| 1. |
- Wahba, H.H., et al.
(författare)
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High resolution digital holographic microscopy for the study of aggregated natural cellulose nanowhisker fibers
- 2015
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Ingår i: Optics and lasers in engineering. - : Elsevier BV. - 0143-8166 .- 1873-0302. ; 73, s. 69-74
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, digital holographic (DH) microscopy demonstrates its ability to perform a full characterization of nanofibers. The high resolution and magnification of the presented method to study the nanofibers are tested using standard MIL-STD-150A 1951 USAF resolution test target. In this investigation, aggregated natural cellulose nanowhisker fibers are positioned in the front of the microscopic objective using a 3D translation stage in the object arm of DH setup. The recorded off-axis holograms are refocused using the angular spectrum method. The reconstructed complex field is used to calculate optical phase and intensity distributions of the object at different reconstruction depths. A simple algorithm is used to define the focused image with suitable accuracy. The dimensions and orientation of the fibers can be evaluated from the optical field at different depths. Then, the shape and textures along the aggregated natural cellulose nanowhisker fiber can be presented in a 3D space.
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| 4. |
- Eilertsen, G., et al.
(författare)
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Similarities and differences in the experience of fatigue among people living with fibromyalgia, multiple sclerosis, ankylosing spondylitis and stroke
- 2015
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Ingår i: Journal of Clinical Nursing. - : Wiley. - 0962-1067 .- 1365-2702. ; 24:13-14, s. 2023-2034
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Tidskriftsartikel (refereegranskat)abstract
- Aims and objectives: To elucidate the experience of fatigue across several long-term illnesses, focusing on the similarities and differences. Background: Fatigue is common to many long-term illnesses, but it has been studied mainly within the context of a single illness; qualitative studies comparing the experience and its impact on daily life across different long-term illnesses are lacking. Design: Qualitative design. Methods: A secondary analysis was conducted of five original interview studies involving 95 persons with ankylosing spondylitis, fibromyalgia, multiple sclerosis or stroke. Results: Similarities and differences concerning experiences of fatigue were found across the studied long-term illnesses. All patients expressed the perception of having an unfamiliar body. Fatigue was also commonly expressed as unpredictable, uncontrollable and invisible to others. Differences were related to a constant versus a varying condition, a sudden and an uncontrollable sleepiness, a mutual reinforcement with pain and increased stress sensitivity. A lack of energy and a need for sleep and rest were common experiences, as was the impact on social relationships. There were also similarities regarding how the patients managed their daily life. The search for practical solutions and attitude adjustment differed with the fatigue characteristics. All patients felt a lack of understanding and disbelief from others. Conclusion and relevance to clinical practice: Fatigue is commonly expressed by patients with long-term illnesses. Variations in experience are related to the type of diagnosis. The disparity between experiences influences how patients managed and adjusted to the conditions of everyday life. The illness-specific characteristics of fatigue warrant increased clinical awareness and may allow professionals to offer adequate information and establish effective methods of managing the condition. The feeling of invisibility and difficulty describing the experience of fatigue in particular highlights this need. © 2015 John Wiley & Sons Ltd.
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| 5. |
- Frostevarg, Jan, 1982-, et al.
(författare)
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The formation of osseointegrating surfaceson titanium by laser irradiation
- 2018
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Ingår i: 71st IIW General Assembly, C-IV.
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Konferensbidrag (refereegranskat)abstract
- Pulsed lasers can be used to modify the surface of medical implants in order to accelerate bone growth(osseointegration). Here, it is used to create a surface that is beneficial for rapid osseointegration, also calledBioHelix™, having ridges and covered in attached droplets of diameters between 1 and 20 μm. This paper presentsthe results of an experimental program in which a range of laser parameters were used to create different surfacetextures on titanium substrates. The resulting surfaces were analyzed by scanning electron microscope and MicroComputer Tomography. The paper explains how different types of surface are created by the laser-materialinteraction under different conditions. It is shown that optimization of the laser parameters results in a robustprocess which produces a surface that is fundamentally different from those created by other methods
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| 7. |
- Olsson, Rickard, et al.
(författare)
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Challenges to the interpretation of the electromagnetic feedback from laser welding
- 2011
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Ingår i: Optics and lasers in engineering. - : Elsevier BV. - 0143-8166 .- 1873-0302. ; 49:2, s. 188-194
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Tidskriftsartikel (refereegranskat)abstract
- This paper considers the point that it is not possible to interpret individual weld perturbations from the raw electromagnetic feedback collected from laser weld zones. The presentation of electromagnetic data as a 3D cloud is presented as a new, useful tool in the analysis of this feedback. It is shown that there is a very low correlation between the plasma or thermal signals and the reflected light signal from the weld zone, and that a strong correlation exists between the plasma and thermal signals. It is also demonstrated that data points from a weld perturbation form a different 3D cluster to those from the stable welding process. A strategy for future real time data analysis is presented utilising a suitably shaped data cloud envelope. The rates of data fit to the various segments of such an envelope could be correlated with specific weld anomalies.
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| 8. |
- Olsson, Rickard, 1959-, et al.
(författare)
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Normal vector distribution as a classification tool for convoluted rough surfaces with overhanging features
- 2020
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Ingår i: Journal of laser applications. - : Laser Institute of America. - 1042-346X .- 1938-1387. ; 32:2
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Tidskriftsartikel (refereegranskat)abstract
- Convoluted rough surfaces involving overhanging features can be a natural consequence of laser additive manufacturing and other spray techniques or can be generated deliberately by laser surface texturing, e.g., to aid osseointegration. Overhanging features add an extra level of complexity to the topography of a rough surface and can have a substantial effect on wettability, etc. However, features of this type are invisible to traditional surface roughness measurement techniques. This work presents a computer-based surface analysis method that gives useful information about the presence and nature of overhanging features on rough technical surfaces. The technique uses micro-computer tomography to generate a typical cross section of the surface under investigation. The angles of the vectors normal to the surface can then be analyzed to reveal the presence of overhanging features, which can also be indicated by the standard deviation of the normal vector distribution. Titanium surfaces generated by six different techniques were compared. The characteristics of these surfaces varied strongly, as did the shapes of the overhangs involved. These variations are reflected by different statistical distributions of the normal vectors.
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| 10. |
- Olsson, Rickard, 1959-, et al.
(författare)
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Topographical evaluation of laser generated surfaces using statistical analysis of surface-normal vector distributions
- 2021
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Ingår i: IOP Conference Series: Materials Science and Engineering. - : Institute of Physics (IOP).
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Konferensbidrag (refereegranskat)abstract
- Surfaces generated by Additive Manufacturing or laser texturing can involve the solidification of droplets of liquid, which can give rise to overhanging features on the solidified surface. Overhanging features add a layer of complexity to the surface topography and are undetectable by standard surface roughness measurement techniques such as profilometry. Such features are important because they can have a considerable effect on surface properties such as wettability. New techniques and algorithms are therefore required to analyse and quantify convoluted surfaces with overhanging (re-entrant) features. Earlier work by the authors introduced the concept of using X-ray micro-computed tomography (Micro-CT) to identify the directions of vectors normal to the surface at any point and thus indicate the presence or absence of overhanging features. This paper divides overhanging features into two types; simple and compound, and introduces new, size independent, analysis techniques which measure what proportion of each type is on the surface. Another extension of the analysis is the comparison of surface profiles taken in different directions in order to identify any surface roughness anisotropies.
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