Exploiting Orientation Information to Improve Range-Based Localization Accuracy

Funding Information: This work supported in part by the Fundação para a Ciência e a Tecnologia under Project IF/00325/2015, Project foRESTER PCIF/SSI/0102/2017, and Project UIDB/04111/2020, and in part by the Universidade Lusófona/ILIND internal project TESLA.This work addresses target localization problem in precarious surroundings where possibly no links are line of sight. It exploits the known architecture of available reference points to act as an irregular antenna array in order to estimate the azimuth angle between a reference point and a target, based on distance estimates withdrawn from integrated received signal strength (RSS) and time of arrival (TOA) observations. These fictitious azimuth angle observations are then used to linearize the measurement models, which triggers effortless derivation of a new estimator in a closed-form. It is shown here that, by using fixed network geometry in which target orientation with respect to a line formed by a pair of anchors can be correctly estimated, the localization performance can be significantly enhanced. The new approach is validated through computer simulations, which corroborate our intuition of profiting from inherent information within a network.publishersversionpublishe

Comparing charge transfer tuning effects by chemical substitution and uniaxial pressure in the organic charge transfer complex tetramethoxypyrene-tetracyanoquinodimethane

In the search for novel organic charge transfer salts with variable charge transfer degree we study the effects of two modifications to the recently synthesized donor-acceptor Tetramethoxypyrene (TMP)-Tetracyanoquinodimethane (TCNQ). One is of chemical nature by substituting the acceptor TCNQ molecules by F4TCNQ molecules. The second consists in simulating the application of uniaxial pressure along the stacking axis of the system. In order to test the chemical substitution, we have grown single crystals of TMP-F4TCNQ and analyzed its electronic structure via electronic transport measurements, ab initio density functional theory (DFT) calculations and UV/VIS/IR absorption spectroscopy. This system shows an almost ideal geometrical overlap of nearly planar molecules alternately stacked (mixed stack) and this arrangement is echoed by a semiconductor-like transport behavior with an increased conductivity along the stacking direction. This is in contrast to TMP-TCNQ which shows a less pronounced anisotropy and a smaller conductivity response. Our bandstructure calculations confirm the one-dimensional behavior of TMP-F4TCNQ with pro- nounced dispersion only along the stacking axis. Infrared measurements illustrating the CN vibration frequency shift in F4TCNQ suggest however no improvement on the degree of charge transfer in TMP-F4TCNQ with respect to TMP-TCNQ. In both complexes about 0.1 is transferred from TMP to the acceptor. Concerning the pressure effect, our DFT calculations on designed TMP-TCNQ and TMP-F4TCNQ structures under different pressure conditions show that application of uniaxial pressure along the stacking axis of TMP-TCNQ may be the route to follow in order to obtain a much more pronounced charge transfer

Primena grafičkih simbola u pejsažnoj arhitekturi

The drawing problem of landscape spaces caused by unsatisfactory developed graphic symbols in all fields, particularly in horticulture field, was emphasized in this paper. The graphic symbols solutions from some fields defined by YUS standards and other aren’t defined by standards, which are used in professional literature, were analyzed. The features, which graphic symbols should fulfill for landscape spaces drawing needs, were defined. Some graphic symbol solutions for landscape spaces drawing were proposed because they are not enough defined by national as well as international standards neither they are used in professional literature in the standardized forms. The proposed graphic symbols refer to the horticulture plants and other elements of landscape spaces. The proposed graphic symbols have simple form easy for drawing and in enough extent associates on drawing object. They can use for drawing project documentation, for marketing and commercial drawings and other drawings for wide circle users.U radu je istaknut problem crtanja pejsažnih prostora zbog nedovoljno razvijenih grafičkih simbola iz svih oblasti, a naročito iz oblasti hortikulture. Analizirana su rešenja grafičkih simbola iz nekih oblasti koja su definisana našim standardima i ona koja nisu standardima određena, a koriste se u stručnoj literaturi. Definisane su karakteristike koje treba da imaju grafički simboli za potrebe crtanja pejsažnih prostora. U radu su predložena neka rešenja grafičkih simbola za crtanje pejsažnih prostora, obzirom da našim nacionalnim kao ni međunarodnim standardima nisu u dovoljnoj meri definisani, niti se u stručnoj literaturi koriste ujednačeni oblici. Predloženi grafički simboli se odnose na hortikulturne biljke i druge elemente pejsažnih prostora. Predložena rešenja grafičkih simbola su jednostavnih oblika lakih za crtanje, a u dovoljnoj meri asociraju na predmet crtanja. Mogu se koristiti za crtanje projektne dokumentacije, za markentiške i komercijalne crteže i druge crteže za širi krug korisnika

Dramatic Changes in the Electronic Structure Upon Transition to the Collapsed Tetragonal Phase in CaFe2As2

We use angle-resolved photoemission spectroscopy (ARPES) and density functional theory (DFT) calculations to study the electronic structure of CaFe$_2$As$_2$ in previously unexplored collapsed tetragonal (CT) phase. This unusual phase of the iron arsenic high temperature superconductors was hard to measure as it exists only under pressure. By inducing internal strain, via the post growth, thermal treatment of the single crystals, we were able to stabilize the CT phase at ambient-pressure. We find significant differences in the Fermi surface topology and band dispersion data from the more common orthorhombic-antiferromagnetic or tetragonal-paramagnetic phases, consistent with electronic structure calculations. The top of the hole bands sinks below the Fermi level, which destroys the nesting present in parent phases. The absence of nesting in this phase along with apparent loss of Fe magnetic moment, are now clearly experimentally correlated with the lack of superconductivity in this phase.Comment: 5 pages, 4 figures, accepted in PRB(RC

PHYSICAL AND CHEMICAL PROPERTIES OF SOIL IN FRUIT GROWING AREA TOPOLA (SERBIA)

The aim of the investigation was to assess the level of soil fertility and repair measures in order to enhance the productivity of fruit production in a traditional fruit growing area. (Municipality of Topola, Serbia). The following tests were performed: mechanical composition, physical and chemical properties of soil, total adsorbed base cation, capacity of adsorbed base cation, degree of base saturation, different types of soil acidity, contents of carbon, humus, total nitrogen, easily accessible forms of P2O5 and K2O. Results obtained have shown that soils from all studied sites are of “heavy” mechanical texture with 75,40-84,90% of physical clay. High capacity of cation adsorption, low to medium hydrolytic acidity and high to almost complete saturation of adsorbed bases, has been measured. In compliance with previous analyses, it has been assessed that soils are neutral and of low acid chemical reaction, with low carbon and medium humus content and total nitrogen. Easily accessible content of P2O5 and K2O varies depending on the food quantity on individual parcels with low to medium accessibility to parcels with no fruit plantations. Based on the parameters analysed, the tested soils demand repair of mechanical properties, which will facilitate greater nutrient uptake