| 1. |
- Santoro, Maurizio, et al.
(författare)
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Forest growing stock volume of the northern hemisphere : Spatially explicit estimates for 2010 derived from Envisat ASAR
- 2015
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Ingår i: Remote Sensing of Environment. - : Elsevier BV. - 0034-4257 .- 1879-0704. ; 168, s. 316-334
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents and assesses spatially explicit estimates of forest growing stock volume (GSV) of the northern hemisphere (north of 10 degrees N) from hyper-temporal observations of Envisat Advanced Synthetic Aperture Radar (ASAR) backscattered intensity using the BIOMASAR algorithm. Approximately 70,000 ASAR images at a pixel size of 0.01 degrees were used to estimate GSV representative for the year 2010. The spatial distribution of the GSV across four ecological zones (polar, boreal, temperate, subtropical) was well captured by the ASAR-based estimates. The uncertainty of the retrieved GSV was smallest in boreal and temperate forest (<30% for approximately 80% of the forest area) and largest in subtropical forest. ASAR-derived GSV averages at the level of administrative units were mostly in agreement with inventory-derived estimates. Underestimation occurred in regions of very high GSV (>300 m(3)/ha) and fragmented forest landscapes. For the major forested countries within the study region, the relative RMSE between ASAR-derived GSV averages at provincial level and corresponding values from National Forest Inventory was between 12% and 45% (average: 29%).
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| 2. |
- Bertilsson, Johan, et al.
(författare)
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Stress Levels Escalate When Repeatedly Performing Tasks Involving Threats
- 2019
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Ingår i: Frontiers in Psychology. - : Frontiers Media SA. - 1664-1078. ; 10, s. 1562-1562
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Tidskriftsartikel (refereegranskat)abstract
- Police work may include performing repeated tasks under the influence of psychological stress, which can affect perceptual, cognitive and motor performance. However, it is largely unknown how repeatedly performing stressful tasks physically affect police officers in terms of heart rate and pupil diameter properties. Psychological stress is commonly assessed by monitoring the changes in these biomarkers. Heart rate and pupil diameter was measured in 12 male police officers when performing a sequence of four stressful tasks, each lasting between 20 and 130 s. The participants were first placed in a dimly illuminated anteroom before allowed to enter a brightly lit room where a scenario was played out. After each task was performed, the participants returned to the anteroom for about 30 s before performing the next sequential task. Performing a repeated sequence of stressful tasks caused a significant increase in heart rate (p = 0.005). The heart rate started to increase already before entering the scenario room and was significantly larger just after starting the task than just before starting the task (p < 0.001). This pattern was more marked during the first tasks (p < 0.001). Issuance of a verbal "abort" command which terminated the tasks led to a significant increase of heart rate (p = 0.002), especially when performing the first tasks (p = 0.002). The pupil diameter changed significantly during the repeated tasks during all phases but in a complex pattern where the pupil diameter reached a minimum during task 2 followed by an increase during tasks 3 and 4 (p ≤ 0.020). During the initial tasks, the pupil size (p = 0.014) increased significantly. The results suggest that being repeatedly exposed to stressful tasks can produce in itself an escalation of psychological stress, this even prior to being exposed to the task. However, the characteristics of both the heart rate and pupil diameter were complex, thus, the findings highlight the importance of studying the effects and dynamics of different stress-generating factors. Monitoring heart rate was found useful to screen for stress responses, and thus, to be a vehicle for indication if and when rotation of deployed personnel is necessary to avoid sustained high stress exposures.
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| 3. |
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| 4. |
- Fransson, Åsa, 1971, et al.
(författare)
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Characterization of fractured crystalline rock: two Swedish in situ field experiments
- 2014
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Ingår i: 1st International Discrete Fracture Network Engineering Conference, 20-22 oct 2014, Vancouver, Canada.
-
Konferensbidrag (refereegranskat)abstract
- Construction of a nuclear waste repository requires information and an understanding of the fractured rock. The Swedish concept for nuclear waste deposition that is currently being developed by the Swedish Nuclear Fuel and Waste Management Co (SKB) includes a natural barrier in the form of crystalline rock, and engineered barriers in the form of bentonite and a copper canister. This paper aims to present two in situ field experiments: the first is the Large fractures experiment and the second is BRIE, the Bentonite Rock Interaction Experiment. Important issues include possible deformation (shearing) of fractures and deformation zones influencing the localization of canisters, and fluid flow, resulting in hydration of the bentonite. The aim of Large fractures is to further develop strategies and integrated investigation and modelling methodology for the identification and characterization of geological structures to ensure that (size) determination of large fractures or minor deformation zones to a greater extent can be based on real properties and to a lesser degree on a criterion related to the existence of a full perimeter fracture – tunnel intersection. BRIE is a field experiment which addresses the hydraulic interaction between the system components of compacted bentonite and the near-field host rock composed of hard and fractured bedrock. The above experiments are presented in terms of investigations performed to obtain discrete fracture descriptions. Grouting of fractures intersecting the investigation borehole of the Large fractures experiment was designed based on field data and a decrease in flow from above 200 liters/min to below 1 liter/min was achieved. The magnitude of the transmissivity of the fracture/deformation zone that was grouted indicates a large fracture size. This is also indicated by the ongoing integrated interpretation (geology, hydrogeology and geophysics). Results from BRIE show that hydration is uneven and is controlled by the main conductive fracture, highlighting the need for a relevant fracture description.
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| 5. |
- Fransson, Åsa, 1971, et al.
(författare)
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Swedish grouting design: hydraulic testing and grout selection
- 2016
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Ingår i: Ground Improvement. - : Thomas Telford Ltd.. - 1365-781X. ; 169:4, s. 275-285
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Tidskriftsartikel (refereegranskat)abstract
- © 2016, Thomas Telford Services Ltd. All rights reserved. To ensure successful sealing of rock and soil, an adequate description of the system to be grouted is required as a basis for the grouting design and the selection of the grouting material. In rock, the individual fractures and the hydraulic apertures of these fractures form the basis of the Swedish grouting design concept. The hydraulic aperture is a key parameter when describing grouting behaviour and it is used to determine the extent to which the grout can enter fractures - that is, the penetrability. The hydraulic aperture also determines the penetration length, and therefore the grout parameters (e.g. yield stress and viscosity) as well as the grouting pressure and time needed to be adopted to the hydraulic aperture. Once these parameters are chosen, a suitable grouting technique can be adopted. Simple, practical rock and grout tests are important inputs to ensure correct design and performance. The aim of this paper is to present a testing procedure and provide examples from laboratory and field experience to demonstrate that the approach also works in practice.
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| 6. |
- Kaluza, Johan, 1986-
(författare)
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Sjukskrivnas arbetsbörda : Arbetande medborgare möter en kundorienterad byråkrati
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Denna avhandling är baserad på en empirisk studie av Försäkringskassan. Teoretiskt tar avhandlingen sitt avstamp i litteraturen om arbetande konsumenter och kundorienterade byråkratier. Följande paradox utgör avhandlingens utgångspunkt: för att kvalificera för sjukförsäkring måste medborgarens förmåga att utföra sitt arbete vara begränsad samtidigt som handläggningen av sjukförsäkringen förutsätter att medborgaren utför arbete för att få tillgång till den. För att förklara hur paradoxen hanteras så är syftet med avhandlingen att kartlägga och förklara de praktiker som arbetande medborgares samt kundorienterade byråkrater, med stöd av andra aktörer, utför för att realisera sjukförsäkringen. Kartläggningen resulterar i konstaterandet att arbetet består av åtta praktiker uppdelade i två teman; stödpraktiker och kontrollpraktiker. Utifrån praktikteori diskuteras sedan hur dessa praktiker samspelar med varandra samt vad som inträffar då samspelet misslyckas. Avhandlingen identifierar även tre strategier som aktörerna använder när samspelet mellan praktiker misslyckas, nämligen korrigering, påtryckning och övertagande.Avhandlingen bidrar med ny kunskap genom att utveckla begreppet arbetande medborgare och genom att kartlägga arbetet som utförs för att realisera offentliga tjänster. Arbetet stimuleras delvis av medborgarnas oro av att göra fel inom försäkringen. Handläggare använder medborgarnas arbete för att underlätta sin arbetssituation genom vad som i avhandlingen benämns byråkratiskt samskapande. Utvecklingen av detta begrepp utgör avhandlingens andra centrala forskningsbidrag. Genom begreppet vidareutvecklas teorin om kundorienterade byråkratier. Begreppet skapar också en grund för en kritisk diskussion av begreppet samskapande inom tjänsteforskningen som förutsätter att medborgare fritt kan påverka utfallet av handläggningen. Avhandlingen visar dock att samskapande för medborgarna i princip uteslutande består av rutinmässig insamling och kontroll av uppgifter.
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| 7. |
- Neumann, M., et al.
(författare)
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Assessing Performance of L- and P-Band Polarimetric Interferometric SAR Data in Estimating Boreal Forest Above-Ground Biomass
- 2012
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Ingår i: IEEE Transactions on Geoscience and Remote Sensing. - 0196-2892 .- 1558-0644. ; 50:3, s. 714-726
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Tidskriftsartikel (refereegranskat)abstract
- Biomass estimation performance using polarimetric interferometric synthetic aperture radar (PolInSAR) data is evaluated at L- and P-band frequencies over boreal forest. PolInSAR data are decomposed into ground and volume contributions, retrieving vertical forest structure and polarimetric layer characteristics. The sensitivity of biomass to the obtained parameters is analyzed, and a set of these parameters is used for biomass estimation, evaluating one parametric and two non-parametric methodologies: multiple linear regression, support vector machine, and random forest. The methodology is applied to airborne SAR data over the Krycklan Catchment, a boreal forest test site in northern Sweden. The average forest biomass is 94 tons/ha and goes up to 183 tons/ha at forest stand level (317 tons/ha at plot level). The results indicate that the intensity at HH-VV is more sensitive to biomass than any other polarization at L-band. At P-band, polarimetric scattering mechanism type indicators are the most correlated with biomass. The combination of polarimetric indicators and estimated structure information, which consists of forest height and ground-volume ratio, improved the root mean square error (rmse) of biomass estimation by 17%-25% at L-band and 5%-27% at P-band, depending on the used parameter set. Together with additional ground and volume polarimetric characteristics, the rmse was improved up to 27% at L-band and 43% at P-band. The cross-validated biomass rmse was reduced to 20 tons/ha in the best case. Non-parametric estimation methods did not improve the cross-validated rmse of biomass estimation, but could provide a more realistic distribution of biomass values.
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| 8. |
- Neumann, M., et al.
(författare)
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Parametric and non-parametric forest biomass estimation from PolInSAR data
- 2011
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Ingår i: IEEE International Geoscience and Remote Sensing Symposium, IGARSS 2011. Vancouver, 24-29 July 2011. - 9781457710056 ; , s. 420-423, s. 420-423
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Konferensbidrag (refereegranskat)abstract
- Biomass estimation performance from model-based polarimetric SAR interferometry (PolInSAR) using generic parametric and non-parametric regression methods is evaluated at L- and P-band frequencies over boreal forest. PolInSAR data is decomposed into ground and volume contributions, estimating vertical forest structure, and using a set of obtained parameters for biomass regression. The considered estimation methods include multiple linear regression, support vector machine and random forest. The biomass estimation performance is evaluated on DLR's airborne SAR data at L- and P-bands over Krycklan Catchment, a boreal forest test site in Northern Sweden. The combination of polarimetric indicators and estimated structure information has improved the root mean square error (RMSE) of biomass estimation up to 28% at L-band and up to 46% at P-band. The cross-validated biomass RMSE was reduced to 20 tons/ha.
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| 9. |
- Nyström, Mattias, et al.
(författare)
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Detection of windthrown trees using airborne laser scanning
- 2014
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Ingår i: International Journal of Applied Earth Observation and Geoinformation. - : Elsevier BV. - 0303-2434 .- 1569-8432. ; 30, s. 21-29
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Tidskriftsartikel (refereegranskat)abstract
- In this study, a method has been developed for the detection of windthrown trees under a forest canopy, using the difference between two elevation models created from the same high density (65 points/m(2)) airborne laser scanning data. The difference image showing objects near the ground was created by subtracting a standard digital elevation model (DEM) from a more detailed DEM created using an active surface algorithm. Template matching was used to automatically detect windthrown trees in the difference image. The 54 ha study area is located in hemi-boreal forest in southern Sweden (Lat. 58 degrees 29' N, Long. 13 degrees 38' E) and is dominated by Norway spruce (Picea abies) with 3.5% deciduous species (mostly birch) and 1.7% Scots pine (Pinus sylvestris). The result was evaluated using 651 field measured windthrown trees. At individual tree level, the detection rate was 38% with a commission error of 36%. Much higher detection rates were obtained for taller trees; 89% of the trees taller than 27 m were detected. For pine the individual tree detection rate was 82%, most likely due to the more easily visible stem and lack of branches. When aggregating the results to 40 m square grid cells, at least one tree was detected in 77% of the grid cells which according to the field measurements contained one or more windthrown trees. (C) 2014 Elsevier B.V. All rights reserved.
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| 10. |
- Sandberg, Gustaf, 1982, et al.
(författare)
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L- and P-band backscatter intensity for biomass retrieval in hemiboreal forest
- 2011
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Ingår i: Remote Sensing of Environment. - : Elsevier BV. - 0034-4257 .- 1879-0704. ; 115:11, s. 2874 - 2886
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Tidskriftsartikel (refereegranskat)abstract
- At present, the greatest source of uncertainty in the global carbon cycle is in the terrestrial ecosystems. In orderto reduce these uncertainties it is necessary to provide consistent and accurate global estimates of the worldforest biomass. One of the most promising methods for obtaining such estimates is through polarimetric SARbackscatter measurements at low frequencies. In this paper, the relation between polarimetric SAR backscatterat L- and P-bands and forest biomass is investigated using data acquired within the BioSAR-I campaign insouthern Sweden during 2007. Methods for estimating biomass on stand level using these data are developedand evaluated, and the results for the two frequency bands are compared. For L-band data, the best results wereobtained using HV-polarized backscatter only, giving estimation errors in terms of root mean square errors(RMSE) between 31% and 46% of the mean biomass for stands with biomass ranging from 10 to 290 t/ha, and an(adjusted) coefficient of determination (R2) between 0.4 and 0.6. For P-band data, the results are better thanfor L-band. Models using HV- or HH-polarized P-band backscatter give similar results, as does a modelincluding both HV and HH. The RMSEs were between 18 and 27%, and the R2 values were between 0.7 and 0.8.
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| 11. |
- Sundström, Johan, Professor, 1971-, et al.
(författare)
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Risk factors for subarachnoid haemorrhage : a nationwide cohort of 950 000 adults
- 2019
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Ingår i: International Journal of Epidemiology. - : Oxford University Press. - 0300-5771 .- 1464-3685. ; 48:6, s. 2018-2025
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Subarachnoid haemorrhage (SAH) is a devastating disease, with high mortality rate and substantial disability among survivors. Its causes are poorly understood. We aimed to investigate risk factors for SAH using a novel nationwide cohort consortium.METHODS: We obtained individual participant data of 949 683 persons (330 334 women) between 25 and 90 years old, with no history of SAH at baseline, from 21 population-based cohorts. Outcomes were obtained from the Swedish Patient and Causes of Death Registries.RESULTS: During 13 704 959 person-years of follow-up, 2659 cases of first-ever fatal or non-fatal SAH occurred, with an age-standardized incidence rate of 9.0 [95% confidence interval (CI) (7.4-10.6)/100 000 person-years] in men and 13.8 [(11.4-16.2)/100 000 person-years] in women. The incidence rate increased exponentially with higher age. In multivariable-adjusted Poisson models, marked sex interactions for current smoking and body mass index (BMI) were observed. Current smoking conferred a rate ratio (RR) of 2.24 (95% CI 1.95-2.57) in women and 1.62 (1.47-1.79) in men. One standard deviation higher BMI was associated with an RR of 0.86 (0.81-0.92) in women and 1.02 (0.96-1.08) in men. Higher blood pressure and lower education level were also associated with higher risk of SAH.CONCLUSIONS: The risk of SAH is 45% higher in women than in men, with substantial sex differences in risk factor strengths. In particular, a markedly stronger adverse effect of smoking in women may motivate targeted public health initiatives.
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| 12. |
- Thörn, Johan, 1986, et al.
(författare)
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Fracture Deformation Measurements during Grouting in Hard Rock
- 2012
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Ingår i: Geotechnical Special Publication. - Reston, VA : American Society of Civil Engineers. - 0895-0563. - 9780784412350 ; :228 GSP, s. 836-845
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Konferensbidrag (refereegranskat)abstract
- When a fracture system in crystalline rock is grouted the rock mass may deform. Such deformations may reduce the grouting efficiency since new flow paths are opened. The work presented here show that deformations occur at hydraulic tests and grouting and that deformation can be measured and evaluated as stiffness from in situ tests. Deformation measurements, hydraulic testing, and grouting was conducted in spring 2010 in the Hallandsås tunnel and hydraulic testing in a service tunnel in Gothenburg (Runslätt and Thörn, 2010). For measuring physical deformation recently developed equipment from Chalmers University of Technology was used. Deformations were measured seven times in the same borehole. Three measurements were during grouting, and the remaining four from water pressure tests. Most deformations occurred at pump pressures of 1-1.4 MPa, which is lower than the calculated normal rock stress. Stiffness has been evaluated in several ways, including a new method, (Fransson, et al., 2010). Generally the evaluated stiffness is lower in the Hallandsås tunnel than in the Gothenburg tunnel. The results show agreement with other in situ experiments.
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| 13. |
- Ulander, Lars, 1962, et al.
(författare)
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BIOSAR 2010 - A SAR campaign in support to the BIOMASS mission
- 2011
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Ingår i: Proceedings of IGARSS 2011 Symposium, Vancouver, Canada, 24-29 July, 2011. - 9781457710056 ; , s. 1528-1531, s. 1528-1531
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The ESA funded campaign BioSAR 2010 was carried out at the forestry test site Remningstorp in southern Sweden, in support to the BIOMASS satellite mission under study. Fully polarimetric SAR data were successfully acquired at L- and P-band using ONERA's multi-frequency system SETHI. In addition with other data types gathered, e.g. LiDAR and in-situ measurements, the compiled data set will be used for analyses and comparisons with biomass estimation results obtained at the same test site in the campaign BioSAR 2007, in which DLR's E-SAR made the SAR imaging. Detection of forest changes, robustness of biomass retrieval algorithms and long-term P-band coherence will be in focus as well as cross-validations between the two SAR sensors.
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| 14. |
- Wallensten, Anders, et al.
(författare)
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Surveillance of influenza A virus in migratory waterfowl in northern Europe
- 2007
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Ingår i: Emerging Infectious Diseases. - 1080-6040 .- 1080-6059. - 1080-6040 ; 13:3, s. 404-411
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Tidskriftsartikel (refereegranskat)abstract
- We conducted large-scale, systematic sampling of influenza type A virus in migratory waterfowl (mostly mallards [Anas platyrhynchos]) at Ottenby Bird Observatory, southeast Sweden. As with previous studies, we found a higher prevalence in fall than spring, and among juveniles compared with adults. However, in contrast to other studies, we found that prevalence in spring was sometimes high (mean 4.0%, highest 9.5%). This finding raises the possibility that ducks are capable of perpetuating influenza A virus of different subtypes and subtype combinations throughout the year and from 1 year to the next. Isolation of the H5 and H7 subtypes was common, which suggests risk for transmission to sensitive domestic animals such as poultry. We argue that wild bird screening can function as a sentinel system, and we give an example of how it could have been used to forecast a remote and deadly outbreak of influenza A in poultry.
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| 15. |
- Aksoy, Samet, et al.
(författare)
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Forest Biophysical Parameter Estimation via Machine Learning and Neural Network Approaches
- 2023
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Ingår i: IGARSS 2023 - 2023 IEEE International Geoscience and Remote Sensing Symposium. - : IEEE. - 9798350320107 - 9798350320091 - 9798350331745 ; , s. 2661-2664
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Konferensbidrag (refereegranskat)abstract
- This paper presents the first results of the ongoing development of new forest mapping methods for the Swedish national forest mapping case using Airborne Laser Scanning (ALS) data, utilizing the recent findings in machine learning (ML) and Artificial Intelligence (AI) techniques. We used Random Forest (RF) and eXtreme Gradient Boosting (XGBoost) as ML models. In addition, Neural networks (NN) based approaches were utilized in this study. ALS derived features were used to estimate the stem volume (V), above-ground biomass (AGB), basal area (B), tree height (H), stem diameter (D), and forest stand age (A). XGBoost ML algorithm outperformed RF 1 % to 3 % in the R² metric. NN model performed similar to ML model, however it is superior in the estimation of V, AGB, and B parameters.
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| 16. |
- Alfredsson, Lars, et al.
(författare)
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Job strain and major risk factors for coronary heart disease. : Baseline results from the WOLF Study
- 2002
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Ingår i: Scandinavian Journal of Work, Environment & Health. - 0355-3140. ; 28:4, s. 238-248
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Tidskriftsartikel (refereegranskat)abstract
- The results do not support the hypothesis that job strain has an adverse impact on serum total cholesterol and plasma fibrinogen levels. They suggest that an increased risk of coronary heart disease in association with job strain, if causal, is mediated by other factors, possibly partly by hypertension and low levels of high-density lipoprotein cholesterol.
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| 17. |
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| 18. |
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| 19. |
- Askne, Jan, 1936, et al.
(författare)
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Model-Based Biomass Estimation of a Hemi-Boreal Forest from Multitemporal TanDEM-X Acquisitions
- 2013
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Ingår i: Remote Sensing. - : MDPI AG. - 2072-4292. ; 5:11, s. 5574-5597
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Tidskriftsartikel (refereegranskat)abstract
- Above-ground forest biomass is a significant variable in the terrestrial carbon budget, but is still estimated with relatively large uncertainty. Remote sensing methods can improve the characterization of the spatial distribution and estimation accuracy of biomass; in this respect, it is important to examine the potential offered by new sensors. To assess the contribution of the TanDEM-X mission, eighteen interferometric Synthetic Aperture Radar (SAR) image pairs acquired over the hemi-boreal test site of Remningstorp in Sweden were investigated. Three models were used for interpretation of TanDEM-X signatures and above-ground biomass retrieval: Interferometric Water Cloud Model (IWCM), Random Volume over Ground (RVoG) model, and a simple model based on penetration depth (PD). All use an allometric expression to relate above-ground biomass to forest height measured by TanDEM-X. The retrieval was assessed on 201 forest stands with a minimum size of 1 ha, and ranging from 6 to 267 Mg/ha (mean biomass of 105 Mg/ha) equally divided into a model training dataset and a validation test dataset. Biomass retrieved using the IWCM resulted in a Root Mean Square Error (RMSE) between 17% and 33%, depending on acquisition date and image acquisition geometry (angle of incidence, interferometric baseline, and orbit type). The RMSE in the case of the RVoG and the PD models were slightly higher. A multitemporal estimate of the above-ground biomass using all eighteen acquisitions resulted in an RMSE of 16% with R-2 = 0.93. These results prove the capability of TanDEM-X interferometric data to estimate forest aboveground biomass in the boreal zone.
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| 20. |
- Axelsson, Magnus, 1974, et al.
(författare)
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Design criteria for permeation grouting in hard rock at great depths
- 2008
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Ingår i: Proceedings World Tunnel Congress 2008, Underground facilities for better environmnet and saftey. ; 1, s. 510-520
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Tidskriftsartikel (refereegranskat)abstract
- Grouting at tunnelling in hard rock at great depths below the groundwater table, when constructing a nuclear waste repository for example, makes special demands on the strength of the grout in order to resist groundwater forces. The aim of this study is to distinguish the most important parameters to ensure that suitable grouting can be performed at large depths. Initially, laboratory studies were conducted in order to determine the most critical parameters. The results from the laboratory tests were used in a field study at the Äspö Hard Rock Laboratory in Sweden. The results indicate that the most important characteristics for the rock are the fracture aperture and the groundwater gradient and for the grout: a resolute grouting pressure and sufficient early strength. This implies that for cementitious grouts the yield stress is important and for non-cementitious grouts it is the shear strength prior to gelling. The results emphasise the need to perform hydraulic characterisation of the rock mass in advance. The results also show the importance of performing a proper grouting, especially at large depths where a decreased penetration length of the grout increases the risk of a high gradient and hence erosion of the grout.
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| 21. |
- Bargholtz, Chr., et al.
(författare)
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The WASA detector facility at CELSIUS
- 2008
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 594:3, s. 339-350
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Tidskriftsartikel (refereegranskat)abstract
- The WASA 4 pi multidetector system, aimed at investigating light meson production in light ion collisions and eta meson rare decays at the CELSIUS storage ring in Uppsala is presented. A unique feature of the system is the use of hydrogen pellets as internal targets for the first time. A detailed description of the design, together with the anticipated and achieved performance parameters are given. (C) 2008 Elsevier B.V. All rights reserved.
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| 22. |
- Bergström, Hans, 1952-, et al.
(författare)
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Wind power in forests : wind and effects on loads
- 2013
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Within the project V-312, Wind power in forests, researchers and a PhD student at Uppsala University, WeatherTech Scandinavia, the Royal Institute of Technology (KTH), DTU Wind Energy in Denmark and Teknikgruppen have been cooperating. Within the project atmospheric turbulence measurements with high vertical resolution have been done, also down between the trees, to make it possible to give better theoretical descriptions of the observed properties. Several mesoscale models have also been used to model the above forest winds. The atmospheric measurements have been complemented by wind tunnel measurements using a wind tunnel floor designed with small cylindrical wooden sticks that should simulate the effect of the trees generating a known momentum sink able to affect the flow. The combined new knowledge about the forest boundary layer wind and turbulence properties have been used as input to a dynamical wind turbine computer model, used to simulate the turbine load response to the turbulent wind field.
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| 23. |
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| 24. |
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| 25. |
- Bertilsson, Johan, et al.
(författare)
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Towards systematic and objective evaluation of police officer performance in stressful situations
- 2020
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Ingår i: Police Practice and Research. - : Informa UK Limited. - 1561-4263 .- 1477-271X. ; 21:6, s. 655-669
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Tidskriftsartikel (refereegranskat)abstract
- To ensure a continuous high standard of police units, it is critical to recruit people who perform well in stressful situations. Today, this selection process includes performing a large series of tests, which still may not objectively reveal a person’s capacity to handle a life-threatening situation when subjected to high levels of stress. To obtain more systematic and objective data, 12 police officers were exposed to six scenarios with varying levels of threat while their heart rate and pupil size were monitored. The scenarios were filmed and six expert evaluators assessed the performance of the police officers according to seven predefined criteria. Four of the scenarios included addressing a moderate threat level task and the scenarios were executed in a rapid sequence. Two further scenarios included a familiar firearm drill performed during high and low threat situations. The results showed that there was a large agreement between the experts in how they judged the performance of the police officers (p < 0.001). Performance increased significantly over tasks in four of the seven evaluation criteria (p ≤ 0.037). There was also a significant effect of pupil size (p = 0.004), but not heart rate, when comparing the different sequential scenarios. Moreover, a high level of threat considerably impaired the motor performance of the police officers during the firearms drill (p = 0.002). Finally, the pupil seemed to systematically dilate more when a threat appeared immediately than with a delay in the scenarios (p = 0.007). We conclude that systematic and quantitative judgments from experts provide valuable and reliable information about the performance of participants in realistic and stressful policing scenarios. Furthermore, objective physiological measures of heart rate and pupil size may help to explain and understand why performance sometimes deteriorates.
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| 26. |
- Bhattacharyya, Anirban, et al.
(författare)
-
ESS RF Source and Spoke Cavity Test Plan
- 2015
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This report describes the test plan for the first high power RF source, ESS prototype double spoke cavity and ESS prototype cryomodule at the FREIA Laboratory.
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| 27. |
- Bohlin, Jonas, et al.
(författare)
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A comparison of forest inventories based on aerial image matching and Airborne Laser Scanning data
- 2014
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Forest inventories are now commonly done by Airborne Laser Scanning (ALS), especially because many countries are collecting ALS data nation-wide to produce high quality elevation data. With an accurate digital elevation model, 3D data from aerial image matching could be a more cost-effective alternative to repeated ALS acquisitions for providing updated data to forest management planning in the future. This study aims at comparing the quality of forest inventory data obtained by aerial image matching and ALS. In the study area, a mixed boreal forest situated in central Sweden, aerial images from the national acquisition program with a ground sampling distance of 0.5 m and ALS data with a point density of 1.5-2 pulses per m2 from the national ALS production were available. The aerial images were matched with three different algorithms to assess possible differences in forest information content. Two hundred field plots, located within the study area, were utilized for non-parametric prediction of forest variables using random forest. Accuracy assessment was made by leave-one-out cross-validation at plot level. The results show similar accuracy of ALS and image matching-based predictions, with ALS slightly superior. Accuracy, in terms of root mean square errors in percent of surveyed plot mean, of ALS were: 6.4% for tree height; 12.5% for tree diameter; 18.2% for basal area and 20.0% for stem volume, and of image matching: 9.5% for tree height; 15.3% for tree diameter; 21.8% for basal area and 24.8% for stem volume. Among the image matching algorithms used, SURE was found to estimate the forest variables with best accuracies. However, the other algorithms produced similar results. These results indicate that inventory data acquired by matching of aerial images have a large potential for operational use in forest management planning as a cost-effective alternative to new ALS campaigns.
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| 28. |
- Bohlin, Jonas, et al.
(författare)
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Deciduous forest mapping using change detection of multi-temporal canopy height models from aerial images acquired at leaf-on and leaf-off conditions
- 2016
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Ingår i: Scandinavian Journal of Forest Research. - : Informa UK Limited. - 0282-7581 .- 1651-1891. ; 31, s. 517-525
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Tidskriftsartikel (refereegranskat)abstract
- Discrimination of deciduous trees using spectral information from aerial images has only been partly successfully due to the complexity of the reflectance at different view angles, times of acquisition, phenology of the trees and inter-tree radiance. Therefore, the objective was to evaluate the accuracy of estimating the proportion of deciduous stem volume (P) utilizing change detection between canopy height models (CHMs) generated by digital photogrammetry from leaf-on and leaf-off aerial images instead of using spectral information. The study was conducted at a hemiboreal study area in Sweden. Using aerial images from three seasons, CHMs with a resolution of approximately 0.5 m were generated using semi-global matching. For training plots, metrics describing the change between leaf-on and leaf-off conditions were calculated and used to model the continuous variable P, using the Random Forest approach. Validated at sub-stands, the estimation accuracy of P in terms of root mean square error and bias was found to be 18% and −6%, respectively. The overall classification accuracy, using four equally wide classes, was 83% with a kappa value of 0.68. The validation plots in classes of high proportion of coniferous or deciduous stem volume were well classified, whereas the mixed forest classes showed lower classification accuracies.
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| 29. |
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| 30. |
- Bohlin, Jonas, et al.
(författare)
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Extraction of Spectral Information from Airborne 3D Data for Assessment of Tree Species Proportions
- 2021
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Ingår i: Remote Sensing. - : MDPI AG. - 2072-4292. ; 13
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Tidskriftsartikel (refereegranskat)abstract
- With the rapid development of photogrammetric software and accessible camera technology, land surveys and other mapping organizations now provide various point cloud and digital surface model products from aerial images, often including spectral information. In this study, methods for colouring the point cloud and the importance of different metrics were compared for tree species-specific estimates at a coniferous hemi-boreal test site in southern Sweden. A total of three different data sets of aerial image-based products and one multi-spectral lidar data set were used to estimate tree species-specific proportion and stem volume using an area-based approach. Metrics were calculated for 156 field plots (10 m radius) from point cloud data and used in a Random Forest analysis. Plot level accuracy was evaluated using leave-one-out cross-validation. The results showed small differences in estimation accuracy of species-specific variables between the colouring methods. Simple averages of the spectral metrics had the highest importance and using spectral data from two seasons improved species prediction, especially deciduous proportion. Best tree species-specific proportion was estimated using multi-spectral lidar with 0.22 root mean square error (RMSE) for pine, 0.22 for spruce and 0.16 for deciduous. Corresponding RMSE for aerial images was 0.24, 0.23 and 0.20 for pine, spruce and deciduous, respectively. For the species-specific stem volume at plot level using image data, the RMSE in percent of surveyed mean was 129% for pine, 60% for spruce and 118% for deciduous.
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| 31. |
- Bohlin, Jonas, et al.
(författare)
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Forest variable estimation using photogrammetric matching of digital aerial images in combination with a high-resolution DEM
- 2012
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Ingår i: Scandinavian Journal of Forest Research. - : Informa UK Limited. - 0282-7581 .- 1651-1891. ; 27, s. 692-699
-
Tidskriftsartikel (refereegranskat)abstract
- The rapid development in aerial digital cameras in combination with the increased availability of high-resolution Digital Elevation Models (DEMs) provides a renaissance for photogrammetry in forest management planning. Tree height, stem volume, and basal area were estimated for forest stands using canopy height, density, and texture metrics derived from photogrammetric matching of digital aerial images and a high-resolution DEM. The study was conducted at a coniferous hemi-boreal site in southern Sweden. Three different data-sets of digital aerial images were used to test the effects of flight altitude and stereo overlap on an area-based estimation of forest variables. Metrics were calculated for 344 field plots (10 m radius) from point cloud data and used in regression analysis. Stand level accuracy was evaluated using leave-one-out cross validation of 24 stands. For these stands the tree height ranged from 4.8 to 26.9 m (17.8 m mean), stem volume 13.3 to 455 m3 ha-1 (250 m3 ha-1 mean), and basal area from 4.1 to 42.9 m2 ha-1 (27.1 m2 ha-1 mean) with mean stand size of 2.8 ha. The results showed small differences in estimation accuracy of forest variables between the data-sets. The data-set of digital aerial images corresponding to the standard acquisition of the Swedish National Land Survey (Lantma¨teriet), showed Root Mean Square Errors (in percent of the surveyed stand mean) of 8.8% for tree height, 13.1% for stem volume and 14.9% for basal area. The results imply that photogrammetric matching of digital aerial images has significant potential for operational use in forestry.
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| 32. |
- Bohlin, Jonas, et al.
(författare)
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Species-specific forest variable estimation using non-parametric modeling of multi-spectral photogrammetric point cloud data
- 2012
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The recent development in software for automatic photogrammetric processing of multispectral aerial imagery, and the growing nation-wide availability of Digital Elevation Model (DEM) data, are about to revolutionize data capture for forest management planning in Scandinavia. Using only already available aerial imagery and ALS-assessed DEM data, raster estimates of the forest variables mean tree height, basal area, total stem volume, and species-specific stem volumes were produced and evaluated. The study was conducted at a coniferous hemi-boreal test site in southern Sweden (lat. 58° N, long. 13° E). Digital aerial images from the Zeiss/Intergraph Digital Mapping Camera system were used to produce 3D point-cloud data with spectral information. Metrics were calculated for 696 field plots (10 m radius) from point-cloud data and used in k-MSN to estimate forest variables. For these stands, the tree height ranged from 1.4 to 33.0 m (18.1 m mean), stem volume from 0 to 829 m3 ha-1 (249 m3 ha-1 mean) and basal area from 0 to 62.2 m2 ha-1 (26.1 m2 ha-1 mean), with mean stand size of 2.8 ha. Estimates made using digital aerial images corresponding to the standard acquisition of the Swedish National Land Survey (Lantmäteriet) showed RMSEs (in percent of the surveyed stand mean) of 7.5% for tree height, 11.4% for basal area, 13.2% for total stem volume, 90.6% for pine stem volume, 26.4 for spruce stem volume, and 72.6% for deciduous stem volume. The results imply that photogrammetric matching of digital aerial images has significant potential for operational use in forestry.
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| 33. |
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| 34. |
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| 35. |
- Bratt, Ola, 1963, et al.
(författare)
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The Swedish national guidelines on prostate cancer, part 1: early detection, diagnostics, staging, patient support and primary management of non-metastatic disease
- 2022
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Ingår i: Scandinavian Journal of Urology. - : Medical Journals Sweden AB. - 2168-1805 .- 2168-1813. ; 56:4, s. 265-273
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Tidskriftsartikel (refereegranskat)abstract
- Objective There is now an unprecedented amount of evidence to consider when revising prostate cancer guidelines. We believe that there is a value in publishing summaries of national clinical guidelines in English for others to read and comment on. Methods This is part 1 of a summary of the Swedish prostate cancer guidelines that were published in June 2022. It covers the early detection, diagnostics, staging, patient support and management of the non-metastatic disease. Part 2 covers recurrence after local treatment and management of the metastatic disease. Results The 2022 Swedish guidelines include several new recommendations: rectal iodine-povidone to reduce post-biopsy infections, external beam radiation with focal boost to the tumour, use of a pre-rectal spacer to reduce rectal side effects after external beam radiotherapy in some expert centres, 6 months' concomitant and adjuvant rather than neoadjuvant and concomitant hormonal treatment together with radiotherapy for unfavourable intermediate and high-risk disease, and adjuvant abiraterone plus prednisolone together with a GnRH agonist for a subgroup of men with very high-risk disease. The Swedish guidelines differ from the European by having more restrictive recommendations regarding genetic testing and pelvic lymph node dissection, the risk group classification, recommending ultra-hypofractionated (7 fractions) external radiotherapy for intermediate and selected high-risk cancers, by not recommending any hormonal treatment together with radiotherapy for favourable intermediate-risk disease, and by recommending bicalutamide monotherapy instead of a GnRH agonist for some patient groups. Conclusions The 2022 Swedish prostate cancer guidelines include several new recommendations and some that differ from the European guidelines.
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| 36. |
- Bratt, Ola, 1963, et al.
(författare)
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The Swedish national guidelines on prostate cancer, part 2: recurrent, metastatic and castration resistant disease
- 2022
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Ingår i: Scandinavian Journal of Urology. - : Medical Journals Sweden AB. - 2168-1805 .- 2168-1813. ; 56:4, s. 278-284
-
Tidskriftsartikel (refereegranskat)abstract
- Objective There is now an unprecedented amount of evidence to consider when revising prostate cancer guidelines. We believe that there is a value in publishing summaries of national clinical guidelines in English for others to read and comment on. Methods This is part 2 of a summary of the Swedish prostate cancer guidelines that were published in June 2022. This part covers recurrence after local treatment and management of metastatic and castration resistant disease. Part 1 covers early detection, diagnostics, staging, patient support and management of non-metastatic disease. Results The 2022 Swedish guidelines include several new recommendations. Among these is a recommendation of a period of observation with repeated PSA tests for patients with approximately 10 years' life expectancy who experience a BCR more than 2-5 years after radical prostatectomy, to allow for estimating the PSA doubling time before deciding whether to give salvage radiotherapy or not. Recent results from the PEACE-1 trial led to the recommendation of triple-treatment with a GnRH agonist, abiraterone plus prednisolone and 6 cycles of docetaxel for patients with high-volume metastatic disease who are fit for chemotherapy. The Swedish guidelines differ from the European ones by having more restrictive recommendations about genetic testing of and high-dose zoledronic acid or denosumab treatment for men with metastatic prostate cancer, and by recommending considering bicalutamide monotherapy for selected patients with low-volume metastatic disease. Conclusions The 2022 Swedish prostate cancer guidelines include several new recommendations and some that differ from the European guidelines.
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| 37. |
- Butron, Christian, 1978, et al.
(författare)
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Drip sealing of tunnels in hard rock: A new concept for the design and evaluation of permeation grouting
- 2010
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Ingår i: Tunnelling and Underground Space Technology. - : Elsevier BV. - 0886-7798. ; 25:2, s. 114-121
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a new pre-excavation grouting concept to prevent dripping and reduce the inflow into a railway tunnel. For this purpose, the tunnel's roof was drip-sealed using colloidal silica and the walls and invert of the tunnel were grouted with cement. The grouting design process followed a structured approach with pre-investigations of core-drilled boreholes providing parameters for the layout. Water pressure tests and pressure volume time recordings were used for the evaluation. Results showed that the design was successful: the total transmissivity was reduced from 4.9 x 10(-08) m(2)/s to the measurement limit (1.6 x 10(-08) m(2)/s), and the dripping was reduced to eight spots from the roof. Improved rock characterisation showed that the grout hole separation was within the transmissivity correlation length and that grouting efficiency depends to a large extent on the dimensionality of the flow system of the rock mass. (c) 2009 Elsevier Ltd. All rights reserved.
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| 38. |
- Casselgren, Johan, et al.
(författare)
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Investigation of ice surface change during vehicle testing
- 2014
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Ingår i: International Journal of Vehicle Systems Modelling and Testing. - 1745-6436 .- 1745-6444. ; 9:2, s. 137-150
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Tidskriftsartikel (refereegranskat)abstract
- Today, there are a lot of vehicles and tyre testing carried out on lake ice surfaces. Thus, it is important to have knowledge about parameters that affect roadgrip. The thesis within this paper is that the liquid like layer which appears due to increasing temperature can be reduced by manipulating the ice roughness. This in turn should decrease the temperature dependence of the roadgrip in temperatures around 0°C. In order to investigate this, measurements of temperature, surface roughness and hardness and roadgrip were performed on three outdoor ice surfaces using an IR thermometer, an optical sensor with three IR-diodes, a steel ball drop indentation test and an RT3 curve, respectively. Additional ice roughness measurements were also made on two tempered ice surfaces in an ice hall. Results show a clear connection between ice temperature and roadgrip, unfortunately the created ice roughness was too small to influence the change in roadgrip
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| 39. |
- Chi, Jinshu, et al.
(författare)
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The carbon balance of a managed boreal landscape measured from a tall tower in northern Sweden
- 2019
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Ingår i: Agricultural and Forest Meteorology. - : Elsevier BV. - 0168-1923 .- 1873-2240. ; 274, s. 29-41
-
Tidskriftsartikel (refereegranskat)abstract
- Boreal forests exchange large amounts of carbon dioxide (CO2) with the atmosphere. A managed boreal landscape usually comprises various potential CO2 sinks and sources across forest stands of varying age classes, clear-cut areas, mires, and lakes. Due to this heterogeneity and complexity, large uncertainties exist regarding the net CO2 balance at the landscape scale. In this study, we present the first estimate of the net CO2 exchange over a managed boreal landscape (∼68 km2) in northern Sweden, based on tall tower eddy covariance measurements. Our results suggest that from March 1, 2016 to February 28, 2018, the heterogeneous landscape was a net CO2 sink with a 2-year mean uptake of −87 ± 6 g C m−2 yr−1. Due to an earlier and warmer spring and sunnier autumn, the landscape was a stronger CO2 sink during the first year (−122 ± 8 g C m−2) compared to the second year (−52 ± 9 g C m−2). Footprint analysis shows that 87% of the CO2 flux measurements originated from forests, whereas mires, clear-cuts, lakes, and grassland contributed 11%, 1%, 0.7%, and 0.2%, respectively. Altogether, the CO2 sink strength of the heterogeneous landscape was up to 38% lower compared to the sink strength of a mature stand surrounding the tower. Overall, this study suggests that the managed boreal landscape acted as a CO2 sink and advocates tall tower eddy covariance measurements to improve regional carbon budget estimates.
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| 40. |
- Chi, Jinshu, et al.
(författare)
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The Net Landscape Carbon Balance—Integrating terrestrial and aquatic carbon fluxes in a managed boreal forest landscape in Sweden
- 2020
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Ingår i: Global Change Biology. - : Wiley. - 1354-1013 .- 1365-2486. ; 26:4, s. 2353-2367
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Tidskriftsartikel (refereegranskat)abstract
- The boreal biome exchanges large amounts of carbon (C) and greenhouse gases (GHGs) with the atmosphere and thus significantly affects the global climate. A managed boreal landscape consists of various sinks and sources of carbon dioxide (CO2), methane (CH4), and dissolved organic and inorganic carbon (DOC and DIC) across forests, mires, lakes, and streams. Due to the spatial heterogeneity, large uncertainties exist regarding the net landscape carbon balance (NLCB). In this study, we compiled terrestrial and aquatic fluxes of CO2, CH4, DOC, DIC, and harvested C obtained from tall-tower eddy covariance measurements, stream monitoring, and remote sensing of biomass stocks for an entire boreal catchment (~68 km2) in Sweden to estimate the NLCB across the land–water–atmosphere continuum. Our results showed that this managed boreal forest landscape was a net C sink (NLCB = 39 g C m−2 year−1) with the landscape–atmosphere CO2 exchange being the dominant component, followed by the C export via harvest and streams. Accounting for the global warming potential of CH4, the landscape was a GHG sink of 237 g CO2-eq m−2 year−1, thus providing a climate-cooling effect. The CH4 flux contribution to the annual GHG budget increased from 0.6% during spring to 3.2% during winter. The aquatic C loss was most significant during spring contributing 8% to the annual NLCB. We further found that abiotic controls (e.g., air temperature and incoming radiation) regulated the temporal variability of the NLCB whereas land cover types (e.g., mire vs. forest) and management practices (e.g., clear-cutting) determined their spatial variability. Our study advocates the need for integrating terrestrial and aquatic fluxes at the landscape scale based on tall-tower eddy covariance measurements combined with biomass stock and stream monitoring to develop a holistic understanding of the NLCB of managed boreal forest landscapes and to better evaluate their potential for mitigating climate change.
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| 41. |
- Dahl, Mats, et al.
(författare)
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Analysis of eyewitness testimony in a police shooting with fatal outcome - Manifestations of spatial and temporal distortions
- 2018
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Ingår i: Cogent Psychology. - : Taylor & Francis. - 2331-1908. ; 5:1
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Tidskriftsartikel (refereegranskat)abstract
- Eyewitness statements are commonly used in the criminal justice system and viewed as having a high-probative value, especially when the witness has no motive to lie, other witness recollection corroborates the account, orthe witness is highly confident. A fatal police shooting incident in Sweden had 13 witnesses (nine civilians and four police officers) and was also filmed with two mobile phones. All interviews were conducted before witnesses viewed the films, allowing for the analysis of discrepancies between their statements and the videos. In this incident, a police patrol was sent to find out a man who was reported to have attacked two persons with a knife. When found, the perpetrator refused to obey the officer's commands, and the police eventually shot at him. The analysis showed clear differences between the witness testimonies and the film. Elements associated with perceived threat, for example, the assailant's armament and movement direction and number of shots fired, were remembered fairly accurately. However, most witnesses poorly recollected when, that is, after which shot, the assailant fell to the ground. Moreover, memory of the actual order of events was altered and important aspects omitted that were crucial from a legal point of view.
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| 42. |
- Dahlqvist, Johan, 1987-, et al.
(författare)
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TEST TURBINE INSTRUMENTATION FOR CAVITY PURGE INVESTIGATIONS
- 2014
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Ingår i: The XXII Symposium on Measuring Techniques in Turbomachinery, Lyon, 4-5 September 2014.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The upstream wheelspace of the KTH Test Turbine has been instrumented with the aim of investigating cavity flow phenomena, as well as cavity-main annulus interaction. Measurements include static pressure, unsteady pressure and temperature.The stage used is of high pressure steam turbine design. The trials include investigating the design point and also a high pressure, high speed operating point, assimilating gas turbine operation. At each point, varying amounts of purge flow are superposed and the influences on the measurements studied.Initial results show considerable dependence of both operating
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| 43. |
- Doeweler, Fabian, et al.
(författare)
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Linking High-Resolution UAV-Based Remote Sensing Data to Long-Term Vegetation Sampling : A Novel Workflow to Study Slow Ecotone Dynamics
- 2024
-
Ingår i: Remote Sensing. - : MDPI. - 2072-4292. ; 16:5
-
Tidskriftsartikel (refereegranskat)abstract
- Unravelling slow ecosystem migration patterns requires a fundamental understanding of the broad-scale climatic drivers, which are further modulated by fine-scale heterogeneities just outside established ecosystem boundaries. While modern Unoccupied Aerial Vehicle (UAV) remote sensing approaches enable us to monitor local scale ecotone dynamics in unprecedented detail, they are often underutilised as a temporal snapshot of the conditions on site. In this study in the Southern Alps of New Zealand, we demonstrate how the combination of multispectral and thermal data, as well as LiDAR data (2019), supplemented by three decades (1991-2021) of treeline transect data can add great value to field monitoring campaigns by putting seedling regeneration patterns at treeline into a spatially explicit context. Orthorectification and mosaicking of RGB and multispectral imagery produced spatially extensive maps of the subalpine area (similar to 4 ha) with low spatial offset (Craigieburn: 6.14 +/- 4.03 cm; Mt Faust: 5.11 +/- 2.88 cm, mean +/- standard error). The seven multispectral bands enabled a highly detailed delineation of six ground cover classes at treeline. Subalpine shrubs were detected with high accuracy (up to 90%), and a clear identification of the closed forest canopy (Fuscospora cliffortioides, >95%) was achieved. Two thermal imaging flights revealed the effect of existing vegetation classes on ground-level thermal conditions. UAV LiDAR data acquisition at the Craigieburn site allowed us to model vegetation height profiles for similar to 6000 previously classified objects and calculate annual fine-scale variation in the local solar radiation budget (20 cm resolution). At the heart of the proposed framework, an easy-to-use extrapolation procedure was used for the vegetation monitoring datasets with minimal georeferencing effort. The proposed method can satisfy the rapidly increasing demand for high spatiotemporal resolution mapping and shed further light on current treeline recruitment bottlenecks. This low-budget framework can readily be expanded to other ecotones, allowing us to gain further insights into slow ecotone dynamics in a drastically changing climate.
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| 44. |
- Dumarey, Melanie, 1982-, et al.
(författare)
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Combining experimental design and orthogonal projections to latent structures to study the influence of microcrystalline cellulose properties on roll compaction
- 2011
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Ingår i: International Journal of Pharmaceutics. - : Elsevier. - 0378-5173 .- 1873-3476. ; 416:1, s. 110-119
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Tidskriftsartikel (refereegranskat)abstract
- Roll compaction is gaining importance in pharmaceutical industry for the dry granulation of heat or moisture sensitive powder blends with poor flowing properties prior to tabletting. We studied the influence of microcrystalline cellulose (MCC) properties on the roll compaction process and the consecutive steps in tablet manufacturing. Four dissimilar MCC grades, selected by subjecting their physical characteristics to principal components analysis, and three speed ratios, i.e. the ratio of the feed screw speed and the roll speed of the roll compactor, were included in a full factorial design. Orthogonal projection to latent structures was then used to model the properties of the resulting roll compacted products (ribbons, granules and tablets) as a function of the physical MCC properties and the speed ratio. This modified version of partial least squares regression separates variation in the design correlated to the considered response from the variation orthogonal to that response. The contributions of the MCC properties and the speed ratio to the predictive and orthogonal components of the models were used to evaluate the effect of the design variation. The models indicated that several MCC properties, e.g. bulk density and compressibility, affected all granule and tablet properties, but only one studied ribbon property: porosity. After roll compaction, Ceolus KG 1000 resulted in tablets with obvious higher tensile strength and lower disintegration time compared to the other MCC grades. This study confirmed that the particle size increase caused by roll compaction is highly responsible for the tensile strength decrease of the tablets.
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| 45. |
- Dumarey, Melanie, et al.
(författare)
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OPLS methods for the analysis of hyperspectral images—comparison with MCR-ALS
- 2014
-
Ingår i: Journal of Chemometrics. - : John Wiley & Sons. - 0886-9383 .- 1099-128X. ; 28:8, s. 687-696
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Tidskriftsartikel (refereegranskat)abstract
- Two new orthogonal projections to latent structures (OPLS) based methods were proposed to analyze hyperspectral images, enabling the visualization ofmultiple chemical compounds in onematrix without the need of extensive preprocessing. Both proposed methods delivered images representing the chemical distribution in the ribbon similar to the more traditional multivariate curve resolution–alternating least squares (MCR-ALS) method, but their image background was less dynamic resulting in a stronger chemical contrast. This indicated that the methods successfully removed structured variation orthogonal to the chemical information (pure spectra of individual compounds), which was confirmed by the fact that physical scattering effects caused by grooves and edges were captured in the images visualizing the orthogonal components of the model. Hereby, the OPLS-based method employing the pure spectra as weights in the OPLS algorithm was more successful in distinguishing compounds with a similar spectral signal than the transposed OPLS algorithm(pure spectra of individual compounds were used as response in OPLS model). It should be noted that for the main compounds, the MCR-ALS method enabled easier visual interpretation compared to the OPLS-based methods by setting all values below zero to zero, resulting in a higher contrast between pixels containing the studied compound and pixels not containing that compound.
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| 46. |
- Engen, Marit, et al.
(författare)
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Continuing the development of the public service logic : a study of value co-destruction in public services
- 2021
-
Ingår i: Public Management Review. - : Taylor & Francis. - 1471-9037 .- 1471-9045. ; 23:6, s. 886-905
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Tidskriftsartikel (refereegranskat)abstract
- This paper reports on a study of value co-destruction in public services, i.e. diminishment of value by interaction between providers, users, and other actors. The goal is to contribute to the public service logic (PSL) that suggest a shift from linear co-production to dynamic value co-creation. However, PSL has devoted scant attention to value co-destruction. The paper contributes by identifying four dimensions representing causes of value co-destruction in public services. The paper also shows how value may be co-destroyed in the interaction between several types of actors, thus advancing a service ecosystems perspective for understanding value co-destruction.
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| 47. |
- Eriksson, Leif, 1970, et al.
(författare)
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Backscatter signatures of wind-thrown forest in satellite SAR images
- 2012
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Ingår i: International Geoscience and Remote Sensing Symposium (IGARSS). - 2153-6996 .- 2153-7003. - 9781467311588 ; , s. 6435-6438
-
Konferensbidrag (refereegranskat)abstract
- Two field experiments have been conducted in Sweden to allow an evaluation of the backscatter signatures of wind-thrown forest from L-band, C-band and X-band Synthetic Aperture Radar. When the trees are felled the backscattered signal from TerraSAR-X (X-band) increase with about 1.5 dB, while for ALOS PALSAR (L-band) a decrease with the same amount is observed. Radar images with fine spatial resolution also show shadowing effects that should be possible to use for identification of storm felled forest.
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| 48. |
- Fjeld, Dag, et al.
(författare)
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Modelling forest road trafficability with satellite-based soil moisture variables
- 2024
-
Ingår i: International Journal of Forest Engineering. - : Taylor & Francis Group. - 1494-2119 .- 1913-2220. ; 35:1, s. 93-104
-
Tidskriftsartikel (refereegranskat)abstract
- Recent decades have seen increased temperatures and precipitation in the Nordic countries with long-term projections for reduced frost duration and depth. The consequence of these trends has been a gradual shift of delivery volumes to the frost-free season, requiring more agile management to exploit suitable weather conditions. Bearing capacity and trafficability are dependent on soil moisture state and in this context two satellite missions offer potenially useful information on soil moisture levels; NASA's SMAP (Soil Moisture Active Passive) and ESA's Sentinel-1. The goal of this pilot study was to quantify the performance of such satellite-based soil moisture variables for modeling forest road bearing capacity (e-module) during the frost-free season. The study was based on post-transport registrations of 103 forest road segments on the coastal and interior side of the Scandinavian mountain range. The analysis focused on roads of three types of surface deposits. Weekly SMAP soil moisture values better explained the variation in road e-module than soil water index (SWI) derived from Sentinel-1. Soil Water Index (SWI), however, reflected the weather conditions typical for operations on the respective surface deposit types. Regression analysis using (i) SMAP-based soil dryness index and (ii) its interaction with surface deposit types, together with (iii) the ratio between a combined SMAP_SWI dryness index and segment-specific depth to water (DTW) explained over 70% of the variation in road e-module. The results indicate a future potential to monitor road trafficability over large supply areas on a weekly level, given further refinement of study methods and variables for improved prediction.
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| 49. |
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| 50. |
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