Design method for four-reflector type beam waveguide systems

Discussed is a method for the design of four reflector type beam waveguide feed systems, comprised of a conical horn and 4 focused reflectors, which are used widely as the primary reflector systems for communications satellite Earth station antennas. The design parameters for these systems are clarified, the relations between each parameter are brought out based on the beam mode development, and the independent design parameters are specified. The characteristics of these systems, namely spillover loss, crosspolarization components, and frequency characteristics, and their relation to the design parameters, are also shown. It is also indicated that design parameters which decide the dimensions of the conical horn or the shape of the focused reflectors can be unerringly established once the design standard for the system has been selected as either: (1) minimizing the crosspolarization component by keeping the spillover loss to within acceptable limits, or (2) minimizing the spillover loss by maintaining the crossover components below an acceptable level and the independent design parameters, such as the respective sizes of the focused reflectors and the distances between the focussed reflectors, etc., have been established according to mechanical restrictions. A sample design is also shown. In addition to being able to clarify the effects of each of the design parameters on the system and improving insight into these systems, the efficiency of these systems will also be increased with this design method

MAPPING SPATIAL ACCURACY OF FOREST TYPE CLASSIFICATION IN JAXA’s HIGH-RESOLUTION LAND USE AND LAND COVER MAP

Accuracy assessment of forest type maps is essential to evaluate the classification of forest ecosystems quantitatively. However, map users do not understand in which regions those forest types are well classified from conventional static accuracy measures. Hence, the objective of this study is to unveil spatial heterogeneities of accuracies of forest type classification in a map. Four forest types (deciduous broadleaf forest (DBF), deciduous needleleaf forest (DNF), evergreen broadleaf forest (EBF), and evergreen needleleaf forest (ENF)) found in the JAXA’s land use / cover map of Japan were assessed by a volunteered Site-based dataset for Assessment of Changing LAnd cover by JAXA (SACLAJ). A geographically weighted (GW) correspondence matrix was applied to them to calculate the degree of overall agreements of forest type classes (forest overall accuracy), and the degree of accuracy for each forest class (forest user’s and producer’s accuracies) in a spatially varying way. This study compared spatial surfaces of these measures with static ones of them. The results show that the forest overall accuracy of the forest map tends to be relatively more accurate in the central Japan, while less in the Kansai and Chubu regions and the northern edge of Hokkaido. Static forest user’s accuracy measures for DBF, DNF, and ENF are better than forest producer’s accuracy ones, while the GW approach tells us such characteristics vary spatially and some areas have opposite trends. This kind of spatial accuracy assessment provides a more informative description of the accuracy than the simple use of conventional accuracy measures

Spatio-temporal distribution of pyrethroids in soil in Mediterranean paddy fields

[EN] The demand of rice by the increase in population in many countries has intensified the application of pesticides and the use of poor quality water to irrigate fields. The terrestrial environment is one compartment affected by these situations, where soil is working as a reservoir, retaining organic pollutants. Therefore, it is necessary to develop methods to determine insecticides in soil and monitor susceptible areas to be contaminated, applying adequate techniques to remediate them. Materials and methods This study investigates the occurrence of ten pyrethroid insecticides (PYs) and its spatio-temporal variance in soil at two different depths collected in two periods (before plow and during rice production), in a paddy field area located in the Mediterranean coast. Pyrethroids were quantified using gas chromatography mass spectrometry (GC MS) after ultrasound-assisted extraction with ethyl acetate. The results obtained were assessed statistically using non-parametric methods, and significant statistical differences (p&#8201;<&#8201;0.05) in pyrethroids content with soil depth and proximity to wastewater treatment plants were evaluated. Moreover, a geographic information system (GIS) was used to monitor the occurrence of PYs in paddy fields and detect risk areas. Results and discussion Pyrethroids were detected at concentrations &#8804;57.0 ng g&#8722;1 before plow and &#8804;62.3 ng g&#8722;1 during rice production, being resmethrin and cyfluthrin the compounds found at higher concentrations in soil. Pyrethroids were detected mainly at the top soil, and a GIS program was used to depict the obtained results, showing that effluents from wastewater treatment plants (WWTPs) were the main sources of soil contamination. No toxic effects were expected to soil organisms, but it is of concern that PYs may affect aquatic organisms, which represents the worst case scenario. Conclusions A methodology to determine pyrethroids in soil was developed to monitor a paddy field area. The use of water from WWTPs to irrigate rice fields is one of the main pollution sources of pyrethroids. It is a matter of concern that PYs may present toxic effects on aquatic organisms, as they can be desorbed from soil. Phytoremediation may play an important role in this area, reducing the possible risk associated to PYs levels in soil.Authors wish to thank INIA for the predoctoral fellowship (R. Aznar) and Spanish Ministry of Economy and Competitiveness RTA2014-00012-C03-01 for financial support and Jonathan Villanueva Martin for his contribution to this work.Aznar, R.; Moreno-Ramón, H.; Albero, B.; Sánchez Brunete, C.; Tadeo, JL. (2016). Spatio-temporal distribution of pyrethroids in soil in Mediterranean paddy fields. 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Agric Eco Environ 123(4):247–260Aznar R, Albero B, Sanchez-Brunete C, Miguel E, Tadeo JL (2014) Multiresidue analysis of insecticides and other selected environmental contaminants in poultry manure by gas chromatography/mass spectrometry. J AOAC Int 97(4):978–986Campo J, Masia A, Blasco C, Pico Y (2013) Occurrence and removal efficiency of pesticides in sewage treatment plants of four Mediterranean River Basins. J Hazard Mater 263:146–157European Commission (2002) Review report for the active substance Cyfluthrin, 6843/VI/97-finalEuropean Commission (2004) Review report for the active substance α-Cypermethrin, SANCO/4335/2000-finalEuropean Commission (2005) Review report for the active substance Esfenvalerate, 6846/VI/97-finalFeo ML, Ginebreda A, Eljarrat E, Barcelo D (2010) Presence of pyrethroid pesticides in water and sediments of Ebro River Delta. J Hydrol 393(3-4):156–162Fojut TL, Palumbo AJ, Tjeerdema RS (2012) Aquatic life water quality criteria derived via the UC Davis method: II. Pyrethroid insecticides. Rev Environ Contam Toxicol 216:51–103Gan J, Lee SJ, Liu WP, Haver DL, KAbashima JN (2005) Distribution and persistence of pyrethroids in runoff sediments. J Environ Qual 34:836–841Hill IR (1985) Aquatic organisms and pyrethroids. Pestic Sci 27:429–465Huang LM, Thompson A, Zhang GL, Chen LM, Han GZ, Gong ZT (2015) The use of chronosequences in studies of paddy soil evolution: a review. Geoderma 237:199–210Katagi T (2004) Photodegradation of pesticides on plant and soil surfaces. Rev Environ Contam Toxicol 182:1–189Laskowski DA (2002) Physical and chemical properties of pyrethroids. Rev Environ Contam Toxicol 174:49–170Mahabali S, Spagnoghe P (2014) Mitigation of two insecticides by wetlands plants: feasibility study for the treatment of agricultural runoff in Suriname (South America). Water Air Soil Pollut 225:1771Maund SJ, Hamer MJ, Lane MCG, Farrelly E, Rapley JH, Goggin UM, Gentle WE (2002) Partitioning, bioavailability, and toxicity of the pyrethroid insecticide cypermethrin in sediments. Environ Toxicol Chem 21(1):9–15Maund SJ, Campbell PJ, Giddings JM, Hamer MJ, Henry K, Pilling ED, Warinton JS, Wheeler JR (2012) Ecotoxicology of synthetic pyrethroids. Top Curr Chem 314:137–165Money E, Carter GP, Serre ML (2009) Using river distances in the space/time estimation of dissolved oxygen along two impaired river networks in New Jersey. Water Res 43(7):1948–1958Moore MT, Cooper CM, Smith S, Jr Cullum RF, Knight SS, Locke MA, Bennett ER (2009) Mitigation of two pyrethroid insecticides in Mississippi Delta constructed wetland. Environ Pollut 157:250–256Moreno-Ramón H, Marqués-Mateu A, Ibáñez-Asensio S, Gisbert JM (2015) Wetland soils under rice management and seawater intrusion: characterization and classification. 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Shedding light on plant litter decomposition: Advances, implications and new directions in understanding the role of photodegradation

Litter decomposition contributes to one of the largest fluxes of carbon (C) in the terrestrial biosphere and is a primary control on nutrient cycling. The inability of models using climate and litter chemistry to predict decomposition in dry environments has stimulated investigation of non-traditional drivers of decomposition, including photodegradation, the abiotic decomposition of organic matter via exposure to solar radiation. Recent work in this developing field shows that photodegradation may substantially influence terrestrial C fluxes, including abiotic production of carbon dioxide, carbon monoxide and methane, especially in arid and semi-arid regions. Research has also produced contradictory results regarding controls on photodegradation. Here we summarize the state of knowledge about the role of photodegradation in litter decomposition and C cycling and investigate drivers of photodegradation across experiments using a meta-analysis. Overall, increasing litter exposure to solar radiation increased mass loss by 23% with large variation in photodegradation rates among and within ecosystems. This variation was tied to both litter and environmental characteristics. Photodegradation increased with litter C to nitrogen (N) ratio, but not with lignin content, suggesting that we do not yet fully understand the underlying mechanisms. Photodegradation also increased with factors that increased solar radiation exposure (latitude and litter area to mass ratio) and decreased with mean annual precipitation. The impact of photodegradation on C (and potentially N) cycling fundamentally reshapes our thinking of decomposition as a solely biological process and requires that we define the mechanisms driving photodegradation before we can accurately represent photodegradation in global C and N models. © 2012 US Government