1,174 research outputs found
Practical Accuracy Limits of Radiation-Aware Magneto-Inductive 3D Localization
The key motivation for the low-frequency magnetic localization approach is
that magnetic near-fields are well predictable by a free-space model, which
should enable accurate localization. Yet, limited accuracy has been reported
for practical systems and it is unclear whether the inaccuracies are caused by
field distortion due to nearby conductors, unconsidered radiative propagation,
or measurement noise. Hence, we investigate the practical performance limits by
means of a calibrated magnetoinductive system which localizes an active
single-coil agent with arbitrary orientation, using 4 mW transmit power at 500
kHz. The system uses eight single-coil anchors around a 3m x 3m area in an
office room. We base the location estimation on a complex baseband model which
comprises both reactive and radiative propagation. The link coefficients, which
serve as input data for location estimation, are measured with a multiport
network analyzer while the agent is moved with a positioner device. This
establishes a reliable ground truth for calibration and evaluation. The system
achieves a median position error of 3.2 cm and a 90th percentile of 8.3 cm.
After investigating the model error we conjecture that field distortion due to
conducting building structures is the main cause of the performance bottleneck.
The results are complemented with predictions on the achievable accuracy in
more suitable circumstances using the Cram\'er-Rao lower bound.Comment: To appear at the IEEE ICC 2019 Workshops. This work has been
submitted to the IEEE for possible publication. Copyright may be transferred
without notice, after which this version may no longer be accessibl
ORGANIC AGRICULTURE AND FOOD SECURITY
Modelling the impacts of organic production up-scaled to regional and global levels gives an initial quan-tification of the potential extent of changes that large-scale conversion might induce. Optimistic estimates of change with respect to organic yield potential lead to modest impacts on global commodity prices, production, and trade. Conversion in high-input regions in Europe and North America to certified organic decreases production and increases commodity prices. Hunger in this scenario slightly worsens. Transition of low-input areas in Sub-Saharan Africa to non-certified organic leads to in-creased production and decreased prices. Food secu-rity improves slightly in this scenario. The switch for low-input regions helps decrease trade dependency in some commodities. Achievement of productivity levels in these scenarios is dependent on many factors that introduce a significant amount of uncertainty in the results. The extent of these impacts can be improved if concerted effort in research and development for yield and productivity enhancement is supported
Dimerelloid rhynchonellide brachiopods in the Lower Jurassic of the Engadine (Canton Graubünden, National Park, Switzerland)
New brachiopods (Dimerelloidea, Rhynchonellida) from Lower Jurassic (?lower Hettangian) hemipelagic sediments of the Swiss National Park in south-eastern Engadine are described: Sulcirostra doesseggeri sp. nov. and Carapezzia engadinensis sp. nov. Sulcirostra doesseggeri is externally similar to S. fuggeri (Frauscher 1883), a dubious species, that could not be included in a comparative study, because relevant samples no longer exist. A single specimen was tentatively assigned to Sulcirostra ?zitteli (Böse 1894) by comparison of its external morphology with S. zitteli from the type locality. The partly silicified brachiopods are associated with sponge spicules, radiolarians and crinoid ossicles. Macrofossils are rare: dictyid sponges, gastropods, bivalves, crustaceans, shark teeth and scales of an actinopterygian fish. The Lower Jurassic sediments (Alpisella beds, a basal member of the Allgäu Formation) preserving the brachiopods belong to the Ortler nappe (Upper Austroalpine nappes). The exact age of the Alpisella beds is not known, as index fossils are lacking. Their stratigraphic position above the Rhaetian Kössen Formation and below the ammonite-dated Trupchun beds suggests a very Early Jurassic, probably early Hettangian age for the new brachiopod fauna. The new species of Sulcirostra and Carapezzia are confined to a very small geographic area, a peculiarity also observed in other Early Jurassic dimerelloid brachiopods. These brachiopods presumably adapted to current-dominated submarine highs, where their shells could not accumulate, except when trapped in submarine cavities or re-deposited in submarine fans. Transport by turbidity currents is suggested for the Early Jurassic dimerelloids from the Engadine. Problems with the generic definition of Sulcirostra and the higher rank classification of Carapezzia are discusse
Buckhorn Plantain
Buckhorn plantain (Plantago lanceotata) is a weed with increasing significance in Wasatch County. It is invading alfalfa fields and pastures in the Wallsburg and Heber valleys. Other names for buckhorn plantain are narrow-leaf plantain, ribwart plantain, English plantain, and ribgrass. Plantain is a problem because it reduces the health of the plants that remain by crowding out desirable plant species and using up soil nutrients, water, and light
Integrated economic modeling of global and regional micronutrient security:
In this paper, we examine the implications of alternative country-specific scenarios for biofortification on the reduction of micronutrient deficiency prevalence in under-fives. The scenarios are implemented within a long-term projections model of agriculture production and consumption, given the timeframe needed to develop and implement biofortification of crops and the need to account for changing diets over time. The effectiveness of the various biofortification strategies is largely determined by the evolution of regional dietary patterns over time, which show continued reliance on staple food crops among the poor. It suggests that cereal grain-focused biofortification is likely to be most effective in South Asia, while targeting roots and tubers is most effective in Sub-Saharan Africa.Biofortification, Micronutrients, Economic models,
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