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Review of Unbiased FIR Filters, Smoothers, and Predictors for Polynomial Signals
Extracting an estimate of a slowly varying signal corrupted by noise is a common task. Examples can be found in industrial, scientific and biomedical instrumentation. Depending on the nature of the application the signal estimate is allowed to be a delayed estimate of the original signal or, in the other extreme, no delay is tolerated. These cases are commonly referred to as filtering, prediction, and smoothing depending on the amount of advance or lag between the input data set and the output data set. In this review paper we provide a comprehensive set of design and analysis tools for designing unbiased FIR filters, predictors, and smoothers for slowly varying signals, i.e. signals that can be modeled by low order polynomials. Explicit expressions of parameters needed in practical implementations are given. Real life examples are provided including cases where the method is extended to signals that are piecewise slowly varying. A critical view on recursive implementations of the algorithms is provided
CONSERVATION AGRICULTURE ON UKRAINIAN CHERNOZEMS
As the granary of Europe, Ukraine has seen a significant rise in productivity and efficiency of its agriculture during the past decades. Chernozems are the primary soils in Ukraine. In order to maintain continued increases in grain production, Ukraine needs to implement conservation tillage and other sustainable land management practices to reduce soil degradation. The paper reviews the problem of Chernozems degradation and summarizes the influences of conservation tillage, cropping systems, fertilization, crop residue management, strip-cropping and contour farming on physical, chemical, and biological properties of Ukrainian Chernozems for the past 50 years. The conversion from plow-tillage to minimum tillage and no-till improves infiltration rate, pH and soil organic matter (SOM) in 0- to 10-cm layer and lead to carbon accumulation in fulvic acids and humins. No significant differences in SOM storage were observed among tillage systems in the 0- to 100-cm layer. The five crop rotation increased 0.8, 0.71, 0.94 t ha-1 yield of cereals and 5.8, 1.0, 4.2 t ha-1 sugar beet under conventional tillage, deep minimum tillage and reduced minimum tillage, respectively. Recommended application of manure in conservation agriculture in the humid zone - 12 t ha-1, in semi-humid zone - 10-12 t ha-1 and 8-10 t ha-1 in semi-arid zone. Green manure, cover crops and inter crops increased crop yield by 2-10% on Forest-Steppe and Steppe Chernozems. The combination of strip cropping, contour farming, contour bunds, and terracing are particularly recommended for the sloping farmland in order to reduce soil erosion. Land-related policies and relevant legislation in Ukraine are also outlined with an aim to contribute to the creation of guidelines and strategies for further implementation of appropriate practices for sustainable agriculture
Feedback algorithm for switch location : analysis of complexity and application to network design
An accelerated feedback algorithm to solve the single-facility minisum problem is studied with application to designing networks with the star topology. The algorithm, in which the acceleration with respect to the Weiszfeld procedure is achieved by multiplying the current Weiszfeld iterate by an accelerating feedback factor, is shown to converge faster than the accelerating procedures available in the literature. Singularities encountered in the algorithm are discussed in detail. A simple practical exception handling subroutine is developed. Several applications of the algorithm to designing computer networks with the star topology are demonstrated. Applications of the algorithm as a subroutine for multi-switch location problems are considered. Various engineering aspects involved in acquiring and processing coordinates for geographic locations are discussed. A complete algorithm in pseudocode along with the source code listing in Mathematica 4.1 is presented
Structurally-driven magnetic state transition of biatomic Fe chains on Ir(001)
Using first-principles calculations, we demonstrate that the magnetic
exchange interaction and the magnetocrystalline anisotropy of biatomic Fe
chains grown in the trenches of the 5x1 reconstructed Ir(001) surface depend
sensitively on the atomic arrangement of the Fe atoms. Two structural
configurations have been considered which are suggested from recent
experiments. They differ by the local symmetry and the spacing between the two
strands of the biatomic Fe chain. Since both configurations are very close in
total energy they may coexist in experiment. We have investigated collinear
ferro- and antiferromagnetic solutions as well as a collinear state with two
moments in one direction and one in the opposite direction (up-down-up-state).
For the structure with a small interchain spacing, there is a strong exchange
interaction between the strands and the ferromagnetic state is energetically
favorable. In the structure with larger spacing, the two strands are
magnetically nearly decoupled and exhibit antiferromagnetic order along the
chain. In both cases, due to hybridization with the Ir substrate the exchange
interaction along the chain axis is relatively small compared to freestanding
biatomic iron chains. The easy magnetization axis of the Fe chains also
switches with the structural configuration and is out-of-plane for the
ferromagnetic chains with small spacing and along the chain axis for the
antiferromagnetic chains with large spacing between the two strands. Calculated
scanning tunneling microscopy images and spectra suggest the possibility to
experimentally distinguish between the two structural and magnetic
configurations.Comment: Accepted for publication in Physical Review
Hierarchical ordering of reticular networks
The structure of hierarchical networks in biological and physical systems has
long been characterized using the Horton-Strahler ordering scheme. The scheme
assigns an integer order to each edge in the network based on the topology of
branching such that the order increases from distal parts of the network (e.g.,
mountain streams or capillaries) to the "root" of the network (e.g., the river
outlet or the aorta). However, Horton-Strahler ordering cannot be applied to
networks with loops because they they create a contradiction in the edge
ordering in terms of which edge precedes another in the hierarchy. Here, we
present a generalization of the Horton-Strahler order to weighted planar
reticular networks, where weights are assumed to correlate with the importance
of network edges, e.g., weights estimated from edge widths may correlate to
flow capacity. Our method assigns hierarchical levels not only to edges of the
network, but also to its loops, and classifies the edges into reticular edges,
which are responsible for loop formation, and tree edges. In addition, we
perform a detailed and rigorous theoretical analysis of the sensitivity of the
hierarchical levels to weight perturbations. We discuss applications of this
generalized Horton-Strahler ordering to the study of leaf venation and other
biological networks.Comment: 9 pages, 5 figures, During preparation of this manuscript the authors
became aware of a related work by Katifori and Magnasco, concurrently
submitted for publicatio
Indications of superconductivity in doped highly oriented pyrolytic graphite
We have observed possible superconductivity using standard resistance vs.
temperature techniques in phosphorous ion implanted Highly Oriented Pyrolytic
Graphite. The onset appears to be above 100 K and quenching by an applied
magnetic field has been observed. The four initial boron implanted samples
showed no signs of becoming superconductive whereas all four initial and eight
subsequent samples that were implanted with phosphorous showed at least some
sign of the existence of small amounts of the possibly superconducting phases.
The observed onset temperature is dependent on both the number of electron
donors present and the amount of damage done to the graphene sub-layers in the
Highly Oriented Pyrolytic Graphite samples. As a result the data appears to
suggest that the potential for far higher onset temperatures in un-damaged
doped graphite exists.Comment: 7 pages, 1 table, 5 figures, 11 references, Acknowledgments section
was correcte
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