Reduced copper treatments in strawberries by cultural methods

Effect of cultural methods on leaf spot (Mycosphaerella fragariae Tul.) and yield in strawberries. The possibilities of reduction of copper input in organic strawberry crops is explored

Interest Rate Policy and Supply-side Adjustment Dynamics

In contrast to the present consensus view of stabilization policy, theoretical and empirical research strongly support the consideration of supply-side adjustment to pronounced variations of factor-utilization in order to trace a more realistic pattern of macroeconomic adjustment dynamics within simulation studies. Against this background, our paper seeks to illuminate the relevance of endogenous supply-side adjustment for monetary policy research. We modify a basic New Keynesian model by explicitly considering demand-side stimulus on the evolution of productive capacity and analyze stability, impulse response, and welfare issues if the central bank follows a simple monetary policy rule. Thereby, we control for the robustness of our policy implications by various states of output gap mismeasurement the central bank might be confronted with. We find that, in contrast to a basic New Keynesian Model, output gap stabilization plays a more prominent role when potential output is endogenous.monetary policy, factor-utilization, endogenous potential output, output gap mismeasurement

Measurement of the earthshine polarization in the B, V, R, and I band as function of phase

The characterization of the polarimetric properties of the planet Earth is important for the interpretation of expected observations and the planning of future instruments. We present a multi-wavelengths and multi-phase set of benchmark values for the polarization signal of the integrated light from the planet Earth derived from new polarimetric observations of the earthshine back-scattered from the Moon's dark side. Using a new, specially designed wide field polarimeter we measured the fractional polarization of the earthshine in the B, V, R and I filters for Earth phase angles alpha between 30{\deg} and 110{\deg}. The phase dependence of the earthshine polarization is fitted by a function p x sin(alpha)^2. To determine the polarization of the planet Earth we correct our earthshine measurements by a polarization efficiency function for the lunar surface derived from measurements of lunar samples from the literature. The polarization of the earthshine decreases towards longer wavelengths and is about a factor 1.3 lower for the higher albedo highlands. For mare regions the measured maximum polarization is about 13 % at quadrature in the B band. The resulting fractional polarizations for Earth are 24.6 % for the B band, 19.1 % for the V band, 13.5 % for the R band, and 8.3 % for the I band. Together with literature values for the spectral reflectivity of Earth we obtain a contrast between the polarized flux of the Earth and the (total) flux of the Sun with an uncertainty of less than 20 % and we find that the best phase to detect an Earth twin is around an Earth phase alpha=65{\deg}. The polarimetric models of Earth-like planets from Stam (2008) are in qualitative agreement with our results but there are also significant differences which might guide more detailed computations.Comment: 14 pages, 14 figures, accepted for publication in Astronomy & Astrophysic

Laboratory Studies on Aqueous Absorption and High Temperature Chemistry of NOx and SOx in Thermal Conversion of Biomass Waste

In order to fulfill the transition to a climate neutral economy and society, various renewable energy sources are needed to replace fossil fuels. Thermal conversion of biomass waste streams plays an important role in this transition. From a circular economy point of view, thermal conversion of valuable biomass materials, e.g. wood, is undesired. However, biomass waste streams, e.g. from agriculture and forest industry, which cannot be recycled or re-used can be valorized by recovering energy and valuable elements via thermal conversion. Thermal conversion of biomass waste is connected to various challenges due to their chemical and physical nature. Nitrogen and alkali metals are common components in biomass waste. In thermal conversion, nitrogen partly forms NOx emissions, which are harmful to the environment. Hence, NOx needs to be removed from the flue gases. The alkali in the biomass can cause deposit formation and corrosion on metal surfaces. In order to minimize high-temperature corrosion, biomass-fired boilers use lower steam temperatures as compared to e.g. coal fired boilers, which reduces the electrical efficiency of biomass-fired boilers. To reduce corrosion issues, corrosive alkali compounds such as alkali chlorides or hydroxides need to be captured in less corrosive forms, e.g. alkali sulfates. The present work focuses on various aspects of the nitrogen and sulfur chemistry in thermal conversion processes using biomass waste streams. The formation of NOx and NOx precursors was studied for the thermal conversion of pre-treated bark and straw. The sulfation of sodium salts with SO₂ has been investigated in post-flame conditions. Regarding NOx removal from flue gases, NO₂ absorption in aqueous solutions with sulfite and thiosulfate has been studied. Combustion and devolatilization experiments for the investigation of NOx emissions were performed in a single particle reactor consisting of an electrically heated quartz tube reactor. Single biomass particles were combusted (3% O₂/rest N₂) or devolatilized (100% N₂) in the reactor. Pre-treated bark samples had a lower fuel-N to NO conversion as compared to the raw bark, while pre-treated straw samples had higher fuel-N to NO conversions. During the char conversion, washed samples had the highest conversion for both straw and bark. This was explained by the catalytic effect of ash forming elements in reducing NO emissions during char conversion. The ash forming elements also influenced the NOx precursor formation during devolatilization. Samples with higher calcium contents showed higher NH₃ formation tendencies during devolatilization. The split between NH₃ and HCN also seems to be affected by the fuel-N and fuel-H content. Sodium sulfation experiments were performed in a multi-jet burner, which provided well-controlled post-flame conditions at 850 to 1475 °C. NaOH(g) or NaCl(g) and SO₂ were fed separately to the combustion environment were the sulfation reactions took place. The sodium salts were fed with a resulting gas phase concentration of 20 ppm, and SO₂ with 0–150 ppm. The concentrations of NaOH(g) and NaCl(g) were quantified using broadband UV absorption spectroscopy to follow the degree of sulfation. At temperatures above 1275 °C, almost no sulfation of NaOH(g) was observed, while most of the NaOH(g) was sulfated at 985 °C and below. The sulfation of NaCl(g) occurred to a much lower extent as compared at NaOH(g). At 850 °C, around half of the NaCl(g) was sulfated with 150 ppm SO₂. Chemical equilibrium calculations and kinetic modeling results were compared to the experimental results. At the highest investigated temperatures, the system could be described by chemical equilibrium. At 1115 °C and below, the measured concentrations were in good agreement with the kinetic model for NaOH(g). In the case of NaCl(g), the kinetic model over-predicted the degree of sulfation. The combined experimental data, chemical equilibrium calculations and kinetic modeling support that sulfation of alkali species can occur in the gas phase through homogenous reactions. NO₂ absorption tests were performed by bubbling test gases with various NO₂ concentrations with and without air through aqueous solutions containing sulfur containing additives. Without the additives, NO₂ was absorbed at low rates in water, i.e. 15% with 50 ppm NO₂ inlet concentration. When sulfite was present in the solution, NO₂ reacted with the sulfite to nitrite at increasingly higher rates. With 1 mM sulfite, the absorption rate increased by 200% as compared to water and by 500% with 10 mM at pH 8. The pH was shown to have a great impact on the performance of the sulfite additive due to the sulfite-bisulfite equilibrium. The absorption efficiency decreased with decreasing pH. Another factor that had a significant influence on the absorption efficiency was the presence of oxygen in the incoming gas. Without oxygen present, sulfite was consumed at a rate proportional to the NO₂ absorption, as sulfite only reacted with NO₂. In the presence of oxygen, however, sulfite was consumed at much higher rates due to radical chain reactions oxidizing sulfite to sulfate. While the sulfite oxidation rate was independent on the oxygen concentration for the investigated conditions (2–10% O₂), the rate increased linearly with the sulfite concentration in the absorption solution. The addition of thiosulfate to the sulfite solution has been shown to effectively reduce the sulfite oxidation, as thiosulfate acts as a radical scavenger. For a 10 mM sulfite solution, the sulfite oxidation rate decreased by 75% with 1 mM thiosulfate.För att genomföra omställningen till en klimatneutral ekonomi behövs bättre förståelse för olika typers förnybara energi. Termisk omvandling av biomassaavfallsströmmar spelar en viktig roll i denna omställning. Sett från en cirkulärekonomis synvinkel är termisk omvandling av värdefulla biomassamaterial såsom trä icke-önskvärt. Däremot kan biomassaavfallsströmmas bättre utnyttjas, t.ex. avfall från jordbruk och skogsindustri som inte kan återanvändas, genom att återvinna energi och värdefulla element via termisk omvandling. Termisk omvandling av biomassa har flera utmaningar på grund av deras kemiska och fysiska egenskaper. Kväve och alkalimetaller är vanliga komponenter i biomassa. Kväve i biomassan leder vid termisk omvandling till utsläpp av kväveoxider, som är skadligt för miljön. Därför måste kväveoxider avlägsnas från rökgaserna. Alkalimetaller i biomassan kan orsaka avlagringar och korrosion på metallytor. Biomassaeldade pannor använder lägre ångtemperaturer jämfört med t.ex. koleldade pannor för att minska på högtemperaturkorrosion, vilket också leder till en lägre verkningsgrad hos biomassaeldade pannor. För att minska korrosionsproblem måste korrosiva alkalikomponenter såsom alkaliklorider eller -hydroxider omvandlas till mindre korrosiva komponenter, såsom alkalisulfater. Detta arbete fokuserar på olika aspekter av kväve- och svavelkemi relaterad till termisk omvandling av biomassaavfallsströmmar. Denna avhandling har studerat omvandlingen av bränslekväve till kväveoxider och mellanprodukter som leder till bildning av kväveoxider för termisk omvandling av förbehandlad bark och halm. Avhandlingen har även undersökt sulfateringen av natriumsalter med SO₂ i en förbränningsmiljö. För avlägsnande av kväveoxider från rökgaser studerades NO₂-absorption i vattenlösningar med sulfit och tiosulfat. Förbrännings- och termiska degraderingsexperiment för att undersöka utsläppet av kväveoxider utfördes i en elektriskt uppvärmd en-partikelreaktor gjord av kvartsglas. Biomassapartiklar förbrändes (3% O₂/rest N₂) eller pyrolyserades (100% N₂) i reaktorn. Förbehandlade bark gav upphov till en lägre omvandling av bränsle-N till NO jämfört med obehandlad bark, medan förbehandlad halm gav upphov till en högre omvandling av bränsle-N till NO. Under koksförbränning uppgav tvättat bränsle den högsta omvandlingen av N till NO för både halm och bark. Detta förklarades av den katalytiska effekten av askabildande element vilken ger upphov till att NO-utsläppen minskar under koksförbränningen. De askbildande elementen påverkar också bildandet av kvävehaltiga mellanprodukter under pyrolysen. Prover med högre kalciumhalter uppvisade högre tendens att bilda NH₃ under pyrolysskedet. Fördelningen mellan NH₃ och HCN påverkades också av halterna av N och H i bränslet. Natriumsulfateringsexperimenten utfördes i en förbränningsreaktor vid välkontrollerade förhållanden vid temperaturer mellan 850 och1475 °C. NaOH(g) eller NaCl(g) och SO2 matades separat till förbränningsmiljön där sulfateringsreaktionerna ägde rum. Ingångskoncentrationerna för natriumsalterna var 20 ppm och 0-150 ppm för SO₂. K NaOH(g) och NaCl(g)-koncentrationerna kvantifierades med hjälp av bredbands UV-absorptionsspektroskopi för att följa sulfateringen. Vid temperaturer över 1275 °C observerades nästan ingen sulfatering av NaOH(g), medan det mesta av NaOH(g) sulfaterades vid temperaturer lägre än 985 °C. Sulfateringen av NaCl(g) skedde i lägre utsträckning jämfört med NaOH(g). Vid 850°C sulfaterades ungefär hälften av all NaCl(g) med 150 ppm SO₂. Kemiska jämviktsberäkningar och kinetiska modelleringsresultat jämfördes med de experimentella resultaten. Vid de högsta undersökta temperaturerna kunde systemet beskrivas väl med kemisk jämvikt. Vid temperaturer lägre än 1115 °C var de uppmätta koncentrationerna i god överensstämmelse med den kinetiska modellen för NaOH(g). I fallet med NaCl(g) förutspådde den kinetiska modellen högre grad av sulfatering än vad som observerades i experimenten. En kombination av experimentella data, kemiska jämviktsberäkningar och kinetisk modellering stödjer att sulfatering av alkalisalter sker i gasfasen genom homogena reaktioner. NO2-absorptionstest utfördes genom att bubbla testgaser med olika NO2-koncentrationer med och utan syre genom vattenlösningar innehållande svavelhaltiga tillsatser. Utan tillsatserna absorberades 15% av inkommande NO2 i vatten. Med tillsatt sulfit i lösningen reagerade NO2 med sulfiten till nitrit. Med tillsats av 1 mM sulfit ökade absorptionshastigheten med 200 % jämfört med vatten och med 10 mM ökade hastigheten med 500 % vid pH 8. Absorptionslösningens pH visade sig ha en stor inverkan på prestandan hos sulfittillsatsen vilket kunde förklaras med sulfit-bisulfit-jämviktstillståndet. Absorptionseffektiviteten minskade med sjunkande pH. En annan faktor som hade en betydande inverkan på absorptionseffektiviteten var ifall testgasen innehöll syre. I frånvaro av syre förbrukades sulfit proportionellt mot mängden absorberad NO2 eftersom sulfit reagerade med NO2. I närvaro av syre förbrukades sulfit däremot snabbare på grund av radikala kedjereaktioner som bidrog till att sulfit oxiderades till sulfat. Medan sulfitoxidationshastigheten var oberoende av syrekoncentrationen för de undersökta förhållandena (2, 5 och 10 % O₂), ökade oxidationshastigheten linjärt med sulfitkoncentrationen i absorptionslösningen. Tillsatsen av tiosulfat till sulfitlösningen har visat sig effektivt reducera sulfitoxidationen, eftersom tiosulfat fungerar som en radikalfångare. För en 10 mM sulfitlösning med 1 mM tiosulfat minskade sulfitoxidationshastigheten med 75 %

Broadband THz study of excitonic resonances in the high-density regime

We report the first terahertz study of the intra-excitonic 1s-2p transition at high excitation densities in GaAs/AlGaAs quantum wells. A strong shift, broadening, and ultimately the disappearance of this resonance occurs with increasing density, after ultrafast photoexcitation at the near-infrared exciton line. Densities of excitons and unbound electron-hole pairs are followed quantitatively using a model of the composite terahertz dielectric response. Comparison with near-infrared absorption changes reveals a significantly enhanced energy shift and broadening of the intra-excitonic resonance.Comment: 4 pages, 4 figure

Augmented reality and GIS: On the possibilities and limits of markerless AR

Ponencias, comunicaciones y pósters presentados en el 17th AGILE Conference on Geographic Information Science "Connecting a Digital Europe through Location and Place", celebrado en la Universitat Jaume I del 3 al 6 de junio de 2014.The application of Augmented Reality (AR) in the geo-spatial domain offers huge potentials: AR can visualize invisible properties of spatial entities, can display historic data for them, or can help in finding places. Whatever the application is, AR in the geo-spatial domain will often be purely sensor based, thus without the help of visual or sensory markers. In this paper we analyse the achievable accuracy of AR projections under everyday conditions with consumer hardware. We can show that AR can be applied in applications in smaller geographic scale, but is not sufficient if it comes to the preciseness required when inspecting infrastructural data of small scale