Long-Term Soil Structure Observatory for Monitoring Post-Compaction Evolution of Soil Structure

The projected intensification of agriculture to meet food targets of a rapidly growing world population are likely to accentuate already acute problems of soil compaction and deteriorating soil structure in many regions of the world. The key role of soil structure for soil functions, the sensitivity of soil structure to agronomic management practices, and the lack of reliable observations and metrics for soil structure recovery rates after compaction motivated the establishment of a long-term Soil Structure Observatory (SSO) at the Agroscope research institute in Zürich, Switzerland. The primary objective of the SSO is to provide long-term observation data on soil structure evolution after disturbance by compaction, enabling quantification of compaction recovery rates and times. The SSO was designed to provide information on recovery of compacted soil under different post-compaction soil management regimes, including natural recovery of bare and vegetated soil as well as recovery with and without soil tillage. This study focused on the design of the SSO and the characterization of the pre- and post-compaction state of the field. We deployed a monitoring network for continuous observation of soil state variables related to hydrologic and biophysical functions (soil water content, matric potential, temperature, soil air O2 and CO2 concentrations, O2 diffusion rates, and redox states) as well as periodic sampling and in situ measurements of infiltration, mechanical impedance, soil porosity, gas and water transport properties, crop yields, earthworm populations, and plot-scale geophysical measurements. Besides enabling quantification of recovery rates of compacted soil, we expect that data provided by the SSO will help improve our general understanding of soil structure dynamics

Soil compaction: effects on soil hydraulic properties and preferential water flow

Soil compaction caused by passage of agricultural machinery over the surface is an issue in many agricultural soils with a high clay content. Compaction is known to modify soil pore structure and soil hydraulic properties, but can also affect the occurrence of preferential flow. Water flow through preferential flow pathways can facilitate transport of fertilisers, pesticides and contaminants to groundwater, creating harmful environmental problems. In two complementary studies, this thesis examined soil hydraulic properties and preferential water flow on soil cores sampled in the field and quantified flow patterns in situ at two sites approximately 300 m apart in central Sweden. One year after compaction of field plots, X-ray computed tomography (CT) imaging was used to visualise and quantify soil pore structures in soil columns taken from the subsoil (30-50 cm depth). Degree of preferential water flow and transport were derived from non-reactive tracer breakthrough curves. Dye tracing experiments were performed in the field and different soil mechanical and hydraulic properties were measured to help explain the dye patterns. Contrasting effects of wheel traffic were observed at the two neighbouring sites. Thus, even quite small differences in initial soil and site conditions can significantly influence the extent to which applied compaction stresses affect the connectivity of structural pore space in soil and, consequently, water flow patterns. These results contradict previous findings of an increase in preferential flow following soil compaction. This discrepancy in results was analysed with the help of a conceptual model, which suggested that preferential flow is greatest at some intermediate level of compaction at which macropore continuity is still maintained, despite reductions in macroporosity. The model also illustrated how compaction, and subsequent recovery from compaction, might affect susceptibility to preferential flow and surface runoff. To prevent subsoil compaction, it is important to consider soil conditions at the time of trafficking, which can significantly influence the effect of compaction on soil pore connectivity and associated water flow

Theoretical Design of a Single Phase 2kW Power Supply with 1.5kV DC Output

This 15hp degree project in electrical engineering is carried out at ScandiNova Systems AB in Uppsala, Sweden. The company constructs pulse generators used in areas such as sterilization or radiation therapy. As a step in development they want to design their own power supply for one of their generators instead of purchasing it from an external supplier. This paper is about how to make a theoretical design of a power supply that can use worldwide single-phase AC line input and deliver ~1500V DC output. The paper has a power loss and harmonic theory part and a method part for power inductor calculation etc. The result is a power supply seen from the AC line starting with a second order EMI-filter, a full-wave rectifier bridge, a PFC (Power Factor Correction) boost converter based on the controller UCC28180 from Texas Instruments and a SLR (Series Loaded Resonant) half-bridge converter with control and feedback produced by the company itself. Associated energy efficiency calculations, drawing, component lists and physical design compared to the size of the current power supply and components made in SolidWorks is the design output. The conclusion is that the goal parameters are theoretically fulfilled and realistic but that experimental testing is needed for optimizing the design and control. That is why some of the parameters are changeable for best modifiability later in the product design.Detta 15hp examensarbete i elektroteknik har utförts på Scandinova Systems AB i Uppsala, Sverige. Deras verksamhet är att bygga pulsgeneratorer som används i områden som sterilisering eller strålbehandling. Som ett steg i utvecklingen vill de utforma sitt eget nätaggregat till en av sina generatorer istället för att köpa den från en extern leverantör. Denna uppsats handlar om hur man gör en teoretisk konstruktion av ett nätaggregat som kan användas i hela världen med enfas växelström på linjeingången och leverera ~1500V på DC-utgången. Uppsatsen har en teoridel om effektförluster och harmoniska övertoner och en metod del om beräkning av induktor etc. Resultatet är ett nätaggregat sedd från AC linjeingång som börjar med ett andra ordningens EMI-filter, en helvågslikriktare, en PFC (Power Factor Correction) boost omvandlare baserad på styrenheten UCC28180 från Texas Instruments och en SLR (Series Loaded Resonant) halvbrygga med styrning och återkoppling som produceras av företaget självt. Energieffektivitetsberäkningar, ritningar, komponentlistor och fysisk utformning jämfört med storleken på det aktuella nätaggregatet och komponenter tillverkade i SolidWorks är projektets utkomst. Slutsatsen är att målparametrarna teoretiskt är uppfyllda och realistiska, men att experimentell testning behövs för att optimera design och kontroll. Det är därför en del av parametrarna är utbytbara för bästa modifierbarhet senare i produktdesignen

Theoretical Design of a Single Phase 2kW Power Supply with 1.5kV DC Output

This 15hp degree project in electrical engineering is carried out at ScandiNova Systems AB in Uppsala, Sweden. The company constructs pulse generators used in areas such as sterilization or radiation therapy. As a step in development they want to design their own power supply for one of their generators instead of purchasing it from an external supplier. This paper is about how to make a theoretical design of a power supply that can use worldwide single-phase AC line input and deliver ~1500V DC output. The paper has a power loss and harmonic theory part and a method part for power inductor calculation etc. The result is a power supply seen from the AC line starting with a second order EMI-filter, a full-wave rectifier bridge, a PFC (Power Factor Correction) boost converter based on the controller UCC28180 from Texas Instruments and a SLR (Series Loaded Resonant) half-bridge converter with control and feedback produced by the company itself. Associated energy efficiency calculations, drawing, component lists and physical design compared to the size of the current power supply and components made in SolidWorks is the design output. The conclusion is that the goal parameters are theoretically fulfilled and realistic but that experimental testing is needed for optimizing the design and control. That is why some of the parameters are changeable for best modifiability later in the product design.Detta 15hp examensarbete i elektroteknik har utförts på Scandinova Systems AB i Uppsala, Sverige. Deras verksamhet är att bygga pulsgeneratorer som används i områden som sterilisering eller strålbehandling. Som ett steg i utvecklingen vill de utforma sitt eget nätaggregat till en av sina generatorer istället för att köpa den från en extern leverantör. Denna uppsats handlar om hur man gör en teoretisk konstruktion av ett nätaggregat som kan användas i hela världen med enfas växelström på linjeingången och leverera ~1500V på DC-utgången. Uppsatsen har en teoridel om effektförluster och harmoniska övertoner och en metod del om beräkning av induktor etc. Resultatet är ett nätaggregat sedd från AC linjeingång som börjar med ett andra ordningens EMI-filter, en helvågslikriktare, en PFC (Power Factor Correction) boost omvandlare baserad på styrenheten UCC28180 från Texas Instruments och en SLR (Series Loaded Resonant) halvbrygga med styrning och återkoppling som produceras av företaget självt. Energieffektivitetsberäkningar, ritningar, komponentlistor och fysisk utformning jämfört med storleken på det aktuella nätaggregatet och komponenter tillverkade i SolidWorks är projektets utkomst. Slutsatsen är att målparametrarna teoretiskt är uppfyllda och realistiska, men att experimentell testning behövs för att optimera design och kontroll. Det är därför en del av parametrarna är utbytbara för bästa modifierbarhet senare i produktdesignen

Theoretical Design of a Single Phase 2kW Power Supply with 1.5kV DC Output

This 15hp degree project in electrical engineering is carried out at ScandiNova Systems AB in Uppsala, Sweden. The company constructs pulse generators used in areas such as sterilization or radiation therapy. As a step in development they want to design their own power supply for one of their generators instead of purchasing it from an external supplier. This paper is about how to make a theoretical design of a power supply that can use worldwide single-phase AC line input and deliver ~1500V DC output. The paper has a power loss and harmonic theory part and a method part for power inductor calculation etc. The result is a power supply seen from the AC line starting with a second order EMI-filter, a full-wave rectifier bridge, a PFC (Power Factor Correction) boost converter based on the controller UCC28180 from Texas Instruments and a SLR (Series Loaded Resonant) half-bridge converter with control and feedback produced by the company itself. Associated energy efficiency calculations, drawing, component lists and physical design compared to the size of the current power supply and components made in SolidWorks is the design output. The conclusion is that the goal parameters are theoretically fulfilled and realistic but that experimental testing is needed for optimizing the design and control. That is why some of the parameters are changeable for best modifiability later in the product design.Detta 15hp examensarbete i elektroteknik har utförts på Scandinova Systems AB i Uppsala, Sverige. Deras verksamhet är att bygga pulsgeneratorer som används i områden som sterilisering eller strålbehandling. Som ett steg i utvecklingen vill de utforma sitt eget nätaggregat till en av sina generatorer istället för att köpa den från en extern leverantör. Denna uppsats handlar om hur man gör en teoretisk konstruktion av ett nätaggregat som kan användas i hela världen med enfas växelström på linjeingången och leverera ~1500V på DC-utgången. Uppsatsen har en teoridel om effektförluster och harmoniska övertoner och en metod del om beräkning av induktor etc. Resultatet är ett nätaggregat sedd från AC linjeingång som börjar med ett andra ordningens EMI-filter, en helvågslikriktare, en PFC (Power Factor Correction) boost omvandlare baserad på styrenheten UCC28180 från Texas Instruments och en SLR (Series Loaded Resonant) halvbrygga med styrning och återkoppling som produceras av företaget självt. Energieffektivitetsberäkningar, ritningar, komponentlistor och fysisk utformning jämfört med storleken på det aktuella nätaggregatet och komponenter tillverkade i SolidWorks är projektets utkomst. Slutsatsen är att målparametrarna teoretiskt är uppfyllda och realistiska, men att experimentell testning behövs för att optimera design och kontroll. Det är därför en del av parametrarna är utbytbara för bästa modifierbarhet senare i produktdesignen

Natural and anthropogenic compaction in North Germany (Schleswig-Holstein): Verification of harmful subsoil compactions

Many soil types in the federal state of Schleswig-Holstein (North Germany) are naturally compacted in the subsoil due to pedo- or geogenic processes (42% of the area) but, due to anthropogenic impacts, the percentage of subsoil compaction has increased further. To determine the overall subsoil compaction status of seven representative soil types in Schleswig-Holstein (≤ 60 cm depth), air capacity (AC), saturated hydraulic conductivity (Ks) and effective bulk density (ρBeff) of 342 soil profiles from the database of the State Agency for Agriculture, Environment and Rural Areas of Schleswig-Holstein (LLUR) were evaluated with respect to critical threshold values (AC  1.7 g cm−3). The compaction status was classified into Classes I–IV, where a harmful subsoil compaction was assumed if both values of AC and Ks simultaneously exceeded (are smaller than) their threshold value (Class IV). Subsoils of (Stagnic) Luvisols and Stagnosols derived from glacial till, as well as those of Fluvic Gleyic Stagnosols of the marshlands, showed a high degree of natural compaction (46%–65% in Class IV). In contrast, sandy subsoil horizons of Podzols and Brunic Arenosols derived from glacifluvial sediments were rarely compacted (< 13% in Class IV), and possessed the lowest ρBeff, which were similar to Anthrosols. Only 5%–18% of their subsoil horizons exceeded the critical value of 1.7 g cm−3. Additionally, anthropogenic subsoil compaction of at least 6%–10% was verified for (Stagnic) Luvisols and Stagnosols