| 1. |
- Andersson, Klas, 1977, et al.
(författare)
-
Radiation intensity of lignite-fired oxy-fuel flames
- 2008
-
Ingår i: Experimental Thermal and Fluid Science. - : Elsevier BV. - 0894-1777. ; 33:1, s. 67-76
-
Tidskriftsartikel (refereegranskat)abstract
- The radiative heat transfer in oxy-fuel flames is compared to corresponding conditions in air-fuel flames during combustion of lignite in the Chalmers 100 kW oxy-fuel test facility. In the oxy-fuel cases the flue-gas recycle rate was varied, so that, in principle, the same stoichiometry was kept in all cases, whereas the oxygen fraction in the recycled flue-gas mixture ranged from 25 to 29 vol.%. Radial profiles of gas concentration, temperature and total radiation intensity were measured in the furnace. The temperature, and thereby the total radiation intensity of the oxy-fuel flames, increases with decreasing flue-gas recycle rate. The ratio of gas and total radiation intensities increases under oxy-fuel conditions compared to air-firing. However, when radiation overlap between gas and particles is considered the ratios for air-firing and oxy-fuel conditions become more similar, since the gas-particle overlap is increased in the CO2-rich atmosphere. A large fraction of the radiation in these lignite flames is emitted by particles whose radiation was not significantly influenced by oxy-fuel operation. Therefore, an increment of gas radiation due to higher CO2 concentration is not evident because of the background of particle radiation, and, the total radiation intensities are similar during oxy-fuel and air-fuel operation as long as the temperature distributions are similar.
|
|
| 2. |
|
|
| 3. |
- Eriksson, Joakim, 1977-, et al.
(författare)
-
MODELLING DECISION-MAKING IN COMPLEX PRODUCT DEVELOPMENT
- 2008
-
Ingår i: Proceedings of the DESIGN 2008, 10th International Design Conference, Dubrovnik, Croatia. - Dubrovnik. - 9789536313891 ; , s. 1129-1138
-
Konferensbidrag (refereegranskat)abstract
- One challenge today for companies lies in finding the right approach to measuring and continuously improving the current state of a company’s product development process. The task of continuously improving the performance demands the successful management of information, communication, cooperation and decision-making in a context of uncertainty, which is a highly complex task in itself. To be able to manage a complex product development system in an appropriate way, the authors have identified three important interdependent aspects of product development. The aspects are decision-making, uncertainty and performance. These aspects form the foundation for the suggested model which is intended to be used by engineering design researchers.
|
|
| 4. |
- Falkenback, Dan, et al.
(författare)
-
Is the course of gastroesophageal reflux disease progressive? A 21-year follow-up.
- 2009
-
Ingår i: Scandinavian Journal of Gastroenterology. - : Informa UK Limited. - 1502-7708 .- 0036-5521. ; 44:11, s. 1277-1287
-
Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE. We re-evaluated a cohort of patients referred for reflux symptoms and objectively diagnosed with pathological reflux, with the purpose of clarifying the course of conservatively treated gastroesophageal reflux disease (GERD). MATERIAL AND METHODS. All consecutive patients with GERD diagnosed between 1984 and 1988 showing pathologic 24-h pH-metry in the interval 3.8-10% and without any previous surgery in the gastroesophageal tract were assessed for further follow-up. A total of 40 evaluable patients were followed in the years 2007-08 with endoscopy, manometry, 24-h pH-metry, Helicobacter pylori assessment and the self-administered questionnaires the GERD Impact Scale, the Reflux Disease Questionnaire, the Quality of Life in Reflux and Dyspepsia and the Medical Outcome Study Short Form-36 Health Survey. Baseline data from the 1980s were retrieved and compared with the evaluations conducted at follow-up. RESULTS. At follow-up 20.7 years (range 18.8-23.5 years) after referral, the study population showed more use of acid suppressants (p = 0.007) and increasing prevalences of esophagitis (p = 0.001) and Barrett's esophagus (p = 0.002). Esophagitis was seen in 16/40 patients (40%) at baseline and in 29/40 (72.5%) at follow-up. No significant deterioration was seen at follow-up in manometry data and in most pH data. Patients with esophagitis (ERD) were less likely to have a positive H. pylori test (hazard ratio 0.054; p = 0.002) than non-erosive (NERD) patients. Symptom evaluations showed significantly lower quality of life in the ERD group. CONCLUSIONS. After 20 years a considerable part of the cohort still experienced symptoms of reflux and showed endoscopic progression, although no significant deteriorations were seen in manometry data and in most pH-metry data. H. pylori infection was inversely associated with erosive esophagitis and this supports the hypothesis that H. pylori colonization is a protective factor against GERD.
|
|
| 5. |
|
|
| 6. |
- Hjärtstam, Stefan, 1978, et al.
(författare)
-
Combustion characteristics of lignite-fired oxy-fuel flames
- 2009
-
Ingår i: Fuel. - : Elsevier BV. - 0016-2361. ; 88:11, s. 2216-2224
-
Tidskriftsartikel (refereegranskat)abstract
- This experimental work describes the combustion characteristics of lignite-fired oxy-fuel flames, in terms of temperature distribution, gas composition (O2, CO2, CO, total hydrocarbon concentration and NO) and ignition behaviour. The aim is to evaluate the flame structure of three oxy-fuel cases (obtained by changing the flue gas recycle rate) including a comparison with an air-fired reference case. Measurements were performed in Chalmers 100 kW test unit, which facilitates oxy-fuel combustion under flue gas recycling conditions. Temperature, O2 and CO concentration profiles and images of the flames indicate that earlier ignition and more intense combustion with higher peak temperatures follow from reduction of the recycle rate during oxy-fuel operation. This is mostly due to higher O2 concentration in the feed gas, reduced cooling from the recycled flue gas, and change in flow patterns between the cases. The air case and the oxy-fuel case with the highest recycle rate were most sensitive to changes in overall stoichiometry. Despite significant differences in local CO concentration between the cases, the stack concentrations of CO are comparable. Hence, limiting CO emissions from oxy-fuel combustion is not more challenging than during air-firing. The NO emission, as shown previously, was significantly reduced by flue gas recycling.
|
|
| 7. |
|
|
| 8. |
- Johansson, Jan, et al.
(författare)
-
Impact of Proton Pump Inhibitors on Benign Anastomotic Stricture Formations After Esophagectomy and Gastric Tube Reconstruction: Results From a Randomized Clinical Trial.
- 2009
-
Ingår i: Annals of Surgery. - 1528-1140.
-
Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE:: The primary aim of this study was to evaluate if the use of proton pump inhibitors (PPIs) reduced the prevalence of benign anastomotic strictures after uncomplicated esophagectomies with gastric tube reconstruction and circular stapled anastomoses. SUMMARY BACKGROUND DATA:: Benign anastomotic strictures are associated with anastomotic leaks or conduit ischemia. Also patients without those complications develop benign anastomotic strictures. We hypothesize that patients without postoperative anastomotic complications may develop benign anastomotic strictures due to exposure of acid gastric tube contents to the anastomotic area, and that the formation of such strictures may be reduced by prophylactic use of PPIs. METHODS:: Eighty patients without preoperative chemo- or radiotherapy, without clinical or radiological signs of anastomotic leaks were included in this clinical trial. The patients were randomized to b.i.d. PPIs or no treatment for 1 year. Benign anastomotic strictures were defined as anastomotic narrowing not allowing a standard diagnostic endoscope to pass without dilatation. The study was registered in the EudraCT database (2009-009997-28) for clinical trials. RESULTS:: Seventy-nine patients were evaluated. Benign anastomotic strictures developed in 5/39 (13%) patients in the PPI group and in 18/40 (45%) in the control group (RR 5.6, 95% CI: 2.0-15.9, P = 0.001). The use of a narrower 25 mm cartridge as compared to a wider 28 or 31 mm cartridge significantly increased stricture formations (RR 2.9, 95% CI: 1.1-7.6, P = 0.025). CONCLUSIONS:: Prophylactic PPI treatment reduced the prevalence of benign anastomotic strictures following esophagectomy with gastric tube reconstruction and circular stapled anastomoses. Larger sized circular staple cartridges additionally reduced the stricture prevalence.
|
|
| 9. |
- Johansson, Jan, et al.
(författare)
-
Two Different Surgical Approaches in the Treatment of Adenocarcinoma at the Gastroesophageal Junction.
- 2008
-
Ingår i: World Journal of Surgery. - : Springer Science and Business Media LLC. - 1432-2323 .- 0364-2313. ; 32, s. 1013-1020
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Adenocarcinoma at the gastroesophageal junction may be regarded as of esophageal or of gastric origin, and tumor removal may follow the principles of esophagectomy or extended gastrectomy. We determined the impact of this strategy on our patients with tumors at this site. METHODS: Baseline patient and tumor characteristics were collected, and tumors were categorized according to Siewert's classification (I, II, or III) of gastroesophageal junction tumors. Totally, 133 patients were operated on between 1990 and 2001. Ninety-six patients with type I (n = 67), II (n = 26), and III (n = 3) tumors underwent esophagectomy and gastric tube reconstruction, and 37 patients with type I (n = 5), II (n = 26), and III (n = 6) tumors underwent extended gastrectomy and long Roux-en-Y reconstructions. RESULTS: After adjusting for the independently significant impact factors-tumor stage, tumor dissection (R0-R2), and length of tumor free resection margins-we did not find any specific survival benefit associated with either of the two evaluated surgical approaches for tumor resection and reconstruction. The EORTC quality of life forms revealed good results as indicated by the functional scales and the symptom scales. CONCLUSIONS: Provided that adequate tumor dissection is performed, patients with adenocarcinoma at the gastroesophageal junction can be resected and reconstructed using the principles for esophagectomy or extended gastrectomy.
|
|
| 10. |
- Johnsson, Helena, et al.
(författare)
-
ICT support for industrial production of houses : the Swedish case
- 2007
-
Ingår i: Bringing ITC knowledge to work. - Maribor : Faculty of Civil Engineering. - 9789612480332 ; , s. 407-413
-
Konferensbidrag (refereegranskat)abstract
- The Swedish construction sector is currently undergoing great changes. The large costs for labour have forced the construction companies to rationalise and minimise labour intense work operations. Therefore, the current trend in construction to adopt the principles of lean production and transform it into lean construction, suits the Swed-ish way of working and the entire Swedish construction sector has caught on. A growing market is the prefabrication of building elements that are transported to site and then erected. The development has been taken so far that modular houses i.e. vol-umes/rooms are prefabricated. Companies in the prefabrication industry within construction fall between two sectors; the construction industry and the manufacturing industry. In terms of IT support the contradiction between the two sectors become evident. Software developed for the construction sector seldom provide enough detailing to suffice as a basis for industrial production, while software supporting the manufacturing industry are incapable of delivering standard construction documenta-tion. The current study presents a multiple case study where six Swedish industrial manu-facturers of timber houses were studied. The process from tender acceptance to mod-ule delivery is described. Alongside, a survey of the building sys-tem revealed that much still needs to be done in terms of documenting a building system. The results show that the ques-tion of IT support is more a question of consequent information strategies than eloquent IT tools. The pressing need for a method for documenting building systems is stressed and different methods are discussed.
|
|
