categories for the following temperatures: rain (> +2-degrees-C), sleet (0 to +2-degrees-C) and snow (less-than-or-equal-to 0-degree-C). At low wind speeds (< 3 m/s) the passage time of individual particles could be used to distinguish between rain and snow. The accumulated attenuation time for the same precipitation mass was approximately 25 and 5 times greater for snow and sleet respectively compared to rain. With the attenuation time for the snow-fall corrected for wind influence the quotient between the attenuation time for snow and rain is decreased from approximately 25 to approximately 12 times.
N/A / Link / Lundberg , Angela / 1994

Luleå tekniska universitet Övrigt
N/A / Link / Hansson , Johan / 2005

90-73168-00-7 / Link / Hedström , Peter / 2005

This paper presents measurements of voltages and currents taken by fluorescent lamps with high-frequency ballast. The results are discussed in time domain, in frequency domain and in time-frequency domain. A number of different high-frequency components are present: recurrent transients, narrow-band time-invariant signals, and time-dependent signals. The increase in distortion with increasing number of lamps is studied as well. The distortion increases about linear with the number of lamps in the frequency range 2-9 kHz but shows only a minor increase or no increase at all in the frequency range 9-150 kHz.
N/A / Link / Larsson , Anders / 2006

Luleå tekniska universitet Övrigt
N/A / Link / Berg , Elisabeth / 1999

Luleå tekniska universitet Övrigt
N/A / Link / Piippola , Saila / 1999

1-84064-148-7 / Link / Söderholm , Patrik / 2002

Luleå tekniska universitet Övrigt
91-620-5416-3 / Link / Söderholm , Patrik / 2004

A column-switching system for fast determination of (R)- and (S)-naproxen       in liver microsomes has been developed. The centrifuged sample was       injected directly onto a pre-column with octadecylcoated silica. The       retained analytes were then directed to an alpha 1-AGP column using a       mobile phase composed of phosphate buffer (pH 6.5), dimethylocytylamine       (30 mM) and the nonionic surfactant, Tween 20 (40 g/l). The method gave       high absolute recoveries and good repeatabilities: 99.6% (1.7% relative       standard deviation) and 94.9% (2.4% R.S.D.) for the (R)- and (S)-naproxen,       respectively. The use of a surfactant in combination with an aliphatic       amine in the mobile phase involves reduced retention times with retained       enantioselectivity. Furthermore, the presence of the surfactant makes it       possible to inject biological samples directly into the chromatographic       system.
N/A / Link / Haupt , Dan / 1992

The main topic of this thesis is experimental analysis of material surfaces using scanning probe microscopies. These microscopes are used for characterization through high-resolution topographical imaging, but also for controlled modification of surfaces and molecules. The surface characterization includes evaluation and development of fractal methods for surface roughness determination. The term modification is used for manipulating the structures on a microscale by scraping them with a tiny tip. The major application of this technique in the present work is the analysis of effects induced by plasma-surface interactions. Such studies are fundamental in the understanding of erosion and deposition processes on the first wall in controlled fusion devices. In this work, scanning probe microscopes were for the first time used for studying such plasma-facing materials. Both the surface structure and composition have to be known in order to evaluate new wall-materials for fusion reactors. The materials studied here are graphites, SiC/Al coatings, graphite-silicon mixtures and various silicon carbide based composites. They were all exposed to plasmas, either to lowenergy deuterium plasmas and ions in laboratory experiments, or to the plasma in a socalled tokamak. The results show the usefulness of these high-resolution microscopes in the study of plasma-surface interaction. Several other surface sensitive techniques were also applied, at the home laboratories of our collaborators, the most important ones being Rutherford backscattering spectroscopy and nuclear reaction analysis. The scanning probe microscopy in combination with the ion-beam analysis made it possible to trace fine structural features on the surfaces and to measure the surface roughness. The main results are: (i) the detection of the initial stages of bubble/blister formation on CSi mixtures, SiC/AI coatings and graphites; (ii) the morphological changes and the physical properties of the silicon carbide composites; (iii) the distinction of radiation damages on different phases of multicomponent composites; (iv) the estimation of layer thickness with scanning probe microscopy; (v) the determination of the structure of codeposited layers formed during exposure in a tokamak; (vi) the uptake of deuterium by the materials. The atomic force microscope has also been used to study the human protein spectrin, and we managed to image free spectrins with molecular resolution in an almost natural environment. The elongated spectrin macromolecule was found to be 100 rim long and 5 nm broad. Indications of a substructure were observed. The force between the sensor tip and the molecules was crucial, both for sample movement, manipulation and image resolution. Therefore, the instrument was rebuilt to operate with so called tapping-mode in liquid. Preliminary results with this method on spectrin are presented.
N/A / Link / Almqvist , Nils / 1995

This paper revisits defocused speckle correlation as a tool for measuring the response in metal sheets during percussion laser drilling processing. For the processing the 4th harmonic Nd:YAG wavelength (266 nm) was used in pulsed mode. It is shown that the method provides a cost efficient and robust alternative to speckle interferometry for the study of the small deformations that appear during laser processing. The accuracy was shown to be in the order of a few tens of μrads for the tilt component being measured which translates to a few nm in deflection when being spatially integrated. In the measurements deflections up to 50 nm was detected on the backside of silver and a copper sheet, respectively.
9780819464262 / Link / Sjödahl , Mikael / 2006

Luleå tekniska universitet Övrigt
N/A / Link / Forsberg , Fredrik / 2006

The deformation behavior of metastable austenitic stainless steel AISI 301, suffering different initial cold rolling reduction, has been investigated during uniaxial tensile loading. In situ highenergy x-ray diffraction was employed to characterize the residual strain evolution and the strain induced martensitic transformation. Moreover, the 3DXRD technique was employed to characterize the deformation behavior of individual austenite grains during elastic and early plastic deformation. The cold rolling reduction was found to induce compressive residual strains in the austenite along rolling direction and balancing tensile residual strains in the -martensite. The opposite residual strain state was found in the transverse direction. The residual strain states of five individual austenite grains in the bulk of a sample suffering 2% cold rolling reduction was found to be divergent. The difference among the grains, considering both the residual strains and the evolution of these, could not be solely explained by elastic and plastic anisotropy. The strain states of the five austenite grains are also a consequence of the local neighborhood. Introduction The metastable austenitic stainless steels partially transform from the soft and ductile austenite to the hard and brittle martensite during deformation. This deformation induced martensitic transformation provides a compos...
0-87849-414-6 / Link / Hedström , Peter / 2006

Luleå tekniska universitet Övrigt
This paper reviews and analyzes how Sweden became a leader concerning low carbon emissions, by using economical incentives, investments in new technologies and work to form international collaborations. The lessons from the Swedish case may be used by other countries and regions to be better able to achieve results from policy initiatives.
N/A / Link / Leduc , Sylvain / 2006

Luleå tekniska universitet Övrigt
1-899332-59-6 / Link / Söderholm , Patrik / 1999

Luleå tekniska universitet Övrigt
N/A / Link / Wästerlund , Dianne / 1999

Luleå tekniska universitet Övrigt
N/A / Link / Lindström , Lisbeth / 2007

Luleå tekniska universitet Övrigt
N/A / Link / Lundberg Vesterlund , Lena / 1998

Luleå tekniska universitet Övrigt
91-630-9694-3 / Link / Rydhagen , Birgitta / 2000

In the paper by Nesvizhevsky et al. [Phys. Rev. D 67, 102002 (2003)], it is argued that the lowest quantum state of neutrons in the Earth's gravitational field has been experimentally identified. While this is most likely correct, it is imperative to investigate all alternative explanations of the result in order to close all loopholes, as it is the first experiment ever claimed to have observed gravitational quantum states. Here we show that geometrical effects in the experimental setup can mimic the results attributed to gravity. Modifications of the experimental setup to close these possible loopholes are suggested.
N/A / Link / Hansson , Johan / 2003

N/A / Link / Jonsen , Pär / 2006