| 1. |
- Piikki, Kristin, et al.
(författare)
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Digital soil mapping for modelling of transport pathways for pesticides to surface water
- 2015
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Detailed spatial information of soil texture and SOM content are needed for the modelling of pesticide fate. As part of the SLF project Transport pathways for pesticides to surface water (SLFH1133108) such maps were derived for three depth layers of the soil profile in two sub-catchments with a total area of 450 ha. Data from proximal sensor measurements were combined with national datasets (a digital elevation model and a Quaternary deposit map) and calibrated against soil sample data. Different modelling strategies were tested and the best strategy for each layer was selected for production of the final maps. For topsoil texture, Marsplines modelling with a reduced number of covariables gave the best results (the final models included topographic variables and gamma radiation). In the upper subsoil, the texture was best predicted by an empirical relationship to the topsoil predictions. This is not surprising since the number of calibration samples in the subsoil was very small (n = 18) compared to the number of calibration samples (n = 85). In the deep subsoil, the best strategy was again to use Marsplines modelling with a reduced number of covariables. The SOM content in the topsoil and was mapped by Marsplines modelling using a limited number of predictors and allowing interactions. In the subsoil, however, all soil samples but one had SOM < 3 % and the entire area was classified as as SOM class u. Organic soils according to the SGU QD map (peat areas) were not included in the mapping. Instead they were directly assigned as SOM class t and the texture was not determined.
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| 2. |
- Ren, Keni, 1983-, et al.
(författare)
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Where do we find missing data in a commercial real-time location system? Evidence from 2 dairy farms
- 2021
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Ingår i: JDS Communications. - : American Dairy Science Association. - 2666-9102. ; 2, s. 345-350
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Tidskriftsartikel (refereegranskat)abstract
- Real-time indoor positioning using ultra-wideband devices provides an opportunity for modern dairy farms to monitor the behavior of individual cows; however, missing data from these devices hinders reliable continuous monitoring and analysis of animal movement and social behavior. The objective of this study was to examine the data quality, in terms of missing data, in one commercially available ultra-wideband–based real-time location system for dairy cows. The focus was on detecting major obstacles, or sections, inside open freestall barns that resulted in increased levels of missing data. The study was conducted on 2 dairy farms with an existing commercial real-time location system. Position data were recorded for 6 full days from 69 cows on farm 1 and from 59 cows on farm 2. These data were used in subsequent analyses to determine the locations within the dairy barns where position data were missing for individual cows. The proportions of missing data were found to be evenly distributed within the 2 barns after fitting a linear mixed model with spatial smoothing to logit-transformed proportions (mean = 18% vs. 4% missing data for farm 1 and farm 2, respectively), with the exception of larger proportions of missing data along one of the walls on both farms. On farm 1, the variation between individual tags was large (range: 9–49%) compared with farm 2 (range: 12–38%). This greater individual variation of proportions of missing data indicates a potential problem with the individual tag, such as a battery malfunction or tag placement issue. Further research is needed to guide researchers in identifying problems relating to data capture problems in real-time monitoring systems on dairy farms. This is especially important when undertaking detailed analyses of animal movement and social interactions between animals.
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| 3. |
- Bennet, Patrik, 1995
(författare)
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Characteristics of Vertical Forest Backscatter Profiles Measured using Radar Tomography
- 2023
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Forests are an integral part of the Earth’s climate system, having shaped the conditions of life throughout millions of years, but the coverage and conditions of forests are under rapid change. To monitor this change and predict the impact on climate, yearly global mapping of forest Above-Ground Biomass (AGB) is needed. Synthetic Aperture Radar (SAR) is a well-suited technique for this purpose, able to sense through dense canopies with high spatial resolution. Tomographic SAR (TomoSAR) resolves the vertical distribution of backscatter by constructing 3D tomograms of forested areas. Here, results obtained in the TomoSense project are presented, where sensitivity of P- and L-band TomoSAR to AGB of a temperate forest is analysed. For the first time, differences between the AGB dependence of spruce and beech vertical backscatter profiles are identified. Moreover, unique observations of ground slope influence on TomoSAR AGB retrieval are presented. The effect for P-band is significant, but not for L-band. For spruce, AGB was estimated for P-/L-band (ground slopes below 10◦), with R2 = 0.86/0.75 and RMSE = 15.6/12.5%. Without separating forest types, R2 = 0.77/0.54 and RMSE = 11.4/12.0%. Finally, unique L-band radar tomography observations using the BorealScat tower-based radar are presented. Time series of the vertical backscatter profile of a boreal forest during the summer of 2018 is analysed. Weekly diurnal cycles up to 1.3 dB are observed, showing clear differences depending on both canopy height layer and polarization. These differences are new results which are likely related to tree transpiration phenomena but needs further study.
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| 4. |
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| 5. |
- Iwaki, Takuya, 1986-, et al.
(författare)
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Multi-loop periodic event-triggered actuation : applications to PID, cascade, and decoupling control
- 2022
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Ingår i: International Journal of Control. - : Informa UK Limited. - 0020-7179 .- 1366-5820. ; , s. 1-16
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Tidskriftsartikel (refereegranskat)abstract
- This paper studies periodic event-triggered actuation applied to PID, cascade, and decoupling control. We propose an event-triggered output feedback controller, in which the control command is actuated only when it exceeds its previous value by a certain threshold. An exponential stability condition is derived in the form of LMIs using a Lyapunov–Krasovskii functional based on Wirtinger's inequality. It is shown that an observer-based controller can reject an unknown step disturbance. Using this result, we propose a way to tune the event threshold subject to a given stability margin. We apply the proposed framework to PID, cascade, and decoupling control to illustrate how the event thresholds can be tuned in practice. Numerical examples show for these three control architectures how controller–actuator communication can be reduced without performance degradation.
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| 6. |
- Risman, PO, 1943, et al.
(författare)
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Retro-modelling of a dual resonant applicator and accurate dielectric properties of liquid water from −20 °C to +100 °C
- 2007
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Ingår i: Measurement Science and Technology. - : IOP Publishing. - 0957-0233 .- 1361-6501. ; 18, s. 959-966
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Tidskriftsartikel (refereegranskat)abstract
- A critical analysis is made of literature reports on the dielectric properties of pure water from liquid water supercooled at −20 ◦C, to +100 ◦C, in principle in the frequency range 0 to 3 GHz. Measurements using completemulti-step numerical modelling of a dual resonant cavity at about 920 MHz and 2230 MHz are presented. The measured data at about +20 ◦C are used as reference for the calculation of data at other temperatures. Due to the high resolution and considerations of various error sources, the resultingaccuracy becomes high and allows the construction of improved empiricalformulae for the Debye relaxation behaviour.
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| 7. |
- Ahlman, Linnéa, 1987, et al.
(författare)
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Stress Detection Using Proximal Sensing of Chlorophyll Fluorescence on the Canopy Level
- 2021
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Ingår i: AgriEngineering. - : MDPI AG. - 2624-7402. ; 3:3, s. 648-668
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Tidskriftsartikel (refereegranskat)abstract
- Chlorophyll fluorescence is interesting for phenotyping applications as it is rich in biological information and can be measured remotely and non-destructively. There are several techniques for measuring and analysing this signal. However, the standard methods use rather extreme conditions, e.g., saturating light and dark adaption, which are difficult to accommodate in the field or in a greenhouse and, hence, limit their use for high-throughput phenotyping. In this article, we use a different approach, extracting plant health information from the dynamics of the chlorophyll fluorescence induced by a weak light excitation and no dark adaption, to classify plants as healthy or unhealthy. To evaluate the method, we scanned over a number of species (lettuce, lemon balm, tomato, basil, and strawberries) exposed to either abiotic stress (drought and salt) or biotic stress factors (root infection using Pythium ultimum and leaf infection using Powdery mildew Podosphaera aphanis ). Our conclusions are that, for abiotic stress, the proposed method was very successful, while, for powdery mildew, a method with spatial resolution would be desirable due to the nature of the infection, i.e., point-wise spread. Pythium infection on the roots is not visually detectable in the same way as powdery mildew; however, it affects the whole plant, making the method an interesting option for Pythium detection. However, further research is necessary to determine the limit of infection needed to detect the stress with the proposed method.
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| 8. |
- A. Bateki, Christian, et al.
(författare)
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Of milk and mobiles: Assessing the potential of cellphone applications to reduce cattle milk yield gaps in Africa using a case study
- 2021
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Ingår i: Computers and Electronics in Agriculture. - : Elsevier BV. - 0168-1699. ; 191
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Tidskriftsartikel (refereegranskat)abstract
- There are growing expectations that Information and Communication Technology (ICT) applications could help improve on-farm yields amongst smallholder farmers in developing countries, and consequently, food and nutrition security. However, few studies have quantified the actual contribution of ICT applications on farmers’ yields, and these studies predominantly focused on crop production. We assessed the potential of ICT applications to close milk yield gaps among small- and medium scale dairy cattle farmers in Africa. First, we developed a theoretical framework summarizing biophysical and socio-economic constraints that foster milk yield gaps and discussed which constraints can be addressed using ICT applications. Second, using a case study of a feeding advice application for dairy cattle pre-tested with farmers in rural Kenya, we analyzed how much stand-alone the application could contribute to close dairy cattle milk yield gaps. Our findings suggest that ICT applications could help address some existing biophysical and socio-economic constraints fostering milk yield gaps, including data collection for breeding programs, feeding management advice, and facilitating access to markets and capital. Our stand-alone ICT application closed yield gaps by 2 % to 6 % on representative farms. Several factors may explain the limited actual contribution of selected ICT applications to reduce existing milk yield gaps, including the quality of the input data and models used in ICT applications, and more structural constraints that cannot be addressed by digital tools. Therefore, although ICT applications could help address constraints to achieving higher milk yields on dairy farms, a significant contribution to improve yields may only be achieved when conditions surrounding their use are adequate.
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| 9. |
- Ericson, Marten, et al.
(författare)
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Architecture landscape
- 2023
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Ingår i: Towards Sustainable and Trustworthy 6G: Challenges, Enablers, and Architectural Design. - 9781638282396 ; , s. 11-39
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- The network architecture evolution journey will carry on in the years ahead, driving a large scale adoption of 5th Generation (5G) and 5G-Advanced use cases with significantly decreased deployment and operational costs, and enabling new and innovative use-case-driven solutions towards 6th Generation (6G) with higher economic and societal values. The goal of this chapter, thus, is to present the envisioned societal impact, use cases and the End-to-End (E2E) 6G architecture. The E2E 6G architecture includes summarization of the various technical enablers as well as the system and functional views of the architecture.
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| 10. |
- Ringdahl, Ola, 1971-, et al.
(författare)
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Estimating wheel slip for a forest machine using RTK-DGPS
- 2012
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Ingår i: Journal of terramechanics. - : Elsevier BV. - 0022-4898 .- 1879-1204. ; 49:5, s. 271-279
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Tidskriftsartikel (refereegranskat)abstract
- Wheel slip may increase the risk for wheel rutting and tear up ground vegetation and superficial roots and thereby decreasing the bearing capacity of the ground, but also reducing the growth of nearby standing forest trees. With increased slip, more energy is consumed for making wheel ruts in the ground, with increased fuel consumption as a result. This paper proposes a novel method for measuring slip in an uneven forest terrain with an 8WD forestry machine. This is done by comparing the wheel velocity reported by the machine and velocity measured with an accurate DGPS system. Field tests with a forestry machine showed that slip could be calculated accurately with the suggested method. The tests showed that there was almost no slip on asphalt or gravel surfaces. In a forest environment, 10–15% slip was common. A future extension of the method enabling estimation of the slip of each wheel pair in the bogies is also suggested.
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