| 1. |
- Hellström, Lisbeth M., et al.
(författare)
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An analytical and numerical study of some aspects of the wood chipping process
- 2009
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Ingår i: Nordic Pulp & Paper Research Journal. - : Walter de Gruyter GmbH. - 0283-2631 .- 2000-0669. ; 24:2, s. 225-230
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Tidskriftsartikel (refereegranskat)abstract
- In order to model the wood chipping process, the primary process parameters have been identified and their first order interaction studied. The model is analytical and incorporates, in particular, the influence of sliding friction between the wood chipping tool and the log. To estimate the accuracy of the analytical model, a Finite Element (FE) analysis of the problem considered was also performed. The analytical model and the FE analysis are both restricted to small deformations and linear elastic orthotropic material behaviour. The most severe limitation with both the analytical and the FE model is the assumption of linearly elastic material. On the other hand it is felt that existing models of anisotropic plasticity in metals are lacking too much of physical relevance, if applied to wood. The analytical model predicts the normal and shear strain distribution in the crack-plane prior to crack initiation. The analytical distributions are in reasonable agreement with the corresponding distribution of the FE analysis. Based on experimental findings, it is suggested that the stress field over the entire crack-plane, in conjunction with the stress field close to the tip of the chipping tool, are critical for chip creation, rather than just the latter.
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| 2. |
- Hellström, Lisbeth M, et al.
(författare)
-
An Analytical and Numerical Study of some aspects of the Wood Chipping Process
- 2009
-
Ingår i: Nordic Pulp & Paper Research Journal. - 0283-2631 .- 2000-0669. ; 24:2, s. 225-230
-
Tidskriftsartikel (refereegranskat)abstract
- SUMMARY: In order to model the wood chipping process, the primary process parameters have been identified and their first order interaction studied. The model is analytical and incorporates, in particular, the influence of sliding friction between the wood chipping tool and the log. To estimate the accuracy of the analytical model, a Finite Element (FE) analysis of the problem considered was also performed. The analytical model and the FE analysis are both restricted to small deformations and linear elastic orthotropic material behaviour. The most severe limitation with both the analytical and the FE model is the assumption of linearly elastic material. On the other hand, it is felt that existing models of anisotropic plasticity in metals are lacking too much of physical relevance, if applied to wood. The analytical model predicts the normal and shear strain distribution in the crack-plane prior to crack initiation. The analytical distributions are in reasonable agreement with the corresponding distribution of the FE analysis. Based on experimental findings, it is suggested that the stress field over the entire crack-plane, in conjunction with the stress field close to the tip of the chipping tool, are critical for chip creation, rather than just the latter.
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| 3. |
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| 4. |
- Karling, Pontus, et al.
(författare)
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Function and dysfunction of the colon and anorectum in adults: working team report of the Swedish Motility Group (SMoG).
- 2009
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Ingår i: Scandinavian journal of gastroenterology. - : Informa UK Limited. - 1502-7708 .- 0036-5521. ; 44:6, s. 646-60
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Forskningsöversikt (refereegranskat)abstract
- Symptoms of fecal incontinence and constipation are common in the general population. These can, however, be unreliably reported and are poorly discriminatory for underlying pathophysiology. Furthermore, both symptoms may coexist. In the elderly, fecal impaction always must be excluded. For patients with constipation, colon transit studies, anorectal manometry and defecography may help to identify patients with slow-transit constipation and/or pelvic floor dysfunction. The best documented medical treatments for constipation are the macrogols, lactulose and isphagula. Evolving drugs include lubiprostone, which enhances colonic secretion by activating chloride channels. Surgery is restricted for a highly selected group of patients with severe slow-transit constipation and for those with large rectoceles that demonstrably cause rectal evacuatory impairment. For patients with fecal incontinence that does not resolve on antidiarrheal treatment, functional and structural evaluation with anorectal manometry and endoanal ultrasound or magnetic resonance (MR) of the anal canal may help to guide management. Sacral nerve stimulation is a rapidly evolving alternative when other treatments such as biofeedback and direct sphincter repair have failed. Advances in understanding the pathophysiology as a guide to treatment of patients with constipation and fecal incontinence is a continuing important goal for translational research. The content of this article is a summary of presentations given by the authors at the Fourth Meeting of the Swedish Motility Group, held in Gothenburg in April 2007.
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| 5. |
- Thottappillil, Rajeev, et al.
(författare)
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Response of Civilian Facilities to Intentional Electromagnetic Interference (IEMI), with Emphasis on the Swedish Railway Network
- 2005
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Konferensbidrag (refereegranskat)abstract
- Recently a research program was initiated in Sweden to investigate the possible susceptibility of IEMI to civilian networks, with emphasis on the Swedish railway network. The objective is to develop a methodology for investigating and protecting sensitive railway facilities against IEMI and to recommend ways in which EMI control in the railways could be improved for better defense against IEMI. Details of the research program and some preliminary results are presented in this paper.
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| 6. |
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| 7. |
- Andersson, Henrik
(författare)
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Development of Process Technology for Photon Radiation Measurement Applications
- 2007
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis presents work related to new types of photo detectors and their applications. The focus has been on the development of process technology and methods by means of experimentation and measurements. The overall aim has been to develop and improve photon radiation measurement applications which are possible to manufacture using standard Si processing technology. A new type of position sensitive detector that has switching possibilities based on the MOS principle has been fabricated and characterized. The influence of mechanical stress on the linearity of position sensitive detectors has been investigated. The results show that mechanical stress arising, for example, by the mounting of detectors in capsules can have an impact on device performance. Under normal circumstances these effects are rather small, but are considered to be worthwhile taking into account. Electroless deposition of Nickel including various dopants in porous silicon was performed to manufacture electrical contacts for this interesting material. After heat treatment it was confirmed by X-ray diffraction that Nickel silicide had been formed and I-V measurements show that different contacts exhibit Ohmic and rectifying behaviour. Spectrometers are used extensively in the process and food industry to measure both the chemical content and the amount of substances used during manufacturing. These instruments are often rather bulky and costly, though the trend is towards smaller and more portable equipment. A spectrometer based on an array of Fabry-Perot interferometers mounted close to an array detector is shown to be a viable option for the manufacture of a very compact device. Such a device has minimal intermediate optics and it may be possible, in the future, for it to be developed and completely integrated with a detector array into a single unit.
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| 8. |
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| 9. |
- Bengtsson, Jörgen, et al.
(författare)
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The influence of age on the distribution of morphine and morphine-3-glucuronide across the blood-brain barrier in sheep
- 2009
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Ingår i: British Journal of Pharmacology. - : Wiley. - 0007-1188 .- 1476-5381. ; 157:6, s. 1085-1096
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Tidskriftsartikel (refereegranskat)abstract
- Background and purpose The effect of age on the distribution of morphine and morphine-3-glucuronide (M3G) across the blood-brain barrier (BBB) was studied in a sheep model utilizing intracerebral microdialysis. The effect of neonatal asphyxia on brain drug distribution was also studied. Experimental approach Microdialysis probes were inserted into the cortex, striatum and blood of 11 lambs (127 gestation days) and six ewes. Morphine, 1 mg.kg(-1), was intravenously administered as a 10 min constant infusion. Microdialysis and blood samples were collected for up to 360 min and analysed using liquid chromatography-tandem mass spectrometry. The half-life, clearance, volume of distribution, unbound drug brain : blood distribution ratio (K(p,uu)) and unbound drug volume of distribution in brain (V(u,brain)) were estimated. Key results Morphine K(p,uu) was 1.19 and 1.89 for the sheep and premature lambs, respectively, indicating that active influx into the brain decreases with age. Induced asphyxia did not affect transport of morphine or M3G across the BBB. Morphine V(u,brain) measurements were higher in sheep than in premature lambs. The M3G K(p,uu) values were 0.27 and 0.17 in sheep and premature lambs, indicating a net efflux from the brain in both groups. Conclusions and implications The morphine K(p,uu) was above unity, indicating active transport into the brain; influx was significantly higher in premature lambs than in adult sheep. These results in sheep differ from those in humans, rats, mice and pigs where a net efflux of morphine from the brain is observed.
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| 10. |
- Bengtsson, Magnus Wilhelm, 1977-
(författare)
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Effects of Orexins, Guanylins and Feeding on Duodenal Bicarbonate Secretion and Enterocyte Intracellular Signaling
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The duodenal epithelium secretes bicarbonate ions and this is regarded as the primary defence mechanism against the acid discharged from the stomach. For an efficient protection, the duodenum must also function as a sensory organ identifying luminal factors. Enteroendocrine cells are well-established intestinal “taste” cells that express signaling peptides such as orexins and guanylins. Luminal factors affect the release of these peptides, which may modulate the activity of nearby epithelial and neural cells.The present thesis considers the effects of orexins and guanylins on duodenal bicarbonate secretion. The duodenal secretory response to the peptides was examined in anaesthetised rats in situ and the effects of orexin-A on intracellular calcium signaling by human as well as rat duodenal enterocytes were studied in vitro.Orexin-A, guanylin and uroguanylin were all stimulants of bicarbonate secretion. The stimulatory effect of orexin-A was inhibited by the OX1-receptor selective antagonist SB-334867. The muscarinic antagonist atropine on the other hand, did not affect the orexin-A-induced secretion, excluding involvement of muscarinic receptors. Orexin-A induced calcium signaling in isolated duodenocytes suggesting a direct effect at these cells. Interestingly, orexin-induced secretion and calcium signaling as well as mucosal orexin-receptor mRNA and OX1-receptor protein levels were all substantially downregulated in overnight fasted rats compared with animals with continuous access to food. Further, secretion induced by Orexin-A was shown to be dependent on an extended period of glucose priming.The uroguanylin-induced bicarbonate secretion was reduced by atropine suggesting involvement of muscarinic receptors. The melatonin receptor antagonist luzindole attenuated the secretory response to intra-arterially administered guanylins but had no effect on secretion when the guanylins were given luminally. In conclusion, the results suggest that orexin-A as well as guanylins may participate in the regulation of duodenal bicarbonate secretion. Further, the duodenal orexin system is dependent on the feeding status of the animals.
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