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- Kinell, Mats, et al.
(författare)
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Fan Shaped And Cylindrical Holes Studied in a Vane Film Cooling Test Rig
- 2010
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Ingår i: Proceedings of the Asme Turbo Expo 2010, Vol 4, Pts a and B. - 9780791843994 - 9780791838723 ; , s. 1777-1784
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Konferensbidrag (refereegranskat)abstract
- In order to optimize the vane film cooling and thereby increase the efficiency of a gas turbine, different film cooling configurations were experimentally investigated. Dynamic similarity was obtained regarding main flow Reynolds number, airfoil pressure coefficient, adiabatic wall temperature and film cooling ejection ratio. The maximum reached Mach number was 0.52. The geometry of the test section, consisting of one vane and two flow paths, was modified in order to meet the dimensionless pressure coefficient distribution around the airfoil experienced by a full stage airfoil. This would ascertain that scaled but engine realistic pressure gradients would be achieved in the rig test.During the test, the cold airfoil was suddenly imposed to a hot main stream and the evaluation of both the film cooling effectiveness and the heat transfer coefficient distribution on the visiable surface could be done at one single test using timeresolved temperature measurements obtained through IR thermography. A high resolution MWIR camera was used together with a silicon viewing window. The post-processing allowed for corrections regarding emissions and determination of the desired parameters on the vane surface.Results, heat transfer coefficients and film cooling effectiveness, for fan shaped and cylindrical film cooling holes configurations are compared. The results show clear benefit of using shaped holes over cylindrical ditto, especially on the suction side where near hole film effectiveness is enhanced by approximately 25%, but the results also show that this benefit diminishes to nothing in the suction side trailing edge region.The local heat transfer coefficients are generally lower for the shaped hole configurations. Contrary to the film effectiveness the shaped holes configurations show lower heat transfer coefficients also at the suction side trailing edge region, making use of the shaped hole configurations superior to cylindrical ones as the heat flux to the surface is reduced.Numerical predictions using a boundary layer code, TEXSTAN, and CFD, for a smooth wall configuration corresponds well with the measured results.
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- Åstrand, Håkan, et al.
(författare)
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In vivo estimation of the contribution of elastin and collagen on the mechanical properties in the abdominal aorta of man : effect of age and gender
- 2011
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Ingår i: Journal of applied physiology. - : AMER PHYSIOLOGICAL SOC. - 8750-7587 .- 1522-1601. ; 110:1, s. 8750-8757
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Tidskriftsartikel (refereegranskat)abstract
- The mechanical properties of the aorta affect cardiac function and are related to cardiovascular morbidity/mortality. This study was designed to evaluate the isotropic (mainly elastin, elastiniso) and anisotropic (mainly collagen, collagenani) material parameters within the human aorta in vivo. Thirty healthy men and women in three different age categories (23–30, 41–54, and 67–72 yr) were included. A novel mechanical model was used to identify the mechanical properties and the strain field with aid of simultaneously recorded pressure and radius in the abdominal aorta. The magnitudes of the material parameters relating to both the stiffness of elastiniso and collagenani were in agreement with earlier in vitro studies. The load-bearing fraction attributed to collagenani oscillated from 10 to 30% between diastolic and systolic pressures during the cardiac cycle. With age, stiffness of elastiniso increased in men, despite the decrease in elastin content that has been found due to elastolysis. Furthermore, an increase in stiffness of collagenani at high physiological pressure was found. This might be due to increased glycation, as well as changed isoforms of collagen in the aortic wall with age. A marked sex difference was observed, with a much less age-related effect, both on elastiniso and collagenani stiffness in women. Possible factors of importance could be the effect of sex hormones, as well as differing collagen isoforms, between the sexes.
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- Alex, Jonas, et al.
(författare)
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Effect evaluation of a heated ambulance mattress-prototype on body temperatures and thermal comfort - an experimental study
- 2014
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Ingår i: Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine. - : Springer Science and Business Media LLC. - 1757-7241. ; 22, s. 43-
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Tidskriftsartikel (refereegranskat)abstract
- Background:Exposure to cold temperatures is, often, a neglected problem in prehospital care. One of the leading influences of the overall sensation of cold discomfort is the cooling of the back. The aim of this study was to evaluate the effect of a heated ambulance mattress-prototype on body temperatures and thermal comfort in an experimental study.Method: Data were collected during four days in November, 2011 inside and outside of a cold chamber. All participants (n = 23) participated in two trials each. In one trial, they were lying on a stretcher with a supplied heated mattress and in the other trial without a heated mattress. Outcomes were back temperature, finger temperature, core body temperature, Cold Discomfort Scale (CDS), four statements from the state-trait anxiety - inventory (STAI), and short notes of their experiences of the two mattresses. Data were analysed both quantitatively and qualitatively. A repeated measure design was used to evaluate the effect of the two mattresses.Results:A statistical difference between the regular mattress and the heated mattress was found in the back temperature. In the heated mattress trial, the statement "I am tense" was fewer whereas the statements "I feel comfortable", "I am relaxed" and "I feel content" were higher in the heated mattress trial. The qualitative analyses of the short notes showed that the heated mattress, when compared to the unheated mattress, was experienced as warm, comfortable, providing security and was easier to relax on.Conclusions:Heat supply from underneath the body results in increased comfort and may prevent hypothermia which is important for injured and sick patients in ambulance care.
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- Aléx, Jonas, et al.
(författare)
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Patients' experiences of cold exposure during ambulance care
- 2013
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Ingår i: Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine. - London : BioMed Central. - 1757-7241. ; 21
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Exposure to cold temperatures is often a neglected problem in prehospital care. Cold exposure increase thermal discomfort and, if untreated causes disturbances of vital body functions until ultimately reaching hypothermia. It may also impair cognitive function, increase pain and contribute to fear and an overall sense of dissatisfaction. The aim of this study was to investigate injured and ill patients' experiences of cold exposure and to identify related factors.METHOD: During January to March 2011, 62 consecutively selected patients were observed when they were cared for by ambulance nursing staff in prehospital care in the north of Sweden. The field study was based on observations, questions about thermal discomfort and temperature measurements (mattress air and patients' finger temperature). Based on the observation protocol the participants were divided into two groups, one group that stated it was cold in the patient compartment in the ambulance and another group that did not. Continuous variables were analyzed with independent sample t-test, paired sample t-test and dichotomous variables with cross tabulation.RESULTS: In the ambulance 85% of the patients had a finger temperature below comfort zone and 44% experienced the ambient temperature in the patient compartment in the ambulance to be cold. There was a significant decrease in finger temperature from the first measurement indoor compared to measurement in the ambulance. The mattress temperature at the ambulance ranged from -22.3°C to 8.4°C.CONCLUSION: Cold exposure in winter time is common in prehospital care. Sick and injured patients immediately react to cold exposure with decreasing finger temperature and experience of discomfort from cold. Keeping the patient in the comfort zone is of great importance. Further studies are needed to increase knowledge which can be a base for implications in prehospital care for patients who probably already suffer for other reasons.
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| 9. |
- Andersson, Gerhard, et al.
(författare)
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Effects of Two Forms of Internet-Delivered Cognitive Behaviour Therapy for Depression on Future Thinking
- 2013
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Ingår i: Cognitive Therapy and Research. - New York, USA : Springer Science and Business Media LLC. - 0147-5916 .- 1573-2819. ; 37:1, s. 29-34
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to investigate if future thinking would change following two forms of Internet-delivered cognitive behavior therapy (ICBT) for major depression. A second aim was to study the association between pre-post changes in future thinking and pre-post changes in depressive symptoms. Effects of psychological treatments are most often tested with self-report inventories and seldom with tests of cognitive function. We included data from 47 persons diagnosed with major depression who received either e-mail therapy or guided self-help during 8 weeks. Participants completed a future thinking task (FTT), in which they were asked to generate positive and negative events that they thought were going to happen in the future and rated the events in terms of emotion and likelihood. The FTT was completed before and after treatment. Data on depressive symptoms were also collected. FTT index scores for negative events were reduced after treatment. There was no increase for the positive events. Change scores for the FTT negative events and depression symptoms were significantly correlated. We conclude that ICBT may lead to decreased negative future thinking and that changes in depression symptoms correlate to some extent with reductions in negative future thinking.
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| 10. |
- Andersson, Jonas, et al.
(författare)
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Dysregulation of subcutaneous adipose tissue blood flow in overweight postmenopausal women
- 2010
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Ingår i: Menopause. - : Ovid Technologies (Wolters Kluwer Health). - 1072-3714 .- 1530-0374. ; 17:2, s. 365-371
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: A putative link between abdominal obesity and metabolic-vascular complications after menopause may be due to a decreased adipose tissue blood flow (ATBF). The present work aimed to analyze possible changes in ATBF with being overweight and menopausal and its putative link to endothelial dysfunction and autonomic nervous system balance.METHODS: Forty-three healthy women were classified into four groups according to weight and menopause status. The ATBF was measured by xenon washout while fasting and after oral glucose intake. The nitric oxide synthase inhibitor asymmetric dimethylarginine was used as a marker of endothelial function and heart rate variability-estimated autonomic nervous system activity.RESULTS: Fasting ATBF was decreased in both overweight groups (P = 0.044 and P = 0.048) versus normal-weight premenopausal women. Normal-weight and overweight postmenopausal women exhibited lower maximum ATBF compared with normal-weight premenopausal women (P = 0.015 and P = 0.001, respectively), and overweight postmenopausal women exhibited lower maximum ATBF compared with normal-weight postmenopausal women (P = 0.003). A negative correlation was found between fasting ATBF and asymmetric dimethylarginine (P = 0.015), whereas maximum ATBF was negatively associated with sympathetic-parasympathetic nervous system balance (ratio of the power of the low frequency to the power of the high frequency; P = 0.002).CONCLUSIONS: Loss of ATBF flexibility in overweight postmenopausal women may contribute to the metabolic dysfunction seen in this group of women.
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