| 1. |
- Arvidsson, Rickard, 1984, et al.
(författare)
-
Life cycle assessment of hydrotreated vegetable oil from rape, oil palm and Jatropha
- 2011
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Ingår i: Journal of Cleaner Production. - : Elsevier BV. - 0959-6526 .- 1879-1786. ; 19:2-3, s. 128-137
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Tidskriftsartikel (refereegranskat)abstract
- A life cycle assessment of hydrotreated vegetable oil (HVO) biofuel was performed. The study wascommissioned by Volvo Technology Corporation and Volvo Penta Corporation as part of an effort to gaina better understanding of the environmental impact of potential future biobased liquid fuels for cars andtrucks. The life cycle includes production of vegetable oil from rape, oil palm or Jatropha, transport of theoil to the production site, production of the HVO from the oil, and combustion of the HVO. The functionalunit of the study is 1 kWh energy out from the engine of a heavy-duty truck and the environmentalimpact categories that are considered are global warming potential (GWP), acidification potential (AP),eutrophication potential (EP) and embedded fossil production energy. System expansion was used totake into account byproducts from activities in the systems; this choice was made partly to make thisstudy comparable to results reported by other studies. The results show that HVO produced from palmoil combined with energy production from biogas produced from the palm oil mill effluent has thelowest environmental impact of the feedstocks investigated in this report. HVO has a significantly lowerlife cycle GWP than conventional diesel oil for all feedstocks investigated, and a GWP that is comparableto results for e.g. rape methyl ester reported in the literature. The results show that emissions from soilcaused by microbial activities and leakage are the largest contributors to most environmental impactcategories, which is supported also by other studies. Nitrous oxide emissions from soil account for morethan half of the GWP of HVO. Nitrogen oxides and ammonia emissions from soil cause almost all of thelife cycle EP of HVO and contribute significantly to the AP as well. The embedded fossil production energywas shown to be similar to results for e.g. rape methyl ester from other studies. A sensitivity analysisshows that variations in crop yield and in nitrous oxide emissions from microbial activities in soil cancause significant changes to the results.
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| 2. |
- Colliander, Cristian, 1980-
(författare)
-
Science mapping and research evaluation : a novel methodology for creating normalized citation indicators and estimating their stability
- 2014
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The purpose of this thesis is to contribute to the methodology at the intersection of relational and evaluative bibliometrics. Experimental investigations are presented that address the question of how we can most successfully produce estimates of the subject similarity between documents. The results from these investigations are then explored in the context of citation-based research evaluations in an effort to enhance existing citation normalization methods that are used to enable comparisons of subject-disparate documents with respect to their relative impact or perceived utility. This thesis also suggests and explores an approach for revealing the uncertainty and stability (or lack thereof) coupled with different kinds of citation indicators.This suggestion is motivated by the specific nature of the bibliographic data and the data collection process utilized in citation-based evaluation studies.The results of these investigations suggest that similarity-detection methods that take a global view of the problem of identifying similar documents are more successful in solving the problem than conventional methods that are more local in scope. These results are important for all applications that require subject similarity estimates between documents. Here these insights are specifically adopted in an effort to create a novel citation normalization approach that – compared to current best practice – is more in tune with the idea of controlling for subject matter when thematically different documents are assessed with respect to impact or perceived utility. The normalization approach is flexible with respect to the size of the normalization baseline and enables a fuzzy partition of the scientific literature. It is shown that this approach is more successful than currently applied normalization approaches in reducing the variability in the observed citation distribution that stems from the variability in the articles’ addressed subject matter. In addition, the suggested approach can enhance the interpretability of normalized citation counts. Finally, the proposed method for assessing the stability of citation indicators stresses that small alterations that could be artifacts from the data collection and preparation steps can have a significant influence on the picture that is painted by the citationindicator. Therefore, providing stability intervals around derived indicators prevents unfounded conclusions that otherwise could have unwanted policy implications.Together, the new normalization approach and the method for assessing the stability of citation indicators have the potential to enable fairer bibliometric evaluative exercises and more cautious interpretations of citation indicators.
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| 3. |
- Ekesbo, Rickard, et al.
(författare)
-
Lack of adherence to hypertension treatment guidelines among GPs in southern Sweden-A case report- based survey
- 2012
-
Ingår i: BMC Family Practice. - : Springer Science and Business Media LLC. - 1471-2296. ; 13
-
Tidskriftsartikel (refereegranskat)abstract
- Background: General practitioners (GPs) often fail to correctly adhere to guidelines for the treatment of hypertension. The reasons for this are unclear, but could be related to lack of knowledge in assessing individual patients' cardiovascular disease risk. Our aim was to investigate how GPs in southern Sweden adhere to clinical guidelines for the treatment of hypertension when major cardiovascular risk factors are taken into consideration. Method: A questionnaire with five genuine cases of hypertension with different cardiovascular risk profiles was sent to a random sample of GPs in southern Sweden (n = 109) in order to investigate the attitude towards blood pressure (BP) treatment when major cardiovascular risk factors were present. Results: In general, GPs who responded tended to focus on the absolute target BP rather than assessing the entire cardiovascular risk factor profile. Thus, cases with the highest risk of cardiovascular disease were not treated accordingly. However, there was also a tendency to overtreat the lowest risk individuals. Furthermore, the BP levels for initiating pharmacological treatment varied widely (systolic BP 140-210 mmHg). ACE inhibitors (70%) were the most common first choice of pharmacological treatment. Conclusion: In this study, GPs in Southern Sweden were suggesting, for different cases, either under- or overtreatment in relation to current guidelines for treatment of hypertension. On reason may be that they failed to correctly assess individual cardiovascular risk factor profiles. Key points: Despite international and national clinical guidelines on the treatment of hypertension, general practitioners often fail to correctly assess the cardiovascular risk for patients in a clinical setting. Most GPs use target blood pressure levels but do not consider other cardiovascular risk factors. Both under- and overtreatment of high and low cardiovascular risk groups were seen in this study.
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| 4. |
- Gerward, Sofia, et al.
(författare)
-
Trends in out-of-hospital ischaemic heart disease deaths 1992 to 2003 in southern Sweden.
- 2012
-
Ingår i: Scandinavian Journal of Public Health. - : SAGE Publications. - 1651-1905 .- 1403-4948. ; 40:4, s. 340-347
-
Tidskriftsartikel (refereegranskat)abstract
- AIMS: In western countries out-of-hospital ischaemic heart disease (IHD) deaths account for approximately 50-70% of all IHD deaths. The objective was to examine the trends in out-of-hospital IHD deaths in the Region of Skåne in southern Sweden, in different sex- and age-groups. METHODS: All 14,347 persons (range 24-110 years) in Skåne who died out-of-hospital between 1992 and 2003 from IHD (I410-I414; I20-I25) as the underlying cause of death. Subjects with previous admission for IHD since 1970 were excluded. Data were retrieved from the Swedish National Cause of Death and Patient Register. Age-standardized IHD mortality rates and trends were calculated using Poisson regression analysis. RESULTS: Age-standardized annual out-of-hospital IHD mortality rates from 1992-2003 decreased in men from 177±13 to 103±9/100,000 inhabitants (-4.7%; p<0.001) and in women from 142±11 to 96±9/100,000 (-2.7%; p<0.001). In men, the annual change in age-standardized IHD mortality rates were -5.3 % (p<0.001), -4.0 % (p<0.001) and -4.7 % (p<0.001), respectively, in the age groups 20-64 years, 65-74 years and ≥75 years. Corresponding figures in women were -4.4 % (p<0.001), -2.4 % (p=0.003) and -2.5 % (p<0.001). The proportion of IHD deaths occurring out-of-hospital was in these age groups 50%, 40% and 35% respectively. CONCLUSIONS: In Skåne, out-of-hospital mortality in IHD deaths decreased significantly between 1992 and 2003. The decrease is more pronounced in men than women, and at the end of the study period in 2003, rates were almost equal. The proportion of IHD deaths occurring outside hospital was higher in younger people than in older people.
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| 5. |
- Nilsson, Rickard, et al.
(författare)
-
Utredning och provning av kostnadseffektiva metoder för bullerminimering av spårfordon
- 2013
-
Ingår i: Transportforum 2013. - Linköping : Statens väg- och transportforskningsinstitut. ; , s. 122-135
-
Konferensbidrag (refereegranskat)abstract
- Den här artikeln avser att för ett befintligt spårtrafiksystem översiktligt beskriva olika bullerreducerande åtgärders effekt, deras ekonomiska aspekter samt indirekt inverkan på systemet och dess omgivning. SL (AB Storstockholms Lokaltrafik) arbetar aktivt för att minska tågtrafikens störning till omgivningen, med den långsiktiga strävan att hela SLs spårsystem ska innehålla riktvärden för ny- och ombyggd järnväg enligt infrastrukturpropositionen. Ett viktigt medel för att nå denna ambition är succesivt byte av fordonsparken till nya och tystare fordon, detta kommer dock inte ge tillräcklig bullerreduktion, ytterligare åtgärder kommer att krävas. Beroende på problembilden kan det innebära att en enstaka åtgärd eller flera åtgärder i kombination behöver tas till. För att kartlägga, utvärdera och skapa kunskap om olika åtgärdsalternativ har SL därför arbetat långsiktigt och systematiskt med att utvärdera ett antal olika metoder. En viktig aspekt i sammanhanget är att då SLs spår till stor del går mycket nära bostäder är det önskvärt att hitta effektiva bullerskyddsåtgärder med så liten påverkan som möjligt avseende landskapsbild och barriäreffekt. Med hänsyn till ägardirektivet om ekonomi i balans är det även viktigt att se till total nytta relativt total kostnad vid val av åtgärd.
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| 6. |
- Olsson, Rickard, 1969-, et al.
(författare)
-
Adsorption, desorption, and surface-promoted hydrolysis of Glucose-1-phosphate in Aqueous Goethite (α-FeOOH) Suspensions
- 2010
-
Ingår i: Langmuir. - : Americal Chemical Society. - 0743-7463 .- 1520-5827. ; 26:24, s. 18760-18770
-
Tidskriftsartikel (refereegranskat)abstract
- Adsorption, desorption, and precipitation reactions at environmental interfaces govern the fate of phosphorus in terrestrial and aquatic environments. Typically, a substantial part of the total pool of phosphorus consists of organophosphate, and in this study we have focused on the interactions between glucose-1-phosphate (G1P) and goethite (α-FeOOH) particles. The adsorption and surface-promoted hydrolysis reactions have been studied at room temperature as a function of pH, time, and total concentration of G1P by means of quantitative batch experiments in combination with infrared spectroscopy. A novel simultaneous infrared and potentiometric titration (SIPT) technique has also been used to study the rates and mechanisms of desorption of the surface complexes. The results have shown that G1P adsorption occurs over a wide pH interval and at pH values above the isoelectric point of goethite (IEP(goethite) = 9.4), indicating a comparatively strong interaction with the particle surfaces. As evidenced by IR spectroscopy, G1P formed pH-dependent surface complexes on goethite, and investigations of both adsorption and desorption processes were consistent with a model including three types of surface complexes. These complexes interact monodentately with surface Fe but differ in hydrogen bonding interactions via the auxiliary oxygens of the phosphate group. The apparent desorption rates were shown to be influenced by reaction pathways that include interconversion of surface species, which highlights the difficulty in determining the intrinsic desorption rates of individual surface complexes. Desorption results have also indicated that the molecular structures of surface complexes and the surface charge are two important determinants of G1P desorption rates. Finally, this study has shown that surface-promoted hydrolysis of G1P by goethite is base-catalyzed but that the extent of hydrolysis was small.
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| 7. |
- Olsson, Rickard, et al.
(författare)
-
Adsorption mechanisms of glucose in aqueous goethite suspensions
- 2011
-
Ingår i: Journal of Colloid and Interface Science. - : Elsevier Inc. - 0021-9797 .- 1095-7103. ; 353:1, s. 263-268
-
Tidskriftsartikel (refereegranskat)abstract
- The adsorption of glucose and polysaccharides onto solid surfaces is important in several areas of science and engineering including soil chemistry and mineral processing. In this work we have studied the adsorption of D-glucose at the water-goethite (α-FeOOH) interface as a function of pH using batch adsorption measurements and a simultaneous infrared and potentiometric technique. Molecular orbital calculations were also performed in order to support interpretations of the infrared spectroscopic data. Infrared spectroscopy has shown that glucose adsorbs at the water-goethite interface with an intact ring structure and that the β-form is favored relative to the α isomer. The collective spectroscopic and macroscopic results were fully consistent with an adsorption mechanism where glucose interacts with goethite surface sites via hydrogen bonding interactions. Specific infrared peak shifts indicated that glucose primarily acts as a hydrogen bond donor and that it interacts with acceptor sites that become increasingly more prevalent as the surface is deprotonated. These results are in general agreement with the acid/base model for mono- and polysaccharide interactions at metal oxide surfaces, but contradict the inner sphere hypothesis that was proposed based on ex situ spectroscopic measurements.
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| 8. |
- Olsson, Rickard, 1969-, et al.
(författare)
-
Enzymatic hydrolysis of organic phosphates adsorbed on mineral surfaces
- 2012
-
Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 46, s. 285-291
-
Tidskriftsartikel (refereegranskat)abstract
- Esters of phosphoric acid constitute a sizable fraction of the total phosphorus supply in the environment and thus play an important role in the global phosphorus cycle. Enzymatic hydrolysis of these esters to produce orthophosphate is often a required reaction preceding phosphorus uptake by plants and microorganisms. Generally, adsorption to environmental particles is assumed to limit this process. Here we show, however, that the rate of enzymatic hydrolysis of glucose-1-phosphate (G1P) adsorbed on goethite by acid phosphatase (AcPase) can be of the same order of magnitude as in aqueous solution. The surface process releases carbon to the solution whereas orthophosphate remains adsorbed on goethite. This hydrolysis reaction is strictly an interfacial process governed by the properties of the interface. A high surface concentration of substrate mediates the formation of a catalytically active layer of AcPase, and although adsorption likely reduces the catalytic efficiency of the enzyme, this reduction is almost balanced by the fact that enzyme and substrate are concentrated at the mineral surfaces. Our results suggest that mineral surfaces with appropriate surface properties can be very effective in concentrating substrates and enzymes thereby creating microchemical environments of high enzymatic activity. Hence, also strongly adsorbed molecules in soils and aquatic environments may be subjected to biodegradation by extracellular enzymes.
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| 9. |
- Olsson, Rickard, 1969-
(författare)
-
Surface reactions on mineral particles controlling the hydrolysis of glucose phosphates
- 2011
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Phosphorus (P) is an essential nutrient. A significant amount of soil P may be in the form of organophosphates. Due to the size of these compounds, hydrolysis is often required before P can be assimilated by organisms. Hydrolysis may be mediated by mineral surfaces, or catalyzed by extra cellular enzymes. Since both organophosphates and enzymes have a strong affinity for environmental particles, a study of the hydrolysis of organophosphates must focus on reactions at the water/particle interface. This thesis is a summary of four papers, discussing the adsorption, desorption, and abiotic and enzymatic hydrolysis of glucose-1-phosphate (G1P) and glucose-6-phosphate (G6P) in aqueous goethite suspensions. A new technique for simultaneous infrared and potentiometric titrations (SIPT) allowed in-situ measurements of the interfacial reactions. It was found that glucose phosphates form pH-dependent inner sphere complexes on goethite, which coordinate in a monodentate fashion, and are stabilized by hydrogen bonding. Desorption involves a change in speciation of the surface complexes, illustrating the difficulty in determining desorption rates for individual complexes. The surface mediated hydrolysis is primarily base catalyzed for G1P, and acid catalyzed for G6P. The difference is partly due to electronic factors, and partly to differences in glucose group/goethite interactions. Considerably more extensive is the hydrolysis catalyzed by an acid phosphatase (AcPase). The rate of the enzymatic hydrolysis are strongly dependent on the glucose phosphate surface coverage, showing that surface properties affect the adsorption mode of enzymes, and thus their catalytic activity. In solution, AcPase showed a greater specificity towards G6P, but this specificity was partly lost after adsorption onto goethite.
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| 10. |
- Orvnäs, Anneli, et al.
(författare)
-
Active Lateral Secondary Suspension with H∞ Control to Improve Ride Comfort : Simulations on a Full-Scale Model
- 2011
-
Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 0042-3114 .- 1744-5159. ; 49:9, s. 1409-1422
-
Tidskriftsartikel (refereegranskat)abstract
- In this study, a full-scale rail vehicle model is used to investigate how lateral ride comfort is influenced by implementing the H and sky-hook damping control strategies. Simulations show that significant ride comfort improvements can be achieved on straight track with both control strategies compared with a passive system. In curves, it is beneficial to add a carbody centring Hold-Off Device (HOD) to reduce large spring deflections and hence to minimise the risk of bumpstop contact. In curve transitions, the relative lateral displacement between carbody and bogie is reduced by the concept of H control in combination with the HOD. However, the corresponding concept with sky-hook damping degrades the effect of the carbody centring function. Moreover, it is shown that lateral and yaw mode separation is a way to further improve the performance of the studied control strategies.
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| 11. |
- Orvnäs, Anneli, et al.
(författare)
-
An active secondary suspension concept to improve lateral and vertical ride comfort
- 2013
-
Ingår i: 9th international conference on railway bogies and running gears, Budapest, September 9-12. - Budapest, Hungary : Department of Railway vehicles, Aircraft and Ships at the BME. ; , s. 86-88
-
Konferensbidrag (refereegranskat)abstract
- When the speed of a rail vehicle is increased, ride comfort is normally negatively affected. The suspensions of the vehicle have to be modified in order to compensate for the amplified vibrations in the carbody. However, the possibilities of improvement by means of conventional passive damping will eventually reach a limit. Therefore, active suspension technology in rail vehicles is considered to be an alternative solution, since it offers better options of improving the vehicle’s dynamic performance compared to conventional passive solutions.Although previous research has been performed concerning concepts of combined active lateral and vertical secondary suspension – by replacing the lateral and vertical dampers with actuators – no such concept known to the authors has been introduced for service implementation.This paper presents an active secondary suspension concept used to simultaneously improve lateral and vertical ride comfort. In the first phase of the research project, focus was on an active secondary suspension concept in the lateral direction (ALS), including dynamic and quasi-static lateral control of the carbody. Simulations were validated against running tests, showing significant ride comfort improvements. The ALS system will soon be taken into service operation.In the next phase of the project, simulations were performed with the active suspension device in the vertical direction (AVS), including dynamic vertical and quasi-static roll control of the carbody. The simulations performed with the AVS system indicated significant ride comfort improvements compared to the passive system.In the final phase of the project, the ALS and AVS systems are combined. Simulation results show that the active system significantly improves lateral and vertical ride comfort compared to a passive system. Further, by means of the quasi-static roll control of the carbody, higher speeds in curves can be allowed without negatively affecting ride comfort. Moreover, the active suspension concept reduces the influence on ride comfort caused by the air spring stiffness. This means that the total air spring volume can be reduced.
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| 12. |
- Orvnäs, Anneli, et al.
(författare)
-
Aspects of Using Active Vertical Secondary Suspension to Improve Ride Comfort
- 2011
-
Ingår i: 22nd International Symposium on Dynamics of Vehicles on Roads and Tracks, IAVSD'11.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This paper presents various aspects of using active vertical secondary suspension in a rail vehicle to improve ridecomfort. Dynamic control of the vertical and roll modes of the carbody is achieved by means of actuators replacingthe conventional vertical dampers in the secondary suspension. Active damping improves vertical ride comfort,compared to a passive system. Besides dynamic control, the actuators are able to generate quasi-static roll controlbetween the carbody and bogies in curves. This allows for higher speeds in curves, without negatively affecting ridecomfort.
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| 13. |
- Orvnäs, Anneli
(författare)
-
On Active Secondary Suspension in Rail Vehicles to Improve Ride Comfort
- 2011
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- One way to make rail vehicles a competitive means of transportation is to increase running speed. However, higher speeds usually generate increased forces and accelerations on the vehicle, which have a negative effect on ride comfort. With conventional passive suspension, it may be difficult to maintain acceptable passenger comfort. Therefore, active technology in the secondary suspension can be implemented to improve, or at least maintain, ride comfort at increased vehicle speeds or when track conditions are unfavourable. This thesis describes the development of an active secondary suspension concept to improve ride comfort in a high-speed train. Firstly, an active lateral secondary suspension system (ALS) was developed, including dynamic control of the lateral and yaw modes of the carbody. Furthermore, quasi-static lateral carbody control was included in the suspension system in order to laterally centre the carbody above the bogies in curves at high track plane acceleration and hence to avoid bumpstop contact. By means of simulations and on-track tests, it is shown that the ALS system can offer significant lateral ride comfort improvements compared to a passive system. Two different control strategies have been studied—the relatively simple sky-hook damping and the multi-variable H∞ control—using first a quarter-car and then a full-scale vehicle model. Simulation results show that significant ride comfort improvements can be achieved with both strategies compared to a passive system. Moreover, H∞ control in combination with the carbody centring device is better at reducing the relative lateral displacement in transition curves compared to sky-hook damping. Secondly, an active vertical secondary suspension system (AVS) was developed, using simulations. Dynamic control of the vertical and roll modes of the carbody, together with quasi-static roll control of the carbody, show significant vertical ride comfort improvements and allow higher speeds in curves. Further, the AVS system compensates for negative ride comfort effects if the structural stiffness of the carbody is reduced and if the vertical air spring stiffness is increased. Finally, the two active suspension systems (ALS and AVS) were combined in simulations. The results show that both lateral and vertical ride comfort is improved with the active suspension concept at a vehicle speed of 250 km/h, compared to the passive system at 200 km/h. Further, active suspension in one direction does not affect the other direction. The ALS system has been included in two recent orders comprising more than 800 cars.
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| 14. |
- Orvnäs, Anneli, et al.
(författare)
-
Ride comfort improvements in a high-speed train with active secondary suspension
- 2010
-
Ingår i: Journal of Mechanical Systems for Transportation and Logistics. - : Japan Society of Mechanical Engineers. - 1882-1782. ; 3:1, s. 206-215
-
Tidskriftsartikel (refereegranskat)abstract
- A combination of increased vehicle speeds and non-improved railway tracks may have a negative impact on passenger comfort. Active technology can replace the conventional passive solution of the secondary suspension of a rail vehicle in order to maintain good passenger comfort even when vehicle speed is increased and track conditions are inferior. This paper focuses on the benefits of using a so-called Hold-Off-Device (HOD) function in the lateral secondary suspension. On-track tests have been performed with the active secondary suspension concept implemented in a two-car Regina train during the summers of 2007 and 2008. The evaluated measurement results have been very satisfactory and the device will be implemented in long-term tests in service operation. These tests were carried out in the beginning of 2009.
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| 15. |
- Orvnäs, Anneli, et al.
(författare)
-
Ride Comfort Improvements of a REGINA Train with Active Lateral Secondary Suspension
- 2010
-
Ingår i: 8th International Conference on Railway Bogies and Running Gears, BOGIE '10, Budapest, Hungary, September 13-16, 2010..
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This study describes the development of a system of active lateral secondary suspension (ALS) for commercial use. Simulations and on-track tests have been performed with a two-car REGINA train-set since 2007, using electro-hydraulic actuators together with sky-hook damping and a carbody centring Hold-Off Device to actively control the secondary suspension. Measurement results show that the ALS system significantly reduces the lateral dynamic carbody accelerations. Furthermore, the lateral quasi-static displacements between carbody and bogies in curves at high track plane accelerations are significantly reduced. Hence, lateral ride comfort is improved and higher speeds, particularly in curves, may be allowed. The satisfactory results have led to long-term tests in service operation, which are being carried out since the beginning of 2009.
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| 16. |
- Persson, Rickard, et al.
(författare)
-
On-track test of tilt control strategies for less motion sickness on tilting trains
- 2012
-
Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 0042-3114 .- 1744-5159. ; 50:7, s. 1103-1120
-
Tidskriftsartikel (refereegranskat)abstract
- Carbody tilting is today a mature and inexpensive technology that permits higher train speeds in horizontal curves, thus shortening travel time. However, tilting trains run a greater risk of causing motion sickness than non-tilting ones. It is likely that the difference in motions between the two train types contributes to the observed difference in risk of motion sickness. Decreasing the risk of motion sickness has until now been equal to increasing the discomfort related to quasi-static lateral acceleration. But, there is a difference in time perception between discomfort caused by quasi-static quantities and motion sickness, which opens up for new solutions. One proposed strategy is to let the local track conditions influence the tilt and give each curve its own optimised tilt angle. This is made possible by new tilt algorithms, storing track data and using a positioning system to select the appropriate data. The present paper reports from on-track tests involving more than 100 test subjects onboard a tilting train. A technical approach is taken evaluating the effectiveness of the new tilt algorithms and the different requirements on quasi-static lateral acceleration and lateral jerk in relative terms. The evaluation verifies that the rms values important for motion sickness can be influenced without changing the requirements on quasi-static lateral acceleration and lateral jerk. The evaluation shows that reduced quantities of motions assumed to have a relation to motion sickness also lead to a reduction in experienced motion sickness. However, a limitation of applicability is found as the lowest risk of motion sickness was not recorded for the test case with motions closest to those of a non-tilting train. An optimal level of tilt, different from no tilt at all, is obtained. This non-linear relation has been observed by other researchers in laboratory tests.
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| 17. |
- Persson, Rickard, 1958-, et al.
(författare)
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Strategies for less motion sickness on tilting trains
- 2010
-
Ingår i: Proceedings of Comprail 2010. - Southampton : WIT Press. - 9781845644680 ; , s. 581-591
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Many railways have put tilting trains into operation on lines with horizontal curves with small radii. Tilting trains have vehicle bodies that can roll inwards, reducing the lateral acceleration perceived by the passengers. Tilting trains can therefore run through curves at higher speeds. However, excessive tilt motions can cause motion sickness in sensitive passengers. On the other hand, too little tilting will cause discomfort from high lateral acceleration and jerk [1].The present paper presents new tilt algorithms aimed at balancing the conflicting objectives of ride comfort and less motion sickness. An enhanced approach is taken, where the amount of tilt depends on the local track conditions and the train speed. The paper shows how selected tilt algorithms influence certain motion sickness related carbody motions.Speed profiles designed to avoid local peaks in the risk of motion sickness are another possibility. The speed profiles for both tilting and non-tilting trains are today set from safety and comfort perspectives only, thus minimizing the running time. The present paper shows how speed profiles could be used to balance the conflicting objectives of running time and less risk of motion sickness. The result is derived from simulations and put in relation to today’s tilt algorithms and speed profiles on the Stockholm – Gothenburg main line in Sweden (457 km).
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| 18. |
- Persson, Rickard, 1958-
(författare)
-
Tilting trains : Enhanced benefits and strategies for less motion sickness
- 2011
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Carbody tilting is today a mature and inexpensive technology that allows higher train speeds in horizontal curves, thus shortening travel time. This doctoral thesis considers several subjects important for improving the competitiveness of tilting trains compared to non-tilting ones. A technology review is provided as an introduction to tilting trains and the thesis then focuses on enhancing the benefits and strategies for less motion sickness. A tilting train may run about 15% faster in curves than a non-tilting one but the corresponding simulated running time benefit on two Swedish lines is about 10%. The main reason for the difference is that speeds are set on other grounds than cant deficiency at straight track, stations, bridges, etc. The possibility to further enhance tilting trains’ running speed is studied under identified speed limitations due to vehicle-track interaction such as crosswind requirements at high speed curving. About 9% running time may be gained on the Stockholm–Gothenburg (457 km) mainline in Sweden if cant deficiency, top speed, and tractive performance are improved compared with existing tilting trains. Non-tilting high-speed trains are not an option on this line due to the large number of 1,000 m curves. Tilting trains run a greater risk of causing motion sickness than non-tilting trains. Roll velocity and vertical acceleration are the two motion components that show the largest increase, but the amplitudes are lower than those used in laboratory tests that caused motion sickness. Scientists have tried to find models that can describe motion sickness based on one or more motion quantities. The vertical acceleration model shows the highest correlation to motion sickness on trains with active tilt. However, vertical acceleration has a strong correlation to several other motions, which precludes vertical acceleration being pointed out as the principal cause of motion sickness in tilting trains. Further enhanced speeds tend to increase carbody motions even more, which may result in a higher risk of motion sickness. However, means to counteract the increased risk of motion sickness are identified in the present work that can be combined for best effect. Improved tilt control can prevent unnecessary fluctuations in motion sickness related quantities perceived by the passengers. The improved tilt control can also manage the new proposed tilt algorithms for less risk of motion sickness, which constitute one of the main achievements in the present study. Local speed restrictions are another means of avoiding increased peak levels of motion sickness when increasing the overall speed. The improved tilt control and the proposed tilt algorithms have proven to be effective in on-track tests involving more than 100 test subjects. The new tilt algorithms gave carbody motions closer to non-tilting trains. Rather unexpectedly, however, the test case with the largest decrease in tilt gave a greater risk of motion sickness than the two test cases with less reduction in tilt. It is likely that even better results can be achieved by further optimization of the tilt algorithms; the non-linear relation between motions and motion sickness is of particular interest for further study.
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| 19. |
- Persson, Rickard, 1958-
(författare)
-
Tilting trains : benefits and motion sickness
- 2010
-
Ingår i: Proceedings of the Institution of mechanical engineers. Part F, journal of rail and rapid transit. - 0954-4097 .- 2041-3017. ; 224:F6, s. 513-522
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Tidskriftsartikel (refereegranskat)abstract
- Carbody tilting is today a mature and inexpensive technology that allows higher speeds on curves, thus shortening travel time. The technology has been accepted by many train operators, but some issues are still holding back the full potential of tilting trains. This paper focuses on improving the benefits and limiting the drawbacks of tilting trains. This is done by quantifying the possible running time benefits compared with today's tilting trains, identifying what motion components have an influence on motion sickness, and finally quantifying the influence from the increased speed on these motion components. A running time analysis was made to show what potential there is to further improve running times by optimizing tracks and trains. Relations between cant deficiency, top speed, tractive performance, and running times are shown for a tilting train. About 9 per cent running time may be gained on the Stockholm-Gothenburg (457 km) main line in Sweden if cant deficiency, top speed, and tractive performance are improved compared with existing tilting trains. Introduction of non-tilting high-speed trains is not an option on this line due to the large number of 1000 m curves. However, tilting trains run a greater risk of causing motion sickness than non-tilting trains. Roll velocity and vertical acceleration are the two motion components that show the largest increase, but the amplitudes are lower than those used in laboratory tests that caused motion sickness. Higher curve speeds will increase carbody motions still further, but there are some possibilities to trade between vertical and lateral carbody acceleration by increasing or decreasing roll.
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| 20. |
- Qazizadeh, Alireza, et al.
(författare)
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On-Track Tests and Simulation of Active Secondary Suspension on a Rail Vehicle : Research, Development and Maintenance
- 2014
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Ingår i: Proceedings of the Second International Conference on Railway Technology. - Stirlingshire, UK : Civil-Comp Press. - 9781905088591
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Konferensbidrag (refereegranskat)abstract
- Ride comfort is one of the important criteria when designing and approving a new train. This parameter is negatively affected by low track quality or by increased train speed. One way to improve ride comfort in such operation conditions is to use active suspension control. However, the solution needs to be economic and reliable to remain attractive to industry. In this paper such an active suspension is developed and tested in a collaboration between KTH and Bombardier. The active control is implemented by replacing secondary vertical and lateral dampers with actuators. Skyhook control theory is used in combination with mode separation to calculate the reference force to the actuators. A two carbody train set manufactured by Bombardier is used as a test train. One of the cars has conventional passive suspension and is used as a reference car and the other is equipped with active secondary lateral and vertical suspension. Before carrying out the measurements, different failure scenarios of the active suspension were defined and studied in the multi-body simulation software Simpack. Active secondary vertical and lateral suspensions were finally tested together for the first time in Sweden in May 2013. Measurements were performed at different speeds up to 200 km/h on tracks around Stockholm. The results show a significant reduction of the vibration level in the carbody. According to the comfort values, up to 44% improvement is achieved.
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| 21. |
- Scheringer, Martin, et al.
(författare)
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Planetary boundaries for chemical pollution
- 2012
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Ingår i: Dioxin 2012 - 32nd International Symposium on Halogenated Persistent Organic Compounds.
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Konferensbidrag (refereegranskat)abstract
- Based on the concept by Rockström et al the paper discusses the principles of the concept in relation to chemical pollution and the specific challenges associated to that. The paper conclude the chemical pollution is certainly a strong anthropogenic impact of global relevance. However, because of the local or regional nature of many exposures and effects caused by chemicals, there is probably not a single tipping point for the global system that would have to be reflected by a planetary boundary. Therefore, in order to assess and manage chemical pollution, it seems to be more promising to focus on certain classes of chemicals separately and to derive boundaries of different types for these classes of chemicals, as illustrated in the paper for CFCs, POPs and food contaminants.
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| 22. |
- Thomas, Dirk, 1978-, et al.
(författare)
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Improving crosswind stability of fast rail vehicles using active secondary suspension
- 2014
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Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 0042-3114 .- 1744-5159. ; 52:7, s. 909-921
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Tidskriftsartikel (refereegranskat)abstract
- Rail vehicles are today increasingly equipped with active suspension systems for ride comfort purposes. In this paper, it is studied whether these often powerful systems also can be used to improve crosswind stability. A fast rail vehicle equipped with active secondary suspension for ride comfort purposes is exposed to crosswind loads during curve negotiation. For high crosswind loads, the active secondary suspension is used to reduce the impact of crosswind on the vehicle. The control input is taken from the primary vertical suspension deflection. Three different control cases are studied and compared with the only comfort-oriented active secondary suspension and a passive secondary suspension. The application of active secondary suspension resulted in significantly improved crosswind stability.
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