| 1. |
- Sadrizadeh, Sasan, et al.
(författare)
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Numerical simulation of the impact of surgeon posture on airborne particle distribution in a turbulent mixing operating theatre
- 2016
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Ingår i: Building and Environment. - : Elsevier. - 0360-1323 .- 1873-684X. ; 110, s. 140-147
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Tidskriftsartikel (refereegranskat)abstract
- Airborne particles released from surgical team members are major sources of surgical site infections. To reduce the risk of such infections, ultraclean-zoned ventilation systems have been widely applied, as a complement to the ventilation of the main operating theatre. The function of ventilation in an operating theatre is usually determined without considering the influence of the staff members' posture and movements. The question of whether the surgeon's posture during an on-going operation will influence particle distribution within the surgical area has not yet been explored in depth or well documented. In the present study we analysed data from investigation of two positions (bending and straightened up), which represent the most common surgeon and staff-member postures. The investigation was performed by applying the computational fluid dynamics methodology to solve the governing equations for airflow and airborne particle dispersion. Ultraclean-zoned ventilation systems were examined as an addition to the conventional operating theatre. We examined three distinct source strengths (mean value of pathogens emitted from one person per second) due to the variety of staff clothing systems. In the upright posture, the screen units reduced the mean air counts of bacteria and the mean counts of sedimenting bacteria to a standard level for infection-prone surgeries in the surgical area. However, the performance of this system could be reduced drastically by improper Work experience. Surgical garments with a high protective capacity result in lower source strength and thus reduces the particle concentration within the surgical area. These results are useful for developing best practices to prevent or at least reduce the infection rate during a surgical intervention.
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| 2. |
- Bagheri, Azam, et al.
(författare)
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Improved characterization of multi-stage voltage dips based on the space phasor model
- 2018
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Ingår i: Electric power systems research. - : Elsevier. - 0378-7796 .- 1873-2046. ; 154, s. 319-328
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Tidskriftsartikel (refereegranskat)abstract
- This paper proposes a method for characterizing voltage dips based on the space phasor model of the three phase-to-neutral voltages, instead of the individual voltages. This has several advantages. Using a K-means clustering algorithm, a multi-stage dip is separated into its individual event segments directly instead of first detecting the transition segments. The logistic regression algorithm fits the best single-segment characteristics to every individual segment, instead of extreme values being used for this, as in earlier methods. The method is validated by applying it to synthetic and measured dips. It can be generalized for application to both single- and multi-stage dips.
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| 3. |
- Pettersson, Anita, et al.
(författare)
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Chemical fractionation for the characterisation of fly ashes from co-combustion of biofuels using different methods for alkali reduction
- 2009
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Ingår i: Fuel. - : Elsevier BV. - 0016-2361 .- 1873-7153. ; 88:9, s. 1758-1772
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Tidskriftsartikel (refereegranskat)abstract
- a b s t r a c tChemical fractionation, SEM–EDX and XRD was used for characterisation of fly ashes from different cocombustiontests in a 12MW circulating fluidized bed boiler. The fuels combusted were wood pellets asbase fuel and straw pellets as co-fuel in order to reach a fuel blend with high alkali and chlorine concentrations.This fuel blend causes severe problems with both agglomeration of bed material if silica sand isused and with deposits in the convection section of the boiler. Counter measures to handle this situationand avoiding expensive shut downs, tests with alternative bed materials and additives were performed.Three different bed materials were used; silica sand, Olivine sand and blast furnace slag (BFS) and differentadditives were introduced to the furnace of the boiler; Kaolin, Zeolites and Sulphur with silica sand asbed material. The results of the study are that BFS gives the lowest alkali load in the convection pass comparedwith Silica and Olivine sand. In addition less alkali and chlorine was found in the fly ashes in theBFS case. The Olivine sand however gave a higher alkali load in the convection section and the chemicalfractionation showed that the main part of the alkali in the fly ashes was soluble, thus found as KCl whichwas confirmed by the SEM–EDX and XRD.The comparison of the different additives gave that addition of Kaolin and Zeolites containing aluminium-silicates captured 80% of the alkali in the fly ash as insoluble alkali–aluminium-silikates and reducedthe KCl load on the convection section. Addition of sulphur reduced the KCl load in the flue gas even morebut the K2SO4 concentration was increased and KCl was found in the fly ashes anyhow. The chemical fractionationshowed that 65% of the alkali in the fly ashes of the Sulphur case was soluble.
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| 4. |
- Karimipanah, Taghi, 1953-
(författare)
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Deflection of wall-jets in ventilated enclosures described by pressure distribution
- 1998
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Ingår i: Building and Environment. - 0360-1323 .- 1873-684X. ; 34:3, s. 329-333
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Tidskriftsartikel (refereegranskat)abstract
- The pressure field in fluid systems reflects the flow configuration. Measurements of the pressure along the perimeter of a slot ventilated room have been conducted for different room sizes. The momentum of the jet at the end of the room is decreased with increasing room length. The impingement region (region where the influence of the opposing wall is present) starts, independent of room size, when the distance from the supply device is about 70% of the room length. Corner flows could not be predicted by CFD using the linear eddy viscosity or standard stress models. However, these effects may be captured by using a second moment closure turbulence model with a new near wall approach now available in literature.
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| 5. |
- Karimipanah, Taghi, 1953-, et al.
(författare)
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Investigation of air quality, comfort parameters and effectiveness for two floor-level air supply systems in classrooms
- 2007
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Ingår i: Building and Environment. - : Elsevier BV. - 0360-1323 .- 1873-684X. ; 42:2, s. 647-655
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Tidskriftsartikel (refereegranskat)abstract
- The method of distributing the outdoor air in classrooms has a major impact on indoor air quality and thermal comfort of pupils. In a previous study, ([11] Karimipanah T, Sandberg M, Awbi HB. A comparative study of different air distribution systems in a classroom. In: Proceedings of Roomvent 2000, vol. II, Reading, UK, 2000. p. 1013-18; [13] Karimipanah T, Sandberg M, Awbi HB, Blomqvist C. Effectiveness of confluent jets ventilation system for classrooms. In: Idoor Air 2005, Beijing, China, 2005 (to be presented).) presented results for four and two types of air distribution systems tested in a purpose built classroom with simulated occupancy as well as computational fluid dynamics (CFD) modelling. In this paper, the same experimental setup has been used to investigate the indoor environment in the classroom using confluent jet ventilation, see also ([12] Cho YJ, Awbi HB, Karimipanah T. The characteristics of wall confluent jets for ventilated enclosures. In: Proceedings of Roomvent 2004, Coimbra, Portugal, 2004.) Measurements of air speed, air temperature and tracer gas concentrations have been carried out for different thermal conditions. In addition, 56 cases of CFD simulations have been carried to provide additional information on the indoor air quality and comfort conditions throughout the classroom, such as ventilation effectiveness, air exchange effectiveness, effect of flow rate, effect of radiation, effect of supply temperature, etc., and these are compared with measured data.
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| 6. |
- Karimipanah, Taghi, 1953-, et al.
(författare)
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Theoretical and experimental investigation of impinging jet ventilation and comparison with wall displacement ventilation
- 2002
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Ingår i: Building and Environment. - 0360-1323 .- 1873-684X. ; 37:12, s. 1329-1342
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Tidskriftsartikel (refereegranskat)abstract
- This paper focuses on evaluating the performance of a new impinging jet ventilation system and compares its performance with a wall displacement ventilation system. Experimental data for an impinging jet in a room are presented and non-dimensional expressions for the decay of maximum velocity over the floor are derived. In addition, the ventilation efficiency, local mean age of air and other characteristic parameters were experimentally and numerically obtained for a mock-up classroom ventilated with the two systems. The internal heat loads from 25 person-simulators and lighting were used in the measurements and simulations to provide a severe test for the two types of ventilation systems. In addition to a large number of experimental data CFD simulations were used to study certain parameters in more detail. The results presented here are part of a larger research programme to develop alternative and efficient systems for room ventilation.
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| 7. |
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| 8. |
- Eriksson, Anders, 1953-
(författare)
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Criteria for optimality in movements
- 2006
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Ingår i: Journal of Biomechanics. - 0021-9290 .- 1873-2380. ; 39:s1, s. S54-S54
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Tidskriftsartikel (refereegranskat)
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| 9. |
- Eriksson, Anders, 1953-, et al.
(författare)
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Engineering computational technology
- 2007
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Ingår i: Advances in Engineering Software. - : Elsevier BV. - 0965-9978 .- 1873-5339. ; 38:11-12, s. 723-725
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Tidskriftsartikel (refereegranskat)
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| 10. |
- Niklasson, Gunnar, 1953-, et al.
(författare)
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Electrochromic and Thermochromic Oxide Materials
- 2019
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Ingår i: Applied Surface Science. - : Elsevier BV. - 0169-4332 .- 1873-5584. ; 482, s. 70-72
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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