| 1. |
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| 2. |
- Westerberg, Martin, et al.
(författare)
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Hemodynamic effects of cardiotomy suction blood.
- 2006
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Ingår i: The Journal of thoracic and cardiovascular surgery. - : Elsevier BV. - 1097-685X .- 0022-5223. ; 131:6, s. 1352-7
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: Cardiac surgery induces a systemic inflammatory activation, which in severe cases is associated with peripheral vasodilation and hypotension. Cardiotomy suction blood contains high levels of inflammatory mediators, but the effect of cardiotomy suction blood on the vasculture is unknown. We investigated the effect of cardiotomy suction blood on systemic vascular resistance in vivo and whether cell-saver processing of suction blood affects the vascular response. METHODS: Twenty-five patients undergoing coronary surgery (mean age, 68 +/- 2 years; 80% men) were included in a prospective randomized study. The patients were randomized to retransfusion of cell-saver processed (n = 13) or cell-saver unprocessed (n = 12) suction blood during full cardiopulmonary bypass. Mean arterial blood pressure was continuously registered during retransfusion, and systemic vascular resistance was calculated. Plasma concentrations of tumor necrosis factor alpha, interleukin 6, and complement factor C3a were measured in suction blood. RESULTS: Retransfusion of cardiotomy suction blood induced a transient reduction in systemic vascular resistance in all patients. The peak reduction was significantly less pronounced in the group receiving cell-saver processed blood (-12% +/- 2% vs -28% +/- 3%, P = .001). There was a significant correlation between tumor necrosis factor alpha concentration in retransfused cardiotomy suction blood and peak reduction of systemic vascular resistance (r = 0.60, P = .002). CONCLUSIONS: The results suggest cardiotomy suction blood is vasoactive and might influence vascular resistance and blood pressure during cardiac surgery. The observed vasodilation is proportional to the inflammatory activation of suction blood and can be reduced by processing suction blood with a cell-saving device before retransfusion.
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| 3. |
- Abbasi, Saeed, et al.
(författare)
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A pin-on-disc study of the rate of airborne wear particle emissions from railway braking materials
- 2012
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Ingår i: Wear. - UK : Elsevier. - 0043-1648 .- 1873-2577. ; 284, s. 18-29
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Tidskriftsartikel (refereegranskat)abstract
- The current study investigates the characteristics of particles generated from the wear of braking materials, and provides an applicable index for measuring and comparing wear particle emissions. A pin-on-disc tribometer equipped with particle measurement instruments was used. The number concentration, size, morphology, and mass concentration of generated particles were investigated and reported for particles 10 nm-32 mu m in diameter. The particles were also collected on filters and investigated using EDS and SEM. The effects of wear mechanisms on particle morphology and changes in particle concentration are discussed. A new index, the airborne wear particle emission rate (AWPER), is suggested that could be used in legislation to control non-exhaust emissions from transport modes, particularly rail transport.
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| 4. |
- Abbasi, Saeed, 1973-, et al.
(författare)
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A field test study of airborne wear particles from a running regional train
- 2012
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Ingår i: IMechE, Part F: Journal of Rail and Rapid Transit. - UK : Sage Publications. - 0954-4097 .- 2041-3017. ; 226:1, s. 95-109
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Tidskriftsartikel (refereegranskat)abstract
- Inhalable airborne particles have inverse health affect. In railways, mechanical brakes, the wheel–rail contact, current collectors, ballast, sleepers, and masonry structures yield particulate matter. Field tests examined a Swedish track using a train instrumented with particle measurement devices, brake pad temperature sensors, and speed and brake sensors. The main objective of this field test was to study the characteristics of particles generated from disc brakes on a running train with an on-board measuring set-up.Two airborne particle sampling points were designated, one near a pad–rotor disc brake contact and a second under the frame, not near a mechanical brake or the wheel–rail contact; the numbers and size distributions of the particles detected were registered and evaluated under various conditions (e.g. activating/deactivating electrical brakes or negotiating curves). During braking, three speed/temperature-dependent particle peaks were identified in the fine region, representing particles 280 nm, 350 nm, and 600 nm in diameter. In the coarse region, a peak was discerned for particles 3–6 μm in diameter. Effects of brake pad temperature on particle size distribution were also investigated. Results indicate that the 280 nm peak increased with increasing temperature, and that electrical braking significantly reduced airborne particle numbers. FESEM images captured particles sizing down to 50 nm. The ICP-MS results indicated that Fe, Cu, Zn, Al, Ca, and Mg were the main elements constituting the particles.
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| 5. |
- Abbasi, Saeed, et al.
(författare)
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Particle emissions from rail traffic : a literature review
- 2013
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Ingår i: Critical reviews in environmental science and technology. - USA : Taylor & Francis. - 1064-3389 .- 1547-6537. ; 43:23, s. 2211-2244
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Forskningsöversikt (refereegranskat)abstract
- Particle emissions are a drawback of rail transport. This work is a comprehensive presentation of recent research into particle emissions from rail vehicles. Both exhaust and non-exhaust particle emissions are considered when examining particle characteristics such as PM10, and PM2.5 concentration levels, size, morphology, composition, as well as adverse health effects, current legislation, and available and proposed solutions for reducing such emissions. High concentration levels in enclosed rail traffic environments are reported and some toxic effects of the particles. We find that only a few limited studies have examined the adverse health effects of non-exhaust particle emissions and that no relevant legislation exists. Thus further research in this area is warranted.
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| 6. |
- Addie, Graeme, et al.
(författare)
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Pipeline design characteristics of some industrial paste-like slurries
- 2005
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Ingår i: Conference Proceedings - First Extractive Metallurgy Operators' Conference. - : The Australian Institute of Mining and Metallurgy. ; , s. 147-154
-
Konferensbidrag (refereegranskat)abstract
- There is a wide variety of industrial pastes or non-settling slurries pumped in mining, dredging and reclamation projects as products, refuse and tails. The types and/or names of some of the common ones are alumina red mud, phosphate clays, tar sands mature fine tails, tar sands (CT) consolidated clays and fly ash. The pipeline performance or friction of these varies dramatically with the type, its concentration and the particulars of the actual slurry making it difficult to select pumping equipment and to design associated pipelines. The GIW Hydraulic Laboratory in Grovetown Georgia has tested a number of these slurries over the last 30 years for various mining customers. Where available in the public domain and/or where permission has been obtained, the results of those tests are presented in this paper in a form usable for pipeline and pump system designers and users.
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| 7. |
- Addie, Graeme R., et al.
(författare)
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A first slurry standard and some implications for paste application
- 2007
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Ingår i: Paste 2007. - Perth : Australian Centre for Geomechanics. - 975675656 ; , s. 153-162
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Konferensbidrag (refereegranskat)abstract
- The Hydraulic Institute has just completed the task of developing a new ANSI/HI standard on Rotodynamic (Centrifugal) Slurry Pumps covering nomenclature, definitions, applications, and operation. The standard provides examples of all the different types of pumps available and has an extensive section on definitions. Slurries and their effect on performance and wear are covered. A slurry service class is established which then is used to limit velocities and head produced per pump to give acceptable wear. A special section deals with mechanical seals and a new method for determining flange loads is presented and guidelines are given for commissioning, start-up etc.The head limits and the performance derating are of special interest when centrifugal slurry pumps are applied to thickened tailings and paste-like slurries. For Newtonian liquids, the Hydraulic Institute's Viscosity Correction Method (ANSI/HI 2004) provides a procedure widely used for viscous effects on the performance. For the homogeneous flow of viscous slurries, the new slurry standard refers to an applicable viscosity to use with the method and to "consult the pump manufacturer for guidance regarding non-Newtonian slurry pump performance."Experimental performance results are presented here and applied to the viscosity correction method for a simulated tailings product slurry characterized by a fully sheared yield stress of about 100 Pa, evaluated from pipeline data. The pump was a GIW-LCC type three-vane all metal unit with a 0.3m-diameter impeller having an open shroud with a simple auger-like inducer. Results are also given for an underground hydraulic fill product characterized by a Newtonian kinematic viscosity which is 1300 times that for water. The different results obtained here point out the strong influence the rheological behavior has on the choice of pump size and the power requirement.
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| 8. |
- Addie, Graeme R., et al.
(författare)
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Design, selection, sizing and control considerations for cyclone feed slurry pumps
- 1999
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Ingår i: Powder Technology. - 0032-5910 .- 1873-328X. ; 104:3, s. 233-239
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Tidskriftsartikel (refereegranskat)abstract
- Cyclone feed centrifugal slurry pumps in semi-autogenous grinding (SAG) mill and other cyclone feed circuits see coarse size slurries at high concentrations that can result in high wear if the pump is not designed, selected, sized and operated correctly. The high proportion of static head of the normal cyclone feed circuits usually results in a relatively flat system curve which in conjunction with the typically flat slurry pump curve results in large changes in operating flow with small changes in system head. When this is combined with the normal (or abnormal) fluctuations in the output from the mill upstream of the pumps, any shortcomings in the pump control system and/or matching of the pump means large fluctuations in flow and increased wear. This difficulty could be corrected by continuous variations in speed. A means of control by which the speed is changed in an appropriate way is suggested here. In this case then the pump-input power, the known water performance of the pump and the system flow, can be used to calculate an effective pump discharge pressure. By comparison with a calculated system head, the pump speed can be regulated such that the pressures are equal and the system stable for any practical variation of incoming flow or specific gravity.
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| 9. |
- Addie, Graeme R., et al.
(författare)
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The new ANSI/HI centrifugal slurry pump standard
- 2007
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Ingår i: South African Institute of Mining and Metallurgy. - 0038-223X. ; 107:6, s. 403-409
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Tidskriftsartikel (refereegranskat)abstract
- The Hydraulic Institute has completed the task of developing a new ANSI/HI standard 12.1-12.6 (2005) for Rotodynamic (Centrifugal) Slurry Pumps covering nomenclature, definitions, applications, and operation. The standard provides examples of the different slurry pump types and contains an extensive section on pump and slurry definitions. The effect of slurry on pump performance is covered along with the pumping of froth. Reference is also made to ANSI/HI standard 9.6.7 (2004), which contains a new method for pump performance correction when handling viscous fluids.Classification of slurry services is established and then is used to determine limitations on velocities and total head per pump in order to obtain acceptable wear performance. The new service class, head per stage and other limits are directly related to capital and other cost considerations that will affect solids transport system economics. The writers review the contents of the new standard, highlight the main points, and discuss the reason for the slurry classification, corresponding limits and expected implications, particularly with respect to operating costs of the pumps in solids transport systems.
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| 10. |
- Addie, G.R., et al.
(författare)
-
Weir Minerals North America
- 2007
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Ingår i: Hydrotransport 17. - : South African Institute of Mining and Metallurgy. - 9781920211028 - 9781855980846 ; , s. 205-218
-
Konferensbidrag (refereegranskat)abstract
- The Hydraulic Institute has completed the task of developing a new ANSI/HI standard 12.1-12.6 (2005) for rotodynamic (centrifugal) slurry pumps covering nomenclature, definitions, applications, and operation. The standard provides examples of the different slurry pump types and contains an extensive section on pump and slurry definitions. The effect of slurry on pump performance is covered along with the pumping of froth. Reference is also made to ANSI/HI standard 9.6.7 (2004), which contains a new method for pump performance correction when handling viscous fluids. Classification of slurry services is established and then is used to determine limitations on velocities and total head per pump in order to obtain acceptable wear performance. The new service class, head per stage and other limits are directly related to capital and other cost considerations that will affect solids transport system economics. The writers review the contents of the new standard, highlight the main points, and discuss the reason for the slurry classification, corresponding limits and expected implications, particularly with respect to operating costs of the pumps in solids transport systems
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| 11. |
- Andersson, Kjell, 1959-, et al.
(författare)
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A flexible chain proposal for winch based point absorbers
- 2018
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Ingår i: Proceedings of the ASME 2018 International Design Engineering Technical Conferences & Computers and Information in Engineering Conference IDETC/CIE 2018.
-
Konferensbidrag (refereegranskat)abstract
- Ocean wave power is a promising renewable energy source for future energy production. It has however been difficult to find a cost-effective solution to convert the wave energy into electricity. The harsh marine environment and the fact that wave power is delivered with high forces at low speeds makes design of durable mechanical structures and efficient energy conversion challenging. The dimensioning forces strongly depend on the wave power concept, the Wave Energy Converter (WEC) implementation and the actual Power TakeOff (PTO) system. A WEC using a winch as a Power Take-Off system, i.e. a Winch Based Point Absorber (WBPA), could potentially accomplish a low Levelized Cost Of Energy (LCOE) if akey component - a low-cost, durable and efficient winch that can deal with high loads - can be developed. A key problem for achieving a durable winch is to find a force transmitting solution that can deal with these high loads and handle up to 80 million cycles. In this article we propose a design solution for a force transmitting chain in a WBPA system where elastomeric bearings are used as a means to achieve the relative motion between the links in the chain. With this solution no sliding is present and the angular motion is achieved as a deformation in the elastomeric bearing when the chain is winded on a drum. The link was designed primarily to minimize the number of joints in the chain: Thereby the maximum allowed relative angle between the links when rolled up over the drum should be as large as possible within practical limits. The angle is to be handled by the elastomeric bearing. A detailed strength analysis of the link has been performed as well as topology optimization to increase the strength to weight ratio. A test rig for a first proof of concept testing has been developed and the first preliminary test results indicate that this concept with using elastomeric bearings can be a potential solution for a durable chain and should be analyzed further for fatigue conditions and under water operations.
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| 12. |
- Andersson, Kjell, 1959-, et al.
(författare)
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A Flexible Chain Proposal for Winch-Based Point Absorbers
- 2019
-
Ingår i: Journal of mechanical design (1990). - : ASME. - 1050-0472 .- 1528-9001. ; 141:10
-
Tidskriftsartikel (refereegranskat)abstract
- Ocean wave power is a promising renewable energy source. It has, however, been difficult to find a cost-effective solution to convert wave energy into electricity. The harsh marine environment and the fact that wave power is delivered with large forces at low speed make design of durable mechanical structures and efficient energy conversion challenging. The dimensioning forces strongly depend on the wave power concept, the wave energy converter (WEC) implementation, and the actual power take-off (PTO) system. A WEC with a winch as a power take-off system, i.e., a winch-based point absorber (WBPA), could potentially enable a low levelized cost of energy (LCOE) if a low-cost, durable and efficient winch that can deal with peak loads can be developed. A key challenge for realizing such a winch is to find a force transmitting solution that can deal with these peak loads and that can handle up to 80 million cycles during its life. In this article, we propose a design solution for a force transmitting chain with elastomer bearings connecting the links of the chain. With this solution no sliding is present, and the angular motion is realized as elastic shear deformations in the elastomer bearings when the chain is wound onto the winch drum. The elastomer bearings were designed for low shear stiffness and high compression stiffness, and the links were designed primarily to minimize the number of joints in the chain. Thereby, the maximum allowed relative angle between the links when rolled up over the drum should be as large as possible within practical limits. Finite element-based topological optimization was performed with the aim to increase the link strength to weight ratio. A test rig for a first proof of concept testing has been developed, and preliminary test results indicate that this chain concept with elastomer bearings can be a potential solution for a durable chain and should be analyzed and tested further for fatigue and sea operations.
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| 13. |
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| 14. |
- Andreasson, Patrik, et al.
(författare)
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River flow with excessive suspended sediment load : an evaluation of turbulent flow characteristics
- 1986
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Ingår i: Nordic Hydrology. - : IWA Publishing. - 0029-1277 .- 1996-9694. ; 17:4-5, s. 383-390
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Tidskriftsartikel (refereegranskat)abstract
- River flows with high volume concentrations (20-50%) of silty sediments generally imply that the mixture has non-Newtonian properties. In this study, the rheological behavior of mixtures with solids particles smaller than 0. 1 mm was identified experimentally with viscosimeters. Characteristic flow parameters, such as energy losses and depths, were then determined in several examples for turbulent open channel flows.
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| 15. |
- Engman, M., et al.
(författare)
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Some design considerations of high density base metal tailings handling systems
- 2004
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Ingår i: Proceedings of the 12th international conference on Transport & sedimentation of solid particles joined with 12th international symposium on Freight pipelines. - Prague : Institute of Hydrodynamics, Academy of Sciences of the Czech Republic. - 8023934651 ; , s. 307-318
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Konferensbidrag (refereegranskat)
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| 16. |
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| 17. |
- Engström, Maria, 1974-
(författare)
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Secondary currents in groundwater
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The thesis concerns the small vertical water movements created by thermal convection and the Coriolis force acting on groundwater flows. These small flows are of importance to vertical transports of temperature, nutrients and contaminants that would not be spread in the way they are. The first part analyzes thermally driven, seasonal groundwater convection by numerical simulation. The second part shows that the Coriolis force also induces secondary currents in groundwater flow through different vertical permeability distributions. Density driven convection occurs during the autumn in southern Sweden when the ambient air temperature cools the mean groundwater temperature from about 10ºC. When the shallow groundwater is cooled by the ambient air its increased density makes this water sink, slowly increasing in temperature, while pressing the warmer water upwards creating a convection cell. The process is ongoing as long as there is a thermal gradient between ground surface and the groundwater. Under favorable conditions convection can reach a depth of 6m. Such density-driven water movements occur most easily in more permeable soil. In northern Sweden, the situation is reversed, since the mean groundwater temperature is below 4ºC, at which water is at its density maximum. So, in springtime when the uppermost groundwater is heated to 4ºC by the warmer air the convection process starts. Here, the sinking groundwater does not reach the same depth, less than one meter. The Coriolis force has been considered too small to have any effect on groundwater flow, though its importance in meteorology and oceanography is well established. These theories have been applied using numerical simulations of groundwater flow. The numerical model has been validated by simulating some earlier studies of Coriolis forces in fluids. Furthermore the model has been extended to include porous media. It has been shown that secondary currents occur in nonlinear vertical permeability distributions. For simulations of constant and linear distributions no secondary currents have been seen. The development is more pronounced in confined aquifers. The structure of the bottom of the aquifer affects how the secondary currents arise. It was shown that both temperature gradients and the Coriolis force form secondary currents in groundwater and a general conclusion is that groundwater flow is more complex than previously assumed.
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| 18. |
- Eriksson, B., et al.
(författare)
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Development of slurry transportation technology in Sweden
- 1978
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Ingår i: Pipes and Pipelines International. - 0370-1204. ; 23:6, s. 10-13
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Tidskriftsartikel (refereegranskat)abstract
- A system-oriented development project has been started by the LKAB mining company and Chalmers University of Technology (CTH), in co-operation with manufacturers and inventors. The development work has concentrated on improvements of some components and better understanding of specific problems, which, seen together, are believed to be of great interest in slurry transportation applications. So far, a rubber-lined plastic pipe for high-pressure applications has been developed, and a high-pressure pump without large external devices and with a minimum of moving parts is to be patented. Simultaneous laboratory and in-plant tests of the new components have been started, and studies on freezing problems, chemical additives, and secondary flow have also been carried out. A pilot-plant investigation on hydraulic hoisting of heavy ore by centrifugal pumps has been completed at CTH.
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| 19. |
- Folkeson, Anders, et al.
(författare)
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A conference on engineering design is a complex product
- 2004
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Ingår i: Design 2004. - 9536313596 ; , s. 1355-1362
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Konferensbidrag (refereegranskat)abstract
- Many of the challenges in organising and developing an international engineering conference under severe time and cost constraints are similar to those involved developing a complex technical artefact. The large number of authors and reviewers who are active in the process and the just-in-time character of their deliveries further complicate the task. This paper describes and analyses the experience of developing a recent international conference on engineering design from a product development perspective. Key factors for developing a successful conference are analysed. The main purpose is to provide future conference organisers with recommendations to help promote successful and rewarding conferences.
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| 20. |
- Furlan, John M., et al.
(författare)
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Centrifugal pump performance when handling highly non-Newtonian clays and tailings slurries
- 2014
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Ingår i: 19th International Conference on Hydrotransport 2014. - : Curran Associates, Inc.. - 9781634394444 ; , s. 117-130
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Konferensbidrag (refereegranskat)abstract
- Recent loop testing performed at the GIW Hydraulic Lab (Furlan et al. 2013, 2014) has provided pump performance data for two highly non-Newtonian slurries of significantly different character: a high clay content slurry with minimal coarse solids; and a typical, low clay content, two component tailings slurry. The importance of air removal in the sump and pipe loop was demonstrated using a simple, yet novel de-aeration system. In addition to the measurement of performance losses, determination of the upper limit of "pumpability" for these slurries relative to their concentration and associated yield stress was investigated. However, once the slurry was de-aerated, no limits could be found, other than those dictated by suction side losses (NPSHA) or excessive pipeline friction gradients, indicating that the only true limit in practice is one of system economics, i.e. pump operating and capital cost. Experimentally measured pump head and efficiency were compared against corresponding predictions from two different models: the Walker and Goulas technique (Walker and Goulas, 1983), and the Graham et al. technique (Graham et al., 2009), with special focus given to the dependence of the losses on pump rotary speed.
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| 21. |
- Furlan, John M., et al.
(författare)
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Centrifugal pump performance when handling highly non-Newtonian clays and tailings slurries
- 2016
-
Ingår i: Canadian Journal of Chemical Engineering. - : Wiley. - 0008-4034 .- 1939-019X. ; 94:6, s. 1108-1115
-
Tidskriftsartikel (refereegranskat)abstract
- Recent loop testing performed at the GIW Hydraulic Lab (Furlan et al. 2013, 2014) has provided pump performance data for two highly non-Newtonian slurries of significantly different character: a high clay content slurry with minimal coarse solids; and a typical, low clay content, two component tailings slurry. The importance of air removal in the sump and pipe loop was demonstrated using a simple, yet novel de-aeration system. In addition to the measurement of performance losses, determination of the upper limit of "pumpability" for these slurries relative to their concentration and associated yield stress was investigated. However, once the slurry was de-aerated, no limits could be found, other than those dictated by suction side losses (NPSHA) or excessive pipeline friction gradients, indicating that the only true limit in practice is one of system economics, i.e. pump operating and capital cost. Experimentally measured pump head and efficiency were compared against corresponding predictions from two different models: the Walker and Goulas technique (Walker and Goulas, 1983), and the Graham et al. technique (Graham et al., 2009), with special focus given to the dependence of the losses on pump rotary speed.
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| 22. |
- Furlan, J., et al.
(författare)
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Pipe loop testing of a mixture containing fine, dense solids with magnetic properties
- 2019
-
Ingår i: 19th International Conference on Transport & Sedimentation of Solid Particles. - : Wydawnictwo Uniwersytetu Przyrodniczego we Wrocławiu (Wrocław University of Environmental and Life Sciences). ; , s. 23-29
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Tests were performed in the GIW Hydraulic Laboratory on a milled copper slag tailings slurry in pipe loops with 75 and 100 mm diameter loss sections. Volumetric concentrations of 1 to 14% were tested in the 100 mm loop, and the initial results, derived using magnetic flow meter measurements, showed pressure losses approximately equal to that of water. Chemical Testing of the solid particles was performed, and they were found to be made up of 56% magnetite by weight. Magnetite has been found in the past (Sonar Trac paper) to effect magnetic flow meter measurements, which was the primary method being used in this test program. Secondary measurements using a Sonar Trac instrument indicated, in contrast, the more common and expected equivalent fluid behavior in the 4” loop at the lower concentrations, where the losses, when expressed in height of slurry, now landed on top of the carrier liquid curve, which was found to be equal to that of water. A comparison between the measurements from the magnetic flow meter, and those from the sonar trac, showed a linear dependency between the flow rate ratio (between the magnetic flow meter measurement and the sonar trac measurement) and the solids concentration. These tests illustrate the importance of having knowledge of the makeup of the solid particles in a slurry, and the utility of acoustic based flow rate measurement methods in cases where magnetite (or other solids particles with magnetic properties) particles are present within the slurry.
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| 23. |
- Hagnestål, Anders, 1976-, et al.
(författare)
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Durable winch-based point absorbers
- 2017
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Ingår i: Proceedings of the 12th European Wave and Tidal Energy Conference 27th Aug - 1st Sept 2017, Cork, Ireland. - : European Wave and Tidal Energy Conference.
-
Konferensbidrag (refereegranskat)abstract
- Wave power could give a significant contribution to afuture sustainable energy system if the Levelized Cost Of Energycan be reduced to a competitive level. Winch-based pointabsorbers could potentially accomplish this if a key component –a low-cost, durable and efficient winch that can deal with highloads – can be developed. In this article the possibilities of winchbasedpoint absorbers and the challenges that need to beovercome are described. Further, the possibilities to design suchwinches are explored and several different design approaches areevaluated and compared. At present, we believe that such awinch solution can be found although more research is needed todevelop a full concept, and the most promising solutions so farinvolve inverted tooth chains, flat UHMwPE fiber (Dyneema)bands and flat carbon fibre structures.
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| 24. |
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| 25. |
- Häggström, Daniel
(författare)
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On synchronization of heavy truck transmissions
- 2016
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Gear shifts are becoming more and more important as engines are adapted to low speed high torque working conditions. Synchronizers are key components for successful gear shifts. To adapt the synchronizers to new working conditions due to adaptations to new engines, improved development tools are needed. The presented thesis describes the development of two types of numerical models for the synchronization process, namely fluid-structure interaction to simulate the pre-synchronization phase and thermomechanical FE models to simulate the main synchronization phase. A methodology for developing friction models based on a combination of physical testing and numerical simulations is presented. Additionally, a comprehensive gear shift and synchronizer frame of reference section is presented.In paper A, two numerical fluid-structure interaction simulation models for assessing the pre-synchronization phase are presented. Simulations show that the synchronizer functionality is highly dependent on the gear shift maneuvering system, and that grooves in the synchronizer surface have a positive effect on the oil evacuation during the pre-synchronization phase.Paper B describes the development of a numerical thermomechanical model for simulating the main synchronization phase. Two parameter studies were performed, one based on external loads and one based on synchronizer geometry. The effect on the temperature increase from differences in thermal properties between molybdenum and carbon friction linings are presented.In paper C, a verification and validation methodology for highly transient thermomechanical processes was presented. Numerical verification, bulk temperature measurement, surface temperature measurement and qualitative visual inspection were combined to verify and validate the simulation model presented in paper B.In paper D, a methodology combining physical testing with an thermomechanical simulation model to develop a friction model was exemplified by a molybdenum coated synchronizer. A simplified thermal model was developed to remove the dependence of full finite element thermal models. The friction models shows good agreement with measured data.
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| 26. |
- Höstman, Staffan, et al.
(författare)
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Non-toxic alveolar oxygen concentration without hypoxemia during apnoeic oxygenation : an experimental study
- 2011
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Ingår i: Acta Anaesthesiologica Scandinavica. - : Wiley. - 0001-5172 .- 1399-6576. ; 55:9, s. 1078-1084
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Tidskriftsartikel (refereegranskat)abstract
- Background: Oxygenation without tidal breathing, i.e. apnoeic oxygenation in combination with extracorporeal carbon dioxide removal, might be an option in the treatment of acute respiratory failure. However, ventilation with 100% O(2), which is potentially toxic, is considered a prerequisite to ensure acceptable oxygenation. We hypothesized that trapping nitrogen (N(2)) in the lungs before the start of apnoeic oxygenation would keep the alveolar O(2) at a non-toxic level and still maintain normoxaemia. The aim was to test whether a predicted N(2) concentration would agree with a measured concentration at the end of an apnoeic period. Methods: Seven anaesthetized, muscle relaxed, endotracheally intubated pigs (22-27 kg) were ventilated in a randomized order with an inspired fraction of O(2) 0.6 and 0.8 at two positive end-expiratory pressure levels (5 cm and 10 cm H(2)O) before being connected to continuous positive airway pressure using 100% O(2) for apnoeic oxygenation. N(2) was measured before the start of and at the end of the 10-min apnoeic period. The predicted N(2) concentration was calculated from the initial N(2) concentration, the end-expiratory lung volume, and the anatomical dead space. Results: The mean difference and standard deviation between measured and predicted N(2) concentration was -0.5 +/- 2%, P = 0.587. No significant difference in the agreement between measured and predicted N(2) concentrations was seen in the four settings. Conclusions: This study indicates that it is possible to predict and keep alveolar N(2) concentration at a desired level and, thus, alveolar O(2) concentration at a non-toxic level during apnoeic oxygenation.
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| 27. |
- Lagerlund, Johan, 1979-, et al.
(författare)
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Permeation grouting laboratory testing for embankment dams – a note on flow resistance
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Ingår i: Geotechnical Research. - 2052-6156.
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Tidskriftsartikel (refereegranskat)abstract
- During suffusion in embankment dams, fine material from the core is eroded away, resulting in a gradually coarser soil. A soil damaged by suffusion can be remediated with permeation grouting. During permeation grouting, too high grouting pressures inside the dam must be avoided as neither to fracture nor heave the surrounding soil. It is therefore important to find out how much of the grouting pressures at the pumps are lost inside pipelines due to the grout materials resistance to flow.In this paper, a pilot scale vertical permeation grouting investigation has been performed with two modified low mobility grout materials, developed for embankment dams. Frictional pipeline losses, including local loss at the end of the pipeline, were measured to 1 – 64 kPa/m at pipeline velocities 0.01 – 1.03 m/s. Hydraulic conductivities for the grout material during permeation of two coarse grained materials were calculated to 1.4x10-4 m/s – 3.3x10-4 m/s, on par with expected values. Viscosity was calculated to 12.6 and 11.8 Pas for the tested grout materials. The obtained results within this study will allow for easier predictions of grouting pressures in future grouting operations in embankment dams. The need for pilot injection tests in the field should thus be diminished.
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| 28. |
- Lindén, Julia, et al.
(författare)
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DSM-based Reliability Analysis of Modular Architectures
- 2015
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Ingår i: Modeling and managing complex systems. - München : Carl Hanser Verlag GmbH. - 9783446445734 ; , s. 111-122
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Konferensbidrag (refereegranskat)abstract
- The main function of a heavy truck is to transport goods. Furthermore,the truck is directly operated by a driver, who has several additional functionalrequirements, of both ergonomic and communicative characters. Transport is a trustbusiness and today’s just-in-time delivery systems rely on getting the goods on time.Product reliability, which is the ability of a system to perform according to itsfunctional targets, is consequently a crucially important property for a heavy truck.This paper proposes a structure for a system reliability model that integrates differentand complementary representations, such as Function-Means trees and DesignStructure Matrix. The novelty of the presented approach is that it treats andintegrates the technical and the human subsystems through the human-technicalsystem interfaces in an extended DSM. The proposed reliability systems approachis verified with a component analysis case study of a truck cab and driver system.
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| 29. |
- Lindén, Julia, et al.
(författare)
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Model-based reliability analysis
- 2016
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Ingår i: Artificial intelligence for engineering design, analysis and manufacturing. - : Cambridge University Press. - 0890-0604 .- 1469-1760. ; 30:3, s. 277-288
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Tidskriftsartikel (refereegranskat)abstract
- The main function of a heavy truck is to transport goods, with ton-kilometers/year as an example of a major quantitative performance measure. Furthermore, the truck is directly operated by a driver, who has several additional functional requirements, of both ergonomic and communicative characters. Failure of these functions may be a subjective experience, differing between drivers, but the failures are still important. Today's just-in-time delivery systems rely on getting the goods on time, and this requires high availability. Availability is reduced not only by technical failures but also by subjectively experienced failures, because these also require repairs, or downtime. Product reliability is a systems property that cannot be attributed to a single component. It is in many cases related to interaction between components, or to interaction between humans and the technical system, in the case of subjectively experienced failures. Reliability assessments of systems with interactive functions require a system model that includes the interfaces between the technical system and human features that are carriers of interactive functions. This paper proposes a model of system architecture, for the purpose of reliability assessments, that integrates different and complementary representations, such as function-means diagrams and a design structure matrix. The novelty of the presented approach is that it treats and integrates the technical and the human subsystems through the human-technical system interfaces. The proposed systems reliability approach is described and verified with a component analysis case study of an extended truck cab and driver system.
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| 30. |
- Lindén, Julia, et al.
(författare)
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Modelling uncertainty of reliability forecasts with varying operating conditions
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Heavy truck customers attach great importance to reliability, which make reliability assessments essential in product development projects. Since changes are easier and less expensive in early project stages, early reliability assessments are valuable. At these early stages, complete vehicle testing cannot yet be made. System reliability assessments must be made based on test data from component and subsystem tests, sometimes performed with different operating conditions than the system will be used in. Test data must be translated to the new situation, which requires information about how various factors affect reliability. Furthermore, the uncertainty in the forecast increases when the assessment is made for new operating conditions. Therefore, we also need information about how uncertainty propagates. The question is how this translation can be made, when data is sparse and expert judgement must be used, and how the increasing uncertainty can be reasonably modelled. In this paper, current methods to take into account varying operating conditions have been reviewed, and four methods have been tested in a case study. These methods are one based on fuzzy logic, a first-order second-moment reliability method (VMEA), and two variants of the proportional hazards model. The study shows that several methods are capable of handling sparse data, but only VMEA can model how uncertainty increases when operating conditions vary. It has however the drawback of being quite sensitive to uncertainty in the input data.
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| 31. |
- Lindén, Julia, et al.
(författare)
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Reliability Assessment with Varying Operating Conditions
- 2016
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Ingår i: Procedia CIRP. - : Elsevier. - 2212-8271. ; , s. 796-801
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Konferensbidrag (refereegranskat)abstract
- Product reliability is a systems property that cannot be attributed to a single component. It is in many cases related to interactions between components, or to interactions between humans and the technical system. Product functionality includes both technical functions, like structural integrity and interactive functions, like ergonomics. Reliability assessments in the early stages of the development process are valuable, since design changes cost significantly less if made early. System reliability tests can only be made towards the end of the development process, but early estimates can be based on test data from component tests and function tests. Operating conditions often vary between component tests and system tests. Therefore, reliability assessments where data from one situation is used to predict reliability in a different situation must take this variation into account. We investigate how this can be done for both technical and interactive functions. The study is made in the context of system reliability for heavy trucks, where both technical functions and interactive functions affect product reliability. Two cases have been assembled from test data, one concerning a component on a truck cab, the other an interactive function of a truck. Two reliability estimation methods have been evaluated to investigate if the methods can be used for interactive functions as well as for technical functions. We conclude that a method for reliability estimation of interactive functions must be able to model increased uncertainty due to intrapersonal variation.
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| 32. |
- Lindén, Julia
(författare)
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Supporting complete vehicle reliability forecasts
- 2017
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Reliability is one of the properties that customers of heavy trucks value highest.Dependent on all parts and functions of the vehicle, reliability is a complexproperty, which can normally be measured only towards the end of a developmentproject. At earlier development stages, forecasts can give valuable decision supportfor project planning.The main function of a heavy truck is to transport goods, but the truck also hasinteractive functions as the working environment of the driver. Interactivefunctions are functions experienced by the driver. They are subjective, in the senseof being person dependent, so that a system can be experienced as inadequate byone user but satisfactory by another. Examples of interactive functions of heavytrucks are climate comfort and ergonomics, which are experienced differently bydifferent drivers. Failures of these functions lead to costs and limited availabilityfor the customer. Therefore it is important to include them in reliability forecasts.The work described in this thesis concerns some elements of the system reliabilityforecast. Two studies are presented, one proposing a qualitative systemarchitecture model and the other reviewing and testing methods for evaluating theimpact of varying operating conditions. Two case studies of a truck cab in a systemreliability test were made. The first case study shows that the system architecturemodel supports reliability forecasts by including interactive functions as well asexternal factors, human and environmental, which affect function performance.The second case study shows that modelling uncertainty is crucial for interactivefunctions and recommends a method to forecast function performance while takingvarying operating conditions into account.
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| 33. |
- Matoušek, Václav, et al.
(författare)
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Deposition limit velocity : Effect of particle size distribution
- 2017
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Ingår i: International Conferences on Transport and Sedimentation of Solid Particles 2017. - : Wydawnictwo Uniwersytetu Przyrodniczego we Wroclawiu. - 9788377172698 ; , s. 217-224
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Konferensbidrag (refereegranskat)abstract
- Industrial settling slurries often consist of particles of very different sizes; the particle size distribution may cover sizes which differ with two orders of magnitude. A broad particle size distribution affects parameters of slurry flow including deposition limit velocity. We present experimental results of the deposition limit velocity collected during a comprehensive experimental campaign testing slurry flows composed of solids of different fractions in the GIW Hydraulic Laboratory in 2016. Four narrow graded fractions (carrier fluid, pseudo-homogeneous, heterogeneous, and stratified) were tested in permutations from the individual components to the complete mixture at various concentrations. The primary experiments were carried out in a 203-mm pipe, and selected corresponding experiments were repeated in a 103-mm pipe. The experimental results show that interactions among components affect the resulting deposition limit velocity in flows of broadly graded settling slurries. The effect of particle size distribution on the deposition limit velocity is not benign. The deposit velocity is not necessarily lower in a flow of slurry composed of four components than in slurry flow of one component with the highest deposit velocity from the four components. We discuss possible modifications of a deposit velocity predictive model in order to take effects of a broad particle size distribution into account.
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| 34. |
- Matousek, Vaclav, et al.
(författare)
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Frictional head loss of various bimodal settling slurry flows in pipe
- 2019
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Ingår i: ASME-JSME-KSME 2019 8th Joint Fluids Engineering Conference, AJKFluids 2019 Volume 5, 2019. - : ASME Press. - 9780791859087
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Konferensbidrag (refereegranskat)abstract
- Pipe flows of bimodal settling slurries exhibit frictional head losses quite different from those determined simply as a sum of loss contributions by the individual fractions. Mechanisms governing flow friction and resulting from an interaction of grains of different fractions in transported slurry are not well understood. This makes a prediction of the frictional head loss in flows of bimodal slurries with Newtonian carrier uncertain. An extensive experimental campaign was conducted in GIW Hydraulic Laboratory in 2016 with slurries of four narrow graded fractions of the virtually same grain densities and very different grain sizes (carrier-liquid fraction, pseudo-homogeneous-, heterogeneous-, and stratified fractions). Besides testing of the individual fractions, different combinations of the fraction mixtures (bimodal, three- and four-component) were tested as well. In our previous work published in 2018, we employed experimental results for bimodal slurry composed of coarse granite rock (the stratifiedfraction) and fine sand (the pseudo homogeneous fraction) to analyze the observed considerable reduction of the frictional head loss caused by an addition of the fine sand to the granite rock slurry. In this work, we extend our analysis to the other bimodal slurries composed of permutations of the four fractions (in total 3 additional bimodal slurries) with a major objective to identify possible mechanisms leading to a modification of the frictional head loss due to an addition of a finer fraction to a coarser mono-disperse slurry, and to quantify this effect for the purposes of a predictive four-component model (4CM). The investigation shows that the frictional loss of bimodal slurry is always smaller than the theoretical loss obtained as the sum of losses of the fractions, although the massive reduction observed in the slurry composed of the stratified rock and fine sand is not observed in any other bimodal slurry. The investigation also suggests that the friction effect obtained by the finer fraction addition is due to different mechanisms for different bimodal slurries although all mechanisms are associated with altering mechanical friction due to granular contacts. It is shown that the observed effects can be well reproduced by the friction loss model 4CM, calibrated by the experimental data set from the 203-mm pipe and validated by the data set from the 103-mm pipe.
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| 35. |
- Matoušek, Václav, et al.
(författare)
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Pipe-Size Scale-Up of Frictional Head Loss in Settling Slurry Flows Using Predictive Models : Experimental Validation
- 2020
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Ingår i: ASME 2020 Fluids Engineering Division Summer Meeting collocated with the ASME 2020 Heat Transfer Summer Conference and the ASME 2020 18th International Conference on Nanochannels, Microchannels, and Minichannels. - : American Society of Mechanical Engineers (ASME).
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Konferensbidrag (refereegranskat)abstract
- Transported Newtonian settling slurries (mixtures of solid particles and carrying liquid) tend to stratify in a slurry pipeline and the degree of their stratification significantly affects the frictional head loss in a pipeline system. Solid particles can span a broad range of sizes from those typical for fine sand to those typical for coarse gravel. Different fractions of solids have different properties and form different flow patterns. The different patterns are associated with different dominating particle support mechanisms and friction mechanisms in slurry flow. Hence, there are different models describing and predicting the frictional head loss in pipe flows of different settling slurries. In the presented work, we focus on friction-loss models for heterogeneous (partially-stratified) flow (V50-model), and for fully-stratified flow (Vsm-model). The models can serve as tools to scale up information on frictional head loss in flow of specific slurry obtained experimentally in a small laboratory pipe to larger pipes of industrial sizes. So far, the reliability of the scale up has been difficult to verify as an availability of coarse particle experimental data was restricted to small laboratory pipes (an internal diameter of a pipe typically not larger than 100 mm) and data from larger pipes were extremely scarce.In 2016 and 2019, extensive experimental campaigns were conducted in the GIW Hydraulic Laboratory (Grovetown, GA, U.S.A.) testing flows of Newtonian settling slurries in pipes of 3 very different sizes (103 mm, 203 mm, and 489 mm). We exploit the experimental data to evaluate the pipe-size scale-up ability of the heterogeneous V50-model and the stratified Vsm-model. The evaluation includes an analysis of the pipe-size effect on the characteristic velocities of the models: the suspension velocity V50 and the deposition-limit velocity Vsm.
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| 36. |
- Matoušek, Václav, et al.
(författare)
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Threshold Criteria for Components of Predictive Model for Pipe Flow of Broadly-Graded Slurry
- 2018
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Ingår i: ASME 2018 5th Joint US-European Fluids Engineering Division Summer Meeting. - : The American Society of Mechanical Engineers. - 9780791851579
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Konferensbidrag (refereegranskat)abstract
- Industrial slurries transported in pressurized pipelines often consist of particles of broad size distribution. The broad particle size distribution affects slurry flow behavior in a pipe. A four-component model (4CM) predicts the frictional pressure drop in pipe flow of broadly graded slurry. The model considers Newtonian carrying liquid and splits the broadly graded solids into fractions (components) each of which contributes to the pressure drop through its own dominating friction mechanism expressed by a particular sub-model in the 4CM. The sorting of the solids into the components (carrier, pseudo-homogeneous, heterogeneous, fully-stratified) must be based on appropriate criteria. For the sake of simplicity, the 4CM currently uses threshold sizes of particles to split the solids into 4 components.The goal of the present work is to analyze the existing criteria for the threshold between the pseudo-homogeneous component and heterogeneous component and for the threshold between the heterogeneous component and fully-stratified component. The analysis is based on a description of mechanisms governing particle support (suspension, deposition) of each particular solids component in slurry flow. It shows that the existing grain-size thresholds actually express certain proportions among threshold velocities of flow delimiting different slurry flow regimes. Such threshold velocities are the deposition-limit velocity, the initial-suspension velocity, and the full-suspension velocity. We discuss the proportions and demonstrate how properties (of liquid, solids, flow) and associated parameters additional to the grain size may influence the thresholds.The analytical results are supported by experimental results for flow of individual components in a laboratory loop.
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| 37. |
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| 38. |
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| 39. |
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| 40. |
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| 41. |
- Sellgren, Anders
(författare)
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A note on depositional behaviour and conduit flow resistance of complex slurries
- 2010
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Ingår i: Conference in Minerals Engineering. - Luleå : Luleå tekniska universitet. - 9789174390971 ; , s. 185-196
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Slurries in mineral processing typically have average particles sizes of 20 to 100μm with maximum sizes of up to 500 to 1000μm. With solids volumetric concentrations varying from a few percent up to and over 40% the corresponding slurries are here termed complex because they cover an intermediate area between "non-settling" and "settling" types of mixtures. Depositional and flow resistance behaviours, some of which may be considered counter-intuitive, are discussed based on reported observations with heavy ore concentrates, tailings and sand slurries.
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| 42. |
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| 43. |
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| 44. |
- Sellgren, Anders
(författare)
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Airflow cooling in storm water systems
- 1984
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Ingår i: Proceedings of the Third International Conference on Urban Storm Drainage : Göteborg, Sweden, June 4 - 8, 1984. - Göteborg : Chalmers tekniska högskola. - 9170321280 ; , s. 117-126
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Konferensbidrag (refereegranskat)abstract
- Observations have shown that large quantities of ground heat are lost when air flows through storm water systems during cold spells in winter. The temperature distribution in the ground around a storm water pipeline under a street was examined. The non-linear problem of heat conduction with phase change in moist soil was mathematically modelled and the model was used to simulate ground temperature changes caused by the flow of cold air in a buried pipe. Some consequences of airflow cooling are schematically discussed
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| 45. |
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| 46. |
- Sellgren, Anders, et al.
(författare)
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Centrifugal slurry pump performance deratings : A coherent approach
- 2017
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Ingår i: 20th International Conference on Hydrotransport. - : BHR Group Limited. ; , s. 401-414
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Konferensbidrag (refereegranskat)abstract
- A basis for a coherent derating approach, which is founded on principal parameters from commonly referred to derating procedures, is discussed. A weighting technique may couple the diminishing drag influences to rheological effects for the intermediate two-component and viscous area here represented by highly concentrated mine tailings slurries. Loop test results with authentic tailings demonstrated the decreasing head derating with increased rotary speed and thus the viscous influence, a dependence which increased with particle fineness. A marked effect on the derating with yield stresses of 200-260 Pa was also found. Maximum reductions in head and efficiency were 15 and 25%, respectively, at solids concentrations by volume of up to about 50%
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| 47. |
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| 48. |
- Sellgren, Anders, et al.
(författare)
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Choice of solids concentration in mine tailings pipelines
- 1986
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Ingår i: Slurry technology - the second decade. - Washington : Slurry technology association. ; , s. 243-249
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Konferensbidrag (refereegranskat)abstract
- The majority of slurry transport applications are short-distance in-plant installations, mainly in the minerals industry. For example with most ores, after the concentration process, a fine-grained tailings slurry is transported by pipeline, sometimes as far as several kilometers, to disposal areas. Great savings of energy and water can be obtained at concentrators if the tailings slurry is thickened more effectively and water is reused directly instead of being transported the long way around the disposal area. A recent study, Sellgren (1983), shows that large amounts of heating energy can be recovered using a heat pump arrangement. The potential savings in Swedish mines was estimated to be about 10 to 20 GWh per year at every concentrator, the greatest part of which will be savings in oil.
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| 49. |
- Sellgren, Anders, et al.
(författare)
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Cost-effective pumping of coarse mineral products using fine sands
- 1997
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Ingår i: Powder Technology. - 0032-5910 .- 1873-328X. ; 94:3, s. 191-194
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Tidskriftsartikel (refereegranskat)abstract
- Coarse mineral particles with sizes of up to 200 mm can be pumped energy-effectively together with sands (< 1 mm) under nearly pseudohomogeneous conditions at volumetric solids concentrations of up to 40%. Recent experimental results indicate that particles with sizes of 0.1-0.5 mm play an important role in reducing pipe wall friction. Experimental results in pipelines with diameters of up to 0.44 m have here been used in a brief demonstration of industrial applications: integrated systems for waste rock transportation together with fine-grained tailings, coarse mineral particle pumping from open-pit mines or to disposal with dry deposition and recirculation of water and fine particles. Experiments with a crushed rock product (20-38 mm) pumped at a volumetric concentration of 13% showed that the friction losses were reduced considerably by particle degradation during the circulation in the pipeline loop. Circulatory effects must therefore be carefully considered when using coarse-particle loop results in the design of industrial once-through systems
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| 50. |
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