50 research outputs found
Ultra Wideband Indoor Navigation System
Typical indoor environments contain multiple walls and obstacles consisting of different materials. As a result, current narrowband radio frequency (RF) indoor navigation systems cannot satisfy the challenging demands for most indoor applications. The RF ultra wideband (UWB) system is a promising technology for indoor localisation owing to its high bandwidth that permits mitigation of the multipath identification problem. This work proposes a novel UWB navigation system that permits accurate mobile robot (MR) navigation in indoor environments. The navigation system is composed of two sub-systems: the localisation system and the MR control system. The main contributions of this work are focused on estimation algorithm for localisation, digital implementation of transmitter and receiver and integration of both sub-systems that enable autonomous robot navigation. For sub-systems performance evaluation, statics and dynamics experiments were carried out which demonstrated that the proposed system reached an accuracy that outperforms traditional sensors technologies used in robot navigation, such as odometer and sonar.Fil: Segura M.. Universidad Nacional de San Juan; ArgentinaFil: Mut, Vicente Antonio. Universidad Nacional de San Juan; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Sisterna C.. Universidad Nacional de San Juan; Argentin
Alternaria infectoria species-group associated with black point of wheat in Argentina
Regional surveys are being conducted in Argentina to assess the presence of wheat (Triticum aestivum) pathogens on grains across the main cropping area. During 2001 and 2002, grain samples with a dark brown or blackish discoloration around the embryo end, known as black point, were observed on several cultivars across the wheat region of Buenos Aires Province.Centro de Investigaciones de Fitopatologí
Alternaria infectoria species-group associated with black point of wheat in Argentina
Regional surveys are being conducted in Argentina to assess the presence of wheat (Triticum aestivum) pathogens on grains across the main cropping area. During 2001 and 2002, grain samples with a dark brown or blackish discoloration around the embryo end, known as black point, were observed on several cultivars across the wheat region of Buenos Aires Province.Centro de Investigaciones de Fitopatologí
Blueberry blight caused by Bipolaris cynodontis in Argentina
Blueberry (Vaccinium corymbosum) production in Argentina has grown remarkably in the last 8 years due to the high demand worldwide in the off-season fresh market. Since it is a new crop in Argentina, diseases are just starting to become problematic for farmers. Surveys have been conducted since 2000 to detect new pathogenic associations and to evaluate their distribution, incidence and severity in different blueberry varieties and localities.Facultad de Ciencias Agrarias y Forestale
Blueberry blight caused by Bipolaris cynodontis in Argentina
Blueberry (Vaccinium corymbosum) production in Argentina has grown remarkably in the last 8 years due to the high demand worldwide in the off-season fresh market. Since it is a new crop in Argentina, diseases are just starting to become problematic for farmers. Surveys have been conducted since 2000 to detect new pathogenic associations and to evaluate their distribution, incidence and severity in different blueberry varieties and localities.Facultad de Ciencias Agrarias y Forestale
Cosmology, Oscillating Physics and Oscilllating Biology
According to recent reports there is an excess correlation and an apparent
regularity in the galaxy one-dimensional polar distribution with a
characteristic scale of 128 Mpc. This aparent spatial periodicity can
be naturally explained by a time oscillation of the gravitational constant .
On the other hand, periodic growth features of bivalve and coral fossiles
appear to show a periodic component in the time dependence of the number of
days per year. In this letter we show that a time oscillating gravitational
constant with similar period and amplitude can explain such a feature.Comment: 9 pages. latex using revtex. This revised version is supposed to be
free of e-mail nois
Charge conservation and time-varying speed of light
It has been recently claimed that cosmologies with time dependent speed of
light might solve some of the problems of the standard cosmological scenario,
as well as inflationary scenarios. In this letter we show that most of these
models, when analyzed in a consistent way, lead to large violations of charge
conservation. Thus, they are severly constrained by experiment, including those
where is a power of the scale factor and those whose source term is the
trace of the energy-momentum tensor. In addition, early Universe scenarios with
a sudden change of related to baryogenesis are discarded.Comment: 4 page
Galactic periodicity and the oscillating G model
We consider the model involving the oscillation of the effective
gravitational constant that has been put forward in an attempt to reconcile the
observed periodicity in the galaxy number distribution with the standard
cosmological models. This model involves a highly nonlinear dynamics which we
analyze numerically. We carry out a detailed study of the bound that
nucleosynthesis imposes on this model. The analysis shows that for any assumed
value for (the total energy density) one can fix the value of
(the baryonic energy density) in such a way as to
accommodate the observational constraints coming from the
primordial abundance. In particular, if we impose the inflationary value
the resulting baryonic energy density turns out to be . This result lies in the very narrow range allowed by the observed values of the primordial
abundances of the other light elements. The remaining fraction of
corresponds to dark matter represented by a scalar field.Comment: Latex file 29 pages with no figures. Please contact M.Salgado for
figures. A more careful study of the model appears in gr-qc/960603
Alternaria infectoria species-group associated with black point of wheat in Argentina
Regional surveys are being conducted in Argentina to assess the presence of wheat (Triticum aestivum) pathogens on grains across the main cropping area. During 2001 and 2002, grain samples with a dark brown or blackish discoloration around the embryo end, known as black point, were observed on several cultivars across the wheat region of Buenos Aires Province.Centro de Investigaciones de Fitopatologí
Energy production in varying {\alpha} theories
Aims. On the basis the theoretical model proposed by Bekenstein for
{\alpha}'s variation, we analyze the equations that describe the energy
exchange between matter and both the electromagnetic and the scalar fields.
Methods. We determine how the energy flow of the material is modified by the
presence of a scalar field. We estimate the total magnetic energy of matter
from the "sum rules techniques". We compare the results with data obtained from
the thermal evolution of the Earth and other planets. Results. We obtain
stringent upper limits to the variations in {\alpha} that are comparable with
those obtained from atomic clock frequency variations. Conclusions. Our
constraints imply that the fundamental length scale of Bekenstein's theory "lB"
cannot be larger than Planck's length "lP"