| 1. |
- Aronsson, Per, et al.
(författare)
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An operational decision support tool for stump harvest
- 2011
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- A multi-criteria decision support tool was developed to optimise stump harvesting for energy in Sweden. The decision tool takes account of multiple, sometimes conflicting, criteria relating to stump harvest; energy and climate, economics, biodiversity, and soil and water. Data on harvested stems are used as primary input data in the tool. Such data are routinely collected in harvester computers. The tool effectively deals with mixed sets of data; quantitative harvest data are re-calculated to metric (e.g. stump biomass), and qualitative data (e.g. biodiversity implications) are incorporated. A digital terrain map derived from air-borne laser scanning provides basic data for estimating soil wetness, while digital maps of water courses, key habitats and protected areas, or other sensitive habitats, are used to identify potentially and practically harvestable stumps.In four sub-models, an index from 0 to 10 is calculated for each stump, with 0 representing ‘Not at all suitable’ and 10 ‘Highly suitable for extraction’. Through this, a stump of high value for wood-living species is assigned a low index in the biodiversity sub-model and a large, easily accessible stump is assigned a high index in the economic sub-model. When calculating the net index, the sub-indices can be weighted according to the preferences of the end-user.An energy and climate sub-model incorporates greenhouse gas (GHG) emissions from forest operations and the effect of advancing GHG emissions when stump biomass is incinerated instead of being left to decompose. In the economic sub-model the potential monetary return from each stump is calculated based on estimated revenue from harvested stump biomass and the costs of stump harvesting and forwarding operations (based on cost functions and GIS calculations of transport distances).The biodiversity sub-model considers four types of wood-dependent organisms (lichens, mosses, insects and fungi) in terms of their habitat requirements, vulnerability, sun exposure preferences, locality, etc. A panel of external experts has drawn up a grading scale of stump values for the different taxonomic groups. The proximity to key habitats and exposure to sunlight are derived from a spatial model.Soil and water issues are handled within a sub-model estimating the consequences for long-term soil fertility (nutrient cycling and soil compaction) and water (leaching of plant nutrients and mercury, and particle transport due to soil damage by heavy machinery).The tool offers the end-user possibilities to prioritise and plan for cost-effective stump harvesting, while minimising negative environmental impacts.
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| 2. |
- Baalsrud Hauge, J. M., et al.
(författare)
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Bridging educational and working environments through pervasive approaches
- 2017
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Ingår i: 3rd International Joint Conference on Serious Games, JCSG 2017. - Cham : Springer Verlag. - 9783319701103 ; , s. 296-307
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Konferensbidrag (refereegranskat)abstract
- In the education of mechanical engineers alternative learning methods like serious games, simulations etc. have been used in past decades to better the learning outcomes. However, a main concern is still the amount of resources used on adapting and modding games as well as the challenges related to the implementation in the class room setting. Typically a positive learning experience does not only rely on the game as such, but how good the facilitator or teacher is to change game mechanics and the narratives so that players with different learning curves, past experience and cognitive abilities all stay in flow and feel immersed. Physical simulation games played in a workshop setting often have this ability, whereas this still seems to be a challenge in digitalized games. The main purpose of this article is to identify mechanics that need to be adapted differently for different user groups in order to keep them in flow, motivated and engaged in order to have a high learning experience and how we can take advantage of technologies like VR to reduce the costs and the resources.
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| 3. |
- Beelen, Rob, et al.
(författare)
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Development of NO2 and NOx land use regression models for estimating air pollution exposure in 36 study areas in Europe : the ESCAPE project
- 2013
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Ingår i: Atmospheric Environment. - : Elsevier. - 1352-2310 .- 1873-2844. ; 72, s. 10-23
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Tidskriftsartikel (refereegranskat)abstract
- Estimating within-city variability in air pollution concentrations is important. Land use regression (LUR) models are able to explain such small-scale within-city variations. Transparency in LUR model development methods is important to facilitate comparison of methods between different studies. We therefore developed LUR models in a standardized way in 36 study areas in Europe for the ESCAPE (European Study of Cohorts for Air Pollution Effects) project.Nitrogen dioxide (NO2) and nitrogen oxides (NOx) were measured with Ogawa passive samplers at 40 or 80 sites in each of the 36 study areas. The spatial variation in each area was explained by LUR modeling. Centrally and locally available Geographic Information System (GIS) variables were used as potential predictors. A leave-one out cross-validation procedure was used to evaluate the model performance.There was substantial contrast in annual average NO2 and NOx concentrations within the study areas. The model explained variances (R2) of the LUR models ranged from 55% to 92% (median 82%) for NO2 and from 49% to 91% (median 78%) for NOx. For most areas the cross-validation R2 was less than 10% lower than the model R2. Small-scale traffic and population/household density were the most common predictors. The magnitude of the explained variance depended on the contrast in measured concentrations as well as availability of GIS predictors, especially traffic intensity data were important. In an additional evaluation, models in which local traffic intensity was not offered had 10% lower R2 compared to models in the same areas in which these variables were offered.Within the ESCAPE project it was possible to develop LUR models that explained a large fraction of the spatial variance in measured annual average NO2 and NOx concentrations. These LUR models are being used to estimate outdoor concentrations at the home addresses of participants in over 30 cohort studies.
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| 4. |
- Dellve, Lotta, 1965, et al.
(författare)
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Health care clinicians’ engagement in organizational redesign of care processes: The importance of work and organizational conditions
- 2018
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Ingår i: Applied Ergonomics. - : Elsevier BV. - 0003-6870 .- 1872-9126. ; 68, s. 249-257
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Tidskriftsartikel (refereegranskat)abstract
- The Swedish health care system is reorienting towards horizontal organization for care processes. A main challenge is to engage health care clinicians in the process. The aim of this study was to assess engagement (i.e. attitudes and beliefs, the cognitive state and clinical engagement behaviour) among health care clinicians, and to investigate how engagement was related to work resources and demands during organizational redesign. A cohort study was conducted, using a questionnaire distributed to clinicians at five hospitals working with care process improvement approaches, two of them having implemented Lean production. The results show that kinds of engagement are interlinked and contribute to clinical engagement behaviour in quality of care and patient safety. Increased work resources have importance for engagements in organizational improvements, especially in top-down implementations. An extended work engagement model during organizational improvements in health care was supported. The model contributes to knowledge about how and when clinicians are mobilized to engage in organizational changes.
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| 5. |
- Håkansson, Charlotta, 1971-
(författare)
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Greenhouse Gas Fluxes and Carbon Sequestration in Young Norway Spruce Stands : The Effects of Fertilization
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The enormous challenge of climate change is discussed and debated today because of its major impact on life on Earth. The forests have an important role to play as the plants absorb carbon dioxide (CO2) from the atmosphere through their photosynthesis and the growing tree retain carbon (C). Hence, the larger the growth the greater the carbon storage and climate benefit. The demand for wood and wood products is increasing as well as the ongoing debate about forest management. Therefore, alternative management methods to increase wood production is of interest and the effects these methods could have on climate change mitigation. In this context this Thesis deals with the effect of fertilization on carbon balance and growth in young forest as well as flows of the greenhouse gases, CO2, methane (CH4), and nitrous oxide (N2O) from forest land. In addition, it deals also with the reliability and comparability of different measurement methods which are compared with respect to the carbon balance.The studies have been carried out in a young mixed stand of Norway spruce (Picea abies (L.) Karst) and birch (Betula pendula and B.pubescens) on a storm-felled (Gudrun 2005) area in southern Sweden, Kronoberg county. Part of the area was fertilized with 150 kg N ha-1 everysecond year from 2014 and forward, while the other part was kept unfertilized. In the unfertilized part a dose experiment was set up where 0,150, 300, and 450 kg N ha-1 were added to investigate the impact of the different fertilizer levels on forest floor greenhouse gas fluxes. Chamber measurements of forest floor fluxes, eddy-flux measurements of stand net-fluxes and tree measurements of height, diameter and birch leaf biomass were conducted in different, occasionally overlapping, periods in the years 2013-2021.The results show that even if the flows of CO2 from the forest floor increase initially after a first standard fertilization, the effect decreases quickly. The net fluxes show that the stands become carbon sinks already eight years after the storm with a net uptake of about 18 ton CO2 ha-1 yr-1 of. The forest floor fluxes of CH4 and N2O also show a short-term effect of fertilization, however the levels are very low compared to CO2. The fertilization induced increase of total tree biomass growth increased with time. The results show that 12 and 15 years after regeneration, the fertilization compared to the control has increased the tree growth by 3.4 and 6.3 m3 ha-1 yr-1 and carbon storage by 4.7 and 8.7 ton C ha-1 yr-1 respectively.Comparison of measurement results of the Eddy-flux technique's netflows and chamber measurements of soil respiration together with tree growth shows the importance of calibrating the measurement methods when the results are later to be used in modeling future climate scenarios.
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| 6. |
- LarsOlle, Anders, et al.
(författare)
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A multi-criteria decision support model for optimal stump harvesting
- 2012
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- A multi-criteria decision support model for optimal stump harvesting Sweden was developed. The model quantifies the effect of harvesting each individual stump over a harvesting object in four criteria's: - Biodiversity (Biodiversity value index) - Economy (SEK) - Greenhouse gas emissions (CO2) - Soil and water (Soil and water preservation index) The four criteria's are sometimes in conflict to each other, and uses values that are not directly comparable. The intended use for this model is to contribute with the objective evaluation of all four criteria's in the decision in what stumps to harvest and what stumps to leave in the harvesting object. The model uses individual stump data (e.g. position, tree species and stump biomass) and harvesting object GIS data (roads, elevation map, soil map, terrain map). Primary data on individual stumps comes from the logging system in the stem harvesters: GPS and operator classification. Such data are routinely collected in harvesters. Official map data for the harvesting object are available from the Swedish mapping, cadastral and land registration authority (Lantmäteriet). This includes the topographic map and elevation maps data in 2 m resolution. Also, GIS data are collected in the inspections before harvesting the stems. The biodiversity sub-model considers different types of wood-dependent organisms (lichens, mosses, insects and fungi) in terms of their habitat requirements, vulnerability, sun exposure preferences, locality, etc. A panel of external experts has drawn up a grading scale of stump values for the different taxonomic groups. The proximity to key habitats and exposure to sunlight are derived from a spatial model. In the economic sub-model the potential net return from each stump is calculated based on estimated revenue from harvested stump biomass and the costs of stump harvesting and transport (based on cost functions and GIS calculations of transport distances). An energy and climate sub-model incorporates greenhouse gas (GHG) emissions from forest operations and the effect of advancing GHG emissions when stump biomass is incinerated instead of being left to decompose. Soil and water issues are handled within a sub-model estimating the consequences for long-term soil fertility (nutrient cycling and soil compaction) and water (leaching of plant nutrients and mercury, and particle transport due to soil damage by heavy machinery). Each criteria is evaluated in totally four sub-models. To be able to compare the resulting value from each of the criteria, a harvesting index from 0 to 1 is calculated for each stump. The value 0 represents ‘Not at all suitable for harvest’ and 1 ‘Highly suitable for harvest’. Through this, a stump of high biodiversity value is assigned a low harvesting index in the biodiversity sub-model and a large, easily accessible stump is assigned a high harvesting index in the economic sub-model. When calculating the total net index, the harvesting index from each criteria has to be weighed together using one coefficient for each criteria. The weighing coefficient for each criteria is chosen according to the preferences of the decision maker. The tool offers the end-user possibilities to prioritise and plan for cost-effective stump harvesting, while minimising negative environmental impacts.
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| 7. |
- Raddino, Salvatore, et al.
(författare)
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CFD modeling of annular flow with a three-field approach
- 2018
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Ingår i: 2018 26th International Conference on Nuclear Engineering. - : ASME Press. - 9784888982566
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Konferensbidrag (refereegranskat)abstract
- Prediction of Critical Heat Flux and dryout is crucial for BWRs. Today 1-D models based on empirical correlations are used in order to model these phenomena. However, in order to get a better physical understanding and be able to model more complex geometries CFD modeling of annular flow is developed. The complexity of annular flows makes modeling of the different interactions involved challenging. In the present study a three-field approach is used in order to model annular flow; steam, liquid droplets and liquid film represent the different fields which are coupled to each other, i.e. both mass and momentum are exchanged between the modeled fields. The steam and droplets are modeled using Euler-Lagrangian multiphase CFD model and the liquid film is modeled through empirical models implemented at the wall boundary. The implemented model is validated against experimental data with good agreement. In order to enlarge the model validity range further improvements are needed especially concerning the entrainment modeling.
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| 8. |
- Strömgren, Magnus, et al.
(författare)
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Factors shaping workplace segregation between natives and immigrants
- 2014
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Ingår i: Demography. - : Springer. - 0070-3370 .- 1533-7790. ; 51:2, s. 645-671
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Tidskriftsartikel (refereegranskat)abstract
- Research on segregation of immigrant groups is increasingly turning its attention from residential areas toward other important places, such as the workplace, where immigrants can meet and interact with members of the native population. This article examines workplace segregation of immigrants. We use longitudinal, georeferenced Swedish population register data, which enables us to observe all immigrants in Sweden for the period 1990–2005 on an annual basis. We compare estimates from ordinary least squares with fixed-effects regressions to quantify the extent of immigrants' self-selection into specific workplaces, neighborhoods, and partnerships, which may bias more naïve ordinary least squares results. In line with previous research, we find lower levels of workplace segregation than residential segregation. The main finding is that low levels of residential segregation reduce workplace segregation, even after we take into account intermarriage with natives as well as unobserved characteristics of immigrants such as willingness and ability to integrate into the host society. Being intermarried with a native reduces workplace segregation for immigrant men but not for immigrant women.
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| 9. |
- Strömgren, M., et al.
(författare)
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The effect of interparticle contact area on the strength of cold-pressed aluminium powder compacts
- 1973
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Ingår i: Powder Metallurgy. - : Informa UK Limited. - 0032-5899 .- 1743-2901. ; 16:32, s. 155-165
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Tidskriftsartikel (refereegranskat)abstract
- Measurements of the tensile strength of spherical cold-pressed aluminium powder, pressed to various densities up to the theoretical maximum, have shown that compaction is a two-stage process. At some high, intermediate pressure, interparticle sliding occurs in a way that does not itself increase densification but makes it easier for further deformation to occur. It is likely that the pressure at which this sliding takes place is dependent on the work-hardening rate of the powder as well as the powder size and morphology. In any case, it is shown to be important to the densification and strength reached by the compact. It is concluded that the strength of a green compact is dependent upon the interparticle metallic contacts made during compaction. However, the green strength is well below that of wrought aluminium, probably due to the presence of broken-up oxides, which act as stress-concentrators at the interparticle boundaries.
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| 10. |
- Timpka, Toomas, et al.
(författare)
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Population-based simulations of influenza pandemics : validity and significance for public health policy
- 2009
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Ingår i: BULLETIN OF THE WORLD HEALTH ORGANIZATION. - 0042-9686 .- 1564-0604. ; 87:4, s. 305-311
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Tidskriftsartikel (refereegranskat)abstract
- Objective To examine the validity and usefulness of pandemic simulations aimed at informing practical decision-making in public health. Methods We recruited a multidisciplinary group of nine experts to assess a case-study simulation of influenza transmission in a Swedish county. We used a non-statistical nominal group technique to generate evaluations of the plausibility, formal validity (verification) and predictive validity of the simulation. A health-effect assessment structure was used as a framework for data collection. Findings The unpredictability, of social order during disasters was not adequately addressed by simulation methods; even minor disruptions of the social order may invalidate key infrastructural assumptions underpinning current pandemic simulation models. Further, a direct relationship between model flexibility and computation time was noted. Consequently, simulation methods cannot, in practice, support integrated modifications of microbiological, epidemiological and spatial submodels or handle multiple parallel scenarios. Conclusion The combination of incomplete surveillance data and simulation methods that neglect social dynamics limits the ability of national public health agencies to provide policy-makers and the general public with the critical and timely information needed during a pandemic.
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